Mild blast-induced traumatic brain injury (bTBI) is a modality of injury that has been of major concern considering a large number of military personnel exposed to the blast wave from explosives. bTBI results from the propagation of high-pressure static blast forces and their subsequent energy transmission within brain tissue. Current literature presents a neuro-centric approach to the role of mitochondria dynamics dysfunction in bTBI; however, changes in astrocyte-specific mitochondrial dynamics have not been characterized. As a result of fission and fusion, the mitochondrial structure is constantly altering shape to respond to physiological stimuli or stress insults by adapting structure and function, which are intimately connected. Dysregulation of the protein regulator of mitochondrial fission, DRP1, and upregulation in the phosphorylation of DRP1 at the serine 616 site is reported to play a crucial role in astrocytic mitochondrial dysfunction, favoring fission over fusion post-TBI. Astrocytic mitochondria are starting to be recognized to play an essential role in overall brain metabolism, synaptic transmission, and neuron protection. Mitochondria are vulnerable to injury insults leading to the worsening of mitochondrial fission and increased mitochondrial fragmentation. In this study, a combination of in vitro and in vivo bTBI models were used to examine the effect of blast on astrocytic mitochondrial dynamics. Acute differential remodeling of the astrocytic mitochondrial network was observed, accompanied by an acute (4hr) and sub-acute (7 days) activation of the GTP-protein DRP1. Further, results showed a time-dependent reactive astrocyte phenotype transition in the rat hippocampus. This discovery can lead to innovative therapeutics targets to help prevent secondary injury cascades that involve mitochondria dysfunction. / Doctor of Philosophy / Blast-induced traumatic brain injury (bTBI) is a modality of injury that has become prominent considering a large number of military personnel exposed to a blast wave caused by explosives. Blast injury results from the energy transmission of the blast wave to the brain. Within the brain, there are specialized cells, called astrocytes, that help maintain a healthy environment. This work investigates the role that astrocytes play during the injury recovery process. Within the astrocytes, there are organelles called mitochondria, that help maintain the energy for the cell. The number and function of mitochondria can change in response to the brain injury. They can increase in number by a process called fission and they can decrease in number by a process called fusion. These events effect the function of the mitochondria. Researchers have methods that can identify changes in the number and function of the mitochondria. In this work, astrocyte mitochondrial dynamics were examined and compared using models of bTBI. We found significant changes in the mitochondria of astrocytes, which could lead to an unhealthy environment in the brain. This discovery can lead to new treatments for patients that may improve their quality of life following bTBI.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/113140 |
| Date | 11 January 2023 |
| Creators | Guilhaume Correa, Fernanda |
| Contributors | Graduate School, VandeVord, Pamela J., Pickrell, Alicia M., Sontheimer, Harald W., Olsen, Michelle Lynne |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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