Dopamine denervation of the nucleus accumbens induces a selective increase in the number of δ-opioid binding sites

Abstract Selective lesions of dopamine (DA) neurons of the nucleus accumbens were made in rats by local injections of 6-hydroxydopamine (6-OHDA). Seven days after 6-OHDA, the binding affinities and capacities at μ-, δ- and κ-opioid binding sites were determined in the nucleus accumbens by selective labelling techniques. 6-OHDA pretreatment caused a significant increase in the number of δ-opioid binding sites (+30%) while the number of μ-, κ- and total sites was not modified. The affinity at μ-, δ- and κ-sites was unchanges after 6-OHDA pretreatment.