Abstract: Objective: The present study was designed to examine the expression levels of Rad50 in the salivary gland of Wistar rats after irradiation． Methods: 60 Wistar rats were randomly distributed into 6 groups: five groups  were irradiated for 3，6，9，12，and 15 Gy doses of 60Co γ-ray respectively,  and a sham irradiation group as control. The rats were sacrificed at 2-hour after irradiation. Histopathological changes in the parotid and submandibular glands  were observed by  transmission electron microscopy (TEM)． Rad50 mRNA levels were evaluated by RT-PCR. Rad50 protein levels were evaluated by immunohistochemistry method． Statistical analysis were performed by means of SPSS 13.0 software. The experimental data were expressed as x±s; comparisons were made by factorial ANOVA. P<0.05 were considered significant. Results： Expressions of Rad50 mRNA and protein level in  parotid glands and submandibular glands after irradiation were significantly higher than those in normal control salivary glands (P<0.05). The expression level of Rad50 in each irradiated groups appeared differently but did not reach statistical significance (P>0.05). Ultra structures of those irradiated salivary gland cells showed injured variations at some degree in a dose-dependent manner as demonstrated by the transmission electron microscope. Conclusion： γ-ray  radiation may affect expression of Rad50 mRNA and protein levels  in the parotid and submandibular glands, but the expression intensity does not manifested in a radiation dose-dependent manner. Our study demonstrate that the limitation of expression potential of Rad50 in the salivary glands, may be  related to the radiation unsensitivities of the salivary glands.

Key words: Rad50, irradiation, parotid gland, submandibular gland, rat

摘要：   目的： 检测Rad50在放射后大鼠涎腺组织中的表达水平。方法： 选用 60只Wistar大白鼠，随机分成6组，每组10只。分为对照组(未照射)、3 Gy组、6 Gy组、9 Gy组、12 Gy组、15 Gy组。放射组大白鼠用⁶⁰Co一次性照射后2 h内处死，立即取出其腮腺、下颌下腺组织备用。用电镜观察放射后各组涎腺组织超微结构的变化，用反转录聚合酶链反应 (RT-PCR)检测Rad50基因表达水平的变化，用免疫组织化学法观察其蛋白表达水平的变化。结果： 各放射组涎腺组织中Rad50的表达均高于对照组 (P<0.05)，但不同放射剂量的各放射组之间Rad50的表达无明显差异（P > 0.05）。透射电镜下可见大鼠腮腺、下颌下腺细胞超微结构随着放射剂量的增加，发生较明显改变。结论： 放射可引起涎腺组织Rad50表达水平增高，但其表达水平并未随放射剂量的增加而增高，提示Rad50在涎腺放射损伤修复中的表达水平有限，这可能是涎腺放射敏感性机制之一。 

关键词: Rad50, 放射, 腮腺, 下颌下腺, 鼠

CLC Number: 

•  

• R739.87