| Objective: To investigate the protective effect and relative mechanism of Ophiocordyceps sinensis polysaccharides(CSP)against X-ray irradiation in mice.The project provides a theoretical basis for the use of Ophiocordyceps sinensis polysaccharides as an effective radioprotector or an alternative strategy in reducing irradiation-induced injury.Methods: In this study,polysaccharides from Ophiocordyceps sinensis powder were extracted by hot water and the content of polysaccharides was determined by phenol-sulfuric acid method.The survival rate of mice for 30 days was determined,and the relevant indicators including blood peripheral parameters,organ indexes,DNA content of bone marrow,antioxidant enzyme activity and lipid peroxides content in liver,histopathology,and the expression of related enzymes in MAPK family were detected.In the survival rate experiment,male Kunming mice of SPF grade were randomly divided into control,model,positive(amifostine,150 mg/kg),low-dose CSP(100 mg/kg),middle-dose CSP(200 mg/kg),and high-dose CSP(400 mg/kg)groups.Mice were given saline or CSP orally in control and model groups and in CSP-treated groups,respectively,for 14 days before X-ray irradiation.Mice were administered amifostine via intraperitoneal injection in the positive group 30 min before 5 Gy irradiation.All mice except the control groups,received 8 Gy whole-body X-ray irradiation using a medical electronic linear accelerator.To investigate the antioxidant effect of CSP and relevant mechanism mediated by the MAPK pathway.The animals were grouped and administered the same way as the survival rate experiment.All mice,except the control groups,received 5 Gy whole-body X-ray irradiation.Body weight of mice was observed before and after irradiation,and blood physical parameters were determined on the 1st,3rd and 5th days after irradiation.The indexes of thymus and spleen of mice,DNA content of bone marrow,the activity of superoxide dismutase(SOD),glutathione peroxidase(GSH-PX),catalase(CAT)and the content of malondialdehyde(MDA)in livers were detected and the pathological changes of spleen and thymus of mice were observed on the 5th day after irradiation.The protein and m RNA expression of extracellular regulated protein kinase 1(ERK1),c-Jun N-terminal kinase 1(JNK1)and p38 mitogen-activated protein kinase(p38 MAPK)in livers were determined using ELISA and q PCR methods on the 5th day after irradiation.Results: The average content of polysaccharides in the fermented Ophiocordyceps sinensis was 1.35%.The improved phenol-sulfuric acid method showed stable absorbance,good precision and repeatability,and the results are accurate and reliable.The survival rate experiment results indicated that CSP could improve the physical signs and significantly improve the survival rate of irradiation-injured mice.Mice in the model group after 8 Gy X-ray irradiation showed worse conditions,such as loss of appetite,loss of weight,dull fur,slow movement and mental depression,and the survival rate was significantly decreased by 50%,than control group after irradiation.These signs in CSPtreated groups all improved,and the survival rate and time of mice were also significantly increased in 30 days.The survival rate of the middle-dose CSP group was 80% higher than that in the model group.The indexes determined experiments showed that CSP could significantly improve blood physiological parameters of irradiation-injured mice.Compared to the model group,WBC counts and LYM counts in the middle-dose CSP group were increased significantly by 59.65% and 70.00% on the 3rd day after irradiation,respectively,and GRA counts in low-and middle-dose CSP groups were increased by 100.00% and 71.43% on the 5th day after irradiation,respectively.PLT counts in low-dose CSP group were decreased by 22.84% and 24.43% on the 3rd and 5th days after irradiation,respectively,compared to the model group.At the same time,CSP could significantly improve the thymus and spleen indexes of the irradiation-injured mice,and the middle-dose CSP group exhibited remarkable increases of 69.62% and 30.00%,respectively,compared to the model group.However,there was no statistical significance of DNA content in bone marrow despite a small increase in each CSP group.Moreover,CSP could significantly change the activity of antioxidant enzymes and the content of lipid peroxides in the liver of irradiation-injured mice.SOD activity was increased significantly by 64.71%,52.36%,and 44.07% in the low-,middle-and high-dose CSP groups,respectively,compared to the model group.GSH-PX activity was decreased by 11.29%,18.16% and 22.37% in the low-,middle-and high-dose CSP groups,respectively,compared to the model group.CAT activity was decreased by 6.24%,10.88%,and 17.95% in the low-,middle-and high-dose CSP groups,respectively,compared to the model group.MDA content was decreased by 32.22% in the low-dose CSP group,and there was no statistical significance in the middle-and high-dose CSP groups,compared to the model group.Pathological results showed that CSP could improve the thymus and spleen damage caused by irradiation.The number of thymus and spleen lymphocytes was increased and pathological changes were improved compared to the model group.The results of related mechanism studies indicated that CSP could significantly change the protein and m RNA expression of ERK1,JNK1 and p38 MAPK in the liver of irradiation-injured mice.The protein expression of ERK1 was lower by 16.42% and 32.70%,in the middle-and high-dose CSP groups,respectively,and lower by 9.95% in the low-dose CSP group,but it was not significantly different from the model group.The protein expression of JNK1 in the high-dose group was decreased by 47.98%,and by 17.25% and 14.47% in the low-and middle-dose CSP groups,respectively,which shows a slight but not significant decrease,compared with the model group.The protein expression of p38 MAPK in all three CSP groups was decreased significantly by 18.95%,24.10% and 34.73%,respectively,compared to the model group.The m RNA expression of ERK1 in the low-dose,middle-dose and high-dose CSP groups was reduced by 60.92%,52.87% and 63.22%,respectively,compared to the model group.The m RNA expression of JNK1 was decreased by 66.77%,53.23% and 57.54%,respectively,and the m RNA expression of p38 MAPK was decreased significantly by 71.06%,61.89% and 55.30% in the lowdose,middle dose and high-dose CSP groups,respectively,compared to the model group.Conclusion: CSP protect mice from X-ray irradiation in vivo,which is speculated to be related to improving immunity and removing free radicals in the body,and this protective effect may be exerted via the MAPK signaling pathway. |
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