No abstract

Decoctions of the root of the plant Neorautanenia mitis (A. Rich) Verde (Papilonaceae) are commonly employed ethnomedicinally in the treatment of neuropsychiatric disorders and some other conditions. The central inhibitory effects of the methanol extract of N. mitis (5-20 mg=kg) were therefore investigated in mice and rats to provide scientific evidence for some of these claims. Activities of the extract were studied on pentobarbital hypnosis in rats, and spontaneous motor activity (SMA), exploratory activity, rota-rod performance (motor coordination), and amphetamine-induced as well as apomorphine-induced hyperactivity, all in mice. The extract at doses of 5, 10, and 20 mg=kg (i.p.) produced significant (p < 0.05) prolongation of pentobarbital hypnosis and significantly (p< 0.05) reduced both SMA and exploratory behavior at the same doses. The extract attenuated both amphetamineand apomorphineinduced hyperactivity in mice at the higher doses (10 and 20 mg=kg) but had no effect on motor coordination. The results suggest that the extract possesses biologically active principles with central effects that are sedative in nature and may partly be mediated through activity on dopamine (D 2 )-receptors.