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Di Cosmo C, De Marco G, Agretti P, Ferrarini E, Dimida A, Falcetta P, Benvenga S, Vitti P, Tonacchera M. Screening for drugs potentially interfering with MCT8-mediated T 3 transport in vitro identifies dexamethasone and some commonly used drugs as inhibitors of MCT8 activity. J Endocrinol Invest 2022; 45:803-814. [PMID: 34850364 DOI: 10.1007/s40618-021-01711-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/19/2021] [Indexed: 12/19/2022]
Abstract
BACKGROUND Monocarboxylate transporter 8 (MCT8) is the first thyroid hormone transporter that has been linked to a human disease. Besides genetic alterations other factors might impair MCT8 activity. AIM This study aimed at investigating whether some common drugs having a structural similarity with TH and/or whose treatment is associated with thyroid function test abnormalities, or which behave as antagonists of TH action can inhibit MCT8-mediated T3 transport. METHODS [125I]T3 uptake and efflux were measured in COS-7 cells transiently transfected with hMCT8 before and after exposure to increasing concentrations of hydrocortisone, dexamethasone, prednisone, prednisolone, amiodarone, desethylamiodarone, dronedarone, buspirone, carbamazepine, valproic acid, and L-carnitine. The mode of inhibition was also determined. RESULTS Dexamethasone significantly inhibited T3 uptake at 10 μM; hydrocortisone reduced T3 uptake only at high concentrations, i.e. at 500 and 1000 μM; prednisone and prednisolone were devoid of inhibitory potential. Amiodarone caused a reduction of T3 uptake by MCT8 only at the highest concentrations used (44% at 50 μM and 68% at 100 μM), and this effect was weaker than that produced by desethylamiodarone and dronedarone; buspirone resulted a potent inhibitor, reducing T3 uptake at 0.1-10 μM. L-Carnitine inhibited T3 uptake only at 500 mM and 1 M. Kinetic experiments revealed a noncompetitive mode of inhibition for all compounds. All drugs inhibiting T3 uptake did not affect T3 release. CONCLUSION This study shows a novel effect of some common drugs, which is inhibition of T3 transport mediated by MCT8. Specifically, dexamethasone, buspirone, desethylamiodarone, and dronedarone behave as potent inhibitors of MCT8.
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Affiliation(s)
- C Di Cosmo
- Department of Clinical and Experimental Medicine, Endocrinology Unit, University of Pisa, via Paradisa 2, 56124, Pisa, Italy.
| | - G De Marco
- Department of Clinical and Experimental Medicine, Endocrinology Unit, University of Pisa, via Paradisa 2, 56124, Pisa, Italy
| | - P Agretti
- Laboratory of Chemistry and Endocrinology, University Hospital of Pisa, Pisa, Italy
| | - E Ferrarini
- Department of Clinical and Experimental Medicine, Endocrinology Unit, University of Pisa, via Paradisa 2, 56124, Pisa, Italy
| | - A Dimida
- Department of Clinical and Experimental Medicine, Endocrinology Unit, University of Pisa, via Paradisa 2, 56124, Pisa, Italy
| | - P Falcetta
- Department of Clinical and Experimental Medicine, Endocrinology Unit, University of Pisa, via Paradisa 2, 56124, Pisa, Italy
| | - S Benvenga
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - P Vitti
- Department of Clinical and Experimental Medicine, Endocrinology Unit, University of Pisa, via Paradisa 2, 56124, Pisa, Italy
| | - M Tonacchera
- Department of Clinical and Experimental Medicine, Endocrinology Unit, University of Pisa, via Paradisa 2, 56124, Pisa, Italy
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Lisco G, Giagulli VA, Iovino M, Zupo R, Guastamacchia E, De Pergola G, Iacoviello M, Triggiani V. Endocrine system dysfunction and chronic heart failure: a clinical perspective. Endocrine 2022; 75:360-376. [PMID: 34713389 PMCID: PMC8553109 DOI: 10.1007/s12020-021-02912-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 10/13/2021] [Indexed: 11/01/2022]
Abstract
Chronic heart failure (CHF) leads to an excess of urgent ambulatory visits, recurrent hospital admissions, morbidity, and mortality regardless of medical and non-medical management of the disease. This excess of risk may be attributable, at least in part, to comorbid conditions influencing the development and progression of CHF. In this perspective, the authors examined and described the most common endocrine disorders observed in patients with CHF, particularly in individuals with reduced ejection fraction, aiming to qualify the risks, quantify the epidemiological burden and discuss about the potential role of endocrine treatment. Thyroid dysfunction is commonly observed in patients with CHF, and sometimes it could be the consequence of certain medications (e.g., amiodarone). Male and female hypogonadism may also coexist in this clinical context, contributing to deteriorating the prognosis of these patients. Furthermore, growth hormone deficiency may affect the development of adult myocardium and predispose to CHF. Limited recommendation suggests to screen endocrine disorders in CHF patients, but it could be interesting to evaluate possible endocrine dysfunction in this setting, especially when a high suspicion coexists. Data referring to long-term safety and effectiveness of endocrine treatments in patients with CHF are limited, and their impact on several "hard" endpoints (such as hospital admission, all-cause, and cardiovascular mortality) are still poorly understood.
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Affiliation(s)
- Giuseppe Lisco
- Interdisciplinary Department of Medicine, Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases, University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Vito Angelo Giagulli
- Interdisciplinary Department of Medicine, Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases, University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Michele Iovino
- Interdisciplinary Department of Medicine, Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases, University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Roberta Zupo
- National Institute of Gastroenterology, Saverio de Bellis, Research Hospital, Castellana Grotte, Bari, Italy
| | - Edoardo Guastamacchia
- Interdisciplinary Department of Medicine, Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases, University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Giovanni De Pergola
- National Institute of Gastroenterology, Saverio de Bellis, Research Hospital, Castellana Grotte, Bari, Italy
- Clinical Nutrition Unit, Medical Oncology, Department of Internal Medicine and Clinical Oncology, University of Bari, School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Massimo Iacoviello
- Department of Medical and Surgical Sciences, Cardiology Department, University of Foggia, Foggia, Italy
| | - Vincenzo Triggiani
- Interdisciplinary Department of Medicine, Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases, University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy.
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Therapeutic monitoring of amiodarone and desethylamiodarone after surgical ablation of atrial fibrillation-evaluation of the relationship between clinical effect and the serum concentration. Saudi Pharm J 2021; 29:369-376. [PMID: 34135663 PMCID: PMC8180463 DOI: 10.1016/j.jsps.2021.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 03/06/2021] [Indexed: 11/30/2022] Open
Abstract
Background Association between clinical effect and serum concentration of amiodarone (AMI) and its active metabolite desethylamidarone (DEA) in patients after surgical ablation (SA) of atrial fibrillation (AF) has not yet been studied. Aims We wanted to find a correlation between AMI and DEA serum concentration and maintaining sinus rhythm (SR) after SA of AF. Methods Sixty eight patients with AF who had undergone surgical ablation between 2014 and 2017 were included in a single-centre, prospective, observational study. Maintaining of SR was evaluated by standard 12-lead ECG and 24-hour Holter ECG monitoring at months 1, 3, 6 and 12 following surgery. Therapeutic monitoring of AMI and DEA concentrations was done to optimize therapy and adverse effects were followed up. Results We have noticed a high success rate in maintaining of SR (overall 83%). The median of serum concentration of AMI was 0.81 mg/L (range 0.16–2.35 mg/L) and DEA 0.70 mg/l (range 0.19–2.63 mg/L). No significant differences were found in the serum concentratration of AMI, DEA or DEA/AMI concentratration ratios between patients with SR and persistent supraventricular tachyarrhythmia except on the second outpatient visit. We observed significant correlation between serum concentration of DEA and thyroid-stimulating hormone elevation. Conclusion We confirmed the efficacy of AMI and DEA at the measured serum concentrations. However, analysis of these concentrations alone cannot replace assessment of the clinical response for treatment. Establishment of individual AMI (and DEA) concentrations at which the optimal therapeutic response is achieved seems to be advantageous. Therapeutic monitoring of AMI and DEA is helpful in personalised pharmacotherapy after SA of AF.
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Key Words
- AF, atrial fibrillation
- ALT, alanine transaminase
- AMI, amiodarone
- AST, aspartate transaminase
- Amiodarone
- Atrial fibrillation
- CABG, coronary artery bypass graft
- DEA, desethylamiodarone
- Desethylamiodarone
- ECG, electrocardiogram
- GMT, gama glutamyl transferase
- Maze procedure
- SA, surgical ablation
- SR, sinus rhythm
- ST, supraventricular tachyarrhythmia
- Serum concentration
- Sinus rhythm
- TDM, therapeutic drug monitoring
- TSH, thyroid-stimulating hormone
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Bianco AC, Dumitrescu A, Gereben B, Ribeiro MO, Fonseca TL, Fernandes GW, Bocco BMLC. Paradigms of Dynamic Control of Thyroid Hormone Signaling. Endocr Rev 2019; 40:1000-1047. [PMID: 31033998 PMCID: PMC6596318 DOI: 10.1210/er.2018-00275] [Citation(s) in RCA: 140] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/15/2019] [Indexed: 12/17/2022]
Abstract
Thyroid hormone (TH) molecules enter cells via membrane transporters and, depending on the cell type, can be activated (i.e., T4 to T3 conversion) or inactivated (i.e., T3 to 3,3'-diiodo-l-thyronine or T4 to reverse T3 conversion). These reactions are catalyzed by the deiodinases. The biologically active hormone, T3, eventually binds to intracellular TH receptors (TRs), TRα and TRβ, and initiate TH signaling, that is, regulation of target genes and other metabolic pathways. At least three families of transmembrane transporters, MCT, OATP, and LAT, facilitate the entry of TH into cells, which follow the gradient of free hormone between the extracellular fluid and the cytoplasm. Inactivation or marked downregulation of TH transporters can dampen TH signaling. At the same time, dynamic modifications in the expression or activity of TRs and transcriptional coregulators can affect positively or negatively the intensity of TH signaling. However, the deiodinases are the element that provides greatest amplitude in dynamic control of TH signaling. Cells that express the activating deiodinase DIO2 can rapidly enhance TH signaling due to intracellular buildup of T3. In contrast, TH signaling is dampened in cells that express the inactivating deiodinase DIO3. This explains how THs can regulate pathways in development, metabolism, and growth, despite rather stable levels in the circulation. As a consequence, TH signaling is unique for each cell (tissue or organ), depending on circulating TH levels and on the exclusive blend of transporters, deiodinases, and TRs present in each cell. In this review we explore the key mechanisms underlying customization of TH signaling during development, in health and in disease states.
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Affiliation(s)
- Antonio C Bianco
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
| | - Alexandra Dumitrescu
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
| | - Balázs Gereben
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Miriam O Ribeiro
- Developmental Disorders Program, Center of Biologic Sciences and Health, Mackenzie Presbyterian University, São Paulo, São Paulo, Brazil
| | - Tatiana L Fonseca
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
| | - Gustavo W Fernandes
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
| | - Barbara M L C Bocco
- Section of Endocrinology, Diabetes, and Metabolism, University of Chicago Medical Center, Chicago, Illinois
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5
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Trohman RG, Sharma PS, McAninch EA, Bianco AC. Amiodarone and thyroid physiology, pathophysiology, diagnosis and management. Trends Cardiovasc Med 2018; 29:285-295. [PMID: 30309693 DOI: 10.1016/j.tcm.2018.09.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 08/15/2018] [Accepted: 09/06/2018] [Indexed: 12/14/2022]
Abstract
Although amiodarone is considered the most effective antiarrhythmic agent, its use is limited by a wide variety of potential toxicities. The purpose of this review is to provide a comprehensive "bench to bedside" overview of the ways amiodarone influences thyroid function. We performed a systematic search of MEDLINE to identify peer-reviewed clinical trials, randomized controlled trials, meta-analyses, and other clinically relevant studies. The search was limited to English-language reports published between 1950 and 2017. Amiodarone was searched using the terms adverse effects, hypothyroidism, myxedema, hyperthyroidism, thyroid storm, atrial fibrillation, ventricular arrhythmia, and electrical storm. Google and Google scholar as well as bibliographies of identified articles were reviewed for additional references. We included 163 germane references in this review. Because amiodarone is one of the most frequently prescribed antiarrhythmic drugs in the United States, the mechanistic, diagnostic and therapeutic information provided is relevant for practicing clinicians in a wide range of medical specialties.
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Affiliation(s)
- Richard G Trohman
- Divisions of Cardiology and Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States.
| | - Parikshit S Sharma
- Divisions of Cardiology and Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
| | - Elizabeth A McAninch
- Divisions of Cardiology and Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
| | - Antonio C Bianco
- Divisions of Cardiology and Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
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Dysthyroidism and Chronic Heart Failure: Pathophysiological Mechanisms and Therapeutic Approaches. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1067:239-253. [PMID: 29235066 DOI: 10.1007/5584_2017_132] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Among comorbidity in chronic heart failure (CHF), dysthyroidism represents a relevant problem especially in the ageing CHF patients worldwide. Thyroid greatly affects many cardiovascular activities and its dysfunction may worsen a CHF condition. In particular, hypothyroidism has a relative high prevalence in patients with heart failure and it plays a key role in influencing CHF onset, progression and prognosis. Hyperthyroidism, is less frequent in this clinical context but it necessitates of immediate treatment because of its negative effects on cardiovascular balance. Also, it must be considered that dysthyroism may also be iatrogenic and the main responsible drug is Amiodarone.Based on the best available evidence and our cumulative clinical experience, this manuscript analyzes the prevalence, the pathophysiology and the prognostic impact of thyroid disorders in chronic heart failure.
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Bogazzi F, Tomisti L, Bartalena L, Aghini-Lombardi F, Martino E. Amiodarone and the thyroid: a 2012 update. J Endocrinol Invest 2012; 35:340-8. [PMID: 22433945 DOI: 10.3275/8298] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Amiodarone-induced thyroid dysfunction occurs in 15-20% of amiodarone-treated patients. Amiodarone-induced hypothyroidism (AIH) does not pose relevant problems, is easily controlled by L-thyroxine replacement, and does not require amiodarone withdrawal. Most frequently AIH develops in patients with chronic autoimmune thyroiditis. Amiodarone- induced thyrotoxicosis (AIT) is most frequently due to destructive thyroiditis (type 2 AIT) causing discharge of thyroid hormones from the damaged, but otherwise substantially normal gland. Less frequently AIT is a form of hyperthyroidism (type 1 AIT) caused by the iodine load in a diseased gland (nodular goiter, Graves' disease). A clearcut differentiation between the two main forms is not always possible, despite recent diagnostic advances. As a matter of fact, mixed or indefinite forms do exist, contributed to by both thyroid damage and increased thyroid hormone synthesis. Treatment of type 1 (and mixed forms) AIT is based on the use of thionamides, a short course of potassium perchlorate and, if treatment is not rapidly effective, oral glucocorticoids. Glucocorticoids are the first-line treatment for type 2 AIT. Amiodarone should be discontinued, if feasible from a cardiac standpoint. Continuation of amiodarone has recently been associated with a delayed restoration of euthyroidism and a higher chance of recurrence after glucocorticoid withdrawal. Whether amiodarone treatment can be safely reinstituted after restoration of euthyroidism is still unknown. In rare cases of AIT resistance to standard treatments, or when a rapid restoration of euthyroidism is advisable, total thyroidectomy represents a valid alternative. Radioiodine treatment is usually not feasible due to the low thyroidal iodine uptake.
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Affiliation(s)
- F Bogazzi
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy.
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8
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Rosene ML, Wittmann G, Arrojo e Drigo R, Singru PS, Lechan RM, Bianco AC. Inhibition of the type 2 iodothyronine deiodinase underlies the elevated plasma TSH associated with amiodarone treatment. Endocrinology 2010; 151:5961-70. [PMID: 20926587 PMCID: PMC2999495 DOI: 10.1210/en.2010-0553] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 09/07/2010] [Indexed: 01/10/2023]
Abstract
The widely prescribed cardiac antiarrhythmic drug amiodarone (AMIO) and its main metabolite, desethylamiodarone (DEA), have multiple side effects on thyroid economy, including an elevation in serum TSH levels. To study the AMIO effect on TSH, mice with targeted disruption of the type 2 deiodinase gene (D2KO) were treated with 80 mg/kg AMIO for 4 wk. Only wild-type (WT) mice controls developed the expected approximate twofold rise in plasma TSH, illustrating a critical role for D2 in this mechanism. A disruption in the D2 pathway caused by AMIO could interfere with the transduction of the T4 signal, generating less T3 and softening the TSH feedback mechanism. When added directly to sonicates of HEK-293 cells transiently expressing D2, both AMIO and DEA behaved as noncompetitive inhibitors of D2 [IC(50) of >100 μm and ∼5 μm, respectively]. Accordingly, D2 activity was significantly decreased in the median eminence and anterior pituitary sonicates of AMIO-treated mice. However, the underlying effect on TSH is likely to be at the pituitary gland given that in AMIO-treated mice the paraventricular TRH mRNA levels (which are negatively regulated by D2-generated T3) were decreased. In contrast, AMIO and DEA both exhibited dose-dependent inhibition of D2 activity and elevation of TSH secretion in intact TαT1 cells, a pituitary thyrotroph cell line used to model the TSH feedback mechanism. In conclusion, AMIO and DEA are noncompetitive inhibitors of D2, with DEA being much more potent, and this inhibition at the level of the pituitary gland contributes to the rise in TSH seen in patients taking AMIO.
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Affiliation(s)
- Matthew L Rosene
- Division of Endocrinology, Diabetes, and Metabolism, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
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9
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Belakavadi M, Saunders J, Weisleder N, Raghava PS, Fondell JD. Repression of cardiac phospholamban gene expression is mediated by thyroid hormone receptor-{alpha}1 and involves targeted covalent histone modifications. Endocrinology 2010; 151:2946-56. [PMID: 20392835 PMCID: PMC2875831 DOI: 10.1210/en.2009-1241] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phospholamban (PLB) is a critical regulator of Ca(2+) cycling in heart muscle cells, and its gene expression is markedly down-regulated by T(3). Nonetheless, little is known about the molecular mechanisms of T(3)-dependent gene silencing in cardiac muscle, and it remains unclear whether thyroid hormone receptors (TRs) directly bind at the PLB gene in vivo and facilitate transcriptional repression. To investigate the regulatory role of TRs in PLB transcription, we used a physiological murine heart muscle cell line (HL-1) that retains cardiac electrophysiological properties, expresses both TRalpha1 and TRbeta1 subtypes, and exhibits T(3)-dependent silencing of PLB expression. By performing RNA interference assays with HL-1 cells, we found that TRalpha1, but not TRbeta1, is essential for T(3)-dependent PLB gene repression. Interestingly, a PLB reporter gene containing only the core promoter sequences -156 to +64 displayed robust T(3)-dependent silencing in HL-1 cells, thus suggesting that transcriptional repression is facilitated by TRalpha1 via the PLB core promoter, a regulatory region highly conserved in mammals. Consistent with this notion, chromatin immunoprecipitation and in vitro binding assays show that TRalpha1 directly binds at the PLB core promoter region. Furthermore, addition of T(3) triggered alterations in covalent histone modifications at the PLB promoter that are associated with gene silencing, namely a pronounced decrease in both histone H3 acetylation and histone H3 lysine 4 methylation. Taken together, our data reveal that T(3)-dependent repression of PLB in cardiac myocytes is directly facilitated by TRalpha1 and involves the hormone-dependent recruitment of histone-modifying enzymes associated with transcriptional silencing.
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Affiliation(s)
- Madesh Belakavadi
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854, USA
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Abstract
Amiodarone is a benzofuran derivative approved for the treatment of cardiac arrhythmias. Traditionally classified as a class III antiarrhythmic agent, amiodarone possesses electrophysiologic properties of all four Vaughan-Williams classes. This drug, however, has high iodine content, and this feature plus the intrinsic effects on the body make amiodarone especially toxic to the thyroid gland. Treatment can result in a range of effects from mild derangements in thyroid function to overt hypothyroidism or thyrotoxicosis. The diagnosis and treatment of amiodarone-induced hypothyroidism is usually straightforward, whereas that of amiodarone-induced thyrotoxicosis and the ability to distinguish between the type 1 and type 2 forms of the disease are much more challenging. Dronedarone was approved in 2009 for the treatment of patients with atrial fibrillation. As amiodarone, dronedarone is a benzofuran derivative with similar electrophysiologic properties. In contrast to amiodarone, however, dronedarone is structurally devoid of iodine and has a notably shorter half-life. In studies reported before FDA approval, dronedarone proved to be associated with significantly fewer adverse effects than amiodarone, making it a more attractive choice for patients with atrial fibrillation or flutter, who are at risk of developing amiodarone-induced thyroid dysfunction.
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Affiliation(s)
- Janna Cohen-Lehman
- Department of Medicine, North Shore University Hospital, 350 Community Drive, Manhasset, NY 11030, USA
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11
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Abstract
Assessment of TSH and TPO-Ab before starting amiodarone (AM) treatment is recommended. The usefulness of periodic TSH measurement every 6 months during AM treatment is limited by the often sudden explosive onset of AIT, and the spontaneous return of a suppressed TSH to normal values in half of the cases. AM-induced hypothyroidism develops rather early after starting treatment, preferentially in iodine-sufficient areas and in females with TPO-Ab; it is due to failure to escape from the Wolff-Chaikoff effect, resulting in preserved radioiodine uptake. AM-induced thyrotoxicosis (AIT) occurs at any time during treatment, preferentially in iodine-deficient regions and in males. AIT can be classified in type 1 (iodide-induced thyrotoxicosis, best treated by potassium perchlorate in combination with thionamides and discontinuation of AM) and type 2 (destructive thyrotoxicosis, best treated by prednisone; discontinuation of AM may not be necessary). AIT is associated with a higher rate of major adverse cardiovascular events (especially of ventricular arrhythmias). Uncertainty continues to exist with respect to the feasibility of continuation of AM despite AIT, the appropriate methods to distinguish between AIT type 1 and 2 as well as the advantages of AIT classification into subtypes in view of possible mixed cases, and the best policy when AM needs to be restarted.
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Affiliation(s)
- Silvia A Eskes
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, The Netherlands
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12
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Abstract
Amiodarone and dronedarone are two clinically important benzofuran derivatives. Amiodarone has been used widely for treating resistant tachyarrhythmias in the past three decades. However amiodarone and its main metabolically active metabolite desethylamiodarone can adversely affect many organs, including the thyroid gland. Amiodarone-induced thyroid disorders are common and often present as a management challenge for endocrinologists. The pathogenesis of amiodarone-induced thyroid dysfunction is complex but the inherent effects of the drug itself as well as its high iodine content appear to play a central role. The non-iodinated dronedarone also exhibits anti-arrhythmic properties but appears to be less toxic to the thyroid. This review describes the biochemistry of benzofuran derivatives, including their pharmacology and the physiology necessary for understanding the cellular mechanisms involved in their actions. The known effects of these compounds on thyroid action are described. Recommendations for management of amiodarone-induced hypothyroidism and thyrotoxicosis are suggested. Dronedarone appears to be an alternative but less-effective anti-arrhythmic agent and it does not have adverse effects on thyroid function. It may have a future role as an alternative agent in patients being considered for amiodarone therapy especially those at high risk of developing thyroid dysfunction but not in severe heart failure.
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Affiliation(s)
- T S Han
- Department of Endocrinology, Royal Free and University College Medical School, Royal Free Hospital, Hampstead, London NW3 2QG, UK
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Wiersinga WM. The role of thyroid hormone nuclear receptors in the heart: evidence from pharmacological approaches. Heart Fail Rev 2008; 15:121-4. [PMID: 19096930 PMCID: PMC2820686 DOI: 10.1007/s10741-008-9131-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2008] [Accepted: 12/02/2008] [Indexed: 11/24/2022]
Abstract
This review evaluates the hypothesis that the cardiac effects of amiodarone can be explained—at least partly—by the induction of a local ‘hypothyroid-like condition’ in the heart. Evidence supporting the hypothesis comprises the observation that amiodarone exerts an inhibitory effect on the binding of T3 to thyroid hormone receptors (TR) alpha-1 and beta-1 in vitro, and on the expression of particular T3-dependent genes in vivo. In the heart, amiodarone decreases heart rate and alpha myosin heavy chain expression (mediated via TR alpha-1), and increases sarcoplasmic reticulum calcium-activated ATPase and beta myosin heavy chain expression (mediated via TR beta-1). Recent data show a significant similarity in expression profiles of 8,435 genes in the heart of hypothyroid and amiodarone-treated animals, although similarities do not always exist in transcripts of ion channel genes. Induction of a hypothyroid cardiac phenotype by amiodarone may be advantageous by decreasing energy demands and increasing energy availability.
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Affiliation(s)
- Wilmar M Wiersinga
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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14
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Abstract
Among the drugs affecting the thyroid gland, no drug has puzzled, and at the same time fascinated, endocrinologists more than amiodarone. Amiodarone is a potent class III anti-arrhythmic drug that also possesses beta-blocking properties. It is very rich in iodine, with a 100-mg tablet containing an amount of iodine that is 250 times the recommended daily iodine requirement. Amiodarone produces characteristic alterations in thyroid function tests in euthyroid patients. Understanding these alterations is crucial in avoiding unnecessary investigations and treatment. Amiodarone-induced thyroid dysfunction occurs because of both its iodine content and the direct toxic effects of the compound on thyroid parenchyma. Amiodarone-induced hyperthyroidism is more common in iodine-deficient regions of the world, whereas amiodarone-induced hypothyroidism is usually seen in iodine-sufficient areas. In contrast to amiodarone-induced hypothyroidism, amiodarone-induced thyrotoxicosis is a difficult condition to diagnose and treat. In this review, we discuss the alterations in thyroid function tests seen in euthyroid subjects, the epidemiology and mechanism of amiodarone-induced thyroid dysfunction, treatment options available, and the consequences of amiodarone use in pregnancy and lactation; and finally, we propose a follow-up strategy in patients taking amiodarone.
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Affiliation(s)
- Shehzad Basaria
- Department of Medicine, Division of Endocrinology, Johns Hopkins University School of Medicine, Bayview Medical Center, Baltimore, Maryland, USA
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15
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Gutleb AC, Meerts IATM, Bergsma JH, Schriks M, Murk AJ. T-Screen as a tool to identify thyroid hormone receptor active compounds. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2005; 19:231-8. [PMID: 21783481 DOI: 10.1016/j.etap.2004.06.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Accepted: 06/24/2004] [Indexed: 05/21/2023]
Abstract
The T-Screen represents an in vitro bioassay based on thyroid hormone dependent cell proliferation of a rat pituitary tumour cell line (GH3) in serum-free medium. It can be used to study interference of compounds with thyroid hormone at the cellular level, thus bridging the gap between limitations of assays using either isolated molecules (enzymes, transport proteins) or complex in vivo experiments with all the complex feedback mechanisms present. Compounds are tested both in the absence and presence of thyroid hormone (EC(50) concentration of T(3)) to test for both agonistic and antagonistic potency. Thyroid hormones (3,3'-5-triiodothyronine: T(3) and 3,3',5,5'-tetraiodothyroxine: T(4)) and compounds resembling the structure of thyroid hormones (3,3'-5-triiodothyroacetic acid: Triac; 3,3',5,5'-tetraiodothyroacetic acid: Tetrac) induced cell growth, with the rank order Triac > T(3) > Tetrac > T(4) (relative potency = 1.35 > 1 > 0.29 > 0.07), which is identical to published affinities of these compounds for nuclear thyroid hormone receptors. Exposure to 5,5'-diphenylhydantoin (DPH) in the presence of 0.25nM T(3) resulted in up to 60% decreased cell growth at 200μM DPH. No effect of DPH on basal metabolic activity of GH3 cells was observed at this concentration. Fentinchloride (IC(50) = 21nM) decreased cell growth induced by 0.25nM T(3), whereas parallel exposure to these concentrations in the absence of T(3) did not alter basal metabolic activities of GH3 cells. Apolar sediment extracts from the Dommel (34%) and Terneuzen (14%) decreased cell growth in the presence of 0.25nM T(3), whereas the extract from Hoogeveen increased cell growth (26%) and the extract from North Sea Channel had no effect. The T-Screen proved to be a fast and functional assay for assessing thyroid hormone receptor active potencies of pure chemicals or environmental mixtures.
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Affiliation(s)
- Arno C Gutleb
- Toxicology Section, Wageningen University, Tuinlaan 5, NL-6703 HE Wageningen, The Netherlands
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Bogazzi F, Raggi F, Ultimieri F, Russo D, Campomori A, McKinney JD, Pinchera A, Bartalena L, Martino E. Effects of a mixture of polychlorinated biphenyls (Aroclor 1254) on the transcriptional activity of thyroid hormone receptor. J Endocrinol Invest 2003; 26:972-8. [PMID: 14759069 DOI: 10.1007/bf03348194] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Polychlorinated biphenyls (PCBs) are environmental contaminants which may affect thyroid function. PCBs may reduce serum thyroid hormone (TH) concentrations by either displacing T4 from TH transport proteins or increasing its hepatic metabolism. The reduced serum T4 causes neurological and growth defects in animals exposed to PCBs during the perinatal period, which can partially be reverted by T4 administration. In addition to a hypothyroid-like syndrome, a direct action of PCBs on TH-sensitive genes has been postulated. In the present study the effects of Aroclor 1254 (ARO), a mixture of PCBs, on transcription of TH-dependent genes were investigated. A reporter plasmid containing the TH-responsive element (TRE) of malic enzyme (ME) gene was used in transient transfections to assess the responsiveness to ARO. ARO (10 microM) reduced the CAT activity by about 50% and competed with T3 to reduce the induction of transcription. Cotransfection of TH receptor (TR) and a wild type TRE was required to reveal ARO inhibitiry effect, which was abolished by a mock reaction not containing TR or by a mutated TRE. ARO reduced the 125I-T3 binding to TR by 30%, but did not affect the interaction of TR with a 32P-labeled TRE in gel shift assay. ARO is likely to produce a conformational change in in vitro translated TR, leading to its increased proteolysis by trypsin. These results demonstrate that ARO interacts with TR, thereby affecting the transcription of TH-sensitive genes, and provide a molecular basis to further explain the complex effects of PCBs on TH disruption.
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Affiliation(s)
- F Bogazzi
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy.
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Abstract
In zebrafish, like many other teleost species, the development and differentiation of many major organs continue unabated into the yolk-sac larval stage before culminating in a free-swimming larva capable of exogenous feeding. We investigated the role of thyroid hormone (TH) in this important embryonic to larval transitory phase. Thyroid hormone receptor (TR) alpha and beta mRNAs are expressed during the early stages of zebrafish embryonic development. Beginning from the midblastula stage, the level of TR beta mRNAs increases dramatically and is maintained until the end of the transitory phase. Excessive exogenous thyroxine (T4; 30 nM) is toxic and causes severe developmental defects. Cotreatment of embryos with amiodarone, an antagonist of TR, and goitrogen methimazole (MMI) lead to severe retardation in the maturation of the gastrointestinal system, swim bladder, and the lower jaw cartilages and the resorption of the yolk sac. The developmental arrest is lethal, and treated larvae do not survive beyond 7 day postfertilization (dpf), but can be completely rescued by the presence of 10 nM T4. We propose that the embryonic to larval transitory phase in many teleost species is characterized by its dependency on the timely synthesis of TH and the concomitant autoinductive increase in TR beta mRNA levels.
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Affiliation(s)
- Yi-Wen Liu
- Laboratory of Fish Biology, Institute of Molecular Agrobiology, 1 Research Link, National University of Singapore, S117604, Republic of Singapore
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