Expression of LXR in rats with obesity or hyperglycemia and its impact on PEPCK expression in liver

Objective To investigate the expression of LXR in rats with obesity or hyperglycemia and its impact on the regulation of expressions of 11β-HSD1 mRNA and PEPCK mRNA to study the mechanism of impact of LXR signal pathway on glucose metabolism.Methods Twenty-seven male SD rats were modeled and categorized into three groups: normal control(CON) group,obesity(OB) group and diabetes mellitus(DM) group.Weight,blood glucose,serum triglyceride and cholesterol were measured to estimate the metabolic status.Abdominal MRI and liver biopsy were performed to estimate fat accumulation,and glucose clamp test was performed to estimate the insulin resistance status.Then the rats were sacrificed and liver was taken for pathological examination.Real-time PCR was used to determine the liver expression of LXR mRNA,PEPCK mRNA and 11β-HSD1 mRNA.Results MRI and the liver pathological study showed that the OB group had severe abdominal fat accumulation and fatty liver.And the glucose clamp test showed that the rats in OB group had obvious insulin resistance.Comparing to CON group,the LXR mRNA expression was significantly higher and the 11β-HSD1 mRNA expression was significantly lower in OB and DM groups;PEPCK mRNA expression decreased significantly in OB group,while it was significantly higher in DM group(P0.05).Conclusions In obesity status,LXR as a protective receptor of glucose metabolism may keep glucose homeostasis through regulating hepatic glucose metabolic enzymes.Whereas in diabetes period,the protective effect of LXR could not reverse the abnormal alteration of glucose metabolism related enzymes caused by insufficiency of insulin,thereby blood glucose is elevated.