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This Article Full Text Full Text (PDF) All Versions of this Article: 67/6/1734    most recent biolreprod.101.002006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wright, C. Articles by Sweeney, T. Search for Related Content PubMed PubMed Citation Articles by Wright, C. Articles by Sweeney, T. Agricola Articles by Wright, C. Articles by Sweeney, T.

Effect of Maternal Exposure to the Environmental Estrogen, Octylphenol, During Fetal and/or Postnatal Life on Onset of Puberty, Endocrine Status, and Ovarian Follicular Dynamics in Ewe Lambs

^a Faculties of Agriculture ^b Veterinary Medicine, Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland ^c Department of Veterinary Preclinical Studies, University of Glasgow Veterinary School,Glasgow G61 1QH, United Kingdom

Octylphenol (OP) is one of a number of compounds found in the environment that has estrogen-mimicking actions in vivo. Our objective was to determine if maternal exposure to octylphenol during fetal and/or postnatal life would affect the onset of puberty, endocrine status, and subsequent ovarian follicular dynamics of ewe lambs. Lambs were born in March to ewes that received twice weekly s.c. injections of octylphenol (1000 µg/kg/day) from Day 70 of gestation to weaning (n = 6); Day 70 of gestation to birth (n = 3); birth to weaning (n = 5; gestation = 145 days); or corn oil from Day 70 of gestation to weaning (control; n = 5). Blood samples were collected twice weekly to determine progesterone and FSH concentrations from 20 wk of age throughout the first breeding season. Onset of puberty and interestrous intervals were determined from 20 wk of age by twice daily observation for estrus in the presence of a vasectomized ram. During January the ovaries of each lamb were examined using transrectal ultrasonography from the day of estrus for 15 days. Blood samples were collected every 8 h to examine FSH concentrations and every 2 h to detect the preovulatory gonadotropin surge throughout this estrous cycle. The onset of puberty and first progesterone rise was advanced and the FSH preovulatory surge was elevated for longer in the OP-treated lambs compared with the control lambs (P < 0.05). Interestrous intervals, FSH profiles, and ovarian follicular dynamics were not affected (P > 0.05) by exposure to octylphenol. In conclusion, octylphenol exposure advanced the onset of puberty but it did not disrupt FSH concentrations or the dynamics of ovarian follicular growth.

¹ Correspondence: Torres Sweeney, Department of Animal Husbandry and Production, Faculty of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. FAX: 353 1 6600883; tsweeney{at}vetmed.ucd.ie

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