【作者】 王保贞；

【导师】 陈悦；

【作者基本信息】 郑州大学 ， 眼科学， 2010， 硕士

【摘要】 随着科技的发展,近距离工作的要求在增多,全世界范围内近视的发病率也在逐年增高,近视已经严重影响着患者的学习、工作、生活,因而近视也成为了全球共同关注的问题。虽然近二百年来对近视的研究在不断进行,各项可能影响因素也在不断地被发现,但是其病因及发病机制仍没有确切的结论,因此对近视的研究依然是世界眼科学家研究的重要课题。自从1977年Wiesel首次用缝合恒河猴眼睑的方法成功诱导出形觉剥夺性近视(form deprivation myopia, FDM)以来,近视动物模型的建立方法也在不断发展完善。目前,基本确立了两种近视的动物实验模型,即形觉剥夺性近视(form deprivation myopia, FDM)和离焦性近视(defocus myopia)。形觉剥夺性近视是指用缝合眼睑或戴弥散镜片或半透明眼罩来严重破坏动物的形体视觉所引起的近视。离焦性近视是指强迫动物视近或给动物配戴负球镜片使物体聚焦于视网膜的后方,从而引起调节的发生,使眼轴延长,所造成的近视。这两种近视动物模型的建立使得人们对近视的发生、发展及转归有了更加深入的认识,也使眼科学家对近视有了更加深入的研究。目前的研究表明：形觉剥夺可导致视网膜上的多种神经递质与生长因子的水平发生改变,而在这些研究中发现：诱导近视发生的物质主要来自视网膜的神经上皮层。其大致产生过程如下：视网膜神经上皮产生的一级信使首先作用于视网膜色素上皮(retinal pigment epithelium,RPE)和脉络膜,使之产生下一级的生化物质也称为二级信使,二级信使再作用于巩膜,调控巩膜生长从而使巩膜重塑,引起眼轴的过度延长,从而形成近视。其他一些自分泌或旁分泌环路涉及的细胞因子、生长因子及其酪氨酸激酶受体可能也对RPE细胞的病理改变起着至关重要的作用。但是这些因素对近视的影响机制有待于进一步研究。褪黑素(melatonin, MLT)它进入蛙黑色素细胞后会使蛙全身的肤色变浅,因此被称为褪黑素,是松果体在生理条件下夜间分泌的一种甲氧吲哚,化学名为N-乙酰-5-甲氧色胺,是由5-羟色胺转化而来的,其分泌节律由交叉上核团来根据昼夜节律来控制。长期以来,人们认为褪黑素的生物作用主要是调节昼夜节律、中心温度、造血、糖代谢节律以及睡眠-觉醒生物节律相位转换,改善睡眠。但随着研究的深入,人们还发现褪黑素还具有(1)直接清除自由基；(2)增强抗氧化酶的活力及其基因表达；(3)抑制一氧化氮合酶(NOS)的活性；(4)具有强大的线粒体保护功能。近年来已有研究表明NO与视网膜的发育、视觉兴奋和视觉信息的传导有关,提示其可能参与近视的形成。在Jaworski等及Kumi等的研究中发现,早基因c-fos可通过AP-1位点调控多巴胺限速酶-酪氨酸羟化酶(tyrosine hydroxylase,TH)及金属蛋白酶组织抑制剂(tissue inhibitor of metalloproteinases,MMPs),也已被证明对近视的发生及发展具有重要作用,另外,c-fos具有的抗细胞凋亡等功能也可能对近视的发展具有一定影响,并且褪黑素通过对视交叉上核内c-fos基因的调节,来实现光周期信号的传递。本实验拟建立豚鼠FDM模型,观察褪黑素和iNOS、c-fos在豚鼠FDM视网膜中的表达及作用。材料与方法选用出生7天龄的健康花色豚鼠30只,用半透明眼罩遮盖豚鼠右眼,左眼为对照眼。实验前对豚鼠进行散瞳检影验光,排除先天性近视及其它眼疾,用形觉剥夺的方法建立近视眼动物模型。形觉剥夺8周后,分别检测双眼屈光度及眼轴长度。HE染色光学显微镜下观察视网膜巩膜病理变化,免疫组织化学染色法检测视网膜褪黑素受体、iNOS和c-fos的表达水平。应用Image-Pro Plus 6.0对蛋白表达进行图像分析,表达强度用平均光密度值表示。实验数据均用x±s表示,采用SPSS 13.0统计软件包进行方差齐性检验,双眼之间比较采用配对t检验,在此基础上进行单因素方差分析及相关性检验,以a=0.05作为检验水准。结果1.形觉剥夺前遮盖眼屈光度(3.85±0.80D)与对照眼屈光度(3.75±1.20D)无明显差异(P>0.05),形觉剥夺8周后遮盖眼屈光度(—7.25±2.60D),对照眼屈光度(2.85±0.96D)(P<0.05)；形觉剥夺前遮盖眼眼轴长度(6.78±0.18mm)与对照眼眼轴长度(6.86±0.22mm)无明显差异(P>0.05),形觉剥夺8周后,遮盖眼眼轴长度(8.54±0.20mm),对照眼眼轴长度(7.12±0.17mm),有显著差异(P<0.05)。2.免疫组化检测形觉剥夺前褪黑素的表达遮盖眼(0.3650±0.0518A)和对照眼(0.4142±0.0778A)无明显差异(P>0.05),iNOS的表达遮盖眼(0.3321±0.0476A)和对照眼(0.3431±0.0354A)无明显差异(P>0.05),c-fos的表达遮盖眼(0.3752±0.0560A)和对照眼(0.3756±0.0822A)无明显差异(P>0.05)；形觉剥夺8周后褪黑素的表达遮盖眼(0.3199±0.0279A)和对照眼(0.3960±0.0932A)有显著差异(P＜0.05),iNOS的表达遮盖眼(0.4005±0.0605A)和对照眼(0.3326±0.1071A)有显著差异(P<0.05),c-fos的表达遮盖眼(0.2083±0.0604A)和对照眼(0.3654±0.0733A)有显著差异(P<0.05),也就是遮盖眼较对照眼视网膜中褪黑素受体的表达减少,iNOS表达增多,c-fos表达减少。3.遮盖眼中褪黑素受体与iNOS的表达(r=—0.8132,P=0.026<0.05),呈负相关,而与c-fos的表达(r=0.7085,P=0.075>0.05)呈正相关。结论1.单眼半透明眼罩遮盖8周后明显形成近视,动物形觉剥夺模型成功建立。2.遮盖眼视网膜中褪黑素受体表达明显减少,提示褪黑素可能参与了近视的形成。3.遮盖眼视网膜中iNOS表达明显增多,提示iNOS可能参与了近视的形成。4.遮盖眼视网膜中c-fos表达明显减少,提示c-fos可能参与了近视的形成。5.遮盖眼视网膜中褪黑素和iNOS的表达呈明显的负相关,褪黑素和c-fos呈明显的正相关。可以推测在形觉剥夺性近视的形成过程中褪黑素影响了iNOS、c-fos的表达和活性,导致了近视的形成。更多还原

【Abstract】 With the technology development, the near work demands are increasing, worldwide incidence of myopia has also increased year by year, myopia serious impact on the patient’s study, work, life, so short-sighted global issues of common concern. Although for the last two hundred years of myopia in the ongoing study of the various factors that may affect the continuous discovery, but its etiology and pathogenesis is still no definite conclusion, so the study of myopia is an important scientific research of the world’s Ophthalmology experts.Since Wiesel built up form deprivation myopia (FDM) on rhesus monkey in 1977 for the first time, the method to establish animal models of myopia has also been developed. At present, basically two kinds of animal model of myopia were established:form deprivation myopia (form deprivation myopia, FDM), myopic defocus (defocus myopia). Form deprivation myopia refers to stitching the eyelids or wearing translucent goggles dispersion lenses or serious damage to the visual shape of animals, then myopia happened. Defocus myopia is forced animals to see close, or depending on wearing a negative lens so that objects focus on behind the retina, causing adjustment occurs, so that axial extension caused by myopia. Both animal models of myopia make the occurrence of myopia, development and prognosis have a better understanding, but also Ophthalmology experts have a more indepth study. Current research shows that:form-deprived retina can lead to a variety of neurotransmitter and growth factor levels change, and these studies found that induced myopia, the material mainly from the neurosensory retina. General generating process as follows:retinal neuroepithelial generated by a first messenger acting on the retinal pigment epithelium (retinal pigment epithelium, RPE) and choroid, thus producing lower levels of biochemical substances, also known as the secondary messenger, acting on the two messenger sclera, scleral growth control so that sclera remodeling, causing excessive axial extension of the formation of short-sighted. A number of other autocrine or paracrine loops involving cytokines, growth factor and its tyrosine kinase receptor may be pathological changes in RPE cells play a crucial role. The impact of the mechanism of these factors needs to be further studied.Melatonin (melatonin, MLT) will enter the frog after frog melanocytes lighter body color, so called melatonin. Under physiological conditions the pineal gland at night a methoxy indole secretion, chemical, called N-acetyl-5-methoxy tryptamine, is a 5-HT transformation comes from the cross on their secretion rhythm nuclei to be controlled under the circadian rhythm. For a long time, people think melatonin is mainly regulate the biological role of the circadian rhythm, center temperature, blood sugar metabolism, as well as rhythm sleep-wake circadian rhythm phase-change and improve sleep. However, with the in-depth study of melatonin, Melatonin is also found to have (1) direct free radical scavenging; (2) to enhance the vitality of antioxidant enzymes and gene expression; (3) inhibit the activity of nitric oxide synthase; (4) a powerful mitochondrial protection. In recent years, studies have shown that NO has been the development of retinal, visual excitement and visual information transduction, suggesting its possible participation in the formation of myopia. And, in Jaworski, etc, and Kumi study found that early gene c-fos via regulation of AP-1 sites of dopamine rate-limiting enzyme-tyrosine hydroxylase (tyrosine hydroxylase, TH) and tissue inhibitor of metallopro-teinase (tissue inhibitor of metalloproteinases, MMPs), have also been proved have an important role in the occurrence and development of myopia, in addition, c-fos with the anti-apoptotic features on the development of myopia, and melatonin by suprachiasmatic nucleus c-fos gene regulation, to achieve photoperiod signals.In this study, the proposed FDM model of guinea pig, to observe the expression and effects of melatonin and iNOS, c-fos in guinea pig retina FDM.Material and MethodsUse thirty seven-days-old healthy multicolor guinea pigs, covering their right eye with semi-transparent goggle, the left eyeas the control eye. Experiments carried out before the cycloplegic retinoscopy guinea pigs to exclude congenital myopia and other eye diseases, the methods of form deprivation myopia model used to establish. After form-deprived 8 weeks, to detect eye refraction and axial length. HE staining was observed under optical microscope, the sclera retina pathological changes detected by immunohistochemical staining of retinal melatonin receptor, iNOS and c-fos expression. Application of Image-Pro Plus 6.0 image to analysis of protein expression, expression intensity with the average optical density value expressed.Experimental data are available, said use of SPSS 13.0 statistical software package homogeneity of variance test, Paired-Samples T test were used to analyze the difference between the experimental and control groups. In this based on single-factor analysis of variance and correlation tests. Withα=0.05 as the test standard.Results1. Before covered, form-deprived eyes were (3.85±0.80D) and the control eyes were (3.75±1.20D), there is no significant difference (P>0.05), covered after 8 weeks form-deprived eyes were (-7.25±2.60D), the control eye refraction (2.85±0.96D) (P<0.05); before form deprivation the covered eye axial length (6.78±0.18mm) and the control eye axial length (6.86±0.22mm), there is no significant difference (P>0.05),8 weeks after form deprivation, covering eye axial length (8.54±0.20mm), control eye axial length (7.12±0.17mm), were significantly different (P <0.05). Before covering refraction, form-deprived eyes and control eyes’s axial length was no significant difference (P>0.05), form-deprived for 8 weeks, form-deprived eyes and control eyes’s axial length were significantly different (P<0.05).2. Immunohistochemistry Before covered the expression of form-deprived eyes melatonin (0.3650±0.0518A) and the control eyes (0.4142±0.0778A) were no significant difference (P>0.05), iNOS expression in the deprived eyes (0.3321± 0.0476A) and the control eyes (0.3431±0.0354A) were no significant difference (P >0.05), c-fos expression in the deprived eyes (0.3752±0.0560A) and the control eyes (0.3756±0.0822A) were no significant difference (P>0.05); form deprivation for 8 weeks cover the eye after the expression of melatonin (0.3199±0.0279A) and the control eyes (0.3960±0.0932A) were significantly different (P<0.05), the expression of iNOS in the deprived eyes (0.4005±0.0605A) and the control eyes (0.3326±0.1071 A) were significantly different (P<0.05), c-fos expression in the deprived eyes (0.2083±0.0604A) and the control eyes (0.3654±0.0733A) were significantly different (P<0.05), which is covered than in the control eye retina reduction in the expression of melatonin receptor, the expression of iNOS increased, the expression of c-fos decreased.3. Cover the eyes of the melatonin receptor and iNOS expression (r=-0.8132, P= 0.026<0.05), negative correlation with c-fos expression (r=0.7085, P=0.075>0.05) were positively correlated.Conclusion1. Covered with monocular translucent goggles after 8 weeks the myopia was formed, animal form deprivation myopia model has been successfully established.2. In the expression of monocular retinal melatonin receptors in covered significan-tly reduced, suggesting that melatonin may be involved in the formation of myopia.3. Covering group the expression of monocular retinal iNOS was significantly increased, suggesting that iNOS may be involved in the formation of myopia.4. Covering group the expression of monocular retinal c-fos was significantly reduced, suggesting that c-fos may be involved in the formation of short-sighted.5. Covering group of retinal melatonin and the expression of iNOS were significantly negative related to melatonin and c-fos showed significant positive correlation. Presumably in form deprivation myopia in the formation of melatonin affected the iNOS, c-fos expression and activity, leading to the formation of myopia.更多还原