提前光照刺激对早产近视小鼠视网膜中capase-3表达的影响

目的 观察早产近视小鼠视网膜的凋亡情况以及caspase-3蛋白的表达变化,探讨早产近视的发病机理.方法 选取实验用新生C57BL/6J小鼠共60只,随机分成3组(P6开睑组、P10开睑组和自然开睑组),每组各20只.P6开睑组和P10开睑组分别于新生6d龄和10 d龄处理右眼,使其睁眼接受提前光照,左眼为自身对照不作处理,自然开睑组小鼠眼睑待P14时自然睁开.所有小鼠于P15检影验光获得双眼屈光度数,采用电子数显千分尺测量眼轴长度,TUNEL法检测各组小鼠视网膜细胞的凋亡,免疫组织化学方法和Western-blot检测小鼠视网膜中caspase-3蛋白的表达.结果 P6开睑组小鼠形成了(-7.55±0.15)D的相对近视,P10开睑组小鼠形成了(-5.25±0.10)D的相对近视,自然开睑组小鼠未形成相对近视,三组比较差异有统计学意义(P＜0.05);P6开睑组右眼眼轴长度(2.49±0.08) mm及P10开睑组小鼠右眼眼轴长度(2.51±0.03)mm均明显短于自然开睑组右眼眼轴长度(2.58±0.04)mm,三组比较差异有统计学意义(P＜0.05).免疫组织化学结果显示:caspase-3阳性细胞主要表达于P6开睑组和P10开睑组小鼠视网膜内核层和神经节细胞层.TUNEL结果显示,P6开睑组和P10开睑组小鼠视网膜视神经节细胞层可见棕黄色凋亡细胞.Western-blot结果显示caspase-3蛋白P6开睑组(灰度值52.70％)和P10开睑组(灰度值35.76％)小鼠视网膜中的表达量上调.结论 提前光照刺激可诱导小鼠形成相对近视,接受光照的时间越早,小鼠形成的相对近视度数越高;提前光照刺激小鼠近视形成过程中,神经节细胞和内核层细胞发生凋亡,caspase-3蛋白参与凋亡的发生.

Effects of early lighting exposure on the expression of retinal caspase-3 in animal model of premature myopia

Objective To observe the apoptosis of retina and the expression of caspase-3 in mice with premature myopia and to explore the pathogenesis of premature myopia.Methods Together 60 newborn C57BL/6J mice were selected and divided randomly into three groups (n =20):P6 group (opening the eyelid on day 6 after birth),P10 group (opening the eyelid on day 10 after birth) and normal group (opening the eyelid naturally).The right eyes of mice in the P6 and P10 group were subjected to lighting exposure,and the left eyes were left untreated serving controls with its right eyes;while the eyes in the normal group open naturally without any treatment.Then the refraction was checked on day 15 through retinophotoscopy,and ocular axial length was measured by micrometer with electronic digital display.TUNEL assay was used to determine retinal apoptosis.Immunohistochemistry and Western blot were used to detect the expression of caspase-3 in mice retina.Results The right eyes developed significant myopia in the P6 group [(-7.55 ±0.15)D] and P10 group [(-5.25 ±0.10)D],while the eyes in the normal group did not suffer from myopia,and there was significant difference in the three groups (P ＜0.05).The average axial length of right eyes in the P6 group [(2.49 ± 0.08) mm] and the P10 group [(2.51 ±0.03)mm] was shorter than that in the normal group [(2.58 ± 0.04) mm],with significant difference (P ＜ 0.05).Immunohistochemistry showed that the expression of caspase-3 had a dramatically increase in ganglion cell layer and inner nuclear layer of retina of mice in P6 group and P10 group.TUNEL results showed that brown-stained positive apoptotic cells appeared in ganglion cell layer in the P6 and P10 group,while Western blot showed that the expression of caspase-3 protein in mouse retina in P6 group (gray value 52.70％) and P10 group (gray value 35.76％) was upregulated.Conclusion Early lighting exposure can induce premature myopia of mice,and the earlier the mice receive light,the higher the relative degree of myopia is;meanwhile during the process of premature myopia,ganglion cells and nuclear layer cells suffer apoptosis,as well as caspase-3 protein involves in the occurrence of apoptosis.