Berson David M
Department of Neuroscience, Brown University, P.O. Box G-L4, Providence, RI 02912, USA.
Pflugers Arch. 2007 Aug;454(5):849-55. doi: 10.1007/s00424-007-0242-2. Epub 2007 Mar 10.
A third class of photoreceptors has recently been identified in the mammalian retina. They are a rare cell type within the class of ganglion cells, which are the output cells of the retina. These intrinsically photosensitive retinal ganglion cells support a variety of physiological responses to daylight, including synchronization of circadian rhythms, modulation of melatonin release, and regulation of pupil size. The goal of this review is to summarize what is currently known concerning the cellular and biochemical basis of phototransduction in these cells. I summarize the overwhelming evidence that melanopsin serves as the photopigment in these cells and review the emerging evidence that the downstream signaling cascade, including the light-gated channel, might resemble those found in rhabdomeric invertebrate photoreceptors.
最近在哺乳动物视网膜中发现了第三类光感受器。它们是神经节细胞类中的一种稀有细胞类型，而神经节细胞是视网膜的输出细胞。这些内在光敏性视网膜神经节细胞支持对日光的多种生理反应，包括昼夜节律的同步、褪黑素释放的调节以及瞳孔大小的调节。本综述的目的是总结目前关于这些细胞中光转导的细胞和生化基础的已知信息。我总结了压倒性的证据，即黑视蛋白是这些细胞中的光色素，并回顾了新出现的证据，即包括光门控通道在内的下游信号级联可能类似于在无脊椎动物横纹肌光感受器中发现的信号级联。
