Exercise and dietary change ameliorate high fat diet induced obesity and insulin resistance via mTOR signaling pathway.

PURPOSE: The purpose of this study was to investigate the effect of exercise and dietary change on obesity and insulin resistance and mTOR signaling protein levels in skeletal muscles of obese rats. METHODS: Sixty male Sprague-Dawley rats were divided into CO (Normal diet) and HF (High Fat diet) groups in order to induce obesity for 15 weeks. The rats were then subdivided into CO, COT (CO + Training), HF, HFT (HF + Training), HFND (Dietary change), and HFNDT (HFND + Training) groups (10 rats / group). The training groups underwent moderate-intensity treadmill exercise for 8 weeks, after which soleus muscles were excised and analyzed. Data was statistically analyzed by independent t-test and One-way ANOVA tests with a 0.05 significance level. RESULTS: Fasting blood glucose, plasma insulin, and HOMA-IR in the HF group were significantly higher, as compared with other groups (p <.05). Protein levels of insulin receptor subunit-1 (IRS-1), IRS-2, and p-Akt were significantly higher in the HFT, HFND, and HFNDT groups, as compared with HF group. In addition, the protein levels of the mammalian target of rapamycin complex 1 (mTORC1) and ribosomal S6 protein kinase 1 were significantly decreased by exercise and dietary change (p <.05). However, mTORC2 and phosphoinositide 3-kinase were significantly increased (p <.05). CONCLUSION: In summary, despite the negative impact of continuous high fat intake, regular exercise and dietary change showed a positive effect on insulin resistance and mTOR signaling protein levels.

Effects of combined open kinetic chain and closed kinetic chain training using pulley exercise machines on muscle strength and angiogenesis factors.

[Purpose] This study investigated the effects of combined open kinetic chain and closed kinetic chain training using pulley exercise machines on muscle strength, anaerobic power, and blood levels of angiogenesis factors. [Subjects and Methods] Twenty male university students were equally divided between control and pulley training groups. The pulley-training group underwent 8 weeks of combined training. Open kinetic chain training consisted of 2 sets of 10 repetitions at 60% of one repetition maximum; closed kinetic chain training consisted of 2 sets of 10 repetitions of resistance exercise using the subject's own body weight. Isokinetic strength (trunk and knee), anaerobic power, vascular endothelial growth factor, angiopoietin-1, angiopoietin-2, and follistatin were analyzed. [Results] After 8 weeks, flexor and extensor muscle strength significantly increased in the trunk and knee; average and peak power also increased significantly. Angiopoietin 1 increased 25% in the control group and 48% in the pulley training group; vascular endothelial growth factor and follistatin increased significantly in the pulley-training group after 8 weeks. [Conclusion] Eight weeks of combined training using pulley exercise machines effectively increased biochemical factors related to muscle growth, as well as muscle strength in the trunk and knees.

Effects of treadmill exercise on skeletal muscle†mTOR signaling pathway in high-fat diet-induced obese mice.

[Purpose] The aim of this study was to investigate the effects of regular treadmill exercise on skeletal muscle Rictor-Akt and mTOR-Raptor-S6K1 signaling pathway in high-fat diet-induced obese mice. [Subjects and Methods] Four- week-old C57BL/6 mice were adopted and classified into normal diet group (ND, n = 10), normal diet and training group (NDT, n = 10), high-fat diet group (HF, n = 10), and high-fat diet and training group (HFT, n = 10). The exercise program consisted of a treadmill exercise provided at low intensity for 1-4 weeks, and moderate intensity for 5-8 weeks. [Results] The Western blot method was used to measure the expression of mTOR, Raptor, S6K1, Rictor, and Akt proteins in the soleus muscle. mTOR levels were significantly higher in the HF group than in the ND and NDT groups. Raptor/mTORC1 and S6K1 levels were significantly higher in the HF group than in all the other groups. Akt levels were significantly lower in the HF group than in the NDT group. The risk of obesity may be associated with the overactivation of the mTOR-Raptor-S6K1 signaling pathway and a decrease in Akt levels. [Conclusion] This study also indicates that performing aerobic exercise may be associated with the downregulation of the mTOR-Raptor-S6K1 pathway.

The effect of exercise on expression of myokine and angiogenesis mRNA in skeletal muscle of high fat diet induced obese rat.

PURPOSE: The purpose of this study was to investigate the effect of regular treadmill exercise on the mRNA expressions of myokines and angiogenesis factors in the skeletal muscle of obese rats. METHODS: Thirty two male Sprague-Dawley rats (4weeks old) were divided into the CO (control) and HF (high fat diet) groups. Obesity was induced in the HF group by consumption of 45% high-fat diet for 15 weeks. These groups were further subdivided into training groups (COT and HFT); the training groups conducted moderate intensity treadmill training for 8 weeks. Soleus muscles were excised and analyzed by real-time quantitative PCR. RESULTS: mRNA expression of myokines, such as PGC-1α, IL-6, and IL-15, in the COT and HFT groups (which conducted regular exercise), were higher as compared with the CO and HF groups (p < 0.05). Also, the levels in the HF group were significantly lower when compared with CO group (p < 0.05). Expression of angiogenesis mRNA, namely mTOR, VEGF, and FLT1, were significantly lower in the HF group, as compared to the CO group (p < 0.05). In addition, COT group had a higher expression of mTORC1, mTORC2, VEGF and FLT mRNA, than the CO group (p < 0.05); the HFT group also had higher expressions of mTOR, VEGF and FLT1 mRNA than the HF group (p < 0.05). CONCLUSION: These results indicate that mRNA expression of myokines was increased through the activity of muscle contraction, and it also promoted the mRNA expression of angiogenesis due to activation of mTOR. Thus, we conclude that not only under normal health conditions, but in obesity and excess nutritional circumstances also, regular exercise seems to act positively on the glycemic control and insulin sensitivity through the angiogenesis signaling pathway.

Exercise training improves cardiac autonomic nervous system activity in type 1 diabetic children.

[Purpose] We investigated the effect exercise training has on cardiac autonomic nervous system (ANS) and cardiovascular risk profiles in children with type 1 diabetes mellitus (DM). [Subjects] Fifteen type 1 DM children (all boys; 13.0±1.0 years of age) were enrolled in the study. [Methods] The subjects received exercise training three times a week in a 12-week program. Each child was asked to walk on a treadmill to achieve an exercise intensity of VO2max 60%. ANS activity was measured by power spectral analysis of the electrocardiogram (ECG). Blood samples were obtained for serum lipid profiles. To evaluate Doppler-shifted Fourier pulsatility index (PI) analysis, a 5-MHz continuous wave Doppler (VASCULAB D10) set was used to measure forward blood flow velocity (FLOW) in the radial artery. [Results] Total and low-frequency (LF) power of heart rate variability increased significantly after exercise intervention. Total cholesterol (TC) levels were significant lower after exercise intervention. Total and high-frequency (HF) power were significantly correlated with higher TC levels, but diastolic blood pressure and HF was significantly correlated with lower TC levels. [Conclusion] Regular exercise intervention should be prescribed for children with type 1 DM.

Effects of exercise and diet change on cognition function and synaptic plasticity in high fat diet induced obese rats.

BACKGROUND: Nutritional imbalance-induced obesity causes a variety of diseases and in particular is an important cause of cognitive function decline. This study was performed on Sprague Dawley (SD) rats with 13-weeks of high fat diet-induced obesity in connection to the effects of regular exercise and dietary control for 8 weeks on the synaptic plasticity and cognitive abilities of brain. METHODS: Four weeks-old SD rats were adopted classified into normal-normal diet-sedentary (NNS, n = 8), obesity-high fat diet-sedentary (OHS, n = 8), obesity-high fat diet-training (OHT, n = 8), obesity-normal diet-sedentary (ONS, n = 8) and obesity- normal diet-training (ONT, n = 8). The exercise program consisted of a treadmill exercise administered at a speed of 8 m/min for 1-4 weeks, and 14 m/min for 5-8 weeks. The Western blot method was used to measure the expression of NGF, BDNF, p38MAPK and p-p38MAPK proteins in hippocampus of the brain, and expressions of NGF, BDNF, TrkA, TrkB, CREB and synapsin1 mRNA were analyzed through qRT-PCR. RESULTS: The results suggest cognitive function-related protein levels and mRNA expression to be significantly decreased in the hippocampus of obese rats, and synaptic plasticity as well as cognitive function signaling sub-pathway factors were also significantly decreased. In addition, 8-weeks exercises and treatment by dietary change had induced significant increase of cognitive function-related protein levels and mRNA expression as well as synaptic plasticity and cognitive function signaling sub-pathway factors in obese rats. In particular, the combined treatment had presented even more positive effect. CONCLUSIONS: Therefore, it was determined that the high fat diet-induced obesity decreases plasticity and cognitive function of the brain, but was identified as being improved by exercises and dietary changes. In particular, it is considered that regular exercise has positive effects on memory span and learning capacity unlike dietary control.