Basic Research of Light-Evoked Changes in the Interphotoreceptor Matrix

(1)在绿光和蓝光适应的大鼠中观察到光诱发的光感受器基质(IPM)的变化，而在红光适应的动物中没有观察到这种变化。结果表明，杆状光感受器是光诱导视网膜色素上皮细胞发生变化的主要原因。(2)通过电子显微镜观察，暗适应大鼠视网膜色素上皮细胞的颗粒成分弥漫分布在外节周围，而光适应动物视网膜色素上皮的顶突上可见颗粒成分聚集。遗传性视网膜变性小鼠视网膜外节段中度或明显缩短时，IPM的光诱发改变消失。结果表明，正常外节的存在是IPM发生光反应所必需的。(4)用互补于α2，6-唾液酸基转移酶mRNA的反义RNA探针进行原位杂交组织化学研究，发现α2，6-唾液酸基转移酶在出生后第14天至16天期间在大鼠视网膜中的表达增加，此时IPM首次发生光诱导的改变。结果表明，糖链末端的唾液酸在产生IPM的光响应中起着重要作用。(5)测量了猴视网膜IPM的电阻。周边视网膜的电阻低于黄斑，提示视杆相关的IPM的电阻低于视锥相关的IPM。

(1) The light-evoked changes of the interphotoreceptor matrix (IPM) were observed in green- and blue-light-adapted rats, whereas they were not detected in red-light-adapted animals. The results indicate that rod photoreceptors are predominantly responsible for light-evoked changes in the IPM.(2) By electron microscopic examination, the granular components of the IPM were diffusely detected around outer segments in dark-adapted rats, whereas they were observed to be accumulated on the apical process of the retinal pigment epithelia in light-adapted animals. The light-evoked change of the IPM is proved to occur on electron microscopic level.(3) The light-evoked changes of the IPM were observed to be extinct when the outer segments became moderately or markedly shortened in mice with inherited retinal degeneration. The results indicate that the presence of normal outer segments is necessary for the light response of the IPM to occur.(4) By in situ hybridization histochemistry using antisense RNA probes complementary for alpha2,6-sialyltransferase mRNA, its expression in rat retinas was increased between post-natal day (P) 14 and P16, when the light-evoked change in the IPM first occurs. The results indicate that the presence of sialic acid on the termini of sugar chains plays an important role in generating the light responece of the IPM.(5) The electrical resistance of the IPM of the monkey retina was measured. The resistance of the peripheral retina was lower than that of the macula, suggesting that the electrical resistance of the rod associated IPM is lower than that of the cone associated IPM.