Ribelayga Christophe, Cao Yu, Mangel Stuart C
Department of Neuroscience, The Ohio State University College of Medicine, Columbus, OH 43210, USA.
Neuron. 2008 Sep 11;59(5):790-801. doi: 10.1016/j.neuron.2008.07.017.
Although rod and cone photoreceptor cells in the vertebrate retina are anatomically connected or coupled by gap junctions, a type of electrical synapse, rod-cone electrical coupling is thought to be weak. Using tracer labeling and electrical recording in the goldfish retina and tracer labeling in the mouse retina, we show that the retinal circadian clock, and not the retinal response to the visual environment, controls the extent and strength of rod-cone coupling by activating dopamine D(2)-like receptors in the day, so that rod-cone coupling is weak during the day but remarkably robust at night. The results demonstrate that circadian control of rod-cone electrical coupling serves as a synaptic switch that allows cones to receive very dim light signals from rods at night, but not in the day. The increase in the strength and extent of rod-cone coupling at night may facilitate the detection of large dim objects.
尽管脊椎动物视网膜中的视杆和视锥光感受器细胞在解剖学上通过缝隙连接（一种电突触）相连或耦合，但视杆 - 视锥电耦合被认为是较弱的。通过在金鱼视网膜中使用示踪标记和电记录以及在小鼠视网膜中使用示踪标记，我们发现视网膜生物钟而非视网膜对视觉环境的反应，通过在白天激活多巴胺D（2）样受体来控制视杆 - 视锥耦合的程度和强度，使得视杆 - 视锥耦合在白天较弱而在夜间显著增强。结果表明，视杆 - 视锥电耦合的昼夜节律控制充当了一种突触开关，使视锥细胞在夜间能够接收来自视杆的非常微弱的光信号，而在白天则不能。夜间视杆 - 视锥耦合强度和程度的增加可能有助于检测大型暗物体。
