金属汞对视觉系统危害的毒理学研究

发布时间：2018-07-22 13:22

【摘要】：许多研究表明,金属汞(Hg)是一种危害非常广泛的重金属毒物,是人类环境污染中最常见的公害之一。前期研究结果显示金属汞对视觉系统具有危害作用,且视网膜神经纤维及视细胞受到危害发生于汞中毒之前,因此,进一步研究金属汞对视觉系统危害的毒理学研究有重要意义。目的：制作汞中毒易感鼠动物模型,对比正常鼠和易感鼠视网膜电图(electroretinogram, ERG)中a、b波和视网膜显微结构的变化情况,初步探讨金属汞对视觉系统的危害和可能中毒机理。方法：将48只健康清洁级SD大鼠编号,随机分为3组：对照组；低浓度汞蒸气处理组0.01mg/m3；高浓度汞蒸气处理组3mg/m3。各组大鼠在染汞前及染汞1周、2周、3周和4周末,分别做左眼ERG检测1次,共5次。各实验组动物分别于染汞1周、2周、3周和4周末分批被处死,收集动物眼球,显微镜下取视网膜组织,同等条件下用透射式电子显微镜(Transmission Electron Microscope,TEM)摄片,对比观察各组视网膜神经节细胞及双极细胞超微结构的变化。结果：1.ERG检查：实验前,实验组与对照组间视网膜各波振幅及潜伏期对比无明显差异。低浓度染汞组1、2周末ERG的a波振幅及潜伏期无明显差异,b波振幅降低及潜伏期延长；染汞3、4周末ERG的a、b波均出现振幅降低及潜伏期延长变化,染汞4周末变化更明显,a、b波形低平。高浓度染汞组1周末ERG的a波振幅及潜伏期无明显差异,b波振幅降低及潜伏期延长；染汞2周末ERG的a、b波均出现振幅降低及潜伏期延长变化,变化明显。染汞3、4周末ERG的a、b波波型不易辨认,表现为无波型。2.视网膜超微结构观察：电镜下视网膜形态发生改变。结果表明：(1)随着染汞周期的延长,视网膜双极细胞、神经节细胞、Miiller细胞出现病理变化,表现为：线粒体、内质网水肿,细胞核切迹水肿,细胞核溶解、消失,凋亡小体等。(2)两实验组与对照组比较,1周末、2周末、3周末和4周末视网膜超微结构变化水平均明显升高,且有显著性差异(P0.01)；在相同时间点,1周末、2周末、3周末和4周末实验组间比较均有显著性差异(P0.05)。结论：1.金属汞可导致视网膜双极细胞和神经节细胞胞体、胞突超微结构发生改变,以致对视觉系统造成危害；2.金属汞对视觉系统超微结构的损害程度与空气中汞蒸气浓度及暴露时间呈正相关关系；3.ERG检测结果与电镜观察发现的形态学改变结果是一致的。
[Abstract]:Many studies have shown that metal mercury (Hg) is one of the most common public hazards in human environmental pollution. Previous studies have shown that metallic mercury is harmful to the visual system and that retinal nerve fibers and visual cells are damaged before mercury poisoning, so, It is of great significance to further study the toxicological study on the harm of metallic mercury to the visual system. Objective: to make a rat model of mercury poisoning and compare the changes of AGB wave and retinal microstructure in electroretinogramgram (ERG) of normal and susceptible rats, and to explore the harm of metallic mercury to the visual system and the possible mechanism of poisoning. Methods: 48 healthy and clean SD rats were randomly divided into three groups: control group, low concentration mercury vapor treatment group (0.01 mg / m ~ 3) and high concentration mercury vapor treatment group (3 mg / m ~ (-3). The rats in each group were tested for ERG in left eye for 5 times before and after 1 week and 2 weeks and 4 weeks of exposure respectively. The animals in each experimental group were killed at 1 week, 2 weeks, 3 weeks and 4 weeks after exposure to mercury, respectively. The eyeballs were collected, the retinal tissues were taken under microscope, and transmission electron microscopy (TEM) was used to film the animals under the same conditions. The ultrastructural changes of retinal ganglion cells and bipolar cells were observed. Results 1. ERG: before the experiment, there was no significant difference in amplitude and latency between the experimental group and the control group. There was no significant difference in a wave amplitude and latency of ERG at the end of 1 and 2 weeks in low concentration mercury exposed group, and the amplitude and latency of ERG were all decreased and latent period prolonged at the end of 3 ~ 4 weeks after mercury exposure, and there was no significant difference in the amplitude and latency of ERG at the end of the 1st and 2nd week. The change of mercury at the end of 4 weeks was more obvious. There was no significant difference in a wave amplitude and latency of ERG at the end of 1 week in the high concentration group, but the amplitude and latency of ERG were decreased and prolonged at the end of 2 weeks after mercury exposure. The wave patterns of ERG in ERG at the end of the 4th week were not easy to identify, showing no wave type. 2. Observation of retinal ultrastructure: morphological changes of retina were observed under electron microscope. The results showed that: (1) with the prolongation of mercury staining cycle, the pathological changes of retinal bipolar cells, ganglion cells and Miiller cells were as follows: mitochondria, endoplasmic reticulum edema, nuclear notch edema, nuclear dissolution and disappearance. (2) the changes of retinal ultrastructure in the experimental group were significantly higher than those in the control group at the end of the 1st week, the 3rd weekend and the 4th weekend (P0.01). At the same time, there were significant differences between the experimental groups on the 1st weekend, 2nd weekend, 3rd weekend and 4th weekend (P0.05). Conclusion 1. Metal mercury can cause retinal bipolar cells and ganglion cell bodies, process ultrastructure changes, causing harm to the visual system. The degree of damage of metallic mercury to the ultrastructure of the visual system was positively correlated with the concentration of mercury vapor in the air and the exposure time. 3. The results of ERG were consistent with the morphological changes observed by electron microscope.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R779.13

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