Experiments were conducted in order to examine the mechanism of changes in body temperature induced by phencyclidine (PCP) in mice. It is well known that morphine changes body temperature in a biphasic manner. PCP also produced hyperthermia at low doses (5 and 10 mg/kg) and hypothermia at high dose (40 mg/kg). The changes in body temperature induced by PCP were blocked by naloxone, a mu antagonist. Pretreatment with morphine (2.5 mg/kg), a mu agonist, or ethylketocyclazocine (EKC: 2.5 mg/kg), a kappa agonist, potentiated hypothermia induced by high dose of PCP. Effects of morphine and EKC on PCP-induced hypothermia were antagonized by naloxone. N- Allylnormetazocine (SKF 10 047: 20 mg/kg), a kappa and mu antagonist, antagonized PCP - and EKC + PCP-induced hypothermia but not morphine + PCP-induced hypothermia. Furthermore, Mr 2266, a kappa antagonist, antagonized PCP (lOmg/kg)- induced hyperthermia and EKC + PCP-induced hypothermia. It is suggested that PCP may affect thermoregulation through mu and/or kappa opioid receptor mechanisms.
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