Bcl-2、Bax、Insulin在高脂诱导C57BL/6J小鼠胰岛损伤中的表达

Expression of Bcl-2,Bax and Insulin in Pancreatic Islet Injury of C57BL/6J Mice Induced by High Fat Diet

目的探讨细胞凋亡因子在高脂引起的小鼠胰岛损伤中的表达。方法雄性C57BL/6J小鼠分高脂饮食组(HFD)和低脂饮食对照组(LFD),每组6只,喂养12周时尾部取血进行葡萄糖耐量实验(GTT)及胰岛素耐量实验(ITT)检测胰岛功能。持续喂养至20周时处死取胰腺组织用于透射电镜,苏木素-伊红(haematoxylineosin,HE)染色观察胰岛形态;免疫组化(immunohistochemical,IHC)检测Bcl-2、Bax及Insulin蛋白表达水平。结果喂养12周后,小鼠GTT和ITT显示,HFD组小鼠葡萄糖负荷时的血糖水平高于LFD组(P<0.05)。注射胰岛素后,HFD组小鼠血糖下降缓慢且血糖水平仍较LFD组高(P<0.05)。HE结果显示HFD组小鼠胰岛数量和体积较LFD组减少,形态损伤严重。电镜下观察HFD组胰岛β细胞超微结构受损较LFD组严重,HFD组β细胞形态不规则,细胞核固缩,染色质边集,有大量电子密度较小的脂滴堆积,其中胰岛细胞胞浆内胰岛素分泌颗粒减少。免疫组化的结果显示:HFD组Bcl-2表达低于低脂组,同时HFD组Bax表达高于LFD组,而HFD组胰岛中的Insulin表达低于LFD组(P<0.01)。结论高脂导致C57BL/6J小鼠胰岛细胞结构功能损伤,影响胰岛素的合成与分泌,并且增加细胞凋亡。Bcl-2及Bax在胰岛细胞凋亡中起一定的作用,并可能与高脂饮食有关。

Objective To investigate the expression of apoptotic factors in islets of mice induced by high fat.Methods C57 BL/6 J male mice were divided into high fat diet group（HFD）and low fat diet control group（LFD）,with 6 rats in each group. At 12 weeks,the glucose tolerance and insulin tolerance test were used to detect the islet function. The pancreas tissue was sacrificed at 20 weeks for transmission electron microscopy,and haematoxylin-eosin（HE）staining was used to observe the morphology of the islet,and the expression of Bcl-2,Bax and Insulin protein was detected by immunohistochemical（IHC）. Results After 12 weeks of feeding,glucose tolerance and insulin tolerance test in mice showed that the glucose level of HFD group was higher than that of group LFD（P0.05）. After injection of insulin,blood glucose in groupHFD decreased slowly and blood glucose level was higher than that in group LFD（P〈0.05）. HE results showed that the number and volume of islets in HFD group were lower than those in LFD group,and the morphological damage was serious. Under electron microscope,the ultrastructure of islet beta cells in groupHFD was damaged more seriously than that in group LFD. In groupHFD,the morphology of beta cells was irregular,nuclear condensation,chromatin set,and a large number of small electron density lipid droplets accumulated,and insulin secreting granules in the islet cell cytoplasm decreased. The results of immunohistochemistry showed that the expression of Bcl-2 in groupHFD was lower than that in low fat group,while the expression of Bax in groupHFD was higher than that in group LFD,and the expression of Insulin in groupHFD was lower than that in group LFD（P〈0.01）.Conclusion High fat can induce structural damage of islet cells in C57 BL/6 J mice,affect insulin synthesis and secretion,and increase cell apoptosis. Bcl-2 and Bax play a role in the apoptosis of islet cells and may be related to the high fat diet.