Low-intensity aerobic exercise training: inhibition of skeletal muscle atrophy in high-fat-diet-induced ovariectomized rats.

Hye Jin Kim,Won Jun Lee

doi:10.20463/jenb.2017.0022

Abstract

[Purpose]Postmenopausal women are highly susceptible to diseases, such as obesity, type 2 diabetes, osteoporosis, or skeletal muscle atrophy and many people recognize the need for regular physical activity. Aerobic exercise training is known to improve the oxidative capacity and insulin sensitivity of skeletal muscles. This study aimed to investigate the role of low-intensity aerobic exercise training on skeletal muscle protein degradation or synthesis in the plantaris muscles of high-fat-fed ovariectomized rats.[Methods]Ovariectomized female rats were divided into two groups: a high-fat diet-sedentary group (HFD), and a high-fat diet-aerobic exercise group (HFD+EX). The exercise group exercised aerobically on a treadmill 5 days/week for 8 weeks. The rats progressively ran 30 min/day at 15 m/min, up to 40 min/day at 18 m/min, 0% slope, in the last 4 weeks.[Results]Although aerobic exercise led to significantly increased AMP-activated protein kinase (AMPK) phosphorylation at Thr172, phosphorylation of the mammalian target of rapamycin (mTOR) substrate Thr389 S6K1 level did not decrease. Additionally, even though Akt activity did not increase at Ser473, the atrogin-1 level significantly decreased in the exercise group compared to the non-exercise group. Immunohistochemical staining revealed that high-fat-induced TSC2 protein expression was eliminated in response to aerobic exercise.[Conclusion]These results suggest that aerobic exercise can inhibit skeletal muscle protein degradation, but it cannot increase protein synthesis in the plantaris muscle of high-fat-fed ovariectomized rats. Our findings have implications in understanding skeletal muscle mass maintenance with low intensity aerobic exercise in post-menopausal women.

Highlights

Menopause involves a natural change in the female body, many studies have reported that loss of estrogen due to menopause can cause negative outcomes, such as obesity, metabolic disease, inflammation, osteoporosis, or skeletal muscle atrophy[1, 2, 3]
To test the effect of the high-fat diet and aerobic exercise on total TSC2 protein expression, which inhibits the mammalian target of rapamycin and p70S6K, we performed immunohistochemical staining
In the plantaris muscles of high-fat-fed OVX rats, that atrogin-1 protein expression significantly decreased we demonstrated a significant reduction in TSC2 following 8 weeks of low-intensity aerobic exercise and atrogin-1 protein expression following 8 weeks training, and that it was not regulated with Akt activof low-intensity aerobic treadmill exercise

Summary

Introduction

Menopause involves a natural change in the female body, many studies have reported that loss of estrogen due to menopause can cause negative outcomes, such as obesity, metabolic disease, inflammation, osteoporosis, or skeletal muscle atrophy[1, 2, 3]. Hormone replacement therapy (HRT) has been closely associated with an improvement in metabolic health, and the maintenance of skeletal muscle mass and strength in menopausal, and postmenopausal women[3]. The various health risks of long-term HRT use have been seriously contested, and many researchers have begun to investigate the effect of alternative HRT, such as regular exercise and natural resources on inhibition of menopause-related risk factors. Numerous studies have demonstrated that various types of exercise (e.g. swimming, walking, resistance training, and Pilates) can prevent or improve deleterious effects, including skeletal muscle atrophy, on menopausal women[4, 5]. The molecular mechanisms underlying this have not yet been defined

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