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Optical imaging of neurons related to fictive swallowing using GCaMP6f in an arterially perfused rat preparation. J Oral Biosci 2023; 65:126-131. [PMID: 36738967 DOI: 10.1016/j.job.2023.01.009] [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: 01/16/2023] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 02/05/2023]
Abstract
OBJECTIVE It is difficult to comprehensively study the activity patterns and distribution of neurons in the brainstem that control the act of swallowing, as they are located deep in the brain. In this study, we aimed to evaluate the usefulness of calcium imaging using GCaMP6f in arterially perfused preparations to study the activity of swallowing-related neurons in the brainstem. METHODS Arterially perfused rat preparations were prepared 3-4 weeks after the injection of a neuron-specific virus expressing GCaMP6f. Fictive swallowing was induced by repetitive electrical stimulation of the superior laryngeal nerve (SLN). Simultaneously, the activity of GCaMP6f-expressing neurons in the dorsal brainstem, between 0.1 and 4.8 mm rostral to the obex, was assessed by changes in the intracellular calcium concentration using confocal laser microscopy. RESULTS Neurons responding to stimulation of the SLN included swallowing-related neurons (48%), which showed an increase in fluorescence intensity at the time of swallowing bursts in the cervical vagus nerve, and stimulation-related neurons (52%), which showed an increase in fluorescence intensity through stimulation, regardless of the swallowing bursts. Despite a broad search area, swallowing-related neurons were localized exclusively in and around the solitary nucleus. In contrast, most stimulation-related neurons were located in the brainstem reticular formation, which is more rostral than the solitary nucleus. CONCLUSIONS Calcium imaging using GCaMP in arterially perfused rat preparations is useful for an efficient search of the activity pattern and distribution of neurons located in a wide area of the brainstem.
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Takemura A, Sugiyama Y, Yamamoto R, Kinoshita S, Kaneko M, Fuse S, Hashimoto K, Mukudai S, Umezaki T, Dutschmann M, Hirano S. Effect of pharmacological inhibition of the pontine respiratory group on swallowing interneurons in the dorsal medulla oblongata. Brain Res 2022; 1797:148101. [PMID: 36183794 DOI: 10.1016/j.brainres.2022.148101] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/31/2022] [Accepted: 09/26/2022] [Indexed: 11/15/2022]
Abstract
OBJECTIVES To examine the role of neurons of the pontine respiratory group (PRG) overlapping with the Kölliker-Fuse nucleus in the regulation of swallowing, we compared the activity of swallowing motor activities and interneuron discharge in the dorsal swallowing group in the medulla before and after pharmacological inhibition of the PRG. METHODS In 23 in situ perfused brainstem preparation of rats, we recorded the activities of the vagus (VNA), hypoglossal (HNA), and phrenic nerves (PNA), and swallowing interneurons of the dorsal medulla during fictive swallowing elicited by electrical stimulation of the superior laryngeal nerve or oral water injection. Subsequently, respiratory- and swallow-related motor activities and single unit cell discharge were assessed before and after local microinjection of the GABA-receptor agonist muscimol into the area of PRG ipsilateral to the recording sites of swallowing interneurons. RESULTS After muscimol injection, the amplitude and duration of swallow-related VNA bursts decreased to 71.3 ± 2.84 and 68.1 ± 2.76 % during electrically induced swallowing and VNA interburst intervals during repetitive swallowing decreased. Similar effects were observed for swallowing-related HNA. The swallowing motor activity was similarly qualitatively altered during physiologically induced swallowing. All 23 neurons were changed in either discharge duration or frequency after PRG inhibition, however, the general discharge patterns in relation to the motor output remained unchanged. CONCLUSION Descending synaptic inputs from PRG provide control of the primary laryngeal sensory gate and synaptic activity of the PRG partially determine medullary cell and cranial motor nerve activities that govern the pharyngeal stage of swallowing.
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Affiliation(s)
- Akiyo Takemura
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Yoichiro Sugiyama
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
| | - Ryota Yamamoto
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; Department of Otolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-5852, Japan
| | - Shota Kinoshita
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Mami Kaneko
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Shinya Fuse
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Keiko Hashimoto
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Shigeyuki Mukudai
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Toshiro Umezaki
- Department of Speech and Hearing Sciences, International University of Health and Welfare, and the Voice and Swallowing Center, Fukuoka Sanno Hospital, Fukuoka 814-0001, Japan
| | - Mathias Dutschmann
- Florey Institute of Neuroscience and Mental Health, Gate 11, Royal Parade, University of Melbourne, Victoria 3052, Australia
| | - Shigeru Hirano
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
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Yamamoto R, Sugiyama Y, Hashimoto K, Kinoshita S, Takemura A, Fuse S, Kaneko M, Mukudai S, Umezaki T, Dutschmann M, Nakagawa T, Hirano S. Firing characteristics of swallowing interneurons in the dorsal medulla during physiologically induced swallowing in perfused brainstem preparation in rats. Neurosci Res 2021; 177:64-77. [PMID: 34808248 DOI: 10.1016/j.neures.2021.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/09/2021] [Accepted: 11/17/2021] [Indexed: 12/23/2022]
Abstract
Oropharyngeal swallowing is centrally mediated by a swallowing central pattern generator (Sw-CPG) in the medulla oblongata. The activity of the Sw-CPG depends on the sensory inputs determined by physical and chemical bolus properties. Here we investigate the sensory-motor integration during swallowing arising from different sensory sources. To do so we electrically stimulated the superior laryngeal nerve and we triggered swallowing with oral injections of distilled water or capsaicin solution and extracellularly recorded from swallowing interneurons in arterially perfused brainstem preparations of rats. We recorded the activities of 40 neurons, while monitoring the motor activities of the phrenic, vagal and hypoglossal nerves. Eighteen neurons responded to electrical stimulation of the ipsilateral superior laryngeal nerve, and 6 neurons were excited by oral fluid injection, while 16 non-respiratory neurons did not receive afferent inputs to either electrical or physiological stimuli. The cellular activities displayed by swallowing interneurons during electrical and physiological stimulation of pharyngeal and laryngeal afferent input reveal complex adaptations of the timing of firing patterns and frequencies. The modulation of neuronal activity is likely to contribute to the coordination of efficient bolus transfer during the pharyngeal stage of swallowing.
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Affiliation(s)
- Ryota Yamamoto
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan; Department of Otolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-5852, Japan
| | - Yoichiro Sugiyama
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan.
| | - Keiko Hashimoto
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Shota Kinoshita
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Akiyo Takemura
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Shinya Fuse
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Mami Kaneko
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Shigeyuki Mukudai
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Toshiro Umezaki
- Department of Speech and Hearing Sciences, International University of Health and Welfare, and the Voice and Swallowing Center, Fukuoka Sanno Hospital, Fukuoka, 814-0001, Japan
| | - Mathias Dutschmann
- Florey Institute of Neuroscience and Mental Health, Gate 11, Royal Parade, University of Melbourne, VIC 3052, Australia
| | - Takashi Nakagawa
- Department of Otolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-5852, Japan
| | - Shigeru Hirano
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
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Assessment of the Use of Multi-Channel Organic Electrodes to Record ENG on Small Nerves: Application to Phrenic Nerve Burst Detection. SENSORS 2021; 21:s21165594. [PMID: 34451031 PMCID: PMC8402313 DOI: 10.3390/s21165594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/21/2021] [Accepted: 08/07/2021] [Indexed: 12/26/2022]
Abstract
Effective closed-loop neuromodulation relies on the acquisition of appropriate physiological control variables and the delivery of an appropriate stimulation signal. In particular, electroneurogram (ENG) data acquired from a set of electrodes applied at the surface of the nerve may be used as a potential control variable in this field. Improved electrode technologies and data processing methods are clearly needed in this context. In this work, we evaluated a new electrode technology based on multichannel organic electrodes (OE) and applied a signal processing chain in order to detect respiratory-related bursts from the phrenic nerve. Phrenic ENG (pENG) were acquired from nine Long Evans rats in situ preparations. For each preparation, a 16-channel OE was applied around the phrenic nerve’s surface and a suction electrode was applied to the cut end of the same nerve. The former electrode provided input multivariate pENG signals while the latter electrode provided the gold standard for data analysis. Correlations between OE signals and that from the gold standard were estimated. Signal to noise ratio (SNR) and ROC curves were built to quantify phrenic bursts detection performance. Correlation score showed the ability of the OE to record high-quality pENG. Our methods allowed good phrenic bursts detection. However, we failed to demonstrate a spatial selectivity from the multiple pENG recorded with our OE matrix. Altogether, our results suggest that highly flexible and biocompatible multi-channel electrode may represent an interesting alternative to metallic cuff electrodes to perform nerve bursts detection and/or closed-loop neuromodulation.
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Simera M, Veternik M, Martvon L, Kotmanova Z, Mostafavi S, Bosko O, Kralikova O, Poliacek I. Distinct modulation of tracheal and laryngopharyngeal cough via superior laryngeal nerve in cat. Respir Physiol Neurobiol 2021; 293:103716. [PMID: 34119702 DOI: 10.1016/j.resp.2021.103716] [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: 02/22/2021] [Revised: 06/08/2021] [Accepted: 06/08/2021] [Indexed: 11/26/2022]
Abstract
Unilateral and bilateral cooling and bilateral transsection of the superior laryngeal nerve (SLN) were employed to modulate mechanically induced tracheobronchial (TB) and laryngopharyngeal (LPh) cough in 12 anesthetized cats. There was little effect of SLN block or cut on TB. Bilateral SLN cooling reduced the number of LPh (<50 %, p < 0.05), amplitudes of diaphragm EMG activity (<55 %, p < 0.05), and cough expiratory efforts (<40 %, p < 0.01) during LPh. Effects after unilateral SLN cooling were less pronounced. Temporal analysis of LPh showed only shortening of diaphragm and abdominal muscles burst overlap in the inspiratory-expiratory transition after unilateral SLN cooling. Bilateral cooling reduced both expiratory phase and total cough cycle duration. There was no significant difference in the average effects of cooling left or right SLN on LPh or TB as well as no differences in contralateral and ipsilateral diaphragm and abdominal EMG amplitudes. Our results show that reduced afferent drive in the SLN markedly attenuates LPh with virtually no effect on TB.
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Affiliation(s)
- Michal Simera
- Institute of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Malá Hora 4, 036 01 Martin, Slovak Republic.
| | - Marcel Veternik
- Institute of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Malá Hora 4, 036 01 Martin, Slovak Republic
| | - Lukas Martvon
- Institute of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Malá Hora 4, 036 01 Martin, Slovak Republic
| | - Zuzana Kotmanova
- Institute of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Malá Hora 4, 036 01 Martin, Slovak Republic
| | - Soheil Mostafavi
- Institute of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Malá Hora 4, 036 01 Martin, Slovak Republic
| | - Ondrej Bosko
- Institute of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Malá Hora 4, 036 01 Martin, Slovak Republic
| | - Olga Kralikova
- Institute of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Malá Hora 4, 036 01 Martin, Slovak Republic
| | - Ivan Poliacek
- Institute of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Malá Hora 4, 036 01 Martin, Slovak Republic
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Kinoshita S, Sugiyama Y, Hashimoto K, Fuse S, Mukudai S, Umezaki T, Dutschmann M, Hirano S. Influences of GABAergic Inhibition in the Dorsal Medulla on Contralateral Swallowing Neurons in Rats. Laryngoscope 2020; 131:2187-2198. [PMID: 33146426 DOI: 10.1002/lary.29242] [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: 05/05/2020] [Revised: 09/24/2020] [Accepted: 10/21/2020] [Indexed: 12/21/2022]
Abstract
OBJECTIVES We aimed to examine the effect of unilateral inhibition of the medullary dorsal swallowing networks on the activities of swallowing-related cranial motor nerves and swallowing interneurons. METHODS In 25 juvenile rats, we recorded bilateral vagal nerve activity (VNA) as well as unilateral phrenic and hypoglossal activity (HNA) during fictive swallowing elicited by electrical stimulation of the superior laryngeal nerve during control and following microinjection of the GABA agonist muscimol into the caudal dorsal medulla oblongata in a perfused brainstem preparation. In 20 animals, swallowing interneurons contralateral to the muscimol injection side were simultaneously recorded extracellularly and their firing rates were analyzed during swallowing. RESULTS Integrated VNA and HNA to the injection side decreased to 49.0 ± 16.6% and 32.3 ± 17.9%, respectively. However, the VNA on the uninjected side showed little change after muscimol injection. Following local inhibition, 11 out of 20 contralateral swallowing interneurons showed either increased or decreased of their respective firing discharge during evoked-swallowing, while no significant changes in activity were observed in the remaining nine neurons. CONCLUSION The neuronal networks underlying the swallowing pattern generation in the dorsal medulla mediate the ipsilateral motor outputs and modulate the contralateral activity of swallowing interneurons, suggesting that the bilateral coordination of the swallowing central pattern generator regulates the spatiotemporal organization of pharyngeal swallowing movements. LEVEL OF EVIDENCE NA Laryngoscope, 131:2187-2198, 2021.
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Affiliation(s)
- Shota Kinoshita
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yoichiro Sugiyama
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Keiko Hashimoto
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Shinya Fuse
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Shigeyuki Mukudai
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Toshiro Umezaki
- Department of Speech and Hearing Sciences, International University of Health and Welfare, and the Voice and Swallowing Center, Fukuoka Sanno Hospital, Fukuoka, Japan
| | - Mathias Dutschmann
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Shigeru Hirano
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
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Quipazine Elicits Swallowing in the Arterially Perfused Rat Preparation: A Role for Medullary Raphe Nuclei? Int J Mol Sci 2020; 21:ijms21145120. [PMID: 32698469 PMCID: PMC7404031 DOI: 10.3390/ijms21145120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/06/2020] [Accepted: 07/16/2020] [Indexed: 12/17/2022] Open
Abstract
Pharmacological neuromodulation of swallowing may represent a promising therapeutic option to treat dysphagia. Previous studies suggested a serotonergic control of swallowing, but mechanisms remain poorly understood. Here, we investigated the effects of the serotonergic agonist quipazine on swallowing, using the arterially perfused working heart-brainstem (in situ) preparation in rats. Systemic injection of quipazine produced single swallows with motor patterns and swallow-breathing coordination similar to spontaneous swallows, and increased swallow rate with moderate changes in cardiorespiratory functions. Methysergide, a 5-HT2 receptor antagonist, blocked the excitatory effect of quipazine on swallowing, but had no effect on spontaneous swallow rate. Microinjections of quipazine in the nucleus of the solitary tract were without effect. In contrast, similar injections in caudal medullary raphe nuclei increased swallow rate without changes in cardiorespiratory parameters. Thus, quipazine may exert an excitatory effect on raphe neurons via stimulation of 5-HT2A receptors, leading to increased excitability of the swallowing network. In conclusion, we suggest that pharmacological stimulation of swallowing by quipazine in situ represents a valuable model for experimental studies. This work paves the way for future investigations on brainstem serotonergic modulation, and further identification of neural populations and mechanisms involved in swallowing and/or swallow-breathing interaction.
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