Task-dependent role for dorsal striatum metabotropic glutamate receptors in memory.
The effect of post-training intradorsal striatal infusion of metabotropic glutamate receptor (mGluR) drugs on memory consolidation processes in an inhibitory avoidance (IA) task and visible/hidden platform water maze tasks was examined. In the IA task, adult male Long-Evans rats received post-training intracaudate infusions of the broad spectrum mGluR antagonist alpha-methyl-4-carboxyphenylglycine (MCPG; 1.0, 2.0 mM/0.5 microL), the group I/II mGluR agonist 1-aminocyclopentane-1,3-carboxylic acid (ACPD; 0.5 or 1.0 microM/0.5 microL), or saline immediately following footshock training, and retention was tested 24 h later. In the visible- and hidden-platform water maze tasks, rats received post-training intracaudate infusions of ACPD (1.0 microM), MCPG (2.0 mM), or saline immediately following an eight-trial training session, followed by a retention test 24 h later. In the IA task, post-training infusion of ACPD (0.5 and 1.0 microM) or MCPG (1.0 and 2.0 mM) impaired retention. In the IA and visible-platform water maze tasks, post-training infusion of ACPD (1.0 microM), or MCPG (2.0 mM) impaired retention. In contrast, neither drug affected retention when administered post-training in the hidden-platform task, consistent with the hypothesized role of the dorsal striatum in stimulus-response habit formation. When intradorsal striatal injections were delayed 2 h post-training in the visible-platform water maze task, neither drug affected retention, indicating a time-dependent effect of the immediate post-training injections on memory consolidation. It is hypothesized that MCPG impaired memory via a blockade of postsynaptic dorsal striatal mGluR's, while the impairing effect of ACPD may have been caused by an influence of this agonist on presynaptic "autoreceptor" striatal mGluR populations.
Packard
M G
MG
Department of Psychology, Yale University, New Haven, Connecticut 06520-8025, USA. Mark.Packard@yale.edu
Vecchioli
S F
SF
Schroeder
J P
JP
Gasbarri
A
A
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology; D001565:Benzoates / Q000494:pharmacology; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections; D017072:Neostriatum / Q000737:chemistry / Q000502:physiology*; D018696:Neuroprotective Agents / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology*
D001565:Benzoates; D018691:Excitatory Amino Acid Antagonists; D018696:Neuroprotective Agents; D018094:Receptors, Metabotropic Glutamate; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; C079694:alpha-methyl-4-carboxyphenylglycine; D005998:Glycine