Effects Of Roux-en-Y Gastric Bypass Surgery On The Apoptosis Of Islet B-cell In Type 2 Diabetes Mellitus(T2DM) Rats

Objective To investigate the effect of Roux-en-Y gastric bypass(RYGB) in type 2 diabetes mellitus(T2DM) rats.Methods 60 male SD rats were included in the study; then the rats were randomly divided into three groups, normal sham-operated group(C, n=20), type 2 diabetic control rats(gastric bypass group(RYGB, n=20 and sham-operated group(S-RYGB, n=20)). Type 2 diabetic control rats were induced to diabetes by injection low dose of streptozotocin(STZ)(25mg/kg) at the 14 th day and fed with high-fat diet. C group were injection with the same dose volume of vehicle citrate buffer(p H 4.4) and fed with normal diet. After 72 h, the fasting blood glucose level of the rats above 16.7mmol/L were considered as successful models. One week later, surgical interventions were implemented. For all groups, fasting blood-glucose and body weight were measured in 1th, 2th, 3th and 4th week before and after operation. Rats were decapitated to retrieve the pancreas after 4 weeks of the operation. The apoptosis of the islet β-cells was detected by using TUNEL assay. The apoptosis-related proteins, like β-catenin and caspase12 were viewed by immunohistochemistry SABC method.Results There were no significantly in three groups of weight(P>0.05); but as fasting blood glucose in C group is significantly lower than it in the other groups(P<0.05). Compared with S-RYGB, the weight and fasting blood glucose were significantly lower in RYGB at 2th, 3th, 4th week after operation. The apoptosis rate of the islet β-cells was(4.01±0.39)% in RYGB group, which were lower than those in S-RYGB group at 4th week of the postoperative(P<0.05), but no significantly compared with C(P>0.05). By immunohistochemistry, the expression of β-catenin in RYGB group was 78.5%, which is significantly higher than those in S-RYGB(P<0.05), but the expression of caspase-12 was 35.7 %, which was significantly lower than those in S-RYGB(P<0.05).Conclusions RYGB surgery can significantly reduce the blood glucose level, body weight and up-regulate the expression of β-catenin but down-regulate the expression of caspase-12. Maybe the wnt/β-catenin pathway play a role of apoptosis and the change of blood glucose level.