Laminaria Polysaccharide Protects The Radiation-induced Vascular Injury Of Submandibular Glands By Regulating The P38MAPK Pathway

Objective:To investigate the effect of laminaria japonica polysaccharides?LJP?on the induction of vascular injury in submandibular glands of mice by p38mitogen-activated protein kinase?p38 MAPK?signaling pathway.Method:1.120 female 2-month-old Kunming mice were randomly divided into control group,LJP group,radiation group,radiation+LJP group,30 mice in each group.The radiation induced submandibular glands injury model was established by⁶⁰Co?ray.LJP was intraperitoneally injected from 1d before radiation to 7d after radiation,then the injection changed every 2 days,and ended 14 days after radiation.2.The weight of mice in each group was detected after 1d,7d,14d after radiation,and the total saliva induced by pilocarpine in 30 min was collected,and the weight of submandibular gland in each mouse was weighed.3.HE staining was used to observe the morphological changes of the acinar,catheter,vascular and tissue interstitial in 1d,7d and 14d after radiation.4.Immunohistochemical staining was used to observe the expression of CD31,p-p38MAPK and Bcl-2 in the mice's submandibular glands of 1d,7d and14d after radiation.5.The expression of VEGFA and VEGFR-2 was detected at 1d,7d,and14d after radiation by real-time fluorescence quantitative PCR?qRT-PCR?.6.Enzyme-linked immunosorbent assay?ELISA?was used to measure p-p38MAPK and endothelin-1?ET-1?levels in the submandibular glands.Results:1.Weight changes of mice in different time points:weight of radiation group and radiation+LJP group decreased significantly?P<0.05?.Compared with radiation group,the weight of mice in radiation+LJP group increased?P<0.05?,but there was no difference between LJP group and control group?P>0.05?.2.The amount of saliva of mice in each group at 1d,7d,14d after irradiation:the amount of saliva of mice in radiation and LJP group at different time points was significantly reduced?P<0.05?,with the treatment of LJP,compared with radiation group,the amount of saliva in radiation+LJP group mice increased?P<0.05?,there was no difference between the LJP group and the control group?P>0.05?.3.There was no significant difference in the weight of submandibular gland in each group?P>0.05?.4.HE staining showed that:compared with the control group,there was no significant changes of submandibular gland morphology of mice in LJP group.The control group had abundant capillaries and a large number of red blood cells.Compared with the control group,the capillaries in the radiation group and the radiation+LJP group were less,the smaller acinar cells were seen in the low power microscope,and the small amount of red blood cells were seen in the high power microscope.The acinar cells in the radiation group and the radiation+LJP group showed vacuolar degeneration,with the prolongation of time after treatment of LJP,the amount of capillaries in the radiation+LJP group increased.5.The expression of p-p38MAPK in radiation group and radiation+LJP group increased in 1d,7d and 14d after radiation?P<0.05?,the peak value reached in 1d after radiation,with the prolongation of time after treatment of LJP,the expression of p-p38MAPK in the radiation+LJP group decreased,it returned to the control group in 14d after radiation.The expression of endothelin-1?ET-1?in radiation group and radiation+LJP group increased?P<0.05?,with the prolongation of time after treatment of LJP,the expression of ET-1 in the radiation+LJP group decreased at different time points.There was no significant difference between the LJP group and the control group?P>0.05?.6.The expression of CD31,Bcl-2 in radiation group and radiation+LJP group decreased in 1d,7d and 14d after radiation?P<0.05?,after treatment of LJP,the expression in radiation+LJP group was higher than that in radiation group?P<0.05?at different time points,there was no significant difference between LJP group and control group?P>0.05?.Conclusions:1.Radiation-induced submandibular gland vascular injury is associated with radiation-induced p38 MAPK phosphorylation,and submandibular gland vascular injury results in decreased salivary flow in mice.2.LJP can down-regulate phosphorylation of p38MAPK and down-regulate ET-1 to protect radiation-induced submandibular gland vascular injury and then increase the salivary flow rate in mice.3.LJP upregulates VEGFA and VEGFR-2 expression and down-regulates phosphorylation of p38MAPK to ameliorate radiation-induced submandibular gland vascular injury.