title: Analgesic and other pharmacological activities of an enkephalin analogue, syndyphalin (SD)-25.
abstract: The pharmacological actions of Tyr-D-Met(O)-Gly-MePheol (syndyphalin (SD)-25) were compared with those of morphine after systemic administration. The analgesic potency of SD-25 was about 4 times that of morphine when administered s.c. to rats. SD-25 did not exhibit any narcotic antagonist activity. Subcutaneous administration of SD-25 produced a dose-dependent suppression of morphine withdrawal signs in morphine-dependent rats, typical morphine-like jumping in the mouse jumping test, and an increase in spontaneous locomotor activity in mice. These activities were 2-5 times those of morphine. In the anaesthetized dog, intravenous administration of SD-25 produced a 100-1000 times stronger increase in the amplitude of contractions of the jejunum than did morphine, a weaker depression in respiration than morphine, and a slight increase in blood pressure. These effects were reversed by naloxone. These results indicate that SD-25 possesses potent central nervous system actions closely similar to those of morphine, but its effect on blood pressure and respiration was weaker than that of morphine.
mesh_terms: D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009021:Morphine Dependence / Q000517:prevention & control; D009043:Motor Activity / Q000187:drug effects; D009842:Oligopeptides / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012119:Respiration / Q000187:drug effects
chemical_list: D000700:Analgesics; D009842:Oligopeptides; D009020:Morphine; C030776:syndyphalin