Sex differences in opioid and N-methyl-D-aspartate mediated non-opioid biting fly exposure induced analgesia in deer mice.
There is evidence for sex differences in responses to noxious stimuli and in the expression and mediation of analgesia. In particular, results of investigations with swim stress and the more ethologically appropriate stress of predator odor exposure have suggested sex differences in N-methyl-D-aspartate (NMDA) receptor system involvement in the mediation of analgesia. Whether or not this sex difference generalizes to other environmental stressors is, however, not clear. Biting flies are a natural aversive stimuli commonly encountered by wild and domestic animals and humans. The present study examined the opioid and non-opioid mediated nociceptive (50 degrees C hot plate) responses of reproductive male and female deer mice, Peromyscus maniculatus, exposed to biting fly attack. A 30 min exposure to biting flies (stable flies, Stomoxys calcitrans (L.)) elicited a naloxone sensitive, opioid-mediated analgesia that was of a greater magnitude in males than in female deer mice. In contrast, a 5 min exposure to biting flies elicited a 'on-opioid' analgesia that was of similar magnitude in both sexes and insensitive to both naloxone and the specific kappa opiate antagonist, nor-binaltorphimine. In male mice this non-opioid analgesia was antagonised by the competitive NMDA antagonist, NPC 1262, while in reproductive females the biting fly-induced analgesia was insensitive to NPC 12626. These results show that there are sex differences in NMDA involvement in the mediation of the non-opioid analgesia arising from brief exposure to the stress of biting fly attack. These data from a common, natural environmental challenge support the presence of basic sex difference in NMDA involvement in the mediation of stress-induced analgesia.
Department of Psychology and Neuroscience Program, University of Western Ontario, London, Ontario N6A 5C2, Canada Agriculture and Agri-Food Canada, Box 3000 Main, Lethbridge, Alberta T1J 4B1, Canada Lawson Research Institute, St. Joseph's Health Centre, University of Western Ontario London, Ontario, N6A 5C1, Canada.
Martin
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Kavaliers
Douglas D
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Colwell
Elena
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Choleris
D000596:Amino Acids / Q000494:pharmacology; D000698:Analgesia; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D006793:Houseflies; D007299:Insect Bites and Stings / Q000503:physiopathology*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009619:Nociceptors / Q000502:physiology; D010542:Peromyscus; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D017473:Receptors, Opioid, kappa / Q000502:physiology*; D012727:Sex Characteristics; D013312:Stress, Physiological / Q000503:physiopathology
D000596:Amino Acids; D018691:Excitatory Amino Acid Antagonists; D009292:Narcotic Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D017473:Receptors, Opioid, kappa; C060212:NPC 12626; D009270:Naloxone; C051844:norbinaltorphimine; D009271:Naltrexone