| Subject To evaluate the value of 18F-FDG PET/CT in assessing the radiosensitizing effect by oleanolic acid(OA) on C6 rat glioma model, and to explore the possible mechanism of radiosensitizing effect of OA.We also investigate the clinical value of 18F-FDG PET/CT in the C6 rat glioma model after early radiotherapy and the features of 18F-FDG PET/CT imaging in heterotopic transplantation rat C6 glioma model.Methods Thirty-two tumor-bearing SD rats were randomly divided into 4 groups: A group without OA and radiotherapy,B group with OA alone,C group with radiotherapy alone,D group with OA and radiotherapy. 18F-FDG PET/CT imaging were performed before treatment and 24 h, 7day after treatment for each group. The SUVmax of tumors were calculated in all rats.All rats were sacrificed after PET/CT imaging for HE and immunohistochemistry staining. Paired-t test,one—way analysis of variance,and Spearman correlation analysis were performed to analyze the data using SPSS 13.0.Result There were no significant statistical differences in the SUVmax value between the four group(SUVmax A was 5.252±0.536, SUVmax B was 5.261±0.544, SUVmax C was 5.273±0.520, SUVmax D was 5.232±0.507) before treatment(F=0.008,P=0.99).At 24 h post-treatment, the SUVmax value of C and D group(4.766±0.511,4.403±0.486)decreased siginificantly(t C=14.788,t D=13.366, P ≤ 0.01), while A and B group(5.680±0.635,5.763±0.689) raised significantly(t A=-11.578,t B=-8.651,P≤0.01)(F=10.550,p<0.01).However, there was no significant statistical difference between C and D group(t=1.453,p=0.168).At 7 day post-treatment, the SUVmax value of C and D group(t C=9.750,t D=10.530,P≤0.01)decreased siginificantly,while A and B group(t A=-35.353,t B=-6.884,P≤0.01) raised significantly(F=97.691,P<0.01). Group D decreased more obviously compared with group C(t=5.329,P<0.01).Less tumor cells and more necrosis area were seen in D group compared with other groups by HE staining. The expression of GLUT-1 was lower in D group than other groups were observed by immunohistochemistry staining and the expression of HIF-1α was also lower in D group than other group(F=39.555, F=122.632;P<0.001).Both of the expression of GLUT-1 and HIF-1α were positively correlated SUVmax values(r=0.676,r2=0.457,P<0.01;r=0.853,r2=0.727,P<0.01).The expression of GLUT-1 was also positively correlated with the expression of HIF-1α.Conclusion 18F-FDG PET/CT can evaluate the radiosensitizing effect of OA in vivo, and the radiosensitization of OA may result from the down regulation expression of the HIF-1α. 18F-FDG PET/CT imaging has a certain application value in the evaluation of early curative effect in C6 rat gliomas model after rasitherapy. |
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