Pharmacology and Physiology of Retinal Ganglion Cells

视网膜神经节细胞的药理学和生理学

• 批准号: 8866404
• 负责人: ANDREW T ISHIDA
• 金额: $ 55.06万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-04-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8866404
• 关键词: Adult; Anesthetics; Animals; Area; Axon; Brain; Calcium; Calcium/calmodulin-dependent protein kinase; Cells; Clinical; Cyclic AMP; Data; Dopamine; Dopamine Agonists; Dopamine Antagonists; Dopamine Receptor; Electrodes; Electrophysiology (science); Event; Exposure to; Eye; Goals; Green Fluorescent Proteins; Health; Hour; Image; Light; Light Adaptations; Lighting; Measures; Mediating; Membrane Potentials; Methods; Nerve Fibers; Neuromodulator; Neurons; Optic Nerve; Outcome; Output; Pharmacology; Photophobia; Photoreceptors; Physiology; Presynaptic Terminals; Property; Protocols documentation; Publishing; Rattus; Receptor Activation; Recruitment Activity; Reporting; Research; Retina; Retinal; Retinal Ganglion Cells; Shapes; Signal Transduction; Slice; Stimulus; Suction; Testing; Time; Vision; Visual system structure; Work; age related; analog; base; calcium-dependent protein kinase; calmodulin-dependent protein kinase II; cell type; cranium; desensitization; design; digital; ganglion cell; inhibitor/antagonist; interest; kinase inhibitor; multi-electrode arrays; neuronal cell body; novel; novel strategies; postnatal; protein expression; receptive field; receptor; research study; response; retinal neuron; success; transmission process; visual stimulus

DESCRIPTION (provided by applicant): This application seeks to challenge the research paradigm that the spike output of the eye consists of invariant ("all-or-none") signals. The proposed experiments will test the hypothesis that, in addition to lowering the light sensitivity o photoreceptors, daylight modulates the shape and number of spikes in the adult mammalian optic nerve. The long-term objectives of this work are (i) to identify properties of optic nerve spikes that are altered by illumination which light-adapts photoreceptors, increases endogenous dopamine release, and activates a calcium/calmodulin-dependent protein kinase (CaMKII) in retinal ganglion cell (RGC) somata and axons, and (ii) to distinguish changes in spiking that result from dopamine receptor activation versus those that result from light-induced repetitive spiking. These goals will be pursued in three specific aims. Aim 1 tests whether light, dopamine, and repetitive spiking alter spike shape, duration, and threshold. Although dopamine and repetitive spiking alter spiking in RGCs via various signaling components, new preliminary data presented in this application show that illumination recruits one of these - CaMKII - in RGC axons. Therefore, Aim 2 tests whether dopamine and repetitive spiking activate CaMKII, and whether CaMKII inhibition blocks effects of illumination, dopamine, and repetitive spiking on spikes. Aim 3 will gauge the impact of dopamine receptor activation and repetitive spiking on the spike output of the eye by measuring the responses of RGCs to a RGC-specific dopamine receptor agonist, electrode-stimulated spiking, and light stimuli that identify various functional cell types. These experiments will utilize two novel approaches to identify effects of light adaptation on RGC spiking. First, multi-electrode arrays (MEAs) will be used to initiate spikes in RGCs, and elicited spikes will be recorded in the nerve fiber layer with MEA electrodes and in the optic nerve with suction electrodes. These spikes will be compared before and during light adaptation, and before and after electrode-induced repetitive spiking. Receptor antagonists and kinase inhibitors will be applied before or during these protocols to test involvement of dopamine receptor and CaMKII activation. Secondly, a structural analog of dopamine (SKF-83959) that activates receptors unique to RGCs will be applied to dark-adapted retinae to test whether dopamine mimics the effects of light adaptation on spikes. Effects of brief and long exposures to SKF-83959 and light will be compared, because dopamine is thought to be released for hours during normal daylight. The expected outcomes of this work will identify novel components of light adaptation in the retina, novel effects of dopamine and CaMKII activation on retinal electrophysiology, and a novel contribution of RGC axons to spikes sent by the eye to the brain. These results will fundamentally advance our understanding of how state- and activity-dependent modulation contributes to light adaptation, and of the signals and mechanisms that the retina uses to report changes in illumination to higher levels of the visual system.

描述（由申请人提供）：本申请旨在挑战眼睛的尖峰输出由不变（“全或单位”）信号组成的研究范例。提出的实验将检验以下假设：除了降低光感受器O光感受器外，日光还调节成年哺乳动物视神经的形状和尖峰数。 The long-term objectives of this work are (i) to identify properties of optic nerve spikes that are altered by illumination which light-adapts photoreceptors, increases endogenous dopamine release, and activates a calcium/calmodulin-dependent protein kinase (CaMKII) in retinal ganglion cell (RGC) somata and axons, and (ii) to distinguish changes in spiking that result from dopamine受体激活与由光引起的重复尖峰产生的受体激活。 这些目标将以三个特定的目标实现。 AIM 1测试光，多巴胺和重复的尖峰改变尖峰形状，持续时间和阈值。尽管多巴胺和重复的尖峰通过各种信号传导组件在RGC中改变了尖峰，但本应用程序中介绍的新初步数据表明，照明在RGC轴突中募集了其中一种-CAMKII-。因此，AIM 2测试多巴胺和重复的尖峰是否激活CAMKII，以及CAMKII抑制阻滞是否对尖峰的照明，多巴胺和重复尖峰的影响。 AIM 3将通过测量RGC对RGC特异性多巴胺受体激动剂的反应，电极刺激的尖峰以及鉴定各种功能细胞类型的光刺激，来衡量多巴胺受体激活和重复尖峰对眼睛尖峰输出的影响。 这些实验将利用两种新型方法来识别光适应对RGC尖峰的影响。首先，将使用多电极阵列（MEA）来启动RGC中的尖峰，并将引起的尖峰记录在带有MEA电极的神经纤维层中，并在带有吸气电极的视神经中记录。这些尖峰将在光适应之前和之后进行比较，并在电极诱导的重复峰值之前和之后进行比较。在这些方案之前或期间，将应用受体拮抗剂和激酶抑制剂，以测试多巴胺受体和CAMKII激活的参与。其次，激活RGC的受体的多巴胺（SKF-83959）的结构类似物将用于深色适应性视网膜，以测试多巴胺是否模仿光适应对峰的影响。将比较对SKF-83959和光的短暂曝光和长时间的影响，因为认为多巴胺在正常日光下被释放了几个小时。 这项工作的预期结果将确定视网膜中光适应性的新成分，多巴胺和CaMKII激活对视网膜电生理学的新作用，以及RGC轴突对眼睛发送给大脑的尖峰的新贡献。这些结果从根本上可以促进我们对国家和活动依赖性调制如何促进光适应的理解，以及视网膜用来报告照明对更高级别视觉系统的信号和机制的理解。