Effects of phencyclidine and dizocilpine on NMDA-, kainate-, and water deprivation-induced drinking in pigeons.
The excitatory amino acid (EAA) agonists, N-methyl-D-aspartate (NMDA) and kainate, elicit a copious drinking response in pigeons. NMDA-induced drinking, as compared with kainate- and water deprivation-induced drinking, is selectively antagonized by the competitive, NMDA receptor antagonist CGS 19755, and appears to be mediated by NMDA receptors located in brain. There have been several studies which have reported differences between competitive and non-competitive (PCP-like) NMDA antagonists in blocking various behavioral effects of NMDA, such as discriminative stimulus effects. The present studies examined the effects of the non-competitive antagonists, phencyclidine (PCP) and dizocilpine, on drinking elicited by NMDA, kainate, and water deprivation. PCP and dizocilpine were effective antagonists of NMDA-induced drinking, resulting in surmountable shifts to the right in agonist dose-response functions. These compounds had little effect on drinking evoked by either kainate or water deprivation. These results support the notion that the dipsogenic effects of NMDA are mediated by NMDA-type receptors, and also provide important information as to the characteristics of non-competitive NMDA antagonists. EAA-induced drinking provides a useful tool for the examination of the behavioral pharmacology of EAA agonists and antagonists.
Baron
S.P.
SP
Departments of Psychology, University of Michigan M6322 Medical Science Bldg 1, Ann Arbor, MI 48109-0626, USA.
Woods
J.H.
JH