Amphetamine effects on stimulus-elicited investigation in the mongolian gerbil

Abstract

Inappropriate investigatory behaviors emitted following large doses of amphetamine may occur because the animal is more responsive to external stimuli than normal, or may be due to internal changes and not related to the stimuli. However, NaCl, low acute (0.5–2.0 mg/kg) or chronic (0.5–3.0 mg/kg) doses of d-amphetamine had no effect on normal investigation and habituation to a novel object. An acute dose of 3.0 mg/kg d-amphetamine significantly attenuated the investigation. Chronic injections of 3.0 mg/kg d-amphetamine resulted in less attenuation of investigation indicating the development of tolerance. Single injections of the same doses of amphetamine also attenuated investigation of a socially relevant odor. However, chronic injections caused a non-linear attenuation of investigation of the odor. It was concluded that, in the gerbil, amphetamine does not cause increased responsiveness to external stimuli; nor does it interfere with habituation. In fact, gerbils respond selectively to specific stimuli in spite of the probability that amphetamine-induced stereotypies are competing with stimulus-elicited investigation.