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Updated: Jun 14, 2025
Sex Differences in Mouse Hippocampal Astrocytes after In-Vitro Ischemia
Published on: October 25, 2016
NS-Pten knockout mice exhibit sex and hippocampal subregion-specific increases in microglia/macrophage density
David A Narvaiz1, Katherine J Blandin1, D Gregory Sullens1
1Department of Psychology and Neuroscience, USA.
Abstract:
Seizures induce hippocampal subregion dependent enhancements in microglia/macrophage phagocytosis and cytokine release that may contribute to the development of epilepsy. As a model of hyperactive mTOR induced epilepsy, neuronal subset specific phosphatase and tensin homolog (NS-Pten) knockout (KO) mice exhibit hyperactive mTOR signaling in the hippocampus, seizures that progress with age, and enhanced hippocampal microglia/macrophage activation. However, it is unknown where microglia/macrophages are most active within the hippocampus of NS-Pten KO mice. We quantified the density of IBA1 positive microglia/macrophages in the CA1, CA2/3, and dentate gyrus of NS-Pten KO and wildtype (WT) male and female mice at 4, 10, and 15 weeks of age. NS-Pten KO mice exhibited an overall increase in the number of IBA1 positive microglia/macrophages in each subregion and in the entire hippocampus. After accounting for differences in size, the whole hippocampus of NS-Pten KO mice still exhibited an increased density of IBA1 positive microglia/macrophages. Subregion analyses showed that this increase was restricted to the dentate gyrus of both male and female NS-Pten KO mice and to the CA1 of male NS-Pten KO mice. These data suggest enhanced microglia/macrophage activity may occur in the NS-Pten KO mice in a hippocampal subregion and sex-dependent manner. Future work should seek to determine whether these region-specific increases in microgliosis play a role in the progression of epilepsy in this model.
Insights
Seizures can worsen epilepsy by activating microglia/macrophages in specific brain regions. In a mouse model, these immune cells were more numerous in the dentate gyrus and CA1, suggesting a role in epilepsy progression.
Area of Science:
- Neuroscience
- Immunology
- Epilepsy Research
Background:
- Seizures can lead to epilepsy through enhanced microglia/macrophage activity in the hippocampus.
- Hyperactive mTOR signaling, as seen in neuronal subset specific phosphatase and tensin homolog (NS-Pten) knockout mice, is linked to epilepsy development and increased immune cell activation.
Purpose of the Study:
- To investigate the specific hippocampal subregions with increased microglia/macrophage activity in the NS-Pten knockout mouse model of epilepsy.
- To determine if this microglial/macrophage activation is dependent on hippocampal subregion and sex.
Main Methods:
- Quantified the density of IBA1 positive microglia/macrophages in the CA1, CA2/3, and dentate gyrus of NS-Pten knockout (KO) and wildtype (WT) mice.
- Analyzed mice at 4, 10, and 15 weeks of age, considering both male and female subjects.
Main Results:
- NS-Pten KO mice showed a significant overall increase in microglia/macrophage numbers across the hippocampus compared to WT mice.
- After adjusting for hippocampal size, the density of microglia/macrophages remained elevated in NS-Pten KO mice.
- Subregion analysis revealed increased microglia/macrophage density specifically in the dentate gyrus (males and females) and the CA1 (males) of NS-Pten KO mice.
Conclusions:
- Microglia/macrophage activation in the NS-Pten KO mouse model of epilepsy is not uniform but occurs in a hippocampal subregion- and sex-dependent manner.
- The dentate gyrus and CA1 are key areas of enhanced immune cell activity, potentially contributing to epilepsy progression.
- Further research is needed to elucidate the role of these region-specific increases in microgliosis in epilepsy development.
