Effects of Gs leaf extract on the protein expression levels of NGF in the sciatic nerves of diabetic rats. Data are expressed as the mean ± standard error of the mean (n=6) and were analyzed using one-way analysis of variance followed by the Student-Newman-Keuls post hoc test. *aP<0.05, vs. C group; *bP<0.05 and **bP<0.01, vs. D group. C, control group; D, diabetic group; GS50, rats received 50 mg/kg/day Gs extract; GS100, rats received 100 mg/kg/day Gs extract; NGF, nerve growth factor; Gs, Gymnema sylvestre.