ABSTRACT
Background: Depression is a global burden whose therapy is plagued with inconsistent effi cacy. Hence, the need for the discovery of newer therapies. Methods: In this study, Antiaris toxicaria extract (200, 400 and 800 mg/kg, p.o.), was evaluated for antidepressant activity using behavioral tests battery particularly the forced swim test (FST) and tail suspension test (TST). In order to investigate its mechanism of action, animals groups were pretreated with α-methyldopa (α-MD), para-chlorophenylalanine (PCPA), reserpine, D-serine and 5-hydroxytryptophan. Results: It increased the mobility periods and decreased immobility periods signifi cantly in both the FST and the TST when compared to the control group. But the TST showed more promising effect than the FST. Pre-treatment with α-MD reversed the antidepressant property of A. toxicaria aqueous extract as did PCPA, reserpine and reserpine combined with α-MD. The extract increased the number of head twitches produced by 5-hydroxytryptophan confi rming the involvement of serotonin in the antidepressant property and inhibited carbachol-induced contractions on the isolated rat uterus, which was non-competitively antagonized by propranolol. Treatment with D-serine produced no signifi cant increase in the immobility time produced by the extract at the doses studied. This excludes the involvement of N-methyl-d-aspartate in the possible mechanisms of action. Conclusion: A. toxicaria possesses antidepressant-like action in rodents.