Effects of chronic exposure to estradiol on ovarian cyclicity in C57BL/6J mice: Potentiation at low doses and only partial suppression at high doses

H. Jesionowska, K. Karelus, J. F. Nelson

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Long-term exposure to ovarian hormones contributes to age-related changes in estrous cyclicity in rodents. Estrogens are implicated in this process, but the concentration of estrogen required to exert these effects is not well established. Also, although estrogens are presumed to alter vaginal cyclicity by affecting the hypothalamic-pituitary axis, they may also impair the ability of the vaginal epithelium to cornify. To address these issues, young and middle-aged ovariectomized (ovx) C57BL/6J mice were exposed for 7-10 wk to plasma levels of estradiol (E2) at one of three ranges (30-40, 50-80, or 120-160 pg/ml). Ovaries from young mice were then transplanted under the renal capsule, and vaginal cyclicity was monitored for 4 mo. Mice exposed to the lowest level of E2 not only failed to stop cycling, but had a higher monthly frequency of estrous cycles than did controls (nearly 1 extra cycle/mo). Mice exposed to the intermediate level of E2 showed no impairment in cyclicity. Although mice exposed to the highest concentrations of E2 showed no vaginal cyclicity, they continued to ovulate as evidenced by fresh, albeit reduced, numbers of corpora lutea. These results indicate that, in ovx mice, (1) chronic exposure to relatively low concentrations of E2 potentiates cyclicity, (2) very high levels of E2 are required to induce acyclicity, and (3) this acyclicity reflects vaginal as well as neuroendocrine alterations. The results also indicate that vaginal acyclicity may be a poor indicator of ovulatory acyclicity in mice that have been chronically exposed to E2.

Original languageEnglish (US)
Pages (from-to)312-317
Number of pages6
JournalBiology of reproduction
Volume43
Issue number2
DOIs
StatePublished - Aug 10 1990
Externally publishedYes

ASJC Scopus subject areas

  • Reproductive Medicine
  • Cell Biology

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