Microglial response to sleep deprivation depends on the hippocampal region and paradigm used in adult male mice.

With the current society's focus on high productivity and performance, impaired sleep regimen has become prevalent, affecting as much as 25% of the adult population. Sleep loss can lead to many detrimental consequences, including cognitive impairments. In the brain, the hippocampus is one of the regions most vulnerable to sleep deprivation (SD), often displaying neuronal connectivity changes and reduced synaptic density. Strikingly, acute SD induces brain region- and subregion-specific changes in synaptic plasticity in adult mice, suggesting localized mechanisms of vulnerability. Microglia, the brain's immune cells, are important contributors to synaptic plasticity, and their functions are affected by various paradigms of acute SD, while exhibiting regional and environmental heterogeneity. We thus aimed to compare 2 commonly used but experientially distinct SD paradigms, and explore possible differences in microglial properties across hippocampal subregions, hypothesizing that microglia contribute to the region-specific modulation of synaptic plasticity. We exposed adult male mice to 6 h of SD through the paradigms of gentle handling or novelty exposure. We observed a decreased microglial density with novelty exposure compared to control and gentle handling in the CA1