RESUMO
Ethanolic extract (100, 200 and 400 mg/kg, po) of N. jatamansi administered for 14 successive days to Swiss young albino mice (either sex) produced significant antidepressant-like effect in both tail suspension and forced swim tests. The efficacy of the extract was found to be comparable to imipramine (15 mg/kg, po) and sertraline (20 mg/kg, po). Ethanolic extract (200 mg/kg, po) did not show any significant change on locomotor activity of mice as compared to control; hence it did not produce any motor effects. Further, the extract decreased the whole brain MAO-A and MAO-B activities as compared tocontrol, thus increased the levels of monoamines. The antidepressant effect of the extract was also significantly reversed by pretreatment of animals with baclofen (GABAB agonist); when tested in tail suspension test. The results suggested that the antidepressant-like effect of the extract may also be due to interaction with GABAB receptors, resulting in decrease in the levels of GABA in mouse brain. Thus, the extract may have potential therapeutic value for the management of mental depression.