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Updated: Oct 3, 2025
A Model of Epileptogenesis in Rhinal Cortex-Hippocampus Organotypic Slice Cultures
Published on: March 18, 2021
Hypoxia/Ischemia-Induced Rod Microglia Phenotype in CA1 Hippocampal Slices
Daniele Lana1, Elisabetta Gerace2, Giada Magni3
1Section of Clinical Pharmacology and Oncology, Department of Health Sciences, University of Florence, 50139 Florence, Italy.
Abstract:
The complexity of microglia phenotypes and their related functions compels the continuous study of microglia in diseases animal models. We demonstrated that oxygen-glucose deprivation (OGD) induced rapid, time- and space-dependent phenotypic microglia modifications in CA1 stratum pyramidalis (SP) and stratum radiatum (SR) of rat organotypic hippocampal slices as well as the degeneration of pyramidal neurons, especially in the outer layer of SP. Twenty-four h following OGD, many rod microglia formed trains of elongated cells spanning from the SR throughout the CA1, reaching the SP outer layer where they acquired a round-shaped amoeboid phagocytic head and phagocytosed most of the pyknotic, damaged neurons. NIR-laser treatment, known to preserve neuronal viability after OGD, prevented rod microglia formation. In CA3 SP, pyramidal neurons were less damaged, no rod microglia were found. Thirty-six h after OGD, neuronal damage was more pronounced in SP outer and inner layers of CA1, rod microglia cells were no longer detectable, and most microglia were amoeboid/phagocytic. Damaged neurons, more numerous 36 h after OGD, were phagocytosed by amoeboid microglia in both inner and outer layers of CA1. In response to OGD, microglia can acquire different morphofunctional phenotypes which depend on the time after the insult and on the subregion where microglia are located.
Insights
Microglia in the hippocampus rapidly change shape and function after oxygen-glucose deprivation (OGD). These dynamic microglia phenotypes, including rod-shaped and amoeboid forms, are crucial for clearing damaged neurons following brain injury.
Area of Science:
- Neuroscience
- Cell Biology
- Pathology
Background:
- Microglia are the primary immune cells of the central nervous system.
- Microglia exhibit diverse phenotypes and functions that are critical in disease states.
- Understanding microglia dynamics is essential for developing effective therapeutic strategies.
Purpose of the Study:
- To investigate the dynamic phenotypic changes of microglia in response to oxygen-glucose deprivation (OGD) in a rat organotypic hippocampal slice model.
- To correlate microglia morphology and function with neuronal damage and survival after OGD.
- To assess the impact of near-infrared (NIR) laser treatment on microglia activation and neuronal viability.
Main Methods:
- Organotypic hippocampal slice culture from rats.
- Induction of oxygen-glucose deprivation (OGD) to mimic ischemic conditions.
- Time- and space-dependent morphological analysis of microglia.
- Assessment of neuronal damage and phagocytosis by microglia.
- Evaluation of NIR-laser treatment effects.
Main Results:
- OGD induced rapid, time- and region-specific microglia phenotypic changes in the CA1 region.
- Rod-shaped microglia were observed spanning from stratum radiatum to stratum pyramidale, phagocytosing damaged neurons.
- NIR-laser treatment prevented rod microglia formation and preserved neuronal viability.
- At 36 hours post-OGD, amoeboid microglia were prevalent and actively phagocytosed damaged neurons in CA1.
- Neuronal damage was less severe in the CA3 region, with no rod microglia observed.
Conclusions:
- Microglia exhibit distinct morphofunctional phenotypes in response to OGD, influenced by the time post-insult and anatomical location within the hippocampus.
- Microglia play a critical role in clearing neuronal debris following ischemic events.
- NIR-laser treatment shows potential in mitigating OGD-induced neuronal damage by modulating microglia responses.
