Purines and the health of retinal ganglion cells

嘌呤与视网膜神经节细胞的健康

• 批准号: 7226619
• 负责人: CLAIRE H MITCHELL
• 金额: $ 34.63万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7226619
• 关键词: ATP Receptors; Address; Adenosine; Adenosine A3 Receptor; Affect; Blindness; Cell Death; Cell Survival; Cells; Cessation of life; Condition; Data; Detection; Development; Disease; Elevation; Enzymes; Equilibrium; Experimental Models; Figs - dietary; Glaucoma; Glutamates; Health; In Vitro; Label; Life; Link; Measurement; Measures; Messenger RNA; N-Methyl-D-Aspartate Receptors; N-Methylaspartate; Nervous system structure; Pathway interactions; Permeability; Physiologic Intraocular Pressure; Physiological; Purinergic P1 Receptors; Purines; Rattus; Research; Retina; Retinal; Retinal Ganglion Cells; Role; Signal Transduction; Testing; Thinking; base; ectoATPase; extracellular; ganglion cell; in vivo Model; insight; killings; laser capture microdissection; novel; novel strategies; pressure; prevent; purine; receptor; response; theories; tool

DESCRIPTION (provided by applicant): Glaucoma is a major cause of blindness in the world and is characterized by a loss of retinal ganglion cells. The disease is frequently associated with elevated intraocular pressure, but it is unclear how this elevation leads to the death of ganglion cells. The current proposal is based upon the novel hypothesis that elevated intraocular pressure triggers the release of ATP. This released ATP can activate P2X7 ATP receptors on retinal ganglion cells, leading to activation of NMDA receptors and excitotoxic cell death. Alternatively, the released ATP can be converted into adenosine by ecto-enzymes and stimulate the A3 receptor for adenosine and protect ganglion cells. Three approaches will be used to test this hypothesis. First, the neuroprotective capacity of rat A3 receptors will be investigated pharmacologically, as this represents the most straightforward opportunity for treatment. Receptor identity will be confirmed by amplifying mRNA message from fluorescently-labeled retinal ganglion cells isolated using Laser-Capture Microdissection. Secondly, the interaction between P2X7 and NMDA receptor channels will be explored by examining the ability of NMDA antagonists to prevent the cell death caused by P2X7 stimulation. The mechanism underlying this interaction will be examined by measuring the effect of P2X7 stimulation on glutamate efflux, and determining the permeability of the P2X7 channel itself to glutamate. Indirect pathways for interaction will also be explored, investigating whether P2X7 receptor stimulation depolarizes cells sufficiently to open NMDA channels or trigger a vesicular release of glutamate. Finally, the effect of increased pressure on ATP release will be tested using in vitro and in vivo models. The ability of elevated pressure to trigger ATP release from dissociated rat retinal cells will be confirmed, and the effect of changing the magnitude and duration of this pressure will be investigated. The hypothesis will be tested with a rat model of experimental glaucoma by correlating the magnitude and duration of intraocular pressure elevation with levels of ATP and regulating enzymes. Together this research will provide a new explanation for ganglion cell death in glaucoma and suggests several new approaches to prevent this death.

描述（由申请人提供）：青光眼是世界上失明的主要原因，其特征是视网膜神经节细胞的丧失。该疾病经常与眼内压力升高有关，但目前尚不清楚这种升高是如何导致神经节细胞死亡的。当前的建议是基于新的假设，即升高眼压升高会触发ATP的释放。该释放的ATP可以在视网膜神经节细胞上激活P2X7 ATP受体，从而导致NMDA受体的激活和兴奋性细胞死亡。或者，可以通过肾上腺酶将释放的ATP转化为腺苷，并刺激A3受体的腺苷并保护神经节细胞。将使用三种方法来检验这一假设。首先，将在药理学上研究大鼠A3受体的神经保护能力，因为这是治疗最直接的机会。通过使用激光捕获显微解剖分离的荧光标记的视网膜神经节细胞扩增mRNA消息，可以证实受体身份。其次，通过检查NMDA拮抗剂防止P2X7刺激引起的细胞死亡的能力，将探索P2X7与NMDA受体通道之间的相互作用。通过测量P2X7刺激对谷氨酸外排的影响，并确定P2X7通道本身对谷氨酸的渗透性，可以检查这种相互作用的基础机制。还将探索间接相互作用的间接途径，研究P2X7受体刺激是否使细胞充分去极化以打开NMDA通道或触发谷氨酸的囊泡释放。最后，将使用体外和体内模型测试压力增加对ATP释放的影响。将确认压力触发ATP从解离大鼠视网膜细胞释放的能力，并研究改变该压力的幅度和持续时间的效果。该假设将通过将眼内压升高的幅度和持续时间与ATP水平和调节酶相关联的实验青光眼大鼠模型。这项研究将共同​​为青光眼中的神经节细胞死亡提供新的解释，并提出了一些防止这种死亡的新方法。