Nociceptin

The heptadecapeptide nociceptin (NOP; FGGFT-GARKSARKLANQ) was discovered as the natural ligand of the NOP receptor, the fourth cloned member of the opioid receptor family. NOP is derived from a larger precursor polypeptide (prepro-NOP) which is widely distributed in the nervous system. NOP is primarily an inhibitory neuropeptide that acts on neurons to depress synaptic transmission. NOP is reported to modulate pain, stress and anxiety, feeding, learning and memory, reward and addiction, and the functioning of the heart and vessels, airways, kidney, urinary bladder, intestine, and immune cells. The broad spectrum of pharmacological effects of NOP suggests potential therapeutic applications for NOP receptor agonists and/or antagonists.