SOME BEHAVIORAL-EFFECTS OF CHLOROQUINE IN RATS SUGGESTING DOPAMINERGIC ACTIVATION

The effect of chloroquine on open-field behaviour, apomorphine induced stereotypies and haloperidol and pimozide-induced catalepsy was studi ed in rats. Chloroquine (2.5-10 mg/kg, ip) significantly increased the locomotion frequently of rats in the open-field and also markedly enh anced apomorphine (0.4 mg/kg, sc)-induced locomotion. Haloperidol (0.2 5 mg/kg, ip) antagonised the increased locomotion frequency produced b y chloroquine (5mg/kg, ip), apomorphine (0.4mg/kg, sc) and chloroquine plus apomorphine. L-Dopa (50mg/kg, sc) and benserazide (12.5mg/kg, ip ) plus L-Dopa (50mg/kg, sc) significantly increased chloroquine (5mg/k g, ip)-induced locomotion. SCH 23390 (0.2mg/kg, sc) and sulpiride (30m g/kg, ip), on the other hand, attenuated chloroquine (5mg/kg, ip)-indu ced locomotion. Chloroquine (2.5-5mg/kg, ip) elicited stereotyped beha viour in rats and significantly potentiated apomorphine (2mg/kg, sc)in duced stereotypies. Haloperidol (0.25mg/kg, ip) markedly reduced the s tereotypies produced by both chloroquine (5mg/kg, ip) and apomorphine (2mg/kg, sc). Both chloroquine (2.5-10mg/kg, ip) and apomorphine (0.4m g/kg, sc) significantly delayed the onset and decreased the intensity of catalepsy induced by haloperidol (0.25mg/kg, ip) and pimozide (2mg/ kg, ip) respectively. These findings indicate that chloroquine, in low doses, produces excitatory effects and that dopaminergic mechanisms m ay be involved in the observed effects of chloroquine.