银杏叶提取物对2型糖尿病大鼠肝脏糖皮质激素受体表达的影响

目的： 观察银杏叶提取物（EGB）对2型糖尿病大鼠肝脏糖皮质激素受体(GR)表达的影响，并探讨其机制。方法：雄性SD大鼠30只随机均分成3组：正常对照组、糖尿病对照组、EGB干预组。后两组采用高脂饮食4周，按30 mg/kg 腹腔注射链脲佐菌素（STZ） 诱导2 型糖尿病大鼠模型， EGB干预组给予50 mg·kg-1·d-1EGB连续灌胃12周。治疗结束取血生化检测血糖、血脂水平，放免法检测血胰岛素水平，HE染色光镜下观察肝脏组织的形态学改变，以RT-PCR法检测肝组织GR mRNA的表达水平，免疫组化法检测肝组织GR蛋白表达水平。结果：EGB可降低糖尿病大鼠血糖、血脂、血胰岛素水平，减轻肝细胞脂肪变性、坏死、炎细胞浸润，使肝组织GR mRNA的表达与蛋白表达明显减低。结论：EGB具有抑制2型糖尿病大鼠肝脏GR基因mRNA表达与蛋白表达的作用，这可能是其降低2型糖尿病大鼠血糖、血脂水平，改善肝内脂肪沉积的重要机制之一。

Effects of extract of gingko biloba on expression of glucocorticoid receptor in hepatic tissues from type 2 diabetic rats

AIM: To study the effect and mechanism of extract of ginkgo biloba (EGB) on liver glucocorticoid receptor (GR) expression in type 2 diabetic rats. METHODS: Thirty male Sprague-Dawley rats were divided randomly into three groups: normal control group (n=10), type 2 diabetic group (n=10) and ginkgo biloba treated group (n=10). After fed with high-fat feeding for 4 weeks, the later two groups were injected with streptozotocin at a dose of 30 mg/kg intraperitoneally to induce type 2 diabetic rat model. The EGB treated group was gavaged with EGB at the dose of 50 mg·kg-1·d-1 for 12 weeks. At the end of experiment, the rats were sacrificed, the blood glucose, serum lipid and blood insulin were measured. The morphology of liver tissue was observed under light microscopy with HE staining. GR mRNA expression in liver was measured by RT-PCR. The level of GR protein expression in liver tissue was detected by immunohistochemistry. RESULTS: EGB reduced the levels of blood glucose, blood lipids, blood insulin in diabetic rats. EGB also relieved fatty degeneration and necrosis of the hepatic cells, ameliorated infiltration of inflammatory cells in the liver; and decreased GR expression at both mRNA and protein levels in diabetic liver. CONCLUSION: EGB may inhibit GR expression in liver of type 2 diabetic rats, which results in decreasing the level of blood glucose, blood lipid, blood insulin and relieving the liver damage in type diabetic rats.