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Souza JR, Machado BH. Cardiovascular and respiratory evaluation in adenosine A 2A receptor knockout mice submitted to short-term sustained hypoxia. Exp Physiol 2023; 108:1434-1445. [PMID: 37632713 PMCID: PMC10988442 DOI: 10.1113/ep091221] [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: 03/17/2023] [Accepted: 08/03/2023] [Indexed: 08/28/2023]
Abstract
Sustained hypoxia (SH) in mice induces changes in the respiratory pattern and increase in the parasympathetic tone to the heart. Among adenosine G-protein-coupled receptors (GPCRs), the A2A receptors are especially important in mediating adenosine actions during hypoxia due to their expression in neurons involved with the generation and modulation of the autonomic and respiratory functions. Herein, we performed an in vivo evaluation of the baseline cardiovascular and respiratory parameters and their changes in response to SH in knockout mice for A2A receptors (A2A KO). SH produced similar and significant reductions in mean arterial pressure and heart rate in both wild-type (WT) and A2A KO mice when compared to their respective normoxic controls. Mice from WT and A2A KO groups submitted to normoxia or SH presented similar cardiovascular responses to peripheral chemoreflex activation (KCN). Under normoxic conditions A2A KO mice presented a respiratory frequency (fR ) significantly higher in relation to the WT group, which was reduced in response to SH. These data show that the lack of adenosine A2A receptors in mice does not affect the cardiovascular parameters and the autonomic responses to chemoreflex activation in control (normoxia) and SH mice. We conclude that the A2A receptors play a major role in the control of respiratory frequency and in the tachypnoeic response to SH in mice. NEW FINDINGS: What is the central question of this study? Are cardiovascular and respiratory parameters and their changes in response to sustained hypoxia (SH) altered in adenosine A2A receptor knockout mice? What is the main finding and its importance? Cardiovascular parameters and their changes in response to SH were not altered in A2A KO mice. The respiratory frequency in A2A KO was higher than in WT mice. In response to SH the respiratory frequency increased in WT, while it was reduced in A2A KO mice. A2A receptors play a major role in the modulation of respiratory frequency and in the tachypnoeic response to SH in mice.
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Affiliation(s)
- Juliana R. Souza
- Department of Physiology, School of Medicine of Ribeirão PretoUniversity of São PauloRibeirão PretoSPBrazil
| | - Benedito H. Machado
- Department of Physiology, School of Medicine of Ribeirão PretoUniversity of São PauloRibeirão PretoSPBrazil
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Sebastião AM, Ribeiro JA. Adjusting the brakes to adjust neuronal activity: Adenosinergic modulation of GABAergic transmission. Neuropharmacology 2023; 236:109600. [PMID: 37225084 DOI: 10.1016/j.neuropharm.2023.109600] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 04/20/2023] [Accepted: 05/16/2023] [Indexed: 05/26/2023]
Abstract
About 50 years elapsed from the publication of the first full paper on the neuromodulatory action of adenosine at a 'simple' synapse model, the neuromuscular junction (Ginsborg and Hirst, 1972). In that study adenosine was used as a tool to increase cyclic AMP and for the great surprise, it decreased rather than increased neurotransmitter release, and for a further surprise, its action was prevented by theophylline, at the time only known as inhibitor of phosphodiesterases. These intriguing observations opened the curiosity for immediate studies relating the action of adenine nucleotides, known to be released together with neurotransmitters, to that of adenosine (Ribeiro and Walker, 1973, 1975). Our understanding on the ways adenosine uses to modulate synapses, circuits, and brain activity, vastly expanded since then. However, except for A2A receptors, whose actions upon GABAergic neurons of the striatum are well known, most of the attention given to the neuromodulatory action of adenosine has been focusing upon excitatory synapses. Evidence is growing that GABAergic transmission is also a target for adenosinergic neuromodulation through A1 and A2A receptors. Some o these actions have specific time windows during brain development, and others are selective for specific GABAergic neurons. Both tonic and phasic GABAergic transmission can be affected, and either neurons or astrocytes can be targeted. In some cases, those effects result from a concerted action with other neuromodulators. Implications of these actions in the control of neuronal function/dysfunction will be the focus of this review.
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Affiliation(s)
- Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Portugal; Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Portugal.
| | - Joaquim Alexandre Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Portugal; Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Portugal
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Stocco E, Sfriso MM, Borile G, Contran M, Barbon S, Romanato F, Macchi V, Guidolin D, De Caro R, Porzionato A. Experimental Evidence of A 2A-D 2 Receptor-Receptor Interactions in the Rat and Human Carotid Body. Front Physiol 2021; 12:645723. [PMID: 33935801 PMCID: PMC8082109 DOI: 10.3389/fphys.2021.645723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/09/2021] [Indexed: 12/26/2022] Open
Abstract
Adenosine A2A receptors (A2AR) and dopamine D2 receptors (D2R) are known to be involved in the physiological response to hypoxia, and their expression/activity may be modulated by chronic sustained or intermittent hypoxia. To date, A2AR and D2R can form transient physical receptor–receptor interactions (RRIs) giving rise to a dynamic equilibrium able to influence ligand binding and signaling, as demonstrated in different native tissues and transfected mammalian cell systems. Given the presence of A2AR and D2R in type I cells, type II cells, and afferent nerve terminals of the carotid body (CB), the aim of this work was to demonstrate here, for the first time, the existence of A2AR–D2R heterodimers by in situ proximity ligation assay (PLA). Our data by PLA analysis and tyrosine hydroxylase/S100 colocalization indicated the formation of A2AR–D2R heterodimers in type I and II cells of the CB; the presence of A2AR–D2R heterodimers also in afferent terminals is also suggested by PLA signal distribution. RRIs could play a role in CB dynamic modifications and plasticity in response to development/aging and environmental stimuli, including chronic intermittent/sustained hypoxia. Exploring other RRIs will allow for a broad comprehension of the regulative mechanisms these interactions preside over, with also possible clinical implications.
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Affiliation(s)
- Elena Stocco
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padua, Italy
| | - Maria Martina Sfriso
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padua, Italy
| | - Giulia Borile
- Department of Physics and Astronomy "G. Galilei," University of Padova, Padua, Italy.,Institute of Pediatric Research Città della Speranza, Padua, Italy
| | - Martina Contran
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padua, Italy
| | - Silvia Barbon
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padua, Italy
| | - Filippo Romanato
- Department of Physics and Astronomy "G. Galilei," University of Padova, Padua, Italy.,Institute of Pediatric Research Città della Speranza, Padua, Italy
| | - Veronica Macchi
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padua, Italy
| | - Diego Guidolin
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padua, Italy
| | - Raffaele De Caro
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padua, Italy
| | - Andrea Porzionato
- Department of Neuroscience, Institute of Human Anatomy, University of Padova, Padua, Italy
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Adaptative mechanism of the equilibrative nucleoside transporter 1 (ENT-1) and blood adenosine levels in elite freedivers. Eur J Appl Physiol 2020; 121:279-285. [PMID: 33052430 DOI: 10.1007/s00421-020-04523-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 10/01/2020] [Indexed: 12/21/2022]
Abstract
PURPOSE Long static or intense dynamic apnoea-like high-altitude exposure is inducing hypoxia. Adenosine is known to participate to the adaptive response to hypoxia leading to the control of heart rate, blood pressure and vasodilation. Extracellular adenosine level is controlled through the equilibrative nucleoside transporter 1 (ENT-1) and the enzyme adenosine deaminase (ADA). The aim of this study was to determine the control of adenosine blood level (ABL) via ENT-1 and ADA during apnoea-induced hypoxia in elite freedivers was similar to high-altitude adaptation. METHODS Ten freediver champions and ten controls were studied. Biological (e.g. ENT-1, ADA, ABL, PaO2, PaCO2 and pH) and cardiovascular (e.g. heart rate, arterial pressure) parameters were measured at rest and after a submaximal dry static apnoea. RESULTS In freedivers, ABL was higher than in control participants in basal condition and increased more in response to apnoea. Also, freedivers showed an ADA increased in response to apnoea. Finally, ENT-1 level and function were reduced for the free divers. CONCLUSION Our results suggest in freedivers the presence of an adaptive mechanism similar to the one observed in human exposed to chronic hypoxia induced by high-altitude environment.
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Aldossary HS, Alzahrani AA, Nathanael D, Alhuthail EA, Ray CJ, Batis N, Kumar P, Coney AM, Holmes AP. G-Protein-Coupled Receptor (GPCR) Signaling in the Carotid Body: Roles in Hypoxia and Cardiovascular and Respiratory Disease. Int J Mol Sci 2020; 21:ijms21176012. [PMID: 32825527 PMCID: PMC7503665 DOI: 10.3390/ijms21176012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/13/2020] [Accepted: 08/16/2020] [Indexed: 12/17/2022] Open
Abstract
The carotid body (CB) is an important organ located at the carotid bifurcation that constantly monitors the blood supplying the brain. During hypoxia, the CB immediately triggers an alarm in the form of nerve impulses sent to the brain. This activates protective reflexes including hyperventilation, tachycardia and vasoconstriction, to ensure blood and oxygen delivery to the brain and vital organs. However, in certain conditions, including obstructive sleep apnea, heart failure and essential/spontaneous hypertension, the CB becomes hyperactive, promoting neurogenic hypertension and arrhythmia. G-protein-coupled receptors (GPCRs) are very highly expressed in the CB and have key roles in mediating baseline CB activity and hypoxic sensitivity. Here, we provide a brief overview of the numerous GPCRs that are expressed in the CB, their mechanism of action and downstream effects. Furthermore, we will address how these GPCRs and signaling pathways may contribute to CB hyperactivity and cardiovascular and respiratory disease. GPCRs are a major target for drug discovery development. This information highlights specific GPCRs that could be targeted by novel or existing drugs to enable more personalized treatment of CB-mediated cardiovascular and respiratory disease.
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Affiliation(s)
- Hayyaf S. Aldossary
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
- College of Medicine, Basic Medical Sciences, King Saud bin Abdulaziz University for Health Sciences, Riyadh 11481, Saudi Arabia
| | - Abdulaziz A. Alzahrani
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
- Respiratory Care Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, Makkah 24381, Saudi Arabia
| | - Demitris Nathanael
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
| | - Eyas A. Alhuthail
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
- Collage of Sciences and Health Professions, Basic Sciences Department, King Saud bin Abdulaziz University for Health Sciences, Riyadh 11481, Saudi Arabia
| | - Clare J. Ray
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
| | - Nikolaos Batis
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK;
| | - Prem Kumar
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
| | - Andrew M. Coney
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
| | - Andrew P. Holmes
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham B15 2TT, UK
- Correspondence: ; Tel.: +44-121-415-8161
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Adenosine and the Cardiovascular System: The Good and the Bad. J Clin Med 2020; 9:jcm9051366. [PMID: 32384746 PMCID: PMC7290927 DOI: 10.3390/jcm9051366] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 04/27/2020] [Accepted: 04/29/2020] [Indexed: 12/18/2022] Open
Abstract
Adenosine is a nucleoside that impacts the cardiovascular system via the activation of its membrane receptors, named A1R, A2AR, A2BR and A3R. Adenosine is released during hypoxia, ischemia, beta-adrenergic stimulation or inflammation and impacts heart rhythm and produces strong vasodilation in the systemic, coronary or pulmonary vascular system. This review summarizes the main role of adenosine on the cardiovascular system in several diseases and conditions. Adenosine release participates directly in the pathophysiology of atrial fibrillation and neurohumoral syncope. Adenosine has a key role in the adaptive response in pulmonary hypertension and heart failure, with the most relevant effects being slowing of heart rhythm, coronary vasodilation and decreasing blood pressure. In other conditions, such as altitude or apnea-induced hypoxia, obstructive sleep apnea, or systemic hypertension, the adenosinergic system activation appears in a context of an adaptive response. Due to its short half-life, adenosine allows very rapid adaptation of the cardiovascular system. Finally, the effects of adenosine on the cardiovascular system are sometimes beneficial and other times harmful. Future research should aim to develop modulating agents of adenosine receptors to slow down or conversely amplify the adenosinergic response according to the occurrence of different pathologic conditions.
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