Nociceptin-induced internalization of the ORLI receptor in human neuroblastoma cells

Nociceptin/orphanin FQ (INC) has been proposed as endogenous ligand of the opioid receptor-like I (ORLI) receptor. We investigated NC-induced internal ization and recycling of the ORLI receptor in SK-N-BE human neuroblastoma c ells. Internalization was proven by receptor binding assay on viable cells. NC promotes a time- and concentration-dependent internalization of the ORL I receptor (57% of cell surface receptors are lost after 30 min exposure to 1 muM NC) in a clathrin- and ATP-dependent manner. After 30 min exposure t o NC, ORLI receptor internalization is partially reversible and recycling i s dependent on acid phosphatases. Over-expression of beta -arrestin 2 incre ases NC-promoted internalization of the ORLI receptor. These events contrib ute to NC signaling in neuronal cells through sequestration and recycling o f the ORLI receptor. NeuroReport 12:3159-3163 (C) 2001 Lippincott Williams & Wilkins.