Synaptic transmission from photoreceptors to all types of ON bipolar cells is primarily mediated by the mGluR6 receptor. This receptor, which is apparently expressed uniquely in the nervous system by ON bipolar cells, couples negatively to a nonselective cation channel. This arrangement results in a sign reversal at photoreceptor/ON bipolar cell synapse, which is necessary in order to establish parallel ON and OFF pathways in the retina. The synapse is an important target for second messenger molecules that are known to modulate synaptic transmission elsewhere in the nervous system, second messengers that act on a time scale ranging from milliseconds to minutes. This review focuses on two of these molecules, Ca2+ and cGMP, summarizing our current knowledge of how they modulate gain at the photoreceptor/ON bipolar cell synapse, as well as their proposed sites of action within the mGluR6 cascade. The implications of plasticity at this synapse for retinal function will also be examined.

中文翻译：

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ON双极细胞活性的调节。

从光感受器到所有类型的双极细胞的突触传递主要由 mGluR6 受体介导。这种受体显然在神经系统中由 ON 双极细胞独特表达，与非选择性阳离子通道负耦合。这种排列导致光感受器/ON 双极细胞突触的符号反转，这是在视网膜中建立平行的 ON 和 OFF 通路所必需的。突触是第二信使分子的重要靶标，已知第二信使分子可调节神经系统其他部位的突触传递，第二信使的作用时间范围从几毫秒到几分钟不等。本综述重点关注其中两种分子 Ca2+ 和 cGMP，总结了我们目前对它们如何调节光感受器/ON 双极细胞突触增益的知识，以及他们提议的在 mGluR6 级联中的作用位点。还将检查该突触的可塑性对视网膜功能的影响。