Metkephamid-induced Flehmen in lambs.
When metkephamid, a systemically active analog of methionine enkephalin, was administered intracisternally to male or female prepubescent lambs as early as the first week of life, we observed a behavioral pattern akin to Flehmen, which is a well-characterized grimace displayed by mature ungulates during mating. This metkephamid-induced Flehmen was preceded by transient bradycardia and apnea followed by somnolence for approximately 1 hour, during which Flehmen was observed intermittently. Pretreatment with the specific opiate antagonist, naloxone, blocked this behavioral response. These observations indicate that endogenous opioid peptides may be involved in Flehmen.
D000818:Animals; D001143:Arousal / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D011957:Receptors, Opioid / Q000187:drug effects; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D012741:Sexual Maturation / Q000187:drug effects*; D012756:Sheep
D011957:Receptors, Opioid; D009270:Naloxone; D004744:Enkephalin, Methionine; C028208:metkephamid