OBJECTIVETo 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.

METHODSOne 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.

RESULTSAfter 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).

CONCLUSIONExercise and low-fat diet interventions can decrease the TNF-alpha expression in insulin resistance rat.