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Malintha GHT, Woo DW, Celino-Brady FT, Seale AP. Temperature modulates the osmosensitivity of tilapia prolactin cells. Sci Rep 2023; 13:20217. [PMID: 37980366 PMCID: PMC10657356 DOI: 10.1038/s41598-023-47044-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 11/08/2023] [Indexed: 11/20/2023] Open
Abstract
In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different combinations of temperatures (20, 26 and 32 °C) and osmolalities (280, 330 and 420 mOsm/kg) for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188, but not Prl177, was suppressed at 20 °C. In SW fish, mRNA expression of prl188 increased with rising temperatures at lower osmolalities, while and prl177 decreased at 32 °C and higher osmolalities. In Prl cells of SW-acclimated tilapia incubated in hyperosmotic media, the expressions of Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4,decreased at 32 °C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32 °C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity.
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Affiliation(s)
- G H T Malintha
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI, 96822, USA
| | - Daniel W Woo
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI, 96822, USA
| | - Fritzie T Celino-Brady
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI, 96822, USA
- Division of Genetics, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, 97006, USA
| | - Andre P Seale
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI, 96822, USA.
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Hewage TMG, Woo DW, Celino-Brady FT, Seale AP. Temperature modulates the osmosensitivity of tilapia prolactin cells. RESEARCH SQUARE 2023:rs.3.rs-2524830. [PMID: 36909603 PMCID: PMC10002831 DOI: 10.21203/rs.3.rs-2524830/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different temperature (20, 26 and 32°C) and osmolality (280, 330 and 420 mOsm/kg) combinations for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188 was inhibited at 20°C. In SW fish, mRNA expression of prl188 and prl177 showed direct and inverse relationships with temperature, respectively. In SW-acclimated tilapia Prl cells incubated in hyperosmotic media, Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4, were inhibited at 32°C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32°C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity.
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Rahmad Royan M, Siddique K, Nourizadeh-Lillabadi R, Weltzien FA, Henkel C, Fontaine R. Functional and developmental heterogeneity of pituitary lactotropes in medaka. Gen Comp Endocrinol 2023; 330:114144. [PMID: 36270338 DOI: 10.1016/j.ygcen.2022.114144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/06/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022]
Abstract
In fish, prolactin-producing cells (lactotropes) are located in the anterior part of the pituitary and play an essential role in osmoregulation. However, small satellite lactotrope clusters have been described in other parts of the pituitary in several species. The functional and developmental backgrounds of these satellite clusters are not known. We recently discovered two distinct prolactin-expressing cell types in Japanese medaka (Oryzias latipes), a euryhaline species, using single cell transcriptomics. In the present study, we characterize these two transcriptomically distinct lactotrope cell types and explore the hypothesis that they represent spatially distinct cell clusters, as found in other species. Single cell RNA sequencing shows that one of the two lactotrope cell types exhibits an expression profile similar to that of stem cell-like folliculo-stellate cell populations. Using in situ hybridization, we show that the medaka pituitary often develops additional small satellite lactotrope cell clusters, like in other teleost species. These satellite clusters arise early during development and grow in cell number throughout life regardless of the animal's sex. Surprisingly, our data do not show a correspondence between the stem cell-like lactotropes and these satellite lactotrope clusters. Instead, our data support a scenario in which the stem cell-like lactotropes are an intrinsic stage in the development of every spatially distinct lactotrope cluster. In addition, lactotrope activity in both spatially distinct lactotrope clusters decreases when environmental salinity increases, supporting their role in osmoregulation. However, this decrease appears weaker in the satellite lactotrope cell clusters, suggesting that these lactotropes are regulated differently.
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Affiliation(s)
- Muhammad Rahmad Royan
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Khadeeja Siddique
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | | - Finn-Arne Weltzien
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Christiaan Henkel
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway.
| | - Romain Fontaine
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway.
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Seale AP, Malintha GHT, Celino-Brady FT, Head T, Belcaid M, Yamaguchi Y, Lerner DT, Baltzegar DA, Borski RJ, Stoytcheva ZR, Breves JP. Transcriptional regulation of prolactin in a euryhaline teleost: Characterisation of gene promoters through in silico and transcriptome analyses. J Neuroendocrinol 2020; 32:e12905. [PMID: 32996203 PMCID: PMC8612711 DOI: 10.1111/jne.12905] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 07/31/2020] [Accepted: 08/26/2020] [Indexed: 12/20/2022]
Abstract
The sensitivity of prolactin (Prl) cells of the Mozambique tilapia (Oreochromis mossambicus) pituitary to variations in extracellular osmolality enables investigations into how osmoreception underlies patterns of hormone secretion. Through the actions of their main secretory products, Prl cells play a key role in supporting hydromineral balance of fishes by controlling the major osmoregulatory organs (ie, gill, intestine and kidney). The release of Prl from isolated cells of the rostral pars distalis (RPD) occurs in direct response to physiologically relevant reductions in extracellular osmolality. Although the particular signal transduction pathways that link osmotic conditions to Prl secretion have been identified, the processes that underlie hyposmotic induction of prl gene expression remain unknown. In this short review, we describe two distinct tilapia gene loci that encode Prl177 and Prl188 . From our in silico analyses of prl177 and prl188 promoter regions (approximately 1000 bp) and a transcriptome analysis of RPDs from fresh water (FW)- and seawater (SW)-acclimated tilapia, we propose a working model for how multiple transcription factors link osmoreceptive processes with adaptive patterns of prl177 and prl188 gene expression. We confirmed via RNA-sequencing and a quantitative polymerase chain reaction that multiple transcription factors emerging as predicted regulators of prl gene expression are expressed in the RPD of tilapia. In particular, gene transcripts encoding pou1f1, stat3, creb3l1, pbxip1a and stat1a were highly expressed; creb3l1, pbxip1a and stat1a were elevated in fish acclimated to SW vs FW. Combined, our in silico and transcriptome analyses set a path for resolving how adaptive patterns of Prl secretion are achieved via the integration of osmoreceptive processes with the control of prl gene transcription.
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Affiliation(s)
- Andre P. Seale
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | | | - Fritzie T. Celino-Brady
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | - Tony Head
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | - Mahdi Belcaid
- Hawai’i Institute of Marine Biology, University of Hawai’i at Mānoa, Kaneohe, HI, USA
| | - Yoko Yamaguchi
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, Japan
| | - Darren T. Lerner
- University of Hawai’i Sea Grant College Program, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | - David A. Baltzegar
- Genomic Sciences Laboratory, Office of Research and Innovation, North Carolina State University, Raleigh, NC, USA
| | - Russell J. Borski
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - Zoia R. Stoytcheva
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai’i at Mānoa, Honolulu, HI, USA
| | - Jason P. Breves
- Department of Biology, Skidmore College, Saratoga Springs, NY, USA
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Breves JP, Popp EE, Rothenberg EF, Rosenstein CW, Maffett KM, Guertin RR. Osmoregulatory actions of prolactin in the gastrointestinal tract of fishes. Gen Comp Endocrinol 2020; 298:113589. [PMID: 32827513 DOI: 10.1016/j.ygcen.2020.113589] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/17/2020] [Accepted: 08/14/2020] [Indexed: 02/07/2023]
Abstract
In fishes, prolactin (Prl) signaling underlies the homeostatic regulation of hydromineral balance by controlling essential solute and water transporting functions performed by the gill, gastrointestinal tract, kidney, urinary bladder, and integument. Comparative studies spanning over 60 years have firmly established that Prl promotes physiological activities that enable euryhaline and stenohaline teleosts to reside in freshwater environments; nonetheless, the specific molecular and cellular targets of Prl in ion- and water-transporting tissues are still being resolved. In this short review, we discuss how particular targets of Prl (e.g., ion cotransporters, tight-junction proteins, and ion pumps) confer adaptive functions to the esophagus and intestine. Additionally, in some instances, Prl promotes histological and functional transformations within esophageal and intestinal epithelia by regulating cell proliferation. Collectively, the demonstrated actions of Prl in the gastrointestinal tract of teleosts indicate that Prl operates to promote phenotypes supportive of freshwater acclimation and to inhibit phenotypes associated with seawater acclimation. We conclude our review by underscoring that future investigations are warranted to determine how growth hormone/Prl-family signaling evolved in basal fishes to support the gastrointestinal processes underlying hydromineral balance.
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Affiliation(s)
- Jason P Breves
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA.
| | - Emily E Popp
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Eva F Rothenberg
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Clarence W Rosenstein
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Kaitlyn M Maffett
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Rebecca R Guertin
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
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Dobolyi A, Oláh S, Keller D, Kumari R, Fazekas EA, Csikós V, Renner É, Cservenák M. Secretion and Function of Pituitary Prolactin in Evolutionary Perspective. Front Neurosci 2020; 14:621. [PMID: 32612510 PMCID: PMC7308720 DOI: 10.3389/fnins.2020.00621] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 05/19/2020] [Indexed: 12/16/2022] Open
Abstract
The hypothalamo-pituitary system developed in early vertebrates. Prolactin is an ancient vertebrate hormone released from the pituitary that exerts particularly diverse functions. The purpose of the review is to take a comparative approach in the description of prolactin, its secretion from pituitary lactotrophs, and hormonal functions. Since the reproductive and osmoregulatory roles of prolactin are best established in a variety of species, these functions are the primary subjects of discussion. Different types of prolactin and prolactin receptors developed during vertebrate evolution, which will be described in this review. The signal transduction of prolactin receptors is well conserved among vertebrates enabling us to describe the whole subphylum. Then, the review focuses on the regulation of prolactin release in mammals as we have the most knowledge on this class of vertebrates. Prolactin secretion in response to different reproductive stimuli, such as estrogen-induced release, mating, pregnancy and suckling is detailed. Reproduction in birds is different from that in mammals in several aspects. Prolactin is released during incubation in avian species whose regulation and functional significance are discussed. Little information is available on prolactin in reptiles and amphibians; therefore, they are mentioned only in specific cases to explain certain evolutionary aspects. In turn, the osmoregulatory function of prolactin is well established in fish. The different types of pituitary prolactin in fish play particularly important roles in the adaptation of eutherian species to fresh water environments. To achieve this function, prolactin is released from lactotrophs in hyposmolarity, as they are directly osmosensitive in fish. In turn, the released prolactin acts on branchial epithelia, especially ionocytes of the gill to retain salt and excrete water. This review will highlight the points where comparative data give new ideas or suggest new approaches for investigation in other taxa.
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Affiliation(s)
- Arpád Dobolyi
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Szilvia Oláh
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Dávid Keller
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Rashmi Kumari
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Emese A. Fazekas
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Vivien Csikós
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Éva Renner
- Human Brain Tissue Bank and Microdissection Laboratory, Semmelweis University, Budapest, Hungary
| | - Melinda Cservenák
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
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Differential Expression and Localization of Branchial AQP1 and AQP3 in Japanese Medaka ( Oryzias latipes). Cells 2019; 8:cells8050422. [PMID: 31072010 PMCID: PMC6562476 DOI: 10.3390/cells8050422] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/03/2019] [Accepted: 05/06/2019] [Indexed: 01/08/2023] Open
Abstract
Aquaporins (AQPs) facilitate transmembrane water and solute transport, and in addition to contributing to transepithelial water transport, they safeguard cell volume homeostasis. This study examined the expression and localization of AQP1 and AQP3 in the gills of Japanese medaka (Oryzias latipes) in response to osmotic challenges and osmoregulatory hormones, cortisol, and prolactin (PRL). AQP3 mRNA was inversely regulated in response to salinity with high levels in ion-poor water (IPW), intermediate levels in freshwater (FW), and low levels in seawater (SW). AQP3 protein levels decreased upon SW acclimation. By comparison, AQP1 expression was unaffected by salinity. In ex vivo gill incubation experiments, AQP3 mRNA was stimulated by PRL in a time- and dose-dependent manner but was unaffected by cortisol. In contrast, AQP1 was unaffected by both PRL and cortisol. Confocal microscopy revealed that AQP3 was abundant in the periphery of gill filament epithelial cells and co-localized at low intensity with Na+,K+-ATPase in ionocytes. AQP1 was present at a very low intensity in most filament epithelial cells and red blood cells. No epithelial cells in the gill lamellae showed immunoreactivity to AQP3 or AQP1. We suggest that both AQPs contribute to cellular volume regulation in the gill epithelium and that AQP3 is particularly important under hypo-osmotic conditions, while expression of AQP1 is constitutive.
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Acclimation to different environmental salinities induces molecular endocrine changes in the GH/IGF-I axis of juvenile gilthead sea bream (Sparus aurata L.). J Comp Physiol B 2014; 185:87-101. [PMID: 25395251 DOI: 10.1007/s00360-014-0871-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Revised: 10/15/2014] [Accepted: 10/26/2014] [Indexed: 02/03/2023]
Abstract
To assess the role of the GH/IGF-I axis in osmotic acclimation of the gilthead seabream Sparus aurata, juvenile specimens were acclimated to four environmental salinities: hyposmotic (5 ‰), isosmotic (12 ‰) and hyperosmotic (40 and 55 ‰). The full-length cDNAs for both pituitary adenylate cyclase-activating peptide (PACAP) and prepro-somatostatin-I (PSS-I), the precursor for mature somatostatin-I (SS-I), were cloned. Hypothalamic PACAP and PSS-I, hypophyseal growth hormone (GH) and prolactin (PRL), and hepatic insulin-like growth factor-I (IGF-I) mRNA expression levels were analyzed in the four rearing salinities tested. PACAP and IGF-I mRNA values increased significantly in response to both 5 and 55 ‰ salinities, showing a U-shaped curve relationship with the basal level in the 40 ‰ group. Hypothalamic PSS-I expression increased strongly in the 55 ‰ environment. GH mRNA levels did not change in any of the tested environmental salinities. PRL mRNA maximum levels were encountered in the 5 and 12 ‰ environments, but significantly down-regulated in the 40 ‰. Plasma cortisol levels significantly increased in the 40 ‰ environment. These results are discussed in relation to the well-known high adaptability of Sparus aurata to different environmental salinities and the role of the GH/IGF-I axis in this process.
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Breves JP, McCormick SD, Karlstrom RO. Prolactin and teleost ionocytes: new insights into cellular and molecular targets of prolactin in vertebrate epithelia. Gen Comp Endocrinol 2014; 203:21-8. [PMID: 24434597 PMCID: PMC4096611 DOI: 10.1016/j.ygcen.2013.12.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/20/2013] [Accepted: 12/29/2013] [Indexed: 11/30/2022]
Abstract
The peptide hormone prolactin is a functionally versatile hormone produced by the vertebrate pituitary. Comparative studies over the last six decades have revealed that a conserved function for prolactin across vertebrates is the regulation of ion and water transport in a variety of tissues including those responsible for whole-organism ion homeostasis. In teleost fishes, prolactin was identified as the "freshwater-adapting hormone", promoting ion-conserving and water-secreting processes by acting on the gill, kidney, gut and urinary bladder. In mammals, prolactin is known to regulate renal, intestinal, mammary and amniotic epithelia, with dysfunction linked to hypogonadism, infertility, and metabolic disorders. Until recently, our understanding of the cellular mechanisms of prolactin action in fishes has been hampered by a paucity of molecular tools to define and study ionocytes, specialized cells that control active ion transport across branchial and epidermal epithelia. Here we review work in teleost models indicating that prolactin regulates ion balance through action on ion transporters, tight-junction proteins, and water channels in ionocytes, and discuss recent advances in our understanding of ionocyte function in the genetically and embryonically accessible zebrafish (Danio rerio). Given the high degree of evolutionary conservation in endocrine and osmoregulatory systems, these studies in teleost models are contributing novel mechanistic insight into how prolactin participates in the development, function, and dysfunction of osmoregulatory systems across the vertebrate lineage.
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Affiliation(s)
- Jason P Breves
- Department of Biology & Center for Neuroendocrine Studies, University of Massachusetts, Amherst, MA 01003, USA.
| | - Stephen D McCormick
- Department of Biology & Center for Neuroendocrine Studies, University of Massachusetts, Amherst, MA 01003, USA; USGS, Conte Anadromous Fish Research Center, Turners Falls, MA 01376, USA
| | - Rolf O Karlstrom
- Department of Biology & Center for Neuroendocrine Studies, University of Massachusetts, Amherst, MA 01003, USA
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Watanabe S, Seale AP, Grau EG, Kaneko T. Stretch-activated cation channel TRPV4 mediates hyposmotically induced prolactin release from prolactin cells of mozambique tilapia Oreochromis mossambicus. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1004-11. [DOI: 10.1152/ajpregu.00632.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In teleost fish, prolactin (PRL) is an important hormone for hyperosmoregulation. The release of PRL from the pituitary of Mozambique tilapia is stimulated by a decrease in extracellular osmolality. Previous studies have shown that hyposmotically induced PRL release is linked with cell volume changes, and that stretch-activated Ca2+ channels are likely responsible for the initiation of the signal transduction for PRL release. In this study, we identified the stretch-activated Ca2+ channel transient receptor potential vanilloid 4 (TRPV4) from the rostral pars distalis (RPD) of tilapia acclimated to freshwater (FW). TRPV4 transcripts were ubiquitously expressed in tilapia; the level of expression in RPDs of FW-acclimated fish was lower than that found in RPDs of seawater (SW)-acclimated fish. Immunohistochemical analysis of the pituitary revealed that TRPV4 is localized in the cell membrane of PRL cells of both FW and SW tilapia. A functional assay with CHO-K1 cells showed that tilapia TRPV4 responded to a decrease in extracellular osmolality, and that its function was suppressed by ruthenium red (RR) and activated by 4α-phorbol 12,13-didecanoate (4aPDD). Exposure of dissociated PRL cells from FW-acclimated tilapia to RR blocked hyposmolality induced PRL release. PRL release, on the other hand, was stimulated by 4aPDD. These results indicate that PRL release in response to physiologically relevant changes in extracellular osmolality is mediated by the osmotically sensitive TRPV4 cation channel.
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Affiliation(s)
- Soichi Watanabe
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo, Japan; and
| | - Andre P. Seale
- Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, Hawaii
| | - E. Gordon Grau
- Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, Hawaii
| | - Toyoji Kaneko
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo, Japan; and
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Kwong AKY, Woo NYS. The importance of the olfactory rosettes in maintaining pituitary prolactin and prolactin-releasing peptide levels during hyposmotic acclimation in silver sea bream (Sparus sarba). Comp Biochem Physiol A Mol Integr Physiol 2012; 161:456-62. [PMID: 22266396 DOI: 10.1016/j.cbpa.2012.01.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 01/06/2012] [Accepted: 01/06/2012] [Indexed: 11/19/2022]
Abstract
A potential role of the olfactory rosettes in maintaining prolactin (PRL) and prolactin-releasing peptide (PrRP) levels was examined in the euryhaline silver sea bream (Sparus sarba). The olfactory rosettes were surgically removed in silver sea bream adapted to hypo- (6 ppt) and hyper-osmotic (33 ppt) salinities and the mRNA expression of the two previously identified freshwater-adapting factors, prolactin (PRL) and prolactin-releasing peptide (PrRP), in silver sea bream was measured. The elevation of pituitary PRL and PrRP mRNA expression levels as seen in 6 ppt-adapted fish was abolished by surgical removal of the olfactory rosettes. The PRL and PrRP expression levels in fish adapted to 6 ppt were significantly lowered following olfactory rosette removal. On the other hand, hypothalamic PrRP mRNA expression in 6 ppt-adapted fish did not change. Specific signals for Na(+)-K(+)-ATPase but not CFTR mRNA expression were detected in the surface layers of olfactory epithelial cells by in situ hybridization. The mRNA abundance of CFTR and Na(+)-K(+)-ATPase α and β subunits remained unchanged in the olfactory rosette of silver sea bream adapted to 0, 6, 12, 33 and 50 ppt for 4 weeks and in fish abruptly transferred from 33 ppt to 6 ppt. Data obtained from the olfactory rosette removal experiments suggest a possible role of the olfactory system for maintaining PRL and PrRP expression during hyposmotic acclimation in sea bream.
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Affiliation(s)
- Anna K Y Kwong
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
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Bodinier C, Sucré E, Lecurieux-Belfond L, Blondeau-Bidet E, Charmantier G. Ontogeny of osmoregulation and salinity tolerance in the gilthead sea bream Sparus aurata. Comp Biochem Physiol A Mol Integr Physiol 2010; 157:220-8. [DOI: 10.1016/j.cbpa.2010.06.185] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 06/25/2010] [Accepted: 06/26/2010] [Indexed: 10/19/2022]
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