Quantifying the effect of light activated outer and inner retinal inhibitory pathways on glutamate release from mixed bipolar cells.
Quantifying the effect of light activated outer and inner retinal inhibitory pathways on glutamate release from mixed bipolar cells.
复制标题
量化光激活的外部和内部视网膜抑制途径对混合双极细胞谷氨酸释放的影响。
DOI：
10.1002/syn.22028
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Vigh,Jozsef
中科院分区：
文献类型：
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作者：
Lipin,MikhailY;Vigh,Jozsef
抑制介导的水平和无长突细胞在外部和内部的视网膜，分别是视觉处理的基本组成部分。在这里，我们的目的是确定这些不同的抑制过程如何影响当视网膜被各种强度的全视野光刺激时，从ON双极细胞释放谷氨酸。在暗适应的金鱼视网膜切片中，直接从接受混合视杆细胞和视锥细胞输入（Mbs）的完整双极细胞的轴突终末记录光诱发膜电位变化（ΔVm）。分别用浴用印防己毒素（PTX）和NBQX阻断对Mb的内部和外部视网膜抑制。然后，将对照和经修饰的光反应作为命令电位注射到轴突切断的Mb终末中，以诱导电压门控Ca 2+内流（QCa）和随后的谷氨酸释放。通过膜电容（ΔCm）的增加定量刺激诱发的谷氨酸释放。在一定的光强下，去除视网膜内外抑制后Mb终末去极化程度的增加同样增加了ΔVm/QCaratio，而抑制并不改变QCa和ΔCm之间的总体关系。然而，相对于对照，在PTX和PTX + NBQX存在下记录的光反应在不同刺激强度下不均匀地增加Δ C：在昏暗的刺激强度下，主要是内部视网膜GABA能抑制控制Mbs的释放，而内部和外部视网膜抑制对明亮刺激的释放的影响相同。此外，我们的研究结果表明，QCa和谷氨酸释放之间的非线性关系可以影响视网膜内外抑制通路在不同光强度下介导Mb输出的功效。
Inhibition mediated by horizontal and amacrine cells in the outer and inner retina, respectively, are fundamental components of visual processing. Here, our purpose was to determine how these different inhibitory processes affect glutamate release from ON bipolar cells when the retina is stimulated with full‐field light of various intensities. Light‐evoked membrane potential changes (ΔVm) were recorded directly from axon terminals of intact bipolar cells receiving mixed rod and cone inputs (Mbs) in slices of dark‐adapted goldfish retina. Inner and outer retinal inhibition to Mbs was blocked with bath applied picrotoxin (PTX) and NBQX, respectively. Then, control and pharmacologically modified light responses were injected into axotomized Mb terminals as command potentials to induce voltage‐gated Ca2+influx (QCa) and consequent glutamate release. Stimulus‐evoked glutamate release was quantified by the increase in membrane capacitance (ΔCm). Increasing depolarization of Mb terminals upon removal of inner and outer retinal inhibition enhanced the ΔVm/QCaratio equally at a given light intensity and inhibition did not alter the overall relation betweenQCaand ΔCm. However, relative to control, light responses recorded in the presence of PTX and PTX + NBQX increased ΔCmunevenly across different stimulus intensities: at dim stimulus intensities predominantly the inner retinal GABAergic inhibition controlled release from Mbs, whereas the inner and outer retinal inhibition affected release equally in response to bright stimuli. Furthermore, our results suggest that non‐linear relationship betweenQCaand glutamate release can influence the efficacy of inner and outer retinal inhibitory pathways to mediate Mb output at different light intensities.