ANTIDEPRESSANT-LIKE EFFECT OF METHANOL ROOT BARK EXTRACT OF ACACIA SEYAL DEL. (FABACEAE) IN MICE

Abstract

Depression is a major cause of disability associated with affective and cognitive impairments and has been estimated
to be the single biggest burden of health conditions. Acacia seyal Del. (Fabaceae) is reported to be used in Zaria,
North western Nigeria for the management of depression. The aim of this study is to investigate the antidepressant
activity of methanol root bark extract of Acacia seyal in mice. The root bark of Acacia seyal was collected, dried,
pulverised, powdered and extracted using 70% methanol. The methanol root bark extract was then used for
preliminary phytochemical screening, acute toxicity study (LD50), beam walking assay (BWA) and antidepressant
study. The preliminary phytochemical screening was carried out on the extract based on standard procedures, while
the acute toxicity study was conducted using Organization for Economic Cooperation and Development (OECD)
425 guideline. Motor coordination deficit was assed using beam walking assay. Antidepressant activity was
evaluated using tail suspension test (TST) and open field test (OFT) all in mice. The possible involvement of the
monoaminergic, nitritergic and opiodergic systems in the antidepressant activity of the extract was further evaluated.
The phytochemical constituents detected include tannins, saponins, flavonoids and steroids. The oral LD50 of the
extract was found to be ≥5000 mg/kg in mice. The extract did not significantly affect the number of foot slips in the
BWA and the locomotory behaviour of mice in the OFT. The extract at the tested doses produced significant
(p<0.05) decrease in the duration of immobility in the TST. The anti-immobility effect of the extract at 500 mg/kg
in the TST was reversed by the pre-treatment of mice with sulpiride (50 mg/kg), metergoline (1mg/kg),
cyproheptadine (4mg/kg), prazosin (1 mg/kg), yohimbine (1 mg/kg), atropine (1 mg/kg), L-arginine (50 mg/kg),
Nitro-L-Arginine (50 mg/kg) and Naloxone (2 mg/kg). The methanol root bark extract of Acacia seyal possesses
antidepressant activity possibly mediated through interaction with dopamine, noradrenergic, serotonergic,
cholinergic, opioidergic receptors and nitric oxide pathway.