Down-regulation of β-adrenergic receptors following repeated injections of desmethylimipramine: Permissive role of serotonergic axons

The injection of desmethylimipramine (DMI) twice daily for 3 weeks reduced the density of β-adrenergic receptor recognition sites located in crude synaptic membranes prepared from the cortex and hippocampus and attenuated the stimulation of the membrane-bound adenylate cyclase by isoproterenol. Both actions were abolished if prior to treatment with desmethylimipramine the serotonergic axons were destroyed by an intraventricular injection of 5,7-dihydroxytryptamine. These results show that the down-regulation of β-adrenergic receptors elicited by repeated injections of desmethylimipramine occurs only if the serotonergic axons are intact. © 1982.