Reduced microglial Trem2 levels is associated with abnormal synaptic pruning in the developing hippocampus of mice exposed to early life stress

The goal of this project was to assess the effects of two paradigms of early life stress on microglial gene expression in the developing hippocampus of 17-day old mice. Sixty thousands microglia were isolated from the hippocampus of 17-day old mice pups exposed to control (CTL), limited bedding (LB) or unpredictable postnatal stress (UPS) conditions and were processed to assess gene expression using the mouse Glia panel (Nanostring, Cat # XT-Mm Glial profiling CSO). Microglia were isolated using Percoll gradient followed by flow cytometry from 17-day old pups exposed to CTL, LB and UPS condition (N=8 mice per rearing and sex for a total of 48 mice). Gene expression was assessed using the mouse Glia panel (Nanostring, Cat # XT- CSO-M-Glial-12) by running 4 separate batches with 2 mice per rearing group and sex in each batch. The effects of rearing (CTL, LB, UPS) and sex were initially assessed using a 3 X 2 MANOVA (N=8 mice per rearing and sex for a total of 48 mice) for expressed genes (> 20 counts). This analysis identified 87 differentially regulated genes (DRG) for rearing and only few DRG affected by sex (n=13) or interaction between sex and rearing condition (n=5). Based on the prominent rearing effect, advanced-analysis was conducted using the nSolver software to identify DRG between CTL and LB group, CTL and UPS, and LB and UPS with batch as a covariance.