STIMULATION OF GLUTAMATE RECEPTORS IN THE INTERMEDIATE CAUDAL STRIATUM INDUCES CONTRALATERAL TURNING

The aim of the present study was to investigate the role of striatal N MDA, kainate and AMPA receptors in the turning behaviour of rats. N-me thyl-D-aspartate (NMDA, 500 ng/0.5 mu l), kainic acid (50 ng/0.5 mu l) or pha-amino-3-hydroxy-5-methyl-4-isoxasole-propionic acid (AMPA, 100 0 ng/0.5 mu l), injected into the intermediate and caudal parts of the caudate-putamen, induced contralateral head turns and rotations. This effect was delayed or was not observed after administration of the co mpounds into the globus pallidus. The antagonist of non-NMDA receptors , 6,7-dinitroquinoxaline-2,3-dione (DNQX, 1000 ng/0.5 mu l), antagoniz ed the contralateral head turns and rotations induced by AMPA (1000 ng /0.5 mu l) or kainic acid (50 ng/0.5 mu l), and evoked per se (2000 ng /0.5 mu l) the ipsilateral head turns and rotations. The NMDA receptor antagonist, (+/-)-2-amino-5-phosphonopentanoic acid (AP5, 1000 ng/0.5 mu l), induced mainly ipsilateral head turns and rotations; when inje cted in a dose of 500 ng/0.5 mu l, it inhibited the contralateral head turns and rotations after NMDA. The results seem to suggest that the contralateral head turns and rotations induced by stimulation of NMDA, AMPA and kainate receptors in the intermediate and caudal parts of th e caudate-putamen may result from activation of the gamma-aminobutyrat e (GABA)-ergic strionigral pathway.