1
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Breves JP, Shaughnessy CA. Endocrine control of gill ionocyte function in euryhaline fishes. J Comp Physiol B 2024:10.1007/s00360-024-01555-3. [PMID: 38739280 DOI: 10.1007/s00360-024-01555-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/16/2024] [Accepted: 04/11/2024] [Indexed: 05/14/2024]
Abstract
The endocrine system is an essential regulator of the osmoregulatory organs that enable euryhaline fishes to maintain hydromineral balance in a broad range of environmental salinities. Because branchial ionocytes are the primary site for the active exchange of Na+, Cl-, and Ca2+ with the external environment, their functional regulation is inextricably linked with adaptive responses to changes in salinity. Here, we review the molecular-level processes that connect osmoregulatory hormones with branchial ion transport. We focus on how factors such as prolactin, growth hormone, cortisol, and insulin-like growth-factors operate through their cognate receptors to direct the expression of specific ion transporters/channels, Na+/K+-ATPases, tight-junction proteins, and aquaporins in ion-absorptive (freshwater-type) and ion-secretory (seawater-type) ionocytes. While these connections have historically been deduced in teleost models, more recently, increased attention has been given to understanding the nature of these connections in basal lineages. We conclude our review by proposing areas for future investigation that aim to fill gaps in the collective understanding of how hormonal signaling underlies ionocyte-based processes.
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Affiliation(s)
- Jason P Breves
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY, 12866, USA.
| | - Ciaran A Shaughnessy
- Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK, 74078, USA
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2
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Pfalzgraff T, Skov PV. Combined antagonist treatment of glucocorticoid and mineralocorticoid receptor does not affect weight loss of fasting rainbow trout but inhibits a fasting-induced elevation of cortisol secretion. Comp Biochem Physiol A Mol Integr Physiol 2022; 274:111321. [PMID: 36169060 DOI: 10.1016/j.cbpa.2022.111321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 09/15/2022] [Accepted: 09/15/2022] [Indexed: 11/17/2022]
Abstract
The gastrointestinal system of fish reacts rapidly to food deprivation. The relative masses of digestive organs and activities of digestive enzymes decrease within days of fasting. This is believed to be an energy-conserving strategy as the metabolic cost of maintaining digestive capacity is high. Cortisol is known for its role in energy mobilization following stress exposure, and prolonged elevated cortisol levels have been shown to reduce growth rates in fish. Fish experiencing chronic cortisol elevations show structural changes to their digestive tissues and overall reductions in relative digestive tissue masses. In fish fasting for prolonged periods, circulating cortisol levels have been reported to be downregulated, upregulated, or unchanged compared to feeding fish. This study aimed to investigate if RU486 and spironolactone, antagonists of the glucocorticoid receptor (GR), and mineralocorticoid receptor (MR), respectively, alone or in combination affect circulating cortisol levels during prolonged starvation. In addition, we tested the effects of blocking GR and MR, on the down-regulation of relative digestive tissue mass during starvation, and its effects on weight loss. Three treatment groups of rainbow trout were intraperitoneally implanted with either GR, MR, or GR and MR blockers. A fourth group was implanted with cortisol, while a fifth group served as a control. All treatment groups were sampled over a course of four weeks of food deprivation and compared against each other and fed control fish at day 0 of the trial. Starvation for 2 weeks and longer significantly increased circulating cortisol levels in all groups except for the group implanted with GR and MR antagonists. Loss of body mass occurred most rapidly during the first week of starvation. Spironolactone treatment resulted in significantly reduced loss of mass during the first week, however, over the following weeks, no differences in mass loss were observed in the groups implanted with blockers, while cortisol-treated fish showed the highest decrease in body mass over time. Relative digestive tissue mass decreased in all groups but apparently, the fasting-induced elevation in plasma cortisol levels did not affect the relative weight loss of digestive tissues as no differences were observed between control fish and GR + MR antagonist treated fish. Very high cortisol levels caused by cortisol treatment however caused a faster decrease in the relative mass of some digestive organs, particularly the stomach.
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Affiliation(s)
- Tilo Pfalzgraff
- Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Centre, 9850 Hirtshals, Denmark.
| | - Peter Vilhelm Skov
- Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Centre, 9850 Hirtshals, Denmark
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3
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Shaughnessy CA, Barany A, McCormick SD. 11-Deoxycortisol controls hydromineral balance in the most basal osmoregulating vertebrate, sea lamprey (Petromyzon marinus). Sci Rep 2020; 10:12148. [PMID: 32699304 PMCID: PMC7376053 DOI: 10.1038/s41598-020-69061-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 07/01/2020] [Indexed: 12/23/2022] Open
Abstract
It is unknown whether and how osmoregulation is controlled by corticosteroid signaling in the phylogenetically basal vertebrate group Agnatha, including lampreys and hagfishes. It is known that a truncated steroid biosynthetic pathway in lampreys produces two predominant circulating corticosteroids, 11-deoxycortisol (S) and 11-deoxycorticosterone (DOC). Furthermore, lampreys express only a single, ancestral corticosteroid receptor (CR). Whether S and/or DOC interact with the CR to control osmoregulation in lampreys is still unknown. We examined the role of the endogenous corticosteroids in vivo and ex vivo in sea lamprey (Petromyzon marinus) during the critical metamorphic period during which sea lamprey increase osmoregulatory capacity and acquire seawater (SW) tolerance. We demonstrate in vivo that increases in circulating [S] and gill CR abundance are associated with increases in osmoregulatory capacity during metamorphosis. We further show that in vivo and ex vivo treatment with S increases activity and expression of gill active ion transporters and improves SW tolerance, and that only S (and not DOC) has regulatory control over active ion transport in the gills. Lastly, we show that the lamprey CR expresses an ancestral, spironolactone-as-agonist structural motif and that spironolactone treatment in vivo increases osmoregulatory capacity. Together, these results demonstrate that S is an osmoregulatory hormone in lamprey and that receptor-mediated discriminative corticosteroid regulation of hydromineral balance is an evolutionarily basal trait among vertebrates.
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Affiliation(s)
- Ciaran A Shaughnessy
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA, USA.
| | - Andre Barany
- Departamento de Biología, Universidad de Cádiz, Cádiz, Spain
| | - Stephen D McCormick
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA, USA
- Department of Biology, University of Massachusetts, Amherst, MA, USA
- U.S. Geological Survey, Leetown Science Center, S.O. Conte Anadromous Fish Research Center, Turners Falls, MA, USA
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4
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Liew HJ, Pelle A, Chiarella D, Faggio C, Tang CH, Blust R, De Boeck G. Common carp, Cyprinus carpio, prefer branchial ionoregulation at high feeding rates and kidney ionoregulation when food supply is limited: additional effects of cortisol and exercise. FISH PHYSIOLOGY AND BIOCHEMISTRY 2020; 46:451-469. [PMID: 31773438 DOI: 10.1007/s10695-019-00736-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 11/13/2019] [Indexed: 06/10/2023]
Abstract
This study aims to examine ionoregulatory parameters during exercise and cortisol elevation in common carp fed different food rations. Fish subjected to two different feeding regimes (0.5 or 3.0% body mass (BM) daily) received no implant or an intraperitoneal cortisol implant (250 mg/kg BM) or sham, and were monitored over a 168-h post-implant (PI) period under resting, low aerobic swimming or exhaustive swimming conditions. Plasma osmolality was maintained at relatively stable levels without much influence of feeding, swimming or cortisol, especially in low feeding groups. Nevertheless, a transient hyponatremia was observed in all low feeding fish implanted with cortisol. The hyponatremia was more pronounced in fish swum to exhaustion but even in this group, Na+ levels returned to control levels as cortisol levels recovered (168 h-PI). Cortisol-implanted fish also had lower plasma Cl- levels, and this loss of plasma Cl- was more prominent in fish fed a high ration during exhaustive swimming (recovered at 168 h-PI). Cortisol stimulated branchial NKA and H+ ATPase activities, especially in high ration fish. In contrast, low ration fish upregulated kidney NKA and H+ ATPase activities when experiencing elevated levels of cortisol. In conclusion, low feeding fish experience an ionoregulatory disturbance in response to cortisol implantation especially when swum to exhaustion in contrast to high feeding fish.
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Affiliation(s)
- Hon Jung Liew
- Institute of Tropical Aquaculture and Fisheries, Universiti Malaysia Terengganu, 21030, Kuala Terengganu, Terengganu, Malaysia.
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium.
| | - Antonella Pelle
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres, 31 CAP, 98166, Messina, Italy
| | - Daniela Chiarella
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres, 31 CAP, 98166, Messina, Italy
| | - Caterina Faggio
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres, 31 CAP, 98166, Messina, Italy
| | - Cheng-Hao Tang
- Department of Oceanography, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan, Republic of China
| | - Ronny Blust
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium
| | - Gudrun De Boeck
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020, Antwerp, Belgium
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5
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Lawrence MJ, Eliason EJ, Zolderdo AJ, Lapointe D, Best C, Gilmour KM, Cooke SJ. Cortisol modulates metabolism and energy mobilization in wild-caught pumpkinseed (Lepomis gibbosus). FISH PHYSIOLOGY AND BIOCHEMISTRY 2019; 45:1813-1828. [PMID: 31300974 DOI: 10.1007/s10695-019-00680-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 06/26/2019] [Indexed: 06/10/2023]
Abstract
Acute elevation of cortisol via activation of the hypothalamic-pituitary-interrenal (HPI) axis aids the fish in dealing with a stressor. However, chronic elevation of cortisol has detrimental effects and has been studied extensively in lab settings. However, data pertaining to wild teleosts are lacking. Here, we characterized the metabolic consequences of prolonged cortisol elevation (96 h) in wild-caught pumpkinseed (Lepomis gibbosus). Pumpkinseed were implanted with cocoa butter alone (sham) or containing cortisol (25 mg kg-1 body weight), and at 24, 48, 72, and 96 h, tissue samples were collected, whole-body ammonia excretion was determined, and whole-organism metabolism was assessed using intermittent flow respirometry. Cortisol-treated pumpkinseed exhibited the highest plasma cortisol concentration at 24 h post-implantation, with levels decreasing over the subsequent time points although remaining higher than in sham-treated fish. Cortisol-treated fish exhibited higher standard and maximal metabolic rates than sham-treated fish, but the effect of cortisol treatment on aerobic scope was negligible. Indices of energy synthesis/mobilization, including blood glucose concentrations, hepatosomatic index, hepatic glycogen concentrations, and ammonia excretion rates, were higher in cortisol-treated fish compared with controls. Our work suggests that although aerobic scope was not diminished by prolonged elevation of cortisol levels, higher metabolic expenditures may be of detriment to the animal's performance in the longer term.
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Affiliation(s)
- Michael J Lawrence
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada.
| | - Erika J Eliason
- Department of Ecology, Evolution & Marine Biology, University of California, Santa Barbara, CA, 93117, USA
| | - Aaron J Zolderdo
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada
- Queen's University Biological Station, Queen's University, Elgin, ON, K0G 1E0, Canada
| | - Dominique Lapointe
- St. Lawrence River Institute of Environmental Sciences, Cornwall, ON, K6H 4Z1, Canada
| | - Carol Best
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Kathleen M Gilmour
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Steven J Cooke
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada
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6
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Mattioli CC, Takata R, de Oliveira Paes Leme F, Costa DC, Luz RK. Physiological and metabolic responses of juvenile Lophiosilurus alexandri catfish to air exposure. FISH PHYSIOLOGY AND BIOCHEMISTRY 2019; 45:455-467. [PMID: 30368686 DOI: 10.1007/s10695-018-0576-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 10/02/2018] [Indexed: 06/08/2023]
Abstract
The present study aimed to evaluate the physiological and metabolic stress responses of juvenile Lophiosilurus alexandri submitted to an air exposure test. The subjects consisted of 72 juveniles. Blood samples were taken at: 0 h-fish not exposed to air; 0.5 h-fish shortly after exposure to air for 30 min (prior to returning to the tank); 1.5 h (90 min), 24, 48, and 96 h after the initiation of exposure to air for 30 min. After 96 h, survivorship was 100%. Cortisol and glucose levels were higher at 0.5 h, returning to baseline at 48 and 24 h, respectively. Lactate dehydrogenase levels were highest at 1.5 h after exposure to air, returning to normal values in 24 h. Several changes were recorded in gasometric blood values and electrolytes. With regard to hematology and blood chemistry, exposure to air did not affect globular volume and AST throughout the 96 h of the experiment. The values for alkaline phosphatase were highest at 0, 1.5, and 24 h. Total protein was similar between 0 and 1.5 h and lowest at 96 h, while ALT was highest at 0.5 h. Leukocytes were highest at 0.5, 1.5, 48, and 96 h, while erythrocytes were highest at 96 h. After 96 h, juvenile L. alexandri were able to reestablish the main indicators of stress (cortisol, glucose and lactate dehydrogenase), while other indicators (hematological, biochemical, and gasometric) exhibited compensatory variation for normal physiological re-establishment.
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Affiliation(s)
- Cristiano Campos Mattioli
- Escola de Veterinária, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, n° 6627, Belo Horizonte, CEP 30161-970, Brazil
| | - Rodrigo Takata
- Unidade de Pesquisa e Reprodução de Peixes, Fundação Instituto de Pesca do Estado do Rio de Janeiro, Av. Presidente Vargas, 197, Parque de Exposições, Niterói, CEP 28540-000, Brazil
| | - Fabiola de Oliveira Paes Leme
- Escola de Veterinária, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, n° 6627, Belo Horizonte, CEP 30161-970, Brazil
| | - Deliane Cristina Costa
- Escola de Veterinária, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, n° 6627, Belo Horizonte, CEP 30161-970, Brazil
| | - Ronald Kennedy Luz
- Escola de Veterinária, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, n° 6627, Belo Horizonte, CEP 30161-970, Brazil.
- Laboratório de Aquacultura da Escola de Veterinária da Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, Cep 31270-901, Brazil.
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7
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Khansari AR, Parra D, Reyes-López FE, Tort L. Modulatory in vitro effect of stress hormones on the cytokine response of rainbow trout and gilthead sea bream head kidney stimulated with Vibrio anguillarum bacterin. FISH & SHELLFISH IMMUNOLOGY 2017; 70:736-749. [PMID: 28882798 DOI: 10.1016/j.fsi.2017.09.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 08/25/2017] [Accepted: 09/01/2017] [Indexed: 06/07/2023]
Abstract
In fish, the stress response and their consequences in the immune system have been widely described. Recently, a differential cytokine regulation between rainbow trout (Oncorhynchus mykiss) and gilthead sea bream (Sparus aurata) was reported after treatment with stress hormones together with their receptor antagonists. Nevertheless, there is no evidence of whether antagonists for stress hormone receptors may influence the interaction between hormones and cytokines after bacterial administration. Thus, the aim of our study was to evaluate the cytokine expression in the presence of stress hormones (cortisol, ACTH, adrenaline), hormone receptor antagonists and inactivated Vibrio anguillarum bacterin in rainbow trout and gilthead sea bream head kidney primary cell culture (HKPCC). Mifepristone, spironolactone, propranolol and phentolamine were used to block GR, MR, MC2R, and β-/α-adrenoreceptors. Our results showed an expected increase of the pro-inflammatory and anti-inflammatory response after inactivated V. anguillarum bacterin treatment in both species. Cortisol, ACTH and adrenaline did not modulate the expression of immune-related genes in rainbow trout, while in sea bream cortisol was able to reduce the stimulated gene expression of all cytokines. This effect was only restored to basal expression level in IL-1β and TNF-α by mifepristone. ACTH reduced both pro-inflammatory and anti-inflammatory cytokine expression, excluding IL-1β, only in sea bream. Adrenaline enhanced the expression of IL-1β and TGF-β1 stimulated by inactivated V. anguillarum in sea bream, and the effect was diminished by propranolol. In sum, our results confirm that the immunoendocrine differences reported at gene expression profile between two teleost species are also observed after exposure to inactivated V. anguillarum bacterin, suggesting that stress hormones would differentially modulate the immune response against pathogens in teleost species.
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Affiliation(s)
- Ali Reza Khansari
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - David Parra
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Felipe E Reyes-López
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
| | - Lluís Tort
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
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8
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Khansari AR, Parra D, Reyes-López FE, Tort L. Cytokine modulation by stress hormones and antagonist specific hormonal inhibition in rainbow trout (Oncorhynchus mykiss) and gilthead sea bream (Sparus aurata) head kidney primary cell culture. Gen Comp Endocrinol 2017. [PMID: 28634082 DOI: 10.1016/j.ygcen.2017.06.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A tight interaction between endocrine and immune systems takes place mainly due to the key role of head kidney in both hormone and cytokine secretion, particularly under stress situations in which the physiological response promotes the synthesis and release of stress hormones which may lead into immunomodulation as side effect. Although such interaction has been previously investigated, this study evaluated for the first time the effect of stress-associated hormones together with their receptor antagonists on the expression of cytokine genes in head kidney primary cell culture (HKPCC) of the freshwater rainbow trout (Oncorhynchus mykiss) and the seawater gilthead sea bream (Sparus aurata). The results showed a striking difference when comparing the response obtained in trout and seabream. Cortisol and adrenocorticotropic hormone (ACTH) decreased the expression of immune-related genes in sea bream but not in rainbow trout and this cortisol effect was reverted by the antagonist mifepristone but not spironolactone. On the other hand, while adrenaline reduced the expression of pro-inflammatory cytokines (IL-1β, IL-6) in rainbow trout, the opposite effect was observed in sea bream showing an increased expression (IL-1β, IL-6). Interestingly, this effect was reverted by antagonist propranolol but not phentolamine. Overall, our results confirm the regional interaction between endocrine and cytokine messengers and a clear difference in the sensitivity to the hormonal stimuli between the two species.
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Affiliation(s)
- Ali Reza Khansari
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
| | - David Parra
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
| | - Felipe E Reyes-López
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
| | - Lluís Tort
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
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9
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Lin CH, Hu HJ, Hwang PP. Cortisol regulates sodium homeostasis by stimulating the transcription of sodium-chloride transporter (NCC) in zebrafish (Danio rerio). Mol Cell Endocrinol 2016; 422:93-102. [PMID: 26678829 DOI: 10.1016/j.mce.2015.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 11/16/2015] [Accepted: 12/01/2015] [Indexed: 12/28/2022]
Abstract
In mammals, sodium/hydrogen exchanger (NHE) and sodium-chloride cotransporter (NCC) are expressed in renal tubules, and exhibit functional redundancy and mutual compensation in Na(+) uptake. In teleosts, the gills of the adult and skin of the embryonic stage function as external kidneys, and ionocytes are responsible for ionoregulation in these tissues. NHE- and NCC-expressing ionocytes mutually cooperate to adjust Na(+) uptake, which is analogous to the activity of the mammalian kidney. Cortisol is a hormone that controls Na(+) uptake through regulating NCC expression and activity in mammals; however, cortisol-mediated control of NCC expression is little understood in non-mammalian vertebrates, such as teleosts. It is essential for our understanding of the evolution of such regulation to determine whether cortisol has a conserved effect on NCC in vertebrates. In the present study, we treated zebrafish embryos with low Na(+) medium (LNa, 0.04 mM Na(+)) for 3 d to stimulate the mRNA expression of nhe3b, ncc, and cyp11b1 (a cortisol-synthesis enzyme) and whole body cortisol level. Exogenous cortisol treatment (20 mg/l, 3 d) resulted in an elevation of whole-body Na(+) content, ncc expression, and the density of ncc-expressing cells in zebrafish larvae. In loss-of-function experiments, microinjection of glucocorticoid receptor (gr) morpholino (MO) suppressed sodium content, ncc expression, and the density of ncc-expressing cells, but injection of mr MO had no such effects. In addition, exogenous cortisol treatment and gr MO injection also altered ncc expression and the density of ncc-expressing cells in gcm2 morphant larvae. Taken together, cortisol and GR appear to regulate Na(+) absorption through stimulating ncc expression and the differentiation of ncc-expressing ionocytes, providing new insights into the actions of cortisol on Na(+) uptake.
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Affiliation(s)
- Chia-Hao Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan; National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Huei-Jyun Hu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan.
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10
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Lin CH, Kuan WC, Liao BK, Deng AN, Tseng DY, Hwang PP. Environmental and cortisol-mediated control of Ca(2+) uptake in tilapia (Oreochromis mossambicus). J Comp Physiol B 2016; 186:323-32. [PMID: 26857273 PMCID: PMC4791471 DOI: 10.1007/s00360-016-0963-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/12/2016] [Accepted: 01/21/2016] [Indexed: 12/14/2022]
Abstract
Ca2+ is a vital element for many physiological processes in vertebrates, including teleosts, which live in aquatic environments and acquire Ca2+ from their surroundings. Ionocytes within the adult gills or larval skin are critical sites for transcellular Ca2+ uptake in teleosts. The ionocytes of zebrafish were found to contain transcellular Ca2+ transporters, epithelial Ca2+ channel (ECaC), plasma membrane Ca2+-ATPase 2 (PMCA2), and Na+/Ca2+ exchanger 1b (NCX1b), providing information about the molecular mechanism of transcellular Ca2+ transports mediated by ionocytes in fish. However, more evidence is required to establish whether or not a similar mechanism of transcellular Ca2+ transport also exists in others teleosts. In the present study, ecac, pmca2, and ncx1 were found to be expressed in the branchial ionocytes of tilapia, thereby providing further support for the mechanism of transcellular Ca2+ transport through ionocytes previously proposed for zebrafish. In addition, we also reveal that low Ca2+ water treatment of tilapia stimulates Ca2+ uptake and expression of ecac and cyp11b (the latter encodes a cortisol-synthesis enzyme). Treatment of tilapia with exogenous cortisol (20 mg/l) enhanced both Ca2+ influx and ecac expression. Therefore, increased cyp11b expression is suggested to enhance Ca2+ uptake capacity in tilapia exposed to low Ca2+ water. Furthermore, the application of cortisol receptor antagonists revealed that cortisol may regulate Ca2+ uptake through glucocorticoid and/or mineralocorticoid receptor (GR and/or MR) in tilapia. Taken together, the data suggest that cortisol may activate GR and/or MR to execute its hypercalcemic action by stimulating ecac expression in tilapia.
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Affiliation(s)
- Chia-Hao Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC.,National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Wei-Chun Kuan
- Department of Biological Sciences and Technology, National University of Tainan, Tainan, 70005, Taiwan, ROC
| | - Bo-Kai Liao
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC
| | - Ang-Ni Deng
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC
| | - Deng-Yu Tseng
- Department of Biological Sciences and Technology, National University of Tainan, Tainan, 70005, Taiwan, ROC.
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC.
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11
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Liew HJ, Fazio A, Faggio C, Blust R, De Boeck G. Cortisol affects metabolic and ionoregulatory responses to a different extent depending on feeding ration in common carp, Cyprinus carpio. Comp Biochem Physiol A Mol Integr Physiol 2015. [DOI: 10.1016/j.cbpa.2015.07.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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12
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Kalamarz-Kubiak H, Kleszczyńska A, Kulczykowska E. Cortisol stimulates arginine vasotocin and isotocin release from the hypothalamo-pituitary complex of round goby (Neogobius melanostomus): Probable mechanisms of action. ACTA ACUST UNITED AC 2015; 323:616-26. [PMID: 26173922 DOI: 10.1002/jez.1952] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 05/10/2015] [Accepted: 06/13/2015] [Indexed: 11/09/2022]
Abstract
There were two aims of this in vitro perfusion study. Firstly, to determine which class of receptors, glucocorticoid (GRs) or mineralocorticoid (MRs), are involved in cortisol regulation of arginine vasotocin (AVT) and isotocin (IT) release from the hypothalamo-pituitary (H-P) complex of round goby (Neogobius melanostomus). Secondly, to determine which pathways, genomic or non-genomic, are involved in the aformentioned process.The H-P explants were perfused with cortisol (1.4 × 10(-) (7) M, 2.8 × 10(-7) M, 0.4 × 10(-6) M); only the highest dose significantly increased a release of both nonapeptides. In the perfusion of H-P explants, we used cortisol (0.4 × 10(-6) M) in combination with GRs antagonist RU486 (0.3 × 10(-6) M) or MRs antagonist C03DA01 (0.36 × 10(-6) M) or transcription inhibitor Actinomycin D (1 × 10(-7) M). All inhibitors were also tested seperately. The contents of AVT and IT in the perfusion media was determined by high-performance liquid chromatography (HPLC) with UV detection. This study suggested that different mechanisms were involved in the regulation of AVT and IT release from H-P complex in round goby. Apparently it was GRs but not MRs that were involved in cortisol regulation of AVT and IT release. In the case of AVT, our data points to both genomic and non-genomic pathways mediating the effect of cortisol; in the case of IT, it is only the non-genomic pathway. This study presents the first feasible mechanisms of cortisol action on AVT and IT release from the H-P complex in round goby.
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Affiliation(s)
- Hanna Kalamarz-Kubiak
- Department of Genetics and Marine Biotechnology, Institute of Oceanology Polish Academy of Sciences, Sopot, Poland
| | - Agnieszka Kleszczyńska
- Department of Genetics and Marine Biotechnology, Institute of Oceanology Polish Academy of Sciences, Sopot, Poland
| | - Ewa Kulczykowska
- Department of Genetics and Marine Biotechnology, Institute of Oceanology Polish Academy of Sciences, Sopot, Poland
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13
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Cruz SA, Lin CH, Chao PL, Hwang PP. Glucocorticoid receptor, but not mineralocorticoid receptor, mediates cortisol regulation of epidermal ionocyte development and ion transport in zebrafish (danio rerio). PLoS One 2013; 8:e77997. [PMID: 24205060 PMCID: PMC3812134 DOI: 10.1371/journal.pone.0077997] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/08/2013] [Indexed: 12/25/2022] Open
Abstract
Cortisol is the major endogenous glucocorticoid (GC) both in human and fish, mediated by corticosteroid receptors. Due to the absence of aldosterone production in teleost fish, cortisol is also traditionally accepted to function as mineralocorticoid (MC); but whether it acts through the glucocorticoid receptor (GR) or the mineralocorticoid receptor (MR) remains a subject of debate. Here, we used loss-of-function and rescue assays to determine whether cortisol affects zebrafish epidermal ionocyte development and function via the GR and/or the MR. GR knockdown morphants displayed a significant decrease in the major ionocytes, namely Na(+)-K(+)-ATPase-rich cells (NaRCs) and H(+)-ATPase-rich cells (HRCs), as well as other cells, including epidermal stem cells (ESCs), keratinocytes, and mucus cells; conversely, cell numbers were unaffected in MR knockdown morphants. In agreement, GR morphants, but not MR morphants, exhibited decreased NaRC-mediated Ca(2+) uptake and HRC-mediated H(+) secretion. Rescue via GR capped mRNA injection or exogenous cortisol incubation normalized the number of epidermal ionocytes in GR morphants. We also provide evidence for GR localization in epidermal cells. At the transcript level, GR mRNA is ubiquitously expressed in gill sections and present in both NaRCs and HRCs, supporting the knockdown and functional assay results in embryo. Altogether, we have provided solid molecular evidence that GR is indeed present on ionocytes, where it mediates the effects of cortisol on ionocyte development and function. Hence, cortisol-GR axis performs the roles of both GC and MC in zebrafish skin and gills.
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Affiliation(s)
- Shelly Abad Cruz
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan, R. O. C
| | - Chia-Hao Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan, R. O. C
| | - Pei-Lin Chao
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan, R. O. C
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan, R. O. C
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14
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Simonato JD, Fernandes MN, Martinez CBR. Physiological effects of gasoline on the freshwater fish Prochilodus lineatus(Characiformes: Prochilodontidae). NEOTROPICAL ICHTHYOLOGY 2013. [DOI: 10.1590/s1679-62252013000300022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The purpose of this work was to evaluate the effects of the water-soluble fraction of gasoline (WSFG) on the Neotropical freshwater fish Prochilodus lineatus. The WSFG was prepared by mixing gasoline in water (1:4) and animals were exposed for 6, 24 and 96h to 5% diluted WSFG or only to water. After exposure, blood was collected from the caudal vein and the gills were removed. The following parameters were analyzed: hematological (hemoglobin, hematocrit, number of red blood cells), osmo-ionic (plasma Na+, Cl- and K+ and plasma osmolarity), metabolic (total plasma proteins and glucose), endocrine (cortisol), density and distribution of chloride cells [CC] in the gills (immunohistochemistry), and branchial Na+/K+-ATPase (NKA) activity. Hemolysis was found to occur after 96h exposure to WSFG, as indicated by the decrease in the hematological parameters analyzed, followed by an increase in plasma K+. Secondary stress response was revealed by the occurrence of hyperglycemia in the three periods of exposure, despite the absence of significant increases in the plasma cortisol. The exposure to WSFG also caused an increase in the quantity of CC and in plasma Na+, after 24h, as well as in the enzymatic activity of NKA and plasma osmolarity, after 24h and 96h. These results indicate that fish exposed to the WSFG showed physiological adjusts to maintain their osmotic balance. However, the increase in the quantity of CC in the lamellae may interfere in the gas exchange impairing respiration.
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15
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Medeiros LR, McDonald MD. Cortisol-mediated downregulation of the serotonin 1A receptor subtype in the Gulf toadfish, Opsanus beta. Comp Biochem Physiol A Mol Integr Physiol 2013; 164:612-21. [DOI: 10.1016/j.cbpa.2013.01.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 01/20/2013] [Accepted: 01/22/2013] [Indexed: 12/15/2022]
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16
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Aruna A, Nagarajan G, Chang CF. Differential expression patterns and localization of glucocorticoid and mineralocorticoid receptor transcripts in the osmoregulatory organs of tilapia during salinity stress. Gen Comp Endocrinol 2012; 179:465-76. [PMID: 23085115 DOI: 10.1016/j.ygcen.2012.08.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 08/19/2012] [Accepted: 08/24/2012] [Indexed: 12/12/2022]
Abstract
The glucocorticoid receptor (GR) plays an essential role during seawater (SW) acclimation. However, the regulation of GR isoforms 1 and 2 (GR1 and GR2) and the mineralocorticoid receptor (MR) during SW acclimation is poorly understood. To address this, we localized and examined the GR1, GR2 and MR transcripts in the tilapia gill, kidney and intestine. Our results indicated that the GR1, GR2 and MR levels were increased in the kidney and intestine on day 1 in seawater (SW) fish, which is in agreement with the recognized osmoregulatory role of the corticosteroid receptors. The SW transfer increased the GR2 and MR transcripts in the gill on day 1 and 4, respectively. Surprisingly, no significant difference was obtained for the GR1 mRNA level. Analysis of the plasma parameters in freshwater (FW) and SW tilapia showed that the plasma cortisol levels were significantly increased at day 1 in the SW fish compared to the FW fish. This is the first study that focused on the spatial distribution of GR1, GR2 and MR in the osmoregulatory organs of freshwater (FW)- and SW-acclimated tilapia by in situ hybridization. Consistent with the Q-PCR results, the expression levels of the GR1, GR2 and MR transcripts were increased or decreased in the SW-acclimated tilapia's gill, kidney and intestine compared to the FW fish. We observed that GR1, GR2 and MR were localized in the branchial epithelial cells and chloride cells of the gill, proximal tubules of the kidney and columnar cells of the intestine. Together, these results indicate that the mobilization of corticosteroid receptors is dependent on the target tissue, salinity and exposure time.
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Affiliation(s)
- Adimoolam Aruna
- Department of Aquaculture, National Taiwan Ocean University, Keelung 20224, Taiwan
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17
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Kumai Y, Nesan D, Vijayan MM, Perry SF. Cortisol regulates Na+ uptake in zebrafish, Danio rerio, larvae via the glucocorticoid receptor. Mol Cell Endocrinol 2012; 364:113-25. [PMID: 22963886 DOI: 10.1016/j.mce.2012.08.017] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 08/26/2012] [Accepted: 08/27/2012] [Indexed: 12/22/2022]
Abstract
Unlike other freshwater fish previously examined, zebrafish are capable of increasing their rate of Na(+) uptake during chronic exposure to acidic water (pH 4). In the present study, the potential role of cortisol in the induction of Na(+) uptake during acid-exposure was investigated. When zebrafish larvae (4 days post-fertilization) were treated with waterborne cortisol, the rate of Na(+) uptake was significantly increased; this effect was blocked by co-incubating larvae with RU-486, an antagonist selective for the glucocorticoid receptor (GR). A similar induction in Na(+) uptake, which was also blocked by RU-486, was observed when larvae were treated with dexamethasone, a selective GR agonist. Conversely, treating larvae with aldosterone, a selective agonist for the mineralocorticoid receptor (MR) had no effect on Na(+) uptake. Acid-exposure increased whole body cortisol levels and translational knockdown of GR using antisense morpholinos prevented the full induction of Na(+) uptake during exposure to acidic water, further confirming the role of cortisol and GR in Na(+) uptake stimulation. Using immunohistochemistry, GR was localized to ionocytes known to be responsible for Na(+) uptake (HR-cells). Knockdown of Rhcg1, an apical membrane ammonia channel or Na(+)/H(+) exchanger 3b (NHE3b), proteins known to play an important role in facilitating Na(+) uptake in acidic water, prevented the stimulatory effects of cortisol treatment on Na(+) uptake, suggesting that cortisol regulates Na(+) uptake by stimulating an Rhcg1-NHE3b "functional metabolon".
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Affiliation(s)
- Yusuke Kumai
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
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18
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Cruz SA, Chao PL, Hwang PP. Cortisol promotes differentiation of epidermal ionocytes through Foxi3 transcription factors in zebrafish (Danio rerio). Comp Biochem Physiol A Mol Integr Physiol 2012; 164:249-57. [PMID: 23010242 DOI: 10.1016/j.cbpa.2012.09.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2012] [Revised: 09/14/2012] [Accepted: 09/17/2012] [Indexed: 01/30/2023]
Abstract
Glucocorticoid regulates epidermal cell proliferation, and is used to treat certain skin disorders. Cortisol, a glucocorticoid, is also linked to skin development in teleost fish. Cortisol increases the number of epithelial ionocytes during environmental acclimation in euryhaline fishes, but it is unclear whether this is due to increased differentiation or proliferation. To investigate, we treated zebrafish embryos with exogenous cortisol (20mg/L). The densities of the ionocytes Na(+)-K(+)-ATPase rich cells (NaRCs) and H(+)-ATPase rich cells (HRCs) were significantly increased by cortisol, and this was accompanied by an increase in the respective marker genes. Expression of the glucocorticoid receptor (GR) gene was decreased. Cortisol treatment also increased ionocytes in cultured adult zebrafish gills, and up-regulated expression of genes encoding forkhead box I3 (foxi3a and foxi3b) transcription factors, which regulate ionocyte progenitor development. GR expression was up-regulated by cortisol in vitro; as such, the observed decrease in vivo reflects a regulatory systemic-negative feedback. Notably, in situ hybridization revealed that foxi3a/b mRNA expression was increased by cortisol at 24-48h post-fertilization. Cortisol also decreased keratinocytes, but did not affect epidermal stem cells or mucus cells. We conclude that foxi3a/b transactivation by cortisol-GR favors differentiation of ionocyte progenitors, thereby facilitating proliferation of mature ionocytes.
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Affiliation(s)
- Shelly Abad Cruz
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan, ROC
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19
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Mechanisms and regulation of Na(+) uptake by freshwater fish. Respir Physiol Neurobiol 2012; 184:249-56. [PMID: 22698881 DOI: 10.1016/j.resp.2012.06.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 06/04/2012] [Accepted: 06/05/2012] [Indexed: 11/21/2022]
Abstract
Mechanisms of ion uptake by freshwater (FW) fish have received considerable attention over the past 80 years. Through an assortment of techniques incorporating whole animal physiology, electrophysiology and molecular biological approaches, three models have been proposed to account for Na(+) uptake. (1) Direct exchange of Na(+) and H(+) via one or more types of Na(+)/H(+) exchanger (slc9), (2) uptake of Na(+) through epithelial Na(+) channels energized by an electrical gradient created by H(+)-ATPase and (3) Na(+)/Cl(-) co-transport (slc12). While each mechanism is supported at least in part by theoretical or experimental data, there are several outstanding questions that have not yet been fully resolved. Furthermore, there are few details concerning how these Na(+) uptake mechanisms are fine tuned in response to the fluctuating FW environments. In this review, we summarize the current understanding of these three Na(+) uptake mechanisms and discuss their regulation by endocrine (cortisol and prolactin) and neurohumoral (catecholamines) factors.
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20
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Aruna A, Nagarajan G, Chang CF. Involvement of corticotrophin-releasing hormone and corticosteroid receptors in the brain-pituitary-gill of tilapia during the course of seawater acclimation. J Neuroendocrinol 2012; 24:818-30. [PMID: 22250893 DOI: 10.1111/j.1365-2826.2012.02282.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
The mRNA expression of genes for corticotrophin-releasing hormone (CRH) and the hormone receptors CRH-receptor/CRH-R, glucocorticoid receptor 1/2 (GR1/2) and mineralocorticoid receptor (MR) was studied in the brain, pituitary and gill of tilapia (Oreochromis mossambibus) during salinity and handling stress by real-time quantitative-polymerase chain reaction analysis. The results indicated that the transcripts of CRH and CRH-R were increased in the forebrain, midbrain and gill, whereas elevated hypothalamic CRH mRNA suppressed the CRH-R mRNA in the pituitary in seawater (SW) fish. The levels of plasma osmolality and cortisol were significantly increased in SW compared to freshwater fish. The up-regulation of GR1, GR2, MR and α-NKA (Na(+) /K(+) -ATPase) transcripts in SW fish provided evidence that cortisol responds to stress and involves ion-base regulation via the GR1, GR2 and MR receptors in the gill. These data suggest that GR1, GR2 and MR have a pivotal role in the brain and gill. GR1, GR2 and MR expression may be dependent on CRH and cortisol expression in the brain and gill. In addition, we performed in situ hybridisation analysis to localise and differentiate the CRH, CRH-R, GR1, GR2 and MR transcripts in the brain of FW- and SW-acute acclimated tilapia during salinity stress. In almost all transcripts, the hybridisation signal was significantly abundant in the SW-acute acclimated tilapia brain, especially in the dorsal ventral cephalon, dorsal nucleus preopticus pars magnocellularis and dorsal nucleus preopticus pars parvocellularis. Salinity stress induced differential and specific responses in the gill and brain compared to handling stress.
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Affiliation(s)
- A Aruna
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan
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21
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Flores AM, Mark Shrimpton J. Differential physiological and endocrine responses of rainbow trout, Oncorhynchus mykiss, transferred from fresh water to ion-poor or salt water. Gen Comp Endocrinol 2012; 175:244-50. [PMID: 22137911 DOI: 10.1016/j.ygcen.2011.11.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 08/02/2011] [Accepted: 11/02/2011] [Indexed: 10/15/2022]
Abstract
To understand the physiological and molecular endocrine changes that occur in response to a salinity challenge, we transferred rainbow trout from fresh water to an ion-poor or 24‰ saltwater treatment for 14 days. An increase in gill Na(+), K(+)-ATPase (NKA) activity in salt water was associated with higher mRNA expression for the NKA α1b subunit. In contrast, there was little change in gill NKA activity following transfer to ion-poor water, but the mRNA expression of NKA α1a was significantly elevated. Endocrine signals were assessed by measuring plasma cortisol concentrations and by quantifying changes in mRNA extracted from the gill for glucocorticoid receptors 1 and 2 (GR1 and GR2), mineralocorticoid receptor (MR), growth hormone receptor (GHR1), and prolactin receptor (PrlR). Cortisol increased after transfer to ion-poor and salt water, but both GR and MR mRNA in the gill showed little change. PrlR mRNA was significantly higher when fish were transferred to the ion-poor water and GHR1 mRNA was elevated during the saltwater challenge. This study demonstrated an increase in gill PrlR mRNA that parallels the changes in gill NKA α1a when rainbow trout were transferred to a lower salinity level. Furthermore, the increase in gill GHR1 mRNA supports the importance of GH for seawater acclimation as there is a corresponding increase in the expression of gill NKA α1b, the saltwater isoform. GH and Prl, therefore, may differentially determine the function of cortisol in both fresh- and saltwater ionoregulation.
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MESH Headings
- Animals
- Endocrine System/physiology
- Fresh Water/chemistry
- Gills/metabolism
- Hydrocortisone/metabolism
- Oncorhynchus mykiss/metabolism
- Oncorhynchus mykiss/physiology
- RNA, Messenger
- Receptors, Glucocorticoid/genetics
- Receptors, Glucocorticoid/metabolism
- Receptors, Mineralocorticoid/genetics
- Receptors, Mineralocorticoid/metabolism
- Receptors, Prolactin/genetics
- Receptors, Prolactin/metabolism
- Receptors, Somatotropin/genetics
- Receptors, Somatotropin/metabolism
- Seawater/chemistry
- Sodium Chloride/metabolism
- Sodium-Potassium-Exchanging ATPase/genetics
- Sodium-Potassium-Exchanging ATPase/metabolism
- Stress, Physiological
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Affiliation(s)
- Anne-Marie Flores
- Ecosystem Science and Management (Biology) Program, University of Northern British Columbia, Prince George, Canada V2N 4Z9.
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22
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Kelly SP, Chasiotis H. Glucocorticoid and mineralocorticoid receptors regulate paracellular permeability in a primary cultured gill epithelium. ACTA ACUST UNITED AC 2011; 214:2308-18. [PMID: 21697422 DOI: 10.1242/jeb.055962] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The role of corticosteroid receptors (CRs) in the regulation of gill permeability was examined using a primary cultured trout gill epithelium. The epithelium expressed both glucocorticoid receptors (GR1 and GR2) and a mineralocorticoid receptor (MR), and cortisol treatment significantly increased transepithelial resistance (TER) and decreased paracellular [(3)H]PEG-4000 flux. Epithelial permeability was unaffected by deoxycorticosterone or aldosterone. The GR antagonist RU486 as well as MR antagonists spironolactone and RU26752 significantly reduced, but did not completely block, the effects of cortisol. The MR antagonist eplerenone was without effect. Only RU486 + spironolactone or RU486 + RU26752 treatment completely suppressed the effects of cortisol. On its own, RU486 had cortisol-like effects which could be blocked by spironolactone, suggesting that although RU486 is a GR antagonist, in this system it may also have agonistic properties that are mediated through the MR. The GR agonist dexamethasone increased TER and reduced [(3)H]PEG-4000 flux across cultured epithelia and was unaffected by MR antagonists. Therefore, alterations in transcript abundance of select tight junction (TJ) proteins were examined in response to cortisol, dexamethasone (a GR agonist) and RU486 (as a MR agonist). Occludin and claudin-7, -8d, -12 and -31 mRNA were significantly elevated in response to cortisol, dexamethasone or RU486 treatment. Claudin-3a mRNA was significantly elevated in response to cortisol or dexamethasone only, and claudin-28b and -30 mRNA were significantly altered following cortisol or RU486 treatment only. The data support a role for the GRs and MR in regulating gill permeability and suggest that TJ proteins are responsive to cortisol through both or individual CR types.
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Affiliation(s)
- Scott P Kelly
- Department of Biology, York University, Toronto, ON, Canada, M3J 1P3.
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23
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Rodela TM, Esbaugh AJ, McDonald MD, Gilmour KM, Walsh PJ. Evidence for transcriptional regulation of the urea transporter in the gill of the Gulf toadfish, Opsanus beta. Comp Biochem Physiol B Biochem Mol Biol 2011; 160:72-80. [PMID: 21740977 DOI: 10.1016/j.cbpb.2011.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 06/24/2011] [Accepted: 06/24/2011] [Indexed: 02/01/2023]
Abstract
Ureotelic Gulf toadfish (Opsanus beta) do not excrete urea continuously; instead, urea is accumulated internally until a branchial urea transport mechanism is activated to facilitate the excretion of urea in distinct pulses. This unusual pulsatile urea excretion pattern is regulated, in part, by permissive declines in circulating cortisol concentrations. The current study examined toadfish urea transporter (tUT) and glucocorticoid receptor (GR) transcript levels in toadfish gill following chronic (days) and acute (hours) changes in corticosteroid activity. Experimentally lowering circulating cortisol did not significantly alter tUT mRNA abundance but increased GR mRNA. On an acute timescale, a 6.2-fold upregulation of tUT mRNA occurred 12 to 18 h following a urea pulse event with no change in GR mRNA. In silico analysis of an isolated 1.2 kb fragment, upstream promoter region of the tUT gene, revealed 6 putative glucocorticoid response element (GRE) half sites. In vivo reporter assays of the tUT promoter fragment demonstrated relative luciferase activity was enhanced 3.4- and 9.8-fold following exposure to moderate (via a 48 h crowding stress) and high (via infusion for 48 h) cortisol. We conclude that a GRE-mediated upregulation of mRNA may be required to maintain tUT activity by offsetting post-transcriptional and/or post-translational changes that may be associated with chronically elevated plasma cortisol.
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Affiliation(s)
- Tamara M Rodela
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
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24
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Sakamoto T, Mori C, Minami S, Takahashi H, Abe T, Ojima D, Ogoshi M, Sakamoto H. Corticosteroids stimulate the amphibious behavior in mudskipper: Potential role of mineralocorticoid receptors in teleost fish. Physiol Behav 2011; 104:923-8. [DOI: 10.1016/j.physbeh.2011.06.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 06/01/2011] [Accepted: 06/02/2011] [Indexed: 01/31/2023]
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25
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Pippal JB, Cheung CMI, Yao YZ, Brennan FE, Fuller PJ. Characterization of the zebrafish (Danio rerio) mineralocorticoid receptor. Mol Cell Endocrinol 2011; 332:58-66. [PMID: 20932876 DOI: 10.1016/j.mce.2010.09.014] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 09/06/2010] [Accepted: 09/28/2010] [Indexed: 01/21/2023]
Abstract
Comparison between evolutionarily distant receptors can provide critical insights into both structure and function. Sequence comparison between the mineralocorticoid receptors (MR) of the zebrafish (zMR) and human (hMR) reveals a high degree of sequence conservation in the major functional domains. We isolated a zMR cDNA to contrast the transcriptional response to a range of ligands and to establish whether a teleost MR exhibits the amino/carboxyl-terminal interaction (N/C-interaction) previously reported for the hMR. Aldosterone, deoxycorticosterone (DOC) and cortisol induced zMR transcriptional activity with similar efficacy to that observed with the hMR. The hMR antagonist, spironolactone, acted as an agonist with the zMR. The zMR exhibited an N/C-interaction in response to aldosterone but, in contrast to the hMR, cortisol and DOC predominantly stimulated the interaction in the zMR. Conservation of the N/C-interaction between evolutionarily distant MR provides evidence of functional significance.
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Affiliation(s)
- Jyotsna B Pippal
- Prince Henry's Institute of Medical Research, Monash University, Clayton, VIC 3168, Australia
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26
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Kiilerich P, Pedersen SH, Kristiansen K, Madsen SS. Corticosteroid regulation of Na(+),K(+)-ATPase α1-isoform expression in Atlantic salmon gill during smolt development. Gen Comp Endocrinol 2011; 170:283-9. [PMID: 20171217 DOI: 10.1016/j.ygcen.2010.02.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 02/10/2010] [Accepted: 02/12/2010] [Indexed: 11/25/2022]
Abstract
The proposed mineralocorticoid-like signalling axis in teleost fish, consisting of the hormone 11-deoxycorticosterone (DOC) and a mineralocorticoid receptor (MR), has recently challenged our conception of cortisol being the only osmoregulatory corticosteroid in teleost fish. This paper aimed at comparing the osmoregulatory role of DOC with that of cortisol during the pre-adaptive development of SW-tolerance, smoltification, in Atlantic salmon. Using an in vitro gill block incubation system, the effect of DOC and cortisol in the gill was investigated from January to September, using Na(+),K(+)-ATPase α-subunit isoforms α-1a and α-1b mRNA levels as targets for regulation by the hormones. Cortisol and DOC both conferred significant up-regulation of α-1a and α-1b mRNA levels at specific time-points during smoltification. However, the effect of cortisol and DOC on α-subunit isoforms varied seasonally between isoforms and hormones. The maximum induction of α-1a was 3- to 4-fold compared to controls whereas a 2-fold induction was observed for α-1b. The pattern and capacity of stimulation of α-1a through smoltification were similar for cortisol and DOC, whereas cortisol had an enhanced capacity to stimulate α-1b as compared to DOC. Even though there was no demonstrable change in cortisol or DOC sensitivity in the gill, the magnitude of the hormonal effects were seasonally dependent. This is the first report of DOC-induced effects on osmoregulatory targets in fish, thus indicating a role for DOC and MR signalling in osmoregulation.
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Affiliation(s)
- Pia Kiilerich
- Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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27
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Dual in vitro effects of cortisol on cell turnover in the medaka esophagus via the glucocorticoid receptor. Life Sci 2011; 88:239-45. [DOI: 10.1016/j.lfs.2010.11.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Revised: 10/19/2010] [Accepted: 11/15/2010] [Indexed: 01/26/2023]
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Johansen IB, Sandvik GK, Nilsson GE, Bakken M, Overli O. Cortisol receptor expression differs in the brains of rainbow trout selected for divergent cortisol responses. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2010; 6:126-32. [PMID: 21220219 DOI: 10.1016/j.cbd.2010.11.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 11/25/2010] [Accepted: 11/25/2010] [Indexed: 11/20/2022]
Abstract
In rainbow trout (Oncorhynchus mykiss), selection for divergent post-stress plasma cortisol levels has yielded low (LR)- and high (HR) responsive lines, differing in behavioural and physiological aspects of stress coping. For instance, LR fish display prolonged retention of a fear response and of previously learnt routines, compared to HR fish. This study aims at investigating putative central nervous system mechanisms controlling behaviour and memory retention. The stress hormone cortisol is known to affect several aspects of cognition, including memory retention. Cortisol acts through glucocorticoid receptors 1 and 2 (GR1 and 2) and a mineralcorticoid receptor (MR), all of which are abundantly expressed in the salmonid brain. We hypothesized that different expressions of MR and GRs in LR and HR trout brains could be involved in the observed differences in cognition. We quantified the mRNA expression of GR1, GR2 and MR in different brain regions of stressed and non-stressed LR and HR trout. The expression of MR was higher in LR than in HR fish in all brain parts investigated. This could be associated with reduced anxiety and enhanced memory retention in LR fish. MR and GR1 expression was also subject to negative regulation by stress in a site-specific manner.
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Affiliation(s)
- Ida B Johansen
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Aas, Norway.
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29
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Epithelial remodeling and claudin mRNA abundance in the gill and kidney of puffer fish (Tetraodon biocellatus) acclimated to altered environmental ion levels. J Comp Physiol B 2010; 181:219-38. [PMID: 20976602 DOI: 10.1007/s00360-010-0517-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 09/25/2010] [Accepted: 10/01/2010] [Indexed: 10/18/2022]
Abstract
In water of varying ion content, the gills and kidney of fishes contribute significantly to the maintenance of salt and water balance. However, little is known about the molecular architecture of the tight junction (TJ) complex and the regulation of paracellular permeability characteristics in these tissues. In the current studies, puffer fish (Tetraodon biocellatus) were acclimated to freshwater (FW), seawater (SW) or ion-poor freshwater (IPW) conditions. Following acclimation, alterations in systemic endpoints of hydromineral status were examined in conjunction with changes in gill and kidney epithelia morphology/morphometrics, as well as claudin TJ protein mRNA abundance. T. biocellatus were able to maintain endpoints of hydromineral status within relatively tight limits across the broad range of water ion content examined. Both gill and kidney tissue exhibited substantial alterations in morphology as well as claudin TJ protein mRNA abundance. These responses were particularly pronounced when comparing fish acclimated to SW versus those acclimated to IPW. TEM observations of IPW-acclimated fish gills revealed the presence of cells that exhibited the typical characteristics of gill mitochondria-rich cells (e.g. voluminous, Na(+)-K(+)-ATPase-immunoreactive, exposed to the external environment at the apical surface), but were not mitochondria-rich. To our knowledge, this type of cell has not previously been described in hyperosmoregulating fish gills. Furthermore, modifications in the morphometrics and claudin mRNA abundance of kidney tissue support the notion that spatial alterations in claudin TJ proteins along the nephron of fishes will likely play an important role in the regulation of salt and water balance in these organisms.
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Sloman KA. Exposure of ova to cortisol pre-fertilisation affects subsequent behaviour and physiology of brown trout. Horm Behav 2010; 58:433-9. [PMID: 20546742 DOI: 10.1016/j.yhbeh.2010.05.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 05/12/2010] [Accepted: 05/16/2010] [Indexed: 11/22/2022]
Abstract
Even before fertilisation, exposure of ova to high levels of stress corticosteroids can have significant effects on offspring in a variety of animals. In fish, high levels of cortisol in ovarian fluid can elicit morphological changes and reduce offspring survival. Whether there are other more subtle effects, including behavioural effects, of exposure to cortisol pre-fertilisation in fish is unclear. Here I demonstrate that a brief (3h) exposure of brown trout eggs to a physiologically relevant ( approximately 500 microg l(-)(1)) concentration of cortisol pre-fertilisation resulted in changes to developing offspring. Embryos exposed to cortisol pre-fertilisation displayed elevated oxygen consumption and ammonia excretion rates during development. After hatch, in contrast to the effects of cortisol exposure in juvenile fish, fish exposed to cortisol as eggs were more aggressive than control individuals and responded differently within a maze system. Thus, a transient exposure to corticosteroids in unfertilised eggs results in both physiological and behavioural alterations in fish.
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Affiliation(s)
- Katherine A Sloman
- School of Marine Science and Engineering, University of Plymouth, Plymouth, Devon, UK.
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31
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Rodela TM, McDonald MD, Walsh PJ, Gilmour KM. The regulatory role of glucocorticoid and mineralocorticoid receptors in pulsatile urea excretion of the gulf toadfish,Opsanus beta. J Exp Biol 2009; 212:1849-58. [DOI: 10.1242/jeb.026997] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYGulf toadfish, Opsanus beta, are one among a group of unusual teleosts that excrete urea as their predominant nitrogen end product in response to stressful conditions. Under conditions of crowding or confinement,fasted toadfish excrete the majority of their nitrogen waste in large pulses of urea (>90% of total nitrogen) lasting up to 3 h. An earlier study demonstrated that cortisol has an inhibitory influence on urea pulse size. The present study tested the hypothesis that cortisol mediates changes in urea pulse size in ureotelic toadfish through the glucocorticoid receptor (GR) and not the mineralocorticoid receptor (MR). In vivo pharmacological investigations were used to manipulate the corticosteroid system in crowded toadfish, including experimentally lowering plasma cortisol levels by the injection of metyrapone, blocking cortisol receptors through exposure to either RU-486 (GR antagonist) and spironolactone (MR antagonist), or through exogenous infusion of the tetrapod mineralocorticoid aldosterone (tetrapod MR agonist). The data demonstrate that lowering the activity of cortisol, either by inhibiting its synthesis or by blocking its receptor, resulted in a two- to threefold increase in pulse size with no accompanying change in pulse frequency. Treatment with spironolactone elicited a minor (∼1.5-fold)reduction in pulse size, as did aldosterone treatment, suggesting that the anti-mineralocorticoid spironolactone has an agonistic effect in a piscine system. In summary, the evidence suggests that urea transport mechanisms in pulsing toadfish are upregulated in response to low cortisol, mediated primarily by GRs, and to a lesser extent MRs.
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Affiliation(s)
- Tamara M. Rodela
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
| | - M. Danielle McDonald
- Rosenstiel School of Marine and Atmospheric Science, University of Miami,Miami, FL 33149, USA
| | - Patrick J. Walsh
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
| | - Kathleen M. Gilmour
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
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32
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Mitrovic D, Perry SF. The effects of thermally induced gill remodeling on ionocyte distribution and branchial chloride fluxes in goldfish (Carassius auratus). ACTA ACUST UNITED AC 2009; 212:843-52. [PMID: 19252001 DOI: 10.1242/jeb.025999] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Experiments were performed to evaluate the effects of temperature-induced changes in functional gill lamellar surface area on the distribution of ionocytes and branchial chloride fluxes in goldfish (Carassius auratus). In fish acclimated to warm water (25 degrees C), the ionocytes were scattered along the lamellae and within the interlamellar regions of the filament. In cold water (7 degrees C), the ionocytes were largely absent from the lamellae and filaments but instead were mostly confined to the outer regions of an interlamellar cell mass (ILCM) that formed within the interlamellar channels. Using a ;time-differential double fluorescent staining' technique, it was determined that in fish transferred from 25 degrees to 7 degrees C, the ionocytes on the outer edge of (and within) the ILCM originated predominantly from the migration of pre-existing ionocytes and to a lesser extent from the differentiation of progenitor cells. Despite the greater functional lamellar surface area in the warm-water-acclimated fish, there was no associated statistically significant increase in passive branchial Cl(-) efflux. Because the paracellular efflux of polyethylene glycol was increased 2.5-fold at the warmer temperature, it would suggest that goldfish specifically regulate (minimize) Cl(-) loss that otherwise would accompany the increasing functional lamellar surface area. In contrast to predictions, the numbers and sizes of individual ionocytes was inversely related to functional lamellar surface area resulting in a markedly greater ionocyte surface area in fish acclimated to cold water (5219+/-438 compared with 2103+/-180 microm(2) mm(-1) of filament). Paradoxically, the activity of Na(+)/K(+)-ATPase (as measured at room temperature) also was lower in the cold-water fish (0.43+/-0.06 compared with 1.28+/-0.15 micromol mg(-1) protein h(-1)) despite the greater numbers of ionocytes. There were no statistically significant differences in the rates of Cl(-) uptake in the two groups of fish despite the differences in ionocyte abundance. It is possible that to maintain normal rates of Cl(-) uptake, a greater ionocyte surface area is required in the cold-water fish that possess an ILCM because of the unfavorable positioning of the ionocytes on and within the ILCM, a structure lacking any obvious blood supply.
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Affiliation(s)
- D Mitrovic
- Department of Biology, 30 Marie Curie, Ottawa, ON, Canada, K1N 6N5
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33
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Sloman K, Baker D, Winberg S, Wilson R. Are there physiological correlates of dominance in natural trout populations? Anim Behav 2008. [DOI: 10.1016/j.anbehav.2008.06.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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34
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Reis-Santos P, McCormick SD, Wilson JM. Ionoregulatory changes during metamorphosis and salinity exposure of juvenile sea lamprey (Petromyzon marinus L.). ACTA ACUST UNITED AC 2008; 211:978-88. [PMID: 18310123 DOI: 10.1242/jeb.014423] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ammocoetes of the anadromous sea lamprey Petromyzon marinus L. spend many years in freshwater before metamorphosing and migrating to sea. Metamorphosis involves the radical transformation from a substrate-dwelling, filter feeder into a free-swimming, parasitic feeder. In the present work we examined osmoregulatory differences between ammocoetes and transformers (metamorphic juveniles), and the effects of salinity acclimation. We measured the expression of key ion-transporting proteins [Na(+)/K(+)-ATPase, vacuolar (V)-type H(+)-ATPase and carbonic anhydrase (CA)] as well as a number of relevant blood parameters (hematocrit, [Na(+)] and [Cl(-)]). In addition, immunofluorescence microscopy was used to identify and characterize the distributions of Na(+)/K(+)-ATPase, V-type H(+)-ATPase and CA immunoreactive cells in the gill. Ammocoetes did not survive in the experiments with salinities greater than 10 per thousand, whereas survival in high salinity (> or =25-35 per thousand) increased with increased degree of metamorphosis in transformers. Plasma [Na(+)] and [Cl(-)] of ammocoetes in freshwater was lower than transformers and increased markedly at 10 per thousand. In transformers, plasma ions increased only at high salinity (>25 per thousand). Branchial Na(+)/K(+)-ATPase levels were approximately tenfold higher in transformers compared to ammocoetes and salinity did not affect expression in either group. However, branchial H(+)-ATPase expression showed a negative correlation with salinity in both groups. Na(+)/K(+)-ATPase immunoreactivity was strongest in transformers and associated with clusters of cells in the interlamellar spaces. H(+)-ATPase (B subunit) immunoreactivity was localized to epithelial cells not expressing high Na(+)/K(+)-ATPase immunoreactivity and having a similar tissue distribution as carbonic anhydrase. The results indicate that branchial Na(+)/K(+)-ATPase and salinity tolerance increase in metamorphosing lampreys, and that branchial H(+)-ATPase is downregulated by salinity.
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Affiliation(s)
- Patrick Reis-Santos
- Centro Interdiscplinar de Investigação Marinha e Ambiental, Rua dos Bragas 289, 4050-123 Porto, Portugal
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35
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McCormick SD, Regish A, O'Dea MF, Shrimpton JM. Are we missing a mineralocorticoid in teleost fish? Effects of cortisol, deoxycorticosterone and aldosterone on osmoregulation, gill Na+,K+ -ATPase activity and isoform mRNA levels in Atlantic salmon. Gen Comp Endocrinol 2008; 157:35-40. [PMID: 18462736 DOI: 10.1016/j.ygcen.2008.03.024] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 03/20/2008] [Accepted: 03/26/2008] [Indexed: 11/21/2022]
Abstract
It has long been held that cortisol, acting through a single receptor, carries out both glucocorticoid and mineralocorticoid actions in teleost fish. The recent finding that fish express a gene with high sequence similarity to the mammalian mineralocorticoid receptor (MR) suggests the possibility that a hormone other than cortisol carries out some mineralocorticoid functions in fish. To test for this possibility, we examined the effect of in vivo cortisol, 11-deoxycorticosterone (DOC) and aldosterone on salinity tolerance, gill Na(+),K(+)-ATPase (NKA) activity and mRNA levels of NKA alpha 1a and alpha 1b in Atlantic salmon. Cortisol treatment for 6-14 days resulted in increased, physiological levels of cortisol, increased gill NKA activity and improved salinity tolerance (lower plasma chloride after a 24h seawater challenge), whereas DOC and aldosterone had no effect on either NKA activity or salinity tolerance. NKA alpha 1a and alpha 1b mRNA levels, which increase in response to fresh water and seawater acclimation, respectively, were both upregulated by cortisol, whereas DOC and aldosterone were without effect. Cortisol, DOC and aldosterone had no effect on gill glucocorticoid receptor GR1, GR2 and MR mRNA levels, although there was some indication of possible upregulation of GR1 by cortisol (p=0.07). The putative GR blocker RU486 inhibited cortisol-induced increases in salinity tolerance, NKA activity and NKA alpha 1a and alpha 1b transcription, whereas the putative MR blocker spironolactone had no effect. The results provide support that cortisol, and not DOC or aldosterone, is involved in regulating the mineralocorticoid functions of ion uptake and salt secretion in teleost fish.
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Affiliation(s)
- Stephen D McCormick
- USGS, Conte Anadromous Fish Research Center, One Migratory Way, PO Box 796, Turners Falls, MA 01376, USA.
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36
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Nilsen TO, Ebbesson LOE, Kiilerich P, Björnsson BT, Madsen SS, McCormick SD, Stefansson SO. Endocrine systems in juvenile anadromous and landlocked Atlantic salmon (Salmo salar): seasonal development and seawater acclimation. Gen Comp Endocrinol 2008; 155:762-72. [PMID: 17904138 DOI: 10.1016/j.ygcen.2007.08.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 08/06/2007] [Accepted: 08/10/2007] [Indexed: 10/22/2022]
Abstract
The present study compares developmental changes in plasma levels of growth hormone (GH), insulin-like growth factor I (IGF-I) and cortisol, and mRNA levels of their receptors and the prolactin receptor (PRLR) in the gill of anadromous and landlocked Atlantic salmon during the spring parr-smolt transformation (smoltification) period and following four days and one month seawater (SW) acclimation. Plasma GH and gill GH receptor (GHR) mRNA levels increased continuously during the spring smoltification period in the anadromous, but not in landlocked salmon. There were no differences in plasma IGF-I levels between strains, or any increase during smoltification. Gill IGF-I and IGF-I receptor (IGF-IR) mRNA levels increased in anadromous salmon during smoltification, with no changes observed in landlocked fish. Gill PRLR mRNA levels remained stable in both strains during spring. Plasma cortisol levels in anadromous salmon increased 5-fold in May and June, but not in landlocked salmon. Gill glucocorticoid receptor (GR) mRNA levels were elevated in both strains at the time of peak smoltification in anadromous salmon, while mineralocorticoid receptor (MR) mRNA levels remained stable. Only anadromous salmon showed an increase of gill 11beta-hydroxysteroid dehydrogenase type-2 (11beta-HSD2) mRNA levels in May. GH and gill GHR mRNA levels increased in both strains following four days of SW exposure in mid-May, whereas only the anadromous salmon displayed elevated plasma GH and GHR mRNA after one month in SW. Plasma IGF-I increased after four days in SW in both strains, decreasing in both strains after one month in SW. Gill IGF-I mRNA levels were only increased in landlocked salmon after 4days in SW. Gill IGF-IR mRNA levels in SW did not differ from FW levels in either strain. Gill PRLR mRNA did not change after four days of SW exposure, and decreased in both strains after one month in SW. Plasma cortisol levels did not change following SW exposure in either strain. Gill GR, 11beta-HSD2 and MR mRNA levels increased after four days in SW in both strains, whereas only the anadromous strain maintained elevated gill GR and 11beta-HSD2 mRNA levels after one month in SW. The results indicate that hormones and receptors of the GH and cortisol axes are present at significantly lower levels during spring development and SW acclimation in landlocked relative to anadromous salmon. These findings suggest that attenuation of GH and cortisol axes may, at least partially, result in reduced preparatory upregulation of key gill ion-secretory proteins, possibly a result of reduced selection pressure for marine adaptations in landlocked salmon.
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Affiliation(s)
- Tom O Nilsen
- Department of Biology, University of Bergen, Bergen High Technology Centre, N-5020, Norway.
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37
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Aluru N, Vijayan MM. Hepatic transcriptome response to glucocorticoid receptor activation in rainbow trout. Physiol Genomics 2007; 31:483-91. [PMID: 17848605 DOI: 10.1152/physiolgenomics.00118.2007] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cortisol, the principal corticosteroid in teleosts, is thought to play a key role in the metabolic adjustments critical for regaining homeostasis. However, the target tissue molecular mechanisms involved in this adaptive response to corticosteroid stimulation are still unclear. Cortisol signaling is mediated predominantly by the glucocorticoid receptor (GR), and previous studies have shown that RU486 (a GR antagonist) offsets corticosteroid signaling in teleosts. To elucidate the molecular basis of GR-mediated metabolic readjustments, we exposed primary culture of trout hepatocytes in vitro to cortisol (to mimic stressed levels seen in fish), RU486, or a combination of both for 24 h. The gene expression was analyzed using a low-density custom-made rainbow trout cDNA array enriched with endocrine-, metabolic-, and stress-related genes. The microarray results for select genes were further validated using quantitative real-time PCR. Cortisol treatment significantly increased glucose production in hepatocytes, and this response was blocked by RU486, confirming GR-mediated corticosteroid signaling. Cortisol also elevated GR transcript levels, and this response was abolished by RU486, whereas both cortisol and RU486, either alone or in combination, reduced GR protein content in trout hepatocytes. Cortisol treatment significantly modulated the expression of several genes known to be involved in intermediary metabolism, cellular stress response, reproduction, and xenobiotic metabolism. Most of these cortisol-mediated transcript changes were abolished in the presence of RU486, suggesting a key role for GR-specific signaling in this adaptive response. Taken together, our results suggest a key role for genomic cortisol signaling in the liver molecular reprogramming that is critical for coping with stress in fish.
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38
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Kiilerich P, Kristiansen K, Madsen SS. Hormone receptors in gills of smolting Atlantic salmon, Salmo salar: expression of growth hormone, prolactin, mineralocorticoid and glucocorticoid receptors and 11beta-hydroxysteroid dehydrogenase type 2. Gen Comp Endocrinol 2007; 152:295-303. [PMID: 17289045 DOI: 10.1016/j.ygcen.2006.12.018] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Revised: 11/29/2006] [Accepted: 12/26/2006] [Indexed: 11/17/2022]
Abstract
This is the first study to report concurrent dynamics in mRNA expression of growth hormone receptor (GHR), prolactin receptor (PRLR), gluco- and mineralocorticoid receptor (GR and MR) and the 11beta-hydroxysteroid dehydrogenase type-2 enzyme (11beta-HSD2) in Atlantic salmon (Salmo salar) gill during smoltification. Transcript levels were analysed by quantitative PCR in fresh water (FW) fish and after a 24-h salt water (SW) challenge. GHR transcript levels increased concurrent with gill Na(+),K(+)-ATPase activity in FW fish consistent with the SW-adaptive role of GH. SW-transfer induced an increased GHR expression levels in the early stages of smoltification but a decrease in expression at the peak of smoltification. PRLR transcript levels decreased steadily during smoltification in agreement with the recognized hyper-osmoregulatory role of PRL. Surprisingly, PRLR levels increased after SW transfer during the course of smoltification. GR mRNA levels were low early on during smoltification but increased at the peak of smoltification and remained high during de-smoltification, indicative of increased cortisol signalling at this point. Coherently, SW transfer increased GR levels to smolt levels prior to the smoltification peak. 11beta-HSD2 levels increased at the smoltification peak and MR levels increased during de-smoltification, suggesting a need for protection of MR from cortisol signalling during smoltification. This is supported by the fact that SW-transfer results in a profound up-regulation of 11beta-HSD2, whereas SW transfer down-regulates MR levels. The study concludes that GR and MR may have distinctive roles in developing hypo- and hyper-osmoregulatory mechanisms during smoltification and de-smoltification, respectively.
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Affiliation(s)
- Pia Kiilerich
- Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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39
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Acerete L, Balasch JC, Castellana B, Redruello B, Roher N, Canario AV, Planas JV, MacKenzie S, Tort L. Cloning of the glucocorticoid receptor (GR) in gilthead seabream (Sparus aurata). Differential expression of GR and immune genes in gilthead seabream after an immune challenge. Comp Biochem Physiol B Biochem Mol Biol 2007; 148:32-43. [PMID: 17544309 DOI: 10.1016/j.cbpb.2007.04.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 04/19/2007] [Accepted: 04/19/2007] [Indexed: 01/22/2023]
Abstract
In order to determine the cortisol response after an immune challenge in the gilthead seabream (Sparus aurata), a cortisol receptor (GR) was cloned, sequenced and its expression determined after lipopolysaccharide (LPS) treatment. To clone the gilthead seabream GR (sbGR), consecutive PCR amplifications and screening of a pituitary cDNA library were performed. We obtained a clone of 4586 bp encoding a 784aa protein. Northern blot analysis from head kidney, heart and intestine revealed that the full length sbGR mRNA was approximately 6.5 Kb. A LPS treatment, used as an acute stress model, was employed to characterise the expression of sbGR and some selected genes involved in the immune response (IL-1beta, TNF-alpha, Mx protein, cathepsin D and PPAR-gamma). All genes were expressed in all tissues examined and responses were tissue and time dependent revealing differential gene expression profiles after LPS administration. Furthermore, analysis of plasma cortisol levels after LPS injection, showed an acute response to inflammatory stress with a significant increase two and six h after injection, recovering to basal levels 12 h post-stress in all LPS concentrations tested.
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Affiliation(s)
- L Acerete
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Facultat de Ciències, 08193 Bellaterra, Spain.
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40
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Veillette PA, Merino M, Marcaccio ND, Garcia MM, Specker JL. Cortisol is necessary for seawater tolerance in larvae of a marine teleost the summer flounder. Gen Comp Endocrinol 2007; 151:116-21. [PMID: 17292366 DOI: 10.1016/j.ygcen.2006.12.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 11/22/2006] [Accepted: 12/26/2006] [Indexed: 11/20/2022]
Abstract
Larval-stage summer flounder (Paralichthys dentatus) were immersed in the corticosteroid-receptor blocker RU486 to test the effects of cortisol deficiency on salinity tolerance. Premetamorphic larvae held at 10 (near isosmotic) or 30 (hyperosmotic) parts per thousand ( per thousand) seawater survived well over 5d in 0, 0.012, or 0.12 microM RU486. However, at concentrations of 1.2 or 3.6 microM RU486, mortality was significantly greater for larvae in 30 per thousand compared to larvae in 10 per thousand. In a separate experiment, the ability of RU486 to inhibit tolerance to hyperosmotic medium (30 per thousand) was confirmed; immersion at 1.2 microM RU486 induced mortality of larvae in the metamorphic climax stage held at 30 per thousand, but not 0 or 10 per thousand. Mortality due to RU486 in pre- or prometamorphic stage larvae was prevented by concurrent immersion in cortisol at concentrations approximately 10-200 times greater than RU486, indicating that the action of RU486 was specific to antagonism of cortisol. The efficacy of 1.2 microM RU486 in reducing survival in 30 per thousand was found to be stage-dependent and exhibited the following hierarchy for fastest time to 50% mortality: prometamorphosis>metamorphic climax>premetamorphosis. In a 5-d pretreatment of pre- or prometamorphic larvae by immersion in 20 microM cortisol and/or 0.12 microM RU486 at 30 per thousand, only RU486 had a limited effect on decreasing survival when larvae were challenged with abrupt exposure to 50 per thousand. In total, the results evidence for the first time a necessary role for cortisol in seawater tolerance of a larval marine teleost.
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Affiliation(s)
- Philip A Veillette
- Graduate School of Oceanography, University of Rhode Island, 218 South Ferry Rd., Narragansett, RI 02882-1197, USA.
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41
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Rogerson FM, Yao YZ, Elsass RE, Dimopoulos N, Smith BJ, Fuller PJ. A critical region in the mineralocorticoid receptor for aldosterone binding and activation by cortisol: evidence for a common mechanism governing ligand binding specificity in steroid hormone receptors. Mol Endocrinol 2007; 21:817-28. [PMID: 17284665 DOI: 10.1210/me.2006-0246] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The amino acids that confer aldosterone binding specificity to the mineralocorticoid receptor (MR) remain to be determined. We had previously analyzed a panel of chimeras created between the MR and the glucocorticoid receptor and determined that amino acids 804-874 of the MR ligand binding domain are critical for aldosterone binding. In the present study a further series of chimeras was created within this region. The chimeras were analyzed by a transactivation assay and [(3)H]aldosterone binding, and the critical region was narrowed down to amino acids 820-844. Site-directed mutagenesis was used to create single and multiple amino acid substitutions in this region. These studies identified 12 of the 16 amino acids that differ in the MR and the glucocorticoid receptor in this region as being critical to conferring aldosterone responsivity. The amino acids that differ in the region 820-844 lie on the surface of the molecule and, therefore, it appears that MR ligand binding selectivity is conferred by residues that do not form part of the ligand binding pocket. Other studies have found that the corresponding regions of the androgen and glucocorticoid receptors are critical for the binding of natural and synthetic ligands, suggesting a common mechanism governing ligand binding specificity. The new chimeras also displayed, as previously reported, a dissociation between cortisol binding and transactivation and, intriguingly, only those that bound aldosterone with high affinity were activated by cortisol, suggesting a common mechanism that underlies specificity of aldosterone binding and the ability of cortisol to activate the MR.
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Affiliation(s)
- Fraser M Rogerson
- Prince Henry's Institute of Medical Research, P.O. Box 5152, Clayton 3168, Victoria, Australia
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42
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Singer TD, Raptis S, Sathiyaa R, Nichols JW, Playle RC, Vijayan MM. Tissue-specific modulation of glucocorticoid receptor expression in response to salinity acclimation in rainbow trout. Comp Biochem Physiol B Biochem Mol Biol 2006; 146:271-8. [PMID: 17215158 DOI: 10.1016/j.cbpb.2006.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Revised: 11/03/2006] [Accepted: 11/04/2006] [Indexed: 11/25/2022]
Abstract
While studies clearly point to a role for cortisol signaling in seawater adaptation, very little is known about salinity impact on glucocorticoid receptor (GR) expression in fish. To this end, we investigated the temporal GR expression in the gill and liver of rainbow trout (Oncorhynchus mykiss) to salinity exposure. Trout were subjected to gradual salinity increases (11 ppt for 1 d, 17 ppt for 2 d and 23 ppt for 2 d) over a five day period. Gill Na(+), K(+)-ATPase alpha-subunit mRNA showed a transient elevation with salinity exposure, while gill cystic fibrosis transmembrane conductance regulator mRNA was not significantly affected by salinity. Liver PEPCK transcript levels showed a transient increase at day 1, but not at day 3 or day 5 of salinity exposure, while the activity of this enzyme was significantly depressed at all time points. Liver glycogen content was also significantly reduced by salinity exposure compared to the freshwater group. Gill GR transcript levels were 3-fold greater upon salinity exposure and this level was maintained over the 5 day period, while gill GR protein content remained unchanged except for a significant drop at day 1 of salinity exposure. Liver GR transcript levels showed no significant change with salinity exposure, while GR protein content was transiently elevated at day 3, but not at day 1 or day 5 of salinity exposure. The tissue-specific GR transcript response in the gill leads us to hypothesize a role for osmosensory signal transduction pathway in the regulation of GR expression in fish. Collectively, salinity exposure modulates GR expression and glucocorticoid signaling in rainbow trout.
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Affiliation(s)
- Thomas D Singer
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
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43
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Shahsavarani A, Perry SF. Hormonal and environmental regulation of epithelial calcium channel in gill of rainbow trout (Oncorhynchus mykiss). Am J Physiol Regul Integr Comp Physiol 2006; 291:R1490-8. [PMID: 16763083 DOI: 10.1152/ajpregu.00026.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We indirectly tested the idea that the epithelial Ca2+channel (ECaC) of the trout gill is regulated in an appropriate manner to adjust rates of Ca2+uptake. This was accomplished by assessing the levels of gill ECaC mRNA and protein in fish exposed to treatments known to increase or decrease Ca2+uptake capacity. Exposure of trout to soft water ([Ca2+] = 20–30 nmol/l) for 5 days (a treatment known to increase Ca2+uptake capacity) caused a significant increase in ECaC mRNA levels and an increase in ECaC protein expression. The inducement of hypercalcemia by infusing fish with CaCl2(a treatment known to reduce Ca2+uptake) was associated with a significant decrease in ECaC mRNA levels, yet protein levels were unaltered. ECaC mRNA and protein expression were increased in fish treated with the hypercalcemic hormone cortisol. Finally, exposure of trout to 48 h of hypercapnia (∼7.5 mmHg, a treatment known to increase Ca2+uptake capacity) elicited an ∼100-fold increase in the levels of ECaC mRNA and a significant increase in protein expression. Immunocytochemical analysis of the gills from hypercapnic fish suggested a marked increase in the apical expression of ECaC on pavement cells and a subpopulation of mitochondria-rich cells. The results of this study provide evidence that Ca2+uptake rates are, in part, regulated by the numbers of apical membrane Ca2+channels that, in turn, modulate the inward flux of Ca2+into gill epithelial cells.
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Affiliation(s)
- Arash Shahsavarani
- Dept. of Biology, Center for Advanced Research in Environmental Genomics, Univ. of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5 Canada
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Takahashi H, Takahashi A, Sakamoto T. In vivo effects of thyroid hormone, corticosteroids and prolactin on cell proliferation and apoptosis in the anterior intestine of the euryhaline mudskipper (Periophthalmus modestus). Life Sci 2006; 79:1873-80. [PMID: 16857212 DOI: 10.1016/j.lfs.2006.06.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Revised: 05/26/2006] [Accepted: 06/13/2006] [Indexed: 11/30/2022]
Abstract
We have previously shown that anterior intestinal epithelium of the euryhaline mudskipper (Periophthalmus modestus) undergoes apoptosis during seawater (SW) acclimation, whereas elevated cell proliferation was observed in freshwater (FW)-acclimated fish. To understand the possible endocrine regulation of the gastrointestinal cell turnover during salinity acclimation, we examined the ratios of apoptotic and proliferating cells in the anterior intestine of one-third SW-acclimated mudskipper treated with triiodothyronine (T3), cortisol, 11-deoxycorticosterone (DOC, the putative teleostean mineralocorticoid), or prolactin (PRL). In situ nick end labeling of genomic DNA (TUNEL) and immunohistochemistry of proliferating cells nuclear antigen (PCNA) were used as indicators of apoptosis and cell proliferations, respectively. Cortisol significantly elevated apoptosis (P<0.05) in the epithelia and connective tissues and also stimulated the epithelial cell proliferation (P<0.05). PRL induced epithelial cell proliferation (P<0.05), but did not affect apoptotic status of the intestinal epithelium. Neither T3 nor DOC had any impact on cell proliferation or apoptosis. Together, our results suggest a role for cortisol and PRL in the regulation of anterior intestinal epithelial turnover during salinity acclimation in this species.
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Affiliation(s)
- Hideya Takahashi
- Ushimado Marine Laboratory, Graduate School of Natural Science and Technology, Okayama University, Ushimado, 130-17, Kashino, Ushimado, Setouchi, Japan.
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45
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Metz JR, Peters JJM, Flik G. Molecular biology and physiology of the melanocortin system in fish: a review. Gen Comp Endocrinol 2006; 148:150-62. [PMID: 16620815 DOI: 10.1016/j.ygcen.2006.03.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Revised: 02/27/2006] [Accepted: 03/05/2006] [Indexed: 10/24/2022]
Abstract
The melanocortin system consists of melanocortin peptides derived from the proopiomelanocortin gene (in particular adrenocorticotropic hormone, ACTH, and melanocyte-stimulating hormones, MSH) and five melanocortin receptor subtypes (MC1R-MC5R). Knowledge of the melanocortin system in fish is still limited, but information on the receptor part of the system is very rapidly growing. The melanocortin receptors (MCRs) have been recently cloned from several species of fish. The amino acid sequences appear remarkably well conserved. Pharmacological characterisation studies of the first identified piscine MCRs indicate that ACTH may be the original ligand for the MCRs, while the MSH peptides gained specialised functions in the course of evolution. Considering the tissue distribution of the MCRs, there are two distinctions between mammals and fish: where in mammals the MC4R is exclusively expressed in the central nervous system, in the fish species examined so far it is also peripherally expressed. It does however, alike the situation in mammals, likely play a key role in the central regulation of food intake and energy balance. Not only the MCRs, but also many other factors involved herewith, have been found in fish and roughly appear to function similarly as in mammals. The second difference is the distribution of the MC5R, which appears less widely expressed in fish than in mammals. Considering the available data it is predicted that, in mammals and fish alike, skin colouration is mediated via MC1R and steroidogenesis via MC2R. This review provides a short overview of the basic molecular characteristics, pharmacology, and tissue distribution of the MCRs in the fish investigated up to now, as well as their physiological role in the processes of skin colouration, steroidogenesis, and feeding behaviour.
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Affiliation(s)
- Juriaan R Metz
- Department Organismal Animal Physiology, Institute for Neuroscience, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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Prunet P, Sturm A, Milla S. Multiple corticosteroid receptors in fish: from old ideas to new concepts. Gen Comp Endocrinol 2006; 147:17-23. [PMID: 16545810 DOI: 10.1016/j.ygcen.2006.01.015] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 12/23/2005] [Accepted: 01/05/2006] [Indexed: 10/24/2022]
Abstract
The effect of corticosteroid hormones in fish are mediated through intracellular receptors that act as ligand-binding transcription factors. Many studies have been devoted to cortisol binding using radiolabeled ligand in fish and allowed characterization of a single class of high affinity binding sites in various tissues. Molecular characterization of cortisol receptors has only been initiated recently by cloning the different receptor forms: Following a isolation of a first glucocorticoid receptor (GR), a mineralocorticoid receptor (MR) was described and the presence of various GR isoforms was recently reported. Sequence comparison and phylogenetic analysis of these sequences confirm that fish possess both GR and MR and that GR gene is duplicated. The importance of these various corticosteroid receptor forms is also illustrated by analysis of their transcriptional activity. When tested in human cell lines, these receptors showed functionally distinct actions on GR-sensitive promotors, thus suggesting a more complicated corticosteroid signaling system than initially anticipated from binding studies. These results also suggest that, whereas cortisol is certainly the physiological ligand for GR, this may not be the case for MR which showed high sensitivity for deoxycorticosterone (DOC) and aldosterone. As this last hormone is probably absent in fish, these results raise the question as to whether DOC could be a physiological ligand for MR in fish. Information on DOC effect in fish is very scarce and clarification of the differential osmoregulatory roles of cortisol and DOC in fish needs ellucidation. This will require analysis of all actors of the corticosteroid signaling system at pre-receptor, receptor, and post-receptor levels.
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Affiliation(s)
- P Prunet
- INRA SCRIBE, IFR 140, Campus de Beaulieu, 35042 Rennes Cedex, France.
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Doyon C, Leclair J, Trudeau VL, Moon TW. Corticotropin-releasing factor and neuropeptide Y mRNA levels are modified by glucocorticoids in rainbow trout, Oncorhynchus mykiss. Gen Comp Endocrinol 2006; 146:126-35. [PMID: 16338231 DOI: 10.1016/j.ygcen.2005.10.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Revised: 09/16/2005] [Accepted: 10/16/2005] [Indexed: 11/28/2022]
Abstract
The primary stress response involves neuronal activation that ultimately leads to the release of glucocorticoids. Circulating glucocorticoids are thought to influence their own synthesis and release through a negative feedback mechanism that inhibits the activity of the hypothalamic and pituitary components of the stress axis. This study was designed to address the hypothesis that glucocorticoids modify corticotropin-releasing factor (CRF) and neuropeptide Y (NPY) mRNA levels in the rainbow trout (Oncorhynchus mykiss) brain. Cortisol implantation significantly reduced CRF1 and NPY mRNA levels in fish exposed to an isolation stress. In contrast, cortisol implantation did not prevent the stress-induced elevation of CRF1 and NPY mRNA levels during confinement. Treatment with the glucocorticoid receptor antagonist RU-486 reduced CRF1 mRNA levels in both isolated and confined fish, but had no effect on NPY mRNA. Although the cytochrome P450 inhibitor metyrapone reduced ACTH-induced cortisol secretion in vitro, plasma cortisol levels were elevated in isolated trout treated with metyrapone. Nevertheless, metyrapone implantation increased CRF1 and NPY mRNA levels in confined fish. Together, these results implicate cortisol as a modulator of CRF and NPY mRNA levels in the preoptic area of the trout brain, but that cortisol is only one such regulating mechanism.
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Affiliation(s)
- Christian Doyon
- Centre for Advanced Research in Environmental Genomics (CAREG), Department of Biology, University of Ottawa, Ottawa, Ont., Canada K1N 6N5.
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Scott GR, Keir KR, Schulte PM. Effects of spironolactone and RU486 on gene expression and cell proliferation after freshwater transfer in the euryhaline killifish. J Comp Physiol B 2005; 175:499-510. [PMID: 16088394 DOI: 10.1007/s00360-005-0014-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Revised: 04/20/2005] [Accepted: 06/14/2005] [Indexed: 10/25/2022]
Abstract
We have explored the possible mechanisms by which mineralocorticoid (MR) and glucocorticoid (GR) receptors regulate the response to freshwater transfer in the gills of the euryhaline killifish Fundulus heteroclitus. Killifish were implanted with RU486 (GR antagonist) or spironolactone (MR antagonist) at doses of 0.1-1.0 mg g(-1), and subsequently transferred from 10 per thousand brackish water to freshwater. Compared to brackish water sham fish, mRNA expression of CFTR and NKCC1 decreased in the gills of sham fish transferred to freshwater, whereas Na(+), K(+)-ATPase alpha(1a) mRNA expression and alpha protein abundance, as well as cell proliferation (detected using BrdU) increased. Spironolactone inhibited the normal increase in cell proliferation and Na(+), K(+)-ATPase expression after freshwater transfer. RU486 increased plasma cortisol levels and may have slightly inhibited Na(+), K(+)-ATPase activity, but did not change alpha(1a ) expression. RU486 had no effect on cell proliferation in the non-lamellar region of the gills, but increased proliferation in the lamellar region. Neither antagonist inhibited the suppression of CFTR or NKCC1 expression after freshwater transfer. Glucocorticoid receptor expression was reduced in all sham and antagonist treatments compared to untreated controls, but no other consistent differences were observed. The effects of spironolactone suggest that MR is important for regulating ion transport in killifish gills after freshwater transfer.
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Affiliation(s)
- Graham R Scott
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
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49
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Nebel C, Romestand B, Nègre-Sadargues G, Grousset E, Aujoulat F, Bacal J, Bonhomme F, Charmantier G. Differential freshwater adaptation in juvenile sea-bassDicentrarchus labrax: involvement of gills and urinary system. J Exp Biol 2005; 208:3859-71. [PMID: 16215214 DOI: 10.1242/jeb.01853] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYThe effects of long-term freshwater acclimatization were investigated in juvenile sea-bass Dicentrarchus labrax to determine whether all sea-bass juveniles are able to live in freshwater and to investigate the physiological basis of a successful adaptation to freshwater. This study particularly focused on the ability of sea-bass to maintain their hydromineral balance in freshwater and on their ion (re)absorbing abilities through the gills and kidneys. Two different responses were recorded after a long-term freshwater acclimatization. (1) Successfully adapted sea-bass displayed standard behavior; their blood osmolality was maintained almost constant after the freshwater challenge, attesting to their efficient hyperosmoregulation. Their branchial and renal Na+/K+-ATPase abundance and activity were high compared to seawater fish due to a high number of branchial ionocytes and to the involvement of the urinary system in active ion reabsorption, producing hypotonic urine. (2) Sea-bass that had not successfully adapted to freshwater were recognized by abnormal schooling behavior. Their blood osmolality was low (30% lower than in the successfully adapted sea-bass), which is a sign of acute osmoregulatory failure. High branchial Na+/K+-ATPase abundance and activity compared to successfully adapted fish were coupled to a proliferation of gill chloride cells, whose ultrastructure did not display pathological signs. The large surface used by the gill chloride cells might negatively interfere with respiratory gas exchanges. In their urinary system, enzyme abundance and activity were low, in accordance with the observed lower density of the kidney tubules. Urine was isotonic to blood in unsuccessfully adapted fish, ruling out any participation of the kidney in hyperosmoregulation. The kidney failure seems to generate a compensatory ion absorption through increased gill activity, but net ion loss through urine seems higher than ion absorption by the gills, leading to lower hyper-osmoregulatory performance and to death.
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Affiliation(s)
- Catherine Nebel
- Laboratoire Génome, Populations, Interactions, Adaptation, UMR 5171, Université Montpellier II, Place E. Bataillon, 34095 Montpellier, Cedex 05, France.
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50
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Metz JR, Geven EJW, van den Burg EH, Flik G. ACTH, α-MSH, and control of cortisol release: cloning, sequencing, and functional expression of the melanocortin-2 and melanocortin-5 receptor in Cyprinus carpio. Am J Physiol Regul Integr Comp Physiol 2005; 289:R814-26. [PMID: 15890786 DOI: 10.1152/ajpregu.00826.2004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cortisol release from fish head kidney during the acute phase of the stress response is controlled by the adrenocorticotropic hormone (ACTH) from the pituitary pars distalis (PD). Alpha-melanocyte-stimulating hormone (α-MSH) and β-endorphin, from the pars intermedia (PI), have been implicated in cortisol release during the chronic phase. The present study addresses the regulation of cortisol release by ACTH and α-MSH in common carp ( Cyprinus carpio) and includes characterization of their receptors, namely, the melanocortin-2 and melanocortin-5 receptors (MC2R and MC5R). We could not demonstrate corticotropic activity of α-MSH, β-endorphin, and combinations of these. We do show a corticotrope in the PI, but its identity is as yet uncertain. Carp restrained for 1 and 7 days showed elevated plasma cortisol and α-MSH levels; cortisol is still elevated but lower at day 7 than day 1 of restraint. Interrenal response capacity is unaffected, as estimated by stimulation with a maximum dose ACTH in a superfusion setup. MC2R and MC5R appear phylogenetically well conserved. MC2R is predominantly expressed in head kidney; a low abundance was found in spleen and kidney. MC5R is expressed in brain, pituitary PD, kidney, and skin. Quantitative PCR analysis of MC2R and MC5R expression in the head kidney of restrained fish reveals MC2R mRNA downregulation after 7 days restraint, in line with lower plasma cortisol levels seen. We discuss regulation of corticosteroid production from a phylogenetic perspective. We propose that increased levels of α-MSH exert a positive feedback on hypothalamic corticotropin-releasing hormone release to sustain a mild stress axis activity.
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MESH Headings
- Adrenocorticotropic Hormone/metabolism
- Adrenocorticotropic Hormone/pharmacology
- Amino Acid Sequence
- Animals
- Base Sequence
- Carps
- Cloning, Molecular
- Hydrocortisone/blood
- Hydrocortisone/metabolism
- Kidney/metabolism
- Molecular Sequence Data
- Phylogeny
- Receptor, Melanocortin, Type 2/genetics
- Receptor, Melanocortin, Type 2/metabolism
- Receptors, Corticotropin/genetics
- Receptors, Corticotropin/metabolism
- Receptors, Melanocortin
- Restraint, Physical
- Stress, Physiological/etiology
- Stress, Physiological/metabolism
- Tissue Distribution
- alpha-MSH/blood
- alpha-MSH/metabolism
- alpha-MSH/pharmacology
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Affiliation(s)
- Juriaan R Metz
- Dept. Organismal Animal Physiology, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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