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Updated: Mar 24, 2026
Isolation of Region-specific Microglia from One Adult Mouse Brain Hemisphere for Deep Single-cell RNA Sequencing
Published on: December 3, 2019
Microglial P2 Purinergic Receptor and Immunomodulatory Gene Transcripts Vary By Region, Sex, and Age in the Healthy
Jessica M Crain1, Jyoti J Watters2
1Program in Cellular and Molecular Biology, University of Wisconsin, Madison, WI 53706; Center for Women's Health Research, University of Wisconsin, Madison, WI 53706.
Abstract:
Inflammatory damage in many neurodegenerative diseases is restricted to certain regions of the CNS, and while microglia have long been implicated in the pathology of many of these disorders, information comparing their gene expression in different CNS regions is lacking. Here we tested the hypothesis that the expression of purinergic receptors, estrogen receptors and other neuroprotective and pro-inflammatory genes differed among CNS regions in healthy mice. Because neurodegenerative diseases vary in incidence by sex and age, we also examined the regional distribution of these genes in male and female mice of four different ages between 21 days and 12 months. We postulated that pro-inflammatory gene expression would be higher in older animals, and lower in young adult females. We found that microglial gene expression differed across the CNS. Estrogen receptor alpha (Esr1) mRNA levels were often lower in microglia from the brainstem/spinal cord than from the cortex, whereas tumor necrosis factor alpha (Tnfα) expression was several times higher. In addition, the regional pattern of gene expression often changed with animal age; for example, no regional differences in P2X7 mRNA levels were detected in 21 day-old animals, but at 7 weeks and older, expression was highest in cerebellar microglia. Lastly, the expression of some genes was sexually dimorphic. In microglia from 12 month-old animals, mRNA levels of inducible nitric oxide synthase, but not Tnfα, were higher in females than males. These data suggest that microglial gene expression is not uniformly more pro-inflammatory in males or older animals. Moreover, microglia from CNS regions in which neuronal damage predominates in neurodegenerative disease do not generally express more pro-inflammatory genes than microglia from regions less frequently affected. This study provides an in-depth assessment of regional-, sex- and age-dependent differences in key microglial transcripts from the healthy mouse CNS.
Insights
Microglial gene expression in the central nervous system (CNS) varies by region, age, and sex. This study reveals that pro-inflammatory gene expression is not uniformly higher in older or male mice across all CNS areas.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Microglia are implicated in neuroinflammation in neurodegenerative diseases.
- Regional differences in microglial gene expression within the CNS are not well understood.
- Sex and age influence disease incidence, suggesting potential differences in microglial responses.
Purpose of the Study:
- To investigate regional variations in microglial gene expression in healthy mice.
- To examine how age and sex affect the expression of neuroprotective and pro-inflammatory genes in microglia.
- To test the hypothesis that pro-inflammatory gene expression is higher in older animals and lower in young adult females.
Main Methods:
- Analysis of microglial gene expression across different CNS regions (brainstem/spinal cord, cortex, cerebellum) in mice.
- Comparison of gene expression in male and female mice at four different ages (21 days to 12 months).
- Quantification of mRNA levels for purinergic receptors, estrogen receptors, and inflammatory genes.
Main Results:
- Microglial gene expression significantly differed across CNS regions.
- Estrogen receptor alpha (Esr1) mRNA was lower in brainstem/spinal cord microglia compared to cortex.
- Tumor necrosis factor alpha (Tnfα) expression was higher in the brainstem/spinal cord.
- P2X7 mRNA levels showed age-dependent regional differences, increasing in the cerebellum with age.
- Sexually dimorphic expression was observed for inducible nitric oxide synthase in older female mice.
Conclusions:
- Microglial gene expression in the healthy CNS is regionally, sexually, and age-dependently regulated.
- Pro-inflammatory gene expression in microglia is not universally elevated in older or male mice.
- Microglia in CNS regions frequently affected by neurodegeneration do not inherently express higher levels of pro-inflammatory genes.
