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Gadomski S, Fielding C, García-García A, Korn C, Kapeni C, Ashraf S, Villadiego J, Toro RD, Domingues O, Skepper JN, Michel T, Zimmer J, Sendtner R, Dillon S, Poole KES, Holdsworth G, Sendtner M, Toledo-Aral JJ, De Bari C, McCaskie AW, Robey PG, Méndez-Ferrer S. A cholinergic neuroskeletal interface promotes bone formation during postnatal growth and exercise. Cell Stem Cell 2022; 29:528-544.e9. [PMID: 35276096 PMCID: PMC9033279 DOI: 10.1016/j.stem.2022.02.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 12/02/2021] [Accepted: 02/10/2022] [Indexed: 11/30/2022]
Abstract
The autonomic nervous system is a master regulator of homeostatic processes and stress responses. Sympathetic noradrenergic nerve fibers decrease bone mass, but the role of cholinergic signaling in bone has remained largely unknown. Here, we describe that early postnatally, a subset of sympathetic nerve fibers undergoes an interleukin-6 (IL-6)-induced cholinergic switch upon contacting the bone. A neurotrophic dependency mediated through GDNF-family receptor-α2 (GFRα2) and its ligand, neurturin (NRTN), is established between sympathetic cholinergic fibers and bone-embedded osteocytes, which require cholinergic innervation for their survival and connectivity. Bone-lining osteoprogenitors amplify and propagate cholinergic signals in the bone marrow (BM). Moderate exercise augments trabecular bone partly through an IL-6-dependent expansion of sympathetic cholinergic nerve fibers. Consequently, loss of cholinergic skeletal innervation reduces osteocyte survival and function, causing osteopenia and impaired skeletal adaptation to moderate exercise. These results uncover a cholinergic neuro-osteocyte interface that regulates skeletogenesis and skeletal turnover through bone-anabolic effects.
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Affiliation(s)
- Stephen Gadomski
- Wellcome-MRC Cambridge Stem Cell Institute, Cambridge CB2 0AW, UK; Department of Hematology, University of Cambridge, Cambridge CB2 0AW, UK; National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge CB2 0AW, UK; Skeletal Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA; NIH Oxford-Cambridge Scholars Program in Partnership with Medical University of South Carolina, Charleston, SC 29425, USA
| | - Claire Fielding
- Wellcome-MRC Cambridge Stem Cell Institute, Cambridge CB2 0AW, UK; Department of Hematology, University of Cambridge, Cambridge CB2 0AW, UK; National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge CB2 0AW, UK
| | - Andrés García-García
- Wellcome-MRC Cambridge Stem Cell Institute, Cambridge CB2 0AW, UK; Department of Hematology, University of Cambridge, Cambridge CB2 0AW, UK; National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge CB2 0AW, UK
| | - Claudia Korn
- Wellcome-MRC Cambridge Stem Cell Institute, Cambridge CB2 0AW, UK; Department of Hematology, University of Cambridge, Cambridge CB2 0AW, UK; National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge CB2 0AW, UK
| | - Chrysa Kapeni
- Wellcome-MRC Cambridge Stem Cell Institute, Cambridge CB2 0AW, UK; Department of Hematology, University of Cambridge, Cambridge CB2 0AW, UK; National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge CB2 0AW, UK
| | - Sadaf Ashraf
- Arthritis and Regenerative Medicine Laboratory, Aberdeen Centre for Arthritis and Musculoskeletal Health, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Javier Villadiego
- Instituto de Biomedicina de Sevilla-IBiS (Hospitales Universitarios Virgen del Rocío y Macarena/CSIC/Universidad de Sevilla), 41013 Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, 41009 Seville, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, (CIBERNED), Madrid 28029, Spain
| | - Raquel Del Toro
- Instituto de Biomedicina de Sevilla-IBiS (Hospitales Universitarios Virgen del Rocío y Macarena/CSIC/Universidad de Sevilla), 41013 Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, 41009 Seville, Spain
| | - Olivia Domingues
- Department of Infection and Immunity, Luxembourg Institute of Health, 4354 Esch-sur Alzette, Luxembourg
| | - Jeremy N Skepper
- Department of Physiology, Development, and Neuroscience, Cambridge Advanced Imaging Centre, University of Cambridge, Cambridge CB2 3DY, UK
| | - Tatiana Michel
- Department of Infection and Immunity, Luxembourg Institute of Health, 4354 Esch-sur Alzette, Luxembourg
| | - Jacques Zimmer
- Department of Infection and Immunity, Luxembourg Institute of Health, 4354 Esch-sur Alzette, Luxembourg
| | - Regine Sendtner
- Institute of Clinical Neurobiology, University Hospital of Wuerzburg, 97080 Wuerzburg, Germany
| | - Scott Dillon
- Wellcome-MRC Cambridge Stem Cell Institute, Cambridge CB2 0AW, UK
| | - Kenneth E S Poole
- Cambridge NIHR Biomedical Research Centre, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | | | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital of Wuerzburg, 97080 Wuerzburg, Germany
| | - Juan J Toledo-Aral
- Instituto de Biomedicina de Sevilla-IBiS (Hospitales Universitarios Virgen del Rocío y Macarena/CSIC/Universidad de Sevilla), 41013 Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, 41009 Seville, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, (CIBERNED), Madrid 28029, Spain
| | - Cosimo De Bari
- Arthritis and Regenerative Medicine Laboratory, Aberdeen Centre for Arthritis and Musculoskeletal Health, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Andrew W McCaskie
- Wellcome-MRC Cambridge Stem Cell Institute, Cambridge CB2 0AW, UK; Department of Surgery, School of Clinical Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Pamela G Robey
- Skeletal Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
| | - Simón Méndez-Ferrer
- Wellcome-MRC Cambridge Stem Cell Institute, Cambridge CB2 0AW, UK; Department of Hematology, University of Cambridge, Cambridge CB2 0AW, UK; National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge CB2 0AW, UK; Instituto de Biomedicina de Sevilla-IBiS (Hospitales Universitarios Virgen del Rocío y Macarena/CSIC/Universidad de Sevilla), 41013 Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, 41009 Seville, Spain.
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2
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Kalla M, Hao G, Tapoulal N, Tomek J, Liu K, Woodward L, Dall’Armellina E, Banning AP, Choudhury RP, Neubauer S, Kharbanda RK, Channon KM, Ajijola OA, Shivkumar K, Paterson DJ, Herring N. The cardiac sympathetic co-transmitter neuropeptide Y is pro-arrhythmic following ST-elevation myocardial infarction despite beta-blockade. Eur Heart J 2020; 41:2168-2179. [PMID: 31834357 PMCID: PMC7299634 DOI: 10.1093/eurheartj/ehz852] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/29/2019] [Accepted: 11/12/2019] [Indexed: 01/29/2023] Open
Abstract
AIMS ST-elevation myocardial infarction is associated with high levels of cardiac sympathetic drive and release of the co-transmitter neuropeptide Y (NPY). We hypothesized that despite beta-blockade, NPY promotes arrhythmogenesis via ventricular myocyte receptors. METHODS AND RESULTS In 78 patients treated with primary percutaneous coronary intervention, sustained ventricular tachycardia (VT) or fibrillation (VF) occurred in 6 (7.7%) within 48 h. These patients had significantly (P < 0.05) higher venous NPY levels despite the absence of classical risk factors including late presentation, larger infarct size, and beta-blocker usage. Receiver operating curve identified an NPY threshold of 27.3 pg/mL with a sensitivity of 0.83 and a specificity of 0.71. RT-qPCR demonstrated the presence of NPY mRNA in both human and rat stellate ganglia. In the isolated Langendorff perfused rat heart, prolonged (10 Hz, 2 min) stimulation of the stellate ganglia caused significant NPY release. Despite maximal beta-blockade with metoprolol (10 μmol/L), optical mapping of ventricular voltage and calcium (using RH237 and Rhod2) demonstrated an increase in magnitude and shortening in duration of the calcium transient and a significant lowering of ventricular fibrillation threshold. These effects were prevented by the Y1 receptor antagonist BIBO3304 (1 μmol/L). Neuropeptide Y (250 nmol/L) significantly increased the incidence of VT/VF (60% vs. 10%) during experimental ST-elevation ischaemia and reperfusion compared to control, and this could also be prevented by BIBO3304. CONCLUSIONS The co-transmitter NPY is released during sympathetic stimulation and acts as a novel arrhythmic trigger. Drugs inhibiting the Y1 receptor work synergistically with beta-blockade as a new anti-arrhythmic therapy.
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Affiliation(s)
- Manish Kalla
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Parks Road, Oxford OX13PT, UK
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Guoliang Hao
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Parks Road, Oxford OX13PT, UK
| | - Nidi Tapoulal
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Parks Road, Oxford OX13PT, UK
| | - Jakub Tomek
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Parks Road, Oxford OX13PT, UK
| | - Kun Liu
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Parks Road, Oxford OX13PT, UK
| | - Lavinia Woodward
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Parks Road, Oxford OX13PT, UK
| | | | - Erica Dall’Armellina
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Adrian P Banning
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Robin P Choudhury
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Radcliffe Department of Medicine, Acute Vascular Imaging Centre, University of Oxford, Oxford OX3 9DU, UK
| | - Stefan Neubauer
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Rajesh K Kharbanda
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Keith M Channon
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Olujimi A Ajijola
- UCLA Cardiac Arrhythmia Center and Neurocardiology Research Center, Los Angeles, CA, USA
| | - Kalyanam Shivkumar
- UCLA Cardiac Arrhythmia Center and Neurocardiology Research Center, Los Angeles, CA, USA
| | - David J Paterson
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Parks Road, Oxford OX13PT, UK
| | - Neil Herring
- Department of Physiology, Anatomy and Genetics, Burdon Sanderson Cardiac Science Centre, University of Oxford, Parks Road, Oxford OX13PT, UK
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
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3
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Accentuated antagonism of vagal heart rate control and less potent prejunctional inhibition of vagal acetylcholine release during sympathetic nerve stimulation in the rat. Auton Neurosci 2019; 218:25-30. [PMID: 30890345 DOI: 10.1016/j.autneu.2019.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/30/2019] [Accepted: 02/17/2019] [Indexed: 12/27/2022]
Abstract
Complex interactions are known to occur between the sympathetic and parasympathetic controls of the heart. Although sympathetic nerve stimulation (SNS) usually augments the heart rate (HR) response to vagal nerve stimulation (VNS), exogenously administered norepinephrine (NE) can attenuate the HR response as well as the myocardial interstitial acetylcholine (ACh) release during VNS. To provide a basis for an integrative knowledge about the opposing adrenergic effects on the vagal control of the heart, we examined whether SNS significantly attenuates VNS-induced myocardial interstitial ACh release in the in vivo beating heart. In nine anesthetized rats, changes in HR and myocardial interstitial ACh release in response to 5- and 20-Hz VNS were examined in both the absence and presence of a 5-Hz background SNS. The SNS significantly enhanced the VNS-induced HR reduction during 20-Hz VNS (-101.2 ± 33.1 vs. -163.0 ± 34.9 beats/min, P < 0.001, a 60% augmentation). By contrast, the SNS significantly attenuated the ACh release during 20-Hz VNS (4.30 ± 0.72 vs. 3.80 ± 0.75 nM, P < 0.01, a 12% attenuation). In conclusion, SNS exerted only a moderate inhibitory effect on the VNS-induced myocardial interstitial ACh release in the in vivo beating heart.
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Lang R, Gundlach AL, Holmes FE, Hobson SA, Wynick D, Hökfelt T, Kofler B. Physiology, signaling, and pharmacology of galanin peptides and receptors: three decades of emerging diversity. Pharmacol Rev 2015; 67:118-75. [PMID: 25428932 DOI: 10.1124/pr.112.006536] [Citation(s) in RCA: 218] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Galanin was first identified 30 years ago as a "classic neuropeptide," with actions primarily as a modulator of neurotransmission in the brain and peripheral nervous system. Other structurally-related peptides-galanin-like peptide and alarin-with diverse biologic actions in brain and other tissues have since been identified, although, unlike galanin, their cognate receptors are currently unknown. Over the last two decades, in addition to many neuronal actions, a number of nonneuronal actions of galanin and other galanin family peptides have been described. These include actions associated with neural stem cells, nonneuronal cells in the brain such as glia, endocrine functions, effects on metabolism, energy homeostasis, and paracrine effects in bone. Substantial new data also indicate an emerging role for galanin in innate immunity, inflammation, and cancer. Galanin has been shown to regulate its numerous physiologic and pathophysiological processes through interactions with three G protein-coupled receptors, GAL1, GAL2, and GAL3, and signaling via multiple transduction pathways, including inhibition of cAMP/PKA (GAL1, GAL3) and stimulation of phospholipase C (GAL2). In this review, we emphasize the importance of novel galanin receptor-specific agonists and antagonists. Also, other approaches, including new transgenic mouse lines (such as a recently characterized GAL3 knockout mouse) represent, in combination with viral-based techniques, critical tools required to better evaluate galanin system physiology. These in turn will help identify potential targets of the galanin/galanin-receptor systems in a diverse range of human diseases, including pain, mood disorders, epilepsy, neurodegenerative conditions, diabetes, and cancer.
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Affiliation(s)
- Roland Lang
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Andrew L Gundlach
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Fiona E Holmes
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Sally A Hobson
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - David Wynick
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Tomas Hökfelt
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Barbara Kofler
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
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Abstract
Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targets, upon which target-derived trophic factors take over final maturation, synaptic strength and postnatal survival. Although target-derived neurotrophins have a central role to play in development, alternative sources of neurotrophins may also modulate innervation. Both developing and adult sympathetic neurons express proNGF, and adult parasympathetic cardiac ganglion neurons also synthesize and release NGF. The physiological function of these “non-classical” cardiac sources of neurotrophins remains to be determined, especially in relation to autocrine/paracrine sustenance during development.
Cardiac autonomic nerves are closely spatially associated in cardiac plexuses, ganglia and pacemaker regions and so are sensitive to release of neurotransmitter, neuropeptides and trophic factors from adjacent nerves. As such, in many cardiac pathologies, it is an imbalance within the two arms of the autonomic system that is critical for disease progression. Although this crosstalk between sympathetic and parasympathetic nerves has been well established for adult nerves, it is unclear whether a degree of paracrine regulation occurs across the autonomic limbs during development. Aberrant nerve remodeling is a common occurrence in many adult cardiovascular pathologies, and the mechanisms regulating outgrowth or denervation are disparate. However, autonomic neurons display considerable plasticity in this regard with neurotrophins and inflammatory cytokines having a central regulatory function, including in possible neurotransmitter changes. Certainly, neurotrophins and cytokines regulate transcriptional factors in adult autonomic neurons that have vital differentiation roles in development. Particularly for parasympathetic cardiac ganglion neurons, additional examinations of developmental regulatory mechanisms will potentially aid in understanding attenuated parasympathetic function in a number of conditions, including heart failure.
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Affiliation(s)
- Wohaib Hasan
- Knight Cardiovascular Institute; Oregon Health & Science University; Portland, OR USA
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6
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Oliveira R, Vitor da Costa M, Pedro R, Polito M, Avelar A, Cyrino E, Nakamura F. Acute cardiac autonomic responses after a bout of resistance exercise. Sci Sports 2012. [DOI: 10.1016/j.scispo.2011.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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7
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The cardiac sympathetic co-transmitter galanin reduces acetylcholine release and vagal bradycardia: implications for neural control of cardiac excitability. J Mol Cell Cardiol 2011; 52:667-76. [PMID: 22172449 PMCID: PMC3314977 DOI: 10.1016/j.yjmcc.2011.11.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 11/06/2011] [Accepted: 11/28/2011] [Indexed: 02/06/2023]
Abstract
The autonomic phenotype of congestive cardiac failure is characterised by high sympathetic drive and impaired vagal tone, which are independent predictors of mortality. We hypothesize that impaired bradycardia to peripheral vagal stimulation following high-level sympathetic drive is due to sympatho-vagal crosstalk by the adrenergic co-transmitters galanin and neuropeptide-Y (NPY). Moreover we hypothesize that galanin acts similarly to NPY by reducing vagal acetylcholine release via a receptor mediated, protein kinase-dependent pathway. Prolonged right stellate ganglion stimulation (10 Hz, 2 min, in the presence of 10 μM metoprolol) in an isolated guinea pig atrial preparation with dual autonomic innervation leads to a significant (p < 0.05) reduction in the magnitude of vagal bradycardia (5 Hz) maintained over the subsequent 20 min (n = 6). Immunohistochemistry demonstrated the presence of galanin in a small number of tyrosine hydroxylase positive neurons from freshly dissected stellate ganglion tissue sections. Following 3 days of tissue culture however, most stellate neurons expressed galanin. Stellate stimulation caused the release of low levels of galanin and significantly higher levels of NPY into the surrounding perfusate (n = 6, using ELISA). The reduction in vagal bradycardia post sympathetic stimulation was partially reversed by the galanin receptor antagonist M40 after 10 min (1 μM, n = 5), and completely reversed with the NPY Y2 receptor antagonist BIIE 0246 at all time points (1 μM, n = 6). Exogenous galanin (n = 6, 50–500 nM) also reduced the heart rate response to vagal stimulation but had no effect on the response to carbamylcholine that produced similar degrees of bradycardia (n = 6). Galanin (500 nM) also significantly attenuated the release of 3H-acetylcholine from isolated atria during field stimulation (5 Hz, n = 5). The effect of galanin on vagal bradycardia could be abolished by the galanin receptor antagonist M40 (n = 5). Importantly the GalR1 receptor was immunofluorescently co-localised with choline acetyl-transferase containing neurons at the sinoatrial node. The protein kinase C inhibitor calphostin (100 nM, n = 6) abolished the effect of galanin on vagal bradycardia whilst the protein kinase A inhibitor H89 (500 nM, n = 6) had no effect. These results demonstrate that prolonged sympathetic activation releases the slowly diffusing adrenergic co-transmitter galanin in addition to NPY, and that this contributes to the attenuation in vagal bradycardia via a reduction in acetylcholine release. This effect is mediated by GalR1 receptors on vagal neurons coupled to protein kinase C dependent signalling pathways. The role of galanin may become more important following an acute injury response where galanin expression is increased.
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Florencio Gama E, Maria Santarém J, Aparecido Liberti E, Jacob Filho W, de Souza RR. Exercise changes the size of cardiac neurons and protects them from age-related neurodegeneration. Ann Anat 2010; 192:52-7. [DOI: 10.1016/j.aanat.2009.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 08/12/2009] [Accepted: 09/08/2009] [Indexed: 11/29/2022]
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Floras JS. Sympathetic nervous system activation in human heart failure: clinical implications of an updated model. J Am Coll Cardiol 2009; 54:375-85. [PMID: 19628111 DOI: 10.1016/j.jacc.2009.03.061] [Citation(s) in RCA: 379] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Revised: 03/16/2009] [Accepted: 03/23/2009] [Indexed: 11/28/2022]
Abstract
Disturbances in cardiovascular neural regulation, influencing both disease course and survival, progress as heart failure worsens. Heart failure due to left ventricular systolic dysfunction has long been considered a state of generalized sympathetic activation, itself a reflex response to alterations in cardiac and peripheral hemodynamics that is initially appropriate, but ultimately pathological. Because arterial baroreceptor reflex vagal control of heart rate is impaired early in heart failure, a parallel reduction in its reflex buffering of sympathetic outflow has been assumed. However, it is now recognized that: 1) the time course and magnitude of sympathetic activation are target organ-specific, not generalized, and independent of ventricular systolic function; and 2) human heart failure is characterized by rapidly responsive arterial baroreflex regulation of muscle sympathetic nerve activity (MSNA), attenuated cardiopulmonary reflex modulation of MSNA, a cardiac sympathoexcitatory reflex related to increased cardiopulmonary filling pressure, and by individual variation in nonbaroreflex-mediated sympathoexcitatory mechanisms, including coexisting sleep apnea, myocardial ischemia, obesity, and reflexes from exercising muscle. Thus, sympathetic activation in the setting of impaired systolic function reflects the net balance and interaction between appropriate reflex compensatory responses to impaired systolic function and excitatory stimuli that elicit adrenergic responses in excess of homeostatic requirements. Recent observations have been incorporated into an updated model of cardiovascular neural regulation in chronic heart failure due to ventricular systolic dysfunction, with implications for the clinical evaluation of patients, application of current treatment, and development of new therapies.
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Affiliation(s)
- John S Floras
- Mount Sinai Hospital and University Health Network Division of Cardiology, and the University of Toronto, Toronto, Ontario, Canada.
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10
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Ewert TJ, Gritman KR, Bader M, Habecker BA. Post-infarct cardiac sympathetic hyperactivity regulates galanin expression. Neurosci Lett 2008; 436:163-6. [PMID: 18384957 DOI: 10.1016/j.neulet.2008.03.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2007] [Revised: 03/05/2008] [Accepted: 03/06/2008] [Indexed: 11/17/2022]
Abstract
The neuropeptide galanin is elevated in the cardiac sympathetic innervation after myocardial infarction (MI). Galanin inhibits vagal transmission and may support the regeneration of sympathetic nerves, thereby contributing to the development of arrhythmia and sudden cardiac death after MI. The reason for increased galanin production in sympathetic neurons after myocardial infarction is not known. Cardiac sympathetic neurons are activated chronically after cardiac ischemia-reperfusion, and activation of sympathetic neurons in culture stimulates galanin expression. Therefore, we tested the hypothesis that increased sympathetic nerve activity stimulates galanin expression in cardiac sympathetic neurons after myocardial infarction. To test this hypothesis we used TGR(ASrAOGEN) transgenic rats, which lack brain angiotensinogen and do not exhibit post-infarct sympathetic hyperactivity. Hearts and stellate ganglia were collected 1 week after ischemia-reperfusion. Galanin mRNA was quantified by real-time PCR and peptide content was assayed by enzyme-linked immunosorbent assay. Galanin mRNA increased approximately 3-fold after MI in cardiac sympathetic neurons of both genotypes compared to unoperated and sham controls. Left ventricular galanin content, however, increased after MI only in Sprague-Dawley rats and not in AOGEN rats. These data suggest that post-infarct cardiac sympathetic hyperactivity stimulates galanin peptide production but is not required for increased galanin mRNA expression.
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Protas L, Robinson RB. Dissecting the NPY signaling cascade between cardiac sympathetic and parasympathetic nerves. J Mol Cell Cardiol 2008; 44:470-2. [PMID: 18272171 DOI: 10.1016/j.yjmcc.2008.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Accepted: 01/02/2008] [Indexed: 01/08/2023]
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12
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Herring N, Lokale MN, Danson EJ, Heaton DA, Paterson DJ. Neuropeptide Y reduces acetylcholine release and vagal bradycardia via a Y2 receptor-mediated, protein kinase C-dependent pathway. J Mol Cell Cardiol 2007; 44:477-85. [PMID: 17996892 DOI: 10.1016/j.yjmcc.2007.10.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 09/30/2007] [Accepted: 10/01/2007] [Indexed: 12/16/2022]
Abstract
The co-transmitter neuropeptide Y (NPY), released during prolonged cardiac sympathetic nerve stimulation, can attenuate vagal-induced bradycardia. We tested the hypothesis that NPY reduces acetylcholine release, at similar concentrations to which it attenuates vagal bradycardia, via pre-synaptic Y2 receptors modulating a pathway that is dependent on protein kinase A (PKA) or protein kinase C (PKC). The Y2 receptor was immunofluorescently colocalized with choline acetyl-transferase containing neurons at the guinea pig sinoatrial node. The effect of NPY in the presence of various enzyme inhibitors was then tested on the heart rate response to vagal nerve stimulation in isolated guinea pig sinoatrial node/right vagal nerve preparations and also on (3)H-acetylcholine release from right atria during field stimulation. NPY reduced the heart rate response to vagal stimulation at 1, 3 and 5 Hz (significant at 100 nM and reaching a plateau at 250 nM NPY, p<0.05, n=6) but not to the stable analogue of acetylcholine, carbamylcholine (30, 60 or 90 nM, n=6) which produced similar degrees of bradycardia. The reduced vagal response was abolished by the Y2 receptor antagonist BIIE 0246 (1 microM, n=4). NPY also significantly attenuated the release of (3)H-acetylcholine during field stimulation (250 nM, n=6). The effect of NPY (250 nM) on vagal bradycardia was abolished by the PKC inhibitors calphostin C (0.1 microM, n=5) and chelerythrine chloride (25 microM, n=6) but not the PKA inhibitor H89 (0.5 microM, n=6). Conversely, the PKC activator Phorbol-12-myristate-13-acetate (0.5 microM, n=7) mimicked the effect of NPY and significantly reduced (3)H-acetylcholine release during field stimulation. These results show that NPY attenuates vagal bradycardia via a pre-synaptic decrease in acetylcholine release that appears to be mediated by a Y2 receptor pathway involving modulation of PKC.
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Affiliation(s)
- Neil Herring
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford University OX1 3PT, UK
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13
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Grossman P, Taylor EW. Toward understanding respiratory sinus arrhythmia: relations to cardiac vagal tone, evolution and biobehavioral functions. Biol Psychol 2006; 74:263-85. [PMID: 17081672 DOI: 10.1016/j.biopsycho.2005.11.014] [Citation(s) in RCA: 670] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2005] [Indexed: 11/16/2022]
Abstract
Respiratory sinus arrhythmia (RSA, or high-frequency heart-rate variability) is frequently employed as an index of cardiac vagal tone or even believed to be a direct measure of vagal tone. However, there are many significant caveats regarding vagal tone interpretation: 1. Respiratory parameters can confound relations between RSA and cardiac vagal tone.2. Although intraindividual relations between RSA and cardiac vagal control are often strong, interindividual associations may be modest.3. RSA measurement is profoundly influenced by concurrent levels of momentary physical activity, which can bias estimation of individual differences in vagal tone.4. RSA magnitude is affected by beta-adrenergic tone.5. RSA and cardiac vagal tone can dissociate under certain circumstances.6. The polyvagal theory contains evolution-based speculations that relate RSA, vagal tone and behavioral phenomena. We present evidence that the polyvagal theory does not accurately depict evolution of vagal control of heart-rate variability, and that it ignores the phenomenon of cardiac aliasing and disregards the evolution of a functional role for vagal control of the heart, from cardiorespiratory synchrony in fish to RSA in mammals. Unawareness of these issues can lead to misinterpretation of cardiovascular autonomic mechanisms. On the other hand, RSA has been shown to often provide a reasonable reflection of cardiac vagal tone when the above-mentioned complexities are considered. Finally, a recent hypothesis is expanded upon, in which RSA plays a primary role in regulation of energy exchange by means of synchronizing respiratory and cardiovascular processes during metabolic and behavioral change.
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Affiliation(s)
- Paul Grossman
- Department of Psychosomatic and Internal Medicine, Psychophysiology Research Laboratory, University of Basel Hospital, Hebelstrasse 2, CH-4031 Basel, Switzerland.
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Waldmann M, Thompson GW, Kember GC, Ardell JL, Armour JA. Stochastic behavior of atrial and ventricular intrinsic cardiac neurons. J Appl Physiol (1985) 2006; 101:413-9. [PMID: 16645188 DOI: 10.1152/japplphysiol.01346.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To quantify the concurrent transduction capabilities of spatially distributed intrinsic cardiac neurons, the activities generated by atrial vs. ventricular intrinsic cardiac neurons were recorded simultaneously in 12 anesthetized dogs at baseline and during alterations in the cardiac milieu. Few (3%) identified atrial and ventricular neurons (2 of 72 characterized neurons) responded solely to regional mechanical deformation, doing so in a tightly coupled fashion (cross-correlation coefficient r = 0.63). The remaining (97%) atrial and ventricular neurons transduced multimodal stimuli to display stochastic behavior. Specifically, ventricular chemosensory inputs modified these populations such that they generated no short-term coherence among their activities (cross-correlation coefficient r = 0.21 +/- 0.07). Regional ventricular ischemia activated most atrial and ventricular neurons in a noncoupled fashion. Nicotinic activation of atrial neurons enhanced ventricular neuronal activity. Acute decentralization of the intrinsic cardiac nervous system obtunded its neuron responsiveness to cardiac sensory stimuli. Most atrial and ventricular intrinsic cardiac neurons generate concurrent stochastic activity that is predicated primarily upon their cardiac chemotransduction. As a consequence, they display relative independent short-term (beat-to-beat) control over regional cardiac indexes. Over longer time scales, their functional interdependence is manifest as the result of interganglionic interconnections and descending inputs.
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Affiliation(s)
- M Waldmann
- Department of Cardiology, Technical University RWTH, Aachen, Germany
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15
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Ilebekk A, Björkman JA, Nordlander M. Influence of endogenous neuropeptide Y (NPY) on the sympathetic-parasympathetic interaction in the canine heart. J Cardiovasc Pharmacol 2006; 46:474-80. [PMID: 16160600 DOI: 10.1097/01.fjc.0000177986.21929.d8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The purpose of this study was to examine the sympathetic-parasympathetic interactions on heart rate through release of neuropeptide Y (NPY) and its action on prejunctional NPY Y2 receptors on vagal and sympathetic nerve fibers. In other studies on various preparations and in various organs, attenuation of transmitter release has in fact been demonstrated through activation of the NPY Y2 receptor. In the present study on anesthetized dogs we examine, however, for the first time if vagal bradycardia is attenuated by endogenous NPY released during intense cardiac sympathetic stimulation. In addition, we explore if sympathetic transmitter release and heart rate, during moderate sympathetic stimulation, are affected through this receptor system. The significance of the NPY Y2 receptor was revealed by performing experiments before and after administration of its specific receptor antagonist BIIE0246. We found that attenuation of the bradycardia during vagal nerve stimulation was dose-dependently counteracted by BIIE0246 and that the tachycardia elicited by sympathetic stimulation remained unaffected after NPY Y2 receptor blockade. Thus, endogenous NPY appears to attenuate vagal bradycardia by stimulating prejunctional NPY Y2 receptors on cardiac vagal nerve terminals and, less efficiently, to attenuate transmitter release and tachycardia through a feedback loop on the cardiac sympathetic nerve fibers.
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Affiliation(s)
- Arnfinn Ilebekk
- Institute for Experimental Medical Research, Ullevål University Hospital, 0407 Oslo, Norway.
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16
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Potter EK, Smith-White MA. Galanin modulates cholinergic neurotransmission in the heart. Neuropeptides 2005; 39:345-8. [PMID: 15944033 DOI: 10.1016/j.npep.2004.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2004] [Accepted: 12/02/2004] [Indexed: 11/22/2022]
Abstract
The role of galanin (Gal) in the modulation of cholinergic neurotransmission in the heart in wild-type (129 SvJ), and GALR1 knockout mice has been studied. The mice were anaesthetised and ventilated. Blood pressure (BP) and the increase in pulse interval evoked by stimulation of the vagus nerve (deltaPI) were recorded. Resting BP and PI were not different in control and GALR1-KO mice. In control mice an intravenous, bolus injection of Gal (0.8-13 nmol/kg; n = 4-6) attenuated the deltaPI, dose dependently from 33 +/- 7% to 78 +/- 9.5%. In GALR1-KO mice, Gal (0.8-13 nmol/kg) did not attenuate deltaPI at any dose (n = 3-4). In control mice intravenous, bolus injection of neuropeptide Y (NPY; 0.5-10 nmol/kg, n = 5-7) attenuated the deltaPI by 13 +/- 10% to 67 +/- 7% with a half time to recovery of 0.5-5 +/- 1 min. In control mice, following activation of the cardiac sympathetic nerve (10 Hz for 2 min; n = 3) the deltaPI was attenuated by 92 +/- 2% with a half time to recovery of 7 +/- 1 min. In control mice in the presence of the beta-adrenoceptor antagonist propranolol (1 mg/kg), and 1 micromol/kg BIIE0426 (an NPY Y2 receptor antagonist) the deltaPI was 57+/-3% with a half time to recovery of 2.5+/-0.5 min. In GALR1-KO mice, in the presence of propranolol and BIIE0426 there was no inhibition of deltaPI. In mice, it is proposed that both Gal and NPY contribute to the prolonged attenuation of parasympathetic slowing of the heart following activation of the cardiac sympathetic nerve.
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Affiliation(s)
- Erica K Potter
- Prince of Wales Medical Research Institute, Barker Street, Randwick, 2031 Sydney, Australia.
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17
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Schwertfeger E, Klein T, Vonend O, Oberhauser V, Stegbauer J, Rump LC. Neuropeptide Y inhibits acetylcholine release in human heart atrium by activation of Y2-receptors. Naunyn Schmiedebergs Arch Pharmacol 2004; 369:455-61. [PMID: 15103451 DOI: 10.1007/s00210-004-0930-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2004] [Accepted: 03/25/2004] [Indexed: 11/30/2022]
Abstract
Congestive heart failure and other cardiac diseases are characterized by increased activity of the sympathetic nervous system, whereas at the same time parasympathetic activity is often suppressed. Such imbalance may be a result of or at least enhanced by presynaptic inhibitory effects of sympathetic neurotransmitters on acetylcholine release. We investigated whether the sympathetic cotransmitters neuropeptide Y (NPY), norepinephrine (NE), and ATP are capable of modulating acetylcholine release in human heart atrium. Human atrial appendages were incubated with [(3)H]-choline to label cholinergic transmitter stores and placed in superfusion chambers. Electrical field stimulations (S1, S2) induced a tetrodotoxin-dependent [(3)H]-release, which was taken as an index of endogenous acetylcholine release. NE, NPY, ATP, and a P2-receptor analogue were added before S2. NPY (0.05-1.0 micromol/l) concentration dependently inhibited acetylcholine release. This effect was prevented by the NPY-Y(2)-receptor antagonist BIIE 0246 (0.1 micromol/l) but not by the NPY-Y(1)-receptor antagonist BIBP 3226 (10 micromol/l). ATP (10 micromol/l), a stable analogue ADP-beta S (3 micromol/l), and NE (1 micromol/l) had no effect on acetylcholine release. m-RNA for the NPY-receptor subtypes Y(1), Y(2), Y(4), Y(5), and y(6) was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR). The results suggest that the sympathetic neurotransmitter NPY inhibits parasympathetic neurotransmission in the human heart through activation of presynaptic Y(2)-receptors. NE and ATP seem not to play a role. Since NPY plasma levels are high in chronic heart failure patients, NPY may be one component leading to impaired parasympathetic neurotransmission in those patients.
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Affiliation(s)
- Eckhard Schwertfeger
- Department of Internal Medicine IV, University Hospital Freiburg, Freiburg, Germany
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18
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Smith-White MA, Iismaa TP, Potter EK. Galanin and neuropeptide Y reduce cholinergic transmission in the heart of the anaesthetised mouse. Br J Pharmacol 2003; 140:170-8. [PMID: 12967946 PMCID: PMC1574002 DOI: 10.1038/sj.bjp.0705404] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
(1) This study investigated the effects of galanin (GAL) on inhibition of cholinergic (vagal) activity in the mouse heart using control galanin knockout (GAL-KO) and GAL-1R receptor knockout (GAL-1R-KO) mice. (2) In pentobarbitone anaesthetised mice, supramaximal stimulation every 30 s of the vagus nerve innervating the heart, increased pulse interval (PI) by approximately 50 ms or decreased heart rate by approximately 100 beats min-1. This response was attenuated by intravenous administration of GAL (dose ranged from 0.8 to 13 nmol kg-1) in a dose-dependent manner. (3) In GAL-KO mice, the magnitude of inhibition of the increase in PI (DeltaPI) following a bolus dose of GAL was not different from the DeltaPI in control mice, and neuropeptide Y (NPY), previously shown to attenuate vagal inhibitory activity in mice, evoked a comparative inhibition of DeltaPI in GAL-KO mice. (4) In GAL-1R-KO mice, an intravenous, bolus injection of GAL had no inhibitory effect on vagal activity. (5) In control mice, stimulation of the sympathetic nerve at 25 V, 10 Hz for 2 min in the presence of propranolol evoked a long-lasting attenuation of DeltaPI. The inhibitory effect on DeltaPI was reduced in the presence of the NPY Y2 antagonist, BIIE0246. (6) In GAL-1R-KO mice, stimulation of the sympathetic nerve in the presence of propranolol evoked an attenuation of DeltaPI not significantly different from the response in control mice in the presence of BIIE0246. Following administration of BIIE0246 in GAL-1R-KO mice, the inhibition of DeltaPI that followed stimulation of the sympathetic nerve was abolished. (7) These findings support the view that the nerve terminals of parasympathetic neurons in the mouse heart possess both GAL-1R and NPY Y2 receptors which, when activated, reduce acetylcholine release.
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Affiliation(s)
- Margaret A Smith-White
- Prince of Wales Medical Research Institute, Prince of Wales Hospital, Barker St., Randwick 2031, Sydney, Australia
| | - Tiina P Iismaa
- Garvan Institute of Medical Research, St Vincents Hospital, Darlinghurst, Sydney, Australia
| | - Erica K Potter
- Prince of Wales Medical Research Institute, Prince of Wales Hospital, Barker St., Randwick 2031, Sydney, Australia
- Author for correspondence:
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Gori T, Floras JS, Parker JD. Effects of nitroglycerin treatment on baroreflex sensitivity and short-term heart rate variability in humans. J Am Coll Cardiol 2002; 40:2000-5. [PMID: 12475461 DOI: 10.1016/s0735-1097(02)02532-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES We set out to determine the effect of sustained treatment with nitroglycerin (GTN) on neural modulation of heart rate in humans. BACKGROUND Acutely, exogenous and endogenous nitric oxide reduces sympathetic, while increasing vagal, outflow. An animal study showed loss of these effects during nitrate tolerance. METHODS A total of 29 healthy men (age range, 18 to 32 years) received transdermal GTN (0.6 mg/h/24 h) or no therapy for six days in a parallel controlled trial. The reflex regulation of heart rate was assessed with the spontaneous baroreflex sensitivity (BRS) method. Heart rate variability was calculated both in time (standard deviation of mean RR interval [RRSD]) and frequency domains (Fast Fourier Transformation) over 10-min intervals. RESULTS Systolic blood pressure was unchanged after continuous GTN, whereas mean RR interval decreased significantly (from 839 to 781 ms, p < 0.05). Nitroglycerin blunted BRS (p < 0.05). When compared with untreated subjects, RRSD was significantly lower after GTN, whereas the ratio of low to high frequencies was increased (all p < 0.05). CONCLUSIONS Chronic GTN reduces tonic and reflex vagal heart rate modulation, resulting in greater relative sympathetic influence. Importantly, such changes in the regulation of chronotropic oscillations might have negative prognostic implications in both heart failure and coronary artery disease. Furthermore, because chronic GTN alters the blood pressure/heart rate relationship, our data suggest caution when using these variables as pharmacodynamic markers for the development of nitrate tolerance.
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Affiliation(s)
- Tommaso Gori
- Division of Cardiology, Department of Medicine, Mount Sinai Hospital, and the University Health Network Hospitals, Toronto, Canada
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Herbert RWL, Bolter CP. Respiratory sinus arrhythmia and the heart rate response to carotid baroreceptor activation after hard dynamic exercise in humans. Auton Neurosci 2002; 100:84-9. [PMID: 12422964 DOI: 10.1016/s1566-0702(02)00149-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aim of this study was to examine the influence of 20 min of hard exercise (HR>160 beats min(-1)) on the efficacy of the cardiac parasympathetic nervous control of heart rate in humans (20-31 years; of either sex). This intensity of exercise was chosen to produce strong activation of the cardiac sympathetic nerves. Using well-controlled stimulus parameters, the efficacy of cardiac parasympathetic control of heart rate was assessed by recording the heart rate response to carotid baroreceptor activation (CBR) and the amplitude of respiratory sinus arrhythmia (RSA). Measurements were made while the subject performed light exercise (100-135 beats min (-1)) before (Control 1) and after very brief (Control 2) and prolonged (20 min; post) periods of hard exercise. There was no difference in the CBR in the three different measurement periods; 0.33 +/- 0.17, 0.38 +/- 0.18 and 0.39 +/- 0.18 beats min(-1) mm Hg(-1) (mean +/- S.D., N=6) for Control 1, Control 2 and post, respectively. At a heart rate of 120 beats min (-1), amplitude of the RSA was 6.1 +/- 2.4, 5.6 +/- 2.4 and 3.3 +/- 2.1 beats min(-1) for Control 1, Control 2 and post, respectively (P<0.001 post vs. Control 1 and Control 2, N=8). The decrease in RSA amplitude following hard exercise may be attributable to an exercise-induced reduction in airway resistance and work of breathing. Overall, these results do not support the hypothesis that sustained hard exercise that produces strong activation of cardiac sympathetic nerves reduces cardiac parasympathetic efficacy.
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Affiliation(s)
- Rowan W L Herbert
- Department of Physiology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Smith-White MA, Herzog H, Potter EK. Role of neuropeptide Y Y(2) receptors in modulation of cardiac parasympathetic neurotransmission. REGULATORY PEPTIDES 2002; 103:105-11. [PMID: 11786149 DOI: 10.1016/s0167-0115(01)00368-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of the study was to clarify the role of the Y(2) receptor in regulation of vagal control of the heart, using Y(2)((-/-)) receptor-knockout mice. Adult Y(2)((+/+),(-/-)) mice (50% C57BL/6-50% 129/SvJ background) were anaesthetised and artificially ventilated. Arterial blood pressure and pulse interval was recorded and both vagus nerves were cut. The cardiac end of the right vagus nerve was stimulated supra-maximally every 30 s (7 V, 2-2.5 Hz, 5 s). Neuropeptide Y (NPY) and a Y(2) receptor agonist, N-acetyl [Leu(28, 31)]NPY 24-36, were injected intravenously in both groups of mice. N-acetyl [Leu(28, 31)] NPY 24-36 was also administered to control mice in the presence of a Y(2) receptor antagonist, BIIE0246. Stimulation of the vagus nerve increased pulse interval (PI) by approximately 100 ms. NPY and N-acetyl [Leu(28, 31)] NPY 24-36 attenuated the increase in PI evoked by vagal stimulation in control mice only. The attenuation was reduced in the presence of BIIE0246. The results presented here show in Y(2)((-/-)) receptor-knockout mice that NPY and N-acetyl [Leu(28, 31)] NPY 24-36 have no effect on PI evoked by vagal stimulation. These findings demonstrate that NPY attenuates parasympathetic activity to the heart via the Y(2) receptor.
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Affiliation(s)
- Margaret A Smith-White
- Prince of Wales Medical Research Institute, Prince of Wales Hospital, Barker St., Randwick 2031, Sydney, Australia.
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Wennerblom B, Lurje L, Karlsson T, Tygesen H, Vahisalo R. Circadian variation of heart rate variability and the rate of autonomic change in the morning hours in healthy subjects and angina patients. Int J Cardiol 2001; 79:61-9. [PMID: 11399342 DOI: 10.1016/s0167-5273(01)00405-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Incidence of sudden cardiac death peaks during the early morning hours when there is a rapid withdrawal of vagal and an increase of sympathetic tone. The rate of autonomic change could be of prognostic importance. PATIENTS AND METHODS A total of 65 patients with angina pectoris, free from other diseases and drug free, were Holter monitored for 24 h. A total of 30 patients were also monitored on isosorbide-5-mononitrate (IS-5-MN) and on metoprolol respectively. A total of 33 age-matched healthy subjects served as controls. Spectral components of heart rate variability (HRV) were analysed hourly, with special reference to the rapid changes of autonomic tone during the night and early morning hours. Circadian variation was assessed in two ways: (1) Mean HRV day (8 a.m.-8 p.m.) and night (0-5 a.m.) were compared. (2) For the morning/night hours (0-10 a.m.), individual hourly values for max. and min. HRV, the difference max.-min. (gradient), the rate of change per hour between max. and min. (velocity) and the largest difference between two consecutive hours (max. velocity) were recorded and the mean value for the group calculated. RESULTS During the night/morning hours, healthy controls demonstrated faster HF max. velocity (P=0.002) and higher HF gradient (P=0.011) than angina patients. Metoprolol and IS-5-MN increased the HF gradient (P=0.008 and P=0.003, respectively), and metoprolol tended to increase the max. velocity (P=0.02). Metoprolol substantially decreased the LF/HF gradient (P=0.001), velocity (P=0.008) and max. velocity (P=0.0001). CONCLUSION Rapid vagal withdrawal seemed to be a sign of a healthy autonomic nervous system in the control group but was significantly slower in angina patients. IS-5-MN and metoprolol tended to normalise vagal withdrawal and metoprolol slowed down the rapid increase in sympathetic predominance in the morning in patients.
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Affiliation(s)
- B Wennerblom
- Division of Cardiology, Sahlgrenska University Hospital, S-413 45, Göteborg, Sweden.
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