干预糖毒性对肥胖大鼠胰岛β、α细胞功能改善的作用

目的 探讨糖毒性对肥胖大鼠胰岛β、α细胞功能及分子生物学的损害作用.方法 雄性SD大鼠36只分为4组:(1)正常组:9只,普通饲料喂养.(2)高脂组:9只,高脂饲料喂养.(3)DM对照组:9只,不给予药物干预.(4)糖毒性干预组:9只,皮下注射超长效甘精胰岛素(5 U·kg-1·d-1)降低血糖,共4周.所有大鼠在实验结束时,通过免疫组化观察分析胰岛β、α细胞形态学特点,RT-PCR测定胰腺内胰岛素原mRNA表达水平,Western印迹方法检测胰腺中胰岛素蛋白质含量,胰岛素干预2周和4周后复测葡萄糖耐量试验.结果 糖毒性干预组,胰岛内β细胞比糖尿病对照组相对量增加(分别为0.38±0.08,0.11±0.05,P＜0.01),β细胞浆内胰岛素水平增加(分别为0.58±0.03,0.34±0.14,P＜0.01),胰岛素原mRNA表达增加(分别为1.52±0.14,1.26±0.14,P＜0.01);Western印迹检测胰岛素蛋白质含量明显升高;胰岛内α细胞相对量减少(分别为0.28±0.15,0.16±0.04,P＜0.01).结论 干预糖毒性4周能显著改善糖尿病大鼠胰岛β、α细胞的病理学变化,部分恢复胰岛细胞的功能.

Improvement of the function of islet β and α cells by intervention against glucotoxicity:experiment with rats

Objective To investigate the effects of intervention against gbacotoxicity on improvement of the function and pathological changes of islet β and α cells.Methods Thirty-six male Sprague Dawley rats were randomly divided into four equal groups:normal control(NC)group,fed with standard chow,high-fat(HF)group,fed with extra high-fat chow;diabetes mellitus(DM)control group,fed with high-fat chow for 8 weeks followed by 30 mg/kg streptozotocin iniection to establish DM models;and insulin(INS) group,treated with subcutaneous injection of long-acting insulin(glargine,0.5 U·kg-1·d-1)for 4 weeks after the establishment of DM models.48 h,2 weeks,and 4 weeks after the STZ injection to the 2 DM groups oral glucose tolerance test(OGTT)was performed to all rats.Peripheral blood samples were collected from the caudal vein.Serum insulin level was assayed by radioimmunoassay.Total serum cholesterol(TC) and triglyceride(TG)were measured by enzyme-colorimetric method.By the end of experiment the rats were killed with their pancreases taken out.Immunohistochemistry was used to observe the morphological changes of the islet β and α cells.β cell and α cell masses were calculated by the proportions of positive area in the islet.Proinsulin mRNA level was detected by RT-PCR.Insulin protein content in islets was detected by Western blotting.Results Four weeks after the insulin intervention against glucotoxicity,the fasting blood glucose and blood glucose 2 h after sugar-taking of the INS group were both significantly lower than those of the DM group(both P＜0.01).The relative β cell mass of the INS group was 0.38±0.08,significantly bigger,2.45 times,that of the DM group(0.11 ±0.05,P＜0.01).The relative α cells mass in islets of the INS group was 0.16±0.04,significantly lower,by 43%,than that of the DM group(0.28±0.15,P＜0.01).The insulin contents in β cells of the INS group was 0.58±0.03,significantly higher,by 70.6%,than that of the DM group(0.34±0.14,P＜0.01).The proinsulin mRNA level of the INS group was 1.52±0.14,significantly higher,by 20.6%,than that of the DM group.Conclusion The morphology of islet β、α cells in diabetic rats was improved by four weeks of Intervention against glucotoxicity improves the pathology of islet β and α cells in diabetic and insulin synthesis.