Neoendorphin

Neoendorphins are a group of endogenous opioid peptides derived from the proteolytic cleavage of prodynorphin.^[1] They include α-neoendorphin and β-neoendorphin. The α-neoendorphin is present in greater amounts in the brain than β-neoendorphin. Both are products of the dynorphin gene, which also expresses dynorphin A, dynorphin A_1-8, and dynorphin B.^[2] These opioid neurotransmitters are especially active in CNS receptors, whose primary function is pain sensation.^[3] These peptides all have the consensus amino acid sequence of Tyr-Gly-Gly-Phe-Met (met-enkephalin) or Tyr-Gly-Gly-Phe-Leu (leu-enkephalin).^[4] Binding of neoendorphins to opioid receptors, in the dorsal root ganglion (DRG) neurons results in the reduction of time of calcium-dependent action potential.^[5] The α-neoendorphins binds to μ-opioid, δ-opioid, κ-opioid receptor (KOR), cand β-neoendorphin binds to KOR.^[6][7]