Development and Dynamics of Transmission at Mammalian Rod Bipolar Cell Synapses

描述（由申请人提供）：我的职业目标是在一所研究型大学作为一名独立的研究人员研究视网膜中的信息处理。这里提出的项目将为我提供实现这一目标所需的培训。具体而言，拟议的工作将解决两个具体的目标，使用小鼠视网膜的视杆双极通路作为实验模型。第一：视杆双极的传递是如何发生的？哺乳动物视网膜上所有的无长突细胞突触都是如何发育的？第二条：在视网膜色素变性的小鼠模型中，当由于黑暗饲养或视杆变性而导致视觉输入被剥夺时，视杆双极-全突触的行为是作为未成熟的突触，作为成熟的突触，还是作为不同的东西？第二个问题的答案对于治疗由感光细胞变性引起的视网膜病变，例如发生在色素性视网膜炎中的视网膜病变具有重要意义。重要的是要建立内部视网膜突触的功能特性，并确定这些突触是否能够传递视觉信号，然后再尝试通过光感受器的替代或再生来恢复视力。设计用于实现这些特定目的的实验将在鼠视网膜的体外切片制备中进行。视杆双极细胞和所有无长突细胞将被可视化，成对的电压钳记录将从突触耦合的神经元进行。突触前视杆双极的去极化将引起Ca^* 进入其轴突末端，这种Ca^* 内流将被记录为Ca电流。Ca^* 内流将引起末梢的突触能小泡的胞吐作用;在All无长突蛋白中记录的兴奋性突触后电流将允许我测定这种胞吐作用。与公共卫生的相关性：许多视网膜病变导致光感受器（视杆和视锥）死亡，这剥夺了视网膜神经元的正常输入并导致它们之间的突触连接的变化。由于人们正在做出巨大努力来再生光感受器以治疗或治愈视网膜病变，因此了解患病视网膜的神经回路能够处理视觉信息的程度至关重要。这里提出的工作将检查一个特征良好的视网膜突触，以确定突触传递的正常过程中的发展，并了解如何在感光细胞变性后的突触传递相比，在发展中的视网膜。

DESCRIPTION (provided by applicant): My career goal is to study information processing in the retina as an independent investigator at a research university. The project proposed here will provide me with the training necessary to accomplish this goal. Specifically, the proposed work will address two specific aims using the rod bipolar pathway of the mouse retina as an experimental model. One: how does transmission at the rod bipolar-All amacrine cell synapse of the mammalian retina develop? Two: when deprived of visual input, resulting either from dark- rearing or from rod degeneration in a mouse model of retinitis pigmentosa, does the rod bipolar-All synapse behave as an immature synapse, as a mature synapse, or as something different? The answer to this second question has significant implications for treatment of retinal pathologies arising from photoreceptor degeneration such as that occurring in retinitis pigmentosa. It is important to establish the functional properties of inner retinal synapses and to determine whether these synapses are capable of transferring visual signals before attempting to restore vision by replacement or regeneration of photoreceptors. Experiments designed to achieve these specific aims will be performed in an in vitro slice preparation of murine retina. Rod bipolar and All amacrine cells will be visualized and paired voltage-clamp recordings will be made from synaptically coupled neurons. Depolarization of the presynaptic rod bipolar will elicit Ca^* into its axon terminal, and this Ca^* influx will be recorded as a Ca current. Ca^* influx will evoke exocytosis of glutamatergic vesicles from the terminal; excitatory postsynaptic currents recorded in the All amacrine will allow me to assay this exocytosis. Relevance to public health: Many retinal pathologies cause photoreceptor (rod and cone) death, which deprives retinal neurons of their normal inputs and results in changes in the synaptic connections between them. Because tremendous efforts are being made to regenerate photoreceptors to treat or cure retinal pathologies, it is critical to understand the extent to which the neural circuitry of the diseased retina is capable of processing visual information. The work proposed here will examine a well-characterized retinal synapse to determine the normal course of the development of synaptic transmission and to understand how synaptic transmission following photoreceptor degeneration compares to that in the developing retina.