Neurogenesis in mouse model of blast induced traumatic brain injury
Nair, Nived Unnikrishnan
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The aim of this thesis was to elucidate the effects of blast-induced traumatic brain injury on the process of neurogenesis in the two stem cell niches - the sub-ventricular zone (SVZ) of the lateral ventricle and the dentate gyrus (DG) of the hippocampus. In this study, there were two conditions used - short term (5 days) and long term (21 days), both denoting the number of days after which the murine brains was perfused. I wanted to know if blast wave exposure may direct the stem cells in these niches to give rise to new daughter cells which may follow a neuronal lineage development. For this purpose, Bromodeoxyuridine (BrDU) was administered to mice for 5 days continuously before blast so that the differentiation of BrdU labeled cells could be investigated after blast. The neuronal lineage cells in the SVZ and DG niches were detected using doublecortin (DCX), a marker for neuronal precursor cells and an indicator of neurogenesis. I used immunohistochemistry and stereology along with image analysis to answer questions pertaining to brain damage, neurogenesis and potential recovery by the endogenous progenitors. Brain damage was assessed by the presence of activated microglia, demyelination, neuronal loss and apoptosis. There was a significant increase in the number of DCX+ cells in the DG of the long term condition murine brains. The results show that neurogenesis is activated in response to blast wave exposure in the SGZ, but not in the SVZ and the cortex.