AT1 receptor antagonism does not influence early radiation-induced changes in microglial activation or neurogenesis in the normal rat brain

Kelly R. Conner, M. Elizabeth Forbes, Won Hee Lee, Yong Woo Lee, David R. Riddle

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Blockers of the renin-angiotensin-aldosterone system (RAAS) ameliorate cognitive deficits and some aspects of brain injury after whole-brain irradiation. We investigated whether treatment with the angiotensin II type 1 receptor antagonist L-158,809 at a dose that protects cognitive function after fractionated whole-brain irradiation reduced radiation-induced neuroinflammation and changes in hippocampal neurogenesis, well-characterized effects that are associated with radiation-induced brain injury. Male F344 rats received L-158,809 before, during and after a single 10-Gy dose of radiation. Expression of cytokines, angiotensin II receptors and angiotensin-converting enzyme 2 was evaluated by real-time PCR 24 h, 1 week and 12 weeks after irradiation. At the latter times, microglial density and proliferating and activated microglia were analyzed in the dentate gyrus of the hippocampus. Cell proliferation and neurogenesis were also quantified in the dentate subgranular zone. L-158,809 treatment modestly increased mRNA expression for Ang II receptors and TNF-α but had no effect on radiation-induced effects on hippocampal microglia or neurogenesis. Thus, although L-158,809 ameliorates cognitive deficits after whole-brain irradiation, the drug did not mitigate the neuroinflammatory microglial response or rescue neurogenesis. Additional studies are required to elucidate other mechanisms of normal tissue injury that may be modulated by RAAS blockers.

Original languageEnglish (US)
Pages (from-to)71-83
Number of pages13
JournalRadiation Research
Volume176
Issue number1
DOIs
StatePublished - Jul 2011
Externally publishedYes

ASJC Scopus subject areas

  • Radiation
  • Biophysics
  • Radiology Nuclear Medicine and imaging

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