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本研究旨在探讨尾加压素II(urotensin II,UII)对胰岛β细胞功能的影响及其机制。在整体实验中,采用Wistar大鼠进行糖耐量试验,检测不同剂量UII(3、30、300nmol/kg)对大鼠血糖和胰岛素水平的影响;在细胞实验中,βTC-6细胞孵育实验检测UII对葡萄糖引起的胰岛素分泌(glucose-induced insulin secretion,GIIS)的影响,酸化乙醇抽提法和实时荧光定量PCR分别测定细胞内胰岛素含量和mRNA的水平,Western blot检测胰十二指肠同源盒1(pancreatic duodenal homeobox-1,PDX-1)和葡萄糖激酶(glucokinase,GCK)表达水平。糖耐量试验结果显示,相对对照组,急性静脉注射较高剂量的UII(30、300nmol/kg)使大鼠血浆胰岛素浓度在腹腔注射葡萄糖后15min显著下降,并且使大鼠血糖在腹腔注射葡萄糖后90min明显升高。βTC-6细胞孵育实验结果显示,UII孵育2h能抑制βTC-6细胞的GIIS,但是对细胞内的胰岛素含量和mRNA水平没有影响。UII对GIIS的抑制作用可以被UII受体拮抗剂urantide所阻断,部分被蛋白激酶C(protein kinase C,PKC)非特异性抑制剂chelerythrine chloride(CTC)和生长抑素受体非特异性拮抗剂cyclosomatostatin(CSS)所阻断。Western blot结果显示,UII抑制了βTC-6细胞内GCK的表达,但对PDX-1表达量没有影响。以上结果表明,UII通过激活其特异性受体(较高浓度的UII可能同时激活生长抑素受体)抑制胰岛β细胞GIIS,其作用机制涉及PKC通路的激活、GCK表达受抑所引起的胰岛素颗粒胞吐作用的减弱,但不涉及胰岛素本身表达的下降。
This study aimed to investigate the effects of urotensin II (UII) on pancreatic β-cell function and its mechanism. In the whole experiment, the Wistar rats were used for glucose tolerance test to test the effect of different doses of UII (3, 30, 300nmol / kg) on blood glucose and insulin level in rats. In the experiment of cells, βTC-6cells incubation test was used to detect UII The effect of glucose-induced insulin secretion (GIIS), acidified ethanol extraction and real-time fluorescence quantitative PCR were used to determine the content of intracellular insulin and mRNA, Western blot was used to detect the pancreaticoduodenal homeobox 1, pancreatic duodenal homeobox-1 (PDX-1) and glucokinase (GCK). Glucose tolerance test results showed that the acute intravenous injection of higher doses of UII (30,300 nmol / kg) significantly decreased rat plasma insulin concentration 15 min after intraperitoneal injection of glucose compared with the control group, and the blood glucose of rats after intraperitoneal glucose injection 90min significantly increased. Incubation of βTC-6 cells showed that UII incubated for 2 h inhibited the GIIS of βTC-6 cells but had no effect on intracellular insulin levels and mRNA levels. The inhibitory effect of UII on GIIS can be blocked by the UII receptor antagonist urantide and partially blocked by chelerythrine chloride (CTC), a nonspecific inhibitor of protein kinase C (PKC), and cyclosomatostatin, a non-specific antagonist of somatostatin receptor (CSS) blocked. Western blot results showed that UII inhibited the expression of GCK in βTC-6 cells but had no effect on the expression of PDX-1. The above results indicate that UII inhibits islet β-cell GIIS by activating its specific receptor (higher concentration of UII may activate somatostatin receptor simultaneously), and its mechanism of action involves activation of PKC pathway, inhibition of GCK expression of insulin Granule exocytosis weakened, but does not involve the decline in the expression of insulin itself.