活体视神经示踪剂锰离子对视网膜毒性的研究

发布时间：2018-05-31 16:59

本文选题：锰离子 + 示踪剂　；参考：《宁夏医科大学》2010年硕士论文

【摘要】：视神经损伤是眼科临床中常见的一种外伤毁损性疾病,约占头部闭合性损伤的0.5%~5%,严重时可导致长期乃至永久性的视力障碍或失明。因此,视神经的损伤及其损伤后修复即成为长久以来人们关心的研究热点。以往,在视神经损伤和损伤后修复的研究中,应用的损伤神经定位技术均必须将动物处死,进行病理切片才能进一步观察损伤情况。如果可以找到一种无创性的观察活体视神经轴浆流及突触传递动态过程的技术,势必会对视神经损伤后修复的研究起到重要指导作用。近年来,基于二价锰离子(Mn~(2+))的特性,以Mn~(2+)作为神经示踪剂的磁共振成像技术,使得活体示踪视神经成为可能。应用该技术,Pautler、Koretsky和Thuen等多为学者在研究小鼠和大鼠的视觉通路时发现,将Mn~(2+)注入眼玻璃体腔,Mn~(2+)可被视网膜神经细胞摄取,轴浆上行运输等一系列过程,最终借助磁共振成像技术成功显影视神经。但是,研究多集中在较小动物身上,对较大动物视神经功能成像的研究尚很少,且随着玻璃体腔内注入Mn~(2+)的广泛应用,Mn~(2+)对视网膜的毒性作用亦渐渐引起了人们的关注[7]。究竟影像增强剂Mn~(2+)有多大毒性,能够造成何种程度的损伤人们还知之甚少。依据我们以往的实验研究结果,本实验在青紫兰兔眼玻璃体腔内注入不同浓度MnCl_2溶液,观察不同浓度不同时间点Mn~(2+)对视网膜形态学和功能学方面的毒性。并筛选出既能有效显影视神经又不会造成视功能损伤的锰离子玻璃体腔注入的安全剂量,为Mn~(2+)增强MRI示踪视神经的临床应用和视神经损伤的基础研究提供安全依据。目的1、研究不同浓度下活体视神经示踪剂Mn~(2+)对视网膜形态学和功能学上的影响。2、观察不同浓度下Mn~(2+)对眼视网膜组织的毒性损伤特征,从而筛选出安全且有效的视神经显影浓度,为临床应用及实验研究提供依据。方法60只青紫兰兔120眼随机分为5组,分别单眼玻璃体腔中注入MnCl_210、15、20、30、40mmol/L 25μl。于术前及术后7d、28d行眼底彩色照相、荧光眼底血管造影、闪光视网膜电图(flash electroretinography,F-ERG)检测,并摘除眼球行视网膜光学显微镜和电子显微镜检查,观察并评价不同浓度Mn~(2+)对视网膜形态学及功能学上的毒性损伤情况。结果1、15 mmol/L浓度组:F-ERG b波振幅均值分别为注药前(337μV)、注药后7d(189μV)、注药后28d(317μV),差异有统计学意义(F=20.43,P=0.02)。其中,注药后7d,F-ERG b波振幅与术前正常b波振幅相比有所降低(P0.01),28d b波振幅恢复正常(P0.05);2、≥20 mmol/L浓度组:注药后7d,F-ERG b波振幅与术前正常b波振幅相比有所降低(P0.01),至28d b波振幅未见恢复(P0.01);3、光镜及透射电镜观察,≥20 mmol/L浓度组注药后各时间点均有视网膜组织结构的异常改变。结论1、MnCl_2作为视神经活体示踪剂,在有效的显影浓度内,青紫兰兔眼玻璃体腔注入25μl后,浓度≤15 mmol/L仅引起视网膜功能学上可逆性改变,形态学并无明显损伤;2、当MnCl_2溶液注入剂量25μl,浓度≥20 mmol/L时,视网膜出现功能及形态学损害;3、随着MnCl_2溶液注入浓度升高,视网膜损伤程度与浓度呈正相关。提示MnCl_2作为视神经活体示踪剂,注入剂量25μl,浓度≤15mmol/L是青紫兰兔玻璃体腔注入的安全视神经显影剂量,这为今后的临床应用及相关实验室研究提供了一定参考价值。
[Abstract]:Optic nerve injury is a common traumatic and damaged disease in the clinical ophthalmology, which accounts for the 0.5%~5% of the closed head injury, which can lead to long-term or permanent visual impairment or blindness. Therefore, the injury of the optic nerve and the repair after injury have become a hot research focus for a long time.
In the past, in the study of optic nerve injury and post injury repair, the applied injured nerve location techniques must be executed to kill the animals and make pathological sections to further observe the damage. If we can find a noninvasive technique to observe the axial flow of the optic nerve and the dynamic process of synaptic transmission, it is bound to be after the optic nerve injury. The study of restoration plays an important role in guiding.
In recent years, based on the characteristics of two valence manganese ions (Mn~ (2+)), the magnetic resonance imaging technique of Mn~ (2+) as a neural tracer makes it possible to trace the optic nerve in vivo. With this technique, many scholars, such as Pautler, Koretsky and Thuen, have found that Mn~ (2+) is injected into the vitreous cavity of the eye, and Mn~ (2+) can be considered. A series of processes such as the ingestion of omental nerve cells and the transport of axial pulps and so on, with the help of magnetic resonance imaging (MRI). However, the study is mostly focused on the smaller animals. There are few studies on the optic nerve function imaging of larger animals, and the toxicity of Mn~ (2+) to the retina with the wide application of Mn~ (2+) into the cavity of the glass body The effect has gradually attracted people's attention. How much toxic is [7]. image enhancer Mn~ (2+), and little is known about the extent to which it can cause damage.
According to our previous experimental results, different concentrations of MnCl_2 solution were injected into the vitreous cavity of the blue and blue rabbit eyes to observe the toxicity of Mn~ (2+) to the morphological and functional aspects of the retina at different concentrations and different time points. The safe dose was provided for the safety of Mn~ (2+) - enhanced MRI tracing of optic nerve and basic research of optic nerve injury.
Objective 1 to study the morphological and functional effects of Mn~ (2+) on the retinal morphology and function at different concentrations,.2, and to observe the toxic damage characteristics of Mn~ (2+) to the retinal tissue at different concentrations, so as to screen out the safe and effective optic nerve development concentration, and provide the basis for clinical and experimental research.
Methods a total of 120 eyes of 60 blue and blue rabbits were randomly divided into 5 groups, which were injected with MnCl_210,15,20,30,40mmol/L 25 mu L. in the single eye of the single eye, respectively, before and after the operation, 7d, 28d, fundus color photography, fluorescein fundus angiography, and flash electroretinogram (flash electroretinography, F-ERG) examination, and the retina optical microscope and electron microscopy were used to remove the eyeball. Microendoscopic examination was performed to observe and evaluate the morphological and functional toxicity of Mn~ (2+) at different concentrations.
Results 1,15 mmol/L concentration group: the mean amplitude of F-ERG b wave was before injection (337 mu V), 7d (189 V) after injection, 28d (317 u V) after injection, and the difference was statistically significant (F=20.43, P=0.02). Group: the amplitude of 7D, F-ERG b wave after injection was lower than that of normal B wave before operation (P0.01), and the amplitude of 28d b wave was not recovered (P0.01); 3, optical and transmission electron microscopy were observed, and the abnormal changes of retinal tissue structure were observed at each time point after injection of more than 20 mmol/L concentration groups.
Conclusion 1, MnCl_2 is an active tracer in the optic nerve. Within the effective developing concentration, the concentration of 25 mu in the vitreous cavity of the blue rabbit eye is less than 15 mmol/L, which only causes the reversible change of the retinal function, and there is no obvious damage to the morphology. 2, when the dose of MnCl_2 solution is injected with a dose of 25 mu L and the concentration is more than 20 mmol/L, the retina appears function and morphology. 3, 3, the degree of retinal damage was positively correlated with the increase of concentration of MnCl_2 solution, suggesting that MnCl_2 is a active tracer of optic nerve, and the dose is 25 mu L, and the concentration is less than 15mmol/L, which is a safe optic nerve developing dose injected into the glass cavity of blue blue rabbit. This provides a certain clinical application and related laboratory research. Reference value.
【学位授予单位】：宁夏医科大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：R774.1

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