The molecular and behavioral pharmacology of the orphanin FQ/nociceptin peptide and receptor family

The isolation of an opioid receptor-related clone soon led to the isolation and characterization of a new neuropeptide, termed orphanin FQ or nocicept in (OFQ/N). This heptadecapeptide binds to the NOP1 (previously termed ORL1 ) receptor with exceedingly high affinity, but does not interact directly w ith classical opioid receptors. Functionally, the actions of OFQ/N are dive rse and intriguing. Most work has focused upon pain mechanisms, where OFQ/N has potent anti-analgesic actions supraspinally and analgesic actions spin ally. Other OFQ/N activities are less clear. The diversity of responses mig ht reflect NOP1 receptor heterogeneity, but this remains to be established. The actions of this neurochemical system may also be uniquely dependent on contextual factors, both genetic and environmental. This review will addre ss the molecular biology and behavioral pharmacology of OFQ/N and its recep tor.