甘露醇对实验性视网膜挫伤后神经上皮层水通道蛋白4表达的影响

目的　探讨甘露醇对实验性视网膜挫伤后神经上皮层水通道蛋白4（aquaporin 4，AQP-4）表达的影响。方法　取健康成年大白兔36只，随机分为治疗组、生理盐水组和实验对照组，每组分别在造模后1 d、3 d、7 d、15 d四个时间点进行观察，每个时间点均选取3只兔，均选取右眼为致伤眼。治疗组在造模后立即静脉注射甘露醇（依据体质量按0.5 g·kg^-1用量），然后每12 h给药1次；生理盐水组造模后在各时间点给予相应剂量的生理盐水；实验对照组造模后不给予任何处理。采用免疫组织化学法检测AQP-4在神经上皮层表达情况。结果　各组兔视网膜神经上皮层AQP-4均有表达，阳性表达主要见于视网膜神经节细胞层与内核层。造模后1 d和3 d，治疗组、生理盐水组和实验对照组3组间视网膜神经上皮层AQP-4的表达总体比较差异均有统计学意义（均为P<0.05）；造模后7 d和15 d，3组间AQP-4的表达总体比较差异均无统计学意义（均为P>0.05）；造模后1 d和3 d治疗组与生理盐水组和实验对照组相比，AQP-4的表达均明显降低（均为P<0.05）；生理盐水组与实验对照组相比，AQP-4的表达在4个时间点差异均无统计学意义（均为P>0.05）。造模后视网膜神经上皮层AQP-4的表达随时间呈动态变化；治疗组、生理盐水组和实验对照组AQP-4的表达在造模后1 d、3 d、7 d、15 d均逐渐下降，4个时间点总体比较差异均有统计学意义（均为P<0.05）；各组在造模后1 d和7 d AQP-4的表达差异均有统计学意义（均为P<0.05），造模后1 d和15 d以及3 d和15 d比较差异亦均有统计学意义（均为P<0.05），其余各时间点间两两比较差异均无统计学意义（均为P>0.05）。结论　AQP-4与挫伤后视网膜水肿的发生发展密切相关；甘露醇可明显降低视网膜挫伤后早期神经上皮层AQP-4的表达。

Effects of mannitol on the expression of aquaporin-4 in retinal neurepithelium after experimental retinal contusion

Objective　To investigate the effect of mannitol on expression of aquaporin-4 in retinal neurepithelium after experimental retinal contusion.Methods　A total of 36 healthy adult rabbits were randomly divided into 3 groups:mannitol treatment group，sodium chloride control group and experimental control group.Rabbits in each group were observed on day 1，3，7 and 15 after modeling，respectively.And three rabbits of each group were selected for observation at each time point，and right eyes were selected to establish a model of experimental retinal contusion.Rabbits in the mannitol treatment group were given with intravenous injection of mannitol after modeling （0.5 g·kg^-1 based on body mass index） once each 12 hours.Rabbits in the sodium chloride control group were given the same amount of sodium chloride at each time point after modeling；and rabbits in the experimental control group left untreated.The expression levels of AQP-4 in retinal neuroepithelial layers were observed with immunohistochemical methods.Results　The expression levels of AQP-4 were observed in retinal neuroepithelial layers in rabbits of each group，and positive expression was mainly found in ganglion cell layer and inner nuclear layer.On day 1 and 3 after modeling，there were significant differences in the expression of AQP-4 at retinal neuroepithelial layers among three groups （all P<0.05）；but no statistical difference was found in the expression of AQP-4 among three groups on day 7 and 15 after modeling （all P>0.05）；the expression of AQP-4 was obviously reduced in the mannitol treatment group and sodium chloride control group comparing with that in the experimental control group on day 1 and 3 after modeling （all P<0.05）.No statistical difference was found in the expression of AQP-4 at the four time points between sodium chloride control group and experimental control group （all P>0.05）.The expression of AQP-4 in retinal neuroepithelial layers showed dynamic change with time after modeling.Expression of AQP-4 gradually decreased in mannitol treatment group，sodium chloride control group and experimental control group on day 1，3，7 and 15 after modeling，and statistical difference was found among the four time points （all P<0.05）.Statistical differences were found in the expression of AQP-4 at each group between 1 d and 7 d，between 1 d and 15 d，between 3 d and 15 d after modeling （all P<0.05）.No statistical difference was found between each two groups at each time point （all P>0.05）.Conclusion　AQP-4 is closely related to the occurrence and development of retinal edema.Mannitol can obviously reduce the early expression of AQP-4 in neural epithelial layers after retinal contusion.