Department of Neurohumoral Regulations, Institute of Physiology, Academy of Sciences of the Czech Republic v.v.i., Prague 14220, Czech Republic.
J Comp Neurol. 2010 Sep 1;518(17):3630-44. doi: 10.1002/cne.22421.
Mammalian retina contains a circadian clock that is composed of components similar to those of the master circadian clock within the suprachiasmatic nuclei of the hypothalamus. The aim of the present study was to elucidate whether, when, and where the transcripts of the clock genes Per1 and Per2 and the immediate early gene c-fos are spontaneously expressed and/or induced by light in the newborn rat retina. At postnatal day 1 (P1), P3, P5, and P10, Wistar rat pups were released into constant darkness, and a 30-minute light pulse was administered during the subjective day or during the first or second part of subjective night. Gene expression was determined 30 minutes, 1 hour, 2 hours, and 4 hours after the light pulse by in situ hybridization followed by emulsion autoradiography. Endogenous expression of Per1 was detected in the neuroblastic retina, and Per2 expression was detected in the inner part of the neuroblastic retina from birth. Light pulses induced c-fos expression in ganglion cells from P1. Until P5, the cells were localized in the dorsal part of the retina, but, at P10, they were already distributed across the entire retinal circumference. Light pulses also induced the expression of c-fos and Per1 in the retinal pigment epithelium until P3, but not afterward. Expression of the Per2 gene was not photoresponsive until P10. These data demonstrate that the rat retina is light-sensitive immediately after birth. During early postnatal development, the spatial distribution of spontaneous and light-induced gene expression within the retinal layers changes gradually.
哺乳动物视网膜中存在一个生物钟，它由类似于下丘脑视交叉上核主生物钟的成分组成。本研究的目的是阐明新生大鼠视网膜中时钟基因 Per1 和 Per2 的转录本以及即刻早期基因 c-fos 是否自发表达和/或受光诱导。在出生后第 1 天（P1）、第 3 天（P3）、第 5 天（P5）和第 10 天（P10），Wistar 幼鼠被释放到持续黑暗中，并在主观白天或主观夜晚的第一或第二部分给予 30 分钟的光脉冲。光脉冲后 30 分钟、1 小时、2 小时和 4 小时，通过原位杂交后进行乳胶放射自显影来确定基因表达。内源性 Per1 表达在神经母细胞视网膜中检测到，Per2 表达从出生起就在神经母细胞视网膜的内部检测到。光脉冲从 P1 开始诱导神经节细胞中 c-fos 的表达。直到 P5，细胞位于视网膜的背侧部分，但在 P10，它们已经分布在整个视网膜圆周上。光脉冲还诱导视网膜色素上皮中的 c-fos 和 Per1 表达，直到 P3，但之后没有。Per2 基因的表达直到 P10 才对光有反应。这些数据表明，大鼠视网膜在出生后立即对光敏感。在早期产后发育过程中，视网膜各层内自发和光诱导基因表达的空间分布逐渐发生变化。
