CYP1B1基因敲除小鼠视网膜神经节细胞和视乳头结构的观察

Structural observation of retinal ganglion cells and optic papilla in CYP1B1-knockout mice

目的探讨CYP1B1基因敲除小鼠是否存在视网膜神经节细胞(RGCs)和视乳头结构的改变,以及这些改变与前房角发育之间是否存在关系。方法采用18只成年CYP1B1基因敲除小鼠作为实验对象,随机分成3组,每组6只,分别对视网膜、视乳头及前房角进行光学显微镜和透射电子显微镜观察,并用末端脱氧核苷酸转移酶介导的三磷酸脱氧尿苷缺口末端标记(TUNEL)法检测凋亡的视网膜神经细胞。以同龄C57BL/6J小鼠作对照研究。结果正常对照小鼠未发现视网膜、视乳头及前房角的异常改变。CYP1B1基因敲除小鼠中,光镜组观察发现2只眼视乳头形态结构的改变;电镜组观察发现2只眼RGCs呈现进行性的细胞浆和细胞核的浓缩;TUNEL染色组显示3只眼RGCs层和内核层出现TUNEL阳性细胞。上述7只眼均存在较严重的房角发育畸形。结论CYP1B1基因敲除小鼠部分存在RGCs的变性和视乳头结构的改变,这些改变与前房角发育畸形存在一定的相关性。

Objective The epidemiological survey suggested that primary congenital glaucoma is correlated with CYP1B1 mutation. Other researcher also found the malformed development of aqueous flowing canal in CYP1B1-knockout mice. The purpose of this study was to explore whether retinal ganglion cells damage and optic papilla changes occur in the CYP1B1- knockout mice and the relationship between these alterations to anterior chamber angle development by histopathology investigation. Methods Eighteen adult CYP1B1-knockout mice were averagely assigned to 3 groups. Eighteen C57BL/6J mice were randomly divided groups at a same way as control. The retinal morphology and structure of CYP1B1-knockout mice and C57BL/6J mice,the optic papilla and the anterior chamber angle morphologies were studied by light microscope and transmission electron microscope. The apoptosis of the retinal cells was assayed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling （TUNEL）. Results No obvious morphologic changes of retina, optic papilla and dysgenesis of anterior chamber angle were found under the light microscope and transmission electron microscope in C57BL/61 mice. However, in CYP1B1-knockout mice,expanding of optic disc, edema and disruption of nerve bundles were displayed in 2 eyes under light microscope,and progressive condensation and shrinkage of the retinal ganglion cells nuclei were exhibited in other 2 eyes under the electron microscope. The apoptosis cells in the ganglion cell layer and inner nuclear layer were obviously increased in 3 eyes by TUNEL staining. The anterior chamber angle dysgenesis could be found in above 7 eyes,exhibiting the blockage of trabecular meshwork and Schlemm＇ s canal. Conclusion A part of CYP1B1-knockout mice appear retinal ganglion cells damage and optic papilla changes,and these alterations are positive correlated with the anterior chamber angle dysgenesis.