1
|
Anitha S, Upadhyay S, Grando S, Kane-Potaka J. Does consumption of pearl millet cause goiter? A systematic review of existing evidence. Front Nutr 2024; 11:1323336. [PMID: 38515523 PMCID: PMC10955131 DOI: 10.3389/fnut.2024.1323336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 02/16/2024] [Indexed: 03/23/2024] Open
Abstract
Millets (defined here to also include sorghum) have been consumed in Asian and African countries for centuries, and have in recent years become increasingly popular in Western countries, especially because of their proven health and environmental benefits. Nevertheless, some concerns have been raised that their consumption can interfere with thyroid function and cause goiter. This systematic review aimed to investigate the link between millet consumption and goiter. We found nine papers that were relevant to this topic and included them in this review. Among nine papers eight were on pearl millet and one was on fonio millet. The findings of the review indicate that published literature on the association of pearl millet and increased goiter prevalence are not compelling and strong enough to assert that pearl millet consumed as part of a balanced diet can lead to goiter in the general population. To ensure appropriate factual messaging about millets, we need more scientific research to conclusively state whether millet consumption mediates goitrogenic effects.
Collapse
Affiliation(s)
- Seetha Anitha
- Nutrition Expert, Asia-Pacific Association of Agricultural Research Institutions, Bangkok, Thailand
| | - Shweta Upadhyay
- Nutrition Expert, Asia-Pacific Association of Agricultural Research Institutions, Bangkok, Thailand
| | | | - Joanna Kane-Potaka
- Nutrition Expert, Asia-Pacific Association of Agricultural Research Institutions, Bangkok, Thailand
- Deputy Director General for Strategy, Engagement and Impact, International Rice Research Institute, Los Baños, Philippines
| |
Collapse
|
2
|
Carrijo de Oliveira L, Figueiredo Costa MA, Gonçalves Pedersolli N, Heleno Batista FA, Migliorini Figueira AC, Salgado Ferreira R, Alves Pinto Nagem R, Alves Nahum L, Bleicher L. Reenacting the Birth of a Function: Functional Divergence of HIUases and Transthyretins as Inferred by Evolutionary and Biophysical Studies. J Mol Evol 2021; 89:370-383. [PMID: 33956179 DOI: 10.1007/s00239-021-10010-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 04/19/2021] [Indexed: 10/21/2022]
Abstract
Transthyretin was discovered in the 1940s, named after its ability to bind thyroid hormones and retinol. In the genomic era, transthyretins were found to be part of a larger family with homologs of no obvious function, then called transthyretin-related proteins. Thus, it was proposed that the transthyretin gene could be the result of gene duplication of an ancestral of this newly identified homolog, later found out to be an enzyme involved in uric acid degradation, then named HIUase (5-hydroxy-isourate hydrolase). Here, we sought to re-enact the evolutionary history of this protein family by reconstructing, from a phylogeny inferred from 123 vertebrate sequences, three ancestors corresponding to key moments in their evolution-before duplication; the common transthyretin ancestor after gene duplication and the common ancestor of Eutheria transthyretins. Experimental and computational characterization showed the reconstructed ancestor before duplication was unable to bind thyroxine and likely presented the modern HIUase reaction mechanism, while the substitutions after duplication prevented that activity and were enough to provide stable thyroxine binding, as confirmed by calorimetry and x-ray diffraction. The Eutheria transthyretin ancestor was less prone to characterization, but limited data suggested thyroxine binding as expected. Sequence/structure analysis suggests an early ability to bind the Retinol Binding Protein. We solved the X-ray structures from the two first ancestors, the first at 1.46 resolution, the second at 1.55 resolution with well-defined electron density for thyroxine, providing a useful tool for the understanding of structural adaptation from enzyme to hormone distributor.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Laila Alves Nahum
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Brazil
| | - Lucas Bleicher
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
| |
Collapse
|
3
|
A review of species differences in the control of, and response to, chemical-induced thyroid hormone perturbations leading to thyroid cancer. Arch Toxicol 2021; 95:807-836. [PMID: 33398420 DOI: 10.1007/s00204-020-02961-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 11/26/2020] [Indexed: 12/13/2022]
Abstract
This review summarises the current state of knowledge regarding the physiology and control of production of thyroid hormones, the effects of chemicals in perturbing their synthesis and release that result in thyroid cancer. It does not consider the potential neurodevelopmental consequences of low thyroid hormones. There are a number of known molecular initiating events (MIEs) that affect thyroid hormone synthesis in mammals and many chemicals are able to activate multiple MIEs simultaneously. AOP analysis of chemical-induced thyroid cancer in rodents has defined the key events that predispose to the development of rodent cancer and many of these will operate in humans under appropriate conditions, if they were exposed to high enough concentrations of the affecting chemicals. There are conditions however that, at the very least, would indicate significant quantitative differences in the sensitivity of humans to these effects, with rodents being considerably more sensitive to thyroid effects by virtue of differences in the biology, transport and control of thyroid hormones in these species as opposed to humans where turnover is appreciably lower and where serum transport of T4/T3 is different to that operating in rodents. There is heated debate around claimed qualitative differences between the rodent and human thyroid physiology, and significant reservations, both scientific and regulatory, still exist in terms of the potential neurodevelopmental consequences of low thyroid hormone levels at critical windows of time. In contrast, the situation for the chemical induction of thyroid cancer, through effects on thyroid hormone production and release, is less ambiguous with both theoretical, and actual data, showing clear dose-related thresholds for the key events predisposing to chemically induced thyroid cancer in rodents. In addition, qualitative differences in transport, and quantitative differences in half life, catabolism and turnover of thyroid hormones, exist that would not operate under normal situations in humans.
Collapse
|
4
|
Šošić-Jurjević B, Lütjohann D, Renko K, Filipović B, Radulović N, Ajdžanović V, Trifunović S, Nestorović N, Živanović J, Manojlović Stojanoski M, Kӧhrle J, Milošević V. The isoflavones genistein and daidzein increase hepatic concentration of thyroid hormones and affect cholesterol metabolism in middle-aged male rats. J Steroid Biochem Mol Biol 2019; 190:1-10. [PMID: 30885834 DOI: 10.1016/j.jsbmb.2019.03.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 03/06/2019] [Accepted: 03/13/2019] [Indexed: 01/05/2023]
Abstract
We examined whether isoflavones interfere with thyroid homeostasis, increase hepatic thyroid hormone concentrations and affect cholesterol metabolism in middle-aged (MA) male rats. Thirteen-month-old Wistar rats were injected subcutaneously with 35 mg/kg b.w./day of genistein, daidzein or vehicle (controls) for four weeks. Hepatic Dio1 gene expression was up-regulated by 70% (p < 0.001 for both) and Dio1 enzyme activity increased by 64% after genistein (p < 0.001) and 73% after daidzein treatment (p < 0.0001). Hepatic T3 was 75% higher (p < 0.05 for both), while T4 increased only after genistein treatment. Serum T4 concentrations were 31% lower in genistein- and 49% lower in dadzein-treated rats (p < 0.001 for both) compared with controls. Hepatic Cyp7a1 gene expression was up-regulated by 40% after genistein and 32% after daidzein treatment (p < 0.05 for both), in agreement with a 7α-hydroxycholesterol increase of 50% (p < 0.01) and 88% (p < 0.001), respectively. Serum 24- and 27-hydroxycholesterol were 30% lower (p < 0.05 for both), while only 24-hydroxycholesterol was decreased in the liver by 45% after genistein (p < 0.05) and 39% (p < 0.01) after dadzein treatment. Serum concentration of the cholesterol precursor desmosterol was 32% (p < 0.05) lower only after dadzein treatment alone, while both isoflavones elevated this parameter in the liver by 45% (p < 0.01). In conclusion, isoflavones increased T3 availability in the liver of MA males, despite decreasing serum T4. Hepatic increase of T3 possibly contributes to activation of the neutral pathway of cholesterol degradation into bile acids in the liver. While isoflavones obviously have the potential to trigger multiple mechanisms involved in cholesterol metabolism and oxysterol production, they failed to induce any hypocholesterolemic effect.
Collapse
Affiliation(s)
- B Šošić-Jurjević
- Institute for Biological Research, "Siniša Stanković", University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia.
| | - D Lütjohann
- Institut für Klinische Chemie und Klinische Pharmakologie, Universitätsklinikum Bonn, Sigmund-Freud-Str. 25, D-53127 Bonn, Germany
| | - K Renko
- Institut für Experimentelle Endokrinologie, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany
| | - B Filipović
- Institute for Biological Research, "Siniša Stanković", University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia
| | - N Radulović
- Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš, Serbia
| | - V Ajdžanović
- Institute for Biological Research, "Siniša Stanković", University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia
| | - S Trifunović
- Institut für Klinische Chemie und Klinische Pharmakologie, Universitätsklinikum Bonn, Sigmund-Freud-Str. 25, D-53127 Bonn, Germany
| | - N Nestorović
- Institute for Biological Research, "Siniša Stanković", University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia
| | - J Živanović
- Institute for Biological Research, "Siniša Stanković", University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia
| | - M Manojlović Stojanoski
- Institute for Biological Research, "Siniša Stanković", University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia
| | - J Kӧhrle
- Institut für Experimentelle Endokrinologie, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany
| | - V Milošević
- Institute for Biological Research, "Siniša Stanković", University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia
| |
Collapse
|
5
|
Mehaisen GMK, Ibrahim RM, Desoky AA, Safaa HM, El-Sayed OA, Abass AO. The importance of propolis in alleviating the negative physiological effects of heat stress in quail chicks. PLoS One 2017; 12:e0186907. [PMID: 29053741 PMCID: PMC5650467 DOI: 10.1371/journal.pone.0186907] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 09/22/2017] [Indexed: 01/14/2023] Open
Abstract
Heat stress is one of the most detrimental confrontations in tropical and subtropical regions of the world, causing considerable economic losses in poultry production. Propolis, a resinous product of worker honeybees, possesses several biological activities that could be used to alleviate the deleterious effects of high environmental temperature on poultry production. The current study was aimed at evaluating the effects of propolis supplementation to Japanese quail (Coturnix coturnix japonica) diets on the production performance, intestinal histomorphology, relative physiological and immunological parameters, and selected gene expression under heat stress conditions. Three hundred one-day-old Japanese quail chicks were randomly distributed into 20 wired-cages. At 28 d of age, the birds were divided into 2 temperature treatment groups; a normal at 24°C (C group) and a heat stress at 35°C (HS group). The birds in each group were further assigned to 2 subgroups; one of them was fed on a basal diet without propolis supplementation (-Pr subgroup) while the other was supplemented with propolis (+Pr subgroup). Production performance including body weight gain, feed intake and feed conversion ratio were measured. The intestinal histomorphological measurements were also performed for all treatment groups. Relative physiological parameters including body temperature, corticosterone hormone level, malondialdehyde (MDA) and free triiodothyronine hormone (fT3), as well as the relative immunological parameters including the total white blood cells count (TWBC’s), heterophil/lymphocyte (H/L) ratio and lymphocyte proliferation index, were also measured. Furthermore, the mRNA expression for toll like receptor 5 (TLR5), cysteine-aspartic protease-6 (CASP6) and heat shock proteins 70 and 90 (Hsp70 and Hsp90) genes was quantified in this study. The quail production performance was significantly (P<0.05) impaired by HS treatment, while Pr treatment significantly improved the quail production performance. The villus width and area were significantly (P<0.05) lower in the HS compared to the C group, while Pr treatment significantly increased crypts depth of quail. A negative impact of HS treatment was observed on the physiological status of quail; however, propolis significantly alleviated this negative effect. Moreover, quail of the HS group expressed lower immunological parameters than C group, while propolis enhanced the immune status of the quail. The relative mRNA expression of TLR5 gene was down-regulated by HS treatment while it was up-regulated by the Pr treatment. Furthermore, the positive effects of propolis in HS-quail were evidenced by normalizing the high expressions of CASP6 and Hsp70 genes when compared to the C group. Based on these results, the addition of propolis to quail diets as a potential nutritional strategy in order to improve their performance, especially under heat stress conditions, is recommended.
Collapse
Affiliation(s)
- Gamal M. K. Mehaisen
- Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
- Poultry Cellular and Molecular Physiology Laboratory, Faculty of Agriculture, Cairo University, Giza, Egypt
- * E-mail:
| | - Rania M. Ibrahim
- Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
| | - Adel A. Desoky
- Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
| | - Hosam M. Safaa
- Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
| | - Osama A. El-Sayed
- Poultry Breeding Department, Animal Production Research Institute, Dokki, Giza, Egypt
| | - Ahmed O. Abass
- Department of Animal Production, Faculty of Agriculture, Cairo University, Giza, Egypt
- Poultry Cellular and Molecular Physiology Laboratory, Faculty of Agriculture, Cairo University, Giza, Egypt
| |
Collapse
|
6
|
Šošić-Jurjević B, Filipović B, Wirth EK, Živanović J, Radulović N, Janković S, Milošević V, Köhrle J. Soy isoflavones interfere with thyroid hormone homeostasis in orchidectomized middle-aged rats. Toxicol Appl Pharmacol 2014; 278:124-34. [PMID: 24793811 DOI: 10.1016/j.taap.2014.04.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 04/17/2014] [Accepted: 04/18/2014] [Indexed: 01/10/2023]
Abstract
We previously reported that genistein (G) and daidzein (D) administered subcutaneously (10mg/kg) induce changes in the angio-follicular units of the thyroid gland, reduce concentration of total thyroid hormones (TH) and increase thyrotropin (TSH) in serum of orchidectomized middle-aged (16-month-old) rats. To further investigate these effects, we now examined expression levels of the thyroglobulin (Tg), thyroperoxidase (Tpo), vascular endothelial growth factor A (Vegfa) and deiodinase type 1 (Dio 1) genes in the thyroid; in the pituitary, genes involved in TH feedback control (Tsh β, Dio 1, Dio 2, Trh receptor); and in the liver and kidney, expression of T3-activated genes Dio 1 and Spot 14, as well as transthyretin (Ttr), by quantitative real-time PCR. We also analyzed TPO-immunopositivity and immunofluorescence of T4 bound to Tg, determined thyroid T4 levels and measured deiodinase enzyme activities in examined organs. Decreased expression of Tg and Tpo genes (p<0.05) correlated with immunohistochemical staining results, and together with decreased serum total T4 levels, indicates decreased Tg and TH synthesis following treatments with both isoflavones. However, expression of Spot 14 (p<0.05) gene in liver and kidney was up-regulated, and liver Dio 1 expression and activity (p<0.05) increased. At the level of pituitary, no significant change in gene expression levels, or Dio 1 and 2 enzyme activities was observed. In conclusion, both G and D impaired Tg and TH synthesis, but at the same time increased tissue availability of TH in peripheral tissues of Orx middle-aged rats.
Collapse
Affiliation(s)
- Branka Šošić-Jurjević
- Institute for Biological Research, Siniša Stanković, University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia.
| | - Branko Filipović
- Institute for Biological Research, Siniša Stanković, University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia
| | - Eva Katrin Wirth
- Institut für Experimentelle Endokrinologie, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany
| | - Jasmina Živanović
- Institute for Biological Research, Siniša Stanković, University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia
| | - Niko Radulović
- Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš, Serbia
| | - Snežana Janković
- Institute for Science Application in Agriculture, University of Belgrade, Despot Stefan Blvd. 68b, 11000 Belgrade, Serbia
| | - Verica Milošević
- Institute for Biological Research, Siniša Stanković, University of Belgrade, Despot Stefan Blvd. 142, 11000 Belgrade, Serbia
| | - Josef Köhrle
- Institut für Experimentelle Endokrinologie, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany
| |
Collapse
|
7
|
Landers K, Mortimer R, Richard K. Transthyretin and the human placenta. Placenta 2013; 34:513-7. [DOI: 10.1016/j.placenta.2013.04.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 04/18/2013] [Accepted: 04/19/2013] [Indexed: 12/11/2022]
|
8
|
Murk AJ, Rijntjes E, Blaauboer BJ, Clewell R, Crofton KM, Dingemans MML, Furlow JD, Kavlock R, Köhrle J, Opitz R, Traas T, Visser TJ, Xia M, Gutleb AC. Mechanism-based testing strategy using in vitro approaches for identification of thyroid hormone disrupting chemicals. Toxicol In Vitro 2013; 27:1320-46. [PMID: 23453986 DOI: 10.1016/j.tiv.2013.02.012] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Revised: 02/07/2013] [Accepted: 02/18/2013] [Indexed: 11/16/2022]
Abstract
The thyroid hormone (TH) system is involved in several important physiological processes, including regulation of energy metabolism, growth and differentiation, development and maintenance of brain function, thermo-regulation, osmo-regulation, and axis of regulation of other endocrine systems, sexual behaviour and fertility and cardiovascular function. Therefore, concern about TH disruption (THD) has resulted in strategies being developed to identify THD chemicals (THDCs). Information on potential of chemicals causing THD is typically derived from animal studies. For the majority of chemicals, however, this information is either limited or unavailable. It is also unlikely that animal experiments will be performed for all THD relevant chemicals in the near future for ethical, financial and practical reasons. In addition, typical animal experiments often do not provide information on the mechanism of action of THDC, making it harder to extrapolate results across species. Relevant effects may not be identified in animal studies when the effects are delayed, life stage specific, not assessed by the experimental paradigm (e.g., behaviour) or only occur when an organism has to adapt to environmental factors by modulating TH levels. Therefore, in vitro and in silico alternatives to identify THDC and quantify their potency are needed. THDC have many potential mechanisms of action, including altered hormone production, transport, metabolism, receptor activation and disruption of several feed-back mechanisms. In vitro assays are available for many of these endpoints, and the application of modern '-omics' technologies, applicable for in vivo studies can help to reveal relevant and possibly new endpoints for inclusion in a targeted THDC in vitro test battery. Within the framework of the ASAT initiative (Assuring Safety without Animal Testing), an international group consisting of experts in the areas of thyroid endocrinology, toxicology of endocrine disruption, neurotoxicology, high-throughput screening, computational biology, and regulatory affairs has reviewed the state of science for (1) known mechanisms for THD plus examples of THDC; (2) in vitro THD tests currently available or under development related to these mechanisms; and (3) in silico methods for estimating the blood levels of THDC. Based on this scientific review, the panel has recommended a battery of test methods to be able to classify chemicals as of less or high concern for further hazard and risk assessment for THD. In addition, research gaps and needs are identified to be able to optimize and validate the targeted THD in vitro test battery for a mechanism-based strategy for a decision to opt out or to proceed with further testing for THD.
Collapse
Affiliation(s)
- AlberTinka J Murk
- Wageningen University, Sub-department of Toxicology, Tuinlaan 5, 6703 HE Wageningen, The Netherlands.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Green tea halts progression of cardiac transthyretin amyloidosis: an observational report. Clin Res Cardiol 2012; 101:805-13. [PMID: 22584381 PMCID: PMC3445797 DOI: 10.1007/s00392-012-0463-z] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 04/19/2012] [Indexed: 12/14/2022]
Abstract
Background Treatment options in patients with amyloidotic transthyretin (ATTR) cardiomyopathy are limited. Epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea (GT), inhibits fibril formation from several amyloidogenic proteins in vitro. Thus, it might also halt progression of TTR amyloidosis. This is a single-center observational report on the effects of GT consumption in patients with ATTR cardiomopathy. Methods 19 patients with ATTR cardiomyopathy were evaluated by standard blood tests, echocardiography, and cardiac MRI (n = 9) before and after consumption of GT and/or green tea extracts (GTE) for 12 months. Results Five patients were not followed up for reasons of death (n = 2), discontinuation of GT/GTE consumption (n = 2), and heart transplantation (n = 1). After 12 months no increase of left ventricular (LV) wall thickness and LV myocardial mass was observed by echocardiography. In the subgroup of patients evaluated by cardiac MRI a mean decrease of LV myocardial mass (−12.5 %) was detected in all patients. This was accompanied by an increase of mean mitral annular systolic velocity of 9 % in all 14 patients. Total cholesterol (191.9 ± 8.9 vs. 172.7 ± 9.4 mg/dL; p < 0.01) and LDL cholesterol (105.8 ± 7.6 vs. 89.5 ± 8.0 mg/dL; p < 0.01) decreased significantly during the observational period. No serious adverse effects were reported by any of the participants. Conclusions Our observation suggests an inhibitory effect of GT and/or GTE on the progression of cardiac amyloidosis. We propose a randomized placebo-controlled investigation to confirm our observation. Electronic supplementary material The online version of this article (doi:10.1007/s00392-012-0463-z) contains supplementary material, which is available to authorized users.
Collapse
|
10
|
Blasi D, Pinto M, Nieto J, Arsequell G, Valencia G, Planas A, Centeno NB, Quintana J. Drug discovery targeted at transthyretin cardiac amyloidosis: rational design, synthesis, and biological activity of new transthyretin amyloid inhibitors. Amyloid 2011; 18 Suppl 1:55-7. [PMID: 21838431 DOI: 10.3109/13506129.2011.574354019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- D Blasi
- Drug Discovery Platform, Parc Cientific Barcelona, Barcelona, Spain
| | | | | | | | | | | | | | | |
Collapse
|
11
|
|
12
|
Yamauchi K, Sai G. Characterization of plasma triiodophenol binding proteins in vertebrates and tissue distribution of triiodophenol in Rana catesbeiana tadpoles. Comp Biochem Physiol C Toxicol Pharmacol 2011; 153:328-35. [PMID: 21147258 DOI: 10.1016/j.cbpc.2010.12.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 11/29/2010] [Accepted: 12/06/2010] [Indexed: 12/22/2022]
Abstract
We investigated the interaction of 2,4,6-triiodophenol (TIP), a potent thyroid hormone disrupting chemical, with serum proteins from rainbow trout (Onchorhynchus mykiss), bullfrog (Rana catesbeiana), chicken (Gallus gallus), pig (Sus scrofa domesticus), and rat (Rattus norvegicus) using a [(125)I]TIP binding assay, gel filtration chromatography, and native polyacrylamide gel electrophoresis. [(125)I]TIP bound non-specifically to proteins in trout serum, specifically but weakly to proteins in bullfrog serum, and specifically and strongly to proteins in chicken, pig, and rat serum samples. Candidate TIP-binding proteins included lipoproteins (220-320kDa) in trout, albumin in bullfrog, albumin and transthyretin (TTR) in chicken and pig, and TTR in rat. TTR in the chicken, pig, and rat serum samples was responsible for the high-affinity, low-capacity binding sites for TIP (dissociation constant 2.2-3.5×10(-10)M). In contrast, a weak interaction of [(125)I]TIP with tadpole serum proteins accelerated [(125)I]TIP cellular uptake in vitro. Intraperitoneal injection of [(125)I]TIP in tadpoles revealed that the radioactivity was predominantly accumulated in the gallbladder and the kidney. The differences in the molecular and binding properties of TIP binding proteins among vertebrates would affect in part the cellular availability, tissue distribution and clearance of TIP.
Collapse
Affiliation(s)
- Kiyoshi Yamauchi
- Department of Biological Science, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan.
| | | |
Collapse
|
13
|
Azad RM. Abnormal serum thyroid hormones concentration with healthy functional gland: a review on the metabolic role of thyroid hormones transporter proteins. Pak J Biol Sci 2011; 14:313-26. [PMID: 21874823 DOI: 10.3923/pjbs.2011.313.326] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Laboratory findings can definitely help the patients not to enter into status, where the damage might be happen due to a miss-diagnosis based on clinical assessment alone. The secondary disease accompanied with thyroid patients should also carefully check out due to the interference which some diseases can cause in the amount of serum thyroid hormone, particularly the free thyroxin. The dilemma over thyroid clinical diagnosis occur due to variation on serum thyroid hormone which initiated by other non-thyroidal disorders which can play an important roles in metabolic disorders of thyroid hormone due to the alteration which occur on the serum level of thyroid hormone transporter proteins. The majority of serum thyroid hormones of up to 95-99% are bound to the carrier proteins mainly to Thyroxin-Binding Globulins (TBG), some transthyretin already known as pre-albumin and albumin which are all synthesis in the liver and any modification which alter their production may alter the status of thyroid hormones. It seems TBG, transthyretin and albumin carries 75, 20, 5% of thyroid hormones within blood circulation, respectively. The dilemma facing the thyroid hormones following disruption of thyroid hormone transporter protein synthesis originate from this fact that any alteration of these protein contribute to the alteration of total thyroid and free serum thyroid hormones which are in fact the biologically active form of thyroid hormones. The subsequent of latter implication result in miss-understanding and miss-diagnosis of thyroid function tests, with possible wrongly thyroid clinical care, followed by undesired therapy of otherwise healthy thyroid.
Collapse
Affiliation(s)
- Reza Mansourian Azad
- Biochemistry and Metabolic Disorder Research Center, Gorgan Medical School, Golestan University of Medical Sciences, Gorgan, Iran
| |
Collapse
|
14
|
Connelly S, Choi S, Johnson SM, Kelly JW, Wilson IA. Structure-based design of kinetic stabilizers that ameliorate the transthyretin amyloidoses. Curr Opin Struct Biol 2010; 20:54-62. [PMID: 20133122 DOI: 10.1016/j.sbi.2009.12.009] [Citation(s) in RCA: 143] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Accepted: 12/20/2009] [Indexed: 10/19/2022]
Abstract
Small molecules that bind to normally unoccupied thyroxine (T(4)) binding sites within transthyretin (TTR) in the blood stabilize the tetrameric ground state of TTR relative to the dissociative transition state and dramatically slow tetramer dissociation, the rate-limiting step for the process of amyloid fibril formation linked to neurodegeneration and cell death. These so-called TTR kinetic stabilizers have been designed using structure-based principles and one of these has recently been shown to halt the progression of a human TTR amyloid disease in a clinical trial, providing the first pharmacologic evidence that the process of amyloid fibril formation is causative. Structure-based design has now progressed to the point where highly selective, high affinity TTR kinetic stabilizers that lack undesirable off-target activities can be produced with high frequency.
Collapse
Affiliation(s)
- Stephen Connelly
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | | | | | | | | |
Collapse
|
15
|
Binding of epigallocatechin-3-gallate to transthyretin modulates its amyloidogenicity. FEBS Lett 2009; 583:3569-76. [PMID: 19861125 DOI: 10.1016/j.febslet.2009.10.062] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 10/13/2009] [Accepted: 10/19/2009] [Indexed: 11/21/2022]
Abstract
More than 100 transthyretin (TTR) variants are associated with hereditary amyloidosis. Approaches for TTR amyloidosis that interfere with any step of the cascade of events leading to fibril formation have therapeutic potential. In this study we tested (-)-epigallocatechin-3-gallate (EGCG), the most abundant catechin of green tea, as an inhibitor of TTR amyloid formation. We demonstrate that EGCG binds to TTR "in vitro" and "ex vivo" and that EGCG inhibits TTR aggregation "in vitro" and in a cell culture system. These findings together with the low toxicity of the compound raise the possibility of using EGCG in a therapeutic approach for familial amyloidotic polyneuropathy, the most frequent form of hereditary TTR amyloidosis.
Collapse
|
16
|
|
17
|
Hamann I, Seidlova-Wuttke D, Wuttke W, Köhrle J. Effects of isoflavonoids and other plant-derived compounds on the hypothalamus–pituitary–thyroid hormone axis. Maturitas 2006. [DOI: 10.1016/j.maturitas.2006.06.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
18
|
Maia F, Almeida MDR, Gales L, Kijjoa A, Pinto MMM, Saraiva MJ, Damas AM. The binding of xanthone derivatives to transthyretin. Biochem Pharmacol 2005; 70:1861-9. [PMID: 16236271 DOI: 10.1016/j.bcp.2005.09.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 09/09/2005] [Accepted: 09/12/2005] [Indexed: 11/23/2022]
Abstract
A series of xanthone derivatives, isolated from Calophyllum teysmannii var. inophylloide, have been evaluated for their binding affinity to transthyretin. Transthyretin is a plasma protein involved in the transport of thyroxine (T4) and also implicated in amyloid diseases. Using competition-binding studies with the protein natural ligand T4, we have identified one prenylated xanthone with a very strong affinity to transthyretin. Molecular docking simulations show that the flexible tail of the prenylated xanthone could allow favorable molecular interactions. Since this xanthone may play a role in the thyroxine metabolism and/or over the pathogenic process associated with the amyloid disease, these results may be explored for the design of new ligands.
Collapse
Affiliation(s)
- Filipe Maia
- Unidade de Estrutura Molecular, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
| | | | | | | | | | | | | |
Collapse
|
19
|
Abstract
Abstract Soy isoflavonoids are plant phytoestrogens available as dietary supplements and are increasingly advocated as a natural alternative to oestrogen replacement therapy. As weak oestrogen agonists/antagonists with a range of other enzymatic activities, the isoflavonoids provide a useful model to investigate the actions of endocrine disruptors. Here, the activational and organisational effects of these compounds on the brain are reviewed. In spite of their preferential affinity for oestrogen receptor (ER)beta in vitro, isoflavonoids act in vivo through both ERalpha and ERbeta. Their neurobehavioural actions are largely anti-oestrogenic, either antagonising or producing an action in opposition to that of oestradiol. Small, physiologically relevant exposure levels can alter oestrogen-dependent gene expression in the brain and affect complex behaviour in a wide range of species. The implications for these findings in humans, and particularly in infants, largely remain uninvestigated but are a subject of increasing public interest.
Collapse
Affiliation(s)
- H B Patisaul
- CIIT Centers for Health Research, Six Davis Drive, Research Traingle Park, NC 27709, USA.
| |
Collapse
|
20
|
Ishihara A, Sawatsubashi S, Yamauchi K. Endocrine disrupting chemicals: interference of thyroid hormone binding to transthyretins and to thyroid hormone receptors. Mol Cell Endocrinol 2003; 199:105-17. [PMID: 12581883 DOI: 10.1016/s0303-7207(02)00302-7] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We examined the effects of industrial, medical and agricultural chemicals on 3,5,3'-L-[125I]triiodothyronine ([125I]T(3)) binding to transthyretins (TTRs) and thyroid hormone receptors (TRs). Among the chemicals investigated diethylstilbestrol (DES) was the most powerful inhibitor of [125I]T(3) binding to chicken and bullfrog TTR (cTTR and bTTR). Inhibition of [125I]T(3) binding was more apparent in cTTR than bTTR. Scatchard analysis revealed DES, pentachlorophenol and ioxynil as competitive inhibitors of [125I]T(3) binding to cTTR and bTTR. However, cTTR's affinity for the three chemicals was higher than its affinity for T(3). A miticide dicofol (10(-10)-10(-7) M) activated [125I]T(3) binding to bTTR up to 170%. However, at 4x10(-5) M it inhibited [125I]T(3) binding by 83%. Dicofol's biphasic effect upon [125I]T(3) binding was not detected in TTRs from other species. DES and pentachlorophenol, in the presence of plasma, increased cellular uptake of [125I]T(3) in vitro, by displacing [125I]T(3) from its plasma binding sites. These chemicals did not, however, affect the association of cTTR with chicken retinol-binding protein. All chemicals investigated had little or no influence on [125I]T(3) binding to chicken TR (cTR) and bullfrog TR (bTR). Several endocrine disrupting chemicals that were tested interfered with T(3) binding to TTR rather than to TR. Binding of the endocrine disrupting chemicals to TTR may weaken their intrinsic effects on target cells by depressing their free concentrations in plasma. However, this may affect TH homeostasis in vivo by altering the free concentrations of plasma THs.
Collapse
Affiliation(s)
- Akinori Ishihara
- Department of Biology and Geoscience, Faculty of Science, Shizuoka University, 836 Oya, Japan
| | | | | |
Collapse
|
21
|
Abstract
UNLABELLED The most potent natural plant-derived compounds that can affect thyroid function, thyroid hormone secretion and availability to tissues is the group of flavonoids, i.e. plant pigments. They are present in our daily food, such as vegetables, fruits, grains, nuts, wine, and tea. Epidemiological studies suggest beneficial effects on health of flavonoids, which are commonly attributed to their activity as antioxidants. Experimental studies in vitro, however, showed inhibition of organification in thyroid cells and follicles by several flavonoids. Studies in vivo and vitro with synthetic and natural flavonoids showed displacement of T4 from transthyretin leading to disturbances in thyroid hormone availability in tissues. Radioactive labeled flavonoids appeared to be eliminated rapidly from the body mainly through excretion in the feces. In pregnant rats synthetic flavonoids cross the placenta and accumulate in the fetal compartment, including the fetal brain. Therefore, a high intake of flavonoids is contraindicated. IN CONCLUSION flavonoids show strong interference with many aspects of thyroid hormone synthesis and availability.
Collapse
Affiliation(s)
- Daan van der Heide
- Human and Animal Physiology Group, Wageningen University, Wageningen, The Netherlands.
| | | | | |
Collapse
|
22
|
Persky VW, Turyk ME, Wang L, Freels S, Chatterton R, Barnes S, Erdman J, Sepkovic DW, Bradlow HL, Potter S. Effect of soy protein on endogenous hormones in postmenopausal women. Am J Clin Nutr 2002; 75:145-53. [PMID: 11756072 DOI: 10.1093/ajcn/75.1.145] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The long-term clinical effects of soy protein containing various concentrations of isoflavones on endogenous hormones are unknown. OBJECTIVE We examined the effects of ingestion of soy protein containing various concentrations of isoflavones on hormone values in postmenopausal women. DESIGN Seventy-three hypercholesterolemic, free-living, postmenopausal women participated in a 6-mo double-blind trial in which 40 g protein as part of a National Cholesterol Education Program Step I diet was provided as casein from nonfat dry milk (control), isolated soy protein (ISP) containing 56 mg isoflavones (ISP56), or ISP containing 90 mg isoflavones (ISP90). Endogenous hormone concentrations were measured at baseline and at 3 and 6 mo. RESULTS The concentration of thyroxine and the free thyroxine index were higher in the ISP56 group, and the concentration of thyroid-stimulating hormone was higher in the ISP90 group than in the control group at 3 and 6 mo (P < 0.05). Triiodothyronine was significantly higher in the ISP90 group only at 6 mo. Thyroxine, free thyroxine index, and thyroid-stimulating hormone at 6 mo were inversely associated with measures of baseline estrogenicity. No significant differences were found for endogenous estrogens, cortisol, dehydroepiandrosterone sulfate, insulin, glucagon, or follicle-stimulating hormone after baseline hormone values were controlled for. CONCLUSIONS This study does not provide evidence that long-term ingestion of soy protein alters steroid hormone values, but it suggests that soy protein may have small effects on thyroid hormone values that are unlikely to be clinically important. The thyroid effects are, however, consistent with previous findings in animals and highlight the need for future research investigating possible mechanisms of action.
Collapse
Affiliation(s)
- Victoria W Persky
- Division of Epidemiology and Biostatistics, the School of Public Health, the University of Illinois at Chicago, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Abstract
The main purpose of free T4 and free T3 assays is to distinguish reliably between thyrotoxicosis, hypothyroidism, and the euthyroid state, an objective that cannot be attained with assays of total T4 and T3 because of hereditary and acquired variations in the concentrations of binding proteins. Effective correction for changes in the serum concentration of TBG can be achieved with numerous types of free hormone estimate, but other changes in binding are not well accommodated. Despite remarkable methodologic ingenuity, no current method reflects the free T4 concentration in undiluted serum under in vivo conditions. Equilibrium dialysis, widely considered the reference method for free T4 measurement, is also subject to error, either preanalytic, owing to generation of NEFA in the sample leading to an overestimate of free T4, or analytic with underestimation of the effect of competitors to increase free T4. Current approaches to free T4 measurement are vulnerable to several method-dependent artifacts: abnormal albumin binding of T4 or of the assay tracer, the inhibition of T4 binding to TBG by medications, and the effects of critical illness, especially in heparin-treated patients, pregnancy, and the abnormalities in sick premature infants. Because of systematic variation between methods (i.e., whether a technique is albumin dependent or prone to incubation or dilution artifacts), it is essential to consider methodologic details in evaluating free T4 estimates in these situations and whenever estimates of free T4 are clinically discordant. False-positive abnormalities are more frequent than false-negative results. When free T4 results are correlated with the serum TSH concentration with attention to the assumptions that define this relationship, the majority of false-positive results can be readily identified. If a free T4 anomaly remains unexplained on repeat sampling, it is appropriate to use an alternative free T4 method that depends on a different assay principle and to correlate the result with an authentic total T4 measurement.
Collapse
Affiliation(s)
- J R Stockigt
- Ewen Downie Metabolic Unit and, Department of Medicine, Monash University, Alfred Hospital, Melbourne, Victoria, Australia.
| |
Collapse
|
24
|
Son HY, Nishikawa A, Ikeda T, Imazawa T, Kimura S, Hirose M. Lack of effect of soy isoflavone on thyroid hyperplasia in rats receiving an iodine-deficient diet. Jpn J Cancer Res 2001; 92:103-8. [PMID: 11223538 PMCID: PMC5926687 DOI: 10.1111/j.1349-7006.2001.tb01071.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We have reported a dramatic synergism between soy intake and iodine deficiency regarding induction of thyroid hyperplasia in rats. Because isoflavones are active constituents of soybeans, in the present study, their possible contribution was examined. Female F344 rats were divided into 8 groups, exposed to diet containing a 0.2% soy isoflavone mixture (SI), 0.2% SI + iodine deficiency (ID), 0.04% SI, 0.04% SI + ID, 20% defatted soybean (DS) alone, 20% DS + ID, ID alone or basal diet alone for 5 weeks. Thyroid weight was not influenced by SI, but was increased by the ID and DS diets with a further significant increment in the DS + ID group (P < 0.01). Compared to the control value, serum T(4) was significantly (P < 0.01) increased by 20% DS alone and decreased in all groups given the ID treatment (P < 0.001). Serum thyroid stimulating hormone (TSH) level was increased by ID, and further enhanced by DS (P < 0.01) but not SI. Histopathologically, diffuse hypertrophy and / or hyperplasia of thyroid follicles were observed in the ID-treated groups, the severity being enhanced by DS but not SI. Proliferating cell nuclear antigen labeling indices (%) were elevated in the ID diet groups and again enhanced by DS, but not SI. These results thus suggest that isoflavones may not be involved in the mechanisms underlying the synergistic goitrogenic effect of soybean with iodine deficiency.
Collapse
Affiliation(s)
- H Y Son
- Division of Pathology, National Institute of Health Sciences, Setagaya-ku, Tokyo 158-8501, Japan.
| | | | | | | | | | | |
Collapse
|
25
|
Yamauchi K, Prapunpoj P, Richardson SJ. Effect of diethylstilbestrol on thyroid hormone binding to amphibian transthyretins. Gen Comp Endocrinol 2000; 119:329-39. [PMID: 11017780 DOI: 10.1006/gcen.2000.7528] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transthyretin (TTR) is responsible for a major part of the binding of thyroid hormone to proteins in the plasma in amphibian tadpoles. To characterize the binding properties of amphibian TTRs, the effects of 17 hydrophobic signaling molecules, including 6 endocrine disruptors, on 3,5,3'-l-[(125)I]triiodothyronine ([(125)I]T(3)) binding to plasma proteins were examined in bullfrog Rana catesbeiana tadpoles. T(3) was the most potent competitive inhibitor among the 11 natural biological ligands studied, with an ID(50) of 8 nM. Diethylstilbestrol (DES) was the most powerful inhibitor among the 6 endocrine disruptors studied, with an ID(50) of 20 nM. Similar inhibitions of [(125)I]T(3) binding by these compounds were obtained when purified recombinant Xenopus and Rana TTRs were analyzed. Scatchard analysis revealed that Xenopus and Rana TTRs each possessed a single class of binding site for T(3), with a K(d) of 262 and 1.9 nM, respectively, at 0 degrees C. DES, at a concentration of 200 nM, induced the uptake of [(125)I]T(3) into Rana red blood cells suspended in Rana plasma from prometamorphic stages XIII-XV, when TTR is present in plasma. DES induced the uptake of [(125)I]T(3) into red blood cells to a lesser extent when they were suspended in Rana plasma from metamorphic climax stage XXIV, in which the level of TTR was lower than in plasma from the prometamorphic tadpoles. These results indicate that amphibian TTRs have the ability to bind DES with similar affinity to T(3), the natural ligand, and raise the possibility that DES binding to TTR might induce the temporary elevation of the free concentration of plasma T(3) followed by acceleration of cellular T(3) uptake.
Collapse
Affiliation(s)
- K Yamauchi
- Department of Biology, Shizuoka University, Shizuoka 422-8529, Japan.
| | | | | |
Collapse
|
26
|
Baures PW, Peterson SA, Kelly JW. Discovering transthyretin amyloid fibril inhibitors by limited screening. Bioorg Med Chem 1998; 6:1389-401. [PMID: 9784876 DOI: 10.1016/s0968-0896(98)00130-8] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Insoluble protein fibrils, resulting from the self-assembly of a conformational intermediate are implicated to be the causative agent in several human amyloid diseases including familial amyloid polyneuropathy (FAP) and senile systemic amyloidosis (SSA). These diseases are associated with transthyretin (TTR) amyloid fibrils, which appear to form in the acidic partial denaturing environment of a lysosome or endosome. Here we identify several structural classes of small molecules that are capable of inhibiting the TTR conformational changes facilitating amyloid fibril formation. A small molecule inhibitor that stabilizes the normal conformation of a protein is desirable as a promising approach to treat amyloid diseases and to rigorously test the amyloid hypothesis, the apparent causative role of amyloid fibrils in amyloid disease.
Collapse
Affiliation(s)
- P W Baures
- Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037, USA
| | | | | |
Collapse
|
27
|
Schröder-van der Elst JP, van der Heide D, Rokos H, Morreale de Escobar G, Köhrle J. Synthetic flavonoids cross the placenta in the rat and are found in fetal brain. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:E253-6. [PMID: 9486155 DOI: 10.1152/ajpendo.1998.274.2.e253] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The synthetic flavonoid EMD-49209 is a potent inhibitor of the in vivo and in vitro binding of thyroxine (T4) to transthyretin (TTR). We studied the distribution of 125I-labeled EMD-49209 in maternal tissues, intestinal contents, and fetal tissues in rats that were 20 days pregnant (from 1 to 24 h after intravenous injection). The percent dose of EMD decreased quickly with time. In maternal brain no radioactive flavonoid could be detected. EMD was excreted very rapidly from the intestines. In the fetal compartment the percent dose of EMD increased with time; after 24 h it contained 17% of the EMD. The flavonoid was found in all fetal tissues investigated and also in the fetal brain. Because TTR concentrations are high in the fetal rat, especially in the brain, the transfer of flavonoid to the fetal brain might be linked to TTR expression. The presence of flavonoid in the fetal brain raises the possibility of an essential interference of flavonoids with the availability of T4 in the fetal compartment.
Collapse
|
28
|
Langsteger W. Clinical aspects and diagnosis of thyroid hormone transport protein anomalies. CURRENT TOPICS IN PATHOLOGY. ERGEBNISSE DER PATHOLOGIE 1997; 91:129-61. [PMID: 9018920 DOI: 10.1007/978-3-642-60531-4_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- W Langsteger
- Department of Internal Medicine, Hospital Barmherzige Brüder, Graz, Austria
| |
Collapse
|
29
|
Sartelet H, Serghat S, Lobstein A, Ingenbleek Y, Anton R, Petitfrère E, Aguie-Aguie G, Martiny L, Haye B. Flavonoids extracted from fonio millet (Digitaria exilis) reveal potent antithyroid properties. Nutrition 1996; 12:100-6. [PMID: 8724380 DOI: 10.1016/0899-9007(96)90707-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Digitaria exilis (fonio) is a tiny variety of millet commonly eaten by inhabitants of semiarid regions. A sample of fonio collected right in the middle of a severely iodine-depleted goitrous endemic was submitted to phytochemical investigations in order to assess the potential contributory roles played by vegetable molecules to the goitrogenic processes. The total content of flavonoids amounts to 500 mg/kg of the edible whole cereal grains. Their extraction and identification fail to detect the C-glycosylflavones described in other millet varieties but point out the presence of apigenin (A = 150 mg/kg) and of luteolin (L1 = 350 mg/kg). Ten percent of A and 80% of L1 are present in free form, whereas the remaining 90% of A and 20% of L1 are bound as O-glycosylflavones. Both A and L1 aglycones manifest strong anti-thyroid peroxidase (TPO) activities, resulting in a significant reduction of the hormonogenic capacity of this enzyme. In addition, L1 significantly depresses the cyclic AMP phosphodiesterase, implying a concomitant overproduction of the thyrotropin-dependent nucleotide. These last unreported data are regarded as counteracting to some extent the TPO-mediated goitrogenic properties of L1. Since fonio is devoid of other molecules likely to interfere with the thyroid function, our results are directly and casually attributed to A and L1 found in the customary diet.
Collapse
Affiliation(s)
- H Sartelet
- Laboratory of Biochemistry, Faculty of Sciences, University of Reims, France
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Lim CF, Loidl NM, Kennedy JA, Topliss DJ, Stokigt JR. Effect of loop diuretics and nonsteroidal antiinflammatory drugs on thyrotropin release by rat anterior pituitary cells in vitro. Metabolism 1995; 44:1008-12. [PMID: 7637641 DOI: 10.1016/0026-0495(95)90097-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The close inverse-feedback relationship between serum free thyroxine (T4) and thyrotropin (TSH) is altered in some patients receiving therapeutic doses of drugs such as furosemide, fenclofenac, and diphenylhydantoin. We therefore examined the effect of nonsteroidal antiinflammatory drugs (NSAID), diuretics, and diphenylhydantoin on TSH release in rat anterior pituitary cells in primary culture. TSH content of the culture medium was measured at 22 hours at 37 degrees C either with or without thyrotropin-releasing hormone ([TRH] 10 nmol/L) in medium containing 0.5% bovine serum albumin. The mean basal TSH release by pituitary cells was 6.2 +/- 1.2 ng/mL (n = 10) and was not influenced by unlabeled triiodothyronine ([T3] 100 nmol/L) or any of the drugs tested at < or = 400 mumol/L, except ethyacrynic acid. TRH 10 nmol/L increased mean TSH release by 346% +/- 95% (n = 10). T3 1 and 100 nmol/L inhibited TRH-stimulated TSH release by 24% and 31%, respectively (P < .001), whereas TRH-stimulated TSH release was inhibited by 100 mumol/L meclofenamic acid (29%), fenclofenac (28%), furosemide (24%), and diphenylhydantoin (48%) (P < .001 v TRH alone). Meclofenamic acid and furosemide (100 mumol/L) did not significantly alter the inhibitory effect of T3 1 nmol/L on TRH-stimulated TSH release. These in vitro studies suggest that meclofenamic acid, fenclofenac, furosemide, and diphenylhydantoin could influence TSH release by attenuating the TSH response to TRH. This effect may influence T4-TSH relationships when these agents are used in vivo.
Collapse
Affiliation(s)
- C F Lim
- Ewen Downie Metabolic Unit, Alfred Hospital, Melbourne, Victoria, Australia
| | | | | | | | | |
Collapse
|
31
|
Lim CF, Stockigt JR, Hennemann G. Alterations in hepatocyte uptake and plasma binding of thyroxine in nonthyroidal illness and caloric deprivation. Trends Endocrinol Metab 1995; 6:17-20. [PMID: 18406679 DOI: 10.1016/1043-2760(94)00095-l] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Low plasma T(3) in severe illness is widely thought to be due principally to inhibition of 5'-deiodinase activity, but other factors also contribute to this response. Abnormal plasma constituents, namely, 3-carboxy-4-methyl-5-propyl-2-furan propanoic acid (CMPF) and indoxyl sulfate in uremia, and elevated bilirubin and nonesterified fatty acids (NEFA) can impair T(4) transport into hepatocytes, thereby contributing to the lowering of plasma T(3). Assessment of possible endogenous or exogenous inhibitors of T(4) binding to plasma proteins is prone to dilution-dependent artifacts, which can lead to overestimation or underestimation of competitor potency, depending on experimental details. Because the potency of such competitors is a function of their free concentrations in undiluted serum, inhibitory activity may be enhanced by substances that impair their albumin binding. Oleic acid or CMPF can inhibit the effect of drugs such as furosemide or fenclofenac.
Collapse
Affiliation(s)
- C F Lim
- Ewen Downie Metabolic Unit, and Monash University Department of Medicine, Alfred Hospital, Melbourne, Victoria, Australia, 3181
| | | | | |
Collapse
|
32
|
Lim CF, Stockigt JR, Curtis AJ, Wynne KN, Barlow JW, Topliss DJ. A naturally occurring furan fatty acid enhances drug inhibition of thyroxine binding in serum. Metabolism 1993; 42:1468-74. [PMID: 8231843 DOI: 10.1016/0026-0495(93)90200-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We studied the thyroxine (T4)-displacing effects of a naturally occurring, highly albumin-bound furanoid acid that accumulates in serum in renal failure to concentrations in excess of 0.2 mmol/L. This substance, 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), has been shown to displace acidic drugs from albumin binding. The effects of CMPF on ligand binding were assessed in the following systems: (1) T4 binding to T4-binding globulin (TBG) and transthyretin (TTR), (2) T4 binding in undiluted serum, (3) T4-displacing potency of fenclofenac, furosemide, diflunisal, and aspirin in undiluted serum, (4) serum binding of [14C]-drug preparations, and (5) serum binding of [14C]-oleic acid. CMPF had a minor direct effect on T4 binding to TBG comparable in relative affinity to that of aspirin, ie, almost 7 orders of magnitude less than T4 itself. CMPF alone at a concentration of 0.3 mmol/L, which produced only a 10% to 14% increase in free T4 augmented the T4-displacing effects of high therapeutic concentrations of the various drugs in undiluted serum as follows: furosemide by 180%, fenclofenac by 160%, diflunisal by 130%, and aspirin by 40%. In the presence of fenclofenac, increments of CMPF from 0.075 to 0.3 mmol/L progressively augmented the T4-displacing effect of this drug, associated with a progressive increase in its calculated free concentration. CMPF also inhibited the binding of [14C]-oleic acid, suggesting that in some situations CMPF could also indirectly influence thyroid hormone binding by increasing the unbound concentration of nonesterified fatty acids (NEFA), as previously described.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- C F Lim
- Ewen Downie Metabolic Unit, Alfred Hospital, Melbourne, Victoria, Australia
| | | | | | | | | | | |
Collapse
|
33
|
Abend SL, Fang SL, Alex S, Braverman LE, Leonard JL. Rapid alteration in circulating free thyroxine modulates pituitary type II 5' deiodinase and basal thyrotropin secretion in the rat. J Clin Invest 1991; 88:898-903. [PMID: 1885776 PMCID: PMC295477 DOI: 10.1172/jci115392] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
TSH secretion is decreased by both T4 and T3. This negative feedback control of TSH secretion has been correlated with an increase in pituitary nuclear T3 content, and it is not clear whether T4 exerts its effect directly on the thyrotroph or after its deiodination to T3. However, levels of the pituitary enzyme catalyzing T4 to T3 conversion, 5'D-II, are decreased in the presence of an increased amount of T4. Thus, it is unclear why the thyrotroph would have a mechanism for modulating the production of T3, if T3 is, in fact, the sole bioactive signal providing negative feedback inhibition. To examine this apparent paradox, we administered EMD 21388, a compound which inhibits the binding of T4 to transthyretin resulting in a rapid increase in circulating free T4 levels, to rats pretreated with radiolabeled T4 and T3. We observed increases in pituitary and liver T4 content of greater than 150%, without increases in the respective tissue T3 contents. The EMD 21388-treated rats also exhibited a 25% decrease in pituitary 5'D-II activity (103.8 +/- 15.8 fmol 125I released.mg protein-1.h-1, vs. control, 137.4 +/- 15.9, mean +/- SE), as did rats treated with sodium salicylate, another compound that inhibits T4-TTR binding (100.8 +/- 7.1). TSH levels significantly decreased 2 h after the administration of EMD 21388. These data demonstrate that despite a T4-mediated decrease in pituitary 5'D-II activity, an increase in T4 independently decreases TSH secretion.
Collapse
Affiliation(s)
- S L Abend
- Department of Medicine, University of Massachusetts Medical School, Worcester 01655
| | | | | | | | | |
Collapse
|
34
|
Schröder-van der Elst JP, van der Heide D, Köhrle J. In vivo effects of flavonoid EMD 21388 on thyroid hormone secretion and metabolism in rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1991; 261:E227-32. [PMID: 1872384 DOI: 10.1152/ajpendo.1991.261.2.e227] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In vitro, the synthetic flavonoid EMD 21388 appears to be a potent inhibitor of thyroxine (T4) 5'-deiodinase and diminishes binding of T4 to transthyretin. In this study, in vivo effects of long-term administration of EMD 21388 on thyroid hormone production and metabolism were investigated. Intact male rats received EMD 21388 (20 mumol.kg body wt-1.rat-1.day-1) for 14 days. [125I]T4 and 3,5,3'-[131I]triiodotyronine (T3) were infused continuously and intravenously in a double-isotope protocol for the last 10 and 7 days, respectively. EMD 21388 decreased plasma thyroid hormone concentrations, but thyrotropin levels in plasma and pituitary did not change. Plasma clearance rates for T4 and T3 increased. Thyroidal T4 secretion was diminished, but T3 secretion was elevated. Extrathyroidal T3 production by 5'-deiodination was lower. T4 concentrations were markedly lower in all tissues investigated. Total tissue T3 was lower in brown adipose tissue, brain, cerebellum, and pituitary, tissues that express the type II 5'-deiodinase isozyme due to decreased local T3 production. Most tissues showed increased tissue/plasma ratios for T4 and T3. These results indicate that this flavonoid diminished T4 and increased T3 secretion by the thyroid, probably in analogy with other natural flavonoids, by interference with one or several steps between iodide uptake, organification, and hormone synthesis.
Collapse
|