Study of hypoglycemic effect of Juglans regia leaves and its mechanism

ABSTRACT

Hypoglycemic effect of Juglans regia leaves was reported in other previous researches. To investigate the mechanism of hypoglycemic action of Julans regia Leaves Methanolic Extract [JRLME], we designed the following study. Methods: Male wistar rats were classified in five groups, each of six, including alloxan-induced diabetic rats treated with JRLME at doses of 250 [D+JRLMEa], 500 mg/kg [D+JRLMEb], Acarbose at dose 20 mg/kg [D+Ac], vehicle alone [DC] and normal rats treated with vehicle alone [NC]. The Postprandial blood glucose level was examined in a short time [after a single dose treatment] and a long time [after three weeks daily treatment] model. After three weeks of treatment, all groups' animals were killed to dissect pancreatic and myocardium for RNA extraction and RT-PCR, to assess insulin and glut-4 genes expression, respectively. In addition, other normal rats were killed to extract intestinal brush border membrane for beta-glucosidase solution preparation. The effect of JRLMEa on beta-glucosidase activity was evaluated by an in vitro method, compared to Acarbose as a reference drug. The plant extract had a significant hypoglycemic action in both short and long term models. Decrease in PBG level was the most at 8 hour after treatment and more in D+Ac [53%], D+JRLMEa [40%] and D+JRLMEb [29%] versus DC, respectively. There was also permanent PBG reduction in treated groups in comparison with the DC one during long term period. We did not find change in the insulin and glut-4 genes expression. On the other hand, the in vitro assay of beta-glucosidase activity displayed inhibitory action of JRLME, like Acarbose, but less effectively