辣椒素在小鼠瘤βTC-6细胞中降糖机制的研究

HYPOGLYCEMIC MECHANISM OF CAPSAICIN IN βTC-6 MOUSE INSULINOMA CELLS

目的探讨辣椒素对小鼠瘤βTC-6细胞胰岛分泌功能的作用及其相关的降糖机制。方法(1)辣椒素对小鼠瘤βTC-6细胞增殖率的影响:在不同浓度的辣椒素(0、10、50、100、200、300μmol/L)作用下,测定小鼠瘤βTC-6细胞的增殖率、胰岛素分泌量和胞内Ca2+的浓度;(2)辣椒素受体(TRPV1)调控试验:筛选合适剂量辣椒素(50μmol/L)和辣椒卓平(15μmol/L),培养48 h后测定TRPV1、胰腺十二指肠同源异形盒1(PDX-1)、胰岛素受体底物1(IRS1)、胰岛素受体底物2(IRS2)和葡萄糖转运蛋白2(GLUT2)在βTC-6细胞中的蛋白水平。结果辣椒素能够抑制βTC-6细胞增殖,其胞内Ca2+浓度与胰岛素分泌功能密切相关,且辣椒素能显著上调TRPV1、PDX-1、IRS1、IRS2和GLUT2的蛋白水平,但TRPV1通道被辣椒卓平阻断后,这种上调作用显著减弱。结论 (1)在辣椒素剂量为0~50μmol/L条件下,βTC-6胞内Ca2+浓度与其胰岛素分泌量正相关;(2)辣椒素对胰岛细胞的刺激是其降糖作用的主要来源,与胰岛细胞的增殖无关,且胰岛细胞中可能存在TRPV1–PDX-1–GLUT2/IRS1信号通路。

Objective To study the effect of capsaicin on stimulating the βTC-6 mouse insulinoma cells and related mechanism. Methods （1） The influence of capsaicin on βTC-6 cell proliferation rate, insulin secretion and intracellular Ca^2＋ concentration of βTC-6 cell were measured under the different concentrations of capsaicin （0, 10, 50, 100, 200 and 300 μmol/L）; （2） The protein levels of transient receptor potential vanilloid 1 （TRPV1）, pancreatic duodenum homeobox 1 （PDX-1）, insulin receptor substrate 1 （IRS1）, insulin receptor substrate 2 （IRS2） and glucose transport protein 2 （GLUT2） in βTC-6 cells were measured after cultured 48 hours with the addition of capsaicin （50 μmol/L） and capsazepin （15 μmol/L）. The dosage used in the experiment was based on βTC-6 cell proliferation experiment. Results Cell proliferation was markedly inhibited by capsaicin. The intracellular Ca^2＋ concentration in βTC-6 cells was closely related to insulinm secretion. More importantly, the protein levels of TRPV1, PDX-1, IRS 1, IRS2 and GLUT2 were significantly up-regulated by capsaicin However, this up-regulation was significantly reduced after the TRPV1 ion channels was blocked by capsazepin. Conclusion （1） The positive correlations between intracellular Ca^2＋ concentration and insulin secretion were observed when the concentration of capsaicin ranged from 0 to 50 μmol/L; （2） The hypoglycemic effect of capsaicin was mainly contributed by its stimulation effect on islet cells, not by proliferation of islet cells. The signaling pathways of TRPV1- PDX-1- GLUT2/IRS 1 may co-exist in islet cells.