Acute Stress, Induced by IFNγ  + Aβ, and Chronic Stress, Induced by Age, Affect Microglia in a Sex-Specific Manner.

Microglial phenotype changes in the aged brain, and also in neurodegenerative diseases, and it is generally accepted that these changes at least contribute to the inflammation that can have detrimental effects on brain health. Accumulating data have determined that there are multiple microglial activation states with consistent findings indicating that with stressors including age, a switch towards an inflammatory phenotype occurs. Among the changes that accompany this is a change in metabolism, whereby glycolysis is increased in microglia. Here, we asked whether sex impacted on the response of microglia to two stressors, interferon-γ + amyloid-β (IFNγ  + Aβ) and age. The data show that IFNγ  + Aβ triggered cells from female mice to adopt a glycolytic phenotype. Metabolism was also altered with age; microglia from aged male mice responded by increasing oxidative phosphorylation, and microglial motility was preserved, contrasting with microglia from female mice where motility was compromised. We conclude that sex is a significant variable in the responses of microglia to stressors.