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Chan PYS, Lee LY, Davenport PW. Neural mechanisms of respiratory interoception. Auton Neurosci 2024; 253:103181. [PMID: 38696917 DOI: 10.1016/j.autneu.2024.103181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 04/03/2024] [Accepted: 04/22/2024] [Indexed: 05/04/2024]
Abstract
Respiratory interoception is one of the internal bodily systems that is comprised of different types of somatic and visceral sensations elicited by different patterns of afferent input and respiratory motor drive mediating multiple respiratory modalities. Respiratory interoception is a complex system, having multiple afferents grouped into afferent clusters and projecting into both discriminative and affective centers that are directly related to the behavioral assessment of breathing. The multi-afferent system provides a spectrum of input that result in the ability to interpret the different types of respiratory interceptive sensations. This can result in a response, commonly reported as breathlessness or dyspnea. Dyspnea can be differentiated into specific modalities. These respiratory sensory modalities lead to a general sensation of an Urge-to-Breathe, driven by a need to compensate for the modulation of ventilation that has occurred due to factors that have affected breathing. The multiafferent system for respiratory interoception can also lead to interpretation of the sensory signals resulting in respiratory related sensory experiences, including the Urge-to-Cough and Urge-to-Swallow. These behaviors are modalities that can be driven through the differentiation and integration of multiple afferent input into the respiratory neural comparator. Respiratory sensations require neural somatic and visceral interoceptive elements that include gated attention and detection leading to respiratory modality discrimination with subsequent cognitive decision and behavioral compensation. Studies of brain areas mediating cortical and subcortical respiratory sensory pathways are summarized and used to develop a model of an integrated respiratory neural network mediating respiratory interoception.
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Affiliation(s)
- Pei-Ying Sarah Chan
- Department of Occupational Therapy, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Psychiatry, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
| | - Lu-Yuan Lee
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Paul W Davenport
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
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Lin YS, Chan NJ, Xiao PY, Lai CJ. Stimulatory effect of methylglyoxal on capsaicin-sensitive lung vagal afferents in rats: role of TRPA1. Am J Physiol Regul Integr Comp Physiol 2024; 326:R427-R437. [PMID: 38497128 DOI: 10.1152/ajpregu.00297.2023] [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: 12/31/2023] [Revised: 03/06/2024] [Accepted: 03/11/2024] [Indexed: 03/19/2024]
Abstract
Methylglyoxal (MG), a reactive metabolic byproduct of glycolysis, is a causative of painful diabetic neuropathy. Patients with diabetes are associated with more frequent severe asthma exacerbation. Stimulation of capsaicin-sensitive lung vagal (CSLV) afferents may contribute to the pathogenesis of hyperreactive airway diseases such as asthma. However, the possibility of the stimulatory effect of MG on CSLV afferents and the underlying mechanisms remain unknown. Our results showed that intravenous injection of MG (25 mg/kg, MG25) in anesthetized, spontaneously breathing rats elicited pulmonary chemoreflexes characterized by apnea, bradycardia, and hypotension. The MG-induced apneic response was reproducible and dose dependent. MG25 no longer evoked these reflex responses after perineural capsaicin treatment of both cervical vagi to block C-fibers' conduction, suggesting that the reflexes were mediated through the stimulation of CSLV afferents. Pretreatment with HC030031 [an antagonist of transient receptor potential ankyrin subtype 1 protein (TRPA1)] or AP18 (another TRPA1 antagonist), but not their vehicle, markedly attenuated the apneic response induced by MG25. Consistently, electrophysiological results showed that pretreatment with HC030031 largely attenuated the intense discharge in CSLV afferents induced by injection of MG25 in open-chest and artificially ventilated rats. In isolated CSLV neurons, the perfusion of MG evoked an abrupt and pronounced increase in calcium transients in a concentration-dependent manner. This stimulatory effect on CSLV neurons was also abolished by HC030031 treatment but not by its vehicle. In conclusion, these results suggest that MG exerts a stimulatory effect on CSLV afferents, inducing pulmonary chemoreflexes, and such stimulation is mediated through the TRPA1 activation.NEW & NOTEWORTHY Methylglyoxal (MG) is implicated in the development of painful diabetic neuropathy. A retrospective cohort study revealed an increased incidence of asthma exacerbations in patients with diabetes. This study demonstrated that elevated circulating MG levels stimulate capsaicin-sensitive lung vagal afferents via activation of TRPA1, which in turn triggers respiratory reflexes. These findings provide new information for understanding the pathogenic mechanism of diabetes-associated hyperreactive airway diseases and potential therapy.
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Affiliation(s)
- You Shuei Lin
- Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Graduate Institute of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Nai-Ju Chan
- Graduate Institute of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Pei-Yu Xiao
- Master Program in Biomedical Science, School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Ching Jung Lai
- Master Program in Biomedical Science, School of Medicine, Tzu Chi University, Hualien, Taiwan
- Department of Physiology, Tzu Chi University, Hualien, Taiwan
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Jones AA, Arble DM. In light of breathing: environmental light is an important modulator of breathing with clinical implications. Front Neurosci 2023; 17:1217799. [PMID: 37521684 PMCID: PMC10373889 DOI: 10.3389/fnins.2023.1217799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 06/27/2023] [Indexed: 08/01/2023] Open
Abstract
In vertebrate animals, the automatic, rhythmic pattern of breathing is a highly regulated process that can be modulated by various behavioral and physiological factors such as metabolism, sleep-wake state, activity level, and endocrine signaling. Environmental light influences many of these modulating factors both indirectly by organizing daily and seasonal rhythms of behavior and directly through acute changes in neural signaling. While several observations from rodent and human studies suggest that environmental light affects breathing, few have systematically evaluated the underlying mechanisms and clinical relevance of environmental light on the regulation of respiratory behavior. Here, we provide new evidence and discuss the potential neurobiological mechanisms by which light modulates breathing. We conclude that environmental light should be considered, from bench to bedside, as a clinically relevant modulator of respiratory health and disease.
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Yu J. Research journey into multiple-sensor theory. J Neurophysiol 2023; 130:128-138. [PMID: 37341418 DOI: 10.1152/jn.00062.2023] [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: 02/06/2023] [Revised: 06/05/2023] [Accepted: 06/06/2023] [Indexed: 06/22/2023] Open
Abstract
In 1998, I was asked by the American Physiological Society to review a book written by Dr. Michael de Burgh Daly, Peripheral Arterial Chemoreceptors and Respiratory-Cardiovascular Integration. Inspired by this work, I came to appreciate how researchers in the later stages of their careers and who provide a detailed review of their experimental approach might effectively contribute to science, especially to the benefit of young scientists (Yu J. The Physiologist 41: 231, 1998.). This article is written in that vein. Over several decades of intensive investigation of cardiopulmonary reflexes, focused on the sensory receptors, my colleagues and I advanced a novel multiple-sensor theory (MST) to explain the role of the vagal mechanosensory system. Described here is our research journey through various stages of developing MST and the process of how the problem was identified, approached, and tackled. MST redefines conventional mechanosensor doctrines and is supported by new studies that clarify a century of research data. It entails reinterpretation of many established findings. Hopefully, this article will benefit young scientists, such as graduate and postdoctoral students in the cardiopulmonary sensory research field.
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Affiliation(s)
- Jerry Yu
- Department of Pulmonary Medicine, University of Louisville, Louisville, Kentucky, United States
- Robley Rex VA Medical Center, Louisville, Kentucky, United States
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Yu J. Multiple sensor theory in airway mechanosensory units. Respir Physiol Neurobiol 2023; 313:104071. [PMID: 37149207 DOI: 10.1016/j.resp.2023.104071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/12/2023] [Accepted: 05/02/2023] [Indexed: 05/08/2023]
Abstract
Two conventional doctrines govern airway mechanosensory interpretation: One-Sensor Theory (OST) and Line-Labeled Theory (LLT). In OST, one afferent fiber connects to a single sensor. In LLT, a different type of sensor sends signals via its specific line to a particular brain region to evoke its reflex. Thus, airway slowly adapting receptors (SARs) inhibit breathing and rapidly adapting receptors (RARs) stimulate breathing. However, recent studies show many different mechanosensors connect to a single afferent fiber (Multiple-Sensor Theory, MST). That is, SARs and RARs may send different types of information through the same afferent pathway, indicating different information has been integrated at the sensory unit level. Thus, a sensory unit is not merely a transducer (textbook concept), but also a processor. MST is a conceptual shift. Data generated over last eight decades under OST require re-interpretation.
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Affiliation(s)
- Jerry Yu
- Department of Pulmonary Medicine, University of Louisville, Louisville, KY 40292, Robley Rex VA Medical Center, Louisville, KY 40206, USA.
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Chan NJ, Hsu CC, Lin YS, Lin RL, Lee LY. Inhibitory effect of sulfur dioxide inhalation on Hering-Breuer inflation reflex in mice: role of voltage-gated potassium channels. J Appl Physiol (1985) 2023; 134:1075-1082. [PMID: 36958348 PMCID: PMC10125024 DOI: 10.1152/japplphysiol.00714.2022] [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: 11/22/2022] [Revised: 03/14/2023] [Accepted: 03/21/2023] [Indexed: 03/25/2023] Open
Abstract
Slowly adapting receptors (SARs), vagal mechanosensitive receptors located in the lung, play an important role in regulating the breathing pattern and Hering-Breuer inflation reflex (HBIR). Inhalation of high concentration of sulfur dioxide (SO2), a common environmental and occupational air pollutant, has been shown to selectively block the SAR activity in rabbits, but the mechanism underlying this inhibitory effect remained a mystery. We carried out this study to determine if inhalation of SO2 can inhibit the HBIR and change the eupneic breathing pattern, and to investigate further a possible involvement of voltage-gated K+ channels in the inhibitory effect of SO2 on these vagal reflex-mediated responses. Our results showed 1) inhalation of SO2 (600 ppm; 8 min) consistently abolished both the phasic activity of SARs and their response to lung inflation in anesthetized, artificially ventilated mice, 2) inhalation of SO2 generated a distinct inhibitory effect on the HBIR and induced slow deep breathing in anesthetized, spontaneously breathing mice, and these effects were reversible and reproducible in the same animals, 3) This inhibitory effect of SO2 was blocked by pretreatment with 4-aminopyridine (4-AP), a nonselective blocker of voltage-gated K+ channel, and unaffected by pretreatment with its vehicle. In conclusion, this study suggests that this inhibitory effect on the baseline breathing pattern and the HBIR response was primarily mediated through the SO2-induced activation of voltage-gated K+ channels located in the vagal bronchopulmonary SAR neurons.NEW & NOTEWORTHY This study demonstrated that inhaled sulfur dioxide completely and reversibly abolished the activity of vagal bronchopulmonary slowly adapting receptors, significantly inhibited the apneic response to lung inflation, and induced slow deep breathing in anesthetized mice. More importantly, our results further suggested that this inhibitory effect was mediated through an action of sulfur dioxide and its derivatives on the voltage-gated potassium channels expressed in the slowly adapting receptor sensory neurons innervating the lung.
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Affiliation(s)
- Nai-Ju Chan
- Department of Physiology, University of Kentucky Medical Center, Lexington, Kentucky, United States
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chun-Chun Hsu
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
- School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Division of Pulmonary Medicine, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan
| | - You Shuei Lin
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Ruei-Lung Lin
- Department of Physiology, University of Kentucky Medical Center, Lexington, Kentucky, United States
| | - Lu-Yuan Lee
- Department of Physiology, University of Kentucky Medical Center, Lexington, Kentucky, United States
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Brouns I, Adriaensen D, Timmermans JP. The pulmonary neuroepithelial body microenvironment represents an underestimated multimodal component in airway sensory pathways. Anat Rec (Hoboken) 2023. [PMID: 36808710 DOI: 10.1002/ar.25171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/13/2023] [Accepted: 01/19/2023] [Indexed: 02/22/2023]
Abstract
Exciting new imaging and molecular tools, combined with state-of-the-art genetically modified mouse models, have recently boosted interest in pulmonary (vagal) sensory pathway investigations. In addition to the identification of diverse sensory neuronal subtypes, visualization of intrapulmonary projection patterns attracted renewed attention on morphologically identified sensory receptor end-organs, such as the pulmonary neuroepithelial bodies (NEBs) that have been our area of expertise for the past four decades. The current review aims at providing an overview of the cellular and neuronal components of the pulmonary NEB microenvironment (NEB ME) in mice, underpinning the role of these complexly organized structures in the mechano- and chemosensory potential of airways and lungs. Interestingly, the pulmonary NEB ME additionally harbors different types of stem cells, and emerging evidence suggests that the signal transduction pathways that are active in the NEB ME during lung development and repair also determine the origin of small cell lung carcinoma. Although documented for many years that NEBs appear to be affected in several pulmonary diseases, the current intriguing knowledge on the NEB ME seems to encourage researchers that are new to the field to explore the possibility that these versatile sensor-effector units may be involved in lung pathogenesis or pathobiology.
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Affiliation(s)
- Inge Brouns
- Laboratory of Cell Biology and Histology (CBH), Department of Veterinary Sciences, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
| | - Dirk Adriaensen
- Laboratory of Cell Biology and Histology (CBH), Department of Veterinary Sciences, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
| | - Jean-Pierre Timmermans
- Laboratory of Cell Biology and Histology (CBH), Department of Veterinary Sciences, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
- Antwerp Centre for Advanced Microscopy (ACAM), University of Antwerp, Antwerp, Belgium
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