Effect of Withania somnifera root extract on haloperidol-induced catalepsy in albino mice.

The objective of the study was to evaluate the anticataleptic effect of Withania somnifera (WS) extract, on haloperidol-induced catalepsy in albino mice. Catalepsy was induced with haloperidol (1 mg/kg) i.p. in five groups of male albino mice (n = 6). Three groups received Withania somnifera extract (1.7, 4.25, 8.5 mg/kg) respectively, one group received scopolamine (1 mg/kg) and one group received the vehicle (1% gum acacia) orally, 30 min prior to haloperidol administration. Catalepsy was measured by using standard bar test at 30, 60, 90, 120 and 240 min. This constituted the acute study. For the chronic study, the drugs were administered for 6 more days. Catalepsy was again measured on day 7. Animals were then sacrificed by cervical dislocation and superoxide dismutase (SOD) activity was estimated in the brain. In this study, Withania somnifera extract treated groups showed a dose dependent reduction in cataleptic scores, both in the acute and chronic study. The SOD activity in brain was also found to be lowered in the WS (4.25 mg, 8.5 mg/kg) treated groups. In conclusion, Withania somnifera was found to be more efficacious than scopolamine in reversing haloperidol induced catalepsy. A clear correlation between the SOD levels and cataleptic scores was observed. We believe that the antioxidant properties of this drug could have contributed to the anticataleptic effect.