中文摘要：

[目的]研究苯肾上腺素对放射损伤早期大鼠颌下腺MHCⅠ类分子表达的影响。[方法]Wistar大鼠27只,随机分为空白对照组、单纯照射组及照射给药组（腹腔注射苯肾上腺素5 mg/kg,2次/d）,以直线加速器对大鼠颌下腺区域行20 Gy照射。照射后7 d取颌下腺组织,采用免疫组织化学法检测颌下腺MHCⅠ类分子的定位与表达;半定量逆转录聚合酶链法（reverse transcription-polymerase chain reaction,RT-PCR）检测颌下腺MHCⅠmRNA的表达。[结果]免疫组织化学结果显示：MHCⅠ类分子表达在空白对照组主要在颌下腺腺泡细胞及导管细胞的胞浆和胞膜;单纯照射组在腺泡细胞胞膜及细胞间质的表达较空白对照组增加;而苯肾上腺素连续给药组在腺泡细胞膜及间质的表达较单纯照射组显著减少。RT-PCR结果显示：单纯照射组MHCⅠmRNA的表达较空白对照组增加了45.85%（P〈0.05）,而苯肾上腺素连续给药组MHCⅠmRNA的表达较单纯照射组减少了33.88%（P〈0.05）。[结论]苯肾上腺素能够下调放射线照射损伤所致大鼠颌下腺MHCⅠ类分子的表达。

英文摘要：

[Objective]To investigate the effect of phenylephrine on the expression of MHC classⅠin irradiated submandibular gland in rat during the early stage.[Methods]Wistar rats were randomly divided into three groups： the control group,the simple irradiated group and the irradiated group with phenylephrine treatment（phenylephrine（5 mg/kg） was intraperitoneally injected after irradiation,twice per day）,20 Gy X-ray irradiation was delivered to the submandibular region by a medical linear accelerator.The submandibular glands were removed at 7 d.The distribution and expression of MHC classⅠwere detected by immunohistochemistry,and the expression of MHC Ⅰ mRNA was determined by reverse transcription polymerase chain reaction（RT-PCR）.[Results]The distribution of MHC classⅠwas mainly located in the cytoplasm and cytomembrane of both acinar and ductal cells in the control group,was increased in the cytomembrane of acinar cells and mesenchyme in the simple irradiated group.Expression of the protein was markedly decreased in the irradiated group with phenylephrine treatment.Also,the results from RT-PCR demonstrated that the expression of MHC Ⅰ mRNA was up-regulated 45.85%（P0.05） in the simple irradiated group compared with the control group,but was down-regulated 33.88%（P0.05） in the irradiated group with phenylephrine treatment compared with the simple irradiated group.[Conclusion]The expression of MHC classⅠin the rat submandibular gland could be decreased by phenylephrine treatment after irradiation during the early stage.