[3H]etorphine binding in rat striatum following lesions of the raphe nuclei

Following 5,7-dihydroxytryptamine lesions of the rat raphe nuclei a significant reduction in striatal serotonin concentrations was observed. However, with [3H]etorphine as ligand no change in opiate receptor binding was observed in striatal membranes. Moreover, when [3H]etorphine binding was resolved into its mu- and delta + kappa-components no change in either component was observed compared with controls. It is concluded that opiate receptors are not on striatal serotonergic nerve terminals whose cell bodies are located in the raphe nuclei.