Physiology of intrinsically photosensitive retinal ganglion cells

描述（由申请人提供）：视网膜介导对光的各种潜意识光适应性反应，包括瞳孔收缩、警觉性的急性增强、调节大脑的激素分泌以及使生物钟与亮/暗周期同步。这些反应的诱导不足或时机不当，例如发生在轮班工人或盲人身上，可能导致“时差”症状，冬季抑郁症，睡眠障碍，头痛，甚至乳腺癌和前列腺癌。潜意识视觉系统的视网膜输入由内在光敏视网膜神经节细胞（ipRGC）介导，其产生内在的基于黑视素的光响应以及外在的视杆/视锥驱动的光响应。这些神经元是最近发现的，关于它们如何对不同种类的光做出反应，以及它们如何与视网膜中的其他细胞相互作用，还有很多东西有待了解。该应用程序的长期目标是填补这两个知识空白，并利用这些知识来帮助开发促进健康和生产力的照明技术，冬季抑郁症的光疗法，更好的眼部疾病诊断测试以及改善视力受损状况的医疗创新。该计划包括三个具体目标。在目标1中， 将从使用双光子显微镜鉴定的ipRGC进行全细胞记录，并且将使用各种药理学工具来剖析这些神经节细胞的杆/锥驱动的对光响应的分子和细胞机制。在目标2中，将使用全细胞记录、免疫组织化学和共聚焦成像来鉴定从ipRGC接收输入的视网膜无长突细胞，表征它们的光诱发反应，并确定它们潜在的生理功能。目标3将使用多电极阵列记录、药理学操作和行为测定来确定视网膜色素上皮（RPE）在ipRGC的基于黑视素的光响应的产生中的作用。已知RPE对于经典光感受器的光敏性是至关重要的，但其对于神经节细胞光感受器的重要性尚未得到充分研究。

DESCRIPTION (provided by applicant): The retina mediates various subconscious, photoadaptive responses to light, including pupil constriction, acute enhancement of alertness, regulating hormone secretion from the brain, and synchronizing the body clock to the light/dark cycle. Inadequate or mistimed induction of these responses, such as occurs in shift workers or the blind, can lead to "jet lag" symptoms, winter depression, sleep disorders, headache, and even breast and prostate cancer. Retinal input to the subconscious visual system is mediated by the intrinsically photosensitive retinal ganglion cells (ipRGCs), which generate intrinsic, melanopsin-based light responses as well as extrinsic, rod/cone-driven photoresponses. These neurons were discovered recently and much remains to be learned about how they respond to different kinds of light, and how they interact with other cells in the retina. This application's long-term objective is to fill both of these knowledge gaps and use this knowledge to help develop lighting technologies that promote health and productivity, light therapies for winter depression, better diagnostic tests for eye disorders, and medical innovations that ameliorate conditions of the visually impaired. This grant proposal consists of three Specific Aims. In aim 1, whole-cell recordings will be made from ipRGCs identified using two-photon microscopy, and various pharmacological tools will be used to dissect the molecular and cellular mechanisms underlying these ganglion cells' rod/cone-driven responses to light. In aim 2, whole-cell recording, immunohistochemistry and confocal imaging will be used to identify retinal amacrine cells that receive input from ipRGCs, characterize their light-evoked responses, and determine their potential physiological functions. Aim 3 will use multielectrode-array recording, pharmacological manipulation and behavioral assays to determine the role of the retinal pigment epithelium (RPE) in the generation of ipRGCs' melanopsin-based light responses. The RPE is known to be crucial for the photosensitivity of the classical photoreceptors but their importance for ganglion-cell photoreceptors has not been fully investigated.