Department of Pathology II, Kansai Medical University, Moriguchi, Osaka 570-8506, Japan.
In Vivo. 2011 Mar-Apr;25(2):149-56.
To study the effects of short-term pregnancy hormone treatment, estradiol and progesterone or prolactin, against pre-existing mammary cancer as well as newly developing mammary cancer by using the N-methyl-N-nitrosourea (MNU)-induced rat mammary cancer model.
Three-week-old female Lewis rats (n=103) received an intraperitoneal injection of 50 mg/kg MNU. Nine weeks after the MNU injection, the rats received 3 weeks of hormone treatments, consisting of a subcutaneously implanted 0.5 mg estradiol- and 32.5 mg progesterone-containing pellet (E/P group, n=35) or four subcutaneous injections per week of 5 mg/kg perphenazine (PPZ group, n=38), a prolactin-releasing agent. The remaining rats did not receive hormones (control group, n=30). At 12 weeks of age (when the hormone treatments were started), 6 rats in each of the three groups had palpable tumors. These rats were sacrificed at 15 weeks of age, and the remaining rats were sacrificed at 19 weeks of age. The entire mammary glands and the palpable mammary tumors were histologically examined, and the development and growth of mammary tumors was compared.
Newly developing mammary tumors were suppressed and pre-existing ones regressed in the E/P group, while the development and growth of both newly developing cancers and pre-existing tumors were accelerated in the PPZ group as compared with the control group.
Short-term, pregnancy levels of estradiol and progesterone (but not prolactin) may be the most effective treatment against MNU-induced mammary tumors in female Lewis rats.
使用 N-甲基-N-亚硝脲（MNU）诱导的大鼠乳腺癌模型，研究短期妊娠激素治疗（雌二醇和孕酮或催乳素）对已存在的乳腺癌和新发生的乳腺癌的影响。
3 周龄雌性 Lewis 大鼠（n=103）接受 50mg/kg MNU 腹腔注射。MNU 注射后 9 周，大鼠接受 3 周的激素治疗，包括皮下植入 0.5mg 雌二醇和 32.5mg 孕酮的微球（E/P 组，n=35）或每周皮下注射 5mg/kg 丙嗪（PPZ 组，n=38），一种催乳素释放剂。其余大鼠未接受激素（对照组，n=30）。在 12 周龄（开始激素治疗时），每组 6 只大鼠有可触及的肿瘤。这些大鼠在 15 周龄时被处死，其余大鼠在 19 周龄时被处死。对整个乳腺和可触及的乳腺肿瘤进行组织学检查，并比较乳腺肿瘤的发展和生长。
E/P 组中新发乳腺癌得到抑制，已存在的乳腺癌消退，而 PPZ 组中新发癌症和已存在肿瘤的发展和生长均较对照组加速。
短期妊娠水平的雌二醇和孕酮（而非催乳素）可能是治疗雌性 Lewis 大鼠 MNU 诱导乳腺癌最有效的方法。
