Inhibition of group I metabotropic glutamate receptors blocks spatial learning in rats.
Metabotropic glutamate receptors (mGluRs) are postulated to play a role in long-term potentiation and in learning and memory-formation. Previously, we found that the group I/II mGluR antagonist, (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG), blocks Y-maze spatial alternation learning. In this study, we tested the group I mGluR antagonist (S)4-carboxyphenylglycine (4-CPG) in comparison with MCPG using the same behavioural paradigm. Male Wistar rats were intracerebroventricularly injected with either 29 microg 4-CPG or 209 microg MCPG, 30 min prior to learning. Neither 4-CPG nor MCPG had an effect on spatial alternation performance in the training session. In the memory-retention test 24 h later, however, both the 4-CPG- and the MCPG-treated animals were strongly impaired compared with NaCl-injected control rats. These results suggest a particular importance of group I mGluRs in spatial memory-formation and indicate that MCPG effects found in previous learning experiments were predominantly due to an action at group I mGluRs.
Department of Neurophysiology, Leibniz Institute for Neurobiology, Magdeburg, Germany.
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D000818:Animals; D001565:Benzoates / Q000008:administration & dosage / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D005998:Glycine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D018782:Maze Learning / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors*; D013037:Spatial Behavior / Q000187:drug effects* / Q000502:physiology
D001565:Benzoates; D018691:Excitatory Amino Acid Antagonists; D018094:Receptors, Metabotropic Glutamate; C079694:alpha-methyl-4-carboxyphenylglycine; C079693:4-carboxyphenylglycine; D005998:Glycine