Objective To establish a radiation-injured model of lacrimal gland in mice and explore its pathophysiology.Method Experimental research.According to the random number table,50 healthy mice were divided into five groups:one control group (n =10) and four experimental groups (n =40).The experimental mice (n =40) were exposed to different dosages of irradiation 12,15,18 and 21 Gy,respectively.The sham-irradiated controls (n =10) were anesthetized in parallel with the irradiated rats but not irradiated.The mice were placed laterally and covered with a bolus material,then the X-ray irradiation was performed under general anaesthesia from above towards the mice' orbital region.The schirmer tests,Single-photon emission computed tomography/Computed tomography (SPECT/CT),HE,immunohistological,and ultrastructural examinations were conducted prior and 3 days,7 days as well as 30 days after irradiation.Using t test to compare the differentiation of each group at the same time point.Results In 12 Gy group,there is no statistically significant decline in tear secretion (3 days after radiation,t =2.137,P =0.061 ;7 days after radiation,t =1.137,P =0.243).In 15 Gy group,Schirmer Ⅰ test showed significantly reduced lachrymal secretion and the difference was statistically significant(3 days after radiation:t =3.228,P =0.011 ;7 days after radiaton:t =4.781,P =0.001 ; 30 days after radiation:t =3.162,P =0.011).Immunohistochemical findings include a significant loss in the expression of α-SMA (3 days after radiation,t =4.395,P =0.013 ;30 days after radiation,t =3.049,P =0.035),aquaporin (AQP-5) (3 days after radiation,t =3.587,P =0.028 ;30 days after radiation,t =5.598,P =0.005),and an excessive expression of Tenascin-C (3 days after radiation,t =2.964,P =0.046 ; 30 days after radiation,t =4.028,P =0.017)and CK8 (3 days after radiation,t =5.103,P =0.008 ; 30 days after radiation,t =6.178,P =0.004),which were statistically significant.Ultrastructural changes include a retention of secretory granules and an increase of apoptotic acinar nuclei as well as macrophage phagocytosis.Disturbance in the tracer uptake as well as reduction of the lacrimal ejection fraction was assessed under SPET/CT test and the difference was statistically significant(3 days after radiation:t =2.796,P =0.029 ; 30 days after radiation:t =2.641,P =0.038).This radiation dosage didn't cause obvious eye complications (cataract,radiation retinopathy,etc.).At the dosages of 18 and 21 Gy,the lacrimal gland inflammation and tissue apoptosis expand obviously.Conclusions The model of radiation-injured lacrimal gland was successfully constructed.Pathophysiological manifestation include the impaired structures of lacrimal gland cells and infiltration of inflammatory cells,as well as damaged function of tear secretion.These changes may prerequisites for further study on radiological protection of lacrimal glands during radiotherapy of the periorbital region for orbital tumors.%目的 建立放射性泪腺损伤动物模型并探讨其相应的病理生理改变.方法 实验研究.8周龄雌性C57BL/6小鼠,50只,按照随机数字表法分成5组(各10只):12、15、18、21 Gy照射剂量组及正常对照组.小鼠取卧位并于全身麻醉后行眼眶X线局部外照射.分别于照射前、照射后3d、7d和30 d行泪液分泌试验、泪腺闪烁扫描检测(泪液分泌动力学研究)并取泪腺组织行组织学及超微结构检测.采用t检验比较各组在同一时间点的差异.结果 12 Gy放射剂量组与正常对照组之间差异无统计学意义(照射后3 d:t =2.137,P=0.061;照射后7 d:t=1.137,P =0.243).当照射剂量为15 Gy时,与正常对照组相比,Schirmer Ⅰ检测泪液分泌功能降低,差异有统计学意义(照射后3 d:t =3.228,P =0.011;照射后7 d:t =4.781,P=0.001;照射后30 d:t =3.162,P=0.011);与泪腺分泌相关的α-平滑肌肌动蛋白(α-SMA)(照射后3 d:t =4.395,P=0.013;照射后30 d:t=3.049,P=0.035)、腺体特异水分子通道蛋白5(AQP5)(照射后3d:t=3.587,P=0.028;照射后30 d:t=5.598,P=0.005)的图像吸光度(A)值减少,而细胞黏合素C(Tenascin-C)(照射后3 d:t =2.964,P=0.046;照射后30 d:t=4.028,P=0.017)、细胞角蛋白8(CK8)(照射后3 d:t =5.103,P=0.008;照射后30d:t=6.178,P=0.004)的图像A值增加,差异有统计学意义(P＜0.05);在透射电镜下观察,凋亡小体增多,染色质边集,基质溶解呈空泡状,可见大量巨噬细胞吞噬现象,分泌颗粒减少,基底膜增厚,炎性细胞浸润;泪腺闪烁扫描检测显示泪腺分泌指数下降,差异有统计学意义(照射后3 d:t2.796,P=0.029;照射后30 d:t =2.641,P=0.038);未发现明显眼内并发症(白内障、放射性视网膜病变等).放射剂量增加时,泪腺组织的炎症反应加重,组织凋亡明显,泪腺丧失泪液分泌功能.结论 小鼠X线眼眶外局部照射总量为15 Gy时,可建立放射性泪腺损伤动物模型,病理生理上表现为泪腺组织、细胞结构的破坏,炎性细胞的浸润及泪液分泌功能的降低.
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