Parous rats regain high susceptibility to chemically induced mammary cancer after treatment with various mammotropic hormones.
Parous rats regain high susceptibility to chemically induced mammary cancer after treatment with various mammotropic hormones.
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经产大鼠在用各种促乳腺激素治疗后，对化学诱发的乳腺癌恢复了高度的易感性。
DOI：
10.1093/carcin/22.7.1027
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发表时间：
2001
期刊：
影响因子：
4.7
通讯作者：
Talamantes,F
中科院分区：
文献类型：
--
作者：
Thordarson,G;VanHorn,K;Guzman,RC;Nandi,S;Talamantes,F
在人类和大鼠中的产次提供了显著的保护，防止乳腺肿瘤的发展。本研究旨在探讨促乳激素对甲基亚硝基脲（MNU）诱导的大鼠乳腺癌发生的影响。用17β-雌二醇（E_2）、孕酮（P_4）和甲状腺素（T_4）单独或联合治疗经产大鼠。E2（20 μg/60天）和P4（20 mg/60天）通过硅胶管给药，T4在饮用水中给药（3 μg T4/ml）。激素治疗在MNU注射前7天开始，持续33周。每周触诊动物以进行肿瘤检测。在治疗7天后，即MNU注射时间，评估激素治疗对E2、P4、生长激素（GH）、催乳素（PRL）、T4和胰岛素样生长因子-I（IGF-I）循环浓度的影响。用E2处理的动物具有显著升高的GH、PRL和P4的循环浓度，并且该组中E2的血清水平比其他动物组更一致。P4处理引起血清中P4浓度升高，但不影响其他激素的循环水平。在MNU注射时，在单独用E2或与P4和T4一起处理的动物组中以及在单独用P4处理的动物中，乳腺的增殖升高，但在未处理的经产大鼠中乳腺分化最大，在单独用E2或与P4和T4一起处理的动物中分化最小。在未接受任何激素治疗的经产大鼠中，乳腺肿瘤发生率为10%。单独使用E2或P4治疗显著增加了经产动物的易感性，分别为67%和50.0%;肿瘤发生率与未治疗的AMV大鼠相似（64%）。E2 + P4治疗的经产大鼠肿瘤发生率高于90%。T4给药不影响乳腺癌发生。
Parity in humans and rats provides significant protection against mammary tumor development. This study was carried out to investigate whether treatment of parous rats with mammotropic hormones would affect methyl-nitrosourea (MNU)-induced mammary carcinogenesis. Parous rats were treated with 17β-estradiol (E2), progesterone (P4) and thyroxine (T4) alone or in combination. E2 (20 μg/60 days) and P4 (20 mg/60 days) were administered by silastic tubing and T4 in the drinking water (3 μg T4/ml). Hormonal treatments commenced 7 days before MNU injection and continued for 33 weeks. Animals were palpated weekly for tumor detection. The effects of the hormonal treatments on the circulating concentrations of E2, P4, growth hormone (GH), prolactin (PRL), T4 and insulin-like growth factor-I (IGF-I) after 7 days of treatment, the time of MNU injection, was assessed. Animals treated with E2 had significantly elevated circulation concentrations of GH, PRL and P4, and serum levels of E2 were more consistent in this group than in the other animal groups. P4 treatment caused elevation in P4 concentration in serum but did not affect the circulating levels of other hormones. The proliferation of the mammary gland at the time of MNU injection was elevated in animal groups treated with E2 either alone or with P4 and T4 and in animals treated with P4 alone, but the mammary gland was most differentiated in untreated parous rats and least in animals treated with E2 either alone or with P4 and T4. Mammary tumor incidence was 10% in parous rats that did not receive any hormonal treatment. Treatments with E2 or P4 alone significantly increased the susceptibility of parous animals to 67 and 50.0%, respectively; a tumor incidence similar to that of untreated AMV rats (64%). Parous rats treated with E2 plus P4 had tumor incidence higher than 90%. T4 administered did not affect mammary carcinogenesis.