title: Habituation to sham testing procedures modifies tail-flick latencies: effects on nociception rather than vasomotor tone.
abstract: Habituation of rats to the testing environment and procedures reduces flexor withdrawal latencies to those of spinalised animals. We have now recorded surface temperatures at 3 sites on the tail and tail-flick latencies simultaneously in experimentally naive (novice) rats and in habituated rats. At usual ambient temperatures (20 +/- 1 degree C), tail temperatures fluctuated in accordance with the predictions of an on-off controller. There was an inverse correlation between the tail-flick latency and the temperature at the site of noxious stimulation. A similar correlation was found when the pre-stimulus temperature of the tip of the tail was held at temperatures ranging from 21 degrees C to 35 degrees C. Habituated animals exhibited a similar linear regression slope factor but lower latencies than novice animals at each temperature. We conclude (1) that tail-flick latency is determined partly by the pre-stimulus temperature at the site of noxious thermal stimulation, and (2) that the effects of habituation on tail-flick latency are more likely to be explained by differences in nociception than in regional vasomotor tone.
authors: Department of Physiology, University of Auckland, Auckland (New Zealand).
authors: Richard J
authors: RJ
authors: Milne
authors: Gregory D
authors: GD
authors: Gamble
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000502:physiology; D001831:Body Temperature; D005260:Female; D006185:Habituation, Psychophysiologic; D009619:Nociceptors / Q000502:physiology*; D010147:Pain Measurement; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time; D012016:Reference Values; D012107:Research Design; D013623:Tail / Q000098:blood supply / Q000502:physiology*; D014666:Vasomotor System / Q000502:physiology*