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Updated: Dec 30, 2025
Isolation and Whole-Cell Patch-Clamp Recording of Hippocampal Microglia from Adult Mice
Published on: September 27, 2024
Microglia alter the threshold of spreading depolarization and related potassium uptake in the mouse brain
Dániel P Varga1, Ákos Menyhárt1, Balázs Pósfai2,3
1Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary.
Abstract:
Selective elimination of microglia from the brain was shown to dysregulate neuronal Ca2+ signaling and to reduce the incidence of spreading depolarization (SD) during cerebral ischemia. However, the mechanisms through which microglia interfere with SD remained unexplored. Here, we identify microglia as essential modulators of the induction and evolution of SD in the physiologically intact brain in vivo. Confocal- and super-resolution microscopy revealed that a series of SDs induced rapid morphological changes in microglia, facilitated microglial process recruitment to neurons and increased the density of P2Y12 receptors (P2Y12R) on recruited microglial processes. In line with this, depolarization and hyperpolarization during SD were microglia- and P2Y12R-dependent. An absence of microglia was associated with altered potassium uptake after SD and increased the number of c-fos-positive neurons, independently of P2Y12R. Thus, the presence of microglia is likely to be essential to maintain the electrical elicitation threshold and to support the full evolution of SD, conceivably by interfering with the extracellular potassium homeostasis of the brain through sustaining [K+]e re-uptake mechanisms.
Insights
Microglia are essential for brain electrical activity, regulating spreading depolarization (SD) by modulating neuronal signaling and potassium levels. Their absence disrupts these processes, impacting neuronal excitability.
Area of Science:
- Neuroscience
- Neuroimmunology
- Cellular Electrophysiology
Background:
- Microglia's role in regulating neuronal excitability and spreading depolarization (SD) during cerebral ischemia is known, but the underlying mechanisms are unclear.
- Previous studies indicated that selective elimination of microglia affects neuronal calcium signaling and reduces SD incidence in ischemic conditions.
Purpose of the Study:
- To investigate the mechanisms by which microglia modulate the induction and progression of spreading depolarization (SD) in a healthy brain in vivo.
- To elucidate the role of microglia and P2Y12 receptors (P2Y12R) in neuronal depolarization and hyperpolarization during SD events.
Main Methods:
- Utilized confocal and super-resolution microscopy to observe microglial morphological and functional changes in response to SD.
- Investigated the dependence of SD on microglia and P2Y12R through in vivo experiments.
- Assessed potassium uptake and neuronal activation (c-fos expression) in the absence of microglia.
Main Results:
- SD induced rapid microglial morphological changes, including process recruitment to neurons and increased P2Y12R density on these processes.
- Neuronal depolarization and hyperpolarization during SD were dependent on both microglia and P2Y12R.
- Microglia absence led to altered post-SD potassium uptake and increased c-fos-positive neurons, independent of P2Y12R.
Conclusions:
- Microglia are crucial modulators of SD induction and evolution in the intact brain.
- Microglia likely maintain the electrical elicitation threshold for SD by supporting extracellular potassium ([K+]e) re-uptake mechanisms.
- The findings highlight microglia's essential role in brain electrical homeostasis.
