A Human Neuroblastoma Cell Line Expresses p and 6 Opioid Receptor Sites

A series of neuroblastoma cell lines were screened for the presence of opioid receptor sites with the tracers [3H]diprenorphine (p , 6, K ligand) and f3H]naloxone (p-selective ligand). One human neuroblastoma cell line, SK-N-SH, displayed avid binding for both tracers. Binding experiments with multiple tracers revealed the presence of both p and 6 sites. These sites were stereospecific, saturable, and proteinaceous in character. Saturation binding experiments provided an estimate of 50,000 and 10,000 6 sites/cell. NaCl (100 mM) and guanine nucleotide, guanylyl imidodiphosphate (50 p ~ ) , reduced opioid agonist but not antagonist binding to these sites. Etorphine at 1 nM inhibited prostaglandin El-stimulated cyclic AMP production by approximately 20%, which was reversible by naloxone. The opioid-binding sites on SK-N-SH cells closely resemble the previously reported p and 6 sites in human and rodent brain. Therefore, the SK-NSH neuroblastoma cell line represents a useful tool to study the molecular functions of opioid receptors.