Unoki K, Ohba N, Arimura H, Muramatsu H, Muramatsu T
Department of Ophthalmology, Kagoshima University Faculty of Medicine, Japan.
Invest Ophthalmol Vis Sci. 1994 Nov;35(12):4063-8.
To evaluate the protective effects of midkine (MK), the product of a retinoic acid-responsive gene, on constant light-induced retinal degeneration in albino Sprague-Dawley rats.
Midkine, basic fibroblast growth factor (bFGF), MK plus heparin, or buffer controls were injected intravitreally 2 days before constant light exposure. After 7 days of continuous light exposure, the eyes were perfused with fixative, bisected along the vertical meridian, embedded in paraffin, and sectioned. The degree of retinal light damage was assessed for paraffin-embedded sections by cytologic analysis, by measuring the thickness of the outer nuclear layer (ONL), and by counting the number of macrophages.
After 1 week of constant light exposure, uninjected controls and those injected with phosphate-buffered saline (PBS) lost most of the photoreceptor inner and outer segments, and the thickness of the ONL was decreased. Eyes that were injected with MK or bFGF demonstrated a significant rescue in the photoreceptor layer with a two- to threefold increase in the ONL thickness. The number of macrophages in eyes injected with MK was significantly suppressed compared with controls. Those injected with bFGF had a 1.5-fold increase in number compared with controls.
Midkine has shown strong survival-promoting activity in constant light-induced retinal degeneration, and thus has a high degree of neurotrophic activity in vivo.
评估维甲酸反应基因产物中期因子（MK）对白化Sprague-Dawley大鼠持续光照诱导的视网膜变性的保护作用。
在持续光照前2天经玻璃体腔内注射中期因子、碱性成纤维细胞生长因子（bFGF）、中期因子加肝素或缓冲液对照。持续光照7天后，用固定剂灌注眼睛，沿垂直子午线将其切成两半，石蜡包埋并切片。通过细胞学分析、测量外核层（ONL）厚度和计数巨噬细胞数量，对石蜡包埋切片的视网膜光损伤程度进行评估。
持续光照1周后，未注射的对照大鼠以及注射磷酸盐缓冲盐水（PBS）的大鼠失去了大部分光感受器内节和外节，ONL厚度降低。注射中期因子或bFGF的大鼠视网膜光感受器层得到显著挽救，ONL厚度增加了两到三倍。与对照相比，注射中期因子的大鼠眼中巨噬细胞数量显著减少。注射bFGF的大鼠眼中巨噬细胞数量比对照增加了1.5倍。
中期因子在持续光照诱导的视网膜变性中显示出强大的促存活活性，因此在体内具有高度的神经营养活性。
