Inhibition of small-intestinal sugar absorption mediated by sodium orthovanadate Na3VO4in rats and its mechanisms

Abstract

To investigate the inhibitory effects of sodium orthovanadate on small-intestinal glucose and maltose absorption in rats and its mechanism. 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. alpha-glucosidase was abstracted from the upper small intestine, and its activity was examined. mRNA expression of alpha-glucosidase and glucose-transporter 2 (GLUT2) in epithelial cells of the small intestine was observed by in situ hybridization. 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 micromol/L, 100 micromol/L and 1000 micromol/L could suppress the activity of alpha-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 alpha-glucosidase and GLUT2 in epithelial cells of small intestine. 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 alpha-glucosidase, as well as mRNA expression of GLUT2 in small intestine.