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Shi M, Liu C, Qin Y, Yv L, Lu W. α1 and β3 adrenergic receptor-mediated excitatory effects of adrenaline on the caudal neurosecretory system (CNSS) in olive flounder, Paralichthys olivaceus. Gen Comp Endocrinol 2024; 349:114468. [PMID: 38325527 DOI: 10.1016/j.ygcen.2024.114468] [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: 11/28/2023] [Revised: 01/14/2024] [Accepted: 02/03/2024] [Indexed: 02/09/2024]
Abstract
Adrenaline is one of the most important neurotransmitters in the central nervous system and is produced during stress. In this study, we investigated the modulatory role of adrenaline and adrenergic receptors on the neuroendocrine Dahlgren cells in the caudal neurosecretory system (CNSS) of olive flounder. Ex vivo electrophysiological recordings revealed that adrenaline significantly increased the firing frequency and altered the firing pattern of Dahlgren cells. Moreover, treatment with adrenaline led to a significant upregulation of ion channels and major hormone secretion genes in CNSS at the mRNA levels. Additionally, treatment with adrenaline resulted in a significantly elevation in the expression levels of α1- and β3-adrenergic receptors. Furthermore, the β3-adrenergic receptor antagonist exerts a significant inhibitory effect on adrenaline-induced enhancement firing activities of Dahlgren cells, whereas the α1-adrenergic receptor antagonist displays a comparatively weaker inhibitory effect. Additionally, the enhanced firing activity induced by adrenaline could be effectively suppressed by both α1- and β3-adrenergic receptor antagonists. Taken together, these findings provide strong evidence in favor of the excitatory effects of adrenaline through α1 and β3 adrenergic receptors in CNSS to stimulate the secretion of stress-related hormones, β3-adrenergic receptor plays a more dominant role in the modulation of firing activities of Dahlgren cells by adrenaline and thereby regulates the stress response in olive flounder.
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Affiliation(s)
- Mengmeng Shi
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Cheng Liu
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Yeyang Qin
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Lin Yv
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai 201306, China.
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Shi M, Rupia EJ, Jiang P, Lu W. Switch from fight-flight to freeze-hide: The impacts of severe stress and brain serotonin on behavioral adaptations in flatfish. FISH PHYSIOLOGY AND BIOCHEMISTRY 2024:10.1007/s10695-024-01298-6. [PMID: 38308734 DOI: 10.1007/s10695-024-01298-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 01/01/2024] [Indexed: 02/05/2024]
Abstract
Animals often experience changes in their environment that can be perceived as stressful. Previous evidence indicates that different individuals may have distinct stress responses. The role of serotonin (5-HT) in stress adaptation is well established, but its relationship with different defense strategies and the persistence of physiological and behavioral responses in different individuals during repeated acute stress remain unclear. In this study, using olive flounder (Paralichthys olivaceus) as a model, we analyzed the relationship between boldness and neurotransmitter 5-HT activity. We found that 5-HT suppression with 5-HT synthesis inhibitor p-chlorophenylalanine (pCPA) and 5-HT receptor subtype 1A (5-HT1A) antagonist WAY-100635 increased their oxygen consumption rates and the boldness of shy individuals. We determined the metabolic and behavioral changes in bold and shy individuals to repeated acute stress. The results suggest that bold individuals switch on passive "energy-saving" personality by changing their defense behavior from "fight-flight" to "freeze-hide" during a threat encounter, which manifests high behavioral plasticity. Both behavioral types decreased their spontaneous activity levels, which were also strengthened by limiting metabolic rate. Interestingly, treatment with pCPA and WAY-100635 before stress procedure attenuated stress and increased the boldness across diverse behavioral types. This study provides the initial empirical evidence of how perception of stress impacts both individual defense behavior and personality in this species. These findings can enhance our comprehension of individual variability and behavioral plasticity in animals, thereby improving our ability to develop effective adaptive management strategies.
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Affiliation(s)
- Mengmeng Shi
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai, 201306, China
- International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai, 201306, China
| | - Emmanuel J Rupia
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai, 201306, China
- School of Biological Science, The University of Dodoma, Dodoma, Tanzania
| | - Pengxin Jiang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai, 201306, China
- International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai, 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China.
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai, 201306, China.
- International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai, 201306, China.
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Jiang P, Fang S, Huang N, Lu W. The excitatory effect of 5-HT 1A and 5-HT 2B receptors on the caudal neurosecretory system Dahlgren cells in olive flounder, Paralichthys olivaceus. Comp Biochem Physiol A Mol Integr Physiol 2023; 283:111457. [PMID: 37269940 DOI: 10.1016/j.cbpa.2023.111457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 05/26/2023] [Accepted: 05/29/2023] [Indexed: 06/05/2023]
Abstract
The neurotransmitter 5-hydroxytryptamine (5-HT, serotonin) plays an essential role in the regulation of neural activity via multiple receptors. Here, we investigated the functional role of serotoninergic input on the Dahlgren cell population in the caudal neurosecretory system (CNSS) of olive flounder. In this study, the effect of 5-HT on the firing activity of Dahlgren cells was explored in terms of changes in firing frequency and firing pattern using multicellular recording electrophysiology ex vivo, and the role of several 5-HT receptor subtypes in the regulation was determined. The results revealed that 5-HT increased the firing frequency in a concentration-dependent manner and altered the firing pattern of Dahlgren cells. The effect of 5-HT on the firing activity of Dahlgren cells was mediated through the 5-HT1A and 5-HT2B receptors, selective agonists of both receptors effectively increased the firing frequency of Dahlgren cells, and selective receptor antagonists could also effectively inhibit the increase in firing frequency caused by 5-HT. In addition, the mRNA levels of major signaling pathway-related genes, ion channels, and major secretion hormone genes were significantly upregulated in CNSS after treatment with 5-HT. These findings demonstrate that 5-HT acts as an excitatory neuromodulator on Dahlgren cells and enhances neuroendocrine activity in CNSS.
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Affiliation(s)
- Pengxin Jiang
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Shilin Fang
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Nini Huang
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai 201306, China.
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Tostivint H, Girardot F, Parmentier C, Pézeron G. [The caudal neurosecretory system, the other "neurohypophysial" system in fish]. Biol Aujourdhui 2023; 216:89-103. [PMID: 36744974 DOI: 10.1051/jbio/2022016] [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: 06/01/2022] [Indexed: 02/07/2023]
Abstract
The caudal neurosecretory system (CNSS) is a neuroendocrine complex whose existence is specific to fishes. Structurally, it has many similarities with the hypothalamic-neurohypophyseal complex of other vertebrates. However, it differs regarding its position at the caudal end of the spinal cord and the nature of the hormones it secretes, the most important being urotensins. The CNSS was first described more than 60 years ago, but its embryological origin is totally unknown and its role is still poorly understood. Paradoxically, it is almost no longer studied today. Recent developments in imaging and genome editing could make it possible to resume investigations on CNSS in order to solve the mysteries that still surround it.
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Affiliation(s)
- Hervé Tostivint
- Muséum National d'Histoire Naturelle, CNRS UMR 7221, Physiologie moléculaire et adaptation, 75005 Paris, France
| | - Fabrice Girardot
- Muséum National d'Histoire Naturelle, CNRS UMR 7221, Physiologie moléculaire et adaptation, 75005 Paris, France
| | - Caroline Parmentier
- Sorbonne Université, CNRS UMR 8246, INSERM U1130, IBPS, Neurosciences Paris Seine, Neuroplasticité des comportements de reproduction, 75005 Paris, France
| | - Guillaume Pézeron
- Muséum National d'Histoire Naturelle, CNRS UMR 7221, Physiologie moléculaire et adaptation, 75005 Paris, France
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Jiang P, Pan X, Zhang W, Dai Z, Lu W. Neuromodulatory effects of GnRH on the caudal neurosecretory Dahlgren cells in female olive flounder. Gen Comp Endocrinol 2021; 307:113754. [PMID: 33711313 DOI: 10.1016/j.ygcen.2021.113754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 02/19/2021] [Accepted: 02/28/2021] [Indexed: 01/28/2023]
Abstract
Gonadotropin-releasing hormone (GnRH) is considered a key player in reproduction. The caudal neurosecretory system (CNSS) is a unique neurosecretory structure of fish that may be involved in osmoregulation, nutrition, reproduction, and stress-related responses. However, a direct effect of GnRH on Dahlgren cells remains underexplored. Here, we examined the electrophysiological response of Dahlgren cell population of the CNSS to GnRH analog LHRH-A2 and the transcription of related key genes of CNSS. We found that GnRH increased overall firing frequency and may be changed the firing pattern from silent to burst or phasic firing in a subpopulation of Dahlgren cells. The effect of GnRH on a subpopulation of Dahlgren cells firing activity was blocked by the GnRH receptor (GnRH-R) antagonist cetrorelix. A positive correlation was observed between the UII and GnRH-R mRNA levels in CNSS or gonadosomatic index (GSI) during the breeding season. These findings are the first demonstration of the ability of GnRH acts as a modulator within the CNSS and add to our understanding of the physiological role of the CNSS in reproduction and seasonal adaptation.
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Affiliation(s)
- Pengxin Jiang
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Xinbei Pan
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Wei Zhang
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Zhiqi Dai
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai 201306, China.
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Lan Z, Zhang W, Xu J, Lu W. GABA A receptor-mediated inhibition of Dahlgren cells electrical activity in the olive flounder, Paralichthys olivaceus. Gen Comp Endocrinol 2021; 306:113753. [PMID: 33711316 DOI: 10.1016/j.ygcen.2021.113753] [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: 02/23/2020] [Revised: 02/10/2021] [Accepted: 02/28/2021] [Indexed: 11/24/2022]
Abstract
γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the central nervous system. We investigated its potential role as a neurotransmitter in the neuroendocrine Dahlgren cell population of the caudal neurosecretory system (CNSS) of the flounder Paralichthys olivaceus. The application of GABA in vitro resulted in a decrease in electrical activity of Dahlgren cells, followed by an increase of the number of silent cells, together with a decreased firing frequency of all three activity patterns (tonic, phasic, bursting). GABAA receptor agonist etomidate decreased Dahlgren cell firing activity, in a similar way to GABA. The response to GABA was blocked by the GABAA receptor antagonist bicuculline. GABAA receptor gamma2 subunit (Gabrg2) and chloride channel (Clcn2) mRNA expression were significantly upregulated in the CNSS after GABA superfusion. These data suggest that GABA may modulate CNSS activity in vivo mediated by GABAA receptors.
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Affiliation(s)
- Zhaohui Lan
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Wei Zhang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Jinling Xu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China.
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7
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Lu W, Zhu G, Chen A, Li X, McCrohan CR, Balment R. Gene expression and hormone secretion profile of urotensin I associated with osmotic challenge in caudal neurosecretory system of the euryhaline flounder, Platichthys flesus. Gen Comp Endocrinol 2019; 277:49-55. [PMID: 30633873 DOI: 10.1016/j.ygcen.2019.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 01/03/2019] [Accepted: 01/08/2019] [Indexed: 11/17/2022]
Abstract
The caudal neurosecretory system (CNSS) is a part of stress response system, a neuroendocrine structure unique to fish. To gain a better understanding of the physiological roles of CNSS in fluid homeostasis, we characterized the tissue distribution of urotensin I (UI) expression in European flounder (Platichthys flesus), analyzed the effect chronic exposure to seawater (SW) or freshwater (FW), transfer from SW to FW, and reverse transfer on mRNA levels of UI, L-type Ca2+ channels and Ca-activated K+ channels transcripts in CNSS. The tissue distribution demonstrated that the CNSS is dominant sites of UI expression, and UI mRNA level in fore brain appeared greater than other non-CNSS tissues. There were no consistent differences in CNSS UI expression or urophysis UI content between SW- and FW-adapted fish in July and September. After transfer from SW to FW, at 8 h CNSS UI expression was significantly increased, but urophysis UI content was no significantly changes. At 24 h transfer from SW to FW, expression of CNSS UI was no apparent change and urophysis UI content was reduced. At 8 h and 24 h after transfer from FW to SW UI expression and urophysis UI content was no significantly effect. The expression of bursting dependent L-type Ca2+ channels and Ca-activated K+ channels in SW-adapted fish significantly decreased compared to those in FW-adapted. However, there were no differences in transfer from SW to FW or from FW to SW at 8 h and 24 h. Thus, these results suggest CNSS UI acts as a modulator in response to osmotic stress and plays important roles in the body fluid homeostasis.
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Affiliation(s)
- Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China.
| | - Gege Zhu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Aqin Chen
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Xiaoxue Li
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Catherine R McCrohan
- Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, M13 9PT, UK
| | - Richard Balment
- Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, M13 9PT, UK
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Lan Z, Xu J, Wang Y, Lu W. Modulatory effect of glutamate GluR2 receptor on the caudal neurosecretory Dahlgren cells of the olive flounder, Paralichthys olivaceus. Gen Comp Endocrinol 2018; 261:9-22. [PMID: 29355533 DOI: 10.1016/j.ygcen.2018.01.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 01/13/2018] [Accepted: 01/14/2018] [Indexed: 11/26/2022]
Abstract
A neuromodulatory role for glutamate has been reported for magnocellular neuroendocrine cells in mammalian hypothalamus. We examined the potential role of glutamate as a local intercellular messenger in the neuroendocrine Dahlgren cell population of the caudal neurosecretory system (CNSS) in the euryhaline flounder Paralichthys olivaceus. In pharmacological experiments in vitro, glutamate (Glu) caused an increase in electrical activity of Dahlgren cells, recruitment of previously silent cells, together with a greater proportion of cells showing phasic (irregular) activity. The glutamate substrate, glutamine (Gln), led to increased firing frequency, cell recruitment and enhanced bursting activity. The glutamate effect was not blocked by the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801, or the GluR1/GluR3 (AMPA) receptor antagonist IEm1795-2HBr, but was blocked by the broad-spectrum α-amino-3-hydroxy- 5- methyl-4-isoxazo-lepropionic acid (AMPA) receptor antagonist ZK200775. Our transcriptome sequencing study revealed three AMPA receptor (GluR1, GluR2 and GluR3) in the olive flounder CNSS. Quantitative RT-PCR revealed that GluR2 receptor mRNA expression was significant increased following dose-dependent superfusion with glutamate in the CNSS. GluR1 and GluR3 receptor mRNA expression were decreased following superfusion with glutamate. L-type Ca2+ channel mRNA expression had a significant dose-dependent decrease following superfusion with glutamate, compared to the control. In the salinity challenge experiment, acute transfer from SW to FW, GluR2 receptor mRNA expression was significantly higher than the control at 2 h. These findings suggest that GluR2 is one of the mechanisms which can medicate glutamate action within the CNSS, enhancing electrical activity and hence secretory output.
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Affiliation(s)
- Zhaohui Lan
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Jinling Xu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Youji Wang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China.
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Marley R, Lu W, Balment RJ, McCrohan CR. Cortisol and prolactin modulation of caudal neurosecretory system activity in the euryhaline flounder Platichthys flesus. Comp Biochem Physiol A Mol Integr Physiol 2008; 151:71-7. [DOI: 10.1016/j.cbpa.2008.05.180] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 05/30/2008] [Accepted: 05/30/2008] [Indexed: 11/27/2022]
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Lu W, Worthington J, Riccardi D, Balment RJ, McCrohan CR. Seasonal changes in peptide, receptor and ion channel mRNA expression in the caudal neurosecretory system of the European flounder (Platichthys flesus). Gen Comp Endocrinol 2007; 153:262-72. [PMID: 17562341 DOI: 10.1016/j.ygcen.2007.05.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 04/26/2007] [Accepted: 05/01/2007] [Indexed: 11/24/2022]
Abstract
The caudal neurosecretory system (CNSS) of the euryhaline flounder Platichthys flesus has suggested roles in osmoregulatory, reproductive and nutritional adaptation, as fish migrate between seawater (winter) and brackish/freshwater (summer) environments. This study examined seasonal changes in mRNA expression profile of functionally important genes in the CNSS. cDNAs encoding neuropeptides, receptors and ion channels were cloned by reverse transcriptase polymerase chain reaction (RT-PCR) and screening of a flounder CNSS cDNA library. The expression profile of cloned genes was determined by real-time RT-PCR at 2-month intervals throughout the year in CNSS from seawater-adapted fish. Plasma cortisol (measured by radioimmunoassay) showed a peak in April, the time of spawning. Expression levels of mRNA for peptides urotensins I and II (UI, UII) and corticotropin releasing factor (CRF) all showed a seasonal cycle, with lowest expression in April and highest in August-October. The expression of CRF2(UI), UT(UII) and CRF1 receptors was not correlated with corresponding peptide expression. Receptors for potential neuromodulators of CNSS activity also displayed a seasonal mRNA expression profile. Glucocorticoid, 5-hydroxytryptamine, kappa-opioid and glutamate receptor expression peaked around April, suggesting that modulation of electrical activity of the neurosecretory Dahlgren cells is of particular importance at this time. Expression of mRNA for L-type Ca(2+) and Ca-activated K(+) channels was lower during the summer months. These channels underlie electrical bursting activity in Dahlgren cells. Ion channel mRNA expression was also lower in CNSS from flounder fully adapted to freshwater as opposed to seawater, consistent with previously reported observations of reduced bursting activity in Dahlgren cells from freshwater-adapted CNSS. These findings support the hypothesis that the CNSS is functionally reprogrammed to cope with changes in physiological challenge as fish migrate between sea and estuaries in winter and spring.
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Affiliation(s)
- Weiqun Lu
- Faculty of Life Sciences, The University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester M13 9PT, UK
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Marley R, Lu W, Balment RJ, McCrohan CR. Evidence for nitric oxide role in the caudal neurosecretory system of the European flounder, Platichthys flesus. Gen Comp Endocrinol 2007; 153:251-61. [PMID: 17362951 DOI: 10.1016/j.ygcen.2007.01.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 01/26/2007] [Accepted: 01/28/2007] [Indexed: 11/19/2022]
Abstract
A neuromodulatory role for nitric oxide has been reported for magnocellular neuroendocrine cells in mammalian hypothalamus. We examined its potential as a local intercellular messenger in the neuroendocrine Dahlgren cell population of the caudal neurosecretory system (CNSS) of the euryhaline flounder. Immunocytochemistry using an antibody raised against human neuronal nitric oxide synthase (NOS) indicated the presence of NOS in the Dahlgren cells. Quantitative RT-PCR, using a flounder-specific probe, revealed NOS mRNA expression in the CNSS. In July, though not in September, NOS mRNA expression was significantly higher in fish fully adapted to seawater, compared to freshwater-adapted fish. Following acute transfer of fish from freshwater to seawater, NOS mRNA expression was elevated at 8h and then recovered by 24h. In pharmacological experiments in vitro, application of NO donors (SNAP, SNP) caused an increase in electrical activity (firing frequency) of Dahlgren cells, recruitment of previously silent cells, together with a greater proportion of cells showing phasic (irregular) activity. The NOS substrate, l-arginine, led to increased firing frequency, cell recruitment and enhanced bursting activity. However, this effect was not blocked by the NOS inhibitor L-NAME. These findings suggest that NO acts as a modulator within the CNSS, potentially enhancing electrical activity and hence secretory output. A role in supporting adaptation to hyperosmotic conditions is also indicated.
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Affiliation(s)
- Richard Marley
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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McCrohan CR, Lu W, Brierley MJ, Dow L, Balment RJ. Fish caudal neurosecretory system: a model for the study of neuroendocrine secretion. Gen Comp Endocrinol 2007; 153:243-50. [PMID: 17316635 DOI: 10.1016/j.ygcen.2006.12.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 12/05/2006] [Accepted: 12/26/2006] [Indexed: 11/30/2022]
Abstract
The caudal neurosecretory system (CNSS) is unique to fish and has suggested homeostatic roles in osmoregulation and reproduction. Magnocellular neuroendocrine Dahlgren cells, located in the terminal segments of the spinal cord, project to a neurohaemal organ, the urophysis, from which neuropeptides are released. In the euryhaline flounder Platichthys flesus Dahlgren cells synthesise at least four peptides, including urotensins I and II and CRF. These peptides are differentially expressed with co-localisation of up to three in a single cell. Dahlgren cells display a range of electrical firing patterns, including characteristic bursting activity, which is dependent on L-type Ca(2+) and Ca-activated K(+)channels. Activity is modulated by a range of extrinsic and intrinsic neuromodulators. This includes autoregulation by the secreted peptides themselves, leading to enhanced bursting. Electrophysiological and mRNA expression studies have examined changes in response to altered physiological demands. Bursting activity is more robust and more Dahlgren cells are recruited in seawater compared to freshwater adapted fish and this is mirrored by a reduction in mRNA expression for L-type Ca(2+) and Ca-activated K(+) channels. Acute seawater/freshwater transfer experiments support a role for UII in adaptation to hyperosmotic conditions. Responses to stress suggest a shared role for CRF and UI, released from the CNSS. We hypothesise that the Dahlgren cell population is reprogrammed, both in anticipation of and in response to changed physiological demands, and this is seen as changes in gene expression profile and electrical activity. The CNSS shows striking parallels with the hypothalamic-neurohypophysial system, providing a highly accessible system for studies of neuroendocrine mechanisms. Furthermore, the presence of homologues of urotensins throughout the vertebrates has sparked new interest in these peptides and their functional evolution.
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Affiliation(s)
- Catherine R McCrohan
- Faculty of Life Sciences, University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester M13 9PT, UK.
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Leng G, Ludwig M. Jacques Benoit Lecture. Information processing in the hypothalamus: peptides and analogue computation. J Neuroendocrinol 2006; 18:379-92. [PMID: 16684129 DOI: 10.1111/j.1365-2826.2006.01428.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptides in the hypothalamus are not like conventional neurotransmitters; their release is not particularly associated with synapses, and their long half-lives mean that they can diffuse to distant targets. Peptides can act on their cells of origin to facilitate the development of patterned electrical activity, they can act on their neighbours to bind the collective activity of a neural population into a coherent signalling entity, and the co-ordinated population output can transmit waves of peptide secretion that act as a patterned hormonal analogue signal within the brain. At their distant targets, peptides can re-programme neural networks, by effects on gene expression, synaptogenesis, and by functionally rewiring connections by priming activity-dependent release.
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Affiliation(s)
- G Leng
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
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Ashworth AJ, Banks JR, Brierley MJ, Balment RJ, McCrohan CR. Electrical activity of caudal neurosecretory neurons in seawater and freshwater-adapted Platichthys flesus, in vivo. J Exp Biol 2005; 208:267-75. [PMID: 15634846 DOI: 10.1242/jeb.01372] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
This study examined the electrical firing activity of neuroendocrine Dahlgren cells in the caudal neurosecretory system (CNSS) of the euryhaline flounder in vivo. Intracellular recordings revealed generally similar activity patterns and membrane properties to those previously reported in vitro. To investigate the potential role of the CNSS in osmoregulatory adaptation, extracellular, multiunit, recordings compared the activity patterns of Dahlgren cells in fully seawater- and freshwater-adapted fish. The proportion of cells showing bursting (as opposed to phasic or tonic) activity was greater in seawater-than in freshwater-adapted fish, as was the Correlation Index, a measure of the degree of correlation between firing activities of cells recorded simultaneously from the same preparation. Acute transfer of fish from seawater to freshwater gill perfusion led to recruitment of previously silent Dahlgren cells and a reduction in Correlation Index;freshwater to seawater transfer increased the Correlation Index. Severing the spinal cord anterior to the CNSS led to an increase in overall Dahlgren cell activity. Electrical stimulation of branchial nerve branches providing input to the brainstem, or tactile (pinch) stimulation of lips or fins, led to a reduction in CNSS activity lasting up to 500 s, indicating the presence of descending modulatory pathways from the brain. These results are consistent with a role for CNSS neuropeptides, urotensins, in supporting survival in a hypertonic, seawater, environment.
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Affiliation(s)
- A J Ashworth
- Faculty of Life Sciences, The University of Manchester, Manchester M13 9PT, UK
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