The effect of a single administration of phencyclidine on behavior in the rat over a 21-day period.

The effects of phencyclidine (PCP) (7.0, 11.7, 19.5, 32.6, and 54.4 mg/kg) on locomotor activity, stereotyped behavior (circling, backing up, and weaving frequency), and rotarod performance were evaluated. In addition, the frequency of other PCP-induced abnormal behaviors (head in corner, arched back, and cataleptic freeze) was determined. All doses of PCP produced a significant increase in locomotor activity and stereotyped behavior as well as an impairment of rotarod performance. Both the duration and the time to peak effects (with the exception of rotarod performance) of these PCP-induced behavioral changes appeared to be dose dependent. The delay in attaining peak effects for locomotor activity and stereotypy was attributed to PCP-induced gross motor ataxia, which became more severe and long lasting with increasing dose. Although the longest period of time that significant changes were seen in locomotor activity, stereotyped behavior, and rotarod performance was 12 hr, sporadic recurrences of stereotypy and a significant increase in cataleptic freeze were observed in the high-dose groups (19.5, 32.6, and 54.4 mg/kg) up to 21 days postadministration. These persistent behaviors (stereotypy and cataleptic freeze) are not unlike certain of the prolonged behaviors seen in man with PCP overdose (catatonic stupor along with repetitive orofacial and limb movements).