Short-Term Comparison Of Treatment Effect Of Gastric Bypass Surgery And Exogenous Insulin Administration For Type 2 Diabetic Rats

ObjectiveTo compare the therapy of gastric bypass surgery and exogenous insulin administration for streptozotocin-induced type 2 diabetic rats in terms of short-term treatment effect and changes of pancreatic islet cells morphology.MethodsDiabetic models were established by intraperitoneal administration of streptozotocin(STZ) to male SD rats. The rats were randomly divided into the control group,insulin group,and gastric bypass group. The rats were closely monitored after the surgery in period of 1 week,4 weeks and 12 weeks. The three groups were compared in terms of changes of weight, fasting plasma glucose and fasting C-peptide level to study the therapeutic effect of different treatements. The rats were sacrificed for the pancreas after 12 weeks. Sections of pancreas were performed in addition to immunohistochemical study. Numbers and changes in secretion of islet cells were examined.Results1. There are no significant differences of body weight of rats between three groups at the first week of post-operation (P> 0.05). In the forth and twelfth weeks of post-operation, the body weight of rats in GBP group are lesser than control group and insulin group (P<0.05).There are no significant differences of body weight of rats between control group and insulin group at the forth weeks of post-operation (t=-0.970, P= 0.343> 0.05).The body weight of rats in control group are lesser than in the insulin group at twelfth weeks of post-operation (t=-3.657, P=0.001<0.05).2. In first week, forth weeks and twelfth weeks of post-operation, the fasting glucose is reduce in insulin group which compare with that of control group and GBP group (P<0.05), the fasting glucose of GBP group are reduce which compare with control group at first week, forth weeks and twelfth weeks of post-operation(P<0.05).3. There are no significant differences of fasting C-peptide levels between three groups at the first week of post-operation (P> 0.05).The fasting C-peptide levels of GBP group and insulin group are increase which compare with control group at forth and twelfth week of post-operation(P<0.05). There are no significant differences of the fasting C-peptide levels of GBP group and insulin group at forth weeks of post-operation (t=-1.311, P=0.203> 0.05). The fasting C-peptide in GBP group are increase which compare with insulin group at twelfth weeks of post-operation (t=5.407, P=0.000<0.05).4. The average number of islets in GBP is increase in control group and insulin group at the twelfth weeks of post-operation (P<0.05).There are no significant differences of average number of islets between insulin group and control group at the twelfth week of post-operation(t=0.408, P=0.687>0.05).5. The average gray value of insulin immunohistochemistry in GBP group is reduce which compare with control group and insulin group at the twelfth week of post-operation(P<0.05).The average gray value of insulin immunohistochemistry in insulin group is reduce which compare with control group at the twelfth week of post-operation (t=-5.251, P=0.0000.05)Conclusions1. Gastric bypass surgery is an effective treatment for type 2 diabetic rats, islet cell hyperplasia with increased secretion of insulin were documents. The underlying mechanism awaits further research.2. The insulin group showed better glucose lowering effect than that of the gastric bypass group during short-term observation.3. Treatment of gastric bypass surgery, by short-term observation, showed promotion of hyperplasia of islet cells and improved insulin secretion. Effect on the islet cells is better than that of the insulin group. Long-term effect awaits further verification.