CENTRAL-NERVOUS-SYSTEM ACTIVITY OF RHAZYA-STRICTA (DECNE) IN MICE

1. The effects of orally administered aqueous lyophilized extract of t he leaves of Rhazya stricta (2, 4 and 8 g/kg) on aspects of nervous sy stem function were investigated in mice. 2. In three antinociceptive t ests (hot plate, abdominal constriction, and warm water tail nick test s), the extract exhibited dose-dependent and significant antinocicepti ve activity. Naloxone was ineffective in antagonizing the analgesic ef fect of Rhazya stricta on tail-nick and abdominal constriction tests, possibly indicating that this effect occurs via non-opiate pathways. 3 . Pretreatment of mice with the xenobiotic metabolizing enzymes inhibi tor cimetidine (50 mg/kg) did not significantly alter the antinocicept ive action of the extract, indicating that the effect is probably due to the parent compound(s) present in the extract and not to metabolite s thereof. 4. Rhazya stricta produced dose-dependent sedation, decreas ed motor activity, and impaired motor control. Time spent on a rotarod treadmill was significantly decreased after treatment with the extrac t. 5. Rhazya stricta extract (8 g/kg) produced a degree oi sedation co mparable to that produced by diazepam (5-10 mg/kg), and also significa ntly increased the reaction time of the tail-flick test, an action whi ch was not produced by diazepam. 6. Administration of R. stricta extra ct potentiated pentobarbitone sleeping time in a dose dependent manner . The extract did not significantly antagonize picrotoxin induced conv ulsions. The extract (4 and 8 g/kg) significantly decreased the rectal temperature of normothermic and hyperthermic mice. 7. Pretreatment wi th R. stricta extract (8 g/kg) completely prevented the occurrence of aggressive behaviour in male mice. 8. It is concluded that the crude e xtract of R. stricta has central nervous system depressant properties.