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Fakriadis I, Meiri-Ashkenazi I, Bracha C, Rosenfeld H, Corriero A, Zupa R, Pousis C, Papadaki M, Mylonas CC. Gonadotropin expression, pituitary and plasma levels in the reproductive cycle of wild and captive-reared greater amberjack (Seriola dumerili). Gen Comp Endocrinol 2024; 350:114465. [PMID: 38336122 DOI: 10.1016/j.ygcen.2024.114465] [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: 10/17/2023] [Revised: 01/23/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024]
Abstract
We compared the endocrine status of the pituitary-gonad axis of wild and captive-reared greater amberjack (Seriola dumerili) during the reproductive cycle (April - July), reporting on the expression and release of the two gonadotropins for the first time in the Mediterranean Sea. Ovaries from wild females were characterized histologically as DEVELOPING in early May and SPAWNING capable in late May-July, the latter having a 3 to 4-fold higher gonadosomatic index (GSI). SPAWNING capable wild females exhibited an increase in pituitary follicle stimulating hormone (Fsh) content, plasma testosterone (T) and 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P), while almost a 10-fold increase was observed in pituitary luteinizing hormone (Lh) content. An increasing trend of plasma 17β-estradiol (E2) was also recorded between the two reproductive stages in wild females. Captive-reared females sampled during the reproductive cycle exhibited two additional reproductive categories, with REGRESSED females having extensive follicular atresia and fish in the REGENERATING stage having only primary oocytes in their ovaries. Pituitary content of Fsh and Lh, fshb and lhb expression and plasma levels of Fsh and Lh remained unchanged among the four reproductive stages in captive females, in contrast with plasma E2 and T that decreased in the REGENERATING stage, and 17,20β-P which increased after the DEVELOPING stage. In general, no significant hormonal differences were recorded between captive-reared and wild DEVELOPING females, in contrast to SPAWNING capable females, where pituitary Lh content, plasma Fsh and T were found to be lower in females in captivity. Overall, the captive females lagged behind in reproductive development compared to the wild ones and this was perhaps related to the multiple handling of the sea cages where all the sampled fish were maintained. Between wild males in the DEVELOPING and SPAWNING capable stages, pituitary Lh content, plasma T and 17,20β-P, and GSI exhibited 3 to 4-fold increases, while an increasing trend of pituitary Fsh content, lhb expression levels and plasma 11-ketotestosterone (11-KT) was also observed, and an opposite trend was observed in plasma Lh. Captive males were allocated to one more category, with REGRESSED individuals having no spermatogenic capacity. During the SPAWNING capable phase, almost all measured parameters were lower in captive males compared to wild ones. More importantly, captive males showed significant differences from their wild counterparts throughout the reproductive season, starting already from the DEVELOPING stage. Therefore, it appears that captivity already exerted negative effects in males prior to the onset of the study and the multiple handling of the cage where sampled fish were reared. Overall, the present study demonstrated that female greater amberjack do undergo full vitellogenesis in captivity, albeit with some dysfunctions that may be related to the husbandry of the experiment, while males, on the other hand, may be more seriously affected by captivity even before the onset of the study.
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Affiliation(s)
- Ioannis Fakriadis
- Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Centre for Marine Research, P.O. Box 2214, Heraklion, Crete 71003, Greece; University of Crete, Department of Biology, P.O. Box 2208, Heraklion 71409, Crete, Greece.
| | - Iris Meiri-Ashkenazi
- Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat 88112, Israel
| | - Chen Bracha
- Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat 88112, Israel
| | - Hanna Rosenfeld
- Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat 88112, Israel
| | - Aldo Corriero
- Department of Veterinary Medicine, University of Bari Aldo Moro, Valenzano (Bari), Italy
| | - Rosa Zupa
- Department of Veterinary Medicine, University of Bari Aldo Moro, Valenzano (Bari), Italy
| | | | - Maria Papadaki
- Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Centre for Marine Research, P.O. Box 2214, Heraklion, Crete 71003, Greece
| | - Constantinos C Mylonas
- Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Centre for Marine Research, P.O. Box 2214, Heraklion, Crete 71003, Greece
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2
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Tveiten H, Karlsen K, Thesslund T, Johansson GS, Thiyagarajan DB, Andersen Ø. Impact of germ cell ablation on the activation of the brain-pituitary-gonadal axis in precocious Atlantic salmon (Salmo salar L.) males. Mol Reprod Dev 2022; 89:471-484. [PMID: 35830347 PMCID: PMC9796531 DOI: 10.1002/mrd.23635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/27/2022] [Accepted: 07/04/2022] [Indexed: 01/01/2023]
Abstract
The germ cells are essential for sexual reproduction by giving rise to the gametes, but the importance of germ cells for gonadal somatic functions varies among vertebrates. The RNA-binding dead end (Dnd) protein is necessary for the specification and migration of primordial germ cells to the future reproductive organs. Here, we ablated the gametes in Atlantic salmon males and females by microinjecting dnd antisense gapmer oligonucleotides at the zygotic stage. Precocious maturation was induced in above 50% of both germ cell-depleted and intact fertile males, but not in females, by exposure to an off-season photoperiod regime. Sterile and fertile males showed similar body growth, but maturing fish tended to be heavier than their immature counterparts. Pituitary fshβ messenger RNA levels strongly increased in maturing sterile and fertile males concomitant with the upregulated expression of Sertoli and Leydig cell markers. Plasma concentrations of 11-ketotestosterone and testosterone in maturing sterile males were significantly higher than the basal levels in immature fish, but lower than those in maturing fertile males. The study demonstrates that germ cells are not a prerequisite for the activation of the brain-pituitary-gonad axis and sex steroidogenesis in Atlantic salmon males, but may be important for the maintenance of gonadal somatic functions.
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Affiliation(s)
- Helge Tveiten
- Norwegian College of Fishery ScienceThe Arctic University of NorwayTromsøNorway
| | - Kristian Karlsen
- Norwegian College of Fishery ScienceThe Arctic University of NorwayTromsøNorway,Present address:
Lerøy Aurora AS, Stortorget 1N‐9267 TromsøNorway
| | | | | | | | - Øivind Andersen
- NofimaTromsøNorway,Department of Animal and Aquacultural SciencesNorwegian University of Life Sciences (NMBU)ÅsNorway
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Ahi EP, Sinclair-Waters M, Moustakas-Verho J, Jansouz S, Primmer CR. Strong regulatory effects of vgll3 genotype on reproductive axis gene expression in juvenile male Atlantic salmon. Gen Comp Endocrinol 2022; 325:114055. [PMID: 35580687 DOI: 10.1016/j.ygcen.2022.114055] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 05/07/2022] [Accepted: 05/12/2022] [Indexed: 12/24/2022]
Abstract
Age at maturity is a major contributor to the diversity of life history strategies in organisms. The process of maturation is influenced by both genetics and the environment, and includes changes in levels of sex hormones and behavior, but the specific factors leading to variation in maturation timing are poorly understood. gnrh1 regulates the transcription of gonadotropin genes at pubertal onset in many species, but this gene is lacking in certain teleost species including Atlantic salmon (Salmo salar), which raises the possibility of the involvement of other important regulatory factors during this process. Earlier research has reported a strong association of alternative alleles of the vgll3 gene with maturation timing in Atlantic salmon, suggesting it as a potential candidate regulating reproductive axis genes. Here, we investigated the expression of reproductive axis genes in one-year-old Atlantic salmon males with immature gonads and different vgll3 genotypes during the spawning period. We detected strong vgll3 genotype-dependent differential expression of reproductive axis genes (such as fshb, lhb, amh and igf3) tested in the pituitary, and testis. In addition, we observed differential expression of jun (ap1) and nr5a1b (sf1), potential upstream regulators of gonadotropins in the pituitary, as well as axin2, id3, insl3, itch, ptgs2a and ptger4b, the downstream targets of amh and igf3 in the testis. Hereby, we provide evidence of strong vgll3 genotype-dependent transcriptional regulation of reproductive axis genes prior to sexual maturation and suggest alternative models for distinct actions of vgll3 genotypes on the related molecular processes.
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Affiliation(s)
- Ehsan Pashay Ahi
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland.
| | - Marion Sinclair-Waters
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland
| | - Jacqueline Moustakas-Verho
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland.
| | - Shadi Jansouz
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland.
| | - Craig R Primmer
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland; Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE), University of Helsinki, Finland.
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Crespo D, Skaftnesmo KO, Kjærner-Semb E, Yilmaz O, Norberg B, Olausson S, Vogelsang P, Bogerd J, Kleppe L, Edvardsen RB, Andersson E, Wargelius A, Hansen TJ, Fjelldal PG, Schulz RW. Pituitary Gonadotropin Gene Expression During Induced Onset of Postsmolt Maturation in Male Atlantic Salmon: In Vivo and Tissue Culture Studies. Front Endocrinol (Lausanne) 2022; 13:826920. [PMID: 35370944 PMCID: PMC8964956 DOI: 10.3389/fendo.2022.826920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/17/2022] [Indexed: 12/25/2022] Open
Abstract
Precocious male maturation causes reduced welfare and increased production costs in Atlantic salmon (Salmo salar) aquaculture. The pituitary produces and releases follicle-stimulating hormone (Fsh), the gonadotropin triggering puberty in male salmonids. However, little is known about how Fsh production is regulated in Atlantic salmon. We examined, in vivo and ex vivo, transcriptional changes of gonadotropin-related genes accompanying the initial steps of testis maturation, in pituitaries of males exposed to photoperiod and temperature conditions promoting maturation (constant light and 16°C). Pituitary fshb, lhb and gnrhr2bba transcripts increased in vivo in maturing males (gonado-somatic index > 0.1%). RNA sequencing (RNAseq) analysis using pituitaries from genetically similar males carrying the same genetic predisposition to mature, but differing by responding or not responding to stimulatory environmental conditions, revealed 144 differentially expressed genes, ~2/3rds being up-regulated in responders, including fshb and other pituitary hormones, steroid-related and other puberty-associated transcripts. Functional enrichment analyses confirmed gene involvement in hormone/steroid production and gonad development. In ex vivo studies, whole pituitaries were exposed to a selection of hormones and growth factors. Gonadotropin-releasing hormone (Gnrh), 17β-estradiol (E2) and 11-ketotestosterone (11-KT) up-regulated gnrhr2bba and lhb, while fshb was up-regulated by Gnrh but down-regulated by 11-KT in pituitaries from immature males. Also pituitaries from maturing males responded to Gnrh and sex steroids by increased gnrhr2bba and lhb transcript levels, but fshb expression remained unchanged. Growth factors (inhibin A, activin A and insulin-like growth factor 1) did not change gnrhr2bba, lhb or fshb transcript levels in pituitaries either from immature or maturing males. Additional pituitary ex vivo studies on candidates identified by RNAseq showed that these transcripts were preferentially regulated by Gnrh and sex steroids, but not by growth factors, and that Gnrh/sex steroids were less effective when incubating pituitaries from maturing males. Our results suggest that a yet to be characterized mechanism up-regulating fshb expression in the salmon pituitary is activated in response to stimulatory environmental conditions prior to morphological signs of testis maturation, and that the transcriptional program associated with this mechanism becomes unresponsive or less responsive to most stimulators ex vivo once males had entered pubertal developmental in vivo.
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Affiliation(s)
- Diego Crespo
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
- *Correspondence: Diego Crespo,
| | - Kai Ove Skaftnesmo
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Erik Kjærner-Semb
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Ozlem Yilmaz
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | - Birgitta Norberg
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | - Sara Olausson
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Austevoll Research Station, Storebø, Norway
| | - Petra Vogelsang
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Jan Bogerd
- Reproductive Biology Group, Division Developmental Biology, Department Biology, Science Faculty, Utrecht University, Utrecht, Netherlands
| | - Lene Kleppe
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Rolf B. Edvardsen
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Eva Andersson
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Anna Wargelius
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Tom J. Hansen
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Per Gunnar Fjelldal
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Matre Research Station, Matredal, Norway
| | - Rüdiger W. Schulz
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
- Reproductive Biology Group, Division Developmental Biology, Department Biology, Science Faculty, Utrecht University, Utrecht, Netherlands
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Characterization of hormone-producing cell types in the teleost pituitary gland using single-cell RNA-seq. Sci Data 2021; 8:279. [PMID: 34711832 PMCID: PMC8553774 DOI: 10.1038/s41597-021-01058-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 09/09/2021] [Indexed: 11/08/2022] Open
Abstract
The pituitary is the vertebrate endocrine gland responsible for the production and secretion of several essential peptide hormones. These, in turn, control many aspects of an animal’s physiology and development, including growth, reproduction, homeostasis, metabolism, and stress responses. In teleost fish, each hormone is presumably produced by a specific cell type. However, key details on the regulation of, and communication between these cell types remain to be resolved. We have therefore used single-cell sequencing to generate gene expression profiles for 2592 and 3804 individual cells from the pituitaries of female and male adult medaka (Oryzias latipes), respectively. Based on expression profile clustering, we define 15 and 16 distinct cell types in the female and male pituitary, respectively, of which ten are involved in the production of a single peptide hormone. Collectively, our data provide a high-quality reference for studies on pituitary biology and the regulation of hormone production, both in fish and in vertebrates in general. Measurement(s) | RNA-seq gene expression profiling assay | Technology Type(s) | tag based single cell RNA sequencing | Factor Type(s) | sex | Sample Characteristic - Organism | Oryzias latipes | Sample Characteristic - Environment | fresh water aquarium |
Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.16592621
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Yates MC, Derry AM, Cristescu ME. Environmental RNA: A Revolution in Ecological Resolution? Trends Ecol Evol 2021; 36:601-609. [PMID: 33757695 DOI: 10.1016/j.tree.2021.03.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/26/2021] [Accepted: 03/03/2021] [Indexed: 12/11/2022]
Abstract
Current advancements in environmental RNA (eRNA) exploit its relatively fast turnover rate relative to environmental DNA (eDNA) to assess 'metabolically active' or temporally/spatially recent community diversity. However, this focus significantly underutilizes the trove of potential ecological information encrypted in eRNA. Here, we argue for pushing beyond current species-level eDNA detection capabilities by using eRNA to detect any organisms with unique eRNA profiles, potentially including different life-history stages, sexes, or even specific phenotypes within a species. We also discuss the future of eRNA as a means of assessing the physiological status of organisms and the ecological health of populations and communities, reflecting ecosystem-level conditions. We posit that eRNA has the potential to significantly improve the resolution of organism detection, biological monitoring, and biomonitoring applications in ecology.
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Affiliation(s)
- Matthew C Yates
- Département des Sciences Biologiques, Université du Québec à Montréal, 141 Avenue Président-Kennedy, Montréal, QC, H2X 1Y4, Canada.
| | - Alison M Derry
- Département des Sciences Biologiques, Université du Québec à Montréal, 141 Avenue Président-Kennedy, Montréal, QC, H2X 1Y4, Canada
| | - Melania E Cristescu
- Department of Biology, McGill University, 1205 Dr Penfield Avenue, Montreal, QC, H3A 1B1, Canada
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Rousseau K, Prunet P, Dufour S. Special features of neuroendocrine interactions between stress and reproduction in teleosts. Gen Comp Endocrinol 2021; 300:113634. [PMID: 33045232 DOI: 10.1016/j.ygcen.2020.113634] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 09/10/2020] [Accepted: 09/20/2020] [Indexed: 02/08/2023]
Abstract
Stress and reproduction are both essential functions for vertebrate survival, ensuring on one side adaptative responses to environmental changes and potential life threats, and on the other side production of progeny. With more than 25,000 species, teleosts constitute the largest group of extant vertebrates, and exhibit a large diversity of life cycles, environmental conditions and regulatory processes. Interactions between stress and reproduction are a growing concern both for conservation of fish biodiversity in the frame of global changes and for the development of sustainability of aquaculture including fish welfare. In teleosts, as in other vertebrates, adverse effects of stress on reproduction have been largely documented and will be shortly overviewed. Unexpectedly, stress notably via cortisol, may also facilitate reproductive function in some teleost species in relation to their peculiar life cyles and this review will provide some examples. Our review will then mainly address the neuroendocrine axes involved in the control of stress and reproduction, namely the corticotropic and gonadotropic axes, as well as their interactions. After reporting some anatomo-functional specificities of the neuroendocrine systems in teleosts, we will describe the major actors of the corticotropic and gonadotropic axes at the brain-pituitary-peripheral glands (interrenals and gonads) levels, with a special focus on the impact of teleost-specific whole genome duplication (3R) on the number of paralogs and their potential differential functions. We will finally review the current knowledge on the neuroendocrine mechanisms of the various interactions between stress and reproduction at different levels of the two axes in teleosts in a comparative and evolutionary perspective.
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Affiliation(s)
- Karine Rousseau
- Muséum National d'Histoire Naturelle, Research Unit BOREA, Biology of Aquatic Organisms and Ecosystems, CNRS, IRD, SU, UCN, UA, Paris, France
| | - Patrick Prunet
- INRAE, UR1037, Laboratoire de Physiologie et de Génomique des Poissons (LPGP), Rennes, France
| | - Sylvie Dufour
- Muséum National d'Histoire Naturelle, Research Unit BOREA, Biology of Aquatic Organisms and Ecosystems, CNRS, IRD, SU, UCN, UA, Paris, France.
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8
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Fontaine R, Royan MR, von Krogh K, Weltzien FA, Baker DM. Direct and Indirect Effects of Sex Steroids on Gonadotrope Cell Plasticity in the Teleost Fish Pituitary. Front Endocrinol (Lausanne) 2020; 11:605068. [PMID: 33365013 PMCID: PMC7750530 DOI: 10.3389/fendo.2020.605068] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 10/12/2020] [Indexed: 12/26/2022] Open
Abstract
The pituitary gland controls many important physiological processes in vertebrates, including growth, homeostasis, and reproduction. As in mammals, the teleost pituitary exhibits a high degree of plasticity. This plasticity permits changes in hormone production and secretion necessary to meet the fluctuating demands over the life of an animal. Pituitary plasticity is achieved at both cellular and population levels. At the cellular level, hormone synthesis and release can be regulated via changes in cell composition to modulate both sensitivity and response to different signals. At the cell population level, the number of cells producing a given hormone can change due to proliferation, differentiation of progenitor cells, or transdifferentiation of specific cell types. Gonadotropes, which play an important role in the control of reproduction, have been intensively investigated during the last decades and found to display plasticity. To ensure appropriate endocrine function, gonadotropes rely on external and internal signals integrated at the brain level or by the gonadotropes themselves. One important group of internal signals is the sex steroids, produced mainly by the gonadal steroidogenic cells. Sex steroids have been shown to exert complex effects on the teleost pituitary, with differential effects depending on the species investigated, physiological status or sex of the animal, and dose or method of administration. This review summarizes current knowledge of the effects of sex steroids (androgens and estrogens) on gonadotrope cell plasticity in teleost anterior pituitary, discriminating direct from indirect effects.
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Affiliation(s)
- Romain Fontaine
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Muhammad Rahmad Royan
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Kristine von Krogh
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Finn-Arne Weltzien
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Dianne M. Baker
- Department of Biological Sciences, University of Mary Washington, Fredericksburg, VA, United States
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Somoza GM, Mechaly AS, Trudeau VL. Kisspeptin and GnRH interactions in the reproductive brain of teleosts. Gen Comp Endocrinol 2020; 298:113568. [PMID: 32710898 DOI: 10.1016/j.ygcen.2020.113568] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 07/17/2020] [Accepted: 07/19/2020] [Indexed: 02/09/2023]
Abstract
It is well known that gonadotropin-releasing hormone (Gnrh) has a key role in reproduction by regulating the synthesis and release of gonadotropins from the anterior pituitary gland of all vertebrates. About 25 years ago, another neuropeptide, kisspeptin (Kiss1) was discovered as a metastasis suppressor of melanoma cell lines and then found to be essential for mammalian reproduction as a stimulator of hypothalamic Gnrh and regulator of puberty onset. Soon after, a kisspeptin receptor (kissr) was found in the teleost brain. Nowadays, it is known that in most teleosts the kisspeptin system is composed of two ligands, kiss1 and kiss2, and two receptors, kiss2r and kiss3r. Even though both kisspeptin peptides, Kiss1 and Kiss2, have been demonstrated to stimulate gonadotropin synthesis and secretion in different fish species, their actions appear not to be mediated by Gnrh neurons as in mammalian models. In zebrafish and medaka, at least, hypophysiotropic Gnrh neurons do not express Kiss receptors. Furthermore, kisspeptinergic nerve terminals reach luteinizing hormone cells in some fish species, suggesting a direct pituitary action. Recent studies in zebrafish and medaka with targeted mutations of kiss and/or kissr genes reproduce relatively normally. In zebrafish, single gnrh mutants and additionally those having the triple gnrh3 plus 2 kiss mutations can reproduce reasonably well. In these fish, other neuropeptides known to affect gonadotropin secretion were up regulated, suggesting that they may be involved in compensatory responses to maintain reproductive processes. In this context, the present review explores and presents different possibilities of interactions between Kiss, Gnrh and other neuropeptides known to affect reproduction in teleost fish. Our intention is to stimulate a broad discussion on the relative roles of kisspeptin and Gnrh in the control of teleost reproduction.
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Affiliation(s)
- Gustavo M Somoza
- Instituto Tecnológico de Chascomús (CONICET-UNSAM), Chascomús, Buenos Aires B7130IWA, Argentina.
| | - Alejandro S Mechaly
- Instituto de Investigaciones en Biodiversidad y Biotecnología (CONICET), Mar del Plata, Buenos Aires 7600, Argentina.
| | - Vance L Trudeau
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
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Ciani E, Haug TM, Maugars G, Weltzien FA, Falcón J, Fontaine R. Effects of Melatonin on Anterior Pituitary Plasticity: A Comparison Between Mammals and Teleosts. Front Endocrinol (Lausanne) 2020; 11:605111. [PMID: 33505357 PMCID: PMC7831660 DOI: 10.3389/fendo.2020.605111] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/12/2020] [Indexed: 01/01/2023] Open
Abstract
Melatonin is a key hormone involved in the photoperiodic signaling pathway. In both teleosts and mammals, melatonin produced in the pineal gland at night is released into the blood and cerebrospinal fluid, providing rhythmic information to the whole organism. Melatonin acts via specific receptors, allowing the synchronization of daily and annual physiological rhythms to environmental conditions. The pituitary gland, which produces several hormones involved in a variety of physiological processes such as growth, metabolism, stress and reproduction, is an important target of melatonin. Melatonin modulates pituitary cellular activities, adjusting the synthesis and release of the different pituitary hormones to the functional demands, which changes during the day, seasons and life stages. It is, however, not always clear whether melatonin acts directly or indirectly on the pituitary. Indeed, melatonin also acts both upstream, on brain centers that control the pituitary hormone production and release, as well as downstream, on the tissues targeted by the pituitary hormones, which provide positive and negative feedback to the pituitary gland. In this review, we describe the known pathways through which melatonin modulates anterior pituitary hormonal production, distinguishing indirect effects mediated by brain centers from direct effects on the anterior pituitary. We also highlight similarities and differences between teleosts and mammals, drawing attention to knowledge gaps, and suggesting aims for future research.
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Affiliation(s)
- Elia Ciani
- Department of Pharmacy, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Trude M. Haug
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Gersende Maugars
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Finn-Arne Weltzien
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Jack Falcón
- Laboratoire Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), MNHN, CNRS FRE 2030, SU, IRD 207, UCN, UA, Paris, France
| | - Romain Fontaine
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
- *Correspondence: Romain Fontaine,
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