Comparative extrapyramidal effects of Rauwolfia vomitoria, chlorpromazine and reserpine in mice

Most antipsychotics interfere with the dopaminergic system, resulting in extrapyramidal effects. This study compared the extrapyramidal effects of chlorpromazine (Cpz), the herb Rauwolfia vomitoria (RV) and its alkaloid reserpine (Res), used as antipsychotics, in mice. Ninety age-matched male CD-1 strain of mice (25-33 g body weight) were divided into 3 groups, each consisting of 5 subgroups (n = 6). Cpz (0.0, 0.25, 1.0, 2.0 and 4.0 mg/kg, i.p.) was administered 30 min before testing. RV (0.0, 0.25, 1.0, 2.0 and 4.0 mg/kg, i.p.) and Res (0.0, 0.1, 0.4, 0.8, 1.6 mg/kg, i.p.) were administered 24 h before testing. Locomotor behaviour (open field test) and motor coordination (acceleratory rotarod) were assessed. Mice were also observed for 10 min for tremor and vacuous chewing movement (VCM). CPZ and Res dose-dependently decreased locomotor behaviour and impaired motor coordination (p < 0.01). RV also decreased locomotor behaviour (4.0 mg/kg; p < 0.05) but had minimal effect on motor coordination. VCM was lower in the RV group (0.17 ± 0.16/10 min) than the Res (6.8 ± 1.36/10 min) and Cpz groups (7.83 ± 1.95/10 min): F = 10.703; p < 0.01. The frequency of bouts of tremor was also lower in the RV group (1.17 ± 0.72/10 min) than the Res (21.2 ± 5.63/10 min) and Cpz (7.83 ± 1.59/10 min) groups: F = 11.012; p < 0.001. The root bark extract of R. vomitoria, therefore, has great potential in the management of psychotic disorders. © 2012 The Japanese Society of Pharmacognosy and Springer.