Research article - Peer-reviewed, 2002
Thyroid gland function in ovariectomized ewes exposed to phytoestrogens
Madej, Andrzej; Persson, Elisabeth; Lundh, Torbjörn; Ridderstråle, YvonneAbstract
Phytoestrogens are by definition plant-derived substances that are able to activate the mammalian oestrogen receptors. We examined the possible effects of phytoestrogens on the secretion of thyroid hormones as well as on the immunoreactivity to oestrogen receptor alpha (ERalpha) in the thyroid glands of ovariectomized ewes. Eight ovariectomized ewes were fed 3.5 kg of 100% red clover silage for 14 days. Blood samples were collected before and on day 14 of exposure to phytoestrogens. After 5 months, four of the ewes were re-exposed to red clover silage as described above and the other four served as controls. Blood samples were collected as above. All ewes were slaughtered at the end of the experiment and the thyroid glands were weighed and examined for macroscopical changes. Tissue samples were taken for immunohistochemistry and image analysis. Ewes exposed to red clover silage had significantly higher plasma concentrations of total T-3 and free T-3 than ewes fed hay. The cross-section area of thyroid follicles tended to be larger in ewes fed red clover silage than in the control animals. ERalpha immunoreactivity was stronger in thyroid glands from ewes exposed to phytoestrogens than in ewes fed hay. In conclusion, daily ingestion of 81-95 mg phytoestrogens per kg body weight for 14 days stimulated secretion of thyroid hormones and tended to increase follicle size and ERalpha immunoreactivity of thyroid glands of ovariectomized ewes. (C) 2002 Elsevier Science B.V. All rights reserved.Keywords
thyroid gland function; phytoestrogensPublished in
Journal of Chromatography B2002, volume: 777, number: 1-2, pages: 281-287
Publisher: ELSEVIER SCIENCE BV PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Authors' information
Madej, Andrzej
Swedish University of Agricultural Sciences, Department of Animal Physiology
Swedish University of Agricultural Sciences, Department of Anatomy and Histology
Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management
Ridderstråle, Yvonne
Swedish University of Agricultural Sciences, Department of Animal Physiology
UKÄ Subject classification
Animal and Dairy Science
Publication Identifiers
DOI: https://doi.org/10.1016/S1570-0232(02)00082-X
URI (permanent link to this page)
https://res.slu.se/id/publ/38863