| Objective:Explore the possibility of the occurrence of radiation-induced heart damage caused by 15Gy/3f irradiation with a biological effect dose(BED)similar to that of24Gy/12 f and the changes in early detection indicators,and explore the effect of combining recombinant human endostatin(Endostar,E).Method:75 SD adult male rats were randomly divided into 5 groups(15 rats in each group).The control group were blank control group(group C,no irradiation and Endostar injection),Endostar group(group E,intraperitoneal injection of Endostar 14days)),and cardiac irradiation 25Gy/5f group(MHD25 group,positive control group,5Gy/f,1f/d,continuous irradiation for 5 days),the experimental group were cardiac irradiation 15Gy/3f group(MHD15 group,5Gy/f,1f/d,continuous irradiation for 3days),and cardiac irradiation 15Gy/3f combining Endostar group(MHD15+E group,5Gy/f,1f/d,continuous irradiation 3 days,simultaneous injection of Endostar 14days);At 24 h,48h,and 15 d after irradiation,the tail blood of rats was taken and used an automatic biochemical analyzer to measure creatine kinase(CK),creatine kinase,MB form(CK-MB),lactate dehydrogenase(LDH)and c-reactive protein(CRP)in each group;At 1,3,and 6 months after irradiation,5 rats in each group were randomly selected to perform cardiac echocardiography to detect ejection fraction(EF),fractional shortening(FS)and other indicators,then the rats were killed and myocardial tissues were taken for HE,Masson,Immunohistochemistry CD34 microvessel staining and semi-quantitative analysis using Image J software;Western Blot and q PCR were used to detect mitochondrial complex II,transforming growth factor-β1(TGF-β1),P-smad2,collagen I protein and gene expression;The experimental results were calculated by Graph pad 5.0 using two-way ANOVA statistics.Results:Compared with group C,group E had no significant changes,MHD25 group,MHD15 group and MHD15+E group observed part of myocardial cell edema and part of inflammatory cell infiltration at 1,3 months after irradiation,the interstitium of myocardial tissue was widened,and the changes of cord-like or reticular fibrosis were seen at 6 months in HE staining.The number of myocardial microvessels per unit area in group E,MHD25 group,MHD15+E group,and MHD15 group all less than that of group C at 1,3,and 6 months after irradiation in microvessel staining;Semi-quantitative analysis showed that the decrease in microvessel density consistent with qualitative analysis was statistically significant(P<0.05),and the microvessel density of each group except for group C was further reduced in 6 months compared with 1 month(P<0.05).Compared with group C,collagen deposition between myocardial tissues increased in the MHD25 group at 3 months after irradiation,and diffuse collagen fiber deposition in the myocardial interstitium at 6 months in the MHD25 group,MHD15 group and MHD15+E group in masson staining;The semi-quantitative analysis results are consistent with qualitative analysis.Compared with group C,the collagen volume fraction(CVF)of the MHD25 group was significantly increased at 3 months after irradiation(P<0.05),and the CVF of the MHD25 group,MHD15 group and MHD15+E group was significantly increased at 6months(P<0.05),and there was no significant difference between the C group and the E group.Compared with group C,the expression of mitochondrial complex II protein was significantly decreased in the MHD25 group at 3 months after irradiation(P<0.05),which also decreased in the MHD25 group,MHD15 group and MHD15+E group at 6months(P<0.05),among them,MHD25 group was compared with MHD15 group the expression was significantly decreased(P<0.05),and there was no significant difference between group C and group E.Compared with group C,TGF-β1,P-smad2,Collagen-I protein expression and TGF-β1,Smad2,Collagen-I gene expression in the MHD25 group increased significantly after 3 months of irradiation(P<0.05),and the expression of the above factors in the MHD25 group,MHD15 group and MHD15+E group increased significantly at 6 months(P<0.05),among them,MHD25 group was compared with MHD15 group the expression of the above factors was significantly increased(P<0.05),and MHD15+E group was compared with MHD15 group the expression of the above factors was significantly increased(P<0.05),there was no significant difference between group C and group E.The detection of serum myocardial enzymes and inflammatory factors showed that there were no significant differences in CK,CK-MB,LDH,and CRP among the groups at 24 h,48h,and 14 d after irradiation(P>0.05).The echocardiogram showed that compared with group C,the EF and FS of MHD25 group,MHD15+E group,and MHD15 group were all decreased at 3 and 6 months after irradiation(P<0.05),and the degree was similar(P>0.05).Comparing 6 months with 1 month after irradiation,EF and FS were decreased in each group(P<0.05),there was no significant difference between group C and group E.However,the thickness of the anterior wall of the left ventricle at the end of systole,the anterior wall of the left ventricle at the end of diastole,the posterior wall of the left ventricle at the end of systole,and the thickness of the posterior wall of the left ventricle at the end of systole in each group had no statistical significance in the same time period of 1,3,and 6 months after irradiation(P>0.05).Conclusion:SD rat heart 15Gy/3f irradiation cause cardiac function damage in the early stage,the EF and FS of echocardiogram are abnormal,the structure of the ventricle has no obvious change.Functional indicators such as EF and FS may detect the occurrence of RIHD early,but serological predictive indicators have yet to be found.Myocardial fibrosis in the late stage,the appearance delayed and degree is lower than that of high-dose irradiation,and all induce myocardial fibrosis through TGF-β1/Smad2 signaling pathway.Endostar 6mg/kg injection observed no obvious myocardial fibrosis,and compared heart irradiation combined with Endostar with cardiac irradiation alone,the expression of TGF-β1/Smad2 signaling pathway related factors increased. |
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