The use of 100 nM CGP 20712 A (1-[2-((3-carbamoyl-4-hydroxy)phenoxy)ethylamino]-3-[4-(1-methyl-4- trifluoromethyl-2-imidazolyl)phenoxy]-2-propanol methanesulfonate), a specific beta 1-adrenoceptor antagonist, in an in vitro [3H]dihydroalprenolol binding assay simplified the detection of drug-induced alterations in central beta 1- and beta 2-adrenoceptor density. Injection of rats with DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride), a selective noradrenergic neurotoxin, caused an increase in neocortical and hippocampal beta 1-adrenoceptor density. Subchronic infusion of desipramine, a noradrenaline uptake inhibitor, effected a decrease in neocortical and hippocampal beta 1-adrenoceptor density. Subchronic infusion of clenbuterol, a centrally acting beta-adrenoceptor agonist, appeared to decrease striatal beta 2-adrenoceptor density. The results are discussed in terms of the quantitation and regulation of central beta-adrenoceptors.