Rad50在放射后大鼠涎腺中的表达

Differential Expression of Rad50 in Mouse Salivary Gland Following Irradiation

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。

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 dosedependent 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.