Browsing by Subject "memory deficits"

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  • Anttila, Emmi (Helsingin yliopisto, 2021)
    Mild traumatic brain injury (TBI) is defined as an injury that disrupts the normal functioning of the brain and is the result of external force to the head. It is the most common type of traumatic head injury, and it is common especially in contact sports and within military personnel. Mild TBI typically causes no clear structural changes to the head, but it can induce persistent clinical symptoms, as well as microscopic pathological changes to the brain that may eventually lead to neurodegeneration and increase the risk for several diseases. Mild TBI is a risk factor for several neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, and chronic traumatic encephalopathy. The primary objective of this study was to develop a repetitive mild TBI mouse model for future research purposes in the field of head trauma and neurodegeneration. The injury was induced as a closed head injury with an electromagnetic impactor. Literature and pilot experiments were used to define the parameters of the impactor required to induce a brain injury of desired severity. The characterization criteria of the mild TBI model considered the criteria used to define human mild TBI, as well as long term effects often reported after repetitive mild TBI: neurodegeneration as tau protein related pathology, neuroinflammation, and memory deficits. The secondary objective of this study was to tentatively test a prolyl oligopeptidase (PREP) inhibitor on the behavioral and histological effects of mild TBI. The functioning of the mild TBI model was studied by histopathological and behavioral assessments. After baseline behavioral assessment and repetitive (1 injury every 24 hours altogether 5 times) mild TBI inductions, the mice were monitored for approximately 3 months, during which several rounds of behavioral tests were performed. Barnes maze and novel object recognition tests were used to assess memory functions, and locomotor activity test was used to assess general locomotor activity. After euthanasia, brain histopathology was performed to study the amount of tau protein and the level of neuroinflammation. Due to the low number of animals in the study, the results are directional and need to be confirmed in subsequent studies. The histopathology showed greater amount of neuroinflammation and tau protein in the brains of injured mice, but statistical evaluations could not be made. Memory functions were slightly worse in the injured mice compared to controls, but significance of the results is unclear. Locomotor activity was not influenced by the mild TBIs. PREP inhibition treatment increased the locomotor activity of the mice, but the significance is unclear. The mild TBI model seems promising and the characterization criteria were partially met. The results of the study need to be verified in subsequent studies with a greater amount of animals. The model developed here can be used to study the involvement of head trauma in neurodegeneration, as well as treatment alternatives to changes caused by mild TBIs. As there currently are no curative treatments to neurodegenerative diseases, research regarding neurodegeneration and its risk factors is highly important.