差异圆锥通路对固有光敏感视网膜神经节细胞亚型的影响。

Differential cone pathway influence on intrinsically photosensitive retinal ganglion cell subtypes.

机构信息

Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, USA.

出版信息

J Neurosci. 2010 Dec 1;30(48):16262-71. doi: 10.1523/JNEUROSCI.3656-10.2010.

Abstract

A small subset of ganglion cells in the mammalian retina express the photopigment melanopsin and are intrinsically photosensitive (ipRGCs). These cells are the primary conduits through which photic information is relayed to non-image-forming visual centers that mediate behaviors such as the pupillary light reflex and circadian entrainment. M1 and M2 cells comprise distinct morphological subpopulations of ipRGC, and possess physiological diversity in their intrinsic membrane properties and intrinsic light responses. Additionally, evidence now indicates that all ipRGCs receive photic information from rods/cones via synaptic signaling. It has recently been reported that Off-stratifying M1 cells paradoxically receive input from the On pathway within the Off sublamina of the inner plexiform layer. The purpose of the current study was to examine the functional consequences of cone pathway signaling to M1 and M2 cells. Using pharmacological tools and single-cell recordings of synaptic responses in wild-type and melanopsin-null mice, we found that the On pathway forms the primary excitatory synaptic input to both M1 and M2 cells. This input was much more influential in shaping the light-evoked responses and resting membrane properties of M2 cells than M1 cells. These findings indicate a surprising differential reliance upon cone-mediated phototransduction by ipRGC subpopulations. These findings also suggest that ipRGC subtypes signal diverse photic information to various non-image-forming visual centers.

摘要

哺乳动物视网膜中的一小部分神经节细胞表达光色素 melanopsin,并且具有内在光敏性(ipRGCs)。这些细胞是将光信息传递到介导瞳孔光反射和昼夜节律同步等非成像视觉中心的主要途径。M1 和 M2 细胞是 ipRGC 的不同形态亚群,其内在膜特性和内在光反应具有生理多样性。此外,现在有证据表明,所有 ipRGC 都通过突触信号从视杆/视锥细胞接收光信息。最近有报道称,反分层 M1 细胞在内部丛状层的 Off 亚层内从 On 途径中出乎意料地接收输入。本研究的目的是研究视锥途径信号对 M1 和 M2 细胞的功能后果。使用药理学工具和野生型和 melanopsin 缺失小鼠的单细胞记录来检测突触反应,我们发现 On 途径形成了对 M1 和 M2 细胞的主要兴奋性突触输入。这种输入对 M2 细胞的光诱发反应和静息膜特性的塑造比 M1 细胞更为重要。这些发现表明 ipRGC 亚群对光感受器介导的光转导具有惊人的差异依赖性。这些发现还表明,ipRGC 亚型向各种非成像视觉中心传递不同的光信息。

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