Related Experiment Video
Updated: Jan 21, 2026
Quantifying Synapses: an Immunocytochemistry-based Assay to Quantify Synapse Number
Published on: November 16, 2010
Physiological Implications of Microglia-Synapse Interactions
Hiroaki Wake1,2,3, Hiroshi Horiuchi4,5, Daisuke Kato1,4
1Division of System Neuroscience, Kobe University Graduate School of Medicine, Kobe, Japan.
Abstract:
Microglia are the sole immune responding cells in the central nervous system. Their role as neuroimmune cells in the pathogenesis of various neurodegenerative and infectious diseases of the brain have been extensively studied. Upon brain disease and infection, they adopt an activated phenotype associated with the release of cytokines and neurotrophic factors and resulting in neuroprotective or neurotoxic outcomes. However, microglia are resident also in the healthy or physiological brain, but much less is known about their role(s) in the healthy brain, partly due to technical limitations regarding investigation of these highly reactive cells in the intact brain. Recent developments in molecular probes and in vivo optical imaging techniques has now helped to characterize microglia in the physiological or healthy brain. In vivo two-photon imaging of fluorescently labeled microglia have revealed that they are highly motile cells in the healthy brain, extending and retracting their processes that extend from a largely stationary cell soma. In this chapter, we briefly summarize some of the physiological functions of microglia in the uninjured brain, with a focus on interactions they have with synapses.
Insights
Microglia, the brain's immune cells, are highly motile in the healthy brain, constantly extending processes. New imaging techniques reveal their crucial roles in the physiological brain, including synapse interactions.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are the primary immune cells of the central nervous system.
- Their roles in neurodegenerative and infectious diseases are well-studied, involving cytokine release and neuroprotection/neurotoxicity.
- Limited understanding exists regarding microglia functions in the healthy brain due to technical challenges.
Purpose of the Study:
- To characterize microglia in the physiological brain.
- To investigate the functions of microglia in the absence of injury.
- To focus on microglia-synapse interactions in the healthy brain.
Main Methods:
- Utilized advanced molecular probes.
- Employed in vivo optical imaging techniques.
- Specifically used in vivo two-photon imaging of fluorescently labeled microglia.
Main Results:
- Demonstrated that microglia are highly motile cells in the healthy brain.
- Observed microglia extending and retracting processes from a stationary cell body.
- Provided insights into the dynamic behavior of microglia in the physiological state.
Conclusions:
- Recent imaging advancements allow for better characterization of microglia in healthy brains.
- Microglia exhibit significant motility and process extension/retraction in the uninjured brain.
- Further research into physiological microglia functions, particularly synapse interactions, is warranted.
Related Concept Videos
02:47The Synapse
01:26Chemical Synapses
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
01:26Chemical Synapses
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
01:28Electrical Synapses
Gap junctions allow the current to pass directly from one cell to the next. In contrast, in the chemical synapse, the neurotransmitters carry the information through the synaptic cleft from one neuron to the next. They consist of two...
01:25Overview of Synapses
01:25Physiological Barriers
The blood endothelial barrier is the most porous of these. It allows all small ionized, un-ionized, and lipophilic molecules to pass through the endothelial lining into the interstitial space...