Swim-induced grooming in mice is mediated by a dopaminergic substrate

Grooming induced in mice after a period of swimming was potently and dose-dependently blocked by neuroleptics. The order of potency of the neuroleptics was spiroperidol greater than haloperidol greater than cis-flupenthixol greater than pimozide greater than chlorpromazine greater than thioridazine. The trans isomer of flupenthixol was inactive at 40 microM/kg. The alpha-adrenergic receptor antagonists, phentolamine and phenoxybenzamine, and the catecholamine synthesis inhibitor, alpha-methyl-p-tyrosine were essentially without effect on the grooming behaviour. Amitriptyline inhibited grooming behaviour only in doses which severely affected the animals motor function. Fluoxetine was without effect. Cis-flupenthixol was less active in inhibiting grooming in animals chronically treated with haloperidol than in control animals, indicating the presence of supersensitive dopamine receptors. The data indicate that swim-induced grooming in mice is mediated via dopaminergic systems.