Gandilhon P, Melancon R, Djiane J, Kelly P A
J Natl Cancer Inst. 1982 Aug;69(2):447-51.
Prolonged exposure to retinyl acetate (RA) in the diet inhibits the development of 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary cancers in rats. The effectiveness of RA was examined when given 6 months after the administration of DMBA. Non-inbred female Sprague-Dawley rats with DMBA-induced mammary tumors were divided into 3 groups and treated for 4 weeks as follows: Group 1 served as controls, group 2 was ovariectomized, and group 3 received 328 mg RA/kg diet. Ovariectomy (OVX) markedly reduced both the number and size of the tumors. RA administration failed to induce any significant regression in tumor number but significantly retarded tumor growth when compared to tumor growth in group 1 controls. The levels of estradiol, progestin, and prolactin (PRL) receptors were significantly reduced after OVX, whereas only the levels of PRL receptors declined significantly after RA administration. Circulating progesterone concentrations were not affected in the RA-treated group but the plasma PRL level was significantly increased. The present studies show that if treatment with RA is delayed until 6 months after carcinogen administration, the protective effect of RA can still be observed although its effectiveness is less dramatic than when it is administered earlier.
饮食中长期接触醋酸视黄酯（RA）可抑制7,12-二甲基苯并[a]蒽（DMBA）诱导的大鼠乳腺癌的发生。在给予DMBA 6个月后给予RA，检测其有效性。将患有DMBA诱导的乳腺肿瘤的非近交系雌性Sprague-Dawley大鼠分为3组，并进行如下4周的治疗：第1组作为对照组，第2组进行卵巢切除术，第3组接受328 mg RA/kg饮食。卵巢切除术（OVX）显著减少了肿瘤的数量和大小。与第1组对照组的肿瘤生长相比，给予RA未能使肿瘤数量出现任何显著的消退，但显著延缓了肿瘤生长。OVX后，雌二醇、孕激素和催乳素（PRL）受体水平显著降低，而给予RA后仅PRL受体水平显著下降。RA治疗组的循环孕酮浓度未受影响，但血浆PRL水平显著升高。目前的研究表明，如果将RA治疗推迟到给予致癌物6个月后，仍可观察到RA的保护作用，尽管其效果不如早期给药时显著。
