Role of serum leptin,TNF-α and IL-6 on insulin resistance in high-fat diet induced obese rats

Objective: To evaluate the role of serum leptin, TNF-α and IL-6 on insulin resistance in high-fat diet induced obese rats.Methods: After fed with high-fat diet for 8 weeks,the obese rats who were 30g heavier than controls were separated and fed for another 4 weeks.The blood samples were drawed by heart puncture.The serum levels of glucose were measured by glucose oxide-peroxidase method,the levels of leptin and insulin by RIA,and the levels of TNF-α,IL-6 by ELISA.The ratio of insulin versus glucose(I/G) was used as an indicator for insulin resistance.Results: Compared with the controls,the serum levels of leptin,IL-6 and I/G were higher in the obese rats,but the levels of TNF-α were not different between two groups;The levels of leptin and IL-6,but not TNF-α,were closely related to the parameters evaluating insulin resistance in obese rats.Conclusions: The serum levels of leptin and IL-6 are increased in high-fat diet induced obese rats and contribute to insulin resistance.The levels of TNF-α in obese rats are neither statistically increased nor related to insulin resistance.