Retinoid hyposignaling contributes to aging-related decline in hippocampal function in short-term/working memory organization and long-term declarative memory encoding in mice

J Neurosci. 2008 Jan 2;28(1):279-91. doi: 10.1523/JNEUROSCI.4065-07.2008.

Abstract

An increasing body of evidence indicates that the vitamin A metabolite retinoic acid (RA) plays a role in adult brain plasticity by activating gene transcription through nuclear receptors. Our previous studies in mice have shown that a moderate downregulation of retinoid-mediated transcription contributed to aging-related deficits in hippocampal long-term potentiation and long-term declarative memory (LTDM). Here, knock-out, pharmacological, and nutritional approaches were used in a series of radial-arm maze experiments with mice to further assess the hypothesis that retinoid-mediated nuclear events are causally involved in preferential degradation of hippocampal function in aging. Molecular and behavioral findings confirmed our hypothesis. First, a lifelong vitamin A supplementation, like short-term RA administration, was shown to counteract the aging-related hippocampal (but not striatal) hypoexpression of a plasticity-related retinoid target-gene, GAP43 (reverse transcription-PCR analyses, experiment 1), as well as short-term/working memory (STWM) deterioration seen particularly in organization demanding trials (STWM task, experiment 2). Second, using a two-stage paradigm of LTDM, we demonstrated that the vitamin A supplementation normalized memory encoding-induced recruitment of (hippocampo-prefrontal) declarative memory circuits, without affecting (striatal) procedural memory system activity in aged mice (Fos neuroimaging, experiment 3A) and alleviated their LTDM impairment (experiment 3B). Finally, we showed that (knock-out, experiment 4) RA receptor beta and retinoid X receptor gamma, known to be involved in STWM (Wietrzych et al., 2005), are also required for LTDM. Hence, aging-related retinoid signaling hypoexpression disrupts hippocampal cellular properties critically required for STWM organization and LTDM formation, and nutritional vitamin A supplementation represents a preventive strategy. These findings are discussed within current neurobiological perspectives questioning the historical consensus on STWM and LTDM system partition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / physiology*
  • Animals
  • Behavior, Animal
  • GAP-43 Protein / metabolism
  • Hippocampus / drug effects
  • Hippocampus / physiopathology*
  • Keratolytic Agents / administration & dosage
  • Maze Learning
  • Memory Disorders / genetics
  • Memory Disorders / pathology*
  • Memory Disorders / physiopathology*
  • Memory, Short-Term / physiology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Receptors, Retinoic Acid / deficiency
  • Retinoid X Receptors / deficiency
  • Retinoids / metabolism*
  • Time Factors
  • Tretinoin / administration & dosage
  • Vitamin A / therapeutic use

Substances

  • GAP-43 Protein
  • Keratolytic Agents
  • Receptors, Retinoic Acid
  • Retinoid X Receptors
  • Retinoids
  • retinoic acid receptor beta
  • Vitamin A
  • Tretinoin