nociceptin

Nociceptin/orphanin FQ (N/OFQ), a 17-amino acid neuropeptide, is the endogenous ligand for the nociceptin receptor (NOP, ORL-1). Nociceptin acts as a potent anti-analgesic, effectively counteracting the effect of pain-relievers; its activation is associated with brain functions such as pain sensation and fear learning. The gene coding for prepronociceptin is located on Ch8p21 in humans. Nociceptin is derived from the prepronociceptin protein, as are a further two peptides, nocistatin and NocII, both of which inhibit N/OFQ receptor function. Nociceptin is the first example of reverse pharmacology; the NOP receptor was discovered before the endogenous ligand which was discovered by two separate groups in 1995. Roles of nociceptin Since its discovery, nociceptin has been of great interest to researchers. Nociceptin is a peptide related to the opioid class of compounds (ex. morphine and codeine), but it does not act at the classic opioid receptors (namely, mu, kappa, and delta opioid receptors) which typically act as pain relievers. Nociceptin is widely distributed in the CNS; it is found in the hypothalamus, brainstem, and forebrain, as well as in the ventral and dorsal horns of the spinal cord. The NOP receptor is also widely distributed throughout areas of the brain, including the cortex, anterior olfactory nucleus, lateral septum, hypothalamus, hippocampus, amygdala, central gray, pontine nuclei, interpeduncular nucleus, substantia nigra, raphe complex, locus coeruleus, and spinal cord. Pain