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Reed M, Pan W, Musa L, Arlotta S, Mennigen JA, Jonz MG. A role for dopamine in control of the hypoxic ventilatory response via D 2 receptors in the zebrafish gill. J Comp Neurol 2024; 532:e25548. [PMID: 37837632 DOI: 10.1002/cne.25548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 09/21/2023] [Accepted: 10/03/2023] [Indexed: 10/16/2023]
Abstract
Dopamine is a neurotransmitter involved in oxygen sensing and control of reflex hyperventilation. In aquatic vertebrates, oxygen sensing occurs in the gills via chemoreceptive neuroepithelial cells (NECs), but a mechanism for dopamine in autonomic control of ventilation has not been defined. We used immunohistochemistry and confocal microscopy to map the distribution of tyrosine hydroxylase (TH), an enzyme necessary for dopamine synthesis, in the gills of zebrafish. TH was found in nerve fibers of the gill filaments and respiratory lamellae. We further identified dopamine active transporter (dat) and vesicular monoamine transporter (vmat2) expression in neurons of the gill filaments using transgenic lines. Moreover, TH- and dat-positive nerve fibers innervated NECs. In chemical screening assays, domperidone, a D2 receptor antagonist, increased ventilation frequency in zebrafish larvae in a dose-dependent manner. When larvae were confronted with acute hypoxia, the D2 agonist, quinpirole, abolished the hyperventilatory response. Quantitative polymerase chain reaction confirmed expression of drd2a and drd2b (genes encoding D2 receptors) in the gills, and their relative abundance decreased following acclimation to hypoxia for 48 h. We localized D2 receptor immunoreactivity to NECs in the efferent gill filament epithelium, and a novel cell type in the afferent filament epithelium. We provide evidence for the synthesis and storage of dopamine by sensory nerve terminals that innervate NECs. We further suggest that D2 receptors on presynaptic NECs provide a feedback mechanism that attenuates the chemoreceptor response to hypoxia. Our studies suggest that a fundamental, modulatory role for dopamine in oxygen sensing arose early in vertebrate evolution.
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Affiliation(s)
- Maddison Reed
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Wen Pan
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Lina Musa
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Stefania Arlotta
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Jan A Mennigen
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Michael G Jonz
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, Ontario, Canada
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2
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Perry SF, Pan YK, Gilmour KM. Insights into the control and consequences of breathing adjustments in fishes-from larvae to adults. Front Physiol 2023; 14:1065573. [PMID: 36793421 PMCID: PMC9923008 DOI: 10.3389/fphys.2023.1065573] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 01/11/2023] [Indexed: 01/31/2023] Open
Abstract
Adjustments of ventilation in fishes to regulate the volume of water flowing over the gills are critically important responses to match branchial gas transfer with metabolic needs and to defend homeostasis during environmental fluctuations in O2 and/or CO2 levels. In this focused review, we discuss the control and consequences of ventilatory adjustments in fish, briefly summarizing ventilatory responses to hypoxia and hypercapnia before describing the current state of knowledge of the chemoreceptor cells and molecular mechanisms involved in sensing O2 and CO2. We emphasize, where possible, insights gained from studies on early developmental stages. In particular, zebrafish (Danio rerio) larvae have emerged as an important model for investigating the molecular mechanisms of O2 and CO2 chemosensing as well as the central integration of chemosensory information. Their value stems, in part, from their amenability to genetic manipulation, which enables the creation of loss-of-function mutants, optogenetic manipulation, and the production of transgenic fish with specific genes linked to fluorescent reporters or biosensors.
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3
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Leonard EM, Weaver FE, Nurse CA. Lactate sensing by neuroepithelial cells isolated from the gills of killifish (Fundulus heteroclitus). J Exp Biol 2022; 225:285898. [PMID: 36420741 DOI: 10.1242/jeb.245088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/16/2022] [Indexed: 11/25/2022]
Abstract
Lactate is produced in most vertebrate cells as a by-product of anaerobic metabolism. In addition to its role as a fuel for many tissues, circulating lactate can act as a signalling molecule and stimulates ventilation in air- and water-breathing vertebrates. Recent evidence suggests lactate acts on O2- and CO2/H+-sensitive chemoreceptors located in the mammalian carotid body. While analogous receptors (neuroepithelial cells or NECs) in fish gills are presumed to also function as lactate sensors, direct evidence is lacking. Here, using ratiometric Fura-2 Ca2+ imaging, we show that chemosensitive NECs isolated from killifish gills respond to lactate (5-10 mmol l-1; pHe ∼7.8) with intracellular Ca2+ elevations. These responses were inhibited by an L-type Ca2+ channel blocker (nifedipine; 0.5 µmol l-1), a monocarboxylic acid transporter (MCT) blocker (α-cyano-4-hydroxycinnamate; 300 µmol l-1) or a competitive MCT substrate (pyruvate; 5 mmol l-1). These data provide the first direct evidence that gill NECs act as lactate sensors.
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Affiliation(s)
- Erin M Leonard
- Department of Biology, Wilfred Laurier University, Waterloo, ON, Canada, N2L 3C5
| | - Fiona E Weaver
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Colin A Nurse
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
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4
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Reed M, Jonz MG. Neurochemical Signalling Associated With Gill Oxygen Sensing and Ventilation: A Receptor Focused Mini-Review. Front Physiol 2022; 13:940020. [PMID: 35910553 PMCID: PMC9325958 DOI: 10.3389/fphys.2022.940020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 06/21/2022] [Indexed: 11/13/2022] Open
Abstract
Despite the large body of work describing vertebrate ventilatory responses to hypoxia, remarkably little is known about the receptors and afferent pathways mediating these responses in fishes. In this review, we aim to summarize all receptor types to date implicated in the neurotransmission or neuromodulation associated with O2 sensing in the gills of fish. This includes serotonergic, cholinergic, purinergic, and dopaminergic receptor subtypes. Recent transcriptomic analysis of the gills of zebrafish using single-cell RNA sequencing has begun to elucidate specific receptor targets in the gill; however, the absence of receptor characterization at the cellular level in the gill remains a major limitation in understanding the neurochemical control of hypoxia signalling.
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Affiliation(s)
- Maddison Reed
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Michael G. Jonz
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
- Brain and Mind Research Institute, University of Ottawa, ON, Ottawa, Canada
- *Correspondence: Michael G. Jonz,
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5
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Single-cell transcriptomic analysis of neuroepithelial cells and other cell types of the gills of zebrafish (Danio rerio) exposed to hypoxia. Sci Rep 2022; 12:10144. [PMID: 35710785 PMCID: PMC9203529 DOI: 10.1038/s41598-022-13693-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 05/26/2022] [Indexed: 12/21/2022] Open
Abstract
The fish gill is a multifunctional organ involved in numerous physiological processes, such as gas exchange and sensing of hypoxia by respiratory chemoreceptors, called neuroepithelial cells (NECs). Many studies have focused on zebrafish (Danio rerio) to investigate the structure, function and development of the gills, yet the transcriptomic profile of most gill cells remains obscure. We present the results of a comprehensive transcriptomic analysis of the gills of zebrafish using single-cell RNA sequencing (scRNA‐seq). Gill cells from ETvmat2:EGFP zebrafish were individually labelled before scRNA‐seq library construction using 10× Genomics Chromium technology. 12,819 cells were sequenced with an average depth of over 27,000 reads per cell. We identified a median of 485 genes per cell and 16 cell clusters, including NECs, neurons, pavement cells, endothelial cells and mitochondrion-rich cells. The identity of NECs was confirmed by expression of slc18a2, encoding the vesicular monoamine transporter, Vmat2. Highly differentially-expressed genes in NECs included tph1a, encoding tryptophan hydroxylase, sv2 (synaptic vesicle protein), and proteins implicated in O2 sensing (ndufa4l2a, cox8al and epas1a). In addition, NECs and neurons expressed genes encoding transmembrane receptors for serotonergic, cholinergic or dopaminergic neurotransmission. Differential expression analysis showed a clear shift in the transcriptome of NECs following 14 days of acclimation to hypoxia. NECs in the hypoxia group showed high expression of genes involved in cell cycle control and proliferation. The present article provides a complete cell atlas for the zebrafish gill and serves as a platform for future studies investigating the molecular biology and physiology of this organ.
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6
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Boggs TE, Friedman JS, Gross JB. Alterations to cavefish red blood cells provide evidence of adaptation to reduced subterranean oxygen. Sci Rep 2022; 12:3735. [PMID: 35260642 PMCID: PMC8904627 DOI: 10.1038/s41598-022-07619-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/15/2022] [Indexed: 11/10/2022] Open
Abstract
Animals inhabiting extreme environments allow the powerful opportunity to examine adaptive evolution in response to diverse pressures. One such pressure is reduced oxygen, commonly present at high-altitude and subterranean environments. Cave-dwelling animals must also deal with darkness and starvation, both of which have been rigorously studied as key forces driving the evolution of cave-associated traits. Interestingly, hypoxia as an environmental pressure has received less attention. Here we examined putatively adaptive phenotypes evolving in a freshwater teleost fish, Astyanax mexicanus, which includes both surface- and cave-dwelling forms. This model system also provides the opportunity to identify convergent responses to hypoxia, owing to the presence of numerous natural and independently-colonised cave populations, alongside closely-related surface conspecifics. The focus of this study is hemoglobin, an essential molecule for oxygen transport and delivery. We found that multiple cave populations harbor a higher concentration of hemoglobin in their blood, which is coincident with an increase in cave morph erythrocyte size compared to surface fish. Interestingly, both cave and surface morphs have comparable numbers of erythrocytes per unit of blood, suggesting elevated hemoglobin is not due to overproduction of red blood cells. Alternatively, owing to an increased cell area of erythrocytes in cavefish, we reason that they contain more hemoglobin per erythrocyte. These findings support the notion that cavefish have adapted to hypoxia in caves through modulation of both hemoglobin production and erythrocyte size. This work reveals an additional adaptive feature of Astyanax cavefish, and demonstrates that coordinated changes between cellular architecture and molecular changes are necessary for organisms evolving under intense environmental pressure.
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Affiliation(s)
- Tyler E Boggs
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Jessica S Friedman
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Joshua B Gross
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, 45221, USA.
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7
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Maina JN, Icardo JM, Zaccone G, Aragona M, Lauriano ER, Alesci A, Albano M, Guerrera MC, Germana A, Fernandes JMO, Kiron V, Capillo G. Immunohistochemical and ultrastructural study of the immune cell system and epithelial surfaces of the respiratory organs in the bimodally-breathing African sharptooth catfish (Clarias gariepinus Burchell, 1822). Anat Rec (Hoboken) 2022; 305:3212-3229. [PMID: 35142056 DOI: 10.1002/ar.24896] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/04/2022] [Accepted: 01/31/2022] [Indexed: 11/12/2022]
Abstract
Ach, represents the old neurotransmitter in central and peripheral nervous system. Its muscarinic and nicotinic receptors (mAChRs and nAChRs) constitute an independent cholinergic system that is found in immune cells and playsa key role in regulation of the immune function and cytokine production. Gas exchanging surfaces of the gills and air-breathing organs (ABOs) of the sharptooth catfish Clarias gariepinus were investigated using ultrastructural and confocal immunofluorescence techniques. This study was predominantly focused on the structure of the immune cell types, the expression of their neurotransmitters, including the antimicrobial peptide piscidin 1, and the functional significance of respiratory gas exchange epithelia. A network of immune cells (monocytes, eosinophils, and mast cells) was observed in the gill and theABO epithelia. Eosinophils containing 5HT immunoreactivity were seen in close association with mast cells expressing acetylcholine (Ach), 5HT, nNOS and piscidin 1. A rich and dense cholinergic innervation dispersing across the islet capillaries of the gas exchange barrier, and the localization of Ach in the squamous pavement cells covering the capillaries, were evidenced byVAChT antibodies.We report for the first time that piscidin 1(Pis 1) positive mast cells interact with Pis 1 positive nerves found in the epithelia of the respiratory organs.Pis 1 immunoreactivity was also observed in the covering respiratory epithelium of the ABOs and associated with a role in local mucosal immune defense . The above results anticipate future studies on the neuro-immune interactions at mucosal barrier surfaces, like the gill and the skin of fish, areas densely populated by different immune cells and sensory nerves that constantly sense and adapt to tissue-specific environmental challenges. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- John Ndegwa Maina
- Department of Zoology, Auckland Park Campus, University of Johannesburg, Johannesburg, South Africa
| | - Jose Manuel Icardo
- Department of Anatomy and Cell Biology, Faculty of Medicine, University of Cantabria, Santander, Spain
| | - Giacomo Zaccone
- Department of Veterinary Sciences, Polo Universitario dell'Annunziata, University of Messina, Italy
| | - Marialuisa Aragona
- Department of Veterinary Sciences, Polo Universitario dell'Annunziata, University of Messina, Italy
| | - Eugenia Rita Lauriano
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Italy
| | - Alessio Alesci
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Italy
| | - Marco Albano
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Italy
| | - Maria Cristina Guerrera
- Department of Veterinary Sciences, Polo Universitario dell'Annunziata, University of Messina, Italy
| | - Antonino Germana
- Department of Veterinary Sciences, Polo Universitario dell'Annunziata, University of Messina, Italy
| | | | - Viswanath Kiron
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Gioele Capillo
- Department of Veterinary Sciences, Polo Universitario dell'Annunziata, University of Messina, Italy.,Institute for Marine Biological Resources and Biotechnology (IRBIM) , National Research Council (CNR), Section of Messina, Messina, Italy
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8
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Cochrane PV, Jonz MG, Wright PA. The development of the O 2-sensing system in an amphibious fish: consequences of variation in environmental O 2 levels. J Comp Physiol B 2021; 191:681-699. [PMID: 34023926 DOI: 10.1007/s00360-021-01379-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 03/04/2021] [Accepted: 05/07/2021] [Indexed: 11/25/2022]
Abstract
Proper development of the O2-sensing system is essential for survival. Here, we characterized the development of the O2-sensing system in the mangrove rivulus (Kryptolebias marmoratus), an amphibious fish that transitions between hypoxic aquatic environments and O2-rich terrestrial environments. We found that NECs formed in the gills and skin of K. marmoratus during embryonic development and that both NEC populations are retained from the embryonic stage to adulthood. We also found that the hyperventilatory response to acute hypoxia was present in embryonic K. marmoratus, indicating that functional O2-sensing pathways are formed during embryonic development. We then exposed embryos to aquatic normoxia, aquatic hyperoxia, aquatic hypoxia, or terrestrial conditions for the first 30 days of embryonic development and tested the hypothesis that environmental O2 availability during embryonic development modulates the development of the O2-sensing system in amphibious fishes. Surprisingly, we found that O2 availability during embryonic development had little impact on the density and morphology of NECs in the gills and skin of K. marmoratus. Collectively, our results demonstrate that, unlike the only other species of fish in which NEC development has been studied to date (i.e., zebrafish), NEC development in K. marmoratus is largely unaffected by environmental O2 levels during the embryonic stage, indicating that there is interspecies variation in O2-induced plasticity in the O2-sensing system of fishes.
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Affiliation(s)
- Paige V Cochrane
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.
| | - Michael G Jonz
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
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9
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Pan W, Scott AL, Nurse CA, Jonz MG. Identification of oxygen-sensitive neuroepithelial cells through an endogenous reporter gene in larval and adult transgenic zebrafish. Cell Tissue Res 2021; 384:35-47. [PMID: 33404838 DOI: 10.1007/s00441-020-03307-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/17/2020] [Indexed: 11/28/2022]
Abstract
In teleost fish, specialized oxygen (O2) chemoreceptors, called neuroepithelial cells (NECs), are found in the gill epithelium in adults. During development, NECs are present in the skin before the formation of functional gills. NECs are known for retaining the monoamine neurotransmitter, serotonin (5-HT) and are conventionally identified through immunoreactivity with antibodies against 5-HT or synaptic vesicle protein (SV2). However, identification of NECs in live tissue and isolated cell preparations has been challenging due to the lack of a specific marker. The present study explored the use of the transgenic zebrafish, ETvmat2:GFP, which expresses green fluorescent protein (GFP) under the control of the vesicular monoamine transporter 2 (vmat2) regulatory element, to identify NECs. Using immunohistochemistry and confocal microscopy, we confirmed that the endogenous GFP in ETvmat2:GFP labelled serotonergic NECs in the skin of larvae and in the gills of adults. NECs of the gill filaments expressed a higher level of endogenous GFP compared with other cells. The endogenous GFP also labelled intrabranchial neurons of the gill filaments. Flow cytometric analysis demonstrated that filamental NECs could be distinguished from other dissociated gill cells based on high GFP expression alone. Acclimation to 2 weeks of severe hypoxia (PO2 = 35 mmHg) induced an increase in filamental NEC frequency, size and GFP gene expression. Here we present for the first time a transgenic tool that labels O2 chemoreceptors in an aquatic vertebrate and its use in high-throughput experimentation.
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Affiliation(s)
- Wen Pan
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt., Ottawa, ON, K1N 6N5, Canada
| | - Angela L Scott
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Colin A Nurse
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Michael G Jonz
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt., Ottawa, ON, K1N 6N5, Canada.
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10
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Porteus C, Kumai Y, Abdallah SJ, Yew HM, Kwong RW, Pan Y, Milsom WK, Perry SF. Respiratory responses to external ammonia in zebrafish (Danio rerio). Comp Biochem Physiol A Mol Integr Physiol 2021; 251:110822. [DOI: 10.1016/j.cbpa.2020.110822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/10/2020] [Accepted: 10/09/2020] [Indexed: 01/03/2023]
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11
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Disruption of tph1 genes demonstrates the importance of serotonin in regulating ventilation in larval zebrafish (Danio rerio). Respir Physiol Neurobiol 2020; 285:103594. [PMID: 33271304 DOI: 10.1016/j.resp.2020.103594] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/13/2020] [Accepted: 11/23/2020] [Indexed: 01/22/2023]
Abstract
Serotonergic neuroepithelial cells (NECs) in larval zebrafish are believed to be O2 chemoreceptors. Serotonin (5-HT) within these NECs has been implicated as a neurotransmitter mediating the hypoxic ventilatory response (HVR). Here, we use knockout approaches to discern the role of 5-HT in regulating the HVR by targeting the rate limiting enzyme for 5-HT synthesis, tryptophan hydroxylase (Tph). Using transgenic lines, we determined that Tph1a is expressed in skin and pharyngeal arch NECs, as well as in pharyngeal arch Merkel-like cells (MLCs), whereas Tph1b is expressed predominately in MLCs. Knocking out the two tph1 paralogs resulted in similar changes in detectable serotonergic cell density between the two mutants, yet their responses to hypoxia (35 mmHg) were different. Larvae lacking Tph1a (tph1a-/- mutants) displayed a higher ventilation rate when exposed to hypoxia compared to wild-types, whereas tph1b-/- mutants exhibited a lower ventilation rate suggesting that 5-HT located in locations other than NECs, may play a dominant role in regulating the HVR.
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12
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Pan YK, Perry SF. Neuroendocrine control of breathing in fish. Mol Cell Endocrinol 2020; 509:110800. [PMID: 32240728 DOI: 10.1016/j.mce.2020.110800] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/21/2020] [Accepted: 03/23/2020] [Indexed: 10/24/2022]
Abstract
Beginning with the discovery more than 35 years ago that oxygen chemoreceptors of the fish gill are enriched with serotonin, numerous studies have examined the importance of this, and other neuroendocrine factors in piscine chemoreceptor function, and in particular on the chemoreceptor-mediated reflex control of breathing. However, despite these studies, there is continued debate as to the role of neuroendocrine factors in the initiation or modulation of breathing during environmental disturbances or physical activity. In this review, we summarize the state-of-knowledge surrounding the neuroendocrine control of oxygen chemoreception in fish and the associated reflex adjustments to ventilation. We focus on neurohumoral substances that either are present in chemosensory cells or those that are localised elsewhere but have also been implicated in the direct control of breathing. These substances include serotonin, catecholamines (adrenaline and noradrenaline), acetylcholine, purines and gaseous neurotransmitters. Despite the growing indirect evidence for an involvement of these neuroendocrine factors in chemoreception and ventilatory control, direct evidence awaits the incorporation of novel methods currently under development.
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Affiliation(s)
- Yihang Kevin Pan
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada
| | - Steve F Perry
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada.
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13
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Lucu Č. Hypoxia attenuate ionic transport in the isolated gill epithelium of Carcinus maenas. J Comp Physiol B 2020; 190:391-401. [PMID: 32333115 DOI: 10.1007/s00360-020-01277-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/31/2020] [Accepted: 04/08/2020] [Indexed: 12/18/2022]
Abstract
The gills are osmorespiratory organs of aquatic organisms and the prime target of environmentally induced hypoxia. We have studied the impact of severe hypoxia (0.5 mg O2/L) on the ionic transport across posterior gills of Carcinus maenas acclimated to 12 ppt seawater (DSW). The short-circuit current (Isc) across hemilamellae from gills i.e. active ion transport was studied in micro Ussing chambers. Hypoxia induced by deoxygenation of the basolateral side, and not the apical side, resulted in time-dependent inhibition of Isc and full recovery of Isc after reoxygenation. Exposure of the crabs to severe 7 h hypoxia decreased the specific activity of Na+,K+-ATPase in the gills by 36%. Full recovery of enzyme activity occurred in fasted crabs after 3 days of reoxygenation. The intensity of Western blotting bands was not different in the gills of oxygenated, hypoxic and reoxygenated crabs. The reversible, nonspecific blocker of K+ channels Cs and hypoxia inhibited over 90% of Isc which is after reoxygenation fully recovered. The specific blocker of Cl- channels NPPB [5-nitro-2-(3-phenylpropylamino)benzoic acid] blocked Isc by 68.5%. Only the rest of not inhibited Isc in aerated saline was blocked by hypoxia and recovered after reoxygenation. The activity of the antioxidant enzyme catalase was not changed during hypoxia and reoxygenation kept the high enzyme activity in the gills at the level of crabs acclimated to DSW. As a response to hypoxia the presence of 2 mM H2O2 induce an initial slight transient decrease of Isc followed by a rise and after reoxygenation fully recovered Isc. Incubation of hemilamellae with the antioxidant derivative Trolox did not affect the inhibition of Isc by hypoxia.
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Affiliation(s)
- Čedomil Lucu
- Center for Marine Research, Institute Ruđer Bošković, Rovinj, Zagreb, Croatia.
- Alfred Wegener-Institute Helmholtz Centre for Polar and Marine Research, Wadden Sea Station List, Sylt, Germany.
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14
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Abstract
Respiratory chemoreceptors in vertebrates are specialized cells that detect chemical changes in the environment or arterial blood supply and initiate autonomic responses, such as hyperventilation or changes in heart rate, to improve O2 uptake and delivery to tissues. These chemoreceptors are sensitive to changes in O2, CO2 and/or H+. In fish and mammals, respiratory chemoreceptors may be additionally sensitive to ammonia, hypoglycemia, and numerous other stimuli. Thus, chemoreceptors that affect respiration respond to different types of stimuli (or modalities) and are considered to be "polymodal". This review discusses the polymodal nature of respiratory chemoreceptors in vertebrates with a particular emphasis on chemoreceptors of the carotid body and pulmonary epithelium in mammals, and on neuroepithelial cells in water- and air-breathing fish. A major goal will be to examine the evidence for putative polymodal chemoreceptors in fish within the context of studies on mammalian models, for which polymodal chemoreceptors are well described, in order to improve our understanding of the evolution of polymodal chemoreceptors in vertebrates, and to aid in future studies that aim to identify putative receptors in air- and water-breathing fish.
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15
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Gattuso A, Garofalo F, Cerra MC, Imbrogno S. Hypoxia Tolerance in Teleosts: Implications of Cardiac Nitrosative Signals. Front Physiol 2018; 9:366. [PMID: 29706897 PMCID: PMC5906588 DOI: 10.3389/fphys.2018.00366] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/26/2018] [Indexed: 12/18/2022] Open
Abstract
Changes in environmental oxygen (O2) are naturally occurring phenomena which ectotherms have to face on. Many species exhibit a striking capacity to survive and remain active for long periods under hypoxia, even tolerating anoxia. Some fundamental adaptations contribute to this capacity: metabolic suppression, tolerance of pH and ionic unbalance, avoidance and/or repair of free-radical-induced cell injury during reoxygenation. A remarkable feature of these species is their ability to preserve a normal cardiovascular performance during hypoxia/anoxia to match peripheral (tissue pO2) requirements. In this review, we will refer to paradigms of hypoxia- and anoxia-tolerant teleost fish to illustrate cardiac physiological strategies that, by involving nitric oxide and its metabolites, play a critical role in the adaptive responses to O2 limitation. The information here reported may contribute to clarify the molecular and cellular mechanisms underlying heart vulnerability vs. resistance in relation to O2 availability.
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Affiliation(s)
- Alfonsina Gattuso
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy
| | - Filippo Garofalo
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy
| | - Maria C Cerra
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy
| | - Sandra Imbrogno
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy
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