Removal of microglial-specific MyD88 signaling alters dentate gyrus doublecortin and enhances opioid addiction-like behaviors.

Journal Article (Journal Article)

Drugs of abuse promote a potent immune response in central nervous system (CNS) via the activation of microglia and astrocytes. However, the molecular mechanisms underlying microglial activation during addiction are not well known. We developed and functionally characterized a novel transgenic mouse (Cx3cr1-CreBTtg/0:MyD88f/f [Cretg/0]) wherein the immune signaling adaptor gene, MyD88, was specifically deleted in microglia. To test the downstream effects of loss of microglia-specific MyD88 signaling in morphine addiction, Cretg/0 and Cre0/0 mice were tested for reward learning, extinction, and reinstatement using a conditioned place preference (CPP) paradigm. There were no differences in drug acquisition, but Cretg/0 mice had prolonged extinction and enhanced reinstatement compared to Cre0/0 controls. Furthermore, morphine-treated Cretg/0 mice showed increased doublecortin (DCX) signal relative to Cre0/0 control mice in the hippocampus, indicative of increased number of immature neurons. Additionally, there was an increase in colocalization of microglial lysosomal marker CD68 with DCX+cells in morphine-treated Cretg/0 mice but not in Cre0/0 or drug-naŃ—ve mice, suggesting a specific role for microglial MyD88 signaling in neuronal phagocytosis in the hippocampus. Our results show that MyD88 deletion in microglia may negatively impact maturing neurons within the adult hippocampus and thus reward memories, suggesting a novel protective role for microglia in opioid addiction.

Full Text

Duke Authors

Cited Authors

  • Rivera, PD; Hanamsagar, R; Kan, MJ; Tran, PK; Stewart, D; Jo, YC; Gunn, M; Bilbo, SD

Published Date

  • February 2019

Published In

Volume / Issue

  • 76 /

Start / End Page

  • 104 - 115

PubMed ID

  • 30447281

Pubmed Central ID

  • PMC6348129

Electronic International Standard Serial Number (EISSN)

  • 1090-2139

Digital Object Identifier (DOI)

  • 10.1016/j.bbi.2018.11.010


  • eng

Conference Location

  • Netherlands