Antidepressant-like effect of hydroalcoholic extract of Valeriana prionophylla Standl. from Guatemala: Evidence for the involvement of the monoaminergic systems

Abstract

Background: Previous studies carried out in our laboratories have shown that Valeriana prionophylla displays central effects in mice. The antidepressant effect of the Valeriana prionophylla was the most prominent effect. The goal of this study was to evaluate the mechanism of action of the antidepressant property of HEVp, and its effect when used chronically. Methods: Experiments were performed using the forced swimming test and the open field test. Female Swiss mice (25-30 g, 3 months) were divided into groups (N=8-10): negative control (saline), antagonist systems evaluated, HEVp and antagonist/HEVp. The treatments with NAN-190 (0.5 mg/kg, i.p.), ketanserin (5 mg/kg, i.p.), prazosin (1 mg/kg, i.p.), yohimbine (1 mg/kg, i.p.), haloperidol (0.2 mg/kg, i.p.), pimozide (0.2 mg/kg, i.p.), SCH-23390 (0.05 mg/kg, i.p.), L-arginine (750 mg/kg, i.p.), bicuculline (1 mg/kg, i.p.) and phaclofen (1 mg/kg, i.p.) were administered 30 min before HEVp. The treatments with reserpine (2 mg/kg, i.p.) and PCPA (100 mg/kg, i.p.) were administered 4 hours and 4 days before the test, respectively. Sub-chronic treatment was administered for 15 days, and the test was performed on days 1, 7 and 15 of the treatment. Results: The anti-immobility effect caused by HEVp was significantly attenuated by treatment of the reserpine, PCPA, NAN-190, ketanserin, prazosin, yohimbine, L-arginine, bicuculline and phaclofen, but was not affected by haloperidol, pimozide and SCH-23390. Conclusion: The mechanisms involved in their effects indicate that HEVp produces antidepressant effects through pathways that involve interaction with L-arginine-nitric oxide, serotonergic and GABAergic systems, as well as interaction with the ?-adrenoceptors.