Effects of parachlorophenylalanine and amphetamine on habituation of exploration.

Parachlorophenylalanine (PCPA, 400 mg/kg) retarded the habituation of exploration in the rat recorded over 3 successive days. A more detailed analysis showed that this was not due to any retention deficit, but was secondary to an impairment of habituation within each session. PCPA also disrupted the response of rats to a change of stimuli. (+)amphetamine (4 mg/kg) prevented exploration in the rat and a 2 mg/kg dose reduced exploration and impaired within-session habituation. (+)amphetamine (1 mg/kg) in mice impaired within-session habituation, without significantly reducing exploration. The nature of the deficits produced by these 2 drugs is discussed.