二十二碳六烯酸抑制大鼠视网膜光感受器细胞凋亡

Inhibiting Effect of Docosahexaenoic Acid on Apoptosis of Photoreceptor Cells of Rats

目的:观察二十二碳六烯酸(DHA)对N-甲基-N-亚硝基脲(MNU)所致视网膜光感受器细胞凋亡的影响,为其临床应用提供理论依据。方法:35只雌性SD大鼠随机分为7组,每组5只。除正常组外,其余各组均于出生后35 d开始灌胃,DHA组和造模组每日分别灌服含有一定量DHA的脱脂牛奶或等体积的脱脂牛奶,持续15 d后行腹腔注射MNU 40 mg/kg。分别于造模后12,24,48 h全麻后处死相应动物,取眼球行光镜观察及用末端脱氧核苷酸转移酶介导dUTP缺口末段标记(TUNEL)法检测各组大鼠视网膜细胞的凋亡。结果:光镜下显示中周部视网膜在造模后24 h开始出现光感受器细胞排列紊乱,少量核固缩,48 h后光感受器细胞已大量溶解,而DHA组光感受器细胞的形态均接近正常,仅见排列紊乱、稀疏。造模组光感受器细胞在造模后12,24,48 h的凋亡百分率(AI)分别为(5.3±1.1)%、(60.6±4.1)%、(97.1±1.9)%,DHA组在造模后12,24,48 h的AI分别为(4.3±1.4)%、(44.5±7.8)%和(78.7±5.8)%,24 h和48 h后造模组和DHA组间比较均有统计学差异(P<0.05)。结论:二十二碳六烯酸40 mg/(kg.d)可以有效抑制视网膜光感受器细胞的凋亡。

Objective： To observe the effects of docosahexaenoic acid（DHA） on the histomorphology of retina and photoreceptor cells apoptosis induced by N-methyl-N-nitrosourea（MNU）,in order to provide some valuable evidences for clinical application of DHA.Methods： Thirty-five female SD rats were randomly divided into seven groups（with five rats per group）.Except the normal group,all rats in DHA groups or model groups were daily and intragastrically administrated of skim milk added DHA or the equal volume of skim milk for 15 days since the 35th day after the birth.These animals were intraperitoneally injected with MNU at 40 mg/kg,and then were sacrificed at 12 h,24 h or 48 h after injection.The eyeballs were taken into the fixatives for histological observation and TUNEL staining.Results： By light microscopy,we observed the change of retina after injection of MNU.Photoreceptor cells of retina were arranged irregularly and few nuclei condensated in model group 24 hours after MNU injection.After 48 hours of animal models establishment,a large amount of nucleis dissolved.But the morphology of photoreceptor cells didn＇t show evident changes in all DHA groups.We only observed that the arrangement of cells were loose and irregular in 24 h and 48 h DHA groups.The AI of the photoreceptor cells in 12 h,24 h and 48 h model groups were（5.3±1.1）%,（60.6±4.1）%,and（97.1±1.9）%,respectively,and（4.3±1.4）%,（44.5±7.8）%,and（78.7±5.8）% respectively,in 12,24,and 48 h DHA groups.Significant difference was found between the model groups and DHA groups after 24 h and 48 h after animal models establishment（all P0.05）.Conclusion： DHA at the dosages of 40 mg/kg was capable of inhibiting the apoptosis of the photoreceptor cells.