Comparison between locomotor activity changes produced by phencyclidine and D-amphetamine in CD-1 male mice

Comparative studies were pursued to investigate the locomotor activity induced by phencyclidine hydrochloride in CD-1 male mice. Horizontal, vertical, and rotational activity counts were quantitated using an infrared beam animal activity monitor. Five doses (1.5, 2.5, 3.5, 5.0, and 10.0 mg/kg, i.p.) of phencyclidine were compared. At the 1.5 mg/kg dose, no locomotor activity changes were observed when compared to a saline control group. Increased activity was observed at the 2.5, 3.5, and 5.0 mg/kg doses. Decreased activity was observed at the 10.0 mg/kg dose when compared to the 5.0 mg/kg dose possibly due to ataxia. In addition, the locomotor activity produced by acute d-amphetamine and acute phencyclidine was compared at doses of 2.5 mg/kg and 5.0 mg/kg respectively. The overall locomotor activity levels produced by acute d-amphetamine and phencyclidine were not significantly different at p less than 0.05. The time to peak activities and peak level activities were also similar and occurred at 20-25 minutes and 1100-1300 inches respectively after i.p. administration. Administration of apomorphine after phencyclidine did not change overall locomotor activity. The data implies that phencyclidine may act primarily as a dopamine reuptake inhibitor rather than a dopamine release stimulator. Phencyclidine also affects other activity (unlike amphetamine) as seen by the severe depression of vertical activity.