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Shin MK, Tang WY, Amorim MR, Sham JSK, Polotsky VY. Carotid body denervation improves hyperglycemia in obese mice. J Appl Physiol (1985) 2024; 136:233-243. [PMID: 38126089 DOI: 10.1152/japplphysiol.00215.2023] [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: 04/04/2023] [Revised: 11/14/2023] [Accepted: 12/13/2023] [Indexed: 12/23/2023] Open
Abstract
The carotid bodies (CBs) have been implicated in glucose abnormalities in obesity via elevation of activity of the sympathetic nervous system. Obesity-induced hypertension is mediated by insulin receptor (INSR) signaling and by leptin, which binds to the leptin receptor (LEPRb) in CB and activates transient receptor potential channel subfamily M member 7 (TRPM7). We hypothesize that in mice with diet-induced obesity, hyperglycemia, glucose intolerance, and insulin resistance will be attenuated by the CB denervation (carotid sinus nerve dissection, CSND) and by knockdown of Leprb, Trpm7, and Insr gene expression in CB. In series of experiments in 75 male diet-induced obese (DIO) mice, we performed either CSND (vs. sham) surgeries or shRNA-induced suppression of Leprb, Trpm7, or Insr gene expression in CB, followed by blood pressure telemetry, intraperitoneal glucose tolerance and insulin tolerance tests, and measurements of fasting plasma insulin, leptin, corticosterone, glucagon and free fatty acids (FFAs) levels, hepatic expression of gluconeogenesis enzymes phosphoenolpyruvate carboxykinase (PEPCK) and glucose 6-phosphatase (G-6-Pase) mRNA and liver glycogen levels. CSND decreased blood pressure, fasting blood glucose levels and improved glucose tolerance without any effect on insulin resistance. CSND did not affect any hormone levels and gluconeogenesis enzymes, but increased liver glycogen level. Genetic knockdown of CB Leprb, Trpm7, and Insr had no effect on glucose metabolism. We conclude that CB contributes to hyperglycemia of obesity, probably by modulation of the glycogen-glucose equilibrium. Diabetogenic effects of obesity on CB in mice do not occur via activation of CB Leprb, Trpm7, and Insr.NEW & NOTEWORTHY This paper provides first evidence that carotid body denervation abolishes hypertension and improves fasting blood glucose levels and glucose tolerance in mice with diet-induced obesity. Furthermore, we have shown that this phenomenon is associated with increased liver glycogen content, whereas insulin sensitivity and enzymes of gluconeogenesis were not affected.
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Affiliation(s)
- Mi-Kyung Shin
- Department of Anesthesiology and Critical Care Medicine, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States
| | - Wan-Yee Tang
- Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh, Pennsylvania, United States
| | - Mateus R Amorim
- Department of Anesthesiology and Critical Care Medicine, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States
| | - James S-K Sham
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Vsevolod Y Polotsky
- Department of Anesthesiology and Critical Care Medicine, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States
- Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States
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Amorim MR, Wang X, Aung O, Bevans-Fonti S, Anokye-Danso F, Ribeiro C, Escobar J, Freire C, Pho H, Dergacheva O, Branco LGS, Ahima RS, Mendelowitz D, Polotsky VY. Leptin signaling in the dorsomedial hypothalamus couples breathing and metabolism in obesity. Cell Rep 2023; 42:113512. [PMID: 38039129 PMCID: PMC10804286 DOI: 10.1016/j.celrep.2023.113512] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 10/25/2023] [Accepted: 11/14/2023] [Indexed: 12/03/2023] Open
Abstract
Mismatch between CO2 production (Vco2) and respiration underlies the pathogenesis of obesity hypoventilation. Leptin-mediated CNS pathways stimulate both metabolism and breathing, but interactions between these functions remain elusive. We hypothesized that LEPRb+ neurons of the dorsomedial hypothalamus (DMH) regulate metabolism and breathing in obesity. In diet-induced obese LeprbCre mice, chemogenetic activation of LEPRb+ DMH neurons increases minute ventilation (Ve) during sleep, the hypercapnic ventilatory response, Vco2, and Ve/Vco2, indicating that breathing is stimulated out of proportion to metabolism. The effects of chemogenetic activation are abolished by a serotonin blocker. Optogenetic stimulation of the LEPRb+ DMH neurons evokes excitatory postsynaptic currents in downstream serotonergic neurons of the dorsal raphe (DR). Administration of retrograde AAV harboring Cre-dependent caspase to the DR deletes LEPRb+ DMH neurons and abolishes metabolic and respiratory responses to leptin. These findings indicate that LEPRb+ DMH neurons match breathing to metabolism through serotonergic pathways to prevent obesity-induced hypoventilation.
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Affiliation(s)
- Mateus R Amorim
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA; Department of Anesthesiology and Critical Care Medicine, George Washington University, Washington, DC 20037, USA.
| | - Xin Wang
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - O Aung
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA
| | - Shannon Bevans-Fonti
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA; Department of Anesthesiology and Critical Care Medicine, George Washington University, Washington, DC 20037, USA
| | | | - Caitlin Ribeiro
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - Joan Escobar
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - Carla Freire
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA
| | - Huy Pho
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA
| | - Olga Dergacheva
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - Luiz G S Branco
- University of São Paulo, Ribeirão Preto, São Paulo 14040-904, Brazil
| | - Rexford S Ahima
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA
| | - Vsevolod Y Polotsky
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA; Department of Anesthesiology and Critical Care Medicine, George Washington University, Washington, DC 20037, USA; Department of Pharmacology and Physiology, George Washington University, Washington, DC 20037, USA.
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Kim LJ, Pho H, Anokye-Danso F, Ahima RS, Pham LV, Polotsky VY. The effect of diet-induced obesity on sleep and breathing in female mice. Sleep 2023; 46:zsad158. [PMID: 37262435 PMCID: PMC10424169 DOI: 10.1093/sleep/zsad158] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/24/2023] [Indexed: 06/03/2023] Open
Abstract
Obesity and male sex are main risk factors for sleep-disordered breathing (SDB). We have shown that male diet-induced obesity (DIO) mice develop hypoventilation, sleep apnea, and sleep fragmentation. The effects of DIO on breathing and sleep architecture in females have not been investigated. We hypothesized that female mice are less susceptible to the detrimental effects of DIO on sleep and SDB compared to males. Female DIO-C57BL/6J and lean C57BL/6J mice underwent 24-hour metabolic studies and were exposed to 8% CO2 to measure the hypercapnic ventilatory response (HCVR), and sleep studies. Ventilatory response to arousals was calculated as ratio of the average and peak minute ventilation (VE) during each arousal relative to the baseline VE. Breathing stability was measured with Poincaré plots of VE. Female obesity was associated with decreased metabolism, indicated by reduced oxygen consumption (VO2) and CO2 production (VCO2). VE in 8% CO2 and HCVR were significantly attenuated during wakefulness. NREM sleep duration was reduced in DIO mice, but REM sleep was preserved. Ventilation during NREM and REM sleep was augmented compared to lean mice. Arousal frequency was similar between groups. Obesity increased the frequency of spontaneous arousals, whereas the apnea index was 4-fold reduced in DIO compared to lean mice. Obesity decreased pre- and post-apnea arousals. Obese mice had more stable breathing with reduced ventilatory response to arousals, compared to lean females. We conclude that obese female mice are protected against SDB, which appears to be related to an attenuated CO2 responsiveness, compared to the lean state.
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Affiliation(s)
- Lenise J Kim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Anesthesiology and Critical Care Medicine, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA
| | - Huy Pho
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Frederick Anokye-Danso
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Rexford S Ahima
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Luu V Pham
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Vsevolod Y Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Anesthesiology and Critical Care Medicine, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA
- Department of Pharmacology and Physiology, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA
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Pauza AG, Murphy D, Paton JFR. Transcriptomics of the Carotid Body. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1427:1-11. [PMID: 37322330 DOI: 10.1007/978-3-031-32371-3_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The carotid body (CB) has emerged as a potential therapeutic target for treating sympathetically mediated cardiovascular, respiratory, and metabolic diseases. In adjunct to its classical role as an arterial O2 sensor, the CB is a multimodal sensor activated by a range of stimuli in the circulation. However, consensus on how CB multimodality is achieved is lacking; even the best studied O2-sensing appears to involve multiple convergent mechanisms. A strategy to understand multimodal sensing is to adopt a hypothesis-free, high-throughput transcriptomic approach. This has proven instrumental for understanding fundamental mechanisms of CB response to hypoxia and other stimulants, its developmental niche, cellular heterogeneity, laterality, and pathophysiological remodeling in disease states. Herein, we review this published work that reveals novel molecular mechanisms underpinning multimodal sensing and reveals numerous gaps in knowledge that require experimental testing.
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Affiliation(s)
- Audrys G Pauza
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, Auckland, New Zealand.
| | - David Murphy
- Molecular Neuroendocrinology Research Group, Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Julian F R Paton
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, Auckland, New Zealand
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Zubieta-DeUrioste N, Wilson RJA. Beyond arterial blood gas sensing: the carotid body's TRP to broad physiological function. J Physiol 2022; 600:4965-4966. [PMID: 36334056 DOI: 10.1113/jp283940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 11/02/2022] [Indexed: 11/08/2022] Open
Affiliation(s)
- Natalia Zubieta-DeUrioste
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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