Orexin, also known as hypocretin, is a neuropeptide that regulates arousal, wakefulness, and appetite. It exists in the forms of orexin-A and orexin-B. The most common form of narcolepsy, type 1, in which the individual experiences brief losses of muscle tone, is caused by a lack of orexin in the brain due to destruction of the cells that produce it.
Substance P (SP) is an undecapeptide and a type of neuropeptide, belonging to the tachykinin family of neuropeptides. It acts as a neurotransmitter and a neuromodulator. Substance P and the closely related neurokinin A (NKA) are produced from a polyprotein precursor after alternative splicing of the preprotachykinin A gene. The deduced amino acid sequence of substance P is as follows:
Neuropeptide Y (NPY) is a 36 amino-acid neuropeptide that is involved in various physiological and homeostatic processes in both the central and peripheral nervous systems. It is secreted alongside other neurotransmitters such as GABA and glutamate.
Tachykinin peptides are one of the largest families of neuropeptides, found from amphibians to mammals. They were so named due to their ability to rapidly induce contraction of gut tissue. The tachykinin family is characterized by a common C-terminal sequence, Phe-X-Gly-Leu-Met-NH2, where X is either an Aromatic or an Aliphatic amino acid. The genes that produce tachykinins encode precursor proteins called preprotachykinins, which are chopped apart into smaller peptides by posttranslational proteolytic processing. The genes also code for multiple splice forms that are made up of different sets of peptides.
Nociceptin/orphanin FQ (N/OFQ), a 17-amino acid neuropeptide, is the endogenous ligand for the nociceptin receptor. 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.
Cocaine- and amphetamine-regulated transcript, also known as CART, is a neuropeptide protein that in humans is encoded by the CARTPT gene. CART appears to have roles in reward, feeding, and stress, and it has the functional properties of an endogenous psychostimulant.
The nociceptin opioid peptide receptor (NOP), also known as the nociceptin/orphanin FQ (N/OFQ) receptor or kappa-type 3 opioid receptor, is a protein that in humans is encoded by the OPRL1 gene. The nociceptin receptor is a member of the opioid subfamily of G protein-coupled receptors whose natural ligand is the 17 amino acid neuropeptide known as nociceptin (N/OFQ). This receptor is involved in the regulation of numerous brain activities, particularly instinctive and emotional behaviors. Antagonists targeting NOP are under investigation for their role as treatments for depression and Parkinson's disease, whereas NOP agonists have been shown to act as powerful, non-addictive painkillers in non-human primates.
The urotensin-2 receptor (UR-II-R) also known as GPR14 is a class A rhodopsin family G protein coupled-receptor (GPCR) that is 386 amino acids long which binds primarily to the neuropeptide urotensin II.[1] The receptor quickly rose to prominence when it was found that when activated by urotensin II it induced the most potent vasoconstriction effect ever seen. While the precise function of the urotensin II receptor is not fully known it has been linked to cardiovascular effects, stress, and REM sleep.
The neuropeptide S receptor (NPSR) is a member of the G-protein coupled receptor superfamily of integral membrane proteins which binds neuropeptide S (NPS). It was formerly an orphan receptor, GPR154, until the discovery of neuropeptide S as the endogenous ligand. Increased expression of this gene in ciliated cells of the respiratory epithelium and in bronchial smooth muscle cells is associated with asthma. This gene is a member of the G protein-coupled receptor 1 family and encodes a plasma membrane protein. Mutations in this gene have also been associated with this disease.
The neuropeptide FF receptors are members of the G-protein coupled receptor superfamily of integral membrane proteins which bind the pain modulatory neuropeptides AF and FF. The Neuropeptide FF receptor family is a member of the G protein-coupled receptor superfamily containing two subtypes, NPFF1 and NPFF2, which exhibit a high affinity for Neuropeptide FF (NPFF) peptides. NPFF1 is broadly distributed in the central nervous system with the highest levels found in the limbic system and the hypothalamus. NPFF2 is present in high density, particularly in mammals in the superficial layers of the spinal cord where it is involved in nociception and modulation of opioid functions. These receptors participate to the modulation of opioid receptor function in the brain and spinal cord, and can either reduce or increase opioid receptor function depending which tissue they are released in, reflecting a complex role for neuropeptide FF in pain responses.
Orexin receptor type 2 (Ox2R or OX2), also known as hypocretin receptor type 2 (HcrtR2), is a protein that in humans is encoded by the HCRTR2 gene. It should not be confused for the protein CD200R1 which shares the alias OX2R but is a distinct, unrelated gene located on the human chromosome 3.
Neuropeptide Y receptor type 5 is a protein that in humans is encoded by the NPY5R gene.
JTC-801 is an opioid analgesic drug used in scientific research.
NNC 63-0532 is a nociceptoid drug used in scientific research. It acts as a potent and selective agonist for the nociceptin receptor, also known as the ORL-1 receptor.
J-113,397 is an opioid drug which was the first compound found to be a highly selective antagonist for the nociceptin receptor, also known as the ORL-1 receptor. It is several hundred times selective for the ORL-1 receptor over other opioid receptors, and its effects in animals include preventing the development of tolerance to morphine, the prevention of hyperalgesia induced by intracerebroventricular administration of nociceptin, as well as the stimulation of dopamine release in the striatum, which increases the rewarding effects of cocaine, but may have clinical application in the treatment of Parkinson's disease.
SB-612,111 is an opioid receptor ligand which is a potent and selective antagonist for the nociceptin receptor (ORL-1), several times more potent than the older drug J-113,397. It does not have analgesic effects in its own right, but prevents the development of hyperalgesia, and also shows antidepressant effects in animal studies.
BIBP-3226 is a drug used in scientific research which acts as a potent and selective antagonist for both the Neuropeptide Y receptor Y1 and also the neuropeptide FF receptor. It was the first non-peptide antagonist developed for the Y1 receptor and has been widely used to help determine its functions in the body. Activation of Y1 is thought to be involved in functions such as regulation of appetite and anxiety, and BIBP-3226 has anxiogenic and anorectic effects, as well as blocking the Y1-mediated corticotropin releasing hormone release. It has also been used as a lead compound to develop a number of newer more potent Y1 antagonists.
SHA-68 is a drug which acts as a selective, non-peptide antagonist at the neuropeptide S receptor NPSR. In animal studies it reduced motor stereotypes, and blocks the stimulant action of neuropeptide S.
Netupitant is an antiemetic medication. In the United States, the combinations of netupitant/palonosetron and the prodrug fosnetupitant/palonosetron are approved by the Food and Drug Administration for the prevention of acute and delayed chemotherapy-induced nausea and vomiting, including highly emetogenic chemotherapy such as with cisplatin. In the European Union, the combinations are approved by the European Medicines Agency (EMA) for the same indication.
Olivier Civelli is a molecular biologist, a researcher in the field of neuropharmacology and an educator. He is the Eric L. and Lila D. Nelson Professor of Neuropharmacology at University of California, Irvine. He is also a Professor in the Department of Developmental and Cell Biology at University of California, Irvine. He is most known for his work in advancing understanding of neurotransmission and his impact on drug discovery.
