Effects of estradiol benzoate on 5'-iodothyronine deiodinase activities in female rat anterior pituitary gland, liver and thyroid gland

Lisboa, Patrícia Cristina; Curty, F. H.; Moreira, R.M.; Pazos‐Moura, Carmen C.

doi:10.1590/s0100-879x1997001200016

Cited by 25 publications

(23 citation statements)

References 17 publications

(15 reference statements)

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“…Our results confirm that serum total T4 concentration is not altered by ovariectomy (Christianson et al 1981, Lisbôa et al 1997, but there is a small significant decrease in serum T3, also reported by Lima et al (2006). The hepatic, renal, thyroid, and pituitary D1 activities were unchanged in ovariectomized rats.…”

Section: Discussionsupporting

confidence: 89%

“…Chen & Walfish (1978) and Lisbôa et al (1997) have reported that estradiol treatment of castrated females promotes an increase in serum TSH, but neither we nor Christianson et al (1981) found a similar increase in serum TSH.…”

Section: Discussioncontrasting

confidence: 70%

“…In contrast to male rats, several reports have shown that ovariectomy or b-estradiol administration does not alter liver D1 activity in female rats (Harris et al 1979, Miyashita et al 1995. However, Lisbôa et al (1997Lisbôa et al ( , 2001 reported that ovariectomy produced a decrease in both liver and pituitary D1 activities and that treatment with estradiol was able to return these activities to control levels and to significantly increase thyroid D1.…”

Section: Introductionmentioning

confidence: 95%

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Sexual dimorphism in thyroid function and type 1 iodothyronine deiodinase activity in pre-pubertal and adult rats

Marassi

Fortunato

Silva

et al. 2007

Journal of Endocrinology

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Iodothyronine deiodinase activities are regulated by sex steroids; however, the mechanisms underlying the reported sexual dimorphism are poorly defined. In the present report, we aimed to investigate whether type 1 deiodinase (D1) sexual dimorphism exists early in sexual development by studying pre-pubertal male (Pm) and female (Pf) rats, as well as adult controls (C) and gonadectomized male and females rats. Adult male Wistar rats were studied 21 days after orchiectomy (Tex), and adult females were studied 21 days after ovariectomy (Ovx), and after estradiol benzoate (Eb) replacement. Serum total triiodothyronine (T3) was higher in pre-pubertal (P) rats than in the matching adults, with no difference between genders, although in adult males T3 was significantly lower than in females. There were no sex or age differences in serum total T4. Serum TSH in pre-pubertal (P) rats was within the adult female range, and both were significantly lower than in adult males. D1 activity in liver was greater in Pm than in Pf. In adult females, liver D1 activity was lower, while in adult males it was higher than in P rats. The same pattern of D1 activity was found in kidney. In thyroid and pituitary, D1 activity was similar in Pm, Pf, and adult females, which were all significantly lower than in the adult male. There were no differences in serum T3 and T4 between C and Tex males, but serum TSH was significantly decreased in Tex rats. Hepatic and renal D1 activities were lower in Tex than in C, but no changes were detected in thyroid and pituitary. In Ovx females, T3 was significantly lower than in the C group. Serum T4 was significantly decreased by estradiol replacement therapy in Ovx rats, in both doses used, whereas TSH was unchanged. Eb replacement increased liver and thyroid D1 activity, but in the kidney, only the highest estradiol dose promoted a significant D1 increase. In conclusion, in males, hepatic and renal D1 activity appears to be significantly influenced by gonadal hormones, in contrast to females, in which only exogenous Eb treatment stimulated D1 activity. The comparison between pre-pubertal and adult rats suggests that serum T3 is not the main regulator of D1 activity, and other factors, besides T3 and gonadal hormones, can modulate D1 activity during murine maturation.

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Section: Discussionsupporting

confidence: 89%

Section: Discussioncontrasting

confidence: 70%

Section: Introductionmentioning

confidence: 95%

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Sexual dimorphism in thyroid function and type 1 iodothyronine deiodinase activity in pre-pubertal and adult rats

Marassi

Fortunato

Silva

et al. 2007

Journal of Endocrinology

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“…Some previous reports indicate that estradiol might regulate thyroid function through a direct action on thyrocytes (34), apart from a possible effect on TSH secretion (35)(36)(37)(38). The administration of estradiol to ovariectomized and hypophysectomized rats leads to a higher thyroid radioiodide uptake (32,39), which supports the hypothesis of a direct effect of estrogen on the thyroid.…”

Section: Estrogensupporting

confidence: 72%

The importance of sodium/iodide symporter (NIS) for thyroid cancer management

Carvalho

Ferreira

2007

Arq Bras Endocrinol Metab

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The thyroid gland has the ability to uptake and concentrate iodide, which is a fundamental step in thyroid hormone biosynthesis. Radioiodine has been used as a diagnostic and therapeutic tool for several years. However, the studies related to the mechanisms of iodide transport were only possible after the cloning of the gene that encodes the sodium/iodide symporter (NIS). The studies about the regulation of NIS expression and the possibility of gene therapy with the aim of transferring NIS gene to cells that normally do not express the symporter have also become possible. In the majority of hypofunctioning thyroid nodules, both benign and malignant, NIS gene expression is maintained, but NIS protein is retained in the intracellular compartment. The expression of NIS in non-thyroid tumoral cells in vivo has been possible through the transfer of NIS gene under the control of tissue-specific promoters. Apart from its therapeutic use, NIS has also been used for the localization of metastases by scintigraphy or PET-scan with 124 I. In conclusion, NIS gene cloning led to an important development in the field of thyroid pathophysiology, and has also been fundamental to extend the use of radioiodine for the management of non-thyroid tumors. A glândula tireóide tem capacidade de captar e concentrar iodeto, etapa fundamental na biossíntese dos hormônios tireóideos. O uso de iodo radioativo para fins de diagnóstico e terapia das doenças da tireóide vem sendo feito há muitos anos. Entretanto, somente após a clonagem do gene que codifica o cotransportador de sódio/iodeto (NIS) houve aumento significativo dos estudos relacionados ao mecanismo de transporte de iodeto. Os estudos sobre a regulação da expressão do NIS e a possibilidade de terapia gênica visando à transferência do gene NIS para células que normalmente não expressam esse transportador, foram também viabilizados. Na maior parte dos nódulos tireóideos hipofuncionantes, tanto benignos quanto malignos, a expressão do gene do NIS está presente, mas a proteína NIS fica retida no compartimento intracelular. A transferência do gene usando-se promotores tecido-específicos possibilitou a expressão do NIS em células tumorais não-tireóideas in vivo. Além do seu uso terapêutico, o NIS também vem sendo usado para a localização de metástases tumorais através da cintilografia ou do PET-scan usando-se 124 I. Em conclusão, a clonagem do NIS possibilitou enorme avanço na área de fisiopatologia tireóidea e foi também fundamental para estender o uso do radioiodo para tumores não tireóideos.

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“…All the effects depended on dosage and length of the treatment period (Chen and Walfish, 1978;Boado et al, 1983). It has been demonstrated (Lisboa et al, 1997) that higher doses of estradiol strongly stimulate the activity of thyroid enzymes (5'-deiodinase) which are responsible for the generation of T 3 . In our experiments, the treatments with either silymarin, or E 2, increased the serum concentrations of all thyroid hormones.…”

Section: Discussionmentioning

confidence: 99%

Estrogenic effects of silymarin in ovariectomized rats

Kummer¹,

Mašková²,

Čanderle³

et al. 2001

Vet. Med. - Czech

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The objective of this study was to test whether silymarin induces changes indicative of estrogenic effects in gonadal organs of ovariectomized (OVX) rats. Silymarin was administered in two experimental groups of OVX rats (n = 7 + 7) for 30 days at the doses of 25 or 50 mg per animal per day. OVX rats (n = 7) receiving 5 µg of 17b-estradiol (E2) for the last three days before killing and untreated OVX rats (n = 7) were used as the positive and the negative controls, respectively. Uterine and blood samples were collected immediately after killing. Compared with the negative controls, total and normalized uterine weights were significantly higher in the two experimental groups (P < 0.01 and P < 0.05, respectively). Uterotrophic effects of silymarin were also evident from increased heights of the luminal epithelium (P < 0.01) and the endometrium (P < 0.05). The response was dose-independent within the tested range. The strongest uterine response was observed in the OVX rats treated with E2. A highly significant decrease in mean density of estrogen receptor (ERa) immunostaining in the luminal and the glandular endometrial epithelia (P < 0.01) and a stronger ERa immunostaining in stromal cells were observed in the two experimental and the positive control groups. The activities of alkaline and acid phosphatases were significantly increased in the luminal (P < 0.05) and the glandular (P < 0.01) epithelia only in the rats treated with E2. Both silymarin and E2 induced an increase in thyroid hormone concentrations in blood serum. The rises of free T3 and T4 were significant (P < 0.05) in the group receiving 50 mg of silymarin per day. Hepatic oxidative metabolism of steroids was assumed to be another target of the action of silymarin. The mitochondrial cytochrome P450-dependent testosterone hydroxylase activity and the cytochrome P4501A-dependent 7-ethoxyresorufin O-deethylase activity were significantly increased (P < 0.05) in the group receiving 50 mg of silymarin per day and in the E2-treated control group, respectively. However, the modulations of the CYP enzymes played only a minor role in the overall estrogenic effect of silymarin. Histological and functional alterations in the OVX rats treated orally with silymarin for 30 days were consistent with those seen in E2-treated rats and were indicative of estrogenic effects of silymarin.

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Effects of estradiol benzoate on 5'-iodothyronine deiodinase activities in female rat anterior pituitary gland, liver and thyroid gland

Cited by 25 publications

References 17 publications

Sexual dimorphism in thyroid function and type 1 iodothyronine deiodinase activity in pre-pubertal and adult rats

Sexual dimorphism in thyroid function and type 1 iodothyronine deiodinase activity in pre-pubertal and adult rats

The importance of sodium/iodide symporter (NIS) for thyroid cancer management

Estrogenic effects of silymarin in ovariectomized rats

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