Weiler R, Schultz K, Pottek M, Tieding S, Janssen-Bienhold U
Neurobiology FB 7, University of Oldenburg, D-26111 Oldenburg, Germany.
Proc Natl Acad Sci U S A. 1998 Jun 9;95(12):7139-44. doi: 10.1073/pnas.95.12.7139.
Ambient light conditions affect the morphology of synaptic elements within the cone pedicle and modulate the spatial properties of the horizontal cell receptive field. We describe here that the effects of retinoic acid on these properties are similar to those of light adaptation. Intraorbital injection of retinoic acid into eyes of dark-adapted carp that subsequently were kept in complete darkness results in the formation of numerous spinules at the terminal dendrites of horizontal cells, a typical feature of light-adapted retinae. The formation of these spinules during light adaptation is impaired in the presence of citral, a competitive inhibitor of the dehydrogenase responsible for the generation of retinoic acid in vivo. Intracellularly recorded responses of horizontal cells from dark-adapted eyecup preparations superfused with retinoic acid reveal typical light-adapted spatial properties. Retinoic acid thus appears to act as a light-signaling modulator. Its activity appears not to be at the transcriptional level because its action was not blocked by actinomycin.
环境光条件会影响视锥细胞终足内突触元件的形态,并调节水平细胞感受野的空间特性。我们在此描述,视黄酸对这些特性的影响与光适应的影响相似。向暗适应的鲤鱼眼内眶内注射视黄酸,随后将其置于完全黑暗中,会导致水平细胞终末树突形成大量棘状小体,这是光适应视网膜的典型特征。在柠檬醛存在的情况下,光适应过程中这些棘状小体的形成会受到损害,柠檬醛是负责体内视黄酸生成的脱氢酶的竞争性抑制剂。用视黄酸灌注暗适应眼杯标本后,细胞内记录的水平细胞反应显示出典型的光适应空间特性。因此,视黄酸似乎起到光信号调节剂的作用。其活性似乎不在转录水平,因为其作用未被放线菌素阻断。