Diminished reaction to a novel stimulus during amphetamine withdrawal in rats

This experiment determined whether reaction to a novel stimulus was diminished in a dose-dependent fashion following 8 consecutive days of d-amphetamine administration. Thirty-two male rats were injected with saline, 0.5, 2.5, or 5.0 mg/kg of d-amphetamine (each N = 8). On the ninth day, all animals received saline injections and were tested (a) in the presence of a novel stimulus, or (b) in the absence of a novel stimulus. Reaction to the novel stimulus varied inversely with the dose of d-amphetamine which had been received during the drug administration period. This reduction in reaction to the novel stimulus did not seem to depend on (a) the level of amphetamine-induced sterotypy at the end of the drug administration period (b) general reduction of activity, or (c) interference by drug-conditioned responses.