Chronic Estradiol Exposure Modulates Thyroid Structure and Decreases T&lt;sub&gt;4&lt;/sub&gt; and T&lt;sub&gt;3&lt;/sub&gt; Serum Levels in Middle-Aged Female Rats

Šošić‐Jurjević, Branka; Filipović, Branko; Milošević, Verica; Nestorović, Nataša; Manojlović‐Stojanoski, Milica; Brkić, Branislava; Sekulić, Milka

doi:10.1159/000083139

Cited by 39 publications

(27 citation statements)

References 33 publications

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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%

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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Section: Methodsmentioning

confidence: 99%

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

et al. 2015

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“…For thyroids, the relative volume density (V V ; %) of the corresponding tissue components, defined as the ratio of this component in a volume unit, the thyroid follicles (epithelium plus colloid), follicular epithelium, interstitium and colloid, were calculated as previously described in detail [25]. The follicular cell activation index (ia) represents the epithelial volume/colloid volume ratio and indicates the reaction of the thyroid gland structure to the blood TSH concentration [26].…”

Section: Animals and Methodsmentioning

confidence: 99%

Central Ghrelin Affects Pituitary-Thyroid Axis: Histomorphological and Hormonal Study in Rats

Šošić‐Jurjević

Stevanović²,

Milošević³

et al. 2008

Neuroendocrinology

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Body weight depends on the balance between energy intake and consumption. An interaction between ghrelin and thyroid function has been reported only in pathophysiological states. We examined whether intracerebroventricular (ICV) administration of ghrelin affects the structure and function of the pituitary-thyroid axis in young adult male rats. Ghrelin (0.3 nmol/5 μl PBS) or an equal volume of PBS were injected every 24 h into the lateral cerebral ventricle for 5 days. Two hours after the last treatment the animals were killed, their pituitaries and thyroids excised and prepared for further histological, immunohistochemical and morphometric investigation. Serum TSH levels were measured by RIA, while the total T₄ and T₃ levels were examined by ECLIA. Ghrelin treatment increased pituitary weight (p < 0.05) when compared to the controls, with no effect on the thyroid weight. Smaller, degranulated TSH-immunopositive cells were noticed within the pituitaries of ghrelin-treated animals; their cellular and nuclear volume as well as the relative volume density of thyrotrophs decreased (p < 0.05) in comparison to the control values. The level of serum TSH was reduced (p < 0.05). In the thyroid parenchyma of ghrelin-treated rats, an increased number of hypofunctioning follicles was noticed, characterized by flattened, weakly Tg-immunoreactive epithelium and colloid distension. The relative volume densities of the follicles and colloid increased (p < 0.05), while the thyroid index of activation rate and the serum level of total T₄ decreased (p < 0.05). In conclusion, centrally applied ghrelin modulated the immunohistomorphometric features of pituitary TSH cells and decreased the level of serum TSH, consequently changing thyroid morphology and function, by reducing the T₄ hormone level in the serum.

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“…Serum E 2 concentration is known to influence not only the level of T 4 -binding globulin (TBG; Surks & Sievert 1995) but also the production of T 3 and T 4 from the thyroid gland (Furlanetto et al 1999, Sosic-Jurjevic et al 2005, Alotaibi et al 2006, Lima et al 2006. Using cultured thyrotroph cell line TaT1 (Yusta et al 1998), we studied the direct effect of E 2 on the TSHb mRNA level.…”

Section: Effect Of E 2 On the Expression Of The Tshb Gene In Thyrotromentioning

confidence: 99%

Inhibition of GATA2-dependent transactivation of the TSHβ gene by ligand-bound estrogen receptor α

Nagayama¹,

Sasaki²,

Matsushita³

et al. 2008

Journal of Endocrinology

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Transcriptional repression of the TSH-specific b subunit (TSHb) gene has been regarded to be specific to thyroid hormone (tri-iodothyronine, T 3 ) and its receptors (TRs) in physiological conditions. However, TSHb mRNA levels in the pituitary were reported to decrease in the administration of pharmacologic doses of estrogen (17-b-estradiol, E 2 ) and increase in E 2 receptor (ER)-a null mice. Here, we investigated the molecular mechanism of inhibition of the TSHb gene expression by E 2 -bound E 2 -estrogen receptor 1 (E 2 -ERa). In kidney-derived CV1 cells, transcriptional activity of the TSHb promoter was stimulated by GATA2 and suppressed by THRBs and ERa in a ligand-dependent fashion. Overexpression of PIT1 diminished the E 2 -ERa-induced inhibition, suggesting that PIT1 may protect GATA2 from E 2 -ERa targeting by forming a stable complex with GATA2. Interacting surfaces between ERa and GATA2 were mapped to the DNA-binding domain (DBD) of ERa and the Zn finger domain of GATA2. E 2 -dependent inhibition requires the ERa amino-terminal domain but not the tertiary structure of the second Zn finger motif in E 2 -ERa-DBD. In the thyrotroph cell line, TaT1, E 2 treatment reduced TSHb mRNA levels measured by the reverse transcription PCR. In the human study, despite similar free thyroxine levels, the serum TSH level was small but significantly higher in post-than premenopausal women who possessed no anti-thyroid antibodies (1 . 90 mU/mlG0 . 13 S.E.M. vs 1 . 47 mU/mlG0 . 12 S.E.M., P!0 . 05). Our findings indicate redundancy between T 3 -TR and E 2 -ERa signaling exists in negative regulation of the TSHb gene.

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Chronic Estradiol Exposure Modulates Thyroid Structure and Decreases T<sub>4</sub> and T<sub>3</sub> Serum Levels in Middle-Aged Female Rats

Cited by 39 publications

References 33 publications

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

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

Central Ghrelin Affects Pituitary-Thyroid Axis: Histomorphological and Hormonal Study in Rats

Inhibition of GATA2-dependent transactivation of the TSHβ gene by ligand-bound estrogen receptor α

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