1
|
Li Z, Liu R, Liu J, Jiang Z, Ba X, Li K, Liu L. Effects of flowing water stimulation on hormone regulation during the maturation process of Conger myriaster ovaries. Front Physiol 2024; 15:1404834. [PMID: 38764859 PMCID: PMC11100330 DOI: 10.3389/fphys.2024.1404834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 04/11/2024] [Indexed: 05/21/2024] Open
Abstract
Conger eel (Conger myriaster) is an economically important species in China. Due to the complex life history of the conger eel, achieving artificial reproduction has remained elusive. This study aimed to explore the effect of water stimulation on hormonal regulation during the artificial reproduction of conger eel. The experiment was divided into four groups: A1 (no hormone injection, still water), A2 (no hormone injection, flowing water), B1 (hormone injection, still water), and B2 (hormone injection, flowing water). The flowing water group maintained a flow velocity of 0.4 ± 0.05 m/s for 12 h daily throughout the 60-day period. Steroid hormone levels in the serum and ovaries of conger eels were analyzed using UPLC-MS/MS and ELISA on the 30th and 60th days of the experiment. The relative expression levels of follicle-stimulating hormone (FSHβ) and luteinizing hormone (LHβ) in the pituitary were determined by quantitative PCR. The results showed a significantly lower gonadosomatic index (GSI) in B2 compared to B1 (p < 0.05) on the 30th day. FSH was found to act only in the early stages of ovarian development, with water stimulation significantly enhancing FSH synthesis (p < 0.05), while FSHβ gene was not expressed after hormone injection. Conversely, LH was highly expressed in late ovarian development, with flowing water stimulation significantly promoting LH synthesis (p < 0.05). Serum cortisol (COR) levels were significantly higher in the flowing water group than in the still water group (p < 0.05). Furthermore, estradiol (E2) content of B2 was significantly lower than that of B1 on the 30th and 60th day. Overall, flowing water stimulation enhanced the synthesis of FSH in early ovarian development and LH in late ovarian development, while reducing E2 accumulation in the ovaries. In this study, the effect of flowing water stimulation on hormone regulation during the artificial reproduction of conger eel was initially investigated to provide a theoretical basis for optimizing artificial reproduction techniques.
Collapse
Affiliation(s)
- Zhengcheng Li
- China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology (Shanghai), Shanghai Ocean University, Shanghai, China
- Center for Ecological Aquaculture (CEA), Shanghai Ocean University, Shanghai, China
| | - Rucong Liu
- China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology (Shanghai), Shanghai Ocean University, Shanghai, China
- Center for Ecological Aquaculture (CEA), Shanghai Ocean University, Shanghai, China
| | - Jingwei Liu
- China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology (Shanghai), Shanghai Ocean University, Shanghai, China
- Center for Ecological Aquaculture (CEA), Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Aquaculture, Shanghai Ocean University, Shanghai, China
| | - Zhixin Jiang
- China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology (Shanghai), Shanghai Ocean University, Shanghai, China
- Center for Ecological Aquaculture (CEA), Shanghai Ocean University, Shanghai, China
| | - Xubing Ba
- China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology (Shanghai), Shanghai Ocean University, Shanghai, China
- Center for Ecological Aquaculture (CEA), Shanghai Ocean University, Shanghai, China
| | - Kang Li
- China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology (Shanghai), Shanghai Ocean University, Shanghai, China
- Center for Ecological Aquaculture (CEA), Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Aquaculture, Shanghai Ocean University, Shanghai, China
| | - Liping Liu
- China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology (Shanghai), Shanghai Ocean University, Shanghai, China
- Center for Ecological Aquaculture (CEA), Shanghai Ocean University, Shanghai, China
- Shanghai Engineering Research Center of Aquaculture, Shanghai Ocean University, Shanghai, China
| |
Collapse
|
2
|
Byun JH, Hyeon JY, Hettiarachchi SA, Udagawa S, Mahardini A, Kim JM, Hur SP, Takemura A. Effects of dopamine and melatonin treatment on the expression of the genes associated with artificially induced sexual maturation in Japanese eel, Anguilla japonica. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:389-399. [PMID: 38334250 DOI: 10.1002/jez.2788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 01/14/2024] [Accepted: 01/18/2024] [Indexed: 02/10/2024]
Abstract
Japanese eel (Anguilla japonica) is a commercially important fish species in Asia. Understanding factors like photoperiod, temperature, and lunar cycles is crucial for successful aquaculture and managing its reproduction. Melatonin and dopamine (DA) are essential for regulating reproduction in vertebrates, including fish. This study investigated the effects of melatonin and DA on the reproductive system of mature male Japanese eels to better understand reproductive regulation in fish. To clarify the effects of these hormones on sexual maturation in eels, a critical stage in the reproductive process, sexual maturation was induced by injecting human chorionic gonadotropin, which stimulates the production of sex hormones. To check the effect of melatonin and DA on sexual maturation, DA, melatonin, and DA + domperidone were intraperitoneally injected into fish from each group (six per treatment) at a dose of 1 mg/kg body weight. The fish were then examined using quantitative RT-PCR by comparing the messenger RNA level of reproduction-related genes (gonadotropin releasing hormone 1; gnrh1, gonadotropin releasing hormone 2; gnrh2, follicle stimulating hormone; fshβ, luteinizing hormone; lhβ and DA receptor 2b; d2b), involved in the gonadotropic axis in eels, to those that received a control injection. The results indicate significant differences in the expression levels of gnrh1, gnrh2 and d2b in the brain and d2b, fshβ, lhβ in the pituitary at different stages of sexual maturation. Melatonin appears to enhance the production of sex gonadotropins, whereas DA inhibits them. These findings suggest an interaction between melatonin and DA in regulating reproduction in Japanese eels.
Collapse
Affiliation(s)
- Jun-Hwan Byun
- Department of Fisheries Biology, College of Fisheries Sciences, Pukyong National University, Busan, South Korea
| | - Ji-Yeon Hyeon
- Division of Polar Life Science, Korea Polar Research Institute, Incheon, South Korea
| | | | - Shingo Udagawa
- Department of Co-Creation Management, Organization for Research Promotion, University of the Ryukyus, Okinawa, Japan
| | - Angka Mahardini
- Department of Marine Science, Faculty of Science, Diponegoro University, Semarang, Indonesia
| | - Jong-Myoung Kim
- Department of Fisheries Biology, College of Fisheries Sciences, Pukyong National University, Busan, South Korea
| | - Sung-Pyo Hur
- Department of Marine Life Science, Jeju National University, Jeju, South Korea
| | - Akihiro Takemura
- Department of Chemistry, Biology, and Marine Science, University of the Ryukyus, Okinawa, Japan
| |
Collapse
|
3
|
Dufour S, Quérat B, Tostivint H, Pasqualini C, Vaudry H, Rousseau K. Origin and Evolution of the Neuroendocrine Control of Reproduction in Vertebrates, With Special Focus on Genome and Gene Duplications. Physiol Rev 2019; 100:869-943. [PMID: 31625459 DOI: 10.1152/physrev.00009.2019] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In humans, as in the other mammals, the neuroendocrine control of reproduction is ensured by the brain-pituitary gonadotropic axis. Multiple internal and environmental cues are integrated via brain neuronal networks, ultimately leading to the modulation of the activity of gonadotropin-releasing hormone (GnRH) neurons. The decapeptide GnRH is released into the hypothalamic-hypophysial portal blood system and stimulates the production of pituitary glycoprotein hormones, the two gonadotropins luteinizing hormone and follicle-stimulating hormone. A novel actor, the neuropeptide kisspeptin, acting upstream of GnRH, has attracted increasing attention in recent years. Other neuropeptides, such as gonadotropin-inhibiting hormone/RF-amide related peptide, and other members of the RF-amide peptide superfamily, as well as various nonpeptidic neuromediators such as dopamine and serotonin also provide a large panel of stimulatory or inhibitory regulators. This paper addresses the origin and evolution of the vertebrate gonadotropic axis. Brain-pituitary neuroendocrine axes are typical of vertebrates, the pituitary gland, mediator and amplifier of brain control on peripheral organs, being a vertebrate innovation. The paper reviews, from molecular and functional perspectives, the evolution across vertebrate radiation of some key actors of the vertebrate neuroendocrine control of reproduction and traces back their origin along the vertebrate lineage and in other metazoa before the emergence of vertebrates. A focus is given on how gene duplications, resulting from either local events or from whole genome duplication events, and followed by paralogous gene loss or conservation, might have shaped the evolutionary scenarios of current families of key actors of the gonadotropic axis.
Collapse
Affiliation(s)
- Sylvie Dufour
- Muséum National d'Histoire Naturelle, Biology of Aquatic Organisms and Ecosystems, CNRS, IRD, Sorbonne Université, Université Caen Normandie, Université des Antilles, Paris, France; Université Paris Diderot, Sorbonne Paris Cite, Biologie Fonctionnelle et Adaptative, Paris, France; INSERM U1133, Physiologie de l'axe Gonadotrope, Paris, France; Muséum National d'Histoire Naturelle, Physiologie Moléculaire et Adaptation, Muséum National d'Histoire Naturelle, Paris, France; Université Paris-Saclay, Université Paris-Sud, CNRS, Paris-Saclay Institute of Neuroscience (UMR 9197), Gif-sur-Yvette, France; and Université de Rouen Normandie, Rouen, France
| | - Bruno Quérat
- Muséum National d'Histoire Naturelle, Biology of Aquatic Organisms and Ecosystems, CNRS, IRD, Sorbonne Université, Université Caen Normandie, Université des Antilles, Paris, France; Université Paris Diderot, Sorbonne Paris Cite, Biologie Fonctionnelle et Adaptative, Paris, France; INSERM U1133, Physiologie de l'axe Gonadotrope, Paris, France; Muséum National d'Histoire Naturelle, Physiologie Moléculaire et Adaptation, Muséum National d'Histoire Naturelle, Paris, France; Université Paris-Saclay, Université Paris-Sud, CNRS, Paris-Saclay Institute of Neuroscience (UMR 9197), Gif-sur-Yvette, France; and Université de Rouen Normandie, Rouen, France
| | - Hervé Tostivint
- Muséum National d'Histoire Naturelle, Biology of Aquatic Organisms and Ecosystems, CNRS, IRD, Sorbonne Université, Université Caen Normandie, Université des Antilles, Paris, France; Université Paris Diderot, Sorbonne Paris Cite, Biologie Fonctionnelle et Adaptative, Paris, France; INSERM U1133, Physiologie de l'axe Gonadotrope, Paris, France; Muséum National d'Histoire Naturelle, Physiologie Moléculaire et Adaptation, Muséum National d'Histoire Naturelle, Paris, France; Université Paris-Saclay, Université Paris-Sud, CNRS, Paris-Saclay Institute of Neuroscience (UMR 9197), Gif-sur-Yvette, France; and Université de Rouen Normandie, Rouen, France
| | - Catherine Pasqualini
- Muséum National d'Histoire Naturelle, Biology of Aquatic Organisms and Ecosystems, CNRS, IRD, Sorbonne Université, Université Caen Normandie, Université des Antilles, Paris, France; Université Paris Diderot, Sorbonne Paris Cite, Biologie Fonctionnelle et Adaptative, Paris, France; INSERM U1133, Physiologie de l'axe Gonadotrope, Paris, France; Muséum National d'Histoire Naturelle, Physiologie Moléculaire et Adaptation, Muséum National d'Histoire Naturelle, Paris, France; Université Paris-Saclay, Université Paris-Sud, CNRS, Paris-Saclay Institute of Neuroscience (UMR 9197), Gif-sur-Yvette, France; and Université de Rouen Normandie, Rouen, France
| | - Hubert Vaudry
- Muséum National d'Histoire Naturelle, Biology of Aquatic Organisms and Ecosystems, CNRS, IRD, Sorbonne Université, Université Caen Normandie, Université des Antilles, Paris, France; Université Paris Diderot, Sorbonne Paris Cite, Biologie Fonctionnelle et Adaptative, Paris, France; INSERM U1133, Physiologie de l'axe Gonadotrope, Paris, France; Muséum National d'Histoire Naturelle, Physiologie Moléculaire et Adaptation, Muséum National d'Histoire Naturelle, Paris, France; Université Paris-Saclay, Université Paris-Sud, CNRS, Paris-Saclay Institute of Neuroscience (UMR 9197), Gif-sur-Yvette, France; and Université de Rouen Normandie, Rouen, France
| | - Karine Rousseau
- Muséum National d'Histoire Naturelle, Biology of Aquatic Organisms and Ecosystems, CNRS, IRD, Sorbonne Université, Université Caen Normandie, Université des Antilles, Paris, France; Université Paris Diderot, Sorbonne Paris Cite, Biologie Fonctionnelle et Adaptative, Paris, France; INSERM U1133, Physiologie de l'axe Gonadotrope, Paris, France; Muséum National d'Histoire Naturelle, Physiologie Moléculaire et Adaptation, Muséum National d'Histoire Naturelle, Paris, France; Université Paris-Saclay, Université Paris-Sud, CNRS, Paris-Saclay Institute of Neuroscience (UMR 9197), Gif-sur-Yvette, France; and Université de Rouen Normandie, Rouen, France
| |
Collapse
|
4
|
Daily variation of D2 dopamine receptor transcription in the brain of the Japanese eel Anguilla japonica and its regulation with dopamine and melatonin. Comp Biochem Physiol A Mol Integr Physiol 2019; 240:110581. [PMID: 31634572 DOI: 10.1016/j.cbpa.2019.110581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/31/2019] [Accepted: 09/17/2019] [Indexed: 11/22/2022]
Abstract
Dopamine plays a crucial role in controlling reproduction in eels, and its action is mediated through D2-type dopamine receptors. D2A and D2B receptors in the Japanese eel Anguilla japonica were cloned and characterized in the present study. Attention (daily expression patterns in the brain and endogenous regulation) was paid to D2B receptor because it is considered to play a crucial role in eel reproduction. The cDNAs of D2A and D2B receptors had open reading frames comprising 456 and 454 amino acid residues, respectively, which were phylogenetically clustered with those of other teleost species. Both receptors were highly expressed in the brain. D2B receptor transcript levels exhibited high day/low night variation in the midbrain and pituitary, suggesting that its transcription in these tissues is regulated in a daily manner, possibly under influence of melatonin. Intraperitoneal injection of dopamine downregulated D2B receptor transcription significantly in the midbrain and moderately in the pituitary within 1 h, but upregulated its transcription in the forebrain. Co-injection of dopamine with its antagonist (domperidone) reversed the effect of dopamine in the pituitary and forebrain, but not in the midbrain, suggesting that the effect of dopamine on D2B receptor transcription differs among brain regions. The same treatment with melatonin resulted in decreased D2B receptor transcription in the midbrain. These findings indicate that dopamine and melatonin have key roles in the daily variation in D2B receptor transcription in the brain of Japanese eel, and that they are related to a daily base secretion of hormones in the hypothalamic-pituitary-gonadal axis in this species.
Collapse
|
5
|
Jéhannet P, Kruijt L, Damsteegt EL, Swinkels W, Heinsbroek LTN, Lokman PM, Palstra AP. A mechanistic model for studying the initiation of anguillid vitellogenesis by comparing the European eel (Anguilla anguilla) and the shortfinned eel (A. australis). Gen Comp Endocrinol 2019; 279:129-138. [PMID: 30796898 DOI: 10.1016/j.ygcen.2019.02.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 02/19/2019] [Accepted: 02/19/2019] [Indexed: 12/20/2022]
Abstract
An inverse relation exists between the maturation stage at the start of the oceanic reproductive migration and the migration distance to the spawning grounds for the various eel species. The European eel Anguilla anguilla migrates up to 5-6000 km and leaves in a previtellogenic state. The shortfinned eel A. australis migrates 2-4000 km and leaves in an early vitellogenic state. In this study, we compared the early pubertal events in European silver eels with those in silver shortfinned eels to gain insights into the initiation of vitellogenesis. Immediately after being caught, yellow and silver eels of both species were measured and sampled for blood and tissues. Eye index (EI), gonadosomatic index (GSI) and hepatosomatic index (HSI) were calculated. Plasma 11-ketotestosterone (11-KT) and 17β-estradiol (E2) levels were measured by radioimmunoassay. Pituitary, liver and ovaries were dissected for quantitative real-time PCR analyses (pituitary dopamine 2b receptor d2br, gonadotropin-releasing hormone receptors 1 and 2 gnrhr1 and gnrhr2, growth hormone gh and follicle-stimulating hormone-β fshb; liver estrogen receptor 1 esr1; gonad follicle-stimulating hormone receptor fshr, androgen receptors α and β ara and arb, vitellogenin receptor vtgr and P450 aromatase cyp19). Silver eels of both species showed a drop in pituitary gh expression, progressing gonadal development (GSI of ∼1.5 in European eels and ∼3.0 in shortfinned eels) and steroid level increases. In shortfinned eels, but not European eels, expression of fshb, gnrhr1 and gnrhr2, and d2br in the pituitary was up-regulated in the silver-stage as compared to yellow-stage females, as was expression of fshr, ara and arb in the ovaries. Expression of esr1 in European eels remained low while esr1 expression was up-regulated over 100-fold in silver shortfinned eels. The mechanistic model for anguillid vitellogenesis that we present suggests a first step that involves a drop in Gh and a second step that involves Fsh increase when switching in the life history trade-off from growth to reproduction. The drop in Gh is associated with gonadal development and plasma steroid increase but precedes brain-pituitary-gonad axis (BPG) activation. The Fsh increase marks BPG activation and increased sensitivity of the liver to estrogenic stimulation, but also an increase in D2br-mediated dopaminergic signaling to the pituitary.
Collapse
Affiliation(s)
- P Jéhannet
- Wageningen University & Research Animal Breeding and Genomics, Wageningen Livestock Research, PO Box 338, 6700 AH Wageningen, The Netherlands
| | - L Kruijt
- Wageningen University & Research Animal Breeding and Genomics, Wageningen Livestock Research, PO Box 338, 6700 AH Wageningen, The Netherlands
| | - E L Damsteegt
- Department of Zoology, University of Otago, 340 Great King Street, PO Box 56, Dunedin 9054, New Zealand
| | - W Swinkels
- DUPAN Foundation, Bronland 12-D, 6700 AE Wageningen, The Netherlands
| | - L T N Heinsbroek
- Wageningen University & Research Animal Breeding and Genomics, Wageningen Livestock Research, PO Box 338, 6700 AH Wageningen, The Netherlands; Wageningen Eel Reproduction Experts B.V., Mennonietenweg 13, 6702 AB Wageningen, The Netherlands
| | - P M Lokman
- Department of Zoology, University of Otago, 340 Great King Street, PO Box 56, Dunedin 9054, New Zealand
| | - A P Palstra
- Wageningen University & Research Animal Breeding and Genomics, Wageningen Livestock Research, PO Box 338, 6700 AH Wageningen, The Netherlands.
| |
Collapse
|
6
|
Androstenedione and 17α-methyltestosterone induce early ovary development of Anguilla japonica. Theriogenology 2018; 120:16-24. [PMID: 30081244 DOI: 10.1016/j.theriogenology.2018.07.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 07/11/2018] [Accepted: 07/14/2018] [Indexed: 11/22/2022]
Abstract
Endocrine effects as 11-ketotestosterone (11-KT), an unaromatizable androgen, regulating the follicles growth in the previtellogenic stage of eel reproduction have been widely elucidated. However, the influence of aromatizable androgens on the brain-pituitary-gonad axis during oogenesis in A. japonica has not been clearly elaborated. In the study, androstenedione (AD) and 17α-methyltestosterone (MT) were employed together to induce ovary development of seven-year-old female Anguilla japonica through feeding or exposure in the migration season. After female A. japonica had been fed with commercial diet containing 5 mg AD and MT kg d-1 body weight respectively for 45 d in fresh water (Trial I), the development of oocytes still remained at the oil droplet stage, but the GSI and follicle diameter increased significantly. The serum 11-KT level and expression of liver vitellogenin mRNA were significantly elevated. After female fish had been exposed to seawater containing 50 μg L-1 AD and MT respectively for 45 d (Trial II), the ovaries of A. japonica almost reached midvitellogenic stage and the GSI and follicle diameter increased significantly. Yolk granular layer was observed in the peripheral ooplasm. The serum 11-KT level maintained consistently low, and the serum E2 level declined significantly to a relatively low level. The expression levels of ovarian arα and cyp19a1, brain (with pituitary together) mGnRH and lhβ increased significantly. The results showed that A. japonica in Trial II appeared a higher ovarian development than those in Trial I. These findings indicated that AD and MT increased the oil droplet and enlarged follicle diameter in previtellogenic stage, while the vitellogenesis and gonadotropin release did not occur in Trial I. In Trial II, AD and MT promoted vitellogenesis by stimulating the ovary expression of arα and by up-regulating brain mGnRH and pituitary lhβ expression.
Collapse
|
7
|
Trautner JH, Reiser S, Blancke T, Unger K, Wysujack K. Metamorphosis and transition between developmental stages in European eel (Anguilla anguilla, L.) involve epigenetic changes in DNA methylation patterns. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2017; 22:139-145. [DOI: 10.1016/j.cbd.2017.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 04/04/2017] [Accepted: 04/04/2017] [Indexed: 12/24/2022]
|
8
|
Jolly C, Rousseau K, Prézeau L, Vol C, Tomkiewicz J, Dufour S, Pasqualini C. Functional Characterisation of Eel Dopamine D2 Receptors and Involvement in the Direct Inhibition of Pituitary Gonadotrophins. J Neuroendocrinol 2016; 28. [PMID: 27453551 DOI: 10.1111/jne.12411] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 06/21/2016] [Accepted: 07/20/2016] [Indexed: 01/11/2023]
Abstract
In various vertebrate species, dopamine (DA) exerts an inhibitory action on reproduction. In the European eel, DA plays a pivotal role in the inhibitory control of gonadotroph function and the blockade of puberty. In vivo studies have suggested that this effect is mediated by receptors pharmacologically related to the D2 family. In the European eel, two distinct D2 receptor (D2-R) paralogous genes have been identified (D2A-R and D2B-R) and both were shown to be expressed in the pituitary. We investigated the potential role of each paralogue in the control of gonadotroph function in this species. Eel recombinant D2A-R or D2B-R were expressed in HEK 293 cells, with a universal Gα subunit, and receptor activation was followed by inositol phosphate production. Recombinant D2-Rs exhibited a comparable affinity for DA, although they had differential affinities for mammalian D2-R agonists and antagonists, supporting subtle structure/activity differences. Furthermore, using eel pituitary cell primary cultures, the expression by gonadotroph cells of both native eel D2-R paralogues was examined by in situ hybridisation of D2A-R or D2B-R transcripts, coupled with immunofluorescence of luteinising hormone (LH)β or follicle-stimulating (FSH)β. LH and to a lesser extent, FSH cells expressed both D2-R transcripts but with a clear predominance of D2B-R. Notably, D2B-R transcripts were detected for the majority of LH cells. Accordingly, using these cultures, we showed that DA potently inhibited basal and testosterone-stimulated LHβ expression and less potently basal and activin-stimulated FSHβ expression. We also tested some D2-R antagonists, aiming to select the most adequate one to be used in innovative protocols for induction of eel sexual maturation. We identified eticlopride as the most potent inhibitor of DA action on basal and stimulated LH expression in vitro. Our data suggest a differential functionalisation of the duplicated receptor genes and demonstrate that mainly D2B-R is involved in the dopaminergic inhibitory control of eel gonadotroph function.
Collapse
Affiliation(s)
- C Jolly
- Muséum National d'Histoire Naturelle, Sorbonne Universités, Research Unit BOREA, Biologie des Organismes et Ecosystèmes Aquatiques, CNRS 7208, IRD207, UPMC, UCN, UA, Paris, France
| | - K Rousseau
- Muséum National d'Histoire Naturelle, Sorbonne Universités, Research Unit BOREA, Biologie des Organismes et Ecosystèmes Aquatiques, CNRS 7208, IRD207, UPMC, UCN, UA, Paris, France
| | - L Prézeau
- CNRS UMR5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM U661, Montpellier, France
- Université de Montpellier 1 & 2, Montpellier, France
| | - C Vol
- CNRS UMR5203, Institut de Génomique Fonctionnelle, Montpellier, France
- INSERM U661, Montpellier, France
- Université de Montpellier 1 & 2, Montpellier, France
| | - J Tomkiewicz
- National Institute of Aquatic Resources, Technical University of Denmark, Charlottenlund, Denmark
| | - S Dufour
- Muséum National d'Histoire Naturelle, Sorbonne Universités, Research Unit BOREA, Biologie des Organismes et Ecosystèmes Aquatiques, CNRS 7208, IRD207, UPMC, UCN, UA, Paris, France.
| | - C Pasqualini
- Institut des Neurosciences Paris-Saclay, Développement et Evolution de la Neurotransmission, Département Dev-Evo, Université Paris Sud, CNRS UMR 9197, Gif-Sur-Yvette, France.
| |
Collapse
|