Primary Study On The Effect Of FoxO1 Expression On Pancreatic Islet β-Cell Apoptosis In Type 2 Diabetic Rat

PARTⅠTHE EXPRESSION OF FOXO1 AND CASPASE-3 IN ISLET B-CELLS OF TYPE 2 DIABETIC RATObjective:To explore the expression of forkhead transcription factor FoxO1 and caspase-3 in the isletβ-cell of type 2 diabetic rat.Methods:Male SD rats,weighing(170±20.5)g,were housed under controlled temperature conditions and a 12h light/12h dark circle. Hyperglycemia was induced by the intraperitoneal injection of streptozotocin(30mg/kg).After 72h following streptozotocin administration,blood was collected from tail vein and was analyzed for blood glucose.Animals showing fasting blood glucose higher than 300mg/dl(16.7mmol/L) were considered as type 2 diabetic rats and used for this study.Animals were divided into two groups:(1) control group: Rats treated with normal diet for 16 weeks;(2) diabetic group:Diabetic rats treated with fat-glucose-rich-diet for 16 weeks.Then to observe the rats' pathological changes of pancreatic tissue;the expression of FoxO1 and caspase-3 were detected by immunohistochemistry.Results:Rat model of type 2 diabetes mellitus was constructed successfully.Compared with the control group rats,not only the amount of pancreatic island significantly decreased(P＜0.01),the construction of pancreatic island also significantly changed.Transcription factors FoxO1 mainly expressed in the nucleus in the diabetic rat isletβcells while in the control group mainly expressed in the cytoplasm.Caspase-3 expressed in pancreatic isletβcells of both diabetic rats and normal rat,but their levels had significantly different.Furthermore,the pancreatic isletβcells of their expressing FoxO1 in nuclear just were that of higher expressing the caspase-3.Conclusions:FoxO1 relatively specificly expressed in the pancreatic isletβ-cell,which may be associate with the apoptosis of pancreatic isletβ-cell.PARTⅡEFFECT OF FOXO1 ON THE APOPTOSIS IN PANCREATIC ISLET B-CELL OF DIABETIC RATObjective:To explore the relation between higher expressing forkhead transeription factor FoxO1 in the nuclear of pancrestic isletβcell and apoptosis of pancreatic isletβ-cell in diabetic rat.Methods:Until the pancreas paraffin sections of diabetic rat model were made,the expression of FoxO1 and caspase-3 were detected by immunohistochemistry;TUNEL was applied to examine apoptoticβcell in pancreatic sections;Immunofluorescence combined TUNEL fluorescence detection observed the relation among FoxO1,caspase-3 and apoptosis.Results:Compared with the control group rats,there were higher FoxO1,caspase-3 expression and apoptosis in diabetic group(P＜0.01). Moreover,the level of FoxO1 and caspase-3,TUNEL were positively correlated(P＜0.01).FoxO1 and caspase-3 immunofluorescence combined TUNEL fluorescence detection displayed:the islet cells which higher expressed FoxO1 and caspase-3 in nuclear just were the apoptotic islet cells.Conclusions:Transcription factor FoxO1 may be involved in regulating type 2 diabetes isletβcell apoptosis.