Optical studies of the cone photoreceptor synapse

锥体感光器突触的光学研究

• 批准号: 7385931
• 负责人: RICHARD H KRAMER
• 金额: $ 35.74万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7385931
• 关键词: Affect; Cells; Chromosome Pairing; Color; Cytoplasm; Dyes; Electron Microscopy; Electrons; Endocytosis; Exocytosis; FM1 43; Feedback; Fluorescent Dyes; Functional disorder; Glutamate Receptor; Glutamates; Goals; Image; Ionomycin; Lateral; Left; Life Cycle Stages; Light; Measures; Membrane Potentials; Microscopic; Microscopy; Monitor; Neuromodulator; Optics; Pathway interactions; Pattern; Photons; Physiologic pulse; Preparation; Pulse taking; Rate; Reaction; Recovery; Regulation; Retina; Retinal; Retinal Cone; Retinal Diseases; Signal Transduction; Slice; Synapses; Synaptic Vesicles; System; Testing; Vesicle; Vision; horizontal cell; imprint; insight; neurotransmitter release; postsynaptic; presynaptic; programs; research study; response; size; two-dimensional; uptake; visual information; voltage; voltage clamp

DESCRIPTION (provided by applicant): Cone photoreceptors tonically release glutamate in the dark. Light hyperpolarizes cones and causes a graded reduction in glutamate release. Understanding how cones regulate transmitter release is crucial for understanding how visual information is transmitted to bipolar and horizontal cells. Previous studies have indirectly inferred presynaptic release from cones by measuring postsynaptic responses from these cells. However, many fundamental questions remain because, until now, there has been no direct measure of cone transmitter release. Among the key questions are: 1) What is the spatio-temporal pathway taken by synaptic vesicles as they journey between endocytosis and exocytosis in the cone terminal? 2) What is the quantitative relationship between presynaptic voltage, Ca2+ concentration, and exocytosis? 3) What is the rate of release from cones in the light and dark? 4) How is release modulated by feedback synapses and modulatory transmitters in the outer retina? 5) What is the size and extent of the lateral-inhibition contrast signal on arrays of cone terminals in the retina? Our goal is to answer these questions by directly measuring presynaptic release from cones. We will use the activity-dependent uptake and release of fluorescent lipophilic dyes, including FM1-43, as indicators of endocytosis and exocytosis. Preliminary results show that uptake and release of the dyes into cone terminals are Ca2+ and depolarization-dependent. Electron microscopic studies show localization of "photoconverted" dye to synaptic vesicles. FM1-43 release occurs rapidly in the dark, is suppressed by light, and is affected by synaptic feedback from HCs. We have monitored FM 1-43 release from individually dissociated cones, groups of cones in retinal slices, and 2-dimensional arrays of cone terminals in intact retinal flat mounts. These preparations allow us to answer subcellular-to systems-level questions about the regulation of cone neurotransmitter release. These results will provide fundamental information about the mechanisms of normal vision and will provide insights about synaptic dysfunction that occur in retinal diseases.

描述（由申请人提供）：黑暗中锥形感受器在色调释放谷氨酸。光超极化锥体并导致谷氨酸释放的分级降低。了解锥体调节发射器释放的方式对于理解视觉信息如何传输到双极和水平细胞至关重要。先前的研究通过测量这些细胞的突触后反应从锥中间接推断出突触前释放。但是，仍然存在许多基本问题，因为到目前为止，还没有直接衡量锥形发射器释放的方法。关键问题包括：1）突触囊泡在锥末端的内吞和胞吐作用之间行驶时，突触囊泡采取了什么时空途径？ 2）突触前电压，Ca2+浓度和胞吐作用之间有什么定量关系？ 3）在黑暗和黑暗中，锥体的释放速率是多少？ 4）如何通过视网膜外反馈突触和调节发射器调制释放？ 5）在视网膜中圆锥端阵列阵列的横向抑制对比度信号的大小和程度是多少？我们的目标是通过直接测量锥体的突触前释放来回答这些问题。我们将使用活动依赖性摄取和荧光亲脂染料的释放，包括FM1-43，作为内吞作用和胞吐作用的指标。初步结果表明，将染料摄取和释放到锥末端是Ca2+和去极化依赖性的。电子显微镜研究表明，“光转向”染料定位于突触囊泡。 FM1-43释放迅速发生在黑暗中，被光抑制，并受到HCS突触反馈的影响。我们已经监视了FM 1-43从单独解离的锥，视网膜切片中的一组锥和二维视网膜平坦式圆锥末端释放的释放。这些准备工作使我们能够回答有关锥神经递质释放调控的系统到系统级别的问题。这些结果将提供有关正常视力机制的基本信息，并将提供有关视网膜疾病中发生的突触功能障碍的见解。