Glial response in early stages of traumatic brain injury

Traumatic brain in jury affects a number of individuals per year and is a major cause of worldwide death and disability. Yet, its pathophysiological mechanism remains unclear. It is well-known that glial cells, including microglia and astrocytes, are activated and involved in tissue damage and repair in the peri-lesion regions after traumatic brain injury; however, global glial responses are rarely reported. The purpose of this study was to investigate the global activation of microglia and astrocytes 1 day after traumatic brain injury. To test this, we used a weight drop device to inflict traumatic brain injury on left side of the brain and performed hematoxylin-eosin staining to detect tissue damage. We used immunohistochemical staining and western blotting to detect the activation of microglia and astrocytes 1 day after TBI. We found that microglia were significantly activated in ipsilateral regions. Interestingly, we found that astrocytes were also significantly activated in the ipsilateral regions, contralateral cortex, and contralateral corpus callosum. These results suggest that a focal damage can cause a global glial reaction.