肝脏胰岛素抵抗与肝糖输出调控基因表达的关系

目的观察高脂饮食饲养造成的肝脏胰岛素抵抗与肝糖输出有关的调控基因表达的关系。方法将8周龄雄性SD大鼠随机分为2组:正常饲养组(10例)和高脂饮食饲养组(10例)。饲养期间动态观察体重和空腹血糖变化趋势。饲养至28周实验终点时取空腹血测胰岛素和甘油三酯。采用肝脏对3H-2- 脱氧葡萄糖的摄取能力测定各组的肝脏胰岛素敏感性,用蒽酮法测定肝糖原含量,并用逆转录聚合酶链反应法分析糖异生和糖原合成关键酶肝脏磷酸烯丙醇羧激酶、葡萄糖-6-磷酸酶、糖原合成酶和PPAR γ协同刺激因子1 α的mRNA表达的变化。结果高脂饮食饲养大鼠出现明显腹型肥胖。血浆甘油三酯水平升高。饲养18周开始,高脂饮食组空腹血糖增加[正常饲养组(4．77±0．63)mmol／L,高脂饮食组[(5．45± 0.87)mmol／L,P<0．05],此差异持续到28周;肝脏3H-2-脱氧葡萄糖摄取率高脂饮食组较正常饲养组下降42．0％,肝糖原含量增加92．4％(P<0．01)l磷酸烯丙醇羧激酶mRNA增加41．5％,协同刺激因子1α mRNA增加30．8％(P<0．05)。结论长期高脂饮食诱导肝脏协同刺激因子1α和肝脏磷酸烯丙醇羧激酶基因表达,糖异生增加,同时肝糖分解不能相应受到抑制,导致肝糖输出增加及空腹血糖升高。

Relationship between hepatic insulin resistance and the expression of genes involved in hepatic glucose output

Objective To study the relationship between hepatic insulin resistance induced by high fat diet and the expression of genes involving hepatic glucose output. Methods Normal 8-week-old male SD rats were randomly divided into two groups, i.e, normal chow group (NC, n = 10) and high fat diet group (HF, n = 10). They were fed for 28 weeks. Body weight and fasting blood glucose (FBG) were measured. At the end of the experiment, the rats were sacrificed and their fasting insulin (INS) and triglycerides (TG) were measured. Hepatic insulin sensitivity was measured by tissue uptake of 3H-2-deoxyglucose and the content of hepatic glycogen was measured using the anthrone method. Gene expression was investigated by using the semi-quantitative RT-PCR method. Results As compared with NC group, CF group rats developed visceral obesity which was accompanied by higher plasma TG. FBG in CF group increased starting from the 18th week (NC 4.77?. 63 mmol/L vs HF 5.45?.87 mmol/L, P < 0.05). The rate of uptake of 3H-2-deoxyglucose in livers decreased by 51% in the HF group. The content of hepatic glycogen increased by 92.4% (P < 0.01). The level of phosphoenolpyruvate carboxykinase (PEPCK) and PGC-la mRNA increased by 41.5% and 30.8%, respectively (P < 0.05). Conclusion A high fat diet induced expressions of PGC-la and PEPCK. It suggests that gluconeogenesis may play a role in the increase of hepatic glucose output and FBG.