Effects of phencyclidine on rat prolactin, dopamine receptor and locomotor activity

Plasma prolactin (PRL) was decreased in naive rats sacrificed 30 min after phencyclidine (PCP) administration (10 mg/kg, s.c.). There was, however, no decrease in plasma PRL 30 min after s.c. injection of PCP (10 mg/kg) on the 29th day following 28 days of chronic PCP administration. These data suggest the development of tolerance to the PRL-suppressive effect of PCP as result of long-term administration of the drug. The Bmax of [3H]-spiperone binding to rat striatal membranes was decreased 24 hrs after 28 days of PCP treatment without change in affinity (Kd). No indication of the development of tolerance in these rats was found with regard to the locomotor-stimulating effect of PCP. The plasma PRL-suppressive effect of the PCP analog PCMP was found to be stereospecific; (-) PCMP was much less potent than (+)-PCMP.