Gastric Bypass Surgery For The Hypoglycemic Effect Of Obese Type 2 Diabetic Rats And Its Mechanism

Objective: To investigate the effect of Roux-en-Y gastric bypass (RYGB) on glucosemetabolism in non-obese Goto-Kakizaki (GK) type2diabetic rats and its mechanism.Methods: Eighteen male GK rats and eighteen male Wistar rats were randomlydivided into four groups: GK operation group (group A), GK sham operation group(group B), Wistar operation group (group C), Wistar sham operation group (group D).There were9rats in each group. The body weight, food intake, fasting blood glucoseand insulin levels were measured before and after the operation. Oral glucosetolerance test (OGTT) was measured before and on the8th week after the operation.The area under blood glucose concentration curve (AUC) was calculated. Liver tissuewas harvested8weeks postoperatively and reverse transcriptase polymerase chainreaction was used to detect liver GCK mRNA expression after the operation．Results:(1) Body weight and food intake: One week after surgery, the body weightand average food intake decreased apparently among all groups (P＜0.05), andgradually increased from the2nd week until8th week after surgery. During the8-week follow-up period, there was no significant statistical differences in both bodyweight and food intake between group A and B, so was group C and D (P＞0.05).(2)Fasting blood glucose: The fasting blood glucose of group A decreased as early as the1st week after surgery, which decreased from preoperative (8.731.30)mmol/L to(6.840.89),(5.600.84),(6.210.71),(6.270.93),(5.860.57)mmol/L on the1st,2nd,3rd,4th and8th week postoperation (P＜0.05), and the glycemia remainedconsistently lower in group A with respect to group B. The fasting blood glucose ofgroup B, C and D had no significant changes through the entire follow-up period.(3)Fasting serum insulin: Fastingg serum insulin concentration rose from (17.303.24)mU/L preoperative to (19.484.73),(20.165.09),(22.354.91)mU/L on the1st,4th and8th week postoperation (P＞0.05), and the insulin level remained consistentlylower in group A with respect to group B, but there was no significant changes during the follow-up period (P＞0.05).(4) Area under blood glucose concentration curve(AUC): On the8th week after surgery，the glucose tolerance was strikingly improvedin group A, as demonstrated by a20.6%reduction of the AUC, which decreased frompreoperative (60.235.14)mmol·h/L to (47.804.85) mmol·h/L (P＜0.05). AUC ofgroup A was lower than that of group B at the same checking point (P＜0.05). TheAUC of blood glucose concentration had no significant changes among group B, Cand D (P＞0.05).(5) Liver tissue GCK mRNA level: On the8th week after surgery，the liver GCK mRNA level in group A was significantly higher than group B (p＜0.05), while there was no significanct differences in group C and D.Conclusion: Roux-en-Y gastric bypass can directly improve glucose metabolism innon-obese type2diabetic rats, independently of effects on body weight and foodintake. The increased expression of liver tissue GCK mRNA might contribute to thehypoglycemic effect of the surgery.