In vitro modulation of CNS beta-receptor number by antidepressants and beta-agonists

In vitro incubation of rat cerebral cortex slices with antidepressant drugs reduced beta-adrenergic receptor binding of 3H-dihydroalprenolol by 30%. The decrease was maximum after 60 min, and was reversible after 120 min. (-)-Isoproterenol incubation caused a rapid and reversible loss (60%) of beta-receptor binding. Both effects were due to a decrease in beta-receptor sites. In vitro beta-receptor subsensitivity due to desipramine and isoproterenol was non-additive. The observed reversible loss of beta-receptor sites may be an initial phase of the beta-receptor down-regulation by antidepressants seen in vivo.