Rapida Induzione di Cancri Mammari Con 3-Metilcolantrene e Progesterone Nel Ratto

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Abstract
Sprague-Dawley rats, castrated (20) and intact (20) were given orally 10 mg 3-methylcholanthrene 6 times a week for 50 days. Half of the ovariectomized and half of the non-ovariectomized animals were additionally and simultaneously injected with 4 mg of progesterone intramuscularly. All the rats under experiment developed multiple mammary tumours (adenocarcinomas), except for 4 out of the ten animals castrated and treated with 3-methylcholanthrene. The earliest occurrence was observed in the intact rats treated with 3-methylcholanthrene and progesterone (average time of occurrence of the neoplasms: 40th day of treatment). The mammary glands of the castrated rats given 3-methylcholanthrene were less atrophic than those of the corresponding controls. Mammary proliferations, of the dioestrus type, were observed in the ovariectomized rats treated with 3-methylcholanthrene and progesterone, and in tre normal rats treated with 3-methylcholanthrene only. In the non-ovariectomized rats, the concomitant administration of 3-methylcholanthrene and progesterone brought about changes similar to those of the first day's pregnancy. The present experiment shows that 3-methylcholanthrene behaves like an oestrogen in stimulating the mammary gland and in inducing breast cancers in the rat. Progesterone acts concomitantly with 3-methylcholanthrene and enhances its activity.