Brief exposure to a natural predator, the short-tailed weasel, induces benzodiazepine-sensitive analgesia in white-footed mice.
Exposure to a natural predator, the short-tailed weasel, Mustela erminea, elicited significant increases in the nociceptive responses of wild male white-footed mice, Peromyscus leucopus. A short (30 sec), ecologically relevant, nonvisual exposure to a weasel elicited a relatively brief (15 min) analgesia that was insensitive to the opiate antagonist, naloxone (1.0 mg/kg), and was blocked by either pre- or post-exposure injections of the benzodiazepine antagonist, Ro15-1788 (10 mg/kg), or agonist, diazepam (4.0 mg/kg). A 5 min exposure to the weasel elicited an analgesic response of longer duration (15-30 min) that was sensitive to both naloxone and the benzodiazepine agonist and antagonist. A 15 min exposure to the weasel induced a higher amplitude analgesia that was of relatively long duration (45 min), blocked by naloxone, and insensitive to the benzodiazepine manipulations. Exposures of 5 and 15 min to a nonpredator, the European rabbit, Oryctolagus cuniculus, elicited low amplitude, naloxone-reversible analgesic responses that were unaffected by the benzodiazepine manipulations. Thirty-sec exposures to the rabbit had no significant effects on the nociceptive response of the rabbit. These results indicate that a brief, ecologically appropriate, exposure to a predator elicits a benzodiazepine-mediated analgesia while a more prolonged exposure to a predator induces opioid-mediated analgesia. These results show that the opioid and nonopioid distinction between the effects of long- and short-term laboratory stresses is also evident with a natural, ecologically relevant, stressor.
Kavaliers
M
M
Division of Oral Biology, Faculty of Dentistry, University of Western Ontario, London, Canada.
D000698:Analgesia; D000818:Animals; D001070:Appetitive Behavior; D003975:Diazepam / Q000494:pharmacology*; D005442:Flumazenil / Q000494:pharmacology*; D006234:Handling, Psychological; D006358:Hot Temperature; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D010542:Peromyscus / Q000502:physiology*; D011235:Predatory Behavior; D011817:Rabbits; D012016:Reference Values; D012377:Rodentia / Q000502:physiology*
D009270:Naloxone; D005442:Flumazenil; D003975:Diazepam