Hippocampal dependent learning ability correlates with N-methyl-D-aspartate (NMDA) receptor levels in CA3 neurons of young and aged rats

Michelle M. Adams, Thressa D. Smith, Diana Moga, Michela Gallagher, Yuehua Wang, Barry B. Wolfe, Peter R. Rapp, John H. Morrison

Research output: Contribution to journalArticle

Abstract

Hippocampal N-methyl-D-Aspartate (NMDA) receptors mediate mechanisms of cellular plasticity critical for spatial learning in rats. The present study examined the relationship between spatial learning and NMDA receptor expression in discrete neuronal populations, as well as the degree to which putative age-related changes in NMDA receptors are coupled to the effects of normal aging on spatial learning. Young and aged Long-Evans rats were tested in a Morris water maze task that depends on the integrity of the hippocampus. Levels of NR1, the obligatory subunit for a functional NMDA receptor, were subsequently quantified both biochemically by Western blot in whole homogenized hippocampus, and immunocytochemically by using a high-resolution confocal laser scanning microscopy method. The latter approach allowed comprehensive, regional analysis of discrete elements of excitatory hippocampal circuitry. Neither method revealed global changes, nor were there region-specific differences in hippocampal NR1 levels between young and aged animals. However, across all subjects, individual differences in spatial learning ability correlated with NR1 immunofluorescence levels selectively in CA3 neurons of the hippocampus. Parallel confocal microscopic analysis of the GluR2 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) receptor failed to reveal reliable differences as a function of age or spatial learning ability. This analysis linking age, performance, and NR1 levels demonstrates that although dendritic NR1 is generally preserved in the aged rat hippocampus, levels of this receptor subunit in selective elements of hippocampal circuitry, are linked to spatial learning. These findings suggest that NMDA receptor abundance in CA3 bears a critical relationship to learning mediated by the hippocampus throughout the life span.

Original languageEnglish (US)
Pages (from-to)230-243
Number of pages14
JournalJournal of Comparative Neurology
Volume432
Issue number2
DOIs
StatePublished - Apr 2 2001

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Aptitude
N-Methyl-D-Aspartate Receptors
Learning
Hippocampus
Neurons
Isoxazoles
Long Evans Rats
AMPA Receptors
Individuality
Confocal Microscopy
Fluorescent Antibody Technique
Spatial Learning
Western Blotting
Acids
Water
Population

Keywords

  • Aging
  • Confocal microscopy
  • Excitatory amino acids
  • Glutamate receptors
  • Hippocampus
  • Memory

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Hippocampal dependent learning ability correlates with N-methyl-D-aspartate (NMDA) receptor levels in CA3 neurons of young and aged rats. / Adams, Michelle M.; Smith, Thressa D.; Moga, Diana; Gallagher, Michela; Wang, Yuehua; Wolfe, Barry B.; Rapp, Peter R.; Morrison, John H.

In: Journal of Comparative Neurology, Vol. 432, No. 2, 02.04.2001, p. 230-243.

Research output: Contribution to journalArticle

Adams, Michelle M. ; Smith, Thressa D. ; Moga, Diana ; Gallagher, Michela ; Wang, Yuehua ; Wolfe, Barry B. ; Rapp, Peter R. ; Morrison, John H. / Hippocampal dependent learning ability correlates with N-methyl-D-aspartate (NMDA) receptor levels in CA3 neurons of young and aged rats. In: Journal of Comparative Neurology. 2001 ; Vol. 432, No. 2. pp. 230-243.
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