Efficacy of an active compound of the herb, ashwagandha in prevention of stress induced hyperglycemia

Objective: To find out whether an isolated compound (IC) from the ethanolic extract of roots of ashwagandha prevents stress-induced hyperglycemia by direct interference with the action of increased concentration of corticosterone on hepatocytes or by preventing hyper-secretion of corticosterone or both. Methods: A group of rats served as controls, and those in another group were subjected to restraint (1 h) and forced swimming exercise (15 min), after a gap of 4 h daily for 4 w. The third group of rats received orally IC (5 mg/kg bw/rat) 1 h prior to exposure to stressors. After the last treatment period, a blood sample was collected and serum was separated for the estimation of corticosterone and glucose. In in vitro experiment, hepatocytes were treated with different concentrations of corticosterone (100, 200, 300, 400 and 500 ng/ml). In another set of experiment, hepatocytes were treated with different doses of IC (1, 10, 100, 1000 and 10 000 μg/ml of medium) along with corticosterone (400ng/ml). The concentration of glucose and activities of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) were determined after the treatment. Results: Stress exposure caused a significant increase in serum concentration of corticosterone and glucose whereas, administration of IC did not result in similar changes. Further, treatment of corticosterone in in vitro significantly increased the activities of PEPCK and G6Pase and concentration of glucose in a dose-dependent manner in hepatocytes. However, treatment with IC did not interfere with the corticosterone-induced an increase in the activities of PEPCK and G6Pase as well as the concentration of glucose in hepatocytes. Conclusion: The in vivo and in vitro results put together reveal that IC does not directly interfere with the action of corticosterone on hepatocytes. However, it prevents stress-induced hyperglycemia by suppressing hyper-secretion of corticosterone.