Narayan Daniel S, Chidlow Glyn, Wood John Pm, Casson Robert J
Ophthalmic Research Laboratories, Hanson Institute Centre for Neurological Diseases, Adelaide, South Austalia, Australia.
South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Austalia, Australia.
Clin Exp Ophthalmol. 2017 Sep;45(7):730-741. doi: 10.1111/ceo.12952. Epub 2017 May 17.
Photoreceptors are the first-order neurons of the visual pathway, converting light into electrical signals. Rods and cones are the two main types of photoreceptors in the mammalian retina. Rods are specialized for sensitivity at the expense of resolution and are responsible for vision in dimly lit conditions. Cones are responsible for high acuity central vision and colour vision. Many human retinal diseases are characterized by a progressive loss of photoreceptors. Photoreceptors consist of four primary regions: outer segments, inner segments, cell bodies and synaptic terminals. Photoreceptors consume large amounts of energy, and therefore, energy metabolism may be a critical juncture that links photoreceptor function and survival. Cones require more energy than rods, and cone degeneration is the main cause of clinically significant vision loss in retinal diseases. Photoreceptor segments are capable of utilizing various energy substrates, including glucose, to meet their large energy demands. The pathways by which photoreceptor segments meet their energy demands remain incompletely understood. Improvements in the understanding of glucose metabolism in photoreceptor segments may provide insight into the reasons why photoreceptors degenerate due to energy failure. This may, in turn, assist in developing bio-energetic therapies aimed at protecting photoreceptors.
光感受器是视觉通路的一级神经元，可将光转化为电信号。视杆细胞和视锥细胞是哺乳动物视网膜中两种主要的光感受器类型。视杆细胞以牺牲分辨率为代价专门用于提高敏感度，负责在昏暗光线下的视觉。视锥细胞负责高敏锐度的中央视觉和色觉。许多人类视网膜疾病的特征是光感受器逐渐丧失。光感受器由四个主要区域组成：外段、内段、细胞体和突触终末。光感受器消耗大量能量，因此，能量代谢可能是连接光感受器功能与存活的关键节点。视锥细胞比视杆细胞需要更多能量，视锥细胞变性是视网膜疾病中导致临床上显著视力丧失的主要原因。光感受器节段能够利用包括葡萄糖在内的各种能量底物来满足其巨大的能量需求。光感受器节段满足其能量需求的途径仍未完全了解。对视锥细胞节段葡萄糖代谢认识的提高可能有助于深入了解光感受器因能量衰竭而变性的原因。这反过来可能有助于开发旨在保护光感受器的生物能量疗法。
