Barhl1 is directly regulated by thyroid hormone in the developing cerebellum of mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Hongyan, E-mail: hongyan_dong@hc-sc.gc.ca; Yauk, Carole L.; Wade, Michael G.

Highlights: Black-Right-Pointing-Pointer Thyroid hormone receptor binds to the promoter region of Barhl1. Black-Right-Pointing-Pointer Barhl1 expression in cerebellum is negatively regulated by thyroid hormone. Black-Right-Pointing-Pointer Negative regulation of Barhl1 by thyroid hormone was confirmed in vitro. Black-Right-Pointing-Pointer Thyroid hormone may play a role in normal brain development through transcriptional control of Barhl1. -- Abstract: Thyroid hormones (THs) are essential for the brain development. Despite considerable effort, few genes directly regulated by THs have been identified. In this study, we investigate the effects of THs on the regulation of Barhl1, a transcription factor that regulates sensorineural development. Using DNA microarray combined withmore » chromatin immunoprecipitation (ChIP-chip), we identified a TR{beta} binding site in the promoter of Barhl1. The binding was further confirmed by ChIP-PCR. The site is located approximately 755 bp upstream of the transcription start site. Reporter vectors containing the binding site or mutated fragments were transfected into GH3 cells. T3 treatment decreased the transcriptional activity of the wild fragment but not the mutant. Two 28 bp oligonucleotides containing sequences that resemble known TH response elements (TREs) were derived from this binding site and DNA-protein interaction was performed using electrophoretic mobility shift assays (EMSA). Binding analysis in a nuclear extract containing TR{beta} revealed that one of these fragments bound TR{beta}. This complex was shifted with the addition of anti-TR{beta} antibody. We investigated Barhl1 expression in animal models and TH-treated cultured cells. Both long term treatment with 6-propyl-2-thiouracil and short-term treatment with 0.05% methimazole/1% sodium perchlorate (both treatments render mice hypothyroid) resulted in up-regulation of Barhl1. TH supplementation of hypothyroid mice caused a decrease in the expression of Barhl1 compared to control animals. Similarly, the expression of Barhl1 in cultured GH3 decreased with the addition of T3. Given the important role of Barhl1 in brain development, we propose that perturbations of TH-mediated transcriptional control of Barhl1 may play a role in the impaired neurodevelopment induced by hypothyroidism.« less

Methyltestosterone-induced transient hyperthyroidism in a hypothyroid patient.

PubMed

Krysiak, R; Okopien, B

2013-01-01

In this paper we report different effects of methyltestosterone administration on thyroid function in two twin brothers, one of whom suffered from hypothyroidism, while the other was apparently healthy. Methyltestosterone, which is a non-aromatisable androgen, resulted in a marked reduction of thyroxine-binding globulin (TBG), irrespectively of the patient's hormonal status, while the impact on free thyroid hormones depended on baseline thyroid function. Our research shows that a possibility of the use of non-aromatisable androgens or other drugs affecting TBG levels should be taken into consideration in all hypothyroid patients receiving levothyroxine, in whom thyroid hormone status suddenly changes without any apparent reason.

(−) Arctigenin and (+) Pinoresinol Are Antagonists of the Human Thyroid Hormone Receptor β

PubMed Central

2015-01-01

Lignans are important biologically active dietary polyphenolic compounds. Consumption of foods that are rich in lignans is associated with positive health effects. Using modeling tools to probe the ligand-binding pockets of molecular receptors, we found that lignans have high docking affinity for the human thyroid hormone receptor β. Follow-up experimental results show that lignans (−) arctigenin and (+) pinoresinol are antagonists of the human thyroid hormone receptor β. The modeled complexes show key plausible interactions between the two ligands and important amino acid residues of the receptor. PMID:25383984

Effect of adrenal hormones on thyroid secretion and thyroid hormones on adrenal secretion in the sheep.

PubMed Central

Falconer, I R; Jacks, F

1975-01-01

1. Previous work has shown that after stressful stimuli, sheep initially secrete increased amounts of thyroid hormone, at a time when adrenal secretion is also elevated. 2. This study was designed to evaluate (a) any short-term activation or inhibition of thyroid secretion by exogenous cortisol or ACTH administered in quantities comparable to those secreted after stress in sheep and (b) any short-term effect that exogenous thyroxine or triiodothyronine may have on the concentration of plasma cortisol in the sheep. 3. Thyroid activity was measured by determination of plasma protein bound 125I (PB125I) and total 125I in thyroid vein and mixed venous (jugular) blood. Plasma cortisol and thyroxine concentrations were measured by a competitive protein-binding assay at intervals for up to 5 hr after commencement of the experiment. 4. No evidence of an activation of thyroid secretion was found during cortisol or ACTH infusion, as monitored by thyroid vein PB125I. Similarly there was no evidence of any inhibition of thyroid function, as measured by continued secretion of thyroid hormones into thyroid vein blood. 5. No effect on plasma cortisol concentration due to thyroid hormone treatment was observed. 6. It was concluded that (a) elevated circulating corticosteroids in physiological concentrations have no short-term effects on thyroid activity in the sheep and (b) the short-term alterations in thyroid and adrenal cortical secretion observed during stress in the sheep could not be attributed to direct interaction of elevated thyroid hormone concentrations with adrenal cortical secretion. PMID:170400

Thyroid hormone modulates insulin-like growth factor-I(IGF-I) and IGF-binding protein-3, without mediation by growth hormone, in patients with autoimmune thyroid diseases.

PubMed

Inukai, T; Takanashi, K; Takebayashi, K; Fujiwara, Y; Tayama, K; Takemura, Y

1999-10-01

The expression and synthesis of insulin-like growth factor-1 (IGF-I) and IGF-binding protein-3 (IGFBP-3) are regulated by various hormones and nutritional conditions. We evaluated the effects of thyroid hormones on serum levels of IGF-I and IGFBP-3 levels in patients with autoimmune thyroid diseases including 54 patients with Graves' disease and 17 patients with Hashimoto's thyroiditis, and in 32 healthy age-matched control subjects. Patients were subdivided into hyperthyroid, euthyroid and hypothyroid groups that were untreated, or were treated with methylmercaptoimidazole (MMI) or L-thyroxine (L-T4). Serum levels of growth hormone (GH), IGF-I and IGFBP-3 were determined by radioimmunoassay. Serum GH levels did not differ significantly between the hyperthyroid and the age-matched euthyroid patients with Graves' disease. The serum levels of IGF-I and IGFBP-3 showed a significant positive correlation in the patients (R=0.616, P<0.001). The levels of both IGF-I and IFGBP-3 were significantly higher in the hyperthyroid patients with Graves' disease or in those with Hashimoto's thyroiditis induced by excess L-T4 administration than in control subjects. Patients with hypothyroid Graves' disease induced by the excess administration of MMI showed significantly lower IGFBP-3 levels as compared to those in healthy controls (P<0.05). Levels of IGFBP-3, but not IGF-I levels, showed a significant positive correlation with the levels of free T4 and free T3. In Graves' disease, levels of TPOAb, but not of TRAb, showed a significant positive correlation with IGFBP-3. We conclude that in patients with autoimmune thyroid diseases, thyroid hormone modulates the synthesis and/or the secretion of IGF-I and IGFBP-3, and this function is not mediated by GH.

Impaired hair growth and wound healing in mice lacking thyroid hormone receptors.

PubMed

Contreras-Jurado, Constanza; García-Serrano, Laura; Martínez-Fernández, Mónica; Ruiz-Llorente, Lidia; Paramio, Jesus M; Aranda, Ana

2014-01-01

Both clinical and experimental observations show that the skin is affected by the thyroidal status. In hypothyroid patients the epidermis is thin and alopecia is common, indicating that thyroidal status might influence not only skin proliferation but also hair growth. We demonstrate here that the thyroid hormone receptors (TRs) mediate these effects of the thyroid hormones on the skin. Mice lacking TRα1 and TRβ (the main thyroid hormone binding isoforms) display impaired hair cycling associated to a decrease in follicular hair cell proliferation. This was also observed in hypothyroid mice, indicating the important role of the hormone-bound receptors in hair growth. In contrast, the individual deletion of either TRα1 or TRβ did not impair hair cycling, revealing an overlapping or compensatory role of the receptors in follicular cell proliferation. In support of the role of the receptors in hair growth, TRα1/TRβ-deficient mice developed alopecia after serial depilation. These mice also presented a wound-healing defect, with retarded re-epithelialization and wound gaping, associated to impaired keratinocyte proliferation. These results reinforce the idea that the thyroid hormone nuclear receptors play an important role on skin homeostasis and suggest that they could be targets for the treatment of cutaneous pathologies.

Thyroid hormones upregulate apolipoprotein E gene expression in astrocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roman, Corina; Fuior, Elena V.; Trusca, Violeta G.

Apolipoprotein E (apoE), a protein mainly involved in lipid metabolism, is associated with several neurodegenerative disorders including Alzheimer's disease. Despite numerous attempts to elucidate apoE gene regulation in the brain, the exact mechanism is still uncovered. The mechanism of apoE gene regulation in the brain involves the proximal promoter and multienhancers ME.1 and ME.2, which evolved by gene duplication. Herein we questioned whether thyroid hormones and their nuclear receptors have a role in apoE gene regulation in astrocytes. Our data showed that thyroid hormones increase apoE gene expression in HTB14 astrocytes in a dose-dependent manner. This effect can be intermediatedmore » by the thyroid receptor β (TRβ) which is expressed in these cells. In the presence of triiodothyronine (T3) and 9-cis retinoic acid, in astrocytes transfected to overexpress TRβ and retinoid X receptor α (RXRα), apoE promoter was indirectly activated through the interaction with ME.2. To determine the location of TRβ/RXRα binding site on ME.2, we performed DNA pull down assays and found that TRβ/RXRα complex bound to the region 341–488 of ME.2. This result was confirmed by transient transfection experiments in which a series of 5′- and 3′-deletion mutants of ME.2 were used. These data support the existence of a biologically active TRβ binding site starting at 409 in ME.2. In conclusion, our data revealed that ligand-activated TRβ/RXRα heterodimers bind with high efficiency on tissue-specific distal regulatory element ME.2 and thus modulate apoE gene expression in the brain. - Highlights: • T3 induce a dose-dependent increase of apoE expression in astrocytes. • Thyroid hormones activate apoE promoter in a cell specific manner. • Ligand activated TRβ/RXRα bind on the distal regulatory element ME.2 to modulate apoE. • The binding site of TRβ/RXRα heterodimer is located at 409 bp on ME.2.« less

Iodine Atoms: A New Molecular Feature for the Design of Potent Transthyretin Fibrillogenesis Inhibitors

PubMed Central

Pinto, Marta; Almeida, Maria Rosário; Gales, Luis; Ballesteros, Alfredo; Barluenga, José; Pérez, Juan J.; Vázquez, Jesús T.; Centeno, Nuria B.; Saraiva, Maria Joao; Damas, Ana M.; Planas, Antoni; Arsequell, Gemma; Valencia, Gregorio

2009-01-01

The thyroid hormone and retinol transporter protein known as transthyretin (TTR) is in the origin of one of the 20 or so known amyloid diseases. TTR self assembles as a homotetramer leaving a central hydrophobic channel with two symmetrical binding sites. The aggregation pathway of TTR into amiloid fibrils is not yet well characterized but in vitro binding of thyroid hormones and other small organic molecules to TTR binding channel results in tetramer stabilization which prevents amyloid formation in an extent which is proportional to the binding constant. Up to now, TTR aggregation inhibitors have been designed looking at various structural features of this binding channel others than its ability to host iodine atoms. In the present work, greatly improved inhibitors have been designed and tested by taking into account that thyroid hormones are unique in human biochemistry owing to the presence of multiple iodine atoms in their molecules which are probed to interact with specific halogen binding domains sitting at the TTR binding channel. The new TTR fibrillogenesis inhibitors are based on the diflunisal core structure because diflunisal is a registered salicylate drug with NSAID activity now undergoing clinical trials for TTR amyloid diseases. Biochemical and biophysical evidence confirms that iodine atoms can be an important design feature in the search for candidate drugs for TTR related amyloidosis. PMID:19125186

The axolotl (Ambystoma mexicanum), a neotenic amphibian, expresses functional thyroid hormone receptors.

PubMed

Safi, Rachid; Bertrand, Stéphanie; Marchand, Oriane; Duffraisse, Marilyne; de Luze, Amaury; Vanacker, Jean-Marc; Maraninchi, Marie; Margotat, Alain; Demeneix, Barbara; Laudet, Vincent

2004-02-01

Neotenic amphibians such as the axolotl (Ambystoma mexicanum) are often unable to undergo metamorphosis under natural conditions. It is thought that neoteny represents a deviation from the standard course of amphibian ontogeny, affecting the thyroid axis at different levels from the central nervous system to peripheral organs. Thyroid hormone receptors (TRs) that bind the thyroid hormone (TH) T(3) have been described in axolotl. However, the full sequences of TR were needed to better characterize the TH response and to be able to assess their functional capacity at the molecular level. We report that each of the alpha and beta axolotl TRs bind both DNA and TH, and they activate transcription in response to TH in a mammalian cell-based transient transfection assay. Moreover, both TRs are expressed in axolotl tissues. Interestingly, each TR gene generates alternatively spliced isoforms, harboring partial or total deletions of the ligand-binding domain, which are expressed in vivo. Further, we found that in the axolotl, TH regulates the expression of stromelysin 3 and collagenase 3, which are TH target genes in Xenopus. Taken together, these results suggest that axolotl TRs are functional and that the molecular basis of neoteny in the axolotl is not linked to a major defect in TH response in peripheral tissues.

Thyroid hormone upregulates zinc-α2-glycoprotein production in the liver but not in adipose tissue.

PubMed

Simó, Rafael; Hernández, Cristina; Sáez-López, Cristina; Soldevila, Berta; Puig-Domingo, Manel; Selva, David M

2014-01-01

Overproduction of zinc-α2-glycoprotein by adipose tissue is crucial in accounting for the lipolysis occurring in cancer cachexia of certain malignant tumors. The main aim of this study was to explore whether thyroid hormone could enhance zinc-α2-glycoprotein production in adipose tissue. In addition, the regulation of zinc-α2-glycoprotein by thyroid hormone in the liver was investigated. We performed in vitro (HepG2 cells and primary human adipocytes) and in vivo (C57BL6/mice) experiments addressed to examine the effect of thyroid hormone on zinc-α2-glycoprotein production (mRNA and protein levels) in liver and visceral adipose tissue. We also measured the zinc-α2-glycoprotein serum levels in a cohort of patients before and after controlling their hyperthyroidism. Our results showed that thyroid hormone up-regulates zinc-α2-glycoprotein production in HepG2 cells in a dose-dependent manner. In addition, the zinc-α2-glycoprotein proximal promoter contains functional thyroid hormone receptor binding sites that respond to thyroid hormone treatment in luciferase reporter gene assays in HepG2 cells. Furthermore, zinc-α2-glycoprotein induced lipolysis in HepG2 in a dose-dependent manner. Our in vivo experiments in mice confirmed the up-regulation of zinc-α2-glycoprotein induced by thyroid hormone in the liver, thus leading to a significant increase in zinc-α2-glycoprotein circulating levels. However, thyroid hormone did not regulate zinc-α2-glycoprotein production in either human or mouse adipocytes. Finally, in patients with hyperthyroidism a significant reduction of zinc-α2-glycoprotein serum levels was detected after treatment but was unrelated to body weight changes. We conclude that thyroid hormone up-regulates the production of zinc-α2-glycoprotein in the liver but not in the adipose tissue. The neutral effect of thyroid hormones on zinc-α2-glycoprotein expression in adipose tissue could be the reason why zinc-α2-glycoprotein is not related to weight loss in hyperthyroidism.

Thyroid Hormone Upregulates Zinc-α2-glycoprotein Production in the Liver but Not in Adipose Tissue

PubMed Central

Simó, Rafael; Hernández, Cristina; Sáez-López, Cristina; Soldevila, Berta; Puig-Domingo, Manel; Selva, David M.

2014-01-01

Overproduction of zinc-α2-glycoprotein by adipose tissue is crucial in accounting for the lipolysis occurring in cancer cachexia of certain malignant tumors. The main aim of this study was to explore whether thyroid hormone could enhance zinc-α2-glycoprotein production in adipose tissue. In addition, the regulation of zinc-α2-glycoprotein by thyroid hormone in the liver was investigated. We performed in vitro (HepG2 cells and primary human adipocytes) and in vivo (C57BL6/mice) experiments addressed to examine the effect of thyroid hormone on zinc-α2-glycoprotein production (mRNA and protein levels) in liver and visceral adipose tissue. We also measured the zinc-α2-glycoprotein serum levels in a cohort of patients before and after controlling their hyperthyroidism. Our results showed that thyroid hormone up-regulates zinc-α2-glycoprotein production in HepG2 cells in a dose-dependent manner. In addition, the zinc-α2-glycoprotein proximal promoter contains functional thyroid hormone receptor binding sites that respond to thyroid hormone treatment in luciferase reporter gene assays in HepG2 cells. Furthermore, zinc-α2-glycoprotein induced lipolysis in HepG2 in a dose-dependent manner. Our in vivo experiments in mice confirmed the up-regulation of zinc-α2-glycoprotein induced by thyroid hormone in the liver, thus leading to a significant increase in zinc-α2-glycoprotein circulating levels. However, thyroid hormone did not regulate zinc-α2-glycoprotein production in either human or mouse adipocytes. Finally, in patients with hyperthyroidism a significant reduction of zinc-α2-glycoprotein serum levels was detected after treatment but was unrelated to body weight changes. We conclude that thyroid hormone up-regulates the production of zinc-α2-glycoprotein in the liver but not in the adipose tissue. The neutral effect of thyroid hormones on zinc-α2-glycoprotein expression in adipose tissue could be the reason why zinc-α2-glycoprotein is not related to weight loss in hyperthyroidism. PMID:24465683

Pituitary resistance to thyroid hormone associated with a base mutation in the hormone-binding domain of the human 3,5,3'-triiodothyronine receptor-beta.

PubMed

Sasaki, S; Nakamura, H; Tagami, T; Miyoshi, Y; Nogimori, T; Mitsuma, T; Imura, H

1993-05-01

Point mutations in the human T3 receptor-beta (TR beta) gene causing single amino acid substitutions have been identified in several different kindreds with generalized resistance to thyroid hormone. Until now, no study has been reported on the TR gene in cases of pituitary resistance (PRTH). In the present study, we analyzed the TR beta gene in a 30-yr-old Japanese female with PRTH. She exhibited clinical features of hyperthyroidism, elevated serum thyroid hormone levels accompanied by inappropriately increased secretion of TSH, mildly elevated basal metabolic rate, and increased urinary excretion of hydroxyproline. No pituitary tumor was detected. DNA fragments of exons 3-8 of the genomic TR beta gene were generated by the polymerase chain reaction and analyzed by a single stranded conformation polymorphism method. Exon 7 of the patient's TR beta gene showed an abnormal band, suggesting the existence of mutation(s). By subcloning and sequencing the DNA, a point mutation was identified in one allele at nucleotide 1297 (C to T), which altered the 333rd amino acid, arginine, to tryptophan. Neither of her apparently normal parents had any mutations of the TR beta gene. In vitro translation products of the mutant TR beta gene showed remarkably decreased T3-binding activity (Ka, 2.1 x 10(8) M-1; normal TR beta Ka, 1.1 x 10(10) M-1). Since the molecular defect detected in a patient with PRTH is similar to that seen in subjects with generalized resistance to thyroid hormone, both types of the syndrome may represent a continuous spectrum of the same etiological defect with variable tissue resistance to thyroid hormone.

Insights into Enzyme Catalysis and Thyroid Hormone Regulation of Cerebral Ketimine Reductase/μ-Crystallin Under Physiological Conditions.

PubMed

Hallen, André; Cooper, Arthur J L; Jamie, Joanne F; Karuso, Peter

2015-06-01

Mammalian ketimine reductase is identical to μ-crystallin (CRYM)-a protein that is also an important thyroid hormone binding protein. This dual functionality implies a role for thyroid hormones in ketimine reductase regulation and also a reciprocal role for enzyme catalysis in thyroid hormone bioavailability. In this research we demonstrate potent sub-nanomolar inhibition of enzyme catalysis at neutral pH by the thyroid hormones L-thyroxine and 3,5,3'-triiodothyronine, whereas other thyroid hormone analogues were shown to be far weaker inhibitors. We also investigated (a) enzyme inhibition by the substrate analogues pyrrole-2-carboxylate, 4,5-dibromopyrrole-2-carboxylate and picolinate, and (b) enzyme catalysis at neutral pH of the cyclic ketimines S-(2-aminoethyl)-L-cysteine ketimine (owing to the complex nomenclature trivial names are used for the sulfur-containing cyclic ketimines as per the original authors' descriptions) (AECK), Δ(1)-piperideine-2-carboxylate (P2C), Δ(1)-pyrroline-2-carboxylate (Pyr2C) and Δ(2)-thiazoline-2-carboxylate. Kinetic data obtained at neutral pH suggests that ketimine reductase/CRYM plays a major role as a P2C/Pyr2C reductase and that AECK is not a major substrate at this pH. Thus, ketimine reductase is a key enzyme in the pipecolate pathway, which is the main lysine degradation pathway in the brain. In silico docking of various ligands into the active site of the X-ray structure of the enzyme suggests an unusual catalytic mechanism involving an arginine residue as a proton donor. Given the critical importance of thyroid hormones in brain function this research further expands on our knowledge of the connection between amino acid metabolism and regulation of thyroid hormone levels.

Identification of Thyroid Hormones and Functional Characterization of Thyroid Hormone Receptor in the Pacific Oyster Crassostrea gigas Provide Insight into Evolution of the Thyroid Hormone System

PubMed Central

Huang, Wen; Xu, Fei; Qu, Tao; Zhang, Rui; Li, Li; Que, Huayong; Zhang, Guofan

2015-01-01

Thyroid hormones (THs) play important roles in development, metamorphosis, and metabolism in vertebrates. During the past century, TH functions were regarded as a synapomorphy of vertebrates. More recently, accumulating evidence has gradually convinced us that TH functions also occur in invertebrate chordates. To date, however, TH-related studies in non-chordate invertebrates have been limited. In this study, THs were qualitatively detected by two reliable methods (HPLC and LC/MS) in a well-studied molluscan species, the Pacific oyster Crassostrea gigas. Quantitative measurement of THs during the development of C. gigas showed high TH contents during embryogenesis and that oyster embryos may synthesize THs endogenously. As a first step in elucidating the TH signaling cascade, an ortholog of vertebrate TH receptor (TR), the most critical gene mediating TH effects, was cloned in C. gigas. The sequence of CgTR has conserved DNA-binding and ligand-binding domains that normally characterize these receptors. Experimental results demonstrated that CgTR can repress gene expression through binding to promoters of target genes and can interact with oyster retinoid X receptor. Moreover, CgTR mRNA expression was activated by T4 and the transcriptional activity of CgTR promoter was repressed by unliganded CgTR protein. An atypical thyroid hormone response element (CgDR5) was found in the promoter of CgTR, which was verified by electrophoretic mobility shift assay (EMSA). These results indicated that some of the CgTR function is conserved. However, the EMSA assay showed that DNA binding specificity of CgTR was different from that of the vertebrate TR and experiments with two dual-luciferase reporter systems indicated that l-thyroxine, 3,3′,5-triiodothyronine, and triiodothyroacetic acid failed to activate the transcriptional activity of CgTR. This is the first study to functionally characterize TR in mollusks. The presence of THs and the functions of CgTR in mollusks contribute to better understanding of the evolution of the TH system. PMID:26710071

Thyroid hormones and their effects: a new perspective.

PubMed

Hulbert, A J

2000-11-01

The thyroid hormones are very hydrophobic and those that exhibit biological activity are 3',5',3,5-L-tetraiodothyronine (T4), 3',5,3-L-triiodothyronine (T3), 3',5',3-L-triiodothyronine (rT3) and 3,5',-L-diiothyronine (3,5-T2). At physiological pH, dissociation of the phenolic -OH group of these iodothyronines is an important determinant of their physical chemistry that impacts on their biological effects. When non-ionized these iodothyronines are strongly amphipathic. It is proposed that iodothyronines are normal constituents of biological membranes in vertebrates. In plasma of adult vertebrates, unbound T4 and T3 are regulated in the picomolar range whilst protein-bound T4 and T3 are maintained in the nanomolar range. The function of thyroid-hormone-binding plasma proteins is to ensure an even distrubtion throughout the body. Various iodothyronines are produced by three types of membrane-bound cellular deiodinase enzyme systems in vertebrates. The distribution of deiodinases varies between tissues and each has a distinct developmental profile. Thyroid hormones. (1) the nuclear receptor mode is especially important in the thyroid hormone axis that controls plasma and cellular levels of these hormones. (2) These hormones are strongly associated with membranes in tissues and normally rigidify these membranes. (3) They also affect the acyl composition of membrane bilayers and it is suggested that this is due to the cells responding to thyroid-hormone-induced membrane rigidificataion. Both their immediate effects on the physical state of membranes and the consequent changes in membrane composition result in several other thyroid hormone effects. Effects on metabolism may be due primarily to membrane acyl changes. There are other actions of thyroid hormones involving membrane receptors and influences on cellular interactions with the extracellulara matrix. The effects of thyroid hormones are reviewed and appear to b combinations of these various modes of action. During development, vertebrates show a surge in T4 and other thyroid hormones, as well as distinctive profiles in the appearance of the deiodinase enzymes and nuclear receptors. Evidence from the use of analogues supports multiple modes of action. Re-examination of data from th early 1960s supports a membrane action. Findings from receptor 'knockout' mice supports an important role for receptors in the development of the thyroid axis. These iodothyronines may be better thought of as 'vitamone'-like molecules than traditional hormonal messengers.

Thyroid hormone and COUP-TF1 regulate kallikrein-binding protein (KBP) gene expression.

PubMed

Liu, Yan-Yun; Nakatani, Teruyo; Kogai, Takahiko; Mody, Kaizeen; Brent, Gregory A

2011-03-01

Kallikrein-binding protein (KBP) is a component of the kallikrein-kinin system that mediates vasodilation and inhibits tumor growth by antagonizing vascular endothelial growth factor-mediated angiogenesis. We demonstrate that KBP gene expression is repressed by T(3) and modulated by the orphan nuclear receptor, chicken ovalbumin upstream promoter transcription factor 1 (COUP-TF1). In hypothyroid mice, KBP mRNA expression in the testis was increased 2.1-fold compared with euthyroid mice. We have identified two negative thyroid hormone response elements (nTREs) in the mouse KBP gene, nTRE1 located in the 5' flanking region (-53 to -29) and nTRE2, located in the first intron (104-132). We used functional assays, cofactor knockdown, and chromatin immunoprecipitation assays to characterize nTRE1 and nTRE2 in hepatic (HepG2) and testes (GC-1spg) cell lines. Reporter expression directed by both elements was enhanced with addition of thyroid hormone receptor and repressed with the addition of T(3). COUP-TF1 enhanced basal expression of both elements but blunted unliganded thyroid hormone receptor enhancement and T(3) repression of nTRE1 but not nTRE2. Both nTREs bound nuclear corepressor and binding increased in response to T(3). Nuclear corepressor knockdown resulted in loss of T(3) repression of both nTRE1 and nTRE2. COUP-TF1, which usually represses T(3) induction of positive thyroid hormone response elements, reverses T(3) repression mediated by nTRE1 in the mouse KBP gene. Endogenous KBP expression is repressed by T(3) and two functional nTREs, both of which are required, have been characterized in the KBP gene. COUP-TF1 may be an important factor to modulate expression of genes that are repressed by T(3).

Thyroid Hormone and COUP-TF1 Regulate Kallikrein-Binding Protein (KBP) Gene Expression

PubMed Central

Liu, Yan-Yun; Nakatani, Teruyo; Kogai, Takahiko; Mody, Kaizeen

2011-01-01

Kallikrein-binding protein (KBP) is a component of the kallikrein-kinin system that mediates vasodilation and inhibits tumor growth by antagonizing vascular endothelial growth factor-mediated angiogenesis. We demonstrate that KBP gene expression is repressed by T3 and modulated by the orphan nuclear receptor, chicken ovalbumin upstream promoter transcription factor 1 (COUP-TF1). In hypothyroid mice, KBP mRNA expression in the testis was increased 2.1-fold compared with euthyroid mice. We have identified two negative thyroid hormone response elements (nTREs) in the mouse KBP gene, nTRE1 located in the 5′ flanking region (−53 to −29) and nTRE2, located in the first intron (104–132). We used functional assays, cofactor knockdown, and chromatin immunoprecipitation assays to characterize nTRE1 and nTRE2 in hepatic (HepG2) and testes (GC-1spg) cell lines. Reporter expression directed by both elements was enhanced with addition of thyroid hormone receptor and repressed with the addition of T3. COUP-TF1 enhanced basal expression of both elements but blunted unliganded thyroid hormone receptor enhancement and T3 repression of nTRE1 but not nTRE2. Both nTREs bound nuclear corepressor and binding increased in response to T3. Nuclear corepressor knockdown resulted in loss of T3 repression of both nTRE1 and nTRE2. COUP-TF1, which usually represses T3 induction of positive thyroid hormone response elements, reverses T3 repression mediated by nTRE1 in the mouse KBP gene. Endogenous KBP expression is repressed by T3 and two functional nTREs, both of which are required, have been characterized in the KBP gene. COUP-TF1 may be an important factor to modulate expression of genes that are repressed by T3. PMID:21266512

Sex-hormone-binding globulin.

PubMed

Anderson, D C

1974-01-01

A review was made to understand how plasma binding protein might influence sex-hormone action in target tissues. Steroids are predominately bound to plasma proteins and only unbound steroids enter the cells. Sex-hormone-binding globulin (SHBG) binds to both the main circulating steroid T and E2 but changes in SHBG concentrations exert significant results. Increased SHBG levels increase estrogen production and decreases T activity; whereas, increased androgens increase T action and inhibit SHBG production. These disturbances in hormone maintenance may lead to abnormal adult sex differentiation such as hirsutism and forms of hynaecomastia. By developing SHBG concentration measurement methods-responses of hirsutism to glucocorticoid or estrogem may be assessed. In addition, the effect of thyroid hormones on SHBG may also have therapeutic implications in endocrine disease.

Impact of light exposure on thyroid-stimulating hormone results using the Siemens Advia Centaur TSH-3Ultra assay.

PubMed

Armer, Jane; Giles, Diane; Lancaster, Ian; Brownbill, Kathryn

2017-09-01

Background Thyroid-stimulating hormone (TSH) is used as the first-line test of thyroid function. Siemens Healthcare Diagnostics recommend that Siemens Centaur reagents must be protected from light in the assay information and on reagent packaging. We have compared the effect of light exposure on results using Siemens TSH-3Ultra and follicle-stimulating hormone reagents. The thyroid-stimulating hormone reagent includes fluoroscein thiocyanate whereas the follicle-stimulating hormone reagent does not. Methods Three levels of quality controls were analysed using SiemensTSH-3Ultra and follicle-stimulating hormone reagent packs that had been kept protected from light or exposed to light at 6-h intervals for 48 h and then at 96 h. Results Thyroid-stimulating hormone results were significantly lower after exposure of TSH-3Ultra reagent packs to light. Results were >15% lower at all three levels of quality control following 18 h of light exposure and continued to decrease until 96 h. There was no significant difference in follicle-stimulating hormone results whether reagents had been exposed to or protected from light. Conclusions Thyroid-stimulating hormone results but not follicle-stimulating hormone results are lowered after exposure of reagent packs to light. Laboratories must ensure that TSH-3Ultra reagents are not exposed to light and analyse quality control samples on every reagent pack to check that there has not been light exposure prior to delivery. The labelling on TSH-3Ultra reagent packs should reflect the significant effect of light exposure compared with the follicle-stimulating hormone reagent. We propose that the effect of light exposure on binding of fluoroscein thiocyanate to the solid phase antibody causes the falsely low results.

Direct Regulation of Mitochondrial RNA Synthesis by Thyroid Hormone

PubMed Central

Enríquez, José A.; Fernández-Silva, Patricio; Garrido-Pérez, Nuria; López-Pérez, Manuel J.; Pérez-Martos, Acisclo; Montoya, Julio

1999-01-01

We have analyzed the influence of in vivo treatment and in vitro addition of thyroid hormone on in organello mitochondrial DNA (mtDNA) transcription and, in parallel, on the in organello footprinting patterns at the mtDNA regions involved in the regulation of transcription. We found that thyroid hormone modulates mitochondrial RNA levels and the mRNA/rRNA ratio by influencing the transcriptional rate. In addition, we found conspicuous differences between the mtDNA dimethyl sulfate footprinting patterns of mitochondria derived from euthyroid and hypothyroid rats at the transcription initiation sites but not at the mitochondrial transcription termination factor (mTERF) binding region. Furthermore, direct addition of thyroid hormone to the incubation medium of mitochondria isolated from hypothyroid rats restored the mRNA/rRNA ratio found in euthyroid rats as well as the mtDNA footprinting patterns at the transcription initiation area. Therefore, we conclude that the regulatory effect of thyroid hormone on mitochondrial transcription is partially exerted by a direct influence of the hormone on the mitochondrial transcription machinery. Particularly, the influence on the mRNA/rRNA ratio is achieved by selective modulation of the alternative H-strand transcription initiation sites and does not require the previous activation of nuclear genes. These results provide the first functional demonstration that regulatory signals, such as thyroid hormone, that modify the expression of nuclear genes can also act as primary signals for the transcriptional apparatus of mitochondria. PMID:9858589

Weight-of-evidence analysis of human exposures to dioxins and dioxin-like compounds and associations with thyroid hormone levels during early development.

PubMed

Goodman, Julie E; Kerper, Laura E; Boyce, Catherine Petito; Prueitt, Robyn L; Rhomberg, Lorenz R

2010-10-01

Thyroid hormones play a critical role in the proper development of brain function and cell growth. Several epidemiological studies have been conducted to assess potential associations between pre- and post-natal exposure to dioxins or dioxin-like compounds (DLCs) and the levels of circulating thyroid hormones during early development. Dioxins and DLCs include chlorinated dibenzo-p-dioxins, chlorinated dibenzofurans, and mono- and non-ortho polychlorinated biphenyls (PCBs). We identified a total of 23 relevant epidemiological studies (21 cohort studies and 1 case-control study) that measured exposures to various types of dioxins and DLCs as well as markers of thyroid function, such as thyroid stimulating hormone (TSH), total thyroxine (T4), free T4, total triiodothyroxine (T3), free T3, and thyroid-binding globulin concentrations in cord blood or circulation. While some of the studies reported associations between concentrations of dioxins and/or DLCs and some biomarkers of thyroid function, the majority of the observed associations were not statistically significant. Moreover, there were no clear and consistent effects across studies for any of the hormone levels examined, and while a number of studies showed a statistically significant association with exposure for a given marker of thyroid function, other studies showed either no change or changes in the opposite direction for the same thyroid function marker. Similarly, when the results were analyzed considering developmental stage, there generally were no clear and consistent effects at any age from birth through 12 years of age. The absence of a clear correlation between background exposures to dioxins and DLCs and thyroid function biomarkers during development is not consistent with the hypothesis that background exposures to these chemicals cause effects on thyroid function during development. Copyright (c) 2010 Elsevier Inc. All rights reserved.

GLIS3 is indispensable for TSH/TSHR-dependent thyroid hormone biosynthesis and follicular cell proliferation

PubMed Central

Kang, Hong Soon; Kumar, Dhirendra; Liao, Grace; Lichti-Kaiser, Kristin; Gerrish, Kevin; Liao, Xiao-Hui; Refetoff, Samuel; Jothi, Raja; Jetten, Anton M.

2017-01-01

Deficiency in Krüppel-like zinc finger transcription factor GLI-similar 3 (GLIS3) in humans is associated with the development of congenital hypothyroidism. However, the functions of GLIS3 in the thyroid gland and the mechanism by which GLIS3 dysfunction causes hypothyroidism are unknown. In the current study, we demonstrate that GLIS3 acts downstream of thyroid-stimulating hormone (TSH) and TSH receptor (TSHR) and is indispensable for TSH/TSHR-mediated proliferation of thyroid follicular cells and biosynthesis of thyroid hormone. Using ChIP-Seq and promoter analysis, we demonstrate that GLIS3 is critical for the transcriptional activation of several genes required for thyroid hormone biosynthesis, including the iodide transporters Nis and Pds, both of which showed enhanced GLIS3 binding at their promoters. The repression of cell proliferation of GLIS3-deficient thyroid follicular cells was due to the inhibition of TSH-mediated activation of the mTOR complex 1/ribosomal protein S6 (mTORC1/RPS6) pathway as well as the reduced expression of several cell division–related genes regulated directly by GLIS3. Consequently, GLIS3 deficiency in a murine model prevented the development of goiter as well as the induction of inflammatory and fibrotic genes during chronic elevation of circulating TSH. Our study identifies GLIS3 as a key regulator of TSH/TSHR-mediated thyroid hormone biosynthesis and proliferation of thyroid follicular cells and uncovers a mechanism by which GLIS3 deficiency causes neonatal hypothyroidism and prevents goiter development. PMID:29083325

Hypothyroidism and Nephrotic Syndrome: Why, When and How to Treat.

PubMed

Mario, F Di; Pofi, R; Gigante, A; Rivoli, L; Rosato, E; Isidori, A M; Cianci, R; Barbano, B

2017-01-01

Hypothyroidism, characterised by low/normal free thyroxine (FT4) and free triiodothyronine (FT3) with elevated thyroid-stimulating hormone (TSH), is a well-known complication of nephrotic syndrome (NS). This is a common feature of primary and secondary glomerular diseases and comprises loss of protein in the urine and increased urinary excretion of thyroid hormones and thyroxine- binding globulin. With a normal thyroid reserve, this scenario is associated with the development of subclinical hypothyroidism, with a slight increase in TSH and normal free fractions. However, with a low thyroid reserve the transition toward overt hypothyroidism is almost inevitable, affecting morbidity and mortality. As T4 replacement is a cheap and well-established treatment to achieve a stable hormone status in different types of thyroid deficiency, it is essential to recognise and appropriately treat this condition. In this article we summarise the evidence on this nephro-endocrine disorder in humans and focus on diagnostic and therapeutic strategies. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Capacity for cooperative binding of thyroid hormone (T3) receptor dimers defines wild type T3 response elements.

PubMed

Brent, G A; Williams, G R; Harney, J W; Forman, B M; Samuels, H H; Moore, D D; Larsen, P R

1992-04-01

Thyroid hormone response elements (T3REs) have been identified in a variety of promoters including those directing expression of rat GH (rGH), alpha-myosin heavy chain (rMHC), and malic enzyme (rME). A detailed biochemical and genetic analysis of the rGH element has shown that it consists of three hexamers related to the consensus [(A/G)GGT(C/A)A]. We have extended this analysis to the rMHC and rME elements. Binding of highly purified thyroid hormone receptor (T3R) to T3REs was determined using the gel shift assay, and thyroid hormone (T3) induction was measured in transient tranfections. We show that the wild type version of each of the three elements binds T3R dimers cooperatively. Mutational analysis of the rMHC and rME elements identified domains important for binding T3R dimers and allowed a direct determination of the relationship between T3R binding and function. In each element two hexamers are required for dimer binding, and mutations that interfere with dimer formation significantly reduce T3 induction. Similar to the rGH element, the rMHC T3RE contains three hexameric domains arranged as a direct repeat followed by an inverted copy, although the third domain is weaker than in rGH. All three are required for full function and T3R binding. The rME T3RE is a two-hexamer direct repeat T3RE, which also binds T3R monomer and dimer. Across a series of mutant elements, there was a strong correlation between dimer binding in vitro and function in vivo for rMHC (r = 0.99, P less than 0.01) and rME (r = 0.67, P less than 0.05) T3REs. Our results demonstrate a similar pattern of T3R dimer binding to a diverse array of hexameric sequences and arrangements in three wild type T3REs. Addition of nuclear protein enhanced T3R binding but did not alter the specificity of binding to wild type or mutant elements. Binding of purified T3R to T3REs was highly correlated with function, both with and without the addition of nuclear protein. T3R dimer formation is the common feature which defines the capacity of these elements to confer T3 induction.

Assessing the relationship between perfluoroalkyl substances, thyroid hormones and binding proteins in pregnant women; a longitudinal mixed effects approach.

PubMed

Berg, Vivian; Nøst, Therese Haugdahl; Hansen, Solrunn; Elverland, Astrid; Veyhe, Anna-Sofía; Jorde, Rolf; Odland, Jon Øyvind; Sandanger, Torkjel Manning

2015-04-01

The mechanisms involved in thyroid homeostasis are complex, and perfluoroalkyl substances (PFASs) have been indicated to interfere at several levels in this endocrine system. Disruption of the maternal thyroid homeostasis during early pregnancy is of particular concern, where subclinical changes in maternal thyroid hormones (THs) may affect embryonic and foetal development. The present study investigated associations between THs, thyroid binding proteins (TH-BPs) and PFAS concentrations in pregnant women from Northern Norway. Women participating in The Northern Norway Mother-and-Child contaminant Cohort Study (MISA) donated a blood sample at three visits related to their pregnancy and postpartum period (during the second trimester, 3 days and 6 weeks after delivery) in the period 2007-2009. Participants were assigned to quartiles according to PFAS concentrations during the second trimester and mixed effects linear models were used to investigate potential associations between PFASs and repeated measurements of THs, TH-BPs, thyroxin binding capacity and thyroid peroxidase antibodies (anti-TPOs). Women within the highest perfluorooctane sulfonate (PFOS) quartile had 24% higher mean concentrations of thyroid stimulating hormone (TSH) compared to the first quartile at all sampling points. Women within the highest quartiles of perfluorodecanoate (PFDA) had 4% lower mean concentrations of triiodothyronine (T3) and women within the highest quartile of perfluoroundecanoate (PFUnDA) had 3% lower mean concentrations of free triiodothyronine (FT3). Further, the difference in concentrations and the changes between three time points were the same for the PFAS quartiles. Thyroxin binding capacity was associated with all the THs and TH-BPs, and was selected as a holistic adjustment for individual changes in TH homeostasis during pregnancy. Finally, adjusting for maternal iodine status did not influence the model predictions. Findings in the present study suggest modifications of TH homeostasis by PFASs in a background exposed maternal population. The variation in levels of THs between PFAS quartiles was within normal reference ranges and may not be of clinical significance in the pregnant woman. However, subtle individual changes in maternal THs may have significant consequences for foetal health. Copyright © 2015 Elsevier Ltd. All rights reserved.

DR-78, a novel Drosophila melanogaster genomic DNA fragment highly homologous to the DNA-binding domain of thyroid hormone-retinoic acid-vitamin D receptor subfamily.

PubMed

Martín-Blanco, E; Kornberg, T B

1993-11-16

Degenerate oligodeoxyribonucleotides were designed for both ends of the DNA-binding domain of members of the nuclear receptor superfamily. PCR amplified Drosophila melanogaster DNA was purified and cloned (DR plasmids). Genomic lambda DASH clones were identified at high stringency with an amplified DR-78 plasmid DNA and isolated. The partial sequence shows a very probable open reading frame which would encode a peptide highly homologous to members of the thyroid hormone-retinoic acid-vitamin D receptor subfamily. The fragment corresponds to a single copy gene and was mapped at position 78D of chromosome three by in situ hybridization.

Super-sensitive time-resolved fluoroimmunoassay for thyroid-stimulating hormone utilizing europium(III) nanoparticle labels achieved by protein corona stabilization, short binding time, and serum preprocessing.

PubMed

Näreoja, Tuomas; Rosenholm, Jessica M; Lamminmäki, Urpo; Hänninen, Pekka E

2017-05-01

Thyrotropin or thyroid-stimulating hormone (TSH) is used as a marker for thyroid function. More precise and more sensitive immunoassays are needed to facilitate continuous monitoring of thyroid dysfunctions and to assess the efficacy of the selected therapy and dosage of medication. Moreover, most thyroid diseases are autoimmune diseases making TSH assays very prone to immunoassay interferences due to autoantibodies in the sample matrix. We have developed a super-sensitive TSH immunoassay utilizing nanoparticle labels with a detection limit of 60 nU L -1 in preprocessed serum samples by reducing nonspecific binding. The developed preprocessing step by affinity purification removed interfering compounds and improved the recovery of spiked TSH from serum. The sensitivity enhancement was achieved by stabilization of the protein corona of the nanoparticle bioconjugates and a spot-coated configuration of the active solid-phase that reduced sedimentation of the nanoparticle bioconjugates and their contact time with antibody-coated solid phase, thus making use of the higher association rate of specific binding due to high avidity nanoparticle bioconjugates. Graphical Abstract We were able to decrease the lowest limit of detection and increase sensitivity of TSH immunoassay using Eu(III)-nanoparticles. The improvement was achieved by decreasing binding time of nanoparticle bioconjugates by small capture area and fast circular rotation. Also, we applied a step to stabilize protein corona of the nanoparticles and a serum-preprocessing step with a structurally related antibody.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, R.A.; Rajatanavin, R.; Moring, A.F.

Five-month-old lean and obese Zucker rats were fasted for up to 7 days (lean rats) or 28 days (obese rats), and serum total and free T4 and T3 concentrations, percent free T4 and T3 by equilibrium dialysis, and the binding of (/sup 125/I) T4 to serum proteins by gel electrophoresis were measured. In the lean rats, a 4- or 7-day fast resulted in significant decreases in serum total and free T4 and T3 concentrations. There was a decrease in the percent free T3 after 7 days of starvation. In contrast, a 4- or 7-day fast did not alter any ofmore » these variables in the obese rats. However, after 14 or more days of starvation, serum total T4 and T3 concentrations increased, and the percent free T4 and T3 decreased, resulting in no change in the serum free T4 or T3 concentrations in the obese rats. The percent of (/sup 125/I)T4 bound to serum thyronine-binding globulin increased and the percent bound to thyronine-binding prealbumin decreased with the duration of the fast in both the lean and obese rats. The increase in serum thyronine-binding globulin binding of T4 can explain the increase in serum total T4 and T3 concentrations, the decrease in percent free T4 and T3, and the normal free hormone concentration in the long term fasted obese rats. The findings in the lean rats appear to be due to a combination of the known central hypothyroidism that occurs during 4-7 days of fasting and the fasting-induced changes in T4 binding in serum. Changes in T4 and T3 binding in serum during fasting in the rat must be considered when the effects of fasting on serum concentrations of the thyroid hormones, thyroid hormone kinetics, and the peripheral action of the thyroid hormones are evaluated.« less

Design and synthesis of a novel series of [1-(4-hydroxy-benzyl)-1H-indol-5-yloxy]-acetic acid compounds as potent, selective, thyroid hormone receptor β agonists.

PubMed

Burkholder, Timothy P; Cunningham, Brian E; Clayton, Joshua R; Lander, Peter A; Brown, Matthew L; Doti, Robert A; Durst, Gregory L; Montrose-Rafizadeh, Chahrzad; King, Constance; Osborne, Harold E; Amos, Robert M; Zink, Richard W; Stramm, Lawrence E; Burris, Thomas P; Cardona, Guemalli; Konkol, Debra L; Reidy, Charles; Christe, Michael E; Genin, Michael J

2015-04-01

The design, synthesis, and structure activity relationships for a novel series of indoles as potent, selective, thyroid hormone receptor β (TRβ) agonists is described. Compounds with >50× binding selectivity for TRβ over TRα were generated and evaluation of compound 1c from this series in a model of dyslipidemia demonstrated positive effects on plasma lipid endpoints in vivo. Copyright © 2015 Elsevier Ltd. All rights reserved.

Exposure to DBP and High Iodine Aggravates Autoimmune Thyroid Disease Through Increasing the Levels of IL-17 and Thyroid-Binding Globulin in Wistar Rats.

PubMed

Duan, Jiufei; Kang, Jun; Deng, Ting; Yang, Xu; Chen, Mingqing

2018-05-01

Autoimmune thyroid disease (AITD) is the most common autoimmune disease that causes hypothyroidism. High iodine is a well-known factor that can induce thyroid disorders, including Hashimoto's thyroiditis, one of the main types of AITD. Recent epidemiological studies have indicated that phthalates, especially di-n-butyl phthalate (DBP) may induce thyroid disease. In this study, we aim to determine the effects and underlying mechanisms of high iodine and/or DBP exposure on AITD. Female Wistar rats were modeled with thyroglobulin and exposed to high iodine and/or DBP. We investigated histopathological changes in the thyroid and measured thyroid hormone levels in serum to assess thyroid function. In the thyroid and liver, we detected oxidative stress, proinflammatory factors (IL-1β, IL-6, and IL-17) and the activation of activator protein 1 (AP-1), a transcription factor that is related to the synthesis of the thyroxine-binding globulin (TBG) and the activation of Th17. After blocking AP-1 with SP600125, we detected TBG and the Th17 related cytokines (IL-6 and IL-17). The data showed that thyroid damage and the alteration of thyroid hormones were greater when the rats were exposed to both high iodine and DBP. Coexposure to DBP and high iodine enhanced the activation of AP-1 in the liver and thyroid, and induced an increase in the levels of TBG in serum and IL-17 in the thyroid. Blocking AP-1 activation prevented the increase of TBG and IL-17. The results indicate that high iodine and/or DBP exposure exacerbated AITD through altering TBG levels in serum and aggravating IL-17 in the thyroid.

Isolation of a thyroid hormone-responsive gene by immunoprecipitation of thyroid hormone receptor-DNA complexes.

PubMed Central

Bigler, J; Eisenman, R N

1994-01-01

Thyroid hormone (T3) receptor (TR) is a ligand-dependent transcription factor that acts through specific binding sites in the promoter region of target genes. In order to identify new genes that are regulated by T3, we used anti-TR antiserum to immunoprecipitate TR-DNA complexes from GH4 cell nuclei that had previously been treated with a restriction enzyme. Screening of the immunopurified, cloned DNA for TR binding sites by electrophoretic mobility shift assay yielded 53 positive clones. A subset of these clones was specifically immunoprecipitated with anti-TR antiserum and may therefore represent biologically significant binding sites. One of these clones, clone 122, was characterized in detail. It includes sequences highly related to the NICER long terminal repeat-like element and contains three TR binding sites as determined by DNase I footprinting. Two of the clone 122 TR binding sites are located upstream of the TATA box, and one is located downstream. The TR binding site downstream from the promoter was necessary and sufficient to confer T3-dependent regulation in transient transfection experiments. Expression of a reporter construct under the control of the clone 122 promoter region was activated by TR in the absence of ligand and returned to basal levels after T3 addition. Clone 122 sequences hybridize to at least two different mRNAs of approximately 6 and 10 kb from GH4 cells. The levels of both of these mRNAs increased upon removal of T3. Our studies suggest that specific immunoprecipitation of chromatin allows identification of binding sites and target genes for transcription factors. Images PMID:7935476

Thyroid hormone metabolism and environmental chemical exposure

PubMed Central

2012-01-01

Background Polychlorinated dioxins and –furans (PCDD/Fs) and polychlorinated-biphenyls (PCBs) are environmental toxicants that have been proven to influence thyroid metabolism both in animal studies and in human beings. In recent years polybrominated diphenyl ethers (PBDEs) also have been found to have a negative influence on thyroid hormone metabolism. The lower brominated flame retardants are now banned in the EU, however higher brominated decabromo-diphenyl ether (DBDE) and the brominated flame retardant hexabromocyclododecane (HBCD) are not yet banned. They too can negatively influence thyroid hormone metabolism. An additional brominated flame retardant that is still in use is tetrabromobisphenol-A (TBBPA), which has also been shown to influence thyroid hormone metabolism. Influences of brominated flame retardants, PCDD/F’s and dioxin like-PCBs (dl-PCB’s) on thyroid hormone metabolism in adolescence in the Netherlands will be presented in this study and determined if there are reasons for concern to human health for these toxins. In the period 1987-1991, a cohort of mother-baby pairs was formed in order to detect abnormalities in relation to dioxin levels in the perinatal period. The study demonstrated that PCDD/Fs were found around the time of birth, suggesting a modulation of the setpoint of thyroid hormone metabolism with a higher 3,3’, 5,5’tetrathyroxine (T4) levels and an increased thyroid stimulating hormone (TSH). While the same serum thyroid hormone tests (- TSH and T4) were again normal by 2 years of age and were still normal at 8-12 years, adolescence is a period with extra stress on thyroid hormone metabolism. Therefore we measured serum levels of TSH, T4, 3,3’,5- triiodothyronine (T3), free T4 (FT4), antibodies and thyroxine-binding globulin (TBG) in our adolescent cohort. Methods Vena puncture was performed to obtain samples for the measurement of thyroid hormone metabolism related parameters and the current serum dioxin (PCDD/Fs), PCB and PBDE levels. Results The current levels of T3 were positively correlated to BDE-99. A positive trend with FT4 and BDE-99 was also seen, while a positive correlation with T3 and dl-PCB was also seen. No correlation with TBG was seen for any of the contaminants. Neither the prenatal nor the current PCDD/F levels showed a relationship with the thyroid parameters in this relatively small group. Conclusion Once again the thyroid hormone metabolism (an increase in T3) seems to have been influenced by current background levels of common environmental contaminants: dl-PCBs and BDE-99. T3 is a product of target organs and abnormalities might indicate effects on hormone transporters and could cause pathology. While the influence on T3 levels may have been compensated, because the adolescents functioned normal at the time of the study period, it is questionable if this compensation is enough for all organs depending on thyroid hormones. PMID:22759492

Does exposure to phthalates influence thyroid function and growth hormone homeostasis? The Taiwan Environmental Survey for Toxicants (TEST) 2013.

PubMed

Huang, Han-Bin; Pan, Wen-Harn; Chang, Jung-Wei; Chiang, Hung-Che; Guo, Yue Leon; Jaakkola, Jouni J K; Huang, Po-Chin

2017-02-01

Previous epidemiologic and toxicological studies provide some inconsistent evidence that exposure to phthalates may affect thyroid function and growth hormone homeostasis. To assess the relations between exposure to phthalates and indicators of thyroid function and growth hormone homeostasis disturbances both among adults and minors. We conducted a population-based cross-sectional study of 279 Taiwanese adults (≥18 years old) and 79 minors (<18 years old) in 2013. Exposure assessment was based on urinary biomarkers, 11 phthalate metabolites measured by using online liquid chromatography/tandem mass spectrometry. Indicators of thyroid function included serum levels of thyroxine (T 4 ), free T 4 , triiodothyronine, thyroid-stimulating hormone, and thyroxine-binding globulin (TBG). Growth hormone homeostasis was measured as the serum levels of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP3). We applied multivariate linear regression models to examine these associations after adjusting for covariates. Among adults, serum T 4 levels were negatively associated with urinary mono-(2-ethyl-5-hydroxyhexyl) phthalate (β=-0.028, P=0.043) and the sum of urinary di-(2-ethylhexyl) phthalate (DEHP) metabolite (β=-0.045, P=0.017) levels. Free T 4 levels were negatively associated with urinary mono-ethylhexyl phthalate (MEHP) (β=-0.013, P=0.042) and mono-(2-ethyl-5-oxohexyl) phthalate (β=-0.030, P=0.003) levels, but positively associated with urinary monoethyl phthalate (β=0.014, P=0.037) after adjustment for age, BMI, gender, urinary creatinine levels, and TBG levels. Postive associations between urinary MEHP levels and IGF-1 levels (β=0.033, P=0.006) were observed. Among minors, free T 4 was positively associated with urinary mono benzyl phthalate levels (β=0.044, P=0.001), and IGF-1 levels were negatively associated with the sum of urinary DEHP metabolite levels (β=-0.166, P=0.041) after adjustment for significant covariance and IGFBP3. Our results are consistent with the hypothesis that exposure to phthalates influences thyroid function and growth hormone homeostasis. Copyright © 2016 Elsevier Inc. All rights reserved.

Free and total thyroid hormones in humans at extreme altitude

NASA Astrophysics Data System (ADS)

Basu, Minakshi; Pal, K.; Malhotra, A. S.; Prasad, R.; Sawhney, R. C.

1995-03-01

Alterations in circulatory levels of total T4 (TT4), total T3 (TT3), free T4 (FT4), free T3 (FT3), thyrotropin (TSH) and T3 uptake (T3U) were studied in male and female sea-level residents (SLR) at sea level, in Armed forces personnel staying at high altitude (3750 m) for prolonged duration (acclimatized lowlanders, ALL) and in high-altitude natives (HAN). Identical studies were also performed on male ALL who trekked to an extreme altitude of 5080 m and stayed at an altitude of more than 6300 m for about 6 months. The total as well as free thyroid hormones were found to be significantly higher in ALL and HAN as compared to SLR values. Both male as well as female HAN had higher levels of thyroid hormones. The rise in hormone levels in different ALL ethnic groups drawn from amongst the southern and northern parts of the country was more or less identical. In both HAN and ALL a decline in FT3 and FT4 occurred when these subjects trekked at subzero temperatures to extreme altitude of 5080 m but the levels were found to be higher in ALL who stayed at 6300 m for a prolonged duration. Plasma TSH did not show any appreciable change at lower altitudes but was found to be decreased at extreme altitude. The increase in thyroid hormones at high altitude was not due to an increase in hormone binding proteins, since T3U was found to be higher at high altitudes. A decline in TSH and hormone binding proteins and an increase in the free moiety of the hormones is indicative of a subtle degree of tissue hyperthyroidism which may be playing an important role in combating the extreme cold and hypoxic environment of high altitudes.

Evaluation of two over-the-counter natural thyroid hormone preparations in human volunteers.

PubMed

Csako, G; Corso, D M; Kestner, J; Bokser, A D; Kennedy, P E; Pucino, F

1992-04-01

To determine the pharmacologic activity of over-the-counter (OTC) thyroid preparations. In vitro analysis and a prospective, crossover study in vivo. Tertiary care center. Two healthy adult volunteers. Three OTC preparations (Thyrotrophin PMG [bovine thyroid PMG extract], Thyro Forte [thyroid lymphogland concentrate with synergistic complex], and Thyro Complex [thyroid lyophilized gland concentrate with synergistic complex]) were analyzed in vitro. Volunteers were administered two times the manufacturer's maximum recommended daily dose of either Thyrotrophin PMG or Thyro Forte for one week, washed out for four to five weeks, and crossed over to receive the opposite tablet preparation for an additional week. The triiodothyronine (T3) and thyroxine (T4) contents of OTC preparations were measured by HPLC. Vital signs, serum total and free T4, total T3, thyroid stimulating hormone, thyroxine binding globulin, thyroglobulin, and general chemistry tests (including glucose and cholesterol) were monitored before, during, and between administration of the products. HPLC analysis of the three OTC preparations showed no T4 but did show possible T3 in two of these products. We found no definite clinical or laboratory evidence of thyroid hormone excess with either product. Healthcare professionals should advise against the use of these scientifically unsound and relatively expensive OTC thyroid preparations, of which the therapeutic efficacy is unknown.

Targeting the thyroid gland with thyroid-stimulating hormone (TSH)-nanoliposomes.

PubMed

Paolino, Donatella; Cosco, Donato; Gaspari, Marco; Celano, Marilena; Wolfram, Joy; Voce, Pasquale; Puxeddu, Efisio; Filetti, Sebastiano; Celia, Christian; Ferrari, Mauro; Russo, Diego; Fresta, Massimo

2014-08-01

Various tissue-specific antibodies have been attached to nanoparticles to obtain targeted delivery. In particular, nanodelivery systems with selectivity for breast, prostate and cancer tissue have been developed. Here, we have developed a nanodelivery system that targets the thyroid gland. Nanoliposomes have been conjugated to the thyroid-stimulating hormone (TSH), which binds to the TSH receptor (TSHr) on the surface of thyrocytes. The results indicate that the intracellular uptake of TSH-nanoliposomes is increased in cells expressing the TSHr. The accumulation of targeted nanoliposomes in the thyroid gland following intravenous injection was 3.5-fold higher in comparison to untargeted nanoliposomes. Furthermore, TSH-nanoliposomes encapsulated with gemcitabine showed improved anticancer efficacy in vitro and in a tumor model of follicular thyroid carcinoma. This drug delivery system could be used for the treatment of a broad spectrum of thyroid diseases to reduce side effects and improve therapeutic efficacy. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Early Phthalates Exposure in Pregnant Women Is Associated with Alteration of Thyroid Hormones

PubMed Central

Tsai, Chih-Hsin; Liang, Wei-Yen; Li, Sih-Syuan; Huang, Han-Bin

2016-01-01

Introduction Previous studies revealed that phthalate exposure could alter thyroid hormones during the last trimester of pregnancy. However, thyroid hormones are crucial for fetal development during the first trimester. We aimed to clarify the effect of phthalate exposure on thyroid hormones during early pregnancy. Method We recruited 97 pregnant women who were offered an amniocentesis during the early trimester from an obstetrics clinic in southern Taiwan from 2013 to 2014. After signing an informed consent form, we collected amniotic fluid and urine samples from pregnant women to analyze 11 metabolites, including mono-ethyl phthalate (MEP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono-(2-ethylhexyl) phthalate (MEHP), mono-butyl phthalate (MnBP), of 9 phthalates using liquid chromatography/ tandem mass spectrometry. We collected blood samples from each subject to analyze serum thyroid hormones including thyroxine (T4), free T4, and thyroid-binding globulin (TBG). Results Three phthalate metabolites were discovered to be >80% in the urine samples of the pregnant women: MEP (88%), MnBP (81%) and MECPP (86%). Median MnBP and MECPP levels in pregnant Taiwanese women were 21.5 and 17.6 μg/g-creatinine, respectively, that decreased after the 2011 Taiwan DEHP scandal. Results of principal component analysis suggested two major sources (DEHP and other phthalates) of phthalates exposure in pregnant women. After adjusting for age, gestational age, TBG, urinary creatinine, and other phthalate metabolites, we found a significantly negative association between urinary MnBP levels and serum T4 (β = –5.41; p-value = 0.012; n = 97) in pregnant women using Bonferroni correction. Conclusion We observed a potential change in the thyroid hormones of pregnant women during early pregnancy after DnBP exposure. Additional study is necessitated to clarify these associations. PMID:27455052

Thyroid hormone analogs for the treatment of dyslipidemia: past, present, and future.

PubMed

Delitala, Alessandro P; Delitala, Giuseppe; Sioni, Paolo; Fanciulli, Giuseppe

2017-11-01

Treatment of dyslipidemia is a major burden for public health. Thyroid hormone regulates lipid metabolism by binding the thyroid hormone receptor (TR), but the use of thyroid hormone to treat dyslipidemia is not indicated due to its deleterious effects on heart, bone, and muscle. Thyroid hormone analogs have been conceived to selectively activate TR in the liver, thus reducing potential side-effects. The authors searched the PubMed database to review TR and the action of thyromimetics in vitro and in animal models. Then, all double-blind, placebo controlled trials that analyzed the use of thyroid hormone analog for the treatment of dyslipidemia in humans were included. Finally, the ongoing research on the use of TR agonists was searched, searching the US National Institutes of Health Registry and the WHO International Clinical Trial Registry Platform (ICTRP). Thyromimetics were tested in humans for the treatment of dyslipidemia, as a single therapeutic agent or as an add-on therapy to the traditional lipid-lowering drugs. In most trials, thyromimetics lowered total cholesterol, low-density lipoprotein cholesterol, and triglycerides, but their use has been associated with adverse side-effects, both in pre-clinical studies and in humans. The use of thyromimetics for the treatment of dyslipidemia is not presently recommended. Future possible clinical applications might include their use to promote weight reduction. Thyromimetics might also represent an interesting alternative, both for the treatment of non-alcoholic steatohepatitis, and type 2 diabetes due to their positive effects on insulin sensitivity. Finally, additional experimental and clinical studies are needed for a better comprehension of the effect(s) of a long-term therapy.

Iodide handling by the thyroid epithelial cell.

PubMed

Nilsson, M

2001-01-01

Iodination of thyroglobulin, the key event in the synthesis of thyroid hormone, is an extracellular process that takes place inside the thyroid follicles at the apical membrane surface that faces the follicular lumen. The supply of iodide involves two steps of TSH-regulated transport, basolateral uptake and apical efflux, that imprint the polarized phenotype of the thyroid cell. Iodide uptake is generated by the sodium/iodide symporter present in the basolateral plasma membrane. A candidate for the apical iodide-permeating mechanism is pendrin, a chloride/iodide transporting protein recently identified in the apical membrane. In physiological conditions, transepithelial iodide transport occurs without intracellular iodination, despite the presence of large amounts of thyroglobulin and thyroperoxidase inside the cells. The reason is that hydrogen peroxide, serving as electron acceptor in iodide-protein binding and normally produced at the apical cell surface, is rapidly degraded by cytosolic glutathione peroxidase once it enters the cells. Iodinated thyroglobulin in the lumen stores not only thyroid hormone but iodine incorporated in iodotyrosine residues as well. After endocytic uptake and degradation of thyroglobulin, intracellular deiodination provides a mechanism for recycling of iodide to participate in the synthesis of new thyroid hormone at the apical cell surface.

Evolution of the nuclear receptor gene superfamily.

PubMed Central

Laudet, V; Hänni, C; Coll, J; Catzeflis, F; Stéhelin, D

1992-01-01

Nuclear receptor genes represent a large family of genes encoding receptors for various hydrophobic ligands such as steroids, vitamin D, retinoic acid and thyroid hormones. This family also contains genes encoding putative receptors for unknown ligands. Nuclear receptor gene products are composed of several domains important for transcriptional activation, DNA binding (C domain), hormone binding and dimerization (E domain). It is not known whether these genes have evolved through gene duplication from a common ancestor or if their different domains came from different independent sources. To test these possibilities we have constructed and compared the phylogenetic trees derived from two different domains of 30 nuclear receptor genes. The tree built from the DNA binding C domain clearly shows a common progeny of all nuclear receptors, which can be grouped into three subfamilies: (i) thyroid hormone and retinoic acid receptors, (ii) orphan receptors and (iii) steroid hormone receptors. The tree constructed from the central part of the E domain which is implicated in transcriptional regulation and dimerization shows the same distribution in three subfamilies but two groups of receptors are in a different position from that in the C domain tree: (i) the Drosophila knirps family genes have acquired very different E domains during evolution, and (ii) the vitamin D and ecdysone receptors, as well as the FTZ-F1 and the NGF1B genes, seem to have DNA binding and hormone binding domains belonging to different classes. These data suggest a complex evolutionary history for nuclear receptor genes in which gene duplication events and swapping between domains of different origins took place. PMID:1312460

Genetically modified mouse models to investigate thyroid development, function and growth.

PubMed

Löf, C; Patyra, K; Kero, A; Kero, J

2018-06-01

The thyroid gland produces thyroid hormones (TH), which are essential regulators for growth, development and metabolism. The thyroid is mainly controlled by the thyroid-stimulating hormone (TSH) that binds to its receptor (TSHR) on thyrocytes and mediates its action via different G protein-mediated signaling pathways. TSH primarily activates the G s -pathway, and at higher concentrations also the G q/11 -pathway, leading to an increase of intracellular cAMP and Ca 2+ , respectively. To date, the physiological importance of other G protein-mediated signaling pathways in thyrocytes is unclear. Congenital hypothyroidism (CH) is defined as the lack of TH at birth. In familial cases, high-throughput sequencing methods have facilitated the identification of novel mutations. Nevertheless, the precise etiology of CH yet remains unraveled in a proportion of cases. Genetically modified mouse models can reveal new pathophysiological mechanisms of thyroid diseases. Here, we will present an overview of genetic mouse models for thyroid diseases, which have provided crucial insights into thyroid gland development, function, and growth with a special focus on TSHR and microRNA signaling. Copyright © 2018 Elsevier Ltd. All rights reserved.

Antitumor Responses Stimulated by Dendritic Cells Are Improved by Triiodothyronine Binding to the Thyroid Hormone Receptor β.

PubMed

Alamino, Vanina A; Mascanfroni, Iván D; Montesinos, María M; Gigena, Nicolás; Donadio, Ana C; Blidner, Ada G; Milotich, Sonia I; Cheng, Sheue-Yann; Masini-Repiso, Ana M; Rabinovich, Gabriel A; Pellizas, Claudia G

2015-04-01

Bidirectional cross-talk between the neuroendocrine and immune systems orchestrates immune responses in both physiologic and pathologic settings. In this study, we provide in vivo evidence of a critical role for the thyroid hormone triiodothyronine (T3) in controlling the maturation and antitumor functions of dendritic cells (DC). We used a thyroid hormone receptor (TR) β mutant mouse (TRβPV) to establish the relevance of the T3-TRβ system in vivo. In this model, TRβ signaling endowed DCs with the ability to stimulate antigen-specific cytotoxic T-cell responses during tumor development. T3 binding to TRβ increased DC viability and augmented DC migration to lymph nodes. Moreover, T3 stimulated the ability of DCs to cross-present antigens and to stimulate cytotoxic T-cell responses. In a B16-OVA mouse model of melanoma, vaccination with T3-stimulated DCs inhibited tumor growth and prolonged host survival, in part by promoting the generation of IFNγ-producing CD8(+) T cells. Overall, our results establish an adjuvant effect of T3-TRβ signaling in DCs, suggesting an immediately translatable method to empower DC vaccination approaches for cancer immunotherapy. ©2015 American Association for Cancer Research.

Identification of thyroid hormone receptor binding sites and target genes using ChIP-on-chip in developing mouse cerebellum.

PubMed

Dong, Hongyan; Yauk, Carole L; Rowan-Carroll, Andrea; You, Seo-Hee; Zoeller, R Thomas; Lambert, Iain; Wade, Michael G

2009-01-01

Thyroid hormone (TH) is critical to normal brain development, but the mechanisms operating in this process are poorly understood. We used chromatin immunoprecipitation to enrich regions of DNA bound to thyroid receptor beta (TRbeta) of mouse cerebellum sampled on post natal day 15. Enriched target was hybridized to promoter microarrays (ChIP-on-chip) spanning -8 kb to +2 kb of the transcription start site (TSS) of 5000 genes. We identified 91 genes with TR binding sites. Roughly half of the sites were located in introns, while 30% were located within 1 kb upstream (5') of the TSS. Of these genes, 83 with known function included genes involved in apoptosis, neurodevelopment, metabolism and signal transduction. Two genes, MBP and CD44, are known to contain TREs, providing validation of the system. This is the first report of TR binding for 81 of these genes. ChIP-on-chip results were confirmed for 10 of the 13 binding fragments using ChIP-PCR. The expression of 4 novel TH target genes was found to be correlated with TH levels in hyper/hypothyroid animals providing further support for TR binding. A TRbeta binding site upstream of the coding region of myelin associated glycoprotein was demonstrated to be TH-responsive using a luciferase expression system. Motif searches did not identify any classic binding elements, indicating that not all TR binding sites conform to variations of the classic form. These findings provide mechanistic insight into impaired neurodevelopment resulting from TH deficiency and a rich bioinformatics resource for developing a better understanding of TR binding.

Ovarian ultrasound and ovarian and adrenal hormones before and after treatment for hyperthyroidism.

PubMed

Skjöldebrand Sparre, L; Kollind, M; Carlström, K

2002-01-01

To relate thyroid, steroid and pituitary hormones to ovarian ultrasonographic findings in hyperthyroid patients before and during treatment. Ultrasonography of the ovaries and serum hormone determination by immunoassay were performed before and during thiamazole therapy in 18 women of fertile age treated for hyperthyroidism at the Danderyd Hospital from 1996 to 1998. When hyperthyreotic, the patients had elevated serum levels of sex hormone-binding globulin (SHBG) and subnormal values of cortisol, free testosterone (fT) and dehydroepiandrosterone (DHEA). In the euthyreotic state following treatment, endocrine variables were normalized. Patients with a short duration of the disease had higher pretreatment levels of free thyroxine (fT4), SHBG and testosterone and lower corticosteroid binding globulin (CBG) and cortisol levels compared to patients with a long duration of the disease. The pretreatment ultrasonographic picture was abnormal in 16 of 18 patients. Of the 8 patients who were examined by ultrasonography after 3 months of treatment, all but 1 showed a normal picture. Samples from patients showing an abnormal ultrasonographic picture had significantly higher fT4 and lower free testosterone (fT) values than samples from patients with a normal ultrasonographic picture. Ultrasonographic findings showing a multicystic/multifollicular picture, resembling polycystic ovaries (PCO), in hyperthyroidism may be related to direct effects of thyroid hormones on the ovaries and/or altered intraovarian androgen environment due to elevated SHBG levels. It is highly recommended to assess the thyroid status in patients with multicystic/multifollicular ovaries/PCO. Copyright 2002 S. Karger AG, Basel

Complex Actions of Thyroid Hormone Receptor Antagonist NH-3 on Gene Promoters in Different Cell Lines

PubMed Central

Shah, Vanya; Nguyen, Phuong; Nguyen, Ngoc-Ha; Togashi, Marie; Scanlan, Thomas S.; Baxter, John D.; Webb, Paul

2014-01-01

It is desirable to obtain new antagonists for thyroid hormone (TRs) and other nuclear receptors (NRs). We previously used X-ray structural models of TR ligand binding domains (LBDs) to design compounds, such as NH-3, that impair coactivator binding to activation function 2 (AF-2) and block thyroid hormone (triiodothyronine, T3) actions. However, TRs bind DNA and are transcriptionally active without ligand. Thus, NH-3 could modulate TR activity via effects on other coregulator interaction surfaces, such as activation function (AF-1) and corepressor binding sites. Here, we find that NH-3 blocks TR-LBD interactions with coactivators and corepressors and also inhibits activities of AF-1 and AF-2 in transfections. While NH-3 lacks detectable agonist activity at T3-activated genes in GC pituitary cells it nevertheless activates spot 14 (S14) in HTC liver cells with the latter effect accompanied by enhanced histone H4 acetylation and coactivator recruitment at the S14 promoter. Surprisingly, T3 promotes corepressor recruitment to target promoters. NH-3 effects vary; we observe transient recruitment of N-CoR to S14 in GC cells and dismissal and rebinding of N-CoR to the same promoter in HTC cells. We propose that NH-3 will generally behave as an antagonist by blocking AF-1 and AF-2 but that complex effects on coregulator recruitment may result in partial/mixed agonist effects that are independent of blockade of T3 binding in some contexts. These properties could ultimately be utilized in drug design and development of new selective TR modulators. PMID:18930112

Thyrotoxicosis presenting as hypogonadism: a case of central hyperthyroidism.

PubMed

Childress, R Dale; Qureshi, M Nauman; Kasparova, Meri; Oktaei, Hooman; Williams-Cleaves, Beverly; Solomon, Solomon S

2004-11-01

Herein, we present a case of central thyrotoxicosis with well-documented serial therapeutic interventions. Thyroid-stimulating hormone (TSH)-secreting pituitary tumors represent a rare cause of hyperthyroidism. It is being diagnosed more frequently with the third-generation TSH assay. Many conditions can produce normal or elevated TSH levels in combination with elevated thyroid hormone levels. The differential diagnosis includes resistance to thyroid hormone (RTH, Refetoff's syndrome), assay interference from anti-T4/T3 and heterophile antibodies, elevated or altered binding proteins, drugs affecting peripheral metabolism, and noncompliance with thyroid replacement therapy. In contrast to RTH, our patient presented had high alpha-subunit-to-TSH molar ratio, failed TSH response to thyrotropin-releasing hormone stimulation, and a large pituitary mass. Normal or high TSH in the presence of elevated T4 or T3 is a fairly common clinical scenario with many etiologic possibilities. This TSH-producing adenoma represents an unusual initial clinical presentation, as hypogonadism appeared before features of thyrotoxicosis were appreciated. This case represents the most modern therapeutic approach to the management of this rare disease. Our patient has done well on octreotide with control of thyrotoxicosis and an additional 30% shrinkage of his tumor mass.

NFE2-Related Transcription Factor 2 Coordinates Antioxidant Defense with Thyroglobulin Production and Iodination in the Thyroid Gland.

PubMed

Ziros, Panos G; Habeos, Ioannis G; Chartoumpekis, Dionysios V; Ntalampyra, Eleni; Somm, Emmanuel; Renaud, Cédric O; Bongiovanni, Massimo; Trougakos, Ioannis P; Yamamoto, Masayuki; Kensler, Thomas W; Santisteban, Pilar; Carrasco, Nancy; Ris-Stalpers, Carrie; Amendola, Elena; Liao, Xiao-Hui; Rossich, Luciano; Thomasz, Lisa; Juvenal, Guillermo J; Refetoff, Samuel; Sykiotis, Gerasimos P

2018-06-01

The thyroid gland has a special relationship with oxidative stress. While generation of oxidative substances is part of normal iodide metabolism during thyroid hormone synthesis, the gland must also defend itself against excessive oxidation in order to maintain normal function. Antioxidant and detoxification enzymes aid thyroid cells to maintain homeostasis by ameliorating oxidative insults, including during exposure to excess iodide, but the factors that coordinate their expression with the cellular redox status are not known. The antioxidant response system comprising the ubiquitously expressed NFE2-related transcription factor 2 (Nrf2) and its redox-sensitive cytoplasmic inhibitor Kelch-like ECH-associated protein 1 (Keap1) defends tissues against oxidative stress, thereby protecting against pathologies that relate to DNA, protein, and/or lipid oxidative damage. Thus, it was hypothesized that Nrf2 should also have important roles in maintaining thyroid homeostasis. Ubiquitous and thyroid-specific male C57BL6J Nrf2 knockout (Nrf2-KO) mice were studied. Plasma and thyroids were harvested for evaluation of thyroid function tests by radioimmunoassays and of gene and protein expression by real-time polymerase chain reaction and immunoblotting, respectively. Nrf2-KO and Keap1-KO clones of the PCCL3 rat thyroid follicular cell line were generated using CRISPR/Cas9 technology and were used for gene and protein expression studies. Software-predicted Nrf2 binding sites on the thyroglobulin enhancer were validated by site-directed in vitro mutagenesis and chromatin immunoprecipitation. The study shows that Nrf2 mediates antioxidant transcriptional responses in thyroid cells and protects the thyroid from oxidation induced by iodide overload. Surprisingly, it was also found that Nrf2 has a dramatic impact on both the basal abundance and the thyrotropin-inducible intrathyroidal abundance of thyroglobulin (Tg), the precursor protein of thyroid hormones. This effect is mediated by cell-autonomous regulation of Tg gene expression by Nrf2 via its direct binding to two evolutionarily conserved antioxidant response elements in an upstream enhancer. Yet, despite upregulating Tg levels, Nrf2 limits Tg iodination both under basal conditions and in response to excess iodide. Nrf2 exerts pleiotropic roles in the thyroid gland to couple cell stress defense mechanisms to iodide metabolism and the thyroid hormone synthesis machinery, both under basal conditions and in response to excess iodide.

WOMEN IN CANCER THEMATIC REVIEW: Thyroid-stimulating hormone in thyroid cancer: does it matter?

PubMed

Nieto, Hannah; Boelaert, Kristien

2016-11-01

Differentiated thyroid cancer is the most common endocrine malignancy and the incidence is increasing rapidly worldwide. Appropriate diagnosis and post-treatment monitoring of patients with thyroid tumours are critical. Fine needle aspiration cytology remains the gold standard for diagnosing thyroid cancer, and although there have been significant refinements to this technique, diagnostic surgery is often required for patients suspected to have malignancy. Serum thyroid-stimulating hormone (TSH) is higher in patients with malignant thyroid nodules than in those with benign disease, and TSH is proportionally increased in more aggressive tumours. Importantly, we have shown that the pre-operative serum TSH concentration independently predicts the presence of malignancy in subjects presenting with thyroid nodules. Establishing the use of TSH measurements in algorithms identifying high-risk thyroid nodules in routine clinical practice represents an exciting, cost-efficient and non-invasive approach to optimise thyroid cancer diagnosis. Binding of TSH to receptors on thyrocytes stimulates a number of growth promoting pathways both in normal and malignant thyroid cells, and TSH suppression with high doses of levothyroxine is routinely used after thyroidectomy to prevent cancer recurrence, especially in high-risk tumours. This review examines the relationship between serum TSH and thyroid cancer and reflects on the clinical potential of TSH measurements in diagnosis and disease monitoring. © 2016 Society for Endocrinology.

The evolutionary and integrative roles of transthyretin in thyroid hormone homeostasis.

PubMed

Schreiber, G

2002-10-01

In larger mammals, thyroid hormone-binding plasma proteins are albumin, transthyretin (TTR) and thyroxine (T4)-binding globulin. They differ characteristically in affinities and release rates for T4 and triiodothyronine (T3). Together, they form a 'buffering' system counteracting thyroid hormone permeation from aqueous to lipid phases. Evolution led to important differences in the expression pattern of these three proteins in tissues. In adult liver, TTR is only made in eutherians and herbivorous marsupials. During development, it is also made in tadpole and fish liver. More intense TTR synthesis than in liver is found in the choroid plexus of reptilians, birds and mammals, but none in the choroid plexus of amphibians and fish, i.e. species without a neocortex. All brain-made TTR is secreted into the cerebrospinal fluid, where it becomes the major thyroid hormone-binding protein. During ontogeny, the maximum TTR synthesis in the choroid plexus precedes that of the growth rate of the brain and occurs during the period of maximum neuroblast replication. TTR is only one component in a network of factors determining thyroid hormone distribution. This explains why, under laboratory conditions, TTR-knockout mice show no major abnormalities. The ratio of TTR affinity for T4 over affinity for T3 is higher in eutherians than in reptiles and birds. This favors T4 transport from blood to brain providing more substrate for conversion of the biologically less active T4 into the biologically more active T3 by the tissue-specific brain deiodinases. The change in affinity of TTR during evolution involves a shortening and an increase in the hydrophilicity of the N-terminal regions of the TTR subunits. The molecular mechanism for this change is a stepwise shift of the splice site at the intron 1/exon 2 border of the TTR gene. The shift probably results from a sequence of single base mutations. Thus, TTR evolution provides an example for a molecular mechanism of positive Darwinian evolution. The amino acid sequences of fish and amphibian TTRs are very similar to those in mammals, suggesting that substantial TTR evolution occurred before the vertebrate stage. Open reading frames for TTR-like sequences already exist in Caenorhabditis elegans, yeast and Escherichia coli genomes.

Modulation of thyroid hormone receptors by non-thyroidal stimuli

DOE Office of Scientific and Technical Information (OSTI.GOV)

ErkenBrack, D.E.; Clemons, G.K.

1988-01-01

The ability of non-thyroidal stimuli to affect the binding affinity and capacity of solubilized nuclear receptors for thyroid hormones was studied in a normal homeostatic system (erythropoiesis) and a pathobiologic one (lung-ozone interaction). No significant effects on affinity were found, as Kd control values for receptors derived from rat bone marrow averaged 57 (+/- 28) pM while experimental (hypoxic) values averaged 89 (+/- 55) pM. Kd control values in rat lung were found to average 142 (+/- 22) pM while average values derived from experimental protocols with ozone and methimazole were 267 (+/- 44) pM and 161 (+/- 35) pMmore » respectively. Finally, Kd control values for receptors derived from cultured MEL cells averaged 19 (+/- 2.6) pM while experimental values during exposure to DMSO or IGF1 were 23 (+/- 3.6) pM and 26 (+/- 11) pM respectively. In contrast, binding capacity (expressed as fmoles of hormone bound per unit protein of solubilized receptor) was markedly perturbed in several tissues by various agents: ozone effects on lung were shown by an average control value of 3.3 (+/- 0.4) as opposed to an experimental average of 28 (+/- 1.9); and hypoxia effects on erythroid tissue were displayed by an average control value of 0.7 (+/- 0.07) as opposed to the experimental figure of 1.8 (+/- 0.03). In cultured MEL cells, binding capacity was seen to be increased from control values of 388 (+/- 15) sites/cell to 1243 (+/- 142) sites/cell after DMSO exposure and 2002 (+/- 10) sites/cell after IGF1 exposure. Parallel experiments done with receptors derived from rat liver yielded values similar to those reported by other investigators and were unaffected by the experimental agents.« less

Pesticides in mixture disrupt metabolic regulation: in silico and in vivo analysis of cumulative toxicity of mancozeb and imidacloprid on body weight of mice.

PubMed

Bhaskar, Rakesh; Mohanty, Banalata

2014-09-01

Pesticides acting as endocrine disrupting chemicals disrupt the homeostasis of body metabolism. The present study elucidated that the low dose coexposure of thyroid disrupting dithiocarbamate fungicide mancozeb (MCZ) and neonicotinoid insecticide imidacloprid (IMI) during lactation increased the risk of body weight gain in mice later in life. Body weight gain has been linked to pesticide-induced hypothyroidism and hyperprolactinemia and alteration of lipid profiles. In vivo results were substantiated with in silico molecular docking (MD) analysis that predicted the binding affinity of pesticides with thyroid hormone receptors (TRα and TRβ) and peroxisome proliferator activated receptor gamma (PPARγ), the major nuclear receptors of peripheral fat metabolism. Binding potency of MCZ and IMI was compared with that of T3, and its antagonist ethylene thiourea (ETU) as well as PPARγ agonist (rosiglitazone) and antagonist (HL005). MD simulation predicted that both MCZ and IMI may compete with T3 for binding with TRs. Imidazole group of IMI formed hydrogen bonds with TRs like that of ETU. MCZ may compete with rosiglitazone and HL005 for PPARγ, but IMI showed no affinity. Thus while both MCZ and IMI could disrupt the TRs functioning, MCZ alone may affect PPARγ. Coexposure of pesticides decreased the plasma thyroid hormones and increased the cholesterol and triglyceride. Individual pesticide exposure in low dose might not exert the threshold response to affect the receptors signaling further to cause hormonal/metabolic impairment. Thus, cumulative response of the mixture of thyroid disrupting pesticides can disrupt metabolic regulation through several pathways and contribute to gain in body weight. Copyright © 2014 Elsevier Inc. All rights reserved.

The role of polyhalogenated aromatic hydrocarbons on thyroid hormone disruption and cognitive function: a review.

PubMed

Builee, T L; Hatherill, J R

2004-11-01

Thyroid hormones (TH) are essential to normal brain development, influencing behavior and cognitive function in both adult and children. It is suggested that conditions found in TH abnormalities such as hypothyroidism, hyperthyroidism and generalized resistance to thyroid hormone (GRTH) share symptomatic behavioral impulses found in cases of attention deficit hyperactivity disorder (ADHD) and other cognitive disorders. Disrupters of TH are various and prevalent in the environment. This paper reviews the mechanisms of TH disruption caused by the general class of polyhalogenated aromatic hydrocarbons (PHAH)'s acting as thyroid disrupters (TD). PHAHs influence the hypothalamus-pituitary-thyroid (HPT) axis, as mimicry agents affecting synthesis and secretion of TH. Exposure to PHAH induces liver microsomal enzymes UDP-glucuronosyltransferase (UGT) resulting in accelerated clearance of TH. PHAHs can compromise function of transport and receptor binding proteins such as transthyretin and aryl hydrocarbon receptors (Ahr). Glucose metabolism and catecholamine synthesis are disrupted in the brain by the presence of PHAH. Further, PHAH can alter brain growth and development by perturbing cytoskeletal formation, thereby affecting neuronal migration, elongation and branching. The complex relationships between PHAH and cognitive function are examined in regard to the disruption of T4 regulation in the hypothalamus-pituitary-thyroid axis, blood, brain, neurons, liver and pre and postnatal development.

[A 35-year-old man with gynaecomastia as the first symptom of hyperthyroidism].

PubMed

Mullens, A; van den Bruel, A; Vanderschueren, D

2002-02-02

A 35-year-old man suffered painful bilateral gynaecomastia for 2 months due to serious Graves' hyperthyroidism. During treatment with propylthiouracil and levothyroxine, the plasma concentrations of thyroid hormone, sex hormones and sex hormone-binding globulin normalised and the gynaecomastia disappeared. Gynaecomastia occurs in 30 to 40% of men diagnosed with Graves' hyperthyroidism. However, gynaecomastia as a presenting symptom of this autoimmune disease is uncommon.

Transcriptional activation by the thyroid hormone receptor through ligand-dependent receptor recruitment and chromatin remodelling.

PubMed

Grøntved, Lars; Waterfall, Joshua J; Kim, Dong Wook; Baek, Songjoon; Sung, Myong-Hee; Zhao, Li; Park, Jeong Won; Nielsen, Ronni; Walker, Robert L; Zhu, Yuelin J; Meltzer, Paul S; Hager, Gordon L; Cheng, Sheue-yann

2015-04-28

A bimodal switch model is widely used to describe transcriptional regulation by the thyroid hormone receptor (TR). In this model, the unliganded TR forms stable, chromatin-bound complexes with transcriptional co-repressors to repress transcription. Binding of hormone dissociates co-repressors and facilitates recruitment of co-activators to activate transcription. Here we show that in addition to hormone-independent TR occupancy, ChIP-seq against endogenous TR in mouse liver tissue demonstrates considerable hormone-induced TR recruitment to chromatin associated with chromatin remodelling and activated gene transcription. Genome-wide footprinting analysis using DNase-seq provides little evidence for TR footprints both in the absence and presence of hormone, suggesting that unliganded TR engagement with repressive complexes on chromatin is, similar to activating receptor complexes, a highly dynamic process. This dynamic and ligand-dependent interaction with chromatin is likely shared by all steroid hormone receptors regardless of their capacity to repress transcription in the absence of ligand.

Endoplasmic reticulum stress inhibits expression of genes involved in thyroid hormone synthesis and their key transcriptional regulators in FRTL-5 thyrocytes

PubMed Central

Wen, Gaiping; Eder, Klaus

2017-01-01

Endoplasmic reticulum (ER) stress is characterized by the accumulation of misfolded proteins due to an impairment of ER quality control pathways leading to the activation of a defense system, called unfolded protein response (UPR). While thyrocytes are supposed to be highly susceptible to environmental conditions that cause ER stress due to the synthesis of large amounts of secretory proteins required for thyroid hormone synthesis, systematic investigations on the effect of ER stress on expression of key genes of thyroid hormone synthesis and their transcriptional regulators are lacking. Since the aim of the ER stress-induced UPR is to restore ER homeostasis and to facilitate cell survival through transient shutdown of ribosomal protein translation, we hypothesized that the expression of genes involved in thyroid hormone synthesis and their transcriptional regulators, all of which are not essential for cell survival, are down-regulated in thyrocytes during ER stress, while sterol regulatory element-binding proteins (SREBPs) are activated during ER stress in thyrocytes. Treatment of FRTL-5 thyrocytes with the ER stress inducer tunicamycin (TM) dose-dependently increased the mRNA and/or protein levels of known UPR target genes, stimulated phosphorylation of the ER stress sensor protein kinase RNA-like ER kinase (PERK) and of the PERK target protein eukaryotic initiation factor 2α (eIF2α) and caused splicing of the ER stress-sensitive transcription factor X-box binding protein (XBP-1) (P < 0.05). The mRNA levels and/or protein levels of genes involved in thyroid hormone synthesis, sodium/iodide symporter (NIS), thyroid peroxidase (TPO) and thyroglobulin (TG), their transcriptional regulators and thyrotropin (TSH) receptor and the uptake of Na125I were reduced at the highest concentration of TM tested (0.1 μg/mL; P < 0.05). Proteolytic activation of the SREBP-1c pathway was not observed in FRTL-5 cells treated with TM, whereas TM reduced proteolytic activation of the SREBP-2 pathway at 0.1 μg TM/mL (P < 0.05). In conclusion, the expression of key genes involved in thyroid hormone synthesis and their critical regulators and of the TSH receptor as well as the uptake of iodide is attenuated in thyrocytes during mild ER stress. Down-regulation of NIS, TPO and TG during ER stress is likely the consequence of impaired TSH/TSHR signaling in concert with reduced expression of critical transcriptional regulators of these genes. PMID:29095946

Endoplasmic reticulum stress inhibits expression of genes involved in thyroid hormone synthesis and their key transcriptional regulators in FRTL-5 thyrocytes.

PubMed

Wen, Gaiping; Ringseis, Robert; Eder, Klaus

2017-01-01

Endoplasmic reticulum (ER) stress is characterized by the accumulation of misfolded proteins due to an impairment of ER quality control pathways leading to the activation of a defense system, called unfolded protein response (UPR). While thyrocytes are supposed to be highly susceptible to environmental conditions that cause ER stress due to the synthesis of large amounts of secretory proteins required for thyroid hormone synthesis, systematic investigations on the effect of ER stress on expression of key genes of thyroid hormone synthesis and their transcriptional regulators are lacking. Since the aim of the ER stress-induced UPR is to restore ER homeostasis and to facilitate cell survival through transient shutdown of ribosomal protein translation, we hypothesized that the expression of genes involved in thyroid hormone synthesis and their transcriptional regulators, all of which are not essential for cell survival, are down-regulated in thyrocytes during ER stress, while sterol regulatory element-binding proteins (SREBPs) are activated during ER stress in thyrocytes. Treatment of FRTL-5 thyrocytes with the ER stress inducer tunicamycin (TM) dose-dependently increased the mRNA and/or protein levels of known UPR target genes, stimulated phosphorylation of the ER stress sensor protein kinase RNA-like ER kinase (PERK) and of the PERK target protein eukaryotic initiation factor 2α (eIF2α) and caused splicing of the ER stress-sensitive transcription factor X-box binding protein (XBP-1) (P < 0.05). The mRNA levels and/or protein levels of genes involved in thyroid hormone synthesis, sodium/iodide symporter (NIS), thyroid peroxidase (TPO) and thyroglobulin (TG), their transcriptional regulators and thyrotropin (TSH) receptor and the uptake of Na125I were reduced at the highest concentration of TM tested (0.1 μg/mL; P < 0.05). Proteolytic activation of the SREBP-1c pathway was not observed in FRTL-5 cells treated with TM, whereas TM reduced proteolytic activation of the SREBP-2 pathway at 0.1 μg TM/mL (P < 0.05). In conclusion, the expression of key genes involved in thyroid hormone synthesis and their critical regulators and of the TSH receptor as well as the uptake of iodide is attenuated in thyrocytes during mild ER stress. Down-regulation of NIS, TPO and TG during ER stress is likely the consequence of impaired TSH/TSHR signaling in concert with reduced expression of critical transcriptional regulators of these genes.

Hydroxylated polybrominated diphenyl ethers exhibit different activities on thyroid hormone receptors depending on their degree of bromination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Xiao-Min, E-mail: rxm200318@gmail.com; Guo, Liang-Hong, E-mail: LHGuo@rcees.ac.cn; Gao, Yu, E-mail: francesscototti@gmail.com

2013-05-01

Polybrominated diphenyl ethers (PBDEs) have been shown to disrupt thyroid hormone (TH) functions in experimental animals, and one of the proposed disruption mechanisms is direct binding of hydroxylated PBDE (OH-PBDE) to TH receptors (TRs). However, previous data on TH receptor binding and TH activity of OH-PBDEs were very limited and sometimes inconsistent. In the present paper, we examined the binding potency of ten OH-PBDEs with different degrees of bromination to TR using a fluorescence competitive binding assay. The results showed that the ten OH-PBDEs bound to TR with potency that correlated to their bromination level. We further examined their effectmore » on TR using a coactivator binding assay and GH3 cell proliferation assay. Different TR activities of OH-PBDEs were observed depending on their degree of bromination. Four low-brominated OH-PBDEs (2′-OH-BDE-28, 3′-OH-BDE-28, 5-OH-BDE-47, 6-OH-BDE-47) were found to be TR agonists, which recruited the coactivator peptide and enhanced GH3 cell proliferation. However, three high-brominated OH-PBDEs (3-OH-BDE-100, 3′-OH-BDE-154, 4-OH-BDE-188) were tested to be antagonists. Molecular docking was employed to simulate the interactions of OH-PBDEs with TR and identify the structural determinants for TR binding and activity. According to the docking results, low-brominated OH-PBDEs, which are weak binders but TR agonists, bind with TR at the inner side of its binding pocket, whereas high-brominated compounds, which are potent binders but TR antagonists, reside at the outer region. These results indicate that OH-PBDEs have different activities on TR (agonistic or antagonistic), possibly due to their different binding geometries with the receptor. - Highlights: ► Thyroid hormone (TH) activity of OH-PBDEs with different Br number was evaluated. ► Four different experimental approaches were employed to investigate the mechanism. ► Low-brominated OH-PBDEs were agonists, but high-brominated ones were antagonists. ► Low-brominated OH-PBDEs bind to TH receptor differently than high-brominated ones.« less

The effect of growth hormone replacement on the thyroid axis in patients with hypopituitarism: in vivo and ex vivo studies.

PubMed

Glynn, Nigel; Kenny, Helena; Quisenberry, Leah; Halsall, David J; Cook, Paul; Kyaw Tun, Tommy; McDermott, John H; Smith, Diarmuid; Thompson, Christopher J; O'Gorman, Donal J; Boelen, Anita; Lado-Abeal, Joaquin; Agha, Amar

2017-05-01

Alterations in the hypothalamic-pituitary-thyroid axis have been reported following growth hormone (GH) replacement. The aim was to examine the relationship between changes in serum concentration of thyroid hormones and deiodinase activity in subcutaneous adipose tissue, before and after GH replacement. A prospective, observational study of patients receiving GH replacement as part of routine clinical care. Twenty adult hypopituitary men. Serum TSH, thyroid hormones - free and total thyroxine (T4) and triiodothyronine (T3) and reverse T3, thyroglobulin and thyroid-binding globulin (TBG) levels were measured before and after GH substitution. Changes in serum hormone levels were compared to the activity of deiodinase isoenzymes (DIO1, DIO2 and DIO3) in subcutaneous adipose tissue. The mean daily dose of growth hormone (GH) was 0·34 ± 0·11 mg (range 0·15-0·5 mg). Following GH replacement, mean free T4 levels declined (-1·09 ± 1·99 pmol/l, P = 0·02). Reverse T3 levels also fell (-3·44 ± 1·42 ng/dl, P = 0·03) and free T3 levels increased significantly (+0·34 ± 0·15 pmol/l, P = 0·03). In subcutaneous fat, DIO2 enzyme activity declined; DIO1 and DIO3 activities remained unchanged following GH substitution. Serum TSH, thyroglobulin and TBG levels were unaltered by GH therapy. In vitro analysis of subcutaneous adipose tissue from hypopituitary human subjects demonstrates that GH replacement is associated with significant changes in deiodinase isoenzyme activity. However, the observed variation in enzyme activity does not explain the changes in the circulating concentration of thyroid hormones induced by GH replacement. It is possible that deiodinase isoenzymes are differentially regulated by GH in other tissues including liver and muscle. © 2016 John Wiley & Sons Ltd.

Thyroid Hormone Receptor β (THRB) Is a Major Target Gene for MicroRNAs Deregulated in Papillary Thyroid Carcinoma (PTC)

PubMed Central

Boguslawska, Joanna; Jendrzejewski, Jaroslaw; Liyanarachchi, Sandya; Pachucki, Janusz; Wardyn, Kazimierz A.; Nauman, Alicja

2011-01-01

Context: Loss of the thyroid hormone receptor is common in tumors. In mouse models, a truncated THRB gene leads to thyroid cancer. Previously, we observed up-regulation of the expression of eight microRNAs (miRs) in papillary thyroid carcinoma (PTC) tumors. Objective: Our objective was to determine whether THRB might be inhibited by miRs up-regulated in PTC. Design: The potential binding of miR to the 3′-untranslated region of THRB was analyzed in silico. Direct inhibition by miRs binding to the cloned 3′-untranslated region of THRB was evaluated using luciferase assays. Inhibition of endogenous THRB and its target genes (DIO1 and APP) was examined in cell lines transfected by pre-miRs. The impact on thyroid hormone response element (TRE) was evaluated in promoter assays. Correlations between the expression of THRB and miRs was evaluated in 13 PTC tumor/normal tissue pairs. Results: THRB contains binding sites for the top seven miRs up-regulated in PTC (P = 0.0000002). Direct interaction with THRB was shown for miR-21 and miR-146a. We observed lower levels of THRB transcripts in cell lines transfected with miR-21, -146a, and -221 (down-regulation of 37–48%; P < 0.0001), but not with miR-181a. THRB protein was suppressed down to 10–28% by each of four miRs. Concomitant expression of DIO1 and APP was affected (down-regulation of 32–66%, P < 0.0034 and up-regulation of 48–57%, P < 0.0002, respectively). All four miRs affected TRE activity in promoter assays. Down-regulation of luciferase occurred after transfection with pTRE-TK-Luc construct and each of four miRs. The analysis of tumor/normal tissue pairs revealed down-regulation of THRB in 11 of 13 pairs (1.3- to 9.1-fold), and up-regulation of miR-21, -146a, -181a, and -221 in almost all pairs. Conclusions: MiRs up-regulated in PTC tumors directly inhibit the expression of THRB, an important tumor suppressor gene. PMID:21159845

Thyroid hormones in the elderly sick: "T4 euthyroidism".

PubMed

Burrows, A W; Shakespear, R A; Hesch, R D; Cooper, E; Aickin, C M; Burke, C W

1975-11-22

Thyroid function and serum levels of triiodothyronine (T3) and thyroxine (T4) were investigated in 79 euthyroid geriatric patients. Of the 59 inpatients and 20 outpatients 35 (59%) and 2, respectively, had low T3 levels. In contrast, 7 (12%) and 6 (30%), respectively, had raised T4 levels. Two further patients were excluded from the study because of raised levels of thyroid-stimulating hormone. Thyroxine-binding globulin was greatly increased in both groups of patients, but low serum albumin levels were present in 31 (39%). Despite these changes free T3 and T4 indices closely followed total T3 and T4 levels. The difference between the two groups of patients did not correlate with body weight, diagnostic categories, age, drug treatment, or duration of stay in hospital.

Thyroid hormones in the elderly sick: "T4 euthyroidism".

PubMed Central

Burrows, A W; Shakespear, R A; Hesch, R D; Cooper, E; Aickin, C M; Burke, C W

1975-01-01

Thyroid function and serum levels of triiodothyronine (T3) and thyroxine (T4) were investigated in 79 euthyroid geriatric patients. Of the 59 inpatients and 20 outpatients 35 (59%) and 2, respectively, had low T3 levels. In contrast, 7 (12%) and 6 (30%), respectively, had raised T4 levels. Two further patients were excluded from the study because of raised levels of thyroid-stimulating hormone. Thyroxine-binding globulin was greatly increased in both groups of patients, but low serum albumin levels were present in 31 (39%). Despite these changes free T3 and T4 indices closely followed total T3 and T4 levels. The difference between the two groups of patients did not correlate with body weight, diagnostic categories, age, drug treatment, or duration of stay in hospital. PMID:811313

Triiodothyronine enhances accumulation of intracellular lipids in adipocytes through thyroid hormone receptor α via direct and indirect mechanisms.

PubMed

Gambo, Yurina; Matsumura, Miki; Fujimori, Ko

2016-08-15

Triiodothyronine (T3) enhanced the expression of adipogenic and lipogenic genes with elevation of the intracellular lipids through thyroid hormone receptor (TR) α in mouse 3T3-L1 cells. However, the transcription of the SREBP-1c and HSL genes was decreased by T3. Such T3-mediated alterations were negated by TRα siRNA. Chromatin immunoprecipitation assay showed that the binding of TRα to the TR-responsive element (TRE) of the FAS promoter was elevated by T3. In contrast, the ability of TRα to bind to the TRE of the SREBP-1c promoter was decreased by T3. In addition, the binding of SREBP-1c to the SRE of the HSL promoter was lowered by T3. These results indicate that T3 increased the accumulation of intracellular lipids by enhancing the expression of the FAS gene through direct binding of TRα to the FAS promoter and simultaneously lowered the amount of lipolysis via reduced binding of T3-decreased SREBP-1c to the HSL promoter. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Evidence of a bigenomic regulation of mitochondrial gene expression by thyroid hormone during rat brain development.

PubMed

Sinha, Rohit Anthony; Pathak, Amrita; Mohan, Vishwa; Babu, Satish; Pal, Amit; Khare, Drirh; Godbole, Madan M

2010-07-02

Hypothyroidism during early mammalian brain development is associated with decreased expression of various mitochondrial encoded genes along with evidence for mitochondrial dysfunction. However, in-spite of the similarities between neurological disorders caused by perinatal hypothyroidism and those caused by various genetic mitochondrial defects we still do not know as to how thyroid hormone (TH) regulates mitochondrial transcription during development and whether this regulation by TH is nuclear mediated or through mitochondrial TH receptors? We here in rat cerebellum show that hypothyroidism causes reduction in expression of nuclear encoded genes controlling mitochondrial biogenesis like PGC-1alpha, NRF-1alpha and Tfam. Also, we for the first time demonstrate a mitochondrial localization of thyroid hormone receptor (mTR) isoform in developing brain capable of binding a TH response element (DR2) present in D-loop region of mitochondrial DNA. These results thus indicate an integrated nuclear-mitochondrial cross talk in regulation of mitochondrial transcription by TH during brain development. Copyright 2010 Elsevier Inc. All rights reserved.

Evidence of a bigenomic regulation of mitochondrial gene expression by thyroid hormone during rat brain development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinha, Rohit Anthony; Pathak, Amrita; Mohan, Vishwa

Hypothyroidism during early mammalian brain development is associated with decreased expression of various mitochondrial encoded genes along with evidence for mitochondrial dysfunction. However, in-spite of the similarities between neurological disorders caused by perinatal hypothyroidism and those caused by various genetic mitochondrial defects we still do not know as to how thyroid hormone (TH) regulates mitochondrial transcription during development and whether this regulation by TH is nuclear mediated or through mitochondrial TH receptors? We here in rat cerebellum show that hypothyroidism causes reduction in expression of nuclear encoded genes controlling mitochondrial biogenesis like PGC-1{alpha}, NRF-1{alpha} and Tfam. Also, we for themore » first time demonstrate a mitochondrial localization of thyroid hormone receptor (mTR) isoform in developing brain capable of binding a TH response element (DR2) present in D-loop region of mitochondrial DNA. These results thus indicate an integrated nuclear-mitochondrial cross talk in regulation of mitochondrial transcription by TH during brain development.« less

The role of thyroid hormone in trophoblast function, early pregnancy maintenance, and fetal neurodevelopment.

PubMed

Ohara, Noriyuki; Tsujino, Taro; Maruo, Takeshi

2004-11-01

To review the literature on the roles of thyroid hormone in trophoblast function, early pregnancy maintenance, and fetal neurodevelopment. MEDLINE was searched for English-language papers published from 1971 to 2003, using the key words "brain," "hypothyroidism," "placenta," "pregnancy," "threatened abortion," "thyroid hormone," "thyroid hormone receptor," "thyroid hormone replacement therapy," "thyroid hormone-responsive gene," and "trophoblast." Transplacental transfer of thyroid hormone occurs before the onset of fetal thyroid hormone secretion. Thyroid hormone receptors and iodothyronine deiodinases are present in the placenta and the fetal central nervous system early in pregnancy, and thyroid hormone plays a crucial role both in trophoblast function and fetal neurodevelopment. Maternal hypothyroxinemia is associated with a high rate of spontaneous abortion and long-term neuropsychological deficits in children born of hypothyroid mothers. Maternal iodine deficiency also causes a wide spectrum of neuropsychological disorders in children, ranging from subclinical deficits in cognitive motor and auditory functions to hypothyroid-induced cognitive impairment in infants. However, these conditions are preventable when iodine supplementation is initiated before the second trimester. Although thyroid hormone replacement therapy is effective for reducing the adverse effects complicated by maternal hypothyroidism, the appropriate dose of thyroid hormone is mandatory in protecting the early stage of pregnancy. Close monitoring of maternal thyroid hormone status and ensuring adequate maternal thyroid hormone levels in early pregnancy are of great importance to prevent miscarriage and neuropsychological deficits in infants.

Effect of thyroid hormone on the levels of erythrocyte carbonic anhydrase isozymes and 2,3-diphosphoglycerate in rabbits.

PubMed

Kondo, T; Taniguchi, N; Ishikawa, N; Ide, H; Takakuwa, E; Murao, M

1978-05-01

Levels of rabbit erythrocyte carbonic anhydrase B and C isozymes were determined in experimental hyperthyroidism using a quantitative immunologic technique. Levels of erythrocyte 2,3-diphosphoglycerate and protein binding iodine were simultaneously determined. Thyroxine and 3,5,3'-triiodothyronine were administered to rabbits orally for 30 days. A significant decrease in carbonic anhydrase B type was observed after 30 days, although no significant change was observed in carbonic anhydrase C type. These findings suggest that the steady state level of carbonic anhydrase B type in red cells is affected by thyroid hormone more readily than that of carbonic anhydrase C type. The level of red cell 2,3-diphosphoglycerate increased markedly after 10 days of treatment, corresponding to the increase of protein binding iodine. The clinical or pathologic significances were discussed in relation to the changes in the levels of these isozymes and 2,3-diphosphglycerate in red cells.

Small-molecule agonists for the thyrotropin receptor stimulate thyroid function in human thyrocytes and mice

PubMed Central

Neumann, Susanne; Huang, Wenwei; Titus, Steve; Krause, Gerd; Kleinau, Gunnar; Alberobello, Anna Teresa; Zheng, Wei; Southall, Noel T.; Inglese, James; Austin, Christopher P.; Celi, Francesco S.; Gavrilova, Oksana; Thomas, Craig J.; Raaka, Bruce M.; Gershengorn, Marvin C.

2009-01-01

Seven-transmembrane-spanning receptors (7TMRs) are prominent drug targets. However, small-molecule ligands for 7-transmembrane-spanning receptors for which the natural ligands are large, heterodimeric glycoprotein hormones, like thyroid-stimulating hormone (TSH; thyrotropin), have only recently been reported, and none are approved for human use. We have used quantitative high-throughput screening to identify a small-molecule TSH receptor (TSHR) agonist that was modified to produce a second agonist with increased potency. We show that these agonists are highly selective for human TSHR versus other glycoprotein hormone receptors and interact with the receptor's serpentine domain. A binding pocket within the transmembrane domain was defined by docking into a TSHR homology model and was supported by site-directed mutagenesis. In primary cultures of human thyrocytes, both TSH and the agonists increase mRNA levels for thyroglobulin, thyroperoxidase, sodium iodide symporter, and deiodinase type 2, and deiodinase type 2 enzyme activity. Moreover, oral administration of the agonist stimulated thyroid function in mice, resulting in increased serum thyroxine and thyroidal radioiodide uptake. Thus, we discovered a small molecule that activates human TSHR in vitro, is orally active in mice, and could be a lead for development of drugs to use in place of recombinant human TSH in patients with thyroid cancer. PMID:19592511

Thyroid Stimulating Hormone Receptor Antibodies in Thyroid Eye Disease-Methodology and Clinical Applications.

PubMed

Diana, Tanja; Kahaly, George J

2018-05-02

Thyroid stimulating hormone receptor antibodies (TSHR-Ab) cause autoimmune hyperthyroidism and are prevalent in patients with related thyroid eye disease (TED). To provide a historical perspective on TSHR-Ab and to present evidence-based recommendations for clinical contemporary use. The authors review the recent literature pertaining to TSHR-Ab in patients with TED and describe the various immunoassays currently used for detecting TSHR-Ab and their clinical applications. We provide a historical summary and description of the various methods used to detect TSHR-Ab, foremost, the functional TSHR-Ab. Increasing experimental and clinical data demonstrate the clinical usefulness of cell-based bioassays for measurements of functional TSHR-Ab in the diagnosis and management of patients with autoimmune TED and in the characterization of patients with autoimmune-induced hyperthyroidism and hypothyroidism. Thyroid stimulating hormone receptor antibodies, especially the functional stimulating antibodies, are sensitive, specific, and reproducible biomarkers for patients with autoimmune TED and correlate well with clinical disease activity and clinical severity. Unlike competitive-binding assays, bioassays have the advantage of indicating not only the presence of antibodies but also their functional activity and potency. Measurement of TSHR-Ab (especially stimulating antibodies) is a clinically useful tool for the management of patients with TED.

Purification and characterization of rat liver nuclear thyroid hormone receptors.

PubMed Central

Ichikawa, K; DeGroot, L J

1987-01-01

Nuclear thyroid hormone receptor was purified to 904 pmol of L-3,5,3'-triiodothyronine (T3) binding capacity per mg of protein with 2.5-5.2% recovery by sequentially using hydroxylapatite column chromatography, ammonium sulfate precipitation, Sephadex G-150 gel filtration, DNA-cellulose column chromatography, DEAE-Sephadex column chromatography, and heparin-Sepharose column chromatography. Assuming that one T3 molecule binds to the 49,000-Da unit of the receptor, we reproducibly obtained 6.4-14.7 micrograms of receptor protein with 4.2-4.9% purity from 4-5 kg of rat liver. Elution of receptor from the heparin-Sepharose column was performed using 10 mM pyridoxal 5'-phosphate, which was observed to diminish binding of receptor to heparin-Sepharose or DNA-cellulose. This effect was specific for pyridoxal 5'-phosphate, since related compounds were not effective. Purified receptor bound T3 with high affinity (6.0 X 10(9) liter/mol), and the order of affinity of iodothyronine analogues to purified receptor was identical to that observed with crude receptor preparations [3,5,3'-triiodothyroacetic acid greater than L-T3 greater than D-3,5,3'-triiodothyronine (D-T3) greater than L-thyroxine greater than D-thyroxine]. Purified receptor had a sedimentation coefficient of 3.4 S, Stokes radius of 34 A, and calculated molecular mass of 49,000. Among several bands identified by silver staining after electrophoresis in NaDodSO4/polyacrylamide gels, one 49,000-Da protein showed photoaffinity labeling with [125I]thyroxine that was displaceable with excess unlabeled T3. The tryptic fragment and endogenous proteinase-digested fragment of the affinity-labeled receptor showed saturable binding in 27,000-Da and 36,000-Da peptides, respectively. These molecular masses are in agreement with estimates from gel filtration and gradient sedimentation, indicating that affinity labeling occurred at the hormone binding domain of nuclear thyroid hormone receptor. This procedure reproducibly provides classical native rat liver T3 nuclear receptor in useful quantity and purity and of the highest specific activity so far reported. Images PMID:3472213

Hyperactivity and learning deficits in transgenic mice bearing a human mutant thyroid hormone beta1 receptor gene.

PubMed

McDonald, M P; Wong, R; Goldstein, G; Weintraub, B; Cheng, S Y; Crawley, J N

1998-01-01

Resistance to thyroid hormone (RTH) is a human syndrome mapped to the thyroid receptor beta (TRbeta) gene on chromosome 3, representing a mutation of the ligand-binding domain of the TRbeta gene. The syndrome is characterized by reduced tissue responsiveness to thyroid hormone and elevated serum levels of thyroid hormones. A common behavioral phenotype associated with RTH is attention deficit hyperactivity disorder (ADHD). To test the hypothesis that RTH produces attention deficits and/or hyperactivity, transgenic mice expressing a mutant TRbeta gene were generated. The present experiment tested RTH transgenic mice from the PV kindred on behavioral tasks relevant to the primary features of ADHD: hyperactivity, sustained attention (vigilance), learning, and impulsivity. Male transgenic mice showed elevated locomotor activity in an open field compared to male wild-type littermate controls. Both male and female transgenic mice exhibited impaired learning of an autoshaping task, compared to wild-type controls. On a vigilance task in an operant chamber, there were no differences between transgenics and controls on the proportion of hits, response latency, or duration of stimulus tolerated. On an operant go/no-go task measuring sustained attention and impulsivity, there were no differences between controls and transgenics. These results indicate that transgenic mice bearing a mutant human TRbeta gene demonstrate several behavioral characteristics of ADHD and may serve a valuable heuristic role in elucidating possible candidate genes in converging pathways for other causes of ADHD.

Analysis of differential secondary effects of novel rexinoids: select rexinoid X receptor ligands demonstrate differentiated side effect profiles

PubMed Central

Marshall, Pamela A; Jurutka, Peter W; Wagner, Carl E; van der Vaart, Arjan; Kaneko, Ichiro; Chavez, Pedro I; Ma, Ning; Bhogal, Jaskaran S; Shahani, Pritika; Swierski, Johnathon C; MacNeill, Mairi

2015-01-01

In order to determine the feasibility of utilizing novel rexinoids for chemotherapeutics and as potential treatments for neurological conditions, we undertook an assessment of the side effect profile of select rexinoid X receptor (RXR) analogs that we reported previously. We assessed pharmacokinetic profiles, lipid and thyroid-stimulating hormone (TSH) levels in rats, and cell culture activity of rexinoids in sterol regulatory element-binding protein (SREBP) induction and thyroid hormone inhibition assays. We also performed RNA sequencing of the brain tissues of rats that had been dosed with the compounds. We show here for the first time that potent rexinoid activity can be uncoupled from drastic lipid changes and thyroid axis variations, and we propose that rexinoids can be developed with improved side effect profiles than the parent compound, bexarotene (1). PMID:26038698

Role of co-regulators in metabolic and transcriptional actions of thyroid hormone.

PubMed

Astapova, Inna

2016-04-01

Thyroid hormone (TH) controls a wide range of physiological processes through TH receptor (TR) isoforms. Classically, TRs are proposed to function as tri-iodothyronine (T3)-dependent transcription factors: on positively regulated target genes, unliganded TRs mediate transcriptional repression through recruitment of co-repressor complexes, while T3 binding leads to dismissal of co-repressors and recruitment of co-activators to activate transcription. Co-repressors and co-activators were proposed to play opposite roles in the regulation of negative T3 target genes and hypothalamic-pituitary-thyroid axis, but exact mechanisms of the negative regulation by TH have remained elusive. Important insights into the roles of co-repressors and co-activators in different physiological processes have been obtained using animal models with disrupted co-regulator function. At the same time, recent studies interrogating genome-wide TR binding have generated compelling new data regarding effects of T3, local chromatin structure, and specific response element configuration on TR recruitment and function leading to the proposal of new models of transcriptional regulation by TRs. This review discusses data obtained in various mouse models with manipulated function of nuclear receptor co-repressor (NCoR or NCOR1) and silencing mediator of retinoic acid receptor and thyroid hormone receptor (SMRT or NCOR2), and family of steroid receptor co-activators (SRCs also known as NCOAs) in the context of TH action, as well as insights into the function of co-regulators that may emerge from the genome-wide TR recruitment analysis. © 2016 Society for Endocrinology.

EFFECTS ON HEPATIC GENE EXPRESSION IN MALE RATS ADMINISTERED PBDES IN HOUSEHOLD DUST

EPA Science Inventory

Studies show that polybrominated diphenyl ethers (PBDEs) decrease thyroid hormone concentrations via induction of hepatic uridinediphosphate-glucoronosyltransferase (UGTs) and transthyretin (Ttr) binding. Because PBDEs exhibit endocrine disrupting properties and are present in h...

Gelsolin: a novel thyroid hormone receptor-beta interacting protein that modulates tumor progression in a mouse model of follicular thyroid cancer.

PubMed

Kim, Caroline S; Furuya, Fumihiko; Ying, Hao; Kato, Yasuhito; Hanover, John A; Cheng, Sheue-yann

2007-03-01

Follicular thyroid cancer (FTC) is known to metastasize to distant sites via hematogenous spread; however, the underlying pathways that contribute to metastasis remain unknown. Recent creation of a knockin mutant mouse that expresses a mutant thyroid hormone receptor-beta (TRbeta(PV/PV) mouse) that spontaneously develops thyroid cancer with metastasis similar to humans has provided new opportunities to study contributors to FTC metastasis. This study evaluates the role of gelsolin, an actin-regulatory protein, in modulating the metastatic potential of FTC. Gelsolin was previously found by cDNA microarray analysis to be down-regulated in TRbeta(PV/PV) mice as compared with wild-type mice. This study found an age-dependent reduction of gelsolin protein abundance in TRbeta(PV/PV) mice as tumorigenesis progressed. Knockdown of gelsolin by small interfering RNA resulted in increased tumor cell motility and increased gelsolin expression by histone deacetylase inhibitor (trichostatin A) led to decreased cell motility. Additional biochemical analyses demonstrated that gelsolin physically interacted with TRbeta1 or PV in vivo and in vitro. The interaction regions were mapped to the C terminus of gelsolin and the DNA binding domain of TR. The physical interaction of gelsolin with PV reduced its binding to actin, leading to disarrayed cytoskeletal architectures. These results suggest that PV-induced alteration of the actin/gelsolin cytoskeleton contributes to increased cell motility. Thus, the present study uncovered a novel PV-mediated oncogenic pathway that could contribute to the local tumor progression and metastatic potential of thyroid carcinogenesis.

Role of maternal thyroid hormones in the developing neocortex and during human evolution

PubMed Central

Stenzel, Denise; Huttner, Wieland B.

2013-01-01

The importance of thyroid hormones during brain development has been appreciated for many decades. In humans, low levels of circulating maternal thyroid hormones, e.g., caused by maternal hypothyroidism or lack of iodine in diet, results in a wide spectrum of severe neurological defects, including neurological cretinism characterized by profound neurologic impairment and mental retardation, underlining the importance of the maternal thyroid hormone contribution. In fact, iodine intake, which is essential for thyroid hormone production in the thyroid gland, has been related to the expansion of the brain, associated with the increased cognitive capacities during human evolution. Because thyroid hormones regulate transcriptional activity of target genes via their nuclear thyroid hormone receptors (THRs), even mild and transient changes in maternal thyroid hormone levels can directly affect and alter the gene expression profile, and thus disturb fetal brain development. Here we summarize how thyroid hormones may have influenced human brain evolution through the adaptation to new habitats, concomitant with changes in diet and, therefore, iodine intake. Further, we review the current picture we gained from experimental studies in rodents on the function of maternal thyroid hormones during developmental neurogenesis. We aim to evaluate the effects of maternal thyroid hormone deficiency as well as lack of THRs and transporters on brain development and function, shedding light on the cellular behavior conducted by thyroid hormones. PMID:23882187

21 CFR 862.1690 - Thyroid stimulating hormone test system.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Thyroid stimulating hormone test system. 862.1690... Systems § 862.1690 Thyroid stimulating hormone test system. (a) Identification. A thyroid stimulating hormone test system is a device intended to measure thyroid stimulating hormone, also known as...

21 CFR 862.1690 - Thyroid stimulating hormone test system.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Thyroid stimulating hormone test system. 862.1690... Systems § 862.1690 Thyroid stimulating hormone test system. (a) Identification. A thyroid stimulating hormone test system is a device intended to measure thyroid stimulating hormone, also known as...

2,4,6-Tribromophenol Interferes with the Thyroid Hormone System by Regulating Thyroid Hormones and the Responsible Genes in Mice

PubMed Central

Lee, Dongoh; Ahn, Changhwan; Hong, Eui-Ju; An, Beum-Soo; Hyun, Sang-Hwan; Choi, Kyung-Chul; Jeung, Eui-Bae

2016-01-01

2,4,6-Tribromophenol (TBP) is a brominated flame retardant (BFR). Based on its affinity for transthyretin, TBP could compete with endogenous thyroid hormone. In this study, the effects of TBP on the thyroid hormone system were assessed in mice. Briefly, animals were exposed to 40 and 250 mg/kg TBP. Thyroid hormones were also administered with or without TBP. When mice were treated with TBP, deiodinase 1 (Dio1) and thyroid hormone receptor β isoform 2 (Thrβ2) decreased in the pituitary gland. The levels of deiodinase 2 (Dio2) and growth hormone (Gh) mRNA increased in response to 250 mg/kg of TBP, and the relative mRNA level of thyroid stimulating hormone β (Tshβ) increased in the pituitary gland. Dio1 and Thrβ1 expression in the liver were not altered, while Dio1 decreased in response to co-treatment with thyroid hormones. The thyroid gland activity decreased in response to TBP, as did the levels of free triiodothyronine and free thyroxine in serum. Taken together, these findings indicate that TBP can disrupt thyroid hormone homeostasis and the presence of TBP influenced thyroid actions as regulators of gene expression. These data suggest that TBP interferes with thyroid hormone systems PMID:27420076

2,4,6-Tribromophenol Interferes with the Thyroid Hormone System by Regulating Thyroid Hormones and the Responsible Genes in Mice.

PubMed

Lee, Dongoh; Ahn, Changhwan; Hong, Eui-Ju; An, Beum-Soo; Hyun, Sang-Hwan; Choi, Kyung-Chul; Jeung, Eui-Bae

2016-07-12

2,4,6-Tribromophenol (TBP) is a brominated flame retardant (BFR). Based on its affinity for transthyretin, TBP could compete with endogenous thyroid hormone. In this study, the effects of TBP on the thyroid hormone system were assessed in mice. Briefly, animals were exposed to 40 and 250 mg/kg TBP. Thyroid hormones were also administered with or without TBP. When mice were treated with TBP, deiodinase 1 (Dio1) and thyroid hormone receptor β isoform 2 (Thrβ2) decreased in the pituitary gland. The levels of deiodinase 2 (Dio2) and growth hormone (Gh) mRNA increased in response to 250 mg/kg of TBP, and the relative mRNA level of thyroid stimulating hormone β (Tshβ) increased in the pituitary gland. Dio1 and Thrβ1 expression in the liver were not altered, while Dio1 decreased in response to co-treatment with thyroid hormones. The thyroid gland activity decreased in response to TBP, as did the levels of free triiodothyronine and free thyroxine in serum. Taken together, these findings indicate that TBP can disrupt thyroid hormone homeostasis and the presence of TBP influenced thyroid actions as regulators of gene expression. These data suggest that TBP interferes with thyroid hormone systems.

Changes of Serum Angiotensin-Converting Enzyme Activity During Treatment of Patients with Graves’ Disease*

PubMed Central

Lee, Dong Soo; Chung, June-Key; Cho, Bo Youn; Koh, Chang-Soon; Lee, Munho

1986-01-01

Serum angiotensin-converting enzyme activity was measured spectrophotometrically, and serum thyrotropin-binding-inhibitory immunoglobulin (TBII) activity was measured by radioreceptor assay in normal subjects and in patients with Graves’ disease serially before and during treatment, and these activities were compared with each other and with thyroid hormone levels in various thyroid functional status. Correlation between serum angiotensin-converting enzyme activity and serum thyroid hormone level was pursued with relation to the changes of thyroid functional status in patients with Graves’ disease during treatment. Serum angiotensin-converting enzyme activity was significantly elevated in patients with hyperthyroid Graves’ disease before the start of treatment (35 ± 13 nmol/min/ml, n=50), and not in patients with Graves’ disease, euthyroid state during treatment with antithyroid drugs or radioactive iodine (23 ± 9 nmol/min/ml, n=12), but decreased significantly in patients with Graves’ disease, hypothyroid state transiently during treatment (15 ± 4 nmol/min/ml, n=12), respectively in comparison with normal control subjects. Serum angiotensin-converting enzyme activity was positively correlated with the log value of serum T3 concentration (r=0.62, p<0.001, n=95), and with the log value of free thyroxine index (r=0.66, p<0.001, n=91) but not statistically significantly with serum TBII activity. Serum angiotensin-converting enzyme activity was followed in 11 patients with initially increased activity and the activity decreased in proportion to serum thyroid hormone level during treatment, irrespective of treatment modality. It is suggested that thyroid hormones play a role in the increase and decrease of serum angiotensin-converting enzyme activity directly or indirectly influencing the peripheral tissues (probably reticuloendothelial cells or peripheral endothelial cells) in patients with Graves’ disease. PMID:15759385

Molecular Aspects of Thyroid Hormone Actions

PubMed Central

Cheng, Sheue-Yann; Leonard, Jack L.; Davis, Paul J.

2010-01-01

Cellular actions of thyroid hormone may be initiated within the cell nucleus, at the plasma membrane, in cytoplasm, and at the mitochondrion. Thyroid hormone nuclear receptors (TRs) mediate the biological activities of T3 via transcriptional regulation. Two TR genes, α and β, encode four T3-binding receptor isoforms (α1, β1, β2, and β3). The transcriptional activity of TRs is regulated at multiple levels. Besides being regulated by T3, transcriptional activity is regulated by the type of thyroid hormone response elements located on the promoters of T3 target genes, by the developmental- and tissue-dependent expression of TR isoforms, and by a host of nuclear coregulatory proteins. These nuclear coregulatory proteins modulate the transcription activity of TRs in a T3-dependent manner. In the absence of T3, corepressors act to repress the basal transcriptional activity, whereas in the presence of T3, coactivators function to activate transcription. The critical role of TRs is evident in that mutations of the TRβ gene cause resistance to thyroid hormones to exhibit an array of symptoms due to decreasing the sensitivity of target tissues to T3. Genetically engineered knockin mouse models also reveal that mutations of the TRs could lead to other abnormalities beyond resistance to thyroid hormones, including thyroid cancer, pituitary tumors, dwarfism, and metabolic abnormalities. Thus, the deleterious effects of mutations of TRs are more severe than previously envisioned. These genetic-engineered mouse models provide valuable tools to ascertain further the molecular actions of unliganded TRs in vivo that could underlie the pathogenesis of hypothyroidism. Actions of thyroid hormone that are not initiated by liganding of the hormone to intranuclear TR are termed nongenomic. They may begin at the plasma membrane or in cytoplasm. Plasma membrane-initiated actions begin at a receptor on integrin αvβ3 that activates ERK1/2 and culminate in local membrane actions on ion transport systems, such as the Na+/H+ exchanger, or complex cellular events such as cell proliferation. Concentration of the integrin on cells of the vasculature and on tumor cells explains recently described proangiogenic effects of iodothyronines and proliferative actions of thyroid hormone on certain cancer cells, including gliomas. Thus, hormonal events that begin nongenomically result in effects in DNA-dependent effects. l-T4 is an agonist at the plasma membrane without conversion to T3. Tetraiodothyroacetic acid is a T4 analog that inhibits the actions of T4 and T3 at the integrin, including angiogenesis and tumor cell proliferation. T3 can activate phosphatidylinositol 3-kinase by a mechanism that may be cytoplasmic in origin or may begin at integrin αvβ3. Downstream consequences of phosphatidylinositol 3-kinase activation by T3 include specific gene transcription and insertion of Na, K-ATPase in the plasma membrane and modulation of the activity of the ATPase. Thyroid hormone, chiefly T3 and diiodothyronine, has important effects on mitochondrial energetics and on the cytoskeleton. Modulation by the hormone of the basal proton leak in mitochondria accounts for heat production caused by iodothyronines and a substantial component of cellular oxygen consumption. Thyroid hormone also acts on the mitochondrial genome via imported isoforms of nuclear TRs to affect several mitochondrial transcription factors. Regulation of actin polymerization by T4 and rT3, but not T3, is critical to cell migration. This effect has been prominently demonstrated in neurons and glial cells and is important to brain development. The actin-related effects in neurons include fostering neurite outgrowth. A truncated TRα1 isoform that resides in the extranuclear compartment mediates the action of thyroid hormone on the cytoskeleton. PMID:20051527

Thyroid Hormones and Growth in Health and Disease

PubMed Central

Tarım, Ömer

2011-01-01

Thyroid hormones regulate growth by several mechanisms. In addition to their negative feedback effect on the stimulatory hormones thyrotropin-releasing hormone (TRH) and thyrotropin (TSH), thyroid hormones also regulate their receptors in various physiological and pathological conditions. Up-regulation and down-regulation of the thyroid receptors fine-tune the biological effects exerted by the thyroid hormones. Interestingly, the deiodinase enzyme system is another intrinsic regulator of thyroid physiology that adjusts the availability of thyroid hormones to the tissues, which is essential for normal growth and development. Almost all chronic diseases of childhood impair growth and development. Every disease may have a unique mechanism to halt linear growth, but reduced serum concentration or diminished local availability of thyroid hormones seems to be a common pathway. Therefore, the effects of systemic diseases on thyroid physiology must be taken into consideration in the evaluation of growth retardation in affected children. Conflict of interest:None declared. PMID:21750631

Assessment of the binding of hydroxylated polybrominated diphenyl ethers to thyroid hormone transport proteins using a site-specific fluorescence probe.

PubMed

Ren, Xiao M; Guo, Liang-Hong

2012-04-17

Polybrominated diphenyl ethers (PBDEs) have been shown to disrupt thyroid hormone (TH) functions on experimental animals, and one of the proposed disruption mechanisms is the competitive binding of PBDE metabolites to TH transport proteins. In this report, a nonradioactive, site-specific fluorescein-thyroxine (F-T4) conjugate was designed and synthesized as a fluorescence probe to study the binding interaction of hydroxylated PBDEs to thyroxine-binding globulin (TBG) and transthyretin (TTR), two major TH transport proteins in human plasma. Compared with free F-T4, the fluorescence intensity of TTR-bound conjugate was enhanced by as much as 2-fold, and the fluorescence polarization value of TBG-bound conjugate increased by more than 20-fold. These changes provide signal modulation mechanisms for F-T4 as a fluorescence probe. Based on fluorescence quantum yield and lifetime measurements, the fluorescence intensity enhancement was likely due to the elimination of intramolecular fluorescence quenching of fluorescein by T4 after F-T4 was bound to TTR. In circular dichroism and intrinsic tryptophan fluorescence measurements, F-T4 induced similar spectroscopic changes of the proteins as T4 did, suggesting that F-T4 bound to the proteins at the T4 binding site. By using F-T4 as the fluorescence probe in competitive binding assays, 11 OH-PBDEs with different levels of bromination and different hydroxylation positions were assessed for their binding affinity with TBG and TTR, respectively. The results indicate that the binding affinity generally increased with bromine number and OH position also played an important role. 3-OH-BDE-47 and 3'-OH-BDE-154 bound to TTR and TBG even stronger, respectively, than T4. With rising environmental level and high bioaccumulation capability, PBDEs have the potential to disrupt thyroid homeostasis by competitive binding with TH transport proteins.

[Serum thyroxine-binding protein for determining the functional state of the thyroid gland in pregnant women with endemic goiter].

PubMed

Korol'kova, O A; Cheremukhin, V I

1975-01-01

A determination was made of the hormone-forming capacity of the thyroid gland in pregnent women under conditions of goiter endemic at various periods of pregnancy by trimesters (123-in healthy pregnant women, 206-with euthyroid goiter of the I degree, 271-or II degree, 90-of the II degree, and 4-of the IV degree). A method of zonal electrophoresis in the medinal-veronal buffer was applied. Thyrofixin with I131 isotope (made in the USSR) was used. With increase of the periods of pregnancy and the degree of euthyroid hyperplasia of the thyroid gland and goiter the thyroid gland function became elevated irrespective of age.

Studies on Changes of β-Adrenergic Receptors in Polymorphonuclear Cell and Mononuclear Cell with the Changes of Thyroid Function

PubMed Central

Lee, Jong Do; You, Myung Hee; Kim, Young Seol; Kim, Jin Woo; Kim, Kwang Won; Kim, Sun Woo; Choi, Young Kil

1986-01-01

Although it has been well established that thyroid hormones increase β-adrenergic receptors of various tissues in the animal studies, there are controversies about the β-adrenergic receptor changes of human mononuclear cells and polymorphonuclear cells. The present study was performed to analyze the change of β-adrenergic receptor of those cells according to the thyroid functional status and to evaluate their usefulness in assessment of sympathetic hyperactivity. We measured [3H]-dihydroalprenolol binding to circulating mononuclear and polymorphonuclear cells from 18 patients with hyperthyrodism, 7 with hypothyroidism, 8 with euthyroid goiter and 21 normal controls. Only with polymorphonuclear cells the receptor concentration was significantly higher (P<0.01) in hyperthyroidism (46.07±4.78 fmol/mg protein) than in the normal control (28.42±2.06 fmol/mg protein) and the affinity constants of both cells were comparable to normal control values. And serum concentrations of T3 were not correlated well with the changes of receptor concentrations in hyperthyroidism. The patients with hypothyroidism and euthyroid goiter showed no significant difference in the receptor concentration and the affinity constants with both cell binding assays. These results indicate that thyroid hormones increase the receptor concentration in polymorphonuclear cells which might be responsible for the symptoms of sympathetic hyperactivity and the polymorphornuclear cells are useful for β-adrenergic receptor assay. PMID:15759381

Thyroid hormone effects on mitochondrial energetics.

PubMed

Harper, Mary-Ellen; Seifert, Erin L

2008-02-01

Thyroid hormones are the major endocrine regulators of metabolic rate, and their hypermetabolic effects are widely recognized. The cellular mechanisms underlying these metabolic effects have been the subject of much research. Thyroid hormone status has a profound impact on mitochondria, the organelles responsible for the majority of cellular adenosine triphosphate (ATP) production. However, mechanisms are not well understood. We review the effects of thyroid hormones on mitochondrial energetics and principally oxidative phosphorylation. Genomic and nongenomic mechanisms have been studied. Through the former, thyroid hormones stimulate mitochondriogenesis and thereby augment cellular oxidative capacity. Thyroid hormones induce substantial modifications in mitochondrial inner membrane protein and lipid compositions. Results are consistent with the idea that thyroid hormones activate the uncoupling of oxidative phosphorylation through various mechanisms involving inner membrane proteins and lipids. Increased uncoupling appears to be responsible for some of the hypermetabolic effects of thyroid hormones. ATP synthesis and turnover reactions are also affected. There appear to be complex relationships between mitochondrial proton leak mechanisms, reactive oxygen species production, and thyroid status. As the majority of studies have focused on the effects of thyroid status on rat liver preparations, there is still a need to address fundamental questions regarding thyroid hormone effects in other tissues and species.

Vitamin D receptor displays DNA binding and transactivation as a heterodimer with the retinoid X receptor, but not with the thyroid hormone receptor.

PubMed

Thompson, P D; Hsieh, J C; Whitfield, G K; Haussler, C A; Jurutka, P W; Galligan, M A; Tillman, J B; Spindler, S R; Haussler, M R

1999-12-01

The vitamin D receptor (VDR) is a transcription factor believed to function as a heterodimer with the retinoid X receptor (RXR). However, it was reported [Schräder et al., 1994] that, on putative vitamin D response elements (VDREs) within the rat 9k and mouse 28k calcium binding protein genes (rCaBP 9k and mCaBP 28k), VDR and thyroid hormone receptor (TR) form heterodimers that transactivate in response to both 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) and triiodothyronine (T(3)). We, therefore, examined associations of these receptors on the putative rCaBP 9k and mCaBP 28k VDREs, as well as on established VDREs from the rat osteocalcin (rOC) and mouse osteopontin (mOP) genes, plus the thyroid hormone response element (TRE) from the rat myosin heavy chain (rMHC) gene. In gel mobility shift assays, we found no evidence for VDR-TR heterodimer interaction with any tested element. Further, employing these hormone response elements linked to reporter genes in transfected cells, VDR and TR mediated responses to their cognate ligands only from the rOC/mOP and rMHC elements, respectively, while the CaBP elements were unresponsive to any combination of ligand(s). Utilizing the rOC and mOP VDREs, two distinct repressive actions of TR on VDR-mediated signaling were demonstrated: a T(3)-independent action, presumably via direct TR-RXR competition for DNA binding, and a T(3)-dependent repression, likely by diversion of limiting RXR from VDR-RXR toward the formation of TR-RXR heterodimers. The relative importance of these two mechanisms differed in a response element-specific manner. These results may provide a partial explanation for the observed association between hyperthyroidism and bone demineralization/osteoporosis. Copyright 1999 Wiley-Liss, Inc.

Molecular basis for the autoreactivity against thyroid stimulating hormone receptor.

PubMed

Kohn, L D; Kosugi, S; Ban, T; Saji, M; Ikuyama, S; Giuliani, C; Hidaka, A; Shimura, H; Akamizu, T; Tahara, K

1992-01-01

The present report identifies an important immunogenic region of the TSH receptor and determinants on the TSH receptor for the two types of autoantibodies seen in hyperthyroid Graves' disease and hypothyroid idiopathic myxedema, TSAbs and TSBAbs, respectively. The immunogenic domain with no important functional determinants, is contained within residues 303-382 and involves residues 352-366 in particular. There are determinants flanking the immunogenic domain on the C-terminal portion of the receptor which are the TSBAb and high affinity TSH binding sites: residues 295-306, 387-395, and tyrosine 385. Determinants on the N-terminal portion of the external domain, centered on residues 38-45, are TSAb interactions linked to low affinity TSH binding important for signal generation: threonine 40 and residues 30-33, 34-37, 42-45, 52-56, and 58-61. These determinants are conserved in human and rat receptors, are not present in gonadotropin receptors, and are each related to separate actions of TSH: binding vs. signal generation. They can, therefore, account for organ specific autoimmunity and the different disease expression effected by TSBAbs vs TSAbs, i.e. hypo- vs. hyperthyroidism, respectively. It is proposed that, in the thyroid, hormonal (TSH, insulin, hydrocortisone, IGF-I) suppression of class I genes might be one means of preserving self-tolerance in the face of the hormone action to increase the expression of tissue specific genes such as thyroglobulin and thyroid peroxidase. Inappropriately high class I expression in the thyroid, i.e. if induced by interferon, viruses, or some as yet unknown agent, would contribute to the generation of autoimmune disease. Thus, it would result in increased antigen presentation to the immune system, particularly those autoantigens increased by TSH and its cAMP signal such as thyroglobulin or thyroid peroxidase, or whose turnover is increased by TSH and its cAMP signal, such as the TSH receptor. In the case of the latter, peptide 352-366, known to be near a protease sensitive site on the receptor [41,49], would now act as a potent self-antigen and induce the formation of receptor autoantibodies. It is further proposed that methimazole and high doses of iodide are therapeutically effective agents in thyroid autoimmune disease because they, in part, decrease MHC class I gene expression. Speculation is presented which suggests that elimination of negative regulation of MHC class I and the TSH receptor is an important factor in the development of autoimmune thyroid disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Insulin-like growth factor-binding protein-3 (IGFBP-3) but not insulin-like growth factor-I (IGF-I) remains elevated in euthyroid TSH-suppressed Graves' disease.

PubMed

Wan Nazaimoon, W M; Khalid, B A

1998-04-01

Thyroid hormones have been shown to be involved in the regulation of insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3) expression. This is a cross-sectional study to look at the effects of thyroid hormone status on the circulating levels of IGF-I and IGFBP-3 in a group of 127 patients, aged 20-80 years, who were hyperthyroid, hypothyroid, rendered euthyroid and clinically euthyroid with normal free thyroxine (fT4), but suppressed thyroid stimulating hormone (TSH) levels. TSH was measured by the IMx (Abbott) ultrasensitive assay, while radioimmunoassays for total T3 and T4 were performed using kits from ICN, USA; fT4 and fT3 using kits from DPC USA; IGF-I and IGFBP-3 using kits from Nichols Institute Diagnostics B.V., Netherlands. Differences in the levels of IGF-I between the 4 groups of patients were significant only in the patients aged 20-40. Mean (+/-SEM) IGF-I levels of hypothyroid patients (169+/-19ng/ml) was significantly lower than hyperthyroid (315+/-26 ng/ml, p=0.003), euthyroid patients (241+/-19 ng/ml, p=0.002) and patients with suppressed TSH (308+/-29 ng/ml, p=0.02). The IGF-I levels of the hyperthyroid and suppressed TSH patients were, however, comparable to age-matched normal subjects (281+/-86 ng/ml). Although there was no difference in mean IGFBP-3 levels between the 4 groups of patients, the levels in the patients aged 20-40 with hyperthyroidism (3.7+/-0.9 microg/ml) and suppressed TSH (3.9+/-1.2 microg/ml) were significantly higher (p=0.02) than age-matched normal subjects (3.1+/-0.8 microg/ml). The IGF-I levels of the thyroid patients aged 20-40 showed significant negative correlation to TSH and positive correlations to the thyroid hormones. Hence, whilst low IGF-I is associated with hypothyroidism, high IGFBP-3 is associated with hyperthyroidism. Our finding that IGFBP-3 remained significantly elevated in patients with suppressed TSH but normalised fT4 and fT3 is important as it suggests a prolonged tissue effect of thyroid hormones on IFGBP-3. As such patients have been shown to have higher risk for atrial fibrillation, the significance and possible role of IGFBP-3 in these conditions should be further elucidated in future studies.

Thyroiditis: an integrated approach.

PubMed

Sweeney, Lori B; Stewart, Christopher; Gaitonde, David Y

2014-09-15

Thyroiditis is a general term that encompasses several clinical disorders characterized by inflammation of the thyroid gland. The most common is Hashimoto thyroiditis; patients typically present with a nontender goiter, hypothyroidism, and an elevated thyroid peroxidase antibody level. Treatment with levothyroxine ameliorates the hypothyroidism and may reduce goiter size. Postpartum thyroiditis is transient or persistent thyroid dysfunction that occurs within one year of childbirth, miscarriage, or medical abortion. Release of preformed thyroid hormone into the bloodstream may result in hyperthyroidism. This may be followed by transient or permanent hypothyroidism as a result of depletion of thyroid hormone stores and destruction of thyroid hormone-producing cells. Patients should be monitored for changes in thyroid function. Beta blockers can treat symptoms in the initial hyperthyroid phase; in the subsequent hypothyroid phase, levothyroxine should be considered in women with a serum thyroid-stimulating hormone level greater than 10 mIU per L, or in women with a thyroid-stimulating hormone level of 4 to 10 mIU per L who are symptomatic or desire fertility. Subacute thyroiditis is a transient thyrotoxic state characterized by anterior neck pain, suppressed thyroid-stimulating hormone, and low radioactive iodine uptake on thyroid scanning. Many cases of subacute thyroiditis follow an upper respiratory viral illness, which is thought to trigger an inflammatory destruction of thyroid follicles. In most cases, the thyroid gland spontaneously resumes normal thyroid hormone production after several months. Treatment with high-dose acetylsalicylic acid or nonsteroidal anti-inflammatory drugs is directed toward relief of thyroid pain.

A one-year follow-up on the effects of raloxifene on thyroid function in postmenopausal women.

PubMed

Ceresini, Graziano; Morganti, Simonetta; Rebecchi, Isabella; Bertone, Luca; Ceda, Gian Paolo; Bacchi-Modena, Alberto; Sgarabotto, Mariapaola; Baldini, Monica; Ablondi, Fabrizio; Valenti, Giorgio; Braverman, Lewis E

2004-01-01

Estrogens increase serum thyroxine-binding globulin (TBG) and total thyroxine (TT4) concentrations. Serum free thyroxine (FT4) concentrations, however, remain normal. Raloxifene (RAL) is a selective estrogen receptor modulator used to treat postmenopausal osteoporosis. Data on the long-term effects of RAL on thyroid physiology are scanty. We evaluated the effects of RAL administration for 1 year on thyroid function in osteopenic, postmenopausal women. Fifty osteopenic, postmenopausal women were randomly assigned to receive either RAL (60 mg/day, n = 25) or placebo (PL, n = 25) for 1 year, in a double-blind study. Measurements of serum TBG, TT4, FT4, thyroid-stimulating hormone (TSH), thyroid hormone-binding ratio (THBR), FT4 index (FT4-I) and TT4/TBG ratio were carried out at baseline and after 4 and 12 months of therapy. Baseline values were similar in both treatment groups. Serum TBG concentrations were increased during RAL treatment from baseline values of 29.60 +/- 0.9 microg/mL to 31.45 +/- 1.33 and 32.34 +/- 1.37 microg/mL at 4 months and 1 year, respectively (P < 0.05, baseline v 1-year values) but were unchanged during PL treatment. A small, insignificant increase in TT4 and TSH concentrations occurred in the RAL group and no changes in the PL group. All other values were unchanged during either treatment. These results demonstrate that RAL significantly increased serum TBG levels, but the changes were small and not accompanied by changes in FT4-I, FT4, or TSH concentrations, suggesting that long-term RAL treatment is unlikely to clinically affect the thyroid status in euthyroid, postmenopausal women.

BXR, an embryonic orphan nuclear receptor activated by a novel class of endogenous benzoate metabolites

PubMed Central

Blumberg, Bruce; Kang, Heonjoong; Bolado, Jack; Chen, Hongwu; Craig, A. Grey; Moreno, Tanya A.; Umesono, Kazuhiko; Perlmann, Thomas; De Robertis, Eddy M.; Evans, Ronald M.

1998-01-01

Nuclear receptors are ligand-modulated transcription factors that respond to steroids, retinoids, and thyroid hormones to control development and body physiology. Orphan nuclear receptors, which lack identified ligands, provide a unique, and largely untapped, resource to discover new principles of physiologic homeostasis. We describe the isolation and characterization of the vertebrate orphan receptor, BXR, which heterodimerizes with RXR and binds high-affinity DNA sites composed of a variant thyroid hormone response element. A bioactivity-guided screen of embryonic extracts revealed that BXR is activatable by low-molecular-weight molecules with spectral patterns distinct from known nuclear receptor ligands. Mass spectrometry and 1H NMR analysis identified alkyl esters of amino and hydroxy benzoic acids as potent, stereoselective activators. In vitro cofactor association studies, along with competable binding of radiolabeled compounds, establish these molecules as bona fide ligands. Benzoates comprise a new molecular class of nuclear receptor ligand and their activity suggests that BXR may control a previously unsuspected vertebrate signaling pathway. PMID:9573044

Exposure to pyrethroids insecticides and serum levels of thyroid-related measures in pregnant women

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jie; Hisada, Aya; Yoshinaga, Jun, E-mail: junyosh@k.u-tokyo.ac.jp

Possible association between environmental exposure to pyrethroid insecticides and serum thyroid-related measures was explored in 231 pregnant women of 10–12 gestational weeks recruited at a university hospital in Tokyo during 2009–2011. Serum levels of free thyroxine (fT4), thyroid stimulating hormone (TSH) and thyroid biding globulin (TBG) and urinary pyrethroid insecticide metabolite (3-phenoxybenzoic acid, 3-PBA) were measured. Obstetrical information was obtained from medical records and dietary and lifestyle information was collected by self-administered questionnaire. Geometric mean concentration of creatinine-adjusted urinary 3-PBA was 0.363 (geometric standard deviation: 3.06) μg/g cre, which was consistent with the previously reported levels for non-exposed Japanese adultmore » females. The range of serum fT4, TSH and TBG level was 0.83–3.41 ng/dL, 0.01–27.4 μIU/mL and 16.4–54.4 μg/mL, respectively. Multiple regression analysis was carried out by using either one of serum levels of thyroid-related measures as a dependent variable and urinary 3-PBA as well as other potential covariates (age, pre-pregnancy BMI, parity, urinary iodine, smoking and drinking status) as independent variables: 3-PBA was not found as a significant predictor of serum level of thyroid-related measures. Lack of association may be due to lower pyrethroid insecticide exposure level of the present subjects. Taking the ability of pyrethroid insecticides and their metabolite to bind to nuclear thyroid hormone (TH) receptor, as well as their ability of placental transfer, into consideration, it is warranted to investigate if pyrethroid pesticides do not have any effect on TH actions in fetus brain even though maternal circulating TH level is not affected. -- Highlights: • Pyrethroid exposure and thyroid hormone status was examined in pregnant women. • Urinary 3-phenoxybenzoic acid was used as a biomarker of exposure. • Iodine nutrition, age and other covariates were included in statistical models. • No association was found between levels of thyroid hormone and pyrethroid exposure. • The result may be ascribed to lower exposure level.« less

Thyroid-stimulating Hormone (TSH): Measurement of Intracellular, Secreted, and Circulating Hormone in Xenopus laevis and Xenopus tropicalis.

EPA Science Inventory

Thyroid Stimulating Hormone (TSH) is a hormone produced in the pituitary that stimulates the thyroid gland to grow and produce thyroid hormone (TH). The concentration of TH controls developmental changes that take place in a wide variety of organisms. Many use the metaphoric ch...

Neonatal thyrotoxicosis caused by maternal autoimmune hyperthyroidism.

PubMed

Correia, Miguel Fragata; Maria, Ana Teresa; Prado, Sara; Limbert, Catarina

2015-03-06

Neonatal immune hyperthyroidism is a rare but potentially fatal condition. It occurs in 1-5% of infants born to women with Graves' disease (GD). In most of the cases it is due to maternal antibodies transferred from the mother into the fetal compartment, stimulating the fetal thyroid by binding thyrotropin (thyroid-stimulating hormone, TSH) receptor. We present a case of neonatal thyrotoxicosis due to maternal GD detected at 25 days of age and discuss the potential pitfalls in the diagnosis. 2015 BMJ Publishing Group Ltd.

Neonatal thyrotoxicosis caused by maternal autoimmune hyperthyroidism

PubMed Central

Correia, Miguel Fragata; Maria, Ana Teresa; Prado, Sara; Limbert, Catarina

2015-01-01

Neonatal immune hyperthyroidism is a rare but potentially fatal condition. It occurs in 1–5% of infants born to women with Graves’ disease (GD). In most of the cases it is due to maternal antibodies transferred from the mother into the fetal compartment, stimulating the fetal thyroid by binding thyrotropin (thyroid-stimulating hormone, TSH) receptor. We present a case of neonatal thyrotoxicosis due to maternal GD detected at 25 days of age and discuss the potential pitfalls in the diagnosis. PMID:25750228

[The influence of hypothyroidism on the conversion and binding of thyroid hormones in patients with end-stage renal disease].

PubMed

Dubczak, Iwanna; Niemczyk, Longin; Bartoszewicz, Zbigniew; Szamotulska, Katarzyna; Saracyn, Marek; Niemczyk, Stanisław

2017-03-21

Hypothyroidism in patients with renal failure (RF) causes many metabolic and clinical problems, and both these diseases can mutually exacerbate their disturbances. The aim of this study was to evaluate the effect of hypothyroidism, and end-stage renal disease (ESRD) on conversion of thyroid hormones (TH) in patients with ESRD treated with chronic hemodialysis (HD). The study was performed in 74 patients, including 41 women (K) and 33 men (M) aged 28-83 y.o. in 4 groups: G1 - 12 people with ESRD treated with HD and with newly diagnosed hypothyroidism without substitution (6 K and M 6) aged 66,83±12,90 y.o., G2 - 26 patients with ESRD treated with HD without hypothyroidism (10 F, 16 M) aged 58,85±15,52 y.o., G3 - 11 hypothyroid patients without RF (9 K, 2 M) aged 54,73±21,26 y.o., G4 - 25-persons from control group of healthy subjects (16 M, 9 M) aged 51,24±12,58 y.o. In all subjects the concentration of TSH and TH (T4, T3, fT4, TSH, FT3, rT3) were measured and values of conversion factors (T3/T4, FT3/ fT4, rT3/fT4 and rT3/fT3) and binding TH to protein factors (fT4/T4 and fT3/T3) were calculated. Lower concentration of T3 (p=0.012), fT3 (p<0.001) i fT4 (p=0.014) was found in patients without hypothyroidism than in healthy subjects. Renal failure with concomitant hypothyroidism intensify the disturbances of T4 to T3 conversion (p=0.034) and hypothyroidism with concomitant renal failure disrupts binding of T3 to proteins (p=0.001). FT3 to fT4 ratio in renal failure with concomitant hypothyroidism group was significantly lower than in each other group. rT3 concentrations were the highest in healthy subjects. Concomitance of hypothyroidism and end-stage renal disease reduces the conversion of thyroxine to triiodothyronine, but does not increase the production of rT3. Hypothyroidism significantly increases the disorders of thyroid hormones in end-stage renal disease. There is decreased tendency to bind of thyroid hormone to protein in hypothyroidism in patients with end-stage renal disease.

Changes of thyroid hormone levels and related gene expression in zebrafish on early life stage exposure to triadimefon.

PubMed

Liu, Shaoying; Chang, Juhua; Zhao, Ying; Zhu, Guonian

2011-11-01

In this study, zebrafish was exposed to triadimefon. Thyroid hormones levels and the expression of related genes in the hypothalamic-pituitary-thyroid (HPT) axis, including thyroid-stimulating hormone (TSH-beta), deiodinases (dio1 and dio2) and the thyroid hormone receptor (thraa and thrb) were evaluated. After triadimefon exposure, increased T4 can be explained by increased thyroid-stimulating hormone (TSH-beta). The conversion of T4 to T3 (deiodinase type I-dio1) was decreased, which reduced the T3 level. Thyroid hormone receptor beta (thrb) mRNA levels were significantly down-regulated, possibly as a response to the decreased T3 levels. The overall results indicated that triadimefon exposure could alter gene expression in the HPT axis and that mechanisms of disruption of thyroid status by triadimefon could occur at several steps in the synthesis, regulation, and action of thyroid hormones. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

Thyroid hormone transporters in health and disease: advances in thyroid hormone deiodination.

PubMed

Köhrle, Josef

2007-06-01

Thyroid hormone metabolism by the three deiodinase selenoproteins -- DIO1, DIO2, and DIO3 -- regulates the local availability of various iodothyronine metabolites and thus mediates their effects on gene expression, thermoregulation, energy metabolism, and many key reactions during the development and maintenance of an adult organism. Circulating serum levels of thyroid hormone and thyroid-stimulating hormone, used as a combined indicator of thyroid hormone status, reflect a composite picture of: thyroid secretion; tissue-specific production of T(3) by DIO1 and DIO2 activity, which both contribute to circulating levels of T(3); and degradation of the prohormone T4, of the thyromimetically active T(3), of the inactive rT(3), of other iodothyronines metabolites with a lower iodine content and of thyroid hormone conjugates. Degradation reactions are catalyzed by either DIO1 or DIO3. Aberrant expression of individual deiodinases in disease, single nucleotide polymorphisms in their genes, and novel regulators of DIO gene expression (such as bile acids) provide a more complex picture of the fine tuning and the adaptation of systemic and local bioavailability of thyroid hormones.

A TSHR-LH/CGR chimera that measures functional thyroid-stimulating autoantibodies (TSAb) can predict remission or recurrence in Graves' patients undergoing antithyroid drug (ATD) treatment.

PubMed

Giuliani, Cesidio; Cerrone, Dominique; Harii, Norikazu; Thornton, Mark; Kohn, Leonard D; Dagia, Nilesh M; Bucci, Ines; Carpentieri, Maria; Di Nenno, Barbara; Di Blasio, Andrea; Vitti, Paolo; Monaco, Fabrizio; Napolitano, Giorgio

2012-07-01

A functional thyroid-stimulating autoantibodies (TSAb) assay using a thyroid-stimulating hormone receptor chimera (Mc4) appears to be clinically more useful than the commonly used assay, a binding assay that measures all the antibodies binding to the thyroid-stimulating hormone receptor without functional discrimination, in diagnosing patient with Graves' disease (GD). The objective of the study was to investigate whether an Mc4 assay can predict relapse/remission of hyperthyroidism after antithyroid drug (ATD) treatment in patients with GD. An Mc4 assay was used to prospectively track TSAb activity in GD patients treated with ATD over a 5-yr period. GD patients from the Chieti University participated in this study. Interventions included the assessment of patients' sera using the Mc4 assay, the Mc4-derivative assay (Thyretain), and a human monoclonal thyroid-stimulating hormone receptor antibody, M22 assay. The Mc4 assay, a sensitive index of remission and recurrence, was used in this study. The TSAb levels significantly decreased only in the remitting group as evidenced by Mc4 assay values at the end of ATD (0.96 ± 1.47, 10.9 ± 26.6. and 24.7 ± 37.5 arbitrary units for the remitting, relapsing, and unsuspended therapy groups, respectively). Additional prognostic help was obtained by thyroid volume measurements at the end of treatment. Although not statistically significant, the Mc4 assay has a trend toward improved positive predictive value (95.4 vs. 84.2 or 87.5%), specificity (96.4 vs. 86.4 and 90.9%), and accuracy (87.3 vs. 83.3 and 80.9%) comparing the Mc4, Thyretain, and M22 assays, respectively. Thyretain has a trend toward improved negative predictive value (82.6 vs. 81.8 and 76.9%) and sensitivity (80 vs. 77.8 and 70%) comparing Thyretain, Mc4, and M22 assays, respectively. The Mc4 assay is a clinically useful index of remission and relapse in patients with GD. Larger studies are required to confirm these findings.

Hypothyroidism: etiology, diagnosis, and management.

PubMed

Almandoz, Jaime P; Gharib, Hossein

2012-03-01

Hypothyroidism is the result of inadequate production of thyroid hormone or inadequate action of thyroid hormone in target tissues. Primary hypothyroidism is the principal manifestation of hypothyroidism, but other causes include central deficiency of thyrotropin-releasing hormone or thyroid-stimulating hormone (TSH), or consumptive hypothyroidism from excessive inactivation of thyroid hormone. Subclinical hypothyroidism is present when there is elevated TSH but a normal free thyroxine level. Treatment involves oral administration of exogenous synthetic thyroid hormone. This review presents an update on the etiology and types of hypothyroidism, including subclinical disease; drugs and thyroid function; and diagnosis and treatment of hypothyroidism. Copyright © 2012 Elsevier Inc. All rights reserved.

Withdrawal From Chronic Nicotine Reduces Thyroid Hormone Levels and Levothyroxine Treatment Ameliorates Nicotine Withdrawal-Induced Deficits in Hippocampus-Dependent Learning in C57BL/6J Mice

PubMed Central

Leach, Prescott T.; Holliday, Erica; Kutlu, Munir G.

2015-01-01

Introduction: Cigarette smoking alters a variety of endocrine systems including thyroid hormones. Altered thyroid hormone signaling may lead to a subclinical or overt hypothyroid condition that could contribute to nicotine withdrawal-related symptoms, such as cognitive deficits. Thus, normalizing thyroid hormone levels may represent a novel therapeutic target for ameliorating nicotine withdrawal-associated cognitive deficits. Methods: The current studies conducted an analysis of serum thyroid hormone levels after chronic and withdrawal from chronic nicotine treatment in C57BL/6J mice using an enzyme-linked immunosorbent assay. The present studies also evaluated the effect of synthetic thyroid hormone (levothyroxine) on contextual and cued memory. Results: The current studies found that nicotine withdrawal reduces secreted thyroid hormone levels by 9% in C57BL/6J mice. Further, supplemental thyroid hormone not only enhanced memory in naïve animals, but also ameliorated deficits in hippocampus-dependent learning associated with nicotine withdrawal. Conclusions: These results suggest that smokers attempting to quit should be monitored closely for changes in thyroid function. If successfully treated, normalization of thyroid hormone levels may ameliorate some deficits associated with nicotine withdrawal and this may lead to higher rates of successful abstinence. PMID:25358661

Control of Pituitary Thyroid-stimulating Hormone Synthesis and Secretion by Thyroid Hormones during Xenopus Metamorphosis

EPA Science Inventory

Serum thyroid hormone (TH) concentrations in anuran larvae rise rapidly during metamorphosis. Such a rise in an adult anuran would inevitably trigger a negative feedback response resulting in decreased synthesis and secretion of thyroid-stimulating hormone (TSH) by the pituitary....

Thyroid hormone and the central control of homeostasis.

PubMed

Warner, Amy; Mittag, Jens

2012-08-01

It has long been known that thyroid hormone has profound direct effects on metabolism and cardiovascular function. More recently, it was shown that the hormone also modulates these systems by actions on the central autonomic control. Recent studies that either manipulated thyroid hormone signalling in anatomical areas of the brain or analysed seasonal models with an endogenous fluctuation in hypothalamic thyroid hormone levels revealed that the hormone controls energy turnover. However, most of these studies did not progress beyond the level of anatomical nuclei; thus, the neuronal substrates as well as the molecular mechanisms remain largely enigmatic. This review summarises the evidence for a role of thyroid hormone in the central autonomic control of peripheral homeostasis and advocates novel strategies to address thyroid hormone action in the brain on a cellular level.

Hyperthyroidism: Diagnosis and Treatment.

PubMed

Kravets, Igor

2016-03-01

Hyperthyroidism is an excessive concentration of thyroid hormones in tissues caused by increased synthesis of thyroid hormones, excessive release of preformed thyroid hormones, or an endogenous or exogenous extrathyroidal source. The most common causes of an excessive production of thyroid hormones are Graves disease, toxic multinodular goiter, and toxic adenoma. The most common cause of an excessive passive release of thyroid hormones is painless (silent) thyroiditis, although its clinical presentation is the same as with other causes. Hyperthyroidism caused by overproduction of thyroid hormones can be treated with antithyroid medications (methimazole and propylthiouracil), radioactive iodine ablation of the thyroid gland, or surgical thyroidectomy. Radioactive iodine ablation is the most widely used treatment in the United States. The choice of treatment depends on the underlying diagnosis, the presence of contraindications to a particular treatment modality, the severity of hyperthyroidism, and the patient's preference.

Effects of a monophasic combined oral contraceptive containing nomegestrol acetate and 17β-oestradiol in comparison to one containing levonorgestrel and ethinylestradiol on markers of endocrine function.

PubMed

Ågren, Ulla M; Anttila, Marjatta; Mäenpää-Liukko, Kristiina; Rantala, Maija-Liisa; Rautiainen, Hilkka; Sommer, Werner F; Mommers, Ellen

2011-12-01

To compare the effects of two monophasic combined oral contraceptives, containing either nomegestrol acetate/17β-oestradiol (NOMAC/E2) or levonorgestrel/ ethinylestradiol (LNG/EE) on endocrine function, androgens, and sex hormone-binding globulin (SHBG). Randomised, open-label, multi-centre trial involving 121 healthy women, aged 18-50 years old. Participants received NOMAC/E2 (2.5 mg/1.5 mg) in a 24/4-day regimen (n=60) or LNG/EE (150 μg/30 μg) in a 21/7-day regimen (n=61) for six cycles. The primary outcome was the change from baseline to cycle 6 in markers of adrenal and thyroid function, androgens, and SHBG. Total cortisol, corticosteroid-binding globulin (CBG), and thyroxine-binding globulin (TBG) increased from baseline in both groups, with significantly greater increases in the LNG/EE group. No relevant changes from baseline or differences between the groups were observed for thyroid-stimulating hormone (TSH) and free thyroxine (T4). Androgens and androgen precursors decreased from baseline in both groups, with significantly greater decreases in the LNG/EE group (except for free testosterone). A greater increase in SHBG was observed with NOMAC/E2 than with LNG/EE. NOMAC/E2 has significantly less influence on markers of adrenal and thyroid function and androgens than LNG/EE. The clinical relevance of these findings requires further study.

Effects of a monophasic combined oral contraceptive containing nomegestrol acetate and 17β-oestradiol in comparison to one containing levonorgestrel and ethinylestradiol on markers of endocrine function

PubMed Central

Ågren, Ulla M; Anttilat, Marjatta; Mäenpää-Liukko, Kristiina; Rantala, Maija-Liisa; Rautiainen, Hilkka; Sommer, Werner F; Mommers, Ellen

2011-01-01

Objectives To compare the effects of two monophasic combined oral contraceptives, containing either nomegestrol acetate/17β-oestradiol (NOMAC/E2) or levonorgestrel/ ethinylestradiol (LNG/EE) on endocrine function, androgens, and sex hormone-binding globulin (SHBG). Methods Randomised, open-label, multi-centre trial involving 121 healthy women, aged 18-50 years old. Participants received NOMAC/E2 (2.5 mg/1.5 mg) in a 24/4-day regimen (n = 60) or LNG/EE (150 μg/30 μg) in a 21/7-day regimen (n = 61) for six cycles. The primary outcome was the change from baseline to cycle 6 in markers of adrenal and thyroid function, androgens, and SHBG. Results Total cortisol, corticosteroid-binding globulin (CBG), and thyroxine-binding globulin (TBG) increased from baseline in both groups, with significantly greater increases in the LNG/EE group. No relevant changes from baseline or differences between the groups were observed for thyroid-stimulating hormone (TSH) and free thyroxine (T4). Androgens and androgen precursors decreased from baseline in both groups, with significantly greater decreases in the LNG/EE group (except for free testosterone). A greater increase in SHBG was observed with NOMAC/E2 than with LNG/EE. Conclusions NOMAC/E2 has significantly less influence on markers of adrenal and thyroid function and androgens than LNG/EE. The clinical relevance of these findings requires further study. PMID:21942708

Thyroid Function Tests.

ERIC Educational Resources Information Center

Glover, Irving T.

1979-01-01

Describes two tests, T-4 and T-3, for hypothyroid based on the binding of the hormones by proteins. The tests were performed in courses for physicians, clinical chemists, laboratory technicians, and undergraduate science students by the individuals involved and on their own sera. These tests are commercially available in kit form. (GA)

New avenues for regulation of lipid metabolism by thyroid hormones and analogs

PubMed Central

Senese, Rosalba; Lasala, Pasquale; Leanza, Cristina; de Lange, Pieter

2014-01-01

Weight loss due to negative energy balance is a goal in counteracting obesity and type 2 diabetes mellitus. The thyroid is known to be an important regulator of energy metabolism through the action of thyroid hormones (THs). The classic, active TH, 3,5,3′-triiodo-L-thyronine (T3) acts predominantly by binding to nuclear receptors termed TH receptors (TRs), that recognize TH response elements (TREs) on the DNA, and so regulate transcription. T3 also acts through “non-genomic” pathways that do not necessarily involve TRs. Lipid-lowering therapies have been suggested to have potential benefits, however, the establishment of comprehensive therapeutic strategies is still awaited. One drawback of using T3 in counteracting obesity has been the occurrence of heart rhythm disturbances. These are mediated through one TR, termed TRα. The end of the previous century saw the exploration of TH mimetics that specifically bind to TR beta in order to prevent cardiac disturbances, and TH derivatives such as 3,5-diiodo-L-thyronine (T2), that possess interesting biological activities. Several TH derivatives and functional analogs have low affinity for the TRs, and are suggested to act predominantly through non-genomic pathways. All this has opened new perspectives in thyroid physiology and TH derivative usage as anti-obesity therapies. This review addresses the pros and cons of these compounds, in light of their effects on energy balance regulation and on lipid/cholesterol metabolism. PMID:25538628

New avenues for regulation of lipid metabolism by thyroid hormones and analogs.

PubMed

Senese, Rosalba; Lasala, Pasquale; Leanza, Cristina; de Lange, Pieter

2014-01-01

Weight loss due to negative energy balance is a goal in counteracting obesity and type 2 diabetes mellitus. The thyroid is known to be an important regulator of energy metabolism through the action of thyroid hormones (THs). The classic, active TH, 3,5,3'-triiodo-L-thyronine (T3) acts predominantly by binding to nuclear receptors termed TH receptors (TRs), that recognize TH response elements (TREs) on the DNA, and so regulate transcription. T3 also acts through "non-genomic" pathways that do not necessarily involve TRs. Lipid-lowering therapies have been suggested to have potential benefits, however, the establishment of comprehensive therapeutic strategies is still awaited. One drawback of using T3 in counteracting obesity has been the occurrence of heart rhythm disturbances. These are mediated through one TR, termed TRα. The end of the previous century saw the exploration of TH mimetics that specifically bind to TR beta in order to prevent cardiac disturbances, and TH derivatives such as 3,5-diiodo-L-thyronine (T2), that possess interesting biological activities. Several TH derivatives and functional analogs have low affinity for the TRs, and are suggested to act predominantly through non-genomic pathways. All this has opened new perspectives in thyroid physiology and TH derivative usage as anti-obesity therapies. This review addresses the pros and cons of these compounds, in light of their effects on energy balance regulation and on lipid/cholesterol metabolism.

Novel neural pathways for metabolic effects of thyroid hormone.

PubMed

Fliers, Eric; Klieverik, Lars P; Kalsbeek, Andries

2010-04-01

The relation between thyrotoxicosis, the clinical syndrome resulting from exposure to excessive thyroid hormone concentrations, and the sympathetic nervous system remains enigmatic. Nevertheless, beta-adrenergic blockers are widely used to manage severe thyrotoxicosis. Recent experiments show that the effects of thyrotoxicosis on hepatic glucose production and insulin sensitivity can be modulated by selective hepatic sympathetic and parasympathetic denervation. Indeed, thyroid hormone stimulates hepatic glucose production via a sympathetic pathway, a novel central pathway for thyroid hormone action. Rodent studies suggest that similar neural routes exist for thyroid hormone analogues (e.g. thyronamines). Further elucidation of central effects of thyroid hormone on autonomic outflow to metabolic organs, including the thyroid and brown adipose tissue, will add to our understanding of hyperthyroidism. Copyright 2009 Elsevier Ltd. All rights reserved.

Graves' disease: diagnostic and therapeutic challenges (multimedia activity).

PubMed

Kahaly, George J; Grebe, Stefan K G; Lupo, Mark A; McDonald, Nicole; Sipos, Jennifer A

2011-06-01

Graves' disease is the most common cause of hyperthyroidism in the United States. Graves' disease occurs more often in women with a female:male ratio of 5:1 and a population prevalence of 1% to 2%. A genetic determinant to the susceptibility to Graves' disease is suspected because of familial clustering of the disease, a high sibling recurrence risk, the familial occurrence of thyroid autoantibodies, and the 30% concordance in disease status between identical twins. Graves' disease is an autoimmune thyroid disorder characterized by the infiltration of immune effector cells and thyroid antigen-specific T cells into the thyroid and thyroid-stimulating hormone receptor expressing tissues, with the production of autoantibodies to well-defined thyroidal antigens, such as thyroid peroxidase, thyroglobulin, and the thyroid-stimulating hormone receptor. The thyroid-stimulating hormone receptor is central to the regulation of thyroid growth and function. Stimulatory autoantibodies in Graves' disease activate the thyroid-stimulating hormone receptor leading to thyroid hyperplasia and unregulated thyroid hormone production and secretion. Below-normal levels of baseline serum thyroid-stimulating hormone receptor, normal to elevated serum levels of T4, elevated serum levels of T3 and thyroid-stimulating hormone receptor autoantibodies, and a diffusely enlarged, heterogeneous, hypervascular (increased Doppler flow) thyroid gland confirm diagnosis of Graves' disease (available at: http://supplements.amjmed.com/2010/hyperthyroid/faculty.php). This Resource Center is also available through the website of The American Journal of Medicine (www.amjmed.com). Click on the “Thyroid/Graves' Disease” link in the “Resource Centers” section, found on the right side of the Journal homepage. Copyright © 2011 Elsevier Inc. All rights reserved.

The role of thyroid hormone signaling in the prevention of digestive system cancers.

PubMed

Brown, Adam R; Simmen, Rosalia C M; Simmen, Frank A

2013-08-06

Thyroid hormones play a critical role in the growth and development of the alimentary tract in vertebrates. Their effects are mediated by nuclear receptors as well as the cell surface receptor integrin αVβ3. Systemic thyroid hormone levels are controlled via activation and deactivation by iodothyronine deiodinases in the liver and other tissues. Given that thyroid hormone signaling has been characterized as a major effector of digestive system growth and homeostasis, numerous investigations have examined its role in the occurrence and progression of cancers in various tissues of this organ system. The present review summarizes current findings regarding the effects of thyroid hormone signaling on cancers of the esophagus, stomach, liver, pancreas, and colon. Particular attention is given to the roles of different thyroid hormone receptor isoforms, the novel integrin αVβ3 receptor, and thyroid hormone-related nutrients as possible protective agents and therapeutic targets. Future investigations geared towards a better understanding of thyroid hormone signaling in digestive system cancers may provide preventive or therapeutic strategies to diminish risk, improve outcome and avert recurrence in afflicted individuals.

The Role of Thyroid Hormone Signaling in the Prevention of Digestive System Cancers

PubMed Central

Brown, Adam R.; Simmen, Rosalia C. M.; Simmen, Frank A.

2013-01-01

Thyroid hormones play a critical role in the growth and development of the alimentary tract in vertebrates. Their effects are mediated by nuclear receptors as well as the cell surface receptor integrin αVβ3. Systemic thyroid hormone levels are controlled via activation and deactivation by iodothyronine deiodinases in the liver and other tissues. Given that thyroid hormone signaling has been characterized as a major effector of digestive system growth and homeostasis, numerous investigations have examined its role in the occurrence and progression of cancers in various tissues of this organ system. The present review summarizes current findings regarding the effects of thyroid hormone signaling on cancers of the esophagus, stomach, liver, pancreas, and colon. Particular attention is given to the roles of different thyroid hormone receptor isoforms, the novel integrin αVβ3 receptor, and thyroid hormone-related nutrients as possible protective agents and therapeutic targets. Future investigations geared towards a better understanding of thyroid hormone signaling in digestive system cancers may provide preventive or therapeutic strategies to diminish risk, improve outcome and avert recurrence in afflicted individuals. PMID:23924944

Human amniotic fluid contaminants alter thyroid hormone signalling and early brain development in Xenopus embryos

NASA Astrophysics Data System (ADS)

Fini, Jean-Baptiste; Mughal, Bilal B.; Le Mével, Sébastien; Leemans, Michelle; Lettmann, Mélodie; Spirhanzlova, Petra; Affaticati, Pierre; Jenett, Arnim; Demeneix, Barbara A.

2017-03-01

Thyroid hormones are essential for normal brain development in vertebrates. In humans, abnormal maternal thyroid hormone levels during early pregnancy are associated with decreased offspring IQ and modified brain structure. As numerous environmental chemicals disrupt thyroid hormone signalling, we questioned whether exposure to ubiquitous chemicals affects thyroid hormone responses during early neurogenesis. We established a mixture of 15 common chemicals at concentrations reported in human amniotic fluid. An in vivo larval reporter (GFP) assay served to determine integrated thyroid hormone transcriptional responses. Dose-dependent effects of short-term (72 h) exposure to single chemicals and the mixture were found. qPCR on dissected brains showed significant changes in thyroid hormone-related genes including receptors, deiodinases and neural differentiation markers. Further, exposure to mixture also modified neural proliferation as well as neuron and oligodendrocyte size. Finally, exposed tadpoles showed behavioural responses with dose-dependent reductions in mobility. In conclusion, exposure to a mixture of ubiquitous chemicals at concentrations found in human amniotic fluid affect thyroid hormone-dependent transcription, gene expression, brain development and behaviour in early embryogenesis. As thyroid hormone signalling is strongly conserved across vertebrates the results suggest that ubiquitous chemical mixtures could be exerting adverse effects on foetal human brain development.

Molecular characterization of human thyroid hormone receptor β isoform 4.

PubMed

Moriyama, Kenji; Yamamoto, Hiroyuki; Futawaka, Kumi; Atake, Asami; Kasahara, Masato; Tagami, Tetsuya

2016-01-01

Thyroid hormone exerts a pleiotropic effect on development, differentiation, and metabolism through thyroid hormone receptor (TR). A novel thyroid hormone receptor β isoform (TRβ4) was cloned using PCR from a human pituitary cDNA library as a template. We report here the characterization of TRβ4 from a molecular basis. Temporal expression of TRβ4 during the fetal period is abundant in the brain and kidney, comparable with the adult pattern. Western blot analysis revealed that TRs are ubiquitination labile proteins, while TRβ1 is potentially stable. TRβ1, peroxisome proliferator-activated receptors (PPAR), and vitamin D receptor (VDR), which belong to class II transcription factors that function via the formation of heterodimeric complexes with retinoid X receptor (RXR), were suppressed by TRβ4 in a dose-dependent manner. Thus, TRβ4 exhibits ligand-independent transcriptional silencing, possibly as a substitute for dimerized RXR. In this study, TRβ1 and TRβ4 transcripts were detected in several cell lines. Quantitative RT-PCR assay showed that the expression of TRβ4 in human embryonic carcinoma cells of the testis was suppressed by sex hormone in a reciprocal manner to TRβ1. In contrast, TRβ4 was expressed under a high dose of triiodothyronine (T3) in a reciprocal manner to TRβ1. Finally, in transiently transfected NIH-3T3 cells, green fluorescence protein (GFP)-tagged TRβ4 was mostly nuclear in both the absence and the presence of T3. By mutating defined regions of both TRβs, we found that both TRβ1 and TRβ4 had altered nuclear/cytoplasmic distribution as compared with wild-type, and different to T3 and the nuclear receptor corepressor (NCoR). Thus, site-specific DNA binding is not essential for maintaining TRβs within the nucleus.

Thyroid hormone concentrations, disease, physical function, and mortality in elderly men.

PubMed

van den Beld, Annewieke W; Visser, Theo J; Feelders, Richard A; Grobbee, Diederick E; Lamberts, Steven W J

2005-12-01

Physiological changes in thyroid hormone concentrations might be related to changes in the overall physical function in the elderly. We determined to what extent thyroid hormone concentrations are related to physical function and mortality in elderly men. A longitudinal population study (the Zoetermeer study) was conducted. Mortality was registered in the subsequent 4 yr. Four hundred three independently and ambulatory living men (aged 73-94 yr) participated. The study examined the association between serum thyroid hormones and parameters of physical function as well as the association with mortality. TSH, free T4 (FT4) total T4, T3, rT3, and T4-binding globulin were measured. Physical function was estimated by the number of problems in activities of daily living, a measure of physical performance score (PPS), leg extensor strength and grip strength, bone density, and body composition. Serum rT3 increased significantly with age and the presence of disease. Sixty-three men met the biochemical criteria for the low T3 syndrome (decreased serum T3 and increased serum rT3). This was associated with a lower PPS, independent of disease. Furthermore, higher serum FT4 (within the normal range of healthy adults) and rT3 (above the normal range of healthy adults) were related with a lower grip strength and PPS, independent of age and disease. Isolated low T3 was associated with a better PPS and a higher lean body mass. Low FT4 was related to a decreased risk of 4-yr mortality. In a population of independently living elderly men, higher FT4 and rT3 concentrations are associated with a lower physical function. High serum rT3 may result from a decreased peripheral metabolism of thyroid hormones due to the aging process itself and/or disease and may reflect a catabolic state. Low serum FT4 is associated with a better 4-yr survival; this may reflect an adaptive mechanism to prevent excessive catabolism.

Assessment of criteria used by veterinary practitioners to diagnose hypothyroidism in sighthounds and investigation of serum thyroid hormone concentrations in healthy Salukis.

PubMed

Shiel, Robert E; Sist, MaryDee; Nachreiner, Raymond F; Ehrlich, Claire P; Mooney, Carmel T

2010-02-01

To assess use of serum thyroid hormone concentrations by veterinarians to diagnose hypothyroidism in sighthounds and to evaluate serum thyroid hormone concentrations in healthy Salukis. Retrospective case series and cross-sectional study. 398 sighthounds of various breeds with a diagnosis of hypothyroidism and 283 healthy Salukis. Pretreatment thyroid hormone assay results from sighthounds subsequently classified as hypothyroid by practitioners were retrieved from a laboratory database. In healthy Salukis, serum concentrations of total thyroxine (T(4)), free T(4), total triiodothyronine (T(3)), free T(3), and thyroid-stimulating hormone (TSH) and antibodies against thyroglobulin and thyroid hormones were assayed. Records indicated hypothyroidism had been diagnosed in 303 (76.1%) sight-hounds on the basis of low serum thyroid hormone concentrations alone and in 30 (7.5%) others despite all thyroid hormone indices being within reference limits. Only 65 (16.3%) dogs had a high TSH concentration or positive thyroglobulin autoantibody result to support the diagnosis. In healthy Salukis, median (reference limits) serum concentrations of total T(4), free T(4), total T(3), free T(3), and TSH were 13.0 nmol/L (2.8 to 40.0 nmol/L), 12.0 pmol/L (2.0 to 30.3 pmol/L), 1.0 nmol/L (0.4 to 2.1 nmol/L), 4.0 pmol/L (1.6 to 7.7 pmol/L), and 0.18 ng/mL (0 to 0.86 ng/mL), respectively. Diagnosis of hypothyroidism by practitioners was most often made without adequate supportive laboratory evidence. Thyroid hormone values in healthy Salukis differed markedly from standard reference limits for some, but not all, thyroid hormone indices. Breed-specific reference limits should be used when interpreting thyroid hormone profiles of sighthounds.

Thyroid hormone accelerates the differentiation of adult hippocampal progenitors.

PubMed

Kapoor, R; Desouza, L A; Nanavaty, I N; Kernie, S G; Vaidya, V A

2012-09-01

Disrupted thyroid hormone function evokes severe physiological consequences in the immature brain. In adulthood, although clinical reports document an effect of thyroid hormone status on mood and cognition, the molecular and cellular changes underlying these behavioural effects are poorly understood. More recently, the subtle effects of thyroid hormone on structural plasticity in the mature brain, in particular on adult hippocampal neurogenesis, have come to be appreciated. However, the specific stages of adult hippocampal progenitor development that are sensitive to thyroid hormone are not defined. Using nestin-green fluorescent protein reporter mice, we demonstrate that thyroid hormone mediates its effects on hippocampal neurogenesis by influencing Type 2b and Type 3 progenitors, although it does not alter proliferation of either the Type 1 quiescent progenitor or the Type 2a amplifying neural progenitor. Thyroid hormone increases the number of doublecortin (DCX)-positive Type 3 progenitors, and accelerates neuronal differentiation into both DCX-positive immature neurones and neuronal nuclei-positive granule cell neurones. Furthermore, we show that this increase in neuronal differentiation is accompanied by a significant induction of specific transcription factors involved in hippocampal progenitor differentiation. In vitro studies using the neurosphere assay support a direct effect of thyroid hormone on progenitor development because neurospheres treated with thyroid hormone are shifted to a more differentiated state. Taken together, our results indicate that thyroid hormone mediates its neurogenic effects via targeting Type 2b and Type 3 hippocampal progenitors, and suggests a role for proneural transcription factors in contributing to the effects of thyroid hormone on neuronal differentiation of adult hippocampal progenitors. © 2012 The Authors. Journal of Neuroendocrinology © 2012 British Society for Neuroendocrinology.

Thyroid hormones and fetal brain development.

PubMed

Pemberton, H N; Franklyn, J A; Kilby, M D

2005-08-01

Thyroid hormones are intricately involved in the developing fetal brain. The fetal central nervous system is sensitive to the maternal thyroid status. Critical amounts of maternal T3 and T4 must be transported across the placenta to the fetus to ensure the correct development of the brain throughout ontogeny. Severe mental retardation of the child can occur due to compromised iodine intake or thyroid disease. This has been reported in areas of the world with iodine insufficiency, New Guinea, and also in mother with thyroid complications such as hypothyroxinaemia and hyperthyroidism. The molecular control of thyroid hormones by deiodinases for the activation of thyroid hormones is critical to ensure the correct amount of active thyroid hormones are temporally supplied to the fetus. These hormones provide timing signals for the induction of programmes for differentiation and maturation at specific stages of development. Understanding these molecular mechanisms further will have profound implications in the clinical management of individuals affected by abnormal maternal of fetal thyroid status.

The thyroid hormone receptor β induces DNA damage and premature senescence.

PubMed

Zambrano, Alberto; García-Carpizo, Verónica; Gallardo, María Esther; Villamuera, Raquel; Gómez-Ferrería, Maria Ana; Pascual, Angel; Buisine, Nicolas; Sachs, Laurent M; Garesse, Rafael; Aranda, Ana

2014-01-06

There is increasing evidence that the thyroid hormone (TH) receptors (THRs) can play a role in aging, cancer and degenerative diseases. In this paper, we demonstrate that binding of TH T3 (triiodothyronine) to THRB induces senescence and deoxyribonucleic acid (DNA) damage in cultured cells and in tissues of young hyperthyroid mice. T3 induces a rapid activation of ATM (ataxia telangiectasia mutated)/PRKAA (adenosine monophosphate-activated protein kinase) signal transduction and recruitment of the NRF1 (nuclear respiratory factor 1) and THRB to the promoters of genes with a key role on mitochondrial respiration. Increased respiration leads to production of mitochondrial reactive oxygen species, which in turn causes oxidative stress and DNA double-strand breaks and triggers a DNA damage response that ultimately leads to premature senescence of susceptible cells. Our findings provide a mechanism for integrating metabolic effects of THs with the tumor suppressor activity of THRB, the effect of thyroidal status on longevity, and the occurrence of tissue damage in hyperthyroidism.

HISTORICAL AND CURRENT PERSPECTIVE IN THE USE OF THYROID EXTRACTS FOR THE TREATMENT OF HYPOTHYROIDISM.

PubMed

Hennessey, James V

2015-10-01

To describe the history, refinements, implementation, physiology, and clinical outcomes achieved over the past several centuries of thyroid hormone replacement strategies. A Medline search was initiated using the following search terms: bioidentical thyroid hormone, thyroid hormone extract, combination thyroxine (T4) and tri-iodothyronine (T3) therapy, homeopathic thyroid hormone therapy, and thyroid hormone replacement. Pertinent articles of interest were identified by title (and where available abstract) for further review. Additional references were identified during a review of the identified literature. A rich history of physician intervention in thyroid dysfunction was identified dating back more than 2 millennia. Although not precisely documented, thyroid ingestion from animal sources had been used for centuries but was finally scientifically described and documented in Europe over 130 years ago. Since the reports by Bettencourt and Murray, there has been a continuous documentation of outcomes, refinement of hormone preparation production, and updating of recommendations for the most effective and safe use of these hormones for relieving the symptoms of hypothyroidism. As the thyroid extract preparations contain both levothyroxine (LT4) and liothyronine (LT3), current guidelines do not endorse their use as controlled studies do not clearly document enhanced objective outcomes compared with LT4 monotherapy. Among current issues cited, the optimum ratio of LT4 to LT3 has yet to be determined, and the U.S. Food and Drug Administration (FDA) does not appear to be monitoring the thyroid hormone ratios or content in extract preparations on the market. Taken together, these limitations are important detriments to the use of thyroid extract products. The evolution of thyroid hormone therapies has been significant over the extended period of time they have been in use to treat hypothyroidism. Although numerous websites continue to advocate the use of thyroid hormone extracts as a superior therapy for hypothyroidism, none of the most recent guidelines of major endocrine societies recommend thyroid extract use for hypothyroidism.

Multiple steroid and thyroid hormones detected in baleen from eight whale species

PubMed Central

Lysiak, Nadine S; Robbins, Jooke; Moore, Michael J; Seton, Rosemary E; Torres, Leigh; Buck, C Loren

2017-01-01

Abstract Recent studies have demonstrated that some hormones are present in baleen powder from bowhead (Balaena mysticetus) and North Atlantic right (Eubalaena glacialis) whales. To test the potential generalizability of this technique for studies of stress and reproduction in large whales, we sought to determine whether all major classes of steroid and thyroid hormones are detectable in baleen, and whether these hormones are detectable in other mysticetes. Powdered baleen samples were recovered from single specimens of North Atlantic right, bowhead, blue (Balaenoptera [B.]musculus), sei (B. borealis), minke (B. acutorostrata), fin (B. physalus), humpback (Megaptera novaeangliae) and gray (Eschrichtius robustus) whales. Hormones were extracted with a methanol vortex method, after which we tested all species with commercial enzyme immunoassays (EIAs, Arbor Assays) for progesterone, testosterone, 17β-estradiol, cortisol, corticosterone, aldosterone, thyroxine and tri-iodothyronine, representing a wide array of steroid and thyroid hormones of interest for whale physiology research. In total, 64 parallelism tests (8 species × 8 hormones) were evaluated to verify good binding affinity of the assay antibodies to hormones in baleen. We also tested assay accuracy, although available sample volume limited this test to progesterone, testosterone and cortisol. All tested hormones were detectable in baleen powder of all species, and all assays passed parallelism and accuracy tests. Although only single individuals were tested, the consistent detectability of all hormones in all species indicates that baleen hormone analysis is likely applicable to a broad range of mysticetes, and that the EIA kits tested here perform well with baleen extract. Quantification of hormones in baleen may be a suitable technique with which to explore questions that have historically been difficult to address in large whales, including pregnancy and inter-calving interval, age of sexual maturation, timing and duration of seasonal reproductive cycles, adrenal physiology and metabolic rate. PMID:29230292

[Effect of combined oral contraceptives on the hypophyseo-thyroid and hypophyseo-adrenal systems in women with various anatomy of the thyroid gland].

PubMed

Zigizmund, V A; Sadykova, M Sh; Samoĭlova, O N; Moiseeva, O M

1988-11-01

Potential therapeutic effects of combined oral contraceptives (COC) rigevidon and ovidon (estrogen:gestagen ratio of 1:5) were studied in 97 women aged 19-35 years. With respect to the anatomical state of the thyroid, the patients were divided into two groups: group 1 included 42 women with normal thyroid function and group 2 included 55 women with euthyroid hyperplasia of the thyroid gland of stage I-II (the anatomical state of the thyroid gland was ranked according to the five-point Swiss scale adopted by WHO in 1975). All patients had a history of pregnancy, normal delivery, or abortion. The state of the pituitary-thyroid system was estimated by absorption of iodine isotopes in the thyroid tissue, and by the blood levels of thyrotropic hormone, thyroxine-binding globulin, thyroxine, and triiodothyronine. Activity of the pituitary- adrenal system was estimated by the blood levels of adrenocorticotropic hormone (ACTH) and cortisol. Blood samples were withdrawn 9 and 10 hours prior to the onset of COC administration, and after 24 and 48 weeks of COC use. The changes in the functional state of the pituitary- thyroid system in groups 1 and 2 were identical throughout the entire period of COC administration. Progressive increase in the levels of thyroxine and triiodothyronine was associated with inhibition of the thyrotropic function of the pituitary seen as decrease in thyrotropin levels. COC administration caused decrease in size of hyperplastic tyroid gland. Prior to COC administration, women in group 2 showed significant elevation of ACTH levels and marked decrease in ACTH levels and increase in cortisol levels in both groups. Normalization of the size of thyroid gland indicated that COC be used therapeutically in patients with thyroid hyperplasia.

Krüppel-like factors are effectors of nuclear receptor signaling

PubMed Central

Knoedler, Joseph R.; Denver, Robert J.

2015-01-01

Binding of steroid and thyroid hormones to their cognate nuclear receptors (NRs) impacts virtually every aspect of postembryonic development, physiology and behavior, and inappropriate signaling by NRs may contribute to disease. While NRs regulate genes by direct binding to hormone response elements in the genome, their actions may depend on the activity of other transcription factors (TFs) that may or may not bind DNA. The Krüppel-like family of transcription factors (KLF) is an evolutionarily conserved class of DNA-binding proteins that influence many aspects of development and physiology. Several members of this family have been shown to play diverse roles in NR signaling. For example, KLFs 1) act as accessory transcription factors for NR actions, 2) regulate expression of NR genes, and 3) as gene products of primary NR response genes function as key players in NR-dependent transcriptional networks. In mouse models, deletion of different KLFs leads to aberrant transcriptional and physiological responses to hormones, underscoring the importance of these proteins in the regulation of hormonal signaling. Understanding the functional relationships between NRs and KLFs will yield important insights into mechanisms of NR signaling. In this review we present a conceptual framework for understanding how KLFs participate in NR signaling, and we provide examples of how these proteins function to effect hormone action. PMID:24642391

Neurodevelopmental Consequences of Low-Level Thyroid Hormone Disruption Induced by Environmental Contaminants

EPA Science Inventory

Inadequate levels of thyroid hormone during critical developmental periods lead to stunted growth, mental retardation, and neurological 'cretinism'. Animal models of developmental thyroid hormone deficiency mirror well the impact of severe insults to the thyroid system. However, ...

The effect of lead intoxication on endocrine functions.

PubMed

Doumouchtsis, K K; Doumouchtsis, S K; Doumouchtsis, E K; Perrea, D N

2009-02-01

Studies on the effects of lead on the endocrine system are mainly based on occupationally lead-exposed workers and experimental animal models. Although evidence is conflicting, it has been reported that accumulation of lead affects the majority of the endocrine glands. In particular, it appears to have an effect on the hypothalamic-pituitary axis causing blunted TSH, GH, and FSH/LH responses to TRH, GHRH, and GnRH stimulation, respectively. Suppressed GH release has been reported, probably caused by reduced synthesis of GHRH, inhibition of GHRH release or reduced somatotrope responsiveness. Higher levels of PRL in lead intoxication have been reported. In short-term lead-exposed individuals, high LH and FSH levels are usually associated to normal testosterone concentrations, whereas in long-term exposed individuals' low testosterone levels do not induce high LH and FSH concentrations. These findings suggest that lead initially causes some subclinical testicular damage, followed by hypothalamic or pituitary disturbance when longer periods of exposure take place. Similarly, lead accumulates in granulosa cells of the ovary, causing delays in growth and pubertal development and reduced fertility in females. In the parenchyma of adrenals histological and cytological changes are demonstrated, causing changes in plasma basal and stress-mediated corticosterone concentrations and reduced cytosolic and nuclear glucocorticoid receptor binding. Thyroid hormone kinetics are also affected. Central defect of the thyroid axis or an alteration in T4 metabolism or binding to proteins may be involved in derangements in thyroid hormone action. Lead toxicity involves alterations on calcitropic hormones' homeostasis, which increase the risk of skeletal disorders.

Biosensor discovery of thyroxine transport disrupting chemicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchesini, Gerardo R.; Meimaridou, Anastasia; Haasnoot, Willem

2008-10-01

Ubiquitous chemicals may interfere with the thyroid system that is essential in the development and physiology of vertebrates. We applied a surface plasmon resonance (SPR) biosensor-based screening method for the fast screening of chemicals with thyroxine (T4) transport disrupting activity. Two inhibition assays using the main thyroid hormone transport proteins, T4 binding globulin (TBG) and transthyretin (TTR), in combination with a T4-coated biosensor chip were optimized and automated for screening chemical libraries. The transport protein-based biosensor assays were rapid, high throughput and bioeffect-related. A library of 62 chemicals including the natural hormones, polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs) and metabolites,more » halogenated bisphenol A (BPA), halogenated phenols, pharmaceuticals, pesticides and other potential environmentally relevant chemicals was tested with the two assays. We discovered ten new active compounds with moderate to high affinity for TBG with the TBG assay. Strikingly, the most potent binding was observed with hydroxylated metabolites of the brominated diphenyl ethers (BDEs) BDE 47, BDE 49 and BDE 99, that are commonly found in human plasma. The TTR assay confirmed the activity of previously identified hydroxylated metabolites of PCBs and PBDEs, halogenated BPA and genistein. These results show that the hydroxylated metabolites of the ubiquitous PBDEs not only target the T4 transport at the TTR level, but also, and to a great extent, at the TBG level where most of the T4 in humans is circulating. The optimized SPR biosensor-based transport protein assay is a suitable method for high throughput screening of large libraries for potential thyroid hormone disrupting compounds.« less

Alternatives to in vivo tests to detect endocrine disrupting chemicals (EDCs) in fish and amphibians--screening for estrogen, androgen and thyroid hormone disruption.

PubMed

Scholz, S; Renner, P; Belanger, S E; Busquet, F; Davi, R; Demeneix, B A; Denny, J S; Léonard, M; McMaster, M E; Villeneuve, D L; Embry, M R

2013-01-01

Endocrine disruption is considered a highly relevant hazard for environmental risk assessment of chemicals, plant protection products, biocides and pharmaceuticals. Therefore, screening tests with a focus on interference with estrogen, androgen, and thyroid hormone pathways in fish and amphibians have been developed. However, they use a large number of animals and short-term alternatives to animal tests would be advantageous. Therefore, the status of alternative assays for endocrine disruption in fish and frogs was assessed by a detailed literature analysis. The aim was to (i) determine the strengths and limitations of alternative assays and (ii) present conclusions regarding chemical specificity, sensitivity, and correlation with in vivo data. Data from 1995 to present were collected related to the detection/testing of estrogen-, androgen-, and thyroid-active chemicals in the following test systems: cell lines, primary cells, fish/frog embryos, yeast and cell-free systems. The review shows that the majority of alternative assays measure effects directly mediated by receptor binding or resulting from interference with hormone synthesis. Other mechanisms were rarely analysed. A database was established and used for a quantitative and comparative analysis. For example, a high correlation was observed between cell-free ligand binding and cell-based reporter cell assays, between fish and frog estrogenic data and between fish embryo tests and in vivo reproductive effects. It was concluded that there is a need for a more systematic study of the predictive capacity of alternative tests and ways to reduce inter- and intra-assay variability.

Wild fish from the Bay of Quinte Area of Concern contain elevated tissue concentrations of PCBs and exhibit evidence of endocrine-related health effects.

PubMed

Simmons, D B D; McMaster, M E; Reiner, E J; Hewitt, L M; Parrott, J L; Park, B J; Brown, S B; Sherry, J P

2014-05-01

The Bay of Quinte (BOQ) is an Area of Concern listed under the Great Lakes Water Quality Agreement. The presence of dioxins and dioxin-like PCBs in fish in the BOQ AOC has led to restrictions on fish consumption by humans, which is a beneficial use impairment. Adult yellow perch (Perca flavescens) and brown bullhead (Ameiurus nebulosus) were sampled from Trenton, Belleville, and Deseronto (reference site) in the BOQ. A suite of hormone assays and various measures of exposure and/or sublethal health effects were used to assess the health status of fish of both species and sex. Condition factor, hepatosomatic index, ethoxyresorufin-O-deethylase activity, circulating steroid and thyroid hormones, thyroid activation, oocyte size distribution, spermatogenic cell stages, and plasma vitellogenin were among the endpoints that were significantly (p < 0.05) affected by location. Many of those effects corresponded with significantly (p < 0.05) greater tissue concentrations of polychlorinated biphenyls (PCBs) at Belleville and Trenton. Hepatic extracts from brown bullhead sampled from Trenton had significantly (p < 0.05) greater binding activity to the androgen receptor and sex steroid binding protein. Taken together, these data and preliminary data from a concomitant study suggest that PCBs are likely being hydroxylated in vivo, resulting in enhanced bioactivity at endocrine receptors and measurable health responses. The present study supports the growing body of evidence that PCBs and their metabolites can affect fish thyroid and steroid hormone systems. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

[Sub-acute thyroiditis in a patient on immunosuppressive treatment].

PubMed

D'Amico, Giovanna; Di Crescenzo, Vincenzo; Caleo, Alessia; Garzi, Alfredo; Vitale, Mario

2013-01-01

Sub-acute thyroiditis or De Quervain's thyroiditis is a viral, inflammatory disease which causes the serum release of thyroidal hormones and hyperthyroidism. The pathogenesis of thyroid follicle damage is unclear because the exclusive viral action or a concomitant autoimmune component, determined by the lymphoid infiltrate remain to be assessed. We describe the case of a patient under immunosuppressive treatment, who developed sub-acute thyroiditis with hormone release and hyperthyroidism. The patient, while was under immunosuppressive treatment for kidney transplant, exhibited a clinical picture and hormonal profile of hyperthyroidism. Thyroid scintiscan exhibited an extremely low uptake. Fine-needle cytologic diagnosis was granulomatous sub-acute thyroiditis (De Quervain's thyroiditis). This case suggests the primary or even exclusive role of the viral infection in hormone release and hyperthyroidism in sub-acute thyroiditis, excluding an autoimmune component.

Alternate pathways of thyroid hormone metabolism.

PubMed

Wu, Sing-Yung; Green, William L; Huang, Wen-Sheng; Hays, Marguerite T; Chopra, Inder J

2005-08-01

The major thyroid hormone (TH) secreted by the thyroid gland is thyroxine (T(4)). Triiodothyronine (T(3)), formed chiefly by deiodination of T(4), is the active hormone at the nuclear receptor, and it is generally accepted that deiodination is the major pathway regulating T(3) bioavailability in mammalian tissues. The alternate pathways, sulfation and glucuronidation of the phenolic hydroxyl group of iodothyronines, the oxidative deamination and decarboxylation of the alanine side chain to form iodothyroacetic acids, and ether link cleavage provide additional mechanisms for regulating the supply of active hormone. Sulfation may play a general role in regulation of iodothyronine metabolism, since sulfation of T(4) and T(3) markedly accelerates deiodination to the inactive metabolites, reverse triiodothyronine (rT(3)) and T(2). Sulfoconjugation is prominent during intrauterine development, particularly in the precocial species in the last trimester including humans and sheep, where it may serve both to regulate the supply of T(3), via sulfation followed by deiodination, and to facilitate maternal-fetal exchange of sulfated iodothyronines (e.g., 3,3'-diiodothyronine sulfate [T(2)S]). The resulting low serum T(3) may be important for normal fetal development in the late gestation. The possibility that T(2)S or its derivative, transferred from the fetus and appearing in maternal serum or urine, can serve as a marker of fetal thyroid function is being studied. Glucuronidation of TH often precedes biliary-fecal excretion of hormone. In rats, stimulation of glucuronidation by various drugs and toxins may lead to lower T(4) and T(3) levels, provocation of thyrotropin (TSH) secretion, and goiter. In man, drug induced stimulation of glucuronidation is limited to T(4), and does not usually compromise normal thyroid function. However, in hypothyroid subjects, higher doses of TH may be required to maintain euthyroidism when these drugs are given. In addition, glucuronidates and sulfated iodothyronines can be hydrolyzed to their precursors in gastrointestinal tract and various tissues. Thus, these conjugates can serve as a reservoir for biologically active iodothyronines (e.g., T(4), T(3), or T(2)). The acetic acid derivatives of T(4), tetrac and triac, are minor products in normal thyroid physiology. However, triac has a different pattern of receptor affinity than T(3), binding preferentially to the beta receptor. This makes it useful in the treatment of the syndrome of resistance to thyroid hormone action, where the typical mutation affects only the beta receptor. Thus, adequate binding to certain mutated beta receptors can be achieved without excessive stimulation of alpha receptors, which predominate in the heart. Ether link cleavage of TH is also a minor pathway in normal subjects. However, this pathway may become important during infections, when augmented TH breakdown by ether-link cleavage (ELC) may assist in bactericidal activity. There is a recent claim that decarboxylated derivates of thyronines, that is, monoiodothyronamine (T(1)am) and thyronamine (T(0)am), may be biologically important and have actions different from those of TH. Further information on these interesting derivatives is awaited.

Neonatal Persistent Exposure to 6-Propyl-2-thiouracil, a Thyroid-Disrupting Chemical, Differentially Modulates Expression of Hepatic Catalase and C/EBP-β in Adult Rats.

PubMed

Bunker, Suresh Kumar; Dandapat, Jagneshwar; Sahoo, Sunil Kumar; Roy, Anita; Chainy, Gagan B N

2016-02-01

Persistent exposure of rats to 6-propyl-2-thiouracil (PTU) from birth resulted in decreases in plasma thyroid hormone (TH) levels and hepatic expression of catalase and CCAAT enhancer binding protein β (C/EBP-β). Catalase promoter region (-185 to +52) that contains binding sites for C/EBP-β showed an augmentation in the methylation level along with a change in methylation pattern of CpG islands in response to PTU treatment. PTU withdrawal on 30 days of birth restored TH levels and C/EBP-β to control rats in adulthood. Although catalase expression was restored to some extent in adult rats in response to PTU withdrawal, a permanent change in its promoter CpG methylation pattern was recorded. The results suggest that downregulation of adult hepatic catalase gene in response to persistent neonatal PTU exposure may not solely be attributed to thyroid-disrupting properties of PTU. It is possible that besides thyroid-disrupting behavior, PTU may impair expression of hepatic catalase by altering methylation pattern of its promoter. © 2015 Wiley Periodicals, Inc.

Short-chain chlorinated paraffins (SCCPs) induced thyroid disruption by enhancement of hepatic thyroid hormone influx and degradation in male Sprague Dawley rats.

PubMed

Gong, Yufeng; Zhang, Haijun; Geng, Ningbo; Xing, Liguo; Fan, Jingfeng; Luo, Yun; Song, Xiaoyao; Ren, Xiaoqian; Wang, Feidi; Chen, Jiping

2018-06-01

Short-chain chlorinated paraffins (SCCPs) are known to disturb thyroid hormone (TH) homeostasis in rodents. However, the mechanism remains to be fully characterized. In this study, male Sprague Dawley rats received SCCPs (0, 1, 10, or 100mg/kg/day) via gavage once a day for consecutive 28days. Plasma and hepatic TH concentrations, thyrocyte structure, as well as thyroid and hepatic mRNA and protein levels of genes associated with TH homeostasis were examined. Moreover, we performed molecular docking to predict interactions between constitutive androstane receptor (CAR), a key regulator in xenobiotic-induced TH metabolism, with different SCCP molecules. Exposure to SCCPs significantly decreased the circulating free thyroxine (T 4 ) and triiodothyronine (T 3 ) levels, but increased thyroid-stimulating hormone (TSH) levels by a feedback mechanism. Decreased hepatic T 4 and increased hepatic T 3 levels were also seen after 100mg/kg/day SCCPs exposure. SCCPs didn't show any significant effects on the expression of thyroid TH synthesis genes or thyrocyte structure. However, stimulation effects were observed for mRNA and protein levels of hepatic uridine diphosphoglucuronosyl transferase (UGT) 1A1 and organic anion transporter 2, suggesting an accelerated TH metabolism in rat liver. The increased cytochrome P450 2B1 but not 1A1 mRNA and protein levels indicated that the CAR signaling was activated by SCCPs exposure. According to docking analysis, SCCPs form hydrophobic interactions with CAR and the binding affinity shows dependency on chlorine content. Overall, our data showed that CAR implicated enhancement of hepatic TH influx and degradation could be the main cause for SCCPs induced TH deficiency in male rats. Copyright © 2017 Elsevier B.V. All rights reserved.

Maternal exposure to UV filters: associations with maternal thyroid hormones, IGF-I/IGFBP3 and birth outcomes.

PubMed

Krause, M; Frederiksen, H; Sundberg, K; Jørgensen, F S; Jensen, L N; Nørgaard, P; Jørgensen, C; Ertberg, P; Petersen, J H; Feldt-Rasmussen, U; Juul, A; Drzewiecki, K T; Skakkebaek, N E; Andersson, A M

2018-02-01

Several chemical UV filters/absorbers ('UV filters' hereafter) have endocrine-disrupting properties in vitro and in vivo . Exposure to these chemicals, especially during prenatal development, is of concern. To examine maternal exposure to UV filters, associations with maternal thyroid hormone, with growth factor concentrations as well as to birth outcomes. Prospective study of 183 pregnant women with 2nd trimester serum and urine samples available. Maternal concentrations of the chemical UV filters benzophenone-1 (BP-1) and benzophenone-3 (BP-3) in urine and 4-hydroxy-benzophenone (4-HBP) in serum were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The relationships between 2nd trimester maternal concentrations of the three chemical UV filters and maternal serum concentrations of thyroid hormones and growth factors, as well as birth outcomes (weight, height, and head and abdominal circumferences) were examined. Positive associations between maternal serum concentrations of 4-HBP and triiodothyronine (T 3 ), thyroxine (T 4 ), insulin-like growth factor I (IGF-I) and its binding protein IGFBP3 were observed in mothers carrying male fetuses. Male infants of mothers in the middle 4-HBP exposure group had statistically significantly lower weight and shorter head and abdominal circumferences at birth compared to the low exposure group. Widespread exposure of pregnant women to chemical UV filters and the possible impact on maternal thyroid hormones and growth factors, and on fetal growth, calls for further studies on possible long-term consequences of the exposure to UV filters on fetal development and children's health. © 2018 The authors.

Nuclear Import and Export of the Thyroid Hormone Receptor.

PubMed

Zhang, Jibo; Roggero, Vincent R; Allison, Lizabeth A

2018-01-01

The thyroid hormone receptors, TRα1 and TRβ1, are members of the nuclear receptor superfamily that forms one of the most abundant classes of transcription factors in multicellular organisms. Although primarily localized to the nucleus, TRα1 and TRβ1 shuttle rapidly between the nucleus and cytoplasm. The fine balance between nuclear import and export of TRs has emerged as a critical control point for modulating thyroid hormone-responsive gene expression. Mutagenesis studies have defined two nuclear localization signal (NLS) motifs that direct nuclear import of TRα1: NLS-1 in the hinge domain and NLS-2 in the N-terminal A/B domain. Three nuclear export signal (NES) motifs reside in the ligand-binding domain. A combined approach of shRNA-mediated knockdown and coimmunoprecipitation assays revealed that nuclear entry of TRα1 is facilitated by importin 7, likely through interactions with NLS-2, and importin β1 and the adapter importin α1 interacting with both NLS-1 and NLS-2. Interestingly, TRβ1 lacks NLS-2 and nuclear import depends solely on the importin α1/β1 heterodimer. Heterokaryon and fluorescence recovery after photobleaching shuttling assays identified multiple exportins that play a role in nuclear export of TRα1, including CRM1 (exportin 1), and exportins 4, 5, and 7. Even single amino acid changes in TRs dramatically alter their intracellular distribution patterns. We conclude that mutations within NLS and NES motifs affect nuclear shuttling activity, and propose that TR mislocalization contributes to the development of some types of cancer and Resistance to Thyroid Hormone syndrome. © 2018 Elsevier Inc. All rights reserved.

The Presence of Thyroid-Stimulation Blocking Antibody Prevents High Bone Turnover in Untreated Premenopausal Patients with Graves' Disease.

PubMed

Cho, Sun Wook; Bae, Jae Hyun; Noh, Gyeong Woon; Kim, Ye An; Moon, Min Kyong; Park, Kyoung Un; Song, Junghan; Yi, Ka Hee; Park, Do Joon; Chung, June-Key; Cho, Bo Youn; Park, Young Joo

2015-01-01

Osteoporosis-related fractures are one of the complications of Graves' disease. This study hypothesized that the different actions of thyroid-stimulating hormone receptor (TSHR) antibodies, both stimulating and blocking activities in Graves' disease patients might oppositely impact bone turnover. Newly diagnosed premenopausal Graves' disease patients were enrolled (n = 93) and divided into two groups: patients with TSHR antibodies with thyroid-stimulating activity (stimulating activity group, n = 83) and patients with TSHR antibodies with thyroid-stimulating activity combined with blocking activity (blocking activity group, n = 10). From the stimulating activity group, patients who had matched values for free T4 and TSH binding inhibitor immunoglobulin (TBII) to the blocking activity group were further classified as stimulating activity-matched control (n = 11). Bone turnover markers BS-ALP, Osteocalcin, and C-telopeptide were significantly lower in the blocking activity group than in the stimulating activity or stimulating activity-matched control groups. The TBII level showed positive correlations with BS-ALP and osteocalcin levels in the stimulating activity group, while it had a negative correlation with the osteocalcin level in the blocking activity group. In conclusion, the activation of TSHR antibody-activated TSH signaling contributes to high bone turnover, independent of the actions of thyroid hormone, and thyroid-stimulation blocking antibody has protective effects against bone metabolism in Graves' disease.

Induction of painless thyroiditis in patients receiving programmed death 1 receptor immunotherapy for metastatic malignancies.

PubMed

Orlov, Steven; Salari, Farnaz; Kashat, Lawrence; Walfish, Paul G

2015-05-01

Immunotherapies against immune checkpoints that inhibit T cell activation [cytotoxic T lymphocyte antigen 4 (CTLA-4) and programmed cell death 1 (PD-1)] are emerging and promising treatments for several metastatic malignancies. However, the precise adverse effects of these therapies on thyroid gland function have not been well described. We report on 10 cases of painless thyroiditis syndrome (PTS) from a novel etiology, following immunotherapy with anti-PD-1 monoclonal antibodies (mAb) during treatment for metastatic malignancies. Six patients presented with transient thyrotoxicosis in which thyrotropin binding inhibitory immunoglobulins (TBII) were absent for all, whereas four patients had evidence of positive antithyroid antibodies. All thyrotoxic patients required temporary beta-blocker therapy and had spontaneous resolution of thyrotoxicosis with subsequent hypothyroidism. Four patients presented with hypothyroidism without a detected preceding thyrotoxic phase, occurring 6-8 weeks after initial drug exposure. All of these patients had positive antithyroid antibodies and required thyroid hormone replacement therapy for a minimum of 6 months. Patients receiving anti-PD-1 mAb therapy should be monitored for signs and symptoms of PTS which may require supportive treatment with beta-blockers or thyroid hormone replacement. The anti-PD-1 mAb is a novel exogenous cause of PTS and provides new insight into the possible perturbations of the immune network that may modulate the development of endogenous PTS, including cases of sporadic and postpartum thyroiditis.

γ-Aminobutyric acid ameliorates fluoride-induced hypothyroidism in male Kunming mice.

PubMed

Yang, Haoyue; Xing, Ronge; Liu, Song; Yu, Huahua; Li, Pengcheng

2016-02-01

This study evaluated the protective effects of γ-aminobutyric acid (GABA), a non-protein amino acid and anti-oxidant, against fluoride-induced hypothyroidism in mice. Light microscope sample preparation technique and TEM sample preparation technique were used to assay thyroid microstructure and ultrastructure; enzyme immunoassay method was used to assay hormone and protein levels; immunohistochemical staining method was used to assay apoptosis of thyroid follicular epithelium cells. Subacute injection of sodium fluoride (NaF) decreased blood T4, T3 and thyroid hormone-binding globulin (TBG) levels to 33.98 μg/l, 3 2.8 ng/ml and 11.67 ng/ml, respectively. In addition, fluoride intoxication induced structural abnormalities in thyroid follicles. Our results showed that treatment of fluoride-exposed mice with GABA appreciably decreased metabolic toxicity induced by fluoride and restored the microstructural and ultrastructural organisation of the thyroid gland towards normalcy. Compared with the negative control group, GABA treatment groups showed significantly upregulated T4, T3 and TBG levels (42.34 μg/l, 6.54 ng/ml and 18.78 ng/ml, respectively; P<0.05), properly increased TSH level and apoptosis inhibition in thyroid follicular epithelial cells. To the best of our knowledge, this is the first study to establish the therapeutic efficacy of GABA as a natural antioxidant in inducing thyroprotection against fluoride-induced toxicity. Copyright © 2015 Elsevier Inc. All rights reserved.

TSH increment and the risk of incident type 2 diabetes mellitus in euthyroid subjects.

PubMed

Jun, Ji Eun; Jin, Sang-Man; Jee, Jae Hwan; Bae, Ji Cheol; Hur, Kyu Yeon; Lee, Moon-Kyu; Kim, Sun Wook; Kim, Jae Hyeon

2017-03-01

Thyroid function is known to influence glucose metabolism, and thyroid-stimulating hormone is the most useful parameter in screening for thyroid dysfunction. Therefore, the aim of this study was to investigate the incidence of type 2 diabetes according to baseline thyroid-stimulating hormone level and thyroid-stimulating hormone change in euthyroid subjects. We identified and enrolled 17,061 euthyroid subjects without diabetes among participants who had undergone consecutive thyroid function tests between 2006 and 2012 as a part of yearly health check-up program. Thyroid-stimulating hormone changes were determined by subtracting baseline thyroid-stimulating hormone level from thyroid-stimulating hormone level at 1 year before diagnosis of diabetes or at the end of follow-up in subjects who did not develope diabetes. During 84,595 person-years of follow-up, there were 956 new cases of type 2 diabetes. Cox proportional hazards models showed the risk of incident type 2 diabetes was significantly increased with each 1 μIU/mL increment in TSH after adjustment for multiple confounding factors (hazard ratio = 1.13, 95% confidence interval: 1.07-1.20, P < 0.001). Compared with individuals in the lowest tertile (-4.08 to 0.34 μIU/mL), those in the highest thyroid-stimulating hormone change tertile (0.41-10.84 μIU/mL) were at greater risk for incident type 2 diabetes (hazard ratio = 1.25, 95% confidence interval: 1.05-1.48, P for trend = 0.011). However, baseline thyroid-stimulating hormone level and tertile were not associated with the risk for diabetes. Prominent increase in thyroid-stimulating hormone concentration can be an additional risk factor for the development of type 2 diabetes in euthyroid subjects.

Direct effects of thyroid hormones on hepatic lipid metabolism.

PubMed

Sinha, Rohit A; Singh, Brijesh K; Yen, Paul M

2018-05-01

It has been known for a long time that thyroid hormones have prominent effects on hepatic fatty acid and cholesterol synthesis and metabolism. Indeed, hypothyroidism has been associated with increased serum levels of triglycerides and cholesterol as well as non-alcoholic fatty liver disease (NAFLD). Advances in areas such as cell imaging, autophagy and metabolomics have generated a more detailed and comprehensive picture of thyroid-hormone-mediated regulation of hepatic lipid metabolism at the molecular level. In this Review, we describe and summarize the key features of direct thyroid hormone regulation of lipogenesis, fatty acid β-oxidation, cholesterol synthesis and the reverse cholesterol transport pathway in normal and altered thyroid hormone states. Thyroid hormone mediates these effects at the transcriptional and post-translational levels and via autophagy. Given these potentially beneficial effects on lipid metabolism, it is possible that thyroid hormone analogues and/or mimetics might be useful for the treatment of metabolic diseases involving the liver, such as hypercholesterolaemia and NAFLD.

Hydroxylated polybrominated diphenyl ethers exhibit different activities on thyroid hormone receptors depending on their degree of bromination.

PubMed

Ren, Xiao-Min; Guo, Liang-Hong; Gao, Yu; Zhang, Bin-Tian; Wan, Bin

2013-05-01

Polybrominated diphenyl ethers (PBDEs) have been shown to disrupt thyroid hormone (TH) functions in experimental animals, and one of the proposed disruption mechanisms is direct binding of hydroxylated PBDE (OH-PBDE) to TH receptors (TRs). However, previous data on TH receptor binding and TH activity of OH-PBDEs were very limited and sometimes inconsistent. In the present paper, we examined the binding potency of ten OH-PBDEs with different degrees of bromination to TR using a fluorescence competitive binding assay. The results showed that the ten OH-PBDEs bound to TR with potency that correlated to their bromination level. We further examined their effect on TR using a coactivator binding assay and GH3 cell proliferation assay. Different TR activities of OH-PBDEs were observed depending on their degree of bromination. Four low-brominated OH-PBDEs (2'-OH-BDE-28, 3'-OH-BDE-28, 5-OH-BDE-47, 6-OH-BDE-47) were found to be TR agonists, which recruited the coactivator peptide and enhanced GH3 cell proliferation. However, three high-brominated OH-PBDEs (3-OH-BDE-100, 3'-OH-BDE-154, 4-OH-BDE-188) were tested to be antagonists. Molecular docking was employed to simulate the interactions of OH-PBDEs with TR and identify the structural determinants for TR binding and activity. According to the docking results, low-brominated OH-PBDEs, which are weak binders but TR agonists, bind with TR at the inner side of its binding pocket, whereas high-brominated compounds, which are potent binders but TR antagonists, reside at the outer region. These results indicate that OH-PBDEs have different activities on TR (agonistic or antagonistic), possibly due to their different binding geometries with the receptor. Copyright © 2013 Elsevier Inc. All rights reserved.

Thyroid Hormone, Cancer, and Apoptosis.

PubMed

Lin, Hung-Yun; Chin, Yu-Tan; Yang, Yu-Chen S H; Lai, Husan-Yu; Wang-Peng, Jacqueline; Liu, Leory F; Tang, Heng-Yuan; Davis, Paul J

2016-06-13

Thyroid hormones play important roles in regulating normal metabolism, development, and growth. They also stimulate cancer cell proliferation. Their metabolic and developmental effects and growth effects in normal tissues are mediated primarily by nuclear hormone receptors. A cell surface receptor for the hormone on integrin [alpha]vβ3 is the initiation site for effects on tumor cells. Clinical hypothyroidism may retard cancer growth, and hyperthyroidism was recently linked to the prevalence of certain cancers. Local levels of thyroid hormones are controlled through activation and deactivation of iodothyronine deiodinases in different organs. The relative activities of different deiodinases that exist in tissues or organs also affect the progression and development of specific types of cancers. In this review, the effects of thyroid hormone on signaling pathways in breast, brain, liver, thyroid, and colon cancers are discussed. The importance of nuclear thyroid hormone receptor isoforms and of the hormone receptor on the extracellular domain of integrin [alpha]vβ3 as potential cancer risk factors and therapeutic targets are addressed. We analyze the intracellular signaling pathways activated by thyroid hormones in cancer progression in hyperthyroidism or at physiological concentrations in the euthyroid state. Determining how to utilize the deaminated thyroid hormone analog (tetrac), and its nanoparticulate derivative to reduce risks of cancer progression, enhance therapeutic outcomes, and prevent cancer recurrence is also deliberated. © 2016 American Physiological Society. Compr Physiol 6:1221-1237, 2016. Copyright © 2016 John Wiley & Sons, Inc.

PRESENCE AND BIOSYNTHESIS OF THYROID HORMONES IN A TUNICATE, CIONA INTESTINALIS (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roche, L.J.; Salvatore, G.; Rametta, G.

1962-09-10

A tunicate, Ciona intestinalis L., binds very actively I/sup 131/-ions. The labeled iodine is preferentially located (75%) in the external layer of the tunic. The iodine metabolism is there chiefly oriented toward the biosynthesis of iodothyronines (thyroid hormones). The presence of free thyroxine and 3,5,3'- triiodothyronine in the tissues of Ciona has been established. Biogenesis of 3,5,3'-triiodothyronine and thyroxine proceeds chiefly in the tunic, in which three fractions of iodoproteins were characterized. Two of these, one soluble in various media, the other bound to insoluble structure, contain 3,5,3'- triiodothyronine, thyroxine and their precursors, 3-monoiodo- and 3,5- diiodotyrosine. The four iodinatedmore » amino acids are freed from these proteins by action of pancreatic proteinases and papain. An insoluble residue of iodinated scleroprotein, not hydrolyzed by proteinases, does not take part to endocrine activity; 3-monoiodotyrosine and 3,5-diiodotyrosine only are found in the products of its alkaline hydrolysis. The mechanism of hormonogenesis seems identical in all chordata (urochordata, cephalochordata, and vertebrates). As thyroid hormones are found in these and not in invertebrates lower than urochordata, their appearance in this subphylum can be considered as a fundamental step of biochemical evolution of the thyroid function. Biosynthesis of iodothyronines is characteristic of chordata. It proceeds in all of these, including protochordata, by the same mechanism, but under conditions submitted to the evolution of the secretory tissue through a series of steps, the last of which is the thyroid follicle of vertebrates. (auth)« less

[Thyroid emergencies : Thyroid storm and myxedema coma].

PubMed

Spitzweg, C; Reincke, M; Gärtner, R

2017-10-01

Thyroid emergencies are rare life-threatening endocrine conditions resulting from either decompensated thyrotoxicosis (thyroid storm) or severe thyroid hormone deficiency (myxedema coma). Both conditions develop out of a long-standing undiagnosed or untreated hyper- or hypothyroidism, respectively, precipitated by an acute stress-associated event, such as infection, trauma, or surgery. Cardinal features of thyroid storm are myasthenia, cardiovascular symptoms, in particular tachycardia, as well as hyperthermia and central nervous system dysfunction. The diagnosis is made based on clinical criteria only as thyroid hormone measurements do not differentiate between thyroid storm and uncomplicated hyperthyroidism. In addition to critical care measures therapy focusses on inhibition of thyroid hormone synthesis and secretion (antithyroid drugs, perchlorate, Lugol's solution, cholestyramine, thyroidectomy) as well as inhibition of thyroid hormone effects in the periphery (β-blocker, glucocorticoids).Cardinal symptoms of myxedema coma are hypothermia, decreased mental status, and hypoventilation with risk of pneumonia and hyponatremia. The diagnosis is also purely based on clinical criteria as measurements of thyroid hormone levels do not differ between uncomplicated severe hypothyroidism and myxedema coma. In addition to substitution of thyroid hormones and glucocorticoids, therapy focusses on critical care measures to treat hypoventilation and hypercapnia, correction of hyponatremia and hypothermia.Survival of both thyroid emergencies can only be optimized by early diagnosis based on clinical criteria and prompt initiation of multimodal therapy including supportive measures and treatment of the precipitating event.

Peripheral thyroid hormone levels and hepatic thyroid hormone deiodinase gene expression in dairy heifers on the day of ovulation and during the early peri-implantation period.

PubMed

Meyerholz, Marie Margarete; Mense, Kirsten; Linden, Matthias; Raliou, Mariam; Sandra, Olivier; Schuberth, Hans-Joachim; Hoedemaker, Martina; Schmicke, Marion

2016-09-08

Before the onset of fetal thyroid hormone production, the transplacental delivery of maternal thyroid hormones is necessary for embryonic and fetal development. Therefore, the adaptation of maternal thyroid hormone metabolism may be important for pregnancy success and embryo survival. The aims of this study were to determine the thyroid hormone levels during the early peri-implantation period until day 18 and on the day of ovulation, to determine whether pregnancy success is dependent on a "normothyroid status" and to determine whether physiological adaptations in maternal thyroid hormone metabolism occur, which may be necessary to provide sufficient amounts of biologically active T3 to support early pregnancy. Therefore, blood samples obtained on the day of ovulation (day 0) and days 14 and 18 of the Holstein-Friesian heifers (n = 10) during the respective pregnant, non-pregnant and negative control cycles were analyzed for thyroid-stimulating-hormone (TSH), thyroxine (T4) and triiodothyronine (T3). Liver biopsies (day 18) from pregnant and respective non-pregnant heifers were analyzed for mRNA expression of the most abundant hepatic thyroid hormone deiodinase (DIO1) by real time qPCR. Although liver DIO1 mRNA expression did not differ between the pregnant and non-pregnant heifers on day 18, the serum concentrations of TSH and T3 on day 18 were higher in non-pregnant heifers compared to pregnant heifers (P < 0.05). Moreover, T3 decreased between day 0 and 18 in pregnant heifers (P < 0.001). In conclusion, no associations between thyroid hormone patterns on day 18 and pregnancy success were detected. During the early peri-implantation period, TSH and T3 may be affected by the pregnancy status because both TSH and T3 were lower on day 18 in pregnant heifers compared to non-pregnant dairy heifers. In further studies, the thyroid hormone axis should be evaluated throughout the entire gestation to confirm these data and identify other possible effects of pregnancy on the thyroid hormone axis in cattle.

Dronerarone acts as a selective inhibitor of 3,5,3'-triiodothyronine binding to thyroid hormone receptor-alpha1: in vitro and in vivo evidence.

PubMed

Van Beeren, H C; Jong, W M C; Kaptein, E; Visser, T J; Bakker, O; Wiersinga, W M

2003-02-01

Dronedarone (Dron), without iodine, was developed as an alternative to the iodine-containing antiarrhythmic drug amiodarone (AM). AM acts, via its major metabolite desethylamiodarone, in vitro and in vivo as a thyroid hormone receptor alpha(1) (TRalpha(1)) and TRbeta(1) antagonist. Here we investigate whether Dron and/or its metabolite debutyldronedarone inhibit T(3) binding to TRalpha(1) and TRbeta(1) in vitro and whether dronedarone behaves similarly to amiodarone in vivo. In vitro, Dron had a inhibitory effect of 14% on the binding of T(3) to TRalpha(1), but not on TRbeta(1). Desethylamiodarone inhibited T(3) binding to TRalpha(1) and TRbeta(1) equally. Debutyldronedarone inhibited T(3) binding to TRalpha(1) by 77%, but to TRbeta(1) by only 25%. In vivo, AM increased plasma TSH and rT(3), and decreased T(3). Dron decreased T(4) and T(3), rT(3) did not change, and TSH fell slightly. Plasma total cholesterol was increased by AM, but remained unchanged in Dron-treated animals. TRbeta(1)-dependent liver low density lipoprotein receptor protein and type 1 deiodinase activities decreased in AM-treated, but not in Dron-treated, animals. TRalpha(1)-mediated lengthening of the QTc interval was present in both AM- and Dron-treated animals. The in vitro and in vivo findings suggest that dronedarone via its metabolite debutyldronedarone acts as a TRalpha(1)-selective inhibitor.

Thyroid Hormones Are Transport Substrates and Transcriptional Regulators of Organic Anion Transporting Polypeptide 2B1.

PubMed

Meyer Zu Schwabedissen, Henriette E; Ferreira, Celio; Schaefer, Anima M; Oufir, Mouhssin; Seibert, Isabell; Hamburger, Matthias; Tirona, Rommel G

2018-07-01

Levothyroxine replacement therapy forms the cornerstone of hypothyroidism management. Variability in levothyroxine oral absorption may contribute to the well-recognized large interpatient differences in required dose. Moreover, levothyroxine-drug pharmacokinetic interactions are thought to be caused by altered oral bioavailability. Interestingly, little is known regarding the mechanisms contributing to levothyroxine absorption in the gastrointestinal tract. Here, we aimed to determine whether the intestinal drug uptake transporter organic anion transporting polypeptide 2B1 (OATP2B1) may be involved in facilitating intestinal absorption of thyroid hormones. We also explored whether thyroid hormones regulate OATP2B1 gene expression. In cultured Madin-Darby Canine Kidney II/OATP2B1 cells and in OATP2B1-transfected Caco-2 cells, thyroid hormones were found to inhibit OATP2B1-mediated uptake of estrone-3-sulfate. Competitive counter-flow experiments evaluating the influence on the cellular accumulation of estrone-3-sulfate in the steady state indicated that thyroid hormones were substrates of OATP2B1. Additional evidence that thyroid hormones were OATP2B1 substrates was provided by OATP2B1-dependent stimulation of thyroid hormone receptor activation in cell-based reporter assays. Bidirectional transport studies in intestinal Caco-2 cells showed net absorptive flux of thyroid hormones, which was attenuated by the presence of the OATP2B1 inhibitor, atorvastatin. In intestinal Caco-2 and LS180 cells, but not in liver Huh-7 or HepG2 cells, OATP2B1 expression was induced by treatment with thyroid hormones. Reporter gene assays revealed thyroid hormone receptor α -mediated transactivation of the SLCO2B1 1b and the SLCO2B1 1e promoters. We conclude that thyroid hormones are substrates and transcriptional regulators of OATP2B1. These insights provide a potential mechanistic basis for oral levothyroxine dose variability and drug interactions. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

75 FR 66104 - Government-Owned Inventions; Availability for Licensing

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-27

... receptor gene exhibit impaired growth and resistance to thyroid hormone. Proc Natl Acad Sci U S A. 2000 Nov... overactivated. These mice have a knock-in dominantly negative mutant thyroid hormone receptor [beta] gene (TR... mutation in the thyroid hormone receptor beta gene spontaneously develop thyroid carcinoma: a mouse model...

Neurotoxicity of Thyroid Disrupting Contaminants

EPA Science Inventory

Thyroid hormones playa critical role in the normal development ofthe mammalian brain. Thyroid disrupting chemicals (TDCs) are environmental contaminants that alter the structure or function ofthe thyroid gland, alter regulatory enzymes associated with thyroid hormone (TH) homeost...

Phenols and Parabens in relation to Reproductive and Thyroid Hormones in Pregnant Women

PubMed Central

Aker, Amira M; Watkins, Deborah J; Johns, Lauren E; Ferguson, Kelly K; Soldin, Offie P; Del Toro, Liza V Anzalota; Alshawabkeh, Akram N; Cordero, José F; Meeker, John D

2016-01-01

Introduction Phenols and parabens are ubiquitous environmental contaminants. Evidence from animal studies and limited human data suggest they may be endocrine disruptors. In the current study, we examined associations of phenols and parabens with reproductive and thyroid hormones in 106 pregnant women recruited for the prospective cohort, “Puerto Rico Testsite for Exploring Contamination Threats (PROTECT)”. Methods Urinary exposure biomarkers (bisphenol A, triclosan, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol, butyl, methyl and propyl paraben) and serum hormone levels (estradiol, progesterone, sex hormone-binding globulin (SHBG), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone) were measured at up to two time points during pregnancy (16–20 weeks and 24–28 weeks). We used linear mixed models to assess relationships between exposure biomarkers and hormone levels across pregnancy, controlling for urinary specific gravity, maternal age, BMI and education. In sensitivity analyses, we evaluated cross-sectional relationships between exposure and hormone levels stratified by study visit using linear regression. Results An IQR increase in methyl paraben was associated with a 7.70% increase (95% CI 1.50, 13.90) in SHBG. Furthermore, an IQR increase in butyl paraben as associated with an 8.46% decrease (95% CI 16.92, 0.00) in estradiol, as well as a 9.34% decrease (95% CI −18.31, −0.38) in estradiol/progesterone. Conversely, an IQR increase in butyl paraben was associated with a 5.64% increase (95% CI 1.26, 10.02) in FT4. Progesterone was consistently negatively associated with phenols, but none reached statistical significance. After stratification, methyl and propyl paraben were suggestively negatively associated with estradiol at the first time point (16–20 weeks), and suggestively positively associated with estradiol at the second time point (24–28 weeks). Conclusions Within this ongoing birth cohort, certain phenols and parabens were associated with altered reproductive and thyroid hormone levels during pregnancy. These changes may contribute to adverse health effects in mothers or their offspring, but additional research is required. PMID:27448730

Phenols and parabens in relation to reproductive and thyroid hormones in pregnant women.

PubMed

Aker, Amira M; Watkins, Deborah J; Johns, Lauren E; Ferguson, Kelly K; Soldin, Offie P; Anzalota Del Toro, Liza V; Alshawabkeh, Akram N; Cordero, José F; Meeker, John D

2016-11-01

Phenols and parabens are ubiquitous environmental contaminants. Evidence from animal studies and limited human data suggest they may be endocrine disruptors. In the current study, we examined associations of phenols and parabens with reproductive and thyroid hormones in 106 pregnant women recruited for the prospective cohort, "Puerto Rico Testsite for Exploring Contamination Threats (PROTECT)". Urinary exposure biomarkers (bisphenol A, triclosan, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol, butyl, methyl and propyl paraben) and serum hormone levels (estradiol, progesterone, sex hormone-binding globulin (SHBG), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone) were measured at up to two time points during pregnancy (16-20 weeks and 24-28 weeks). We used linear mixed models to assess relationships between exposure biomarkers and hormone levels across pregnancy, controlling for urinary specific gravity, maternal age, BMI and education. In sensitivity analyses, we evaluated cross-sectional relationships between exposure and hormone levels stratified by study visit using linear regression. An IQR increase in methyl paraben was associated with a 7.70% increase (95% CI 1.50, 13.90) in SHBG. Furthermore, an IQR increase in butyl paraben as associated with an 8.46% decrease (95% CI 16.92, 0.00) in estradiol, as well as a 9.34% decrease (95% CI -18.31,-0.38) in estradiol/progesterone. Conversely, an IQR increase in butyl paraben was associated with a 5.64% increase (95% CI 1.26, 10.02) in FT4. Progesterone was consistently negatively associated with phenols, but none reached statistical significance. After stratification, methyl and propyl paraben were suggestively negatively associated with estradiol at the first time point (16-20 weeks), and suggestively positively associated with estradiol at the second time point (24-28 weeks). Within this ongoing birth cohort, certain phenols and parabens were associated with altered reproductive and thyroid hormone levels during pregnancy. These changes may contribute to adverse health effects in mothers or their offspring, but additional research is required. Copyright © 2016 Elsevier Inc. All rights reserved.

Thyroid hormone and obesity.

PubMed

Pearce, Elizabeth N

2012-10-01

To review several of the most recent and most important clinical studies regarding the effects of thyroid treatments on weight change, associations between thyroid status and weight, and the effects of obesity and weight change on thyroid function. Weight decreases following treatment for hypothyroidism. However, following levothyroxine treatment for overt hypothyroidism, weight loss appears to be modest and mediated primarily by loss of water weight rather than fat. There is conflicting evidence about the effects of thyroidectomy on weight. In large population studies, even among euthyroid individuals, serum thyroid-stimulating hormone is typically positively associated with body weight and BMI. Both serum thyroid-stimulating hormone and T3 are typically increased in obese compared with lean individuals, an effect likely mediated, at least in part, by leptin. Finally, there is no consistent evidence that thyroid hormone treatment induces weight loss in obese euthyroid individuals, but thyroid hormone analogues may eventually be useful for weight loss. The interrelationships between body weight and thyroid status are complex.

The emergence of levothyroxine as a treatment for hypothyroidism.

PubMed

Hennessey, James V

2017-01-01

To describe the historical refinements, understanding of physiology and clinical outcomes observed with thyroid hormone replacement strategies. A Medline search was initiated using the search terms, levothyroxine, thyroid hormone history, levothyroxine mono therapy, thyroid hormone replacement, combination LT4 therapy, levothyroxine Bioequivalence. Pertinent articles of interest were identified by title and where available abstract for further review. Additional references were identified in the course of review of the literature identified. Physicians have intervened in cases of thyroid dysfunction for more than two millennia. Ingestion of animal thyroid derived preparations has been long described but only scientifically documented for the last 130 years. Refinements in hormone preparation, pharmaceutical production and regulation continue to this day. The literature provides documentation of physiologic, pathologic and clinical outcomes which have been reported and continuously updated. Recommendations for effective and safe use of these hormones for reversal of patho-physiology associated with hypothyroidism and the relief of symptoms of hypothyroidism has documented a progressive refinement in our understanding of thyroid hormone use. Studies of thyroid hormone metabolism, action and pharmacokinetics have allowed evermore focused recommendations for use in clinical practice. Levothyroxine mono-therapy has emerged as the therapy of choice of all recent major guidelines. The evolution of thyroid hormone therapies has been significant over an extended period of time. Thyroid hormone replacement is very useful in the treatment of those with hypothyroidism. All of the most recent guidelines of major endocrine societies recommend levothyroxine mono-therapy for first line use in hypothyroidism.

Thyroid profiles in a patient with resistance to thyroid hormone and episodes of thyrotoxicosis, including repeated painless thyroiditis.

PubMed

Taniyama, Matsuo; Otsuka, Fumiko; Tozaki, Teruaki; Ban, Yoshiyuki

2013-07-01

Thyrotoxic disease can be difficult to recognize in patients with resistance to thyroid hormone (RTH) because the clinical symptoms of thyrotoxicosis cannot be observed, and thyrotropin (TSH) may not be suppressed because of hormone resistance. Painless thyroiditis is a relatively common cause of thyrotoxicosis, but its occurrence in RTH has not been reported. We assessed the thyroid profile in a patient with RTH and episodes of thyrotoxicosis who experienced repeated painless thyroiditis. A 44-year-old Japanese woman with RTH, which was confirmed by the presence of a P453A mutation in the thyroid hormone receptor β (TRβ) gene, showed a slight elevation of the basal levels of thyroid hormones, which indicated that her pituitary RTH was mild. She experienced a slight exacerbation of hyperthyroxinemia concomitant with TSH suppression. A diagnosis of painless thyroiditis was made because of the absence of TSH receptor antibodies, low Tc-99m pertechnetate uptake by the thyroid gland, and transient suppression followed by a slight elevation of TSH following the elevation of thyroid hormones. The patient's complaints of general malaise and occasional palpitations did not change throughout the course of painless thyroiditis. Three years later, painless thyroiditis occurred again without any deterioration of the clinical manifestations. Mild pituitary RTH can be overcome by slight exacerbation of hyperthyroxinemia during mild thyrotoxicosis. When pituitary resistance is severe and TSH is not suppressed, thyrotoxicosis may be overlooked.

American Thyroid Association Guide to Investigating Thyroid Hormone Economy and Action in Rodent and Cell Models

PubMed Central

Anderson, Grant; Forrest, Douglas; Galton, Valerie Anne; Gereben, Balázs; Kim, Brian W.; Kopp, Peter A.; Liao, Xiao Hui; Obregon, Maria Jesus; Peeters, Robin P.; Refetoff, Samuel; Sharlin, David S.; Simonides, Warner S.; Weiss, Roy E.; Williams, Graham R.

2014-01-01

Background: An in-depth understanding of the fundamental principles that regulate thyroid hormone homeostasis is critical for the development of new diagnostic and treatment approaches for patients with thyroid disease. Summary: Important clinical practices in use today for the treatment of patients with hypothyroidism, hyperthyroidism, or thyroid cancer are the result of laboratory discoveries made by scientists investigating the most basic aspects of thyroid structure and molecular biology. In this document, a panel of experts commissioned by the American Thyroid Association makes a series of recommendations related to the study of thyroid hormone economy and action. These recommendations are intended to promote standardization of study design, which should in turn increase the comparability and reproducibility of experimental findings. Conclusions: It is expected that adherence to these recommendations by investigators in the field will facilitate progress towards a better understanding of the thyroid gland and thyroid hormone dependent processes. PMID:24001133

Sex Differences in Brain Thyroid Hormone Levels during Early Post-Hatching Development in Zebra Finch (Taeniopygia guttata).

PubMed

Yamaguchi, Shinji; Hayase, Shin; Aoki, Naoya; Takehara, Akihiko; Ishigohoka, Jun; Matsushima, Toshiya; Wada, Kazuhiro; Homma, Koichi J

2017-01-01

Thyroid hormones are closely linked to the hatching process in precocial birds. Previously, we showed that thyroid hormones in brain had a strong impact on filial imprinting, an early learning behavior in newly hatched chicks; brain 3,5,3'-triiodothyronine (T3) peaks around hatching and imprinting training induces additional T3 release, thus, extending the sensitive period for imprinting and enabling subsequent other learning. On the other hand, blood thyroid hormone levels have been reported to increase gradually after hatching in altricial species, but it remains unknown how the brain thyroid hormone levels change during post-hatching development of altricial birds. Here, we determined the changes in serum and brain thyroid hormone levels of a passerine songbird species, the zebra finch using radioimmunoassay. In the serum, we found a gradual increase in thyroid hormone levels during post-hatching development, as well as differences between male and female finches. In the brain, there was clear surge in the hormone levels during development in males and females coinciding with the time of fledging, but the onset of the surge of thyroxine (T4) in males preceded that of females, whereas the onset of the surge of T3 in males succeeded that of females. These findings provide a basis for understanding the functions of thyroid hormones during early development and learning in altricial birds.

Liothyronine

MedlinePlus

... the thyroid gland does not produce enough thyroid hormone). Liothyronine is also used to treat a goiter ( ... where the thyroid gland produces too much thyroid hormone). Liothyronine is in a class of medications called ...

Induction of metamorphosis in the sand dollar Peronella japonica by thyroid hormones.

PubMed

Saito, M; Seki, M; Amemiya, S; Yamasu, K; Suyemitsu, T; Ishihara, K

1998-06-01

The larva of the sand dollar Peronella japonica lacks a mouth and gut, and undergoes metamorphosis into a juvenile sand dollar without feeding. In the present study, it was found that thyroid hormones accelerate the metamorphosis of P. japonica larvae. The contents of thyroid hormones in larvae increased gradually during development. Thiourea and potassium perchlorate, inhibitors of thyroid hormone synthesis, delayed larval metamorphosis and simultaneously repressed an increase in the content of thyroxine in the larval body. These results suggest that the P. japonica larva has a system for synthesis of thyroid hormones that act as factors for inducing metamorphosis.

Relationship between thyroid functions and urinary growth hormone secretion in patients with hyper- and hypothyroidism.

PubMed

Murao, K; Takahara, J; Sato, M; Tamaki, M; Niimi, M; Ishida, T

1994-10-01

Thyroid hormone plays an important role in growth hormone (GH) synthesis and secretion. To study the relationship between thyroid function and urinary GH secretion in the hyperthyroid and hypothyroid states, we measured thyroid hormones, simultaneously with serum and urinary GH levels, in 54 patients with thyroid diseases. GH-releasing hormone (GRH) test was performed in 18 patients in order to evaluate serum and urinary GH responses to GRH in hyper- and hypothyroid states. Serum thyroid hormone levels were strongly correlated with the urinary GH levels in the patients, and the correlation was greater than that between serum thyroid hormone and serum GH levels. Urinary GH levels were significantly higher in the hyperthyroid patients than in the euthyroid and hypothyroid patients, although serum GH levels were not significantly different among these three groups. Serum GH response to GRH was significantly decreased in hyperthyroid patients as compared to euthyroid patients. However, urinary GH levels after GRH administration were not decreased in the hyperthyroid patients. These results suggest that hyperthyroid states increase GH in urine and may accelerate the urinary clearance of GH.

MODEST THYROID HORMONE INSUFFICIENCY DURING DEVELOPMENT INDUCES A CELLULAR MALFORMATION IN THE CORPUS CALLOSUM: A MODEL OF CORTICAL DYSPLASIA.

EPA Science Inventory

There is a growing body of evidence that subtle decreases in maternal thyroid hormone during gestation can impact fetal brain development. The present study examined the impact of graded levels of thyroid hormone insufficiency on brain development in rodents. Maternal thyroid ho...

Stimulation of thyroid hormone secretion by thyrotropin in beluga whales, Delphinapterus leucas.

PubMed Central

St Aubin, D J

1987-01-01

Bovine thyroid stimulating hormone administered to three beluga whales, Delphinapterus leucas, was effective in producing an increase in circulating levels of triiodothyronine and thyroxine. A single dose of 10 I.U. of thyroid stimulating hormone resulted in a 145% increase in triiodothyronine and a 35% increase in thyroxine after nine hours in a whale tested within two hours after capture. The response was less pronounced in an animal tested with the same does on two occasions after four and eight weeks in captivity. In the third whale, 10 I.U. of thyroid stimulating hormone given on each of three consecutive days produced a marked increase in triiodothyronine and thyroxine. The elevation of thyroxine concentration persisted for at least two days after the last injection of thyroid stimulating hormone. A subsequent decrease in thyroxine to levels below baseline signalled the suppression of endogenous thyroid stimulating hormone. This preliminary study helps to establish a protocol for testing thyroid function in cetaceans. PMID:3651900

The interrelationships of thyroid and growth hormones: effect of growth hormone releasing hormone in hypo- and hyperthyroid male rats.

PubMed

Root, A W; Shulman, D; Root, J; Diamond, F

1986-01-01

Growth hormone (GH) and the thyroid hormones interact in the hypothalamus, pituitary and peripheral tissues. Thyroid hormone exerts a permissive effect upon the anabolic and metabolic effects of GH, and increases pituitary synthesis of this protein hormone. GH depresses the secretion of thyrotropin and the thyroid hormones and increases the peripheral conversion of thyroxine to triiodothyronine. In the adult male rat experimental hypothyroidism produced by ingestion of propylthiouracil depresses the GH secretory response to GH-releasing hormone in vivo and in vitro, reflecting the lowered pituitary stores of GH in the hypothyroid state. Short term administration of large amounts of thyroxine with induction of the hyperthyroid state does not affect the in vivo GH secretory response to GH-releasing hormone in this animal.

Cerebral Cortex Hyperthyroidism of Newborn Mct8-Deficient Mice Transiently Suppressed by Lat2 Inactivation

PubMed Central

Núñez, Bárbara; Martínez de Mena, Raquel; Obregon, Maria Jesus; Font-Llitjós, Mariona; Nunes, Virginia; Palacín, Manuel; Dumitrescu, Alexandra M.; Morte, Beatriz; Bernal, Juan

2014-01-01

Thyroid hormone entry into cells is facilitated by transmembrane transporters. Mutations of the specific thyroid hormone transporter, MCT8 (Monocarboxylate Transporter 8, SLC16A2) cause an X-linked syndrome of profound neurological impairment and altered thyroid function known as the Allan-Herndon-Dudley syndrome. MCT8 deficiency presumably results in failure of thyroid hormone to reach the neural target cells in adequate amounts to sustain normal brain development. However during the perinatal period the absence of Mct8 in mice induces a state of cerebral cortex hyperthyroidism, indicating increased brain access and/or retention of thyroid hormone. The contribution of other transporters to thyroid hormone metabolism and action, especially in the context of MCT8 deficiency is not clear. We have analyzed the role of the heterodimeric aminoacid transporter Lat2 (Slc7a8), in the presence or absence of Mct8, on thyroid hormone concentrations and on expression of thyroid hormone-dependent cerebral cortex genes. To this end we generated Lat2-/-, and Mct8-/yLat2 -/- mice, to compare with wild type and Mct8-/y mice during postnatal development. As described previously the single Mct8 KO neonates had a transient increase of 3,5,3′-triiodothyronine concentration and expression of thyroid hormone target genes in the cerebral cortex. Strikingly the absence of Lat2 in the double Mct8Lat2 KO prevented the effect of Mct8 inactivation in newborns. The Lat2 effect was not observed from postnatal day 5 onwards. On postnatal day 21 the Mct8 KO displayed the typical pattern of thyroid hormone concentrations in plasma, decreased cortex 3,5,3′-triiodothyronine concentration and Hr expression, and concomitant Lat2 inactivation produced little to no modifications. As Lat2 is expressed in neurons and in the choroid plexus, the results support a role for Lat2 in the supply of thyroid hormone to the cerebral cortex during early postnatal development. PMID:24819605

Cerebral cortex hyperthyroidism of newborn mct8-deficient mice transiently suppressed by lat2 inactivation.

PubMed

Núñez, Bárbara; Martínez de Mena, Raquel; Obregon, Maria Jesus; Font-Llitjós, Mariona; Nunes, Virginia; Palacín, Manuel; Dumitrescu, Alexandra M; Morte, Beatriz; Bernal, Juan

2014-01-01

Thyroid hormone entry into cells is facilitated by transmembrane transporters. Mutations of the specific thyroid hormone transporter, MCT8 (Monocarboxylate Transporter 8, SLC16A2) cause an X-linked syndrome of profound neurological impairment and altered thyroid function known as the Allan-Herndon-Dudley syndrome. MCT8 deficiency presumably results in failure of thyroid hormone to reach the neural target cells in adequate amounts to sustain normal brain development. However during the perinatal period the absence of Mct8 in mice induces a state of cerebral cortex hyperthyroidism, indicating increased brain access and/or retention of thyroid hormone. The contribution of other transporters to thyroid hormone metabolism and action, especially in the context of MCT8 deficiency is not clear. We have analyzed the role of the heterodimeric aminoacid transporter Lat2 (Slc7a8), in the presence or absence of Mct8, on thyroid hormone concentrations and on expression of thyroid hormone-dependent cerebral cortex genes. To this end we generated Lat2-/-, and Mct8-/yLat2-/- mice, to compare with wild type and Mct8-/y mice during postnatal development. As described previously the single Mct8 KO neonates had a transient increase of 3,5,3'-triiodothyronine concentration and expression of thyroid hormone target genes in the cerebral cortex. Strikingly the absence of Lat2 in the double Mct8Lat2 KO prevented the effect of Mct8 inactivation in newborns. The Lat2 effect was not observed from postnatal day 5 onwards. On postnatal day 21 the Mct8 KO displayed the typical pattern of thyroid hormone concentrations in plasma, decreased cortex 3,5,3'-triiodothyronine concentration and Hr expression, and concomitant Lat2 inactivation produced little to no modifications. As Lat2 is expressed in neurons and in the choroid plexus, the results support a role for Lat2 in the supply of thyroid hormone to the cerebral cortex during early postnatal development.

Thyroid Hormones and Moderate Exposure to Perchlorate during Pregnancy in Women in Southern California.

PubMed

Steinmaus, Craig; Pearl, Michelle; Kharrazi, Martin; Blount, Benjamin C; Miller, Mark D; Pearce, Elizabeth N; Valentin-Blasini, Liza; DeLorenze, Gerald; Hoofnagle, Andrew N; Liaw, Jane

2016-06-01

Findings from national surveys suggest that everyone in the United States is exposed to perchlorate. At high doses, perchlorate, thiocyanate, and nitrate inhibit iodide uptake into the thyroid and decrease thyroid hormone production. Small changes in thyroid hormones during pregnancy, including changes within normal reference ranges, have been linked to cognitive function declines in the offspring. We evaluated the potential effects of low environmental exposures to perchlorate on thyroid function. Serum thyroid hormones and anti-thyroid antibodies and urinary perchlorate, thiocyanate, nitrate, and iodide concentrations were measured in 1,880 pregnant women from San Diego County, California, during 2000-2003, a period when much of the area's water supply was contaminated from an industrial plant with perchlorate at levels near the 2007 California regulatory standard of 6 μg/L. Linear regression was used to evaluate associations between urinary perchlorate and serum thyroid hormone concentrations in models adjusted for urinary creatinine and thiocyanate, maternal age and education, ethnicity, and gestational age at serum collection. The median urinary perchlorate concentration was 6.5 μg/L, about two times higher than in the general U.S. Adjusted associations were identified between increasing log10 perchlorate and decreasing total thyroxine (T4) [regression coefficient (β) = -0.70; 95% CI: -1.06, -0.34], decreasing free thyroxine (fT4) (β = -0.053; 95% CI: -0.092, -0.013), and increasing log10 thyroid-stimulating hormone (β = 0.071; 95% CI: 0.008, 0.133). These results suggest that environmental perchlorate exposures may affect thyroid hormone production during pregnancy. This could have implications for public health given widespread perchlorate exposure and the importance of thyroid hormone in fetal neurodevelopment. Steinmaus C, Pearl M, Kharrazi M, Blount BC, Miller MD, Pearce EN, Valentin-Blasini L, DeLorenze G, Hoofnagle AN, Liaw J. 2016. Thyroid hormones and moderate exposure to perchlorate during pregnancy in women in Southern California. Environ Health Perspect 124:861-867; http://dx.doi.org/10.1289/ehp.1409614.

Editor's Highlight: Structure-Based Investigation on the Binding and Activation of Typical Pesticides With Thyroid Receptor.

PubMed

Xiang, Dandan; Han, Jian; Yao, Tingting; Wang, Qiangwei; Zhou, Bingsheng; Mohamed, Abou Donia; Zhu, Guonian

2017-12-01

A broad range of pesticides have been reported to interfere with the normal function of the thyroid endocrine system. However, the precise mechanism(s) of action has not yet been thoroughly elucidated. In this study, 21 pesticides were assessed for their binding interactions and the potential to disrupt thyroid homeostasis. In the GH3 luciferase reporter gene assays, 5 of the pesticides tested had agonistic effects in the order of procymidone > imidacloprid > mancozeb > fluroxypyr > atrazine. 11 pesticides inhibited luciferase activity of T3 to varying degrees, demonstrating their antagonistic activity. And there are 4 pesticides showed mixed effects when treated with different concentrations. Surface plasmon resonance (SPR) biosensor technique was used to directly measure the binding interactions of these pesticides to the human thyroid hormone receptor (hTR). 13 pesticides were observed to bind directly with TR, with a KD ranging from 4.80E-08 M to 9.44E-07 M. The association and disassociation of the hTR/pesticide complex revealed 2 distinctive binding modes between the agonists and antagonists. At the same time, a different binding mode was displayed by the pesticides showed mix agonist and antagonist activity. In addition, the molecular docking simulation analyses indicated that the interaction energy calculated by CDOCKER for the agonists and antagonists correlated well with the KD values measured by the surface plasmon resonance assay. These results help to explain the differences of the TR activities of these tested pesticides. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Thyroid hormones: Possible roles in epilepsy pathology.

PubMed

Tamijani, Seyedeh Masoumeh Seyedhoseini; Karimi, Benyamin; Amini, Elham; Golpich, Mojtaba; Dargahi, Leila; Ali, Raymond Azman; Ibrahim, Norlinah Mohamed; Mohamed, Zahurin; Ghasemi, Rasoul; Ahmadiani, Abolhassan

2015-09-01

Thyroid hormones (THs) L-thyroxine and L-triiodothyronine, primarily known as metabolism regulators, are tyrosine-derived hormones produced by the thyroid gland. They play an essential role in normal central nervous system development and physiological function. By binding to nuclear receptors and modulating gene expression, THs influence neuronal migration, differentiation, myelination, synaptogenesis and neurogenesis in developing and adult brains. Any uncorrected THs supply deficiency in early life may result in irreversible neurological and motor deficits. The development and function of GABAergic neurons as well as glutamatergic transmission are also affected by THs. Though the underlying molecular mechanisms still remain unknown, the effects of THs on inhibitory and excitatory neurons may affect brain seizure activity. The enduring predisposition of the brain to generate epileptic seizures leads to a complex chronic brain disorder known as epilepsy. Pathologically, epilepsy may be accompanied by mitochondrial dysfunction, oxidative stress and eventually dysregulation of excitatory glutamatergic and inhibitory GABAergic neurotransmission. Based on the latest evidence on the association between THs and epilepsy, we hypothesize that THs abnormalities may contribute to the pathogenesis of epilepsy. We also review gender differences and the presumed underlying mechanisms through which TH abnormalities may affect epilepsy here. Copyright © 2015 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Thyroid hormones and coronary artery calcification in euthyroid men and women.

PubMed

Zhang, Yiyi; Kim, Bo-Kyoung; Chang, Yoosoo; Ryu, Seungho; Cho, Juhee; Lee, Won-Young; Rhee, Eun-Jung; Kwon, Min-Jung; Rampal, Sanjay; Zhao, Di; Pastor-Barriuso, Roberto; Lima, Joao A; Shin, Hocheol; Guallar, Eliseo

2014-09-01

Overt and subclinical hypothyroidism are risk factors for atherosclerosis. It is unclear whether thyroid hormone levels within the normal range are also associated with atherosclerosis measured by coronary artery calcium (CAC). We conducted a cross-sectional study of 41 403 apparently healthy young and middle-aged men and women with normal thyroid hormone levels. Free thyroxin, free triiodothyronine, and thyroid-stimulating hormone levels were measured by electrochemiluminescent immunoassay. CAC score was measured by multidetector computed tomography. The multivariable adjusted CAC ratios comparing the highest versus the lowest quartile of thyroid hormones were 0.74 (95% confidence interval, 0.60-0.91; P for trend <0.001) for free thyroxin, 0.81 (0.66-1.00; P for trend=0.05) for free triiodothyronine, and 0.78 (0.64-0.95; P for trend=0.01) for thyroid-stimulating hormone. Similarly, the odds ratios for detectable CAC (CAC >0) comparing the highest versus the lowest quartiles of thyroid hormones were 0.87 (0.79-0.96; P for linear trend <0.001) for free thyroxin, 0.90 (0.82-0.99; P for linear trend=0.02) for free triiodothyronine, and 0.91 (0.83-1.00; P for linear trend=0.03) for thyroid-stimulating hormone. In a large cohort of apparently healthy young and middle-aged euthyroid men and women, low-normal free thyroxin and thyroid-stimulating hormone were associated with a higher prevalence of subclinical coronary artery disease and with a greater degree of coronary calcification. © 2014 American Heart Association, Inc.

Effects of Sample Handling and Analytical Procedures on Thyroid Hormone Concentrations in Pregnant Women's Plasma.

PubMed

Villanger, Gro Dehli; Learner, Emily; Longnecker, Matthew P; Ask, Helga; Aase, Heidi; Zoeller, R Thomas; Knudsen, Gun P; Reichborn-Kjennerud, Ted; Zeiner, Pål; Engel, Stephanie M

2017-05-01

Maternal thyroid function is a critical mediator of fetal brain development. Pregnancy-related physiologic changes and handling conditions of blood samples may influence thyroid hormone biomarkers. We investigated the reliability of thyroid hormone biomarkers in plasma of pregnant women under various handling conditions. We enrolled 17 pregnant women; collected serum and plasma were immediately frozen. Additional plasma aliquots were subjected to different handling conditions before the analysis of thyroid biomarkers: storage at room temperature for 24 or 48 hours before freezing and an extra freeze-thaw cycle. We estimated free thyroid hormone indices in plasma based on T3 uptake. High correlations between plasma and serum (>0.94) and intraclass correlation coefficients for plasma handling conditions (0.96 to 1.00) indicated excellent reliability for all thyroid hormone biomarkers. Delayed freezing and freeze-thaw cycles did not affect reliability of biomarkers of thyroid function in plasma during pregnancy. See video abstract at, http://links.lww.com/EDE/B180.

Thyroid Hormone Receptor β (TRβ) and Liver X Receptor (LXR) Regulate Carbohydrate-response Element-binding Protein (ChREBP) Expression in a Tissue-selective Manner*

PubMed Central

Gauthier, Karine; Billon, Cyrielle; Bissler, Marie; Beylot, Michel; Lobaccaro, Jean-Marc; Vanacker, Jean-Marc; Samarut, Jacques

2010-01-01

Thyroid hormone (TR) and liver X (LXR) receptors are transcription factors involved in lipogenesis. Both receptors recognize the same consensus DNA-response element in vitro. It was previously shown that their signaling pathways interact in the control of cholesterol elimination in the liver. In the present study, carbohydrate-response element-binding protein (ChREBP), a major transcription factor controlling the activation of glucose-induced lipogenesis in liver, is characterized as a direct target of thyroid hormones (TH) in liver and white adipose tissue (WAT), the two main lipogenic tissues in mice. Using genetic and molecular approaches, ChREBP is shown to be specifically regulated by TRβ but not by TRα in vivo, even in WAT where both TR isoforms are expressed. However, this isotype specificity is not found in vitro. This TRβ specific regulation correlates with the loss of TH-induced lipogenesis in TRβ−/− mice. Fasting/refeeding experiments show that TRβ is not required for the activation of ChREBP expression particularly marked in WAT following refeeding. However, TH can stimulate ChREBP expression in WAT even under fasting conditions, suggesting completely independent pathways. Because ChREBP has been described as an LXR target, the interaction of LXR and TRβ in ChREBP regulation was assayed both in vitro and in vivo. Each receptor recognizes a different response element on the ChREBP promoter, located only 8 bp apart. There is a cross-talk between LXR and TRβ signaling on the ChREBP promoter in liver but not in WAT where LXR does not regulate ChREBP expression. The molecular basis for this cross-talk has been determined in in vitro systems. PMID:20615868

Adjunctive cholestyramine therapy for thyrotoxicosis.

PubMed

Solomon, B L; Wartofsky, L; Burman, K D

1993-01-01

Initial therapy of thyrotoxicosis usually includes beta-blockade for symptom relief and thionamides to block new thyroid hormone synthesis. In view of the increased enterohepatic circulation of thyroxine (T4) and triiodothyronine (T3) in thyrotoxicosis, we proposed that cholestyramine, an anion exchange resin which binds iodothyronines, when used adjunctively with thionamides and a beta-blocker, would lower serum iodothyronine levels faster than would standard therapy alone. A double blind placebo-controlled cross-over design was used with patients randomly assigned to either the treatment or control groups. They received their initial treatment for two weeks (Phase 1) followed by a one-week washout period, and then crossed to the opposite treatment for two weeks (Phase 2). Standard therapy included atenolol 50 mg daily, individualized dosages of methimazole and either 4 g of cholestyramine or 4 g of placebo powder four times per day. Fifteen patients with thyrotoxicosis (14 Graves' disease, 1 toxic adenoma) participated in this study. Total and free thyroxine and triiodothyronine, as well as thyroid-stimulating immunoglobulin and thyrotrophin-binding inhibitory immunoglobulin, were measured weekly. Seven patients received cholestyramine and eight patients received placebo during Phase 1. A more rapid decline in all thyroid hormone levels was seen in the cholestyramine-treated group (F = 4-7, P < 0.01) than in the placebo group (F = 2-3.1, P = 0.05). In Phase 2, the eight patients who received cholestyramine showed an additional decline in free thyroxine from weeks one to two, but the overall rate of decline in hormone levels was not different between the groups. Immunoglobulin levels remained unaffected regardless of group, treatment, or time. We conclude that cholestyramine is a safe and effective adjunctive agent in the treatment of thyrotoxicosis and that its greatest efficacy may be during the first few weeks of treatment.

TSH (Thyroid-stimulating hormone) test

MedlinePlus

... your blood ( hyperthyroidism ), or too little thyroid hormone ( hypothyroidism ). Symptoms of hyperthyroidism, also known as overactive thyroid, ... Bulging of the eyes Difficulty sleeping Symptoms of hypothyroidism, also known as underactive thyroid, include: Weight gain ...

Corticotropin-releasing hormone: Mediator of vertebrate life stage transitions?

PubMed

Watanabe, Yugo; Grommen, Sylvia V H; De Groef, Bert

2016-03-01

Hormones, particularly thyroid hormones and corticosteroids, play critical roles in vertebrate life stage transitions such as amphibian metamorphosis, hatching in precocial birds, and smoltification in salmonids. Since they synergistically regulate several metabolic and developmental processes that accompany vertebrate life stage transitions, the existence of extensive cross-communication between the adrenal/interrenal and thyroidal axes is not surprising. Synergies of corticosteroids and thyroid hormones are based on effects at the level of tissue hormone sensitivity and gene regulation. In addition, in representative nonmammalian vertebrates, corticotropin-releasing hormone (CRH) stimulates hypophyseal thyrotropin secretion, and thus functions as a common regulator of both the adrenal/interrenal and thyroidal axes to release corticosteroids and thyroid hormones. The dual function of CRH has been speculated to control or affect the timing of vertebrate life history transitions across taxa. After a brief overview of recent insights in the molecular mechanisms behind the synergic actions of thyroid hormones and corticosteroids during life stage transitions, this review examines the evidence for a possible role of CRH in controlling vertebrate life stage transitions. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of phenobarbital on thyroid hormone contabolism in rat hepatocytes

EPA Science Inventory

Hepatic enzyme inducers such as phenobarbital (PB) decrease circulating thyroid hormone (TH) concentrations in rodents. PB induction of hepatic xenobiotic metabolizing enzymes increases thyroid hormones catabolism and biliary elimination. This study examines the catabolism and cl...

Molecular mechanisms of corticosteroid synergy with thyroid hormone during tadpole metamorphosis

PubMed Central

Bonett, Ronald M.; Hoopfer, Eric D.; Denver, Robert J.

2010-01-01

Corticosteroids (CS) act synergistically with thyroid hormone (TH) to accelerate amphibian metamorphosis. Earlier studies showed that CS increase nuclear 3,5,3′-triiodothyronine (T3) binding capacity in tadpole tail, and 5′ deiodinase activity in tadpole tissues, increasing the generation of T3 from thyroxine (T4). In the present study we investigated CS synergy with TH by analyzing expression of key genes involved in TH and CS signaling using tadpole tail explant cultures, prometamorphic tadpoles, and frog tissue culture cells (XTC-2 and XLT-15). Treatment of tail explants with T3 at 100 nM, but not at 10 nM caused tail regression. Corticosterone (CORT) at three doses (100, 500, 3400 nM) had no effect or increased tail size. T3 at 10 nM plus CORT caused tails to regress similar to 100 nM T3. Thyroid hormone receptor beta (TRβ) mRNA was synergistically upregulated by T3 plus CORT in tail explants, tail and brain in vivo, and tissue culture cells. The activating 5′ deiodinase type 2 (D2) mRNA was induced by T3 and CORT in tail explants and tail in vivo. Thyroid hormone increased expression of glucocorticoid (GR) and mineralocorticoid receptor (MR) mRNAs. Our findings support that the synergistic actions of TH and CS in metamorphosis occur at the level of expression of genes for TRβ and D2, enhancing tissue sensitivity to TH. Concurrently, TH enhances tissue sensitivity to CS by upregulating GR and MR. Environmental stressors can modulate the timing of tadpole metamorphosis in part by CS enhancing the response of tadpole tissues to the actions of TH. PMID:20338173

Thyroid hormone receptor inhibits hepatoma cell migration through transcriptional activation of Dickkopf 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chi, Hsiang-Cheng; Liao, Chen-Hsin; Huang, Ya-Hui

Highlights: •T{sub 3} affects DKK4 mRNA and protein expression in HepG2-TR cells. •Regulation of DKK4 by T{sub 3} is at transcriptional level. •DKK4 overexpression suppresses hepatoma cell metastasis. -- Abstract: Triiodothyronine (T{sub 3}) is a potent form of thyroid hormone mediates several physiological processes including cellular growth, development, and differentiation via binding to the nuclear thyroid hormone receptor (TR). Recent studies have demonstrated critical roles of T{sub 3}/TR in tumor progression. Moreover, long-term hypothyroidism appears to be associated with the incidence of human hepatocellular carcinoma (HCC), independent of other major HCC risk factors. Dickkopf (DKK) 4, a secreted protein thatmore » antagonizes the canonical Wnt signaling pathway, is induced by T{sub 3} at both mRNA and protein levels in HCC cell lines. However, the mechanism underlying T{sub 3}-mediated regulation of DKK4 remains unknown. In the present study, the 5′ promoter region of DKK4 was serially deleted, and the reporter assay performed to localize the T{sub 3} response element (TRE). Consequently, we identified an atypical direct repeat TRE between nucleotides −1645 and −1629 conferring T{sub 3} responsiveness to the DKK4 gene. This region was further validated using chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA). Stable DKK4 overexpression in SK-Hep-1 cells suppressed cell invasion and metastatic potential, both in vivo andin vitro, via reduction of matrix metalloproteinase-2 (MMP-2) expression. Our findings collectively suggest that DKK4 upregulated by T{sub 3}/TR antagonizes the Wnt signal pathway to suppress tumor cell progression, thus providing new insights into the molecular mechanism underlying thyroid hormone activity in HCC.« less

Tissue-specific regulation of malic enzyme by thyroid hormone in the neonatal rat.

PubMed

Sood, A; Schwartz, H L; Oppenheimer, J H

1996-05-15

Two recent studies have claimed that thyroid hormone administration accelerates malic enzyme gene expression in the neonatal brain in contrast to the well-documented lack of effect of triiodothyronine on malic enzyme gene expression in the adult brain. Since these observations conflict with earlier observations in our laboratory, we reinvestigated the effect of thyroid hormone status on the ontogeny of malic enzyme gene expression in the neonatal rat. Neither hypothyroidism nor hyperthyroidism influenced the ontogenesis of malic enzyme activity in neonatal brain whereas the patterns of gene expression and enzyme activity in liver were markedly affected. Our results suggest that tissue-specific factors in brain block thyroid hormone-induced gene expression by thyroid hormone.

A New Family of Nuclear Receptor Coregulators That Integrate Nuclear Receptor Signaling through CREB-Binding Protein

PubMed Central

Mahajan, Muktar A.; Samuels, Herbert H.

2000-01-01

We describe the cloning and characterization of a new family of nuclear receptor coregulators (NRCs) which modulate the function of nuclear hormone receptors in a ligand-dependent manner. NRCs are expressed as alternatively spliced isoforms which may exhibit different intrinsic activities and receptor specificities. The NRCs are organized into several modular structures and contain a single functional LXXLL motif which associates with members of the steroid hormone and thyroid hormone/retinoid receptor subfamilies with high affinity. Human NRC (hNRC) harbors a potent N-terminal activation domain (AD1), which is as active as the herpesvirus VP16 activation domain, and a second activation domain (AD2) which overlaps with the receptor-interacting LXXLL region. The C-terminal region of hNRC appears to function as an inhibitory domain which influences the overall transcriptional activity of the protein. Our results suggest that NRC binds to liganded receptors as a dimer and this association leads to a structural change in NRC resulting in activation. hNRC binds CREB-binding protein (CBP) with high affinity in vivo, suggesting that hNRC may be an important functional component of a CBP complex involved in mediating the transcriptional effects of nuclear hormone receptors. PMID:10866662

Temperature induced variation in gene expression of thyroid hormone receptors and deiodinases of European eel (Anguilla anguilla) larvae.

PubMed

Politis, S N; Servili, A; Mazurais, D; Zambonino-Infante, J-L; Miest, J J; Tomkiewicz, J; Butts, I A E

2018-04-01

Thyroid hormones (THs) are key regulators of growth, development, and metabolism in vertebrates and influence early life development of fish. TH is produced in the thyroid gland (or thyroid follicles) mainly as T4 (thyroxine), which is metabolized to T3 (3,5,3'-triiodothyronine) and T2 (3,5-diiodothyronine) by deiodinase (DIO) enzymes in peripheral tissues. The action of these hormones is mostly exerted by binding to a specific nuclear thyroid hormone receptor (THR). In this study, we i) cloned and characterized thr sequences, ii) investigated the expression pattern of the different subtypes of thrs and dios, and iii) studied how temperature affects the expression of those genes in artificially produced early life history stages of European eel (Anguilla anguilla), reared in different thermal regimes (16, 18, 20 and 22 °C) from hatch until first-feeding. We identified 2 subtypes of thr (thrα and thrβ) with 2 isoforms each (thrαA, thrαB, thrβA, thrβB) and 3 subtypes of deiodinases (dio1, dio2, dio3). All thr genes identified showed high similarity to the closely related Japanese eel (Anguilla japonica). We found that all genes investigated in this study were affected by larval age (in real time or at specific developmental stages), temperature, and/or their interaction. More specifically, the warmer the temperature the earlier the expression response of a specific target gene. In real time, the expression profiles appeared very similar and only shifted with temperature. In developmental time, gene expression of all genes differed across selected developmental stages, such as at hatch, during teeth formation or at first-feeding. Thus, we demonstrate that thrs and dios show sensitivity to temperature and are involved in and during early life development of European eel. Copyright © 2017 Elsevier Inc. All rights reserved.

Relational Stability in the Expression of Normality, Variation, and Control of Thyroid Function

PubMed Central

Hoermann, Rudolf; Midgley, John E. M.; Larisch, Rolf; Dietrich, Johannes W.

2016-01-01

Thyroid hormone concentrations only become sufficient to maintain a euthyroid state through appropriate stimulation by pituitary thyroid-stimulating hormone (TSH). In such a dynamic system under constant high pressure, guarding against overstimulation becomes vital. Therefore, several defensive mechanisms protect against accidental overstimulation, such as plasma protein binding, conversion of T4 into the more active T3, active transmembrane transport, counter-regulatory activities of reverse T3 and thyronamines, and negative hypothalamic–pituitary–thyroid feedback control of TSH. TSH has gained a dominant but misguided role in interpreting thyroid function testing in assuming that its exceptional sensitivity thereby translates into superior diagnostic performance. However, TSH-dependent thyroid disease classification is heavily influenced by statistical analytic techniques such as uni- or multivariate-defined normality. This demands a separation of its conjoint roles as a sensitive screening test and accurate diagnostic tool. Homeostatic equilibria (set points) in healthy subjects are less variable and do not follow a pattern of random variation, rather indicating signs of early and progressive homeostatic control across the euthyroid range. In the event of imminent thyroid failure with a reduced FT4 output per unit TSH, conversion efficiency increases in order to maintain FT3 stability. In such situations, T3 stability takes priority over set point maintenance. This suggests a concept of relational stability. These findings have important implications for both TSH reference limits and treatment targets for patients on levothyroxine. The use of archival markers is proposed to facilitate the homeostatic interpretation of all parameters. PMID:27872610

Thyroid-stimulation hormone-receptor antibodies as a predictor of thyrosuppressive drug therapy outcome in Graves' disease patients.

PubMed

Aleksić, Aleksandar Z; Aleksić, Željka; Manić, Saška; Mitov, Vladimir; Jolić, Aleksandar

2014-01-01

Graves' disease is autoimmune hyperthyroidism caused by pathological stimulation of thyroid-stimulation hormone-receptor antibodies. The decision on changing the therapy can be made on time by determining the prognostic factors of thyrosuppressive drug therapy outcome. The aim of the study was to determine the significance of thyroid-stimulation hormone-receptor antibodies level on the prediction of therapy outcome. The study was prospective and involved 106 drug-treated patients with newly diagnosed Graves' disease. Thyroid-stimulation hormone-receptor antibodies level was measured at the beginning of therapy, during therapy and 12 months after it had been introduced. No statistically significant difference in the level of thyroid-stimulation hormone-receptor antibodies was found at the beginning of disease and 12 months after the introduction of thyrosuppressive drug therapy among the patients who had been in remission and those who had not. Regardless of the outcome, thyroid-stimulation hormone-receptor antibodies level significantly decreased in all patients 12 months after the therapy had been introduced. The level of thyroid-stimulation hormone-receptor antibodies at the beginning of disease and 12 months after the introduction of therapy cannot predict the outcome of thyrosuppressive drug therapy.

Selenium and the control of thyroid hormone metabolism.

PubMed

Köhrle, Josef

2005-08-01

Thyroid hormone synthesis, metabolism and action require adequate availability of the essential trace elements iodine and selenium, which affect homeostasis of thyroid hormone-dependent metabolic pathways. The three selenocysteine-containing iodothyronine deiodinases constitute a novel gene family. Selenium is retained and deiodinase expression is maintained at almost normal levels in the thyroid gland, the brain and several other endocrine tissues during selenium deficiency, thus guaranteeing adequate local and systemic levels of the active thyroid hormone T(3). Due to their low tissue concentrations and their mRNA SECIS elements deiodinases rank high in the cellular and tissue-specific hierarchy of selenium distribution among various selenoproteins. While systemic selenium status and expression of abundant selenoproteins (glutathione peroxidase or selenoprotein P) is already impaired in patients with cancer, disturbed gastrointestinal resorption, unbalanced nutrition or patients requiring intensive care treatment, selenium-dependent deiodinase function might still be adequate. However, disease-associated alterations in proinflammatory cytokines, growth factors, hormones and pharmaceuticals modulate deiodinase isoenzyme expression independent from altered selenium status and might thus pretend causal relationships between systemic selenium status and altered thyroid hormone metabolism. Limited or inadequate supply of both trace elements, iodine and selenium, leads to complex rearrangements of thyroid hormone metabolism enabling adaptation to unfavorable conditions.

Effects of prenatal exposure to organochlorines on thyroid hormone status in newborns from two remote coastal regions in Quebec, Canada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dallaire, Renee; Dewailly, Eric; Ayotte, Pierre

Background: Several prospective studies have revealed that prenatal exposure to polychlorinated biphenyls (PCBs) and other organochlorine compounds (OCs) affect neurodevelopment during infancy. One of the mechanisms by which PCBs might interfere with neurodevelopment is a deficit in thyroid hormone (TH) concentrations. Objectives: We investigated the potential impact of transplacental exposure to PCBs and hexachlorobenzene (HCB) on TH concentrations in neonates from two remote coastal populations exposed to OCs through the consumption of seafood products. Methods: Blood samples were collected at birth from the umbilical cord of neonates from Nunavik (n=410) and the Lower North Shore of the St. Lawrence Rivermore » (n=260) (Quebec, Canada) for thyroid parameters [thyroid-stimulating hormone (TSH), free T{sub 4} (fT{sub 4}), total T{sub 3} (tT{sub 3}), and thyroxine-binding globuline (TBG)] and contaminants analyses. Results: In multivariate models, umbilical cord plasma concentrations of PCB 153, the predominant PCB congener, were not associated with TH and TSH levels in both populations. Prenatal exposure to HCB was positively associated with fT{sub 4} levels at birth in both populations (Nunavik, {beta}=0.12, p=0.04; St. Lawrence, {beta}=0.19, p<0.01), whereas TBG concentrations were negatively associated with PCB 153 concentrations ({beta}=-0.13, p=0.05) in the St. Lawrence cohort. Conclusion: OCs levels were not associated to a reduction in THs in neonates from our two populations. Essential nutrients derived from seafood such as iodine may have prevented the negative effects of OCs on the thyroid economy during fetal development.« less

Association between thyroid hormones and TRAIL.

PubMed

Bernardi, Stella; Bossi, Fleur; Toffoli, Barbara; Giudici, Fabiola; Bramante, Alessandra; Furlanis, Giulia; Stenner, Elisabetta; Secchiero, Paola; Zauli, Giorgio; Carretta, Renzo; Fabris, Bruno

2017-11-01

Recent studies suggest that a circulating protein called TRAIL (TNF-related apoptosis-inducing ligand) might have a role in the regulation of body weight and metabolism. Interestingly, thyroid hormones seem to increase TRAIL tissue expression. This study aimed at evaluating whether overt thyroid disorders affected circulating TRAIL levels. TRAIL circulating levels were measured in euthyroid, hyperthyroid, and hypothyroid patients before and after thyroid function normalization. Univariate and multivariate analyses were performed to evaluate the correlation between thyroid hormones and TRAIL. Then, the stimulatory effect of both triiodothyronine (T3) and thyroxine (T4) on TRAIL was evaluated in vitro on peripheral blood mononuclear cells. Circulating levels of TRAIL significantly increased in hyperthyroid and decreased in hypothyroid patients as compared to controls. Once thyroid function was restored, TRAIL levels normalized. There was an independent association between TRAIL and both fT3 and fT4. Consistent with these findings, T3 and T4 stimulated TRAIL release in vitro. Here we show that thyroid hormones are associated with TRAIL expression in vivo and stimulate TRAIL expression in vitro. Given the overlap between the metabolic effects of thyroid hormones and TRAIL, this work sheds light on the possibility that TRAIL might be one of the molecules mediating thyroid hormones peripheral effects. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Maternal iron deficiency alters circulating thyroid hormone levels in developing neonatal rats

EPA Science Inventory

Thyroid hormone insufficiency and iron deficiency (FeD) during fetal and neonatal life are both similarly deleterious to mammalian development suggesting a possible linkage between iron and thyroid hormone insufficiencies. Recent published data from our laboratory demonstrate a r...

Establishing Adverse Outcome Pathways of Thyroid Hormone Disruption in an Amphibian Model

EPA Science Inventory

The Adverse Outcome Pathway (AOP) provides a framework for understanding the relevance of toxicology data in ecotoxicological hazard assessments. The AOP concept can be applied to many toxicological pathways including thyroid hormone disruption. Thyroid hormones play a critical r...

Thyrotropin-producing pituitary adenoma simultaneously existing with Graves' disease: a case report.

PubMed

Arai, Nobuhiko; Inaba, Makoto; Ichijyo, Takamasa; Kagami, Hiroshi; Mine, Yutaka

2017-01-06

Thyrotropin-producing pituitary tumor is relatively rare. In particular, concurrent cases associated with Graves' disease are extremely rare and only nine cases have been reported so far. We describe a case of a thyrotropin-producing pituitary adenoma concomitant with Graves' disease, which was successfully treated. A 40-year-old Japanese woman presented with mild signs of hyperthyroidism. She had positive anti-thyroid-stimulating hormone receptor antibody, anti-thyroglobulin antibody, and anti-thyroid peroxidase antibody. Her levels of serum thyroid-stimulating hormone, which ranged from low to normal in the presence of high levels of serum free thyroid hormones, were considered to be close to a state of syndrome of inappropriate secretion of thyroid-stimulating hormone. Magnetic resonance imaging showed a macropituitary tumor. The coexistence of thyrotropin-producing pituitary adenoma and Graves' disease was suspected. Initial therapy included anti-thyroid medication, which was immediately discontinued due to worsening symptoms. Subsequently, surgical therapy for the pituitary tumor was conducted, and her levels of free thyroid hormones, including the thyroid-stimulating hormone, became normal. On postoperative examination, her anti-thyroid-stimulating hormone receptor antibody levels decreased, and the anti-thyroglobulin antibody became negative. The coexistence of thyrotropin-producing pituitary adenoma and Graves' disease is rarely reported. The diagnosis of this condition is complicated, and the appropriate treatment strategy has not been clearly established. This case suggests that physicians should consider the coexistence of thyrotropin-producing pituitary adenoma with Graves' disease in cases in which thyroid-stimulating hormone values range from low to normal in the presence of thyrotoxicosis, and the surgical treatment of thyrotropin-producing pituitary adenoma could be the first-line therapy in patients with both thyrotropin-producing pituitary adenoma and Graves' disease.

Hyperthyroidism

PubMed Central

2016-01-01

Hyperthyroidism is characterised by increased thyroid hormone synthesis and secretion from the thyroid gland, whereas thyrotoxicosis refers to the clinical syndrome of excess circulating thyroid hormones, irrespective of the source. The most common cause of hyperthyroidism is Graves’ disease, followed by toxic nodular goitre. Other important causes of thyrotoxicosis include thyroiditis, iodine-induced and drug-induced thyroid dysfunction, and factitious ingestion of excess thyroid hormones. Treatment options for Graves’ disease include antithyroid drugs, radioactive iodine therapy, and surgery, whereas antithyroid drugs are not generally used long term in toxic nodular goitre, because of the high relapse rate of thyrotoxicosis after discontinuation. β blockers are used in symptomatic thyrotoxicosis, and might be the only treatment needed for thyrotoxicosis not caused by excessive production and release of the thyroid hormones. Thyroid storm and hyperthyroidism in pregnancy and during the post-partum period are special circumstances that need careful assessment and treatment. PMID:27038492

Hyperthyroidism.

PubMed

De Leo, Simone; Lee, Sun Y; Braverman, Lewis E

2016-08-27

Hyperthyroidism is characterised by increased thyroid hormone synthesis and secretion from the thyroid gland, whereas thyrotoxicosis refers to the clinical syndrome of excess circulating thyroid hormones, irrespective of the source. The most common cause of hyperthyroidism is Graves' disease, followed by toxic nodular goitre. Other important causes of thyrotoxicosis include thyroiditis, iodine-induced and drug-induced thyroid dysfunction, and factitious ingestion of excess thyroid hormones. Treatment options for Graves' disease include antithyroid drugs, radioactive iodine therapy, and surgery, whereas antithyroid drugs are not generally used long term in toxic nodular goitre, because of the high relapse rate of thyrotoxicosis after discontinuation. β blockers are used in symptomatic thyrotoxicosis, and might be the only treatment needed for thyrotoxicosis not caused by excessive production and release of the thyroid hormones. Thyroid storm and hyperthyroidism in pregnancy and during the post-partum period are special circumstances that need careful assessment and treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

The renin-angiotensin system in thyroid disorders and its role in cardiovascular and renal manifestations.

PubMed

Vargas, Félix; Rodríguez-Gómez, Isabel; Vargas-Tendero, Pablo; Jimenez, Eugenio; Montiel, Mercedes

2012-04-01

Thyroid disorders are among the most common endocrine diseases and affect virtually all physiological systems, with an especially marked impact on cardiovascular and renal systems. This review summarizes the effects of thyroid hormones on the renin-angiotensin system (RAS) and the participation of the RAS in the cardiovascular and renal manifestations of thyroid disorders. Thyroid hormones are important regulators of cardiac and renal mass, vascular function, renal sodium handling, and consequently blood pressure (BP). The RAS acts globally to control cardiovascular and renal functions, while RAS components act systemically and locally in individual organs. Various authors have implicated the systemic and local RAS in the mediation of functional and structural changes in cardiovascular and renal tissues due to abnormal thyroid hormone levels. This review analyzes the influence of thyroid hormones on RAS components and discusses the role of the RAS in BP, cardiac mass, vascular function, and renal abnormalities in thyroid disorders.

Sulfated Metabolites of Polychlorinated Biphenyls Are High-Affinity Ligands for the Thyroid Hormone Transport Protein Transthyretin

PubMed Central

Grimm, Fabian A.; Lehmler, Hans-Joachim; He, Xianran; Robertson, Larry W.

2013-01-01

Background: The displacement of l-thyroxine (T4) from binding sites on transthyretin (TTR) is considered a significant contributing mechanism in polychlorinated biphenyl (PCB)-induced thyroid disruption. Previous research has discovered hydroxylated PCB metabolites (OH-PCBs) as high-affinity ligands for TTR, but the binding potential of conjugated PCB metabolites such as PCB sulfates has not been explored. Objectives: We evaluated the binding of five lower-chlorinated PCB sulfates to human TTR and compared their binding characteristics to those determined for their OH-PCB precursors and for T4. Methods: We used fluorescence probe displacement studies and molecular docking simulations to characterize the binding of PCB sulfates to TTR. The stability of PCB sulfates and the reversibility of these interactions were characterized by HPLC analysis of PCB sulfates after their binding to TTR. The ability of OH-PCBs to serve as substrates for human cytosolic sulfotransferase 1A1 (hSULT1A1) was assessed by OH-PCB–dependent formation of adenosine-3´,5´-diphosphate, an end product of the sulfation reaction. Results: All five PCB sulfates were able to bind to the high-affinity binding site of TTR with equilibrium dissociation constants (Kd values) in the low nanomolar range (4.8–16.8 nM), similar to that observed for T4 (4.7 nM). Docking simulations provided corroborating evidence for these binding interactions and indicated multiple high-affinity modes of binding. All OH-PCB precursors for these sulfates were found to be substrates for hSULT1A1. Conclusions: Our findings show that PCB sulfates are high-affinity ligands for human TTR and therefore indicate, for the first time, a potential relevance for these metabolites in PCB-induced thyroid disruption. PMID:23584369

IL-1β a potential factor for discriminating between thyroid carcinoma and atrophic thyroiditis.

PubMed

Kammoun-Krichen, Maha; Bougacha-Elleuch, Noura; Mnif, Mouna; Bougacha, Fadia; Charffedine, Ilhem; Rebuffat, Sandra; Rebai, Ahmed; Glasson, Emilie; Abid, Mohamed; Ayadi, Fatma; Péraldi-Roux, Sylvie; Ayadi, Hammadi

2012-01-01

Interactions between cytokines and others soluble factors (hormones, antibodies...) can play an important role in the development of thyroid pathogenesis. The purpose of the present study was to examine the possible correlation between serum cytokine concentrations, thyroid hormones (FT4 and TSH) and auto-antibodies (Tg and TPO), and their usefulness in discriminating between different thyroid conditions. In this study, we investigated serum from 115 patients affected with a variety of thyroid conditions (44 Graves' disease, 17 Hashimoto's thyroiditis, 11 atrophic thyroiditis, 28 thyroid nodular goitre and 15 papillary thyroid cancer), and 30 controls. Levels of 17 cytokines in serum samples were measured simultaneously using a multiplexed human cytokine assay. Thyroid hormones and auto-antibodies were measured using ELISA. Our study showed that IL-1β serum concentrations allow the discrimination between atrophic thyroiditis and papillary thyroid cancer groups (p = 0.027).

Development of the thyroid gland.

PubMed

Nilsson, Mikael; Fagman, Henrik

2017-06-15

Thyroid hormones are crucial for organismal development and homeostasis. In humans, untreated congenital hypothyroidism due to thyroid agenesis inevitably leads to cretinism, which comprises irreversible brain dysfunction and dwarfism. Elucidating how the thyroid gland - the only source of thyroid hormones in the body - develops is thus key for understanding and treating thyroid dysgenesis, and for generating thyroid cells in vitro that might be used for cell-based therapies. Here, we review the principal mechanisms involved in thyroid organogenesis and functional differentiation, highlighting how the thyroid forerunner evolved from the endostyle in protochordates to the endocrine gland found in vertebrates. New findings on the specification and fate decisions of thyroid progenitors, and the morphogenesis of precursor cells into hormone-producing follicular units, are also discussed. © 2017. Published by The Company of Biologists Ltd.

The influence of hormonal and neuronal factors on rat heart adrenoceptors

PubMed Central

Kunos, George; Mucci, Lucia; O'Regan, Seana

1980-01-01

1 The influence of hormonal and neuronal factors on adrenoceptors mediating increased cardiac force and rate of contraction were studied in rat isolated atria. The pharmacological properties of these receptors were deduced from the relative potencies of agonists and from the effects of selective α- and β-adrenoceptor antagonists. The numbers and affinities of α- and β-adrenoceptors were also determined by radioligand binding to ventricular membrane fragments. 2 Hypophysectomy reduced the inotropic potency of isoprenaline and increased the potency of phenylephrine and methoxamine in left atria. The effect of phenylephrine was inhibited by propranolol less effectively and by phentolamine or phenoxybenzamine more effectively in hypophysectomized than in control rats. The difference in block was smaller at low than at high antagonist concentrations. Similar but smaller changes were observed for chronotropic responses of right atria. 3 The decreased β- and increased α-receptor response after hypophysectomy was similar to that observed earlier in thyroidectomized rats (Kunos, 1977). These changes developed slowly after hypophysectomy (>2 weeks), they were both reversed within 2 days of thyroxine treatment (0.2 mg/kg daily), but were not affected by cortisone treatment (50 mg/kg every 12 h for 4 days). 4 Treatment of hypophysectomized rats for 2 days with thyroxine increased the density of [3H]-dihydroalprenolol ([3H]-DHA) binding sites from 27.5 ± 2.7 to 45.5 ± 5.7 fmol/mg protein and decreased the density of [3H]-WB-4101 binding sites from 38.7 ± 3.1 to 18.7 ± 2.5 fmol/mg protein. The affinity of either type of binding site for agonists or antagonist was not significantly altered by thyroxine treatment and the sum total of α1- and β-receptors remained the same. 5 Sympathetic denervation of thyroidectomized rats by 6-hydroxydopamine increased the inotropic potency of isoprenaline and noradrenaline and the blocking effect of propranolol, and decreased the potency of phenylephrine and the blocking effect of phenoxybenzamine to or beyond values observed in euthyroid controls. The density of [3H]-DHA binding sites was higher and that of [3H]-WB-4101 binding sites was lower in the denervated than in the innervated hypothyroid myocardium. Depletion of endogenous noradrenaline stores by reserpine did not significantly alter the adrenoceptor response pattern of the hypothyroid preparations and did not influence the density or affinity of [3H]-DHA and [3H]-WB-4101 binding sites. 6 These results indicate that thyrotropin or steroids do not contribute to the reciprocal changes in the sensitivity of cardiac α1- and β-adrenoceptors in altered thyroid states. These thyroid hormone-dependent changes are probably due to a parallel, reciprocal change in the numbers but not the affinities of α1- and β-adrenoceptors. Reciprocal regulation of cardiac α1- and β-adrenoceptors by thyroid hormones requires intact sympathetic innervation but not the presence of normal stores of the neurotransmitter. PMID:7470752

Thyroid hormone concentrations in captive and free-ranging West Indian manatees (Trichechus manatus).

PubMed

Ortiz, R M; MacKenzie, D S; Worthy, G A

2000-12-01

Because thyroid hormones play a critical role in the regulation of metabolism, the low metabolic rates reported for manatees suggest that thyroid hormone concentrations in these animals may also be reduced. However, thyroid hormone concentrations have yet to be examined in manatees. The effects of captivity, diet and water salinity on plasma total triiodothyronine (tT(3)), total thyroxine (tT(4)) and free thyroxine (fT(4)) concentrations were assessed in adult West Indian manatees (Trichechus manatus). Free-ranging manatees exhibited significantly greater tT(4) and fT(4) concentrations than captive adults, regardless of diet, indicating that some aspect of a captive existence results in reduced T(4) concentrations. To determine whether this reduction might be related to feeding, captive adults fed on a mixed vegetable diet were switched to a strictly sea grass diet, resulting in decreased food consumption and a decrease in body mass. However, tT(4) and fT(4) concentrations were significantly elevated over initial values for 19 days. This may indicate that during periods of reduced food consumption manatees activate thyroid-hormone-promoted lipolysis to meet water and energetic requirements. Alterations in water salinity for captive animals did not induce significant changes in thyroid hormone concentrations. In spite of lower metabolic rates, thyroid hormone concentrations in captive manatees were comparable with those for other terrestrial and marine mammals, suggesting that the low metabolic rate in manatees is not attributable to reduced circulating thyroid hormone concentrations.

A Hormonally Active Malignant Struma Ovarii

PubMed Central

Lara, Carolina; Salame, Latife; Padilla-Longoria, Rafael

2016-01-01

Struma ovarii is a rare monodermal variant of ovarian teratoma that contains at least 50% thyroid tissue. Less than 8% of struma ovarii cases present with clinical and biochemical evidence of thyrotoxicosis due to ectopic production of thyroid hormone and only 5% undergo malignant transformation into a papillary thyroid carcinoma. Only isolated cases of hormonally active papillary thyroid carcinoma developing within a struma ovarii have been reported in the literature. We report the case of a 36-year-old woman who presented with clinical signs and symptoms of hyperthyroidism as well as a left adnexal mass, which proved to be a thyroid hormone-producing, malignant struma ovarii. PMID:27882257

Regulation of fish growth hormone transcription.

PubMed

Farchi-Pisanty, O; Hackett, P B; Moav, B

1995-09-01

Regulation of endogenous fish growth hormone transcription was studied using carp pituitaries in vitro. It was demonstrated that thyroid hormone (T3) and 9-cis retinoic acid have increased the steady state levels of growth hormone messenger RNA in pituitary cells, as compared with beta-actin messenger RNA levels. In contrast, estrogen failed to increase growth hormone mRNA levels. The possible involvement of thyroid hormone receptor in pituitary gene expression was demonstrated by in situ localization of both growth hormone mRNA and thyroid hormone receptor mRNA in the pituitaries as early as 4 days after fertilization.

Thyroid and the Heart

PubMed Central

Grais, Ira Martin; Sowers, James R.

2015-01-01

Thyroid hormones modulate every component of the cardiovascular system necessary for normal cardiovascular development and function. When cardiovascular disease is present, thyroid function tests are characteristically indicated to determine if overt thyroid disorders or even subclinical dysfunction exists. As hypothyroidism, hypertension and cardiovascular disease all increase with advancing age monitoring of TSH, the most sensitive test for hypothyroidism, is important in this expanding segment of our population. A better understanding of the impact of thyroid hormonal status on cardiovascular physiology will enable health care providers to make decisions regarding thyroid hormone evaluation and therapy in concert with evaluating and treating hypertension and cardiovascular disease. The goal of this review is to access contemporary understanding of the effects of thyroid hormones on normal cardiovascular function and the potential role of overt and subclinical hypothyroidism and hyperthyroidism in a variety of cardiovascular diseases. PMID:24662620

Pituitary Tumors

MedlinePlus

... or milk production), sex hormones (control the menstrual cycle and other sexual functions), thyroid gland hormones (control the thyroid gland), adrenal gland hormones, and vasopressin (a hormone involved in water and electrolyte balance). Symptoms of pituitary adenoma and ...

THYROID HORMONE DISRUPTION: FROM KINETICS TO DYNAMICS.

EPA Science Inventory

A wide range of chemicals with diverse structures act as thyroid disrupting chemicals (TDCs). Broadly defined, TDCs are chemicals that alter the structure or function of the thyroid gland, alter regulatory enzymes associated with thyroid hormones (THs), or change circulating or t...

Early Temporal Effects of Three Thyroid Hormone Synthesis Inhibitors in Xenopus laevis

EPA Science Inventory

Thyroid axis disruption is an important consideration when evaluating the risks associated with chemicals. Bioassay methods that include thyroid-related endpoints have been developed in a variety of species, including amphibians, whose metamorphic development is thyroid hormone ...

[Advances in postoperative thyroid-stimulating hormone suppression therapy in females with thyroid cancer].

PubMed

Song, F; Yi, H L

2018-05-07

Differentiated thyroid cancer is the most common malignant carcinoma in female population.Postoperative long-term thyroid-stimulating hormone(TSH) suppression therapy can reduce the risk of recurrence for differentiated thyroid cancer and control the progress of the disease, but it also induces simultaneously subclinical hypothyroidism and imposes negative effect on female. In addition to cardiovascular disease, TSH suppression therapy can lead to the alteration of sex hormone metabolism, menstrual disorder, poor influence on pregnancy and osteoporosis. This article reviews the recent studies on postoperative TSH suppression therapy in women with thyroid cancer.

New approaches to thyroid hormones and purinergic signaling.

PubMed

Silveira, Gabriel Fernandes; Buffon, Andréia; Bruno, Alessandra Nejar

2013-01-01

It is known that thyroid hormones influence a wide variety of events at the molecular, cellular, and functional levels. Thyroid hormones (TH) play pivotal roles in growth, cell proliferation, differentiation, apoptosis, development, and metabolic homeostasis via thyroid hormone receptors (TRs) by controlling the expression of TR target genes. Most of these effects result in pathological and physiological events and are already well described in the literature. Even so, many recent studies have been devoted to bringing new information on problems in controlling the synthesis and release of these hormones and to elucidating mechanisms of the action of these hormones unconventionally. The purinergic system was recently linked to thyroid diseases, including enzymes, receptors, and enzyme products related to neurotransmitter release, nociception, behavior, and other vascular systems. Thus, throughout this text we intend to relate the relationship between the TH in physiological and pathological situations with the purinergic signaling.

New Approaches to Thyroid Hormones and Purinergic Signaling

PubMed Central

Silveira, Gabriel Fernandes; Buffon, Andréia; Bruno, Alessandra Nejar

2013-01-01

It is known that thyroid hormones influence a wide variety of events at the molecular, cellular, and functional levels. Thyroid hormones (TH) play pivotal roles in growth, cell proliferation, differentiation, apoptosis, development, and metabolic homeostasis via thyroid hormone receptors (TRs) by controlling the expression of TR target genes. Most of these effects result in pathological and physiological events and are already well described in the literature. Even so, many recent studies have been devoted to bringing new information on problems in controlling the synthesis and release of these hormones and to elucidating mechanisms of the action of these hormones unconventionally. The purinergic system was recently linked to thyroid diseases, including enzymes, receptors, and enzyme products related to neurotransmitter release, nociception, behavior, and other vascular systems. Thus, throughout this text we intend to relate the relationship between the TH in physiological and pathological situations with the purinergic signaling. PMID:23956925

THE THYROID HORMONE TRANSPORTER, MCT8, SELECTIVELY RESPONDS TO THYROID HORMONE INSUFFICIENCY IN THE DEVELOPMENT RAT BRAIN.

EPA Science Inventory

Thyroid hormone (TH) is essential for normal brain development. Therefore, it is not surprising that a variety of adaptive mechanisms are activated in response to TH insufficiency. However, not all brain regions respond in the same fashion to TH insufficiency. This observation...

Polybrominated Diphenyl Ether (DE-71)Interferes with Thyroid Hormone Action Independent Of Effects On Circulating Levels of Thyroid Hormone in Male Rats

EPA Science Inventory

Polybrominated diphenyl ethers (PBDEs) are routinely found in human tissues including cord blood and breast milk. PBDEs may interfere with thyroid hormone (TH) during development, which could produce neurobehavioral deficits. An assumption in experimental and epidemiological stud...

Analysis of thyroid hormones in biological samples using stable isotope dilution liquid chromatography-tandem mass spectrometry

EPA Science Inventory

This poster presentation will describe analytical chemistry methods for measuring thyroid hormones and related precursors and metabolites in very small tissue or plasma samples. These methods are amenable to measure thyroid hormones in amphibian tadpoles or small mammals used as ...

Gene Expression as a Biomarker of Effect of Thyroid Hormone Action in Developing Brain: Relation to Serum Hormones.

EPA Science Inventory

Disruption of thyroid hormone (TH) homeostasis is a known effect of environmental contaminants. Although animal models of developmental TH deficiency can predict the impact of severe insults to the thyroid system, the effects of moderate TH insufficiencies have proved more diffic...

Thyroid Hormone in the Clinic and Breast Cancer.

PubMed

Hercbergs, Aleck; Mousa, Shaker A; Leinung, Matthew; Lin, Hung-Yun; Davis, Paul J

2018-06-01

There is preclinical and recent epidemiological evidence that thyroid hormone supports breast cancer. These observations raise the issue of whether management of breast cancer in certain settings should include consideration of reducing the possible contribution of thyroid hormone to the advancement of the disease. In a preliminary experience, elimination of the clinical action of endogenous L-thyroxine (T 4 ) in patients with advanced solid tumors, including breast cancer, has favorably affected the course of the cancer, particularly when coupled with administration of exogenous 3,5,3'-triiodo-L-thyronine (T 3 ) (euthyroid hypothyroxinemia). We discuss in the current brief review the possible clinical settings in which to consider whether endogenous thyroid hormone-or exogenous thyroid hormone in the patient with hypothyroidism and coincident breast cancer-is significantly contributing to breast cancer outcome.

Levothyroxine

MedlinePlus

Levothyroxine, a thyroid hormone, is used to treat hypothyroidism, a condition where the thyroid gland does not ... hormone.Levothyroxine is also used to treat congenital hypothyroidism (cretinism) and goiter (enlarged thyroid gland). Levothyroxine is ...

Hormonal and reproductive risk factors of papillary thyroid cancer: A population-based case-control study in France.

PubMed

Cordina-Duverger, Emilie; Leux, Christophe; Neri, Monica; Tcheandjieu, Catherine; Guizard, Anne-Valérie; Schvartz, Claire; Truong, Thérèse; Guénel, Pascal

2017-06-01

The three times higher incidence of thyroid cancer in women compared to men points to a role of female sex hormones in its etiology. However the effects of these factors are poorly understood. We analyzed the association between thyroid cancer and hormonal and reproductive factors among women enrolled in CATHY, a population-based case-control study conducted in France. The study included 430 cases of papillary thyroid cancer and 505 controls frequency-matched on age and area of residence. The odds ratios for thyroid cancer increased with age at menarche (p trend 0.05). Postmenopausal women were at increased risk, as compared to premenopausal women, particularly if menopause followed an ovariectomy, and for women with age at menopause <55years. In addition, use of oral contraceptives and menopausal hormone therapy reduced the association with thyroid cancer by about one third, and breastfeeding by 27%. Overall, these findings provide evidence that the risk of thyroid cancer increases with later age at menarche and after menopause, and decreases with use of oral contraceptives and menopausal hormone therapy. These findings confirm an implication of hormonal factors in papillary thyroid cancer risk, whose mechanisms need to be elucidated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hyperthyroidism.

PubMed

Maji, D

2006-10-01

Hyperthyroidism is a clinical situation where there is excess thyroid hormones in the circulation due to increased synthesis of hormone from a hyperactive thyroid gland. Common causes are Graves' disease, toxic multinodular goitre and toxic solitary nodule. Excess thyroid hormones in the circulation are also found in thyroiditis (hormone leakage) and excess exogenous thyroxine intake. Thyrotoxicosis is the term applied when there is excess thyroid hormone in the circulation due to any cause. Thyrotoxicosis can be easily diagnosed by high serum level of thyroxine (T4) and triiodothyronine (T3) and low serum level of thyroid stimulating hormone (TSH). Hyperthyroidism is confirmed by high isotope (I 131 or Tc99) uptake by the thyroid gland, while in thyroiditis it will be low. Treatment of hyperthyroidism depends on the underlying cause. Antithyroid drugs, 1131 therapy and surgery are the options of treatment of hyperthyroidism. Surgery is the preferred treatment for toxic adenoma and toxic multinodular goitre, while 1131 therapy may be suitable in some cases. Antithyroid drugs and 1131 therapy are mostly preferred for Graves' disease. Beta-adrenergic blockers are used for symptomatic relief in most patients of thyrotoxicosis due to any cause. Other rare causes of hyperthyroidism like, amiodarone induced thyrotoxicosis, choriocarcinoma, thyrotropin secreting pituitary tumour are difficult to diagnose as well as to treat.

Subclinical Hyperthyroidism: When to Consider Treatment.

PubMed

Donangelo, Ines; Suh, Se Young

2017-06-01

Subclinical hyperthyroidism is defined by a low or undetectable serum thyroid-stimulating hormone level, with normal free thyroxine and total or free triiodothyronine levels. It can be caused by increased endogenous production of thyroid hormone (e.g., in Graves disease, toxic nodular goiter, or transient thyroiditis), by administration of thyroid hormone to treat malignant thyroid disease, or by unintentional excessive replacement therapy. The prevalence of subclinical hyperthyroidism in the general population is about 1% to 2%; however, it may be higher in iodinedeficient areas. The rate of progression to overt hyperthyroidism is higher in persons with thyroid-stimulating hormone levels less than 0.1 mIU per L than in persons with low but detectable thyroid-stimulating hormone levels. Subclinical hyperthyroidism is associated with an increased risk of atrial fibrillation and heart failure in older adults, increased cardiovascular and all-cause mortality, and decreased bone mineral density and increased bone fracture risk in postmenopausal women. However, the effectiveness of treatment in preventing these conditions is unclear. A possible association between subclinical hyperthyroidism and quality-of-life parameters and cognition is controversial. The U.S. Preventive Services Task Force found insufficient evidence to assess the balance of benefits and harms of screening for thyroid dysfunction in asymptomatic persons. The American Thyroid Association and the American Association of Clinical Endocrinologists recommend treating patients with thyroid-stimulating hormone levels less than 0.1 mIU per L if they are older than 65 years or have comorbidities such as heart disease or osteoporosis.

Endocrinology Update: Thyroid Disorders.

PubMed

Kelley, Scott

2016-12-01

Thyroid disease affects nearly every organ system in the body. Hypothyroidism is a state of thyroid hormone insufficiency that results in decreased metabolism and secondary effects including fatigue and weight gain. Primary hypothyroidism typically is a result of autoimmune thyroiditis or iodine deficiency and is assessed by measurement of the thyroid-stimulating hormone (TSH) level. This level usually is elevated in patients with hypothyroidism and low in patients with hyperthyroidism. Levothyroxine is the treatment of choice for hypothyroidism. Hyperthyroidism is a state of thyroid hormone excess, which increases the metabolic rate and causes symptoms including anxiety and tremor. Graves disease is the most common etiology in developed countries. Patients with hyperthyroidism are evaluated with measurement of TSH and free thyroxine levels. Management options include antithyroid drugs, radioactive iodine, and surgery. Thyroid nodules are detected commonly in family medicine, and may or may not be associated with thyroid hormone abnormalities. Patients with thyroid nodules should be evaluated with TSH level measurement and thyroid ultrasonography to guide further testing. Written permission from the American Academy of Family Physicians is required for reproduction of this material in whole or in part in any form or medium.

Competition between thyroid hormone receptor-associated protein (TRAP) 220 and transcriptional intermediary factor (TIF) 2 for binding to nuclear receptors. Implications for the recruitment of TRAP and p160 coactivator complexes.

PubMed

Treuter, E; Johansson, L; Thomsen, J S; Wärnmark, A; Leers, J; Pelto-Huikko, M; Sjöberg, M; Wright, A P; Spyrou, G; Gustafsson, J A

1999-03-05

Transcriptional activation by nuclear receptors (NRs) involves the concerted action of coactivators, chromatin components, and the basal transcription machinery. Crucial NR coactivators, which target primarily the conserved ligand-regulated activation (AF-2) domain, include p160 family members, such as TIF2, as well as p160-associated coactivators, such as CBP/p300. Because these coactivators possess intrinsic histone acetyltransferase activity, they are believed to function mainly by regulating chromatin-dependent transcriptional activation. Recent evidence suggests the existence of an additional NR coactivator complex, referred to as the thyroid hormone receptor-associated protein (TRAP) complex, which may function more directly as a bridging complex to the basal transcription machinery. TRAP220, the 220-kDa NR-binding subunit of the complex, has been identified in independent studies using both biochemical and genetic approaches. In light of the functional differences identified between p160 and TRAP coactivator complexes in NR activation, we have attempted to compare interaction and functional characteristics of TIF 2 and TRAP220. Our findings imply that competition between the NR-binding subunits of distinct coactivator complexes may act as a putative regulatory step in establishing either a sequential activation cascade or the formation of independent coactivator complexes.

The hippocampal formation: morphological changes induced by thyroid, gonadal and adrenal hormones.

PubMed

Gould, E; Woolley, C S; McEwen, B S

1991-01-01

The hippocampal formation is of considerable interest due to its proposed role in a number of important functions, including learning and memory processes. Manipulations of thyroid, gonadal and adrenal hormones have been shown to influence hippocampal physiology as well as learning and memory. The cellular events which underlie these hormone-induced functional changes are largely unexplored. However, studies suggest that hormonal manipulations during development and in adulthood result in dramatic morphological changes within the hippocampal formation. Because neuronal physiology has been suggested to depend upon neuronal morphology, we have been determining the morphologic sensitivity of hippocampal neurons to thyroid and steroid hormones in an effort to elucidate possible structural mechanisms to account for differences in hippocampal function. In this review, hormone-induced structural changes in the developing and adult hippocampal formation are discussed, with particular emphasis on their functional relevance. Sex differences, as well as the developmental effects of thyroid hormone and glucocorticoids, are described. Moreover, the effects of ovarian steroids, thyroid hormone and glucocorticoids on neuronal morphology in the hippocampal formation of the adult rat are reviewed. These hormone-induced structural changes may account, at least in part, for previously reported hormone-induced changes in hippocampal function.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahren, B.

The thyroid gland is known to harbor cholinergic and VIPergic nerves. In the present study, the influences of cholinergic stimulation by carbachol, cholinergic blockade by methylatropine and stimulation with various VIP sequences on basal, TSH-induced and VIP-induced thyroid hormone secretion were investigated in vivo in mice. The mice were pretreated with /sup 125/I and thyroxine; the subsequent release of /sup 125/I is an estimation of thyroid hormone secretion. It was found that basal radioiodine secretion was inhibited by both carbachol and methylatropine. Furthermore, TSH-induced radioiodine secretion was inhibited already by a low dose of carbachol. Moreover, a high dose ofmore » carbachol could inhibit VIP-induced radioiodine secretion. Methylatropine did not influence TSH- or VIP-stimulated radioiodine secretion, but counteracted the inhibitory action of carbachol on TSH- and VIP-induced radioiodine release. In addition, contrary to VIP, six various synthesized VIP fragments had no effect on basal or stimulated radioiodine release. It is concluded that basal thyroid hormone secretion is inhibited by both cholinergic activation and blockade. Furthermore, TSH-induced thyroid hormone secretion is more sensitive to inhibition with cholinergic stimulation than is VIP-induced thyroid hormone secretion. In addition, the VIP stimulation of thyroid hormone secretion seems to require the full VIP sequence.« less

Pituitary apoplexy

MedlinePlus

... body's sex glands produce little or no hormones) Hypothyroidism (thyroid gland does not make enough thyroid hormone) ... other missing hormones are not replaced, symptoms of hypothyroidism and hypogonadism may develop.

A review on hyperthyroidism: thyrotoxicosis under surveillance.

PubMed

Mansourian, Azad Reza

2010-11-15

Thyrotoxicosis exhibit collective clinical manifestation, caused by excessive serum thyroid hormones particularity thyroxin. The clinical signs and symptoms included general alteration of metabolic process leading to weight loss fatigue and weakness and some specific disorders such as cardiovascular, neuromuscular reproductive gastrointestinal dermatological and bone disorders. The diagnosis of thyrotoxicosis relay on the thyroid function test carried out by the laboratory serum measurement of thyroxin, triiodothyronine and thyroid stimulating hormones accompanied by other para-medical examinations suggested by clinicians and endociologicst. In thyrotoxicosis serum level of thyroid hormones and thyroxin in particular elevated accompanied by pituitary thyroid stimulating hormone suppression reaching to undetectable level in sever thyrotoxicosis. Among the most common cause of thyrotoxicosis are, thyroid autoimmunity diseases thyroid toxic, adenoma toxic nodular and multinodular hyperthyroidism. The main aim behind this review is to explore the clinical manifestation, the causative factors, diagnosis, metabolic disorder occur due to thyrotoxicosis.

Disruption of thyroid hormone functions by low dose exposure of tributyltin: an in vitro and in vivo approach.

PubMed

Sharan, Shruti; Nikhil, Kumar; Roy, Partha

2014-09-15

Triorganotins, such as tributyltin chloride (TBTCl), are environmental contaminants that are commonly found in the antifouling paints used in ships and other vessels. The importance of TBTCl as an endocrine-disrupting chemical (EDC) in different animal models is well known; however, its adverse effects on the thyroid gland are less understood. Hence, in the present study, we aimed to evaluate the thyroid-disrupting effects of this chemical using both in vitro and in vivo approaches. We used HepG2 hepatocarcinoma cells for the in vitro studies, as they are a thyroid hormone receptor (TR)-positive and thyroid responsive cell line. For the in vivo studies, Swiss albino male mice were exposed to three doses of TBTCl (0.5, 5 and 50μg/kg/day) for 45days. TBTCl showed a hypo-thyroidal effect in vivo. Low-dose treatment of TBTCl exposure markedly decreased the serum thyroid hormone levels via the down-regulation of the thyroid peroxidase (TPO) and thyroglobulin (Tg) genes by 40% and 25%, respectively, while augmenting the thyroid stimulating hormone (TSH) levels. Thyroid-stimulating hormone receptor (TSHR) expression was up-regulated in the thyroid glands of treated mice by 6.6-fold relative to vehicle-treated mice (p<0.05). In the transient transactivation assays, TBTCl suppressed T3 mediated transcriptional activity in a dose-dependent manner. In addition, TBTCl was found to decrease the expression of TR. The present study thus indicates that low concentrations of TBTCl suppress TR transcription by disrupting the physiological concentrations of T3/T4, followed by the recruitment of NCoR to TR, providing a novel insight into the thyroid hormone-disrupting effects of this chemical. Copyright © 2014 Elsevier Inc. All rights reserved.

Associations between Repeated Measures of Maternal Urinary Phthalate Metabolites and Thyroid Hormone Parameters during Pregnancy

PubMed Central

Johns, Lauren E.; Ferguson, Kelly K.; McElrath, Thomas F.; Mukherjee, Bhramar; Meeker, John D.

2016-01-01

Background: Maintaining thyroid homeostasis during pregnancy is essential for normal fetal growth and development. Growing evidence suggests that phthalates interfere with normal thyroid function. Few human studies have investigated the degree to which phthalates may affect thyroid hormone levels in particularly susceptible populations such as pregnant women. Objectives: We examined the associations between repeated measures of urinary phthalate metabolites and plasma thyroid hormone levels in samples collected at up to four time points per subject in pregnancy. Additionally, we investigated the potential windows of susceptibility to thyroid hormone disturbances related to study visit of sample collection. Methods: Data were obtained from pregnant women (n = 439) participating in a nested case–control study of preterm birth with 116 cases and 323 controls. We measured 9 phthalate metabolite concentrations in urine samples collected at up to four study visits per subject during pregnancy (median = 10, 18, 26, and 35 weeks of gestation, respectively). We also measured a panel of thyroid function markers in plasma collected at the same four time points per subject during pregnancy. Results: Although our results were generally null, in repeated measures analyses we observed that phthalate metabolites were largely inversely associated with thyrotropin and positively associated with free and total thyroid hormones. Cross-sectional analyses by study visit revealed that the magnitude and/or direction of these relationships varied by timing of exposure during gestation. Conclusions: These results support previous reports showing the potential for environmental phthalate exposure to alter circulating levels of thyroid hormones in pregnant women. Citation: Johns LE, Ferguson KK, McElrath TF, Mukherjee B, Meeker JD. 2016. Associations between repeated measures of maternal urinary phthalate metabolites and thyroid hormone parameters during pregnancy. Environ Health Perspect 124:1808–1815; http://dx.doi.org/10.1289/EHP170 PMID:27152641

THYROID HORMONE RECEPTOR BETA GENE MUTATION (P453A) IN A TURKISH FAMILY PRODUCING RESISTANCE TO THYROID HORMONE

PubMed Central

Bayraktaroglu, Taner; Noel, Janet; Mukaddes, Nahit Motavalli; Refetoff, Samuel

2018-01-01

Two members of a Turkish family, a mother and son, had thyroid function tests suggestive of resistance to thyroid hormone (RTH). The clinical presentation was, however, different. The mother (proposita) had palpitation, weakness, tiredness, nervousness, dry mouth and was misdiagnosed as having multinodular toxic goiter which was treated with antithyroid drugs and partial thyroidectomy. Her younger son had attention deficit hyperactivity disorder and primary encopresis, but normal intellectual quotient. Both had elevated serum iodothyronine levels with nonsuppressed thyrotropin. A mutation in one allele of the thyroid hormone receptor beta gene (P453A) was identified, providing a genetic confirmation for the diagnosis of RTH. PMID:18561095

Thyroid hormone regulates the expression of the sonic hedgehog signaling pathway in the embryonic and adult Mammalian brain.

PubMed

Desouza, Lynette A; Sathanoori, Malini; Kapoor, Richa; Rajadhyaksha, Neha; Gonzalez, Luis E; Kottmann, Andreas H; Tole, Shubha; Vaidya, Vidita A

2011-05-01

Thyroid hormone is important for development and plasticity in the immature and adult mammalian brain. Several thyroid hormone-responsive genes are regulated during specific developmental time windows, with relatively few influenced across the lifespan. We provide novel evidence that thyroid hormone regulates expression of the key developmental morphogen sonic hedgehog (Shh), and its coreceptors patched (Ptc) and smoothened (Smo), in the early embryonic and adult forebrain. Maternal hypo- and hyperthyroidism bidirectionally influenced Shh mRNA in embryonic forebrain signaling centers at stages before fetal thyroid hormone synthesis. Further, Smo and Ptc expression were significantly decreased in the forebrain of embryos derived from hypothyroid dams. Adult-onset thyroid hormone perturbations also regulated expression of the Shh pathway bidirectionally, with a significant induction of Shh, Ptc, and Smo after hyperthyroidism and a decline in Smo expression in the hypothyroid brain. Short-term T₃ administration resulted in a significant induction of cortical Shh mRNA expression and also enhanced reporter gene expression in Shh(+/LacZ) mice. Further, acute T₃ treatment of cortical neuronal cultures resulted in a rapid and significant increase in Shh mRNA, suggesting direct effects. Chromatin immunoprecipitation assays performed on adult neocortex indicated enhanced histone acetylation at the Shh promoter after acute T₃ administration, providing further support that Shh is a thyroid hormone-responsive gene. Our results indicate that maternal and adult-onset perturbations of euthyroid status cause robust and region-specific changes in the Shh pathway in the embryonic and adult forebrain, implicating Shh as a possible mechanistic link for specific neurodevelopmental effects of thyroid hormone.

Thyroid disease and the cardiovascular system.

PubMed

Danzi, Sara; Klein, Irwin

2014-06-01

Thyroid hormones, specifically triiodothyronine (T3), have significant effects on the heart and cardiovascular system. Hypothyroidism, hyperthyroidism, subclinical thyroid disease, and low T3 syndrome each cause cardiac and cardiovascular abnormalities through both genomic and nongenomic effects on cardiac myocytes and vascular smooth muscle cells. In compromised health, such as occurs in heart disease, alterations in thyroid hormone metabolism may further impair cardiac and cardiovascular function. Diagnosis and treatment of cardiac disease may benefit from including analysis of thyroid hormone status, including serum total T3 levels. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of recombinant human growth hormone in the treatment of dwarfism and relationship between IGF-1, IGFBP-3 and thyroid hormone

PubMed Central

Ren, Shanxiang; Nie, Yuxiang; Wang, Aihong

2016-01-01

The effects of recombinant human growth hormone (rhGH) in the treatment of dwarfism and the relationship between insulin-like growth factor (IGF)-1, IGF-binding protein (IGFBP)-3 and thyroid hormone were examined in the present study. For this purpose, 66 patients diagnosed with dwarfism were selected retrospectively, with 36 cases of growth hormone deficiency (GHD) and 30 cases of idiopathic short stature (ISS). The therapeutic dose of GHD 0.10 IU/kg·day and ISS 0.15 IU/kg·day were injected subcutaneously every night before sleep until adulthood. The average follow-up was 5 years, and the results were evaluated and measured every 3 months, including height, BA, secondary test of growth hormone (GH peak), IGF-1, IGFBP-3 and thyroid hormone (FT3, FT4 and TSH). After treatment, the height, BA, GH peak, IGF-A and IGFBP-3 of the GHD group were all increased, and the differences were statistically significant (P<0.05), while FT3, FT4 and TSH had no significant change (P<0.05). The height and BA increased and the differences were statistically significant (P<0.05). The indexes of the ISS group were not statistically significant (P>0.05). The results of the Pearson-related analysis suggested that GH peak of the GHD group, IGF-1 and IGFBP-3 were positively associated with height (P<0.05), and had no relationship with BA (P<0.05). None of the above indexes of the ISS group had an obvious correlation with height and BA (P>0.05). rhGH was effective for GHD and ISS, with the GHD effect being positively associated with the GH peak, IGF-1 and IGFBP-3. ISS had no obvious relationship with GH peak, IGF-1 and IGFBP-3 although other influencing factors may be involved. PMID:28105090

Effects of recombinant human growth hormone in the treatment of dwarfism and relationship between IGF-1, IGFBP-3 and thyroid hormone.

PubMed

Ren, Shanxiang; Nie, Yuxiang; Wang, Aihong

2016-12-01

The effects of recombinant human growth hormone (rhGH) in the treatment of dwarfism and the relationship between insulin-like growth factor (IGF)-1, IGF-binding protein (IGFBP)-3 and thyroid hormone were examined in the present study. For this purpose, 66 patients diagnosed with dwarfism were selected retrospectively, with 36 cases of growth hormone deficiency (GHD) and 30 cases of idiopathic short stature (ISS). The therapeutic dose of GHD 0.10 IU/kg·day and ISS 0.15 IU/kg·day were injected subcutaneously every night before sleep until adulthood. The average follow-up was 5 years, and the results were evaluated and measured every 3 months, including height, BA, secondary test of growth hormone (GH peak), IGF-1, IGFBP-3 and thyroid hormone (FT3, FT4 and TSH). After treatment, the height, BA, GH peak, IGF-A and IGFBP-3 of the GHD group were all increased, and the differences were statistically significant (P<0.05), while FT3, FT4 and TSH had no significant change (P<0.05). The height and BA increased and the differences were statistically significant (P<0.05). The indexes of the ISS group were not statistically significant (P>0.05). The results of the Pearson-related analysis suggested that GH peak of the GHD group, IGF-1 and IGFBP-3 were positively associated with height (P<0.05), and had no relationship with BA (P<0.05). None of the above indexes of the ISS group had an obvious correlation with height and BA (P>0.05). rhGH was effective for GHD and ISS, with the GHD effect being positively associated with the GH peak, IGF-1 and IGFBP-3. ISS had no obvious relationship with GH peak, IGF-1 and IGFBP-3 although other influencing factors may be involved.

Selenium glutathione peroxidase activities and thyroid functions in human individuals

NASA Astrophysics Data System (ADS)

Bellisola, G.; Calza Contin, M.; Ceccato, D.; Cinque, G.; Francia, G.; Galassini, S.; Liu, N. Q.; Lo Cascio, C.; Moschini, G.; Sussi, P. L.

1996-04-01

At least two enzymes are involved in metabolism of thyroid hormones. GSHPx protects thyrocyte from high H 2O 2 levels that are required for iodination of prohormones to form T4 in thyroid cell. Type I iodothyronine 5'-deiodinase (5'-D) catalyzes the deiodination of L-thyroxin (T4) to the biologically active thyroid hormone 3,3'-5-triiodothyronine (T 3) in liver, in kidney and in thyroid tissues. Circulating thyroid hormones, plasma Se levels, GSHPx activities in platelets and in plasma were investigated in 29 human individuals with increased thyroid mass. PIXE was applied to measure Se in 1 ml of plasma because we supposed patients were in a marginal carential status for Se. Plasma Se concentrations were compared with those of normal individuals. Correlation studies between plasma Se level and both GSHPx activities were carried out as well as between platelets and plasma GSHPx activities to verify the hypothesis of a marginal Se deficiency in patients. Significance of circulating thyroid hormones levels will be discussed.

Decreased alertness

MedlinePlus

... involves the brain Liver failure Thyroid conditions that cause low thyroid hormone levels or very high thyroid hormone levels Brain disorders or injury, such as: Dementia or Alzheimer disease Head trauma Seizure Stroke Infections that affect ...

Hyperthyroidism and the Heart.

PubMed

Osuna, Patricia Mejia; Udovcic, Maja; Sharma, Morali D

2017-01-01

Thyroid hormones have a significant impact on cardiac function and structure. Excess thyroid hormone affects cardiovascular hemodynamics, leading to high-output heart failure and, in late stages, dilated cardiomyopathy. In this review, we discuss how hyperthyroidism affects cardiovascular pathophysiology and molecular mechanisms and examine the complications caused by excess thyroid hormone, such as heart failure and atrial fibrillation.

Adipocyte-myocyte crosstalk in skeletal muscle insulin resistance; is there a role for thyroid hormone?

PubMed

Havekes, Bas; Sauerwein, Hans P

2010-11-01

To review original research studies and reviews that present data on adipocyte-myocyte crosstalk in the development of skeletal muscle insulin resistance with a specific focus on thyroid hormone. Adipose tissue communicates with skeletal muscle not only through free fatty acids but also through secretion of various products called adipokines. Adipokines came out as governors of insulin sensitivity and are deregulated in obesity. In addition to well known leptin, adiponectin, interleukin-6 and tumor necrosis factor-alpha, newer adipokines like retinol-binding protein 4 have been associated with insulin resistance. There is mounting evidence that not only adipose tissue but also skeletal muscle produces and secretes biologically active proteins or 'myokines' that facilitate metabolic crosstalk between organ systems. In recent years, increased expression of myostatin, a secreted anabolic inhibitor of muscle growth and development, has been associated with obesity and insulin resistance. Both hypothyroidism and hyperthyroidism affect insulin sensitivity in multiple ways that might overlap adipocyte-myocyte crosstalk. Recent studies have provided new insights in effects of processing of the parent hormone T4 to the active T3 at the level of the skeletal muscle. Adipocyte-myocyte crosstalk is an important modulator in the development of skeletal muscle insulin resistance. Thyroid disorders are very common and may have detrimental effects on skeletal muscle insulin resistance, potentially by interacting with adipocyte-myocyte crosstalk.

Partial thyrocyte-specific Gαs deficiency leads to rapid-onset hypothyroidism, hyperplasia, and papillary thyroid carcinoma-like lesions in mice.

PubMed

Patyra, Konrad; Jaeschke, Holger; Löf, Christoffer; Jännäri, Meeri; Ruohonen, Suvi T; Undeutsch, Henriette; Khalil, Moosa; Kero, Andreina; Poutanen, Matti; Toppari, Jorma; Chen, Min; Weinstein, Lee S; Paschke, Ralf; Kero, Jukka

2018-05-25

Thyroid function is controlled by thyroid-stimulating hormone (TSH), which binds to its G protein-coupled receptor [thyroid-stimulating hormone receptor (TSHR)] on thyrocytes. TSHR can potentially couple to all G protein families, but it mainly activates the G s - and G q/11 -mediated signaling cascades. To date, there is a knowledge gap concerning the role of the individual G protein cascades in thyroid pathophysiology. Here, we demonstrate that the thyrocyte-specific deletion of G s -protein α subunit (Gα s ) in adult mice [tamoxifen-inducible G s protein α subunit deficient (iTGα s KO) mice] rapidly impairs thyrocyte function and leads to hypothyroidism. Consequently, iTGα s KO mice show reduced food intake and activity. However, body weight and the amount of white adipose tissue were decreased only in male iTGα s KO mice. Unexpectedly, hyperplastic follicles and papillary thyroid cancer-like tumor lesions with increased proliferation and slightly increased phospho-ERK1/2 staining were found in iTGα s KO mice at an older age. These tumors developed from nonrecombined thyrocytes still expressing Gα s in the presence of highly elevated serum TSH. In summary, we report that partial thyrocyte-specific Gα s deletion leads to hypothyroidism but also to tumor development in thyrocytes with remaining Gα s expression. Thus, these mice are a novel model to elucidate the pathophysiological consequences of hypothyroidism and TSHR/G s /cAMP-mediated tumorigenesis.-Patyra, K., Jaeschke, H., Löf, C., Jännäri, M., Ruohonen, S. T., Undeutsch, H., Khalil, M., Kero, A., Poutanen, M., Toppari, J., Chen, M., Weinstein, L. S., Paschke, R., Kero, J. Partial thyrocyte-specific Gα s deficiency leads to rapid-onset hypothyroidism, hyperplasia, and papillary thyroid carcinoma-like lesions in mice.

Implication from thyroid function decreasing during chemotherapy in breast cancer patients: chemosensitization role of triiodothyronine

PubMed Central

2013-01-01

Background Thyroid hormones have been shown to regulate breast cancer cells growth, the absence or reduction of thyroid hormones in cells could provoke a proliferation arrest in G0-G1 or weak mitochondrial activity, which makes cells insensitive to therapies for cancers through transforming into low metabolism status. This biological phenomenon may help explain why treatment efficacy and prognosis vary among breast cancer patients having hypothyroid, hyperthyroid and normal function. Nevertheless, the abnormal thyroid function in breast cancer patients has been considered being mainly caused by thyroid diseases, few studied influence of chemotherapy on thyroid function and whether its alteration during chemotherapy can influence the respose to chemotherapy is still unclear. So, we aimed to find the alterations of thyroid function and non-thyroidal illness syndrome (NTIS) prevalence druing chemotherapy in breast cancer patients, and investigate the influence of thyroid hormones on chemotherapeutic efficacy. Methods Thyroid hormones and NTIS prevalence at initial diagnosis and during chemotherapy were analyzed in 685 breast diseases patients (369 breast cancer, 316 breast benign lesions). The influence of thyroid hormones on chemotherapeutic efficacy was evaluated by chemosensitization test, to compare chemotherapeutic efficacy between breast cancer cells with chemotherapeutics plus triiodothyronine (T3) and chemotherapeutics only. Results In breast cancer, NTIS prevalence at the initial diagnosis was higher and increased during chemotherapy, but declined before the next chemotherapeutic course. Thyroid hormones decreased signigicantly during chemotherapy. T3 can enhance the chemosensitivity of MCF-7 to 5-Fu and taxol, with progression from G0-G1 phase to S phase. The similar chemosensitization role of T3 were found in MDA-MB-231. We compared chemotherapeutic efficacy among groups with different usage modes of T3, finding pretreatment with lower dose of T3, using higher dose of T3 together with 5-Fu or during chemotherapy with 5-Fu were all available to achieve chemosensitization, but pretreatment with lower dose of T3 until the end of chemotherapy may be a safer and more efficient therapy. Conclusions Taken together, thyroid hormones decreasing during chemotherapy was found in lots of breast cancer patients. On the other hand, thyroid hormones can enhance the chemotherapeutic efficacy through gatherring tumor cells in actively proliferating stage, which may provide a new adjuvant therapy for breast cancer in furture, especially for those have hypothyroidism during chemotherapy. PMID:23829347

Asymptomatic hyperthyroidism in older adults: is it a distinct clinical and laboratory entity?

PubMed

Mooradian, Arshag D

2008-01-01

Hyperthyroidism is the result of increased serum free thyroid hormone levels and is associated with a well recognized set of clinical signs and symptoms. However, older patients who develop hyperthyroidism tend to have fewer hyperadrenergic signs and an increased incidence of weight loss, cardiac arrhythmias and, occasionally, apathetic mood. This article highlights the paucity of clinical signs and symptoms of hyperthyroidism in older people and reviews the potential biochemical changes in thyroid hormone physiology that may account for an altered clinical presentation in older people with hyperthyroidism. First, a brief vignette from our own clinical practice is described to highlight an unusual presentation of hyperthyroidism in an older woman. The subject is then reviewed on the basis of relevant articles identified through a MEDLINE search of the English literature, using the key words 'hyperthyroidism' and 'aging'. The available evidence indicates that the clinical syndrome of asymptomatic hyperthyroidism in older adults appears to be distinct from the more widely recognized syndromes of apathetic hyperthyroidism or thyroid hormone resistance. Age-related changes in thyroid hormone economy and reduced cellular uptake of thyroid hormone as well as changes in thyroid hormone regulation of gene expression may account for reduced manifestations of hyperthyroidism in older adults. Thus, in addition to the well known changes in thyroid gland anatomy and function with aging, there may be an age-related resistance to thyroid hormone action. Asymptomatic hyperthyroidism may well be a syndrome that is currently under-diagnosed.

A case of thyroid storm with multiple organ failure effectively treated with plasma exchange.

PubMed

Sasaki, Kazuki; Yoshida, Akira; Nakata, Yukiko; Mizote, Isamu; Sakata, Yasushi; Komuro, Issei

2011-01-01

We describe a 48-year-old man with thyroid storm presenting with heart failure. He presented severely impaired left ventricular wall motion and a marked increase in the liver enzymes. He developed disseminated intravascular coagulation on day 2. Due to elevated serum thyroid hormone level, anti-thyroid hormone receptor antibody positivity, and his clinical symptoms, he was diagnosed as thyroid storm due to untreated Graves' disease. His condition did not improve even after 6 days of conventional therapy including steroids. After therapeutic plasma exchange was carried out, his thyroid hormone level decreased markedly. Consequently, his condition recovered gradually, and he was discharged at day 43.

Fluoride caused thyroid endocrine disruption in male zebrafish (Danio rerio).

PubMed

Jianjie, Chen; Wenjuan, Xue; Jinling, Cao; Jie, Song; Ruhui, Jia; Meiyan, Li

2016-02-01

Excessive fluoride in natural water ecosystem has the potential to detrimentally affect thyroid endocrine system, but little is known of such effects or underlying mechanisms in fish. In the present study, we evaluated the effects of fluoride on growth performance, thyroid histopathology, thyroid hormone levels, and gene expressions in the HPT axis in male zebrafish (Danio rerio) exposed to different determined concentrations of 0.1, 0.9, 2.0 and 4.1 M of fluoride to investigate the effects of fluoride on thyroid endocrine system and the potential toxic mechanisms caused by fluoride. The results indicated that the growth of the male zebrafish used in the experiments was significantly inhibited, the thyroid microtrastructure was changed, and the levels of T3 and T4 were disturbed in fluoride-exposed male fish. In addition, the expressional profiles of genes in HPT axis displayed alteration. The expressions of all studied genes were significantly increased in all fluoride-exposed male fish after exposure for 45 days. The transcriptional levels of corticotrophin-releasing hormone (CRH), thyroid-stimulating hormone (TSH), thyroglobulin (TG), sodium iodide symporter (NIS), iodothyronine I (DIO1), and thyroid hormone receptor alpha (TRα) were also elevated in all fluoride-exposed male fish after 90 days of exposure, while the inconsistent expressions were found in the mRNA of iodothyronineⅡ (DIO2), UDP glucuronosyltransferase 1 family a, b (UGT1ab), transthyretin (TTR), and thyroid hormone receptor beta (TRβ). These results demonstrated that fluoride could notably inhibit the growth of zebrafish, and significantly affect thyroid endocrine system by changing the microtrastructure of thyroid, altering thyroid hormone levels and endocrine-related gene expressions in male zebrafish. All above indicated that fluoride could pose a great threat to thyroid endocrine system, thus detrimentally affected the normal function of thyroid of male zebrafish. Copyright © 2015. Published by Elsevier B.V.

Thyroid dysfunction and thyroid autoimmunity in euthyroid women in achieving fertility.

PubMed

Medenica, S; Nedeljkovic, O; Radojevic, N; Stojkovic, M; Trbojevic, B; Pajovic, B

2015-01-01

Thyroid disease is the second most common endocrine condition in women of childbearing age. Thyroid hormones are involved in control of menstrual cycle and in achieving fertility affecting the actions of follicle-stimulating hormone and luteinizing hormone on steroid biosynthesis by specific triiodothyronine sites on oocytes; therefore, affect all aspects of reproduction. It remains controversial if pregnant women should be screened for thyroid dysfunction. Purpose of this review was to examine recent studies on the assessment of thyroid dysfunction in pregnancy, its treatment and newly perspective of thyroid autoimmunity in pregnant euthyroid women in achieving fertility. An electronic search was conducted using the internet medical databases: Medline/PubMed, EMBASE, EBSCO, and the Cochrane library. Thyroid gland faces great challenge in pregnancy when many hormonal changes occur. Precondition for normal follicular development and ovulation is pulsate gonadothropin realizing hormone secretion. Thyroid dysfunction in pregnancy is classified as forms of hypothyroidism (positivity of thyroid autoantibody, isolated hypothyroidism, and subclinical or overt hypothyroidism), hyperthyroidism, and autoimmune disease, but also thyroid nodules and cancer, iodine insufficiency and postpartum thyroiditis. These conditions can cause adverse effects on mother and fetus including pregnancy loss, gestational hypertension, or pre-eclampsia, pre-term delivery, low birth weight, placental abruption and postpartum hemorrhage. There is an evidence that thyroid autoimmunity, in thyroid dysfunction adversely affects conception and pregnancy outcomes, but it is unclear what impact has isolated eumetabolic thyroid autoimmunity in achieving fertility, especially in women undergoing in vitro fertilization. Treatment of euthyroid pregnant women with positive thyroid peroxides antibodies is still controverse, but not few studies show that levothyroxine substitution is able to lower the chance of miscarriage and premature delivery. Further randomized trials are needed to expand our knowledge of physiologic changes in thyroid function during the pregnancy and to reveal mechanisms by which thyroid autoimmunity in euthyroid women affect fertility, especially the success of assisted reproductive technology in achieving the same and validity of levothyroxine administration in thyroid autoimmunity positive women.

Clear cell variant of follicular thyroid carcinoma with normal thyroid-stimulating hormone value: a case report

PubMed Central

2014-01-01

Introduction Clear cell carcinomas of the thyroid gland with normal thyroid-stimulating hormone value are very rare, but clear cell changes are described in most reported cases of thyroidal lesions. Case presentation In this report, we describe the case of a 50-year-old Caucasian woman with a normal thyroid-stimulating hormone level who underwent surgery to treat a multi-nodular goiter. The pathology was a clear cell variant of follicular thyroid carcinoma. The tumor was 1cm in diameter and consisted of pure clear cells. Conclusion Clear cell variants of follicular thyroid carcinoma are rarely seen, especially it is misdiagnosed with metastatic renal cell carcinoma. In this report, we describe the case of a patient with a clear cell variant of follicular thyroid carcinoma with an interesting pathology. PMID:24884725

PCBs Alter Dopamine Mediated Function in Aging Workers

DTIC Science & Technology

2007-01-01

Thyroid Hormone Function Analysis of serum samples collected for thyroid hormone function (T3, T4, free T3, free T4, and TSH levels) has been conducted by...Thyroid Hormone Measure Mean sem Mean sem TSH 2.06 0.13 2.55 0.36 T4 7.94 0.18 8.72 0.22 Free T4 1.23 0.02 1.22 0.03 T3 133 3.05 122 2.74...FreeT3 5.31 0.08 4.56 0.08 TSH = Thyroid Stimulating Hormone T4 = Thyroxine T3 = 3,5,3-Triidothyronine Investigators Meetings and

Clinical associations of maternal thyroid function with foetal brain development: Epidemiological interpretation and overview of available evidence.

PubMed

Korevaar, Tim I M; Tiemeier, Henning; Peeters, Robin P

2018-04-24

Thyroid hormone is an important regulator of early brain development, particularly during early stages of gestation during which foetal thyroid hormone availability depends on the maternal transfer of thyroid hormones. There is a wide range of experimental studies showing that low maternal thyroid hormone availability is associated with suboptimal brain development parameters. While few clinical studies have shown that overt maternal hypothyroidism is associated with lower child IQ, the question whether more subclinical changes in maternal thyroid function could also lead to suboptimal foetal brain development. In this review, we put the latter studies in perspective and discuss their interpretation from an epidemiological and clinical perspective. Furthermore, we extend this discussion to also include future perspective and identify important knowledge gaps in the field. © 2018 John Wiley & Sons Ltd.

Follow-up of congenital heart disease patients with subclinical hypothyroidism.

PubMed

Martínez-Quintana, Efrén; Rodríguez-González, Fayna

2015-08-01

Subclinical hypothyroidism or mild thyroid failure is a common problem in patients without known thyroid disease. Demographic and analytical data were collected in 309, of which 181 were male and 128 were female, congenital heart disease (CHD) patients. CHD patients with thyroid-stimulating hormone above 5.5 mIU/L were also followed up from an analytical point of view to determine changes in serum glucose, cholesterol, N-terminal pro b-type natriuretic peptide, and C-reactive protein concentrations. Of the CHD patients, 35 (11.3%) showed thyroid-stimulating hormone concentration above 5.5 mIU/L. Of them, 27 were followed up during 2.4±1.2 years - 10 were under thyroid hormone replacement treatment, and 17 were not. Of the 27 patients (25.9%), 7 with subclinical hypothyroidism had positive anti-thyroid peroxidase, and 3 of them (42.8%) with positive anti-thyroid peroxidase had Down syndrome. Down syndrome and hypoxaemic CHD patients showed higher thyroid-stimulating hormone concentrations than the rest of the congenital patients (p<0.001). No significant differences were observed in serum thyroxine, creatinine, uric acid, lipids, C-reactive protein, or N-terminal pro b-type natriuretic peptide concentrations before and after the follow-up in those CHD patients with thyroid-stimulating hormone above 5.5 mIU/L whether or not they received levothyroxine therapy. CHD patients with subclinical hypothyroidism showed no significant changes in serum thyroxine, cholesterol, C-reactive protein, or N-terminal pro b-type natriuretic peptide concentrations whether or not they were treated with thyroid hormone replacement therapy.

Thyroid hormone action on intermediary metabolism. Part I: respiration, thermogenesis and carbohydrate metabolism.

PubMed

Müller, M J; Seitz, H J

1984-01-02

The effect of thyroid hormones on mitochondrial respiration are summarized: T3 directly stimulates mitochondrial respiration and the synthesis of adenosine 5'-triphosphate (ATP). Cytosolic ATP availability is increased by a thyroid hormone-induced increase in adenine nucleotide translocation across the mitochondrial membrane; the steady state ATP concentration and the cytosolic ATP/adenosine 5'-diphosphate (ADP) ratio is even decreased in hyperthyroid tissues because of the simultaneous stimulation of the synthesis and consumption of ATP. With regard to the thyroid hormone-induced energy wasting processes, heart work, intra- and interorgan futile cycling and Na+/K+-ATPase are involved to varying degrees. As a consequence of the thyroid hormone-induced hydrolysis of ATP, thermogenesis is increased in hyper- and decreased in hypothyroidism. Despite an increased rate of glucose utilization, clinical and experimental hyperthyroidism is often characterized by an abnormal oral glucose tolerance test. This finding is due to the thyroid hormone-induced increase in intestinal glucose absorption as well as the still enhanced endogenous glucose production in the liver. Hypothyroid patients show a reduced glucose tolerance test because of a decrease in intestinal glucose absorption and a sometimes reduced glucose turnover. The thyroid hormone-induced alterations in glucose metabolism are most probably not due to alterations in serum insulin levels and/or to a peripheral insulin resistance at the receptor level.

Efficacy of a food supplement in patients with hashimoto thyroiditis.

PubMed

Nordio, M; Basciani, S

2015-01-01

Thyroid inflammation has been commonly seen in recent decades, due to a series of factors and is considered as the most frequent thyroid illness. It is characterized by some distinctive traits, which include morphological and hormonal modifications, often in association with an elevated anti-thyroid autoantibody title. The aim of the therapy is to improve symptoms as fast as possible, treating inflammation and subsequent hypothyroidism, when present. Therefore, we evaluated the efficacy of a Food Supplement (FS) containing enzymes which is commonly used in various inflammatory processes and is able to modulate immune reactions during inflammation in a very rapid and efficacious way. An open, controlled study was then designed and 45 patients with Hashimoto thyroiditis were enrolled and divided into 3 groups (FS alone; thyroid hormones alone; FS plus thyroid hormones). Blood, morphological and subjective parameters were considered. The results obtained indicate that the FS used in our study is efficacious and safe when used alone and/or in combination with thyroid hormones in the treatment of autoimmune thyroiditis, as documented by the improvement of the majority of the parameters considered. The efficacy was considered faster than thyroid hormones alone as far as subjective symptomatology is considered. In conclusion, the use of the food supplement evaluated herein during inflammation may be considered an additional tool in clinicians’ hands, when facing patients with autoimmune thyroiditis, especially in presence of subjective symptomatology, in order to rapidly alleviate it.

BRAIN, LIVER AND THYROID BIOMARKERS REFLECT ENHANCED SENSITIVITY OF THE DEVELOPING RAT TO THYROID HORMONE DEPLETION.

EPA Science Inventory

Many developmental events are regulated at least in part by thyroid hormones. It was hypothesized that tissue biomarkers of thyroid status would be more accurate predictors of neurotoxicity than serum biomarkers in rats treated with the goitrogen propylthiouracil (PTU). Over seve...

Negative Feedback Control of Pituitary Thyroid-stimulating Hormone Synthesis and Secretion by Thyroid Hormones during Metamorphosis in Xenopus laevis

EPA Science Inventory

A basic understanding of the endocrinology of the hypothalamic-pituitary-thyroid (HPT) axis of anuran larvae is necessary for predicting the consequences of HPT perturbation by thyroid-disrupting chemicals (TDCs) on the whole organism. This project examined negative feedback con...

Prenatal and Neonatal Thyroid Stimulating Hormone Levels and Autism Spectrum Disorders

ERIC Educational Resources Information Center

Yau, Vincent M.; Lutsky, Marta; Yoshida, Cathleen K.; Lasley, Bill; Kharrazi, Martin; Windham, Gayle; Gee, Nancy; Croen, Lisa A.

2015-01-01

Thyroid hormones are critical for normal brain development. This study examined autism spectrum disorders (ASD) and thyroid stimulating hormone (TSH) levels measured in mid-pregnancy maternal serum and infant blood after birth. Three groups of children born in Orange County, CA in 2000-2001 were identified: ASD (n = 78), developmental delay…

Hyperthyroidism and the Heart

PubMed Central

Osuna, Patricia Mejia; Udovcic, Maja; Sharma, Morali D.

2017-01-01

Thyroid hormones have a significant impact on cardiac function and structure. Excess thyroid hormone affects cardiovascular hemodynamics, leading to high-output heart failure and, in late stages, dilated cardiomyopathy. In this review, we discuss how hyperthyroidism affects cardiovascular pathophysiology and molecular mechanisms and examine the complications caused by excess thyroid hormone, such as heart failure and atrial fibrillation. PMID:28740583

Unexplained high thyroid stimulating hormone: a "BIG" problem.

PubMed

Mendoza, Heidi; Connacher, Alan; Srivastava, Rajeev

2009-01-01

Macro-hormones and macro-enzymes are high molecular weight conjugates of hormones or enzymes, respectively, often with immunoglobulins. These are referred to as macromolecular complexes, and may cause artefactually elevated biochemical tests results. Macro enzymes of the most commonly measured serum enzymes have been identified and are recognised as a source of elevated measurements that may cause diagnostic confusion; macro-creatine kinase and macro-amylase are the two better known macro-enzymes in clinical practice. Literature on macro-hormones is largely restricted to macro-prolactin. We present a case of a clinically euthyroid patient, who had persistently elevated thyroid stimulating hormone (TSH) but free thyroxine within the reference limits. She underwent repeated thyroid investigations and thyroid hormone interference studies, until macro-TSH was identified as the most likely cause of unexplained elevated TSH. Following the identification and characterisation of this biochemical abnormality, she is no longer subject to repeated blood tests for assessment of thyroid function; the patient currently remains clinically euthyroid.

Thyroid Hormone Regulates the Expression of the Sonic Hedgehog Signaling Pathway in the Embryonic and Adult Mammalian Brain

PubMed Central

Desouza, Lynette A.; Sathanoori, Malini; Kapoor, Richa; Rajadhyaksha, Neha; Gonzalez, Luis E.; Kottmann, Andreas H.; Tole, Shubha

2011-01-01

Thyroid hormone is important for development and plasticity in the immature and adult mammalian brain. Several thyroid hormone-responsive genes are regulated during specific developmental time windows, with relatively few influenced across the lifespan. We provide novel evidence that thyroid hormone regulates expression of the key developmental morphogen sonic hedgehog (Shh), and its coreceptors patched (Ptc) and smoothened (Smo), in the early embryonic and adult forebrain. Maternal hypo- and hyperthyroidism bidirectionally influenced Shh mRNA in embryonic forebrain signaling centers at stages before fetal thyroid hormone synthesis. Further, Smo and Ptc expression were significantly decreased in the forebrain of embryos derived from hypothyroid dams. Adult-onset thyroid hormone perturbations also regulated expression of the Shh pathway bidirectionally, with a significant induction of Shh, Ptc, and Smo after hyperthyroidism and a decline in Smo expression in the hypothyroid brain. Short-term T3 administration resulted in a significant induction of cortical Shh mRNA expression and also enhanced reporter gene expression in Shh+/LacZ mice. Further, acute T3 treatment of cortical neuronal cultures resulted in a rapid and significant increase in Shh mRNA, suggesting direct effects. Chromatin immunoprecipitation assays performed on adult neocortex indicated enhanced histone acetylation at the Shh promoter after acute T3 administration, providing further support that Shh is a thyroid hormone-responsive gene. Our results indicate that maternal and adult-onset perturbations of euthyroid status cause robust and region-specific changes in the Shh pathway in the embryonic and adult forebrain, implicating Shh as a possible mechanistic link for specific neurodevelopmental effects of thyroid hormone. PMID:21363934

A randomized, open-label, crossover study comparing the effects of oral versus transdermal estrogen therapy on serum androgens, thyroid hormones, and adrenal hormones in naturally menopausal women.

PubMed

Shifren, Jan L; Desindes, Sophie; McIlwain, Marilyn; Doros, Gheorghe; Mazer, Norman A

2007-01-01

To compare the changes induced by oral versus transdermal estrogen therapy on the total and free serum concentrations of testosterone (T), thyroxine (T4), and cortisol (C) and the concentrations of their serum binding globulins sex hormone-binding globulin, thyroxine-binding globulin, and cortisol-binding globulin in naturally menopausal women. Randomized, open-label, crossover. Interventions included a 6-week withdrawal from previous hormone therapy (baseline), followed in randomized order by 12 weeks of oral conjugated equine estrogens (CEE) (0.625 mg/d) and 12 weeks of transdermal estradiol (TD E2) (0.05 mg/d), with oral micronized progesterone (100 mg/d) given continuously during both transdermal estrogen therapy regimens. Twenty-seven women were enrolled in the study, and 25 completed both treatment periods. The mean(SD) percentage changes from baseline of sex hormone-binding globulin, total T, and free T with oral CEE were +132.1% (74.5%), +16.4% (43.8%), and -32.7% (25.9%), respectively, versus +12.0% (25.1%), +1.2% (43.7%), and +1.0% (45.0%) with TD E2. The mean (SD) percentage changes of thyroxine-binding globulin, total T4, and free T4 with oral CEE were +39.9% (20.1%), +28.4% (29.2%), and -10.4% (22.3%), respectively, versus +0.4% (11.1%), -0.7% (16.5%), and +0.2% (26.6%) with TD E2. The mean (SD) percentage changes of cortisol-binding globulin, total C, and free C with oral CEE were +18.0% (19.5%), +29.2% (46.3%), and +50.4% (126.5%), respectively, versus -2.2% (11.3%), -6.7% (30.8%), and +1.8% (77.1%) with TD E2. Concentrations of all hormones and binding globulins were significantly different (P < or = 0.003) during administration of oral versus transdermal estrogen therapy, except for free T4 and free C. Compared with oral CEE, TD E2 exerts minimal effects on the total and free concentrations of T, T4, and C and their binding proteins.

Prediction of binding affinity and efficacy of thyroid hormone receptor ligands using QSAR and structure based modeling methods

PubMed Central

Politi, Regina; Rusyn, Ivan; Tropsha, Alexander

2016-01-01

The thyroid hormone receptor (THR) is an important member of the nuclear receptor family that can be activated by endocrine disrupting chemicals (EDC). Quantitative Structure-Activity Relationship (QSAR) models have been developed to facilitate the prioritization of THR-mediated EDC for the experimental validation. The largest database of binding affinities available at the time of the study for ligand binding domain (LBD) of THRβ was assembled to generate both continuous and classification QSAR models with an external accuracy of R2=0.55 and CCR=0.76, respectively. In addition, for the first time a QSAR model was developed to predict binding affinities of antagonists inhibiting the interaction of coactivators with the AF-2 domain of THRβ (R2=0.70). Furthermore, molecular docking studies were performed for a set of THRβ ligands (57 agonists and 15 antagonists of LBD, 210 antagonists of the AF-2 domain, supplemented by putative decoys/non-binders) using several THRβ structures retrieved from the Protein Data Bank. We found that two agonist-bound THRβ conformations could effectively discriminate their corresponding ligands from presumed non-binders. Moreover, one of the agonist conformations could discriminate agonists from antagonists. Finally, we have conducted virtual screening of a chemical library compiled by the EPA as part of the Tox21 program to identify potential THRβ-mediated EDCs using both QSAR models and docking. We concluded that the library is unlikely to have any EDC that would bind to the THRβ. Models developed in this study can be employed either to identify environmental chemicals interacting with the THR or, conversely, to eliminate the THR-mediated mechanism of action for chemicals of concern. PMID:25058446

Optimized FPGA Implementation of the Thyroid Hormone Secretion Mechanism Using CAD Tools.

PubMed

Alghazo, Jaafar M

2017-02-01

The goal of this paper is to implement the secretion mechanism of the Thyroid Hormone (TH) based on bio-mathematical differential eqs. (DE) on an FPGA chip. Hardware Descriptive Language (HDL) is used to develop a behavioral model of the mechanism derived from the DE. The Thyroid Hormone secretion mechanism is simulated with the interaction of the related stimulating and inhibiting hormones. Synthesis of the simulation is done with the aid of CAD tools and downloaded on a Field Programmable Gate Arrays (FPGAs) Chip. The chip output shows identical behavior to that of the designed algorithm through simulation. It is concluded that the chip mimics the Thyroid Hormone secretion mechanism. The chip, operating in real-time, is computer-independent stand-alone system.

Effects of thyroid hormone manipulation on pre-nuptial molt, luteinizing hormone and testicular growth in male white-crowned sparrows (Zonotrichia leuchophrys gambelii).

PubMed

Pérez, Jonathan H; Meddle, Simone L; Wingfield, John C; Ramenofsky, Marilyn

2018-01-01

Most seasonal species rely on the annual change in day length as the primary cue to appropriately time major spring events such as pre-nuptial molt and breeding. Thyroid hormones are thought to be involved in the regulation of both of these spring life history stages. Here we investigated the effects of chemical inhibition of thyroid hormone production using methimazole, subsequently coupled with either triiodothyronine (T3) or thyroxine (T4) replacement, on the photostimulation of pre-nuptial molt and breeding in Gambel's white-crowned sparrows (Zonotrichia leuchophrys gambelii). Suppression of thyroid hormones completely prevented pre-nuptial molt, while both T3 and T4 treatment restored normal patterns of molt in thyroid hormone-suppressed birds. Testicular recrudescence was blocked by methimazole, and restored by T4 but not T3, in contrast to previous findings demonstrating central action of T3 in the photostimulation of breeding. Methimazole and replacement treatments elevated plasma luteinizing hormone levels compared to controls. These data are partially consistent with existing theories on the role of thyroid hormones in the photostimulation of breeding, while highlighting the possibility of additional feedback pathways. Thus we suggest that regulation of the hypothalamic pituitary gonad axis that controls breeding may be more complex than previously considered. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

IODIDE DEFICIENCY, THYROID HORMONES, AND NEURODEVELOPMENT

EPA Science Inventory

ABSTRACT BODY: Iodide is an essential nutrient for thyroid hormone synthesis. Severe iodide insufficiency during early development is associated with cognitive deficits. Environmental contaminants can perturb the thyroid axis and this perturbation may be more acute under conditio...

Heterodimers of Retinoic Acid Receptors and Thyroid Hormone Receptors Display Unique Combinatorial Regulatory Properties

PubMed Central

Lee, Sangho; Privalsky, Martin L.

2009-01-01

Nuclear receptors are ligand-regulated transcription factors that regulate key aspects of metazoan development, differentiation, and homeostasis. Nuclear receptors recognize target genes by binding to specific DNA recognition sequences, denoted hormone response elements (HREs). Many nuclear receptors can recognize HREs as either homodimers or heterodimers. Retinoid X receptors (RXRs), in particular, serve as important heterodimer partners for many other nuclear receptors, including thyroid hormone receptors (TRs), and RXR/TR heterodimers have been proposed to be the primary mediators of target gene regulation by T3 hormone. Here, we report that the retinoic acid receptors (RARs), a distinct class of nuclear receptors, are also efficient heterodimer partners for TRs. These RAR/TR heterodimers form with similar affinities as RXR/TR heterodimers on an assortment of consensus and natural HREs, and preferentially assemble with the RAR partner 5′ of the TR moiety. The corepressor and coactivator recruitment properties of these RAR/TR heterodimers and their transcriptional activities in vivo are distinct from those observed with the corresponding RXR heterodimers. Our studies indicate that RXRs are not unique in their ability to partner with TRs, and that RARs can also serve as robust heterodimer partners and combinatorial regulators of T3-modulated gene expression. PMID:15650024

Thyroid hormones and female reproduction.

PubMed

Silva, Juneo F; Ocarino, Natália M; Serakides, Rogéria

2018-05-14

Thyroid hormones are vital for the proper functioning of the female reproductive system, since they modulate the metabolism and development of ovarian, uterine and placental tissues. Therefore, hypo- and hyperthyroidism may result in subfertility or infertility in both women and animals. Other well-documented sequelae of maternal thyroid dysfunctions include menstrual/estral irregularity, anovulation, abortion, preterm delivery, preeclampsia, intrauterine growth restriction, postpartum thyroiditis, and mental retardation in children. Several studies have been carried out involving prospective and retrospective studies of women with thyroid dysfunction, as well as in vivo and in vitro assays of hypo- and hyperthyroidism using experimental animal models and/or ovarian, uterine and placental cell culture. These studies have sought to elucidate the mechanisms by which thyroid hormones influence reproduction to better understand the physiology of the reproductive system and to provide better therapeutic tools for reproductive dysfunctions that originate from thyroid dysfunctions. Therefore, this review aims to summarize and update the available information related to the role of thyroid hormones in the morphophysiology of the ovary, uterus and placenta in women and animals and the effects of hypo- and hyperthyroidism on the female reproductive system.

Thyroid hormone increases fibroblast growth factor receptor expression and disrupts cell mechanics in the developing organ of corti

PubMed Central

2013-01-01

Background Thyroid hormones regulate growth and development. However, the molecular mechanisms by which thyroid hormone regulates cell structural development are not fully understood. The mammalian cochlea is an intriguing system to examine these mechanisms, as cellular structure plays a key role in tissue development, and thyroid hormone is required for the maturation of the cochlea in the first postnatal week. Results In hypothyroid conditions, we found disruptions in sensory outer hair cell morphology and fewer microtubules in non-sensory supporting pillar cells. To test the functional consequences of these cytoskeletal defects on cell mechanics, we combined atomic force microscopy with live cell imaging. Hypothyroidism stiffened outer hair cells and supporting pillar cells, but pillar cells ultimately showed reduced cell stiffness, in part from a lack of microtubules. Analyses of changes in transcription and protein phosphorylation suggest that hypothyroidism prolonged expression of fibroblast growth factor receptors, and decreased phosphorylated Cofilin. Conclusions These findings demonstrate that thyroid hormones may be involved in coordinating the processes that regulate cytoskeletal dynamics and suggest that manipulating thyroid hormone sensitivity might provide insight into the relationship between cytoskeletal formation and developing cell mechanical properties. PMID:23394545

Effects of Inula racemosa root and Gymnema sylvestre leaf extracts in the regulation of corticosteroid induced diabetes mellitus: involvement of thyroid hormones.

PubMed

Gholap, S; Kar, A

2003-06-01

The efficacy of Inula racemosa (root) and Gymnema sylvestre (leaf) extracts either alone or in combination was evaluated in the amelioration of corticosteroid-induced hyperglycaemia in mice. Simultaneously thyroid hormone levels were estimated by radio-immunoassay (RIA) in order to ascertain whether the effects are mediated through thyroid hormones or not. While the corticosteroid (dexamethasone) administration increased the serum glucose concentration, it decreased serum concentrations of the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Administration of the two plant extracts either alone or in combination decreased the serum glucose concentration in dexamethasone induced hyperglycaemic animals. However, the administration of Inula racemosa and Gymnema sylvestre extracts in combination proved to be more effective than the individual extracts. These effects were comparable to a standard corticosteroid-inhibiting drug, ketoconazole. As no marked changes in thyroid hormone concentrations were observed by the administration of any of the plant extracts in dexamethasone treated animals, it is further suggested that these plant extracts may not prove to be effective in thyroid hormone mediated type II diabetes, but for steroid induced diabetes.

Allosteric activation of the follicle-stimulating hormone (FSH) receptor by selective, nonpeptide agonists.

PubMed

Yanofsky, Stephen D; Shen, Emily S; Holden, Frank; Whitehorn, Erik; Aguilar, Barbara; Tate, Emily; Holmes, Christopher P; Scheuerman, Randall; MacLean, Derek; Wu, May M; Frail, Donald E; López, Francisco J; Winneker, Richard; Arey, Brian J; Barrett, Ronald W

2006-05-12

The pituitary glycoprotein hormones, luteinizing hormone and follicle-stimulating hormone (FSH), act through their cognate receptors to initiate a series of coordinated physiological events that results in germ cell maturation. Given the importance of FSH in regulating folliculogenesis and fertility, the development of FSH mimetics has been sought to treat infertility. Currently, purified and recombinant human FSH are the only FSH receptor (FSH-R) agonists available for infertility treatment. By screening unbiased combinatorial chemistry libraries, using a cAMP-responsive luciferase reporter assay, we discovered thiazolidinone agonists (EC50's = 20 microm) of the human FSH-R. Subsequent analog library screening and parallel synthesis optimization resulted in the identification of a potent agonist (EC50 = 2 nm) with full efficacy compared with FSH that was FSH-R-selective and -dependent. The compound mediated progesterone production in Y1 cells transfected with the human FSH-R (EC50 = 980 nm) and estradiol production from primary rat ovarian granulosa cells (EC50 = 10.5 nm). This and related compounds did not compete with FSH for binding to the FSH-R. Use of human FSH/thyroid-stimulating hormone (TSH) receptor chimeras suggested a novel mechanism for receptor activation through a binding site independent of the natural hormone binding site. This study is the first report of a high affinity small molecule agonist that activates a glycoprotein hormone receptor through an allosteric mechanism. The small molecule FSH receptor agonists described here could lead to an oral alternative to the current parenteral FSH treatments used clinically to induce ovarian stimulation for both in vivo and in vitro fertilization therapy.

The effect of adrenaline and noradrenaline on hormone secretion and blood flow from the thyroid vein in sheep with exteriorized thyroids.

PubMed

Falconer, I R

1967-02-01

1. Emotional stimulus to the sheep has previously been shown to cause increased thyroid hormone secretion; the influence of adrenaline and noradrenaline in this process has been investigated.2. Sheep bearing exteriorized thyroid glands on carotid artery-jugular vein loops were used. Thyroid vein blood was collected through a cannula in the jugular vein within the loop, and blood flow was measured by a plethysmographic technique.3. (131)I (50 muc) was injected intramuscularly (I.M.) into the sheep, and 4-7 days later the concentration of total and protein bound (131)I in thyroid vein blood was measured in samples taken every 10 min for 4 hr. Intracarotid injections of 1 mug, I.V. injections of 5 mug, or I.V. infusions at 10 mug/min for 10 min, of adrenaline or noradrenaline were administered 1.5 hr after commencement of sampling. Blood flow from the thyroid was measured in similar experiments.4. No significant changes in thyroid hormone secretion could be attributed to adrenaline or noradrenaline, and it was concluded that circulating catecholamines do not influence the release of thyroid hormone observed after brief emotional stimulus in the sheep.

The −258 A/G (SNP rs12885300) polymorphism of the human type-2 deiodinase gene is associated with a shift in the pattern of secretion of thyroid hormones following a TRH-induced acute rise in TSH

PubMed Central

Peltsverger, Maya Y.; Butler, Peter W.; Alberobello, Anna Teresa; Smith, Sheila; Guevara, Yanina; Dubaz, Ornella M.; Luzon, Javier A.; Linderman, Joyce; Celi, Francesco S.

2012-01-01

Objective Type-2 deiodinase gene (DIO2) polymorphisms have been associated with changes in pituitary-thyroid axis homeostasis. The −258 A/G (SNP rs12885300) polymorphism has been associated with increased enzymatic activity, but data are conflicting. To characterize the effects of the −258 A/G polymorphism on intra-thyroidal T4 to T3 conversion and thyroid hormone secretion pattern we studied the effects of acute, TRH-mediated, TSH stimulation of the thyroid gland. Design Retrospective analysis. Methods The thyroid hormone secretion in response to 500 mcg iv TRH injection was studied in 45 healthy volunteers. Results Twenty-six subjects (16 females, 10 males, 32.8±10.4 years) were homozygous for the ancestral (−258 A/A) allele, 19 (11 females, 8 males, 31.1±10.9 years) were carrier of the (−258 G/x) variant. While no differences in the peak TSH and T3 levels were observed, carriers of the −258G/x allele showed a blunted rise in free T4 (p<0.01). The −258G/x 92Thr/Thr haplotype, compared to the other groups, had lower TSH values at 60' (p<0.03). No differences were observed between genotypes in baseline thyroid hormone levels. Conclusions The −258G/x DIO2 polymorphism variant is associated with a decreased rate of acute TSH-stimulated free T4 secretion with a normal T3 release from the thyroid consistent with a shift in the reaction equilibrium toward the product. These data indicate that the −258G DIO2 polymorphism cause changes in the pattern of hormonal secretion. These findings are a proof-of-concept that common polymorphisms in the DIO2 can subtly affect the circulating levels of thyroid hormone and might modulate the thyroid hormone homeostasis. PMID:22307573

Perfluoroalkyl substances exposure and thyroid hormones in humans: epidemiological observations and implications

PubMed Central

Lee, Jung Eun

2017-01-01

Thyroid hormones play crucial roles in normal neurodevelopment of fetus and child. Many chemicals can affect control and homeostasis of thyroid hormones, and eventually lead to various adverse health effects including neurodevelopmental disorders. Perfluoroalkyl substances (PFASs) are among the thyroid disrupting chemicals that can be encountered among general human population. Due to their unique physicochemical characteristics, PFASs have been used as surfactants and surface coating materials in many applications. Therefore, PFASs have been frequently detected in humans and environment worldwide. In cross-sectional studies using nationally representative general human populations of United States, several PFASs have shown significant associations with thyroid hormones. Moreover, among pregnant women and their infants, not only major PFASs such as perfluorooctane sulfonic acid and perfluorooctanoic acid, but also those with shorter or longer carbon chains showed significant associations with thyroid hormones. Often demographic characteristics such as sex, age, and disease status appear to influence the associations between PFASs exposure and thyroid hormones. In general, major PFASs showed hypothyroidism effects among pregnant women and infants. As 8 carbon based PFASs have been phased out, those with shorter or longer carbon chains have been used in growing amount as replacement. However, only limited information is available for their occurrences and toxicity among humans. Further investigations on these substituting PFASs are required. In addition, efforts are warranted to identify sources of and mitigate exposure to these thyroid disrupting chemicals especially during pregnancy and early stages of life. PMID:28443254

Elevated Serum Polybrominated Diphenyl Ethers and Alteration of Thyroid Hormones in Children from Guiyu, China

PubMed Central

Xu, Xijin; Liu, Junxiao; Zeng, Xiang; Lu, Fangfang; Chen, Aimin; Huo, Xia

2014-01-01

Informal electronic waste (e-waste) recycling results in serious environmental pollution of polybrominated diphenyl ethers (PBDEs) and heavy metals. This study explored whether there is an association between PBDEs, heavy metal and key growth- and development-related hormones in children from Guiyu, an e-waste area in southern China. We quantified eight PBDE congeners using gas chromatographic mass spectrometry, lead and cadmium utilizing graphite furnace atomic absorption spectrometry, three thyroids with radioimmunoassay and two types of growth hormones by an enzyme-linked immune-sorbent assay (ELISA) in 162 children, 4 to 6 years old, from Guiyu. In blood, median total PBDE was 189.99 ng/g lipid. Lead and cadmium concentrations in blood averaged 14.53±4.85 µg dL−1 and 0.77±0.35 µg L−1, respectively. Spearman partial correlation analysis illustrated that lead was positively correlated with BDE153 and BDE183. Thyroid-stimulating hormone (TSH) was positively correlated with almost all PBDE congeners and negatively correlated with insulin-like growth factor binding protein-3 (IGFBP-3), whereas free triiodothyronine (FT3) and free thyroxine (FT4) were negatively correlated with BDE154. However, no correlation between the hormones and blood lead or cadmium levels was found in this study. Adjusted multiple linear regression analysis showed that total PBDEs was negatively associated with FT3 and positively associated with TSH. Notably, FT4 was positively correlated with FT3, house functions as a workshop, and father's work involved in e-waste recycling and negatively correlated with vitamin consumptions. TSH was negatively related with FT4, paternal residence time in Guiyu, working hours of mother, and child bean products intake. IGFBP-3 was positively correlated with IGF-1 and house close to an e-waste dump. These results suggest that elevated PBDEs and heavy metals related to e-waste in Guiyu may be important risk factors for hormone alterations in children. PMID:25415336

[Rare differential diagnosis of hyperthyroidism].

PubMed

Besemer, Britta; Müssig, Karsten

2016-06-01

A 54-year-old female patient is admitted for evaluation of her thyroid function after two cycles of ipilimumab therapy. The decision for the anti-cytotoxic-T-lymphocyte-antigen-4-therapy (anti-CTLA-4) was made two months earlier because of malignant melanoma with pulmonary metastases. The patient was euthyroid before initiation of treatment and without known thyroid disease. The laboratory reveals thyrotoxicosis with elevated anti-thyroid peroxidase and anti-thyroglobulin antibody levels. The anti-thyroid stimulating hormone receptor antibody levels are within the normal range. Thyroid ultrasound shows a normal-sized, inhomogenous, hypoechogenic thyroid gland, consistent with autoimmune thyroiditis. Diagnosis of hyperthyroidism due to ipilimumab-induced autoimmune thyroiditis is made. The patient does not receive any thyroid-specific medication, with regular control of the thyroid hormone levels. When the patient becomes euthyroid, the ipilimumab therapy is continued. Three weeks later, the patient develops hypothyroidism and a supplementation with L-thyroxine is initiated. An anti-CTLA-4 therapy may cause thyroid dysfunction. Therefore, before initiation and in the course of the treatment, regular controls of the thyroid hormone levels are required. © Georg Thieme Verlag KG Stuttgart · New York.

Site-specific PEGylation of human thyroid stimulating hormone to prolong duration of action.

PubMed

Qiu, Huawei; Boudanova, Ekaterina; Park, Anna; Bird, Julie J; Honey, Denise M; Zarazinski, Christine; Greene, Ben; Kingsbury, Jonathan S; Boucher, Susan; Pollock, Julie; McPherson, John M; Pan, Clark Q

2013-03-20

Recombinant human thyroid stimulating hormone (rhTSH or Thyrogen) has been approved for thyroid cancer diagnostics and treatment under a multidose regimen due to its short circulating half-life. To reduce dosing frequency, PEGylation strategies were explored to increase the duration of action of rhTSH. Lysine and N-terminal PEGylation resulted in heterogeneous product profiles with 40% or lower reaction yields of monoPEGylated products. Eleven cysteine mutants were designed based on a structure model of the TSH-TSH receptor (TSHR) complex to create unique conjugation sites on both α and β subunits for site-specific conjugation. Sequential screening of mutant expression level, oligomerization tendency, and conjugation efficiency resulted in the identification of the αG22C rhTSH mutant for stable expression and scale-up PEGylation. The introduced cysteine in the αG22C rhTSH mutant was partially blocked when isolated from conditioned media and could only be effectively PEGylated after mild reduction with cysteine. This produced a higher reaction yield, ~85%, for the monoPEGylated product. Although the mutation had no effect on receptor binding, PEGylation of αG22C rhTSH led to a PEG size-dependent decrease in receptor binding. Nevertheless, the 40 kDa PEG αG22C rhTSH showed a prolonged duration of action compared to rhTSH in a rat pharmacodynamics model. Reverse-phase HPLC and N-terminal sequencing experiments confirmed site-specific modification at the engineered Cys 22 position on the α-subunit. This work is another demonstration of successful PEGylation of a cysteine-knot protein by an engineered cysteine mutation.

Role of Thyroid Hormones in Skeletal Development and Bone Maintenance

PubMed Central

Bassett, J. H. Duncan

2016-01-01

The skeleton is an exquisitely sensitive and archetypal T3-target tissue that demonstrates the critical role for thyroid hormones during development, linear growth, and adult bone turnover and maintenance. Thyrotoxicosis is an established cause of secondary osteoporosis, and abnormal thyroid hormone signaling has recently been identified as a novel risk factor for osteoarthritis. Skeletal phenotypes in genetically modified mice have faithfully reproduced genetic disorders in humans, revealing the complex physiological relationship between centrally regulated thyroid status and the peripheral actions of thyroid hormones. Studies in mutant mice also established the paradigm that T3 exerts anabolic actions during growth and catabolic effects on adult bone. Thus, the skeleton represents an ideal physiological system in which to characterize thyroid hormone transport, metabolism, and action during development and adulthood and in response to injury. Future analysis of T3 action in individual skeletal cell lineages will provide new insights into cell-specific molecular mechanisms and may ultimately identify novel therapeutic targets for chronic degenerative diseases such as osteoporosis and osteoarthritis. This review provides a comprehensive analysis of the current state of the art. PMID:26862888

Update on subclinical hyperthyroidism.

PubMed

Donangelo, Ines; Braunstein, Glenn D

2011-04-15

Subclinical hyperthyroidism is defined by low or undetectable serum thyroid-stimulating hormone levels, with normal free thyroxine and total or free triiodothyronine levels. It can be caused by increased endogenous production of thyroid hormone (as in Graves disease or toxic nodular goiter), administration of thyroid hormone for treatment of malignant thyroid disease, or unintentional excessive thyroid hormone therapy. The rate of progression to overt hyperthyroidism is higher in persons who have suppressed thyroid-stimulating hormone levels compared with those who have low but detectable levels. Subclinical hyperthyroidism is associated with an increased risk of atrial fibrillation in older adults, and with decreased bone mineral density in postmenopausal women; however, the effectiveness of treatment in preventing these conditions is unknown. There is lesser-quality evidence suggesting an association between subclinical hyperthyroidism and other cardiovascular effects, including increased heart rate and left ventricular mass, and increased bone turnover markers. Possible associations between subclinical hyperthyroidism and quality of life parameters, cognition, and increased mortality rates are controversial. Prospective randomized controlled trials are needed to address the effects of early treatment on potential morbidities to help determine whether screening should be recommended in the asymptomatic general population.

Inhibitors for Androgen Receptor Activation Surfaces

DTIC Science & Technology

2007-09-01

Inhibitor of Coregulator Binding to the Thyroid Hormone Receptor.. Molecular Endocrinology, 2007 Sep 6; [Epub ahead of print] PMID: 17823305 (related...Kiplin Guy†, Paul Webb‡, and Robert J. Fletterick* *Department of Biochemistry and Biophysics, §Department of Molecular and Cellular Pharmacology, and...are also small but significant shifts in secondary structural elements; residues 720–730 (H3) and 825–847 (H9) exhibit rmsd of 0.33 and 0.44

Structural and functional maturation of rat gastrointestinal barrier with thyroxine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Israel, E.J.; Pang, K.Y.; Harmatz, P.R.

It has been noted that the closure of the intestinal barrier to immunoglobulins is a normal maturational process in the rat. It has also been noted that the microvillus membrane (MVM) of newborn animals differs from adult MVM. The purpose of this study is to document whether thyroid hormone can induce closure in vivo in the rat and to relate this effect of thyroxine to the structural and functional maturation of the intestinal MVM. To assess closure, 2-wk-old rats were fed in rat immunoglobulin G (IgG), and serum antibody binding activity was measured 4 h later. The antibody binding activitymore » of treated animals (T) was 1.5-2 times less than that of controls (C), indicating that thyroxine stimulates closure. The MVM similarly showed signs of maturation. Structural maturation was demonstrated by the lower fluidity of the thyroid-treated animals' membranes. Under the influence of thyroxine, the number of receptors on the MVM for IgG had decreased, while the K/sub a/ remained the same, demonstrating the functional maturation of the MVM. In conclusion, thryoid hormone can induce both structural and functional maturation of the intestinal MVM and can enhance the intestinal mucosal barrier by decreasing the penetration of antibodies.« less

Insufficient documentation for clinical efficacy of selenium supplementation in chronic autoimmune thyroiditis, based on a systematic review and meta-analysis.

PubMed

Winther, Kristian Hillert; Wichman, Johanna Eva Märta; Bonnema, Steen Joop; Hegedüs, Laszlo

2017-02-01

By a systematic review and meta-analysis to investigate clinically relevant effects of selenium supplementation in patients with chronic autoimmune thyroiditis. Controlled trials in adults (≥18 years) with autoimmune thyroiditis, comparing selenium with or without levothyroxine substitution, versus placebo and/or levothyroxine substitution, were eligible for inclusion. Identified outcomes were serum thyrotropin (thyroid stimulating hormone) levels in LT4-untreated patients, thyroid ultrasound and health-related quality of life. Eleven publications, covering nine controlled trials, were included in the systematic review. Random effects model meta-analyses were performed in weighted mean difference for thyroid stimulating hormone, ultrasound and health-related quality of life. Quality of evidence was assessed per outcome, using GRADE. Meta-analyses showed no change in thyroid stimulating hormone, or improvements in health-related quality of life or thyroid echogenicity (ultrasound), between levothyroxine substitution-untreated patients assigned to selenium supplementation or placebo. Three trials found some improvement in wellbeing in patients receiving levothyroxine substitution, but could not be synthesized in a meta-analysis. The quality of evidence ranged from very low to low for thyroid stimulating hormone as well as ultrasound outcomes, and low to moderate for health-related quality of life, and was generally downgraded due to small sample sizes. We found no effect of selenium supplementation on thyroid stimulating hormone, health-related quality of life or thyroid ultrasound, in levothyroxine substitution-untreated individuals, and sporadic evaluation of clinically relevant outcomes in levothyroxine substitution-treated patients. Future well-powered RCTs, evaluating e.g. disease progression or health-related quality of life, are warranted before determining the relevance of selenium supplementation in autoimmune thyroiditis.

Selenium deficiency inhibits the conversion of thyroidal thyroxine (T4) to triiodothyronine (T3) in chicken thyroids.

PubMed

Lin, Shi-lei; Wang, Cong-wu; Tan, Si-ran; Liang, Yang; Yao, Hai-dong; Zhang, Zi-wei; Xu, Shi-wen

2014-12-01

Selenium (Se) influences the metabolism of thyroid hormones in mammals. However, the role of Se deficiency in the regulation of thyroid hormones in chickens is not well known. In the present study, we examined the levels of thyroidal triiodothyronine (T3), thyroidal thyroxine (T4), free triiodothyronine, free thyroxine (FT4), and thyroid-stimulating hormone in the serum and the mRNA expression levels of 25 selenoproteins in chicken thyroids. Then, principal component analysis (PCA) was performed to analyze the relationships between the selenoproteins. The results indicated that Se deficiency influenced the conversion of T4 to T3 and induced the accumulation of T4 and FT4. In addition, the mRNA expression levels of the selenoproteins were generally decreased by Se deficiency. The PCA showed that eight selenoproteins (deiodinase 1 (Dio1), Dio2, Dio3, thioredoxin reductase 2 (Txnrd2), selenoprotein i (Seli), selenoprotein u (Selu), glutathione peroxidase 1 (Gpx1), and Gpx2) have similar trends, which indicated that they may play similar roles in the metabolism of thyroid hormones. The results showed that Se deficiency inhibited the conversion of T4 to T3 and decreased the levels of the crucial metabolic enzymes of the thyroid hormones, Dio1, Dio2, and Dio3, in chickens. In addition, the decreased selenoproteins (Dio1, Dio2, Dio3, Txnrd2, Seli, Selu, Gpx1, and Gpx2) induced by Se deficiency may indirectly limit the conversion of T4 to T3 in chicken thyroids. The information presented in this study is helpful to understand the role of Se in the thyroid function of chickens.

The Role of the Multiple Hormonal Dysregulation in the Onset of “Anemia of Aging”: Focus on Testosterone, IGF-1, and Thyroid Hormones

PubMed Central

Maggio, Marcello; De Vita, Francesca; Fisichella, Alberto; Lauretani, Fulvio; Ticinesi, Andrea; Ceresini, Graziano; Cappola, Anne; Ferrucci, Luigi; Ceda, Gian Paolo

2015-01-01

Anemia is a multifactorial condition whose prevalence increases in both sexes after the fifth decade of life. It is a highly represented phenomenon in older adults and in one-third of cases is “unexplained.” Ageing process is also characterized by a “multiple hormonal dysregulation” with disruption in gonadal, adrenal, and somatotropic axes. Experimental studies suggest that anabolic hormones such as testosterone, IGF-1, and thyroid hormones are able to increase erythroid mass, erythropoietin synthesis, and iron bioavailability, underlining a potential role of multiple hormonal changes in the anemia of aging. Epidemiological data more consistently support an association between lower testosterone and anemia in adult-older individuals. Low IGF-1 has been especially associated with anemia in the pediatric population and in a wide range of disorders. There is also evidence of an association between thyroid hormones and abnormalities in hematological parameters under overt thyroid and euthyroid conditions, with limited data on subclinical statuses. Although RCTs have shown beneficial effects, stronger for testosterone and the GH-IGF-1 axis and less evident for thyroid hormones, in improving different hematological parameters, there is no clear evidence for the usefulness of hormonal treatment in improving anemia in older subjects. Thus, more clinical and research efforts are needed to investigate the hormonal contribution to anemia in the older individuals. PMID:26779261

The Role of the Multiple Hormonal Dysregulation in the Onset of "Anemia of Aging": Focus on Testosterone, IGF-1, and Thyroid Hormones.

PubMed

Maggio, Marcello; De Vita, Francesca; Fisichella, Alberto; Lauretani, Fulvio; Ticinesi, Andrea; Ceresini, Graziano; Cappola, Anne; Ferrucci, Luigi; Ceda, Gian Paolo

2015-01-01

Anemia is a multifactorial condition whose prevalence increases in both sexes after the fifth decade of life. It is a highly represented phenomenon in older adults and in one-third of cases is "unexplained." Ageing process is also characterized by a "multiple hormonal dysregulation" with disruption in gonadal, adrenal, and somatotropic axes. Experimental studies suggest that anabolic hormones such as testosterone, IGF-1, and thyroid hormones are able to increase erythroid mass, erythropoietin synthesis, and iron bioavailability, underlining a potential role of multiple hormonal changes in the anemia of aging. Epidemiological data more consistently support an association between lower testosterone and anemia in adult-older individuals. Low IGF-1 has been especially associated with anemia in the pediatric population and in a wide range of disorders. There is also evidence of an association between thyroid hormones and abnormalities in hematological parameters under overt thyroid and euthyroid conditions, with limited data on subclinical statuses. Although RCTs have shown beneficial effects, stronger for testosterone and the GH-IGF-1 axis and less evident for thyroid hormones, in improving different hematological parameters, there is no clear evidence for the usefulness of hormonal treatment in improving anemia in older subjects. Thus, more clinical and research efforts are needed to investigate the hormonal contribution to anemia in the older individuals.

Thyroid storm: an updated review.

PubMed

Chiha, Maguy; Samarasinghe, Shanika; Kabaker, Adam S

2015-03-01

Thyroid storm, an endocrine emergency first described in 1926, remains a diagnostic and therapeutic challenge. No laboratory abnormalities are specific to thyroid storm, and the available scoring system is based on the clinical criteria. The exact mechanisms underlying the development of thyroid storm from uncomplicated hyperthyroidism are not well understood. A heightened response to thyroid hormone is often incriminated along with increased or abrupt availability of free hormones. Patients exhibit exaggerated signs and symptoms of hyperthyroidism and varying degrees of organ decompensation. Treatment should be initiated promptly targeting all steps of thyroid hormone formation, release, and action. Patients who fail medical therapy should be treated with therapeutic plasma exchange or thyroidectomy. The mortality of thyroid storm is currently reported at 10%. Patients who have survived thyroid storm should receive definite therapy for their underlying hyperthyroidism to avoid any recurrence of this potentially fatal condition. © The Author(s) 2013.

Paradigm Shift in Thyroid Hormone Mechanism of Action | Center for Cancer Research

Cancer.gov

Thyroid hormone (TH) is one of the primary endocrine regulators of human metabolism and homeostasis. Acting through three forms of the thyroid hormone receptor (THR; alpha-1, beta-1, and beta-2), TH regulates target gene expression in nearly every cell in the body, modulating fundamental processes, such as basal metabolic rate, long bone growth, and neural maturation. TH is

Age impact on autoimmune thyroid disease in females

NASA Astrophysics Data System (ADS)

Stoian, Dana; Craciunescu, Mihalea; Timar, Romulus; Schiller, Adalbert; Pater, Liana; Craina, Marius

2013-10-01

Thyroid autoimmune disease, a widespread phenomenon in female population, impairs thyroid function during pregnancy. Identifying cases, which will develop hypothyroidism during pregnancy, is crucial in the follow-up process. The study group comprised 108 females, with ages between 20-40 years; with known inactive autoimmune thyroid disease, before pregnancy that became pregnant in the study follow-up period. They were monitored by means of clinical, hormonal and immunological assays. Supplemental therapy with thyroid hormones was used, where needed. Maternal age and level of anti-thyroid antibodies were used to predict thyroid functional impairment.

Are thyroid nodules associated with sex-related hormones? A cross-sectional SPECT-China study.

PubMed

Chen, Yi; Chen, Yingchao; Wang, Ningjian; Chen, Chi; Nie, Xiaomin; Li, Qin; Han, Bing; Xia, Fangzhen; Zhai, Hualing; Jiang, Boren; Shen, Zhoujun; Lu, Yingli

2017-08-03

Little is known about the association between thyroid nodules (TNs) and endogenous sex hormones. We aimed to investigate the relationship between TNs and sex-related hormones among men in China. The data were obtained from a cross-sectional study Survey on Prevalence in East China for Metabolic Diseases and Risk Factors (SPECT-China study, 2014-2015) based on the population. In total, 4024 men over 18 years of age who were not using hormone replacement therapy and who underwent complete assays of the serum total testosterone (T), oestradiol (E 2 ), follicle-stimulating hormone (FSH), luteinising hormone (LH) and sex hormone-binding globulin (SHBG) levels as well as thyroid ultrasonography (US) enrolled in this study. Of the 4024 participants (54.15±13.08 years old), 1667 participants (41.4%) had TNs. Men with TN(s) (TN(+) group) had significantly lower levels of total T and SHBG and higher E 2 /T levels compared with the men without TN(s) (TN(-) group) (p<0.05). The TN prevalence decreased with the quartiles of the SHBG level (p<0.05). Binary logistic analysis showed that lower quartiles of SHBG had a greater risk of TN(s) (all p for trend <0.05). This association persisted in the fully adjusted model (p for trend=0.017), in which, for the lowest compared with the highest quartile of SHBG, the OR of TN(s) was 1.42 (95% CI 1.07 to 1.89). No statistically significant association was found between sex-related hormones and US characteristics associated with malignancy (nodule >10 mm, microcalcification and a 'taller' than 'wider' shape). TNs are highly prevalent in men in China. A lower SHBG level was significantly associated with TN among men. The potential role of SHBG in the pathogenesis of the TN remains to be elucidated. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Effects of thyroid hormone status on metabolic pathways of arachidonic acid in mice and humans: A targeted metabolomic approach.

PubMed

Yao, Xuan; Sa, Rina; Ye, Cheng; Zhang, Duo; Zhang, Shengjie; Xia, Hongfeng; Wang, Yu-cheng; Jiang, Jingjing; Yin, Huiyong; Ying, Hao

2015-01-01

Symptoms of cardiovascular diseases are frequently found in patients with hypothyroidism and hyperthyroidism. However, it is unknown whether arachidonic acid metabolites, the potent mediators in cardiovascular system, are involved in cardiovascular disorders caused by hyperthyroidism and hypothyroidism. To answer this question, serum levels of arachidonic acid metabolites in human subjects with hypothyroidism, hyperthyroidism and mice with hypothyroidism or thyroid hormone treatment were determined by a mass spectrometry-based method. Over ten arachidonic acid metabolites belonging to three catalytic pathways: cyclooxygenases, lipoxygenases, and cytochrome P450, were quantified simultaneously and displayed characteristic profiles under different thyroid hormone status. The level of 20-hydroxyeicosatetraenoic acid, a cytochrome P450 metabolite, was positively correlated with thyroid hormone level and possibly contributed to the elevated blood pressured in hyperthyroidism. The increased prostanoid (PG) I2 and decreased PGE2 levels in hypothyroid patients might serve to alleviate atherosclerosis associated with dyslipidemia. The elevated level of thromboxane (TX) A2, as indicated by TXB2, in hyperthyroid patients and mice treated with thyroid hormone might bring about pulmonary hypertension frequently found in hyperthyroid patients. In conclusion, our prospective study revealed that arachidonic acid metabolites were differentially affected by thyroid hormone status. Certain metabolites may be involved in cardiovascular disorders associated with thyroid diseases. Copyright © 2015 Elsevier Inc. All rights reserved.

The interruption of thyroid and interrenal and the inter-hormonal interference in fish: does it promote physiologic adaptation or maladaptation?

PubMed

Peter, Valsa S; Peter, M C Subhash

2011-12-01

Endocrines, the chief components of chemical centers which produce hormones in tune with intrinsic and extrinsic clues, create a chemical bridge between the organism and the environment. In fishes also hormones integrate and modulate many physiologic functions and its synthesis, release, biological actions and metabolic clearance are well regulated. Consequently, thyroid hormones (THs) and cortisol, the products of thyroid and interrenal axes, have been identified for their common integrative actions on metabolic and osmotic functions in fish. On the other hand, many anthropogenic chemical substances, popularly known as endocrine disrupting chemicals, have been shown to disrupt the hormone-receptor signaling pathways in a number fish species. These chemicals which are known for their ability to induce endocrine disruption particularly on thyroid and interrenals can cause malfunction or maladaptation of many vital processes which are involved in the development, growth and reproduction in fish. On the contrary, evidence is presented that the endocrine interrupting agents (EIAs) can cause interruption of thyroid and interrenals, resulting in physiologic compensatory mechanisms which can be adaptive, though such hormonal interactions are less recognized in fishes. The EIAs of physical, chemical and biological origins can specifically interrupt and modify the hormonal interactions between THs and cortisol, resulting in specific patterns of inter-hormonal interference. The physiologic analysis of these inter-hormonal interruptions during acclimation and post-acclimation to intrinsic or extrinsic EIAs reveals that combinations of anti-hormonal, pro-hormonal or stati-hormonal interference may help the fish to fine-tune their metabolic and osmotic performances as part of physiologic adaptation. This novel hypothesis on the phenomenon of inter-hormonal interference and its consequent physiologic interference during thyroid and interrenal interruption thus forms the basis of physiologic acclimation. This interfering action of TH and cortisol during hormonal interruption may subsequently promote ecological adaptation in fish as these physiologic processes ultimately favor them to survive in their hostile environment. Copyright © 2011 Elsevier Inc. All rights reserved.

T-screen and yeast assay for the detection of the thyroid-disrupting activities of cadmium, mercury, and zinc.

PubMed

Li, Jian; Liu, Yun; Kong, Dongdong; Ren, Shujuan; Li, Na

2016-05-01

In the present study, a two-hybrid yeast bioassay and a T-screen were used to screen for the thyroid receptor (TR)-disrupting activity of select metallic compounds (CdCl2, ZnCl2, HgCl2, CuSO4, MnSO4, and MgSO4). The results reveal that none of the tested metallic compounds showed TR-agonistic activity, whereas ZnCl2, HgCl2, and CdCl2 demonstrated TR antagonism. For the yeast assay, the dose-response relationship of these metallic compounds was established, and the concentrations producing 20 % of the maximum effect of ZnCl2, HgCl2, and CdCl2 were 9.1 × 10(-5), 3.2 × 10(-6), and 1.2 × 10(-6) mol/L, respectively. The T-screen also supported the finding that ZnCl2, HgCl2, and CdCl2 decreased the cell proliferation at concentrations ranging from 10(-6) to 10(-4) mol/L. Furthermore, the thyroid-disrupting activity of metallic compounds in environmental water samples collected from the Guanting Reservoir, Beijing, China was evaluated. Solid-phase extraction was used to separate the organic extracts, and a modified two-hybrid yeast bioassay revealed that the metallic compounds in the water samples could affect thyroid hormone-induced signaling by decreasing the binding of the thyroid hormone. The addition of ethylenediaminetetraacetic acid (30 mg/L) could eliminate the effects. Thus, the cause(s) of the thyroid toxicity in the water samples appeared to be partly related to the metallic compounds.

Acute exposure to synthetic pyrethroids causes bioconcentration and disruption of the hypothalamus-pituitary-thyroid axis in zebrafish embryos.

PubMed

Tu, Wenqing; Xu, Chao; Lu, Bin; Lin, Chunmian; Wu, Yongming; Liu, Weiping

2016-01-15

Synthetic pyrethroids (SPs) have the potential to disrupt the thyroid endocrine system in mammals; however, little is known of the effects of SPs and underlying mechanisms in fish. In the current study, embryonic zebrafish were exposed to various concentrations (1, 3 and 10 μg/L) of bifenthrin (BF) or λ-cyhalothrin (λ-CH) until 72 h post fertilization, and body condition, bioaccumulation, thyroid hormone levels and transcription of related genes along the hypothalamus-pituitary-thyroid (HPT) axis examined. Body weight was significantly decreased in the λ-CH exposure groups, but not the BF exposure groups. BF and λ-CH markedly accumulated in the larvae, with concentrations ranging from 90.7 to 596.8 ng/g. In both exposure groups, alterations were observed in thyroxine (T4) and triiodothyronine (T3) levels. In addition, the majority of the HPT axis-related genes examined, including CRH, TSHβ, TTR, UGT1ab, Pax8, Dio2 and TRα, were significantly upregulated in the presence of BF. Compared to BF, λ-CH induced different transcriptional regulation patterns of the tested genes, in particular, significant stimulation of TTR, Pax8, Dio2 and TRα levels along with concomitant downregulation of Dio1. Molecular docking analyses revealed that at the atomic level, BF binds to thyroid hormone receptor (TRα) protein more potently than λ-CH, consequently affecting HPT axis signal transduction. In vitro and in silico experiments disclosed that during the early stages of zebrafish development, BF and λ-CH have the potential to disrupt thyroid endocrine system. Copyright © 2015 Elsevier B.V. All rights reserved.

New medications which decrease levothyroxine absorption.

PubMed

John-Kalarickal, Jennifer; Pearlman, Gwen; Carlson, Harold E

2007-08-01

Medications may sometimes interfere with the intestinal absorption of levothyroxine, primarily by forming an insoluble complex with the thyroid hormone in the intestinal lumen. The goal of this study was to examine the acute effects of three previously unstudied medications on levothyroxine absorption. We studied the effects of three medications on thyroxine absorption in seven normal volunteers. On each study day, the subjects ingested 1 mg levothyroxine sodium, either taken separately or co-administered with sevelamer hydrochloride (Renagel, a phosphate-binding medication used in the treatment of hyperphosphatemia), chromium picolinate (an over-the-counter nutritional supplement), or ezetimibe (Zetia, a drug used in the treatment of hypercholesterolemia). Serum thyroxine was measured at intervals over a 6-hour period following drug ingestion. Sevelamer hydrochloride and chromium picolinate each significantly (p < 0.05) decreased the area under the serum thyroxine concentration curve, while ezetimibe had no effect. Hypothyroid patients taking sevelamer hydrochloride or chromium picolinate should be advised to separate the time of ingestion of these drugs from their thyroid hormone preparation by several hours.

Biomolecular Doping of Single-Walled Carbon Nanotubes by Thyroid Hormone

NASA Astrophysics Data System (ADS)

Rojas, Enrique; Paulson, Scott; Stern, Mike; Staii, Cristian; Dratman, Mary; Johnson, Alan

2004-03-01

Electron doping of semiconducting single-walled carbon nanotubes (SWNTs) by the thyroid hormone triiodothyronine (T3) is observed. T3 is applied locally, in solution, to SWNT field effect transistors (FETs) and binds along the length of the nanotube. T3 acts as an electron donor, shifting the I-V gate characteristics towards negative values of gate voltage. Shifts in the characteristics are measured as a function of the concentration of the solution. The effect is nearly reversible by rinsing the FETs with the solvent. Several days after application of T3, with no solvent rinsing, the gate characteristics are also nearly reversed. Experiments with a similar molecule for which the phenol ring is brominated as well as experiments with the de-iodinated molecule (T0) are performed to inform the effect of the iodine. The interaction of T3 with SWNTs may suggest a electronic interaction of T3 with other one-dimensional systems such as DNA.

Potential protective effect of Pistacia lentiscus oil against chlorpyrifos-induced hormonal changes and oxidative damage in ovaries and thyroid of female rats.

PubMed

Chebab, Samira; Mekircha, Fatiha; Leghouchi, Essaid

2017-12-01

The purpose of this study was to evaluate the protective effect of Pistacia lentiscus oil (PLO), known for its antioxidant properties, on chlorpyrifos (CPF)-induced alterations in the thyroid, reproductive hormone levels, and oxidative damage in the ovaries and thyroid of adult Wistar rats. The animals were treated with orally administered PLO (2 mL/kg), CPF (6.75 mg/kg), and a combination of CPF and PLO for 30 days. Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (Pg), estradiol (E 2 ), triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) were assessed using chemiluminescence assay. Malondialdehyde (MDA), protein carbonyl (PC), and reduced glutathione (GSH) levels were examined in the ovaries and thyroid glands. The oil principal volatile compounds detected by gas chromatography analysis were: myrcene, α-pinene and limonene (26.21, 22.66 and 10.33%, respectively). No significant differences were observed between serum concentrations of TSH and FSH in the examined experimental groups. However, serum concentrations of LH, E 2 , Pg, T3, and T4 decreased significantly in CPF-treated rats in comparison with the controls. The body weight and relative weight of ovaries and thyroids in this group were also significantly reduced. The MDA and PC content increased significantly, while the GSH content was markedly depressed in the thyroid and ovaries of rats treated with CPF. Co-administration of PLO and CPF effectively ameliorated the adverse effects; the oxidative damage was reduced and the levels of thyroid and reproductive hormones restored to a normal range. In conclusion, it appears that PLO substantially alleviates the CPF-induced oxidative damage and hormonal alterations. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

The effects of thyroid hormones on brown adipose tissue in humans: a PET-CT study.

PubMed

Zhang, Qiongyue; Miao, Qing; Ye, Hongying; Zhang, Zhaoyun; Zuo, Chuantao; Hua, Fengchun; Guan, Yihui; Li, Yiming

2014-09-01

Brown adipose tissue (BAT) is important for energy expenditure through thermogenesis, although its regulatory factors are not well known in humans. There is evidence suggesting that thyroid hormones affect BAT functions in some mammals, but the effects of thyroid hormones on BAT activity in humans are still unclear. The aim of this study was to investigate the effects of thyroid hormones on glucose metabolism of BAT and other organs in humans. Nine Graves' disease-caused hyperthyroid patients who were newly diagnosed and untreated were studied. Putative brown adipose tissue activity was determined by the integrated ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron-emission tomography and computed tomography (PET-CT). All hyperthyroid patients were treated with methimazole and had been monitored until their symptoms disappeared and thyroid hormone levels returned to normal. At the end, a second PET-CT scan was performed. The average follow-up period was 77 days. Meanwhile, compared with a group of seventy-five brown adipose tissue-negative controls, thyroid hormones of seventy-five BAT-positive healthy subjects were measured. Active brown adipose tissue was not present in any of the hyperthyroid patients. However, one patient with normalized thyroid function showed active BAT after therapy. The free T3 levels and free T4 levels were significantly lower in the 75 BAT-positive subjects than in the BAT-negative subjects. All hyperthyroid patients showed symmetrically increased uptake of fluorodeoxyglucose in skeletal muscles before treatment, whereas, the standardized uptake value was substantially decreased after treatment. Abnormally high circulating thyroid hormone levels may not increase brown adipose tissue activity, which may be limited by the increased obligatory thermogenesis of muscle in adult humans. Copyright © 2014 John Wiley & Sons, Ltd.

Maternal thyroid hormone trajectories during pregnancy and child behavioral problems.

PubMed

Endendijk, Joyce J; Wijnen, Hennie A A; Pop, Victor J M; van Baar, Anneloes L

2017-08-01

There is ample evidence demonstrating the importance of maternal thyroid hormones, assessed at single trimesters in pregnancy, for child cognition. Less is known, however, about the course of maternal thyroid hormone concentrations during pregnancy in relation to child behavioral development. Child sex might be an important moderator, because there are sex differences in externalizing and internalizing behavioral problems. The current study examined the associations between maternal thyroid hormone trajectories versus thyroid assessments at separate trimesters of pregnancy and child behavioral problems, as well as sex differences in these associations. In 442 pregnant mothers, serum levels of TSH and free T4 (fT4) were measured at 12, 24, and 36weeks gestation. Both mothers and fathers reported on their children's behavioral problems, between 23 and 60months of age. Latent growth mixture modeling was used to determine the number of different thyroid hormone trajectories. Three trajectory groups were discerned: 1) highest and non-increasing TSH with lowest fT4 that decreased least of the three trajectories; 2) increasing TSH and decreasing fT4 at intermediate levels; 3) lowest and increasing TSH with highest and decreasing fT4. Children of mothers with the most flattened thyroid hormone trajectories (trajectory 1) showed the most anxiety/depression symptoms. The following trimester-specific associations were found: 1) lower first-trimester fT4 was associated with more child anxiety/depression, 2) higher first-trimester TSH levels were related to more attention problems in boys only. A flattened course of maternal thyroid hormone concentrations during pregnancy was a better predictor of child anxiety/depression than first-trimester fT4 levels. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessment of the value of quantitative thyroid scintigraphy for determination of thyroid function in dogs.

PubMed

Shiel, R E; Pinilla, M; McAllister, H; Mooney, C T

2012-05-01

To assess the value of thyroid scintigraphy to determine thyroid status in dogs with hypothyroidism and various non-thyroidal illnesses. Thyroid hormone concentrations were measured and quantitative thyroid scintigraphy performed in 21 dogs with clinical and/or clinicopathological features consistent with hypothyroidism. In 14 dogs with technetium thyroidal uptake values consistent with euthyroidism, further investigations supported non-thyroidal illness. In five dogs with technetium thyroidal uptake values within the hypothyroid range, primary hypothyroidism was confirmed as the only disease in four. The remaining dog had pituitary-dependent hyperadrenocorticism. Two dogs had technetium thyroidal uptake values in the non-diagnostic range. One dog had iodothyronine concentrations indicative of euthyroidism. In the other, a dog receiving glucocorticoid therapy, all iodothyronine concentrations were decreased. Markedly asymmetric technetium thyroidal uptake was present in two dogs. All iodothyronine concentrations were within reference interval but canine thyroid stimulating hormone concentration was elevated in one. Non-thyroidal illness was identified in both cases. In dogs, technetium thyroidal uptake is a useful test to determine thyroid function. However, values may be non-diagnostic, asymmetric uptake can occur and excess glucocorticoids may variably suppress technetium thyroidal uptake and/or thyroid hormone concentrations. Further studies are necessary to evaluate quantitative thyroid scintigraphy as a gold standard method for determining canine thyroid function. © 2012 British Small Animal Veterinary Association.

Follicular thyroglobulin induces cathepsin H expression and activity in thyrocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oda, Kenzaburo; Laboratory of Molecular Diagnostics, Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases, 4-2-1 Aoba-cho, Higashimurayama, Tokyo 189-0002; Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Toho University, 5-21-16 Omorinishi, Ota, Tokyo 143-8540

Thyroglobulin (Tg) stored in thyroid follicles exerts a potent negative-feedback effect on each step of pre-hormone biosynthesis, including Tg gene transcription and iodine uptake and organification, by suppressing the expression of specific transcription factors that regulate these steps. Pre-hormones are stored in the follicular colloid before being reabsorbed. Following lysosomal proteolysis of its precursor, thyroid hormone (TH) is released from thyroid follicles. Although the suppressive effects of follicular Tg on each step of pre-hormone biosynthesis have been extensively characterized, whether follicular Tg accumulation also affects hormone reabsorption, proteolysis, and secretion is unclear. In this study we explored whether follicular Tgmore » can regulate the expression and function of the lysosomal endopeptidases cathepsins. We found that in the rat thyroid cell line FRTL-5 follicular Tg induced cathepsin H mRNA and protein expression, as well as cathepsin H enzyme activity. Double immunofluorescence staining showed that Tg endocytosis promoted cathepsin H translocalization into lysosomes where it co-localized with internalized Tg. These results suggest that cathepsin H is an active participant in lysosome-mediated pre-hormone degradation, and that follicular Tg stimulates mobilization of pre-hormones by activating cathepsin H-associated proteolysis pathways. - Highlights: • Follicular Tg increases cathepsin H mRNA and protein levels in rat thyroid cells. • Follicular Tg increases cathepsin H enzyme activity in rat thyroid cells. • After Tg stimulation cathepsin H co-localizes to lysosomes with follicular Tg. • Cathepsin H promotes hormone secretion by lysosome-mediated mechanisms.« less

Alien/CSN2 gene expression is regulated by thyroid hormone in rat brain.

PubMed

Tenbaum, Stephan P; Juenemann, Stefan; Schlitt, Thomas; Bernal, Juan; Renkawitz, Rainer; Muñoz, Alberto; Baniahmad, Aria

2003-02-01

Alien has been described as a corepressor for the thyroid hormone receptor (TR). Corepressors are coregulators that mediate gene silencing of DNA-bound transcriptional repressors. We describe here that Alien gene expression in vivo is regulated by thyroid hormone both in the rat brain and in cultured cells. In situ hybridization revealed that Alien is widely expressed in the mouse embryo and also throughout the rat brain. Hypothyroid animals exhibit lower expression of both Alien mRNAs and protein levels as compared with normal animals. Accordingly, we show that Alien gene is inducible after thyroid hormone treatment both in vivo and in cell culture. In cultured cells, the hormonal induction is mediated by either TRalpha or TRbeta, while cells lacking detectable amounts of functional TR lack hormonal induction of Alien. We have detected two Alien-specific mRNAs by Northern experiments and two Alien-specific proteins in vivo and in cell lines by Western analysis, one of the two forms representing the CSN2 subunit of the COP9 signalosome. Interestingly, both Alien mRNAs and both detected proteins are regulated by thyroid hormone in vivo and in cell lines. Furthermore, we provide evidence for the existence of at least two Alien genes in rodents. Taken together, we conclude that Alien gene expression is under control of TR and thyroid hormone. This suggests a negative feedback mechanism between TR and its own corepressor. Thus, the reduction of corepressor levels may represent a control mechanism of TR-mediated gene silencing.

Effects of prolonged fasting on plasma cortisol and TH in postweaned northern elephant seal pups

NASA Technical Reports Server (NTRS)

Ortiz, R. M.; Wade, C. E.; Ortiz, C. L.

2001-01-01

Northern elephant seal (Mirounga angustirostris) pups rely on the oxidation of fat stores as their primary source of energy during their 8- to 12-wk postweaning fast; however, potential endocrine mechanisms involved with this increased fat metabolism have yet to be examined. Therefore, 15 pups were serially blood sampled in the field during the first 7 wk of their postweaning fast to examine the changes in plasma concentrations of cortisol and thyroid hormones (TH), which are involved in fat metabolism in other mammals. Cortisol increased, indicating that it contributed to an increase in lipolysis. Increased total triiodothyronine (tT(3)) and thyroxine (tT(4)) may not reflect increased thyroid gland activity, but rather alterations in hormone metabolism. tT(3)-to-tT(4) ratio decreased, suggesting a decrease in thyroxine (T(4)) deiodination, whereas the negative correlation between total proteins and free T(4) suggests that the increase in free hormone is attributed to a decrease in binding globulins. Changes in TH are most similar to those observed during hibernation than starvation in mammals, suggesting that the metabolic adaptations to natural fasting are more similar to hibernation despite the fact these animals remain active throughout the fasting period.

Inhibition of the Thyroid Hormone Pathway in Xenopus by Mercaptobenzothiazole

EPA Science Inventory

Amphibian metamorphosis is a thyroid hormone-dependent process that provides a potential model system to assess chemicals for their ability to disrupt the hypothalamic-pituitary-thyroid (HPT) axis. Several studies have demonstrated the sensitivity of this system to a variety of ...

Evaluating iodide recycling inhibition as a novel molecular initiating event for thyroid axis disruption

EPA Science Inventory

The enzyme iodotyrosine deiodinase (dehalogenase, IYD) catalyzes iodide recycling and promotes iodide retention in thyroid follicular cells. Loss of function or chemical inhibition of IYD reduces available iodide for thyroid hormone synthesis, which leads to hormone insufficiency...

Thyroid hormonal disturbances related to treatment of hepatitis C with interferon-alpha and ribavirin

PubMed Central

Danilovic, Debora Lucia Seguro; Mendes-Correa, Maria Cassia; Chammas, Maria Cristina; Zambrini, Heverton; Marui, Suemi

2011-01-01

OBJECTIVE: To characterize thyroid disturbances induced by interferon-alpha and ribavirin therapy in patients with chronic hepatitis C. INTRODUCTION: Interferon-alpha is used to treat chronic hepatitis C infections. This compound commonly induces both autoimmune and non-autoimmune thyroiditis. METHODS: We prospectively selected 26 patients with chronic hepatitis C infections. Clinical examinations, hormonal evaluations, and color-flow Doppler ultrasonography of the thyroid were performed before and during antiviral therapy. RESULTS: Of the patients in our study, 54% had no thyroid disorders associated with the interferon-alpha therapy but showed reduced levels of total T3 along with a decrease in serum alanine aminotransferase. Total T4 levels were also reduced at 3 and 12 months, but free T4 and thyroid stimulating hormone (TSH) levels remained stable. A total of 19% of the subjects had autoimmune interferon-induced thyroiditis, which is characterized by an emerge of antithyroid antibodies or overt hypothyroidism. Additionally, 16% had non-autoimmune thyroiditis, which presents as destructive thyroiditis or subclinical hypothyroidism, and 11% remained in a state of euthyroidism despite the prior existence of antithyroidal antibodies. Thyrotoxicosis with destructive thyroiditis was diagnosed within three months of therapy, and ultrasonography of these patients revealed thyroid shrinkage and discordant change in the vascular patterns. DISCUSSION: Decreases in the total T3 and total T4 levels may be related to improvements in the hepatocellular lesions or inflammatory changes similar to those associated with nonthyroidal illnesses. The immune mechanisms and direct effects of interferon-alpha can be associated with thyroiditis. CONCLUSION: Interferon-alpha and ribavirin induce autoimmune and non-autoimmune thyroiditis and hormonal changes (such as decreased total T3 and total T4 levels), which occur despite stable free T4 and TSH levels. A thyroid hormonal evaluation, including the analysis of the free T4, TSH, and antithyroid antibody levels, should be mandatory before therapy, and an early re-evaluation within three months of treatment is necessary as an appropriate follow-up. PMID:22012048

Thyroid hormonal disturbances related to treatment of hepatitis C with interferon-alpha and ribavirin.

PubMed

Danilovic, Debora Lucia Seguro; Mendes-Correa, Maria Cassia; Chammas, Maria Cristina; Zambrini, Heverton; Marui, Suemi

2011-01-01

To characterize thyroid disturbances induced by interferon-alpha and ribavirin therapy in patients with chronic hepatitis C. Interferon-alpha is used to treat chronic hepatitis C infections. This compound commonly induces both autoimmune and non-autoimmune thyroiditis. We prospectively selected 26 patients with chronic hepatitis C infections. Clinical examinations, hormonal evaluations, and color-flow Doppler ultrasonography of the thyroid were performed before and during antiviral therapy. Of the patients in our study, 54% had no thyroid disorders associated with the interferon-alpha therapy but showed reduced levels of total T3 along with a decrease in serum alanine aminotransferase. Total T4 levels were also reduced at 3 and 12 months, but free T4 and thyroid stimulating hormone (TSH) levels remained stable. A total of 19% of the subjects had autoimmune interferon-induced thyroiditis, which is characterized by an emerge of antithyroid antibodies or overt hypothyroidism. Additionally, 16% had non-autoimmune thyroiditis, which presents as destructive thyroiditis or subclinical hypothyroidism, and 11% remained in a state of euthyroidism despite the prior existence of antithyroidal antibodies. Thyrotoxicosis with destructive thyroiditis was diagnosed within three months of therapy, and ultrasonography of these patients revealed thyroid shrinkage and discordant change in the vascular patterns. Decreases in the total T3 and total T4 levels may be related to improvements in the hepatocellular lesions or inflammatory changes similar to those associated with nonthyroidal illnesses. The immune mechanisms and direct effects of interferon-alpha can be associated with thyroiditis. Interferon-alpha and ribavirin induce autoimmune and non-autoimmune thyroiditis and hormonal changes (such as decreased total T3 and total T4 levels), which occur despite stable free T4 and TSH levels. A thyroid hormonal evaluation, including the analysis of the free T4, TSH, and antithyroid antibody levels, should be mandatory before therapy, and an early re-evaluation within three months of treatment is necessary as an appropriate follow-up.

A Rapid Cytoplasmic Mechanism for PI3 Kinase Regulation by the Nuclear Thyroid Hormone Receptor, TRβ, and Genetic Evidence for Its Role in the Maturation of Mouse Hippocampal Synapses In Vivo

PubMed Central

Martin, Negin P.; Fernandez de Velasco, Ezequiel Marron; Mizuno, Fengxia; Scappini, Erica L.; Gloss, Bernd; Erxleben, Christian; Williams, Jason G.; Stapleton, Heather M.; Gentile, Saverio

2014-01-01

Several rapid physiological effects of thyroid hormone on mammalian cells in vitro have been shown to be mediated by the phosphatidylinositol 3-kinase (PI3K), but the molecular mechanism of PI3K regulation by nuclear zinc finger receptor proteins for thyroid hormone and its relevance to brain development in vivo have not been elucidated. Here we show that, in the absence of hormone, the thyroid hormone receptor TRβ forms a cytoplasmic complex with the p85 subunit of PI3K and the Src family tyrosine kinase, Lyn, which depends on two canonical phosphotyrosine motifs in the second zinc finger of TRβ that are not conserved in TRα. When hormone is added, TRβ dissociates and moves to the nucleus, and phosphatidylinositol (3, 4, 5)-trisphosphate production goes up rapidly. Mutating either tyrosine to a phenylalanine prevents rapid signaling through PI3K but does not prevent the hormone-dependent transcription of genes with a thyroid hormone response element. When the rapid signaling mechanism was blocked chronically throughout development in mice by a targeted point mutation in both alleles of Thrb, circulating hormone levels, TRβ expression, and direct gene regulation by TRβ in the pituitary and liver were all unaffected. However, the mutation significantly impaired maturation and plasticity of the Schaffer collateral synapses on CA1 pyramidal neurons in the postnatal hippocampus. Thus, phosphotyrosine-dependent association of TRβ with PI3K provides a potential mechanism for integrating regulation of development and metabolism by thyroid hormone and receptor tyrosine kinases. PMID:24932806

Change of body height is regulated by thyroid hormone during metamorphosis in flatfishes and zebrafish.

PubMed

Xu, Juan; Ke, Zhonghe; Xia, Jianhong; He, Fang; Bao, Baolong

2016-09-15

Flatfishes with more body height after metamorphosis should be better adapted to a benthic lifestyle. In this study, we quantified the changes in body height during metamorphosis in two flatfish species, Paralichthys olivaceus and Platichthys stellatus. The specific pattern of cell proliferation along the dorsal and ventral edge of the body to allow fast growth along the dorsal/ventral axis might be related to the change of body height. Thyroid hormone (T4 and T3) and its receptors showed distribution or gene expression patterns similar to those seen for the cell proliferation. 2-Mercapto-1-methylimidazole, an inhibitor of endogenous thyroid hormone synthesis, inhibited cell proliferation and decreased body height, suggesting that the change in body shape was dependent on the local concentration of thyroid hormone to induce cell proliferation. In addition, after treatment with 2-mercapto-1-methylimidazole, zebrafish larvae were also shown to develop a slimmer body shape. These findings enrich our knowledge of the role of thyroid hormone during flatfish metamorphosis, and the role of thyroid hormone during the change of body height during post-hatching development should help us to understand better the biology of metamorphosis in fishes. Copyright © 2016 Elsevier Inc. All rights reserved.

Intrinsic Regulation of Thyroid Function by Thyroglobulin

PubMed Central

Sellitti, Donald F.

2014-01-01

Background: The established paradigm for thyroglobulin (Tg) function is that of a high molecular weight precursor of the much smaller thyroid hormones, triiodothyronine (T3) and thyroxine (T4). However, speculation regarding the cause of the functional and morphologic heterogeneity of the follicles that make up the thyroid gland has given rise to the proposition that Tg is not only a precursor of thyroid hormones, but that it also functions as an important signal molecule in regulating thyroid hormone biosynthesis. Summary: Evidence supporting this alternative paradigm of Tg function, including the up- or downregulation by colloidal Tg of the transcription of Tg, iodide transporters, and enzymes employed in Tg iodination, and also the effects of Tg on the proliferation of thyroid and nonthyroid cells, is examined in the present review. Also discussed in detail are potential mechanisms of Tg signaling in follicular cells. Conclusions: Finally, we propose a mechanism, based on experimental observations of Tg effects on thyroid cell behavior, that could account for the phenomenon of follicular heterogeneity as a highly regulated cycle of increasing and decreasing colloidal Tg concentration that functions to optimize thyroid hormone production through the transcriptional activation or suppression of specific genes. PMID:24251883

Thyroid hormone use: trends in the United States from 1960 through 1988.

PubMed

Kaufman, S C; Gross, T P; Kennedy, D L

1991-01-01

Thyroid hormone preparations comprised over 1% of all prescriptions filled by retail pharmacies during 1988 in the conterminous United States, i.e., the 48 contiguous states. Their large market share gives the patterns of their use substantial public health importance. This article describes prescription thyroid hormone use in the United States from 1960 through 1988, using pharmaceutical marketing research data collected from panels of retail pharmacies and office-based physicians. Although the use of natural products has declined by over 50% since 1960, about one fourth of all thyroid hormone prescriptions were for natural preparations as recently as 1988. Per capita thyroid mentions (i.e., patient-physician contacts during which a thyroid agent of any kind was recommended, prescribed, dispensed, administered, ordered to be given by a hospital, or given as a sample) doubled during this period among those over 59 years old. Per capita mentions for synthetic thyroid products increased fourfold and tenfold among men and women in this age group, respectively. Use for weight loss, despite the label's boxed warning indicating it to be ineffective and potentially dangerous, has diminished but persists. Obesity was second only to hypothyroidism among the diagnoses underlying thyroid product mentions.

Preoperative Serum Thyrotropin to Thyroglobulin Ratio Is Effective for Thyroid Nodule Evaluation in Euthyroid Patients.

PubMed

Wang, Lina; Li, Hao; Yang, Zhongyuan; Guo, Zhuming; Zhang, Quan

2015-07-01

This study was designed to assess the efficiency of the serum thyrotropin to thyroglobulin ratio for thyroid nodule evaluation in euthyroid patients. Cross-sectional study. Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China. Retrospective analysis was performed for 400 previously untreated cases presenting with thyroid nodules. Thyroid function was tested with commercially available radioimmunoassays. The receiver operating characteristic curves were constructed to determine cutoff values. The efficacy of the thyrotropin:thyroglobulin ratio and thyroid-stimulating hormone for thyroid nodule evaluation was evaluated in terms of sensitivity, specificity, positive predictive value, positive likelihood ratio, negative likelihood ratio, and odds ratio. In receiver operating characteristic curve analysis, the area under the curve was 0.746 for the thyrotropin:thyroglobulin ratio and 0.659 for thyroid-stimulating hormone. With a cutoff point value of 24.97 IU/g for the thyrotropin:thyroglobulin ratio, the sensitivity, specificity, positive predictive value, positive likelihood ratio, and negative likelihood ratio were 78.9%, 60.8%, 75.5%, 2.01, and 0.35, respectively. The odds ratio for the thyrotropin:thyroglobulin ratio indicating malignancy was 5.80. With a cutoff point value of 1.525 µIU/mL for thyroid-stimulating hormone, the sensitivity, specificity, positive predictive value, positive likelihood ratio, and negative likelihood ratio were 74.0%, 53.2%, 70.8%, 1.58, and 0.49, respectively. The odds ratio indicating malignancy for thyroid-stimulating hormone was 3.23. Increasing preoperative serum thyrotropin:thyroglobulin ratio is a risk factor for thyroid carcinoma, and the correlation of the thyrotropin:thyroglobulin ratio to malignancy is higher than that for serum thyroid-stimulating hormone. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.

Thyroid Diseases

MedlinePlus

... beats. All of these activities are your body's metabolism. Thyroid problems include Goiter - enlargement of the thyroid gland Hyperthyroidism - when your thyroid gland makes more thyroid hormones ...

Considering common sources of exposure in association studies - Urinary benzophenone-3 and DEHP metabolites are associated with altered thyroid hormone balance in the NHANES 2007-2008.

PubMed

Kim, Sujin; Kim, Sunmi; Won, Sungho; Choi, Kyungho

2017-10-01

Epidemiological studies have shown that thyroid hormone balances can be disrupted by chemical exposure. However, many association studies have often failed to consider multiple chemicals with possible common sources of exposure, rendering their conclusions less reliable. In the 2007-2008 National Health and Nutrition Examination Survey (NHANES) from the U.S.A., urinary levels of environmental phenols, parabens, and phthalate metabolites as well as serum thyroid hormones were measured in a general U.S. population (≥12years old, n=1829). Employing these data, first, the chemicals or their metabolites associated with thyroid hormone measures were identified. Then, the chemicals/metabolites with possible common exposure sources were included in the analytical model to test the sensitivities of their association with thyroid hormone levels. Benzophenone-3 (BP-3), bisphenol A (BPA), and a metabolite of di(2-ethylhexyl) phthalate (DEHP) were identified as significant determinants of decreased serum thyroid hormones. However, significant positive correlations were detected (p-value<0.05, r=0.23 to 0.45) between these chemicals/metabolites, which suggests that they might share similar exposure sources. In the subsequent sensitivity analysis, which included the chemicals/metabolite with potentially similar exposure sources in the model, we found that urinary BP-3 and DEHP exposure were associated with decreased thyroid hormones among the general population but BPA exposure was not. In association studies, the presence of possible common exposure sources should be considered to circumvent possible false-positive conclusions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Thyroid function, Alzheimer's disease and postoperative cognitive dysfunction: a tale of dangerous liaisons?

PubMed

Mafrica, Federica; Fodale, Vincenzo

2008-05-01

Hypothyroidism and hyperthyroidism are commonly present conditions in adults, leading to neurological symptoms, affecting the central and peripheral nervous system, and to neurocognitive impairment. Several studies investigated a possible association between Alzheimer's disease (AD) and thyroid dysfunctions. Increasing evidence supports an extensive interrelationship between thyroid hormones and the cholinergic system, which is selectively and early affected in AD. Moreover, thyroid hormones negatively regulate expression of the amyloid-beta protein precursor (AbetaPP), which plays a key role in the development of AD. A condition, the so called euthyroid sick syndrome (ESS), characterized by reduced serum T_{3} and T_{4} concentrations without increased serum thyroid stimulation hormone secretion, occurs within hours after major surgery. After surgery, elderly patients often exhibit a transient, reversible state of cognitive alterations. Delirium occurs in 10-26% of general medical patients over 65, and it is associated with a significant increase in morbidity and mortality. Modifications in thyroid hormone functioning may take place as a consequence of psycho-physical stress caused by surgery, and probably as a consequence of reduced conversion of T4 into T3 by the liver engaged in metabolizing anesthetic drugs. Therefore, modifications of thyroid hormones post-surgery, might play a role in the pathogenesis of postoperative cognitive dysfunction.

Thyroid hormone status and pituitary function in adult rats given oral doses of perfluorooctanesulfonate (PFOS)

EPA Science Inventory

Perfluorooctanesulfonate (PFOS) is widely distributed and persistent in humans and wildlife. Prior toxicological studies have reported decreased total and free thyroid hormones in serum without a major compensatory rise in thyrotropin (TSH) or altered thyroid gland histology. Alt...

[Thyroid hormones and the development of the nervous system].

PubMed

Mussa, G C; Zaffaroni, M; Mussa, F

1990-09-01

The growth and differentiation of the central nervous system are closely related to the presence of iodine and thyroid hormones. During the first trimester of human pregnancy the development of the nervous system depends entirely on the availability of iodine; after 12 week of pregnancy it depends on the initial secretion of iodothyronine by the fetal thyroid gland. During the early stages of the development of the nervous system a thyroid hormone deficit may provoke alterations in the maturation of both noble nervous cells (cortical pyramidal cells, Purkinje cells) and glial cells. Hypothyroidism may lead to cellular hypoplasia and reduced dendritic ramification, gemmules and interneuronal connections. Experimental studies in hypothyroid rats have also shown alterations in the content and organization of neuronal intracytoplasmatic microtubules, the biochemical maturation of synaptosomes and the maturation of nuclear and cytoplasmatic T3 receptors. Excess thyroid hormones during the early stages of development may also cause permanent damage to the central nervous system. Hyperthyroidism may initially induce an acceleration of the maturation processes, including the migration and differentiation of cells, the extension of the dendritic processes and synaptogenesis. An excess of thyroid hormones therefore causes neuronal proliferation to end precociously leading to a reduction of the total number of gemmules. Experimental research and clinical studies have partially clarified the correlation between the maturation of the nervous system and thyroid function during the early stages of development; both a deficit and excess of thyroid hormones may lead to permanent anatomo-functional damage to the central nervous system.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue-specific thyroid hormone regulation of gene transcripts encoding iodothyronine deiodinases and thyroid hormone receptors in striped parrotfish (Scarus iseri).

PubMed

Johnson, Kaitlin M; Lema, Sean C

2011-07-01

In fish as in other vertebrates, the diverse functions of thyroid hormones are mediated at the peripheral tissue level through iodothyronine deiodinase (dio) enzymes and thyroid hormone receptor (tr) proteins. In this study, we examined thyroid hormone regulation of mRNAs encoding the three deiodinases dio1, dio2 and dio3 - as well as three thyroid hormone receptors trαA, trαB and trβ - in initial phase striped parrotfish (Scarus iseri). Parrotfish were treated with dissolved phase T(3) (20 nM) or methimazole (3 mM) for 3 days. Treatment with exogenous T(3) elevated circulating T(3), while the methimazole treatment depressed plasma T(4). Experimentally-induced hyperthyroidism increased the relative abundance of transcripts encoding trαA and trβ in the liver and brain, but did not affect trαB mRNA levels in either tissue. In both sexes, methimazole-treated fish exhibited elevated dio2 transcripts in the liver and brain, suggesting enhanced outer-ring deiodination activity in these tissues. Accordingly, systemic hyperthyroidism elevated relative dio3 transcript levels in these same tissues. In the gonad, however, patterns of transcript regulation were distinctly different with elevated T(3) increasing mRNAs encoding dio2 in testicular and ovarian tissues and dio3, trαA and trαB in the testes only. Thyroid hormone status did not affect dio1 transcript abundance in the liver, brain or gonads. Taken as a whole, these results demonstrate that thyroidal status influences relative transcript abundance for dio2 and dio3 in the liver, provide new evidence for similar patterns of dio2 and dio3 mRNA regulation in the brain, and make evident that fish exhibit tr subtype-specific transcript abundance changes to altered thyroid status. Copyright © 2011 Elsevier Inc. All rights reserved.

Influence of thyroid in nervous system growth.

PubMed

Mussa, G C; Mussa, F; Bretto, R; Zambelli, M C; Silvestro, L

2001-08-01

Nervous system growth and differentiation are closely correlated with the presence of iodine and thyroid hormones in initial development stages. In the human species, encephalon maturation during the first quarter of pregnancy is affected according to recent studies by the transplacenta passage of maternal thyroid hormones while it depends on initial iodiothyronin secretion by the foetal gland after the 12th week of pregnancy. Thyroid hormone deficiency during nervous system development causes altered noble nervous cells, such as the pyramidal cortical and Purkinje cells, during glial cell proliferation and differentiation alike. Neurons present cell hypoplasia with reduced axon count, dendritic branching, synaptic spikes and interneuron connections. Oligodendrocytes decrease in number and average myelin content consequently drops. Biochemical studies on hypothyroid rats have demonstrated alterations to neuron intraplasmatic microtubule content and organisation, changed mitochondria number and arrangement and anomalies in T3 nuclear and citoplasmatic receptor maturation. Alterations to microtubules are probably responsible for involvement of the axon-dendrite system, and are the consequence of deficient thyroid hormone action on the mitochondria, the mitochondria enzymes and proteins associated with microtubules. Nuclear and citoplasmatic receptors have been identified and gene clonation studies have shown two families of nuclear receptors that include several sub-groups in their turn. A complex scheme of temporal and spatial expression of these receptors exists, so they probably contribute with one complementary function, although their physiological role differs. The action of thyroid hormones occurs by changing cell protein levels because of their regulation at the transcriptional or post-transcriptional level. Genes submitted to thyroid hormone control are either expressed by oligodendrytes, which are myelin protein coders or glial differentiation mediators, or are nervous cell specific, genes coding neurotropins or proteins involved in synaptic excitation. The use of new PMRS and MRI non-invasive techniques has enabled identification of metabolic and biochemical markers for alterations in the encephalon of untreated hypothyroid children. Even an excess of thyroid hormones during early nervous system development can cause permanent effects. Hyperthyroidism in fact initially induces accelerated maturation process including cell migration and differentiation, extension of dendritic processes and synaptogenesis but a later excess of thyroid hormones causes reduction of the total number of dendritic spikes, due to early interruption of neuron proliferation. Experimental studies and clinical research have clarified not only the correlation between nervous system maturation and thyroid function during early development stages and the certain finding from this research is that both excess and deficient thyroid hormones can cause permanent anatomo-functional alterations to the nervous system.

Thyroid and adrenal relationships

PubMed Central

Parsons, Victor; Ramsay, Ian

1968-01-01

A brief review of the actions of adrenal medullary and thyroid hormones is presented and the ways in which they interact are examined. It is concluded that thyroid hormone produces the necessary intracellular environment without which the steady state and emergency actions of cathecholamines would be vitiated. In hyperthyroidism the increased concentration of thyroid hormones results in a lowering of the threshold for catecholamine action. For this reason it is possible to alleviate many of the symptoms of thyrotoxicosis by means of drugs which block β-adrenergic receptors. Attention is also drawn to the simultaneous occurrence of thyroid and adrenal disease, in the hope that this will encourage the search for further links in this field of endocrinology. PMID:5655216

IN VITRO METABOLISM OF THYROID HORMONES BY RECOMBINANT HUMAN UDP-GLUCORONOSYLTRANSFERASES AND SULFOTRANSFERASES

EPA Science Inventory

Endocrine disruptors can decrease thyroid hormone levels via the induction of hepatic uridinediphosphate-glucoronosyltransferases (UGTs) and sulfotransferases (SULTs). Due to their ability to catalyze glucuronidation and sulfation of hormones and xenobiotics, UGTs and SULTs play ...

Cytophysiological Changes in the Follicular Epithelium of the Thyroid Gland after Long-Term Exposure to Low Doses of Dichlorodiphenyltrichloroethane (DDT).

PubMed

Yaglova, N V; Yaglov, V V

2017-03-01

Exposure to endocrine disruptors is considered as a risk factor thyroid gland diseases. We analyzed cytophysiological changes in rat thyroid follicular epithelium after long-term exposure to low doses of the most widespread disruptor DDT. Analysis of thyroid hormone production and light and electron microscopy of thyroid gland samples revealed cytophysiological changes in thyroid epithelium related to impaired transport through the apical membrane, suppressed Golgi complex activity, and impaired thyrotrophic hormone regulation of the secretory functions of thyroid cells, which led to compensatory transition from merocrine to microapocrine secret release.

[Thyroid and cardiovascular disorders].

PubMed

Zyśko, Dorota; Gajek, Jacek

2004-05-01

In this study three problems concerning interactions between thyroid and cardiovascular system are discussed. Cardiac arrhythmias, congestive heart failure, pleural effusion, hyperlipidaemia, arterial hypertension may be consequences of thyroid disorders leading to inappropriate hormone secretion. During such illnesses as heart failure, myocardial infarction and in patients undergoing coronary artery bypass surgery profound changes may occur in thyroid hormone metabolism known as sick euthyroid syndrome. Treatment with amiodarone may lead to changes in thyroid tests results and to development of hypothyroidism or thyrotoxicosis.

Tissue-engineered thyroid cell sheet rescued hypothyroidism in rat models after receiving total thyroidectomy comparing with nontransplantation models.

PubMed

Arauchi, Ayumi; Shimizu, Tatsuya; Yamato, Masayuki; Obara, Takao; Okano, Teruo

2009-12-01

For hormonal deficiency caused by endocrine organ diseases, continuous oral hormone administration is indispensable to supplement the shortage of hormones. In this study, as a more effective therapy, we have tried to reconstruct the three-dimensional thyroid tissue by the cell sheet technology, a novel tissue engineering approach. The cell suspension obtained from rat thyroid gland was cultured on temperature-responsive culture dishes, from which confluent cells detach as a cell sheet simply by reducing temperature without any enzymatic treatment. The 8-week-old Lewis rats were exposed to total thyroidectomy as hypothyroidism models and received thyroid cell sheet transplantation 1 week after total thyroidectomy. Serum levels of free triiodothyronine (fT(3)) and free thyroxine (fT(4)) significantly decreased 1 week after total thyroidectomy. On the other hand, transplantation of the thyroid cell sheets was able to restore the thyroid function 1 week after the cell sheet transplantation, and improvement was maintained for 4 weeks. Moreover, morphological analyses showed typical thyroid follicle organization, and anti-thyroid-transcription-factor-1 antibody staining demonstrated the presence of follicle epithelial cells. The presence of functional microvessels was also detected within the engineered thyroid tissues. In conclusion, our results indicate that thyroid cell sheets transplanted in a model of total thyroidectomy can reorganize histologically to resemble a typical thyroid gland and restore thyroid function in vivo. In this study, we are the first to confirm that engineered thyroid tissue can repair hypothyroidism models in rats and, therefore, cell sheet transplantation of endocrine organs may be suitable for the therapy of hormonal deficiency.

Developmental thyroid hormone insufficiency and brain development: A role for brain-derived neurotrophic factor (BDNF)?*

EPA Science Inventory

Thyroid hormones (TH) are essential for normal brain development. Even subclinical hypothyroidism experienced in utero can result in neuropsychological deficits in children despite normal thyroid status at birth. Neurotrophins have been implicated in a host of brain cellular func...

Analysis of thyroid hormones in gland and serum using liquid chromatography-tandem mass spectrometry

EPA Science Inventory

Thyroid hormones (THs), which are critical for growth and development in all vertebrates, can be impacted through chemical perturbation of the hypothalamic-pituitary-thyroid (HPT)-axis. Amphibian and mammalian models are being used to address this research priority within US EPA...

Dose-Response Analysis of Developmental Iodide Deficiency: Reductions in Thyroid Hormones and Impaired Hippocampal Synaptic Transmission

EPA Science Inventory

Iodide is an essential nutrient for thyroid hormone synthesis and severe iodide deficiency (ID) during early development is associated with neurological impairments. Several environmental contaminants can perturb the thyroid axis and this perturbation may be more acute under cond...

Quantitative Adverse Outcome Pathway for Neurodevelopmental Effects of Thyroid Peroxidase-Induced Thyroid Hormone Synthesis Inhibition

EPA Science Inventory

Adequate levels of thyroid hormones (TH) are needed for proper brain development and deficiencies lead to adverse neurological outcomes in humans and in animal models. Environmental chemicals have been shown to disrupt TH levels, yet the relationship between developmental exposur...

Vascular and renal function in experimental thyroid disorders.

PubMed

Vargas, Félix; Moreno, Juan Manuel; Rodríguez-Gómez, Isabel; Wangensteen, Rosemary; Osuna, Antonio; Alvarez-Guerra, Miriam; García-Estañ, Joaquín

2006-02-01

This review focuses on the effects of thyroid hormones in vascular and renal systems. Special emphasis is given to the mechanisms by which thyroid hormones affect the regulation of body fluids, vascular resistance and, ultimately, blood pressure. Vascular function is markedly affected by thyroid hormones that produce changes in vascular reactivity and endothelial function in hyper- and hypothyroidism. The hypothyroid state is accompanied by a marked decrease in sensitivity to vasoconstrictors, especially to sympathetic agonists, alteration that may play a role in the reduced blood pressure of hypothyroid rats, as well as in the preventive effects of hypothyroidism on experimental hypertension. Moreover, in hypothyroid rats, the endothelium-dependent and nitric oxide donors vasodilation is reduced. Conversely, the vessels from hyperthyroid rats showed an increased endothelium-dependent responsiveness that may be secondary to the shear-stress induced by the hyperdynamic circulation, and that may contribute to the reduced vascular resistance characteristic of this disease. Thyroid hormones also have important effects in the kidney, affecting renal growth, renal haemodynamics, and salt and water metabolism. In hyperthyroidism, there is a resetting of the pressure-natriuresis relationship related to hyperactivity of the renin-angiotensin system, which contributes to the arterial hypertension associated with this endocrine disease. Moreover, thyroid hormones affect the development and/or maintenance of various forms of arterial hypertension. This review also describes recent advances in our understanding of thyroid hormone action on nitric oxide and oxidative stress in the regulation of cardiovascular and renal function and in the long-term control of blood pressure.

The effects of subchronic acrylamide exposure on gene expression, neurochemistry, hormones, and histopathology in the hypothalamus-pituitary-thyroid axis of male Fischer 344 rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowyer, J.F.; Latendresse, J.R.; Delongchamp, R.R.

Acrylamide (AA) is an important industrial chemical that is neurotoxic in rodents and humans and carcinogenic in rodents. The observation of cancer in endocrine-responsive tissues in Fischer 344 rats has prompted hypotheses of hormonal dysregulation, as opposed to DNA damage, as the mechanism for tumor induction by AA. The current investigation examines possible evidence for disruption of the hypothalamic-pituitary-thyroid axis from 14 days of repeated exposure of male Fischer 344 rats to doses of AA that range from one that is carcinogenic after lifetime exposure (2.5 mg/kg/d), an intermediate dose (10 mg/kg/d), and a high dose (50 mg/kg/d) that ismore » neurotoxic for this exposure time. The endpoints selected include: serum levels of thyroid and pituitary hormones; target tissue expression of genes involved in hormone synthesis, release, and receptors; neurotransmitters in the CNS that affect hormone homeostasis; and histopathological evaluation of target tissues. These studies showed virtually no evidence for systematic alteration of the hypothalamic-pituitary-thyroid axis and do not support hormone dysregulation as a plausible mechanism for AA-induced thyroid cancer in the Fischer 344 rat. Specifically, there were no significant changes in: 1) mRNA levels in hypothalamus or pituitary for TRH, TSH, thyroid hormone receptor {alpha} and {beta}, as well 10 other hormones or releasing factors; 2) mRNA levels in thyroid for thyroglobulin, thyroid peroxidase, sodium iodide symporter, or type I deiodinases; 3) serum TSH or T3 levels (T4 was decreased at high dose only); 4) dopaminergic tone in the hypothalamus and pituitary or importantly 5) increased cell proliferation (Mki67 mRNA and Ki-67 protein levels were not increased) in thyroid or pituitary. These negative findings are consistent with a genotoxic mechanism of AA carcinogenicity based on metabolism to glycidamide and DNA adduct formation. Clarification of this mechanistic dichotomy may be useful in human cancer risk assessments for AA.« less

New Insights into Thyroid Hormone Action

PubMed Central

Mendoza, Arturo; Hollenberg, Anthony N.

2017-01-01

Thyroid hormones (TH) are endocrine messengers essential for normal development and function of virtually every vertebrate. The hypothalamic-pituitary-thyroid axis is exquisitely modulated to maintain nearly constant TH (T4 and T3) concentrations in circulation. However peripheral tissues and the CNS control the intracellular availability of TH, suggesting that circulating concentrations of TH are not fully representative of what each cell type sees. Indeed, recent work in the field has identified that TH transporters, deiodinases and thyroid hormone receptor coregulators can strongly control tissue-specific sensitivity to a set amount of TH. Furthermore, the mechanism by which the thyroid hormone receptors regulate target gene expression can vary by gene, tissue and cellular context. This review will highlight novel insights into the machinery that controls the cellular response to TH, which include unique signaling cascades. These findings shed new light into the pathophysiology of human diseases caused by abnormal TH signaling. PMID:28174093

Prolonged weightlessness effect on postflight plasma thyroid hormones

NASA Technical Reports Server (NTRS)

Leach, C. S.; Johnson, P. C.; Driscoll, T. B.

1977-01-01

Blood drawn before and after spaceflight from the nine Skylab astronauts showed a statistically significant increase in mean plasma thyroxine (T-4) of 1.4 micro g/dl and in thyroid-stimulating hormone (TSH) of 4 microunits ml. Concurrent triiodothyronine (T-3) levels decreased 27 ng/dl indicating inhibited conversion of T-4 to T-3. The T-3 decrease is postulated to be a result of the increased cortisol levels noted during and following each mission. These results confirm the thyroidal changes noted after the shorter Apollo flights and show that thyroid hormone levels change during spaceflight.

Thyroid organotypic rat and human cultures used to investigate drug effects on thyroid function, hormone synthesis and release pathways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vickers, Alison E.M., E-mail: vickers_alison@allergan.com; Heale, Jason; Sinclair, John R.

Drug induced thyroid effects were evaluated in organotypic models utilizing either a rat thyroid lobe or human thyroid slices to compare rodent and human response. An inhibition of thyroid peroxidase (TPO) function led to a perturbation in the expression of key genes in thyroid hormone synthesis and release pathways. The clinically used thiourea drugs, methimazole (MMI) and 6-n-propyl-2-thioruacil (PTU), were used to evaluate thyroid drug response in these models. Inhibition of TPO occurred early as shown in rat thyroid lobes (2 h) and was sustained in both rat (24–48 h) and human (24 h) with ≥ 10 μM MMI. Thyroidmore » from rats treated with single doses of MMI (30–1000 mg/kg) exhibited sustained TPO inhibition at 48 h. The MMI in vivo thyroid concentrations were comparable to the culture concentrations (∼ 15–84 μM), thus demonstrating a close correlation between in vivo and ex vivo thyroid effects. A compensatory response to TPO inhibition was demonstrated in the rat thyroid lobe with significant up-regulation of genes involved in the pathway of thyroid hormone synthesis (Tpo, Dio1, Slc5a5, Tg, Tshr) and the megalin release pathway (Lrp2) by 24 h with MMI (≥ 10 μM) and PTU (100 μM). Similarly, thyroid from the rat in vivo study exhibited an up-regulation of Dio1, Slc5a5, Lrp2, and Tshr. In human thyroid slices, there were few gene expression changes (Slc5a5, ∼ 2-fold) and only at higher MMI concentrations (≥ 1500 μM, 24 h). Extended exposure (48 h) resulted in up-regulation of Tpo, Dio1 and Lrp2, along with Slc5a5 and Tshr. In summary, TPO was inhibited by similar MMI concentrations in rat and human tissue, however an increased sensitivity to drug treatment in rat is indicated by the up-regulation of thyroid hormone synthesis and release gene pathways at concentrations found not to affect human tissue. -- Highlights: ► Novel model of rat thyroid or human thyroid slices to evaluate pathways of injury. ► TPO inhibition by MMI or PTU altered hormone synthesis and release genes. ► Rat thyroid was more sensitive to the drug effects than human tissue.« less

Gene Expression in Developing Brain is Altered by Modest Reductions in Circulating Levels of Thyroid Hormone.

EPA Science Inventory

Disruption of thyroid hormone (TH) homeostasis is a known effect of environmental contaminants. Although animal models of developmental TH deficiency can predict the impact of severe insults to the thyroid system, the effects of moderate TH insufficiencies have not been adequatel...

Gene transcription ontogeny of thyroid-axis development in early-life stage fathead minnows (Pimephales promelas)

EPA Science Inventory

Disruption of thyroid hormone signaling is a form of endocrine disruption that is of concern to both human health and ecosystems. Research is being conducted to define the biological targets chemicals may interact with to disrupt thyroid hormone signaling and the stages in develo...

Predictive Modeling of a Mixture of Thyroid Hormone Disrupting Chemicals that Affect Production and Clearance of Thyroxine

EPA Science Inventory

Thyroid hormone (TH) disrupting compounds interfere with both thyroidal and extrathyroidal mechanisms to decrease circulating thyroxine (T4). This research tested the hypothesis that serum T4 concentrations of rodents exposed to a mixture of both TH synthesis inhibitors (pesticid...

HPLC-ICP/MS Analysis of Thyroid Hormone and Related Iodinated Compounds in Tissues and Media

EPA Science Inventory

Quantifying thyroid hormone (TH) and the synthetic precursors and metabolic products of TH is important for developing models of the hypothalamic-pituitary-thyroid (HPT) axis as well as for understanding the effects of xenobiotics on HPT axis function. In this study, the developm...

Interpreting in vivo Effects of Thyroid Synthesis Inhibitors through the Lens of in vitro and ex vivo Assays

EPA Science Inventory

The US EPA has been charged to evaluate chemicals for their ability to disrupt endocrine pathways including estrogen, androgen, and thyroid hormone. Amphibian metamorphosis, which is regulated by thyroid hormone, is an ideal model system for investigating disruption of the thyroi...

Developmental and cell-specific expression of thyroid hormone transporters in the mouse cochlea.

PubMed

Sharlin, David S; Visser, Theo J; Forrest, Douglas

2011-12-01

Thyroid hormone is essential for the development of the cochlea and auditory function. Cochlear response tissues, which express thyroid hormone receptor β (encoded by Thrb), include the greater epithelial ridge and sensory epithelium residing inside the bony labyrinth. However, these response tissues lack direct blood flow, implying that mechanisms exist to shuttle hormone from the circulation to target tissues. Therefore, we investigated expression of candidate thyroid hormone transporters L-type amino acid transporter 1 (Lat1), monocarboxylate transporter (Mct)8, Mct10, and organic anion transporting polypeptide 1c1 (Oatp1c1) in mouse cochlear development by in situ hybridization and immunofluorescence analysis. L-type amino acid transporter 1 localized to cochlear blood vessels and transiently to sensory hair cells. Mct8 localized to the greater epithelial ridge, tympanic border cells underlying the sensory epithelium, spiral ligament fibrocytes, and spiral ganglion neurons, partly overlapping with the Thrb expression pattern. Mct10 was detected in a highly restricted pattern in the outer sulcus epithelium and weakly in tympanic border cells and hair cells. Organic anion transporting polypeptide 1c1 localized primarily to fibrocytes in vascularized tissues of the spiral limbus and spiral ligament and to tympanic border cells. Investigation of hypothyroid Tshr(-/-) mice showed that transporter expression was delayed consistent with retardation of cochlear tissue maturation but not with compensatory responses to hypothyroidism. The results demonstrate specific expression of thyroid hormone transporters in the cochlea and suggest that a network of thyroid hormone transport underlies cochlear development.

Interactions between the thyroid hormones and the hormones of the growth hormone axis.

PubMed

Laron, Zvi

2003-12-01

The normal secretion and action of the thyroid hormones and the hormones of the GH/IGF-I (growth hormone/ insulin-like growth factor I) axis are interdependent. Their interactions often differ in man from animal studies in rodents and sheep. Thus neonates with congenital hypothyroidism are of normal length in humans but IUGR (intrauterine growth retardation) in sheep. Postnatally normal GH/IGF-I secretion and action depends on an euthyroid state. Present knowledge on the interactions between the two axes is reviewed in states of hypo- and hyperthyroidism, states of GH/IGF-I deprivation and hypersecretion, as well as the relationship between IGF-I and thyroid cancer. Emphasis is given to data in children and aspects of linear growth and skeletal maturation.

[Effect of thyroid hormones on the histotopography of lectin receptors in the rat salivary gland].

PubMed

Lutsik, A D; Iashchenko, A M; Detiuk, E S

1987-04-01

Using lectin-peroxidase technique, the influence of hypo- and hyperthyroidism on histotopography of glycoconjugates has been investigated in rat submandibular gland. The following lectins were used: peanut agglutinin (PNA), wheat germ agglutinin (WGA), Laburnum anagyroides lectin (LAL) and concanavalin A (con A). It has been demonstrated that hyperthyroidism is accompanied by the loss of con A, WGA and LAL receptor sites. Hypothyrodism enhanced con A binding to granular duct cells with a parallel reduction in WGA and LAL binding to these or other duct cells. Hypothyroidism as well as hyperthyroidism markedly enhanced PNA binding to duct epitheliocytes with redistribution of these lectin binding sites from the luminal surface of salivary ducts into the cytoplasm of duct cells. Possible interpretations of the observed phenomena are discussed.

Leptin, NPY, Melatonin and Zinc Levels in Experimental Hypothyroidism and Hyperthyroidism: The Relation to Zinc.

PubMed

Baltaci, Abdulkerim Kasım; Mogulkoc, Rasim

2017-06-01

Since zinc mediates the effects of many hormones or is found in the structure of numerous hormone receptors, zinc deficiency leads to various functional impairments in the hormone balance. And also thyroid hormones have important activity on metabolism and feeding. NPY and leptin are affective on food intake and regulation of appetite. The present study is conducted to determine how zinc supplementation and deficiency affect thyroid hormones (free and total T3 and T4), melatonin, leptin, and NPY levels in thyroid dysfunction in rats. The experiment groups in the study were formed as follows: Control (C); Hypothyroidism (PTU); Hypothyroidism+Zinc (PTU+Zn); Hypothyroidism+Zinc deficient; Hyperthyroidism (H); Hyperthyroidism+Zinc (H+Zn); and Hyperthyroidism+Zinc deficient. Thyroid hormone parameters (FT 3 , FT 4 , TT 3 , and TT 4 ) were found to be reduced in hypothyroidism groups and elevated in the hyperthyroidism groups. Melatonin values increased in hyperthyroidism and decreased in hypothyroidism. Leptin and NPY levels both increased in hypo- and hyperthyroidism. Zinc levels, on the other hand, decreased in hypothyroidism and increased in hyperthyroidism. Zinc supplementation, particularly when thyroid function is impaired, has been demonstrated to markedly prevent these changes.

Maternal phthalate exposure during the first trimester and serum thyroid hormones in pregnant women and their newborns.

PubMed

Yao, Hui-Yuan; Han, Yan; Gao, Hui; Huang, Kun; Ge, Xing; Xu, Yuan-Yuan; Xu, Ye-Qing; Jin, Zhong-Xiu; Sheng, Jie; Yan, Shuang-Qin; Zhu, Peng; Hao, Jia-Hu; Tao, Fang-Biao

2016-08-01

Animal and human studies have suggested that phthalate alters thyroid hormone concentrations. This study investigated the associations between phthalate exposure during the first trimester and thyroid hormones in pregnant women and their newborns. Pregnant women were enrolled from the prospective Ma'anshan Birth Cohort study in China. A standard questionnaire was completed by the women at the first antenatal visit. Seven phthalate metabolites were measured in one-spot urine at enrolment (10.0 ± 2.1 gestational weeks), as were thyroid hormone levels in maternal and cord sera. Multivariable linear regression showed that 1-standard deviation (SD) increase in natural log (ln)-transformed mono(2-ethylhexyl) phthalate (MEHP) and mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) was associated with 0.163 μg/dL (p = 0.001) and 0.173 μg/dL (p = 0.001) decreases in maternal total thyroxine (TT4). Both MEHP and MEHHP were negatively associated with maternal free thyroxine (FT4; β: -0.013, p < 0.001 and β: -0.011, p = 0.001, respectively) and positively associated with maternal thyroid-stimulating hormone (β: 0.101, p < 0.001; β: 0.132, p < 0.001, respectively). An inverse association was observed between monobenzyl phthalate and maternal TT4 and FT4. A 1-SD increase in ln-transformed monoethyl phthalate was inversely associated with maternal TT4 (β: -0.151, p = 0.002). By contrast, the concentrations of phthalate metabolites in urine were not associated with those of thyroid hormone in cord serum. Our analysis suggested that phthalate exposure during the first trimester disrupts maternal thyroid hormone levels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Polybrominated diphenyl ether (PBDE) exposures and thyroid hormones in children at age 3 years.

PubMed

Vuong, Ann M; Braun, Joseph M; Webster, Glenys M; Thomas Zoeller, R; Hoofnagle, Andrew N; Sjödin, Andreas; Yolton, Kimberly; Lanphear, Bruce P; Chen, Aimin

2018-08-01

Polybrominated diphenyl ethers (PBDEs) reduce serum thyroid hormone concentrations in animal studies, but few studies have examined the impact of early-life PBDE exposures on thyroid hormone disruption in childhood. We used data from 162 mother-child pairs from the Health Outcomes and Measures of the Environment Study (2003-2006, Cincinnati, OH). We measured PBDEs in maternal serum at 16 ± 3 weeks gestation and in child serum at 1-3 years. Thyroid hormones were measured in serum at 3 years. We used multiple informant models to investigate associations between prenatal and early-life PBDE exposures and thyroid hormone levels at age 3 years. Prenatal PBDEs were associated with decreased thyroid stimulating hormone (TSH) levels at age 3 years. A 10-fold increase in prenatal ∑PBDEs (BDE-28, -47, -99, -100, and -153) was associated with a 27.6% decrease (95% CI -40.8%, -11.3%) in TSH. A ten-fold increase in prenatal ∑PBDEs was associated with a 0.25 pg/mL (0.07, 0.43) increase in free triiodothyronine (FT 3 ). Child sex modified associations between prenatal PBDEs and thyroid hormones, with significant decrements in TSH among females and decreased free T 4 (FT 4 ) in males. Prenatal ∑PBDEs were not associated with TT 4 , FT 4 , or total T 3 . These findings suggest an inverse relationship between prenatal ∑PBDEs and TSH at 3 years. Associations may be sexually dimorphic, with an inverse relationship between prenatal BDE-47 and -99 and TSH in females and null associations among males. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thyroid hormones states and brain development interactions.

PubMed

Ahmed, Osama M; El-Gareib, A W; El-Bakry, A M; Abd El-Tawab, S M; Ahmed, R G

2008-04-01

The action of thyroid hormones (THs) in the brain is strictly regulated, since these hormones play a crucial role in the development and physiological functioning of the central nervous system (CNS). Disorders of the thyroid gland are among the most common endocrine maladies. Therefore, the objective of this study was to identify in broad terms the interactions between thyroid hormone states or actions and brain development. THs regulate the neuronal cytoarchitecture, neuronal growth and synaptogenesis, and their receptors are widely distributed in the CNS. Any deficiency or increase of them (hypo- or hyperthyroidism) during these periods may result in an irreversible impairment, morphological and cytoarchitecture abnormalities, disorganization, maldevelopment and physical retardation. This includes abnormal neuronal proliferation, migration, decreased dendritic densities and dendritic arborizations. This drastic effect may be responsible for the loss of neurons vital functions and may lead, in turn, to the biochemical dysfunctions. This could explain the physiological and behavioral changes observed in the animals or human during thyroid dysfunction. It can be hypothesized that the sensitive to the thyroid hormones is not only remarked in the neonatal period but also prior to birth, and THs change during the development may lead to the brain damage if not corrected shortly after the birth. Thus, the hypothesis that neurodevelopmental abnormalities might be related to the thyroid hormones is plausible. Taken together, the alterations of neurotransmitters and disturbance in the GABA, adenosine and pro/antioxidant systems in CNS due to the thyroid dysfunction may retard the neurogenesis and CNS growth and the reverse is true. In general, THs disorder during early life may lead to distortions rather than synchronized shifts in the relative development of several central transmitter systems that leads to a multitude of irreversible morphological and biochemical abnormalities (pathophysiology). Thus, further studies need to be done to emphasize this concept.

Lipid profile and thyroid hormone status in the last trimester of pregnancy in single-humped camels (Camelus dromedarius).

PubMed

Omidi, Arash; Sajedi, Zhila; Montazer Torbati, Mohammad Bagher; Ansari Nik, Hossein

2014-04-01

Changes in lipid metabolism have been shown to occur during pregnancy. The thyroid hormones affect lipid metabolism. The present study was carried out to find out whether the last trimester of pregnancy affects thyroid hormones, thyroid-stimulating hormone (TSH), lipid, and lipoprotein profile in healthy dromedary camels. Twenty clinical healthy dromedary camels aged between 4-5 years were divided into two equal groups: (1) pregnant camels in their last trimester of pregnancy and (2) non-pregnant age-matched controls. Thyroid function tests were carried out by measuring serum levels of TSH, free thyroxin (fT4), total thyroxin (T4), free triiodothyronine (fT3), and total triiodothyronine (T3) by commercially available radio immunoassay kits. Total cholesterol (TC), triglyceride (TG), and high-density lipoprotein (HDL) cholesterol were analyzed using enzymatic/spectrophotometric methods while low-density lipoprotein (LDL) cholesterol, very low-density lipoprotein (VLDL), and total lipid (TL) were calculated using Friedewald's and Raylander's formula, respectively. Serum levels of TSH and thyroid hormones except fT4 did not show any significant difference between pregnant and non-pregnant camels. fT4 level was lower in the pregnant camels (P < 0.05). Serum levels of total cholesterol, triglyceride, total lipid, LDL cholesterol, HDL cholesterol, and VLDL did not show significant difference between pregnant and non-pregnant camels. All of these variables in pregnant camels were higher than non-pregnant. Based on the results of this study, the fetus load may not alter the thyroid status of the camel and the concentrations of thyroid hormones were not correlated with TSH and lipid profile levels in the healthy pregnant camels.

Paradigm Shift in Thyroid Hormone Mechanism of Action | Center for Cancer Research

Cancer.gov

Thyroid hormone (TH) is one of the primary endocrine regulators of human metabolism and homeostasis. Acting through three forms of the thyroid hormone receptor (THR; alpha-1, beta-1, and beta-2), TH regulates target gene expression in nearly every cell in the body, modulating fundamental processes, such as basal metabolic rate, long bone growth, and neural maturation. TH is also essential for proper development and differentiation of all cells of the human body.

Higher Thyroid-Stimulating Hormone, Triiodothyronine and Thyroxine Values Are Associated with Better Outcome in Acute Liver Failure

PubMed Central

Sowa, Jan-Peter; Manka, Paul; Katsounas, Antonios; Syn, Wing-Kin; Führer, Dagmar; Gieseler, Robert K.; Bechmann, Lars P.; Gerken, Guido; Moeller, Lars C.; Canbay, Ali

2015-01-01

Introduction Changes in thyroid hormone levels, mostly as non-thyroidal illness syndrome (NTIS), have been described in many diseases. However, the relationship between acute liver failure (ALF) and thyroid hormone levels has not yet been clarified. The present study evaluates potential correlations of select thyroid functional parameters with ALF. Methods 84 consecutively recruited ALF patients were grouped according to the outcome of ALF (spontaneous recovery: SR; transplantation or death: NSR). TSH, free thyroxine (fT4), free triiodothyronine (fT3), T4, and T3 were determined. Results More than 50% of patients with ALF presented with abnormal thyroid parameters. These patients had greater risk for an adverse outcome than euthyroid patients. SR patients had significantly higher TSH, T4, and T3 concentrations than NSR patients. Albumin concentrations were significantly higher in SR than in NSR. In vitro T3 treatment was not able to rescue primary human hepatocytes from acetaminophen induced changes in mRNA expression. Conclusions In patients with ALF, TSH and total thyroid hormone levels differed significantly between SR patients and NSR patients. This might be related to diminished liver-derived transport proteins, such as albumin, in more severe forms of ALF. Thyroid parameters may serve as additional indicators of ALF severity. PMID:26147961

Higher Thyroid-Stimulating Hormone, Triiodothyronine and Thyroxine Values Are Associated with Better Outcome in Acute Liver Failure.

PubMed

Anastasiou, Olympia; Sydor, Svenja; Sowa, Jan-Peter; Manka, Paul; Katsounas, Antonios; Syn, Wing-Kin; Führer, Dagmar; Gieseler, Robert K; Bechmann, Lars P; Gerken, Guido; Moeller, Lars C; Canbay, Ali

2015-01-01

Changes in thyroid hormone levels, mostly as non-thyroidal illness syndrome (NTIS), have been described in many diseases. However, the relationship between acute liver failure (ALF) and thyroid hormone levels has not yet been clarified. The present study evaluates potential correlations of select thyroid functional parameters with ALF. 84 consecutively recruited ALF patients were grouped according to the outcome of ALF (spontaneous recovery: SR; transplantation or death: NSR). TSH, free thyroxine (fT4), free triiodothyronine (fT3), T4, and T3 were determined. More than 50% of patients with ALF presented with abnormal thyroid parameters. These patients had greater risk for an adverse outcome than euthyroid patients. SR patients had significantly higher TSH, T4, and T3 concentrations than NSR patients. Albumin concentrations were significantly higher in SR than in NSR. In vitro T3 treatment was not able to rescue primary human hepatocytes from acetaminophen induced changes in mRNA expression. In patients with ALF, TSH and total thyroid hormone levels differed significantly between SR patients and NSR patients. This might be related to diminished liver-derived transport proteins, such as albumin, in more severe forms of ALF. Thyroid parameters may serve as additional indicators of ALF severity.

Hypothyroidism in Women.

PubMed

Dunn, Donna; Turner, Carla

2016-01-01

Hypothyroidism, a disease in which the thyroid gland does not make enough thyroid hormone, is the second most common endocrine disorder among women. Symptoms of hypothyroidism include fatigue, weight gain, alteration in cognition, infertility, and menstrual abnormalities. The most common cause of hypothyroidism in the United States is Hashimoto's thyroiditis. The American Thyroid Association recommends an initial screening for thyroid disease at age 35years and every 5years thereafter. Thyroid-stimulating hormone is highly sensitive to thyroid dysfunction and is used to evaluate thyroid disorders. Monotherapy with levothyroxine is the standard for treating hypothyroidism. Diagnosing hypothyroidism requires appropriate diagnostic tests to facilitate prompt diagnosis and treatment. © 2016 AWHONN, the Association of Women’s Health, Obstetric and Neonatal Nurses.

Xenopus laevis deiodinase 3 expression for in vitro screening of potential chemical inhibitors

EPA Science Inventory

Thyroid hormones are essential for normal sequential development and metamorphosis of amphibian tissues and organs. Critical to this process are the deiodinase (DIO) enzymes which catalyze the removal of an iodine from thyroid hormones to either activate or inactivate the hormone...

Thyroid Allostasis–Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming

PubMed Central

Chatzitomaris, Apostolos; Hoermann, Rudolf; Midgley, John E.; Hering, Steffen; Urban, Aline; Dietrich, Barbara; Abood, Assjana; Klein, Harald H.; Dietrich, Johannes W.

2017-01-01

The hypothalamus–pituitary–thyroid feedback control is a dynamic, adaptive system. In situations of illness and deprivation of energy representing type 1 allostasis, the stress response operates to alter both its set point and peripheral transfer parameters. In contrast, type 2 allostatic load, typically effective in psychosocial stress, pregnancy, metabolic syndrome, and adaptation to cold, produces a nearly opposite phenotype of predictive plasticity. The non-thyroidal illness syndrome (NTIS) or thyroid allostasis in critical illness, tumors, uremia, and starvation (TACITUS), commonly observed in hospitalized patients, displays a historically well-studied pattern of allostatic thyroid response. This is characterized by decreased total and free thyroid hormone concentrations and varying levels of thyroid-stimulating hormone (TSH) ranging from decreased (in severe cases) to normal or even elevated (mainly in the recovery phase) TSH concentrations. An acute versus chronic stage (wasting syndrome) of TACITUS can be discerned. The two types differ in molecular mechanisms and prognosis. The acute adaptation of thyroid hormone metabolism to critical illness may prove beneficial to the organism, whereas the far more complex molecular alterations associated with chronic illness frequently lead to allostatic overload. The latter is associated with poor outcome, independently of the underlying disease. Adaptive responses of thyroid homeostasis extend to alterations in thyroid hormone concentrations during fetal life, periods of weight gain or loss, thermoregulation, physical exercise, and psychiatric diseases. The various forms of thyroid allostasis pose serious problems in differential diagnosis of thyroid disease. This review article provides an overview of physiological mechanisms as well as major diagnostic and therapeutic implications of thyroid allostasis under a variety of developmental and straining conditions. PMID:28775711

No obvious sympathetic excitation after massive levothyroxine overdose: A case report.

PubMed

Xue, Jianxin; Zhang, Lei; Qin, Zhiqiang; Li, Ran; Wang, Yi; Zhu, Kai; Li, Xiao; Gao, Xian; Zhang, Jianzhong

2018-06-01

Thyrotoxicosis from an overdose of medicinal thyroid hormone is a condition that may be associated with a significant delay in onset of toxicity. However, limited literature is available regarding thyrotoxicosis attributed to excessive ingestion of exogenous thyroid hormone and most cases described were pediatric clinical researches. Herein, we presented the course of a patient who ingested a massive amount of levothyroxine with no obvious sympathetic excited symptoms exhibited and reviewed feasible treatment options for such overdoses. A 41-year-old woman patient with ureteral calculus ingested a massive amount of levothyroxine (120 tablets, equal to 6 mg in total) during her hospitalization. Her transient vital signs were unremarkable after ingestion except for significantly accelerated breathing rate of 45 times per minute. Initial laboratory findings revealed evidently elevated serum levels of thyroxine (T4) >320 nmol/L, free triiodothyronine (fT3) 10.44 pmol/L, and free thyroxine (fT4) >100 pmol/L. The patient had a history of hypothyroidism, which was managed with thyroid hormone replacement (levothyroxine 100 μg per day). Besides, she also suffered from systemic lupus erythematosus and chronic pancreatitis. This is a case of excessive ingestion of exogenous thyroid hormone in an adult. The interventions included use propranolol to prevent heart failure; utilize hemodialysis to remove redundant thyroid hormone from blood; closely monitor the vital signs, basal metabolic rate, blood biochemical indicators, and serum levels of thyroid hormone. The woman had no obvious symptoms of thyrotoxicosis. After 4 weeks, the results of thyroid function indicated that serum thyroid hormone levels were completely recovered to pre-ingestion levels. Accordingly, the levothyroxine was used again as before. Adults often exhibit more severe symptoms after intaking overdose levothyroxine due to their complex medical history and comorbidities than children. As for them, hemodialysis should be considered as soon as possible. Besides, diverse treatments according to specific symptoms and continuously monitoring were indispensable.

[Iodine and thyroid gland with or without nuclear catastrophe].

PubMed

Dilas, Ljiljana Todorović; Bajkin, Ivana; Icin, Tijana; Paro, Jovanka Novaković; Zavisić, Branka Kovacev

2012-01-01

Iodine, as a trace element, is a necessary and limiting substrate for thyroid gland hormone synthesis. It is an essential element that enables the thyroid gland to produce thyroid hormones thyroxine (T4) and triiodothyronine (T3). Synthesis of Thyroid Hormones and Iodine Metabolism. Three iodine molecules are added to make triiodothyronine, and four for thyroxine - the two key hormones produced by the thyroid gland. Iodine deficiency The proper daily amount of iodine is required for optimal thyroid function. Iodine deficiency can cause hypothyroidism, developmental brain disorders and goiter. Iodine deficiency is the single most common cause of preventable mental retardation and brain damage in the world. It also decreases child survival, causes goiters, and impairs growth and development. Iodine deficiency disorders in pregnant women cause miscarriages, stillbirths, and other complications. Children with iodine deficiency disorders can grow up stunted, apathetic, mentally retarded, and incapable of normal movements, speech or hearing. Excessive Iodine Intake. Excessive iodine intake, which can trigger a utoimmune thyroid disease and dysfunction. is on the other side. Iodine use in Case of Nuclear Catastrophe. In addition to other severe consuquences of radioactivity, high amount of radioactive iodine causes significant increase in incidence of thyroid gland carcinoma after some of the nuclear catastrophes (Hiroshima, Nagasaki, Chernobyl, Fukushima). The incidence of thyroid carcinoma was increased mostly in children. This paper was aimed at clarifying some of the possibilities of prevention according to the recommendations given by the World Health Organization.

Comparison of the in vitro effects of TCDD, PCB 126 and PCB 153 on thyroid-restricted gene expression and thyroid hormone secretion by the chicken thyroid gland.

PubMed

Katarzyńska, Dorota; Hrabia, Anna; Kowalik, Kinga; Sechman, Andrzej

2015-03-01

The aim of this study was to compare the in vitro effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3,3',4,4',5-pentachlorobiphenyl (PCB 126; a coplanar PCB congener) and 2,2'4,4',5,5'-hexachlorobiphenyl (PCB153; non-coplanar PCB) on mRNA expression of thyroid-restricted genes, i.e. sodium iodide symporter (NIS), thyroid peroxidase (TPO) and thyroglobulin (TG), and thyroid hormone secretion from the thyroid gland of the laying chicken. Relative expression levels of NIS, TG and TPO genes and thyroxine (T4) and triiodothyronine (T3) secretion from the thyroidal explants were quantified by the real-time qPCR and RIA methods, respectively. In comparison with the control group, TCDD and PCB 126 significantly increased mRNA expression of TPO and TG genes. TCDD did not affect NIS mRNA levels, but PCB 126 decreased its expression. No effect of PCB 153 on the expression of these genes was observed. TCDD and PCB 126 significantly decreased T4 and T3 secretion. There was no significant effect of PCB 153 on these hormone secretions. In conclusion, the results obtained show that in comparison with non-coplanar PCB 153, TCDD and coplanar PCB 126 can directly affect thyroid hormone synthesis and secretion, and in consequence, they may disrupt the endocrine function of the thyroid gland of the laying chicken. Copyright © 2015 Elsevier B.V. All rights reserved.

APPLICATION OF ORGANIC IODINE SPECIES ANALYTICS: DETERMINING THYROID HORMONE STATUS IN ADULT DANIO RERIO AND DEVELOPING XENOPUS LAEVIS USING LC/ICP-MS

EPA Science Inventory

Disruption of normal thyroid function by xenobiotic chemicals is an important ecological issue. Theoretically, normal thyroid hormone (TH) homeostasis and action can be disrupted at several sites in the synthetic and elimination pathways. Indeed, xenobiotic chemicals, which are k...

Gene transcription ontogeny of hypothalamic-pituitary-thyroid-axis development in early-life stage fathead minnow and zebrafish

EPA Science Inventory

Disruption of thyroid hormone signaling is a form of endocrine disruption that is of concern to both human health and ecosystems. Research is being conducted to define the biological targets chemicals may interact with to disrupt thyroid hormone signaling and the stages in develo...

Thyroid Surgery

MedlinePlus

... thyroid surgery, requiring treatment with thyroid hormone (see Hypothyroidism brochure ). This is especially true if you had ... Disease Graves’ Eye Disease Hashimoto’s Thyroiditis Hyperthyroidism (Overactive) Hypothyroidism (Underactive) Iodine Deficiency Low Iodine Diet Medullary Thyroid ...

Mild Thyroid Hormone Insufficiency During Development Compromises Activity-Dependent Neuroplasticity in the Hippocampus of Adult Male Rats

EPA Pesticide Factsheets

behavioral measures of learning and memory in adult offspring of rats treated with thyroid hormone synthesis inhibitor, propylthiouracil.Electrophysiological measures of 'memory' in form of plasticity model known as long term potentiation (LTP)Molecular changes induced by LTPThis dataset is associated with the following publication:Gilbert , M., K. Sanchez-Huerta, and C. Wood. Mild Thyroid Hormone Insufficiency During Development Compromises Activity-Dependent Neuroplasticity in the Hippocampus of Adult Make Rats. ENDOCRINOLOGY. Endocrine Society, 157(2): 774-87, (2016).

SEX-STEROID AND THYROID HORMONE CONCENTRATIONS IN JUVENILE ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) FROM CONTAMINATED AND REFERENCE LAKES IN FLORIDA, USA

EPA Science Inventory

Sex-steroid and thyroid hormones are critical regulators of growth and reproduction in all vertebrates, and several recent studies suggest that environmental chemicals can alter circulating concentrations of these hormones. This study examines plasma concentrations of estradiol-...

THYROID HORMONE INSUFFICIENCY AND BRAIN DEVELOPMENT -- DETERMINATION OF NEUROTOXICITY AT LOW LEVELS OF HORMONE DISRUPTION.

EPA Science Inventory

Thyroid hormone (TH) deficiencies during development produce deleterious effects on brain structure and function. The degree to which TH must be perturbed to induce neurotoxicity remains unclear. The present study was conducted as part of a Cooperative Agreement between US EPA, U...

Exposure to PFDoA causes disruption of the hypothalamus-pituitary-thyroid axis in zebrafish larvae.

PubMed

Zhang, Shengnan; Guo, Xiaochun; Lu, Shaoyong; Sang, Nan; Li, Guangyu; Xie, Ping; Liu, Chunsheng; Zhang, Liguo; Xing, Yi

2018-04-01

Perfluorododecanoic acid (PFDoA), a kind of perfluorinated carboxylic acid (PFCA) with 12 carbon atoms, has an extensive industrial utilization and is widespread in both wildlife and the water environment, and was reported to have the potential to cause a disruption in the thyroid hormone system homeostasis. In this study, zebrafish embryos/larvae were exposed to different concentrations of PFDoA (0, 0.24, 1.2, 6 mg/L) for 96 h post-fertilization (hpf). PFDoA exposure caused obvious growth restriction connected with the reduced thyroid hormones (THs) contents in zebrafish larvae, strengthening the interference effect on the growth of fish larvae. The transcriptional level of genes within the hypothalamic-pituitary-thyroid (HPT) axis was analyzed. The gene expression levels of thyrotropin-releasing hormone (trh) and corticotrophin-releasing hormone (crh) were upregulated upon exposure to 6 mg/L of PFDoA, and iodothyronine deiodinases (dio2) was upregulated in the 1.2 mg/L PFDoA group. The transcription of thyroglobulin (tg) and thyroid receptor (trβ) were significantly downregulated upon exposure to 1.2 mg/L and 6 mg/L of PFDoA. PFDoA could also decrease the levels of sodium/iodide symporter (nis) and transthyretin (ttr) gene expression in a concentration-dependent manner after exposure. A significant decrease in thyroid-stimulating hormoneβ (tshβ), uridinediphosphate-glucuronosyltransferase (ugt1ab) and thyroid receptor (trα) gene expression were observed at 6 mg/L PFDoA exposure. Upregulation and downregulation of iodothyronine deiodinases (dio1) gene expression were observed upon the treatment of 1.2 mg/L and 6 mg/L PFDoA, respectively. All the data demonstrated that gene expression in the HPT axis altered after different PFDoA treatment and the potential mechanisms of the disruption of thyroid status could occur at several steps in the process of synthesis, regulation, and action of thyroid hormones. Copyright © 2018 Elsevier Ltd. All rights reserved.

Exercise training versus T3 and T4 hormones treatment: The differential benefits of thyroid hormones on the parasympathetic drive of infarcted rats.

PubMed

Teixeira, Rayane Brinck; Zimmer, Alexsandra; de Castro, Alexandre Luz; Carraro, Cristina Campos; Casali, Karina Rabello; Dias, Ingrid Gonçalves Machuca; Godoy, Alessandra Eifler Guerra; Litvin, Isnard Elman; Belló-Klein, Adriane; da Rosa Araujo, Alex Sander

2018-03-01

This study aimed to investigate whether beneficial effects of thyroid hormones are comparable to those provided by the aerobic exercise training, to verify its applicability as a therapeutic alternative to reverse the pathological cardiac remodeling post-infarction. Male rats were divided into SHAM-operated (SHAM), myocardial infarction (MI), MI subjected to exercise training (MIE), and MI who received T3 and T4 treatment (MIH) (n = 8/group). MI, MIE and MIH groups underwent an infarction surgery while SHAM was SHAM-operated. One-week post-surgery, MIE and MIH groups started the exercise training protocol (moderate intensity on treadmill), or the T3 (1.2 μg/100 g/day) and T4 (4.8 μg/100 g/day) hormones treatment by gavage, respectively, meanwhile SHAM and MI had no intervention for 9 weeks. The groups were accompanied until 74 days after surgery, when all animals were anesthetized, left ventricle echocardiography and femoral catheterization were performed, followed by euthanasia and left ventricle collection for morphological, oxidative stress, and intracellular kinases expression analysis. Thyroid hormones treatment was more effective in cardiac dilation and infarction area reduction, while exercise training provided more protection against fibrosis. Thyroid hormones treatment increased the lipoperoxidation and decreased GSHPx activity as compared to MI group, increased the t-Akt2 expression as compared to SHAM group, and increased the vascular parasympathetic drive. Thyroid hormones treatment provided differential benefits on the LV function and autonomic modulation as compared to the exercise training. Nevertheless, the redox unbalance induced by thyroid hormones highlights the importance of more studies targeting the ideal duration of this treatment. Copyright © 2018 Elsevier Inc. All rights reserved.

The Bottlenose Dolphin (Tursiops truncatus) as a Model to Understand Variation in Stress and Reproductive Hormone Measures in Relation to Sampling Matrix, Demographics, and Environmental Factors

DTIC Science & Technology

2013-09-30

physiological processes driven by the GCs are essential for an individual’s ability to respond and adapt to stress, prolonged elevation of GC hormones...capture-release health assessments. Stress and reproductive hormones (cortisol, aldosterone , thyroid, testosterone, progesterone) have been routinely...ACE) Basin, also in South Carolina. Laboratory Analyses Hormone concentrations (cortisol, aldosterone , reproductive and thyroid hormones) in

The thyroid and environmental stress in mammals

NASA Technical Reports Server (NTRS)

Galton, V. A.

1977-01-01

The effects of hyperoxia at ambient pressure on thyroid function and thyroid hormone metabolism have been assessed. Thyroidal activity was depressed in mice and rats by exposure to hyperoxia, due at least in part to a decrease in the rate of secretion of pituitary thyrotropin. The effects of hyperoxia on the peripheral deiodination of thyroxine were dependent on the concentration of oxygen employed and/or the duration of exposure. When significant changes were observed a reduction in the rate of deiodination and in the deiodinative clearance of T sub 4 occurred. Hyperoxia also resulted in a marked fall in circulating T sub 4 concentration and a decrease in T sub 4-binding activity in serum. Many of these effects of hyperoxia were prevented by the concomitant administration of large amounts of Vitamin E. These decreases in thyroid function and T sub 4 metabolism were associated with a decrease in the rate of whole body oxygen consumption. It was concluded that the deleterious effects of oxygen in the rat were not due to an oxygen induced hyperthyroid state in the peripheral tissues. Thyroxine was shown to be essential for survival during acute cold stress.

Pharmacokinetics and pharmacotherapy of thionamides in pregnancy.

PubMed

Clark, Shannon M; Saade, George R; Snodgrass, Wayne R; Hankins, Gary D V

2006-08-01

Hyperthyroidism occurs in approximately 1 in every 1000 to 2000 pregnancies. Although the signs and symptoms of the disease are similar in the pregnant and nonpregnant patient, the complications of hyperthyroidism can have even more profound consequences for the mother and fetus during gestation. These include maternal heart failure, preeclampsia, miscarriage, and preterm labor; as well as fetal loss and low birth weight. Furthermore, thyroid function and laboratory testing for hyperthyroidism are altered in pregnancy. The gestational increase in thyroid size, increased thyroid-binding globulin levels, increased serum total T4 and total T3 levels, and decreased thyroid stimulating hormone levels often confuses the evaluation of the thyroid status in pregnancy. Worldwide, the thionamides-propylthiouracil, methimazole, and carbimazole-have been used in pregnancy for the treatment of hyperthyroidism. However, propylthiouracil has been the drug of choice in the United States because it is believed to have less potential to induce fetal/neonatal hypothyrodism, to cross the placenta and into breast milk to a lesser degree, and to be less teratogenic than methimazole or carbimazole. None of the above have been substantiated in more recent studies. The pharmacokinetics of the thionamides in the pregnant and nonpregnant states, as well as the pharmacotherapeutic recommendation for hyperthyroidism will be reviewed.

Analysis of iodine-131-induced early thyroid hormone variations in Graves' disease.

PubMed

Xu, Feng; Gu, Aichun; Pan, Yifan; Yang, Liwen; Ma, Yubo

2016-11-01

This prospective study aimed to assess iodine-131 (I)-induced early thyroid hormone variations in Graves' disease (GD) and determine the associated factors. One hundred and seventy-one GD patients treated with I were evaluated (47 men, 124 women). I was administered at 9.0±4.9 mCi on average. Serum free triiodothyronine and free thyroxin were measured within 24 h before treatment and 8 (3-14) days after treatment. Patients were divided into increase, no change, and decrease groups, respectively, on the basis of hormone variations after treatment. χ-Test, analysis of variance, and the Kruskal-Wallis test were used to compare groups in terms of sex, age, course of disease, thyroid stimulating hormone receptor antibodies, antithyroid drug (ATD) pretreatment time, time of ATD discontinuation before I treatment, 24 h thyroid I uptake, thyroid weight, I activity, and I activity/thyroid weight (μCi/g). The Spearman method was used for correlation analyses. Twenty-seven, 20, and 124 cases were assigned to increase, no change, and decrease groups, respectively. Significant differences were found among groups in the time of ATD discontinuation before I treatment [the median duration for methimazole was 11 (5-26), 16 (10-30), and 21 (1-30) days, P=0.000, the median duration for propylthiouracil was 12.5 (5-24), 22 (11-26), and 26 (21-30) days, P=0.000], thyroid weight (93.5±33.6, 90.3±48.8, and 74.1±26.0 g, P=0.003), and μCi/g (84.8±11.8, 100.4±24.9, and 121.1±44.0 μCi/g, P=0.000). Interestingly, μCi/g was negatively and positively correlated to the possibility of hormone increase and decrease, respectively. No significant differences were found in the other parameters assessed. At the early stage of I treatment for GD, few patients showed increased thyroid hormone levels. Key factors may include time of ATD discontinuation before I treatment and μCi/g. High μCi/g might decrease thyroid hormone levels in early treatment, making it safe.

Thyroid-stimulating hormone and adverse left ventricular remodeling following ST-segment elevation myocardial infarction.

PubMed

Reindl, Martin; Feistritzer, Hans-Josef; Reinstadler, Sebastian Johannes; Mueller, Lukas; Tiller, Christina; Brenner, Christoph; Mayr, Agnes; Henninger, Benjamin; Mair, Johannes; Klug, Gert; Metzler, Bernhard

2018-04-01

Adverse left ventricular remodeling is one of the major determinants of heart failure and mortality in patients surviving ST-segment elevation myocardial infarction (STEMI). The hypothalamic-pituitary-thyroid axis is a key cardiovascular regulator; however, the relationship between hypothalamic-pituitary-thyroid status and post-STEMI left ventricular remodeling is unclear. We aimed to investigate the association between thyroid-stimulating hormone concentrations and the development of left ventricular remodeling following reperfused STEMI. In this prospective observational study of 102 consecutive STEMI patients, thyroid-stimulating hormone levels were measured at the first day after infarction and 4 months thereafter. Cardiac magnetic resonance scans were performed within the first week as well as at 4 months follow-up to determine infarct characteristics, myocardial function and as primary endpoint left ventricular remodeling, defined as a 20% or greater increase in left ventricular end-diastolic volume. Patients with left ventricular remodeling ( n=15, 15%) showed significantly lower concentrations of baseline (1.20 [0.92-1.91] vs. 1.73 [1.30-2.60] mU/l; P=0.02) and follow-up (1.11 [0.86-1.28] vs. 1.51 [1.15-2.02] mU/l; P=0.002) thyroid-stimulating hormone. The association between baseline thyroid-stimulating hormone and left ventricular remodeling remained significant after adjustment for major clinical (peak high-sensitivity cardiac troponin T and C-reactive protein, heart rate; odds ratio (OR) 5.33, 95% confidence interval (CI) 1.52-18.63; P=0.01) and cardiac magnetic resonance predictors of left ventricular remodeling (infarct size, microvascular obstruction, ejection fraction; OR 4.59, 95% CI 1.36-15.55; P=0.01). Furthermore, chronic thyroid-stimulating hormone was related to left ventricular remodeling independently of chronic left ventricular remodeling correlates (infarct size, ejection fraction, left ventricular end-diastolic volume, left ventricular end-systolic volume; OR 9.22, 95% CI 1.69-50.22; P=0.01). Baseline and chronic thyroid-stimulating hormone concentrations following STEMI were independently associated with left ventricular remodeling, proposing a novel pathophysiological axis in the development of post-STEMI left ventricular remodeling.

Regulation of mammary gland sensitivity to thyroid hormones during the transition from pregnancy to lactation.

PubMed

Capuco, A V; Connor, E E; Wood, D L

2008-10-01

Thyroid hormones are galactopoietic and help to establish the mammary gland's metabolic priority during lactation. Expression patterns for genes that can alter tissue sensitivity to thyroid hormones and thyroid hormone activity were evaluated in the mammary gland and liver of cows at 53, 35, 20, and 7 days before expected parturition, and 14 and 90 days into the subsequent lactation. Transcript abundance for the three isoforms of iodothyronine deiodinase, type I (DIO1), type II (DIO2) and type III (DIO3), thyroid hormone receptors alpha1 (TRalpha1), alpha2 (TRalpha2) and beta1 (TRbeta1), and retinoic acid receptors alpha (RXRalpha) and gamma (RXRgamma), which act as coregulators of thyroid hormone receptor action, were evaluated by quantitative RT-PCR. The DIO3 is a 5-deiodinase that produces inactive iodothyronine metabolites, whereas DIO1 and DIO2 generate the active thyroid hormone, triiodothyronine, from the relatively inactive precursor, thyroxine. Low copy numbers of DIO3 transcripts were present in mammary gland and liver. DIO2 was the predominant isoform expressed in mammary gland and DIO1 was the predominant isoform expressed in liver. Quantity of DIO1 mRNA in liver tissues did not differ with physiological state, but tended to be lowest during lactation. Quantity of DIO2 mRNA in mammary gland increased during lactation (P < 0.05), with copy numbers at 90 days of lactation 6-fold greater than at 35 and 20 days prepartum. When ratios of DIO2/DIO3 mRNA were evaluated, the increase was more pronounced (>100-fold). Quantity of TRbeta1 mRNA in mammary gland increased with onset of lactation, whereas TRalpha1 and TRalpha2 transcripts did not vary with physiological state. Conversely, quantity of RXRalpha mRNA decreased during late gestation to low levels during early lactation. Data suggest that increased expression of mammary TRbeta1 and DIO2, and decreased RXRalpha, provide a mechanism to increase thyroid hormone activity within the mammary gland during lactation.

Low thyroid function is not associated with an accelerated deterioration in renal function.

PubMed

Meuwese, Christiaan L; van Diepen, Merel; Cappola, Anne R; Sarnak, Mark J; Shlipak, Michael G; Bauer, Douglas C; Fried, Linda P; Iacoviello, Massimo; Vaes, Bert; Degryse, Jean; Khaw, Kay-Tee; Luben, Robert N; Åsvold, Bjørn O; Bjøro, Trine; Vatten, Lars J; de Craen, Anton J M; Trompet, Stella; Iervasi, Giorgio; Molinaro, Sabrina; Ceresini, Graziano; Ferrucci, Luigi; Dullaart, Robin P F; Bakker, Stephan J L; Jukema, J Wouter; Kearney, Patricia M; Stott, David J; Peeters, Robin P; Franco, Oscar H; Völzke, Henry; Walsh, John P; Bremner, Alexandra; Sgarbi, José A; Maciel, Rui M B; Imaizumi, Misa; Ohishi, Waka; Dekker, Friedo W; Rodondi, Nicolas; Gussekloo, Jacobijn; den Elzen, Wendy P J

2018-04-18

Chronic kidney disease (CKD) is frequently accompanied by thyroid hormone dysfunction. It is currently unclear whether these alterations are the cause or consequence of CKD. This study aimed at studying the effect of thyroid hormone alterations on renal function in cross-sectional and longitudinal analyses in individuals from all adult age groups. Individual participant data (IPD) from 16 independent cohorts having measured thyroid stimulating hormone, free thyroxine levels and creatinine levels were included. Thyroid hormone status was defined using clinical cut-off values. Estimated glomerular filtration rates (eGFR) were calculated by means of the four-variable Modification of Diet in Renal Disease (MDRD) formula. For this IPD meta-analysis, eGFR at baseline and eGFR change during follow-up were computed by fitting linear regression models and linear mixed models in each cohort separately. Effect estimates were pooled using random effects models. A total of 72 856 individuals from 16 different cohorts were included. At baseline, individuals with overt hypothyroidism (n = 704) and subclinical hypothyroidism (n = 3356) had a average (95% confidence interval) -4.07 (-6.37 to -1.78) and -2.40 (-3.78 to -1.02) mL/min/1.73 m2 lower eGFR as compared with euthyroid subjects (n = 66 542). In (subclinical) hyperthyroid subjects (n = 2254), average eGFR was 3.01 (1.50-4.52) mL/min/1.73 m2 higher. During 329 713 patient years of follow-up, eGFR did not decline more rapidly in individuals with low thyroid function compared with individuals with normal thyroid function. Low thyroid function is not associated with a deterioration of renal function. The cross-sectional association may be explained by renal dysfunction causing thyroid hormone alterations.

The thyroid hormone triiodothyronine controls macrophage maturation and functions: protective role during inflammation.

PubMed

Perrotta, Cristiana; Buldorini, Marcella; Assi, Emma; Cazzato, Denise; De Palma, Clara; Clementi, Emilio; Cervia, Davide

2014-01-01

The endocrine system participates in regulating macrophage maturation, although little is known about the modulating role of the thyroid hormones. In vitro results demonstrate a negative role of one such hormone, triiodothyronine (T3), in triggering the differentiation of bone marrow-derived monocytes into unpolarized macrophages. T3-induced macrophages displayed a classically activated (M1) signature. A T3-induced M1-priming effect was also observed on polarized macrophages because T3 reverses alternatively activated (M2) activation, whereas it enhances that of M1 cells. In vivo, circulating T3 increased the content of the resident macrophages in the peritoneal cavity, whereas it reduced the content of the recruited monocyte-derived cells. Of interest, T3 significantly protected mice against endotoxemia induced by lipopolysaccharide i.p. injection; in these damaged animals, decreased T3 levels increased the recruited (potentially damaging) cells, whereas restoring T3 levels decreased recruited and increased resident (potentially beneficial) cells. These data suggest that the anti-inflammatory effect of T3 is coupled to the modulation of peritoneal macrophage content, in a context not fully explained by the M1/M2 framework. Thyroid hormone receptor expression analysis and the use of different thyroid hormone receptor antagonists suggest thyroid hormone receptor β1 as the major player mediating T3 effects on macrophages. The novel homeostatic link between thyroid hormones and the pathophysiological role of macrophages opens new perspectives on the interactions between the endocrine and immune systems. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Developmental and Cell-Specific Expression of Thyroid Hormone Transporters in the Mouse Cochlea

PubMed Central

Sharlin, David S.; Visser, Theo J.

2011-01-01

Thyroid hormone is essential for the development of the cochlea and auditory function. Cochlear response tissues, which express thyroid hormone receptor β (encoded by Thrb), include the greater epithelial ridge and sensory epithelium residing inside the bony labyrinth. However, these response tissues lack direct blood flow, implying that mechanisms exist to shuttle hormone from the circulation to target tissues. Therefore, we investigated expression of candidate thyroid hormone transporters L-type amino acid transporter 1 (Lat1), monocarboxylate transporter (Mct)8, Mct10, and organic anion transporting polypeptide 1c1 (Oatp1c1) in mouse cochlear development by in situ hybridization and immunofluorescence analysis. L-type amino acid transporter 1 localized to cochlear blood vessels and transiently to sensory hair cells. Mct8 localized to the greater epithelial ridge, tympanic border cells underlying the sensory epithelium, spiral ligament fibrocytes, and spiral ganglion neurons, partly overlapping with the Thrb expression pattern. Mct10 was detected in a highly restricted pattern in the outer sulcus epithelium and weakly in tympanic border cells and hair cells. Organic anion transporting polypeptide 1c1 localized primarily to fibrocytes in vascularized tissues of the spiral limbus and spiral ligament and to tympanic border cells. Investigation of hypothyroid Tshr−/− mice showed that transporter expression was delayed consistent with retardation of cochlear tissue maturation but not with compensatory responses to hypothyroidism. The results demonstrate specific expression of thyroid hormone transporters in the cochlea and suggest that a network of thyroid hormone transport underlies cochlear development. PMID:21878515

Thyroid hormones regulate anxiety in the male mouse.

PubMed

Buras, Alexander; Battle, Loxley; Landers, Evan; Nguyen, Tien; Vasudevan, Nandini

2014-02-01

Thyroid hormone levels are implicated in mood disorders in the adult human but the mechanisms remain unclear partly because, in rodent models, more attention has been paid to the consequences of perinatal hypo and hyperthyroidism. Thyroid hormones act via the thyroid hormone receptor (TR) α and β isoforms, both of which are expressed in the limbic system. TR's modulate gene expression via both unliganded and liganded actions. Though the thyroid hormone receptor (TR) knockouts and a transgenic TRα1 knock-in mouse have provided us valuable insight into behavioral phenotypes such as anxiety and depression, it is not clear if this is because of the loss of unliganded actions or liganded actions of the receptor or due to locomotor deficits. We used a hypothyroid mouse model and supplementation with tri-iodothyronine (T3) or thyroxine (T4) to investigate the consequences of dysthyroid hormone levels on behaviors that denote anxiety. Our data from the open field and the light-dark transition tests suggest that adult onset hypothyroidism in male mice produces a mild anxiogenic effect that is possibly due to unliganded receptor actions. T3 or T4 supplementation reverses this phenotype and euthyroid animals show anxiety that is intermediate between the hypothyroid and thyroid hormone supplemented groups. In addition, T3 but not T4 supplemented animals have lower spine density in the CA1 region of the hippocampus and in the central amygdala suggesting that T3-mediated rescue of the hypothyroid state might be due to lower neuronal excitability in the limbic circuit. Copyright © 2013 Elsevier Inc. All rights reserved.

Fetal and neonatal thyrotoxicosis

PubMed Central

Batra, Chandar Mohan

2013-01-01

Fetal thyrotoxicosis is a rare disease occurring in 1 out of 70 pregnancies with Grave's disease or in 1 out of 4000-50,000 deliveries. The mortality is 12-20%, usually from heart failure, but other complications are tracheal compression, infections and thrombocytopenia. It results from transfer of thyroid stimulating immunoglobulins from mother to fetus through the placenta. This transplacental transfer begins around 20th week of pregnancy and reaches its maximum by 30th week. These autoantibodies bind to the fetal thyroid stimulating hormone (TSH) receptors and increase the secretion of the thyroid hormones. The mother has an active autoimmune thyroid disease or has been treated for it in the past. She may be absolutely euthyroid due to past treatment by drugs, surgery or radioiodine ablation, but still have active TSH receptor stimulating autoantibodies, which can cause fetal thyrotoxicosis. The other features of this disease are fetal tachycardia, fetal goiter and history of spontaneous abortions and findings of goiter, ascites, craniosyntosis, fetal growth retardation, maceration and hydrops at fetal autopsy. If untreated, this disease can result in intrauterine death. The treatment for this disease consists of giving carbimazole to the mother, which is transferred through the placenta to the fetus. The dose of carbimazole is titrated with the fetal heart rate. If the mother becomes hypothyroid due to carbimazole, thyroxine is added taking advantage of the fact that very little of thyroxine is transferred across the placenta. Neonatal thyrotoxicosis patients are very sick and require emergency treatment. The goal of the treatment is to normalize thyroid functions as quickly as possible, to avoid iatrogenic hypothyroidism while providing management and supportive therapy for the infant's specific signs and symptoms. PMID:24251220

Septic shock non-thyroidal illness syndrome causes hypothyroidism and conditions for reduced sensitivity to thyroid hormone.

PubMed

Castro, Isabel; Quisenberry, Leah; Calvo, Rosa-Maria; Obregon, Maria-Jesus; Lado-Abeal, Joaquin

2013-04-01

Non-thyroidal illness syndrome (NTIS) is part of the neuroendocrine response to stress, but the significance of this syndrome remains uncertain. The aim of this study was to investigate the effect of lipopolysaccharide (LPS)-induced NTIS on thyroid hormone (TH) levels and TH molecular targets, as well as the relationship between septic shock nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) activation and TH receptor β (THRB) gene expression at a multi-tissue level in a pig model. Prepubertal domestic pigs were given i.v. saline or LPS for 48 h. Serum and tissue TH was measured by chemiluminescence and RIA. Expression of THRs and cofactors was measured by real-time PCR, and deiodinase (DIO) activity was measured by enzyme assays. Tissue NF-kB nuclear binding activity was evaluated by EMSA. LPS-treated pigs had decreased TH levels in serum and most tissues. DIO1 expression in liver and kidney and DIO1 activity in kidney decreased after LPS. No changes in DIO2 activity were observed between groups. LPS induced an increase in hypothalamus, thyroid, and liver DIO3 activity. Among the other studied genes, monocarboxylate transporter 8 and THRB were the most commonly repressed in endotoxemic pigs. LPS-induced NF-kB activation was associated with a decrease in THRB gene expression only in frontal lobe, adrenal gland, and kidney cortex. We conclude that LPS-induced NTIS in pigs is characterized by hypothyroidism and tissue-specific reduced TH sensitivity. The role of NF-kB in regulating THRB expression during endotoxemia, if any, is restricted to a limited number of tissues.

[Pregnancy (conception) in hyper- or hypothyroidism].

PubMed

Corssmit, E P; Wiersinga, W M; Boer, K; Prummel, M F

2001-04-14

Pregnancy is accompanied by changes in thyroid function. Due to the increased synthesis of thyroid binding globulin and the thyroid-stimulating effect of human chorionic gonadotrophin (hCG), serum concentrations of thyroid hormones will increase in the first trimester of pregnancy (total T4, T3). Free T4 levels decrease during the latter half of pregnancy. Hyperthyroidism during pregnancy is usually due to Graves' disease. Definitive therapy may be considered for cases prior to pregnancy, although a medical management as would be given during pregnancy is an equally good option. The medical management of hyperthyroidism consists of a monotherapy with thyreostatics in which the recommended dose needs to be adjusted on the basis of free T4 in the high-normal and thyroid stimulating hormone (TSH) in the low-normal area so as to minimise the risk of foetal hypothyroidism. The transplacental passage of maternal TSH receptor stimulating antibodies may cause foetal hyperthyroidism. Another cause of maternal hyperthyroidism during pregnancy is 'gestational transient thyrotoxicosis', which is associated with high hCG levels during the first trimester of pregnancy. It is nearly always accompanied by hyperemesis gravidarum. Hypothyroidism in pregnancy has negative consequences for the foetus. If the hypothyroidism is apparent prior to pregnancy, it should be corrected before conception (target TSH value of 1 mU/l). If discovered during pregnancy, treatment with levothyroxine should be started as soon as possible. In the case of a pre-existing hypothyroidism a 25-50% increase in the levothyroxine dosage is often needed during the first trimester of pregnancy. This is possibly due to an increased requirement. An adequate serum concentration of T4 is necessary for foetal brain development.

Association between genetic polymorphism and levothyroxine bioavailability in hypothyroid patients.

PubMed

Arici, Merve; Oztas, Ezgi; Yanar, Fatih; Aksakal, Nihat; Ozcinar, Beyza; Ozhan, Gul

2018-03-28

Thyroid hormones play a vital role in the human body for growth and differentiation, regulation of energy metabolism, and physiological function. Hypothyroidism is a common endocrine disorder, which generally results from diminished normal circulating concentrations of serum thyroxine (fT4) and triiodothyronine (fT3). The primary choice in hypothyroidism treatment is oral administration of levothyroxine (L-T4), a synthetic T4 hormone, as approximately 100-125 μg/day. Generally, dose adjustment is made by trial and error approach. However, there are several factors which might influence bioavailability of L-T4 treatment. Genetic background could be an important factor in hypothyroid patients as well as age, gender, concurrent medications and patient compliance. The concentration of thyroid hormones in tissue is regulated by both deiodinases enzyme and thyroid hormone transporters. In the present study, it was aimed to evaluate the effects of genetic differences in the proteins and enzymes (DIO1, DIO2, TSHR, THR and UGT) which are efficient in thyroid hormone metabolism and bioavailability of L-T4 in Turkish population. According to our findings, rs225014 and rs225015 variants in DIO2, which catalyses the conversion of thyroxine (pro-hormone) to the active thyroid hormone, were associated with TSH levels. It should be given lower dose to the patients with rs225014 TT and rs225015 GG genotypes in order to provide proper treatment with higher effectivity and lower toxicity.

Dronedarone administration prevents body weight gain and increases tolerance of the heart to ischemic stress: a possible involvement of thyroid hormone receptor alpha1.

PubMed

Pantos, Constantinos; Mourouzis, Iordanis; Malliopoulou, Vassiliki; Paizis, Ioannis; Tzeis, Stylianos; Moraitis, Panagiotis; Sfakianoudis, Konstantinos; Varonos, Dennis D; Cokkinos, Dennis V

2005-01-01

Hypothyroid heart displays a phenotype of cardioprotection against ischemia and this study investigated whether administration of dronedarone, an amiodarone-like compound that has been shown to preferentially antagonize thyroid hormone binding to thyroid hormone receptor alpha1 (TRalpha1), results in a similar effect. Dronedarone was given in Wistar rats (90 mg/kg, once daily (od) for 2 weeks) (DRON), while untreated animals served as controls (CONT). Hypothyroidism (HYPO) was induced by propylthiouracil administration. Isolated rat hearts were perfused in Langendorff mode and subjected to 20 minutes of zero-flow global ischemia (I) followed by 45 minutes of reperfusion (R). 3,5,3' Triiodothyronine remained unchanged while body weight and food intake were reduced. alpha-Myosin heavy chain (alpha-MHC) decreased in DRON while beta-myosin heavy chain (beta-MHC) and sarcoplasmic reticulum Ca2+ adenosine triphosphatase (ATPase) expression (SERCA) was similar to CONT. In HYPO, alpha-MHC and SERCA were decreased while beta-MHC was increased. Myocardial glycogen content was increased in both DRON and HYPO. In DRON, resting heart rate and contractility were reduced and ischemic contracture was significantly suppressed while postischemic left ventricular end-diastolic pressure and lactate dehydrogenase release (IU/L min) after I/R were significantly decreased. In conclusion, dronedarone treatment results in cardioprotection by selectively mimicking hypothyroidism. This is accompanied by a reduction in body weight because of the suppression of food intake. TRs might prove novel pharmacologic targets for the treatment of cardiovascular illnesses.

Mediator subunit MED1 is a T3-dependent and T3-independent coactivator on the thyrotropin β gene promoter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsui, Keiji; Oda, Kasumi; Mizuta, Shumpei

2013-10-11

Highlights: •MED1 is a bona fide T3-dependent coactivator on TSHB promoter. •Mice with LxxLL-mutant MED1 have attenuated TSHβ mRNA and thyroid hormone levels. •MED1 activates TSHB promoter T3-dependently in cultured cells. •T3-dependent MED1 action is enhanced when SRC1/SRC2 or HDAC2 is downregulated. •MED1 is also a T3-independent GATA2/Pit1 coactivator on TSHB promoter. -- Abstract: The MED1 subunit of the Mediator transcriptional coregulator complex is a nuclear receptor-specific coactivator. A negative feedback mechanism of thyroid-stimulating hormone (TSH, or thyrotropin) expression in the thyrotroph in the presence of triiodothyronine (T3) is employed by liganded thyroid hormone receptor β (TRβ) on the TSHβmore » gene promoter, where conventional histone-modifying coactivators act as corepressors. We now provide evidence that MED1 is a ligand-dependent positive cofactor on this promoter. TSHβ gene transcription was attenuated in MED1 mutant mice in which the nuclear receptor-binding ability of MED1 was specifically disrupted. MED1 stimulated GATA2- and Pit1-mediated TSHβ gene promoter activity in a ligand-independent manner in cultured cells. MED1 also stimulated transcription from the TSHβ gene promoter in a T3-dependent manner. The transcription was further enhanced when the T3-dependent corepressors SRC1, SRC2, and HDAC2 were downregulated. Hence, MED1 is a T3-dependent and -independent coactivator on the TSHβ gene promoter.« less

Thyroid disturbance related to chronic hepatitis C infection: role of CXCL10.

PubMed

Danilovic, Debora Lucia Seguro; Mendes-Correa, Maria Cassia; Chammas, Maria Cristina; Zambrini, Heverton; Barros, Raffaelle K; Marui, Suemi

2013-01-01

Association between autoimmune thyroid diseases (AITD) and hepatitis C is controversial, but may occur or worsen during alpha-interferon treatment. The mechanism responsible for autoimmune diseases in infected patients has not been fully elucidated. This study aims to evaluate the frequency of AITD in chronic hepatitis C and the association of chemokine (CXC motif) ligand 10 (CXCL10) and AITD. One hundred and three patients with chronic hepatitis C and 96 controls were prospectively selected to clinical, hormonal, thyroid autoimmunity and ultrasound exams, besides thyroxine-binding globulin (TBG) and CXCL10 measurements and hepatic biopsies. The frequency of AITD among infected subjects was similar to controls. TT3 and TT4 distributions were right shifted, as was TBG, which correlated to both of them. Thyroid heterogeneity and hypoechogenicity were associated with AITD. Increased vascularization was more prevalent in chronic hepatitis C.CXCL10 was higher in infected patients (p=0.007) but was not related to thyroid dysfunction. Increase in CXCL10 levels were consistent with hepatic necroinflammatory activity (p=0.011). In summary, no association was found between chronic hepatitis C and AITD. Infected subjects had higher TT3 and TT4 which were correlated to TBG. Increased CXCL10 was not associated to thyroid dysfunction in HCV-infected population.

Pyrrolidon carboxypeptidase activities in the hypothalamus-pituitary-thyroid and hypothalamus-pituitary-ovary axes of rats with mammary gland cancer induced by N-methyl nitrosourea.

PubMed

Carrera, M P; Ramírez-Expósito, M J; Valenzuela, M T; García, M J; Mayas, M D; Arias de Saavedra, J M; Sánchez, R; Pérez, M C; Martínez-Martos, J M

2005-02-01

Pyrrolidon carboxypeptidase is an omega-peptidase that hydrolyses N-terminal pyroglutamyl residues from biologically active peptides such as gonadotropin-releasing and thyrotrophin-releasing hormones. We previously described a decrease in both rat and human pyrrolidon carboxypeptidase activity with breast cancer, suggesting that gonadotropin-releasing hormone may be an important local intracrine, autocrine and/or paracrine hormonal factor in the pathogenesis of breast cancer while playing a role in the tumoral process. However, the other susceptible substrate of pyrrolidon carboxypeptidase, thyrotrophin-releasing hormone, may also be modified with breast cancer, supporting an association between breast cancer and thyroid disorders. The present work analyses soluble and membrane-bound pyrrolidon carboxypeptidase activities in the hypothalamus-pituitary-thyroid and hypothalamus-pituitary-ovary axes in N-methyl nitrosourea-induced breast cancer in rats. Our aim was to determine the possible relationship between gonadotropin-releasing hormone and thyrotrophin-releasing hormone regulation through pyrrolidon carboxypeptidase activity. We propose that pyrrolidon carboxypeptidase activity dysregulation at various local and systemic levels may participate in the initiation, promotion and progression of breast cancer induced in rat by N-methyl nitrosourea through the increase in gonadotropin-releasing hormone. Since pyrrolidon carboxypeptidase activity also acts on thyrotrophin-releasing hormone, the dysregulation of this enzyme's activity could indirectly affect hypothalamus-pituitary-thyroid axis function, and thus potentially represent a link between the diseases of thyroid and breast cancer.

[Thyroid function in patients with anorexia nervosa and depression].

PubMed

Natori, Y; Yamaguchi, N; Koike, S; Aoyama, A; Tsuchibuchi, S; Kojyo, K; Demura, R

1994-12-01

Thyroid hormone levels were measured in 21 patients with anorexia nervosa, 15 patients with depression and 16 patients with severe depression and were compared with those in 53 normal subjects. In anorexia nervosa and severe depressed patients, serum T3, T4, fT3, fT4 and T3/T4 ratio showed significantly lower values than those in normal subjects. However there was no difference between depressed patients and normal subjects. The serum TSH levels were within normal range in all of the studied subjects. Thus, thyroid hormone levels in severe depressed patients were similar to those in anorexia nervosa and the changes were inversely related to disease conditions. The supplementation of thyroid hormones to antidepressant relieved clinical symptoms in some of the severe depressed patients. These results suggested that the changes in thyroid hormone levels in anorexia nervosa and severe depression were mainly due to impaired conversion of T4 to T3 by increased cortisol secretion through emotional stress.

Endocrine System (For Parents)

MedlinePlus

... the thyroid gland through surgery or radiation treatments. Hypothyroidism. Hypothyroidism is when the levels of thyroid hormones in ... hormone production, is the most common cause of hypothyroidism in kids. Infants can also be born with ...

Thyroid disorders associated with pregnancy: etiology, diagnosis, and management.

PubMed

Lazarus, John H

2005-01-01

Pregnancy has an effect on thyroid economy with significant changes in iodine metabolism, serum thyroid binding proteins, and the development of maternal goiter especially in iodine-deficient areas. Pregnancy is also accompanied by immunologic changes, mainly characterized by a shift from a T helper-1 (Th1) lymphocyte to a Th2 lymphocyte state. Thyroid peroxidase antibodies are present in 10% of women at 14 weeks' gestation, and are associated with (i) an increased pregnancy failure (i.e. abortion), (ii) an increased incidence of gestational thyroid dysfunction, and (iii) a predisposition to postpartum thyroiditis. Thyroid function should be measured in women with severe hyperemesis gravidarum but not in every patient with nausea and vomiting during pregnancy. Graves hyperthyroidism during pregnancy is best managed with propylthiouracil administered throughout gestation. Thyroid-stimulating hormone-receptor antibody measurements at 36 weeks' gestation are predictive of transient neonatal hyperthyroidism, and should be checked even in previously treated patients receiving thyroxine. Postpartum exacerbation of hyperthyroidism is common, and should be evaluated in women with Graves disease not on treatment. Radioiodine therapy in pregnancy is absolutely contraindicated. Hypothyroidism (including subclinical hypothyroidism) occurs in about 2.5% of pregnancies, and may lead to obstetric and neonatal complications as well as being a cause of infertility. During the last few decades, evidence has been presented to underpin the critical importance of adequate fetal thyroid hormone levels in order to ensure normal central and peripheral nervous system maturation. In iodine-deficient and iodine-sufficient areas, low maternal circulating thyroxine levels have been associated with a significant decrement in child IQ and development. These data suggest the advisability of further evaluation for a screening program early in pregnancy to identify women with hypothyroxinemia, and the initiation of prompt treatment for its correction. Hypothyroidism in pregnancy is treated with a larger dose of thyroxine than in the nonpregnant state. Postpartum thyroid dysfunction (PPTD) occurs in 50% of women found to have thyroid peroxidase antibodies in early pregnancy. The hypothyroid phase of PPTD is symptomatic and requires thyroxine therapy. A high incidence (25-30%) of permanent hypothyroidism has been noted in these women. Women having transient PPTD with hypothyroidism should be monitored frequently, as there is a 50% chance of these patients developing hypothyroidism during the next 7 years.

Association of maternal thyroid function during early pregnancy with offspring IQ and brain morphology in childhood: a population-based prospective cohort study.

PubMed

Korevaar, Tim I M; Muetzel, Ryan; Medici, Marco; Chaker, Layal; Jaddoe, Vincent W V; de Rijke, Yolanda B; Steegers, Eric A P; Visser, Theo J; White, Tonya; Tiemeier, Henning; Peeters, Robin P

2016-01-01

Thyroid hormone is involved in the regulation of early brain development. Since the fetal thyroid gland is not fully functional until week 18-20 of pregnancy, neuronal migration and other crucial early stages of intrauterine brain development largely depend on the supply of maternal thyroid hormone. Current clinical practice mostly focuses on preventing the negative consequences of low thyroid hormone concentrations, but data from animal studies have shown that both low and high concentrations of thyroid hormone have negative effects on offspring brain development. We aimed to investigate the association of maternal thyroid function with child intelligence quotient (IQ) and brain morphology. In this population-based prospective cohort study, embedded within the Generation R Study (Rotterdam, Netherlands), we investigated the association of maternal thyroid function with child IQ (assessed by non-verbal intelligence tests) and brain morphology (assessed on brain MRI scans). Eligible women were those living in the study area at their delivery date, which had to be between April 1, 2002, and Jan 1, 2006. For this study, women with available serum samples who presented in early pregnancy (<18 weeks) were included. Data for maternal thyroid-stimulating hormone, free thyroxine, thyroid peroxidase antibodies (at weeks 9-18 of pregnancy), and child IQ (assessed at a median of 6·0 years of age [95% range 5·6-7·9 years]) or brain MRI scans (done at a median of 8·0 years of age [6·2-10·0]) were obtained. Analyses were adjusted for potential confounders including concentrations of human chorionic gonadotropin and child thyroid-stimulating hormone and free thyroxine. Data for child IQ were available for 3839 mother-child pairs, and MRI scans were available from 646 children. Maternal free thyroxine concentrations showed an inverted U-shaped association with child IQ (p=0·0044), child grey matter volume (p=0·0062), and cortex volume (p=0·0011). For both low and high maternal free thyroxine concentrations, this association corresponded to a 1·4-3·8 points reduction in mean child IQ. Maternal thyroid-stimulating hormone was not associated with child IQ or brain morphology. All associations remained similar after the exclusion of women with overt hypothyroidism and overt hyperthyroidism, and after adjustment for concentrations of human chorionic gonadotropin, child thyroid-stimulating hormone and free thyroxine or thyroid peroxidase antibodies (continuous or positivity). Both low and high maternal free thyroxine concentrations during pregnancy were associated with lower child IQ and lower grey matter and cortex volume. The association between high maternal free thyroxine and low child IQ suggests that levothyroxine therapy during pregnancy, which is often initiated in women with subclinical hypothyroidism during pregnancy, might carry the potential risk of adverse child neurodevelopment outcomes when the aim of treatment is to achieve high-normal thyroid function test results. The Netherlands Organisation for Health Research and Development (ZonMw) and the European Community's Seventh Framework Programme. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of peptides Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly on hormonal activity and structure of the thyroid gland in hypophysectomized young chickens and old hens.

PubMed

Kuznik, B I; Pateyuk, A V; Rusaeva, N S; Baranchugova, L M; Obydenko, V I

2011-02-01

Hypophysectomy in 5-days chickens and old hens was followed by hormonal disturbances and structural changes in the thyroid gland. Administration of peptides Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly synthesized on the basis the amino acid composition of extracts from the anterior and posterior lobes of the pituitary gland, respectively, to hypophysectomized birds for 40 days significantly reduced the degree of these changes. The normalizing effect of synthetic peptides on the concentration of thyrotrophic hormone and thyroid hormones in old hens was less pronounced than in chickens.

H-2RIIBP, a member of the nuclear hormone receptor superfamily that binds to both the regulatory element of major histocompatibility class I genes and the estrogen response element.

PubMed

Hamada, K; Gleason, S L; Levi, B Z; Hirschfeld, S; Appella, E; Ozato, K

1989-11-01

Transcription of major histocompatibility complex (MHC) class I genes is regulated by the conserved MHC class I regulatory element (CRE). The CRE has two factor-binding sites, region I and region II, both of which elicit enhancer function. By screening a mouse lambda gt 11 library with the CRE as a probe, we isolated a cDNA clone that encodes a protein capable of binding to region II of the CRE. This protein, H-2RIIBP (H-2 region II binding protein), bound to the native region II sequence, but not to other MHC cis-acting sequences or to mutant region II sequences, similar to the naturally occurring region II factor in mouse cells. The deduced amino acid sequence of H-2RIIBP revealed two putative zinc fingers homologous to the DNA-binding domain of steroid/thyroid hormone receptors. Although sequence similarity in other regions was minimal, H-2RIIBP has apparent modular domains characteristic of the nuclear hormone receptors. Further analyses showed that both H-2RIIBP and the natural region II factor bind to the estrogen response element (ERE) of the vitellogenin A2 gene. The ERE is composed of a palindrome, and half of this palindrome resembles the region II binding site of the MHC CRE. These results indicate that H-2RIIBP (i) is a member of the superfamily of nuclear hormone receptors and (ii) may regulate not only MHC class I genes but also genes containing the ERE and related sequences. Sequences homologous to the H-2RIIBP gene are widely conserved in the animal kingdom. H-2RIIBP mRNA is expressed in many mouse tissues, in agreement with the distribution of the natural region II factor.

Chronic food restriction and the circadian rhythms of pituitary-adrenal hormones, growth hormone and thyroid-stimulating hormone.

PubMed

Armario, A; Montero, J L; Jolin, T

1987-01-01

Adult male Sprague-Dawley rats were subjected to food restriction so that they ate 65% of food ingested by control rats. While control rats had free access to food over the 24-hour period, food-restricted rats were provided with food daily at 10 a.m. The experimental period lasted for 34 days. On day 35, rats from both experimental groups were killed at 08.00, 11.00, 14.00, 24.00 and 02.00 h. Food restriction modified the circadian rhythms of ACTH and corticosterone. In addition, total circulating corticosterone throughout the day was higher in food-restricted than in control rats. In contrast, food restriction resulted in depressed secretion of thyroid-stimulating hormone and growth hormone. The results indicate that time of food availability entrained circadian corticosterone rhythm but not thyroid-stimulating hormone and growth hormone rhythms.

Thyrotropin-induced hyperthyroidism caused by selective pituitary resistance to thyroid hormone. A new syndrome of "inappropriate secretion of TSH".

PubMed Central

Gershengorn, M C; Weintraub, B D

1975-01-01

An 18-yr-old woman with clinical and laboratory features of hyperthyroidism had persistently elevated serum levels of immunoreative thyrotropin (TSH). During 11 yr of follow-up there had been no evidence of a pituitary tumor. After thyrotropin-releasing hormone (TRH), there was a marked increase in TSH and secondarily in triiodothyronine (T3), the latter observation confirming the biologic activity of the TSH. Exogenous T3 raised serum T3 and several measurements of peripheral thyroid hormone effect, while decreasing serum TSH, thyroxine (T4), and thyroidal radioiodine uptake. After T3, the TRH-stimulated TSH response was decreased but was still inappropriate for the elevated serum T3 levels. Dexamethasone reduced serum TSH but did not inhibit TRH stimulation of TSH. Propylthiouracil reduced serum T4 and T3 and raised TSH. This patient represents a new syndrome of TSH-induced hyperthyroidism, differing from previous reports in the absence of an obvious pituitary tumor and in the responsiveness of the TSH to TRH stimulation and thyroid hormone suppression. This syndrome appears to be caused by a selective, partial resistance of the pituitary to the action of thyroid hormone. This case is also compared with previous reports in the literature of patients with elevated serum levels of immunoreactive TSH in the presence of elevated total and free thyroid hormones. A classification of these cases, termed "inappropriate secretion of TSH," is proposed. PMID:1159077

Utilizing mass spectrometry imaging to map the thyroid hormones triiodothyronine and thyroxine in Xenopus tropicalis tadpoles.

PubMed

Goto-Inoue, Naoko; Sato, Tomohiko; Morisasa, Mizuki; Kashiwagi, Akihiko; Kashiwagi, Keiko; Sugiura, Yuki; Sugiyama, Eiji; Suematsu, Makoto; Mori, Tsukasa

2018-02-01

Thyroid hormones are not only responsible for thermogenesis and energy metabolism in animals, but also have an important role in cell differentiation and development. Amphibian metamorphosis provides an excellent model for studying the remodeling of the body. This metamorphic organ remodeling is induced by thyroid hormones, and a larval body is thus converted into an adult one. The matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry (MS) imaging technology is expected to be a suitable tool for investigating small bioreactive molecules. The present study describes the distribution of the thyroid hormones, i.e., triiodothyronine (T3) and thyroxine (T4) and their inactive form reverse T3 (rT3) in Xenopus tropicalis tadpoles using two different types of imaging techniques, MS/MS and Fourier transform (FT)-MS imaging. As a result of MS/MS imaging, we demonstrated that T3 was mainly distributed in the gills. T4 was faintly localized in the eyes, inner gills, and intestine during metamorphosis. The intensity of T3 in the gills and the intensity of T4 in the body fluids were increased during metamorphosis. Moreover, the localization of the inactive form rT3 was demonstrated to be separate from T3, namely in the intestine and muscles. In addition, FT-MS imaging could utilize simultaneous imaging including thyroid hormone. This is the first report to demonstrate the molecular distribution of thyroid hormones themselves and to discriminate T3, T4, and rT3 in animal tissues.

Liver X receptor β controls thyroid hormone feedback in the brain and regulates browning of subcutaneous white adipose tissue.

PubMed

Miao, Yifei; Wu, Wanfu; Dai, Yubing; Maneix, Laure; Huang, Bo; Warner, Margaret; Gustafsson, Jan-Åke

2015-11-10

The recent discovery of browning of white adipose tissue (WAT) has raised great research interest because of its significant potential in counteracting obesity and type 2 diabetes. Browning is the result of the induction in WAT of a newly discovered type of adipocyte, the beige cell. When mice are exposed to cold or several kinds of hormones or treatments with chemicals, specific depots of WAT undergo a browning process, characterized by highly activated mitochondria and increased heat production and energy expenditure. However, the mechanisms underlying browning are still poorly understood. Liver X receptors (LXRs) are one class of nuclear receptors, which play a vital role in regulating cholesterol, triglyceride, and glucose metabolism. Following our previous finding that LXRs serve as repressors of uncoupling protein-1 (UCP1) in classic brown adipose tissue in female mice, we found that LXRs, especially LXRβ, also repress the browning process of subcutaneous adipose tissue (SAT) in male rodents fed a normal diet. Depletion of LXRs activated thyroid-stimulating hormone (TSH)-releasing hormone (TRH)-positive neurons in the paraventricular nucleus area of the hypothalamus and thus stimulated secretion of TSH from the pituitary. Consequently, production of thyroid hormones in the thyroid gland and circulating thyroid hormone level were increased. Moreover, the activity of thyroid signaling in SAT was markedly increased. Together, our findings have uncovered the basis of increased energy expenditure in male LXR knockout mice and provided support for targeting LXRs in treatment of obesity.

Thyroid

MedlinePlus

Thyroid is used to treat the symptoms of hypothyroidism (a condition where the thyroid gland does not produce enough thyroid hormone). Symptoms of hypothyroidism include lack of energy, depression, constipation, weight gain, ...

Novel Insights on Thyroid-Stimulating Hormone Receptor Signal Transduction

PubMed Central

Neumann, Susanne; Grüters, Annette; Krude, Heiko

2013-01-01

The TSH receptor (TSHR) is a member of the glycoprotein hormone receptors, a subfamily of family A G protein-coupled receptors. The TSHR is of great importance for the growth and function of the thyroid gland. The TSHR and its endogenous ligand TSH are pivotal proteins with respect to a variety of physiological functions and malfunctions. The molecular events of TSHR regulation can be summarized as a process of signal transduction, including signal reception, conversion, and amplification. The steps during signal transduction from the extra- to the intracellular sites of the cell are not yet comprehensively understood. However, essential new insights have been achieved in recent years on the interrelated mechanisms at the extracellular region, the transmembrane domain, and intracellular components. This review contains a critical summary of available knowledge of the molecular mechanisms of signal transduction at the TSHR, for example, the key amino acids involved in hormone binding or in the structural conformational changes that lead to G protein activation or signaling regulation. Aspects of TSHR oligomerization, signaling promiscuity, signaling selectivity, phenotypes of genetic variations, and potential extrathyroidal receptor activity are also considered, because these are relevant to an understanding of the overall function of the TSHR, including physiological, pathophysiological, and pharmacological perspectives. Directions for future research are discussed. PMID:23645907

SIRT1 Regulates Thyroid-Stimulating Hormone Release by Enhancing PIP5Kγ Activity through Deacetylation of Specific Lysine Residues in Mammals

PubMed Central

Akieda-Asai, Sayaka; Zaima, Nobuhiro; Ikegami, Koji; Kahyo, Tomoaki; Yao, Ikuko; Hatanaka, Takahiro; Iemura, Shun-ichiro; Sugiyama, Rika; Yokozeki, Takeaki; Eishi, Yoshinobu; Koike, Morio; Ikeda, Kyoji; Chiba, Takuya; Yamaza, Haruyoshi; Shimokawa, Isao; Song, Si-Young; Matsuno, Akira; Mizutani, Akiko; Sawabe, Motoji; Chao, Moses V.; Tanaka, Masashi; Kanaho, Yasunori; Natsume, Tohru; Sugimura, Haruhiko; Date, Yukari; McBurney, Michael W.; Guarente, Leonard; Setou, Mitsutoshi

2010-01-01

Background SIRT1, a NAD-dependent deacetylase, has diverse roles in a variety of organs such as regulation of endocrine function and metabolism. However, it remains to be addressed how it regulates hormone release there. Methodology/Principal Findings Here, we report that SIRT1 is abundantly expressed in pituitary thyrotropes and regulates thyroid hormone secretion. Manipulation of SIRT1 level revealed that SIRT1 positively regulated the exocytosis of TSH-containing granules. Using LC/MS-based interactomics, phosphatidylinositol-4-phosphate 5-kinase (PIP5K)γ was identified as a SIRT1 binding partner and deacetylation substrate. SIRT1 deacetylated two specific lysine residues (K265/K268) in PIP5Kγ and enhanced PIP5Kγ enzyme activity. SIRT1-mediated TSH secretion was abolished by PIP5Kγ knockdown. SIRT1 knockdown decreased the levels of deacetylated PIP5Kγ, PI(4,5)P2, and reduced the secretion of TSH from pituitary cells. These results were also observed in SIRT1-knockout mice. Conclusions/Significance Our findings indicated that the control of TSH release by the SIRT1-PIP5Kγ pathway is important for regulating the metabolism of the whole body. PMID:20668706

Trends in thyroid hormone prescribing and consumption in the UK

PubMed Central

Mitchell, Anna L; Hickey, Bryan; Hickey, Janis L; Pearce, Simon HS

2009-01-01

Background Thyroid hormone replacement is one of the most commonly prescribed and cost effective treatments for a chronic disease. There have been recent changes in community prescribing policies in many areas of the UK that have changed patient access to necessary medications. This study aimed to provide a picture of thyroid hormone usage in the UK and to survey patient opinion about current community prescribing policies for levothyroxine. Methods Data on community prescriptions for thyroid hormones in England between 1998 and 2007, provided by the Department of Health, were collated and analysed. A survey of UK members of a patient support organisation (the British Thyroid Foundation) who were taking levothyroxine was carried out. Results The amount of prescribed thyroid hormones used in England has more than doubled, from 7 to almost 19 million prescriptions, over the last 10 years. The duration of prescriptions has reduced from 60 to 45 days, on average over the same time. Two thousand five hundred and fifty one responses to the patient survey were received. Thirty eight percent of levothyroxine users reported receiving prescriptions of 28 days' duration. 59% of respondents reported being dissatisfied with 28-day prescribing. Conclusion Amongst users of levothyroxine, there is widespread patient dissatisfaction with 28-day prescription duration. Analysis of the full costs of 28-day dispensing balanced against the potential savings of reduced wastage of thyroid medications, suggests that this is unlikely to be an economically effective public health policy. PMID:19432950

Silent pituitary macroadenoma co-secreting growth hormone and thyroid stimulating hormone.

PubMed

Sen, Orhan; Ertorer, M Eda; Aydin, M Volkan; Erdogan, Bulent; Altinors, Nur; Zorludemir, Suzan; Guvener, Nilgun

2005-04-01

Silent pituitary adenomas are a group of tumors showing heterogenous morphological features with no hormonal function observed clinically. To date no explanation has been provided as to why these tumors remain "silent". We report a case of a silent macroadenoma with both growth hormone (GH) and thyroid stimulating hormone (TSH) staining and secretion but with no clinical manifestations, in particular, the absence of features of acromegaly or hyperthyroidism. The relevant literature is reviewed.

Conversion of autoimmune hypothyroidism to hyperthyroidism.

PubMed

Furqan, Saira; Haque, Naeem-ul; Islam, Najmul

2014-08-03

Graves' disease and Hashimoto's thyroiditis are the two autoimmune spectrum of thyroid disease. Cases of conversion from hyperthyroidism to hypothyroidism have been reported but conversion from hypothyroidism to hyperthyroidism is very rare. Although such cases have been reported rarely in the past we are now seeing such conversions from hypothyroidism to hyperthyroidism more frequently in clinical practice. We are reporting three cases of middle aged Asian females who presented with classical symptoms of hypothyroidism and the investigations showed elevated thyroid stimulating hormone with positive thyroid antibodies. Diagnosis of autoimmune hypothyroidism was made and thyroxine replacement therapy was initiated. Patients became asymptomatic with normalization of thyroid stimulating hormone level. After few years they developed symptoms of hyperthyroidism with suppressed thyroid stimulating hormone level. Over replacement of thyroxine was considered and the dose of thyroxine was decreased, but they remain symptomatic. After gradual decrease in the dose of thyroxine it was stopped finally. Even after few months of stopping thyroxine, the symptoms of hyperthyroidism did not improve and the biochemical and imaging modalities confirmed that the patients have developed hyperthyroidism. Anti-thyroid treatment was then started and the patients became symptom free. High index of suspicion should be there for possible conversion of hypothyroidism to hyperthyroidism if a patient with primary hypothyroidism develops persistent symptoms of hyperthyroidism. Otherwise it can be missed easily considering it as an over replacement with thyroid hormone.

Conversion of autoimmune hypothyroidism to hyperthyroidism

PubMed Central

2014-01-01

Background Graves’ disease and Hashimoto’s thyroiditis are the two autoimmune spectrum of thyroid disease. Cases of conversion from hyperthyroidism to hypothyroidism have been reported but conversion from hypothyroidism to hyperthyroidism is very rare. Although such cases have been reported rarely in the past we are now seeing such conversions from hypothyroidism to hyperthyroidism more frequently in clinical practice. Case presentation We are reporting three cases of middle aged Asian females who presented with classical symptoms of hypothyroidism and the investigations showed elevated thyroid stimulating hormone with positive thyroid antibodies. Diagnosis of autoimmune hypothyroidism was made and thyroxine replacement therapy was initiated. Patients became asymptomatic with normalization of thyroid stimulating hormone level. After few years they developed symptoms of hyperthyroidism with suppressed thyroid stimulating hormone level. Over replacement of thyroxine was considered and the dose of thyroxine was decreased, but they remain symptomatic. After gradual decrease in the dose of thyroxine it was stopped finally. Even after few months of stopping thyroxine, the symptoms of hyperthyroidism did not improve and the biochemical and imaging modalities confirmed that the patients have developed hyperthyroidism. Anti-thyroid treatment was then started and the patients became symptom free. Conclusion High index of suspicion should be there for possible conversion of hypothyroidism to hyperthyroidism if a patient with primary hypothyroidism develops persistent symptoms of hyperthyroidism. Otherwise it can be missed easily considering it as an over replacement with thyroid hormone. PMID:25086829

Screening the ToxCast Phase I, II, and e1K Chemical Libraries for Inhibition of Deiodinase Type 1,2 and 3 Enzyme Activity

EPA Science Inventory

Thyroid hormone (TH) signaling and homeostasis is dependent upon coordination of multiple key events including thyroidal iodide uptake and hormone synthesis, and peripheral metabolism and elimination. Deiodinase enzymes play an essential role in converting the pro-hormone thyroxi...

Effects of enteral different-dose levothyroxine-sodium pretreatment on serum thyroid hormone levels and myocardial ischemia-reperfusion injury.

PubMed

Yang, Gui-Zhen; Xue, Fu-Shan; Liu, Ya-Yang; Li, Hui-Xian; Liu, Qing; Liao, Xu

2018-04-01

The available evidence shows that perioperative oral thyroid hormone can significantly attenuate the postoperative decline in the serum hormone level and improve postoperative hemodynamic and prognostic parameters. However, there has been no study assessing the effects of preoperative oral different-dose thyroid hormone on serum hormone levels and myocardial ischemia-reperfusion injury (IRI) after cardiac surgery. Forty-eight healthy Wistar rats, aged 35 days, were randomly allocated into six groups: Group BC, Group C and four pretreatment groups in which the rats were given levothyroxine-sodium of 10 μg, 20 μg, 40 μg and 80 μg/100 g. On the eighth day, the serum thyroid hormone levels were determined and then an isolated heart ischemia-reperfusion model was established with a Langendorff apparatus. Compared with Groups BC and C, serum thyroid hormone levels on the eighth day did not significantly change in Group 10 μg, but were significantly increased in Groups 20 μg, 40 μg and 80 μg. The cardiac enzyme myocardial-bound creatine kinase levels in the coronary effluent during reperfusion were significantly lower in Groups 10 μg and 20 μg and 40 μg than in Group C. The recovery rates of + dp/dt max and - dp/dt max at 30 min during reperfusion were significantly lower in Groups 40 μg and 80 μg than in Groups 10 μg and 20 μg. Compared with Group C, myocardial expressions of heat shock protein 70 and myosin heavy chain α were increased in the four experiment groups and myocardial expression of thyroid hormone receptor α1 was significantly increased in Groups 20 μg, 40 μg and 80 μg. The pretreatment with enterally smaller doses levothyroxine-sodium does not significantly affect serum thyroid hormone levels and produces protection against myocardial IRI, whereas pretreatment with enterally larger doses of levothyroxine-sodium can only provide an attenuated or insignificant cardioprotection because of hyperthyroxinemia. Cardioprotection by levothyroxine-sodium pretreatment is probably attributable to increased myocardial expression of heat shock protein 70 and myosin heavy chain α.

Thyroid hormones and changes in body weight and metabolic parameters in response to weight loss diets: the POUNDS LOST trial.

PubMed

Liu, G; Liang, L; Bray, G A; Qi, L; Hu, F B; Rood, J; Sacks, F M; Sun, Q

2017-06-01

The role of thyroid hormones in diet-induced weight loss and subsequent weight regain is largely unknown. To examine the associations between thyroid hormones and changes in body weight and resting metabolic rate (RMR) in a diet-induced weight loss setting. Data analysis was conducted among 569 overweight and obese participants aged 30-70 years with normal thyroid function participating in the 2-year Prevention of Obesity Using Novel Dietary Strategies (POUNDS) LOST randomized clinical trial. Changes in body weight and RMR were assessed during the 2-year intervention. Thyroid hormones (free triiodothyronine (T3), free thyroxine (T4), total T3, total T4 and thyroid-stimulating hormone (TSH)), anthropometric measurements and biochemical parameters were assessed at baseline, 6 months and 24 months. Participants lost an average of 6.6 kg of body weight during the first 6 months and subsequently regained an average of 2.7 kg of body weight over the remaining period from 6 to 24 months. Baseline free T3 and total T3 were positively associated, whereas free T4 was inversely associated, with baseline body weight, body mass index and RMR. Total T4 and TSH were not associated with these parameters. Higher baseline free T3 and free T4 levels were significantly associated with a greater weight loss during the first 6 months (P<0.05) after multivariate adjustments including dietary intervention groups and baseline body weight. Comparing extreme tertiles, the multivariate-adjusted weight loss±s.e. was -3.87±0.9 vs -5.39±0.9 kg for free T3 (P trend =0.02) and -4.09±0.9 vs -5.88±0.9 kg for free T4 (P trend =0.004). The thyroid hormones did not predict weight regain in 6-24 months. A similar pattern of associations was also observed between baseline thyroid hormones and changes in RMR. In addition, changes in free T3 and total T3 levels were positively associated with changes in body weight, RMR, body fat mass, blood pressure, glucose, insulin, triglycerides and leptin at 6 months and 24 months (all P<0.05). In this diet-induced weight loss setting, higher baseline free T3 and free T4 predicted more weight loss, but not weight regain among overweight and obese adults with normal thyroid function. These findings reveal a novel role of thyroid hormones in body weight regulation and may help identify individuals more responsive to weight loss diets.

The assessment of thyroid autoantibody levels in euthyroid polycystic ovary syndrome patients.

PubMed

Hepşen, Sema; Karaköse, Melia; Çakal, Erman; Öztekin, Sanem; Ünsal, İlknur; Akhanlı, Pınar; Uçan, Bekir; Özbek, Mustafa

2018-04-27

Thyroid hormone abnormalities are commonly seen in polycystic ovary syndrome (PCOS) and have considerable effects on comorbidities. The association with PCOS and thyroid autoimmunity which lead to thyroid pathologies are not revealed clearly. We targeted to commentate anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin (anti-TG) antibody levels and thyroid autoimmunity in PCOS. 184 patients who got the diagnosis of PCOS regard to the revised 2003 Rotterdam criteria were embodied in this study. 106 age-matched female volunteers were included in the control group. Characteristics, biochemical parameters, thyroid hormone and autoantibody levels of groups were investigated. Although; we did not find out a statistically significant difference in TSH and sT4 levels between two groups (p>0.05), anti-TPO and anti-TG antibody levels were determined higher in PCOS group significantly (p<0.001). Anti-TPO Ab and anti-TG Ab positivity prevalence of PCOS patients were significantly higher as against to controls (p<0.001; p=0.01). Not only thyroid hormone levels but also thyroid autoantibody levels should be screened during the investigation of PCOS and the patients with positive results need to be followed up carefully in the long run.

A-FABP mediates adaptive thermogenesis by promoting intracellular activation of thyroid hormones in brown adipocytes

PubMed Central

Shu, Lingling; Hoo, Ruby L. C.; Wu, Xiaoping; Pan, Yong; Lee, Ida P. C.; Cheong, Lai Yee; Bornstein, Stefan R; Rong, Xianglu; Guo, Jiao; Xu, Aimin

2017-01-01

The adipokine adipocyte fatty acid-binding protein (A-FABP) has been implicated in obesity-related cardio-metabolic complications. Here we show that A-FABP increases thermogenesis by promoting the conversion of T4 to T3 in brown adipocytes. We find that A-FABP levels are increased in both white (WAT) and brown (BAT) adipose tissues and the bloodstream in response to thermogenic stimuli. A-FABP knockout mice have reduced thermogenesis and whole-body energy expenditure after cold stress or after feeding a high-fat diet, which can be reversed by infusion of recombinant A-FABP. Mechanistically, A-FABP induces the expression of type-II iodothyronine deiodinase in BAT via inhibition of the nuclear receptor liver X receptor α, thereby leading to the conversion of thyroid hormone from its inactive form T4 to active T3. The thermogenic responses to T4 are abrogated in A-FABP KO mice, but enhanced by A-FABP. Thus, A-FABP acts as a physiological stimulator of BAT-mediated adaptive thermogenesis. PMID:28128199

Developmental toxicity and thyroid hormone-disrupting effects of 2,4-dichloro-6-nitrophenol in Chinese rare minnow (Gobiocypris rarus).

PubMed

Chen, Rui; Yuan, Lilai; Zha, Jinmiao; Wang, Zijian

2017-04-01

In the present study, to evaluate embryonic toxicity and the thyroid-disrupting effects of 2,4-dichloro-6-nitrophenol (DCNP), embryos and adults of Chinese rare minnow (Gobiocypris rarus) were exposed to 2, 20, and 200μg/L DCNP. In the embryo-larval assay, increased percentages of mortality and occurrence of malformations, decreased percentage of hatching, and decreased body length and body weight were observed after DCNP treatment. Moreover, the whole-body T3 levels were significantly increased at 20 and 200μg/L treatments, whereas the T4 levels were markedly decreased significantly (p<0.05) for all DCNP concentrations. In the adult fish assay, plasma T3 levels were significantly increased whereas plasma T4 levels were significantly reduced in the fish treated with 20 and 200μg/L (p<0.05). In addition, DCNP exposure significantly changed the transcription levels of thyroid system related genes, including dio1, dio2, me, nis, tr, and ttr. The increased responsiveness of thyroid hormone and mRNA expression levels of thyroid system related genes suggested that DCNP could disrupt the thyroid hormone synthesis and transport pathways. Therefore, our findings provide new insights of DCNP as a thyroid hormone-disrupting chemical. Copyright © 2017 Elsevier B.V. All rights reserved.

Thyroid functional disease: an under-recognized cardiovascular risk factor in kidney disease patients

PubMed Central

Rhee, Connie M.; Brent, Gregory A.; Kovesdy, Csaba P.; Soldin, Offie P.; Nguyen, Danh; Budoff, Matthew J.; Brunelli, Steven M.; Kalantar-Zadeh, Kamyar

2015-01-01

Thyroid functional disease, and in particular hypothyroidism, is highly prevalent among chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. In the general population, hypothyroidism is associated with impaired cardiac contractility, endothelial dysfunction, atherosclerosis and possibly higher cardiovascular mortality. It has been hypothesized that hypothyroidism is an under-recognized, modifiable risk factor for the enormous burden of cardiovascular disease and death in CKD and ESRD, but this has been difficult to test due to the challenge of accurate thyroid functional assessment in uremia. Low thyroid hormone levels (i.e. triiodothyronine) have been associated with adverse cardiovascular sequelae in CKD and ESRD patients, but these metrics are confounded by malnutrition, inflammation and comorbid states, and hence may signify nonthyroidal illness (i.e. thyroid functional test derangements associated with underlying ill health in the absence of thyroid pathology). Thyrotropin is considered a sensitive and specific thyroid function measure that may more accurately classify hypothyroidism, but few studies have examined the clinical significance of thyrotropin-defined hypothyroidism in CKD and ESRD. Of even greater uncertainty are the risks and benefits of thyroid hormone replacement, which bear a narrow therapeutic-to-toxic window and are frequently prescribed to CKD and ESRD patients. In this review, we discuss mechanisms by which hypothyroidism adversely affects cardiovascular health; examine the prognostic implications of hypothyroidism, thyroid hormone alterations and exogenous thyroid hormone replacement in CKD and ESRD; and identify areas of uncertainty related to the interplay between hypothyroidism, cardiovascular disease and kidney disease requiring further investigation. PMID:24574542

Periods of sensitivity to thyroid hormone during the development of the organ of Corti.

PubMed

Uziel, A

1986-01-01

Cochlear structures are sensitive to the morphogenetic effect of thyroid hormone during the whole duration of maturation. For each structure, there exists a period of maximal sensitivity to thyroid hormone which corresponds to the period of development during which the structure of interest undergoes its main morphological changes (6 to 13 days for the inner sulcus epithelium, 6 to 10 days for the pillars, the 2nd and a part of the 3rd postnatal week for OHCs and their efferent innervation in rats). These periods of sensitivity can be considered as critical periods because cochlear structures are maximally vulnerable to thyroid deficiency during these periods.

Role of the Pineal Body Hormone in Thyroid Function; L'HORMONE EPIPHSAIRE INTERVIENT DANS LA DYNAMIQUE DU METABOLISME DE L'IODE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milcou, S.M.; Costiner, E. et al.

To evaluate the action of the pineal body hormone on thyroid function, hyperactivity of the epiphysis was experimentally induced by administering pineal body hormone four hours before the experiment and then every four hours during the experiment. Iodine tagging was achieved by the intraperltoneal injection of carrierless'' I/sup 131/. The animals, which had been divided into batches of 10, were sacrificed every 2 hours until 48 hours had elapsed following the radioactive tagging. Measurements on the radioactivity of the thyroid and of the blood were carried out in vitro. The values obtained were used in order to draw up simultaneousmore » radioactivity curves applicable to the total radioactivity and to that attributable to inorganic and organic iodine, respectively. The curves showing the variation in the radioactivity reveal a delayed action of the pineal gland hormone which is different according to whether the functional thyroid units have a large or small time constant. (auth)« less

Contribution to the Study of Phosphate Uptake (P$sup 32$) at the Level of the Thyroid, The Suprarenals, and Testicles after Administration of Epiphysis Hormone; CONTRIBUTION A L'ETUDE DE LA PHOSPHOCAPTATION (P$sup 52$) AU NIVEAU DE LA THYROIDE DES SURRENALES ET DES TESTICULES APRES ADMINISTRATION DE L'EPIPHYSE-HORMONE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Negosscou, I.; Bojinescuu, Al.; Cocou, Fl.

1959-10-31

The phosphorus uptake by several endocrine glands after the administration of epiphysis hormone was studied by a tracer technique. After ten days of daily injections of the hormone into male albino rats, the rats received an injection of P/sup 32/. The hormone was again given 6, 12, and 18 hours after the P/sup 32/ injection. Some animals were killed 8 hours after the administration of phosphorus and the rest after 24 hours. The radioactivity of the epiphysis, hypophysis, thyroid, suprarenals, testicles, and seminal vesicles was determined. The results showed a functional inhibition of the phosphorus uptake in the thyroid, suprarenals,more » testicles, and seminal vesicles. A decrease in the phosphorus uptake by the hypophysis was also observed. (J.S.R.)« less

Influence of obesity and surgical weight loss on thyroid hormone levels.

PubMed

Chikunguwo, Silas; Brethauer, Stacy; Nirujogi, Vijaya; Pitt, Tracy; Udomsawaengsup, Suthep; Chand, Bipan; Schauer, Philip

2007-01-01

The pathophysiologic relationship between morbid obesity and thyroid hormones is not well understood. The goal of this study was to evaluate the influence of obesity and weight reduction after bariatric surgery on thyroid hormone levels. Patients who underwent gastric bypass or adjustable gastric banding at our institution, had no previous diagnosis of thyroid disorder, were not taking medication that could affect the thyroid function evaluation, and who were nonsmokers were included in this retrospective evaluation. The association between the thyroid-stimulating hormone (TSH) and free thyroxine (T(4)) levels and body mass index (BMI), and the influence of weight loss after bariatric surgery on these hormones were investigated at different points (preoperatively and 6 and 12 months after bariatric surgery). A total of 86 patients met the study criteria. The TSH levels correlated positively with BMI (P <.001, r = .91) within the BMI range of 30-67 kg/m(2). The mean BMI change from 49 to 32 kg/m(2) after bariatric surgery was associated with a mean reduction in the TSH level from 4.5 to 1.9 microU/mL. Free T(4) showed no association with BMI and was not significantly influenced by weight loss. Before bariatric surgery, 10.5% of the subjects had laboratory values consistent with subclinical hypothyroidism. After bariatric surgery, 100% of these patients experienced significant weight reduction with simultaneous resolution of their subclinical hypothyroidism. The results of our study have demonstrated a statistically significant positive association between serum TSH within the normal range and BMI. No association was found between BMI and free T(4) serum levels. The prevalence of subclinical hypothyroidism in study group was 10.5%. Weight loss after bariatric surgery improved or normalized thyroid hormone levels.

High T3, Low T4 Serum Levels in Mct8 Deficiency Are Not Caused by Increased Hepatic Conversion through Type I Deiodinase

PubMed Central

Wirth, Eva K.; Rijntjes, Eddy; Meyer, Franziska; Köhrle, Josef; Schweizer, Ulrich

2015-01-01

Background The Allan-Herndon-Dudley syndrome is a severe psychomotor retardation accompanied by specific changes in circulating thyroid hormone levels (high T3, low T4). These are caused by mutations in the thyroid hormone transmembrane transport protein monocarboxylate transporter 8 (MCT8). Objective: To test the hypothesis that circulating low T4 and high T3 levels are caused by enhanced conversion of T4 via increased activity of hepatic type I deiodinase (Dio1). Methods We crossed mice deficient in Mct8 with mice lacking Dio1 activity in hepatocytes. Translation of the selenoenzyme Dio1 was abrogated by hepatocyte-specific inactivation of selenoprotein biosynthesis. Results Inactivation of Dio1 activity in the livers of global Mct8-deficient mice does not restore normal circulating thyroid hormone levels. Conclusions Our data suggest that although hepatic Dio1 activity is increased in Mct8-deficient mice, it does not cause the observed abnormal circulating thyroid hormone levels. Since global inactivation of Dio1 in Mct8-deficient mice does normalize circulating thyroid hormone levels, the underlying mechanism and relevant tissues involved remain to be elucidated. PMID:26601078

High T3, Low T4 Serum Levels in Mct8 Deficiency Are Not Caused by Increased Hepatic Conversion through Type I Deiodinase.

PubMed

Wirth, Eva K; Rijntjes, Eddy; Meyer, Franziska; Köhrle, Josef; Schweizer, Ulrich

2015-09-01

The Allan-Herndon-Dudley syndrome is a severe psychomotor retardation accompanied by specific changes in circulating thyroid hormone levels (high T3, low T4). These are caused by mutations in the thyroid hormone transmembrane transport protein monocarboxylate transporter 8 (MCT8). To test the hypothesis that circulating low T4 and high T3 levels are caused by enhanced conversion of T4 via increased activity of hepatic type I deiodinase (Dio1). We crossed mice deficient in Mct8 with mice lacking Dio1 activity in hepatocytes. Translation of the selenoenzyme Dio1 was abrogated by hepatocyte-specific inactivation of selenoprotein biosynthesis. Inactivation of Dio1 activity in the livers of global Mct8-deficient mice does not restore normal circulating thyroid hormone levels. Our data suggest that although hepatic Dio1 activity is increased in Mct8-deficient mice, it does not cause the observed abnormal circulating thyroid hormone levels. Since global inactivation of Dio1 in Mct8-deficient mice does normalize circulating thyroid hormone levels, the underlying mechanism and relevant tissues involved remain to be elucidated.

Thyroid Hormone Indices in Computer Workers with Emphasis on the Role of Zinc Supplementation.

PubMed

Amin, Ahmed Ibrahim; Hegazy, Noha Mohamed; Ibrahim, Khadiga Salah; Mahdy-Abdallah, Heba; Hammouda, Hamdy A A; Shaban, Eman Essam

2016-06-15

This study aimed to investigate the effects of computer monitor-emitted radiation on thyroid hormones and the possible protective role of zinc supplementation. The study included three groups. The first group (group B) consisted of 42 computer workers. This group was given Zinc supplementation in the form of one tablet daily for eight weeks. The second group (group A) comprised the same 42 computer workers after zinc supplementation. A group of 63 subjects whose job does not entail computer use was recruited as a control Group (Group C). All participants filled a questionnaire including detailed medical and occupational histories. They were subjected to full clinical examination. Thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4) and zinc levels were measured in all participants. TSH, FT3, FT4 and zinc concentrations were decreased significantly in group B relative to group C. In group A, all tested parameters were improved when compared with group B. The obtained results revealed that radiation emitted from computers led to changes in TSH and thyroid hormones (FT3 and FT4) in the workers. Improvement after supplementation suggests that zinc can ameliorate hazards of such radiation on thyroid hormone indices.

Placental Transfer of Perfluoroalkyl Substances and Associations with Thyroid Hormones: Beijing Prenatal Exposure Study

NASA Astrophysics Data System (ADS)

Yang, Lin; Li, Jingguang; Lai, Jianqiang; Luan, Hemi; Cai, Zongwei; Wang, Yibaina; Zhao, Yunfeng; Wu, Yongning

2016-02-01

Perfluoroalkyl substances (PFASs) have been detected in wildlife and human samples worldwide. Toxicology research showed that PFASs could interfere with thyroid hormone homeostasis. In this study, eight PFASs, fifteen PFAS precursors and five thyroid hormones were analyzed in 157 paired maternal and cord serum samples collected in Beijing around delivery. Seven PFASs and two precursors were detected in both maternal and cord sera with significant maternal-fetal correlations (r = 0.336 to 0.806, all P < 0.001). The median ratios of major PFASs concentrations in fetal versus maternal serum were from 0.25:1 (perfluorodecanoic acid, PFDA) to 0.65:1 (perfluorooctanoic acid, PFOA). Spearman partial correlation test showed that maternal thyroid stimulating hormone (TSH) was negatively correlated with most maternal PFASs (r = -0.261 to -0.170, all P < 0.05). Maternal triiodothyronin (T3) and free T3 (FT3) showed negative correlations with most fetal PFASs (r = -0.229 to -0.165 for T3; r = -0.293 to -0.169 for FT3, all P < 0.05). Our results suggest prenatal exposure of fetus to PFASs and potential associations between PFASs and thyroid hormone homeostasis in humans.

Thyroid Hormone Differentially Modulates Warburg Phenotype in Breast Cancer Cells

PubMed Central

Suhane, Sonal; Ramanujan, V Krishnan

2011-01-01

Sustenance of cancer cells in vivo critically depends on a variety of genetic and metabolic adaptations. Aerobic glycolysis or Warburg effect has been a defining biochemical hallmark of transformed cells for more than five decades although a clear molecular basis of this observation is emerging only in recent years. In this study, we present our findings that thyroid hormone exerts its non-genomic and genomic actions in two model human breast cancer cell lines differentially. By laying a clear foundation for experimentally monitoring the Warburg phenotype in living cancer cells, we demonstrate that thyroid hormone-induced modulation of bioenergetic profiles in these two model cell lines depends on the degree of Warburg phenotype that they display. Further we also show that thyroid hormone can sensitize mitochondria in aggressive, triple-negative breast cancer cells favorably to increase the chemotherapeutic efficacy in these cells. Even though the role of thyroid hormone in modulating mitochondrial metabolism has been known, the current study accentuates the critical role it plays in modulating Warburg phenotype in breast cancer cells. The clinical significance of this finding is the possibility to devise strategies for metabolically modulating aggressive triple-negative tumors so as to enhance their chemosensitivity in vivo. PMID:21945435

78 FR 37803 - Agency Information Collection Activities; Proposed Collection; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-24

... identify substances that have the potential to interact with the estrogen, androgen, or thyroid hormone... or thyroid hormone systems may proceed to Tier 2, which is designed to identify any adverse endocrine...

Developmental and Thyroid Hormone Regulation of the DNA Methyltransferase 3a Gene in Xenopus Tadpoles

PubMed Central

Kyono, Yasuhiro; Sachs, Laurent M.; Bilesimo, Patrice; Wen, Luan

2016-01-01

Thyroid hormone is essential for normal development in vertebrates. In amphibians, T3 controls metamorphosis by inducing tissue-specific gene regulation programs. A hallmark of T3 action is the modification of chromatin structure, which underlies changes in gene transcription. We found that mRNA for the de novo DNA methyltransferase (DNMT) dnmt3a, but not dnmt1, increased in the brain of Xenopus tadpoles during metamorphosis in parallel with plasma [T3]. Addition of T3 to the rearing water caused a time-dependent increase in dnmt3a mRNA in tadpole brain, tail, and hind limb. By analyzing data from a genome-wide analysis of T3 receptor (TR) binding in tadpole tail, we identified several putative T3 response elements (TREs) within the dnmt3a locus. Using in vitro DNA binding, transient transfection-reporter, and chromatin immunoprecipitation assays for TRs, we identified two functional TREs at −7.1 kb and +5.1 kb relative to the dnmt3a transcription start site. Sequence alignment showed that these TREs are conserved between two related frog species, X. laevis and X. tropicalis, but not with amniotes. Our previous findings showed that this gene is directly regulated by liganded TRs in mouse brain, and whereas the two mouse TREs are conserved among Eutherian mammals, they are not conserved in Xenopus species. Thus, although T3 regulation of dnmt3a may be an ancient pathway in vertebrates, the genomic sites responsible for hormone regulation may have diverged or arisen by convergent evolution. We hypothesize that direct T3 regulation of dnmt3a may be an important mechanism for modulating global changes in DNA methylation. PMID:27779916

[Effects of Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly peptides on hormonal activity and thyroid morphology in hypophysectomized mature and old birds].

PubMed

Kuznik, B I; Pateiuk, A V; Rusaeva, N S; Baranchugova, L M; Obydenko, V I

2011-01-01

The aim of the paper was to investigate effects of Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly peptides which were designed and synthesized on the basis of amino acid study of the hypophyseal anterior and posterior lobe peptides on the thyroid morphology and hormonal activity in mature chicken and old birds. Hypophysectomy was established to produce atrophic changes in the thyroid gland and development of secondary hypothyrosis. Administration of Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly tetrapeptides significantly prevented these impairments by increasing the levels of the thyroid-stimulating hormone (TSH) as well as T3 and T4. Restoration of the thyroid functions and morphology was registered to be greater in one-year-old chicken as compared to five-year-old ones.

Effect of zinc supplementation on the status of thyroid hormones and Na, K, And Ca levels in blood following ethanol feeding.

PubMed

Pathak, R; Dhawan, D; Pathak, A

2011-05-01

The influence of zinc (Zn) on the serum levels of triiodothyronine (T(3)), thyroxine (T(4)), thyroid-stimulating hormone (TSH) and sodium (Na), potassium (K), and calcium (Ca) was evaluated following ethanol toxicity to the rats. To achieve this, male Wistar rats (150-195 g) were given 3 ml of 30% ethanol orally, and zinc was given in the form of zinc sulfate (227 mg/l) in their drinking water daily for 8 weeks. Ethanol feeding resulted in a slight decrease in T(3) and T(4) levels and a significant increase in thyroid-stimulating hormone concentration, which may be due to the direct stimulatory effect of ethanol on thyroid. Interestingly, when zinc was given to these rats, all the above levels were brought quite close to their normal levels, thus indicating the positive role of zinc in thyroid hormone metabolism. Serum Zn and Ca levels were found to be reduced, but Na levels were raised upon ethanol feeding. Restoration of normal levels of these metals upon zinc supplementation to ethanol fed rats confirms that zinc has potential in alleviating some of the altered thyroid functions following ethanol administration.

Hypothalamic-Pituitary-Thyroid Axis Perturbations in Male Mice by CNS-Penetrating Thyromimetics.

PubMed

Ferrara, Skylar J; Bourdette, Dennis; Scanlan, Thomas S

2018-07-01

Thyromimetics represent a class of experimental drugs that can stimulate tissue-selective thyroid hormone action. As such, thyromimetics should have effects on the hypothalamic-pituitary-thyroid (HPT) axis, but details of this action and the subsequent effects on systemic thyroid hormone levels have not been reported to date. Here, we compare the HPT-axis effects of sobetirome, a well-studied thyromimetic, with Sob-AM2, a newly developed prodrug of sobetirome that targets sobetirome distribution to the central nervous system (CNS). Similar to endogenous thyroid hormone, administration of sobetirome and Sob-AM2 suppress HPT-axis gene transcript levels in a manner that correlates to their specific tissue distribution properties (periphery vs CNS, respectively). Dosing male C57BL/6 mice with sobetirome and Sob-AM2 at concentrations ≥10 μg/kg/d for 29 days induces a state similar to central hypothyroidism characterized by depleted circulating T4 and T3 and normal TSH levels. However, despite the systemic T4 and T3 depletion, the sobetirome- and Sob-AM2-treated mice do not show signs of hypothyroidism, which may result from the presence of the thyromimetic in the thyroid hormone-depleted background.

Efficacy of a Home-Based Exercise Program After Thyroidectomy for Thyroid Cancer Patients.

PubMed

Kim, Kyunghee; Gu, Mee Ock; Jung, Jung Hwa; Hahm, Jong Ryeal; Kim, Soo Kyoung; Kim, Jin Hyun; Woo, Seung Hoon

2018-02-01

The objective of this study was to determine the effect of a home-based exercise program on fatigue, anxiety, quality of life (QoL), and immune function of thyroid cancer patients taking thyroid hormone replacement after thyroidectomy. This quasi-experimental study with a non-equivalent control group included 43 outpatients taking thyroid hormone replacement after thyroidectomy (22 in the experimental group and 21 in the control group). After education about the home-based exercise program, subjects in the experimental group underwent 12 weeks of aerobic, resistance, and flexibility exercise. A comparative analysis was conducted between the two groups. Patients in the experimental group were significantly less fatigued or anxious (p < 0.01). They reported significantly improved QoL (p < 0.05) compared to those in the control group. Natural killer cell activity was significantly higher in the exercise group compared to that in the control group (p < 0.05). A home-based exercise program is effective in reducing fatigue and anxiety, improving QoL, and increasing immune function in patients taking thyroid hormone replacement after thyroidectomy. Therefore, such a home-based exercise program can be used as an intervention for patients who are taking thyroid hormone replacement after thyroidectomy.

Thyroid organotypic rat and human cultures used to investigate drug effects on thyroid function, hormone synthesis and release pathways.

PubMed

Vickers, Alison E M; Heale, Jason; Sinclair, John R; Morris, Stephen; Rowe, Josh M; Fisher, Robyn L

2012-04-01

Drug induced thyroid effects were evaluated in organotypic models utilizing either a rat thyroid lobe or human thyroid slices to compare rodent and human response. An inhibition of thyroid peroxidase (TPO) function led to a perturbation in the expression of key genes in thyroid hormone synthesis and release pathways. The clinically used thiourea drugs, methimazole (MMI) and 6-n-propyl-2-thioruacil (PTU), were used to evaluate thyroid drug response in these models. Inhibition of TPO occurred early as shown in rat thyroid lobes (2 h) and was sustained in both rat (24-48 h) and human (24 h) with ≥ 10 μM MMI. Thyroid from rats treated with single doses of MMI (30-1000 mg/kg) exhibited sustained TPO inhibition at 48 h. The MMI in vivo thyroid concentrations were comparable to the culture concentrations (~15-84 μM), thus demonstrating a close correlation between in vivo and ex vivo thyroid effects. A compensatory response to TPO inhibition was demonstrated in the rat thyroid lobe with significant up-regulation of genes involved in the pathway of thyroid hormone synthesis (Tpo, Dio1, Slc5a5, Tg, Tshr) and the megalin release pathway (Lrp2) by 24h with MMI (≥ 10 μM) and PTU (100 μM). Similarly, thyroid from the rat in vivo study exhibited an up-regulation of Dio1, Slc5a5, Lrp2, and Tshr. In human thyroid slices, there were few gene expression changes (Slc5a5, ~2-fold) and only at higher MMI concentrations (≥ 1500 μM, 24h). Extended exposure (48 h) resulted in up-regulation of Tpo, Dio1 and Lrp2, along with Slc5a5 and Tshr. In summary, TPO was inhibited by similar MMI concentrations in rat and human tissue, however an increased sensitivity to drug treatment in rat is indicated by the up-regulation of thyroid hormone synthesis and release gene pathways at concentrations found not to affect human tissue. Copyright © 2012 Elsevier Inc. All rights reserved.

Homozygous Resistance to Thyroid Hormone β: Can Combined Antithyroid Drug and Triiodothyroacetic Acid Treatment Prevent Cardiac Failure?

PubMed

Moran, Carla; Habeb, Abdelhadi M; Kahaly, George J; Kampmann, Christoph; Hughes, Marina; Marek, Jan; Rajanayagam, Odelia; Kuczynski, Adam; Vargha-Khadem, Faraneh; Morsy, Mofeed; Offiah, Amaka C; Poole, Ken; Ward, Kate; Lyons, Greta; Halsall, David; Berman, Lol; Watson, Laura; Baguley, David; Mollon, John; Moore, Anthony T; Holder, Graham E; Dattani, Mehul; Chatterjee, Krishna

2017-09-01

Resistance to thyroid hormone β (RTH β ) due to homozygous THRB defects is exceptionally rare, with only five kindreds reported worldwide. Cardiac dysfunction, which can be life-threatening, is recognized in the disorder. Here we describe the clinical, metabolic, ophthalmic, and cardiac findings in a 9-year-old boy harboring a biallelic THRB mutation (R243Q), along with biochemical, physiologic, and cardiac responses to carbimazole and triiodothyroacetic acid (TRIAC) therapy. The patient exhibits recognized features (goiter, nonsuppressed thyroid-stimulating hormone levels, upper respiratory tract infections, hyperactivity, low body mass index) of heterozygous RTH β , with additional characteristics (dysmorphic facies, winging of scapulae) and more markedly elevated thyroid hormone levels, associated with the homozygous form of the disorder. Notably, an older sibling with similar clinical features and probable homozygous RTH β had died of cardiac failure at age 13 years. Features of early dilated cardiomyopathy in our patient prompted combination treatment with carbimazole and TRIAC. Careful titration of therapy limited elevation in TSH levels and associated increase in thyroid volume. Subsequently, sustained reduction in thyroid hormones with normal TSH levels was reflected in lower basal metabolic rate, gain of lean body mass, and improved growth and cardiac function. A combination of antithyroid drug and TRIAC therapy may prevent thyrotoxic cardiomyopathy and its decompensation in homozygous or even heterozygous RTH β in which life-threatening hyperthyroid features predominate.

Regulation of vernal migration in Gambel's white-crowned sparrows: Role of thyroxine and triiodothyronine.

PubMed

Pérez, Jonathan H; Furlow, J David; Wingfield, John C; Ramenofsky, Marilyn

2016-08-01

Appropriate timing of migratory behavior is critical for migrant species. For many temperate zone birds in the spring, lengthening photoperiod is the initial cue leading to morphological, physiological and behavior changes that are necessary for vernal migration and breeding. Strong evidence has emerged in recent years linking thyroid hormone signaling to the photoinduction of breeding in birds while more limited information suggest a potential role in the regulation of vernal migration in photoperiodic songbirds. Here we investigate the development and expression of the vernal migratory life history stage in captive Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) in a hypothyroidic state, induced by chemical inhibition of thyroid hormone production. To explore possible variations in the effects of the two thyroid hormones, triiodothyronine and thyroxine, we subsequently performed a thyroid inhibition coupled with replacement therapy. We found that chemical inhibition of thyroid hormones resulted in complete abolishment of mass gain, fattening, and muscle hypertrophy associated with migratory preparation as well as resulting in failure to display nocturnal restlessness behavior. Replacement of thyroxine rescued all of these elements to near control levels while triiodothyronine replacement displayed partial or delayed rescue. Our findings support thyroid hormones as being necessary for the expression of changes in morphology and physiology associated with migration as well as migratory behavior itself. Copyright © 2016 Elsevier Inc. All rights reserved.

Food restriction in young Japanese quails: effects on growth, metabolism, plasma thyroid hormones and mRNA species in the thyroid hormone signalling pathway.

PubMed

Rønning, Bernt; Mortensen, Anne S; Moe, Børge; Chastel, Olivier; Arukwe, Augustine; Bech, Claus

2009-10-01

Young birds, in their post-natal growth period, may reduce their growth and metabolism when facing a food shortage. To examine how such responses can be mediated by endocrine-related factors, we exposed Japanese quail chicks to food restriction for either 2 days (age 6-8 days) or 5 days (age 6-11 days). We then measured growth and resting metabolic rate (RMR), and circulating 3,3',5-triiodo-l-thyronine (T3) and 3,5,3',5'-tetraiodothyronine (T4) levels as well as expression patterns of genes involved in growth (insulin-like growth factor-I: IGF-I) and thyroid hormone signalling (thyroid-stimulating hormone-beta: TSHbeta, type II iodothyronine deiodinase: D2, thyroid hormone receptors isoforms: TRalpha and TRbeta). The food-restricted chicks receiving a weight-maintenance diet showed reductions in structural growth and RMR. Plasma levels of both T3 and T4 were reduced in the food-restricted birds, and within the 5 days food-restricted group there was a positive correlation between RMR and T3. IGF-I mRNA showed significantly higher abundance in the liver of ad libitum fed birds at day 8 compared with food-restricted birds. In the brain, TSHbeta mRNA level tended to be lower in food-restricted quails on day 8 compared with controls. Furthermore, TRalpha expression was lower in the brain of food-restricted birds at day 8 compared with birds fed ad libitum. Interestingly, brain D2 mRNA was negatively correlated with plasma T3 levels, tending to increase with the length of food restriction. Overall, our results show that food restriction produced significant effects on circulating thyroid hormones and differentially affected mRNA species in the thyroid hormone signalling pathway. Thus, we conclude that the effects of food restriction observed on growth and metabolism were partly mediated by changes in the endocrine-related factors investigated.

Relationship between Na+-dependent respiration and Na+ + K+-adenosine triphosphatase activity in the action of thyroid hormone on rat jejunal mucosa.

PubMed Central

Liberman, U A; Asano, Y; Lo, C S; Edelman, I S

1979-01-01

Administration of three successive doses of triiodothyronine (T3) (50 micrograms/100 g body wt), given on alternate days to thyroidectomized and euthyroid rats, stimulated oxygen consumption (QO2) and Na+ transport-dependent respiration (QO2 [5]) in the stripped jejunal mucosa, a preparation that consisted mostly of epithelial cells. The increase in QO2(t) accounted for 57% of the increment in QO2 in the transition from the hypothyroid to the euthyroid state and for 29% of the increment in the transition from the euthyroid to the hyperthyroid state. Administration of T3 to hypothyroid rats also increased the yield of epithelial cells. Injection of T3 into thyroidectomized and euthyroid rats increased the specific activity (at Vmax) of the (Na+ + K+)-dependent adenosine triphosphatase (NaK-ATPase) in jejunal crude membrane preparations. No significant change was recorded in the activity of Mg-ATPase in the same preparation. The ratio of QO2/NaK-ATPase and QO2(t)/NaK-ATPase in the various thyroid states remained constant, indicating proportionate increased in the respiratory and enzymatic indices. The effect of administration of T3 to thyroidectomized rats on the number of NaK-ATPase units (recovered in the crude membrane preparation) was estimated by: (a) Na+ + Mg++ + ATP-dependent binding of [3H]-ouabain to crude membrane fractions, and (b) the amount of the phosphorylated intermediate formed in the NaK-ATPase reaction from AT32P(gamma). Estimates were obtained of the maximal number of [3H]ouabain binding sites (Nm) and dissociation constants (Kd). Nm for [3H]ouabain and Nak-ATPase specific activity increased to about the same extent after T3 administration to thyroidectomized rats, with no change in the apparent Kd values. The amount of phosphorylated intermediate formed in jejunal crude membrane preparations also increased significantly. Thus, thyroid hormone administration may increase the number of active Na+pump sites in the plasma membrane. The apparent increase in the number of Na+ pump sites also correlated with the hormone dependent increases in QO2 and QO2(t). Images FIGURE 1 PMID:233567

Relationship between Na+-dependent respiration and Na+ + K+-adenosine triphosphatase activity in the action of thyroid hormone on rat jejunal mucosa.

PubMed

Liberman, U A; Asano, Y; Lo, C S; Edelman, I S

1979-07-01

Administration of three successive doses of triiodothyronine (T3) (50 micrograms/100 g body wt), given on alternate days to thyroidectomized and euthyroid rats, stimulated oxygen consumption (QO2) and Na+ transport-dependent respiration (QO2 [5]) in the stripped jejunal mucosa, a preparation that consisted mostly of epithelial cells. The increase in QO2(t) accounted for 57% of the increment in QO2 in the transition from the hypothyroid to the euthyroid state and for 29% of the increment in the transition from the euthyroid to the hyperthyroid state. Administration of T3 to hypothyroid rats also increased the yield of epithelial cells. Injection of T3 into thyroidectomized and euthyroid rats increased the specific activity (at Vmax) of the (Na+ + K+)-dependent adenosine triphosphatase (NaK-ATPase) in jejunal crude membrane preparations. No significant change was recorded in the activity of Mg-ATPase in the same preparation. The ratio of QO2/NaK-ATPase and QO2(t)/NaK-ATPase in the various thyroid states remained constant, indicating proportionate increased in the respiratory and enzymatic indices. The effect of administration of T3 to thyroidectomized rats on the number of NaK-ATPase units (recovered in the crude membrane preparation) was estimated by: (a) Na+ + Mg++ + ATP-dependent binding of [3H]-ouabain to crude membrane fractions, and (b) the amount of the phosphorylated intermediate formed in the NaK-ATPase reaction from AT32P(gamma). Estimates were obtained of the maximal number of [3H]ouabain binding sites (Nm) and dissociation constants (Kd). Nm for [3H]ouabain and Nak-ATPase specific activity increased to about the same extent after T3 administration to thyroidectomized rats, with no change in the apparent Kd values. The amount of phosphorylated intermediate formed in jejunal crude membrane preparations also increased significantly. Thus, thyroid hormone administration may increase the number of active Na+pump sites in the plasma membrane. The apparent increase in the number of Na+ pump sites also correlated with the hormone dependent increases in QO2 and QO2(t).

Predictors of Malignancy in Patients with Cytologically Suspicious Thyroid Nodules

PubMed Central

Espiritu, Rachel P.; Bahn, Rebecca S.; Henry, Michael R.; Gharib, Hossein; Caraballo, Pedro J.; Morris, John C.

2011-01-01

Background Fine needle aspiration (FNA), although very reliable for cytologically benign and malignant thyroid nodules, has much lower predictive value in the case of suspicious or indeterminate nodules. We aimed to identify clinical predictors of malignancy in the subset of patients with suspicious FNA cytology. Methods We reviewed the electronic medical records of 462 patients who had FNA of thyroid nodules at our institution with a suspicious cytological diagnosis, and underwent surgery at Mayo Clinic between January 2004 and September 2008. Demographic data including age, gender, history of exposure to radiation and use of thyroid hormone was collected. The presence of single versus multiple nodules by ultrasonography, nodule size, and serum thyroid-stimulating harmone (TSH) level before thyroid surgery were recorded. Analysis of the latter was limited to patients not taking thyroid hormone or antithyroid drugs at the time of FNA. Results Of the 462 patients, 327 had lesions suspicious for follicular neoplasm (S-FN) or Hürthle cell neoplasm (S-HCN), 125 had cytology suspicious for papillary carcinoma (S-PC) and 10 had a variety of other suspicious lesions (medullary cancer, lymphoma and atypical). Malignancy rate for suspicious neoplastic lesions (FN+HCN) was ∼15%, whereas malignancy rate for lesions S-PC was 77%. Neither age, serum TSH level, or history of radiation exposure were associated with increased malignancy risk. The presence of multiple nodules (41.1% vs. 26.4%, p=0.0014) or smaller nodule size (2.6±1.8 cm vs. 2.9±1.6 cm, p=0.008) was associated with higher malignancy risk. In patients with cytology suspicious for neoplasm (FN, HCN) malignancy risk was higher in those receiving thyroid hormone therapy than in nonthyroid hormone users (37.7% vs. 16.5%, p=0.0004; odds ratio: 3.1), although serum TSH values did not differ significantly between thyroid hormone users and nonusers. Conclusion In patients with cytologically suspicious thyroid nodules, the presence of multiple nodules or smaller nodule size was associated with increased risk of malignancy. In addition, our study demonstrates for the first time, an increased risk of malignancy in patients with nodules suspicious for neoplasm who are taking thyroid hormone therapy. The reason for this association is unknown. PMID:22007937

Recent Advances in Thyroid Hormone Regulation: Toward a New Paradigm for Optimal Diagnosis and Treatment

PubMed Central

Hoermann, Rudolf; Midgley, John E. M.; Larisch, Rolf; Dietrich, Johannes W.

2017-01-01

In thyroid health, the pituitary hormone thyroid-stimulating hormone (TSH) raises glandular thyroid hormone production to a physiological level and enhances formation and conversion of T4 to the biologically more active T3. Overstimulation is limited by negative feedback control. In equilibrium defining the euthyroid state, the relationship between TSH and FT4 expresses clusters of genetically determined, interlocked TSH–FT4 pairs, which invalidates their statistical correlation within the euthyroid range. Appropriate reactions to internal or external challenges are defined by unique solutions and homeostatic equilibria. Permissible variations in an individual are much more closely constrained than over a population. Current diagnostic definitions of subclinical thyroid dysfunction are laboratory based, and do not concur with treatment recommendations. An appropriate TSH level is a homeostatic concept that cannot be reduced to a fixed range consideration. The control mode may shift from feedback to tracking where TSH becomes positively, rather than inversely related with FT4. This is obvious in pituitary disease and severe non-thyroid illness, but extends to other prevalent conditions including aging, obesity, and levothyroxine (LT4) treatment. Treatment targets must both be individualized and respect altered equilibria on LT4. To avoid amalgamation bias, clinically meaningful stratification is required in epidemiological studies. In conclusion, pituitary TSH cannot be readily interpreted as a sensitive mirror image of thyroid function because the negative TSH–FT4 correlation is frequently broken, even inverted, by common conditions. The interrelationships between TSH and thyroid hormones and the interlocking elements of the control system are individual, dynamic, and adaptive. This demands a paradigm shift of its diagnostic use. PMID:29375474

Management of hyper and hypo thyroid conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Locke, W.

1982-03-01

In hyperthyroidism, the primary objective of therapy is to reduce secretion of thyroid hormone, which can be accomplished in various ways. The stimulus to hypersecretion can be removed in some causes of hyperthyroidism; in others, hormone synthesis and release can be inhibited by drugs such as thioamides, adrenergic blocking agents, or possibly lithium or glucocorticoids. Radioactive iodine is indicated for primary therapy of uncomplicated hyperthyroidism due to Graves' disease in persons over 30 years of age (myxedema may be a complication) and for treatment of autonomous thyroid adenoma in patients who are not suitable candidates for surgery. Surgical ablation ismore » preferred for some causes of hyperthyroidism but may induce postoperative hypothyroidism. Hypothyroidism due to thyroid failure usually presents few therapeutic difficulties and can be managed simply by long-term hormone replacement. Before hormone replacement is prescribed for secondary or tertiary hypothyroidism, the other pituitary functions should be assessed.« less

Role of Oxidative Stress in Thyroid Hormone-Induced Cardiomyocyte Hypertrophy and Associated Cardiac Dysfunction: An Undisclosed Story

PubMed Central

Elnakish, Mohammad T.; Ahmed, Amany A. E.; Mohler, Peter J.; Janssen, Paul M. L.

2015-01-01

Cardiac hypertrophy is the most documented cardiomyopathy following hyperthyroidism in experimental animals. Thyroid hormone-induced cardiac hypertrophy is described as a relative ventricular hypertrophy that encompasses the whole heart and is linked with contractile abnormalities in both right and left ventricles. The increase in oxidative stress that takes place in experimental hyperthyroidism proposes that reactive oxygen species are key players in the cardiomyopathy frequently reported in this endocrine disorder. The goal of this review is to shed light on the effects of thyroid hormones on the development of oxidative stress in the heart along with the subsequent cellular and molecular changes. In particular, we will review the role of thyroid hormone-induced oxidative stress in the development of cardiomyocyte hypertrophy and associated cardiac dysfunction, as well as the potential effectiveness of antioxidant treatments in attenuating these hyperthyroidism-induced abnormalities in experimental animal models. PMID:26146529

Effects of methimazole treatment on growth hormone (GH) response to GH-releasing hormone in patients with hyperthyroidism.

PubMed

Giustina, A; Ferrari, C; Bodini, C; Buffoli, M G; Legati, F; Schettino, M; Zuccato, F; Wehrenberg, W B

1990-12-01

In vitro studies have demonstrated that thyroid hormones can enhance basal and stimulated growth hormone secretion by cultured pituitary cells. However, both in man and in the rat the effects of high thyroid hormone levels on GH secretion are unclear. The aim of our study was to test the GH response to human GHRH in hyperthyroid patients and to evaluate the effects on GH secretion of short- and long-term pharmacological decrease of circulating thyroid hormones. We examined 10 hyperthyroid patients with recent diagnosis of Graves' disease. Twelve healthy volunteers served as controls. All subjects received a bolus iv injection of GHRH(1-29)NH2, 100 micrograms. Hyperthyroid patients underwent a GHRH test one and three months after starting antithyroid therapy with methimazole, 10 mg/day po. GH levels at 15, 30, 45, 60 min and GH peak after stimulus were significantly lower in hyperthyroid patients than in normal subjects. The GH peak was also delayed in hyperthyroid patients. After one month of methimazole therapy, most of the hyperthyroid patients had thyroid hormone levels in the normal range, but they did not show significant changes in GH levels after GHRH, and the GH peak was again delayed. After three months of therapy with methimazole, the hyperthyroid patients did not show a further significant decrease in serum thyroid hormone levels. However, mean GH levels from 15 to 60 min were significantly increased compared with the control study. The GH peak after GHRH was also earlier than in the pre-treatment study.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional central hypothyroidism in the elderly.

PubMed

Sell, Maren A; Schott, Matthias; Tharandt, Lutz; Cissewski, Klaus; Scherbaum, Werner A; Willenberg, Holger S

2008-06-01

Previous studies have shown that blood concentrations of free thyroxin and basal thyroid-stimulating hormone (TSH) decrease during adult life. Suggested mechanisms include reduced thyroid activity resulting from decreased serum TSH concentrations, impairment of peripheral 5'-deiodinase, and an increase in reverse 3,5,3'-triiodothyronine due to non-thyroidal illness. However, testing of pituitary reserves leads to contradictory results and has infrequently been evaluated in studies. We investigated whether the response of TSH to thyrotropin-releasing hormone (TRH) is preserved during aging. This was tested in a cohort of 387 subjects aged 13 to 100 years in whom thyroid disease was excluded by normal thyroid ultrasound, normal values for free thyroxin, free triiodothyronin, TSH, and negative thyroid peroxidase antibodies. Serum concentrations of free thyroxin remained almost unchanged, whereas free triiodothyronin and TSH levels were lower in older subjects. In addition, the TSH response to TRH was blunted in older subjects, especially in male individuals. There is evidence that the decreased thyroid hormone levels observed in aging are due to lower TSH concentrations, and that lower TSH concentrations may be linked to an impaired pituitary activity.

A novel hypothyroid dwarfism due to the missense mutation Arg479Cys of the thyroid peroxidase gene in the mouse.

PubMed

Takabayashi, Shuji; Umeki, Kazumi; Yamamoto, Etsuko; Suzuki, Tohru; Okayama, Akihiko; Katoh, Hideki

2006-10-01

Recently, we found a novel dwarf mutation in an ICR closed colony. This mutation was governed by a single autosomal recessive gene. In novel dwarf mice, plasma levels of the thyroid hormones, T3 and T4, were reduced; however, TSH was elevated. Their thyroid glands showed a diffuse goiter exhibiting colloid deficiency and abnormal follicle epithelium. The dwarfism was improved by adding thyroid hormone in the diet. Gene mapping revealed that the dwarf mutation was closely linked to the thyroid peroxidase (Tpo) gene on chromosome 12. Sequencing of the Tpo gene of the dwarf mice demonstrated a C to T substitution at position 1508 causing an amino acid change from arginine (Arg) to cysteine (Cys) at codon 479 (Arg479Cys). Western blotting revealed that TPO protein of the dwarf mice was detected in a microsomal fraction of thyroid tissue, but peroxidase activity was not detected. These findings suggested that the dwarf mutation caused a primary congenital hypothyroidism by TPO deficiency, resulting in a defect of thyroid hormone synthesis.

[Low levels of TSH measured by a sensitive assay: do they reflect hyperthyroidism? A critical analysis of 580 cases].

PubMed

Rohmer, V; Ligeard-Ducoroy, A; Perdrisot, R; Beldent, V; Jallet, P; Bigorgne, J C

1990-05-12

Highly sensitive TSH assays make it easier to diagnose thyroid diseases. During one year, we performed 5,300 sensitive TSH assays (normal range: 0.15-4 mU/l) in various patients. The purpose of this work was to test the value of the low TSH plasma concentrations found in 580 patients. In 99.7 percent of the cases, low TSH levels were the consequence of a thyroid disorder or a treatment by thyroid hormones; non thyroidal illnesses were detected in only 0.3 percent. However, not all TSH values below 0.15 mU/l were associated with overt or occult thyrotoxicosis. When TSH was undetectable (less than 0.04 mU/l), and excluding thyroid hormone-treated patients, thyrotoxicosis was present in 97 percent of the cases. On the other hand, when TSH values were between 0.04 and 0.15 mU/l, 41 percent of the patients failed to show any sign or symptom of hyperthyroidism, although they had functioning thyroid nodules, multinodular goitre or iodine overload, or they received thyroid hormones.

Interaction of thyroid state and denervation on skeletal myosin heavy chain expression

NASA Technical Reports Server (NTRS)

Haddad, F.; Arnold, C.; Zeng, M.; Baldwin, K.

1997-01-01

The goal of this study was to examine the effects of altered thyroid state and denervation (Den) on skeletal myosin heavy chain (MHC) expression in the plantaris and soleus muscles. Rats were subjected to unilateral denervation (Den) and randomly assigned to one of three groups: (1) euthyroid; (2) hyperthyroid; (3) and hypothyroid. Denervation caused severe muscle atrophy and muscle-type specific MHC transformation. Denervation transformed the soleus to a faster muscle, and its effects required the presence of circulating thyroid hormone. In contrast, denervation transformed the plantaris to a slower muscle independently of thyroid state. Furthermore, thyroid hormone effects did not depend upon innervation status in the soleus, while they required the presence of the nerve in the plantaris. Collectively, these findings suggest that both thyroid hormone and intact nerve (a) differentially affect MHC transformations in fast and slow muscle; and (b) are important factors in regulating the optimal expression of both type I and IIB MHC genes. This research suggests that for patients with nerve damage and/or paralysis, both muscle mass and biochemical properties can also be affected by the thyroid state.

TSHR intronic polymorphisms (rs179247 and rs12885526) and their role in the susceptibility of the Brazilian population to Graves' disease and Graves' ophthalmopathy.

PubMed

Bufalo, N E; Dos Santos, R B; Marcello, M A; Piai, R P; Secolin, R; Romaldini, J H; Ward, L S

2015-05-01

Intronic thyroid-stimulating hormone receptor polymorphisms have been associated with the risk for both Graves' disease and Graves' ophthalmopathy, but results have been inconsistent among different populations. We aimed to investigate the influence of thyroid-stimulating hormone receptor intronic polymorphisms in a large well-characterized population of GD patients. We studied 279 Graves' disease patients (231 females and 48 males, 39.80 ± 11.69 years old), including 144 with Graves' ophthalmopathy, matched to 296 healthy control individuals. Thyroid-stimulating hormone receptor genotypes of rs179247 and rs12885526 were determined by Real Time PCR TaqMan(®) SNP Genotyping. A multivariate analysis showed that the inheritance of the thyroid-stimulating hormone receptor AA genotype for rs179247 increased the risk for Graves' disease (OR = 2.821; 95 % CI 1.595-4.990; p = 0.0004), whereas the thyroid-stimulating hormone receptor GG genotype for rs12885526 increased the risk for Graves' ophthalmopathy (OR = 2.940; 95 % CI 1.320-6.548; p = 0.0083). Individuals with Graves' ophthalmopathy also presented lower mean thyrotropin receptor antibodies levels (96.3 ± 143.9 U/L) than individuals without Graves' ophthalmopathy (98.3 ± 201.9 U/L). We did not find any association between the investigated polymorphisms and patients clinical features or outcome. We demonstrate that thyroid-stimulating hormone receptor intronic polymorphisms are associated with the susceptibility to Graves' disease and Graves' ophthalmopathy in the Brazilian population, but do not appear to influence the disease course.

Increased Oxidative Metabolism and Neurotransmitter Cycling in the Brain of Mice Lacking the Thyroid Hormone Transporter Slc16a2 (Mct8)

PubMed Central

Rodrigues, Tiago B.; Ceballos, Ainhoa; Grijota-Martínez, Carmen; Nuñez, Barbara; Refetoff, Samuel; Cerdán, Sebastian; Morte, Beatriz; Bernal, Juan

2013-01-01

Mutations of the monocarboxylate transporter 8 (MCT8) cause a severe X-linked intellectual deficit and neurological impairment. MCT8 is a specific thyroid hormone (T4 and T3) transporter and the patients also present unusual abnormalities in the serum profile of thyroid hormone concentrations due to altered secretion and metabolism of T4 and T3. Given the role of thyroid hormones in brain development, it is thought that the neurological impairment is due to restricted transport of thyroid hormones to the target neurons. In this work we have investigated cerebral metabolism in mice with Mct8 deficiency. Adult male mice were infused for 30 minutes with (1-13C) glucose and brain extracts prepared and analyzed by 13C nuclear magnetic resonance spectroscopy. Genetic inactivation of Mct8 resulted in increased oxidative metabolism as reflected by increased glutamate C4 enrichment, and of glutamatergic and GABAergic neurotransmissions as observed by the increases in glutamine C4 and GABA C2 enrichments, respectively. These changes were distinct to those produced by hypothyroidism or hyperthyroidism. Similar increments in glutamate C4 enrichment and GABAergic neurotransmission were observed in the combined inactivation of Mct8 and D2, indicating that the increased neurotransmission and metabolic activity were not due to increased production of cerebral T3 by the D2-encoded type 2 deiodinase. In conclusion, Mct8 deficiency has important metabolic consequences in the brain that could not be correlated with deficiency or excess of thyroid hormone supply to the brain during adulthood. PMID:24098341

Increased oxidative metabolism and neurotransmitter cycling in the brain of mice lacking the thyroid hormone transporter SLC16A2 (MCT8).

PubMed

Rodrigues, Tiago B; Ceballos, Ainhoa; Grijota-Martínez, Carmen; Nuñez, Barbara; Refetoff, Samuel; Cerdán, Sebastian; Morte, Beatriz; Bernal, Juan

2013-01-01

Mutations of the monocarboxylate transporter 8 (MCT8) cause a severe X-linked intellectual deficit and neurological impairment. MCT8 is a specific thyroid hormone (T4 and T3) transporter and the patients also present unusual abnormalities in the serum profile of thyroid hormone concentrations due to altered secretion and metabolism of T4 and T3. Given the role of thyroid hormones in brain development, it is thought that the neurological impairment is due to restricted transport of thyroid hormones to the target neurons. In this work we have investigated cerebral metabolism in mice with Mct8 deficiency. Adult male mice were infused for 30 minutes with (1-(13)C) glucose and brain extracts prepared and analyzed by (13)C nuclear magnetic resonance spectroscopy. Genetic inactivation of Mct8 resulted in increased oxidative metabolism as reflected by increased glutamate C4 enrichment, and of glutamatergic and GABAergic neurotransmissions as observed by the increases in glutamine C4 and GABA C2 enrichments, respectively. These changes were distinct to those produced by hypothyroidism or hyperthyroidism. Similar increments in glutamate C4 enrichment and GABAergic neurotransmission were observed in the combined inactivation of Mct8 and D2, indicating that the increased neurotransmission and metabolic activity were not due to increased production of cerebral T3 by the D2-encoded type 2 deiodinase. In conclusion, Mct8 deficiency has important metabolic consequences in the brain that could not be correlated with deficiency or excess of thyroid hormone supply to the brain during adulthood.

Hormonal disturbances in visceral leishmaniasis (kala-azar).

PubMed

Verde, Frederico Araujo Lima; Verde, Francisco Agenor Araujo Lima; Neto, Augusto Saboia; Almeida, Paulo César; Verde, Emir Mendonça Lima

2011-05-01

This study presents a cross-sectional analysis of the hormonal alterations of patients with visceral leishmaniasis. The diagnosis was established by the bone marrow aspiration and polymerase chain reaction test. Primary adrenal insufficiency was observed in 45.8% of patients; low aldosterone/renin plasma ratio in 69.4%; low daily urinary aldosterone excretion in 61.1%; and low transtubular potassium gradient in 68.0%. All patients had normal plasma antidiuretic hormone (ADH) concentrations, hyponatremia, and high urinary osmolality. Plasma parathyroid hormone was low in 63%; hypomagnesemia was present in 46.4%, and increased Mg(++)(EF) in 100%. Primary thyroid insufficiency was observed in 24.6%, and secondary thyroid insufficiency in 14.1%. Normal follicle-stimulating hormone plasma levels were present in 81.4%; high luteinizing hormone and low testosterone plasma levels in 58.2% of men. There are evidences of hypothalamus-pituitary-adrenal axis abnormalities, inappropriate aldosterone and ADH secretions, and presence of hypoparathyroidism, magnesium depletion, thyroid and testicular insufficiencies.

Neuro-Modulation of Immuno-Endocrine Response Induced by Kaliotoxin of Androctonus Scorpion Venom.

PubMed

Ladjel-Mendil, Amina; Martin-Eauclaire, Marie-France; Laraba-Djebari, Fatima

2016-12-01

Kaliotoxin (KTX), a specific blocker of potassium channels, exerts various toxic effects due to its action on the central nervous system. Its use in experimental model could help the understanding of the cellular and molecular mechanisms involved in the neuropathological processes related to potassium channel dysfunctions. In this study, the ability of KTX to stimulate neuro-immuno-endocrine axis was investigated. As results, the intracerebroventricular injection of KTX leads to severe structural-functional alterations of both hypothalamus and thyroid. These alterations were characterized by a massive release of hormones' markers of thyroid function associated with damaged tissue which was infiltrated by inflammatory cell and an imbalanced redox status. Taken together, these data highlight that KTX is able to modulate the neuro-endocrine response after binding to its targets leading to the hypothalamus and the thyroid stimulation, probably by inflammatory response activation and the installation of oxidative stress in these organs. © 2016 Wiley Periodicals, Inc.

Hormone levels

MedlinePlus

Blood or urine tests can determine the levels of various hormones in the body. This includes reproductive hormones, thyroid hormones, adrenal hormones, pituitary hormones, and many others. For more information, see: ...

Experimental hyperthyroidism and central mediators of stress axis and thyroid axis activity in common carp (Cyprinus carpio L.).

PubMed

Geven, Edwin J W; Verkaar, Folkert; Flik, Gert; Klaren, Peter H M

2006-12-01

The effect of experimental hyperthyroidism, realized by T(4) injection, on central mediators of the hypothalamo-pituitary-interrenal axis (HPI-axis) in common carp (Cyprinus carpio L.) was studied. Our results show that hyperthyroidism evokes a marked 3.2-fold reduction in basal plasma cortisol levels. Corticotropin-releasing hormone-binding protein (CRH-BP) mRNA levels in the hypothalamus, measured by real-time quantitative PCR, were significantly elevated by 40%, but CRH, urotensin-I, prepro-TRH, prohormone convertase-1 (PC1), and POMC mRNA levels were unchanged. In the pituitary pars distalis, PC1, CRH receptor-1, and POMC mRNA levels were unaffected, as was ACTH content. Plasma alpha-MSH concentrations were significantly elevated by 30% in hyperthyroid fish, and this was reflected in PC1 and POMC mRNA levels in pituitary pars intermedia that were increased 1.5- and 2.4-fold respectively. The alpha-MSH content of the pars intermedia was unchanged. Hyperthyroidism has profound effects on the basal levels of a central mediator, i.e., CRH-BP, of HPI-axis function in unstressed carp in vivo, and we conclude that HPI- and hypothalamo-pituitary-thyroid-axis functions are strongly interrelated. We suggest that the changes in plasma cortisol, thyroid hormone, and alpha-MSH levels reflect their concerted actions on energy metabolism.

Diagnosis and management of congenital hypothyroidism.

PubMed

Harrell, G B; Murray, P D

1998-03-01

Thyroid hormones are integral to the development and maturation of the central nervous system as well as normal growth and development. Comprehensive knowledge of the maturation and function of the thyroid gland is essential to understanding the pathophysiology of thyroid dysfunction. Early diagnosis and appropriate treatment in thyroid disease are imperative for normalization of thyroid hormone ratios. Optimal management includes early introduction and strict adherence to a regimen of L-thyroxine and routine monitoring of thyroid levels throughout life. Parents need to understand the importance of consistent medication administration and daily assessment of well-being because these actions are crucial to the attainment of an optimal level of development for infants with congenital hypothyroidism.

Is it possible to diagnose canine hypothyroidism?

PubMed

Panciera, D L

1999-04-01

A definitive diagnosis of hypothyroidism can be difficult because of the many clinical abnormalities associated with thyroid hormone deficiency, and the lack of readily available diagnostic tests with high sensitivity and specificity. Thyroid function tests should be performed only in dogs with clinical findings consistent with hypothyroidism. Measurement of serum total thyroxine (T4) concentration is a useful initial screening test since most hypothyroid dogs have values below the reference range. Serum free T4 concentration measured by equilibrium dialysis is a more sensitive and specific test of thyroid function than total T4 and is particularly useful in dogs with non-thyroidal illness or atypical clinical signs. Measurement of serum endogenous thyroid-stimulating hormone concentration is also helpful, but many hypothyroid dogs have normal results. The gold standard for diagnosis of hypothyroidism remains the thyroid-stimulating hormone response test. It should be used to confirm hypothyroidism when other tests do not agree with the clinical impression or if atypical signs or non-thyroidal illness exist or there has been administration of drugs known to alter thyroid function tests. Ultimately, a positive response to treatment is expected in hypothyroid dogs treated appropriately with levothyroxine.

Changes in the role of the thyroid axis during metamorphosis of the Japanese eel, Anguilla japonica.

PubMed

Sudo, Ryusuke; Okamura, Akihiro; Kuroki, Mari; Tsukamoto, Katsumi

2014-08-01

To clarify the role of thyroid function during metamorphosis from leptocephalus to glass eel in the Japanese eel, we examined the histology of the thyroid gland and measured whole-body concentrations of thyroid hormones, thyroxine (T4) and triiodothyronine (T3), and thyroid stimulating hormone β-subunit TSH (TSHβ) mRNA expression levels in five stages of artificially hatched eels (leptocephalus, early-metamorphosis, late-metamorphosis, glass eel, and elver). During metamorphosis, the inner colloid of thyroid follicles showed positive immunoreactivity for T4, and both T4 and T3 levels were significantly increased, whereas a small peak of TSHβ mRNA level was observed at the early-metamorphosis stage. Similarly, TSHβ mRNA levels were highest in the glass eel stage, and then decreased markedly in the elver stage. In contrast to TSHβ mRNA expression, thyroid hormones (both T4 and T3) increased further from the glass eel to elver stages. These results indicated that thyroid function in the Japanese eel was active both during and after metamorphosis. Therefore, the thyrotropic axis may play important roles not only in metamorphosis but also in subsequent inshore or upstream migrations. © 2014 Wiley Periodicals, Inc.

Thyroid hormones and thyroid disease in relation to perchlorate dose and residence near a superfund site.

PubMed

Gold, Ellen B; Blount, Benjamin C; O'Neill Rasor, Marianne; Lee, Jennifer S; Alwis, Udeni; Srivastav, Anup; Kim, Kyoungmi

2013-07-01

Perchlorate is a widely occurring contaminant, which can competitively inhibit iodide uptake and thus thyroid hormone production. The health effects of chronic low dose perchlorate exposure are largely unknown. In a community-based study, we compared thyroid function and disease in women with differing likelihoods of prior and current perchlorate exposure. Residential blocks were randomly selected from areas: (1) with potential perchlorate exposure via drinking water; (2) with potential exposure to environmental contaminants; and (3) neighboring but without such exposures. Eligibility included having lived in the area for ≥6 months and aged 20-50 years during 1988-1996 (during documented drinking water well contamination). We interviewed 814 women and collected blood samples (assayed for thyroid stimulating hormone and free thyroxine) from 431 interviewed women. Daily urine samples were assayed for perchlorate and iodide for 178 premenopausal women with blood samples. We performed multivariable regression analyses comparing thyroid function and disease by residential area and by urinary perchlorate dose adjusted for urinary iodide levels. Residential location and current perchlorate dose were not associated with thyroid function or disease. No persistent effect of perchlorate on thyroid function or disease was found several years after contaminated wells were capped.

Increased sensitivity of thyroid hormone-mediated signaling despite prolonged fasting.

PubMed

Martinez, Bridget; Scheibner, Michael; Soñanez-Organis, José G; Jaques, John T; Crocker, Daniel E; Ortiz, Rudy M

2017-10-01

Thyroid hormones (TH) can increase cellular metabolism. Food deprivation in mammals is typically associated with reduced thyroid gland responsiveness, in an effort to suppress cellular metabolism and abate starvation. However, in prolonged-fasted, elephant seal pups, cellular TH-mediated proteins are up-regulated and TH levels are maintained with fasting duration. The function and contribution of the thyroid gland to this apparent paradox is unknown and physiologically perplexing. Here we show that the thyroid gland remains responsive during prolonged food deprivation, and that its function and production of TH increase with fasting duration in elephant seals. We discovered that our modeled plasma TH data in response to exogenous thyroid stimulating hormone predicted cellular signaling, which was corroborated independently by the enzyme expression data. The data suggest that the regulation and function of the thyroid gland in the northern elephant seal is atypical for a fasted animal, and can be better described as, "adaptive fasting". Furthermore, the modeling data help substantiate the in vivo responses measured, providing unique insight on hormone clearance, production rates, and thyroid gland responsiveness. Because these unique endocrine responses occur simultaneously with a nearly strict reliance on the oxidation of lipid, these findings provide an intriguing model to better understand the TH-mediated reliance on lipid metabolism that is not otherwise present in morbidly obese humans. When coupled with cellular, tissue-specific responses, these data provide a more integrated assessment of thyroidal status that can be extrapolated for many fasting/food deprived mammals. Copyright © 2017 Elsevier Inc. All rights reserved.

Computational Modeling of Thyroid Hormone Regulated Neurodevelopment for Chemical Prioritization (SOT)

EPA Science Inventory

Thyroid hormones (TH) are critical for normal brain development. Environmental chemicals may disrupt TH homeostasis through a variety of physiological systems including membrane transporters, serum transporters, synthesis and catabolic enzymes, and nuclear receptors. Current comp...

RISK ASSESSMENT OF THYROID HORMONE DISRUPTION AND MIXTURES IN MARINE BIOTA

EPA Science Inventory

Varieties of chemicals alter thyroid hormones (THs) in vertabrates. The importance of THs during neurodevelopment, suggest that these chemicals would likely be developmental neurotoxicants. A number of epidemiological studies have demonstrated associations between exposure to p...

Hypothalamic AMPK and fatty acid metabolism mediate thyroid regulation of energy balance.

PubMed

López, Miguel; Varela, Luis; Vázquez, María J; Rodríguez-Cuenca, Sergio; González, Carmen R; Velagapudi, Vidya R; Morgan, Donald A; Schoenmakers, Erik; Agassandian, Khristofor; Lage, Ricardo; Martínez de Morentin, Pablo Blanco; Tovar, Sulay; Nogueiras, Rubén; Carling, David; Lelliott, Christopher; Gallego, Rosalía; Oresic, Matej; Chatterjee, Krishna; Saha, Asish K; Rahmouni, Kamal; Diéguez, Carlos; Vidal-Puig, Antonio

2010-09-01

Thyroid hormones have widespread cellular effects; however it is unclear whether their effects on the central nervous system (CNS) contribute to global energy balance. Here we demonstrate that either whole-body hyperthyroidism or central administration of triiodothyronine (T3) decreases the activity of hypothalamic AMP-activated protein kinase (AMPK), increases sympathetic nervous system (SNS) activity and upregulates thermogenic markers in brown adipose tissue (BAT). Inhibition of the lipogenic pathway in the ventromedial nucleus of the hypothalamus (VMH) prevents CNS-mediated activation of BAT by thyroid hormone and reverses the weight loss associated with hyperthyroidism. Similarly, inhibition of thyroid hormone receptors in the VMH reverses the weight loss associated with hyperthyroidism. This regulatory mechanism depends on AMPK inactivation, as genetic inhibition of this enzyme in the VMH of euthyroid rats induces feeding-independent weight loss and increases expression of thermogenic markers in BAT. These effects are reversed by pharmacological blockade of the SNS. Thus, thyroid hormone-induced modulation of AMPK activity and lipid metabolism in the hypothalamus is a major regulator of whole-body energy homeostasis.

Hypothalamic AMPK and fatty acid metabolism mediate thyroid regulation of energy balance

PubMed Central

López, Miguel; Varela, Luis; Vázquez, María J.; Rodríguez-Cuenca, Sergio; González, Carmen R.; Velagapudi, Vidya R.; Morgan, Donald A.; Schoenmakers, Erik; Agassandian, Khristofor; Lage, Ricardo; de Morentin, Pablo Blanco Martínez; Tovar, Sulay; Nogueiras, Rubén; Carling, David; Lelliott, Christopher; Gallego, Rosalía; Orešič, Matej; Chatterjee, Krishna; Saha, Asish K.; Rahmouni, Kamal; Diéguez, Carlos; Vidal-Puig, Antonio

2010-01-01

Thyroid hormones have widespread cellular effects; however it is unclear whether their effects on the central nervous system (CNS) contribute to global energy balance. Here, we demonstrate that either whole body hyperthyroidism or central administration of triiodothyronine (T3) decreases the activity of hypothalamic AMP-activated protein kinase (AMPK), increases sympathetic nervous system (SNS) activity and upregulates thermogenic markers in brown adipose tissue (BAT). Inhibition of the lipogenic pathway in the ventromedial nucleus of the hypothalamus (VMH) prevents CNS-mediated activation of BAT by thyroid hormone and reverses the weight loss associated with hyperthyroidism. Similarly inhibition of thyroid hormone receptors (TRs) in the VMH reverses the weight loss associated with hyperthyroidism. This regulatory mechanism depends on AMPK inactivation as genetic ablation of this enzyme in the VMH of euthyroid rats induces feeding-independent weight loss and increases expression of thermogenic markers in BAT. These effects are reversed by pharmacological blockade of the SNS. Thus, thyroid-hormone-induced modulation of AMPK activity and lipid metabolism in the hypothalamus is an important regulator of energy homeostasis. PMID:20802499

Trimester specific reference intervals for thyroid function tests in normal Indian pregnant women.

PubMed

Sekhri, Tarun; Juhi, Juhi Agarwal; Wilfred, Reena; Kanwar, Ratnesh S; Sethi, Jyoti; Bhadra, Kuntal; Nair, Sirimavo; Singh, Satveer

2016-01-01

Accurate assessment of thyroid function during pregnancy is critical, for initiation of thyroid hormone therapy, as well as for adjustment of thyroid hormone dose in hypothyroid cases. We evaluated pregnant women who had no past history of thyroid disorders and studied their thyroid function in each trimester. 86 normal pregnant women in the first trimester of pregnancy were selected for setting reference intervals. All were healthy, euthyroid and negative for thyroid peroxidase antibody (TPOAb). These women were serially followed throughout pregnancy. 124 normal nonpregnant subjects were selected for comparison. Thyrotropin (TSH), free thyroxine (FT4), free triiodothyronine (FT3) and anti-TPO were measured using Roche Elecsys 1010 analyzer. Urinary iodine content was determined by simple microplate method. The 2.5th and 97.5th percentiles were calculated as the reference intervals for thyroid hormone levels during each trimester. SPSS (version 14.0, SPSS Inc., Chicago, IL, USA) was used for data processing and analysis. The reference intervals for the first, second and third trimesters for the following parameters: TSH 0.09-6.65, 0.51-6.66, 0.91-4.86 µIU/mL, FT4 9.81-18.53, 8.52-19.43, 7.39-18.28 pM/L and FT3 3.1-6.35, 2.39-5.12, 2.57-5.68 pM/L respectively. Thyroid hormone concentrations significantly differed during pregnancy at different stages of gestation. The pregnant women in the study had median urinary iodine concentration of 150-200 µg/l during each trimester. The trimester-specific reference intervals for thyroid tests during pregnancy have been established for pregnant Indian women serially followed during pregnancy using 2.5th and 97.5th percentiles.

[Study of serum thrombomodulin(TM) levels in patients with hyper- or hypo- thyroidism].

PubMed

Soma, M; Maeda, Y; Matsuura, R; Sasaki, I; Kasakura, S; Saeki, Y; Ikekubo, K; Ishihara, T; Kurahachi, H; Sasaki, S; Tagami, T; Nakao, K

1997-01-01

We studies a relationship between the serum levels of thrombomodulin(TM) and the thyroid functions. Serum TM levels were measured in 48 patients with Graves' disease, 17 patients with primary hypothyroidism, 7 patients with subacute thyroiditis, 5 patients with painless thyroiditis and 2 patients with systematic Refetoff syndrome. These patients did not have malignant tumor, kidney failure, or blood vessel injury. Control sera were obtained from 42 healthy subjects. Serum levels of TM in patients with untreated Graves' disease were significantly higher(p < 0.001) compared with those in controls. Serum levels of TM in patients with hypothyroidism were not significantly changed as compared with those of controls. There were a positive correlation between the serum levels of TM and FT3 as well as FT4. Serial determinations of the serum levels of TM and thyroid function(FT3, FT4 and TH) in patients with Graves' disease during treatment showed that both the serum levels of TM and thyroid hormones (FT3 and FT4) lowered progressively during treatment. After normalization of serum FT3 and FT4, the serum TM levels returned to normal. However, the serum levels of TM in patients with destructive thyroiditis and Refetoff syndrome were normal in spite of high serum levels of thyroid hormones. These data suggest that an increase in serum levels of TM is not the direct result of thyroid hormones themselves but is the result of the prolonged hypermetabolic state induced by their peripheral activities. Thyroid hormones may stimulate the synthesis or metabolism of TM on the surface of vascular endothelial cells in the patients with Graves' disease.

Analysis of current thyroid function test ordering practices.

PubMed

Kluesner, Joseph K; Beckman, Darrick J; Tate, Joshua M; Beauvais, Alexis A; Kravchenko, Maria I; Wardian, Jana L; Graybill, Sky D; Colburn, Jeffrey A; Folaron, Irene; True, Mark W

2018-04-01

Current guidelines recommend thyroid stimulating hormone (TSH) alone as the best test to detect and monitor thyroid dysfunction, yet free thyroxine (FT4) and free triiodothyronine (FT3) are commonly ordered when not clinically indicated. Excessive testing can lead to added economic burden in an era of rising healthcare costs, while rarely contributing to the evaluation or management of thyroid disease. To evaluate our institution's practice in ordering thyroid function tests (TFTs) and to identify strategies to reduce inappropriate FT4 and FT3 testing. A record of all TFTs obtained in the San Antonio Military Health System during a 3-month period was extracted from the electronic medical record. The TFTs of interest were TSH, FT4, thyroid panel (TSH + FT4), FT3, total thyroxine (T4), and total triiodothyronine (T3). These were categorized based on the presence or absence of hypothyroidism. Between August 1 and October 31, 2016, there were 38 214 individual TFTs ordered via 28 597 total laboratory requests; 11 486 of these requests were in patients with a history of hypothyroidism. The number (percent) of laboratory requests fell into these patterns: TSH alone 14 919 (52.14%), TSH + FT4 7641 (26.72%), FT3 alone 3039 (10.63%), FT4 alone 1219 (4.26%), TSH + FT4 + FT3 783 (2.74%), and others 996 (3.48%); 36.0% of TFTs ordered were free thyroid hormones. Projected out to a year, using Department of Defense laboratory costs, $317 429 worth of TFTs would be ordered, with free thyroid hormone testing accounting for $107 720. Inappropriate ordering of free thyroid hormone tests is common. In an era of rising healthcare costs, inappropriate thyroid function testing is an ideal target for efforts to reduce laboratory overutilization, which in our system, could save up to $120 000 per year. Further evaluation is needed to determine strategies that can reduce excessive thyroid hormone testing. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Transcriptomic and phenotypic profiling in developing zebrafish exposed to thyroid hormone receptor agonists

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haggard, Derik E.; Noyes, Pamela D.; Waters, Katrina M.

There is a need to develop novel, high-throughput screening and prioritization methods to identify chemicals with adverse estrogen, androgen, and thyroid activity to protect human health and the environment and is of interest to the Endocrine Disruptor Screening Program. The current aim is to explore the utility of zebrafish as a testing paradigm to classify endocrine activity using phenotypically anchored transcriptome profiling. Transcriptome analysis was conducted on embryos exposed to 25 estrogen-, androgen-, or thyroid-active chemicals at a concentration that elicited adverse malformations or mortality at 120 hours post-fertilization in 80% of the animals exposed. Analysis of the top 1000more » significant differentially expressed transcripts across all treatments identified a unique transcriptional and phenotypic profile for thyroid hormone receptor agonists, which can be used as a biomarker screen for potential thyroid hormone agonists.« less

Thyroid Function in Human Obesity: Underlying Mechanisms.

PubMed

Fontenelle, L C; Feitosa, M M; Severo, J S; Freitas, T E C; Morais, J B S; Torres-Leal, F L; Henriques, G S; do Nascimento Marreiro, D

2016-12-01

Obesity is associated with several metabolic and endocrine disorders; and changes in plasma concentrations, secretion patterns, and clearance of various hormones are observed in obese patients. In this context, recent research has shown that overweight can influence the function of the thyroid gland, usually leading to increased thyrotropin concentrations and changes in the ratio between the hormones triiodothyronine and thyroxine, though within the normal range. The etiology of these changes is still unclear; however, several mechanisms have been proposed including the adaptive process to increase energy expenditure, hyperleptinemia, changes in the activity of deiodinases, the presence of thyroid hormones resistance, chronic low-grade inflammation, and insulin resistance. Although the clinical implications have not been clarified, studies suggest that these changes in the thyroid function of obese individuals may contribute to the worsening of metabolic complications and the development of diseases in the thyroid gland. © Georg Thieme Verlag KG Stuttgart · New York.

Pax2.1 is required for the development of thyroid follicles in zebrafish.

PubMed

Wendl, Thomas; Lun, Klaus; Mione, Marina; Favor, Jack; Brand, Michael; Wilson, Stephen W; Rohr, Klaus B

2002-08-01

The thyroid gland is an organ primarily composed of endoderm-derived follicular cells. Although disturbed embryonic development of the thyroid gland leads to congenital hypothyroidism in humans and mammals, the underlying principles of thyroid organogenesis are largely unknown. In this study, we introduce zebrafish as a model to investigate the molecular and genetic mechanisms that control thyroid development. Marker gene expression suggests that the molecular pathways of early thyroid development are essentially conserved between fish and mammals. However during larval stages, we find both conserved and divergent features of development compared with mammals. A major difference is that in fish, we find evidence for hormone production not only in thyroid follicular cells, but also in an anterior non-follicular group of cells. We show that pax2.1 and pax8, members of the zebrafish pax2/5/8 paralogue group, are expressed in the thyroid primordium. Whereas in mice, only Pax8 has a function during thyroid development, analysis of the zebrafish pax2.1 mutant no isthmus (noi(-/-)) demonstrates that pax2.1 has a role comparable with mouse Pax8 in differentiation of the thyroid follicular cells. Early steps of thyroid development are normal in noi(-/-), but later expression of molecular markers is lost and the formation of follicles fails. Interestingly, the anterior non-follicular site of thyroid hormone production is not affected in noi(-/-). Thus, in zebrafish, some remaining thyroid hormone synthesis takes place independent of the pathway leading to thyroid follicle formation. We suggest that the noi(-/-) mutant serves as a new zebrafish model for hypothyroidism.

Thyroid hormones and menstrual cycle function in a longitudinal cohort of premenopausal women.

PubMed

Jacobson, Melanie H; Howards, Penelope P; Darrow, Lyndsey A; Meadows, Juliana W; Kesner, James S; Spencer, Jessica B; Terrell, Metrecia L; Marcus, Michele

2018-05-01

Previous studies have reported that hyperthyroid and hypothyroid women experience menstrual irregularities more often compared with euthyroid women, but reasons for this are not well-understood and studies on thyroid hormones among euthyroid women are lacking. In a prospective cohort study of euthyroid women, this study characterised the relationship between thyroid hormone concentrations and prospectively collected menstrual function outcomes. Between 2004-2014, 86 euthyroid premenopausal women not lactating or taking hormonal medications participated in a study measuring menstrual function. Serum thyroid hormones were measured before the menstrual function study began. Women then collected first morning urine voids and completed daily bleeding diaries every day for three cycles. Urinary oestrogen and progesterone metabolites (estrone 3-glucuronide (E 1 3G) and pregnanediol 3-glucuronide (Pd3G)) and follicle-stimulating hormone were measured and adjusted for creatinine (Cr). Total thyroxine (T 4 ) concentrations were positively associated with Pd3G and E 1 3G. Women with higher (vs lower) T 4 had greater luteal phase maximum Pd3G (Pd3G = 11.7 μg/mg Cr for women with high T 4 vs Pd3G = 9.5 and 8.1 μg/mg Cr for women with medium and low T 4 , respectively) and greater follicular phase maximum E 1 3G (E 1 3G = 41.7 ng/mg Cr for women with high T 4 vs E 1 3G = 34.3 and 33.7 ng/mg Cr for women with medium and low T 4 , respectively). Circulating thyroid hormone concentrations were associated with subtle differences in menstrual cycle function outcomes, particularly sex steroid hormone levels in healthy women. Results contribute to the understanding of the relationship between thyroid function and the menstrual cycle, and may have implications for fertility and chronic disease. © 2018 John Wiley & Sons Ltd.

Calcitonin: regional distribution of the hormone and its binding sites in the human brain and pituitary.

PubMed

Fischer, J A; Tobler, P H; Kaufmann, M; Born, W; Henke, H; Cooper, P E; Sagar, S M; Martin, J B

1981-12-01

Immunoreactive calcitonin (CT), indistinguishable from human CT-(1-32) and its sulfoxide, has been identified in extracts of the hypothalamus, the pituitary, and the thyroid obtained from human subjects at autopsy. DCT concentrations were highest in a region encompassing the posterior hypothalamus, the median eminence, and the pituitary; intermediate in the substantia nigra, the anterior hypothalamus, the globus pallidus, and the inferior colliculus; and low in the caudate nucleus, the hippocampus, the amygdala, and the cerebral and cerebellar cortices. Specific CT binding measured with 125I-labeled salmon CT was highest in homogenates of the posterior hypothalamus and the median eminence, shown to contain the highest concentrations of endogenous CT in the brain; CT binding was less than 12% of hypothalamic binding in all of the other regions of the brain examined and was negligible in the pituitary. Half-maximal binding was achieved with 0.1 nM nonradioactive salmon CT-(1-32), and the binding was directed to structural or conformational sites, or both, in the COOH-terminal half of salmon CT. The rank order of the inhibition of the binding by CT from different species and analogues of the human hormone was the same as in receptors on a human lymphoid cell line (Moran, J., Hunziker, W. & Fischer, J. A. (1978) Proc. Natl. Acad. Sci. USA 75, 3984-3988). The functional role of CT and of its binding sites in the brain remains to be elucidated.

Comparison of in vitro and in vivo bioassays to measure thyroid hormone disrupting activity in water extracts.

PubMed

Leusch, Frederic D L; Aneck-Hahn, Natalie H; Cavanagh, Jo-Anne E; Du Pasquier, David; Hamers, Timo; Hebert, Armelle; Neale, Peta A; Scheurer, Marco; Simmons, Steven O; Schriks, Merijn

2018-01-01

Environmental chemicals can induce thyroid disruption through a number of mechanisms including altered thyroid hormone biosynthesis and transport, as well as activation and inhibition of the thyroid receptor. In the current study six in vitro bioassays indicative of different mechanisms of thyroid disruption and one whole animal in vivo assay were applied to 9 model compounds and 4 different water samples (treated wastewater, surface water, drinking water and ultra-pure lab water; both unspiked and spiked with model compounds) to determine their ability to detect thyroid active compounds. Most assays correctly identified and quantified the model compounds as agonists or antagonists, with the reporter gene assays being the most sensitive. However, the reporter gene assays did not detect significant thyroid activity in any of the water samples, suggesting that activation or inhibition of the thyroid hormone receptor is not a relevant mode of action for thyroid endocrine disruptors in water. The thyroperoxidase (TPO) inhibition assay and transthyretin (TTR) displacement assay (FITC) detected activity in the surface water and treated wastewater samples, but more work is required to assess if this activity is a true measure of thyroid activity or matrix interference. The whole animal Xenopus Embryonic Thyroid Assay (XETA) detected some activity in the unspiked surface water and treated wastewater extracts, but not in unspiked drinking water, and appears to be a suitable assay to detect thyroid activity in environmental waters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ophthalmic Graves's disease: natural history and detailed thyroid function studies.

PubMed Central

Teng, C S; Yeo, P P

1977-01-01

Of 27 patients with ophthalmic Graves's disease (OGD) who had been clinically euthyroid three years previously, one became clinically hyperthyroid and seven overtly hypothyroid. Improvement in eye signs was associated with a return to normal of thyroidal suppression by triiodothyronine (T3) and of the response of thyroid-stimulating hormone (TSH) to thyrotrophin-releasing hormone (TRH). Of a further 30 patients with OGD who had not been studied previously, three were overtly hypothyroid. Of the combined series, 46 patients were euthyroid, 18 (40%) of whom had an impaired or absent TSH response to TRH, and 3(6-7%) an exaggerated response. Eleven out of 37 patients (29-7%) had abnormal results in the T3 suppression test. There was a significant correlation between thyroidal suppression by T3 and the TSH response to TRH. Total serum concentrations of both T3 and thyroxine (T4) were closely correlated with T3 suppressibility and TRH responsiveness. Free T4 and T3 (fT3) concentrations were normal in all but three patients, in whom raised fT3 was accompanied by abnormal TSH responses and thyroidal suppression. The presence of normal free thyroid hormone concentrations in patients with impaired or absent TSH responses to TRH is interesting and challenges the concept that free thyroid hormones are the major controlling factors in the feedback control of TSH. PMID:576414

[Impact of thyroid diseases on bone].

PubMed

Tsourdi, E; Lademann, F; Siggelkow, H

2018-05-09

Thyroid hormones are key regulators of skeletal development in childhood and bone homeostasis in adulthood, and thyroid diseases have been associated with increased osteoporotic fractures. Hypothyroidism in children leads to an impaired skeletal maturation and mineralization, but an adequate and timely substitution with thyroid hormones stimulates bone growth. Conversely, hyperthyroidism at a young age accelerates skeletal development, but may also cause short stature because of a premature fusion of the growth plates. Hypothyroidism in adults causes an increase in the duration of the remodeling cycle and, thus, leads to low bone turnover and enhanced mineralization, but an association with a higher fracture risk is less well established. In adults, a surplus of thyroid hormones enhances bone turnover, mostly due to an increased bone resorption driven by osteoclasts. Thus, hyperthyroidism is a well-recognized cause of high-bone turnover secondary osteoporosis, resulting in an increased susceptibility to fragility fractures. Subclinical hyperthyroidism, especially resulting from endogenous disease, also has an adverse effect on bone mineral density and is associated with fractures. In most patients with overt or subclinical hyperthyroidism restoration of the euthyroid status reverses bone loss. In postmenopausal women who receive thyroid-stimulating hormone suppression therapy because of thyroid cancer, antiresorptive treatments may be indicated. Overall, extensive data support the importance of a euthyroid status for bone mineral accrual and growth in childhood as well as maintenance of bone health in adulthood.

TSH Compensates Thyroid-Specific IGF-I Receptor Knockout and Causes Papillary Thyroid Hyperplasia

PubMed Central

Müller, Kathrin; Führer, Dagmar; Mittag, Jens; Klöting, Nora; Blüher, Matthias; Weiss, Roy E.; Many, Marie-Christine; Schmid, Kurt Werner

2011-01-01

Although TSH stimulates all aspects of thyroid physiology IGF-I signaling through a tyrosine kinase-containing transmembrane receptor exhibits a permissive impact on TSH action. To better understand the importance of the IGF-I receptor in the thyroid in vivo, we inactivated the Igf1r with a Tg promoter-driven Cre-lox system in mice. We studied male and female mice with thyroidal wild-type, Igf1r+/−, and Igf1r−/− genotypes. Targeted Igf1r inactivation did transiently reduce thyroid hormone levels and significantly increased TSH levels in both heterozygous and homozygous mice without affecting thyroid weight. Histological analysis of thyroid tissue with Igf1r inactivation revealed hyperplasia and heterogeneous follicle structure. From 4 months of age, we detected papillary thyroid architecture in heterozygous and homozygous mice. We also noted increased body weight of male mice with a homozygous thyroidal null mutation in the Igf1r locus, compared with wild-type mice, respectively. A decrease of mRNA and protein for thyroid peroxidase and increased mRNA and protein for IGF-II receptor but no significant mRNA changes for the insulin receptor, the TSH receptor, and the sodium-iodide-symporter in both Igf1r+/− and Igf1r−/− mice were detected. Our results suggest that the strong increase of TSH benefits papillary thyroid hyperplasia and completely compensates the loss of IGF-I receptor signaling at the level of thyroid hormones without significant increase in thyroid weight. This could indicate that the IGF-I receptor signaling is less essential for thyroid hormone synthesis but maintains homeostasis and normal thyroid morphogenesis. PMID:21980075

Waterborne exposure to BPS causes thyroid endocrine disruption in zebrafish larvae

PubMed Central

Zhang, Dan-hua; Zhou, En-xiang; Yang, Zhu-lin

2017-01-01

Bisphenol S (BPS) is widely used as a raw material in industry, resulting in its ubiquitous distribution in natural environment, including the aqueous environment. However, the effect of BPS on the thyroid endocrine system is largely unknown. In this study, zebrafish (Danio rerio) embryos were exposed to BPS at 1, 3, 10, and 30 μg/L, from 2 h post-fertilization (hpf) to 168hpf. Bioconcentration of BPS and whole-body thyroid hormones (THs), thyroid-stimulating hormone (TSH) concentrations as well as transcriptional profiling of key genes related to the hypothalamic-pituitary-thyroid (HPT) axis were examined. Chemical analysis indicated that BPS was accumulated in zebrafish larvae. Thyroxine (T4) and triiodothyronine (T3) levels were significantly decreased at ≥ 10 and 30 μg/L of BPS, respectively. However, TSH concentration was significantly induced in the 10 and 30 μg/L BPS-treated groups. After exposure to BPS, the mRNA expression of corticotrophin releasing hormone (crh) and thyroglobulin (tg) genes were up-regulated at ≥10 μg/L of BPS, in a dose-response manner. The transcription of genes involved in thyroid development (pax8) and synthesis (sodium/iodide symporter, slc5a5) were also significantly increased in the 30 μg/L of BPS treatment group. Moreover, exposure to 10 μg/L or higher concentration of BPS significantly up-regulated genes related to thyroid hormone metabolism (deiodinases, dio1, dio2 and uridinediphosphate glucoronosyltransferases, ugt1ab), which might be responsible for the altered THs levels. However, the transcript of transthyretin (ttr) was significantly down-regulated at ≥ 3 μg/L of BPS, while the mRNA levels of thyroid hormone receptors (trα and trβ) and dio3 remained unchanged. All the results indicated that exposure to BPS altered the whole-body THs and TSH concentrations and changed the expression profiling of key genes related to HPT axis, thus triggering thyroid endocrine disruption. PMID:28467477

Subclinical hypothyroidism: A common finding in adult patients with cyanotic congenital heart disease.

PubMed

Bak, Peter; Hjortshøj, Cristel S; Gaede, Peter; Idorn, Lars; Søndergaard, Lars; Jensen, Annette S

2018-03-01

Cyanotic congenital heart disease is a systemic disease, with effects on multiple organ systems. A high prevalence of subclinical hypothyroidism (SCH) has been reported in a small cohort of cyanotic congenital heart disease patients. Subclinical hypothyroidism has been associated with various adverse cardiovascular effects, as well as an increased risk of progression to overt hypothyroidism. The aim of this study was to examine the prevalence of SCH in cyanotic congenital heart disease patients, consider possible etiologies, and evaluate thyroid function over time. First, 90 clinically stable cyanotic congenital heart disease patients were examined with blood samples (thyroid-stimulating hormone, C-reactive protein, hemoglobin, hematocrit, and N-terminal pro-brain-natriuretic peptide) in a cross-sectional descriptive study. Second, a longitudinal follow-up study of 43 patients originating from the first study part, was carried out. These patients had thyroid function parameters (thyroid-stimulating hormone, thyroid hormones, and thyroid peroxidase antibodies) evaluated biannually. Elevated thyroid-stimulating hormone was present in 24% of the 90 screened patients. During follow-up (6.5 ± 1.0 years), SCH (defined as ≥2 consecutive elevated thyroid-stimulating hormone values) was present in 26%. Three patients progressed to overt hypothyroidism. Patients with SCH were younger (34 ± 12 vs 42 ± 16 years; P = .01) and had a lower oxygen saturation (80 ± 5 vs 84 ± 6%; P = .03). Subclinical hypothyroidism is a very common finding in cyanotic congenital heart disease. This is not associated with increased levels of C-reactive protein, heart failure, or autoimmunity but appears to be associated with cyanosis and age. Since the clinical impact of SCH is uncertain, further studies are needed to determine this. Regular thyroid evaluation is recommended in cyanotic congenital heart disease patients since SCH can develop to overt hypothyroidism. © 2017 Wiley Periodicals, Inc.

Restoration of Cardiac Tissue Thyroid Hormone Status in Experimental Hypothyroidism: A Dose-Response Study in Female Rats

PubMed Central

Weltman, Nathan Y.; Ojamaa, Kaie; Savinova, Olga V.; Chen, Yue-Feng; Schlenker, Evelyn H.; Zucchi, Riccardo; Saba, Alessandro; Colligiani, Daria; Pol, Christine J.

2013-01-01

Thyroid hormones (THs) play a pivotal role in regulating cardiovascular homeostasis. To provide a better understanding of the coordinated processes that govern cardiac TH bioavailability, this study investigated the influence of serum and cardiac TH status on the expression of TH transporters and cytosolic binding proteins in the myocardium. In addition, we sought to determine whether the administration of T3 (instead of T4) improves the relationship between THs in serum and cardiac tissue and cardiac function over a short-term treatment period. Adult female Sprague Dawley rats were made hypothyroid by 7 weeks treatment with the antithyroid drug 6-n-propyl-2-thiouracil (PTU). After establishing hypothyroidism, rats were assigned to 1 of 5 graded T3 dosages plus PTU for a 2-week dose-response experiment. Untreated, age-matched rats served as euthyroid controls. PTU was associated with depressed serum and cardiac tissue T3 and T4 levels, arteriolar atrophy, altered TH transporter and cytosolic TH binding protein expression, fetal gene reexpression, and cardiac dysfunction. Short-term administration of T3 led to a mismatch between serum and cardiac tissue TH levels. Normalization of serum T3 levels was not associated with restoration of cardiac tissue T3 levels or cardiac function. In fact, a 3-fold higher T3 dosage was necessary to normalize cardiac tissue T3 levels and cardiac function. Importantly, this study provides the first comprehensive data on the relationship between altered TH status (serum and cardiac tissue), cardiac function, and the coordinated in vivo changes in cardiac TH membrane transporters and cytosolic TH binding proteins in altered TH states. PMID:23594789

Bisphenol A alternatives bisphenol S and bisphenol F interfere with thyroid hormone signaling pathway in vitro and in vivo.

PubMed

Zhang, Yin-Feng; Ren, Xiao-Min; Li, Yuan-Yuan; Yao, Xiao-Fang; Li, Chuan-Hai; Qin, Zhan-Fen; Guo, Liang-Hong

2018-06-01

The wide use of the alternatives to bisphenol A (BPA) has raised concerns about their potential toxicities. Considering the disrupting activity of BPA on thyroid hormone (TH) signaling, we investigated whether bisphenol S (BPS) and bisphenol F (BPF), two leading alternatives, could interfere with TH signaling pathway using a series of assays in vitro and in vivo. In the fluorescence competitive binding assay, we found BPS and BPF, like BPA, bound to TH receptors (TRα and TRβ), with the binding potencies an order of magnitude lower than BPA (BPA > BPF > BPS). Molecular docking data also show their binding potencies to TRs. In the coactivator recruitment assay, BPS and BPF recruited coactivator to TRβ but not TRα, with weaker potencies than BPA. Correspondingly, agonistic actions of the three bisphenols in the absence or presence of T3 were observed in the TR-mediated reporter gene transcription assay. Also, all the three bisphenols induced TH-dependent GH3 cell proliferation, whereas BPA and BPF inhibited T3 induction in the presence of T3. As for in vivo assay, the three bisphenols like T3 induced TH-response gene transcription in Pelophylax nigromaculatus tadpoles, but in the presence of T3 altered T3-induced gene transcription in a biphasic concentration-response manner. These results for the first time demonstrate that BPS and BPF, like BPA, have potential to interfere with TH signaling pathway, i.e., they generally activate TH signaling in the absence of T3, but in the presence of TH, display agonistic or/and antagonistic actions under certain condition. Our study highlights the potential risks of BPS and BPF as BPA alternatives. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rationalization of the Irrational Neuropathologic Basis of Hypothyroidism-Olfaction Disorders Paradox: Experimental Study.

PubMed

Aydin, Nazan; Ramazanoglu, Leyla; Onen, Mehmet Resid; Yilmaz, Ilhan; Aydin, Mehmet Dumlu; Altinkaynak, Konca; Calik, Muhammet; Kanat, Ayhan

2017-11-01

Hypothyroidism is defined as an underactive thyroid gland and one of the reasons for inadequate stimulation of thyroid is dysfunction of the hormone regulating brain centers. Olfaction disorders have been considered as a problem in hypothyroidism. It has been hypothesized that olfaction disorders reduce olfactory stimulation and diminished olfactory stimulus may trigger hypothyroidism. In this study, an examination was made of the thyroid hormone levels, histologic features of thyroid glands, and vagal nerve network degradation in an experimental animal model of olfactory bulbectomy (OBX). A total of 25 rats were divided into control (n = 5), SHAM (n = 5), and OBX (n = 15) groups and were followed up for 8 weeks. Thyroid hormone levels were measured before (1 time), during the experiment (1 time/month) and the animals were decapitated. The olfactory bulbs, dorsal motor nucleus of the vagal nerves, and thyroid gland sections were stained with hematoxylin-eosin and tunnel dye to determine OBX-related damage. Specimens were analyzed stereologically to evaluate neuron density of the vagal nucleus and hormone-filled total follicle volume (TFV) per cubic centimeter, and these were statistically compared with thyroid hormone levels. The mean degenerated neuron density of the vagal nucleus was 21 ± 8/mm 3 . TFV and triiodothyronine (T 3 )-thyroxine (T 4 ) levels were measured as TFV, (312 ± 91) × 10 6 μm 3 /cm 3 ; T 3 , 105 μg/dl; T 4 , 1.89 μg/dl in control (group I). Mean degenerated neuron density, 56 ± 12/mm 3 ; TFV, (284 ± 69) × 10 6 μm 3 /cm 3 ; T 3 , 103 μg/dl; T 4 , 1.85 μg/dl in SHAM (group II). Mean degenerated neuron density, 235 ± 64/mm 3 ; TFV, (193 ± 34) × 10 6 μm 3 /cm 3 ; T 3 , 86 μg/dl; T 4 , 1.37 μg/dl in the OBX group (group III). The TFV were significantly diminished because of apoptotic degradation in olfactory bulbs and thyroid gland with decreased T 3 - T 4 levels with increased thyroid-stimulating hormone levels in OBX-applied animals of subarachnoid hemorrhage (P < 0.005). The results suggested that diminished hormone secretion as a result of thyroid gland degradation results in both olfaction loss and vagal complex degeneration in OBX animals, contrary to the common belief that anosmia results from hypothyroidism. Copyright © 2017 Elsevier Inc. All rights reserved.

Thyroid Hormones and Changes in Body Weight and Metabolic Parameters in Response to Weight-Loss Diets: The POUNDS LOST Trial

PubMed Central

Liu, Gang; Liang, Liming; Bray, George A.; Qi, Lu; Hu, Frank B.; Rood, Jennifer; Sacks, Frank M.; Sun, Qi

2017-01-01

Background The role of thyroid hormones in diet-induced weight loss and subsequent weight regain is largely unknown. Objectives To examine the associations between thyroid hormones and changes in body weight and resting metabolic rate (RMR) in a diet-induced weight-loss setting. Subjects/Methods Data analysis was conducted among 569 overweight and obese participants aged 30–70 years with normal thyroid function participating in the 2-year POUNDS LOST randomized clinical trial. Changes in body weight and RMR were assessed during the 2-year intervention. Thyroid hormones (free triiodothyronine [T3], free thyroxine [T4], total T3, total T4, and thyroid stimulating hormone [TSH]), anthropometric measurements, and biochemical parameters were assessed at baseline, 6 months, and 24 months. Results Participants lost an average of 6.6 kg of body weight during the first 6 months and subsequently regained an average of 2.7 kg of body weight over the remaining period from 6–24 months. Baseline free T3 and total T3 were positively associated, whereas free T4 was inversely associated, with baseline body weight, body mass index, and RMR. Total T4 and TSH were not associated with these parameters. Higher baseline free T3 and free T4 levels were significantly associated with a greater weight loss during the first 6 months (P<0.05) after multivariate adjustments including dietary intervention groups and baseline body weight. Comparing extreme tertiles, the multivariate-adjusted weight loss ± standard error was −3.87±0.9 vs −5.39±0.9 kg for free T3 (P trend=0.02) and −4.09±0.9 vs −5.88±0.9 kg for free T4 (P trend=0.004). The thyroid hormones did not predict weight regain in 6–24 months. A similar pattern of associations was also observed between baseline thyroid hormones and changes in RMR. In addition, changes in free T3 and total T3 levels were positively associated with changes in body weight, RMR, body fat mass, blood pressure, glucose, insulin, triglycerides, and leptin at 6 months and 24 months (all P<0.05). Conclusions In this diet-induced weight-loss setting, higher baseline free T3 and free T4 predicted more weight loss, but not weight regain among overweight and obese adults with normal thyroid function. These findings reveal a novel role of thyroid hormones in body weight regulation and may help identify individuals more responsive to weight-loss diets. PMID:28138133

Developmental Thyroid Hormone Disruption: Prevalence, Environmental Contaminants and Neurodevelopmental Consequences

EPA Science Inventory

Thyroid hormones (TH) are critical for growth and development and particularly brain development. There are numerous environmental agents that lead to marginal reductions of circulating TH. Although it is clear that severe developmental hypothyroidism is profoundly detrimental to...

Effects of a Model Inducer, Phenobarbital, on Thyroid Hormone Glucuronidation in Rat Hepatocytes

EPA Science Inventory

In vivo, hepatic enzyme inducers such as phenobarbital (PB) decrease circulating thyroid hormone (TH) concentrations. This decrease in circulating TH occurs in part through extrathyroidal mechanisms. Specifically, through the induction of hepatic xenobiotic metabolizing enzymes...

Massive pleural and pericardial effusion due to hypothyroidism in a patient with a surgically treated thyroid-stimulating hormone-producing pituitary adenoma.

PubMed

Lee, Ji-Hoon; Park, MinA; Park, Myung Jae; Jo, Yong Suk

2018-05-14

Hypothyroidism is relatively rare etiology of serositis with effusion, but massive pleural effusion is very unusual. This is a report of massive pleural effusion in patient taking methimazole after surgical resection of thyroid-stimulating hormone (TSH)-producing pituitary adenoma (TSHoma). The patient was clinically and biochemically hypothyroid and responded well to discontinuation of methimazole and thyroid hormone replacement therapy. When assessing patients with pleural effusion, we should not rely on laboratory test results alone, as a detailed medical history and thorough physical examination could be more useful.

[Pediatric reference intervals : retrospective study on thyroid hormone levels].

PubMed

Ladang, A; Vranken, L; Luyckx, F; Lebrethon, M-C; Cavalier, E

2017-01-01

Defining reference range is an essential tool for diagnostic. Age and sexe influences on thyroid hormone levels have been already discussed. In this study, we are defining a new pediatric reference range for TSH, FT3 and FT4 for Cobas C6000 analyzer. To do so, we have taken in account 0 to 18 year old outclinic patients. During the first year of life, thyroid hormone levels change dramatically before getting stabilized around 3 years old. We also compared our results to those obtained in a Canadian large-scale prospective study (the CALIPER initiative).

In Vivo Regulation of Human Skeletal Muscle Gene Expression by Thyroid Hormone

PubMed Central

Clément, Karine; Viguerie, Nathalie; Diehn, Maximilian; Alizadeh, Ash; Barbe, Pierre; Thalamas, Claire; Storey, John D.; Brown, Patrick O.; Barsh, Greg S.; Langin, Dominique

2002-01-01

Thyroid hormones are key regulators of metabolism that modulate transcription via nuclear receptors. Hyperthyroidism is associated with increased metabolic rate, protein breakdown, and weight loss. Although the molecular actions of thyroid hormones have been studied thoroughly, their pleiotropic effects are mediated by complex changes in expression of an unknown number of target genes. Here, we measured patterns of skeletal muscle gene expression in five healthy men treated for 14 days with 75 μg of triiodothyronine, using 24,000 cDNA element microarrays. To analyze the data, we used a new statistical method that identifies significant changes in expression and estimates the false discovery rate. The 381 up-regulated genes were involved in a wide range of cellular functions including transcriptional control, mRNA maturation, protein turnover, signal transduction, cellular trafficking, and energy metabolism. Only two genes were down-regulated. Most of the genes are novel targets of thyroid hormone. Cluster analysis of triiodothyronine-regulated gene expression among 19 different human tissues or cell lines revealed sets of coregulated genes that serve similar biologic functions. These results define molecular signatures that help to understand the physiology and pathophysiology of thyroid hormone action. [The list of transcripts corresponding to up-regulated and down-regulated genes is available as a web supplement at http://www.genome.org.] PMID:11827947

Thyroid Hormone Receptors Control Developmental Maturation of the Middle Ear and the Size of the Ossicular Bones

PubMed Central

Cordas, Emily A.; Ng, Lily; Hernandez, Arturo; Kaneshige, Masahiro; Cheng, Sheue-Yann

2012-01-01

Thyroid hormone is critical for auditory development and has well-known actions in the inner ear. However, less is known of thyroid hormone functions in the middle ear, which contains the ossicles (malleus, incus, stapes) that relay mechanical sound vibrations from the outer ear to the inner ear. During the later stages of middle ear development, prior to the onset of hearing, middle ear cavitation occurs, involving clearance of mesenchyme from the middle ear cavity while the immature cartilaginous ossicles attain appropriate size and ossify. Using in situ hybridization, we detected expression of Thra and Thrb genes encoding thyroid hormone receptors α1 and β (TRα1 and TRβ, respectively) in the immature ossicles, surrounding mesenchyme and tympanic membrane in the mouse. Thra+/PV mice that express a dominant-negative TRα1 protein exhibited deafness with elevated auditory thresholds and a range of middle ear abnormalities including chronic persistence of mesenchyme in the middle ear into adulthood, markedly enlarged ossicles, and delayed ossification of the ossicles. Congenitally hypothyroid Tshr−/− mice and TR-deficient Thra1−/−;Thrb−/− mice displayed similar abnormalities. These findings demonstrate that middle ear maturation is TR dependent and suggest that the middle ear is a sensitive target for thyroid hormone in development. PMID:22253431

The Bottlenose Dolphin (Tursiops truncatus) as a Model to Understand Variation in Stress and Reproductive Hormone Measures in Relation to Sampling Matrix, Demographics, and Environmental Factors

DTIC Science & Technology

2015-09-30

ranging individuals support the existence of these same stress response pathways in marine mammals. 2 While the HPA axis and physiological processes...relying upon methods which include capture-release health assessments. Stress and reproductive hormones (cortisol, aldosterone , thyroid, testosterone...Analyses Hormone concentrations (cortisol, aldosterone , reproductive and thyroid hormones) in serum samples were analyzed by Cornell’s Animal Health

The Bottlenose Dolphin (Tursiops truncatus) as a Model to Understand Variation in Stress and Reproductive Hormone Measures in Relation to Sampling Matrix, Demographics, and Environmental Factors

DTIC Science & Technology

2014-09-30

axis and physiological processes driven by the GCs are essential for an individual’s ability to respond and adapt to stress, prolonged elevation of...health assessments. Stress and reproductive hormones (cortisol, aldosterone , thyroid, testosterone, progesterone) have been routinely measured in blood...in South Carolina. Laboratory Analyses Hormone concentrations (cortisol, aldosterone , reproductive and thyroid hormones) in serum samples have

Hyperthyroidism caused by a pituitary thyrotrophin-secreting tumour with excessive secretion of thyrotrophin-releasing hormone and subsequently followed by Graves' disease in a middle-aged woman.

PubMed

Kamoi, K; Mitsuma, T; Sato, H; Yokoyama, M; Washiyama, K; Tanaka, R; Arai, O; Takasu, N; Yamada, T

1985-11-01

A 46-year-old woman had signs of thyrotoxicosis and galactorrhoea. Serum immunoreactive TSH and its alpha-subunit increased in the presence of high serum triiodothyronine (T3), thyroxine (T4), and free T4 concentrations, whereas beta-subunit TSH was undetectable. Exogenous TRH failed to increase serum TSH. Serum TSH was markedly suppressed by glucocorticoid, but was increased by antithyroid drug. L-Dopa or bromocriptine partially suppressed, but nomifensine had no influence on serum TSH. Serum prolactin (Prl) was above normal and markedly increased by TRH, but depressed by bromocriptine and not suppressed by nomifensine. Plasma TRH was normal in the hyperthyroid state, but was increased by glucocorticoid and antithyroid drug. Excess thyroid hormone depressed plasma TRH concentrations. Basal serum GH levels were constantly low. Transsphenoidal removal of the tumour normalized serum hormones (T3, T4 free T4, TSH, alpha-subunit and Prl), and eradicated the clinical signs of hyperthyroidism and galactorrhoea. Histological study of the tumour tissue demonstrated both thyrotrophes and somatotrophes. A reciprocal relationship between serum TSH and T4 concentrations shifted to a higher level before but was normalized after removal of the tumour. Ten months later, the clinical signs of thyrotoxicosis and the increase in serum thyroid hormone recurred without a concomitant increase in serum TSH and its alpha-subunit. Thyroidal auto-antibodies were slightly positive, but thyrotrophin-binding inhibitor immunoglobulin (TBII) was negative. Administration of antithyroid drug produced a euthyroid state, but 3 years later, discontinuation of the treatment resulted in recurrent hyperthyroidism without suppressed plasma TRH and with no evidence of regrowth of the pituitary tumour. It is suggested that the patient initially had hyperthyroidism owing to excessive TSH secretion from the tumour caused by abnormal TRH secretion, and subsequently had hyperthyroidism owing to Graves' disease.

Evolution of the Antisense Overlap between Genes for Thyroid Hormone Receptor and Rev-erbα and Characterization of an Exonic G-Rich Element That Regulates Splicing of TRα2 mRNA

PubMed Central

Munroe, Stephen H.; Morales, Christopher H.; Duyck, Tessa H.; Waters, Paul D.

2015-01-01

The α-thyroid hormone receptor gene (TRα) codes for two functionally distinct proteins: TRα1, the α-thyroid hormone receptor; and TRα2, a non-hormone-binding variant. The final exon of TRα2 mRNA overlaps the 3’ end of Rev-erbα mRNA, which encodes another nuclear receptor on the opposite strand of DNA. To understand the evolution of this antisense overlap, we sequenced these genes and mRNAs in the platypus Orthorhynchus anatinus. Despite its strong homology with other mammals, the platypus TRα/Rev-erbα locus lacks elements essential for expression of TRα2. Comparative analysis suggests that alternative splicing of TRα2 mRNA expression evolved in a stepwise fashion before the divergence of eutherian and marsupial mammals. A short G-rich element (G30) located downstream of the alternative 3’splice site of TRα2 mRNA and antisense to the 3’UTR of Rev-erbα plays an important role in regulating TRα2 splicing. G30 is tightly conserved in eutherian mammals, but is absent in marsupials and monotremes. Systematic deletions and substitutions within G30 have dramatically different effects on TRα2 splicing, leading to either its inhibition or its enhancement. Mutations that disrupt one or more clusters of G residues enhance splicing two- to three-fold. These results suggest the G30 sequence can adopt a highly structured conformation, possibly a G-quadruplex, and that it is part of a complex splicing regulatory element which exerts both positive and negative effects on TRα2 expression. Since mutations that strongly enhance splicing in vivo have no effect on splicing in vitro, it is likely that the regulatory role of G30 is mediated through linkage of transcription and splicing. PMID:26368571

Combination of didactic lectures and review sessions in endocrinology leads to improvement in student performance as measured by assessments.

PubMed

Qureshi, Ayisha; Cozine, Cassy; Rizvi, Farwa

2013-03-01

There can be no single best way of learning, and each teaching mode has its own merits and demerits. Didactic lectures in and of themselves are insufficient, whereas a problem-based tutorial alone can be as ineffective. This study was conducted to determine if a problem-based review after didactic lectures would lead to better student performance. To compare performance, the same student group was taught three units of endocrinology (growth hormone, thyroid hormone, and diabetes). Students were divided into the following three groups: diabetes didactic lectures only, growth hormone didactic lectures plus review, and thyroid hormone didactic lectures plus review. All three topics were covered in the didactic lectures, but only growth hormone and thyroid hormone topics were covered in the review session. At the end of the course, all students were given formative assessments in the form of multiple-choice questions. A highly significant increase (P < 0.000) in the percentage of correct responses on the questions covering growth hormone (mean: 0.838, SD: 0.158) and thyroid hormone (mean: 0.686, SD: 0.232) compared with diabetes (mean: 0.478, SD: 0.259) was observed. In conclusion, this study provides further evidence that the combination of didactic lectures and an active review session leads to an improvement in student performance.

Stereoselective degradation and thyroid endocrine disruption of lambda-cyhalothrin in lizards (Eremias argus) following oral exposure.

PubMed

Chang, Jing; Hao, Weiyu; Xu, Yuanyuan; Xu, Peng; Li, Wei; Li, Jianzhong; Wang, Huili

2018-01-01

The disturbance of the thyroid system and elimination of chiral pyrethroid pesticides with respect to enantioselectivity in reptiles have so far received limited attention by research. In this study, bioaccumulation, thyroid gland lesions, thyroid hormone levels, and hypothalamus-pituitary-thyroid axis-related gene expression in male Eremias argus were investigated after three weeks oral administration of lambda-cyhalothrin (LCT) enantiomers. In the lizard liver, the concentration of LCT was negatively correlated with the metabolite-3-phenoxybenzoic acid (PBA) level during 21 days of exposure. (+)-LCT exposure induced a higher thyroid follicular epithelium height than (-)-LCT exposure. The thyroxine levels were increased in both treated groups while only (+)-LCT exposure induced a significant change in the triiodothyronine (T3) level. In addition, the expressions of hypothalamus-pituitary-thyroid axis-related genes including thyroid hormone receptors (trs), deiodinases (dios), uridinediphosphate glucuronosyltransferase (udp), and sulfotransferase (sult) were up-regulated after exposure to the two enantiomers. (+)-LCT treatment resulted in higher expression of trs and (-)-LCT exposure led to greater stimulation of dios in the liver, which indicated PBA-induced antagonism on thyroid hormone receptors and LCT-induced disruption of thyroxine (T4) deiodination. The results suggest the (-)-LCT exposure causes higher residual level in lizard liver while induces less disruption on lizard thyroid activity than (+)-LCT. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Mechanism to Enhance Cellular Responsivity to Hormone Action: Krüppel-Like Factor 9 Promotes Thyroid Hormone Receptor-β Autoinduction During Postembryonic Brain Development

PubMed Central

Hu, Fang; Knoedler, Joseph R.

2016-01-01

Thyroid hormone (TH) receptor (TR)-β (trb) is induced by TH (autoinduced) in Xenopus tadpoles during metamorphosis. We previously showed that Krüppel-like factor 9 (Klf9) is rapidly induced by TH in the tadpole brain, associates in chromatin with the trb upstream region in a developmental stage and TH-dependent manner, and forced expression of Klf9 in the Xenopus laevis cell line XTC-2 accelerates and enhances trb autoinduction. Here we investigated whether Klf9 can promote trb autoinduction in tadpole brain in vivo. Using electroporation-mediated gene transfer, we transfected plasmids into premetamorphic tadpole brain to express wild-type or mutant forms of Klf9. Forced expression of Klf9 increased baseline trb mRNA levels in thyroid-intact but not in goitrogen-treated tadpoles, supporting that Klf9 enhances liganded TR action. As in XTC-2 cells, forced expression of Klf9 enhanced trb autoinduction in tadpole brain in vivo and also increased TH-dependent induction of the TR target genes klf9 and thbzip. Consistent with our previous mutagenesis experiments conducted in XTC-2 cells, the actions of Klf9 in vivo required an intact N-terminal region but not a functional DNA binding domain. Forced expression of TRβ in tadpole brain by electroporation-mediated gene transfer increased baseline and TH-induced TR target gene transcription, supporting a role for trb autoinduction during metamorphosis. Our findings support that Klf9 acts as an accessory transcription factor for TR at the trb locus during tadpole metamorphosis, enhancing trb autoinduction and transcription of other TR target genes, which increases cellular responsivity to further TH action on developmental gene regulation programs. PMID:26886257

Modulation of the neonatal pituitary and adrenocortical responses to stress by thyroid hormones in the rat: effects of hypothyroidism and hyperthyroidism.

PubMed

Walker, C D; Sizonenko, P C; Aubert, M L

1989-09-01

Neonatal rats exhibit a period of diminished pituitary and adrenocortical responses to stress during the first 2 weeks of life. Since thyroid hormones are known to affect brain development, modulation of these responses to stress by alterations in thyroid hormone status have been investigated in hypothyroid (Hypo) and hyperthyroid (Hyper) rat pups. Changes in ACTH and corticosterone (B) levels were measured under basal and stress conditions (3 min exposure to ether vapors) in neonates of various ages (day 5-21). Basal T4 and corticosterone-binding globulin (CBG) levels were also measured. Hypo pups were obtained from methimazole-treated mothers and hyperthyroidism was induced by daily subcutaneous injections of L-T4 (100 micrograms/kg BW) from birth on. In Hyper rats, premature onset of ACTH and B responses to stress was observed in 5-day-old rats while significant ACTH and B secretion only appeared by day 10 in vehicle-injected rats. By contrast, ACTH and B responses to stress were delayed in Hypo pups and only occurred by day 21. The lack of ACTH and B responses to stress of 14-day-old Hypo rats could be reversed by one single L-T4 injection (100 micrograms/kg BW) given 24 h, but not 4 h prior to exposure to stress. On day 21, smaller (p less than 0.05) stress-induced ACTH release was observed both in Hypo and Hyper rats compared to intact rats, concomitant with a diminished ACTH secretion following exogenous ovine CRF (10 micrograms/kg BW, i.p.) administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Critical role of types 2 and 3 deiodinases in the negative regulation of gene expression by T₃in the mouse cerebral cortex.

PubMed

Hernandez, Arturo; Morte, Beatriz; Belinchón, Mónica M; Ceballos, Ainhoa; Bernal, Juan

2012-06-01

Thyroid hormones regulate brain development and function through the control of gene expression, mediated by binding of T(3) to nuclear receptors. Brain T(3) concentration is tightly controlled by homeostatic mechanisms regulating transport and metabolism of T(4) and T(3). We have examined the role of the inactivating enzyme type 3 deiodinase (D3) in the regulation of 43 thyroid hormone-dependent genes in the cerebral cortex of 30-d-old mice. D3 inactivation increased slightly the expression of two of 22 positively regulated genes and significantly decreased the expression of seven of 21 negatively regulated genes. Administration of high doses of T(3) led to significant changes in the expression of 12 positive genes and three negative genes in wild-type mice. The response to T(3) treatment was enhanced in D3-deficient mice, both in the number of genes and in the amplitude of the response, demonstrating the role of D3 in modulating T(3) action. Comparison of the effects on gene expression observed in D3 deficiency with those in hypothyroidism, hyperthyroidism, and type 2 deiodinase (D2) deficiency revealed that the negative genes are more sensitive to D2 and D3 deficiencies than the positive genes. This observation indicates that, in normal physiological conditions, D2 and D3 play critical roles in maintaining local T(3) concentrations within a very narrow range. It also suggests that negatively and positively regulated genes do not have the same physiological significance or that their regulation by thyroid hormone obeys different paradigms at the molecular or cellular levels.

TAAR1 induces a disturbed GSK3β phosphorylation in recurrent miscarriages through the ODC

PubMed Central

Stavrou, Stavroula; Gratz, Michael; Tremmel, Eileen; Kuhn, Christina; Hofmann, Simone; Heidegger, Helene; Peryanova, Mina; Hermelink, Kerstin; Hutter, Stefan; Toth, Bettina; Mayr, Doris; Mahner, Sven; Jeschke, Udo; Vattai, Aurelia

2018-01-01

Objectives Thyroid hormones play an important role in the maintenance of pregnancy. Their derivates, endogenous amines, act via binding to the trace amine-associated receptor (TAAR1). The aim of our study was to analyse the regulation of TAAR1, serine/threonine kinase (pGSK3β) and ornithine decarboxylase (ODC) in placentas of healthy pregnancies, spontaneous (SM) and recurrent miscarriages (RM) and to investigate the influence of thyroid hormone derivates on TAAR1 expression in trophoblast model cells in vitro. Methods Patients with SM (n = 15) and RM (n = 15) were compared with patients with healthy pregnancies (n = 15) (pregnancy weeks 7–13 each). Immunohistochemistry was applied to analyse placental TAAR1, pGSK3β and ODC expression. Protein expression of the receptors after stimulation with T3, T1AM and RO5203548 in BeWo trophoblast model cells was determined via Western blot. Double-immunofluorescence was used to determine placental expression of TAAR1 and ODC. Results Levels of TAAR1, pGSK3β and ODC were higher in placentas of RM in comparison to healthy controls. Stimulation of BeWo cells with T3, T1AM and RO5203548 significantly increased TAAR1 expression. ODC expression in BeWo cells was upregulated through T3. Via double-immunofluorescence, TAAR1 and ODC-positive EVT could be detected. Conclusions Upregulation of placental TAAR1 may indicate an increased decarboxylation of thyroid hormones in miscarriages. Patients with RM may have a lack of T3 through an enhanced transformation of T3 into T1AM induced by the ODC. Future investigations could be carried out to analyse what role a prophylactic T3 substitution plays for patients. PMID:29472377

Recurrent hamburger thyrotoxicosis

PubMed Central

Parmar, Malvinder S.; Sturge, Cecil

2003-01-01

RECURRENT EPISODES OF SPONTANEOUSLY RESOLVING HYPERTHYROIDISM may be caused by release of preformed hormone from the thyroid gland after it has been damaged by inflammation (recurrent silent thyroiditis) or by exogenous administration of thyroid hormone, which might be intentional or surreptitious (thyrotoxicosis factitia). Community-wide outbreaks of “hamburger thyrotoxicosis” resulting from inadvertent consumption of beef contaminated with bovine thyroid gland have been previously reported. Here we describe a single patient who experienced recurrent episodes of this phenomenon over an 11-year period and present an approach to systematically evaluating patients with recurrent hyperthyroidism. PMID:12952802

Thyrotoxicosis.

PubMed

Seigel, Stuart C; Hodak, Steven P

2012-03-01

Hyperthyroidism describes the sustained increase in thyroid hormone biosynthesis and secretion by a thyroid gland with increased metabolism. Although the use of radioiodine scanning serves as a useful surrogate that may help characterize the cause of thyrotoxicosis, it only indirectly addresses the underlying physiologic mechanism driving the increase in serum thyroid hormones. In this article, thyrotoxic states are divided into increased or decreased thyroid metabolic function. In addition to the diagnosis, clinical presentation, and treatment of the various causes of hyperthyroidism, a section on functional imaging and appropriate laboratory testing is included. Copyright © 2012 Elsevier Inc. All rights reserved.

What Does the Thyroid Gland Do?

MedlinePlus

... it helps other cells do their job. hypothyroidism (hi-poh-THY-royd-izm): when your thyroid gland ... thyroid hormone (“hypo” means ‘under’ or ‘below’). hyperthyroidism (hi-purr-THY-royd-izm): when your thyroid gland ...

Combination treatment with T4 and T3: toward personalized replacement therapy in hypothyroidism?

PubMed

Biondi, Bernadette; Wartofsky, Leonard

2012-07-01

Levothyroxine therapy is the traditional lifelong replacement therapy for hypothyroid patients. Over the last several years, new evidence has led clinicians to evaluate the option of combined T(3) and T(4) treatment to improve the quality of life, cognition, and peripheral parameters of thyroid hormone action in hypothyroidism. The aim of this review is to assess the physiological basis and the results of current studies on this topic. We searched Medline for reports published with the following search terms: hypothyroidism, levothyroxine, triiodothyronine, thyroid, guidelines, treatment, deiodinases, clinical symptoms, quality of life, cognition, mood, depression, body weight, heart rate, cholesterol, bone markers, SHBG, and patient preference for combined therapy. The search was restricted to reports published in English since 1970, but some reports published before 1970 were also incorporated. We supplemented the search with records from personal files and references of relevant articles and textbooks. Parameters analyzed included the rationale for combination treatment, the type of patients to be selected, the optimal T(4)/T(3) ratio, and the potential benefits of this therapy on symptoms of hypothyroidism, quality of life, mood, cognition, and peripheral parameters of thyroid hormone action. The outcome of our analysis suggests that it may be time to consider a personalized regimen of thyroid hormone replacement therapy in hypothyroid patients. Further prospective randomized controlled studies are needed to clarify this important issue. Innovative formulations of the thyroid hormones will be required to mimic a more perfect thyroid hormone replacement therapy than is currently available.

Quantitative analysis of in-vivo responses of reproductive and thyroid endpoints in male goldfish exposed to monocrotophos pesticide.

PubMed

Zhang, Xiaona; Liu, Wei; Wang, Jun; Tian, Hua; Wang, Wei; Ru, Shaoguo

2018-09-01

Cross-regulation occurs at many points between the hypothalamic-pituitary-gonad (HPG) and hypothalamic-pituitary-thyroid (HPT) axes. Monocrotophos (MCP) pesticide could disrupt HPG and HPT axes, but its direct target within the endocrine system is still unclear. In the present study, hormone concentrations and transcriptional profiles of HPG and HPT genes were examined in male goldfish (Carassius auratus) exposed to 0, 4, 40, and 400 μg/L MCP for 2, 4, 8, and 12 d. In vivo data were analyzed by multiple linear regression and correlation analysis, quantitatively indicating that MCP-induced plasma 17β-estradiol (E 2 ) levels were most associated with alteration of cyp19a transcription, which was also a potential point indirectly modulated by the MCP-altered thyroid hormones (THs) status; disturbance of THs pathways was most related with effect of MCP on regulation of the hypothalamic-pituitary hormones involved in the thyroid system, and the increased E 2 levels might enhance the impact of MCP on HPT axis by modulating hepatic deiodinase expression. Our finding, based on these correlational data, gave a whole view of the regulations, especially on the cross-talk between sex hormone and thyroid hormone pathways upon exposure to chemicals with unknown direct target in vivo, and cautions should be exercised when developing adverse outcome pathway networks for reproductive and thyroidal endocrine disruption. Copyright © 2018 Elsevier Inc. All rights reserved.

Effect of tetrapeptides Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly on the structure and function of the thyroid gland in neonatally hypophysectomized chickens.

PubMed

Kuznik, B I; Pateyuk, A V; Rusaeva, N S

2008-01-01

Tetrapeptides Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly were synthesized on the basis of amino acid composition of pituitary cytomedins. Administration of these tetrapeptides to hypophysectomized chickens for 40 days was followed by an increase in the concentrations of thyrotropic hormone and thyroid hormones and recovery of thyroid gland structure.

Biochemistry of hyperthyroidism and hypothyroidism*

PubMed Central

Hoch, Frederic L.

1968-01-01

The thyroid hormones act directly on mitochondria, and thereby control the transformation of the energy derived from oxidations into a form utilizable by the cell. Through their direct actions on mitochondria, the hormones also control indirectly the rate of protein synthesis and thereby the amount of oxidative apparatus in the cell. A rationale for the effects of thyroid hormone excess or deficiency is based upon studies of the mechanism of thyroid hormone action. In hypothyroidism, slow fuel consumption leads to a low output of utilizable energy. In hyperthyroidism, rapid fuel consumption leads to a high energy output, but as efficiency decreases, the utilizable energy produced decreases. Many of the chemical and physical features of these diseases can be reduced to changes in available energy. PMID:4871771

TRICLOSAN ALTERS THYROID HORMONES HOMEOSTASIS VIA UP-REGULATION OF HEPATIC CATABOLISM.

EPA Science Inventory

Triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) is a chlorinated phenolic antibacterial compound used in household and hygiene products. The structural similarity of triclosan to thyroid hormones, in vitro studies demonstrating activation of the human pregnane X receptor (PXR)...