Yao Qing-Ting, Wu Yan-Hui, Liu Shao-Hua, Xu Hui, Li Jun, Shi Liang
Department of Oral and Maxillofacial Surgery, People's Hospital of Xinjiang Uygur Autonomous Region. Urumqi 830001, Xinjiang Uygur Autonomous Region, China. E-mail:
Shanghai Kou Qiang Yi Xue. 2022 Aug;31(4):359-366.
To investigate the effect and the potential mechanism of ionizing radiation on secretory function and tight junction (TJ) protein claudin-4 in paracellular pathway of rat parotid glands.
Twenty four 8-week-old male Wistar rats were randomly divided into one control group(n=6) and three irradiation groups (i.e., 1-week group post-irradiation, 4-week group post-irradiation, and 12-week group post-irradiation, 6 rats in each group). The experimental glands of irradiation groups were exposed to X-radiation in one-time single doses of 20 Gy. The residual salivary secretion of parotid glands was measured by Schirmer's test. The pathological changes of gland tissues were observed under light microscope after hematoxylin-eosin(H-E) staining. The changes of TJs ultrastructure were observed under transmission electron microscopy (TEM). Immunofluorescence staining and Western blot were used to detect the expression levels of muscarinic acetylcholine M3 subtype receptor, aquaporin 5 (AQP5), and claudin-4 proteins. The experimental results were analyzed with SPSS 23.0 software package for one-way analysis of variance.
The residual salivarysecretion of irradiation group glands at 1, 4, and 12 weeks after irradiation was reduced compared with that of the control group(P<0.05), and the residual salivary secretion of irradiation group at 12 weeks was significantly lower than that at 4 weeks(P<0.05). Histologically, the dilation and congestion of interstitial vessels were observed at early stage after irradiation, and significant reduced number of acinar cells was found at late stage(P<0.05). In the irradiation groups, the ultrastructures of TJ were fuzzy, the electron density was decreased, and the TJ width at 1, 4, and 12 weeks was reduced compared with that in the control group. Immunofluorescence staining and Western blot indicated that the protein expression levels of M3 and AQP5 were down-regulated; however, the protein expression levels of claudin-4 were significantly increased at 1, 4, and 12 weeks after irradiation.
After ionizing radiation, decreased secretory function of paracellular pathway, alterations in TJ structures, and up-regulation of claudin-4 expression may be involved in the mechanism of hyposecretion in rat parotid glands after irradiation.
探讨电离辐射对大鼠腮腺旁细胞途径分泌功能及紧密连接（TJ）蛋白claudin-4的影响及其潜在机制。
将24只8周龄雄性Wistar大鼠随机分为1个对照组（n = 6）和3个照射组（即照射后1周组、照射后4周组和照射后12周组，每组6只）。照射组的实验腺体一次性接受20 Gy的X射线照射。采用泪液滤纸试验测量腮腺残余唾液分泌量。苏木精-伊红（H-E）染色后，在光学显微镜下观察腺体组织的病理变化。在透射电子显微镜（TEM）下观察TJ超微结构的变化。采用免疫荧光染色和蛋白质免疫印迹法检测毒蕈碱型乙酰胆碱M3亚型受体、水通道蛋白5（AQP5）和claudin-4蛋白的表达水平。实验结果采用SPSS 23.0软件包进行单因素方差分析。
照射后1、4和12周，照射组腺体的残余唾液分泌量低于对照组（P < 0.05），且照射后12周照射组的残余唾液分泌量显著低于4周时（P < 0.05）。组织学上，照射后早期可见间质血管扩张和充血，后期腺泡细胞数量显著减少（P < 0.05）。在照射组中，TJ的超微结构模糊，电子密度降低，照射后1、4和12周时TJ宽度与对照组相比减小。免疫荧光染色和蛋白质免疫印迹法表明，M3和AQP5的蛋白表达水平下调；然而，照射后1、4和12周时claudin-4的蛋白表达水平显著升高。
电离辐射后，旁细胞途径分泌功能降低、TJ结构改变以及claudin-4表达上调可能参与了大鼠腮腺照射后分泌减少的机制。
