1
|
Chen S, Takahashi N, Chen C, Pauli JL, Kuroki C, Kaminosono J, Kashiwadani H, Kanmura Y, Mori Y, Ou S, Hao L, Kuwaki T. Transient Receptor Potential Ankyrin 1 Mediates Hypoxic Responses in Mice. Front Physiol 2020; 11:576209. [PMID: 33192579 PMCID: PMC7642990 DOI: 10.3389/fphys.2020.576209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 09/23/2020] [Indexed: 12/03/2022] Open
Abstract
Transient receptor potential ankyrin 1 (TRPA1) is a non-selective cation channel that is broadly expressed in sensory pathways, such as the trigeminal and vagus nerves. It is capable of detecting various irritants in inspired gasses and is activated during hypoxia. In this study, the role of TRPA1 in hypoxia-induced behavioral, respiratory, and cardiovascular responses was examined through four lines of experiments using TRPA1 knockout (KO) mice and wild type (WT) littermates. First, KO mice showed significantly attenuated avoidance behavior in response to a low (15%) oxygen environment. Second, the wake-up response to a hypoxic ramp (from 21 to 10% O2 in 40 s) was measured using EEG electrodes. WT mice woke up within 30 s when oxygen was at 13–14%, but KO mice did not wake up until oxygen levels reached 10%. Histological analysis confirmed that mild (13% O2) hypoxia resulted in an attenuation of trigeminal neuronal activation in KO mice. Third, the ventilatory response to hypoxia was measured with whole body plethysmography. KO mice showed attenuated responses to mild hypoxia (15% O2) but not severe hypoxia (10% O2). Similar responses were observed in WT mice treated with the TRPA1 blocker, AP-18. These data clearly show that TRPA1 is necessary for multiple mild hypoxia (13–15% O2)-induced physiological responses. We propose that TRPA1 channels in the sensory pathways innervating the airway can detect hypoxic environments and prevent systemic and/or cellular hypoxia from occurring.
Collapse
Affiliation(s)
- Sichong Chen
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Nobuaki Takahashi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan.,The Hakubi Center for Advanced Research, Kyoto University, Kyoto, Japan
| | - Changping Chen
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Department of Neurosurgery, First Affiliated Hospital of China Medical University, Shenyang, China
| | - Jordan L Pauli
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Chiharu Kuroki
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Jun Kaminosono
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Hideki Kashiwadani
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Yuichi Kanmura
- Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Shaowu Ou
- Department of Neurosurgery, First Affiliated Hospital of China Medical University, Shenyang, China
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Tomoyuki Kuwaki
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| |
Collapse
|
2
|
Cummings KJ, Leiter JC. Take a deep breath and wake up: The protean role of serotonin preventing sudden death in infancy. Exp Neurol 2020; 326:113165. [PMID: 31887304 PMCID: PMC6956249 DOI: 10.1016/j.expneurol.2019.113165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 12/14/2019] [Accepted: 12/26/2019] [Indexed: 01/24/2023]
Abstract
Recordings from infants who died suddenly and unexpectedly demonstrate the occurrence of recurring apneas, ineffective gasping, and finally, failure to restore eupnea and arouse prior to death. Immunohistochemical and autoradiographic data demonstrate a constellation of serotonergic defects in the caudal raphe nuclei in infants who died of Sudden Infant Death Syndrome (SIDS). The purpose of this review is to synthesize what is known about adaptive responses of the infant to severely hypoxic conditions, which unleash a flood of neuromodulators that inhibit cardiorespiratory function, thermogenesis, and arousal and the emerging role of serotonin, which combats this cardiorespiratory inhibition to foster autoresuscitation, eupnea, and arousal to ensure survival following an hypoxic episode. The laryngeal and carotid body chemoreflexes are potent in newborns and infants, and both reflexes can induce apnea and bradycardia, which may be adaptive initially, but must be terminated if an infant is to survive. Serotonin has a unique ability to touch on each of the processes that may be required to recover from hypoxic reflex apnea: gasping, the restoration of heart rate and blood pressure, termination of apneas and, eventually, stimulation of eupnea and arousal. Recurrent apneic events, bradycardia, ineffective gasping and a failure to terminate apneas and restore eupnea are observed in animals harboring defects in the caudal serotonergic system models - all of these phenotypes are reminiscent of and compatible with the cardiorespiratory recordings made in infants who subsequently died of SIDS. The caudal serotonergic system provides an organized, multi-pronged defense against reflex cardiorespiratory inhibition and the hypoxia that accompanies prolonged apnea, bradycardia and hypotension, and any deficiency of caudal serotonergic function will increase the propensity for sudden unexplained infant death.
Collapse
Affiliation(s)
- Kevin J Cummings
- Department of Biomedical Sciences, University of Missouri-Columbia, Dalton Cardiovascular Research Center, 134 Research Park Drive, Columbia, MO 65203, USA
| | - James C Leiter
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, One Rope Ferry Road, Hanover, NH 03755, USA.
| |
Collapse
|