Conditioned temperature effects using amphetamine as the unconditioned stimulus.

Three groups of male Wistar rats received daily IP injections of either 1, 2 or 5 mg/kg amphetamine at 11:15 h; a fourth group received saline injections throughout. Rectal temperature was measured in the home cage, in a pre-injection environment in which animals were placed for a period of time before the daily injection, and in an injection environment in which animals remained following the injection. Conditioned hyperthermia, a response that mimicked the unconditioned effect of amphetamine, was elicited by cues of the injection environment both during conditioning and after the drug-free period. During conditioning, hypothermia occurred at 10:30 h regardless of where the animals were, but could not be elicited at other times of day. The results with amphetamine parallel those found previously with morphine (Eikelboom and Stewart 1979, 1981).