β 1 - and β 2 -Adrenergic Receptors in Rat Cerebral Cortex Are Independently Regulated

Repeated administration of the tricyclic antidepressant desmethylimipramine to adult rats for 10 days caused a 40 percent decrease in the density of β 1 -adrenergic receptors in the cerebral cortex but had no effect on the density of β 2 -adrenergic receptors. Conversely, destruction of noradrenergic neurons by administration of 6-hydroxydopamine to neonatal rats caused a 64 percent increase in the density of β 1 -adrenergic receptors in adult cerebral cortex with no change in the density of β 2 -adrenergic receptors. These results suggest that the β-adrenergic receptors in rat cortex involved in neuronal function are primarily of the β 1 subtype.