Effects of long-term high-protein diet on expressions of IRS2 and GLUT2 in the liver of diet-induced obese rats

Objective To investigate the effects of long-term high-protein diet on expressions of IRS2 and GLUT2 in the liver of diet-induced obese rats.Methods Diet-induced obese rat models were established by feeding Wistar rats(n=34) a high-calorie and high-fat diet.The obese male rats were randomly divided into three groups: the high-protein diet group(HP group,n=12,protein: 36.7%),the high-fat diet group(HF group,n=11,fat: 38.3%),and the normal food group(NC group,n=11).The total calorie ingestion of each rat per day was similar and consistent for 24 weeks.After 24 weeks,fasting blood glucose(FBG) and fasting blood insulin(FINS) were assayed and QUICKI was calculated to evaluate the insulin sensitivity.mRNA and protein expressions of IRS2 and GLUT2 were determined by RT-PCR and the Western blot method.Results The insulin sensitivity index(QUICKI) of the HP group was 11.31% higher(P0.05)than that of the NC group.Also,among the HP group,the IRS2 mRNA and protein were 16%(P0.05) and 24%(P0.05)higher,while the GLUT2 mRNA and protein were 24%(P0.05) and 25%(P0.05)higher.However,the corresponding indicators of the HF group,compared with those of the NC group,were remarkably low.Conclusion A long-term high-protein diet can raise expressions of IRS2 and GLUT2 in the liver of diet-induced obese rats.This may be one of the mechanisms of how a long-term high-protein diet can improve the insulin sensitivity of diet-induced obese rats.