Study On Amelioration Of Irradiation-induced Salivary Gland Damage In Mice By Antioxidants And Underlying Mechanisms

Objective:A mouse model of ionizing radiation-induced salivary gland damage was constructed using X-rays whole neck irradiation to study the radiation protective effect of HL-003 and its possible mechanism.Methods:The salivary gland damage model induced by ionizing radiation was established by giving 15 Gy of local X-ray irradiation to the neck of mice.The changes of salivary flow rate in each group were detected at 3,7 and 10 days after irradiation;H&E staining was used to observe the pathological changes of salivary glands;the effects of HL-003 on salivary gland epithelial cell marker AQP-5,oxidative stress-related proteins SOD2 and 8-OHdG,and DNA damage markerγ-H2AX,were detected by immunohistochemistry;the apoptosis of salivary gland cells was detected by TUNEL;the expression levels of apoptosis-related proteins were detected by Western blot.Results:HL-003 prevents radiation-induced salivary gland dysfunction and maintains salivary flow rate.HL-003 protects salivary gland epithelial cells by inhibiting the reduction of zymogen granule and acinar vacuolation in salivary glands.Mechanism studies have shown that HL-003 alleviated oxidative stress and DNA damage in salivary gland tissues by regulating the expression of NOX4,SOD2,8-OHdG and y-H2AX.In addition,HL-003 was also involved in regulating the expression of apoptosis-related proteins p-p53,Bax,Bcl-2,Caspase 3 and Caspase 9,suggesting that HL-003 may reduce apoptosis by inhibiting the activation of p53.Conclusion:HL-003 is an effective radioprotector to prevent salivary gland damage caused by ionizing radiation.Objective:To investigate the effects of melatonin(MLT)on whole-neck irradiation(WNI)-induced salivary gland damage in mice.Methods:The salivary gland damage model induced by ionizing radiation was established by giving 15 Gy of local γ-ray irradiation to the neck of mice.The changes of salivary flow rate in each group were continuously detected at 12 weeks after irradiation;H&E,AB-PAS and Masson staining were used to observe the pathological changes of salivary glands;the expression of salivary gland epithelial cell marker AQP-5,oxidative stress-related proteins SOD2 and 8-OHdG,and DNA damage marker y-H2AX were detected by immunohistochemistry;the apoptosis of salivary gland cells was detected by TUNEL;RNA-seq was used to explore the possible mechanism of radiation protection of MLT;the expression level of differential genes was detected by real-time quantitative PCR.Results:By protecting the channel protein AQP-5,MLT not only alleviates salivary gland dysfunction and maintains salivary flow rate,but also protects salivary gland structure and inhibits the WNI-induced reduction in mucin production and degree of fibrosis.Compared with WNI-treated mice,in those receiving MLT,we observed a modulation of oxidative stress in salivary glands via its effects on 8-OHdG and SOD2,as well as an inhibition of DNA damage and apoptosis.With respect to its radioprotective mechanism,we found that MLT may alleviate WNI-induced xerostomia via ribosome-related signaling pathways.In vitro,we demonstrated that MLT has radioprotective effects on salivary gland stem cells.Conclusion:MLT can effectively alleviate radiation-induced damage in salivary glands,thereby providing a new candidate for the prevention of WNI-induced xerostomia.