Vilches-Flores Alonso, Delgado-Buenrostro Norma Laura, Navarrete-Vázquez Gabriel, Villalobos-Molina Rafael
Unidad de Biomedicina, FES Iztacala, Universidad Nacional Autónoma de México, Av. de Los Barrios 1, Los Reyes Iztacala, C.P. 54090, Tlalnepantla, Mexico.
Regul Pept. 2010 Aug 9;163(1-3):81-7. doi: 10.1016/j.regpep.2010.04.013. Epub 2010 May 5.
Endocannabinoid system is involved in food intake and energy balance. Beside the hypothalamus, pancreatic islet also expresses CB1 cannabinoid receptor, however little is known about its physiological role and regulation. Since gene expression of many specific proteins of the islet depends on the concentration of glucose, we studied CB1 receptor expression in response to fasting and feeding. Whole pancreas or islets were isolated from food-deprived adult Wistar rats, with or without a previous 1.5 g/kg glucose oral-intake. CB1, insulin and glucagon expressions were analyzed by confocal immunofluorescence and PCR. In vitro, rat islets were cultured at different glucose concentrations, in the presence of anandamide, or with Rimonabant analog BAR-1. CB1, insulin, glucagon, glucokinase, and PDX-1 expression were determined by real-time RT-PCR, and insulin secretion and islet content by ELISA. CB1 expression in pancreatic islets is upregulated during food restriction, and decreases in response to glucose intake or feeding. In cultured islets, 16 mmol/l glucose, BAR-1, and anandamide at low glucose reduced CB1 mRNA. Insulin, glucagon, glucokinase and PDX-1 expression increased in islets treated with anandamide at low glucose, while BAR-1 modified PDX-1 and glucagon mRNA at high glucose. Basal insulin secretion and insulin content in islets increased with anandamide, but not the glucose-stimulated response. Our results suggest that the endocannabinoid system has an important role in gene expression on islets and its close relationship with glucose response.
内源性大麻素系统参与食物摄入和能量平衡。除下丘脑外，胰岛也表达CB1大麻素受体，但其生理作用和调节机制尚不清楚。由于胰岛中许多特定蛋白质的基因表达取决于葡萄糖浓度，我们研究了禁食和进食对CB1受体表达的影响。从禁食的成年Wistar大鼠中分离出全胰腺或胰岛，部分大鼠在分离前口服1.5 g/kg葡萄糖。通过共聚焦免疫荧光和PCR分析CB1、胰岛素和胰高血糖素的表达。在体外，将大鼠胰岛在不同葡萄糖浓度下培养，同时加入花生四烯乙醇胺或利莫那班类似物BAR-1。通过实时RT-PCR测定CB1、胰岛素、胰高血糖素、葡萄糖激酶和PDX-1的表达，并通过ELISA测定胰岛素分泌和胰岛含量。在食物限制期间，胰岛中CB1的表达上调，而对葡萄糖摄入或进食有反应时则降低。在培养的胰岛中，16 mmol/l葡萄糖、BAR-1和低葡萄糖浓度下的花生四烯乙醇胺可降低CB1 mRNA。低葡萄糖浓度下用花生四烯乙醇胺处理的胰岛中，胰岛素、胰高血糖素、葡萄糖激酶和PDX-1的表达增加，而BAR-1在高葡萄糖浓度下可改变PDX-1和胰高血糖素mRNA。胰岛中的基础胰岛素分泌和胰岛素含量随花生四烯乙醇胺增加，但葡萄糖刺激反应未增加。我们的结果表明，内源性大麻素系统在胰岛基因表达中起重要作用，并且与葡萄糖反应密切相关。
