ANXIOLYTIC ACTIVITY OF THE AQUEOUS EXTRACT OF BRIDELIA MICRANTHA (HOCHST.) BAILL. (EUPHORBIACEAE) IN MICE: POSSIBLE INVOLVEMENT OF GABA-A RECEPTOR COMPLEX

Delphine Mireille ZE Minkoulou, Rose Marlyse Ngo Mune, Jean Pierre Omam Omam, Elisabeth Ngo Bum, Théophile Dimo* 

ABSTRACT

Anxiety has become the most common mental health problem associated with immense health care costs and a high burden of disease. Current drugs used for the treatment of anxiety are associated with a wide variety of prominent side effects. Medicinal plant extracts have become popular due to their efficacy, fewer undesirable effects, and can serve as sources of new pharmaceutical drugs. The aim of this study was to assess the anxiolytic properties of the bark aqueous extract of Bridelia micrantha (Euphorbiaceae) and its possible mechanisms of action. Hyperthermia-induced stress (HIS), Open field (OF), elevated plus maze (EPM) and hole-board tests were used in this study. Groups mice were treated with distilled water, diazepam, phenobarbital or B. micrantha extract (30, 76, 152 and 305 mg/kg). Evaluations of behavioural profile were done 1 h post-treatment and the duration of observation was 5 minutes. The involvement of the GABAA receptor complex in the activity of B. micrantha extract was inferred from experiments with known GABAA-targeting agents. Extract administration caused significant dose-dependent decrease of HIS compared to negative control. Like diazepam, the extract significantly induced anxiolytic effects in mice in the open arms of the EPM, and during the open field and the hole-board tests. The plant extract significantly inhibited the anxiogenic activities of Bicuculline, Flumazenil and N-methyl-β-carboline-3-carboxamide. Thus, bark aqueous extract of B. micrantha possesses anxiolytic activity that might be due to interactions with the benzodiazepine-binding site of the GABAA receptor complex.

Keywords: Mice, B. micrantha, anxiety, anxiolytic, GABA-A receptor complex.