Melanopsin-dependent light avoidance in neonatal mice
Melanopsin-dependent light avoidance in neonatal mice
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DOI：
10.1073/pnas.1008533107
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发表时间：
2010-10-05
影响因子：
11.1
通讯作者：
Copenhagen, David R.
中科院分区：
文献类型：
--
作者：
Johnson, Juliette;Wu, Vincent;Copenhagen, David R.
表达黑视素的本质光敏视网膜神经节细胞 (ipRGC) 形成独立于视杆细胞和视锥细胞的光敏感系统。 ipRGC 的直接光刺激可以调节许多非成像视觉功能，例如昼夜节律和瞳孔反应的光诱导，并且可以加剧成人的偏头痛。在小鼠中，ipRGC 早在出生之日就具有光反应性。相比之下，它们的眼睑直到出生后 12-13 天（P12-13）才打开，并且杆状细胞和视锥细胞发出的光信号直到大约 P10 才开始。在视杆细胞和视锥细胞信号传导出现之前，新生儿中 ipRGC 的生理或行为功能尚未确定。在这里，我们报告说，小到 P6 的幼鼠就会完全避开灯光。光诱导的 ipRGC 反应可以很容易地在小于 P9 的幼鼠的视网膜中记录下来，并且我们没有发现视杆细胞和视锥细胞介导的视觉信号传导到这些年轻小鼠的 RGC 的证据。这些结果证实，负趋光性在视杆细胞和视锥细胞介导的视觉信号发生之前以及在图像形成视觉发生之前就很明显。缺乏黑视蛋白的小鼠不存在负趋光性。我们得出结论，黑视蛋白 ipRGC 的光激活对于负趋光性是必要且充分的。这些结果强烈表明 ipRGC 的光激活可能调节早产儿和新生儿的生理功能，例如睡眠/觉醒周期。
Melanopsin-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs) form a light-sensitive system separate from rods and cones. Direct light stimulation of ipRGCs can regulate many nonimage-forming visual functions such as photoentrainment of circadian rhythms and pupil responses, and can intensify migraine headache in adults. In mice, ipRGCs are light responsive as early as the day of birth. In contrast, their eyelids do not open until 12-13 d after birth (P12-13), and light signaling from rods and cones does not begin until approximately P10. No physiological or behavioral function is established for ipRGCs in neonates before the onset of rod and cone signaling. Here we report that mouse pups as young as P6 will completely turn away from a light. Light-induced responses of ipRGCs could be readily recorded in retinas of pups younger than P9, and we found no evidence for rod-and cone-mediated visual signaling to the RGCs of these younger mice. These results confirm that negative phototaxis is evident before the onset of rod-and cone-mediated visual signaling, and well before the onset of image-forming vision. Negative phototaxis was absent in mice lacking melanopsin. We conclude that light activation of melanopsin ipRGCs is necessary and sufficient for negative phototaxis. These results strongly suggest that light activation of ipRGCs may regulate physiological functions such as sleep/wake cycles in preterm and neonatal infants.