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Hoermann R, Cheung AS, Milne M, Grossmann M. Hypothalamic-Pituitary-Thyroid Axis Set Point Alterations Are Associated With Body Composition in Androgen-Deprived Men. J Endocr Soc 2017; 1:874-885. [PMID: 29264538 PMCID: PMC5686654 DOI: 10.1210/js.2017-00057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 05/17/2017] [Indexed: 12/17/2022] Open
Abstract
Objective: Androgen deprivation therapy (ADT) given to men with prostate cancer is associated with metabolically adverse changes in body composition leading to insulin resistance, but the underlying mechanisms are not fully understood. We investigated prospectively whether androgen deprivation or its consequences may be associated with alterations in thyroid function in men. Design: We performed a prespecified secondary analysis of a prospective case control study. Methods: We prospectively followed men with nonmetastatic prostate cancer newly commencing ADT (n = 34) and age-matched controls (n = 29) for 12 months. We assessed secondary outcomes on thyrotropin (TSH) and thyroid hormones using a linear mixed model to determine mean adjusted differences (MADs) between groups. Results: After a 12-month follow-up period, TSH increased in cases compared with control subjects [MAD, 0.69 mIU/L; 95% confidence interval (CI), 0.58–0.82; P < 0.001]. This was accompanied by a rise in FT4 (MAD, 2.2 pmol/L; 95% CI, 1.1–3.2; P < 0.001), reduced FT3-FT4 conversion (MAD, −0.07; 95% CI, −0.10 to −0.4; P < 0.001), and stable FT3. TSH change correlated significantly with changes in weight, body mass index, and fat mass in cases but not with waist circumference, lean mass, visceral fat, insulin resistance, testosterone, sex hormone binding globulin, and estradiol. The rise in TSH after 12 months was strongly associated with changes in leptin. Conclusions: A profound rise in TSH in the absence of peripheral hypothyroidism under ADT suggests set point adaptations of the hypothalamic-pituitary-thyroid axis. This appears to be mediated by body composition changes and by the fat-associated hormone leptin rather than by androgen deficiency. Further studies are required to determine the causality and biological implications of these findings.
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Affiliation(s)
- Rudolf Hoermann
- Department of Medicine, The University of Melbourne, Heidelberg 3084, Victoria, Australia
| | - Ada S Cheung
- Department of Medicine, The University of Melbourne, Heidelberg 3084, Victoria, Australia.,Department of Endocrinology, Austin Health, Heidelberg 3084, Victoria, Australia
| | - Michele Milne
- Department of Medicine, The University of Melbourne, Heidelberg 3084, Victoria, Australia
| | - Mathis Grossmann
- Department of Medicine, The University of Melbourne, Heidelberg 3084, Victoria, Australia.,Department of Endocrinology, Austin Health, Heidelberg 3084, Victoria, Australia
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Evolutionarily conserved TRH neuropeptide pathway regulates growth in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2017; 114:E4065-E4074. [PMID: 28461507 DOI: 10.1073/pnas.1617392114] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
In vertebrates thyrotropin-releasing hormone (TRH) is a highly conserved neuropeptide that exerts the hormonal control of thyroid-stimulating hormone (TSH) levels as well as neuromodulatory functions. However, a functional equivalent in protostomian animals remains unknown, although TRH receptors are conserved in proto- and deuterostomians. Here we identify a TRH-like neuropeptide precursor in Caenorhabditis elegans that belongs to a bilaterian family of TRH precursors. Using CRISPR/Cas9 and RNAi reverse genetics, we show that TRH-like neuropeptides, through the activation of their receptor TRHR-1, promote growth in Celegans TRH-like peptides from pharyngeal motor neurons are required for normal body size, and knockdown of their receptor in pharyngeal muscle cells reduces growth. Mutants deficient for TRH signaling have no defects in pharyngeal pumping or isthmus peristalsis rates, but their growth defect depends on the bacterial diet. In addition to the decrease in growth, trh-1 mutants have a reduced number of offspring. Our study suggests that TRH is an evolutionarily ancient neuropeptide, having its origin before the divergence of protostomes and deuterostomes, and may ancestrally have been involved in the control of postembryonic growth and reproduction.
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Loewen SP, Ferguson AV. Adropin acts in the rat paraventricular nucleus to influence neuronal excitability. Am J Physiol Regul Integr Comp Physiol 2017; 312:R511-R519. [PMID: 28100478 DOI: 10.1152/ajpregu.00517.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/13/2017] [Accepted: 01/14/2017] [Indexed: 01/28/2023]
Abstract
Adropin is a peptide hormone with cardiovascular and metabolic roles in the periphery, including effects on glucose and lipid homeostasis. Central administration of adropin has been shown to inhibit water intake in rats; however, the site at which central adropin acts has yet to be elucidated. The hypothalamic paraventricular nucleus (PVN), a critical autonomic control center, plays essential roles in the control of fluid balance, energy homeostasis, and cardiovascular regulation, and is, therefore, a potential target for centrally acting adropin. In the present study, we used whole cell patch-clamp techniques to examine the effects of adropin on the excitability of neurons within the PVN. All three neuronal subpopulations (magnocellular, preautonomic, and neuroendocrine) in the PVN were found to be responsive to bath-application of 10 nM adropin, which elicited responses in 68% of cells tested (n = 57/84). The majority of cells (58%) depolarized (5.2 ± 0.3 mV; n = 49) in response to adropin, whereas the remaining responsive cells (10%) hyperpolarized (-3.4 ± 0.5 mV; n = 8), effects that were shown to be concentration-dependent. Additionally, responses were maintained in the presence of 1 μM TTX in 75% of cells tested (n = 9/12), and voltage-clamp analysis revealed that adropin had no effect on the amplitude or frequency of excitatory or inhibitory postsynaptic currents (EPSCs and IPSCs) in PVN neurons, suggesting the peptide exerts direct, postsynaptic actions on these neurons. Collectively, these findings suggest central adropin may exert its physiological effects through direct actions on neurons in the PVN.
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Affiliation(s)
- Spencer P Loewen
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Alastair V Ferguson
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Chatzitomaris A, Hoermann R, Midgley JE, Hering S, Urban A, Dietrich B, Abood A, Klein HH, Dietrich JW. Thyroid Allostasis-Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming. Front Endocrinol (Lausanne) 2017; 8:163. [PMID: 28775711 PMCID: PMC5517413 DOI: 10.3389/fendo.2017.00163] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 06/27/2017] [Indexed: 12/21/2022] Open
Abstract
The hypothalamus-pituitary-thyroid feedback control is a dynamic, adaptive system. In situations of illness and deprivation of energy representing type 1 allostasis, the stress response operates to alter both its set point and peripheral transfer parameters. In contrast, type 2 allostatic load, typically effective in psychosocial stress, pregnancy, metabolic syndrome, and adaptation to cold, produces a nearly opposite phenotype of predictive plasticity. The non-thyroidal illness syndrome (NTIS) or thyroid allostasis in critical illness, tumors, uremia, and starvation (TACITUS), commonly observed in hospitalized patients, displays a historically well-studied pattern of allostatic thyroid response. This is characterized by decreased total and free thyroid hormone concentrations and varying levels of thyroid-stimulating hormone (TSH) ranging from decreased (in severe cases) to normal or even elevated (mainly in the recovery phase) TSH concentrations. An acute versus chronic stage (wasting syndrome) of TACITUS can be discerned. The two types differ in molecular mechanisms and prognosis. The acute adaptation of thyroid hormone metabolism to critical illness may prove beneficial to the organism, whereas the far more complex molecular alterations associated with chronic illness frequently lead to allostatic overload. The latter is associated with poor outcome, independently of the underlying disease. Adaptive responses of thyroid homeostasis extend to alterations in thyroid hormone concentrations during fetal life, periods of weight gain or loss, thermoregulation, physical exercise, and psychiatric diseases. The various forms of thyroid allostasis pose serious problems in differential diagnosis of thyroid disease. This review article provides an overview of physiological mechanisms as well as major diagnostic and therapeutic implications of thyroid allostasis under a variety of developmental and straining conditions.
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Affiliation(s)
- Apostolos Chatzitomaris
- Medical Department I, Endocrinology and Diabetology, Bergmannsheil University Hospitals, Ruhr University of Bochum, Bochum, Germany
- *Correspondence: Apostolos Chatzitomaris,
| | - Rudolf Hoermann
- Private Consultancy, Research and Development, Yandina, QLD, Australia
| | | | - Steffen Hering
- Department for Internal Medicine, Cardiology, Endocrinology, Diabetes and Medical Intensive Care Medicine, Krankenhaus Bietigheim-Vaihingen, Bietigheim-Bissingen, Germany
| | - Aline Urban
- Department for Anesthesiology, Intensive Care and Palliative Medicine, Eastern Allgäu-Kaufbeuren Hospitals, Kaufbeuren, Germany
| | | | - Assjana Abood
- Medical Department I, Endocrinology and Diabetology, Bergmannsheil University Hospitals, Ruhr University of Bochum, Bochum, Germany
| | - Harald H. Klein
- Medical Department I, Endocrinology and Diabetology, Bergmannsheil University Hospitals, Ruhr University of Bochum, Bochum, Germany
- Ruhr Center for Rare Diseases (CeSER), Ruhr University of Bochum and Witten/Herdecke University, Bochum, Germany
| | - Johannes W. Dietrich
- Medical Department I, Endocrinology and Diabetology, Bergmannsheil University Hospitals, Ruhr University of Bochum, Bochum, Germany
- Ruhr Center for Rare Diseases (CeSER), Ruhr University of Bochum and Witten/Herdecke University, Bochum, Germany
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Sun Q, Liu A, Ma Y, Wang A, Guo X, Teng W, Jiang Y. Effects of forced swimming stress on thyroid function, pituitary thyroid-stimulating hormone and hypothalamus thyrotropin releasing hormone expression in adrenalectomy Wistar rats. Exp Ther Med 2016; 12:3167-3174. [PMID: 27882133 PMCID: PMC5103762 DOI: 10.3892/etm.2016.3790] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 08/23/2016] [Indexed: 12/27/2022] Open
Abstract
In order to study the impact that is imposed on the hypothalamic-pituitary-thyroid (HPT) axis of adrenalectomy male Wistar rats by stress caused by swimming, the blood level of triiodothyronine (T3), thyroxine (T4) and thyroid-stimulating hormone (TSH), the expression of TSHβ mRNA at the pituitary and thyrotropin releasing hormone (TRH) expression at the paraventricular nucleus (PVN) were measured. A total of 50 male Wistar rats of 6-8 weeks of age and with an average weight of 190-210 grams were randomly divided into the following two groups: The surgical (without adrenal glands) and non-surgical (adrenalectomy) group. These two groups were then divided into the following five groups, according to the time delay of sacrifice following forced swim (10 min, 2 h, 12 h and 24 h) and control (not subjected to swimming) groups. A bilateral adrenalectomy animal model was established. Serum TSH in the blood was measurement by chemiluminescent immunoassay, and cerebrum tissue were excised for the measurement of TRH expression using an immunohistochemistry assay. In addition, pituitaries were excised for the extraction of total RNA. Finally, reverse transcription-quantitative polymerase chain reaction was performed for quantitation of TSHβ. Following swimming, the serum T3, T4 and TSH, the TSHβ mRNA expression levels in the pituitary and the TRH expression in the PVN of the surgical group were gradually increased. In the non-surgical group, no significant differences were observed in the serum T3, T4 and TSH levels compared with the control group. The TSHβ mRNA expression at the pituitary showed a similar result. Furthermore, the TRH expression at PVN was gradually increased and stress from swimming could increase the blood T4, T3 and TSH levels, TSHβ mRNA expression at the pituitary and TRH expression at the PVN in adrenalectomy Wistar rats. Moreover, the index in the surgical group changed significantly compared with the non-surgical group. In conclusion, the results suggest that there is a positive correlation between stress from forced swimming and the variation of the HPT axis.
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Affiliation(s)
- Qiuyan Sun
- Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Aihua Liu
- Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yanan Ma
- Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Anyi Wang
- Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xinhong Guo
- Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Weiping Teng
- Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yaqiu Jiang
- Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
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Ortiga-Carvalho TM, Chiamolera MI, Pazos-Moura CC, Wondisford FE. Hypothalamus-Pituitary-Thyroid Axis. Compr Physiol 2016; 6:1387-428. [PMID: 27347897 DOI: 10.1002/cphy.c150027] [Citation(s) in RCA: 214] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The hypothalamus-pituitary-thyroid (HPT) axis determines the set point of thyroid hormone (TH) production. Hypothalamic thyrotropin-releasing hormone (TRH) stimulates the synthesis and secretion of pituitary thyrotropin (thyroid-stimulating hormone, TSH), which acts at the thyroid to stimulate all steps of TH biosynthesis and secretion. The THs thyroxine (T4) and triiodothyronine (T3) control the secretion of TRH and TSH by negative feedback to maintain physiological levels of the main hormones of the HPT axis. Reduction of circulating TH levels due to primary thyroid failure results in increased TRH and TSH production, whereas the opposite occurs when circulating THs are in excess. Other neural, humoral, and local factors modulate the HPT axis and, in specific situations, determine alterations in the physiological function of the axis. The roles of THs are vital to nervous system development, linear growth, energetic metabolism, and thermogenesis. THs also regulate the hepatic metabolism of nutrients, fluid balance and the cardiovascular system. In cells, TH actions are mediated mainly by nuclear TH receptors (210), which modify gene expression. T3 is the preferred ligand of THR, whereas T4, the serum concentration of which is 100-fold higher than that of T3, undergoes extra-thyroidal conversion to T3. This conversion is catalyzed by 5'-deiodinases (D1 and D2), which are TH-activating enzymes. T4 can also be inactivated by conversion to reverse T3, which has very low affinity for THR, by 5-deiodinase (D3). The regulation of deiodinases, particularly D2, and TH transporters at the cell membrane control T3 availability, which is fundamental for TH action. © 2016 American Physiological Society. Compr Physiol 6:1387-1428, 2016.
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Affiliation(s)
- Tania M Ortiga-Carvalho
- Institute of Biophysics Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro, Brazil
| | - Maria I Chiamolera
- Department of Medicine, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, Brazil
| | - Carmen C Pazos-Moura
- Institute of Biophysics Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro, Brazil
| | - Fredic E Wondisford
- Department of Medicine, Rutgers-Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA
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57
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Kolaj M, Zhang L, Renaud LP. L-type calcium channels and MAP kinase contribute to thyrotropin-releasing hormone-induced depolarization in thalamic paraventricular nucleus neurons. Am J Physiol Regul Integr Comp Physiol 2016; 310:R1120-7. [PMID: 27009047 PMCID: PMC4935505 DOI: 10.1152/ajpregu.00082.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 03/18/2016] [Indexed: 12/11/2022]
Abstract
In rat paraventricular thalamic nucleus (PVT) neurons, activation of thyrotropin-releasing hormone (TRH) receptors enhances neuronal excitability via concurrent decrease in a G protein-coupled inwardly rectifying K (GIRK)-like conductance and opening of a cannabinoid receptor-sensitive transient receptor potential canonical (TRPC)-like conductance. Here, we investigated the calcium (Ca(2+)) contribution to the components of this TRH-induced response. TRH-induced membrane depolarization was reduced in the presence of intracellular BAPTA, also in media containing nominally zero [Ca(2+)]o, suggesting a critical role for both intracellular Ca(2+) release and Ca(2+) influx. TRH-induced inward current was unchanged by T-type Ca(2+) channel blockade, but was decreased by blockade of high-voltage-activated Ca(2+) channels (HVACCs). Both the pharmacologically isolated GIRK-like and the TRPC-like components of the TRH-induced response were decreased by nifedipine and increased by BayK8644, implying Ca(2+) influx via L-type Ca(2+) channels. Only the TRPC-like conductance was reduced by either thapsigargin or dantrolene, suggesting a role for ryanodine receptors and Ca(2+)-induced Ca(2+) release in this component of the TRH-induced response. In pituitary and other cell lines, TRH stimulates MAPK. In PVT neurons, only the GIRK-like component of the TRH-induced current was selectively decreased in the presence of PD98059, a MAPK inhibitor. Collectively, the data imply that TRH-induced depolarization and inward current in PVT neurons involve both a dependency on extracellular Ca(2+) influx via opening of L-type Ca(2+) channels, a sensitivity of a TRPC-like component to intracellular Ca(2+) release via ryanodine channels, and a modulation by MAPK of a GIRK-like conductance component.
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Affiliation(s)
- Miloslav Kolaj
- Ottawa Hospital Research Institute, Neuroscience Program and University of Ottawa, Department of Medicine, Ottawa, Ontario, Canada
| | - Li Zhang
- Ottawa Hospital Research Institute, Neuroscience Program and University of Ottawa, Department of Medicine, Ottawa, Ontario, Canada
| | - Leo P Renaud
- Ottawa Hospital Research Institute, Neuroscience Program and University of Ottawa, Department of Medicine, Ottawa, Ontario, Canada
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Duntas L. NEW INSIGHTS INTO THE HYPOTHALAMIC-PITUITARY-THYROID AXIS. ACTA ENDOCRINOLOGICA (BUCHAREST, ROMANIA : 2005) 2016; 12:125-129. [PMID: 31149076 PMCID: PMC6535279 DOI: 10.4183/aeb.2016.125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The discovery of thyrotropin releasing hormone (TRH) in 1969 was the definitive step in decoding the hypothalamic-pituitary thyroid (HPT) axis, thereby opening up the era of neuroendocrinology, while it also revolutionized the diagnostic and therapeutic approach to patients with thyroid diseases. TRH, produced in the hypothalamus, is the central regulator of the HPT. It functions via neurons originating in the paraventricular nucleus (PVN), which integrates multiple neuronal and humoral signals and resets the HPT axis according to variations of external and internal environmental conditions. The TRH activates TSH in the pituitary that stimulates the secretion of thyroxine from thyroid which, in turn, exerts a negative feedback on TSH and TRH secretion. However, various factors are involved in the regulation of the HPT axis. Leptin has both indirect and direct effects on TRH regulation, the former by regulating agouti-related peptide (AGRP) in the arcuate nucleus (ARN) that antagonizes the α-MSH stimulatory activity on pro-TRH gene expression in the PVN, and the latter by stimulating hypothalamic TRH expression, TRH transcription via stimulation of pro-convertase 1 and 2 expression, which lead to enhanced processing of pro-TRH into TRH. The interplay of TRH with leptin and the recently reported influence of ghrelin on the HPT axis can alter the setpoint of the axis. The polyphenol resveratrol, as recently observed, exerts an anxiolytic and antidepressant activity in subclinical hypothyroid (SCH) rats. Resveratrol, by decreasing both TSH and TRH mRNA expression, regulates the HPT axis, while in parallel it regulates the Wnt/β-catenin pathway in the hippocampus. These findings open up possibilities for the therapeutic use of resveratrol as coadjuvant, especially in overt and SCH states marked by anxiety and depression. The clinician should be aware of clinical changes that can invalidate the normal regulation of the HPT axis, the most commonly observed being medications and comorbidities.
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Affiliation(s)
- L.H. Duntas
- University of Athens, Evgenideion Hospital, Unit of Endocrinology, Diabetes and Metabolism, Thyroid Section, Athens, Greece
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Bauer PV, Hamr SC, Duca FA. Regulation of energy balance by a gut-brain axis and involvement of the gut microbiota. Cell Mol Life Sci 2016; 73:737-55. [PMID: 26542800 PMCID: PMC11108299 DOI: 10.1007/s00018-015-2083-z] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 10/22/2015] [Accepted: 10/26/2015] [Indexed: 12/11/2022]
Abstract
Despite significant progress in understanding the homeostatic regulation of energy balance, successful therapeutic options for curbing obesity remain elusive. One potential target for the treatment of obesity is via manipulation of the gut-brain axis, a complex bidirectional communication system that is crucial in maintaining energy homeostasis. Indeed, ingested nutrients induce secretion of gut peptides that act either via paracrine signaling through vagal and non-vagal neuronal relays, or in an endocrine fashion via entry into circulation, to ultimately signal to the central nervous system where appropriate responses are generated. We review here the current hypotheses of nutrient sensing mechanisms of enteroendocrine cells, including the release of gut peptides, mainly cholecystokinin, glucagon-like peptide-1, and peptide YY, and subsequent gut-to-brain signaling pathways promoting a reduction of food intake and an increase in energy expenditure. Furthermore, this review highlights recent research suggesting this energy regulating gut-brain axis can be influenced by gut microbiota, potentially contributing to the development of obesity.
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Affiliation(s)
- Paige V Bauer
- Department of Medicine, Toronto General Research Institute, UHN, Toronto, ON, M5G 1L7, Canada
- Department of Physiology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Sophie C Hamr
- Department of Medicine, Toronto General Research Institute, UHN, Toronto, ON, M5G 1L7, Canada
- Department of Physiology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Frank A Duca
- Department of Medicine, Toronto General Research Institute, UHN, Toronto, ON, M5G 1L7, Canada.
- MaRS Centre, Toronto Medical Discovery Tower, Room 10-701H, 101 College Street, Toronto, ON, M5G 1L7, Canada.
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Khan MZ, He L, Zhuang X. The emerging role of GPR50 receptor in brain. Biomed Pharmacother 2016; 78:121-128. [PMID: 26898433 DOI: 10.1016/j.biopha.2016.01.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Accepted: 01/06/2016] [Indexed: 01/08/2023] Open
Abstract
GPR50 receptor one of the member of G protein-coupled receptors (GPCRs) is extensively expressed in the pituitary, hypothalamus,cortex, midbrain, pons, amygdala, and in several brainstem nuclei. The exact function of this receptor in brain is remains unclear. This review presents current knowledge regarding the function of GPR50 receptor in brain, with a focus on role of this receptor in the hypothalamus-pituitary-adrenal (HPA) axis and the glucocorticoid receptor (GR) signaling, leptin signaling, adaptive thermogenesis, torpor, neurite outgrowth, and self-renewal and neuronal differentiation of neural progenitor cells NPCs. Although the results are encouraging, further research is needed to clarify GPR50 role in neurobiology of mood disorders, adaptive thermogenesis, torpor, and in the pathophysiology of neurological disorders.
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Affiliation(s)
- Muhammad Zahid Khan
- Department of Pharmacology, China Pharmaceutical University, Nanjing 210009, China.
| | - Ling He
- China Pharmaceutical University, Department of Pharmacology, No. 24 Tong Jia Xiang, Nanjing,Jiang Su Province 210009, China
| | - Xuxu Zhuang
- China Pharmaceutical University, Department of Pharmacology, No. 24 Tong Jia Xiang, Nanjing,Jiang Su Province 210009, China
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Calvino C, Império GE, Wilieman M, Costa-E-Sousa RH, Souza LL, Trevenzoli IH, Pazos-Moura CC. Hypothyroidism Induces Hypophagia Associated with Alterations in Protein Expression of Neuropeptide Y and Proopiomelanocortin in the Arcuate Nucleus, Independently of Hypothalamic Nuclei-Specific Changes in Leptin Signaling. Thyroid 2016; 26:134-43. [PMID: 26538454 DOI: 10.1089/thy.2015.0384] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND Thyroid hormone and leptin are essential regulators of energy homeostasis. Both hormones stimulate energy expenditure but have opposite effects on appetite. The mechanisms behind food intake regulation in thyroid dysfunctions are poorly understood. It has been shown that hypothyroid rats exhibited impaired leptin anorexigenic effect and signaling in total hypothalamus, even though they were hypophagic. It was hypothesized that hypothyroidism modulates the expression of neuropeptides: orexigenic neuropeptide Y (NPY) and anorexigenic proopiomelanocortin (POMC), independently of inducing nuclei-specific changes in hypothalamic leptin signaling. METHODS Adult male rats were rendered hypothyroid by administration of 0.03% methimazole in the drinking water for 21 days. Protein content of NPY, POMC, and leptin signaling (the signal transducer and activator of transcription 3 [STAT3] pathway) were evaluated by Western blot, and mRNA levels by real time reverse transcription polymerase chain reaction in arcuate (ARC), ventromedial (VMN), and paraventricular (PVN) hypothalamic nuclei isolated from euthyroid (eu) and hypothyroid (hypo) rats. Leptin anorexigenic effect was tested by recording food intake for two hours after intracerebroventricular (i.c.v.) administration of leptin. Statistical differences were considered significant at p ≤ 0.05. RESULTS Hypothyroidism was confirmed by decreased serum triiodothyronine, thyroxine, and increased thyrotropin, in addition to increased levels of pro-TRH mRNA in PVN and Dio2 mRNA in the ARC of hypo rats. Hypothyroidism decreased body weight and food intake associated with decreased protein content of NPY and increased content of POMC in the ARC. Conversely, hypothyroidism induced central resistance to the acute anorexigenic effect of leptin, since while euthyroid rats displayed reduced food intake after leptin i.c.v. injection, hypothyroid rats showed no response. Hypothyroid rats exhibited decreased leptin receptor (ObRb) protein content in ARC and VMN but not in PVN nucleus. ObRb protein changes were concomitant with decreased phosphorylated STAT3 in the ARC, and decreased total STAT3 in VMN and PVN. However, hypothyroidism did not affect mRNA levels of Lepr or Stat3 in the hypothalamic nuclei. CONCLUSIONS Experimental hypothyroidism induced a negative energy balance accompanied by decreased NPY and increased POMC protein content in the ARC, resulting in predominance of anorexigenic pathways, despite central leptin resistance and impairment of the leptin signaling cascade in a nuclei-specific manner.
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Affiliation(s)
- Camila Calvino
- 1 Laboratory of Molecular Endocrinology, Federal University of Rio de Janeiro , Rio de Janeiro, Brazil
| | - Güínever Eustáquio Império
- 2 Laboratory of Translational Endocrinology, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro , Rio de Janeiro, Brazil
| | - Marianna Wilieman
- 1 Laboratory of Molecular Endocrinology, Federal University of Rio de Janeiro , Rio de Janeiro, Brazil
| | | | - Luana Lopes Souza
- 1 Laboratory of Molecular Endocrinology, Federal University of Rio de Janeiro , Rio de Janeiro, Brazil
| | - Isis Hara Trevenzoli
- 1 Laboratory of Molecular Endocrinology, Federal University of Rio de Janeiro , Rio de Janeiro, Brazil
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Intracellular postsynaptic cannabinoid receptors link thyrotropin-releasing hormone receptors to TRPC-like channels in thalamic paraventricular nucleus neurons. Neuroscience 2015; 311:81-91. [DOI: 10.1016/j.neuroscience.2015.10.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 10/07/2015] [Accepted: 10/08/2015] [Indexed: 12/16/2022]
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Tasker JG, Chen C, Fisher MO, Fu X, Rainville JR, Weiss GL. Endocannabinoid Regulation of Neuroendocrine Systems. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 125:163-201. [PMID: 26638767 DOI: 10.1016/bs.irn.2015.09.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The hypothalamus is a part of the brain that is critical for sustaining life through its homeostatic control and integrative regulation of the autonomic nervous system and neuroendocrine systems. Neuroendocrine function in mammals is mediated mainly through the control of pituitary hormone secretion by diverse neuroendocrine cell groups in the hypothalamus. Cannabinoid receptors are expressed throughout the hypothalamus, and endocannabinoids have been found to exert pronounced regulatory effects on neuroendocrine function via modulation of the outputs of several neuroendocrine systems. Here, we review the physiological regulation of neuroendocrine function by endocannabinoids, focusing on the role of endocannabinoids in the neuroendocrine regulation of the stress response, food intake, fluid homeostasis, and reproductive function. Cannabis sativa (marijuana) has a long history of recreational and/or medicinal use dating back to ancient times. It was used as an analgesic, anesthetic, and antianxiety herb as early as 2600 B.C. The hedonic, anxiolytic, and mood-elevating properties of cannabis have also been cited in ancient records from different cultures. However, it was not until 1964 that the psychoactive constituent of cannabis, Δ(9)-tetrahydrocannabinol, was isolated and its chemical structure determined (Gaoni & Mechoulam, 1964).
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Affiliation(s)
- Jeffrey G Tasker
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, USA; Neuroscience Program, Tulane University, New Orleans, Louisiana, USA.
| | - Chun Chen
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, USA
| | - Marc O Fisher
- Neuroscience Program, Tulane University, New Orleans, Louisiana, USA
| | - Xin Fu
- Neuroscience Program, Tulane University, New Orleans, Louisiana, USA
| | - Jennifer R Rainville
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, USA
| | - Grant L Weiss
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, USA
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64
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Stoney PN, Helfer G, Rodrigues D, Morgan PJ, McCaffery P. Thyroid hormone activation of retinoic acid synthesis in hypothalamic tanycytes. Glia 2015; 64:425-39. [PMID: 26527258 PMCID: PMC4949630 DOI: 10.1002/glia.22938] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 10/08/2015] [Accepted: 10/12/2015] [Indexed: 11/11/2022]
Abstract
Thyroid hormone (TH) is essential for adult brain function and its actions include several key roles in the hypothalamus. Although TH controls gene expression via specific TH receptors of the nuclear receptor class, surprisingly few genes have been demonstrated to be directly regulated by TH in the hypothalamus, or the adult brain as a whole. This study explored the rapid induction by TH of retinaldehyde dehydrogenase 1 (Raldh1), encoding a retinoic acid (RA)-synthesizing enzyme, as a gene specifically expressed in hypothalamic tanycytes, cells that mediate a number of actions of TH in the hypothalamus. The resulting increase in RA may then regulate gene expression via the RA receptors, also of the nuclear receptor class. In vivo exposure of the rat to TH led to a significant and rapid increase in hypothalamic Raldh1 within 4 hours. That this may lead to an in vivo increase in RA is suggested by the later induction by TH of the RA-responsive gene Cyp26b1. To explore the actions of RA in the hypothalamus as a potential mediator of TH control of gene regulation, an ex vivo hypothalamic rat slice culture method was developed in which the Raldh1-expressing tanycytes were maintained. These slice cultures confirmed that TH did not act on genes regulating energy balance but could induce Raldh1. RA has the potential to upregulate expression of genes involved in growth and appetite, Ghrh and Agrp. This regulation is acutely sensitive to epigenetic changes, as has been shown for TH action in vivo. These results indicate that sequential triggering of two nuclear receptor signalling systems has the capability to mediate some of the functions of TH in the hypothalamus.
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Affiliation(s)
- Patrick N Stoney
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, AB25 2ZD, United Kingdom
| | - Gisela Helfer
- Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, Aberdeen, Scotland, AB21 9SB, United Kingdom
| | - Diana Rodrigues
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, AB25 2ZD, United Kingdom
| | - Peter J Morgan
- Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, Aberdeen, Scotland, AB21 9SB, United Kingdom
| | - Peter McCaffery
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, AB25 2ZD, United Kingdom
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Abstract
Prolactin (PRL) released from lactotrophs of the anterior pituitary gland in response to the suckling by the offspring is the major hormonal signal responsible for stimulation of milk synthesis in the mammary glands. PRL secretion is under chronic inhibition exerted by dopamine (DA), which is released from neurons of the arcuate nucleus of the hypothalamus into the hypophyseal portal vasculature. Suckling by the young activates ascending systems that decrease the release of DA from this system, resulting in enhanced responsiveness to one or more PRL-releasing hormones, such as thyrotropin-releasing hormone. The neuropeptide oxytocin (OT), synthesized in magnocellular neurons of the hypothalamic supraoptic, paraventricular, and several accessory nuclei, is responsible for contracting the myoepithelial cells of the mammary gland to produce milk ejection. Electrophysiological recordings demonstrate that shortly before each milk ejection, the entire neurosecretory OT population fires a synchronized burst of action potentials (the milk ejection burst), resulting in release of OT from nerve terminals in the neurohypophysis. Both of these neuroendocrine systems undergo alterations in late gestation that prepare them for the secretory demands of lactation, and that reduce their responsiveness to stimuli other than suckling, especially physical stressors. The demands of milk synthesis and release produce a condition of negative energy balance in the suckled mother, and, in laboratory rodents, are accompanied by a dramatic hyperphagia. The reduction in secretion of the adipocyte hormone, leptin, a hallmark of negative energy balance, may be an important endocrine signal to hypothalamic systems that integrate lactation-associated food intake with neuroendocrine systems.
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Affiliation(s)
- William R Crowley
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah Health Sciences Center, Salt Lake City, Utah
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66
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Joseph-Bravo P, Jaimes-Hoy L, Uribe RM, Charli JL. 60 YEARS OF NEUROENDOCRINOLOGY: TRH, the first hypophysiotropic releasing hormone isolated: control of the pituitary-thyroid axis. J Endocrinol 2015; 226:T85-T100. [PMID: 26101376 DOI: 10.1530/joe-15-0124] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/22/2015] [Indexed: 12/25/2022]
Abstract
This review presents the findings that led to the discovery of TRH and the understanding of the central mechanisms which control hypothalamus-pituitary-thyroid axis (HPT) activity. The earliest studies on thyroid physiology are now dated a century ago when basal metabolic rate was associated with thyroid status. It took over 50 years to identify the key elements involved in the HPT axis. Thyroid hormones (TH: T4 and T3) were characterized first, followed by the semi-purification of TSH whose later characterization paralleled that of TRH. Studies on the effects of TH became possible with the availability of synthetic hormones. DNA recombinant techniques facilitated the identification of all the elements involved in the HPT axis, including their mode of regulation. Hypophysiotropic TRH neurons, which control the pituitary-thyroid axis, were identified among other hypothalamic neurons which express TRH. Three different deiodinases were recognized in various tissues, as well as their involvement in cell-specific modulation of T3 concentration. The role of tanycytes in setting TRH levels due to the activity of deiodinase type 2 and the TRH-degrading ectoenzyme was unraveled. TH-feedback effects occur at different levels, including TRH and TSH synthesis and release, deiodinase activity, pituitary TRH-receptor and TRH degradation. The activity of TRH neurons is regulated by nutritional status through neurons of the arcuate nucleus, which sense metabolic signals such as circulating leptin levels. Trh expression and the HPT axis are activated by energy demanding situations, such as cold and exercise, whereas it is inhibited by negative energy balance situations such as fasting, inflammation or chronic stress. New approaches are being used to understand the activity of TRHergic neurons within metabolic circuits.
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Affiliation(s)
- Patricia Joseph-Bravo
- Departamento de Genética del Desarrollo y Fisiología MolecularInstituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), A.P. 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Lorraine Jaimes-Hoy
- Departamento de Genética del Desarrollo y Fisiología MolecularInstituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), A.P. 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Rosa-María Uribe
- Departamento de Genética del Desarrollo y Fisiología MolecularInstituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), A.P. 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Jean-Louis Charli
- Departamento de Genética del Desarrollo y Fisiología MolecularInstituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), A.P. 510-3, Cuernavaca, Morelos 62250, Mexico
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Joseph-Bravo P, Jaimes-Hoy L, Charli JL. Regulation of TRH neurons and energy homeostasis-related signals under stress. J Endocrinol 2015; 224:R139-59. [PMID: 25563352 DOI: 10.1530/joe-14-0593] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Energy homeostasis relies on a concerted response of the nervous and endocrine systems to signals evoked by intake, storage, and expenditure of fuels. Glucocorticoids (GCs) and thyroid hormones are involved in meeting immediate energy demands, thus placing the hypothalamo-pituitary-thyroid (HPT) and hypothalamo-pituitary-adrenal axes at a central interface. This review describes the mode of regulation of hypophysiotropic TRHergic neurons and the evidence supporting the concept that they act as metabolic integrators. Emphasis has been be placed on i) the effects of GCs on the modulation of transcription of Trh in vivo and in vitro, ii) the physiological and molecular mechanisms by which acute or chronic situations of stress and energy demands affect the activity of TRHergic neurons and the HPT axis, and iii) the less explored role of non-hypophysiotropic hypothalamic TRH neurons. The partial evidence gathered so far is indicative of a contrasting involvement of distinct TRH cell types, manifested through variability in cellular phenotype and physiology, including rapid responses to energy demands for thermogenesis or physical activity and nutritional status that may be modified according to stress history.
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Affiliation(s)
- Patricia Joseph-Bravo
- Departamento de Genética del Desarrollo y Fisiología MolecularInstituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), A.P. 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Lorraine Jaimes-Hoy
- Departamento de Genética del Desarrollo y Fisiología MolecularInstituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), A.P. 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Jean-Louis Charli
- Departamento de Genética del Desarrollo y Fisiología MolecularInstituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), A.P. 510-3, Cuernavaca, Morelos 62250, Mexico
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Mayerl S, Liebsch C, Visser TJ, Heuer H. Absence of TRH receptor 1 in male mice affects gastric ghrelin production. Endocrinology 2015; 156:755-67. [PMID: 25490146 DOI: 10.1210/en.2014-1395] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
TRH not only functions as a thyrotropin releasing hormone but also acts as a neuropeptide in central circuits regulating food intake and energy expenditure. As one suggested mode of action, TRH expressed in the caudal brainstem influences vagal activity by activating TRH receptor 1 (TRH-R1). In order to evaluate the impact of a diminished medullary TRH signaling on ghrelin metabolism, we analyzed metabolic changes of TRH-R1 knockout (R1ko) mice in response to 24 hours of food deprivation. Because R1ko mice are hypothyroid, we also studied eu- and hypothyroid wild-type (wt) animals and R1ko mice rendered euthyroid by thyroid hormone treatment. Independent of their thyroidal state, R1ko mice displayed a higher body weight loss than wt animals and a delayed reduction in locomotor activity upon fasting. Ghrelin transcript levels in the stomach as well as total ghrelin levels in the circulation were equally high in fasted wt and R1ko mice. In contrast, only wt mice responded to fasting with a rise in ghrelin-O-acyltransferase mRNA expression and consequently an increase in serum levels of acylated ghrelin. Together, our data suggest that an up-regulation of medullary TRH expression and subsequently enhanced activation of TRH-R1 in the vagal system represents a critical step in the stimulation of ghrelin-O-acyltransferase expression upon starvation that in turn is important for adjusting the circulating levels of acylated ghrelin to the fasting condition.
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Affiliation(s)
- Steffen Mayerl
- Leibniz Institute for Age Research/Fritz Lipmann Institute (S.M., C.L., H.H.), D-07745 Jena, Germany; Brandenburg University of Technology Cottbus-Senftenberg (C.L.), D-01968 Senftenberg, Germany; Department of Internal Medicine (T.J.V.), Erasmus Medical Center, Rotterdam, The Netherlands; and Leibniz Research Institute for Environmental Medicine (H.H.), Düsseldorf, Germany
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69
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Abstract
Industrial chemical contaminants have a variable impact on the hypothalamic-pituitary-thyroid axis, this depending both on their class and on confounding factors. Today, mounting evidence is pointing to the role of environmental factors, and specifically EDCs, in the current distressing upsurge in the incidence of thyroid disease. The unease is warranted. These substances, which are nowadays rife in our environments (including in foodstuffs), have been shown to interfere with thyroid hormone action, biosynthesis, and metabolism, resulting in disruption of tissue homeostasis and/or thyroid function. Importantly, based on the concept of the "nonmonotonic dose-response curve", the relationship between dose and effect has often been found to be nonlinear. Thus, small doses can induce unpredictable, adverse effects, one case being polychlorinated biphenyls (PCBs), of which congener(s) may centrally inhibit the hypothalamic-pituitary-thyroid axis, or dissociate thyroid receptor and selectively affect thyroid hormone signaling and action. This means that PCBs can act as agonists or antagonists at the receptor level, underlining the complexity of the interaction. This review highlights the multifold activity of chemicals demonstrated to cause thyroid disruption. It also represents a call to action among clinicians to undertake systematic monitoring of thyroid function and registering of the classes of EDs and additionally urges broader scientific collaborations to clarify these chemicals' molecular mechanisms of action, substances whose prevalence in our environments is disrupting not only the thyroid but all life on earth.
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Affiliation(s)
- Leonidas H Duntas
- Unit of Endocrinology, Metabolism and Diabetes, Evgenidion Hospital, University of Athens, Papadiamantopoulou 20, 11520, Athens, Greece,
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70
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Martínez-Armenta M, Díaz de León-Guerrero S, Catalán A, Alvarez-Arellano L, Uribe RM, Subramaniam M, Charli JL, Pérez-Martínez L. TGFβ2 regulates hypothalamic Trh expression through the TGFβ inducible early gene-1 (TIEG1) during fetal development. Mol Cell Endocrinol 2015; 400:129-39. [PMID: 25448845 PMCID: PMC4415168 DOI: 10.1016/j.mce.2014.10.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 09/01/2014] [Accepted: 10/27/2014] [Indexed: 01/05/2023]
Abstract
The hypothalamus regulates the homeostasis of the organism by controlling hormone secretion from the pituitary. The molecular mechanisms that regulate the differentiation of the hypothalamic thyrotropin-releasing hormone (TRH) phenotype are poorly understood. We have previously shown that Klf10 or TGFβ inducible early gene-1 (TIEG1) is enriched in fetal hypothalamic TRH neurons. Here, we show that expression of TGFβ isoforms (1-3) and both TGFβ receptors (TβRI and II) occurs in the hypothalamus concomitantly with the establishment of TRH neurons during late embryonic development. TGFβ2 induces Trh expression via a TIEG1 dependent mechanism. TIEG1 regulates Trh expression through an evolutionary conserved GC rich sequence on the Trh promoter. Finally, in mice deficient in TIEG1, Trh expression is lower than in wild type animals at embryonic day 17. These results indicate that TGFβ signaling, through the upregulation of TIEG1, plays an important role in the establishment of Trh expression in the embryonic hypothalamus.
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MESH Headings
- Animals
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- Embryo, Mammalian
- Fetus
- Gene Expression Regulation, Developmental
- Hypothalamus/cytology
- Hypothalamus/growth & development
- Hypothalamus/metabolism
- Immunohistochemistry
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Neurons/cytology
- Neurons/metabolism
- Primary Cell Culture
- Promoter Regions, Genetic
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Rats
- Rats, Wistar
- Receptor, Transforming Growth Factor-beta Type I
- Receptor, Transforming Growth Factor-beta Type II
- Receptors, Transforming Growth Factor beta/genetics
- Receptors, Transforming Growth Factor beta/metabolism
- Signal Transduction
- Thyrotropin-Releasing Hormone/genetics
- Thyrotropin-Releasing Hormone/metabolism
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transforming Growth Factor beta1/genetics
- Transforming Growth Factor beta1/metabolism
- Transforming Growth Factor beta2/genetics
- Transforming Growth Factor beta2/metabolism
- Transforming Growth Factor beta3/genetics
- Transforming Growth Factor beta3/metabolism
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Affiliation(s)
- Miriam Martínez-Armenta
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Sol Díaz de León-Guerrero
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Ana Catalán
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Lourdes Alvarez-Arellano
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Rosa Maria Uribe
- Departamento de Genética y Fisiología Molecular, Instituto de Biotecnología, UNAM, Cuernavaca, Morelos, Mexico
| | | | - Jean-Louis Charli
- Departamento de Genética y Fisiología Molecular, Instituto de Biotecnología, UNAM, Cuernavaca, Morelos, Mexico
| | - Leonor Pérez-Martínez
- Laboratorio de Neuroinmunobiología, Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico.
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71
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Wozniak DR, Quinnell TG. Unmet needs of patients with narcolepsy: perspectives on emerging treatment options. Nat Sci Sleep 2015; 7:51-61. [PMID: 26045680 PMCID: PMC4447169 DOI: 10.2147/nss.s56077] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The treatment options currently available for narcolepsy are often unsatisfactory due to suboptimal efficacy, troublesome side effects, development of drug tolerance, and inconvenience. Our understanding of the neurobiology of narcolepsy has greatly improved over the last decade. This knowledge has not yet translated into additional therapeutic options for patients, but progress is being made. Some compounds, such as histaminergic H3 receptor antagonists, may prove useful in symptom control of narcolepsy. The prospect of finding a cure still seems distant, but hypocretin replacement therapy offers some promise. In this narrative review, we describe these developments and others which may yield more effective narcolepsy treatments in the future.
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Affiliation(s)
- Dariusz R Wozniak
- Respiratory Support and Sleep Centre, Papworth Hospital, Cambridge, UK
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72
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Hoermann R, Midgley JEM, Larisch R, Dietrich JW. Homeostatic Control of the Thyroid-Pituitary Axis: Perspectives for Diagnosis and Treatment. Front Endocrinol (Lausanne) 2015; 6:177. [PMID: 26635726 PMCID: PMC4653296 DOI: 10.3389/fendo.2015.00177] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/04/2015] [Indexed: 12/20/2022] Open
Abstract
The long-held concept of a proportional negative feedback control between the thyroid and pituitary glands requires reconsideration in the light of more recent studies. Homeostatic equilibria depend on dynamic inter-relationships between thyroid hormones and pituitary thyrotropin (TSH). They display a high degree of individuality, thyroid-state-related hierarchy, and adaptive conditionality. Molecular mechanisms involve multiple feedback loops on several levels of organization, different time scales, and varying conditions of their optimum operation, including a proposed feedforward motif. This supports the concept of a dampened response and multistep regulation, making the interactions between TSH, FT4, and FT3 situational and mathematically more complex. As a homeostatically integrated parameter, TSH becomes neither normatively fixed nor a precise marker of euthyroidism. This is exemplified by the therapeutic situation with l-thyroxine (l-T4) where TSH levels defined for optimum health may not apply equivalently during treatment. In particular, an FT3-FT4 dissociation, discernible FT3-TSH disjoint, and conversion inefficiency have been recognized in l-T4-treated athyreotic patients. In addition to regulating T4 production, TSH appears to play an essential role in maintaining T3 homeostasis by directly controlling deiodinase activity. While still allowing for tissue-specific variation, this questions the currently assumed independence of the local T3 supply. Rather it integrates peripheral and central elements into an overarching control system. On l-T4 treatment, altered equilibria have been shown to give rise to lower circulating FT3 concentrations in the presence of normal serum TSH. While data on T3 in tissues are largely lacking in humans, rodent models suggest that the disequilibria may reflect widespread T3 deficiencies at the tissue level in various organs. As a consequence, the use of TSH, valuable though it is in many situations, should be scaled back to a supporting role that is more representative of its conditional interplay with peripheral thyroid hormones. This reopens the debate on the measurement of free thyroid hormones and encourages the identification of suitable biomarkers. Homeostatic principles conjoin all thyroid parameters into an adaptive context, demanding a more flexible interpretation in the accurate diagnosis and treatment of thyroid dysfunction.
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Affiliation(s)
- Rudolf Hoermann
- Department of Nuclear Medicine, Klinikum Luedenscheid, Luedenscheid, Germany
| | | | - Rolf Larisch
- Department of Nuclear Medicine, Klinikum Luedenscheid, Luedenscheid, Germany
| | - Johannes W. Dietrich
- Medical Department I, Endocrinology and Diabetology, Bergmannsheil University Hospitals, Ruhr University of Bochum, Bochum, Germany
- Ruhr Center for Rare Diseases (CeSER), Ruhr University of Bochum and Witten/Herdecke University, Bochum, Germany
- *Correspondence: Johannes W. Dietrich,
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73
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Affiliation(s)
- Sherifa Ahmed Hamed
- Department of Neurology and Psychiatry, Faculty of Medicine, Assiut University Hospital, Floor # 4, Room # 4, P.O.Box 71516, Assiut, Egypt
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74
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Hoermann R, Midgley JEM, Giacobino A, Eckl WA, Wahl HG, Dietrich JW, Larisch R. Homeostatic equilibria between free thyroid hormones and pituitary thyrotropin are modulated by various influences including age, body mass index and treatment. Clin Endocrinol (Oxf) 2014; 81:907-15. [PMID: 24953754 DOI: 10.1111/cen.12527] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 06/06/2014] [Accepted: 06/16/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVE We examined the interrelationships of pituitary thyrotropin (TSH) with circulating thyroid hormones to determine whether they were expressed either invariably or conditionally and distinctively related to influences such as levothyroxine (L-T4) treatment. DESIGN AND METHODS This prospective study employing 1912 consecutive patients analyses the interacting equilibria of TSH and free triiodothyronine (FT3) and free thyroxine (FT4) in the circulation. RESULTS The complex interrelations between FT3, FT4 and TSH were modulated by age, body mass, thyroid volume, antibody status and L-T4 treatment. By group comparison and confirmation by more individual TSH-related regression, FT3 levels were significantly lower in L-T4-treated vs untreated nonhypothyroid autoimmune thyroiditis (median 4·6 vs 4·9 pm, P < 0·001), despite lower TSH (1·49 vs 2·93 mU/l, P < 0·001) and higher FT4 levels (16·8 vs 13·8 pm, P < 0·001) in the treated group. Compared with disease-free controls, the FT3-TSH relationship was significantly displaced in treated patients with carcinoma, with median TSH of 0·21 vs 1·63 (P < 0·001) at a comparable FT3 of 5·0 pm in the groups. Disparities were reflected by calculated deiodinase activity and remained significant even after accounting for confounding influences in a multivariable model. CONCLUSIONS TSH, FT4 and FT3 each have their individual, but also interlocking roles to play in defining the overall patterns of thyroidal expression, regulation and metabolic activity. Equilibria typical of the healthy state are not invariant, but profoundly altered, for example, by L-T4 treatment. Consequently, this suggests the revisitation of strategies for treatment optimization.
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Affiliation(s)
- Rudolf Hoermann
- Department of Nuclear Medicine, Klinikum Luedenscheid, Luedenscheid, Germany
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75
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Herwig A, Campbell G, Mayer CD, Boelen A, Anderson RA, Ross AW, Mercer JG, Barrett P. A thyroid hormone challenge in hypothyroid rats identifies T3 regulated genes in the hypothalamus and in models with altered energy balance and glucose homeostasis. Thyroid 2014; 24:1575-93. [PMID: 25087834 PMCID: PMC4229697 DOI: 10.1089/thy.2014.0169] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND The thyroid hormone triiodothyronine (T3) is known to affect energy balance. Recent evidence points to an action of T3 in the hypothalamus, a key area of the brain involved in energy homeostasis, but the components and mechanisms are far from understood. The aim of this study was to identify components in the hypothalamus that may be involved in the action of T3 on energy balance regulatory mechanisms. METHODS Sprague Dawley rats were made hypothyroid by giving 0.025% methimazole (MMI) in their drinking water for 22 days. On day 21, half the MMI-treated rats received a saline injection, whereas the others were injected with T3. Food intake and body weight measurements were taken daily. Body composition was determined by magnetic resonance imaging, gene expression was analyzed by in situ hybridization, and T3-induced gene expression was determined by microarray analysis of MMI-treated compared to MMI-T3-injected hypothalamic RNA. RESULTS Post mortem serum thyroid hormone levels showed that MMI treatment decreased circulating thyroid hormones and increased thyrotropin (TSH). MMI treatment decreased food intake and body weight. Body composition analysis revealed reduced lean and fat mass in thyroidectomized rats from day 14 of the experiment. MMI treatment caused a decrease in circulating triglyceride concentrations, an increase in nonesterified fatty acids, and decreased insulin levels. A glucose tolerance test showed impaired glucose clearance in the thyroidectomized animals. In the brain, in situ hybridization revealed marked changes in gene expression, including genes such as Mct8, a thyroid hormone transporter, and Agrp, a key component in energy balance regulation. Microarray analysis revealed 110 genes to be up- or downregulated with T3 treatment (± 1.3-fold change, p<0.05). Three genes chosen from the differentially expressed genes were verified by in situ hybridization to be activated by T3 in cells located at or close to the hypothalamic ventricular ependymal layer and differentially expressed in animal models of long- and short-term body weight regulation. CONCLUSION This study identified genes regulated by T3 in the hypothalamus, a key area of the brain involved in homeostasis and neuroendocrine functions. These include genes hitherto not known to be regulated by thyroid status.
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Affiliation(s)
- Annika Herwig
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
- Zoological Institute, University of Hamburg, Hamburg, Germany
| | - Gill Campbell
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Claus-Dieter Mayer
- Biomathematics and Statistics Scotland, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Anita Boelen
- Department of Endocrinology, Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Richard A. Anderson
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Alexander W. Ross
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Julian G. Mercer
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Perry Barrett
- Ingestive Behaviour Group, Rowett Institute for Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
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Fliers E, Kalsbeek A, Boelen A. Beyond the fixed setpoint of the hypothalamus-pituitary-thyroid axis. Eur J Endocrinol 2014; 171:R197-208. [PMID: 25005935 DOI: 10.1530/eje-14-0285] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The hypothalamus-pituitary-thyroid (HPT) axis represents a classical example of an endocrine feedback loop. This review discusses dynamic changes in HPT axis setpoint regulation, identifying their molecular and cellular determinants, and speculates about their functional role. Hypothalamic thyrotropin-releasing hormone neurons were identified as key components of thyroid hormone (TH) setpoint regulation already in the 1980s, and this was followed by the demonstration of a pivotal role for the thyroid hormone receptor beta in negative feedback of TH on the hypothalamic and pituitary level. Gradually, the concept emerged of the HPT axis setpoint as a fixed entity, aiming at a particular TH serum concentration. However, TH serum concentrations appear to be variable and highly responsive to physiological and pathophysiological environmental factors, including the availability or absence of food, inflammation and clock time. During food deprivation and inflammation, TH serum concentrations decrease without a concomitant rise in serum TSH, reflecting a deviation from negative feedback regulation in the HPT axis. Surprisingly, TH action in peripheral organs in these conditions cannot be simply predicted by decreased serum TH concentrations. Instead, diverse environmental stimuli have differential effects on local TH metabolism, e.g. in liver and muscle, occurring quite independently from decreased TH serum concentrations. The net effect of these differential local changes is probably a major determinant of TH action at the tissue level. In sum, hypothalamic HPT axis setpoint regulation as well as TH metabolism at the peripheral organ level is flexible and dynamic, and may adapt the organism in an optimal way to a range of environmental challenges.
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Affiliation(s)
- Eric Fliers
- Department of Endocrinology and MetabolismAcademic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The NetherlandsHypothalamic Integration MechanismsNetherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Andries Kalsbeek
- Department of Endocrinology and MetabolismAcademic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The NetherlandsHypothalamic Integration MechanismsNetherlands Institute for Neuroscience, Amsterdam, The Netherlands Department of Endocrinology and MetabolismAcademic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The NetherlandsHypothalamic Integration MechanismsNetherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Anita Boelen
- Department of Endocrinology and MetabolismAcademic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The NetherlandsHypothalamic Integration MechanismsNetherlands Institute for Neuroscience, Amsterdam, The Netherlands
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Joly-Amado A, Cansell C, Denis RGP, Delbes AS, Castel J, Martinez S, Luquet S. The hypothalamic arcuate nucleus and the control of peripheral substrates. Best Pract Res Clin Endocrinol Metab 2014; 28:725-37. [PMID: 25256767 DOI: 10.1016/j.beem.2014.03.003] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The arcuate nucleus (ARC) of the hypothalamus is particularly regarded as a critical platform that integrates circulating signals of hunger and satiety reflecting energy stores and nutrient availability. Among ARC neurons, pro-opiomelanocortin (POMC) and agouti-related protein and neuropeptide Y (NPY/AgRP neurons) are considered as two opposing branches of the melanocortin signaling pathway. Integration of circulating signals of hunger and satiety results in the release of the melanocortin receptor ligand α-melanocyte-stimulating hormone (αMSH) by the POMC neurons system and decreases feeding and increases energy expenditure. The orexigenic/anabolic action of NPY/AgRP neurons is believed to rely essentially on their inhibitory input onto POMC neurons and second-orders targets. Recent updates in the field have casted a new light on the role of the ARC neurons in the coordinated regulation of peripheral organs involved in the control of nutrient storage, transformation and substrate utilization independent of food intake.
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Affiliation(s)
- Aurélie Joly-Amado
- Univ Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative (BFA) UMR 8251 CNRS, F-75205 Paris, France
| | - Céline Cansell
- Univ Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative (BFA) UMR 8251 CNRS, F-75205 Paris, France
| | - Raphaël G P Denis
- Univ Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative (BFA) UMR 8251 CNRS, F-75205 Paris, France
| | - Anne-Sophie Delbes
- Univ Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative (BFA) UMR 8251 CNRS, F-75205 Paris, France
| | - Julien Castel
- Univ Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative (BFA) UMR 8251 CNRS, F-75205 Paris, France
| | - Sarah Martinez
- Univ Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative (BFA) UMR 8251 CNRS, F-75205 Paris, France
| | - Serge Luquet
- Univ Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative (BFA) UMR 8251 CNRS, F-75205 Paris, France.
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Ghaddab-Zroud R, Seugnet I, Steffensen KR, Demeneix BA, Clerget-Froidevaux MS. Liver X receptor regulation of thyrotropin-releasing hormone transcription in mouse hypothalamus is dependent on thyroid status. PLoS One 2014; 9:e106983. [PMID: 25229406 PMCID: PMC4167690 DOI: 10.1371/journal.pone.0106983] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 08/12/2014] [Indexed: 12/03/2022] Open
Abstract
Reversing the escalating rate of obesity requires increased knowledge of the molecular mechanisms controlling energy balance. Liver X receptors (LXRs) and thyroid hormone receptors (TRs) are key physiological regulators of energetic metabolism. Analysing interactions between these receptors in the periphery has led to a better understanding of the mechanisms involved in metabolic diseases. However, no data is available on such interactions in the brain. We tested the hypothesis that hypothalamic LXR/TR interactions could co-regulate signalling pathways involved in the central regulation of metabolism. Using in vivo gene transfer we show that LXR activation by its synthetic agonist GW3965 represses the transcriptional activity of two key metabolic genes, Thyrotropin-releasing hormone (Trh) and Melanocortin receptor type 4 (Mc4r) in the hypothalamus of euthyroid mice. Interestingly, this repression did not occur in hypothyroid mice but was restored in the case of Trh by thyroid hormone (TH) treatment, highlighting the role of the triiodothyronine (T3) and TRs in this dialogue. Using shLXR to knock-down LXRs in vivo in euthyroid newborn mice, not only abrogated Trh repression but actually increased Trh transcription, revealing a potential inhibitory effect of LXR on the Hypothalamic-Pituitary-Thyroid axis. In vivo chromatin immunoprecipitation (ChIP) revealed LXR to be present on the Trh promoter region in the presence of T3 and that Retinoid X Receptor (RXR), a heterodimerization partner for both TR and LXR, was never recruited simultaneously with LXR. Interactions between the TR and LXR pathways were confirmed by qPCR experiments. T3 treatment of newborn mice induced hypothalamic expression of certain key LXR target genes implicated in metabolism and inflammation. Taken together the results indicate that the crosstalk between LXR and TR signalling in the hypothalamus centres on metabolic and inflammatory pathways.
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Affiliation(s)
- Rym Ghaddab-Zroud
- CNRS UMR 7221-USM 501 « Evolution of Endocrine Regulations », « Regulations, Development and Molecular Diversity » department, Muséum National d’Histoire Naturelle, CP32, Paris, France
| | - Isabelle Seugnet
- CNRS UMR 7221-USM 501 « Evolution of Endocrine Regulations », « Regulations, Development and Molecular Diversity » department, Muséum National d’Histoire Naturelle, CP32, Paris, France
| | - Knut R. Steffensen
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Barbara A. Demeneix
- CNRS UMR 7221-USM 501 « Evolution of Endocrine Regulations », « Regulations, Development and Molecular Diversity » department, Muséum National d’Histoire Naturelle, CP32, Paris, France
| | - Marie-Stéphanie Clerget-Froidevaux
- CNRS UMR 7221-USM 501 « Evolution of Endocrine Regulations », « Regulations, Development and Molecular Diversity » department, Muséum National d’Histoire Naturelle, CP32, Paris, France
- * E-mail:
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Dąbrowska AM, Tarach JS, Kurowska M, Nowakowski A. Thyroid diseases in patients with acromegaly. Arch Med Sci 2014; 10:837-45. [PMID: 25276172 PMCID: PMC4175760 DOI: 10.5114/aoms.2013.36924] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 05/24/2012] [Accepted: 06/14/2012] [Indexed: 01/09/2023] Open
Abstract
Acromegaly often involves the presence of different pathologies of the thyroid gland. Long-lasting stimulation of the follicular epithelium by growth hormone (GH) and insulin-like growth factor 1 (IGF-1) can cause disorders in thyroid function, an increase in its mass and the development of goitre. Acromegalic patients present most frequently with non-toxic multinodular goitre. Nodules are more prevalent in patients with active acromegaly. It has been suggested that then thyroid size increases and it can be reduced through treatment with somatostatin analogues. The relationship between thyroid volume and the level of IGF-1 and the duration of the disease is unclear. Each acromegalic patient requires a hormonal and imaging evaluation of the thyroid when the diagnosis is made, and an accurate evaluation during further observation and treatment. Although the data concerning the co-occurrence of acromegaly and thyroid cancer still remain controversial, it is particularly important to diagnose the patient early and to rule out thyroid cancer.
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Affiliation(s)
| | | | - Maria Kurowska
- Chair and Department of Endocrinology, Medical University of Lublin, Poland
| | - Andrzej Nowakowski
- Chair and Department of Endocrinology, Medical University of Lublin, Poland
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Chausse B, Solon C, Caldeira da Silva CC, Masselli Dos Reis IG, Manchado-Gobatto FB, Gobatto CA, Velloso LA, Kowaltowski AJ. Intermittent fasting induces hypothalamic modifications resulting in low feeding efficiency, low body mass and overeating. Endocrinology 2014; 155:2456-66. [PMID: 24797627 DOI: 10.1210/en.2013-2057] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Intermittent fasting (IF) is an often-used intervention to decrease body mass. In male Sprague-Dawley rats, 24 hour cycles of IF result in light caloric restriction, reduced body mass gain, and significant decreases in the efficiency of energy conversion. Here, we study the metabolic effects of IF in order to uncover mechanisms involved in this lower energy conversion efficiency. After 3 weeks, IF animals displayed overeating during fed periods and lower body mass, accompanied by alterations in energy-related tissue mass. The lower efficiency of energy use was not due to uncoupling of muscle mitochondria. Enhanced lipid oxidation was observed during fasting days, whereas fed days were accompanied by higher metabolic rates. Furthermore, an increased expression of orexigenic neurotransmitters AGRP and NPY in the hypothalamus of IF animals was found, even on feeding days, which could explain the overeating pattern. Together, these effects provide a mechanistic explanation for the lower efficiency of energy conversion observed. Overall, we find that IF promotes changes in hypothalamic function that explain differences in body mass and caloric intake.
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Affiliation(s)
- Bruno Chausse
- Departamento de Bioquímica (B.C., C.C.C., A.J.K.), Instituto de Química, Universidade de São Paulo, 05508-000 Brazil; Faculdade de Ciências Médicas (C.S., L.A.V.), Universidade Estadual de Campinas, 13083-970 Brazil; Faculdade de Ciências Aplicadas (I.G.M., F.B.M-G., C.A.G.), Universidade Estadual de Campinas, 13084-350 Brazil
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81
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Uribe RM, Jaimes-Hoy L, Ramírez-Martínez C, García-Vázquez A, Romero F, Cisneros M, Cote-Vélez A, Charli JL, Joseph-Bravo P. Voluntary exercise adapts the hypothalamus-pituitary-thyroid axis in male rats. Endocrinology 2014; 155:2020-30. [PMID: 24605825 DOI: 10.1210/en.2013-1724] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The hypothalamic-pituitary thyroid (HPT) axis modulates energy homeostasis. Its activity decreases in conditions of negative energy balance but the effects of chronic exercise on the axis are controversial and unknown at hypothalamic level. Wistar male rats were exposed for up to 14 days to voluntary wheel running (WR), or pair-feeding (PF; 18% food restriction), or to repeated restraint (RR), a mild stressor. WR and RR diminished food intake; body weight gain decreased in the 3 experimental groups, but WAT mass and serum leptin more intensely in the WR group. WR, but not RR, produced a delayed inhibition of central markers of HPT axis activity. At day 14, in WR rats paraventricular nucleus-pro-TRH mRNA and serum TSH levels decreased, anterior pituitary TRH-receptor 1 mRNA levels increased, but serum thyroid hormone levels were unaltered, which is consistent with decreased secretion of TRH and clearance of thyroid hormones. A similar pattern was observed if WR animals were euthanized during their activity phase. In contrast, in PF animals the profound drop of HPT axis activity included decreased serum T3 levels and hepatic deiodinase 1 activity; these changes were correlated with an intense increase in serum corticosterone levels. WR effects on HPT axis were not associated with changes in the activity of the hypothalamic-pituitary adrenal axis, but correlated positively with serum leptin levels. These data demonstrate that voluntary WR adapts the status of the HPT axis, through pathways that are distinct from those observed during food restriction or repeated stress.
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Affiliation(s)
- Rosa María Uribe
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca Morelos, México
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82
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Kolaj M, Zhang L, Hermes MLHJ, Renaud LP. Intrinsic properties and neuropharmacology of midline paraventricular thalamic nucleus neurons. Front Behav Neurosci 2014; 8:132. [PMID: 24860449 PMCID: PMC4029024 DOI: 10.3389/fnbeh.2014.00132] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 04/01/2014] [Indexed: 01/01/2023] Open
Abstract
Neurons in the midline and intralaminar thalamic nuclei are components of an interconnected brainstem, limbic and prefrontal cortex neural network that is engaged during arousal, vigilance, motivated and addictive behaviors, and stress. To better understand the cellular mechanisms underlying these functions, here we review some of the recently characterized electrophysiological and neuropharmacological properties of neurons in the paraventricular thalamic nucleus (PVT), derived from whole cell patch clamp recordings in acute rat brain slice preparations. PVT neurons display firing patterns and ionic conductances (IT and IH) that exhibit significant diurnal change. Their resting membrane potential (RMP) is maintained by various ionic conductances that include inward rectifier (Kir), hyperpolarization-activated nonselective cation (HCN) and TWIK-related acid sensitive (TASK) K+ channels. Firing patterns are regulated by high voltage-activated (HVA) and low voltage-activated (LVA) Ca2+ conductances. Moreover, transient receptor potential (TRP)-like nonselective cation channels together with Ca2+- and Na+-activated K+ conductances (KCa; KNa) contribute to unique slow afterhyperpolarizing potentials (sAHPs) that are generally not detectable in lateral thalamic or reticular thalamic nucleus neurons. The excitability of PVT neurons is also modulated by activation of neurotransmitter receptors associated with afferent pathways to PVT and other thalamic midline nuclei. We report on receptor-mediated actions of GABA, glutamate, monoamines and several neuropeptides: arginine vasopressin, gastrin-releasing peptide, thyrotropin releasing hormone and the orexins (hypocretins). This review represents an initial survey of intrinsic and transmitter-sensitive ionic conductances that are deemed to be unique to this population of midline thalamic neurons, information that is fundamental to an appreciation of the role these thalamic neurons may play in normal central nervous system (CNS) physiology and in CNS disorders that involve the dorsomedial thalamus.
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Affiliation(s)
- Miloslav Kolaj
- Neuroscience Program and Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa Ottawa, ON, Canada
| | - Li Zhang
- Neuroscience Program and Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa Ottawa, ON, Canada
| | - Michael L H J Hermes
- Neuroscience Program and Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa Ottawa, ON, Canada
| | - Leo P Renaud
- Neuroscience Program and Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa Ottawa, ON, Canada
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83
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Xia T, Zhang Q, Xiao Y, Wang C, Yu J, Liu H, Liu B, Zhang Y, Chen S, Liu Y, Chen Y, Guo F. CREB/TRH pathway in the central nervous system regulates energy expenditure in response to deprivation of an essential amino acid. Int J Obes (Lond) 2014; 39:105-13. [PMID: 24732144 DOI: 10.1038/ijo.2014.65] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 03/18/2014] [Accepted: 04/06/2014] [Indexed: 01/17/2023]
Abstract
BACKGROUND In the central nervous system (CNS), thyrotropin-releasing hormone (TRH) has an important role in regulating energy balance. We previously showed that dietary deprivation of leucine in mice increases energy expenditure through CNS-dependent regulation. However, the involvement of central TRH in this regulation has not been reported. METHODS Male C57J/B6 mice were maintained on a control or leucine-deficient diet for 7 days. Leucine-deprived mice were either third intracerebroventricular (i.c.v.) injected with a TRH antibody followed by intraperitoneal (i.p.) injection of triiodothyronine (T3) or i.c.v. administrated with an adenovirus of shCREB (cAMP-response element binding protein) followed by i.c.v. injection of TRH. Food intake and body weight were monitored daily. Oxygen consumption, physical activity and rectal temperature were assessed after the treatment. After being killed, the hypothalamus and the brown adipose tissue were collected and the expression of related genes and proteins related was analyzed. In other experiments, control or leucine-deficient medium incubated primary cultured neurons were either infected with adenovirus-mediated short hairpin RNA targeting extracellular signal-regulated kinases 1 and 2 (Ad-shERK1/2) or transfected with plasmid-overexpressing protein phosphatase 1 regulatory subunit 3C (PPP1R3C). RESULTS I.c.v. administration of anti-TRH antibodies significantly reduced leucine deprivation-stimulated energy expenditure. Furthermore, the effects of i.c.v. TRH antibodies were reversed by i.p. injection of T3 during leucine deprivation. Moreover, i.c.v. injection of Ad-shCREB (adenovirus-mediated short hairpin RNA targeting CREB) significantly suppressed leucine deprivation-stimulated energy expenditure via modulation of TRH expression. Lastly, TRH expression was regulated by CREB, which was phosphorylated by ERK1/2 and dephosphorylated by PPP1R3C-containing protein Ser/Thr phosphatase type 1 (PP1) under leucine deprivation in vitro. CONCLUSIONS Our data indicate a novel role for TRH in regulating energy expenditure via T3 during leucine deprivation. Furthermore, our findings reveal that TRH expression is activated by CREB, which is phosphorylated by ERK1/2 and dephosphorylated by PPP1R3C-containing PP1. Collectively, our studies provide novel insights into the regulation of energy homeostasis by the CNS in response to an essential amino-acid deprivation.
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Affiliation(s)
- T Xia
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Q Zhang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Y Xiao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - C Wang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - J Yu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - H Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - B Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Y Zhang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - S Chen
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Y Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Y Chen
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - F Guo
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, The Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
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84
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Fekete C, Lechan RM. Central regulation of hypothalamic-pituitary-thyroid axis under physiological and pathophysiological conditions. Endocr Rev 2014; 35:159-94. [PMID: 24423980 PMCID: PMC3963261 DOI: 10.1210/er.2013-1087] [Citation(s) in RCA: 185] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Accepted: 11/05/2013] [Indexed: 12/18/2022]
Abstract
TRH is a tripeptide amide that functions as a neurotransmitter but also serves as a neurohormone that has a critical role in the central regulation of the hypothalamic-pituitary-thyroid axis. Hypophysiotropic TRH neurons involved in this neuroendocrine process are located in the hypothalamic paraventricular nucleus and secrete TRH into the pericapillary space of the external zone of the median eminence for conveyance to anterior pituitary thyrotrophs. Under basal conditions, the activity of hypophysiotropic TRH neurons is regulated by the negative feedback effects of thyroid hormone to ensure stable, circulating, thyroid hormone concentrations, a mechanism that involves complex interactions between hypophysiotropic TRH neurons and the vascular system, cerebrospinal fluid, and specialized glial cells called tanycytes. Hypophysiotropic TRH neurons also integrate other humoral and neuronal inputs that can alter the setpoint for negative feedback regulation by thyroid hormone. This mechanism facilitates adaptation of the organism to changing environmental conditions, including the shortage of food and a cold environment. The thyroid axis is also affected by other adverse conditions such as infection, but the central mechanisms mediating suppression of hypophysiotropic TRH may be pathophysiological. In this review, we discuss current knowledge about the mechanisms that contribute to the regulation of hypophysiotropic TRH neurons under physiological and pathophysiological conditions.
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Affiliation(s)
- Csaba Fekete
- Department of Endocrine Neurobiology (C.F.), Institute of Experimental Medicine, Hungarian Academy of Sciences, 1083 Budapest, Hungary; Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism (C.F., R.M.L.), Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts 02111; and Department of Neuroscience (R.M.L.), Tufts University School of Medicine, Boston, Massachusetts 02111
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85
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McAninch EA, Bianco AC. Thyroid hormone signaling in energy homeostasis and energy metabolism. Ann N Y Acad Sci 2014; 1311:77-87. [PMID: 24697152 DOI: 10.1111/nyas.12374] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The thyroid hormone (TH) plays a significant role in diverse processes related to growth, development, differentiation, and metabolism. TH signaling modulates energy expenditure through both central and peripheral pathways. At the cellular level, the TH exerts its effects after concerted mechanisms facilitate binding to the TH receptor. In the hypothalamus, signals from a range of metabolic pathways, including appetite, temperature, afferent stimuli via the autonomic nervous system, availability of energy substrates, hormones, and other biologically active molecules, converge to maintain plasma TH at the appropriate level to preserve energy homeostasis. At the tissue level, TH actions on metabolism are controlled by transmembrane transporters, deiodinases, and TH receptors. In the modern environment, humans are susceptible to an energy surplus, which has resulted in an obesity epidemic and, thus, understanding the contribution of the TH to cellular and organism metabolism is increasingly relevant.
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Affiliation(s)
- Elizabeth A McAninch
- Division of Endocrinology, Diabetes, and Metabolism, University of Miami Miller School of Medicine, Miami, Florida
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Li JY, Chai B, Zhang W, Fritze DM, Zhang C, Mulholland MW. LGR4 and its ligands, R-spondin 1 and R-spondin 3, regulate food intake in the hypothalamus of male rats. Endocrinology 2014; 155:429-40. [PMID: 24280058 PMCID: PMC3891940 DOI: 10.1210/en.2013-1550] [Citation(s) in RCA: 16] [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
The hypothalamus plays a key role in the regulation of feeding behavior. Several hypothalamic nuclei, including the arcuate nucleus (ARC), paraventricular nucleus, and ventromedial nucleus of the hypothalamus (VMH), are involved in energy homeostasis. Analysis of microarray data derived from ARC revealed that leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4) is highly expressed. LGR4, LGR5, and LGR6 form a subfamily of closely related receptors. Recently, R-spondin (Rspo) family proteins were identified as ligands of the LGR4 subfamily. In the present study, we investigated the distribution and function of LGR4-LGR6 and Rspos (1-4) in the brain of male rat. In situ hybridization showed that LGR4 is expressed in the ARC, VMH, and median eminence of the hypothalamus. LGR4 colocalizes with neuropeptide Y, proopiomelanocortin, and brain-derived neurotrophic factor neurons. LGR5 is not detectable with in situ hybridization; LGR6 is only expressed in the epithelial lining of the lower portion of the third ventricle and median eminence. Rspo1 is expressed in the VMH and down-regulated with fasting. Rspo3 is expressed in the paraventricular nucleus and also down-regulated with fasting. Rspos 1 and 3 colocalize with the neuronal marker HuD, indicating that they are expressed by neurons. Injection of Rspo1 or Rspo3 into the third brain ventricle inhibited food intake. Rspo1 decreased neuropeptide Y and increased proopiomelanocortin expression in the ARC. Rspo1 and Rspo3 mRNA is up-regulated by insulin. These data indicate that Rspo1 and Rspo3 and their receptor LGR4 form novel circuits in the brain to regulate energy homeostasis.
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Affiliation(s)
- Ji-Yao Li
- Department of Surgery, University of Michigan, Ann Arbor, Michigan 48109-0346
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87
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Fliers E, Boelen A, van Trotsenburg A. Central regulation of the hypothalamo–pituitary–thyroid (HPT) axis. CLINICAL NEUROENDOCRINOLOGY 2014; 124:127-38. [DOI: 10.1016/b978-0-444-59602-4.00009-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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88
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Ramos CF, Zamoner A. Thyroid hormone and leptin in the testis. Front Endocrinol (Lausanne) 2014; 5:198. [PMID: 25505448 PMCID: PMC4243692 DOI: 10.3389/fendo.2014.00198] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 11/10/2014] [Indexed: 12/18/2022] Open
Abstract
Leptin is primarily expressed in white adipose tissue; however, it is expressed in the hypothalamus and reproductive tissues as well. Leptin acts by activating the leptin receptors (Ob-Rs). Additionally, the regulation of several neuroendocrine and reproductive functions, including the inhibition of glucocorticoids and enhancement of thyroxine and sex hormone concentrations in human beings and mice are leptin functions. It has been suggested that thyroid hormones (TH) could directly regulate leptin expression. Additionally, hypothyroidism compromises the intracellular integration of leptin signaling specifically in the arcuate nucleus. Two TH receptor isoforms are expressed in the testis, TRa and TRb, with TRa being the predominant one that is present in all stages of development. The effects of TH involve the proliferation and differentiation of Sertoli and Leydig cells during development, spermatogenesis, and steroidogenesis. In this context, TH disorders are associated with sexual dysfunction. An endocrine and/or direct paracrine effect of leptin on the gonads inhibits testosterone production in Leydig cells. Further studies are necessary to clarify the effects of both hormones in the testis during hypothyroidism. The goal of this review is to highlight the current knowledge regarding leptin and TH in the testis.
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Affiliation(s)
- Cristiane Fonte Ramos
- Laboratory of Morphometry, Metabolism and Cardiovascular Disease, Department of Anatomy, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro, Brazil
- *Correspondence: Cristiane Fonte Ramos, Laboratório de Morfometria, Metabolismo e Doença Cardiovascular, Centro Biomédico, Instituto de Biologia, Universidade do Estado do Rio de Janeiro. Av 28 de Setembro 87 fds, Rio de Janeiro 20551-030, RJ, Brazil e-mail:
| | - Ariane Zamoner
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil
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89
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Abstract
The second-generation antipsychotic drug olanzapine has become a widely prescribed drug in the treatment of schizophrenia and bipolar disorder. Unfortunately, its therapeutic benefits are partly outweighed by significant weight gain and other metabolic side effects, which increase the risk for diabetes and cardiovascular disease. Because olanzapine remains superior to other antipsychotic drugs that show less weight gain liability, insight into the mechanisms responsible for olanzapine-induced weight gain is crucial if it is to be effectively addressed. Over the past few decades, several groups have investigated the effects of olanzapine on energy balance using rat models. Unfortunately, results from different studies have not always been consistent and it remains to be determined which paradigms should be used in order to model olanzapine-induced weight gain most accurately. This review summarizes the effects of olanzapine on energy balance observed in different rat models and discusses some of the factors that appear to contribute to the inconsistencies in observed effects. In addition it compares the effects reported in rats with clinical findings to determine the predictive validity of different paradigms.
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90
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Bianco AC, Anderson G, Forrest D, Galton VA, Gereben B, Kim BW, Kopp PA, Liao XH, Obregon MJ, Peeters RP, Refetoff S, Sharlin DS, Simonides WS, Weiss RE, Williams GR. American Thyroid Association Guide to investigating thyroid hormone economy and action in rodent and cell models. Thyroid 2014; 24:88-168. [PMID: 24001133 PMCID: PMC3887458 DOI: 10.1089/thy.2013.0109] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND An in-depth understanding of the fundamental principles that regulate thyroid hormone homeostasis is critical for the development of new diagnostic and treatment approaches for patients with thyroid disease. SUMMARY Important clinical practices in use today for the treatment of patients with hypothyroidism, hyperthyroidism, or thyroid cancer are the result of laboratory discoveries made by scientists investigating the most basic aspects of thyroid structure and molecular biology. In this document, a panel of experts commissioned by the American Thyroid Association makes a series of recommendations related to the study of thyroid hormone economy and action. These recommendations are intended to promote standardization of study design, which should in turn increase the comparability and reproducibility of experimental findings. CONCLUSIONS It is expected that adherence to these recommendations by investigators in the field will facilitate progress towards a better understanding of the thyroid gland and thyroid hormone dependent processes.
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Affiliation(s)
- Antonio C. Bianco
- Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, Florida
| | - Grant Anderson
- Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, University of Minnesota Duluth, Duluth, Minnesota
| | - Douglas Forrest
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Valerie Anne Galton
- Department of Physiology and Neurobiology, Dartmouth Medical School, Lebanon, New Hampshire
| | - Balázs Gereben
- Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Brian W. Kim
- Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, Florida
| | - Peter A. Kopp
- Division of Endocrinology, Metabolism, and Molecular Medicine, and Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Xiao Hui Liao
- Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, The University of Chicago, Chicago, Illinois
| | - Maria Jesus Obregon
- Institute of Biomedical Investigation (IIB), Spanish National Research Council (CSIC) and Autonomous University of Madrid, Madrid, Spain
| | - Robin P. Peeters
- Division of Endocrinology, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Samuel Refetoff
- Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, The University of Chicago, Chicago, Illinois
| | - David S. Sharlin
- Department of Biological Sciences, Minnesota State University, Mankato, Minnesota
| | - Warner S. Simonides
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Roy E. Weiss
- Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, The University of Chicago, Chicago, Illinois
| | - Graham R. Williams
- Department of Medicine, Imperial College London, Hammersmith Campus, London, United Kingdom
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91
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Denis RGP, Joly-Amado A, Cansell C, Castel J, Martinez S, Delbes AS, Luquet S. Central orchestration of peripheral nutrient partitioning and substrate utilization: implications for the metabolic syndrome. DIABETES & METABOLISM 2013; 40:191-7. [PMID: 24332017 DOI: 10.1016/j.diabet.2013.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 11/11/2013] [Indexed: 12/24/2022]
Abstract
Energy homoeostasis is maintained through a complex interplay of nutrient intake and energy expenditure. The central nervous system is an essential component of this regulation, as it integrates circulating signals of hunger and satiety to develop adaptive responses at the behavioural and metabolic levels, while the hypothalamus is regarded as a particularly crucial structure in the brain in terms of energy homoeostasis. The arcuate nucleus (ARC) of the hypothalamus contains at least two intermingled neuronal populations: the neurons that produce neuropeptide Y (NPY); and the Agouti-related protein (AgRP) produced by AgRP/NPY neurons situated below the third ventricle in close proximity to proopiomelanocortin (POMC)-producing neurons. POMC neurons exert their catabolic and anorectic actions by releasing α-melanocyte-stimulating hormone (α-MSH), while AgRP neurons oppose this action by exerting tonic GABAergic inhibition of POMC neurons and releasing the melanocortin receptor inverse agonist AgRP. The release of neurotransmitters and neuropeptides by second-order AgRP neurons appears to take place on a multiple time scale, thereby allowing neuromodulation of preganglionic neuronal activity and subsequent control of nutrient partitioning - in other words, the coordinated regulation of conversion, storage and utilization of carbohydrates vs. lipids. This suggests that the function of AgRP neurons extends beyond the strict regulation of feeding to the regulation of efferent organ activity, such that AgRP neurons may now be viewed as an important bridge between central detection of nutrient availability and peripheral nutrient partitioning, thus providing a mechanistic link between obesity and obesity-related disorders.
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Affiliation(s)
- R G P Denis
- Unité « biologie fonctionnelle et adaptative » (BFA), université Paris Diderot-Paris 7, CNRS EAC 4413, 4, rue Marie-Andrée-Lagroua-Weill-Hallé, bâtiment Buffon, case courrier 7126, 75205 Paris cedex 13, France
| | - A Joly-Amado
- Unité « biologie fonctionnelle et adaptative » (BFA), université Paris Diderot-Paris 7, CNRS EAC 4413, 4, rue Marie-Andrée-Lagroua-Weill-Hallé, bâtiment Buffon, case courrier 7126, 75205 Paris cedex 13, France
| | - C Cansell
- Unité « biologie fonctionnelle et adaptative » (BFA), université Paris Diderot-Paris 7, CNRS EAC 4413, 4, rue Marie-Andrée-Lagroua-Weill-Hallé, bâtiment Buffon, case courrier 7126, 75205 Paris cedex 13, France
| | - J Castel
- Unité « biologie fonctionnelle et adaptative » (BFA), université Paris Diderot-Paris 7, CNRS EAC 4413, 4, rue Marie-Andrée-Lagroua-Weill-Hallé, bâtiment Buffon, case courrier 7126, 75205 Paris cedex 13, France; Centre national de la recherche scientifique-CNRS, EAC 4413, 75205 Paris, France
| | - S Martinez
- Unité « biologie fonctionnelle et adaptative » (BFA), université Paris Diderot-Paris 7, CNRS EAC 4413, 4, rue Marie-Andrée-Lagroua-Weill-Hallé, bâtiment Buffon, case courrier 7126, 75205 Paris cedex 13, France; Centre national de la recherche scientifique-CNRS, EAC 4413, 75205 Paris, France
| | - A S Delbes
- Unité « biologie fonctionnelle et adaptative » (BFA), université Paris Diderot-Paris 7, CNRS EAC 4413, 4, rue Marie-Andrée-Lagroua-Weill-Hallé, bâtiment Buffon, case courrier 7126, 75205 Paris cedex 13, France; Centre national de la recherche scientifique-CNRS, EAC 4413, 75205 Paris, France
| | - S Luquet
- Unité « biologie fonctionnelle et adaptative » (BFA), université Paris Diderot-Paris 7, CNRS EAC 4413, 4, rue Marie-Andrée-Lagroua-Weill-Hallé, bâtiment Buffon, case courrier 7126, 75205 Paris cedex 13, France; Centre national de la recherche scientifique-CNRS, EAC 4413, 75205 Paris, France.
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92
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Abstract
Body weight is determined by a balance between food intake and energy expenditure. Multiple neural circuits in the brain have evolved to process information about food, food-related cues and food consumption to control feeding behavior. Numerous gastrointestinal endocrine cells produce and secrete satiety hormones in response to food consumption and digestion. These hormones suppress hunger and promote satiation and satiety mainly through hindbrain circuits, thus governing meal-by-meal eating behavior. In contrast, the hypothalamus integrates adiposity signals to regulate long-term energy balance and body weight. Distinct hypothalamic areas and various orexigenic and anorexigenic neurons have been identified to homeostatically regulate food intake. The hypothalamic circuits regulate food intake in part by modulating the sensitivity of the hindbrain to short-term satiety hormones. The hedonic and incentive properties of foods and food-related cues are processed by the corticolimbic reward circuits. The mesolimbic dopamine system encodes subjective "liking" and "wanting" of palatable foods, which is subjected to modulation by the hindbrain and the hypothalamic homeostatic circuits and by satiety and adiposity hormones. Satiety and adiposity hormones also promote energy expenditure by stimulating brown adipose tissue (BAT) activity. They stimulate BAT thermogenesis mainly by increasing the sympathetic outflow to BAT. Many defects in satiety and/or adiposity hormone signaling and in the hindbrain and the hypothalamic circuits have been described and are believed to contribute to the pathogenesis of energy imbalance and obesity.
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Affiliation(s)
- Liangyou Rui
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48109-0622, USA,
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93
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Abstract
Thyroid hormones are extremely important for metabolism, development, and growth during the lifetime. The hypothalamo-pituitary-thyroid axis is precisely regulated for these purposes. Much of our knowledge of this hormonal axis is derived from experiments in animals and mutations in man. This review examines the hypothalamo-pituitary-thyroid axis particularly in relation to the regulated 24-hour serum TSH concentration profiles in physiological and pathophysiological conditions, including obesity, primary hypothyroidism, pituitary diseases, psychiatric disorders, and selected neurological diseases. Diurnal TSH rhythms can be analyzed with novel and precise techniques, eg, operator-independent deconvolution and approximate entropy. These approaches provide indirect insight in the regulatory components in pathophysiological conditions.
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Affiliation(s)
- Ferdinand Roelfsema
- Leiden University Medical Center, Department of Endocrinology and Metabolic Diseases, PO Box 9600, 2300 RC Leiden, The Netherlands.
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94
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Lee SJ, Kirigiti M, Lindsley SR, Loche A, Madden CJ, Morrison SF, Smith MS, Grove KL. Efferent projections of neuropeptide Y-expressing neurons of the dorsomedial hypothalamus in chronic hyperphagic models. J Comp Neurol 2013; 521:1891-914. [PMID: 23172177 DOI: 10.1002/cne.23265] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 08/15/2012] [Accepted: 11/06/2012] [Indexed: 12/31/2022]
Abstract
The dorsomedial hypothalamus (DMH) has long been implicated in feeding behavior and thermogenesis. The DMH contains orexigenic neuropeptide Y (NPY) neurons, but the role of these neurons in the control of energy homeostasis is not well understood. NPY expression in the DMH is low under normal conditions in adult rodents but is significantly increased during chronic hyperphagic conditions such as lactation and diet-induced obesity (DIO). To understand better the role of DMH-NPY neurons, we characterized the efferent projections of DMH-NPY neurons using the anterograde tracer biotinylated dextran amine (BDA) in lactating rats and DIO mice. In both models, BDA- and NPY-colabeled fibers were limited mainly to the hypothalamus, including the paraventricular nucleus of the hypothalamus (PVH), lateral hypothalamus/perifornical area (LH/PFA), and anteroventral periventricular nucleus (AVPV). Specifically in lactating rats, BDA-and NPY-colabeled axonal swellings were in close apposition to cocaine- and amphetamine-regulated transcript (CART)-expressing neurons in the PVH and AVPV. Although the DMH neurons project to the rostral raphe pallidus (rRPa), these projections did not contain NPY immunoreactivity in either the lactating rat or the DIO mouse. Instead, the majority of BDA-labeled fibers in the rRPa were orexin positive. Furthermore, DMH-NPY projections were not observed within the nucleus of the solitary tract (NTS), another brainstem site critical for the regulation of sympathetic outflow. The present data suggest that NPY expression in the DMH during chronic hyperphagic conditions plays important roles in feeding behavior and thermogenesis by modulating neuronal functions within the hypothalamus, but not in the brainstem.
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Affiliation(s)
- Shin J Lee
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon 97006, USA
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95
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Fernandes AM, Beddows E, Filippi A, Driever W. Orthopedia transcription factor otpa and otpb paralogous genes function during dopaminergic and neuroendocrine cell specification in larval zebrafish. PLoS One 2013; 8:e75002. [PMID: 24073233 PMCID: PMC3779234 DOI: 10.1371/journal.pone.0075002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 08/08/2013] [Indexed: 11/29/2022] Open
Abstract
The homeodomain transcription factor Orthopedia (Otp) is an important regulator for specification of defined subsets of neuroendocrine cells and dopaminergic neurons in vertebrates. In zebrafish, two paralogous otp genes, otpa and otpb, are present in the genome. Neither complete loss of Otp activity nor differential contributions of Otpa and Otpb to specification of defined neuronal populations have been analyzed in detail. We characterized zebrafish embryos and early larvae mutant for null alleles of otpa, otpb, or both genes to determine their individual contributions to the specification of th expressing dopaminergic neuronal populations as well as of crh, oxt, avp, trh or sst1.1 expressing neuroendocrine cells. otpa mutant larvae show an almost complete reduction of ventral diencephalic dopaminergic neurons, as reported previously. A small reduction in the number of trh cells in the preoptic region is detectable in otpa mutants, but no significant loss of crh, oxt and avp preoptic neuroendocrine cells. otpb single mutant larvae do not display a reduction in dopaminergic neurons or neuroendocrine cells in the otp expressing regions. In contrast, in otpa and otpb double mutant larvae specific groups of dopaminergic neurons as well as of crh, oxt, avp, trh and sst1.1-expressing neuroendocrine cells are completely lost. These observations suggest that the requirement for otpa and otpb function during development of the larval diencephalon is partially redundant. During evolutionary diversification of the paralogous otp genes, otpa maintained the prominent role in ventral diencephalic dopaminergic and neuroendocrine cell specification and is capable of partially compensating otpb loss of function. In addition, we identified a role of Otp in the development of a domain of somatostatin1-expressing cells in the rostral hindbrain, a region with strong otp expression but so far uncharacterized Otp function. Otp may thus be crucial for defined neuronal cell types also in the hindbrain.
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Affiliation(s)
- António M. Fernandes
- Developmental Biology Unit, Faculty of Biology, and BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Erin Beddows
- Developmental Biology Unit, Faculty of Biology, and BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Alida Filippi
- Developmental Biology Unit, Faculty of Biology, and BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Wolfgang Driever
- Developmental Biology Unit, Faculty of Biology, and BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
- * E-mail:
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96
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Ganella DE, Ma S, Gundlach AL. Relaxin-3/RXFP3 Signaling and Neuroendocrine Function - A Perspective on Extrinsic Hypothalamic Control. Front Endocrinol (Lausanne) 2013; 4:128. [PMID: 24065955 PMCID: PMC3776160 DOI: 10.3389/fendo.2013.00128] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 09/02/2013] [Indexed: 01/08/2023] Open
Abstract
Complex neural circuits within the hypothalamus that govern essential autonomic processes and associated behaviors signal using amino acid and monoamine transmitters and a variety of neuropeptide (hormone) modulators, often via G-protein coupled receptors (GPCRs) and associated cellular pathways. Relaxin-3 is a recently identified neuropeptide that is highly conserved throughout evolution. Neurons expressing relaxin-3 are located in the brainstem, but broadly innervate the entire limbic system including the hypothalamus. Extensive anatomical data in rodents and non-human primate, and recent regulatory and functional data, suggest relaxin-3 signaling via its cognate GPCR, RXFP3, has a broad range of effects on neuroendocrine function associated with stress responses, feeding and metabolism, motivation and reward, and possibly sexual behavior and reproduction. Therefore, this article aims to highlight the growing appreciation of the relaxin-3/RXFP3 system as an important "extrinsic" regulator of the neuroendocrine axis by reviewing its neuroanatomy and its putative roles in arousal-, stress-, and feeding-related behaviors and links to associated neural substrates and signaling networks. Current evidence identifies RXFP3 as a potential therapeutic target for treatment of neuroendocrine disorders and related behavioral dysfunction.
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Affiliation(s)
- Despina E. Ganella
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Sherie Ma
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Andrew L. Gundlach
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
- Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia
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97
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Pazos P, Lima L, Casanueva FF, Diéguez C, García MC. Interleukin 6 deficiency modulates the hypothalamic expression of energy balance regulating peptides during pregnancy in mice. PLoS One 2013; 8:e72339. [PMID: 24015235 PMCID: PMC3756067 DOI: 10.1371/journal.pone.0072339] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 07/08/2013] [Indexed: 01/03/2023] Open
Abstract
Pregnancy is associated with hyperphagia, increased adiposity and multiple neuroendocrine adaptations. Maternal adipose tissue secretes rising amounts of interleukin 6 (IL6), which acts peripherally modulating metabolic function and centrally increasing energy expenditure and reducing body fat. To explore the role of IL6 in the central mechanisms governing dam's energy homeostasis, early, mid and late pregnant (gestational days 7, 13 and 18) wild-type (WT) and Il6 knockout mice (Il6-KO) were compared with virgin controls at diestrus. Food intake, body weight and composition as well as indirect calorimetry measurements were performed in vivo. Anabolic and orexigenic peptides: neuropeptide Y (Npy) and agouti-related peptide (Agrp); and catabolic and anorectic neuropeptides: proopiomelanocortin (Pomc), corticotrophin and thyrotropin-releasing hormone (Crh and Trh) mRNA levels were determined by in situ hybridization. Real time-PCR and western-blot were used for additional tissue gene expression and protein studies. Non-pregnant Il6-KO mice were leaner than WT mice due to a decrease in fat but not in lean body mass. Pregnant Il6-KO mice had higher fat accretion despite similar body weight gain than WT controls. A decreased fat utilization in absence of Il6 might explain this effect, as shown by increased respiratory exchange ratio (RER) in virgin Il6-KO mice. Il6 mRNA levels were markedly enhanced in adipose tissue but reduced in hypothalamus of mid and late pregnant WT mice. Trh expression was also stimulated at gestational day 13 and lack of Il6 blunted this effect. Conversely, in late pregnant mice lessened hypothalamic Il6 receptor alpha (Il6ra), Pomc and Crh mRNA were observed. Il6 deficiency during this stage up-regulated Npy and Agrp expression, while restoring Pomc mRNA levels to virgin values. Together these results demonstrate that IL6/IL6Ra system modulates Npy/Agrp, Pomc and Trh expression during mouse pregnancy, supporting a role of IL6 in the central regulation of body fat in this physiological state.
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Affiliation(s)
- Patricia Pazos
- Department of Physiology/Research Center of Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, Santiago de Compostela, Spain
- Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain
- CIBER Fisiopatología Obesidad y Nutrición (CB06/03), Instituto de Salud Carlos III (ISCIII), Ministerio de Economía y Competitividad (MINECO), Santiago de Compostela, Spain
| | - Luis Lima
- Department of Physiology/Research Center of Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, Santiago de Compostela, Spain
- Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain
| | - Felipe F. Casanueva
- Department of Physiology/Research Center of Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, Santiago de Compostela, Spain
- Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain
- CIBER Fisiopatología Obesidad y Nutrición (CB06/03), Instituto de Salud Carlos III (ISCIII), Ministerio de Economía y Competitividad (MINECO), Santiago de Compostela, Spain
- Laboratorio de Endocrinología Molecular y Celular, Complexo Hospitalario Universitario de Santiago (CHUS), Santiago de Compostela, Spain
| | - Carlos Diéguez
- Department of Physiology/Research Center of Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, Santiago de Compostela, Spain
- Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain
- CIBER Fisiopatología Obesidad y Nutrición (CB06/03), Instituto de Salud Carlos III (ISCIII), Ministerio de Economía y Competitividad (MINECO), Santiago de Compostela, Spain
| | - María C. García
- Department of Physiology/Research Center of Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, Santiago de Compostela, Spain
- Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain
- CIBER Fisiopatología Obesidad y Nutrición (CB06/03), Instituto de Salud Carlos III (ISCIII), Ministerio de Economía y Competitividad (MINECO), Santiago de Compostela, Spain
- * E-mail:
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Guzel S, Seven A, Guzel EC, Buyuk B, Celebi A, Aydemir B. Visfatin, Leptin, and TNF-α: Interrelated Adipokines in Insulin-Resistant Clinical and Subclinical Hypothyroidism. Endocr Res 2013; 38:184-194. [PMID: 23324036 DOI: 10.3109/07435800.2012.760588] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE This study is designed to evaluate the interrelationships among adipokines-visfatin, leptin, and tumor necrosis factor-α (TNF-α)- and insulin resistance (IR) in overt (n = 40) and subclinic hypothyroid (n = 25) patients and compare our findings with sex and body mass index-matched healthy controls (n = 25). METHODS Serum visfatin, leptin, and TNF-α levels were measured by enzyme-linked immunosorbent assay and C-reactive protein by immunoturbidimetry. Thyroid status (TSH, FT3, FT4) and lipid status (triglyceride, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, total cholesterol) parameters were measured. IR was determined by homeostatic model assessment (HOMA-IR) and McAuley (McA) indices. RESULTS HOMA-IR (p < 0.05) and McA indices (p < 0.01) revealed the presence of IR in overt hypothyroid patients. C-reactive protein, TNF-α, leptin, and visfatin levels were significantly higher (p < 0.01, p < 0.01, p < 0.001, and p < 0.001) in overt hypothyroid patients than euthyroid control group. Subclinic hypothyroid patients were observed to have significantly higher leptin and visfatin levels (p < 0.05) than euthyroid control group. In overt hypothyroid patients, we found plasma visfatin to be significantly positively correlated with HOMA-IR index (r = 0.336, p < 0.05) and body mass index (r = 0.445, p < 0.01) and negatively correlated with McA index (r = -0.574, p < 0.01). CONCLUSION This study demonstrates the presence of IR in overt hypothyroid patients by HOMA and McA indices. Increased levels of visfatin, leptin, and TNF-α in overt and subclinic hypothyroid patients and the correlations among these adipokines highlighten their crucial role in the IR-associated disorders.
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Affiliation(s)
- Savas Guzel
- a Medical Faculty, Department of Biochemistry, Namik Kemal University , Tekirdag, Turkey
| | - Arzu Seven
- b Cerrahpasa Medical Faculty, Department of Biochemistry, Istanbul University , Istanbul, Turkey
| | - Eda Celik Guzel
- c Medical Faculty, Department of Family Physcian, Namik Kemal University , Tekirdag, Turkey
| | - Banu Buyuk
- d Department of Internal Medicine, Taksim Training and Research Hospital , Istanbul, Turkey
| | - Aslan Celebi
- d Department of Internal Medicine, Taksim Training and Research Hospital , Istanbul, Turkey
| | - Birsen Aydemir
- e Medical Faculty, Department of Biophysic, Sakarya University , Sakarya, Turkey
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LHX2 is necessary for the maintenance of optic identity and for the progression of optic morphogenesis. J Neurosci 2013; 33:6877-84. [PMID: 23595746 DOI: 10.1523/jneurosci.4216-12.2013] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Eye formation is regulated by a complex network of eye field transcription factors (EFTFs), including LIM-homeodomain gene LHX2. We disrupted LHX2 function at different stages during this process using a conditional knock-out strategy in mice. We find that LHX2 function is required in an ongoing fashion to maintain optic identity across multiple stages, from the formation of the optic vesicle to the differentiation of the neuroretina. At each stage, loss of Lhx2 led to upregulation of a set of molecular markers that are normally expressed in the thalamic eminence and in the anterodorsal hypothalamus in a portion of the optic vesicle or retina. Furthermore, the longer LHX2 function was maintained, the further optic morphogenesis progressed. Early loss of function caused profound mispatterning of the entire telencephalic-optic-hypothalamic field, such that the optic vesicle became mispositioned and appeared to arise from the diencephalic-telencephalic boundary. At subsequent stages, loss of Lhx2 did not affect optic vesicle position but caused arrest of optic cup formation. If Lhx2 was selectively disrupted in the neuroretina from E11.5, the neuroretina showed gross dysmorphology along with aberrant expression of markers specific to the thalamic eminence and anterodorsal hypothalamus. Our findings indicate a continual requirement for LHX2 throughout the early stages of optic development, not only to maintain optic identity by suppressing alternative fates but also to mediate multiple steps of optic morphogenesis. These findings provide new insight into the anophthalmic phenotype of the Lhx2 mutant and reveal novel roles for this transcription factor in eye development.
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Utrilla JC, Morillo-Bernal J, Gordillo-Martínez F, García-Marín R, Herrera JL, Fernández-Santos JM, Díaz-Parrado E, Garnacho C, De Miguel M, Martín-Lacave I. Expression of hypothalamic regulatory peptides in thyroid C cells of different mammals. Gen Comp Endocrinol 2013; 187:6-14. [PMID: 23524276 DOI: 10.1016/j.ygcen.2013.02.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 10/27/2022]
Abstract
Besides intervening in calcium homeostasis by means of calcitonin, C cells are also implicated in the synthesis of an increasing number of regulatory peptides that could exert a paracrine regulation on the neighbouring follicular cells. Among the latest peptides reported in C cells, there are several characteristic hypothalamic peptides, such as TRH, CART, and ghrelin, which are mainly involved in the regulation of the metabolism at hypothalamic-pituitary-thyroid axis. The main aim of the present work has been to study the synthesis of the referred hypothalamic peptides by normal and neoplastic C cells of different mammals as well as in C-cell lines of both rat (CA-77, 6-23) and human (TT) origins in order to elucidate whether this is a fact in this kind of vertebrates. With that objective, we have applied the immunoperoxidase technique to analyze the presence of TRH, CART, ghrelin, and somatostatin in thyroid tissues of different species, and immunofluorescence to study those same peptides in C-cell cultures. Furthermore, we have investigated their expression at mRNA level by RT-PCR analysis. Our results demonstrate immunocolocalization of CART, ghrelin, somatostatin and TRH with calcitonin in normal C cells of different mammals, as well as in rat and human neoplastic C cells. We also confirm the expression of those peptides in rat and human C-cell lines by RT-PCR. Consequently, we can conclude that the synthesis of those peptides by C cells is a general event characteristic of the thyroid gland in mammals.
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Affiliation(s)
- José C Utrilla
- Dpt. Cytology and Histology, School of Medicine, University of Seville, Spain
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