【摘要】 本工作探讨了大鼠饥饿时胰岛素分泌减少的机制。大鼠连续饥饿1至4d,其血浆胰岛素水平的变化不与血糖平行,二者虽均于饥饿第1天即显著下降,但胰岛素在饥饿期间一直维持于低水平。而血糖则于饥饿第3天开始回升,第4天接近正常水平。在离体实验中发现,禁食3d大鼠的离体灌流胰腺对精氨酸的胰岛素分泌反应明显地低于正常摄食大鼠。看来,饥饿时胰岛素分泌的减少似不是由于营养物质对胰岛β细胞刺激作用的减弱,而可能是由于局部抑制性影响加强所致。 我们进一步观察了胰内生长抑素的作用,发现饥饿3d的大鼠,在胰岛素分泌减少的同时,胰腺生长抑素的含量增高,如预先给动物注射半胱胺以耗竭内源性生长抑素,则使饥饿大鼠胰岛素分泌的抑制现象明显减轻。在离体实验中也发现,预先注射半胱胺的饥饿大鼠,其离体灌流的胰腺对精氨酸的反应恢复正常。这些结果提示,胰内生长抑素对β细胞局部抑制作用的增强,可能是饥饿引起胰岛素分泌减少的机制之一。更多还原

【Abstract】 In the present work, we have investigated the possible mechanism of sup-pression of insulin release during starvation. When the rats were starved for 1to 4 days, the variations of their plasma insulin level were not parallel to that ofplasma glucose, although both decreased markedly on the first day of starvation,the plasma insulin remained at this low level throughout the period of starvation,despite the plasma glucose began to rise on the third day and reached to the normallevel on the fourth day of starvation. The in vitro experiments also showed,that the arginine stimulated insulin release in the perfused pancreases, isolatedfrom the rats starved for 3 days, were much lower than that from the regularly fedrats. It is likely that the suppression of insulin release during starvation is notowing to the decrease of stimulation exerted on the B cells by nutrients, and it maybe resulted by the increase of local inhibitory effect. In the further investigation, we have observed the role of pancreatic somatosta-tin, and found that the pancreatic contents of somatostatin in intact animals starvedfor 3 days increased in parallel with the decrease of plasma insulin level, whereas,after pretreatment with cysteamine to deplete endogenous somatostatin, the sup-pression of insulin releases in these starved rats was abolished significantly. Besides,in vitro, the suppression of arginine stimulated insulin release of perfused isolatedpancreases of cysteamine pretreated starved rats was also reversed. These resultssuggest that the increase of local inhibitory effect exerted by pancreatic somatostatinon the B cells might be one of the mechanisms suppressing insulin release duringstarvation.更多还原