The effect of exercise on adiponectin receptor expression in skeletal muscle of insulin-resistant rats

Objective To observe the effects of exercise on serum adiponectin and adiponectin receptor (AdipoR) level in skeletal muscle of insulin-resistant rats. Methods A total of 30 healthy male rats were randomly divided into a control group ( NC, n = 8) and a high-fat group ( HF, n = 22), fed with normal chow and high fat diet, respectively. Eighteen weeks later, the high-fat group was randomly divided into a high-fat diet control group (HC, n = 10) and an exercise group (HE, n = 12). The HC and HE group were continually fed with high fat diet, while the HE group was administered with swimming training for 6 weeks in addition at the same time. After 24 weeks, the insulin sensitivity index was calculated, and serum adiponectin level was detected by using ELISA. The expressions of AdipoR mRNA in skeletal muscle were detected with real-time fluorescence quantitative polymerase chain reaction (PCR). Results After 18 weeks, compared to NC group, the insulin sensitivity index of HF group decreased significantly. It suggested that insulin resistance appeared in HF group. Twenty-four weeks later, compared to NC group, the ISI of HC group was significantly decreased, meanwhile the level of serum adiponectin, expression of AdipoR1 and AdipoR2 mRNA in skeletal muscle of HC group were 71.9% , 59.9% and 69.2% of those of the NC group, respectively; compared to HC group, the ISI was increased significantly by exercise, meanwhile the expression of AdipoR1 mRNA in skeletal muscle was significantly increased by 1.33 times, however the level of serum adiponectin and the expression of AdipoR2 mRNA in skeletal muscle were not altered in HE group. Conclusion Six weeks of exercise improves insulin sensitivity through increasing the expression of AdipoRI mRNA in skeletal muscle. Key words: Exercise; Insulin resistance; Adiponectin; Adiponectin receptor