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 not induce any changes in uterine weight or estrous cycle but led to the decrease of estradiol (E2) concentration in uterine tissue (especially in adult rats or in young rats after 3 months of experiment). No signs of aneuploidy were found in uteruses of animals-"smokers" though proliferation index and percentage of cells in S-phase were increased (according to flow cytometry data) by 3 weeks and decreased by 3 months of experiment. The data obtained support previously made assumption pointing to phasic character of changes 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 promotional to genotoxic one.