Anxiolytic- and antidepressant-like activities of hydroethanol leaf extract of Newbouldia laevis (P.Beauv.) Seem. (Bignoniaceae) in mice.

Abstract

Newbouldia laevis (Bignoniaceae) is a woody tropical plant commonly found in southwest Nigeria. Ethnobotanical survey and literature revealed its application in the management of CNS disorders e.g. psychosis, insomnia, convulsions and associated anxiety and depression. This study evaluated the anxiolytic and antidepressant activities of the hydroethanol leaf extract of N. laevis in mice. The hole-board (HBT), elevated plus maze (EPMT), light/dark exploration (LDET), open field (OFT), social interaction (SIT) (anxiolytic activity), forced swim (FST) and tail suspension (TST) (antidepressant property) tests were employed in this investigation. Mice randomly allotted to different groups were treated orally with distilled water (10ml/kg), diazepam (1 and 3mg/kg), imipramine (20mg/kg) and N. laevis (25-200mg/kg). The mice were subjected to the various tests 60min post-treatment. In the HBT, N. laevis (25 and 100mg/kg) increased the number of sectional crossings significantly (p<0.05). In the OFT, N. laevis (25-200mg/kg) increased the number of general square crossings, centre square crossings, rearings and assisted rearings (p<0.05). In the EPMT, the extract (25 and 50 mg/kg) increased the open arms time spent, number of head dips and entry (p<0.05). In the LDET, N. laevis increased the number of transitions at 100 and 200mg/kg (p<0.05). For the SIT, N. laevis (25 and 200mg/kg) increased the frequency and duration of interaction respectively (p<0.05). In the FST and TST, N. laevis (25-200mg/kg) increased the latency and reduced the total duration of immobility (p<0.05). The effect of the extract on duration of immobility was significantly reversed by sulpiride (Dopamine D2 receptor antagonist). The hydroethanol leaf extract of N. laevis possesses anxiolytic- and antidepressant-like activities, the later possibly mediated by dopaminergic enhancement(s).