背景 面对视觉环境的不断变化,为获得稳定而有效的信息,动物的视觉系统均应根据需要进行必要的调整.色觉系统面临光谱环境的变化,也应该具有一定的可塑性.在长期单色光照射下,视锥细胞密度和视蛋白的表达是否出现相应的变化目前仍不明确.目的 研究长时间单色光照射后豚鼠视网膜视锥细胞密度和视蛋白及其mRNA表达的变化.方法 30只出生3 d的豚鼠按随机数字表法平均分为绿光照射组、紫光照射组和白色混合光照射组,分别暴露于530 nm的绿光、400 nm的紫光及白色混合光照射环境下饲养8周后,制作视网膜铺片,按照对不同波长敏感的光敏视锥细胞在视网膜的分布特点将视网膜分为背侧、腹侧和混合部,分别行免疫细胞化学单标和双标检测,在荧光显微镜下检测不同光敏视锥细胞的密度变化,应用荧光实时定量聚合酶链反应(real-time PCR)法观察不同波长光照射后豚鼠视蛋白mRNA的变化,Westernblot法对视蛋白的变化进行定量检测.结果 视网膜背侧单标免疫细胞化学检测显示,3组绿敏视锥细胞密度的差异有统计学意义(F=234.28,P<0.01),与白色混合光照射组相比,绿光照射组绿敏视锥细胞密度明显增多(q=389.68,P<0.01),紫光照射组明显减少(q=67.11,P<0.01).视网膜腹侧单标免疫细胞化学检测显示,3组紫敏视锥细胞的差异无统计学意义(F=3.14,P>0.05);视网膜混合区双标免疫细胞化学检测显示,与白色混合光照射组比较,绿光照射组共表达视锥细胞密度明显增多(q=157.55,P<0.01),紫光照射组共表达视锥细胞密度明显减少(q:254.85,P<0.01).与白色混合光照射组相比,绿光照射组绿敏视蛋白及其mRNA的表达均明显增多(q=4.71,P<0.05;q=184.45,P<0.01);紫光照射组长波长敏感视蛋白(L视蛋白)及其mRNA的表达均明显减少(q=346.66,P<0.01;q=5.87,P<0.05);各组之间短波长敏感视蛋白(S蛋白)及其mRNA的表达差异均无统计学意义(F=3.27,P>0.05;F=1.24,P>0.05).结论长时间单色光照射下,豚鼠视网膜视锥细胞及其视蛋白的表达表现出相应的变化,这可能是视锥细胞选择有利的空间视敏度而对单色光照射环境的一种代偿性反应,说明色觉系统的发育具有一定的可塑性.绿敏视锥细胞密度的升高可能是与过渡区共表达视锥细胞的分化有关.%Background The visual system of animal have to optimally adjust in various environmental conditions in order to obtain stable and effective visual funetion.However,the color vision system of animals which encounter uncertainty of spectral signals should be plastic.Whether the densities of various cones and expression of opsins change with long-time spectral deprivation is unclear.Objective This study was to investigate the changes of cone density as well as the expression of corresponding opsin and mRNA following the long-term illumination of monochromatic light.Methods Thirty 3-day-old guinea pigs were randomized into 3 groups and exposed tO the 530 nm green light,400 nm purple light and white light for consecutive 8 weeks respectively.The flat-mounted retinal sample was prepared and divided into dorsal zone,ventral zone and mixed zone anatomically according to the distribution of difierent light-sensitive cone.The changes in density of cone cells sensitivited to different colored light were detected by single-1abel or double-label immunocytochemistry.The levels of opsin and its mRNA were determined using Western-blot and real-time PCR respectively.Results The density of green-sensitivity cones was significantly different in the dorsal zone of retina among green light group,purple light group and white light group (F=234.28,P<0.01).Compared with white light group,the density of green-sensitive cones in dorsal retina of green light group was obviously higher but that of purple light group wag evidently lower(q=389.68,P<0.01；q=67.11,P<0.01).No significant difference was found in the density of purple-sensitive cones in the ventral zone of retina among green light group,purple light group and white light group(F=3.14,P>0.05).The density of coexpression of the mixed cone cells was increased in green light group(q=157.55,P<0.01)but decreased in purple light roup (q=254.85,P<0.01)in comparison with white light group.The expression levels of green-opsin and green-opsin mRNA in green light group was significantly elevated(q=184.45,P<0.01；q=4.71,P<0.05),but those of purple light group were evidently declined(q=5.87,P<0.05；q=346.66,P<0.01)in comparison with white light group.There was no statistically significant differences were found in the expression of purple-opsin and its mRNA among all the groups(F=1.24,P>0.05；F=3.27,P>0.05).Conclusion After the exposure of long-time monochromatic light illumination,monochromatic cones density and its opsin in guinea pig occur the corresponding alteration to gain good spatial vision as a compensatory reaction.These outcomes imply that there is some plasticity during the development of color vision.The increase of green-sensitive cones might be from the differentiation of coexpression cones in transition region.
展开▼
