Effects of chronic estradiol treatment on the thyroid gland structure and function of ovariectomized rats

Abdel-Dayem, Menna Mohamed; Elgendy, Mohamed

doi:10.1186/1756-0500-2-173

Cited by 26 publications

(12 citation statements)

References 27 publications

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“…A post-ovariectomy drop in T4 has also been described in rodents, a response that is reversed by exogenous estradiol administration. 35,36 Although there are no studies in humans directly addressing the effects of surgical menopause on thyroid function, a dietary isoflavone supplementation study in oophorectomized women found alterations in free T3 concentrations across time (increased at 6 weeks, decreased at 12 weeks). 37 Isoflavone studies done in naturally menopausal women have not shown significant changes in thyroid hormones.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

“…All are reversed by physiologic doses of estradiol. 35,36 Isoflavones may act similarly, possibly via thyroidal ER binding. 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.…”

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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“…Cost‐effective treatment technologies, based on the particle theory, will need to be assessed for their capability of removing EDCs to ensure a safe drinking water supply. Chronic amounts of estradiol may lead to hyperactivity, so they should be decreased to avoid its undesirable stimulatory effect on the thyroid structure and function 46…”

Section: Discussionmentioning

confidence: 99%

Characterization of molecularly imprinted and nonimprinted polymer submicron particles specifically tailored for removal of trace 17β‐estradiol in water treatment

Lai

Maleki

2010

J of Applied Polymer Sci

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This study investigated the potential use of molecularly imprinted polymer (MIP) submicron particles for the selective removal of trace 17b-estradiol (E2) in water treatment. Methacrylate-based MIP submicron particles were synthesized, in a one-step suspension polymerization procedure, using ethylene glycol dimethacrylate (EGDMA) as the cross-linker. After template removal, the particles could be used as a smart material for specific binding of E2. The submicron size of MIP particles facilitated uniform dispersion in water for up to 17 days. These particles were meritorious in mass transfer behavior, allowing phase partitioning of E2 molecules in water during a short treatment time. After 1-mL water samples of different E2 concentrations were treated with 20 mg of MIP particles for 2 min, recovery percentages as high as 97% 6 3% were achieved. The specific binding capacity of these MIP particles was determined to be 15 mg E2/g. Nonimprinted polymer nanoparticles were also evaluated for nonspecific binding of E2, using 0.5 mg in 1 mL of water, to attain 64% 6 3% efficiency in 3 min towards general water treatment. A simple capillary electrophoresis method was successfully developed for the characterization of MIP and NIP particles. Apparently the less negative the electrophoretic mobility, the higher binding efficiency and faster binding kinetics the particles would exhibit with E2 due to less hindered Brownian diffusion.

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“…The s.c. route of administration was chosen to precisely regulate the dosage of soy phytoestrogens and to avoid metabolism of dietary daidzein to equol (by intestinal microflora), which has stronger estrogenic properties than both G and D [23]. The applied dose of estradiol is equivalent to the dose commonly used in clinical practice for estrogen replacement in postmenopausal women and was used in previous experimental designs [19,24]. Estradiol was dissolved in sterile olive oil, and hence females of the appropriate control group (CE) received the sterile olive oil only.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the precise aim of this study was to examine the effects of subcutaneous genistein or daidzein treatment on the immunofluorescence characteristics of pituitary gonadotropic and lactotropic cells, on the ovarian follicular development as well as on anti-oxidative system operativeness in the ovaries of middle-aged female Wistar rats. We also aimed to make an objective and critical parallel between these effects and the effects of estradiol, commonly used in the prevention and treatment of menopausal symptoms [18,19].…”

Section: Introductionmentioning

confidence: 99%

Effects of soy phytoestrogens on pituitary-ovarian function in middle-aged female rats

et al. 2015

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The aim of this study was to assess the effects of genistein (G) and daidzein (D) on the histological, hormonal, and functional parameters of the pituitary-ovarian axis in middle-aged female rats, and to compare these effects with the effects of estradiol (E), commonly used in the prevention and treatment of menopausal symptoms. Middle-aged (12 month old) Wistar female rats subcutaneously received 35 mg/kg of G, or 35 mg/kg of D, or 0.625 mg/kg of E every day for 4 weeks. Each of the treated groups had a corresponding control group. An intact control group was also established. G and D did not change the intracellular protein content within gonadotropic and lactotropic cells, but vacuolization was observed in all the cell types. In contrast, E caused an inhibition of gonadotropic and stimulation of lactotropic cells. Also, ovaries of middle-aged female rats exposed to G or D have more healthy primordial and primary follicles and less atretic follicles. E treatment in the ovaries had a mostly negative effect, which is reflected by the increased number of atretic follicles in all tested classes. G and D provoked decrease in CuZnSOD and CAT activity, while E treatment increased MnSOD and decreased CuZnSOD and GSHPx activity. All the treatments increased serum estradiol and decreased testosterone levels, while D and E increased the serum progesterone level. In conclusion, soy phytoestrogens exhibited beneficial effects on pituitary-ovarian function in middle-aged female rats, as compared to estradiol.

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Effects of chronic estradiol treatment on the thyroid gland structure and function of ovariectomized rats

Cited by 26 publications

References 27 publications

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

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

Characterization of molecularly imprinted and nonimprinted polymer submicron particles specifically tailored for removal of trace 17β‐estradiol in water treatment

Effects of soy phytoestrogens on pituitary-ovarian function in middle-aged female rats

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