Modification of ethanol intoxication by dopamine agonists and antagonists.

The effects of ethanol on locomotor activity and rotarod performance were measured in the rat. Apomorphine (4 mg/kg s.c.) antagonized and pimozide (0.75 - 1.50 mg/kg s.c.) enhanced the effects of a 2 g/kg dose of ethanol on rotarod performance. No such interaction was seen with pentobarbital, 25 mg/kg, a dose sufficiency to produce an equivalent motor performance deficit. Animals with 6-hydroxydopamine lesions of the substantia nigra were more sensitive to the ethanol-induced impairment of rotarod performance and suppression of locomotor activity than shamoperated controls. The pattern of dopamine depletion in lesioned animals indicated a degree of selectivity of the lesion for the nigrostriatal pathway. The results are compatible with the hypothesis that ethanol interferes with dopaminergic transmission, and that such an interference may be involved in the behavioral effects of ethanol.