Immune basis for hippocampal cholinerginc deficits in pyridostigmine-treated rats

描述(由申请人提供)： 从海湾战争(GW)归来后，退伍军人表现出一系列症状--被指定为海湾战争疾病(GWI)--不能与单一疾病联系在一起。GW退伍军人还表现出更高的心理症状和精神障碍发生率，以及下丘脑-垂体-肾上腺(HPA)轴功能和神经解剖学变化。这些症状的确切原因尚不清楚。用乙酰胆碱酯酶(AChE)抑制剂溴化吡斯的明(PB)预防GW期间神经毒剂的毒害作用。结合士兵所经历的操作压力，这种PB暴露被认为是GWI晚期认知功能障碍的原因之一。其他研究确定，PB是GW退伍军人免疫细胞功能受损的原因之一，这可能是GWI观察到的记忆缺陷的原因之一。由于迷走神经的胆碱能传入和传出控制着调节炎症的反射回路，我们建议调查这一假说，即应激和PB暴露的联合作用导致免疫功能改变，进而导致大脑关键区域胆碱能反应的改变，从而导致认知障碍。使用一个结合重复心理应激和PB暴露的临床前模型，我们将检验我们的主要假设，即GWI中的神经认知缺陷与PB和重复应激对免疫功能的综合影响有关，后者改变了海马乙酰胆碱功能。这一假说将在以下目标中得到验证：“目标1将检验PB+重复应激的组合是否会导致HPA轴功能障碍，增加细胞因子水平，减少胆碱能投射到海马区的活动，并调节迷走神经延髓中心。”Aim 2将研究海马区突触重组、神经元和小胶质细胞树突结构以及神经元变性，这些分析将为RRS+PB大鼠观察到的认知缺陷提供功能解剖学基础。AIM 3将直接评估PB和应激暴露对海马乙酰胆碱释放的综合影响。在体内，微透析将用于检测在执行依赖于海马的任务期间和在暴露于急性应激源期间，海马乙酰胆碱水平的基础和行为诱导的变化。Aim 4将通过在早期和延迟时间点暴露于PB+/-重复应激后对血浆、脾和淋巴结以及从海马区分离的小胶质细胞进行的免疫学分析，更直接地评估应激和PB对免疫功能的影响。这些研究的成功完成将证明，PB+重复应激暴露的组合引起外周介导的促炎细胞因子/趋化因子的变化，这些变化是导致海马胆碱能活动缺陷的机械原因，从而为PB暴露和应激事件后的行为障碍提供了神经化学和解剖学基础。最重要的是，拟议研究的成功完成将确定可迅速用于退伍军人GWI治疗的治疗性干预的基因座。

DESCRIPTION (provided by applicant): Following return from the Gulf War (GW), Veterans have exhibited of a constellation of symptoms - designated Gulf War Illness (GWI) - that cannot be associated with a single disease. GW Veterans also show increased rates of developing psychological symptoms and psychiatric disorders, along with alterations in hypothalamic-pituitary-adrenal (HPA) axis function and neuroanatomical changes. The precise cause for these symptoms remains unknown. The acetylcholinesterase (AChE) inhibitor pyridostigmine bromide (PB) was used as prophylaxis against the deleterious effects of nerve agents during the GW. When combined with the operational stress experienced by soldiers, this PB exposure has been proposed as one of the causes of the late cognitive dysfunction in GWI. Other studies determined that PB is a causative factor in the development of impaired immune cell function in GW Veterans, which may contribute to the memory deficits observed in GWI. Since vagal cholinergic afferents and efferents control a reflex circuit that regulates inflammation, we propose to investigate the hypothesis that the combined effects of stress and PB exposure result in altered immune function, which then leads to modifications in cholinergic responses in key brain areas that lead to cognitive deficits. Using a preclinical model of combined repeated psychological stress and PB exposure, we will test our overarching hypothesis that the neurocognitive deficits in GWI are related to combined effects of PB and repeated stress on immune function that alters acetylcholine function in hippocampus. This hypothesis will be tested in the following Aims: "Aim 1 will examine whether the combination of PB + repeated stress induces HPA axis dysfunction, increases cytokine levels, reduces the activity of cholinergic projections to the hippocampus and modulates vagal medullary centers." "Aim 2 will examine hippocampal synaptic re-organization, neuronal and microglia dendritic architecture and neuronal degeneration, analyses which would provide a functional anatomical basis for cognitive deficits observed in RRS + PB rats." "Aim 3 will directly assess the combined effects of PB and stress exposure on acetylcholine release in the hippocampus. In vivo microdialysis will be used to examine basal and behaviorally-induced changes in hippocampal acetylcholine levels during the performance of a hippocampal-dependent task and during an exposure to an acute stressor." "Aim 4 will more directly assess how stress and PB affect immune function via immunological analyses performed in plasma, spleen, and lymph nodes, as well as microglia isolated from the hippocampus, after exposure to PB +/- repeated stress at early and delayed time points. Successful completion of these studies will demonstrate that the combination of PB + repeated stress exposure elicits peripherally-mediated changes in pro-inflammatory cytokines/chemokines that are mechanistically responsible for deficits in hippocampal cholinergic activity, thereby providing a neurochemical and anatomical basis for behavioral deficits following exposure to PB and stressful events. Most importantly, successful completion of the proposed studies will identify loci for therapeutic intervention that can be quickly implemented for the treatment of GWI in our Veterans.