Lack of generalization of nisoxetine with amphetamine in the rat.

Rats were trained to discriminate between the stimulus properties of intraperitoneally administered d-amphetamine (0.8 mg/kg) and its vehicle in a two-lever, food-motivated operant task. Once trained, doses of the norepinephrine reuptake inhibiting agent nisoxetine, ranging from 10 to 20 mg/kg, were administered to investigate if the amphetamine-trained rats would generalize to this agent. This did not, however, occur. Thus, it would seem that noradrenergic mechanisms have a negligible role in the production of the amphetamine-induced discriminative stimulus cue in the rat. Previous evidence that indicated a noradrenergic mediation of amphetamine discrimination in the mouse contrasted with the present results in rats and this discrepancy should warrant caution in comparing results of discriminative studies in these two species.