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Updated: Mar 14, 2026
Simultaneous Imaging of Microglial Dynamics and Neuronal Activity in Awake Mice
Published on: August 23, 2022
Spontaneous Ca2+ transients in mouse microglia
Laura Korvers1, Amanda de Andrade Costa1, Martin Mersch1
1Max-Delbrueck-Centrum for Molecular Medicine (MDC) in the Helmholtz Association, Cellular Neurosciences, Robert-Roessle-Str. 10, 13092 Berlin, Germany.
Abstract:
Microglia are the resident immune cells in the central nervous system and many of their physiological functions are known to be linked to intracellular calcium (Ca2+) signaling. Here we show that isolated and purified mouse microglia-either freshly or cultured-display spontaneous and transient Ca2+ elevations lasting for around ten to twenty seconds and occurring at frequencies of around five to ten events per hour and cell. The events were absent after depletion of internal Ca2+ stores, by phospholipase C (PLC) inhibition or blockade of inositol-1,4,5-trisphosphate receptors (IP3Rs), but not by removal of extracellular Ca2+, indicating that Ca2+ is released from endoplasmic reticulum intracellular stores. We furthermore provide evidence that autocrine ATP release and subsequent activation of purinergic P2Y receptors is not the trigger for these events. Spontaneous Ca2+ transients did also occur after stimulation with Lipopolysaccharide (LPS) and in glioma-associated microglia, but their kinetics differed from control conditions. We hypothesize that spontaneous Ca2+ transients reflect aspects of cellular homeostasis that are linked to regular and patho-physiological functions of microglia.
Insights
Resident immune cells in the brain, microglia, exhibit spontaneous calcium (Ca2+) signaling. This signaling originates from internal stores and is crucial for microglial homeostasis and function.
Area of Science:
- Neuroimmunology
- Cellular Physiology
- Calcium Signaling
Background:
- Microglia are key immune cells in the central nervous system.
- Their functions are intricately linked to intracellular calcium (Ca2+) signaling pathways.
Purpose of the Study:
- To investigate spontaneous intracellular Ca2+ transients in isolated mouse microglia.
- To determine the source and triggers of these Ca2+ events.
Main Methods:
- Isolation and purification of mouse microglia (fresh and cultured).
- Measurement of intracellular Ca2+ using fluorescence imaging.
- Pharmacological inhibition of phospholipase C (PLC) and inositol-1,4,5-trisphosphate receptors (IP3Rs).
- Assessment of Ca2+ signaling in LPS-stimulated and glioma-associated microglia.
Main Results:
- Isolated microglia display spontaneous, transient Ca2+ elevations (10-20 seconds duration, 5-10 events/hour/cell).
- These events depend on internal Ca2+ stores (endoplasmic reticulum) and are independent of extracellular Ca2+.
- Autocrine ATP release and P2Y receptor activation do not trigger these transients.
- Spontaneous Ca2+ transients are altered in LPS-stimulated and glioma-associated microglia.
Conclusions:
- Spontaneous Ca2+ transients in microglia originate from intracellular stores.
- These signaling events are a fundamental aspect of microglial cellular homeostasis.
- Understanding these transients is vital for comprehending both normal and pathological microglial functions.
