大鼠胰腺发育过程中Munc13-1对胰岛素释放功能的影响

目的:研究大鼠胰腺发育不同阶段Munc13-1基因及蛋白表达的变化及Munc13-1在胰岛素释放过程中的作用. 方法:应用显微分离及提取技术获得大鼠胚胎发育12.5d(E12.5),E15.5,E18.5,新生大鼠,出生后21 d(P21)及成年大鼠胰腺组织;另外,从大鼠胚胎发育15 d开始给予孕鼠半量饮食,造成宫内发育迟缓动物模型,提取其新生大鼠胰腺组织. 采用RT-PCR, Real-time PCR和Western blot技术确定Munc13-1的表达情况,并测定不同发育时期血中胰岛素浓度. 结果:胰岛素基因从E12.5开始出现,Munc13-1基因从E15.5开始表达,随着胎龄的增长,二者表达量皆增多. E15.5和E18.5时munc13-1蛋白表达量较少,以后明显增多. 自E18.5即检测到血中胰岛素的存在,随着胚胎的发育,血胰岛素浓度逐渐升高. 宫内发育迟缓新生大鼠比正常新生大鼠血胰岛素浓度低,同时Munc13-1基因及蛋白表达量亦比正常对照组明显减少. 结论:Munc13-1在胰岛素释放过程中的作用,随着胚胎发育期胰岛素分泌的增多表达也增加,宫内发育迟缓新生大鼠胰岛素分泌减少时,Munc13-1的表达亦减少.

Effect of Munc13-1 on insulin secretion during pancreatic development in rats

AIM: To investigate the expression of Munc13-1 during various stages of embryonic pancreatic development in rats and define the effect of Munc13-1 on insulin secretion. METHODS: Pancreata of rat embryonic day 12.5 (E12.5), E15.5, E18.5, new-born, 21 d after birth (P21) and adult rats were dissected under microscope respectively. In addition, the animal models of intrauterine growth retardation (IUGR) in rats were made by 50% calorie restriction in pregnant rats from gestational day 15 until term. After abstraction of totle RNA and protein, the techniques of RT-PCR, real-time PCR, Western blot and ELISA were used to study the expression of Munc13-1 and insulin secretion. RESULTS: The genes of insulin and Munc13-1 began to be expressed from E12.5 and E15.5 respectively and their expressions were increased as the fetus grew. The result of Western blot showed that the expression of Munc13-1 was low at E15.5 and E18.5 and increased later. Blood insulin level was detected at E18.5 and increased rapidly thereafter. The blood insulin level and the expression of Munc13-1 were reduced simultaneously in IUGR models compared with normal newborn rats. CONCLUSION: The expression of Munc13-1 is accordant to blood insulin level and plays an essential role in insulin exocytosis.