The Effects of Traumatic Brain Injury in Alpha Synuclein and Dopamine Regulation

描述(申请人提供)：创伤性脑损伤(TBI)在美国每年以每10万人200人的发病率发生，由于包括多巴胺(DA)在内的各种神经递质系统的破坏，导致长期的功能和认知障碍。根据我们过去的研究和文献中的发现，颅脑损伤可能同时诱导神经元DA的增加和α-突触核蛋白(AS)的聚集。AS聚集可导致DA合成和再摄取的失调，导致细胞内DA过量，细胞内DA过量可导致AS聚集。从这些证据可以清楚地看出，DA和AS调节可能是相互关联的。阐明AS病理与DA功能障碍之间的联系将提高我们对脑外伤后认知功能障碍机制的认识，并有助于制定预防和减少DA神经传递功能障碍的治疗策略。此外，它可能为我们提供一个关于脑外伤可能导致未来神经退行性疾病(如联核病)风险的洞察力。我们推测，颅脑损伤后DA的急性升高可能是AS聚集的重要因素，而AS的聚集可能进一步促进DA的失调。来支持这一假设。具体目标1将检测抑制DA合成或代谢的药理作用，以防止因急性组织DA升高而导致的AS聚集。Western blotting和免疫组织化学方法证实AS的聚集。具体目标2将通过比较野生型和AS基因敲除小鼠在调节DA的酶的水平和活性以及DA本身的水平和释放方面的差异，来研究AS聚集体对DA调节的影响。酶水平将通过Western blotts进行测定，酶活性将通过高效液相色谱测定产物进行评估。将使用高效液相色谱和体内微透析来确定DA的水平和释放。本项目研究脑外伤后神经递质多巴胺调节功能的丧失可能是由于α-突触核蛋白的病理变化所致。了解这一机制将有助于我们制定治疗策略，以治疗脑外伤后的功能障碍和未来可能发生的神经退行性疾病。 注：下面以基本上未经编辑的形式提供了对个别审查员的批评。这些评论是在审查会议之前编写的，在会议讨论之后可能没有更新或修订。因此，它们可能不能完全反映个别审评员在小组讨论结束时的最后意见或小组的最终多数意见。以上讨论摘要概述了小组讨论的最终结果。

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) occurs in the United States at an incidence of 200 per 100,000 people annually, causing long lasting functional and cognitive deficits due to disruptions of various neurotransmitter systems, including dopamine (DA). Based on our past studies and findings in the literature, TBI may induce both DA increase in neurons and aggregation of a-synuclein (AS). AS aggregation can induce dysregulation of DA synthesis and reuptake leading to excess DA intracellularly, and intracellular DA excess can lead to AS aggregation. It is clear from these evidences that DA and AS regulation may be interrelated. Clarifying the link between AS pathology and DA dysfunction will improve our understanding of the mechanism of cognitive deficits following TBI and contribute to development of therapeutic strategies to prevent and minimize DA neurotransmission deficits. Furthermore, it may provide us with an insight into how TBI may lead to future risk of neurodegenerative diseases like synucleinopathies. We hypothesize that the acute DA increase after TBI may be a significant contributor to AS aggregation, and this aggregation of AS may furthermore contribute to dysregulation of DA. To support this hypothesis. Specific Aim 1 will examine the effect of inhibiting DA synthesis or metabolism pharmacologically to prevent AS aggregation due to acute tissue DA increase after TBI. Western blotting and immunohistochemistry will be performed to confirm aggregation of AS. Specific Aim 2 will examine the effect of AS aggregates on DA regulation by comparing the differences between wild type and AS knockout mice in the levels and activities of enzymes regulating DA as well as level and release of DA itself. Enzyme levels will be measured by Western blots and enzyme activities will be assessed by measuring the products by high performance liquid chromatography. High performance liquid chromatography and microdialysis in vivo will be used to confirm the levels and release of DA. This project investigates how the loss of regulation of neurotransmitter dopamine occurring after TBI may be due to the affects of pathological changes in a-synuclein protein. Understanding this mechanism will help us develop therapeutic strategies to treat functional deficits after TBI and possible future development of neurodegenerative diseases. NOTE: The critiques of individual reviewers are provided below in an essentially unedited form. These critiques were prepared prior to the review meeting and may not have been updated or revised subsequent to the discussion at the meeting. Therefore, they may not fully reflect the final opinions of the individual reviewers at the close of group discussion or the final majority opinion of the group. The Resume and Summary of Discussion above summarizes the final outcome of the group discussion.