Calcium imaging reveals a network of intrinsically light-sensitive inner-retinal neurons
Calcium imaging reveals a network of intrinsically light-sensitive inner-retinal neurons
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DOI：
10.1016/s0960-9822(03)00510-4
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发表时间：
2003-08-05
期刊：
影响因子：
9.2
通讯作者：
Hankins, MW
中科院分区：
文献类型：
--
作者：
Sekaran, S;Foster, RG;Hankins, MW
背景：缺乏视杆和视锥感光细胞(RD/RD CL)的小鼠仍然能够调节一系列对光的反应，包括昼夜节律光携带、瞳孔光反射和光抑制松果体褪黑素。这些数据与一种新型的视网膜内感光细胞的存在相一致。结果：我们通过Fura-2成像监测光刺激(470 Nm)对细胞内Ca~(2+)的影响，检测了RD/RD CL视网膜固有光敏感性的性质和程度。使用这种不依赖于药物或手术分离神经节细胞与视杆细胞和视锥感光细胞的方法，我们在神经节细胞层(GCL)中鉴定了一组光敏神经元。视网膜照射可导致2.7%的神经元细胞内钙离子增加。光诱导的Ca~(2+)通量取决于光刺激的强度和持续时间。这些光响应单位形成了一个广泛的网络，可以通过应用缝隙连接阻滞剂Carbenoxolone来解偶联。我们观察到了三种类型的光诱发的钙内流：持续的、瞬时的和重复的，这表明GCL光感受器的不同功能类别。结论：总体上，我们的数据揭示了在没有视杆和视锥输入的情况下，GCL内固有的光敏神经元与次级光驱动细胞群耦合的异质性合胞体。
Background: Mice lacking rod and cone photoreceptors (rd/rd cl) are still able to regulate a range of responses to light, including circadian photoentrainment, the pupillary light reflex, and suppression of pineal melatonin by light. These data are consistent with the presence of a novel inner-retinal photoreceptor mediating non-image-forming irradiance detection.Results: We have examined the nature and extent of intrinsic light sensitivity in rd/rd cl retinae by monitoring the effect of light stimulation (470 nm) on intracellular Ca2+ via FURA-2 imaging. Using this approach, which does not rely on pharmacological or surgical isolation of ganglion cells from the rod and cone photoreceptors, we identified a population of light-sensitive neurons in the ganglion cell layer (GCL). Retinal illumination induced an increase of intracellular Ca2+ in similar to2.7% of the neurons. The light-evoked Ca2+ fluxes were dependent on the intensity and duration of the light stimulus. The light-responsive units formed an extensive network that could be uncoupled by application of the gap junction blocker carbenoxolone. Three types of light-evoked Ca2+ influx were observed: sustained, transient, and repetitive, which are suggestive of distinct functional classes of GCL photoreceptors.Conclusions: Collectively, our data reveal a heterogeneous syncytium of intrinsically photosensitive neurons in the GCL coupled to a secondary population of light-driven cells, in the absence of rod and cone inputs.