Translational Study of Blast mTBI Effects on Locus Ceruleus-Cerebellar Network Structure and Function

由爆炸引起的爆炸超压引起的轻微创伤性脑损伤(MTBIS或脑震荡) 弹药是伊拉克和阿富汗战争的“标志性伤员”。脑震荡后症状是 很常见，通常在退伍军人从部署回来后持续数年(S)；然而， 这些症状背后的神经病理生物学还知之甚少。我们已发表的和初步的研究 在与战场相关的冲击波mTBI小鼠模型中演示，在具有重复冲击波的活着的退伍军人中 MTBIs，以及在退伍军人和军人的死后脑组织中发现的 小脑尤其脆弱。小脑越来越多地牵涉到认知/行为 以持续性脑震荡后症状为特征的变化。我们的初步研究表明，这些 神经病理生物学改变延伸至去甲肾上腺素能蓝斑(LC)及其投射到 小脑齿状核(CDN)经小脑上脚(SCP)。去了解大自然和 MTBI损伤对LC-小脑齿状核网络的影响 提出了综合翻译的具体目标： 具体目标1.1.确定初始DTI扫描时LC和小脑的变化是否可预测 纵向损害：a)FDG-PET对小脑局部葡萄糖的摄取，b)工作记忆，c) 反复冲击波mTBI伊拉克/阿富汗退伍军人认知定势转移。 具体目标1.2.重复性颅脑损伤死后脑组织中的检测 退伍军人/军人成员和对照病例mTBI是否与LC-小脑纤维特定相关 损伤和/或丢失与LC-皮质和/或LC-海马区纤维损伤和/或丢失相比。 具体目的2.在我们的小鼠BLAST模型中，确定LC-小脑投射是否 尤其容易在重复冲击波mTBI后退化。投射小脑的LC神经元将 在表达绿色荧光的小鼠中用犬腺病毒(CAV)红色荧光报告进行标记 LC纤维中的蛋白质。单细胞RNA测序将测试双标记LC神经元是否投射到 重复性冲击伤后，小脑表现出一种特殊的神经退行性变和细胞应激表型。 具体目标3.1。在非BLAST小鼠中确定工作记忆和认知定势转移 缺陷是由非特异性SCP WM损伤或特定损伤的LC纤维投射到 小脑。双侧注射1%溶血磷脂可造成SCP-WM损伤。LC纤维损伤会 用CAV-Cre AAV-DO白喉毒素双侧病毒转导诱导。 具体目标3.2。在非BLAST小鼠中确定LC神经元是否丢失NA信号 小脑后部足以导致工作记忆和认知定势转移障碍，类似于 爆炸mTBI。将使用病毒转基因方法敲除LC神经元中TH的双侧表达 通过SCP。

Mild traumatic brain injuries (mTBIs or concussions) caused by blast overpressure from exploding ordnance are the “signature injuries” of the wars in Iraq and Afghanistan. Postconcussive symptoms are common and often persist for years after Veterans have returned from deployment(s); however, the neuropathobiology underlying these symptoms is poorly understood. Our published and preliminary studies demonstrate in a battlefield-relevant mouse model of blast mTBI, in living Veterans with repetitive blast mTBIs, and in postmortem brain tissue from Veterans and Servicemembers with blast mTBIs that the cerebellum is particularly vulnerable. The cerebellum is increasingly implicated in cognitive/behavioral changes characteristic of persistent postconcussive symptoms. Our preliminary studies suggest that these neuropathobiologic changes extend to the noradrenergic locus coeruleus (LC) and its projections to the cerebellar dentate nucleus (CDN) via the superior cerebellar peduncles (SCP). To understand the nature and implications of mTBI damage to the LC-cerebellar dentate nucleus network, the following conceptually integrated translational Specific Aims are proposed: Specific Aim 1.1. To determine whether LC and cerebellar changes on initial DTI scan predict longitudinal impairments in: a) cerebellar regional glucose uptake by FDG-PET, b) working memory, and c) cognitive set-shifting in Iraq/Afghanistan Veterans with repetitive blast mTBI. Specific Aim 1.2. To determine in postmortem brain tissue from repetitive mTBI Veteran/Servicemember and control cases whether mTBI is specifically associated with LC-cerebellar fiber injury and/or loss as compared to LC-cortical and/or LC-hippocampal fibers injury and/or loss. Specific Aim 2. To determine, in our mouse blast model, whether LC-cerebellar projections are specifically vulnerable to degeneration following repetitive blast mTBI. Cerebellum-projecting LC neurons will be labeled using a canine adenovirus (CAV) red fluorescent reporter in mice expressing green fluorescent protein in LC fibers. Single cell RNA sequencing will test whether dual-labeled LC neurons projecting to the cerebellum exhibit a specific neurodegenerative and cell stress phenotype following repetitive blast mTBI. Specific Aim 3.1. To determine in non-blast mice whether working memory and cognitive set shifting deficits are caused by nonspecific SCP WM injury or by specific injury to LC fibers projecting to the cerebellum. SCP WM injury will be induced by bilateral injection of 1% lysolecithin. LC fiber injury will be induced using bilateral viral transduction with CAV-Cre AAV-DO diphtheria toxin. Specific Aim 3.2. To determine in non-blast mice if loss of NA signaling by LC neurons projecting to the posterior cerebellum is sufficient to cause working memory and cognitive set shifting deficits similar to blast mTBI. A viral transgenic approach will be used to knock out TH expression bilaterally in LC neurons passing through the SCP.