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Abstract
In all vertebrates, the thyroid axis is an endocrine feedback system that affects growth, differentiation, and reproduction, by sensing and translating central and peripheral signals to maintain homeostasis and a proper thyroidal set-point. Fish, the most diverse group of vertebrates, rely on this system for somatic growth, metamorphosis, reproductive events, and the ability to tolerate changing environments. The vast majority of the research on the thyroid axis pertains to mammals, in particular rodents, and although some progress has been made to understand the role of this endocrine axis in non-mammalian vertebrates, including amphibians and teleost fish, major gaps in our knowledge remain regarding other groups, such as elasmobranchs and cyclostomes. In this review, we discuss the roles of the thyroid axis in fish and its contributions to growth and development, metamorphosis, reproduction, osmoregulation, as well as feeding and nutrient metabolism. We also discuss how thyroid hormones have been/can be used in aquaculture, and potential threats to the thyroid system in this regard.
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Zak MA, Regish AM, McCormick SD, Manzon RG. Exogenous thyroid hormones regulate the activity of citrate synthase and cytochrome c oxidase in warm- but not cold-acclimated lake whitefish (Coregonus clupeaformis). Gen Comp Endocrinol 2017; 247:215-222. [PMID: 28212894 DOI: 10.1016/j.ygcen.2017.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 02/10/2017] [Accepted: 02/12/2017] [Indexed: 11/22/2022]
Abstract
Thermal acclimation is known to elicit metabolic adjustments in ectotherms, but the cellular mechanisms and endocrine control of these shifts have not been fully elucidated. Here we examined the relationship between thermal acclimation, thyroid hormones and oxidative metabolism in juvenile lake whitefish. Impacts of thermal acclimation above (19°C) or below (8°C) the thermal optimum (13°C) and exposure to exogenous thyroid hormone (60µg T4/g body weight) were assessed by quantifying citrate synthase and cytochrome c oxidase activities in liver, red muscle, white muscle and heart. Warm acclimation decreased citrate synthase activity in liver and elevated both citrate synthase and cytochrome c oxidase activities in red muscle. In contrast, induction of hyperthyroidism in warm-acclimated fish stimulated a significant increase in liver citrate synthase and heart cytochrome c oxidase activities, and a decrease in the activity of both enzymes in red muscle. No change in citrate synthase or cytochrome c oxidase activities was observed following cold acclimation in either the presence or absence of exogenous thyroid hormones. Collectively, our results indicate that thyroid hormones influence the activity of oxidative enzymes more strongly in warm-acclimated than in cold-acclimated lake whitefish, and they may play a role in mediating metabolic adjustments observed during thermal acclimation.
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Affiliation(s)
- Megan A Zak
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Amy M Regish
- U.S. Geological Survey, Leetown Science Center, Conte Anadromous Fish Research Laboratory, Turner Falls, MA 01376, USA
| | - Stephen D McCormick
- U.S. Geological Survey, Leetown Science Center, Conte Anadromous Fish Research Laboratory, Turner Falls, MA 01376, USA
| | - Richard G Manzon
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.
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Paunescu A, Zgurschi G, Soare LC, Man GM, Brinzea G, Fierascu RC, Fierascu I, Ponepal MC. The Protective Role of Thiourea on Leuciscus cephalus Exposed to Sublethal Doses of Pendigan 330EC (Pendimethalin) Herbicide. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2016; 97:203-210. [PMID: 27207230 DOI: 10.1007/s00128-016-1834-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 05/17/2016] [Indexed: 06/05/2023]
Abstract
The aim of the study was to investigate the protective role of thiourea on the physiological, hematological, biochemical and histopathological parameters of Leuciscus cephalus exposed to sublethal concentration of Pendigan 330 EC herbicide. The animals were divided in four experimental groups (control, animals subjected to 1 ‰ thiourea, animals subjected to 4 × 10(-4) mL/L herbicide and, respectively, animals subjected to 4 × 10(-4) mL/L herbicide and 1 ‰ thiourea). Exposure of European chub to herbicide administered in water for 2 weeks determined installation of pathological changes in the liver and gills tissues. Also, were observed a decrease in the number of white blood cells and oxygen consumption, breathing frequency, and an increase in the number of red blood cells and glycaemia values. Thiourea counteracts the toxic action, describing itself as normal liver parenchyma and normal gills in animals intoxicated with herbicide, without lesion, and a return to normal values of the studied markers.
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Affiliation(s)
- Alina Paunescu
- Department of Ecology, Faculty of Science, University of Pitesti, 2 Targu Din Vale Street, 110040, Pitesti, Romania
| | - Gabriela Zgurschi
- Department of Ecology, Faculty of Science, University of Pitesti, 2 Targu Din Vale Street, 110040, Pitesti, Romania
| | - Liliana Cristina Soare
- Department of Ecology, Faculty of Science, University of Pitesti, 2 Targu Din Vale Street, 110040, Pitesti, Romania
| | - George Mihail Man
- Department of Ecology, Faculty of Science, University of Pitesti, 2 Targu Din Vale Street, 110040, Pitesti, Romania
| | - Gheorghita Brinzea
- Department of Ecology, Faculty of Science, University of Pitesti, 2 Targu Din Vale Street, 110040, Pitesti, Romania
| | - Radu Claudiu Fierascu
- National Research and Development Institute for Chemistry and Petrochemistry - ICECHIM, 202 Spl. Independentei, Sect. 6, 060021, Bucharest, Romania
| | - Irina Fierascu
- National Research and Development Institute for Chemistry and Petrochemistry - ICECHIM, 202 Spl. Independentei, Sect. 6, 060021, Bucharest, Romania.
| | - Maria Cristina Ponepal
- Department of Ecology, Faculty of Science, University of Pitesti, 2 Targu Din Vale Street, 110040, Pitesti, Romania
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Leung LY, Woo NYS. Effects of growth hormone, insulin-like growth factor I, triiodothyronine, thyroxine, and cortisol on gene expression of carbohydrate metabolic enzymes in sea bream hepatocytes. Comp Biochem Physiol A Mol Integr Physiol 2010; 157:272-82. [PMID: 20647047 DOI: 10.1016/j.cbpa.2010.07.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 07/07/2010] [Accepted: 07/14/2010] [Indexed: 10/19/2022]
Abstract
The present study investigated the regulatory effects of growth hormone (GH), human insulin-like growth factor I (hIGF-I), thyroxine (T(4)), triiodothyronine (T(3)) and cortisol, on mRNA expression of key enzymes involved in carbohydrate metabolism, including glucokinase (GK), glucose-6-phosphatase (G6Pase), glycogen synthase (GS), glycogen phosphorylase (GP) and glucose-6-phosphate dehydrogenase (G6PDH) in hepatocytes isolated from silver sea bream. Genes encoding GK, G6Pase, GS and GP were partially cloned and characterized from silver sea bream liver and real-time PCR assays were developed for the quantification of the mRNA expression profiles of these genes in order to evaluate the potential of these carbohydrate metabolic pathways. GK mRNA level was elevated by GH and hIGF-I, implying that GH-induced stimulation of GK expression may be mediated via IGF-I. GH was found to elevate GS and G6Pase expression, but reduce G6PDH mRNA expression. However, hIGF-I did not affect mRNA levels of GS, G6Pase and G6PDH, suggesting that GH-induced modulation of GS, G6Pase and G6PDH expression levels is direct, and occurs independently of the action of IGF-I. T(3) and T(4) directly upregulated transcript abundance of GK, G6Pase, GS and GP. Cortisol significantly increased transcript amounts of G6Pase and GS but markedly decreased transcript abundance of GK and G6PDH. These changes in transcript abundance indicate that (1) the potential of glycolysis is stimulated by GH and thyroid hormones, but attenuated by cortisol, (2) gluconeogenic and glycogenic potential are augmented by GH, thyroid hormones and cortisol, (3) glycogenolytic potential is upregulated by thyroid hormones but not affected by GH or cortisol, and (4) the potential of the pentose phosphate pathway is attenuated by GH and cortisol but unaffected by thyroid hormones.
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Affiliation(s)
- L Y Leung
- Department of Biology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
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Imbert H, Arrowsmith R, Dufour S, Elie P. Relationships between locomotor behavior, morphometric characters and thyroid hormone levels give evidence of stage-dependent mechanisms in European eel upstream migration. Horm Behav 2008; 53:69-81. [PMID: 17950736 DOI: 10.1016/j.yhbeh.2007.06.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 06/20/2007] [Accepted: 06/26/2007] [Indexed: 10/22/2022]
Abstract
In order to decipher movements during freshwater eel colonization, we experimentally characterized individual locomotor behavior of two eel life history stages: elvers and yellow eels. A ramp located at the flume tank upstream side required a specific locomotor behavior to be ascended. Placing individually tagged eels in the middle of the tank three times successively tested behavioral consistency. Eels climbing the ramp on each trial were classified as "upstream climbers" whereas eels settling in the tank middle were classified as "inactive". Both stages exhibited these two opposite consistent behaviors. However, elvers were predominantly "upstream climbers" (58.1%) whereas yellow eels were predominantly "inactive" (79.6%). We measured morphometric characters and thyroid hormones to determine if upstream activity was related to body condition and thyroid status. Elver upstream climbers had higher body condition as well as higher thyroxine (T(4)) and triiodothyronine (T(3)) levels compared with inactive elvers. Yellow eel upstream climbers had lower body length as well as higher T(3) and (T(3):T(4)) ratio compared with inactive yellow eels. This indicated that the physiological release factors for eel upstream migration may be stage dependent. For elvers, high thyroid gland activity, together with high body condition, may be the physiological release factors for migration. In contrast, for yellow eels, physiological stress may be the release factor with an increase in T(4) deiodination activity in the smallest eels. Our study revealed inter-stage and intra-stage locomotor behavior plasticity and suggested stage-dependent opposite impacts of physiological condition on eel upstream migration.
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Affiliation(s)
- Hélène Imbert
- Cemagref, Unité Ecosystèmes Estuariens et Poissons Migrateurs Amphihalins (EPBX), 50 avenue de Verdun, 33612 Cestas cedex, France.
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Edeline E, Bardonnet A, Bolliet V, Dufour S, Elie P. Endocrine control of Anguilla anguilla glass eel dispersal: effect of thyroid hormones on locomotor activity and rheotactic behavior. Horm Behav 2005; 48:53-63. [PMID: 15919385 DOI: 10.1016/j.yhbeh.2005.02.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2004] [Revised: 02/01/2005] [Accepted: 02/01/2005] [Indexed: 10/25/2022]
Abstract
Dispersal, one of the most important processes in population ecology, is an issue linking physiological and behavioral features. However, the endocrine control of animal dispersal remains poorly understood. Here, we tested whether and how thyroid hormones may influence dispersal in glass eels of Anguilla anguilla, by testing their influence on locomotor activity and rheotactic behavior. Glass eels were caught during their estuarine migration and treated by immersion in either a l-thyroxine (T(4)) or a thiourea (TU) solution. As measured by radioimmunoassay, T(4) and TU treatments induced, respectively, increased and decreased whole-body thyroid hormone levels relative to untreated controls. We tested a total of 960 glass eels distributed into control, and T(4) and TU treatment groups, on their swimming behavior in experimental flume tanks equipped with upstream and downstream traps that allowed us to concurrently measure both the locomotor activity and the rheotactic behavior. Compared to controls, locomotor activity significantly increased among the hyperthyroid, T(4)-treated eels, but significantly decreased among the hypothyroid, TU-treated eels. The results on rheotactic behavior suggested a more complex regulatory mechanism, since TU but not T(4) treatment significantly affected rheotactic behavior. The influence of thyroid hormones on locomotor activity suggests a central role for these hormones in the regulation of mechanisms leading to the colonization of continental habitats by glass eels. Thyroid hormones are also implicated in the control of locomotor activity in mammals and migratory behavior in birds, suggesting that these hormones represent conserved, proximate mediators of dispersal in vertebrates.
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Affiliation(s)
- Eric Edeline
- Cemagref, Unité Ecosystèmes Estuariens et Poissons Migrateurs Amphihalins (EPBX), 50 avenue de Verdun, 33612 Cestas Cedex, France.
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