Defining the microglial transcriptome in the rat subventricular zone (SVZ) after neonatal hypoxia-ischemia (HI).

Purpose: Recent findings indicate a regulatory role of microglia on neurogenesis in the SVZ in health and disease. Microglia in the early postnatal SVZ are not fully maturated and may react differently than adult microglia to injury. We sought to investigate the impact of cortico-striatal neonatal HI injury on the microglial phenotype in the early postnatal SVZ. Results: In comparison to sham SVZ microglia, HI SVZ microglia upregulate both pro- and anti-inflammatory genes as well as neurotrophic genes. HI SVZ microglia do not adopt a M1 or M2 polarization state, but instead share commonly expressed genes with microglia in rodent models of neurodegenerative diseases. Total RNA was extracted from anti-CD11b magnetic bead isolated microglia from the dorsolateral SVZ or M2 supplementary motor cortex (CX) of individual rats: Postnatal day (P) 7 Sprague-Dawley rats were subjected to sham surgery (exposure of the right [ipsilateral] common carotid artery) or HI surgery (temporary occlusion of the ipsilateral common carotid artery and exposure to hypoxia). The anterior dorsolateral SVZ (ipsilateral in HI animals, ipsi- and contralateral in sham animals) and the contralateral CX were microdissected, CD11b+ cells isolated and total RNA extracted at P10 or P20, respectively.