Selective increase ofα1-adrenoceptors and muscarinic cholinergic receptors in rat cerebral cortex after chronic haloperidol

Abstract The effect of chronic administration of haloperidol on α 1 -, α 2 -, and β-adrenoceptors, cholinergic muscarinic GABA A and benzodiazepine receptors in the cerebral cortex of the rat was investigated. Doses of 0.3 and 2mg/kg of haloperidol during 7 days increased markedly the density of α 1 -adrenoceptors without changes in affinity. The α 2 - and β-adrenoceptors were not modified after neuroleptic administration. The number of muscarinic receptors were also increased after haloperidol treatment (2 mg/kg/day). However, the GABA A and benzodiazepine binding sites remained unchanged. In the brainstem an increment in the α 1 -, but not the β-adrenoceptors was observed. The well known increase in the dopamine receptors in the striatum was confirmed. These observations demonstrate a multireceptor effect of haloperidol in the cerebral cortex.