RVD-Hpα (pepcan-12) is an

endogenous Endogenous substances and processes are those that originate from within a living system such as an organism, tissue, or cell. In contrast, exogenous substances and processes are those that originate from outside of an organism. For example, es ...

neuropeptide found in human and mammalian brain, which was originally proposed to act as a selective

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

for the CB₁ cannabinoid receptor. It is a 12-amino acid

polypeptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A p ...

having the amino acid sequence Arg-Val-Asp-Pro-Val-Asn-Phe-Lys-Leu-Leu-Ser-His and is an

N-terminal The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...

extended form of hemopressin, a 9-AA polypeptide derived from the α₁ subunit of hemoglobin which has previously been shown to act as a CB₁ inverse agonist. All three polypeptides have been isolated from various mammalian species, with RVD-Hpα being one of the more abundant neuropeptides expressed in mouse brain, and these neuropeptides represent a new avenue for cannabinoid research distinct from the previously known endogenous lipid-derived cannabinoid agonists such as anandamide. Recently it was shown that RVD-Hpα (also called Pepcan-12) is a potent negative allosteric modulator at CB₁ receptors, together with other newly described N-terminally extended peptides (pepcans). Pepcan-12 is the major peptide of a family of endogenous peptide endocannabinoids (pepcans) shown to act as negative allosteric modulators (NAM) of cannabinoid CB1 receptors. It is shown that pepcan-12 opposite acts as a potent CB2 cannabinoid receptor positive allosteric modulator (PAM). This peptide is very specifically expressed in the noradrenergic neurons in the brain, mainly the locus coeruleus and its projections and in the adrenal medulla. RVD-Hpα also significantly potentiated the effects of CB2

receptor agonists An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

, including the endocannabinoid 2-arachidonoyl glycerol (2-AG), for GTPγS binding and cAMP inhibition (5–10 fold). The putative precursor pepcan-23 was identified with pepcan-12 in brain, liver and kidney in mice,. RVD-Hpα was increased upon endotoxemia and ischemia reperfusion damage where CB2 receptors play a protective role. The wide occurrence of this endogenous hormone-like CB2 receptor PAM, with unforeseen opposite allosteric effects on cannabinoid receptors, suggests its potential role in

peripheral A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...

pathophysiological processes.

References

{{DEFAULTSORT:RVD-Hpalpha Neuropeptides Endocannabinoids