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Updated: Apr 6, 2026
Surgical Approach for Middle Cerebral Artery Occlusion and Reperfusion Induced Stroke in Mice
Published on: October 20, 2016
Effect of Sema4D on microglial function in middle cerebral artery occlusion mice
Toshinori Sawano1, Fumiya Watanabe1, Mitsuko Ishiguchi1,2
1Group of Neurobiology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan.
Abstract:
Cerebral ischemia evokes neuroinflammatory response. Inflammatory stimulation induces microglial activation, such as changes of their morphology from ramified to ameboid, expression of iNOS and cytokines, and the elevation of proliferative activity. Activated microglia play important roles in pathogenesis of cerebral ischemia. A previous study indicated that Sema4D promoted iNOS expression in cultured microglia; however, roles of Sema4D on microglial activation in ischemic injury remains unclear. We investigated the effect of Sema4D-deficiency on microglial activation by using permanent middle cerebral artery occlusion (MCAO) in mice. In this study, ischemia-induced activated microglia were classified into activated-ramified microglia and ameboid microglia based on their morphology. We demonstrated that the rate of iNOS expression in activated-ramified microglia was lower than that in ameboid microglia, while the most proliferating microglia were activated-ramified microglia but not ameboid microglia after cerebral ischemia. Sema4D-deficiency decreased the number of ameboid microglia and iNOS-expressing activated-ramified microglia in the peri-ischemic cortex. These changes by Sema4D-deficiency contributed to the reduction of NO production that was estimated by nitrite concentration in ischemic cortex. On the other hand, Sema4D-deficiency promoted proliferation of microglia in the peri-ischemic cortex. Importantly, ischemia-induced apoptosis and postischemic behavioral abnormality were moderated in Sema4D(-/-) mice. These findings suggest that Sema4D promotes cytotoxic activation of microglia and inhibits functional recovery after cerebral ischemia.
Insights
Sema4D deficiency reduces harmful microglial activation and nitric oxide production after stroke. This neuroprotective effect improves functional recovery and reduces brain injury in mouse models of cerebral ischemia.
Area of Science:
- Neuroscience
- Immunology
- Pathology
Background:
- Cerebral ischemia triggers neuroinflammation, involving microglial activation.
- Activated microglia contribute to ischemic brain injury.
- The role of Sema4D in microglial activation during ischemic stroke is unknown.
Purpose of the Study:
- To investigate the effect of Sema4D deficiency on microglial activation and outcomes following cerebral ischemia.
- To elucidate the role of Sema4D in regulating microglial phenotypes and functions in the ischemic brain.
Main Methods:
- Permanent middle cerebral artery occlusion (MCAO) model in Sema4D-deficient (Sema4D(-/-)) and wild-type mice.
- Morphological classification of microglia (ramified vs. ameboid).
- Assessment of inducible nitric oxide synthase (iNOS) expression, microglial proliferation, nitric oxide (NO) production (nitrite concentration), apoptosis, and behavioral deficits.
Main Results:
- Sema4D deficiency reduced ameboid microglia and iNOS-expressing ramified microglia in the peri-ischemic cortex.
- Nitrite levels were decreased in Sema4D(-/-) mice, indicating reduced NO production.
- Sema4D deficiency promoted microglial proliferation but attenuated ischemia-induced apoptosis and behavioral deficits.
Conclusions:
- Sema4D promotes pro-inflammatory and cytotoxic microglial activation after cerebral ischemia.
- Sema4D deficiency confers neuroprotection by reducing microglial-mediated damage and enhancing functional recovery.
- Targeting Sema4D may represent a therapeutic strategy for ischemic stroke.
