Ishikawa Futoshi, Ohguro Hiroshi, Ohguro Ikuyo, Yamazaki Hitoshi, Mamiya Kazuhisa, Metoki Tomomi, Ito Tadashi, Yokoi Yumiko, Nakazawa Mitsuru
Department of Ophthalmology, Hirosaki University School of Medicine, Hirosaki, Japan.
Invest Ophthalmol Vis Sci. 2006 Dec;47(12):5204-11. doi: 10.1167/iovs.05-1149.
The effects of various light-induced stresses on the retina were examined in the retinal degenerative rat model.
Retinal morphology and electroretinograms (ERGs) were analyzed after application of light-induced stress of several intensities (650, 1300, 2500, or 5000 lux). For evaluation of rhodopsin (Rho) function, the kinetics of Rho regeneration and dephosphorylation were studied by spectrophotometric analysis and immunofluorescence labeling with antibodies specifically directed toward the phosphorylated residues (334)Ser and (338)Ser in the C terminus of Rho. Retinal cGMP concentration was determined by ELISA. Expression levels of neurotrophic factors (FGF2, brain-derived neurotrophic factor [BDNF], platelet-derived growth factor [PDGF], and ciliary neurotrophic factor [CNTF]) were evaluated quantitatively by RT-PCR.
Light intensity-dependent deterioration of ERG responses and thinning of the retinal outer nuclear layer were observed in wild-type and Royal College of Surgeons (RCS) rat retinas. Under dark adaptation after light-induced stress, the kinetics of Rho regeneration were not different between wild-type and RCS rat retinas. Rho dephosphorylation at (334)Ser and (338)Ser was extremely delayed in RCS rat retinas compared with wild-type without light-induced stress, but Rho dephosphorylation at those sites became slower in both RCS and wild-type rat retinas. In terms of expression of neurotrophic factors, almost no significant changes were observed between the animals after light-induced stress.
The present study indicates that light-induced stress causes intensity-dependent deterioration in retinal function and morphology in wild-type and RCS rat retinas. Disruption of the phototransduction cascade resulting from slower kinetics of Rho dephosphorylation appears to be involved in retinal degeneration.
在视网膜退行性变大鼠模型中研究各种光诱导应激对视网膜的影响。
在施加几种强度（650、1300、2500或5000勒克斯）的光诱导应激后，分析视网膜形态和视网膜电图（ERG）。为评估视紫红质（Rho）功能，通过分光光度分析以及用特异性针对Rho C末端磷酸化残基（334）Ser和（338）Ser的抗体进行免疫荧光标记，研究Rho再生和去磷酸化的动力学。通过酶联免疫吸附测定（ELISA）确定视网膜环磷酸鸟苷（cGMP）浓度。通过逆转录聚合酶链反应（RT-PCR）定量评估神经营养因子（成纤维细胞生长因子2 [FGF2]、脑源性神经营养因子[BDNF]、血小板衍生生长因子[PDGF]和睫状神经营养因子[CNTF]）的表达水平。
在野生型和皇家外科学院（RCS）大鼠视网膜中观察到ERG反应的光强度依赖性恶化以及视网膜外核层变薄。在光诱导应激后的暗适应状态下，野生型和RCS大鼠视网膜中Rho再生的动力学没有差异。与无光照应激的野生型相比，RCS大鼠视网膜中（334）Ser和（338）Ser位点的Rho去磷酸化极度延迟，但在RCS和野生型大鼠视网膜中这些位点的Rho去磷酸化都变慢。就神经营养因子的表达而言，光诱导应激后动物之间几乎未观察到显著变化。
本研究表明，光诱导应激在野生型和RCS大鼠视网膜中导致视网膜功能和形态的强度依赖性恶化。Rho去磷酸化动力学减慢导致的光转导级联破坏似乎与视网膜变性有关。
