Cats produce analgesia in rats on the tail-flick test: naltrexone sensitivity is determined by the nociceptive test stimulus.
Previous research has demonstrated that exposure to a cat produces a naltrexone-reversible antinociception as assessed in the formalin test in rats. Because different neurochemical mechanisms inhibit different forms of nociception, the present study examined whether presentation of a cat would also produce a naltrexone-reversible antinociception in the tail-flick response to radiant heat and electric shock. Exposure to the cat produced antinociception in both tail-flick paradigms. Naltrexone blocked the inhibition of the thermally evoked tail-flick response, but had no effect in the electric shock tail-flick paradigm. These results indicate that opioid mediation of stress-induced analgesia is determined, in part, by the nociceptive test employed.
Lichtman
A H
AH
Department of Psychology, Dartmouth College, Hanover, NH 03755.
Fanselow
M S
MS
D000818:Animals; D002415:Cats; D004597:Electroshock; D005239:Fear / Q000502:physiology*; D006358:Hot Temperature; D008297:Male; D009271:Naltrexone / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D051381:Rats
D009271:Naltrexone