Inano H, Suzuki K, Ishii-Ohba H, Ikeda K, Wakabayashi K
National Institute of Radiological Sciences, Chibashi, Japan.
Carcinogenesis. 1991 Jun;12(6):1085-90. doi: 10.1093/carcin/12.6.1085.
Pregnant Wistar rats received whole body irradiation with 260 cGy gamma-rays at days 7, 14 and 20 of pregnancy and then were treated with diethylstilbestrol (DES) for 1 year. The highest incidence (92.9%) for tumorigenesis of mammary glands was observed in the rats irradiated in late pregnancy. Histological examination showed that tumors were classified as fibroadenoma and adenocarcinoma. To determine the reasons for specific induction of mammary tumors by irradiation in late pregnancy, hormone concentrations in serum and estrogen receptors in mammary glands during pregnancy were measured. Concentrations of estradiol, progesterone, 11-deoxycorticosterone and placental lactogen at day 20 were higher than at days 7 and/or 14, but no difference was observed in the concentrations of prolactin and thyroid-stimulating hormone during pregnancy. The estrogen receptor in mammary glands at day 20 was indicated to have the highest affinity and the highest binding capacity during pregnancy. Normal mammary glands at day 20 were suggested to have more abundant epithelial cells in the mammary lobes than those at days 7 and 14. The data suggest that the critical requirements for the initiation of tumorigenesis by gamma-rays are dependent upon the differentiated state of mammary glands exposed to various hormones, and that the concentration and persistence of the synthetic estrogen (DES) are necessary for the promotion of tumorigenesis of the irradiated mammary glands.
怀孕的Wistar大鼠在妊娠第7天、14天和20天接受260 cGy的全身γ射线照射，然后用己烯雌酚（DES）治疗1年。在妊娠晚期接受照射的大鼠中观察到乳腺肿瘤发生的最高发生率（92.9%）。组织学检查显示肿瘤分为纤维腺瘤和腺癌。为了确定妊娠晚期照射特异性诱导乳腺肿瘤的原因，测量了妊娠期间血清中的激素浓度和乳腺中的雌激素受体。第20天雌二醇、孕酮、11-脱氧皮质酮和胎盘催乳素的浓度高于第7天和/或第14天，但妊娠期间催乳素和促甲状腺激素的浓度没有差异。第20天乳腺中的雌激素受体在妊娠期间具有最高的亲和力和最高的结合能力。第20天的正常乳腺被认为比第7天和第14天的乳腺叶中有更丰富的上皮细胞。数据表明，γ射线引发肿瘤发生的关键要求取决于暴露于各种激素的乳腺的分化状态，并且合成雌激素（DES）的浓度和持续存在对于促进受照射乳腺的肿瘤发生是必要的。
