Selective changes in the density of ß1-adrenergic receptors in rat striatum following chronic drug treatment and adrenalectomy

It appears that the density of beta 1-receptors in the caudate is normally affected by changing levels of endogenous catecholamines, similar to that of other beta-adrenergic receptors that receive endogenous input.

Abstract

The corpus striatum has a high density of beta-adrenergic receptors though it appears to contain low levels of beta-hydroxylated catecholamines. In an attempt to determine whether these receptors normally receive an endogenous input, the densities of beta 1 and beta 2-adrenergic receptors in rat caudate have been measured following adrenalectomy and after various pharmacological manipulations. Chronic administration of either pargyline, an inhibitor of monoamine oxidase activity, or desmethylimipramine, an inhibitor of norepinephrine uptake, resulted in a 20-25% decrease in the density of beta 1-adrenergic receptors while either adrenalectomy or the chronic administration of the non-selective beta-adrenergic receptor antagonist propranolol resulted in small but significant increases in the density of beta 1-receptors. These treatments did not lead to significant changes in the density of beta 2-receptors. It thus appears that the density of beta 1-receptors in the caudate is normally affected by changing levels of endogenous catecholamines.