IL-1RA Blocks E. Coli-Induced Suppression of Arc and Long-Term Memory in Aged F344xBN F1 Rats

Brain Behav Immun. 2010 Feb;24(2):254-62. doi: 10.1016/j.bbi.2009.10.005. Epub 2009 Oct 12.

Abstract

In normal aging, a peripheral immune challenge induces a sensitized and protracted neuroinflammatory response in parallel with long-term memory (LTM) impairments. Pro-inflammatory mediators of neuroinflammation impair LTM, synaptic plasticity and LTP. The immediate early gene Arc is considered a critical protein regulating LTM and synaptic plasticity. The present investigation examined whether (1) a peripheral Escherichia coli infection suppresses hippocampal Arc expression, and (2) central pro-inflammatory cytokines (IL-1beta and IL-6) mediate the effects of peripheral E. coli infection on Arc and LTM. In 24 months F344xBN F1 rats, E. coli infection suppressed basal Arc gene expression as well as contextual fear conditioning-induced Arc expression. E. coli treatment failed to alter either basal or conditioning-induced c-Fos expression. At 24h post-infection, intra-cisterna magna (ICM) treatment with the anti-inflammatory cytokine IL-1RA blocked the E. coli-induced suppression of hippocampal Arc and increases in IL-6 protein. At 4-day post-infection, IL-1RA blocked the E. coli-induced LTM impairments and increases in IL-6 protein. The present results suggest that central pro-inflammatory cytokines play a salient role in the suppression of Arc and impairments of LTM by a peripheral immune challenge in older animals.

Publication types

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

MeSH terms

  • Aging / psychology*
  • Animals
  • Cisterna Magna
  • Conditioning, Psychological / drug effects
  • Cytoskeletal Proteins / biosynthesis*
  • Enzyme-Linked Immunosorbent Assay
  • Escherichia coli Infections / complications
  • Escherichia coli Infections / genetics
  • Escherichia coli Infections / psychology*
  • Fear / drug effects
  • Fear / psychology
  • Genes, fos / genetics
  • Hippocampus / drug effects
  • Hippocampus / metabolism
  • Injections
  • Interleukin 1 Receptor Antagonist Protein / pharmacology*
  • Interleukin-6 / biosynthesis
  • Male
  • Memory / drug effects*
  • Memory Disorders / etiology
  • Memory Disorders / prevention & control
  • Memory Disorders / psychology*
  • Nerve Tissue Proteins / biosynthesis*
  • Neuronal Plasticity / drug effects
  • Rats
  • Rats, Inbred BN
  • Rats, Inbred F344
  • Receptors, Interleukin-1 / antagonists & inhibitors*
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Cytoskeletal Proteins
  • Interleukin 1 Receptor Antagonist Protein
  • Interleukin-6
  • Nerve Tissue Proteins
  • Receptors, Interleukin-1
  • activity regulated cytoskeletal-associated protein