Involvement of anti-inflammatory mechanism in the antidepressant activity of methanol stem bark extract of adansonia digitata l. (malvaceae)

Abstract

The plant Adansonia digitata has been reported to possess antidepressant activity mediated via monoaminergic, neuroendocrine and neurotrophic pathways. This study investigated the involvement of anti-inflammatory mechanism in the antidepressant activity of methanol stem bark extract of A. digitata. Acute oral median lethal dose (LD50) was estimated using Organization for Economic Co-operation and Development (OECD 425) method. Depression was induced using Bacillus Calmette-Guerin (BCG, 0.2 mg/kg, i.p.) in mice and readings taken at 0, 4, 24 and 48 hours post BCG administration. Subsequently the antidepressant activity of the extract (250-1000 mg/kg) was assessed using tail suspension test (TST) and open field test (OFT). The extract significantly (p ˂ 0.05) decreased the rectal temperature of mice following BCG-induced sickness 4 and 48 hours post induction. The extract also significantly (p ˂ 0.05) decreased the duration of immobility in the TST at 4 and 48 hours post BCG administration. The extract significantly (p ˂ 0.05) increased the total number of line crossedby mice at 4, 24 and 48 hours post BCG administration. The ability of the extract to ameliorate BCG-induced depression suggests the possible involvement of anti-inflammatory mechanismin its antidepressant activity.