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目的:探讨弱激光(He-Ne激光)对大鼠视网膜的辐射损伤机制。方法:健康成年雄性W istar大鼠40只,随机分成正常对照组,激光辐射后6 h、12 h、1 d、3 d、7 d、14 d和28 d组。分别于各时间点,通过眼底镜、组织病理技术、末端脱氧核糖核酸转移酶介导的dUTP缺口末端标记(TUNEL)、免疫组织化学、图像分析和视网膜电图测定,分析视网膜结构和功能的变化。结果:激光辐射后视网膜出现弥漫性损伤,视乳头下方损伤明显,感光细胞有不同程度的病理改变。辐射后视网膜各层可见TUNEL阳性细胞,尤以内核层多见;辐射后14 d,凋亡细胞开始减少。辐射后各时间点都有NMDAR的表达;随时间推移,NMDAR的表达逐渐增强,至14 d时回落。视网膜电流图b波幅值降低说明视网膜功能下降。结论:单次持续He-Ne激光(平均功率密度:30 mW/cm2,照射时间:15 m in)辐射后,可导致视网膜的损伤,谷氨酸受体的高表达可能是致视网膜损伤的原因之一。
Objective: To investigate the mechanism of radiation damage of rat’s retina with weak laser (He-Ne laser). Methods: Forty adult Wistar rats were randomly divided into normal control group, 6 h, 12 h, 1 d, 3 d, 7 d, 14 d and 28 d after laser irradiation. At each time point, changes of retinal structure and function were analyzed by ophthalmoscope, histopathology, terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL), immunohistochemistry, image analysis and electroretinography . Results: After laser irradiation, the retina showed diffuse damage, obvious damage under the optic nerve and photoreceptor cells with different degrees of pathological changes. TUNEL positive cells were observed in all layers of the retina after radiation, especially in the inner nuclear layer. At 14 days after irradiation, apoptotic cells began to decrease. NMDAR expression was observed at each time point after irradiation; the expression of NMDAR gradually increased over time, and fell to the 14th day. Decreased retinal echocardiographic b-wave amplitude indicates decreased retinal function. CONCLUSIONS: Single continuous He-Ne laser (mean power density: 30 mW / cm2, irradiation time: 15 mins) can cause retinal damage and high expression of glutamate receptors may be the cause of retinal damage one.