Effect of Exercise on Expression of Leptin and Its Receptor in Rats with Insulin Resistance

doi:10.3969/j.issn.1006-9771.2013.01.012

Abstract： Objective To investigate the serum leptin, leptin receptor of tissue in rats with insulin resistance (IR), and the effect of exer-cise on them. Methods 9 male Sprague-Dawley rats were fed with normal diet as control group. 34 rats were randomly assigned into 4 groups: model group (n=9), fed with high-fat/high-sucrose diet without any other intervention; metformin group (n=8), fed with high-fat/high-sucrose diet and metformin 300 mg/kg·d;exercise group (n=9), fed with high-fat/high-sucrose diet and trained with swimming;inte-grated group (n=8), fed with high-fat/high-sucrose diet and metformin 300 mg/kg·d, and trained with swimming. After 6 weeks of interven-tion, the serum leptin was measured with the enzyme-linked immunoabsorbent assay;the expression of leptin receptor protein in liver, skele-tal muscle and adipose were measured with immunohistochemistry, and the expression of leptin receptor mRNA in the same tissues was measured with reverse transcriptase-polymerase chain reaction. Results Compared with the model group, the levels of fasting blood glucose and fasting insulin decreased in the exercise, metformin and integrated group (P<0.05), while the IR index increased (P<0.05). Compared with the control group, the serum leptin increased in the model group (P<0.01), while the expression of leptin receptor protein and mRNA in liver, skeletal muscle and adipose decreased (P<0.01). Compared with the model group, the serum leptin decreased in the exercise, metfor-min and integrated groups (P<0.05), while the expression of leptin receptor protein and mRNA increased (P<0.05). Compared with the met-formin group, the expression of leptin receptor protein and mRNA increased in the exercise and integrated groups (P<0.05). Conclusion High level of serum leptin and low expression of leptin receptor can be found in rats with insulin resistance. Exercise can improve the insu-lin resistance, which may associate with the decrease of the serum leptin and increases of the leptin receptor.