Dopamine agonist-induced restoration of drinking in response to hypertonic saline in adipsic dopamine denervated rats

Bilateral 6-hydroxydopamine lesions of the ascending dopamine neurones of the nigro-striatal bundle or bilateral electrolytic lesions of the lateral hypothalamus cause a syndrome of aphagia and adipsia. Rats with such lesions do not drink in response to hypertonic saline which causes thirst in intact animals. However, the systemic administration of the direct dopamine receptor agonists apomorphine, piribedil and lergotrile restored drinking in response to hypertonic saline in 6-hydroxydopamine treated rats but not in rats with electrolytic lesions of the lateral hypothalamus. Amphetamine and beta-phenylethylamine failed to restore drinking in response to hypertonic saline in either group of lesioned rats which suggests that these drugs may act indirectly on the dopaminergic system. The restoration of drinking model suggests that dopamine may have a permissive function in thirst, and, in addition, appears to represent a useful test for the screening of new drugs for a direct dopamine receptor stimulating action.