Electric neurostimulation regulates microglial activation via retinoic acid receptor α signaling

Smadar Goldfarb, Nina Fainstein, Tal Ganz, Dan Vershkov, Marva Lachish, Tamir Ben-Hur*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Brain stimulation by electroconvulsive therapy is effective in neuropsychiatric disorders by unknown mechanisms. Microglial toxicity plays key role in neuropsychiatric, neuroinflammatory and degenerative diseases. We examined the mechanism by which electroconvulsive seizures (ECS) regulates microglial phenotype and response to stimuli. Microglial responses were examined by morphological analysis, Iba1 and cytokine expression. ECS did not affect resting microglial phenotype or morphology but regulated their activation by Lipopolysaccharide stimulation. Microglia were isolated after ECS or sham sessions in naïve mice for transcriptome analysis. RNA sequencing identified 141 differentially expressed genes. ECS modulated multiple immune-associated gene families and attenuated neurotoxicity-associated gene expression. Blood brain barrier was examined by injecting Biocytin-TMR tracer. There was no breakdown of the BBB, nor increase in gene-signature of peripheral monocytes, suggesting that ECS effect is mainly on resident microglia. Unbiased analysis of regulatory sequences identified the induction of microglial retinoic acid receptor α (RARα) gene expression and a putative common RARα–binding motif in multiple ECS-upregulated genes. The effects of AM580, a selective RARα agonist on microglial response to LPS was examined in vitro. AM580 prevented LPS-induced cytokine expression and reactive oxygen species production. Chronic murine experimental autoimmune encephalomyelitis (EAE) was utilized to confirm the role RARα signaling as mediator of ECS-induced transcriptional pathway in regulating microglial toxicity. Continuous intracerebroventricular delivery of AM580 attenuated effectively EAE severity. In conclusion, ECS regulates CNS innate immune system responses by activating microglial retinoic acid receptor α pathway, signifying a novel therapeutic approach for chronic neuroinflammatory, neuropsychiatric and neurodegenerative diseases.

Original languageAmerican English
Pages (from-to)40-53
Number of pages14
JournalBrain, Behavior, and Immunity
Volume96
DOIs
StatePublished - Aug 2021

Bibliographical note

Funding Information:
This study was supported by the Judy & Sidney Swartz Foundation, the Alfred A. Taubman Foundation, and by a gift from Arlene and Stanley Ferman.

Publisher Copyright:
© 2021 The Author(s)

Keywords

  • Electroconvulsive seizures (ECS)
  • Electroconvulsive therapy (ECT)
  • Microglia
  • Neuroinflammation
  • Neurostimulation
  • Neurotoxicity
  • Retinoic acid receptor a (RARa)

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