Previously, we established that mice of the C3H/Sn line, which multiply intensively, develop mammary gland tumors in 100% of cases before the age of 12 months. In virgin mice of this line, tumors occur in no more than 30%. During pregnancy, the level of steroids is higher and obviously this indicates a more intensive activation of mutated genes by steroid hormones than in virgin mice. The role of hormones at more distant stages of development of the body and organs has been revealed. The possibility of preventing the occurrence of tumors is considered in this work.
Mice of the C3H/Sn and BALB/c lines became pregnant at the same time. Synchronously born C3H/Sn and BALB/c mice were given to BALB/c females for nursing. Some of the mice were given per os approximately 1 μl of a solution of estradiol and corticosterone at the dose of 10-9 M/L for 2 weeks.
BALB/c mothers successfully nursed 15 C3H/Sn mice to puberty. After giving birth, the mice were divided into two groups: 1) intact - 7 pcs. 2) 8 pcs received a solution of estradiol and corticosterone (10-9 M/L) for 2 weeks once a day starting from the first day after delivery. No further action was taken on them. Adult mice were observed up to 3 generations. In 1 group of intact mice, mammary gland tumors were detected in 1 mouse out of 7. In the second group, in 6 out of 8. That is, treatment with estrogens in the early postnatal age leads to the manifestation of the effect in the distant future. It seems that the action of steroids can be biphasic: I — activation. II - is more strongly expressed during sexual maturation of animals, when the level of hormones increases. Such a mechanism of action in the case of unmutated genes ensures the development of mammary glands in children when they become adults. When mutated, it contributes to the development of cancer. Translation from laboratory experiments to the clinic can be based on the reverse scheme: strict limiting of the use of steroids with breast milk during the early postpartum period. Theoretically, no negative consequences are expected, except for breast hypoplasia.
The long-term effect of steroids in the early postnatal period on the development of mammary glands in the future state requires further study.
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The author has declared no conflicts of interest.