[Effects of exercise and low-fat diet on the TNF-alpha expression of insulin resistance in rats].

OBJECTIVE: To investigate the effects of exercise (EX), low-fat diet (LFD) and their combination intervention on the tumor necrosis factor-alpha (TNF-alpha) expression of insulin resistance in rats. METHODS: One hundred and thirty male rats randomly assigned to 2 groups: Control (CON)-10 rats consuming a low-fat diet; HFD-120 rats consuming a high-fat diet (HFD). The dietary regimen was sustained for 8 wk, at which point the 40 HFD group rats gaining the most weight were referred to as the obese rats. Glucose tolerance was assessed by an oral glucose tolerance test (OGTT). During the procedure of OGTT, the blood was drawn for insulin assay (insulin release test). The whole body insulin resistance was assessed by glucose-insulin index. The obese HFD group rats were randomized into one of four intervention groups: HFD-sedentary (HFD-SED), HFD-exercise(HFD-EX), low fat diet-SED (LFD-SED), LFD-EX. Ex rats performed 8-wk exercise training on a motorized treadmill. The CON group had access to low-fat diet for another 8 wk. After 8 wk of exercise and low-fat diet intervention, the OGTT and insulin release test were performed again. To use ELISA technique for detecting TNF-alpha in soleus muscle and adipose tissue. RESULTS: After being fed high-fat diet for 8 wk, glucose-insulin index in the HFD group were significantly greater than that in CON group (P < 0.01). After 8-week exercise and low-fat diet intervention, glucose-insulin index in HFD-SED group was significantly greater than that in CON group (P < 0.01). The index in three intervention groups was significantly less than that in HFD-SED group (P < 0.01) . TNF-alpha content in adipose tissue and the soleus muscle for HFD-SED group was significantly greater than that in CON group (P < 0.01). Three intervention groups were significantly less than HFD-SED group (P < 0.01). CONCLUSION: Exercise and low-fat diet interventions can decrease the TNF-alpha expression in insulin resistance rat.

[Effects of exercise and diet intervention on oxidative stress in insulin resistant rat].

OBJECTIVE: To investigate the effects of exercise, diet and their combination intervention on oxidative stress of insulin resistance rat. METHODS: Establish obesity-induced insulin resistance rat models. Obesity was assessed by the body weight and lipid ratio. Glucose tolerance was assessed by the integrated area under the curve for glucose (AUCg) during an oral glucose tolerance test (OGTT), then 8 weeks of exercise, diet, and combination interventions, respectively. To analyze serum free fatty acids (FFA) content, superoxide dismutase (SOD) and maleic dialdehyde (MDA) content in liver, adipose tissue and soleus muscle by biochemical method. Judge oxidative stressby FFA content and SOD/MDA. RESULTS: Three kinds of intervention reduced the body weight (P < 0.01), lipid ratio (P < 0.01) and AUCg (P < 0.01). Dietary and combination intervention lowered serum free fatty acid concentration (P < 0.01), separate exercise intervention had not such effect. Three kinds of intervention increased SOD/MDA in the liver and adipose tissue, exercise and combination intervention improved SOD/MDA in soleus muscle, dietary intervention alone had not the effect. CONCLUSION: Exercise and dietary intervention may improve the overall insulin resistance by alleviating oxidative stress.

Enhanced adaptation of visual cortical cells to visual stimulation in aged cats.

Aging leads to compromised intracortical inhibition. Whether aging affects the adaptation of cortical neurons to sensory stimulation remains unknown. In this study, adaptation of V(1) neurons to visual stimuli was compared between young adult and aged cats using in vivo extracellular single-unit recording techniques. Our results indicated that neurons in aged cats exhibited significantly stronger adaptation to visual stimuli than did neurons in young adult cats. The enhanced adaptation of visual cortical cells to visual stimulation in the aging brain, which is of great significance to the energy savings in neuronal activity of senescent individuals, could be underlied by a simultaneous change of somatic afterhyperpolarization and synaptic depression mediated by an extensive age-related GABAergic inhibition reduction at cortical and subcortical level.