Development of Wistar rat model of insulin resistance

AIM: To establish a simplified and reliable animal model of insulin resistance with low cost in Wistar rats. METHODS: Wistar rats were treated with a high fat emulsion by ig for 10 d. Changes of the diets, drinking and body weight were monitored every day and insulin resistance was evaluated by hyperinsulinemic-euglycemicclamp techniques and short insulin tolerance test using capillary blood glucose. Morphologic changes of liver, fat, skeletal muscles, and pancreatic islets were assessed under light microscope. mRNA expressions of GLUT2 and α-glucosidase in small intestine epithelium, GLUT4 in skeletal muscles and Kir6.2 in beta cell of islets were determined by in situ hybridization.RESULTS: KITT was smaller in treated animals (4.5±0.9)than in untreated control Wistar rats (6.8±1.5), and so was glucose injection rate. Both adipocyte hypertrophy and large pancreatic islets were seen in high fat fed rats,but no changes of skeletal muscles and livers wereobserved. mRNA levels of GLUT2, α-glucosidase in small intestinal epithelium and Kir6.2 mRNA in beta cells of islets increased, whereas that of GLUT4 in skeletal muscles decreased in high fat fed group compared with normal control group.CONCLUSION: An insulin resistance animal model in Wistar rats is established by ig special fat emulsion.

Inhibition of small-intestinal sugar absorption mediated by sodium orthovanadate Na_3VO_4 in rats and its mechanisms

AIM: To investigate the inhibitory effects of sodium orthovanadate on small-intestinal glucose and maltose absorption in rats and its mechanism.METHODS: Normal Wistar rats were lavaged with sodium orthovanadate (16 mg/kg, 4 mg/kg and 1 mg/kg) for 6 d.Blood glucose values were measured after fasting and 0.5, 1, 1.5 and 2 h after glucose and maltose feeding with oxidation-enzyme method, α-glucosidase was abstracted from the upper small intestine, and its activity was examined.mRNA expression of α-glucosidase and glucose-transporter 2 (GLUT2) in epithelial cells of the small intestine was observed by in situ hybridization.RESULTS: Sodium orthovanadate could delay the increase of plasma glucose concentration after glucose and maltose loading, area under curve (AUC) in these groups was lower than that in control group. Sodium orthovanadate at dosages of 10 μmol/L, 100 μmol/L and 1000 μmol/L could suppress the activity of α-glucosidase in the small intestine of normal rats, with an inhibition rate of 68.18%, 87.22% and 91.91%,respectively. Sodium orthovanadate reduced mRNA expression of α-glucosidase and GLUT2 in epithelial cells of small intestine.CONCLUSION: Sodium orthovanadate can reduce and delay the absorption of glucose and maltose. The mechanism may be that it can inhibit the activity and mRNA expression of α-glucosidase, as well as mRNA expression of GLUT2 in small intestine.