DOPAMINE RECEPTOR BLOCKADE AND REDUCTIONS IN THIRST PRODUCE DIFFERENTIAL-EFFECTS ON DRINKING BEHAVIOR

The present study examined whether thirsty rats pretreated with the do pamine receptor blocker, pimozide, would show patterns of unconditione d drinking behavior similar to those produced by reductions in water d eprivation. An examination of the drinking behavior of 23-, 16-, 12-, 4-, and 0-h water-deprived animals showed that reductions in thirst pr oduced increased latencies to initiate drinking, changes in the within -session pattern of licking, and reductions in the total number of lic ks emitted. In contrast, administration of pimozide to 23-h deprived r ats produced no effect on either initiation latencies or lick patterns , and only marginally reduced the total number of licks emitted during the session. Finally, pimozide produced no effect on either individua l lick durations or interlick intervals. These results suggest that th e primary motivational (i.e., ''thirst'') mechanisms and motoric proce sses underlying drinking behavior are relatively invulnerable to pimoz ide challenge.