SELECTIVE CHANGES IN THE DENSITY OF BETA-1-ADRENERGIC RECEPTORS IN RAT STRIATUM FOLLOWING CHRONIC DRUG-TREATMENT AND ADRENALECTOMY

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 were measured following adrenalectomy and after various pharmacological minipulations. Chronic administration of either pargyline, an inhibitor of monoamine oxidase activity, or demethylimipramine, 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 nonselective .beta.-adrengergic 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. The density of .beta.1-receptors in the caudate is normally affected by changing levels of endogenous catecholamines.