Objective To investigate the therapeutic effect of Vitamin A on the recovery of dry eye that was induced by benzalkonium chloride (BAC) topical medication in the mouse.Methods In this randomized controlled experimental study,50 BALB/c mice were treated with the topical administration of 0.25％ BAC to establish the dry eye condition.Based on the consistency of tear film break-up time (BUT),corneal fluorescein staining scores and inflammation index,the eyes were re-selected and 30 mice were randomly divided into three groups on day 21 after the BAC treatment,with 10 mice (20 eyes) in each group.Group C was set up as a blank control,while groups A and B were treated with 5000 IU/(g·ml) Vitamin A eye drops and microemulsion solvent drops,respectively.BUTs,corneal fluorescein staining scores,inflammation index and tear volumes were evaluated in each group on days 0,1,3,5 and 7 after the therapeutic treatment.Global specimens were collected on day 7.Sections were stained with hematoxylin and eosin (HE) or by periodic acid-Schiff (PAS) assay,and labeled with cytokeratin 10 (K10) antibody.The expression of K10 in the cornea and conjunctiva was quantified by Western Blot.The data were analyzed by one-way ANOVAs.Results On days 0,1,3 and 5,no clinical differences were observed among the groups.On day 7,the BUT values were (4.20±0.89)s,(3.32±1.01)s and (3.28±0.74)s in groups A,B and C,respectively.The BUT in group A was significantly longer than those in groups B and C (F=6.852,P=0.002).The corneal fluorescein staining scores were 3.74±1.31,5.47±1.81 and 5.83±1.54 in groups A,B and C,respectively.The scores in group A were significantly lower than those in groups B and C (F=8.853,P＜0.01).No significant differences were found in the corneal inflammatory index or tear volume among the groups.Corneal morphology showed a loosened corneal epithelium feature in groups B and C,but comeal integrity in group A.PAS assay revealed similar goblet cell numbers between group A and normal eyes,but fewer goblet cells in groups B and C.Cytokeratin 10 was almost negatively expressed in Vitamin A treated groups,while it remained positive in the entire corneal epithelial layer with other treatments.The level of K10 in the cornea was down-regulated in Vitamin A treated groups.Conclusion Vitamin A treatment presented marked therapeutic effects on BAC-induced mouse dry eye,with a more stable tear film,better recovery of epithelial integrity,an increased number of goblet cells,and the elimination of squamous metaplasia,when compared to the treatment of microemulsion solvent eye drops only or without treatment.This experiment show the great potential of Vitamin A in the clinical treatment of dry eye.%目的 通过随机对照实验探讨维生素A对苯扎氯铵诱导的小鼠干眼的治疗作用.方法 实验研究.选用BALB/c小鼠50只,使用0.25％的苯扎氯铵溶液局部点眼以诱导干眼.在第21天时根据泪膜破裂时间(BUT)、角膜荧光素钠染色、炎症指数等参数选择干眼表现程度相近的小鼠30只(60眼)并随机分为A、B、C三组,每组10只(20眼).A、B组分别使用5000 IU/(g·ml)维生素A微乳剂和空白微乳剂滴眼,C组为空白对照组.在治疗的第0、1、3、5、7天检测BUT和角膜上皮荧光素钠染色、眼表炎症程度及基础泪液分泌量.7d治疗结束后取出小鼠眼球,进行HE及过碘酸-希夫(PAS)染色,角蛋白10(K10)免疫荧光标记,以及Western Blot检测角膜组织中K10表达水平.对数据采用单因素方差分析.结果 在药物治疗的第0、l、3、5天各项临床指标差异无统计学意义.治疗第7天时,A、B、C组BUT值分别为(4.20±0.89)s、(3.32±1.01)s和(3.28±0.74)s；其中A组的BUT值较B组和C组长,差异有统计学意义(F=6.825,P=0.002).A、B、C组角膜荧光素钠染色评分分别为3.74±1.31、5.47±1.81和5.83±1.54,其中维生素A微乳组较空白微乳组和空白对照组角膜荧光素钠染色分级轻,差异具有统计学意义(F=8.853,P＜0.01).各组间的角膜炎症指数评分、基础泪液分泌量差异均无统计学意义.组织病理检查示维生素A组与空白微乳组和空白对照组比较,其角膜上皮形态较规整；PAS染色示维生素A组杯状细胞数量更接近正常小鼠.维生素A组的角膜上皮层几乎均不表达K10,而空白微乳组及空白对照组呈阳性表达.Western Blot检测示维生素A组角膜中的K10水平低于空白微乳组和空白对照组.结论 维生素A可以延长苯扎氯铵诱导的干眼小鼠的BUT,降低角膜上皮染色程度,抑制角膜上皮鳞状化生,并能增加结膜杯状细胞数量,有望用于干眼治疗.
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