Contribution of N-methyl-D-aspartate receptors to attention and episodic spatial memory during senescence

Neurobiol Learn Mem. 2015 Nov:125:36-46. doi: 10.1016/j.nlm.2015.07.015. Epub 2015 Jul 30.

Abstract

A decrease in N-methyl-D-aspartate receptor (NMDAR) function is associated with age-related cognitive impairments. However, NMDAR antagonists are prescribed for cognitive decline associated with age-related neurodegenerative disease, raising questions as to the role of NMDAR activity in cognitive function during aging. The current studies examined effects of NMDAR blockade on cognitive task that are sensitive to aging. Young and middle-age rats were trained on the five-choice serial reaction time task (5-CSRTT) and challenged with MK-801 (0.025, 0.05, and 0.1mg/kg or vehicle). Attention deficits were apparent in middle-age and performance of young and middle-age rats was enhanced for low doses of MK-801 (0.025 and 0.05). The beneficial effects on attention were reversed by the highest dose of MK-801. Older animals exhibited a delay-dependent impairment of episodic spatial memory examined on a delayed-matching to place water maze task. Similarly, a low dose of MK-801 (0.05mg/kg) impaired performance with increasing delay and aged animals were more susceptible to disruption by NMDAR blockade. Despite MK-801 impairment of episodic spatial memory, MK-801 had minimal effects on spatial reference memory. Our results confirm that NMDARs contribute to rapidly acquired and flexible spatial memory and support the idea that a decline in NMDAR function contributes to the age-related impairments in cognition.

Keywords: Aging; Attention; Episodic memory; Hippocampus; MK-801; NMDA receptor; Prefrontal cortex.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aging / physiology*
  • Animals
  • Attention / drug effects*
  • Attention / physiology
  • Behavior, Animal / drug effects
  • Behavior, Animal / physiology
  • Cognition / drug effects
  • Cognition / physiology
  • Dizocilpine Maleate / pharmacology*
  • Excitatory Amino Acid Antagonists / pharmacology*
  • Male
  • Memory, Episodic*
  • Rats
  • Rats, Inbred F344
  • Reaction Time / drug effects
  • Reaction Time / physiology
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors*
  • Spatial Memory / drug effects*
  • Spatial Memory / physiology

Substances

  • Excitatory Amino Acid Antagonists
  • Receptors, N-Methyl-D-Aspartate
  • Dizocilpine Maleate