Effect of Gymnema sylvestre, R.Br. on glucose homeostasis in rats

Abstract

Effect of Gymnema sylvestre, R.Br. ( G. sylvestre; GS 4) on glucose homeostasis was studied in rats. In the first set of experiments, the acute effect of GS 4 was examined in both non-diabetic and streptozocin (30 mg/kg)-induced mildly diabetic rats. Administration of 1 g/kg body weight of GS 4 to 18-h fasted non-diabetic rats significantly attenuated the serum glucose response to oral administration of 1 g/kg glucose. The immunoreactive insulin (IRI) response in GS 4-administered rats was lower, but not significantly, than that in control rats. In mildly diabetic rats, a 60 min increment in serum glucose concentrations was significantly reduced by GS 4 administration. No IRI response was observed in these diabetic rats irrespective of GS 4 administration. In the second set of experiments, the chronic effect of GS 4 was examined in mildly diabetic rats. Two weeks after the induction of diabetes, the rats were divided into two groups that had similar impairment of glucose tolerance assessed by an oral glucose loading test. The rats were fed for 32–35 days with either a control diet or a diet supplemented with GS 4. After 4 weeks, GS 4 showed a tendency to reduce the serum glucose concentrations in the fed state and to improve the glucose tolerance. Gain in body weight, food intake, pancreas weight and the pancreatic contents of IRI, protein, amylase and trypsinogen were unaltered in the GS 4-treated group compared with the control. These results suggest the usefulness of G. sylvestre in the treatment of certain classes of non-insulin-dependent diabetes mellitus.