Hypothalamic expression of orexin A and lipid metabolism disorder in rats with alimentary obesity

AIM: To evaluate the effect of orexin A in rat hypothalamus on lipid metabolism disorder in rats with alimentary obesity induced by high-fat diet.METHODS: The rat model of alimentary obesity was induced by high-fat diet. The levels of insulin, triglyceride (TG) and total cholesterol (TC) in the serum were detected by luminescent immunoassay and enzymic method. The mRNA expression of orexin A in rat hypothalamus was determined by real-time PCR.RESULTS: There were statistically significant differences of weight, body fat content, and Lee's index between high-fat diet group and control group after 8-week feeding of high-fat diet. Compared to control animals, the levels of insulin, TG and TC in the rats with alimentary obesity significantly increased by 50％, 94％ and 43％, respectively (P<0.05). The expression of orexin A in rat hypothalamus significantly decreased by 57％, and had significant negative correlation with Lee's index, insulin, TG and TC. Their correlation coefficients were r=-0.798 (P<0.05), r=-0.868 (P<0.05), r=-0.981(P<0.05) and r=-0.815 (P<0.05), respectively. CONCLUSION: Alimentary obesity and lipid metabolism disorder induced by high-fat diet are correlated with down-regulation of orexin A expression in rat hypothalamus.