Perinatal hypoxia-ischemia reduces α 7 nicotinic receptor expression and selective α 7 nicotinic receptor stimulation suppresses inflammation and promotes microglial Mox phenotype

Biomed Res Int. 2014:2014:718769. doi: 10.1155/2014/718769. Epub 2014 Mar 17.

Abstract

Inflammation plays a central role in neonatal brain injury. During brain inflammation the resident macrophages of the brain, the microglia cells, are rapidly activated. In the periphery, α 7 nicotinic acetylcholine receptors ( α 7R) present on macrophages can regulate inflammation by suppressing cytokine release. In the current study we investigated α 7R expression in neonatal mice after hypoxia-ischemia (HI). We further examined possible anti-inflammatory role of α 7R stimulation in vitro and microglia polarization after α 7R agonist treatment. Real-time PCR analysis showed a 33% reduction in α 7R expression 72 h after HI. Stimulation of primary microglial cells with LPS in combination with increasing doses of the selective α 7R agonist AR-R 17779 significantly attenuated TNF α release and increased α 7R transcript in microglial cells. Gene expression of M1 markers CD86 and iNOS, as well as M2 marker CD206 was not influenced by LPS and/or α 7R agonist treatment. Further, Mox markers heme oxygenase (Hmox1) and sulforedoxin-1 (Srx1) were significantly increased, suggesting a polarization towards the Mox phenotype after α 7R stimulation. Thus, our data suggest a role for the α 7R also in the neonatal brain and support the anti-inflammatory role of α 7R in microglia, suggesting that α 7R stimulation could enhance the polarization towards a reparative Mox phenotype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • B7-2 Antigen / biosynthesis
  • Gene Expression Regulation
  • Hypoxia-Ischemia, Brain / drug therapy
  • Hypoxia-Ischemia, Brain / metabolism*
  • Hypoxia-Ischemia, Brain / pathology
  • Inflammation / metabolism
  • Inflammation / pathology
  • Lectins, C-Type / biosynthesis
  • Mannose Receptor
  • Mannose-Binding Lectins / biosynthesis
  • Mice
  • Microglia / metabolism*
  • Microglia / pathology
  • Nitric Oxide Synthase Type II / biosynthesis
  • Receptors, Cell Surface / biosynthesis
  • alpha7 Nicotinic Acetylcholine Receptor / agonists
  • alpha7 Nicotinic Acetylcholine Receptor / biosynthesis*

Substances

  • B7-2 Antigen
  • Cd86 protein, mouse
  • Lectins, C-Type
  • Mannose Receptor
  • Mannose-Binding Lectins
  • Receptors, Cell Surface
  • alpha7 Nicotinic Acetylcholine Receptor
  • Nitric Oxide Synthase Type II
  • Nos2 protein, mouse