Capillary blood flow around microglial somata determines dynamics of microglial processes in ischemic conditions
| Autor: | Hideki Hida, Sergei A. Kirov, Tadashi Masuda, Deborah Croom |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Pathology
medicine.medical_specialty Photochemistry Green Fluorescent Proteins Ischemia Biology Environment Article Brain Ischemia Brain ischemia Cellular and Molecular Neuroscience Mice In vivo medicine Image Processing Computer-Assisted Animals Carotid Stenosis Neocortex Microscopy Confocal Microglia Thrombosis Blood flow Macrophage Activation medicine.disease Capillaries Heart Arrest Stroke medicine.anatomical_structure Neurology nervous system Cerebrovascular Circulation Reperfusion Injury Biophysics Energy Metabolism Perfusion Reperfusion injury |
| Zdroj: | Glia. 59(11) |
| ISSN: | 1098-1136 |
| Popis: | Microglia are the resident immune cells in the brain. Under normal conditions, resting ramified microglia constantly extend and retract fine processes while performing immunological surveillance. In ischemia, microglia become activated as demonstrated by morphological changes during deramification leading to transformation from ramified to amoeboid form. In vivo two-photon microscopy of enhanced green fluorescent protein (EGFP)-expressing microglia in mouse neocortex was used to examine microglial dynamics during the early periods of focal and global ischemia. A penumbra-like "area-at-risk" surrounded by a square-shaped area of severely hypoperfused tissue was created by laser-induced photothrombosis. The dynamics of microglial processes in the area-at-risk was strongly correlated with capillary blood flow (BF) measured within 10 μm of microglial somata. Changes in BF around distal microglial processes (30 μm from somata) had no effect on microglial dynamics. A severe reduction of capillary BF near somata by 84% ± 6% resulted in initiation of microglial deramification, suggesting activation. A moderate decrease in BF near somata by 22% ± 5% or increase by 87% ± 10%, reflecting a redistribution of capillary BF, had no effect on microglial morphology. Complete BF loss during cardiac arrest (CA) or transient bilateral common carotid artery occlusion (BCCAO) entirely stalled all microglial processes without structural changes. Reperfusion after BCCAO induced recovery of microglial dynamics to preocclusion values. These findings suggest that during ischemia, the severe drop in BF around microglial somata coincides with morphological activation. However, this activation requires some residual BF, because complete perfusion loss (as during BCCAO and CA) did not support microglial deramification. |
| Databáze: | OpenAIRE |
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