ACh neuroprotection against excitotoxicity in RGCs

描述(申请人提供)：兴奋性毒性是中枢神经系统过度释放兴奋性神经递质，通过凋亡机制破坏神经元的过程。在哺乳动物的视网膜中，过量的谷氨酸释放与视网膜神经节细胞(RGC)的死亡有关，并与多种视网膜疾病状态有关，包括青光眼、糖尿病视网膜病变和视网膜缺血。最近，本实验室的研究表明，乙酰胆碱(ACh)通过激活烟碱型乙酰胆碱受体(NAChRs)对谷氨酸诱导的成年猪视网膜神经节细胞的兴奋性毒性具有保护作用。然而，nAChRs参与神经保护的类型以及nAChRs激活与神经保护之间的联系机制尚不清楚。根据本实验室获得的初步结果，本提案中将检验的假设是，激活猪视网膜节细胞上的nAChRs启动了一个信号级联反应，以减少谷氨酸诱导的兴奋毒性引起的细胞死亡。针对这一假说，设计了三个特定的目标：1)鉴定和表征与ACh对谷氨酸诱导的兴奋毒性的神经保护作用相关的nAChR亚单位；2)检验需要通过nAChRs进行神经保护的假说；3)测试第二信使通路将nAChR激活与谷氨酸诱导的兴奋毒性的神经保护联系起来的假说。结合免疫细胞化学、药理学、电生理学和钙成像技术，本研究的结果将确定猪视网膜神经节细胞中负责ACh神经保护作用的nAChR亚基的类型，并指出ACh的神经保护作用涉及哪些第二信使级联。了解AChR在视网膜中的神经保护机制最终可以减少由于兴奋毒性而导致的细胞死亡，并可以治疗视网膜中的兴奋毒性相关疾病，如青光眼，以及中枢神经系统的兴奋毒性相关疾病，如阿尔茨海默病。在哺乳动物的视网膜中，过量的谷氨酸释放与视网膜神经节细胞的死亡有关，并与某些视网膜疾病状态有关，包括青光眼、糖尿病视网膜病变和视网膜缺血。这项研究建议识别和分析视网膜中的一种神经保护机制，该机制可以防止视网膜神经节细胞因兴奋毒性而死亡。了解神经保护对抗兴奋性毒性的机制对于未来任何导致视网膜和中枢神经系统其他区域兴奋性毒性治疗的治疗干预都是至关重要的。神经保护治疗最终可以改善世界上数百万人的生活质量。

DESCRIPTION (provided by applicant): Excitotoxicity is the process by which excess excitatory neurotransmitter release in the central nervous system destroys neurons through an apoptotic mechanism. In the mammalian retina, excess glutamate release has been shown to be involved in retinal ganglion cell (RGC) death and is associated with several retinal disease states, including glaucoma, diabetic retinopathy and retinal ischemia. Recently, studies from this lab have demonstrated that acetylcholine (ACh) protects against glutamate-induced excitotoxicity in isolated adult pig retinal ganglion cells through activation of nicotinic acetylcholine receptors (nAChRs). However, the types of nAChRs involved in neuroprotection and the mechanism linking activation of nAChRs to neuroprotection is unknown. Base on preliminary results obtained from this lab, the hypothesis that will be tested in this proposal is that activation of nAChRs on pig RGCs initiates a signaling cascade to reduce cell death caused by glutamate-induced excitotoxicity. Three specific aims have been designed to address this hypothesis: 1) To identify and characterize the nAChR subunits associated with ACh's neuroprotective effect against glutamate-induced excitotoxicity in isolated adult pig RGCs; 2) To test the hypothesis that calcium permeation through nAChRs is required for neuroprotection to occur and 3) To test the hypothesis that second messenger pathways link nAChR activation to neuroprotection of glutamate-induced excitotoxicity. Using a combination of immunocytochemical, pharmacological, electrophysiological and calcium imaging techniques, the results obtained from this study should identify the types of nAChR subunits responsible for ACh neuroprotection in pig retinal ganglion cells and will indicate which second messenger cascades are involved in ACh's neuroprotective effect. Understanding the mechanism of AChR neuroprotection in the retina can ultimately lead to reduced cell death due to excitotoxicity and treatment for excitotoxicity- linked diseases in the retina, such as glaucoma, as well as excitotoxic-linked diseases in the CNS, such as Alzheimer's disease. In the mammalian retina, excess glutamate release has been shown to be involved in retinal ganglion cell death and is associated with certain retinal disease states including glaucoma, diabetic retinopathy and retinal ischemia. This study proposes to identify and analyze a mechanism of neuroprotection in the retina that prevents retinal ganglion cells from dying due to excitotoxicity. Understanding the mechanism of neuroprotection against excitotoxicity is essential for any future therapeutic intervention leading to treatment of excitotoxicity in the retina and other regions of the CNS. Neuroprotection treatment can ultimately improve the quality of life for millions of people in the world.