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Updated: Jun 13, 2026
Two-photon Imaging of Microglial Processes' Attraction Toward ATP or Serotonin in Acute Brain Slices
Published on: January 31, 2019
NO mediates microglial response to acute spinal cord injury under ATP control in vivo
Payam Dibaj1, Fabien Nadrigny, Heinz Steffens
1Department of Neurology, Georg August University of Göttingen, Germany.
Abstract:
To understand the pathomechanisms of spinal cord injuries will be a prerequisite to develop efficient therapies. By investigating acute lesions of spinal cord white matter in anesthetized mice with fluorescently labeled microglia and axons using in vivo two-photon laser-scanning microscopy (2P-LSM), we identified the messenger nitric oxide (NO) as a modulator of injury-activated microglia. Local tissue damages evoked by high-power laser pulses provoked an immediate attraction of microglial processes. Spinal superfusion with NO synthase and guanylate cyclase inhibitors blocked these extensions. Furthermore, local injection of the NO-donor spermine NONOate (SPNO) or the NO-dependent second messenger cGMP induced efficient migration of microglial cells toward the injection site. High-tissue levels of NO, achieved by uniform superfusion with SPNO and mimicking extended tissue damage, resulted in a fast conversion of the microglial shape from ramified to ameboid indicating cellular activation. When the spinal white matter was preconditioned by increased, ambient ATP (known as a microglial chemoattractant) levels, the attraction of microglial processes to local NO release was augmented, whereas it was abolished at low levels of tissue ATP. Because both signaling molecules, NO and ATP, mediate acute microglial reactions, coordinated pharmacological targeting of NO and purinergic pathways will be an effective mean to influence the innate immune processes after spinal cord injury.
Insights
Nitric oxide (NO) activates microglia in spinal cord injuries. Targeting NO and ATP pathways may improve innate immune responses and therapies for spinal cord injury.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Understanding spinal cord injury (SCI) pathomechanisms is crucial for developing effective therapies.
- Microglia play a key role in the innate immune response to SCI.
- Identifying molecular mediators of microglial activation is essential for therapeutic intervention.
Purpose of the Study:
- To investigate the role of nitric oxide (NO) in modulating microglial responses to acute spinal cord white matter injury.
- To explore the interaction between NO and ATP signaling in microglial activation after SCI.
Main Methods:
- In vivo two-photon laser-scanning microscopy (2P-LSM) was used to visualize microglia and axons in anesthetized mice with acute spinal cord lesions.
- Pharmacological agents were used to inhibit or donate nitric oxide (NO) and its downstream messenger cyclic guanosine monophosphate (cGMP).
- Adenosine triphosphate (ATP) levels were manipulated to assess their influence on NO-mediated microglial responses.
Main Results:
- Local tissue damage induced rapid microglial process extension, which was blocked by inhibiting NO synthesis and signaling.
- NO donors and cGMP induced microglial migration towards the injection site.
- Elevated NO levels promoted microglial activation, characterized by a shape change from ramified to ameboid.
- Increased ambient ATP levels augmented, while low ATP levels abolished, the chemoattraction of microglial processes to NO release.
Conclusions:
- Nitric oxide (NO) acts as a key modulator of injury-activated microglia in the spinal cord.
- Both NO and ATP signaling pathways are critical for acute microglial reactions following SCI.
- Coordinated pharmacological targeting of NO and purinergic pathways presents a promising strategy to modulate innate immune processes and potentially treat spinal cord injuries.
