title: Analgesic activity of the naturally occurring heptapeptide [Met]enkephalin-Arg6-Phe7.
abstract: [Met]Enkephalin-Arg6-Phe7 is an opiate-like peptide normally found in the the adrenal gland and brain that has analgesic (antinociceptive) activity when administered directly into the cerebral ventricles of mice. On a molar basis, [Met]-enkephalin-Arg6-Phe7, with a median effective dose (ED50) of 38.5 nmol/mouse, is 8 times more potent than [Met]enkephalin. As with [Met]enkephalin, analgesic activity is blocked by naloxone and intravenous administration does not produce characteristic opiate effects in tests for analgesic, antidiuretic, or antidiarrheal activity. These findings suggest that [Met]enkephalin-Arg6-Phe7 may be at least as important as the enkephalins in the postulated enkephalin system mediating pain and analgesia.
mesh_terms: D000700:Analgesics; D000818:Animals; D003967:Diarrhea / Q000188:drug therapy; D004231:Diuresis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000494:pharmacology*; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives*; D004745:Enkephalins / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D009270:Naloxone / Q000494:pharmacology; D051381:Rats
chemical_list: D000700:Analgesics; D004723:Endorphins; D004745:Enkephalins; D009270:Naloxone; D004744:Enkephalin, Methionine; C027511:enkephalin-Met, Arg(6)-Phe(7)-