Effect On Islet Cell Apoptosis In Diabetic Rats After The Blockage Of The Local Pancreatic Rennin-angiotensin-aldosterone System At Different Sites

ObjectiveTo study the effect of the local renin-angiotensin-aldosterone system on islet cell apoptosis in diabetic rats and view the effect of benazepril alone or in combination of spironolactone on islet cell apoptosis in diabetic rats.Methods32 healthy adult male Wistar rats were randomly divided into four groups, namely normal control group(NC group), diabetes mellitus without intervention group(DM group), benazepril intervention group(BEN group) and benazepril combined with spironolactone intervention group(SPI group).There are eight rats in each group. NC group was fed with the normal diet. The remaining 3 groups rats given high fat high sugar diet for 6 weeks.After, using small dose (30mg/kg) streptozotocin intraperitoneal injecting to Modeling type 2 diabetic rat. After the success of modeling, BEN group and SPI group were respectively intervened by intragastric administration with benazepril (1mg/kg) and benazepril (1mg/kg) plus spironolactone (2mg/kg),when 8 o'clock every morning,The remaining two groups were given intragastric saline 2.5ml every morning 8:00. More than of drug intervention for 8 weeks.During the experiment, blood glucose and body weight change were monitered.To anesthetize rats by 10% chloral hydrate intraperitoneal injection. We took the required samples,rats were killed. Radioimmunoassary was used to detect the levels of pancreatic angiotensin II, aldosterone and serum insulin levels. The expression of myocardial TGF-β1, Smad3 and Smad7 protein was determined by immunohistochemistry. Pancreatic ultrastructure was observed by the electron microscopy.the parameters were shown by x±s.They were analyzed using SPSS13.0.using analysis of variance to comparing between groups. Results1. The levels of pancreatic angiotensinⅡ, aldosterone each group:The levels of pancreatic angiotensin II in NC group is lower than DM group, BEN group and SPI group, the difference was statistically significant. After drug interventing,the angiotensinⅡof BEN group and SPI group was decreased, the difference was statistically significant, but there is no difference between the two groups.The levels of pancreatic aldosterone in NC group is lower than DM group, BEN group and SPI group, the difference was statistically significant. After drug interventing,the aldosterone of BEN group and SPI group was decreased, the difference was statistically significant, but there is no difference between the two groups.2.The expression of myocardial TGF-β1, Smad3, Smad4 protein each group:The levels of pancreatic TGF-β1, Smad3, Smad4 protein in NC group is lower than DM group, BEN group and SPI group, the difference was statistically significant. After drug interventing,the TGF-β1, Smad3, Smad4 protein of BEN group and SPI group was decreased, the difference was statistically significant, but there is no difference between the two groups.3.Apoptosis of islet cells in each group:Ultrastructure of most of the pancreatic P cell were normal in NC group. There was mitochondrial swelling, mitochondria fuzzy, rough endoplasmic reticulum expansion and degranulation, the Golgi complex enlargement, secretory granules decreased in cytoplasm, vacuole-like particles increased significantly, nuclear chromatin margination the nucleus gap widened, the local nuclear membrane disappears. Secretory granules cytoplasmic of BEN group and the SPI group increase in pancreatic,and the apoptosis ofβ-cell was not obvious.ConclusionLocal RAAS of pancreatic induced apoptosis of islet cells in diabetic rats induced apoptosis in diabetic rats by TGF-β/Smad signal transduction pathway.Benazepril and Benazepril combining spironolactone can inhibit the apoptosis of islet cells, but there is no difference between the two groups.