title: Sex differences in opioid and non-opioid mediated predator-induced analgesia in mice.
abstract: The present study compared the nociceptive responses of male and female mice exposed to a predator, an ecologically relevant threatening stimulus. After 15 min of exposure to the presence of an experienced predatory cat, mice displayed a naloxone (1.0 mg/kg)-sensitive opioid mediated analgesic response, while after a brief 30-s exposure to the cat mice displayed a lower amplitude, relatively brief, non-opioid analgesia that was insensitive to naloxone and blocked by the serotonin-1A (5-HT1A) agonist, 8-hydroxy-2-(di-n-propylamino)tetralin. Male mice displayed a significantly greater opioid mediated predator-induced analgesia than females, whereas female mice showed a significantly greater non-opioid, 5-HT1A sensitive, analgesia than males. These results indicate that there are significant sex differences in both the opioid and non-opioid analgesic responses arising from exposure to a natural aversive stimulus.
authors.affiliation: Division of Oral Biology, Faculty of Dentistry, University of Western Ontario, London, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Kavaliers
authors.forename: D D
authors.initials: DD
authors.lastname: Colwell
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000698:Analgesia; D000818:Animals; D002415:Cats; D005260:Female; D006168:Guinea Pigs; D008297:Male; D051379:Mice; D009270:Naloxone / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology* / Q000523:psychology; D011235:Predatory Behavior; D012727:Sex Characteristics; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*
chemical_list: D013764:Tetrahydronaphthalenes; D009270:Naloxone; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin