Vulnerable Periods for the Mouse Mammary Gland: Comparison of the Effects of Ethinyl Estradiol Exposures during Two Early Stages of Development
- Presenter
- Zachary William Clark
- Campus
- UMass Amherst
- Sponsor
- Laura N. Vandenberg, Department of Environmental Health Sciences, UMass Amherst
- Schedule
- Session 1, 10:30 AM - 11:15 AM [Schedule by Time][Poster Grid for Time/Location]
- Location
- Poster Board A36, Campus Center Auditorium, Row 2 (A21-A40) [Poster Location Map]
- Abstract
17α-ethinyl estradiol (EE2; e.g. birth control) serves as a positive control for estrogen-active chemicals, and its effects on hormone-sensitive organs (mammary gland) have not been fully explored. This study compared the effects of EE2 when exposures occur at one of two exposure periods: gestation + the juvenile period/only the juvenile period. Female mice were exposed to EE2 starting at pregnancy day 7, or on lactational day 1 and exposures continued until the litters were weaned. The pups were exposed during gestation + juvenile period, or the juvenile period alone. The mammary gland was evaluated in both offspring sexes at two life stages: weaning (PND21) and puberty (PND32). Other hormone-sensitive outcomes were evaluated. At PND21, females exposed to EE2 during gestation + the juvenile period, or the juvenile period alone, decreased mammary ductal area, but only exposure during gestation + the juvenile period altered TEB parameters. EE2 exposure increased uterine weight and increased the percentage of pups with open vagina at PND21. Morphology of the male mammary gland at PND21 was not altered. At puberty, there were no effects of EE2 on the morphology of the female mammary gland. Exposure to EE2 during gestation+lactation increased ductal area, branching points, and number of TEB-like structures in the mammary glands of the male at PND32. Prior studies show that exposure to EE2 during gestation + lactation alter morphology of the mouse mammary gland. We demonstrate that early life exposures during the lactational period can also alter mammary gland morphology to some effect.
- Keywords
- Ethinyl-estradiol, Mammary gland, Endocrinology, Public Health
- Research Area
- Environmental Science and Sustainability
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