Naloxone does not produce withdrawal hypothermia in chronically phencyclidine-treated rats

Naloxone-induced hypothermia is a sensitive indicator of mu-type opiate dependence in the rat. The present study investigated whether naloxone produces hypothermia in chronically PCP-treated rats. Rats were given daily injections of saline or PCP (10.0 mg/kg s.c.) for 7 days, and on day 8 challenged with naloxone (2.0 mg/kg s.c.). There were no differences between chronic saline- and PCP-treated subjects, indicating that the repeated administration of 10.0 mg/kg per day of PCP does not produce mu-type opiate dependence as reflected by naloxone-precipitated hypothermia.