胃饥饿素及其受体的变化在血糖波动加速GK大鼠糖尿病脑病发病中的作用

Effect of the change of ghrelin and its receptor on accelerating diabetic encephalopathy by blood glucose fluctuation in GK rats

目的探讨胃饥饿素(Ghrelin)及其受体(GHSR1a)的变化在血糖波动加速糖尿病脑病发病过程中的作用。方法 8只雄性Wistar大鼠为正常对照组(NC),16只雄性GK大鼠随机分为持续高血糖组(MS)与血糖波动组(MF)。MF组每日错时腹腔注射葡萄糖及皮下注射胰岛素造成血糖波动模型,MS组每日错时腹腔注射葡萄糖造成持续高血糖模型,NC组每日错时腹腔注射等剂量生理盐水,连续6周,每日观察大鼠一般体征。第6周对大鼠进行行为学检测,包括Morris水迷宫实验、Y迷宫实验;第6周末检测全日9个时间点血糖。麻醉大鼠,心脏采血,检测血清中TC与TG含量。断头取脑,分离海马,HE染色与甲苯胺蓝染色分别观察大鼠海马病理变化及神经元改变。RT-PCR与免疫组织化学分别检测海马中Ghrelin及GHSR1a mRNA与蛋白的表达。结果与NC组比较,MS组与MF组体重增长速度减慢,TC、TG含量升高(P<0.05或P<0.01),认知功能减退,海马病理及神经元改变严重,海马中Ghrelin及GHSR1amRNA与蛋白的表达减少(P<0.05或P<0.01);与MS组比较,MF组在TC、认知功能、海马病理改变、Ghrelin及GHSR1a蛋白的表达上的变化更加明显(P<0.05或P<0.01)。结论 Ghrelin与GHSR1a在糖尿病大鼠海马组织中的表达减少,其在血糖波动加速糖尿病脑病发病过程中发挥重要作用。

Objective To explore the effect of the changes of ghrelin and its receptor （GHSRla） on accelerating diabetic encephalopathy by blood glucose fluctuation in GK rats. Methods Eight male wistar rats were set as normal control group （NC）. 16 male GK rats were randomly divided into sustained hyperglycemia group （MS） and blood glucose fluctuation group （MF）. MF group rats daily accepted intraperitoneal injections of glucose and subcutaneous injections of insulin at different hours for 6 weeks to build the blood glucose fluctuation model. MS group rats daily accepted intraperitoneal injections of glucose at different hours for 6 weeks to build the sustained hyperglycemia model. N group rats daily accepted intraperitoneal injections of isodose NS. General symptoms were recorded every day. The behavioral tests, including Morris water maze test and Y maze test, were taken at the 6th week. The glycemic profile at 9 time points in one day were measured at the end of the 6th week. After executing the rats,blood was taken to detect the content of total TC esterol （TC） and triglyceride （TG）. The changes of pathology and neurons in hippocampus were observed by HE staining and toluidine blue staining. Theexpressions of Ghrelin and GHSRla mRNA in hippocampus were detected by RT-PCR and immunohistochemistry. Results Compared with the NC group, the speed of weight growth in MS and MF group rats were slower,the levels of TC and TG increased significantly（P〈0. 05 or P〈0. 01）, the cognitive function decreased significantly, the changes of pathology and neurons in hippocampus were more serious, the expressions of ghrelin and GHSRla mRNA in hippocampus decreased significantly （P〈0. 05 or P〈0. 01）. Compared with MS group, MF group rats had more obvious changes in TC, cognitive function, pathological changes and the expressions of Ghrelin and GHSRla protein in hipp0campus （P〈0. 05 or P〈0.01）. Conclusion The expressions of ghrelin and GHSRla in hippocampal tissue of diabetic rats decreased significantly which playing an important role on accelerating the process of diabetic encephalopathy by blood glucose fluctuations.