Inputs Underlying the ON-OFF Light Responses of Type 2 Wide-Field Amacrine Cells in TH::GFP Mice
Inputs Underlying the ON-OFF Light Responses of Type 2 Wide-Field Amacrine Cells in TH::GFP Mice
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DOI：
10.1523/jneurosci.6235-10.2011
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发表时间：
2011-03-30
影响因子：
5.3
通讯作者：
Dedek, Karin
中科院分区：
文献类型：
--
作者：
Knop, Gabriel C.;Feigenspan, Andreas;Dedek, Karin
在哺乳动物的视网膜中，已经描述了两种类型的儿茶酚胺能无长突细胞。虽然多巴胺能1型细胞有很好的特征，但2型细胞的生理学到目前为止还不清楚。为了特异性地靶向2型细胞，我们使用了一种在酪氨酸羟化酶启动子控制下表达绿色荧光蛋白的转基因小鼠系。2型细胞是GABA能细胞，具有广泛的树突状树枝，位于内丛状层的中间。我们的数据表明，2型细胞包括两个具有相同生理特性的亚群：一个胞体位于内核层，另一个位于神经节细胞层。双极细胞标记物的免疫染色表明，2型细胞接受来自3Off的兴奋性输入，而5型接受双极细胞的兴奋性输入。膜片钳记录一致地显示，2型细胞是开关的无长突细胞。阻断兴奋性输入揭示了在暗视和中间视光条件下不同的视杆和视锥通路是活跃的。阻断抑制性输入导致2型细胞膜电位振荡，提示GABA能和甘氨酸能无长突细胞强烈影响2型细胞信号转导。在甘氨酸能无长突细胞中，我们发现VGluT3免疫反应阳性的无长突细胞可能是一个候选细胞。总体而言，2型细胞的光响应在广泛的光强度范围内都非常均匀。这些属性指向在暗视和中间视条件下保持的2型细胞的一般功能。
In the mammalian retina, two types of catecholaminergic amacrine cells have been described. Although dopaminergic type 1 cells are well characterized, the physiology of type 2 cells is, so far, unknown. To target type 2 cells specifically, we used a transgenic mouse line that expresses green fluorescent protein under the control of the tyrosine hydroxylase promoter. Type 2 cells are GABAergic and have an extensive dendritic arbor, which stratifies in the middle of the inner plexiform layer. Our data suggest that type 2 cells comprise two subpopulations with identical physiological properties: one has its somata located in the inner nuclear layer and the other in the ganglion cell layer. Immunostaining with bipolar cell markers suggested that type 2 cells receive excitatory inputs from type 3 OFF and type 5 ON bipolar cells. Consistently, patch-clamp recordings showed that type 2 cells are ON-OFF amacrine cells. Blocking excitatory inputs revealed that different rod and cone pathways are active under scotopic and mesopic light conditions. Blockade of inhibitory inputs led to membrane potential oscillations in type 2 cells, suggesting that GABAergic and glycinergic amacrine cells strongly influence type 2 cell signaling. Among the glycinergic amacrine cells, we identified the VGluT3-immunoreactive amacrine cell as a likely candidate. Collectively, light responses of type 2 cells were remarkably uniform over a wide range of light intensities. These properties point toward a general function of type 2 cells that is maintained under scotopic and mesopic conditions.