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Updated: Jun 15, 2026
Intravital Imaging of Axonal Interactions with Microglia and Macrophages in a Mouse Dorsal Column Crush Injury
Published on: November 23, 2014
Delayed neural damage is induced by iNOS-expressing microglia in a brain injury model
Kenji Ono1, Hiromi Suzuki, Makoto Sawada
1Department of Brain Functions, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601, Japan. k_ono@riem.nagoya-u.ac.jp <k_ono@riem.nagoya-u.ac.jp>
Abstract:
Most CNS diseases begin with inflammation with subsequent neural damage eventually occurring; however, the process leading from the onset of inflammation to neural damage remains obscure. We used an artificial brain injury mouse model and examined how neural damage occurred in the brain parenchyma. The damaged area in each mouse was clearly observed by magnetic resonance imaging (MRI), and the progression of damage was observed to occur in a biphasic manner (acute damage, within 1 week; delayed damage, after 2 weeks). We found that the delayed neural damage was absent in iNOS-deficient mice (iNOS-KO mice). Then, we analyzed brain tissues and determined that delayed neural damage was accompanied by an increase in the levels of NO end products and iNOS expression, with accumulation of iNOS-expressing microglia around the injured area. In addition, the expression of IL-1beta mRNA was increased in areas affected by acute damage, but not in those affected by delayed damage. These findings suggest that delayed neural damage might arise from NO production by iNOS-expressing activated microglia and that such activated microglia might become a therapeutic target for many CNS diseases.
Insights
Delayed neural damage in brain injuries is linked to nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS)-expressing microglia. Targeting these activated microglia may offer new therapeutic strategies for central nervous system (CNS) diseases.
Area of Science:
- Neuroscience
- Immunology
- Pathology
Background:
- Central nervous system (CNS) diseases often involve inflammation preceding neural damage.
- The precise mechanisms linking initial inflammation to subsequent neural damage remain unclear.
- Understanding these mechanisms is crucial for developing effective treatments for CNS disorders.
Purpose of the Study:
- To investigate the process of neural damage following artificial brain injury in a mouse model.
- To elucidate the role of inflammation and specific molecular pathways in delayed neural damage.
- To identify potential therapeutic targets for mitigating neural damage in CNS diseases.
Main Methods:
- Utilized an artificial brain injury mouse model.
- Employed magnetic resonance imaging (MRI) to visualize and track brain damage progression.
- Analyzed brain tissues from wild-type and iNOS-deficient (iNOS-KO) mice.
- Assessed levels of nitric oxide (NO) end products, iNOS expression, and IL-1beta mRNA.
Main Results:
- Neural damage occurred in a biphasic manner: acute (within 1 week) and delayed (after 2 weeks).
- Delayed neural damage was significantly reduced in iNOS-KO mice, indicating a role for iNOS.
- Delayed damage correlated with increased NO products, iNOS expression, and iNOS-expressing microglia accumulation around the injury site.
- IL-1beta mRNA was elevated in acute damage but not in delayed damage areas.
Conclusions:
- Delayed neural damage in the brain parenchyma appears to be mediated by nitric oxide produced by iNOS-expressing activated microglia.
- These findings suggest that activated microglia expressing iNOS are a potential therapeutic target for various CNS diseases.
- Targeting iNOS-expressing microglia could offer a novel strategy for treating neuroinflammatory conditions.
