Some behavioural effects of quinine in miceNational Institute for Pharmaceutical Research and Development, PMB 21, Abuja, Federal Capital Territory, Nigeria
Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Ahmadu Bello University, Zaria, Nigeria
The effects of quinine on motor activity, pentobarbitone-induced sleep and gross behaviour were examined in mice. Low doses of quinine (0.1-0.5 mg/kg intraperitoneally) increased locomotor activity in mice; this effect was potentiated by L-dopa (25 mg/kg sub cutaneously), L-dopa (25 mg/kg subcutaneously) plus benserazide (12.5 mg/kg subcutaneously) and pargyline (50 mg/kg intraperitoneally) and antagonized by
Journal of Psychopharmacology, Vol. 3, No. 3,
156-168 (1989) |
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-methyl- p-tyrosine (50 mg/kg intraperitoneally), pimozide (0.2 mg/kg intraperitoneally), L-sulpiride (40 mg/kg intraperitoneally) and SCH 23390 (0.2 mg/kg subcutaneously). Similarly, D-amphet amine (2.5 mg/kg intraperitoneally)-induced locomotor activity in mice was blocked by pimo zide (0.2 mg/kg intraperitoneally). On the other hand, pimozide (0.2 mg/kg intraperitoneally), L-sulpiride (40 mg/kg intraperitoneally and SCH 23390 (0.2 mg/kg subcutaneously) potentiated the locomotor depressant effect of high doses of quinine (1-5 mg/kg) intraperitoneally). Furthermore, the onset and duration of pentobarbitone (30 mg/kg intraperitoneally)-induced sleep were respectively shortened and prolonged in a dose-dependent manner. D-Amphet amine (25 mg/kg intraperitoneally) significantly delayed the onset and shortened the duration of sleep induced by the interaction of quinine (100 mg/kg intraperitoneally) with pen tobarbitone (30 mg/kg intraperitoneally). L-sulpiride (40 mg/kg intraperitoneally) and pimozide (4 mg/kg intraperitoneally), on the other hand, significantly shortened the onset and prolonged the duration of sleep resulting from the interaction of quinine with pentobarbitone. The antagonism of pentobarbitone (30 mg/kg intraperitoneally)-induced sleep by D-amphetamine (2.5 mg/kg intraperitoneally) was prevented by pimozide (4 mg/kg intraperitoneally). Quinine (0.1 mg/kg intraperitoneally) desynchronized the EEG and antagonized pentobarbitone (20 mg/kg intraperitoneally)-induced EEG synchronization while 100 mg/kg intraperitoneally of quinine desynchronized the hyperstriatum with marked decrease in EMG activity in chicks and potentiated pentobarbitone (20 mg/kg intraperitoneally)-induced EEG synchronization with profound reduction in EMG activity. Quinine (0.01-5 mg/kg intraperitoneally) exhibited a biphasic dose-related increase in circling. The stereotyped circling induced by D-amphetamine (4 mg/kg intraperitoneally) was dose-dependently reduced by quinine (0.5-25 mg/kg intra peritoneally) while 0.05-0.1 mg/kg intraperitoneally of quinine weakly potentiated this activity. Pimozide (4 mg/kg intraperitoneally) and L-sulpiride (40 mg/kg intraperitoneally) antagonized both the circling and increase in locomotor activity induced by quinine (0.1 mg/kg intra peritoneally) and D-amphetamine (4 mg/kg intraperitoneally) respectively. These results indi cate that quinine exhibits both excitatory and inhibitory effects on the gross behaviour of mice; these biphasic effects were dose-related. Since pimozide, L-sulpiride and SCH 23390 influenced both effects, both D 1 and D2 receptors may be involved in the behavioural effects of quinine.