糖尿病大鼠瘦素和下丘脑瘦素功能受体的表达与胃排空的关系

目的探讨糖尿病不同阶段胃排空障碍与血清瘦素及其下丘脑OB-Rb表达的关系。方法40只Wistar大鼠随机分为对照饲养1周组（NC1组；n=6）、对照饲养4周组（NC2组；n=6）、糖尿病造模1周组（DM1组；n=14）和糖尿病造模4周组（DM2组；n=14）。分别于给药后1周、4周用酚红灌胃法检测胃排空；用放射免疫法、半定量RT—PCR技术检测大鼠血清瘦素及其下丘脑OB-Rb mRNA的表达。结果注射STZ1周后，DM1组大鼠血清瘦素明显低于NC1组（P〈0．05）；下丘脑OB-Rb mRNA表达明显低于NC1组；液体胃排空是加快的（P〈0．01）。注射STZ4周后，DM2组大鼠血清瘦素和胃排空明显低于NC2组（P〈0．05；P〈0．01）；DM2组下丘脑组织OB—Rb mRNA的表达明显高于NC2组（P〈0．05）。结论Ⅰ型糖尿病早期，机体可能通过降低血清瘦素和反应性的下调下丘脑OB-Rb表达，以加快胃排空。维持能量平衡。而长期高血糖及低瘦素水平可能反馈性的引起下丘脑OB-Rb表达上调，参与胃排空延迟。

The relationship between gastric emptying and expression of Leptin in diabetic rats

Objective Aim To explore the relationship between gastric emptying and expression of leptin and its receptor in different diabetic stages. Methods Fourty Wistar rats were randomly divided into four groups: 1-week normal control group(NC 1 group; n=6), 4-week normal control group (NC2 group;n=6), 1- week diabetes mellitus group (DM 1 group; n = 14)and 4-week diabetes mellitus group (DM2 group ; n = 14). One week and four weeks after the STZ injection, gastric emptying measured by intragastric administration of phenol red;serum leptin concentrations were measured with that of radioimmunoassay; expression of OB-Rb mRNA in hypothalamus was detected with semi-quantitative RT-PCR. Results 1-week after the STZ injection, the expression of serum leptin and OB-Rb mRNA in hypothalamus of DM1 group was decreased signifieantly compared with that of the control (P ＜0.05;P ＜ 0.05) ;DM1 group showed significantly accelerated rates of gastric emptying of the fluid compared with that of the NC1 group (P ＜ 0.01). 4-week after the STZ injection, serum leptin and gastric emptying of the DM2 group decreased significantly compared with that of the NC2 group(P ＜0.05; P ＜ 0.01). Oppositely, the expression of OB-Rb mRNA in the hypothalamus of DM2 group increased significantly(P＜0.05). Conclusion The decreased serum leptin and OB-Rb in the hypothalamua on the short-term hyperglycemia may participate in the rapid gastric emptying and increase ingestion reaction, which can maintain energy balance of the body. The high expression of OB-Rb in the hypothalamus may be a protective mechanism that it could increase leptin sensitivity to inhibit gastric emptying on the long-term hyperglycemia.