Amphetamine: effects on defensive flight or avoidance in the rat.

Treatment with a moderately high dose of amphetamine caused rats to retreat from a stimulus they would normally approach and explore (mechanical robot or live white rabbit). While saline-treated rats spent approximately equal amounts of time in the area of the apparatus near the stimulus, amphetamine-treated rats spent a high percentage of trial time in the area of the apparatus farthest from the stimulus. The drug effects were dose related (range: 1.75, 3.5 and 7.0 mg/kg) with higher avoidance time at higher doses, and significant linear trends accounting for much of the variance. The highest dose of amphetamine elicited response stereotypy. However, control conditions ruled out the possibility that the present results could be explained by competing motor responses of stereotypy or increased activity. Thus, apart from its actions on motor behavior, amphetamine treatment resulted in rats avoiding or retreating from an otherwise neutral stimulus.