Phencyclidine: effects on motor activity and brain biogenic amines in the guinea pig

Previous reports suggesting that the behavioral response of the guinea pig to phencyclidine (PCP) administration is more similar to the effects of PCP observed in higher animals than those observed in mice and rats prompted us to investigate the effects of PC on spontaneous motor activity and brain biogenic amine levels in the guinea pig. Doses of 2.5 and 5.0 mg/kg PCP were found to significantly elevate spontaneous motor activity; however, 7.5 mg/kg PCP produced highly variable results which were not significantly different from control. The concentrations of tryptophan, serotonin, 5-hydroxyindoleacetic acid, and norepinephrine were measured in the forebrain and hindbrain of previously drug naive animals 30 min after administration of 5 mg/kg PCP. As compared to saline injected control animals, PCP was observed to have no effect on any of the neurochemical determinants measured. Contrary to previous reports, these data suggest that PCP produces behavioral effects in the guinea pig which are not unlike those observed in mice and rats. Furthermore, the effects which we report on spontaneous motor activity are not related to changes in the regional concentration of any of the neurochemical variables which were measured.