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独立研究者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。具体来说，提出的工作将解决两个特定的目标，使用小鼠视网膜的杆状双极通路作为实验模型。一：哺乳动物视网膜的杆状双极-无突细胞突触的传输是如何发展的？二：在色素性视网膜炎小鼠模型中，当被剥夺视觉输入时，无论是由于黑暗饲养还是由于杆状双极全突触的退化，杆状双极全突触的行为是不成熟突触，成熟突触，还是其他不同的东西？第二个问题的答案对视网膜病变的治疗具有重要意义，这些视网膜病变是由光感受器变性引起的，例如发生在视网膜色素变性中。在试图通过更换或再生光感受器来恢复视力之前，建立视网膜内突触的功能特性并确定这些突触是否能够传递视觉信号是很重要的。为实现这些特定目标而设计的实验将在小鼠视网膜的体外切片制备中进行。杆状双极细胞和所有无突细胞将被可视化，成对电压钳记录将从突触偶联的神经元。突触前杆双极的去极化将引起Ca^*进入其轴突末端，这种Ca^*流入将被记录为Ca电流。Ca^*内流会引起末端谷氨酸能囊泡的胞吐；记录在脑内的兴奋性突触后电流可以让我分析胞吐现象。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发生变化。由于人们正在努力再生光感受器来治疗或治愈视网膜病变，因此了解病变视网膜的神经回路在多大程度上能够处理视觉信息是至关重要的。这里提出的工作将检查一个具有良好特征的视网膜突触，以确定突触传递的正常发育过程，并了解光感受器变性后的突触传递与发育中的视网膜中的突触传递如何比较。

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.