THE EFFECTS OF AMPHETAMINE, PHENCYCLIDINE, DOPAMINERGIC ANTAGONISTS AND ATYPICAL NEUROLEPTICS ON SCHEDULE-INDUCED-POLYDIPSIA (SIP) ARE DISTINGUISHABLE

The effects of amphetamine, phencyclidine, dopaminergic blockers and a typical neuroleptics on the acquisition of schedule-induced polydipsia in rats were compared in a chronic dose regime followed by 7 days of withdrawal. All compounds suppressed water intake. However, different mechanisms were responsible. The antidopaminergic compounds inhibited the initiation of drinking, as the temporal pattern of licking was shi fted to the right. Phencyclidine inhibited the maintenance of drinking as the number of licks/ml water consumed was increased. The suppressi ng effect of amphetamine may have been due to the reduction of high ra tes of licking and/or a competition between licking and locomotor or o ther amphetamine-induced activities. The number of panel entries were increased by amphetamine and phencyclidine. The typical antidopaminerg ic compounds decreased the number of panel pushes, whereas the atypica l antidopaminergic compounds were without effect on this parameter. In conclusion, it was possible to differentiate between the types of com pounds investigated by comparing their effects on water intake, panel pressing, drinking efficiency and the temporal patterns of licking and panel pressing.