Endomorphin-1 and endomorphin-2 are partial agonists at the human mu-opioid receptor.
Recently two tetrapeptide ligands that bind preferentially to the mu-opioid receptor were identified and named endomorphin-1 and endomorphin-2. We examined the ability of these peptides to stimulate G protein activation in human mu-opioid receptor transfected B82 fibroblasts as measured by [35S]GTPgammaS binding to cell membranes. Both endomorphin-1 and -2 act as partial agonists in this assay system compared with the mu-selective agonist [D-Ala2,N-Me-Phe4, Gly-ol5]enkephalin (DAMGO). In addition, endomorphins demonstrate efficacy similar to morphine. These findings demonstrate that endomorphin peptides have similar activity at the mu-opioid receptor as morphine and suggest that these peptides have the potential to modulate neuronal activity in vivo.
Hosohata
K
K
Department of Pharmacology, University of Arizona, Tucson 85724, USA.
Burkey
T H
TH
Alfaro-Lopez
J
J
Varga
E
E
Hruby
V J
VJ
Roeske
W R
WR
Yamamura
H I
HI
D000701:Analgesics, Opioid / Q000494:pharmacology*; D002460:Cell Line; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology*; D017450:Receptors, Opioid, mu / Q000819:agonists*
D000701:Analgesics, Opioid; D009842:Oligopeptides; D017450:Receptors, Opioid, mu; C105293:endomorphin 1; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C105294:endomorphin 2; D019204:GTP-Binding Proteins