Following the cloning of the classical opioid receptors (mu, delta and kappa), the opiate receptor like-1 (ORL1) was identified as a G-protein coupled receptor (GPCR) with 65% structure homology to the other members of the opioid family. OPRL1 is a receptor for the 17 aa neuropeptide nociceptin/orphanin FQ and may be involved in the regulation of numerous brain activities, particularly instinctive and emotional behaviors. Recently, new study results are consistent with the reported high density of ORL1 receptor mRNA in dorsal raphe nucleus and with inhibitory actions of nociceptin in cells expressing ORL1.