强蓝光照射诱发大鼠视网膜组织结构及功能变化的实验研究

Experimental study on the structural and functional changes of the retinal tissue induced by intense blue light irradiation in rats

摘要:

目的：观察不同时长强蓝光照射后大鼠视网膜组织结构及功能的变化。

方法：选取8周龄健康无特定病原体(SPF)级SD雄性大鼠48只，随机分为对照组(n=12)和3、6、12h实验组(n=12)，对照组大鼠接受自然光照，实验组大鼠每日分别接受465±5nm、1000±100lx蓝光照射3、6、12h，连续光照8wk。采用光学相干断层扫描(OCT)、眼底荧光素血管造影(FFA)及石蜡病理组织切片苏木素-伊红(HE)染色法观察并分析不同方位及不同分层视网膜厚度、组织结构和功能变化。

结果：OCT检查示，各组大鼠视盘上方、下方、鼻侧、颞侧视网膜厚度组间比较均有差异(P<0.05)，且除对照组和3h实验组上方视网膜厚度无差异(P>0.05)，其余各组间各方位视网膜厚度比较均有差异(P<0.05)； 各组大鼠平均视网膜总厚度、内界膜(ILM)-内核层(INL)厚度、外丛状层(OPL)-光感受器外节段(OS)厚度、视网膜色素上皮(RPE)层厚度比较均有差异(P<0.05)，其中各组大鼠平均视网膜总厚度、OPL-OS厚度两两比较均有差异(P<0.05)，对照组分别与3、12h实验组大鼠ILM-INL厚度比较均有差异(P<0.05)，12h实验组分别与对照组和3、6h实验组大鼠RPE层厚度比较均有差异(P<0.05)。FFA检查示，对照组和3h实验组大鼠眼底均无明显荧光渗漏，6、12h实验组大鼠视网膜出现明显荧光渗漏和透见荧光，脉络膜背景荧光增强。HE染色结果示，实验组大鼠视网膜视细胞层细胞萎缩、凋亡，视细胞数目减少，部分细胞核淡染，随光照时间延长，RPE层出现萎缩变薄，且对照组和实验组视网膜视细胞数目具有显著差异(P<0.05)。

结论：强蓝光照射可导致大鼠视网膜厚度变薄，且不同分层视网膜厚度变薄程度不同，也可导致视细胞层细胞数目减少甚至消失，RPE层局灶性萎缩，血管通透性改变，且随光照时间延长，视网膜组织结构及功能变化越明显。

Abstract:

AIM: To observe the structural and functional changes of retinal tissue in rats after different duration of intense blue light irradiation.

METHODS: A total of 48 healthy 8-week-old SD male rats were selected and randomly divided into the control group(n=12)and 3, 6 and 12h experimental groups(n=36). The rats in the control group received natural light, and the rats in the experimental groups received blue light with a wavelength of 465±5nm and the illumination of 1000±100lx for 3, 6, and 12h each day. Optical coherence tomography(OCT), fundus fluorescein angiography(FFA)and haematoxylin-eosin(HE)staining of paraffin pathological section were used to observe the changes of the retinal thickness, retinal tissue structure and the function in different directions and layers.

RESULTS: The OCT results showed that the retinal thickness in the superior, inferior, nasal, and temporal sides of rats in different groups was statistically significant(P<0.05), and there was no statistical significant difference between the control group and the 3h experimental group in the total retinal thickness(P>0.05), while the differences between any other two groups were statistically significant(P<0.05); The mean total retinal thickness, internal limiting membrane(ILM)-inner nuclear layer(INL)thickness, outer plexiform layer(OPL)-outer segment(OS)thickness and retinal pigment epithelium(RPE)of rats in each group were statistically significant(P<0.05), and the mean total retinal thickness and OPL-OS thickness were statistically significant between any two groups(P<0.05). The ILM-INL thickness of rats in the control group and 3 and 12h experimental groups was statistically significant(P<0.05), and the thickness of RPE layer in the 12h experimental group was statistically different from that of the 3 and 6h experimental groups(P<0.05). FFA results showed that there was no obvious fluorescence leakage in the fundus of rats in the control group and the 3h experimental group, while there was obvious fluorescence leakage and hyperfluorescence in the retina of the 6 and 12h experimental groups, and the background fluorescence of choroid was enhanced. HE staining showed the atrophy and apoptosis of cells in the optic cell layer, and some lightly stained nucleus. In addition, RPE layer showed atrophy and thinned with the increase of light time, and there was significant difference in the number of the optic cells between the control group and experimental group(P<0.05).

CONCLUSION: The intense blue light irradiation could cause thinning of the retina in rats, with varying degrees of thinning in different layers of the retina. It could also led to decrease and even disappearance of the number of cells in the visual cell layer, the focal atrophy of the RPE layer, and the change of vascular permeability. With the extension of the light time, the structural and functional changes in retinal tissue became more obvious.