佐藤 幸治 | ![]() |
サトウ コウジ | |
大学院人間発達環境学研究科 人間発達専攻 | |
准教授 | |
自然科学関係 |
2019年 公益財団法人日本スポーツ協会, 秩父宮スポーツ医・科学賞 奨励賞
2014年07月 日本運動生理学会, 若手研究奨励賞, 学会
日本国国内学会・会議・シンポジウム等の賞
2013年 ヤマハ発動機, 特別チャレンジャー賞, 研究助成者
日本国出版社・新聞社・財団等の賞
2010年08月 American Physiological Society, Travel Award
アメリカ合衆国国際学会・会議・シンポジウム等の賞
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研究論文(学術雑誌)
OBJECTIVE: Sulforaphane is a phytochemical that is commonly found in broccoli and broccoli sprouts. However, whether chronic sulforaphane ingestion suppresses heavy resistance exercise-induced muscle damage parameters in humans remains unknown. Therefore, this study investigated the effects of oral chronic sulforaphane ingestion on heavy resistance exercise-induced muscle damage parameters. METHODS: The study had a randomized, double-blind, placebo-controlled, cross-over design. Ten healthy young men (age: 22.0 ± 0.3 y; body weight: 62.6 ± 2.4 kg; height: 171.0 ± 0.1 cm) were administered placebo or sulforaphane (30 mg/d) for 4 wk at the first trial, then after a 4-wk washout period, the participants were administered the opposite treatment for 4 wk at the second trial. The participants were subjected to heavy resistance exercise (bench press, 85% of one-repetition maximum for three times with eight repetitions) after each administration, and blood samples were collected before and at 30 min and 24 h after each exercise session. RESULTS: In this study, 4 wk of sulforaphane intake decreased plasma levels of creatine kinase, especially creatine kinase levels from 30 min to 24 h and baseline to 24 h. Moreover, the change in interleukin-6 levels significantly decreased from baseline to 30 min on prolonged intake of sulforaphane. CONCLUSIONS: Together, these findings suggest that the oral chronic intake of sulforaphane suppressed the heavy resistance exercise-induced increase in muscle damage parameter and expression of inflammatory cytokines. The chronic use of sulforaphane may be a novel therapeutic candidate for the prevention of muscle damage in athletes training daily with high-intensity exercise.
2021年04月07日, Nutrition (Burbank, Los Angeles County, Calif.), 90, 111266 - 111266, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
Substantial evidence has linked dehydroepiandrosterone (DHEA) levels to the anti-obesity and anti-diabetic effects of exercise. While 5'-adenosine monophosphate-activated protein kinase (AMPK) is a negative regulator of adipocyte differentiation and lipid accumulation, activation of mammalian target of rapamycin complex 1 (mTORC1), which is inhibited by AMPK, is required for adipocyte differentiation and positively regulates lipid accumulation. DHEA treatment activates the AMPK pathway in C2C12 myotubes. Hence, DHEA addition to preadipocytes and adipocytes might activate AMPK and inhibit mTORC1, resulting in the inhibition of adipogenesis and lipid accumulation. Therefore, we investigated the effect of DHEA on the AMPK pathway, mTORC1 activity, adipocyte differentiation, and lipid accumulation in 3T3-L1 cells. DHEA suppressed lipid accumulation and adipogenic marker expression during differentiation. It also activated AMPK signaling in preadipocytes and adipocytes and suppressed mTORC1 activity during differentiation. These results suggest that the activation of the AMPK pathway and inhibition of mTORC1 activity may mediate the anti-obesity effect of DHEA, providing novel molecular-level insights into its physiological functions.
Elsevier BV, 2020年06月, Biochemical and Biophysical Research Communications, 528 (3), 614 - 620, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
There is little consensus regarding the impacts of physical activity and nutrient intake on bone mineral density (BMD) in subjects with high or low levels of arterial stiffness. This study was performed to investigate whether physical activity and nutrient intake are associated with BMD in middle-aged women with high levels of arterial stiffness. The study population consisted of middle-aged women aged 40-64 years (n = 22). BMD was assessed by dual-energy X-ray absorptiometry. Carotid-femoral pulse wave velocity (cf-PWV) was used as an indicator of arterial stiffness. Subjects were divided into two groups by median cf-PWV. Physical activity in free-living conditions was evaluated using a triaxial accelerometer. Nutrient intake was also measured using the brief-type self-administered diet history questionnaire. In the High-PWV group, BMD showed a significant negative correlation with age. Using a partial correlation model, BMD was associated with the number of steps and unsaturated fatty acid intake in the High-PWV group. These results suggest that BMD in middle-aged women with high levels of arterial stiffness may be associated with both the number of steps and nutritional intake. Recommendations of physical activity and nutritional intake for the prevention of osteopenia should include consideration of arterial stiffness.
2020年03月03日, International journal of environmental research and public health, 17 (5), 英語, 国際誌[査読有り]
研究論文(学術雑誌)
This study examined whether satisfaction with social interactions and the number of people interacted with during walking groups is associated with affective responses among older adults. Twenty-six older adults were asked to participate in five walking group sessions. The participants walked together for 40-50 min. In every session, the participants reported their affective responses to walking (positive engagement, tranquility, and negative affect), their level of satisfaction with the social interactions experienced, and the number of people interacted with during the walk. The available data were from 107 person-sessions. Multilevel models revealed that, although a higher number of people interacted with was not significantly associated with improvements in any affective responses, higher satisfaction with the interactions was significantly associated with improvements in positive engagement at both the within- and between-person levels. This study found that higher satisfaction with the interactions was associated with desirable affective responses among older adults.
2019年11月17日, Journal of aging and physical activity, 1 - 7, 英語, 国際誌[査読有り]
NEW FINDINGS: What is the central question of this study? Type 2 diabetes mellitus (T2DM) causes skeletal muscle atrophy; does it affect resistance training (RT)-mediated molecular adaptations and subsequent muscle hypertrophy? What is the main finding and its importance? Although skeletal muscle mass and regulation were not preserved under conditions of T2DM, the response of RT-induced skeletal muscle hypertrophy was not impaired in T2DM rat skeletal muscle. These findings suggest that the capacity of RT-mediated muscle mass gain is not diminished in the T2DM condition. ABSTRACT: Type 2 diabetes mellitus (T2DM) is known to cause skeletal muscle atrophy. However, it is not known whether T2DM affects resistance training (RT)-mediated molecular adaptations and subsequent muscle hypertrophy. Therefore, we investigated the effect of T2DM on response of skeletal muscle hypertrophy to chronic RT using a rat resistance exercise mimetic model. T2DM and healthy control rats were subjected to 18 bouts (3 times per week) of chronic RT on unilateral lower legs. RT significantly increased gastrocnemius muscle mass and myonuclei in both T2DM and healthy control rats to the same extent, even though T2DM caused muscle atrophy in the resting condition. Further, T2DM significantly reduced mechanistic target of rapamycin complex 1 (mTORC1) activity (phosphorylation of p70S6KThr389 and 4E-BP1Thr37/46 ) to insulin stimulation and the number of myonuclei in the untrained basal condition, but RT-mediated adaptations were not affected by T2DM. These findings suggested that although the skeletal muscle mass and regulation were not preserved under basal conditions of T2DM, the response of RT-induced skeletal muscle hypertrophy was not impaired in T2DM rat skeletal muscle.
2019年10月, Experimental physiology, 104 (10), 1518 - 1531, 英語, 国際誌[査読有り]
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研究論文(学術雑誌)
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研究論文(学術雑誌)
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研究論文(学術雑誌)
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研究論文(学術雑誌)
Dehydroepiandrosterone (DHEA) is a precursor of sex steroid hormones and is converted to testosterone and estradiol. Normally, androgens and estrogens produced adrenal cortex, testis, and ovary; however, recent studies revealed androgens and estrogens are synthesized by peripheral tissues such as brain, skin, liver, kidney, bone, etc. We found skeletal muscles are also capable of synthesizing androgens and estrogens from DHEA. Circulating DHEA provides substrates required for conversion into potent androgens and estrogens in peripheral tissues. Sex steroid hormone administration has important roles: one is that the enhancement of protein synthesis and anabolism, resulting in muscle growth and increased muscle strength. The other is improvement of hyperglycemia through the activation of glucose signaling pathway in skeletal muscle as well as acceleration of muscle lipid metabolism that increase peroxisome proliferator-activated receptor alpha (PPARα) and PPAR delta (PPARδ). We introduce the effect of DHEA and sex steroid hormones administration on muscle glucose and lipid metabolisms as well as the effect of sex steroid hormone on the muscle hypertrophy.
2018年, Vitamins and hormones, 108, 205 - 221, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
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研究論文(学術雑誌)
Insulin stimulates skeletal muscle glucose uptake via activation of the protein kinase B/Akt (Akt) pathway. Recent studies suggest that insulin downregulates AMP-activated protein kinase (AMPK) activity via Ser485/491 phosphorylation of the AMPK alpha-subunit. Thus lower blood insulin concentrations may induce AMPK signal activation. Acute exercise is one method to stimulate AMPK activation; however, no study has examined the relationship between blood insulin levels and acute resistance exercise-induced AMPK pathway activation. Based on previous findings, we hypothesized that the acute resistance exercise-induced AMPK pathway activation would be augmented by disruptions in insulin secretion through a decrease in AMPK alpha Ser485/491 inhibitory phosphorylation. To test the hypothesis, 10-wk-old male Sprague-Dawley rats were administered the toxin streptozotocin (STZ; 55 mg/kg) to destroy the insulin secreting beta-cells. Three days postinjection, the right gastrocnemius muscle from STZ and control rats was subjected to resistance exercise by percutaneous electrical stimulation. Animals were killed 0, 1, or 3 h later; activation of the Akt/AMPK and downstream pathways in the muscle tissue was analyzed by Western blotting and real-time PCR. Notably, STZ rats showed a significant decrease in basal Akt and AMPK alpha Ser485/491 phosphorylation, but substantial exercise-induced increases in both AMPK alpha Thr172 and acetyl-CoA carboxylase (ACC) Ser79 phosphorylation were observed. Although no significant impact on resistance exercise-induced Akt pathway activation or glucose uptake was found, resistance exercise-induced peroxisome proliferator-activated receptor (PPAR)-gamma coactivator-1 alpha (PGC-1 alpha) gene expression was augmented by STZ treatment. Collectively, these data suggest that circulating insulin levels may regulate acute resistance exercise-induced AMPK pathway activation and AMPK-dependent gene expression relating to basal AMPK alpha Ser485/491 phosphorylation.
American Physiological Society, 2017年08月, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 313 (2), R110 - R119, 英語[査読有り]
研究論文(学術雑誌)
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研究論文(学術雑誌)
Previous studies have demonstrated that an acute bout of aerobic exercise induces a subsequent delayed onset of hypoglycemia among patients with type 1 diabetes. However, the mechanisms of exercise-induced hypoglycemia in type 1 diabetes are still unclear. Streptozotocin (STZ) was injected to 6-week-old male Wistar rats, and three days after STZ injection, animals were randomly assigned into 2 groups: STZ with insulin only (STZ) and STZ with insulin and exercise (STZ+EX). Normal Wistar rats with exercise were used as control (CON+EX). Insulin was intraperitoneally injected (0.5 U/kg) to both STZ groups (-0.5 h), and a bout of aerobic exercise (15 m/min for 30 min) was conducted at euglycemic conditions (0 h). Blood was collected at 0, 1, 3, and 5 h after exercise from the carotid artery. While the blood glucose level was stable during the post-exercise period (0-5 h) in the STZ and CON+EX groups, it decreased significantly only in the STZ+EX group at 3 h. Plasma glucagon, adrenalin, and noradrenalin levels significantly increased at 1 h in the STZ group, whereas significant hormonal responses were observed at 5 h in the STZ+EX group. In skeletal muscle glucose metabolism-related pathway, the level of glucose transporter-4 (GLUT-4) translocation was significantly higher at 1 h in the CON and STZ groups. However, in the STZ+EX group, these activations were maintained by 5 h, indicating a sustained glucose metabolism in the STZ+EX group. A single bout of aerobic exercise induced a delayed onset of hypoglycemia in STZ-treated rats. A prolonged enhancement of GLUT-4 translocation and delayed counter-regulatory hormone responses may have contributed to the induction of hypoglycemia.
PUBLIC LIBRARY SCIENCE, 2017年06月, PLOS ONE, 12 (6), 英語[査読有り]
研究論文(学術雑誌)
Background: Age-related reduction in bone mineral density (BMD) is generally accelerated in women after menopause, and could be even more pronounced in individuals with sarcopenia. Light-load power training with a low number of repetitions would increase BMD, significantly reducing bone loss in individuals at risk of osteoporosis. This study investigated the effects of low-repetition, light-load power training on BMD in Japanese postmenopausal women with sarcopenia. Methods: The training group (n = 7) followed a progressive power training protocol that increased the load with a weighted vest, for two sessions per week, over the course of 6 weeks. The training exercise comprised five kinds of exercises (squats, front lunges, side lunges, calf raises, and toe raises), and each exercise contained eight sets of three repetitions with a 15-s rest between each set. The control group (n = 8) did not undergo any training intervention. We measured BMD, muscle strength, and anthropometric data. Results: Within-group changes in pelvis BMD and knee extensor strength were significantly greater in the training group than the control group (p = 0.029 and 0.030 for pelvis BMD and knee extensor strength, respectively). After low-repetition, light-load power training, we noted improvements in pelvis BMD (1.6%) and knee extensor strength (15.5%). No significant within-or between-group differences were observed for anthropometric data or forearm BMD. Conclusions: Six weeks of low-repetition, light-load power training improved pelvis BMD and knee extensor strength in postmenopausal women with sarcopenia. Since this training program does not require high-load exercise and is therefore easily implementable as daily exercise, it could be an effective form of exercise for sedentary adults at risk for osteoporosis who are fearful of heavy loads and/or training that could cause fatigue.
BIOMED CENTRAL LTD, 2017年05月, BMC GERIATRICS, 17 (1), 102, 英語[査読有り]
研究論文(学術雑誌)
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研究論文(学術雑誌)
The effects of chronic Dioscorea esculenta administration and exercise training on muscle sex steroid hormone levels and insulin resistance in type 2 diabetes rats was assessed. Twenty-week-old male Otsuka Long Evans Tokushima Fatty (OLETF) rats were assigned randomly to the control, D. esculenta treatment, D. esculenta with 5-reductase inhibitor treatment, or the exercise training groups (running at 25 m/min for 1 h, 5 d/wk; n = 10 each group). Eight weeks of D. esculenta treatment or exercise training significantly attenuated the increase in plasma insulin and fasting glucose levels. Plasma and muscle concentrations of dehydroepiandrosterone and 5-dihydrotestosterone (DHT) and the expression of 5-reductase increased significantly in the D. esculenta-treated and exercise training groups, and both treatments led to the upregulation of glucose transporter-4 translocation with concomitant increases in PKB and PKC-/ phosphorylation. Furthermore, the glucose metabolic clearance rate, which represents insulin sensitivity, increased significantly in both the D. esculenta-treated and exercise training groups. These effects were suppressed by administration of the DHT synthetic inhibitor. Together, these findings suggest that the D. esculenta-induced increase in muscle sex steroid hormone levels helps decrease insulin resistance in type 2 diabetes.
FEDERATION AMER SOC EXP BIOL, 2017年02月, FASEB JOURNAL, 31 (2), 793 - 801, 英語[査読有り]
研究論文(学術雑誌)
Dietary protein intake is critical for maintaining an optimal muscle mass, especially among older individuals. Although protein supplementation during resistance training (RT) has been shown to further augment training-induced muscle mass in older individuals, the impact of daily variations in protein intake on training-induced muscle mass has not been explored thus far. Therefore, this study aimed to investigate the relationship between the dietary protein and amino acid intake and RT-induced muscle hypertrophy among older individuals. Ten healthy older men (n=10 mean age56±62 y body weight (BW)=61.5±2.2 kg height=1.65±0.02 m) participated in progressive RT performed 3 times/wk for 12 wk. Body composition (using DXA) and nutritional assessments (using a 3-d dietary record) were performed before and after the training period. Leg lean mass (LLM) increased significantly (15.0±0.8 vs. 15.4±0.8 kg, p< 0.05) after RT, with no change in dietary nutrient intake. The average dietary protein intake was 1.62±0.11 g/kg BW/d, while essential amino acids was 600±51 mg/kg BW/d. Although the correlation between the increase in LLM and dietary protein intake was not significant, a significant correlation was found between the increase in LLM and dietary essential amino acid (EAA) intake. Furthermore, there were significant correlations between the increase in LLM and protein as well as EAA (especially leucine) intake at breakfast among subjects with suboptimal protein intake (p< 0.05). Our study findings indicate that dietary protein as well as EAA intake may be significant contributing factors in muscle hypertrophic response during RT among healthy older men.
Center for Academic Publications Japan, 2017年, Journal of Nutritional Science and Vitaminology, 63 (6), 379 - 388, 英語[査読有り]
研究論文(学術雑誌)
Regular resistance exercise induces skeletal muscle hypertrophy and improvement of glycemic control in type 2 diabetes patients. Administration of dehydroepiandrosterone (DHEA), a sex steroid hormone precursor, increases 5 alpha-dihydrotestosterone (DHT) synthesis and is associated with improvements in fasting blood glucose level and skeletal muscle hypertrophy. Therefore, the aim of this study was to investigate whether increase in muscle DHT levels, induced by chronic resistance exercise, can contribute to skeletal muscle hypertrophy and concomitant improvement of muscular glucose metabolism in type 2 diabetic rats. Male 20-week-old type 2 diabetic rats (OLETF) were randomly divided into 3 groups: sedentary control, resistance training (3 times a week on alternate days for 8 weeks), or resistance training with continuous infusion of a 5 alpha-reductase inhibitor (n = 8 each group). Age-matched, healthy nondiabetic Long-Evans Tokushima Otsuka (LETO) rats (n = 8) were used as controls. The results indicated that OLETF rats showed significant decrease in muscular DHEA, free testosterone, DHT levels, and protein expression of steroidogenic enzymes, with loss of skeletal muscle mass and hyperglycemia, compared to that of LETO rats. However, 8-week resistance training in OLETF rats significantly increased the levels of muscle sex steroid hormones and protein expression of steroidogenic enzymes with a concomitant increase in skeletal muscle mass, improved fasting glucose level, and insulin sensitivity index. Moreover, resistance training accelerated glucose transporter-4 (GLUT-4) translocation and protein kinase B and C-zeta/lambda(IA phosphorylation. Administering the 5a-reductase inhibitor in resistance-trained OLETF rats resulted in suppression of the exercise induced effects on skeletal muscle mass, fasting glucose level, insulin sensitivity index, and GLUT-4 signaling, with a decline in muscular DHT levels. These findings suggest that resistance training-induced elevation of muscular DHT levels may contribute to improvement of hyperglycemia and skeletal muscle hypertrophy in type 2 diabetic rats.
PUBLIC LIBRARY SCIENCE, 2016年11月, PLoS One, 11 (11), 英語[査読有り]
研究論文(学術雑誌)
The accumulation of intramyocellular lipid (IMCL) and extramyocellular lipid (EMCL) is associated with arterial stiffness in middle-aged and older adults. Habitual aerobic exercise induces the improvement of arterial stiffness with reduction in fat accumulation. However, the relationship between aerobic exercise-induced changes in muscular lipids and arterial stiffness remains unclear. The purpose of this study was to investigate whether habitual aerobic exercise-induced changes in IMCL and EMCL content would lead to an improvement of arterial stiffness. First, in a cross-sectional study, we investigated whether cardiorespiratory fitness level affects the association between IMCL or EMCL content and arterial stiffness in 60 middle-aged and older subjects (61.0 +/- 1.3 years). Second, in an intervention study, we examined whether aerobic exercise training-induced changes in IMCL and EMCL content are associated with a reduction in arterial stiffness in 18 middle-aged and older subjects (67.0 +/- 1.7 years). In the cross-sectional study, IMCL content was negatively correlated with brachial-ankle pulse wave velocity (baPWV) (r = -0.47, P<0.05), whereas EMCL content was positively correlated with baPWV (r = 0.48, P<0.05) in the low-fitness group, but was not correlated in the high-fitness group. Furthermore, 8-week aerobic exercise training in older adults increased IMCL content and reduced EMCL content. The training-induced change in baPWV was negatively correlated with training-induced changes in IMCL but was positively correlated with training-induced changes in EMCL. These findings suggest that aerobic exercise training-induced changes in IMCL and EMCL content may be related to a reduction in arterial stiffness in middle-aged and older adults.
NATURE PUBLISHING GROUP, 2016年10月, JOURNAL OF HUMAN HYPERTENSION, 30 (10), 606 - 612, 英語[査読有り]
研究論文(学術雑誌)
Objective Habitual stretching exercise increases carotid arterial compliance, and acute stretching exercise increases arterial compliance in patients with myocardial infarction. However, it is not known whether this arterial adaptation is sustained after exercise. The aim of this study was to examine the effect of a single bout of stretching exercise on the time course of systemic, central, and peripheral arterial stiffness in healthy young subjects. Design Twenty-six healthy young men performed static stretching exercise involving the entire body (trunk, upper limb, and lower limb) for 40 mins. Pulse-wave velocity (PWV; an index of arterial stiffness), blood pressure, and heart rate were measured before and 0, 15, 30, and 60 mins after stretching exercise. Results Femoral-ankle PWV and brachial-ankle PWV were reduced relative to baseline 15 and 30 mins after acute stretching (P < 0.05); however, these arterial responses were not sustained for longer periods, and both PWV values returned to the baseline levels within 60 mins. By contrast, carotid-femoral PWV was unchanged. Conclusion These results suggest that chronic and sufficient repetition of muscle stretch stimulation may result in chronic high arterial compliance, although a single bout of stretch exercise acutely affects arterial compliance.
LIPPINCOTT WILLIAMS & WILKINS, 2016年10月, AMERICAN JOURNAL OF PHYSICAL MEDICINE & REHABILITATION, 95 (10), 764 - 770, 英語[査読有り]
研究論文(学術雑誌)
Regular exercise improves aging-induced deterioration of arterial stiffness, and is associated with elevated production of pentraxin 3 (PTX3) and anti-inflammatory as well as anti-atherosclerotic effects. However, the time-dependent effect of exercise training on arterial stiffness and PTX3 production remains unclear. The purpose of this study was to investigate the time course of the association between the effects of training on the circulating PTX3 level and arterial stiffness in middle-aged and older adults. Thirty-two healthy Japanese subjects (66.2 +/- 1.3 year) were randomly divided into two groups: training (exercise intervention) and sedentary controls. Subjects in the training group completed 8 weeks of aerobic exercise training (60-70% peak oxygen uptake (VO2peak) for 45 min, 3 days per week); during the training period, we evaluated plasma PTX3 concentration and carotid-femoral pulse wave velocity (cfPWV) every 2 wk. cfPWV gradually declined over the 8-week training period, and was significantly reduced after 6 and 8 week of exercise intervention (P < 0.05). Plasma PTX3 level was significantly increased after 4 weeks of the intervention (P < 0.05). In addition, the exercise training-induced reduction in cfPWV was negatively correlated with the percent change in plasma PTX3 level after 6 week (r = -0.54, P < 0.05) and 8 weeks (r = -0.51, P < 0.05) of the intervention, but not correlated at 4 weeks. Plasma PTX3 level was elevated at the early stage of the exercise training intervention, and was subsequently associated with training-induced alteration of arterial stiffness in middle-aged and older adults.
NATURE PUBLISHING GROUP, 2016年09月, JOURNAL OF HUMAN HYPERTENSION, 30 (9), 521 - 526, 英語[査読有り]
研究論文(学術雑誌)
Acute aerobic exercise (AE) is a major physiological stimulus for skeletal muscle glucose uptake through activation of 5′ AMP-activated protein kinase (AMPK). However, the regulation of glucose uptake by acute resistance exercise (RE) remains unclear. To investigate the intracellular regulation of glucose uptake after acute RE versus acute AE, male Sprague–Dawley rats were divided into three groups: RE, AE, or nonexercise control. After fasting for 12�h overnight, the right gastrocnemius muscle in the RE group was exercised at maximum isometric contraction via percutaneous electrical stimulation (3ï¿½× 10�sec, 5 sets). The AE group ran on a treadmill (25�m/min, 60�min). Muscle samples were taken 0, 1, and 3�h after completion of the exercises. AMPK, Ca2+/calmodulin-dependent protein kinase II, and TBC1D1 phosphorylation were increased immediately after both forms of exercise and returned to baseline levels by 3�h. Muscle IGF1 expression was increased by RE but not AE, and maintained until 3�h after RE. Additionally, Akt and AS160 phosphorylation were sustained for 3�h after RE, whereas they returned to baseline levels by 3�h after AE. Similarly, GLUT4 translocation remained elevated 3�h after RE, although it returned to the baseline level by 3�h after AE. Overall, this study showed that AMPK/TBC1D1 and IGF1/Akt/AS160 signaling were enhanced by acute RE, and that GLUT4 translocation after acute RE was more prolonged than after acute AE. These results suggest that acute RE-induced increases in intramuscular IGF1 expression might be a distinct regulator of GLUT4 translocation.
Wiley-Blackwell Publishing Ltd, 2016年08月01日, Physiological Reports, 4 (16), 英語[査読有り]
研究論文(学術雑誌)
Administration of dehydroepiandrosterone (DHEA), a precursor of sex steroid hormones, reduces total and visceral fat mass and elevates adipocytic adiponectin gene expression. The aim of this study is to investigate whether levels of peroxisome proliferator-activated receptors (PPARs) in muscle and transcription of PPAR target genes are affected by long-term DHEA administration or exercise training, and whether altered PPAR levels are associated with circulating adiponectin level in obese rats. After 14 weeks on a high-sucrose diet, obese male Wistar rats were assigned randomly to one of 3 groups: control, DHEA administration (1 mg/kg body weight), or exercise training (treadmill running for 1h, 25m/min, 5 days/week) for 6 weeks (n=7 for each group). Plasma DHEA and total adiponectin levels in the DHEA-treated and exercise-training groups were significantly higher than those in the obese control group. Additionally, DHEA administration and exercise training significantly increased muscular PPAR and PPAR protein levels, with a concomitant increase in mRNA expression of 3-hydroxyacyl-CoA dehydrogenase and cytochrome c oxidase IV, which are target genes of PPAR and PPAR respectively. Moreover, DHEA administration increased these protein and mRNA levels to the same degree as exercise training. Circulating adiponectin level was positively correlated with plasma DHEA and with muscle levels of PPAR and PPAR. These results suggest that in obese rats, secretion of adiponectin due to chronic DHEA administration and exercise training may contribute to an increase in the transcription of genes encoding lipid metabolic enzymes, mediated via elevated expression of PPAR and PPAR in muscle.
GEORG THIEME VERLAG KG, 2016年03月, Horm Metab Res, 48 (3), 207 - 212, 英語[査読有り]
研究論文(学術雑誌)
Previous studies have shown that acute exercise elevates sex steroid hormone concentrations in rodents and that sprint exercise increases circulating testosterone in healthy young men. However, the effect of different exercise intensities on sex steroid hormone responses at different levels of physical fitness is still unclear. In this study, we compared circulating sex steroid hormone responses at different exercise intensities in athletes and non-athletes. Eight male endurance athletes and 11 non-athletes performed two 15 min sessions of submaximal exercise at 40 and 70% peak oxygen uptake (V-O2peak), respectively, and exercised at 90%. V-O2peak until exhaustion. Venous blood samples were collected during the last minute of each submaximal exercise session and immediately after exhaustion. Acute exercise at 40, 70 and 90%. V-O2peak induced significant increases in serum dehydroepiandrosterone (DHEA) and free testosterone concentrations in non-athletes. On the contrary, only 90%. V-O2peak exercise led to an increase in serum DHEA and free testosterone concentrations in athletes. Serum 5 alpha-dihydrotestosterone concentrations increased with 90%. V-O2peak exercise in both athletes and non-athletes. Additionally, serum estradiol concentrations were significantly increased at moderate and high exercise intensities in both athletes and non-athletes. These results indicate that in endurance athletes, serum sex steroid hormone concentrations, especially serum DHEA and 5 alpha-dihydrotestosterone concentrations, increased only with high-intensity exercise, suggesting that different responses of sex steroid hormone secretion are induced by different exercise intensities in individuals with low and high levels of physical fitness. In athletes, therefore, high-intensity exercise may be required to increase circulating sex steroid hormone concentrations.
WILEY-BLACKWELL, 2016年01月, EXPERIMENTAL PHYSIOLOGY, 101 (1), 168 - 175, 英語[査読有り]
研究論文(学術雑誌)
Objectives: Kamishimotsuto (KST) is a supplement containing 13 different herbs including Phellodendron bark, Anemarrhena rhizome and ginseng that have been shown to activate mammalian target of rapamycin complex 1 (mTORC1) and thereby increase muscle protein synthesis in vitro. However, the combined effect of KST and resistance exercise on muscle protein anabolism has not been investigated in vivo. Therefore, the purpose of this study was to investigate the effect of KST supplementation, resistance exercise on (mTORC1) signaling and subsequent muscle protein synthesis. Methods: Male Sprague-Dawley rats were divided into two groups: one group received KST (500 mg/kg/d in water) and the other group received placebo (PLA) for 7 d. After 12 h of fasting, the right gastrocnemius muscle was isometrically exercised via percutaneous electrical stimulation. Muscle samples were analyzed for muscle protein synthesis (MPS) and by western blotting analysis to assess the phosphorylation of p70S6K (Thr389), rpS6 (Ser240/244), and Akt (Ser473 and Thr308). Results: KST supplementation for 7 d significantly increased basal p-Akt (Ser473) levels compared with PLA, phosphorylation of the signaling proteins and MPS at baseline were otherwise unaffected. p-p70S6K and p-rpS6 levels significantly increased 1 h and 3 h after exercise in the PLA group, and these elevations were augmented in the KST group (P < 0.05). Furthermore, MPS at 6 h after resistance exercise was greater in the KST group than in the PLA group (P < 0.05). Conclusions: While resistance exercise alone was able to increase p70S6K and rpS6 phosphorylation, Kamishimotsuto supplementation further augmented resistance exercise-induced muscle protein synthesis through mTORC1 signaling. (C) 2016 Elsevier Inc. All rights reserved.
ELSEVIER SCIENCE INC, 2016年01月, NUTRITION, 32 (1), 108 - 113, 英語[査読有り]
研究論文(学術雑誌)
Sarcopenia has never been diagnosed based on site-specific muscle loss, and little is known about the relationship between site-specific muscle loss and metabolic syndrome (MetS) risk factors. To this end, this cross-sectional study aimed to investigate the relationship between site-specific muscle size and MetS risk factors. Subjects were 38 obese men and women aged 40-82 years. Total body fat and lean body mass were assessed by whole-body dual-energy X-ray absorptiometry (DXA) scan. Muscle thickness (MTH) was measured using B-mode ultrasound scanning in six body regions. Subjects were classified into general obesity (GO) and sarcopenic obesity (SO) groups using the threshold values of one standard deviation below the sex-specific means of either MTH or skeletal muscle index (SMI) measured by DXA. MetS risk score was acquired by standardizing and summing the following continuously distributed variables: visceral fat area, mean blood pressure, HbA1c, and serum triglyceride / high density lipoprotein cholesterol, to obtain the Z-score. Multiple regression analysis revealed that the MetS risk score was independently associated with abdominal MTH in all subjects, but not with MTH in other muscle regions, including the thigh. Although HbA1c and the number of MetS risk factors in the SO group were significantly higher than those in the GO group, there were no significant differences between GO and SO groups as defined by SMI. Ultrasound-derived abdominal MTH would allow a better assessment of sarcopenia in obese patients and can be used as an alternative to the conventionally-used SMI measured by DXA.
PUBLIC LIBRARY SCIENCE, 2015年12月, PLOS ONE, 10 (12), e0143858, 英語[査読有り]
研究論文(学術雑誌)
BACKGROUND Obese and overweight patients are at increased risk of arterial stiffness, and visceral, epicardial and hepatic fat accumulation is associated with cardiovascular disease risk. In general, muscular lipids are stored either in interstitial adipose tissue (extramyocellular lipid (EMCL)) or in lipid droplets within muscle cells (intramyocellular lipid (IMCL)). However, the association between IMCL or EMCL content and arterial stiffness remains unclear. This cross-sectional study aimed to clarify this association. METHODS A total of 237 subjects (18-81 years) were enrolled in this study. The IMCL and EMCL contents of the right vastus lateralis muscle were evaluated by proton magnetic resonance spectroscopy. Arterial stiffness was estimated using brachial-ankle pulse wave velocity (baPWV). RESULTS There were significant correlations between baPWV and the contents of both IMCL (R = -0.23, P < 0.001) and EMCL (R = 0.53, P < 0.001) in all subjects. The baPWV negatively correlated with IMCL content (R = -0.45, P < 0.001) in females only. In contrast, significant positive correlations were observed between baPWV and EMCL content in both males (R = 0.59, P < 0.001) and females (R = 0.55, P < 0.001). IMCL and EMCL contents contributed independently to baPWV variation after adjustment for age, sex, body mass index, visceral and subcutaneous abdominal fat, upper and lower limb fat, blood pressure, heart rate, and lipid profiles. CONCLUSION These results suggest that IMCL and EMCL contents may be a risk factor for arterial stiffness, and this association differed with gender and age.
OXFORD UNIV PRESS, 2015年12月, AMERICAN JOURNAL OF HYPERTENSION, 28 (12), 1473 - 1479, 英語[査読有り]
研究論文(学術雑誌)
Aging-induced arterial stiffening is reduced by aerobic exercise training, and elevated production of nitric oxide (NO) participates in this effect. Adropin is a regulator of endothelial NO synthase and NO release, and circulating adropin level decreases with age. However, the effect of habitual aerobic exercise on circulating adropin levels in healthy middleaged and older adults remains unclear. We sought to determine whether serum adropin level is associated with exercise training-induced changes in arterial stiffness. First, in a cross-sectional study, we investigated the association between serum adropin level and both arterial stiffness and cardiorespiratory fitness in 80 healthy middle-aged and older subjects (65.6 +/- 0.9 yr). Second, in an intervention study, we examined the effects of 8-wk aerobic exercise training on serum adropin level and arterial stiffness in 40 healthy middle-aged and older subjects (67.3 +/- 1.0 yr) divided into two groups: aerobic exercise training and sedentary controls. In the cross-sectional study, serum adropin level was negatively correlated with carotid beta-stiffness (r = -0.437, P < 0.001) and positively correlated with plasma NOx level (r = 0.493, P < 0.001) and cardiorespiratory fitness (r = 0.457, P < 0.001). Serum adropin levels were elevated after the 8-wk aerobic exercise training intervention, and training- induced changes in serum adropin level were correlated with traininginduced changes in carotid beta-stiffness (r = -0.399, P < 0.05) and plasma NOx level (r = 0.623, P < 0.001). Thus the increase in adropin may participate in the exercise-induced reduction of arterial stiffness.
AMER PHYSIOLOGICAL SOC, 2015年11月, AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY, 309 (10), H1642 - H1647, 英語[査読有り]
研究論文(学術雑誌)
Vitamin D and vitamin D receptor (VDR) are involved in the maintenance of skeletal muscle mass and function. Although resistance exercise is well known to enhance muscle growth and improve muscle function, the effect of resistance exercise on VDR has been unclear. We investigated intramuscular VDR expression in response to an acute bout of resistance exercise or endurance exercise. Male adult Sprague-Dawley rats were subjected to either resistance exercise (isometrically exercised via percutaneous electrical stimulation for five sets of ten 3s contractions, with a 7s interval between contractions and 3min rest intervals between sets) or endurance exercise (treadmill at 25mmin(-1) for 60min). Rats were killed immediately or 1, 3, 6 or 24h after completion of the resistance or endurance exercise, and gastrocnemius muscles were removed. Non-exercised control animals were killed in a basal state (control group). Intramuscular VDR expression was significantly higher immediately after resistance exercise and elevated for 3h after exercise compared with the control group (P<0.05), and the resistance exercise significantly increased phosphorylated ERK1/2 and Mnk1 expression (P<0.05), which may be associated with VDR expression, immediately after exercise. Additionally, intramuscular expression of cytochrome P450 27B1, an enzyme related to vitaminD metabolism, was significantly higher at 1 and 3h after exercise (P<0.05) compared with the control group. In contrast, endurance exercise had no effect on any of the measured proteins. Our results indicate that resistance exercise may be an efficient way to increase intramuscular VDR and related enzyme expression.
WILEY-BLACKWELL, 2015年10月, EXPERIMENTAL PHYSIOLOGY, 100 (10), 1168 - 1176, 英語[査読有り]
研究論文(学術雑誌)
Exercise and caloric restriction (CR) have been reported to have anti-ageing, anti-obesity, and health-promoting effects. Both interventions increase the level of dehydroepiandrosterone (DHEA) in muscle and blood, suggesting that DHEA might partially mediate these effects. In addition, it is thought that either 5'-adenosine monophosphate-activated protein kinase (AMPK) or peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1 alpha) mediates the beneficial effects of exercise and CR. However, the effects of DHEA on AMPK activity and PGC-1 alpha expression remain unclear. Therefore, we explored whether DHEA in myotubes acts as an activator of AMPK and increases PGC-1 alpha. DHEA exposure increased glucose uptake but not the phosphorylation levels of Akt and PKC zeta/lambda in C2C12 myotubes. In contrast, the phosphorylation levels of AMPK were elevated by DHEA exposure. Finally, we found that DHEA induced the expression of the genes PGC-1 alpha and GLUT4. Our current results might reveal a previously unrecognized physiological role of DHEA; the activation of AMPK and the induction of PGC-1 alpha by DHEA might mediate its anti-obesity and health-promoting effects in living organisms. (C) 2015 Elsevier Inc. All rights reserved.
ACADEMIC PRESS INC ELSEVIER SCIENCE, 2015年07月, Biochem Biophys Res Commun, 463 (1-2), 42 - 47, 英語[査読有り]
研究論文(学術雑誌)
Aging-induced elevation in C1q secretion activates the Wnt signaling pathway in muscles, leading to the development of muscle fibrosis. However, the association between serum C1q level and muscle mass and strength remains unclear in humans. The aim of the study was to elucidate whether serum C1q level is associated with aging-and resistance training-induced changes in muscle mass and strength. First, in a cross-sectional study, we investigated the association between serum C1q level and muscle mass and strength in 131 healthy subjects, aged 20-81 yr. Second, in an intervention study, we examined the association between the effects of serum C1q level and muscle mass and strength on 12wk resistance training in 11 healthy older adults (60-81 yr). In the cross-sectional study, serum C1q level increased with aging and was negatively correlated with muscle mass and strength. Furthermore, 12 wk resistance training in older adults reduced the age-associated elevation in serum C1q levels. The training effect of serum C1q level significantly correlated with the change in the cross-sectional area of the thigh (r = -0.703; P < 0.01). Serum C1q level may reflect loss of muscle mass; therefore, C1q may be a novel biomarker of sarcopenia.
FEDERATION AMER SOC EXP BIOL, 2015年03月, FASEB JOURNAL, 29 (3), 1003 - 1010, 英語[査読有り]
研究論文(学術雑誌)
To elucidate the effects of endurance training on circulating irisin levels in young and middle-aged/older adults, and to determine the association between endurance training-induced alteration of irisin and reduction in body fat. Twenty-five healthy young (age 21 +/- 1 years; 16 men, 9 women) and 28 healthy middle-aged/older adults (age 67 +/- 8 years; 12 men, 16 women) participated in the study. Each age cohort was divided into two groups: the endurance-training group (14 young, 14 middle-aged/older) and the control group. Subjects in the training groups completed an 8-week endurance-training program (cycling at 60-70% peak oxygen uptake [VO2peak] for 45 min, 3 days/week). Before and after the intervention, we evaluated serum irisin level, VO2peak, and body composition. The increase in VO2peak in the young and middle-aged/older training groups after the intervention period was significantly greater than those in the young and middle-aged/older control groups (P < 0.05). Serum irisin level was significantly increased in the middle-aged/older training group after the intervention period (P < 0.01), but not in the young training group. Furthermore, in the middle-aged/older training group, the endurance training-induced reduction in visceral adipose tissue area was negatively correlated with the change in serum irisin level (r = -0.54, P < 0.05). These results suggest a possible role for secreted irisin in the exercise-induced alteration of abdominal visceral fat in middle-aged and older adults.
PUBLIC LIBRARY SCIENCE, 2015年03月, PLOS ONE, 10 (3), 英語[査読有り]
研究論文(学術雑誌)
Sex steroid hormones are secreted mainly by the ovary and testis and regulate diverse physiological processes in target tissues. Recent studies have shown that sex steroidogenesis-related mRNA and protein expressions, such as for 17 beta-hydroxysteroid dehydrogenase (HSD), 3 beta-HSD, 5 alpha-reductase and aromatase cytochrome P-450 (P450arom) enzymes, are detected in the skeletal muscle, while testosterone, estradiol, and 5 alpha-dihydrotestosterone (DHT) were locally synthesized in skeletal muscle from dehydroepiandrosterone (DHEA). Moreover, in animal and human studies, the sex steroidogenesis enzymes and sex steroid hormone levels in skeletal muscle are upregulated by acute and chronic exercise stimulation. The enhanced muscle sex steroidgenesis is associated with glycemic control via upregulation of muscle glucose transporter-4 (GLUT-4) signaling in obese and diabetic rats and with muscle mass and strength in older men. Thus, an exercise-induced increase of sex steroid hormone in muscle may positively impact age-related concerns such as life-related diseases and sarcopenia. (c) 2014 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, 2015年01月, JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY, 145, 200 - 205, 英語[査読有り][招待有り]
研究論文(学術雑誌)
Objectives. - Low-circulating testosterone is associated with development of type 2 diabetes in obese men. In this study, we examined the effects of experimental overfeeding and weight gain on serum levels of sex hormones and skeletal muscle expression of steroidogenic enzymes in healthy men with (FH+) and without (FH-) a family history of type 2 diabetes. Methods. - Following a 3-day lead in energy balanced diet, FH+ (n = 9) and FH- men (n = 11) were overfed by 5200 kJ/day (45% fat) for 28 days. Body weight, fasting glucose, insulin, sex steroid, sex hormone binding globulin (SHBG) levels, insulin sensitivity (hyperinsulinaemic-euglycaemic clamp) and body fat (DXA) were assessed in all individuals at baseline and day 28, and sex steroidogenesis-related enzyme expression in vastus lateralis biopsies was examined in a subset (n=11). Results. - Body weight, fat mass and fasting insulin levels were increased by overfeeding (P < 0.01) and insulin was increased significantly more in FH+ men (P < 0.01). Serum sex hormone binding globulin (SHBG) and 5 alpha-dihydrotestosterone (DHT) were reduced with overfeeding (P < 0.05), and serum testosterone and DHT were reduced to a greater extent in FH+ men (P < 0.05). Overfeeding reduced mRNA expression of 3 beta-hydroxysteroid dehydrogenase (HSD) and 17 beta HSD (P <= 0.007), independently of group. 5 alpha-Reductase (SRD5A1) mRNA expression was not changed overall, but a time by group interaction was observed (P = 0.04). Conclusion. - Overfeeding reduced SHBG and muscle expression of enzymes involved in the formation of testosterone in skeletal muscle. Men with a family history of T2DM were more susceptible to deleterious outcomes of overfeeding with greater reductions in serum testosterone and DHT and greater increases in markers of insulin resistance, which may contribute to increased risk of developing type 2 diabetes. (C) 2014 Elsevier Masson SAS. All rights reserved.
MASSON EDITEUR, 2014年12月, DIABETES & METABOLISM, 40 (6), 439 - 444, 英語[査読有り]
研究論文(学術雑誌)
Acute dehydroepiandrosterone (DHEA) administration improves hyperglycemia in rats with streptozotocin (STZ)-induced type 1 diabetes mellitus. Diosgenin, a steroid structurally similar to DHEA (dehydroepiandrosterone), is contained highly levels in dioscorea; however, it is still unclear whether this natural product improves hyperglycemia in the type 1 diabetes model rats through an increase muscular GLUT4 signaling. After 1 week of STZ injection, fasting glucose level was measured in blood taken from the tail vein every 30 min for 150 min after injection of diosgenin or dioscorea (3 mg/kg). On another day, muscle was resected 150 min after diosgenin or dioscorea injections. Serum DHEA level increased significantly 120 min after diosgenin or dioscorea injections; concomitantly, blood glucose level decreased significantly. Moreover, GLUT4 translocation, as well as phosphorylation of Akt and PKC zeta/lambda, increased significantly by diosgenin or dioscorea administration. However, these effects of diosgenin and dioscorea were blocked by a 5 alpha-reductase inhibitor that inhibits synthesizing dehydrotestosterone (DHT) from testosterone. Additionally, significant correlations were observed between blood glucose level, GLUT4 translocation level, and muscular sex steroid hormone level 150 min after the administrations. These results suggest that the diosgenin-induced increase in the DHEA level may contribute to the improvement of hyperglycemia by activating the muscular GLUT4 signaling pathway in type 1 diabetes model rats. (C) 2014 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, 2014年09月, JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY, 143, 152 - 159, 英語[査読有り]
研究論文(学術雑誌)
Concurrent training, a combination of endurance (EE) and resistance exercise (RE) performed in succession, may compromise the muscle hypertrophic adaptations induced by RE alone. However, little is known about the molecular signaling interactions underlying the changes in skeletal muscle adaptation during concurrent training. Here, we used an animal model to investigate whether EE before or after RE affects the molecular signaling associated with muscle protein synthesis, specifically the interaction between RE-induced mammalian target of rapamycin complex 1 (mTORC1) signaling and EE-induced AMP-activated protein kinase (AMPK) signaling. Male Sprague-Dawley rats were divided into five groups: an EE group (treadmill, 25 m/min, 60 min), an RE group (maximum isometric contraction via percutaneous electrical stimulation for 3 X 10 s, 5 sets), an EE before RE group, an EE after RE group, and a nonexercise control group. Phosphorylation of p70S6K, a marker of mTORC1 activity, was significantly increased 3 h after RE in both the EE before RE and EE after RE groups, but the increase was smaller in latter. Furthermore, protein synthesis was greatly increased 6 h after RE in the EE before RE group. Increases in the phosphorylation of AMPK and Raptor were observed only in the EE after RE group. Akt and mTOR phosphorylation were increased in both groups, with no between-group differences. Our results suggest that the last bout of exercise dictates the molecular responses and that mTORC1 signaling induced by any prior bout of RE may be downregulated by a subsequent bout of EE.
AMER PHYSIOLOGICAL SOC, 2014年05月, AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM, 306 (10), E1155 - E1162, 英語研究論文(学術雑誌)
Skeletal muscle can synthesize testosterone and 5α-dihydrotestosterone (DHT) from dehydroepiandrosterone (DHEA) via steroidogenic enzymes in vitro, but hormone levels and steroidogenic enzyme expression decline with aging. Resistance exercise has been shown to increase in plasma sex steroid hormone levels. However, it remains unclear whether resistance training can restore impaired steroidogenic enzyme expressions in older individuals. Six young and 13 older men were recruited, and muscle biopsies were taken from the vastus lateralis at basal state. The same group of older subjects underwent resistance training involving knee extension and flexion exercises for 12 wk, and post-training biopsies were performed 4-5 d after the last exercise session. Muscular sex steroid hormone levels and sex steroidgenesis-related enzyme expressions were significantly lower in older subjects than younger ones at baseline, but 12 wk of resistance training significantly restored hormone levels (DHEA: 432±26 at baseline, 682±31 pg/μg protein, DHT: 6.2±0.9 at baseline, 9.8±1.4 pg/μg protein). Furthermore, the steroidogenesis-related enzymes such as 3β-hydroxysteroid dehydrogenase (HSD), 17β-HSD, and 5α-reductase expressions were significantly restored by resistance training. We conclude progressive resistance training restores age-related declines in sex steroidogenic enzyme and muscle sex steroid hormone levels in older men.
2014年04月, FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 28 (4), 1891 - 7, 英語, 国際誌[査読有り]
研究論文(学術雑誌)
Aging-induced deterioration of arterial stiffness is decreased by regular exercise, and increased nitric oxide (NO) production participates in this effect. Apelin regulates endothelial NO synthase in endothelial cells, promoting NO production. However, the effect of aerobic exercise training on circulating apelin levels in healthy middle-aged and older adults remains unknown. Accordingly, this study aimed to clarify the effects of regular aerobic exercise on apelin concentrations in middle-aged and older adults. Thirty-four healthy middle-aged and older subjects (67.0 +/- 1.3 years) were randomly divided into two groups: exercise intervention and sedentary controls. Subjects in the training group completed 8-week of aerobic exercise training (60-70% peak oxygen uptake [VO2peak] for 45 min, 3 days/week). Before and after the intervention, we evaluated plasma apelin and nitrite/nitrate (NOx) concentrations, VO2peak, and arterial stiffness index. In the training group, VO2peak was significantly increased, and carotid beta-stiffness was significantly decreased, after the intervention (P<0.05). Moreover, plasma apelin and NOx levels were significantly increased in the training group after the intervention (P<0.05). Additionally, there was a correlation between the training effects of plasma apelin levels and carotid beta-stiffness (r = -0.508, P = 0.032) and plasma NOx levels (r = 0.494, P = 0.037). By contrast, none of these parameters changed significantly in the control group. These results suggest that the increased in plasma apelin levels may be associated with exercise training-induced alternation of arterial stiffness in middle-aged and older adults.
PUBLIC LIBRARY SCIENCE, 2014年04月, PLOS ONE, 9 (4), 英語[査読有り]
研究論文(学術雑誌)
Recent studies indicate that matrix metalloproteinases (MMPs) and critical linkage proteins in the extracellular matrix (ECM) regulate skeletal muscle mass, although the effects of resistance training (RT) on protein expression and activity are unclear. Thus, the purpose of the present study was to investigate the effects of RT on MMP activity and expression of ECM-related proteins. Ten male Sprague-Dawley rats were randomly assigned to 1 bout (1B) or 18 bouts (18B) of electrical stimulation. The right gastrocnemius muscle was isometrically contracted via percutaneous electrical stimulation (five sets of 5 sec stimulation × five contractions/set with 5 sec interval between contractions and 3 min rest between sets) once (1B) or every other day for 5 weeks (18B). The left leg served as a control. Activity of MMP-2 and MMP-9, determined via gelatin zymography, was increased (P < 0.05) immediately after 1B. However, MMP activation was not evident following 18B. No changes in collagen IV, laminin α2, α7-integrin, or ILK protein expression were detected immediately following 1B or 18B. However, β1-integrin protein expression was significantly increased (P < 0.05) with 18B. Our results suggest that resistance exercise activates MMPs during the initial phase of RT but this response is attenuated with continuation of RT.
American Physiological Society, 2014年, Physiological reports, 2 (11), 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
A recent study identified ursolic acid (UA) as a potent stimulator of muscle protein anabolism via PI3K/Akt signaling, thereby suggesting that UA can increase Akt-independent mTOR complex 1 (mTORC1) activation induced by resistance exercise via Akt signaling. The purpose of the present study was to investigate the effect of UA on resistance exercise-induced mTORC1 activation. The right gastrocnemius muscle of male Sprague-Dawley rats aged 11 wk was isometrically exercised via percutaneous electrical stimulation (stimulating ten 3-s contractions per set for 5 sets), while the left gastrocnemius muscle served as the control. UA or placebo (PLA; corn oil only) was injected intraperitoneally immediately after exercise. The rats were killed 1 or 6 h after the completion of exercise and the target tissues removed immediately. With placebo injection, the phosphorylation of p70(S6K) at Thr(389) increased 1 h after resistance exercise but attenuated to the control levels 6 h after the exercise. On the other hand, the augmented phosphorylation of p70(S6K) was maintained even 6 h after exercise when UA was injected immediately after exercise. A similar trend of prolonged phosphorylation was observed in PRAS40 Thr(246), whereas UA alone or resistance exercise alone did not alter its phosphorylation level at 6 h after intervention. These results indicate that UA is able to sustain resistance exercise-induced mTORC1 activity.
AMER PHYSIOLOGICAL SOC, 2013年09月, AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM, 305 (6), E760 - E765, 英語[査読有り]
研究論文(学術雑誌)
We examined the effects of exercise training on the levels of lipid droplet (LD)-associated and mitochondria-related proteins in diet-induced obese (DIO) rats. Furthermore, we assessed putative factors induced by exercise to activate lipolysis in differentiated 3T3-L1 adipocytes. DIO Wistar male rats (age 20 wk) were divided into sedentary control (SED, n = 7) and exercise training (EX, n = 7) groups. EX animals were subjected to treadmill running (25 m/min, 1 h/day, 5 days/wk) for 6 wk. Epididymal fat was dissected and used for protein analyses. 3T3-L1 adipocytes were incubated with media containing hydrogen peroxide (H2O2), sodium-lactate, caffeine, AICAR, or SNAP (NO donor) for 6 h, or 1 mM H2O2 for 15 min, followed by incubation with normal media for up to 24 h total. Protein expression levels and lipolytic activities were biochemically assayed. Epididymal fat significantly decreased in EX animals compared with SED animals. Levels of cytochrome c oxidase (COx), perilipin, hormone sensitive lipase (HSL), and adipose triglyceride lipase (ATGL) proteins in epididymal fat pads of EX animals were significantly increased compared with those in SED animals. In 3T3-L1 cells, glycerol or fatty acid release was significantly increased by all treatments. Lactate or SNAP significantly increased PGC-1 alpha expression, and H2O2 significantly increased COx protein levels compared with controls. Expression of perilipin, HSL, ATGL, or comparative gene identification (CGI)-58 was significantly increased by all treatments. By increasing lipolytic activity in adipocytes, the exercise-inducible factors are attractive therapeutic effectors against LD-associated metabolic diseases.
AMER PHYSIOLOGICAL SOC, 2013年07月, JOURNAL OF APPLIED PHYSIOLOGY, 115 (2), 260 - 267, 英語[査読有り]
研究論文(学術雑誌)
[査読有り]
研究論文(学術雑誌)
Objective: alpha-Glycerophosphocholine (GPC) is a putative acetylcholine precursor that potentially increases growth hormone secretion through the action of acetylcholine-stimulated catecholamine. The aim of this study was to investigate acute physiologic responses to a single intake of GPC. Methods: Eight healthy male subjects (25 +/- 1 y old) ingested GPC 1000 mg or a placebo in a double-blind randomized crossover study. Fasting blood samples were obtained before the administration of GPC (baseline) and 60 and 120 min after administration. All subjects repeated the identical protocol using the placebo. Results: Plasma free choline levels significantly increased at 60 and 120 min after GPC administration. Plasma growth hormone secretion was increased significantly 60 min after taking GPC, whereas no significant change was observed with the placebo. In addition, the serum free fatty acid was increased 120 min after GPC ingestion, but no changes were seen with the placebo. Moreover, serum acetoacetate and 3-hydroxybutyrate levels, which are indices of hepatic fat oxidation, were increased at 120 min after taking GPC, whereas the placebo had no effect. Conclusion: These findings suggest that a single dose of GPC increases growth hormone secretion and hepatic fat oxidation, with concomitant increases in choline levels, in young adults. (C) 2012 Elsevier Inc. All rights reserved.
ELSEVIER SCIENCE INC, 2012年11月, NUTRITION, 28 (11-12), 1122 - 1126, 英語[査読有り]
研究論文(学術雑誌)
Background: Dehydroepiandrosterone (DHEA) is precursor of sex steroid hormone. We demonstrated that acute DHEA injection to type 1 diabetes model rats induced improvement of hyperglycemia. However, the effect of the combination of DHEA administration and exercise training on insulin resistance is still unclear. This study was undertaken to determine whether 6-weeks of DHEA administration and/or exercise training improve insulin resistance in obese male rats. Methods: After 14 weeks of a high-sucrose diet, obese male Wistar rats were assigned randomly to one of four groups: control, DHEA administration, exercise training, and a combination of DHEA administration and exercise training (n = 10 each group). Results: After 6-weeks of DHEA administration and/or exercise training, rats in the combination group weighed significantly less and had lower serum insulin levels than rats in the other groups. Moreover, the rats treated with DHEA alone or DHEA and exercise had significantly lower fasting glucose levels (combination, 84 +/- 6.5 mg/dL; DHEA, 102 +/- 9.5 mg/dL; control, 148 +/- 10.5 mg/dL). In addition, insulin sensitivity check index showed significant improvements in the combination group (combination, 0.347 +/- 0.11; exercise, 0.337 +/- 0.16%; DHEA, 0.331 +/- 0.14; control, 0.308 +/- 0.12). Muscular DHEA and 5 alpha-dihydrotestosterone (DHT) concentrations were significantly higher in the combination group, and closely correlated with the quantitative insulin-sensitivity check index (DHEA: r = 0.71, p < 0.01; DHT: r = 0.69, p < 0.01). Conclusion: These results showed that a combination of DHEA administration and exercise training effectively improved fasting blood glucose and insulin levels, and insulin sensitivity, which may reflect increased muscular DHEA and DHT concentrations.
BIOMED CENTRAL LTD, 2012年05月, NUTRITION & METABOLISM, 9, 英語[査読有り]
研究論文(学術雑誌)
It is not known whether local androgen metabolism is involved in the mechanisms underlying the dehydroepiandrosterone (DHEA) administration-induced improvement of bone mineral density (BMD) in an estrogen-deficiency state. The aim of the present study was to clarify whether DHEA administration would improve local androgen metabolism and BMD in cancellous site of tibia of ovariectomized (OVX) rats. Twenty-two female rats, 6 weeks old, were randomized into three groups: sham-operated rats, OVX control rats, and OVX rats that received DHEA treatment. DHEA was administered intraperitoneally at 20 mg/kg body weight for 8 weeks. The concentrations of free testosterone and dihydrotestosterone (DHT) in cancellous site of tibia did not change as a result of ovariectomy, while the DHT concentration increased following DHEA administration. We revealed that DHEA administration improved the reduction of 17 beta- and 3 beta-hydroxysteroid dehydrogenases and clearly reversed the reduction of 5 alpha-reductase types 1 and 2 and androgen receptor in the cancellous site of tibia of OVX rats. DHEA administration suppressed estrogen deficiency relative to the decrease in the cancellous BMD, which was positively associated with local DHT concentration. These findings indicate that DHEA administration enhances local bioactive androgen metabolism in the cancellous tibia of young OVX rats, suggesting that local DHT may play a part in the DHEA administration-induced improvement of cancellous BMD.
SPRINGER, 2011年08月, CALCIFIED TISSUE INTERNATIONAL, 89 (2), 105 - 110, 英語[査読有り]
研究論文(学術雑誌)
Sato K, Iemitsu M, Aizawa K, Mesaki N, Fujita S. Increased muscular dehydroepiandrosterone levels are associated with improved hyperglycemia in obese rats. Am J Physiol Endocrinol Metab 301: E274-E280, 2011. First published February 1, 2011; doi:10.1152/ajpendo.00564.2010.-This study was undertaken to assess the effects of dehydroepiandrosterone (DHEA) administration and exercise training on muscular DHEA and 5 alpha-dihydrotestosterone (DHT) levels and hyperglycemia in diet-induced obese and hyperglycemic rats. After 14 wk of a high-sucrose diet, obese male Wistar rats were assigned randomly to one of three 6-wk regimens: control, DHEA treatment, or exercise training (running at 25 m/min for 1 h, 5 days/wk; n = 10 each group). Results indicate that either 6 wk of DHEA treatment or exercise training significantly attenuated serum insulin and fasting glucose levels compared with the control group. Plasma and muscle concentrations of DHEA and DHT and expression levels of 5 alpha-reductase were significantly higher in the DHEA-treated and exercise-training groups. Moreover, both DHEA administration and exercise training upregulated GLUT4 translocation with concomitant increases in protein kinase B and protein kinase C zeta/lambda phosphorylation. Muscle DHEA and DHT concentrations closely correlated with blood glucose levels (DHEA treatment: r = -0.68, P < 0.001; exercise training: r = -0.65, P < 0.001), serum insulin levels, and activation of the GLUT4-regulated signaling pathway. Thus, increased levels of muscle sex steroids may contribute to improved fasting glucose levels via upregulation of GLUT4-regulated signaling in diet-induced obesity and hyperglycemia.
AMER PHYSIOLOGICAL SOC, 2011年08月, AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM, 301 (2), E274 - E280, 英語[査読有り]
研究論文(学術雑誌)
Objective: Aerobic exercise on land decreases arterial stiffness, however, the effect of exercise in water on arterial stiffness has not been clear. This study investigated the effect of a 15-mm cycling exercise on land and that in water on pulse wave velocity (PWV) as an index of arterial stiffness. Methods: Nine healthy young men were randomly performed exercise on land and exercise in water equivalent to 50% of each maximum oxygen uptake on separate days. The PWV from carotid to femoral artery (aortic PWV) and femoral to posterior tibial artery (leg PWV) were measured at baseline and 15, 30, 60 min after exercise. Results: The heart rate in water was significantly lower during exercise than that on land. In addition, the carbon dioxide output and respiratory exchange ratio during exercise were significantly greater in water. Body temperature increased after the exercise on land but decreased after the exercise in water. Although the aortic PWV and leg PWV decreased concomitantly with decrease in SBP and DBP after the exercise on land, there were no significant changes after the exercise in water. Conclusion: Although acute exercise on land decreased arterial stiffness after exercise, acute exercise in water of the same exercise load did not. The differences in body temperature and blood pressure after exercise may result in diverse arterial stiffness after exercise. (Jpn. J. Phys. Fitness Sports Med., 60 (3) : 269 similar to 277 (2011))
JAPANESE SOC PHYSICAL FITNESS SPORTS MEDICINE, 2011年06月, JAPANESE JOURNAL OF PHYSICAL FITNESS AND SPORTS MEDICINE, 60 (3), 269 - 277, 日本語[査読有り]
研究論文(学術雑誌)
Objective: Aerobic exercise on land decreases arterial stiffness? however? the effect of exercise in water on arterial stiffness has not been clear. This study investigated the effect of a 15- min cycling exercise on land and that in water on pulse wave velocity (PWV) as an index of arterial stiffness. Methods: Nine healthy young men were randomly performed exercise on land and exercise in water equivalent to 50% of each maximum oxygen uptake on separate days. The PWV from carotid to femoral artery (aortic PWV) and femoral to posterior tibial artery (leg PWV) were measured at baseline and 15? 30? 60 min after exercise. Results: The heart rate in water was significantly lower during exercise than that on land. In addition? the carbon dioxide output and respiratory exchange ratio during exercise were significantly greater in water. Body temperature increased after the exercise on land but decreased after the exercise in water. Although the aortic PWV and leg PWV decreased concomitantly with decrease in SBP and DBP after the exercise on land? there were no significant changes after the exercise in water. Conclusion: Although acute exercise on land decreased arterial stiffness after exercise? acute exercise in water of the same exercise load did not. The differences in body temperature and blood pressure after exercise may result in diverse arterial stiffness after exercise.
Japanese Society of Physical Fitness and Sports Medicine, 2011年, 体力科学, 60 (3), 269 - 277, 日本語[査読有り]
研究論文(学術雑誌)
Ogoh S, Sato K, Akimoto T, Oue A, Hirasawa A, Sadamoto T. Dynamic cerebral autoregulation during and after handgrip exercise in humans. J Appl Physiol 108: 1701-1705, 2010. First published April 8, 2010; doi:10.1152/japplphysiol. 01031.2009.-The purpose of the present study was to examine the effect of static exercise on dynamic cerebral autoregulation (CA). In nine healthy subjects at rest before, during, and after static handgrip exercise at 30% maximum voluntary contraction, the response to an acute drop in mean arterial blood pressure and middle cerebral artery mean blood velocity was examined. Acute hypotension was induced nonpharmacologically via rapid release of bilateral thigh occlusion cuffs. Subjects were instructed to avoid executing a Valsalva maneuver during handgrip. To quantify dynamic CA, the rate of regulation ( RoR) was calculated from the change in cerebral vascular conductance index during the transient fall in blood pressure. There was no significant difference in RoR between rest (mean +/- SE; 0.278 +/- 0.052/s), exercise (0.333 +/- 0.053/s), and recovery (0.305 +/- 0.059/s) conditions (P +/- 0.747). In addition, there was no significant difference in the rate of absolute cerebral vasodilatory response to acute hypotension between three conditions (P = 0.737). This finding indicates that static exercise and related elevations in blood pressure do not alter dynamic CA.
AMER PHYSIOLOGICAL SOC, 2010年06月, JOURNAL OF APPLIED PHYSIOLOGY, 108 (6), 1701 - 1705, 英語[査読有り]
研究論文(学術雑誌)
Androgens, Such as testosterone, play important roles in regulation of diverse physiological process of target tissues. Recently, we reported that steroidogenic enzymes exist in skeletal Muscle and regulate local production of testosterone in response to exercise. Testosterone is transformed into a bioactive androgen metabolite, dihydrotestosterone (DHT) by 5 alpha-reductase. However, it is unclear whether exercise stimulates local bioactive androgen metabolism in the skeletal muscle in both sexes. In the present study, we examined sex differences in the levels of dehydroepiandrosterone (DHEA), free testosterone, DHT, and steroidogenesis-related enzymes 5 alpha-reductase and androgen receptor (AR) in rat's skeletal muscle before and after a single bout of exercise. Basal muscular free testosterone and DHT levels were higher in males than females, whereas the levels of DHEA did not differ between the sexes. Muscular DHEA, free testosterone, and DHT levels were increased in both sexes after the exercise. There were no differences of 5 alpha-reductase and AR transcripts and proteins between the sexes, and the expression of 5 alpha-reductase was significantly increased in both sexes after the exercise. Finally, the expression of AR was significantly higher in female rats, but not in males after the exercise. These data Suggest that acute exercise enhances the local bioactive androgen metabolism in the skeletal Muscle of both sexes. (C) 2009 Elsevier Inc. All rights reserved.
ELSEVIER SCIENCE INC, 2010年03月, STEROIDS, 75 (3), 219 - 223, 英語[査読有り]
研究論文(学術雑誌)
Aim: Addition of dehydroepiandrosterone (DHEA) to a cultured skeletal muscle locally synthesizes 5 alpha-dihydrotestosterone (DHT). It induced activation of glucose metabolism-related signalling pathway via protein kinase B (Akt) and protein kinase C zeta/lambda (PKC zeta/lambda)-glucose transporter-4 (GLUT4) proteins. However, such an effect of DHEA in vivo remains unclear. Methods: Using streptozotocin (STZ)-induced rats with type 1 diabetes mellitus, we tested the hypothesis that a single bout of DHEA injection in the rats improves hyperglycaemia and muscle GLUT4-regulated signalling pathway. After 1 week of STZ injection (55 mg kg-1) with male Wistar rats, fasting glucose concentrations were determined in a blood sample taken from the tail vein. Blood glucose levels were then monitored for 180 min after DHEA or sesame oil (control) was injected (n = 10 for each group). Results: Blood glucose levels decreased significantly for 30-150 min after 2 mg DHEA injection in the STZ rats. In the skeletal muscle, expression and translocation of GLUT4 protein, phosphorylation of Akt and PKC zeta/lambda, and phosphofructokinase and hexokinase enzyme activities increased significantly by DHEA injection. However, DHEA-induced improvements in Akt and PKC zeta/lambda-GLUT4 pathways were blocked by a DHT inhibitor. Conclusion: These results suggest that a single bout of DHEA injection can improve hyperglycaemia and activate the glucose metabolism-related signalling pathway via Akt and PKC zeta/lambda-GLUT4 proteins of skeletal muscles in rats. Moreover, these results show that a DHEA-induced increase in muscle glucose uptake and utilization might contribute to improvement in hyperglycaemia in type 1 diabetes mellitus.
WILEY-BLACKWELL PUBLISHING, INC, 2009年11月, Acta Physiologica (oxf), 197 (3), 217 - 225, 英語[査読有り]
研究論文(学術雑誌)
Circulating dehydroepiandrosterone (DHEA) is converted to testosterone or estrogen in the target tissues. Recently, we demonstrated that skeletal muscles are capable of locally synthesizing circulating DHEA to testosterone and estrogen. Furthermore, testosterone is converted to 5 alpha-dihydrotestosterone (DHT) by 5 alpha-reductase and exerts biophysiological actions through binding to androgen receptors. However, it remains unclear whether skeletal muscle can synthesize DHT from testosterone and/or DHEA and whether these hormones affect glucose metabolism-related signaling pathway in skeletal muscles. We hypothesized that locally synthesized DHT from testosterone and/or DHEA activates glucose transporter-4 (GLUT-4)-regulating pathway in skeletal muscles. The aim of the present study was to clarify whether DHT is synthesized from testosterone and/or DHEA in cultured skeletal muscle cells and whether these hormones affect the GLUT-4-related signaling pathway in skeletal muscles. In the present study, the expression of 5 alpha-reductase mRNA was detected in rat cultured skeletal muscle cells, and the addition of testosterone or DHEA increased intramuscular DHT concentrations. Addition of testosterone or DHEA increased GLUT-4 protein expression and its translocation. Furthermore, Akt and protein kinase C-zeta/lambda ( PKC-zeta/lambda) phosphorylations, which are critical in GLUT-4-regulated signaling pathways, were enhanced by testosterone or DHEA addition. Testos-terone and DHEA-induced increases in both GLUT-4 expression and Akt and PKC-zeta/lambda phosphorylations were blocked by a DHT inhibitor. Finally, the activities of phosphofructokinase and hexokinase, main glycolytic enzymes, were enhanced by testosterone or DHEA addition. These findings suggest that skeletal muscle is capable of synthesizing DHT from testosterone, and that DHT activates the glucose metabolism-related signaling pathway in skeletal muscle cells.
AMER PHYSIOLOGICAL SOC, 2008年05月, AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM, 294 (5), E961 - E968, 英語[査読有り]
研究論文(学術雑誌)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
研究発表ペーパー・要旨(国際会議)
Introduction The purpose of the present study was to elucidate the effect of unilateral lower limb suspension (ULLS) on aerobic capacity during one legged cycle exercise and whether the change in aerobic exercise capacity after ULLS with or without intensive interval training is related to the change in skeletal muscle volume Methods There were 13 young men who underwent 20 d of ULLS and were divided into 2 groups based on some physical characteristics the control group (CON, N = 7) and the trained group (TRN, N = 6) Subjects m TRN underwent interval cycle training on alternate clays during ULLS The respiratory and circulatory responses to one legged incremental cycling and muscle volume of the thigh were measured before and after 20 d of ULLS Results One legged peak oxygen uptake (VO(2peak)) and total muscle volume of the thigh in CON decreased significantly after 20 d of ULLS (-11 0 +/- 3 5% in VO(2peak) -6 1 +/- 1 8% in total muscle volume) However these parameters were maintained in TRN (+02 +/- 5 2% in VO(2peak), -1 0 +/- 1 8% in total muscle volume) Circulatory variables at rest and during submaximal exercise were unchanged in both groups after ULLS Changes in one legged VO(2peak) were significantly correlated with change in total muscle volume of the thigh in CON Conclusion Our findings indicated that peripheral adaptations after ULLS could relate to the change in aerobic exercise capacity during one legged exercise Our results also suggest that intensive interval training prevents ULLS induced deconditioning of both aerobic exercise capacity and skeletal muscle volume
AEROSPACE MEDICAL ASSOC, 2010年12月, AVIATION SPACE AND ENVIRONMENTAL MEDICINE, 81 (12), 1085 - 1091, 英語[査読有り]
速報,短報,研究ノート等(学術雑誌)
Introduction: Atrophy Of the leg muscles is a serious consequence of disuse and Occurs with prolonged exposure to microgravity. We investigated whether intense interval training on a cycle ergometer would prevent muscle changes during unilateral lower limb suspension (ULLS). Methods: This study involved 11 health), men who were divided into 2 groups, one with training on a cycle ergometer (TRN, N = 6) and the other a control group (CON, N = 5). TRN performed intense interval training (up to 90% of maximum heart rate) on alternate days during 20 d of unloading. Maximum voluntary contraction (MVC) of the quadriceps femoris and volume of the thigh muscle were measured before and after unloading. Muscle functional magnetic resonance imaging (mfMRI), which reflects the contractile activity of the activating muscle, were acquired during submaximal dynamic knee extension exercises. Results: The MVC was significantly decreased in TRN (-11.1%) and CON (- 18.7'%). The total volume Of the thigh muscles was maintained in TRN (-0.2%); however, a significant decrease was found in CON (-6.9%). The mfMRI signal increase for submaximal exercise did not change for TRN; however, it significantly increased for CON. Conclusions: Although the power of this Study was limited, these results Suggest that training oil a cycle ergometer counteracts some of the effects of unloading and merits further study as a potential Countermeasure for muscle changes in microgravity.
AEROSPACE MEDICAL ASSOC, 2009年07月, AVIATION SPACE AND ENVIRONMENTAL MEDICINE, 80 (7), 652 - 656, 英語[査読有り]
速報,短報,研究ノート等(学術雑誌)
[査読有り]
We compared the ventilatory and circulatory responses during 20 s of light dynamic leg and arm exercises performed separately using dominant and non-dominant limbs. Seventeen subjects performed a 20-s single-leg knee extension-flexion exercise with a load of 5% of maximal muscle strength attached to the ankle. Fifteen of the seventeen subjects also did a single-arm elbow flexion-extension exercise in which a load was attached to the wrist in the same way as in the leg exercise. Similar movements were passively performed on the subjects by experimenters to avoid the effects of central command. The magnitude of change from rest (gain) in minute ventilation during passive movement (PAS) was significantly smaller in the dominant limbs than in the non-dominant limbs, though a significant difference was not detected during voluntary exercise (VOL). In contrast, heart rate and blood pressure responses did not show any differences between the dominant and non-dominant limbs during either VOL or PAS. In conclusion, the initial ventilatory response to PAS in the dominant limbs was lower than that of the non-dominant limbs, though the ventilatory response to VOL was not. Circulatory responses were not different between the dominant and non-dominant limbs. These results suggest that peripheral neural reflex during exercise could be different between dominant and non-dominant limbs and that ventilatory response at the onset of exercise might be controlled by the dual neural modulation of central command and peripheral neural reflex, resulting in the same ventilatory response to both dominant and non-dominant limb exercise.
SPRINGER, 2007年10月, EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY, 101 (3), 347 - 358, 英語[査読有り]
速報,短報,研究ノート等(学術雑誌)
The purpose of this study was to clarify whether delayed onset muscle soreness (DOMS) and muscle damage after eccentric exercise (ECC) could affect the ventilatory and circulatory responses at the onset of exercise, and whether those effects would continue after the disappearance of DOMS. Ten males participated in this study. We measured ventilatory and circulatory responses at the onset of exercise, for the first 20 s, during knee extension-relaxation voluntary exercise (VOL) and passive movement (PAS), which was achieved by the experimenter alternatively pulling ropes connected to the subjects' ankles for the same period and frequency as during VOL. VOL and PAS were performed before, 2 days after, and 7 days after ECC. The following results were found: (1) the gain of minute ventilation at the onset of VOL at 2 days after ECC was significantly larger than that of before ECC; (2) the gain of minute ventilation at 7 days after ECC during both VOL and PAS was also enhanced significantly as compared to that of before ECC; and (3) heart rate and blood pressure responses were unchanged throughout the experimental period. In conclusion, ventilatory response at the onset of exercise is augmented during DOMS and EIMD after ECC and the enhanced ventilatory response continued after the disappearance of DOMS. It is suggested that enhanced ventilatory response during exercise after ECC is attributed to at least the changes in neural factors and that the mechanisms inducing these augmented ventilatory responses should be different during the period after ECC.
SPRINGER, 2006年07月, EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY, 97 (5), 598 - 606, 英語[査読有り]
速報,短報,研究ノート等(学術雑誌)
学術書
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学術書
[招待有り]
シンポジウム・ワークショップパネル(指名)
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公開講演,セミナー,チュートリアル,講習,講義等
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シンポジウム・ワークショップパネル(指名)
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[招待有り]
シンポジウム・ワークショップパネル(指名)
口頭発表(一般)
ポスター発表
ポスター発表
ポスター発表
ポスター発表
[招待有り]
シンポジウム・ワークショップパネル(指名)
ポスター発表
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[招待有り]
シンポジウム・ワークショップパネル(指名)
[招待有り]
口頭発表(招待・特別)
ポスター発表
ポスター発表
公開講演,セミナー,チュートリアル,講習,講義等
ポスター発表
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[招待有り]
シンポジウム・ワークショップパネル(指名)
[招待有り]
シンポジウム・ワークショップパネル(指名)
感情調整機能は,自立した生活が困難となる人生の最終段階である約10年間(エンド・オブ・ライフ)の心理的安寧や生活の質(QOL)を左右する最も重要な機能の一つである。身体的,認知的機能の多くは加齢とともに低下するが,感情のコントロールを担う感情調整機能は加齢による低下がみられずむしろ向上する。 高齢期の感情調整機能は低下しないのか?を明らかにするための実験と,感情調整機能が人間関係の喪失,社会的役割の喪失,健康の喪失にどのように影響するのか?を明らかにするための調査を実施した。 実験では,65歳以上の高齢者100名(平均年齢71.74歳, SD=3.85)を対象とし,感情調整機能の測定,認知機能の検査(WAIS -Ⅳ),処理される情報の質の評価として自伝的記憶課題,遺伝子解析のための唾液のサンプリングを行った。その結果,感情調整と種々の認知機能検査結果との間に関連性は認められなかった。一方で,普段の生活の中でよく想起される記憶の感情価,重要度,鮮明度といった指標と感情調整には関連性が認められた。これらの結果は,認知機能のパフォーマンスではなく,どのような情報を思い出し処理するかといった情報の質が感情調整と関連していることを示唆している。 調査では, 20-70代の936名を対象とし,感情調整,社会的つながり,孤独感の測定を実施した。その結果,男性よりも女性の方が感情調整を頻繁におこなうこと,社会的つながりが多い人は感情調整の頻度が高いこと,感情調整をおこなうことで孤独感が低下すること,加齢に伴い感情調整の頻度は低下をすることが示唆された。
2019年度は2つの実験課題を実施した。 研究課題①は、健常な60‐80歳の高齢男女99名(年齢:68.1±5.1歳)を対象とした。二重エネルギーX線吸収法を用いて、全身、四肢の除脂肪量を評価した。加えて、筋力指標として、握力、脚伸展力を測定した。安静状態にて血液サンプルを採取し、血中25(OH)D濃度を評価した。更に、習慣的な食事摂取量(BDHQ)と身体活動量(IPAQ)を収集した。 被験者99名の血中25(OH)D濃度の平均値は88.3±33.3 nmol/lで、血中25(OH)D濃度が不足している(<50 nmol/l)被験者は11%(9名)であった。四肢非脂肪量の平均値は17.1±3.6㎏で、握力の平均値は29.2±7.2kgだった。血中25(OH)D濃度は、全身非脂肪量(β=0.077,p=0.066)、脚伸展力(β=-0.015,p=0.848)、握力(β=0,074,p=0.120)とは有意な関連が認められなかったものの、四肢非脂肪量(β=0.097,p=0.025)と統計的に有意な関連が認められた。 本研究においては、血中25(OH)D濃度は高値(平均88.3±33.3 nmol/l)であった。以上のことから、筋力に対する機能を発揮するには、一定以上の血中25(OH)D濃度があれば可能であることが考えられ、本研究においても、ほとんどの被験者が必要な血中25(OH)D濃度を満たしていた(平均88.3±33.3 nmol/l, <50 nmol/l(不足)の被験者=9名)ため、筋力に対する濃度依存的な関係が認められなかった可能性が考えられる。 研究課題②は、健常な若年男性を被験者として研究を実施した。一過性のレジスタンス運動を実施し、その前後において筋生検により筋サンプルを採取することで、運動前後における筋細胞内でのビタミンD受容体や筋たんぱく質合成に関わるシグナルタンパク質の発現を比較・検討することを目的とした。研究課題②は次年度も引き続き継続し、結果をまとめる予定である。
本研究は,運動により変化する性ステロイドホルモンが動脈硬化度の低下効果に貢献するのかを明らかにするために,性ステロイドホルモン合成酵素の合成阻害剤を用いて直接的に運動効果に影響するかについて検討した。肥満型糖尿病モデルラットを用いて、8週間の有酸素性トレーニングによって動脈硬化度は低下したが、運動とともに活性化型テストステロンであるDHTやエストロゲンであるE2の合成酵素の抑制剤により性ステロイドホルモンの分泌を抑制したが、運動による動脈硬化度の低下効果には影響を及ぼさなかった。本研究結果から,習慣的な有酸素性運動による動脈硬化度の低下に性ステロイドホルモンは関与しない可能性が考えられる。
本研究は,中高齢者の有酸素性トレーニングによりマイオカインの分泌が動脈硬化度の低下に関与するか否かについて検討した。健常な中高齢者男女を対象に,60-70%VO2peak運動強度の自転車運動(週3日,45分間)を8週間実施した。運動トレーニングにより動脈硬化度は有意に低下し,マイオカインの1つであるapelinおよびirisinの血中濃度は有意に増加した。これらのマイオカインと動脈硬化度の変化率との間には負の相関関係が認められた。以上の結果から,中高齢者の有酸素性トレーニングによる動脈硬化度改善の機序にマイオカインの1つであるapelinやirisinが関与する可能性が示唆された。
活性酸素種および活性酸素種とレジスタンス運動の組み合わせが筋タンパク質合成に関与するシグナル伝達応答に及ぼす影響について検討した。その結果、活性酸素種の投与は、安静時の骨格筋におけるmTORC1を活性化することがわかった。しかしながら、活性酸素種投与はレジスタンス運動により惹起されるmTORC1活性化を亢進させなかった。
実験動物の骨格筋を対象とした試験管内(in vitro)の実験から、ヒトの運動トレーニング実験まで行い、異なる強度の運動トレーニングが、大腸がんの発症予防に有効である機序を明らかにした。特に高強度・短時間・間欠的運動トレーニングは、運動強度依存性の活動筋中のAMPK活性を上昇させ、それがPGC1αの発現量を高め、さらにそれが、大腸における前がん細胞であるACFのアポトーシスを誘導するSPARC発現量を高め、それにより血中のSPARC濃度が増加することにより将来の大腸がん発症リスクを低下させることが明らかになった。
骨格筋量調節に関わる細胞外マトリックス構成タンパク質、細胞接着分子、マトリックスメタロプロテアーゼ(MMPs)について、レジスタンス運動(RE)および加齢の影響を検討した。REを繰り返し、タンパク質合成および筋肥大応答が停滞したラット骨格筋において、インテグリン発現量の増加と一過性REに対するMMP-2, 9活性化応答の低下が観察された。高齢男性の骨格筋において若年男性に比べてインテグリン発現量が多く、MMP-2, 9の活性が低下していることがわかった。これらの結果は、インテグリンとMMPs活性の変化が運動による骨格筋量の調節において重要な役割を果たしている可能性を示唆する。
本研究はヒト骨格筋内性ステロイドホルモンの合成酵素発現および組織濃度の検討と加齢および高齢期のレジスタンストレーニングによる発現・分泌変動が筋量・筋力の増加に関連するかを検討した。ヒトの筋生検により、骨格筋内の性ステロイドホルモン合成酵素(3β-HSD, 17β-HSD, 5α-reductase)発現が認められた。また、これらの発現および性ステロイドホルモン濃度は加齢により低下したが、レジスタンストレーニングにより改善し、骨格筋内の性ステロイドホルモン濃度と筋量・筋力との間に有意な正相関が認められた。骨格筋内の性ステロイドホルモンは高齢者の筋量・筋力の維持・増進に関与する可能性が示唆された。
競争的資金
競争的資金
研究課題1では、1型糖尿病モデルラットにおいて急性のジオスゲニン(性ステロイドホルモン前駆体のDHEAに化学構造が類似している栄養成分)を投与した結果、投与後90分後に有意に高血糖が改善し、骨格筋糖代謝調節経路の亢進が認められた。ジオスゲニン投与により骨格筋内の性ステロイドホルモン濃度が増加し、骨格筋糖代謝活性を亢進し、高血糖を改善することが明らかとなった。 研究課題2において、2型糖尿病モデルラットに8週間ジオスゲニンを投与した結果、骨格筋糖代謝活性は亢進し、空腹時血糖、インスリン濃度、さらにインスリン感受性においても有意に改善し、ジオスゲニン投与が2型糖尿病を改善する可能性を見いだした。