The impact of inter-pellet interval and polydipsia on hypoalgesia elicited by non-contingent food delivery.
Exposure to non-contingent food delivery has been shown to elicit an increase in nociceptive thresholds in rats. The conditions which elicit analgesia are similar to those that elicit schedule-induced polydipsia. In both instances animals are food-deprived and receive food on an intermittent schedule. Interpellet interval has been found to be an important predictor of schedule-induced polydipsia. Experiment 1 therefore investigated the effect of varying the interval between pellet deliveries on tail flick latencies in rats. The relationship between nociceptive threshold and inter-pellet interval was found to be bitonic in nature given that animals submitted to fixed time schedules of 30 or 60 s, but not 15 or 120 s, exhibited significant increases in tail flick latencies. Experiment 2 examined the effect of providing animals with water during exposure to non-contingent food delivery. Under these conditions animals exhibited polydipsic behaviour, the development of which attenuated the hypoalgesic response to non-contingent food delivery.
Hodgson
D M
DM
School of Behavioural Sciences, Macquarie University, Sydney, Australia.
Bond
N W
NW
D000818:Animals; D004327:Drinking Behavior / Q000502:physiology*; D005502:Food; D008297:Male; D009619:Nociceptors / Q000502:physiology; D010146:Pain / Q000523:psychology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012055:Reinforcement Schedule; D013997:Time Factors