INTERCELLULAR COMMUNICATION IN RETINAL DEVELOPMENT

神经元连接的组织模式在生命早期是如何发展的， 这是神经系统发育中的一个基本问题。 视网膜中神经元之间的交流甚至发生在 光感受器对光有反应。这导致了协调的模式， 活动，可以指导发展精确的连接， 视网膜，以及视网膜和大脑中的视觉中心之间。没有 如此精确的神经连接视觉图像处理 达到成年人的成熟和复杂程度。这项建议 强调协调活动和细胞间通讯的作用 在雪貂出生后早期的视网膜上。 在第一个项目中，细胞内钙的变化在体外将是 用于监测激发的自发波如何导致 各种类型的神经元之间的活动的相关性， 新生雪貂视网膜的不同区域。特工的身份 细胞将通过将Fura-2成像与细胞内染料- 填充。将对解离细胞进行记录，以便 确定视网膜细胞的节律性爆发活动是否是一种 细胞的生理特性，而不是细胞的网络。的 神经递质释放和缝隙连接在介导 波的传播将使用药理学试剂进行评估， 干扰波，并在细胞内注射示踪剂， 缝隙连接，以确定是否共同活动的细胞是细胞间 耦合。 神经递质及其受体的早期出现， 视网膜表明这些分子在视网膜发育中的作用， 结构和功能。在第二个项目中，我们希望确定 无论是递质介导的神经元之间的局部通信， 新生儿视网膜，在某种程度上，这可能是指导突触 阵在急性新生儿视网膜切片中，无长突细胞和双极细胞 会受到刺激，细胞内的钙水平会受到刺激， 邻居将被光学地监视。细胞通过这种方式 通信（发射器与间隙连接）将使用 药理学试剂和细胞内神经生物素（一种示踪剂， 穿过缝隙连接）注射。在第三个项目中， 将研究新生雪貂心室区细胞的变化。在 特别是，毒蕈碱胆碱能受体在细胞内的作用， 和细胞间信号传导将被检查。的 将确定这些相互作用对细胞增殖的结果 通过检查体内眼内注射毒蕈碱受体 拮抗剂减少有丝分裂。 通过监测大量的 我们希望能更好地了解 这些相互作用可能会导致形成精确的连接， 视网膜，以及视网膜和其中心目标之间。此外，委员会认为， 这些实验将增强我们对人类 策略被用来确保神经元的正常发育， 中枢神经系统中的神经通路。

How organized patterns of neuronal connections develop early in life is a fundamental question in the development of the nervous system. Communication between neurons in the retina occurs even before the photoreceptors respond to light. This leads to patterns of coordinated activity which can guide the development of precise connections within the retina, and between the retina and visual centers in the brain. Without such precision in neural connectivity, visual image processing may never reach its adult level of maturity and sophistication. This proposal addresses the role of coordinated activity and intercellular communication in the retina of the early postnatal ferret. In the first project, changes in intracellular calcium in vitro will be used to monitor how spontaneous waves of excitation may lead to correlations in activity among neurons of various types, and across various regions of the neonatal ferret retina. The identity of the active cells will be obtained by combining Fura-2 imaging with intracellular dye- filling. Recordings from dissociated cells will be made in order to determine whether the rhythmic bursting activity of retinal cells is a physiological property of the cell, rather than the network of cells. The role of neurotransmitter release and gap junctions in mediating the propagation of the waves will be assessed using pharmacological agents to disrupt the waves, and intracellular injection of a tracer that crosses gap junctions, to determine whether coactive cells are intercellularly coupled. The early appearance of neurotransmitters and their receptors in the retina suggests a role for these molecules in the development of retinal structure and function. In the second project, we wish to determine whether transmitters mediate local communication between neurons of the neonatal retina, in a manner which could be instructive for synapse formation. In acute neonatal retinal slices, amacrine and bipolar cells will be stimulated, and the intracellular calcium levels of their neighbors will be monitored optically. The means by which the cells communicate (transmitters versus gap junctions) will be assessed using pharmacological agents and intracellular Neurobiotin (a tracer which crosses gap junctions) injections. In the third project, the interactions of cells in the ventricular zone of neonatal ferrets will be studied. In particular, the role of muscarinic cholinergic receptors in intracellular and intercellular signaling will be examined pharmacologically. The outcome of these interactions on cellular proliferation will be determined by examining whether in vivo intraocular injections of muscarinic receptor antagonists reduces mitosis. By monitoring the physiological interactions between large numbers of developing retinal neurons, we hope to gain a better understanding of how these interactions might lead to the formation of precise connections of the retina, and between the retina and its central targets. Furthermore, these experiments would enhance our understanding of what common strategies are employed to ensure the normal development of neuronal pathways in the central nervous system.