Thyroid gland function in ovariectomized ewes exposed to phytoestrogens

Madej, Andrzej; Persson, Elisabeth; Lundh, Torbjörn; Ridderstråle, Yvonne

doi:10.1016/s1570-0232(02)00082-x

Cited by 24 publications

(18 citation statements)

References 20 publications

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“…This resembles the effect after ingestion of oestrogenic silage, which increases ERa immunoreactivity in the thyroid gland of ovariectomized ewes (Madej et al, 2002). Anderson et al (2002) have demonstrated that the seasonal decline in LH pulse frequency depends on the presence of thyroid hormones occurring in the absence of steroids during spring/ summer in ewes.…”

Section: Discussionmentioning

confidence: 70%

Effects of intracerebroventricular infusion of genistein on gonadotrophin subunit mRNA and immunoreactivity of gonadotrophins and oestrogen receptor-α in the pituitary cells of the anoestrous ewe

Polkowska

Ridderstråle

Wańkowska

et al. 2004

Journal of Chemical Neuroanatomy

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Section: Discussionmentioning

confidence: 70%

Effects of intracerebroventricular infusion of genistein on gonadotrophin subunit mRNA and immunoreactivity of gonadotrophins and oestrogen receptor-α in the pituitary cells of the anoestrous ewe

Polkowska

Ridderstråle

Wańkowska

et al. 2004

Journal of Chemical Neuroanatomy

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“…Thyroid hormone concentrations were observed in ovariectomized ewes fed red clover silage which showed changes in the area of the thyroid follicles and significantly higher concentrations of total T 3 and free T 3 in plasma, however, no differences were observed between the total T 4 and free T 4 . These results suggest that men and women with thyroid conditions should use caution when consuming phytoestrogens (Madej et al, 2002).…”

Section: Adverse Effects Of Phytoestrogensmentioning

confidence: 84%

Phytoestrogens: a review of the present state of research

Ososki

Kennelly

2003

Phytotherapy Research

407

278

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Phytoestrogens are a diverse group of plant-derived compounds that structurally or functionally mimic mammalian estrogens and show potential benefits for human health. The number of articles published on phytoestrogens has risen dramatically in the past couple decades. Further research continues to demonstrate the biological complexity of phytoestrogens, which belong to several different chemical classes and act through diverse mechanisms. This paper discusses the classification of phytoestrogens, methods of identification, their proposed mechanisms of action and botanical sources for phytoestrogens. The effects of phytoestrogens on breast and prostate cancers, cardiovascular disease, menopausal symptoms and osteoporosis will also be examined including research on benefits and risks.

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“…In ovariectomized sheep an isoflavone rich diet results in greater ERα immunoactivity, higher concentrations of T3 and T4, and morphologic changes to the thyroid follicles. 42 In the periphery isoflavones may boost free T4 levels by decreasing TBG. Greater than 99% of plasma T4 is protein bound, TBG being the predominant binding protein.…”

Section: Discussionmentioning

confidence: 99%

Effect of soy isoflavones on thyroid hormones in intact and ovariectomized cynomolgus monkeys (Macaca fascicularis)

Silverstein

Kaplan

Appt³

et al. 2014

Menopause

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Objectives Soy isoflavones are commonly used to alleviate menopause-related symptoms. Menopausal women are at an increased risk for hypothyroidism and there are concerns that isoflavones may be detrimental to thyroid health. The aim of this study was to examine the effects of soy protein and isoflavones on thyroid function and the relationship between thyroid and ovarian function. Methods Adult female cynomolgus monkeys (Macaca fascicularis) were randomized to consume two diets differing only in protein source: casein-lactalbumin (n = 44) or soy protein with isoflavones (n = 41). After 34 months all animals were ovariectomized via laparotomy. Half of the monkeys from each diet treatment group continued to consume their Pre-Ovariectomy treatment phase diet (either SOY [n = 19] or CL [n = 21]) for an additional 34 months. The remaining animals did not continue their diets, and thus were not considered further. Circulating progesterone, triiodothyronine, thyroxine, and thyroid stimulating hormone were measured at baseline. Thyroid hormones were remeasured during each treatment phase. Results Dietary soy increased triiodothyronine in pre-ovariectomized monkeys and prevented a decline in thyroxine following surgical menopause (both p’s < 0.05). Mean progesterone concentrations were positively correlated with triiodothyronine at baseline in pre-ovariectomized monkeys (p < 0.01). Conclusions Progesterone levels and triiodothyronine are positively correlated in macaques. Dietary soy increases triiodothyronine in pre-ovariectomized monkeys and prevents a decline in thyroxine following surgical menopause. The outcomes observed in this study suggest soy protein and isoflavone consumption does not adversely affect and may even preserve thyroid function in postmenopausal women.

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Thyroid gland function in ovariectomized ewes exposed to phytoestrogens

Cited by 24 publications

References 20 publications

Effects of intracerebroventricular infusion of genistein on gonadotrophin subunit mRNA and immunoreactivity of gonadotrophins and oestrogen receptor-α in the pituitary cells of the anoestrous ewe

Effects of intracerebroventricular infusion of genistein on gonadotrophin subunit mRNA and immunoreactivity of gonadotrophins and oestrogen receptor-α in the pituitary cells of the anoestrous ewe

Phytoestrogens: a review of the present state of research

Effect of soy isoflavones on thyroid hormones in intact and ovariectomized cynomolgus monkeys (Macaca fascicularis)

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