Study of tobacco smoke influence on content of estrogens and DNA flow cytometry data in uterine tissue of rats of different age

Female rats aged 2.5-3 months ("young") and 6 months ("adult") were or were not exposed to the influence of tobacco smoke (mainstream cigarette smoke, 2 hrs/day during 3 weeks or 3 months). Treatment with tobacco smoke did no t induce any changes in uterine weight or estrous cycle but led to the decr ease of estradiol (E-2) concentration in uterine tissue (especially in adul t rats or in young rats after 3 months of experiment). No signs of aneuploi dy were found in uteruses of animals-"smokers" though proliferation index a nd percentage of cells in S-phase were increased (according to flow cytomet ry data) by 3 weeks and decreased by 3 months of experiment. The data obtai ned support previously made assumption pointing to phasic character of chan ges in reproductive system under the influence of tobacco smoke and may be used for further confirmation of the concept explaining the role of smoking in the shift of hormonal (estrogen-induced) carcinogenesis type from promo tional to genotoxic one.