Antidepressant activity of methyl jasmonate, a plant stress hormone in mice.

Methyl jasmonate (MJ) is a hormone released by plants in response to external stress, injury or pathogenic invasions. This present investigation evaluated the antidepressant effect of intraperitoneal doses of MJ in mice. Mice were given MJ in the doses of 10, 25 and 50 mg/kg daily for 7 days and then subjected to forced swim test (FST), tail suspension test (TST) and yohimbine lethality test (YLT). The results showed that MJ produced a significant decrease in the period of immobility in the FST and TST, indicating antidepressant activity. MJ potentiated the toxic effect of yohimbine in the YLT, which further suggests antidepressant property and also indicates facilitatory effect on both serotonergic and noradrenergic systems respectively. However, MJ did not significantly alter the spontaneous motor activity of the animals, which indicates a lack of central nervous system stimulant effect. Taken together, these findings suggest that MJ has antidepressant activity and the mechanisms underlying this effect may involve serotonergic and noradrenergic systems.