| Subject To observe the characteristics of 18F-fluoromisonidazol positron emission tomography with computed tomography(18F-FMISO PET/CT)imaging in subcutaneous C6 rat glioma model of SD rat before and after radiotherapy.To evaluate the radiosensitizing effect of ursolic acid(UA) in C6 rat glioma modeland to prove the value of 18F-FMISO PET/CT inevaluating the radiosensitivity enhancement of tumors.Methods 32 subcutaneous C6 glioma model of SD rats were randomly divided into A、B、C and D groups(8 rats in each group),A was the control group without UA or radiotherapy, B was experiment group with UA only, C was experiment group with radiotherapy only and D was experiment group with UA combined radiotherapy.18F-FMISO PET/CT imaging was performed before radiotherapy and 24 h after radiotherapy respectively.The SUVmax values of tumor(SUVmax-T) and the lateral spinal muscle(SUVmax-M) were measured,the ratios of(SUVmax-T)/(SUVmax-M)(T/M)were calculated in all groups.All the rats were sacrificed after PET/CT imaging,then the HE staining and immunohistochemistry staining with HIF-1α were obtained. The paired-t test,one-way analysis of variance,and Spearman correlation analysis were performed to analyze the data using SPSS 16.0.Results(1)Before radiotherapy, the T/Mvalues in A、B、C and D groups were 1.47±0.20、1.47±0.19、1.48±0.21、1.47±0.20 respectively,while the values after radiotherapy were 2.84±0.61、2.69±0.80、1.78±0.34、1.12±0.74 in the 4 groups respectively.(2)24h after radiotherapy,the T/Mvalues in A groupand B group both increased compared with the values before radiotherapy and the differences were statistically significant(group A:t=5.74,P<0.01; group B:t=4.74,P<0.01). 24 h after radiotherapy,the T/Mvalues in group Cand group D were both lower than that before radiotherapy,and the differences were statistically significant(group C:t=3.71,P<0.01; group D:t=3.35,P<0.01).(3)24h after radiotherapy,the T/M value in group D was significantly lower than that in group C, and there was the a significant statistical difference(P<0.01)(4) By immunohistochemistry staining, the positive expression of HIF-1αwas significantly lower in group D than that in other groups(P<0.01).(5)The T/M value was positively correlated with positive expression of HIF-1α(r=0.78,P<0.01).Conclusion UA has a certain application radiosensitizing effectin subcutaneous C6 rat glioma modle, and 18F-FMISO PET/CT can evaluate the radiosensitizing effect exactly and noninvasively by assessing the hypoxic state in tumor. |
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