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Long-term Behavioral and Reproductive Consequences of Embryonic Exposure to Low-dose Toxicants
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Published on: March 6, 2018

Developmental methoxychlor exposure affects multiple reproductive parameters and ovarian folliculogenesis and gene

AnnMarie E Armenti1, Aparna Mahakali Zama, Lisa Passantino

  • 1Department of Animal Sciences School of Environmental and Biological Sciences Rutgers, The State 84 Lipman Drive University of New Jersey New Brunswick, NJ 08901-8525, USA.

Toxicology and Applied Pharmacology
|October 14, 2008
PubMed

Insights

Developmental exposure to methoxychlor (MXC), an organochlorine pesticide, causes adult ovarian dysfunction, reduced fertility, and premature aging in rats. This pesticide disrupts key ovarian hormones and follicle development.

Area of Science:

  • Reproductive toxicology
  • Endocrinology
  • Developmental biology

Background:

  • Methoxychlor (MXC) is an organochlorine pesticide with known endocrine-disrupting properties.
  • Transient developmental exposure to environmental toxins can lead to long-term reproductive health issues.

Purpose of the Study:

  • To investigate the effects of transient developmental exposure to methoxychlor on adult ovarian function in Fischer rats.
  • To determine if MXC exposure during a critical developmental window impacts reproductive parameters, hormone levels, and ovarian molecular markers.

Main Methods:

  • Fischer rats were exposed to low (20 microg/kg/day) or high (100 mg/kg/day) doses of MXC from day 19 post coitum to day 7 postpartum.
  • Reproductive parameters, serum hormone levels, ovarian morphology, and molecular markers were assessed from prepubertal through adult stages.
  • Techniques included estrous cyclicity monitoring, superovulation testing, hormone assays, follicular composition analysis, and immunohistochemistry.

Main Results:

  • High-dose MXC accelerated puberty, reduced litter size, and induced irregular estrous cycles in adult rats.
  • MXC exposure decreased superovulatory response and altered ovarian follicular composition, increasing preantral/early antral follicles and reducing corpora lutea.
  • Key molecular changes included reduced estrogen receptor beta, upregulated anti-Mullerian hormone, reduced luteinizing hormone receptor, and downregulated cytochrome P450 side-chain cleavage.

Conclusions:

  • Developmental exposure to methoxychlor causes significant ovarian dysfunction, reduced fertility, and signs of premature ovarian aging in rats.
  • These effects are likely mediated by alterations in ovarian gene expression, folliculogenesis, and hormonal signaling pathways.
  • The findings highlight the potential risks of environmental endocrine disruptors during critical developmental periods.

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