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Updated: Oct 1, 2025
A Cell Culture Model for Studying the Role of Neuron-Glia Interactions in Ischemia
Published on: November 14, 2020
Cross-talk between GABAergic postsynapse and microglia regulate synapse loss after brain ischemia
Teresa Cramer1, Raminder Gill2, Zahra S Thirouin3
1Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zürich, Switzerland.
Abstract:
Microglia interact with neurons to facilitate synapse plasticity; however, signal(s) contributing to microglia activation for synapse elimination in pathology are not fully understood. Here, using in vitro organotypic hippocampal slice cultures and transient middle cerebral artery occlusion (MCAO) in genetically engineered mice in vivo, we report that at 24 hours after ischemia, microglia release brain-derived neurotrophic factor (BDNF) to downregulate glutamatergic and GABAergic synapses within the peri-infarct area. Analysis of the cornu ammonis 1 (CA1) in vitro shows that proBDNF and mBDNF downregulate glutamatergic dendritic spines and gephyrin scaffold stability through p75 neurotrophin receptor (p75NTR) and tropomyosin receptor kinase B (TrkB) receptors, respectively. After MCAO, we report that in the peri-infarct area and in the corresponding contralateral hemisphere, similar neuroplasticity occurs through microglia activation and gephyrin phosphorylation at serine-268 and serine-270 in vivo. Targeted deletion of the Bdnf gene in microglia or GphnS268A/S270A (phospho-null) point mutations protects against ischemic brain damage, neuroinflammation, and synapse downregulation after MCAO.
Insights
Microglia release brain-derived neurotrophic factor (BDNF) to eliminate synapses after stroke. Targeting BDNF or gephyrin phosphorylation protects against ischemic brain damage and neuroinflammation.
Area of Science:
- Neuroscience
- Neuroinflammation
- Stroke Research
Background:
- Microglia modulate synaptic plasticity, but their role in pathological synapse elimination remains unclear.
- Understanding microglia-neuron signaling is crucial for developing stroke therapies.
Purpose of the Study:
- To elucidate the molecular mechanisms by which microglia contribute to synapse loss following ischemic stroke.
- To investigate the role of brain-derived neurotrophic factor (BDNF) in microglia-mediated synapse elimination.
Main Methods:
- In vitro organotypic hippocampal slice cultures and in vivo transient middle cerebral artery occlusion (MCAO) models.
- Genetic manipulation in mice including targeted deletion of microglial *Bdnf* and phospho-null mutations in gephyrin (Gphn).
- Analysis of synaptic changes, neuroinflammation, and phosphorylation states in vivo and in vitro.
Main Results:
- Microglia release BDNF 24 hours post-ischemia, downregulating glutamatergic and GABAergic synapses in the peri-infarct area.
- BDNF signaling via p75NTR and TrkB receptors affects dendritic spines and gephyrin scaffold stability.
- Microglia activation and gephyrin phosphorylation (Ser268/270) occur in peri-infarct and contralateral hemispheres post-MCAO.
- Targeting microglial BDNF or Gphn phospho-null mutations reduced ischemic brain damage, neuroinflammation, and synapse loss.
Conclusions:
- Microglial BDNF plays a critical role in synapse elimination after ischemic stroke.
- Gephyrin phosphorylation is a key event in microglia-mediated synapse downregulation.
- Targeting the microglial BDNF-gephyrin pathway offers a potential therapeutic strategy for stroke recovery.
