The effect of alpha-adrenolytics on central action of agonists and antagonists of dopaminergic system

alpha-Adrenoceptor blocking agents: phenoxybenzamine, phentolamine and aceperone, potentiated and prolonged amphetamine and apomorphine stereotypy in the rat, but inhibited the amphetamine hypermotility. The hypermotility produced by apomorphine was antagonized only by aceperone. Cataleptogenic action of haloperidol and fluphenazine was inhibited by the alpha-adrenoceptor blocking agents. Phenoxybenzamine and phentolamine, and to a smaller degree aceperone, inhibited the depletion of dopamine following pretreatment of rats with alpha-methyltyrosine. The results indicate that the blockade of central alpha-adrenergic receptors changes the reactivity of dopaminergic system on the action of its agonists and antagonists.