Blockade of pathological retinal ganglion cell hyperactivity improves optogenetically evoked light responses in rd1 mice.
Blockade of pathological retinal ganglion cell hyperactivity improves optogenetically evoked light responses in rd1 mice.
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DOI：
10.3389/fncel.2015.00330
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发表时间：
2015
影响因子：
5.3
通讯作者：
Sernagor E
中科院分区：
文献类型：
--
作者：
Barrett JM;Degenaar P;Sernagor E
视网膜色素变性（RP）是一种进行性视网膜营养不良，导致视力障碍和最终失明。视网膜假体是目前最好的RP视力恢复治疗方法，但只能恢复原始视力。使用假体装置实现的视觉质量差的一个可能的促成因素是在光感受器营养不良性疾病中发生的病理性视网膜神经节细胞（RGC）活动过度。最近，在RP的rd 10小鼠模型中，用甲氨酰胺酸（MFA）阻断间隙连接可减少RGC的过度活动，并改善RGC对闪光和电刺激的反应的信噪比（SNR）。我们试图将这些结果扩展到快速退化的rd 1模型中的时空模式光遗传学刺激，并比较一些已知破坏rd 1活动过度的药物的有效性。我们将rd 1小鼠与在RGCs中表达光敏阳离子通道channelrhodopsin 2（ChR 2）的转基因小鼠品系杂交，使它们能够直接使用高强度蓝光刺激。我们使用60通道ITO多电极阵列记录ChR 2介导的RGC反应，从整体，离体视网膜全视野和图案刺激之前和之后的应用MFA，18-β-大黄酸（18 BGA，另一种间隙连接阻断剂）或氟吡汀（流感，Kv 7钾通道开放剂）。所有三种药物都降低了RGC自发放电，但18 BGA和Flu也降低了RGC对光遗传学刺激的敏感性。然而，所有三种药物都改善了ChR 2介导的反应的SNR。MFA还使得从RGC群体响应中更容易辨别移动棒的运动方向。我们的研究结果支持这一假设，即视网膜退行性疾病中病理性RGC自发活动特征的减少可以改善视网膜假体中视觉反应的质量，并且它们为如何最好地实现光遗传学假体提供了见解。
Retinitis pigmentosa (RP) is a progressive retinal dystrophy that causes visual impairment and eventual blindness. Retinal prostheses are the best currently available vision-restoring treatment for RP, but only restore crude vision. One possible contributing factor to the poor quality of vision achieved with prosthetic devices is the pathological retinal ganglion cell (RGC) hyperactivity that occurs in photoreceptor dystrophic disorders. Gap junction blockade with meclofenamic acid (MFA) was recently shown to diminish RGC hyperactivity and improve the signal-to-noise ratio (SNR) of RGC responses to light flashes and electrical stimulation in the rd10 mouse model of RP. We sought to extend these results to spatiotemporally patterned optogenetic stimulation in the faster-degenerating rd1 model and compare the effectiveness of a number of drugs known to disrupt rd1 hyperactivity. We crossed rd1 mice with a transgenic mouse line expressing the light-sensitive cation channel channelrhodopsin2 (ChR2) in RGCs, allowing them to be stimulated directly using high-intensity blue light. We used 60-channel ITO multielectrode arrays to record ChR2-mediated RGC responses from wholemount, ex-vivo retinas to full-field and patterned stimuli before and after application of MFA, 18-β-glycyrrhetinic acid (18BGA, another gap junction blocker) or flupirtine (Flu, a Kv7 potassium channel opener). All three drugs decreased spontaneous RGC firing, but 18BGA and Flu also decreased the sensitivity of RGCs to optogenetic stimulation. Nevertheless, all three drugs improved the SNR of ChR2-mediated responses. MFA also made it easier to discern motion direction of a moving bar from RGC population responses. Our results support the hypothesis that reduction of pathological RGC spontaneous activity characteristic in retinal degenerative disorders may improve the quality of visual responses in retinal prostheses and they provide insights into how best to achieve this for optogenetic prostheses.