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Boljanović J, Milisavljević M, Latas M, Puškaš L, Bogosavljević N, Vujačić M, Aleksandrić D, Ćetković D, Branković N, Dožić A, Ćetković M. Arterial supply and morphological characteristics of sympathetic neurons in the human superior cervical ganglion. Front Neuroanat 2024; 18:1372180. [PMID: 38511050 PMCID: PMC10950939 DOI: 10.3389/fnana.2024.1372180] [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: 01/17/2024] [Accepted: 02/22/2024] [Indexed: 03/22/2024] Open
Abstract
The aim of this study was the micromorphological analysis of the distribution of microvessels, mast cells and ganglionic neurons in two parts, proximal and distal of the human superior cervical sympathetic ganglions (SCSGs). Statistical analyses were applied to detect the possible metric regional differences in their densities. Five injected human SCSGs with colored India ink and gelatin were microdissected and examined. Second group of five human SCSGs was prepared and serially sliced for CD34 and mast cell tryptase immunostaining. The microscopic fields of two parts of the SCSGs were analyzed for the following quantifications: microvessel density (MVD), mast cell density (MCD), and ganglionic cell count and measurements. The mean number of CD34-positive microvessels in microscopic fields, the MVD, had a value of 83 for the upper parts, and 82.7 for the lower parts of SCSGs. The mean number of tryptase-positive mast cells in microscopic fields, the MCD, was 4.5 in the proximal parts, and 4.7 in the distal parts of SCSGs. The mean number of ganglionic neurons in microscopic fields was 19.5 in the proximal parts, and 19.8 in the distal parts of SCSGs. The density of CD34-positive microvessels, the density of tryptase-positive mast cells, and the density, mean diameters and mean areas of ganglionic neurons were not significantly different in two observed parts, upper and lower of the SCSGs. In conclusion, the distributions of microvessels, mast cells, and neurons in two parts of the SCSGs were uniform with no specific micromorphological variations, there is a homogenous vascular and cellular pattern within the SCSGs.
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Affiliation(s)
- Jelena Boljanović
- Laboratory for Vascular Morphology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Milan Milisavljević
- Laboratory for Vascular Morphology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
- Academy of Medical Sciences, Serbian Medical Association, Belgrade, Serbia
| | - Milan Latas
- Clinic for Psychiatry, University Clinical Center of Serbia, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Laslo Puškaš
- Laboratory for Vascular Morphology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Nikola Bogosavljević
- Institute for Orthopedic Surgery “Banjica”, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Marko Vujačić
- Institute for Orthopedic Surgery “Banjica”, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Dejan Aleksandrić
- Institute for Orthopedic Surgery “Banjica”, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Dejan Ćetković
- Institute of Anatomy, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia
| | - Nemanja Branković
- Pacemaker Center, University Clinical Center of Serbia, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Aleksandra Dožić
- Institute of Anatomy, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia
| | - Mila Ćetković
- Institute of Histology and Embryology, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
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Han C, Lim JY, Koike N, Kim SY, Ono K, Tran CK, Mangutov E, Kim E, Zhang Y, Li L, Pradhan AA, Yagita K, Chen Z, Yoo SH, Burish MJ. Regulation of headache response and transcriptomic network by the trigeminal ganglion clock. Headache 2024; 64:195-210. [PMID: 38288634 PMCID: PMC10961824 DOI: 10.1111/head.14670] [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: 07/02/2023] [Revised: 12/06/2023] [Accepted: 12/20/2023] [Indexed: 02/17/2024]
Abstract
OBJECTIVE To characterize the circadian features of the trigeminal ganglion in a mouse model of headache. BACKGROUND Several headache disorders, such as migraine and cluster headache, are known to exhibit distinct circadian rhythms of attacks. The circadian basis for these rhythmic pain responses, however, remains poorly understood. METHODS We examined trigeminal ganglion ex vivo and single-cell cultures from Per2::LucSV reporter mice and performed immunohistochemistry. Circadian behavior and transcriptomics were investigated using a novel combination of trigeminovascular and circadian models: a nitroglycerin mouse headache model with mechanical thresholds measured every 6 h, and trigeminal ganglion RNA sequencing measured every 4 h for 24 h. Finally, we performed pharmacogenomic analysis of gene targets for migraine, cluster headache, and trigeminal neuralgia treatments as well as trigeminal ganglion neuropeptides; this information was cross-referenced with our cycling genes from RNA sequencing data to identify potential targets for chronotherapy. RESULTS The trigeminal ganglion demonstrates strong circadian rhythms in both ex vivo and single-cell cultures, with core circadian proteins found in both neuronal and non-neuronal cells. Using our novel behavioral model, we showed that nitroglycerin-treated mice display circadian rhythms of pain sensitivity which were abolished in arrhythmic Per1/2 double knockout mice. Furthermore, RNA-sequencing analysis of the trigeminal ganglion revealed 466 genes that displayed circadian oscillations in the control group, including core clock genes and clock-regulated pain neurotransmitters. In the nitroglycerin group, we observed a profound circadian reprogramming of gene expression, as 331 of circadian genes in the control group lost rhythm and another 584 genes gained rhythm. Finally, pharmacogenetics analysis identified 10 genes in our trigeminal ganglion circadian transcriptome that encode target proteins of current medications used to treat migraine, cluster headache, or trigeminal neuralgia. CONCLUSION Our study unveiled robust circadian rhythms in the trigeminal ganglion at the behavioral, transcriptomic, and pharmacogenetic levels. These results support a fundamental role of the clock in pain pathophysiology. PLAIN LANGUAGE SUMMARY Several headache diseases, such as migraine and cluster headache, have headaches that occur at the same time each day. We learned that the trigeminal ganglion, an important pain structure in several headache diseases, has a 24-hour cycle that might be related to this daily cycle of headaches. Our genetic analysis suggests that some medications may be more effective in treating migraine and cluster headache when taken at specific times of the day.
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Affiliation(s)
- Chorong Han
- Department of Biochemistry and Molecular Biology, UTHealth Houston, Houston, Texas, USA
| | - Ji Ye Lim
- Department of Biochemistry and Molecular Biology, UTHealth Houston, Houston, Texas, USA
| | - Nobuya Koike
- Department of Physiology and Systems Bioscience, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Sun Young Kim
- Department of Biochemistry and Molecular Biology, UTHealth Houston, Houston, Texas, USA
| | - Kaori Ono
- Department of Biochemistry and Molecular Biology, UTHealth Houston, Houston, Texas, USA
| | - Celia K. Tran
- Department of Biochemistry and Molecular Biology, UTHealth Houston, Houston, Texas, USA
| | - Elizaveta Mangutov
- Center for Clinical Pharmacology, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Eunju Kim
- Department of Biochemistry and Molecular Biology, UTHealth Houston, Houston, Texas, USA
| | - Yanping Zhang
- Center for Clinical Pharmacology, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Lingyong Li
- Division of Molecular and Translational Biomedicine, Department of Anesthesiology and Perioperative Medicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Amynah A. Pradhan
- Center for Clinical Pharmacology, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Kazuhiro Yagita
- Department of Physiology and Systems Bioscience, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Zheng Chen
- Department of Biochemistry and Molecular Biology, UTHealth Houston, Houston, Texas, USA
| | - Seung-Hee Yoo
- Department of Biochemistry and Molecular Biology, UTHealth Houston, Houston, Texas, USA
| | - Mark J. Burish
- Department of Neurosurgery, UTHealth Houston, Houston, Texas, USA
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Friedrich N, Németh K, Tanner M, Rosta J, Dobos I, Oszlács O, Jancsó G, Messlinger K, Dux M. Anti-CGRP antibody galcanezumab modifies the function of the trigeminovascular nocisensor complex in the rat. J Headache Pain 2024; 25:9. [PMID: 38243174 PMCID: PMC10799508 DOI: 10.1186/s10194-024-01717-2] [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: 12/23/2023] [Accepted: 01/14/2024] [Indexed: 01/21/2024] Open
Abstract
BACKGROUND Monoclonal antibodies directed against the neuropeptide calcitonin gene-related peptide (CGRP) are effective in the prevention of chronic and frequent episodic migraine. Since the antibodies do not cross the blood brain barrier, their antinociceptive effect is attributed to effects in meningeal tissues. We aimed to probe if such an antibody can be visualized within the dura mater and the trigeminal ganglia following its administration to rats and to examine if the activity of the trigeminovascular nocisensor complex is influenced by this treatment. METHODS Effects of the anti-CGRP antibody galcanezumab on the trigeminovascular nocisensor complex was examined by measuring release of sensory neuropeptides and histamine from the rat dura mater. Deposits of galcanezumab were visualized by fluorescence microscopy in the trigeminal ganglion and the dura mater. RESULTS Fluorophore-labelled galcanezumab was detected in the dura mater and the trigeminal ganglion up to 30 days after treatment affirming the long-lasting modulatory effect of this antibody. In female rats, seven days after systemic treatment with galcanezumab the capsaicin-induced release of CGRP was decreased, while that of substance P (SP) was increased in the dura mater. In control rats, release of the inhibitory neuropeptide somatostatin (SOM) was higher in females than in males. Stimulation with high concentration of KCl did not significantly change the release of SOM in control animals, while in rats treated with galcanezumab SOM release was slightly reduced. Galcanezumab treatment also reduced the amount of histamine released from dural mast cells upon stimulation with CGRP, while the effect of compound 48/80 on histamine release was not changed. CONCLUSIONS Galcanezumab treatment is followed by multiple changes in the release of neuropeptides and histamine in the trigeminal nocisensor complex, which may contribute to the migraine preventing effect of anti-CGRP antibodies. These changes affecting the communication between the components of the trigeminal nocisensor complex may reduce pain susceptibility in migraine patients treated with CGRP targeting monoclonal antibodies.
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Affiliation(s)
- Nadine Friedrich
- Department of Physiology, University of Szeged, Dóm Tér 10, 6720, Szeged, Hungary
| | - Krisztina Németh
- Chemical Biology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Krt. 2, 1117, Budapest, Hungary
| | - Martin Tanner
- Department of Physiology, University of Szeged, Dóm Tér 10, 6720, Szeged, Hungary
| | - Judit Rosta
- Department of Physiology, University of Szeged, Dóm Tér 10, 6720, Szeged, Hungary
| | - Ildikó Dobos
- Department of Physiology, University of Szeged, Dóm Tér 10, 6720, Szeged, Hungary
| | - Orsolya Oszlács
- Department of Physiology, University of Szeged, Dóm Tér 10, 6720, Szeged, Hungary
| | - Gábor Jancsó
- Department of Physiology, University of Szeged, Dóm Tér 10, 6720, Szeged, Hungary
| | - Karl Messlinger
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University, 91054, Erlangen-Nuremberg, Germany
| | - Mária Dux
- Department of Physiology, University of Szeged, Dóm Tér 10, 6720, Szeged, Hungary.
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Lee PR, Kim J, Rossi HL, Chung S, Han SY, Kim J, Oh SB. Transcriptional profiling of dental sensory and proprioceptive trigeminal neurons using single-cell RNA sequencing. Int J Oral Sci 2023; 15:45. [PMID: 37749100 PMCID: PMC10519964 DOI: 10.1038/s41368-023-00246-z] [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: 02/05/2023] [Revised: 08/30/2023] [Accepted: 08/31/2023] [Indexed: 09/27/2023] Open
Abstract
Dental primary afferent (DPA) neurons and proprioceptive mesencephalic trigeminal nucleus (MTN) neurons, located in the trigeminal ganglion and the brainstem, respectively, are essential for controlling masticatory functions. Despite extensive transcriptomic studies on various somatosensory neurons, there is still a lack of knowledge about the molecular identities of these populations due to technical challenges in their circuit-validated isolation. Here, we employed high-depth single-cell RNA sequencing (scRNA-seq) in combination with retrograde tracing in mice to identify intrinsic transcriptional features of DPA and MTN neurons. Our transcriptome analysis revealed five major types of DPA neurons with cell type-specific gene enrichment, some of which exhibit unique mechano-nociceptive properties capable of transmitting nociception in response to innocuous mechanical stimuli in the teeth. Furthermore, we discovered cellular heterogeneity within MTN neurons that potentially contribute to their responsiveness to mechanical stretch in the masseter muscle spindles. Additionally, DPA and MTN neurons represented sensory compartments with distinct molecular profiles characterized by various ion channels, receptors, neuropeptides, and mechanoreceptors. Together, our study provides new biological insights regarding the highly specialized mechanosensory functions of DPA and MTN neurons in pain and proprioception.
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Affiliation(s)
- Pa Reum Lee
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
| | - Jihoon Kim
- Genomics and Computational Biology Graduate Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Heather Lynn Rossi
- Department of Pathobiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Sena Chung
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
| | - Seung Yub Han
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Junhyong Kim
- Genomics and Computational Biology Graduate Group, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
| | - Seog Bae Oh
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea.
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Dapino A, Davoine F, Curti S. D-type K+ current rules the function of electrically coupled neurons in a species-specific fashion. J Gen Physiol 2023; 155:e202313353. [PMID: 37378665 PMCID: PMC10308032 DOI: 10.1085/jgp.202313353] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/17/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023] Open
Abstract
Electrical synapses supported by gap junctions are known to form networks of electrically coupled neurons in many regions of the mammalian brain, where they play relevant functional roles. Yet, how electrical coupling supports sophisticated network operations and the contribution of the intrinsic electrophysiological properties of neurons to these operations remain incompletely understood. Here, a comparative analysis of electrically coupled mesencephalic trigeminal (MesV) neurons uncovered remarkable difference in the operation of these networks in highly related species. While spiking of MesV neurons might support the recruitment of coupled cells in rats, this rarely occurs in mice. Using whole-cell recordings, we determined that the higher efficacy in postsynaptic recruitment in rat's MesV neurons does not result from coupling strength of larger magnitude, but instead from the higher excitability of coupled neurons. Consistently, MesV neurons from rats present a lower rheobase, more hyperpolarized threshold, as well as a higher ability to generate repetitive discharges, in comparison to their counterparts from mice. This difference in neuronal excitability results from a significantly higher magnitude of the D-type K+ current (ID) in MesV neurons from mice, indicating that the magnitude of this current gates the recruitment of postsynaptic-coupled neurons. Since MesV neurons are primary afferents critically involved in the organization of orofacial behaviors, activation of a coupled partner could support lateral excitation, which by amplifying sensory inputs may significantly contribute to information processing and the organization of motor outputs.
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Affiliation(s)
- Antonella Dapino
- Laboratorio de Neurofisiología Celular, Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Federico Davoine
- Instituto de Ingeniería Eléctrica, Facultad de Ingeniería, Universidad de la República, Montevideo, Uruguay
| | - Sebastian Curti
- Laboratorio de Neurofisiología Celular, Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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Sanz-Gálvez R, Kolta A. Different species, different gap junctions? J Gen Physiol 2023; 155:e202313430. [PMID: 37526640 PMCID: PMC10394375 DOI: 10.1085/jgp.202313430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023] Open
Abstract
By describing the analogies and differences of a simple homologous circuit involving electrical synapses—the simplest form of synaptic communication—in two closely related species, this article demonstrates how we must be wary of cross-species generalizations.
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Affiliation(s)
- Rafael Sanz-Gálvez
- Centre Interdisciplinaire de Recherche sur le Cerveau et l’Apprentissage (CIRCA), Montréal, Canada
- Department of Neurosciences, Université de Montréal, Montréal, Canada
| | - Arlette Kolta
- Centre Interdisciplinaire de Recherche sur le Cerveau et l’Apprentissage (CIRCA), Montréal, Canada
- Department of Neurosciences, Université de Montréal, Montréal, Canada
- Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montréal, Canada
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Bonini S, Di Zazzo A, Surico PL, Balzamino BO, Luccarelli V, Niutta M, Coassin M, Micera A. Inflammation and Dry Eye-like Symptoms as Concomitant Manifestations of Laryngo-Pharyngeal Reflux. Curr Eye Res 2023:1-7. [PMID: 37092761 DOI: 10.1080/02713683.2023.2207210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
PURPOSE Laryngo-pharyngeal reflux (LPR) is a common worldwide disease. LPR symptoms may involve distant organs and tissues including the ocular surface with manifestations of a Dry Eye-like disease. We evaluated the concomitant involvement of the ocular surface in patients with LPR. We also defined the clinical signs and the roles of chemical and neuro-inflammatory mediators in the tears of LPR patients. METHODS Seventy-seven patients with LPR (mean age 65.8 ± 16.8 SD) and 25 healthy controls (mean age 56.5 ± 16.3 SD) were recruited from the otorhinolaryngology unit. Each subject was evaluated for the presence of concomitant ocular surface disease through clinical examination, including the measurement of tear break-up time (TBUT) and the Ocular Surface Disease Index (OSDI) questionnaire. Tears and conjunctival imprints were collected. The presence of pepsin in tears was detected by ELISA. HLA-DR in conjunctival imprints were imaged by immunofluorescence microscopy. RT-PCR quantified conjunctival mRNA transcripts of HLA-DR, IL-8, MUC5AC, NADPH, VIP, and NPY. RESULTS Patients with LPR had significantly increased OSDI and reduced TBUT scores compared to control subjects (p < 0.05 each). Pepsin was detected in 51% of patient tears while it was not measurable in the controls (p < 0.01). Immunoreactivity for HLA-DR in the conjunctival impressions was greater than for the controls with an increased mRNA expression (p < 0.05). mRNA transcripts for IL-8, NADPH, and VIP were significantly increased in LPR patients (p < 0.05 each), but neither MUC5AC nor NPY were different from controls. CONCLUSIONS LPR can adversely affect the ocular surface, leading to moderate signs and symptoms of dry eye. This study provides evidence that the presence of pepsin, HLA-DR immunoreactivity, and increased mRNA expression of neuro-inflammatory markers in the tears and conjunctival imprints of LPR patients suggests a potential link between LPR inflammation and ocular surface disease.
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Affiliation(s)
- Stefano Bonini
- Ophthalmology Complex Operative Unit, University Campus Bio-Medico, Rome, Italy
| | - Antonio Di Zazzo
- Ophthalmology Complex Operative Unit, University Campus Bio-Medico, Rome, Italy
| | - Pier Luigi Surico
- Ophthalmology Complex Operative Unit, University Campus Bio-Medico, Rome, Italy
| | - Bijorn Omar Balzamino
- Research and Development Laboratory for Biochemical, Molecular and Cellular Applications in Ophthalmological Sciences; Research Laboratories in Ophthalmology, IRCCS - Fondazione Bietti, Rome, Italy
| | - Vitaliana Luccarelli
- Otorhinolaryngology (ENT) Complex Operative Unit, University Campus Bio-Medico, Rome, Italy
| | - Matteo Niutta
- Ophthalmology Complex Operative Unit, University Campus Bio-Medico, Rome, Italy
| | - Marco Coassin
- Ophthalmology Complex Operative Unit, University Campus Bio-Medico, Rome, Italy
| | - Alessandra Micera
- Research and Development Laboratory for Biochemical, Molecular and Cellular Applications in Ophthalmological Sciences; Research Laboratories in Ophthalmology, IRCCS - Fondazione Bietti, Rome, Italy
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Shirakawa Y, Ohno SN, Yamagata KA, Kuramoto E, Oda Y, Nakamura TJ, Nakamura W, Sugimura M. Circadian rhythm of PERIOD2::LUCIFERASE expression in the trigeminal ganglion of mice. Front Neurosci 2023; 17:1142785. [PMID: 37056311 PMCID: PMC10086191 DOI: 10.3389/fnins.2023.1142785] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 03/07/2023] [Indexed: 03/30/2023] Open
Abstract
IntroductionThe trigeminal nerve conveys delicate sensations such as warmth, pain, and tactile pressure in the oral and facial regions, and most trigeminal afferent cell bodies are located in the trigeminal ganglion. Our previous study has shown that sensations in trigeminal nerve innervated areas, specifically in the maxillofacial region, exhibit diurnal variation and that sensitivity changes time-dependently. In this study, we aimed to clarify the rhythm of expression of clock gene in the trigeminal ganglion of mice to elucidate the mechanism of circadian regulation in the same area.MethodsImmunohistochemistry examined the expression of the PER2 protein in the suprachiasmatic nucleus and trigeminal ganglion of wild-type mice. To measure gene expression as bioluminescence, PERIOD2::LUCIFERASE knock-in (PER2::LUC) mice were used. Unilateral trigeminal ganglion and brain sections including the suprachiasmatic nucleus were incubated ex vivo. Bioluminescence levels were then measured using a highly sensitive photodetector. The same experiments were then conducted with Cry1 gene-deficient (Cry1−/−) or Cry2 gene-deficient (Cry2−/−) mice.ResultsIn the trigeminal ganglion, immunohistochemistry localized PER2 protein expression within the neuronal cell body. Mouse trigeminal ganglion ex vivo tissues showed distinct circadian oscillations in PER2::LUC levels in all genotypes, wild-type, Cry1−/−, and Cry2−/−. The period was shorter in the trigeminal ganglion than in the suprachiasmatic nucleus; it was shorter in Cry1−/− and longer in Cry2−/− mice than in the wild-type mice.ConclusionThe expression of Per2 in neurons of the trigeminal ganglion in ex vivo culture and the oscillation in a distinct circadian rhythm suggests that the trigeminal ganglion is responsible for the relay of sensory inputs and temporal gating through autonomous circadian oscillations.
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Affiliation(s)
- Yukie Shirakawa
- Department of Dental Anesthesiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Sachi N. Ohno
- Department of Dental Anesthesiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
- *Correspondence: Sachi N. Ohno,
| | - Kanae A. Yamagata
- Department of Dental Anesthesiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Eriko Kuramoto
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Yoshiaki Oda
- Department of Oral Chrono-Physiology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Takahiro J. Nakamura
- Laboratory of Animal Physiology, School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan
| | - Wataru Nakamura
- Department of Oral Chrono-Physiology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Mitsutaka Sugimura
- Department of Dental Anesthesiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
- Mitsutaka Sugimura,
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KC E, Islam J, Park YS. Trigeminal ganglion itself can be a viable target to manage trigeminal neuralgia. J Headache Pain 2022; 23:150. [PMID: 36424545 PMCID: PMC9686102 DOI: 10.1186/s10194-022-01512-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 10/26/2022] [Indexed: 11/25/2022] Open
Abstract
Excruciating trigeminal neuralgia (TN) management is very difficult and severely affects the patient's quality of life. Earlier studies have shown that the trigeminal ganglion (TG) comprises several receptors and signal molecules that are involved in the process of peripheral sensitization, which influences the development and persistence of neuropathic pain. Targeting TG can modulate this sensitization pathway and mediate the pain-relieving effect. So far,there are few studies in which modulation approaches to TG itself have been suggested so far. "Trigeminal ganglion modulation" and "trigeminal neuralgia" were used as search phrases in the Scopus Index and PubMed databases to discover articles that were pertinent to the topic. In this review, we address the role of the trigeminal ganglion in TN and underlying molecules and neuropeptides implicated in trigeminal pain pathways in processing pathological orofacial pain. We also reviewed different modulation approaches in TG for TN management. Furthermore, we discuss the prospect of targeting trigeminal ganglion to manage such intractable pain.
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Affiliation(s)
- Elina KC
- grid.254229.a0000 0000 9611 0917Program in Neuroscience, Department of Medicine, College of Medicine, Chungbuk National University, Cheongju, Korea
| | - Jaisan Islam
- grid.254229.a0000 0000 9611 0917Program in Neuroscience, Department of Medicine, College of Medicine, Chungbuk National University, Cheongju, Korea
| | - Young Seok Park
- grid.254229.a0000 0000 9611 0917Program in Neuroscience, Department of Medicine, College of Medicine, Chungbuk National University, Cheongju, Korea ,grid.411725.40000 0004 1794 4809Department of Neurosurgery, Chungbuk National University Hospital, Cheongju, Korea
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Liu J, Jia S, Huang F, He H, Fan W. Peripheral role of glutamate in orofacial pain. Front Neurosci 2022; 16:929136. [PMID: 36440288 PMCID: PMC9682037 DOI: 10.3389/fnins.2022.929136] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 10/10/2022] [Indexed: 09/10/2023] Open
Abstract
Glutamate is the principal excitatory neurotransmitter in the central nervous system. In the periphery, glutamate acts as a transmitter and involves in the signaling and processing of sensory input. Glutamate acts at several types of receptors and also interacts with other transmitters/mediators under various physiological and pathophysiological conditions including chronic pain. The increasing amount of evidence suggests that glutamate may play a role through multiple mechanisms in orofacial pain processing. In this study, we reviewed the current understanding of how peripheral glutamate mediates orofacial pain, how glutamate is regulated in the periphery, and how these findings are translated into therapies for pain conditions.
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Affiliation(s)
- Jinyue Liu
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Shilin Jia
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Fang Huang
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Hongwen He
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Wenguo Fan
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
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11
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Fritzsch B, Elliott KL, Yamoah EN. Neurosensory development of the four brainstem-projecting sensory systems and their integration in the telencephalon. Front Neural Circuits 2022; 16:913480. [PMID: 36213204 PMCID: PMC9539932 DOI: 10.3389/fncir.2022.913480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/23/2022] [Indexed: 11/18/2022] Open
Abstract
Somatosensory, taste, vestibular, and auditory information is first processed in the brainstem. From the brainstem, the respective information is relayed to specific regions within the cortex, where these inputs are further processed and integrated with other sensory systems to provide a comprehensive sensory experience. We provide the organization, genetics, and various neuronal connections of four sensory systems: trigeminal, taste, vestibular, and auditory systems. The development of trigeminal fibers is comparable to many sensory systems, for they project mostly contralaterally from the brainstem or spinal cord to the telencephalon. Taste bud information is primarily projected ipsilaterally through the thalamus to reach the insula. The vestibular fibers develop bilateral connections that eventually reach multiple areas of the cortex to provide a complex map. The auditory fibers project in a tonotopic contour to the auditory cortex. The spatial and tonotopic organization of trigeminal and auditory neuron projections are distinct from the taste and vestibular systems. The individual sensory projections within the cortex provide multi-sensory integration in the telencephalon that depends on context-dependent tertiary connections to integrate other cortical sensory systems across the four modalities.
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology, The University of Iowa, Iowa City, IA, United States
- Department of Otolaryngology, The University of Iowa, Iowa City, IA, United States
- *Correspondence: Bernd Fritzsch,
| | - Karen L. Elliott
- Department of Biology, The University of Iowa, Iowa City, IA, United States
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno, NV, United States
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12
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Abstract
Headache disorders can produce recurrent, incapacitating pain. Migraine and cluster headache are notable for their ability to produce significant disability. The anatomy and physiology of headache disorders is fundamental to evolving treatment approaches and research priorities. Key concepts in headache mechanisms include activation and sensitization of trigeminovascular, brainstem, thalamic, and hypothalamic neurons; modulation of cortical brain regions; and activation of descending pain circuits. This review will examine the relevant anatomy of the trigeminal, brainstem, subcortical, and cortical brain regions and concepts related to the pathophysiology of migraine and cluster headache disorders.
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Affiliation(s)
- Andrea M Harriott
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yulia Orlova
- Department of Neurology, University of Florida, Gainesville, Florida
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13
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Noseda R. Cerebro-Cerebellar Networks in Migraine Symptoms and Headache. FRONTIERS IN PAIN RESEARCH 2022; 3:940923. [PMID: 35910262 PMCID: PMC9326053 DOI: 10.3389/fpain.2022.940923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
The cerebellum is associated with the biology of migraine in a variety of ways. Clinically, symptoms such as fatigue, motor weakness, vertigo, dizziness, difficulty concentrating and finding words, nausea, and visual disturbances are common in different types of migraine. The neural basis of these symptoms is complex, not completely known, and likely involve activation of both specific and shared circuits throughout the brain. Posterior circulation stroke, or neurosurgical removal of posterior fossa tumors, as well as anatomical tract tracing in animals, provided the first insights to theorize about cerebellar functions. Nowadays, with the addition of functional imaging, much progress has been done on cerebellar structure and function in health and disease, and, as a consequence, the theories refined. Accordingly, the cerebellum may be useful but not necessary for the execution of motor, sensory or cognitive tasks, but, rather, would participate as an efficiency facilitator of neurologic functions by improving speed and skill in performance of tasks produced by the cerebral area to which it is reciprocally connected. At the subcortical level, critical regions in these processes are the basal ganglia and thalamic nuclei. Altogether, a modulatory role of the cerebellum over multiple brain regions appears compelling, mainly by considering the complexity of its reciprocal connections to common neural networks involved in motor, vestibular, cognitive, affective, sensory, and autonomic processing—all functions affected at different phases and degrees across the migraine spectrum. Despite the many associations between cerebellum and migraine, it is not known whether this structure contributes to migraine initiation, symptoms generation or headache. Specific cerebellar dysfunction via genetically driven excitatory/inhibitory imbalances, oligemia and/or increased risk to white matter lesions has been proposed as a critical contributor to migraine pathogenesis. Therefore, given that neural projections and functions of many brainstem, midbrain and forebrain areas are shared between the cerebellum and migraine trigeminovascular pathways, this review will provide a synopsis on cerebellar structure and function, its role in trigeminal pain, and an updated overview of relevant clinical and preclinical literature on the potential role of cerebellar networks in migraine pathophysiology.
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Affiliation(s)
- Rodrigo Noseda
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
- *Correspondence: Rodrigo Noseda
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14
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Toyoda H, Won J, Kim W, Kim H, Davy O, Saito M, Kim D, Tanaka T, Kang Y, Oh SB. The Nature of Noradrenergic Volume Transmission From Locus Coeruleus to Brainstem Mesencephalic Trigeminal Sensory Neurons. Front Cell Neurosci 2022; 16:841239. [PMID: 35558874 PMCID: PMC9087804 DOI: 10.3389/fncel.2022.841239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Noradrenergic neurons in the locus coeruleus (LC) release noradrenaline (NA) that acts via volume transmission to activate extrasynaptic G-protein coupled receptors (GPCRs) in target cells throughout the brain. As the closest projection, the dorsal LC laterally adjoins the mesencephalic trigeminal nucleus (MTN), in which proprioceptive primary sensory neurons innervating muscle spindles of jaw-closing muscles are exceptionally located. MTN neurons express α2-adrenergic receptors (α2-ARs) and display hyperpolarization-activated cyclic nucleotide-gated (HCN) currents (Ihs), which is downregulated by α2-AR activation. To quantify the activity-dependent outcome of volume transmission of NA from LC to MTN, we investigated how direct LC activation inhibits Ih in MTN neurons by performing dual whole-cell recordings from LC and MTN neurons. Repetition of 20 Hz spike-train evoked with 1-s current-pulse in LC neurons every 30 s resulted in a gradual decrease in Ih evoked every 30 s, revealing a Hill-type relationship between the number of spike-trains in LC neurons and the degree of Ih inhibition in MTN neurons. On the other hand, when microstimulation was applied in LC every 30 s, an LC neuron repeatedly displayed a transient higher-frequency firing followed by a tonic firing at 5–10 Hz for 30 s. This subsequently caused a similar Hill-type inhibition of Ih in the simultaneously recorded MTN neuron, but with a smaller Hill coefficient, suggesting a lower signal transduction efficacy. In contrast, 20 Hz activity induced by a 1-s pulse applied every 5–10 s caused only a transient facilitation of Ih inhibition followed by a forced termination of Ih inhibition. Thus, the three modes of LC activities modulated the volume transmission to activate α2-adrenergic GPCR to differentially inhibit Ih in MTN neurons.
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Affiliation(s)
- Hiroki Toyoda
- Department of Neuroscience and Oral Physiology, Graduate School of Dentistry, Osaka University, Suita, Japan
| | - Jonghwa Won
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, South Korea
| | - Wheedong Kim
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea
| | - Hayun Kim
- Interdisciplinary Program for Brain Science, College of Natural Sciences, Seoul National University, Seoul, South Korea
| | - Oscar Davy
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Mitsuru Saito
- Department of Oral Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Doyun Kim
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, South Korea
| | - Takuma Tanaka
- Graduate School of Data Science, Shiga University, Hikone, Japan
| | - Youngnam Kang
- Department of Neuroscience and Oral Physiology, Graduate School of Dentistry, Osaka University, Suita, Japan
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, South Korea
- Department of Behavioral Sciences, Graduate School of Human Sciences, Osaka University, Suita, Japan
| | - Seog Bae Oh
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea
- Department of Neurobiology and Physiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, South Korea
- Interdisciplinary Program for Brain Science, College of Natural Sciences, Seoul National University, Seoul, South Korea
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15
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Zhao YJ, Liu Y, Wang J, Li Q, Zhang ZM, Tu T, Lei R, Zhang M, Chen YJ. Activation of the Mesencephalic Trigeminal Nucleus Contributes to Masseter Hyperactivity Induced by Chronic Restraint Stress. Front Cell Neurosci 2022; 16:841133. [PMID: 35480958 PMCID: PMC9035558 DOI: 10.3389/fncel.2022.841133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 03/11/2022] [Indexed: 12/12/2022] Open
Abstract
Psychological stress is commonly accepted to be closely associated with masticatory muscle disorder, which is the main symptom of temporomandibular disorder (TMD). Previous studies have confirmed that exposure to stress may cause masticatory muscle hyperactivity. However, the central mechanism underlying this process remains unclear. The mesencephalic trigeminal nucleus (Vme), which resides in the brainstem, is the primary afferent center for masticatory proprioception and plays a key role in oral–motor movements by projecting to the trigeminal motor nucleus (Vmo). Therefore, the present study was designed to examine the role of Vme neurons in masseter overactivity induced by chronic stress. We found that subjecting mice to restraint stress (6 h/day) for 14 days caused significant anxiety-like behavior, obvious masseter overactivity, and markedly enhanced electrophysiological excitability of Vme neurons. By using anterograde tract tracing combined with immunofluorescence staining methods, we observed vesicular glutamate transporter 1 (VGLUT1)-positive glutamatergic projections from the Vme to the Vmo. Moreover, chronic restraint stress (CRS) elevated the expression of VGLUT1 and choline acetyltransferase (ChAT) in Vmo. Furthermore, administration of VGLUT1-targeted short hairpin RNA (shRNA) into the bilateral Vme significantly suppressed the enhanced overexcitability of Vme neurons, downregulated the overexpression of VGLUT1 and ChAT in the Vmo, and attenuated the elevated overactivity of the masseter caused by CRS. Taken together, we showed that CRS can excite neurons in the Vme, enhancing glutamatergic excitatory projections from the Vme to the Vmo and resulting in masseter muscle overactivity. These findings provide us with a novel central mechanism underlying the correlation between psychological factors and TMD.
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Affiliation(s)
- Ya-Juan Zhao
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi’an, China
| | - Yang Liu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi’an, China
| | - Jian Wang
- Department of Cardiothoracic Surgery, General Hospital of Western Theater Command, Chengdu, China
| | - Qiang Li
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi’an, China
| | - Zhou-Ming Zhang
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi’an, China
| | - Teng Tu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi’an, China
| | - Rong Lei
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi’an, China
| | - Min Zhang
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi’an, China
- Min Zhang,
| | - Yong-Jin Chen
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi’an, China
- *Correspondence: Yong-Jin Chen,
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16
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Peripheral Purinergic Modulation in Pediatric Orofacial Inflammatory Pain Affects Brainstem Nitroxidergic System: A Translational Research. BIOMED RESEARCH INTERNATIONAL 2022; 2022:1326885. [PMID: 35309172 PMCID: PMC8933089 DOI: 10.1155/2022/1326885] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/19/2022] [Accepted: 01/22/2022] [Indexed: 11/18/2022]
Abstract
Physiology of orofacial pain pathways embraces primary afferent neurons, pathologic changes in the trigeminal ganglion, brainstem nociceptive neurons, and higher brain function regulating orofacial nociception. The goal of this study was to investigate the nitroxidergic system alteration at brainstem level (spinal trigeminal nucleus), and the role of peripheral P2 purinergic receptors in an experimental mouse model of pediatric inflammatory orofacial pain, to increase knowledge and supply information concerning orofacial pain in children and adolescents, like pediatric dentists and pathologists, as well as oro-maxillo-facial surgeons, may be asked to participate in the treatment of these patients. The experimental animals were treated subcutaneously in the perioral region with pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS), a P2 receptor antagonist, 30 minutes before formalin injection. The pain-related behavior and the nitroxidergic system alterations in the spinal trigeminal nucleus using immunohistochemistry and western blotting analysis have been evaluated. The local administration of PPADS decreased the face-rubbing activity and the expression of both neuronal and inducible nitric oxide (NO) synthase isoforms in the spinal trigeminal nucleus. These results underline a relationship between orofacial inflammatory pain and nitroxidergic system in the spinal trigeminal nucleus and suggest a role of peripheral P2 receptors in trigeminal pain transmission influencing NO production at central level. In this way, orofacial pain physiology should be elucidated and applied to clinical practice in the future.
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17
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Turk AZ, Bishop M, Adeck A, SheikhBahaei S. Astrocytic modulation of central pattern generating motor circuits. Glia 2022; 70:1506-1519. [PMID: 35212422 DOI: 10.1002/glia.24162] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 12/26/2022]
Abstract
Central pattern generators (CPGs) generate the rhythmic and coordinated neural features necessary for the proper conduction of complex behaviors. In particular, CPGs are crucial for complex motor behaviors such as locomotion, mastication, respiration, and vocal production. While the importance of these networks in modulating behavior is evident, the mechanisms driving these CPGs are still not fully understood. On the other hand, accumulating evidence suggests that astrocytes have a significant role in regulating the function of some of these CPGs. Here, we review the location, function, and role of astrocytes in locomotion, respiration, and mastication CPGs and propose that, similarly, astrocytes may also play a significant role in the vocalization CPG.
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Affiliation(s)
- Ariana Z Turk
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Mitchell Bishop
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Afuh Adeck
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Shahriar SheikhBahaei
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, Maryland, USA
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18
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Tear film and ocular surface neuropeptides: Characteristics, synthesis, signaling and implications for ocular surface and systemic diseases. Exp Eye Res 2022; 218:108973. [PMID: 35149082 DOI: 10.1016/j.exer.2022.108973] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 12/14/2021] [Accepted: 02/01/2022] [Indexed: 01/13/2023]
Abstract
Ocular surface neuropeptides are vital molecules primarily involved in maintaining ocular surface integrity and homeostasis. They also serve as communication channels between the nervous system and the immune system, maintaining the homeostasis of the ocular surface. Tear film and ocular surface neuropeptides have a role in disease often due to abnormalities in their synthesis (either high or low production), signaling through defective receptors, or both. This creates imbalances in otherwise normal physiological processes. They have been observed to be altered in many ocular surface and systemic diseases including dry eye disease, ocular allergy, keratoconus, LASIK-induced dry eye, pterygium, neurotrophic keratitis, corneal graft rejection, microbial keratitis, headaches and diabetes. This review examines the characteristics of neuropeptides, their synthesis and their signaling through G-protein coupled receptors. The review also explores the types of neuropeptides within the tears and ocular surface, and how they change in ocular and systemic diseases.
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19
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Melo-Carrillo A, Strassman AM, Schain AJ, Broide RS, Cai BB, Rhéaume C, Brideau-Andersen AD, Ashina S, Flores-Montanez Y, Brin MF, Burstein R. OnabotulinumtoxinA affects cortical recovery period but not occurrence or propagation of cortical spreading depression in rats with compromised blood-brain barrier. Pain 2021; 162:2418-2427. [PMID: 34448754 PMCID: PMC8374711 DOI: 10.1097/j.pain.0000000000002230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 01/11/2021] [Accepted: 02/01/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT OnabotulinumtoxinA (BoNT-A) is an Food and Drug Administration-approved, peripherally acting preventive migraine drug capable of inhibiting meningeal nociceptors. Expanding our view of how else this neurotoxin attenuates the activation of the meningeal nociceptors, we reasoned that if the stimulus that triggers the activation of the nociceptor is lessened, the magnitude and/or duration of the nociceptors' activation could diminish as well. In the current study, we further examine this possibility using electrocorticogram recording techniques, immunohistochemistry, and 2-photon microscopy. We report (1) that scalp (head) but not lumbar (back) injections of BoNT-A shorten the period of profound depression of spontaneous cortical activity that follows a pinprick-induced cortical spreading depression (CSD); (2) that neither scalp nor lumbar injections prevent the induction, occurrence, propagation, or spreading velocity of a single wave of CSD; (3) that cleaved SNAP25-one of the most convincing tools to determine the anatomical targeting of BoNT-A treatment-could easily be detected in pericranial muscles at the injection sites and in nerve fibers of the intracranial dura, but not within any cortical area affected by the CSD; (4) that the absence of cleaved SNAP25 within the cortex and pia is unrelated to whether the blood-brain barrier is intact or compromised; and (5) that BoNT-A does not alter vascular responses to CSD. To the best of our knowledge, this is the first report of peripherally applied BoNT-A's ability to alter a neuronal function along a central nervous system pathway involved in the pathophysiology of migraine.
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Affiliation(s)
- Agustin Melo-Carrillo
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston MA, United States
- Department of Anesthesia, Harvard Medical School, Boston MA, United States
| | - Andrew M. Strassman
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston MA, United States
- Department of Anesthesia, Harvard Medical School, Boston MA, United States
| | - Aaron J. Schain
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston MA, United States
- Department of Anesthesia, Harvard Medical School, Boston MA, United States
| | - Ron S. Broide
- Allergan, an AbbVie Company, Irvine, CA, United States
| | - Brian B. Cai
- Allergan, an AbbVie Company, Irvine, CA, United States
| | | | | | - Sait Ashina
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston MA, United States
- Department of Anesthesia, Harvard Medical School, Boston MA, United States
| | - Yadira Flores-Montanez
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston MA, United States
- Department of Anesthesia, Harvard Medical School, Boston MA, United States
| | - Mitchell F. Brin
- Allergan, an AbbVie Company, Irvine, CA, United States
- University of California, Irvine, United States
| | - Rami Burstein
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston MA, United States
- Department of Anesthesia, Harvard Medical School, Boston MA, United States
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20
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Chuinsiri N, Edwards D, Telezhkin V, Nile CJ, Van der Cruyssen F, Durham J. Exploring the roles of neuropeptides in trigeminal neuropathic pain: A systematic review and narrative synthesis of animal studies. Arch Oral Biol 2021; 130:105247. [PMID: 34454375 DOI: 10.1016/j.archoralbio.2021.105247] [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: 06/14/2021] [Revised: 08/02/2021] [Accepted: 08/22/2021] [Indexed: 12/09/2022]
Abstract
OBJECTIVE This systematic review aims to explore the changes in expression of neuropeptides and/or their receptors following experimental trigeminal neuropathic pain in animals. DESIGN MEDLINE, Embase, and Scopus were searched for publications up to 31st March 2021. Study selection and data extraction were completed by two independent reviewers based on the eligibility criteria. The quality of articles was judged based on the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk-of-bias tool. RESULTS A total of 19 studies satisfied the eligibility criteria and were included for narrative synthesis. Methods of trigeminal neuropathic pain induction were nerve ligation, nerve compression/crush, nerve transection and dental pulp injury. Animal behaviours used for pain verification were evoked responses to mechanical and thermal stimuli. Non-evoked behaviours, including vertical exploration, grooming and food consumption, were also employed in some studies. Calcitonin gene-related peptide (CGRP) and substance P were the most frequently reported neuropeptides. Overall, unclear to high risk of bias was identified in the included studies. CONCLUSIONS Limited evidence has suggested the pro-nociceptive role of CGRP in trigeminal neuropathic pain. In order to further translational pain research, animal models of trigeminal neuropathic pain and pain validation methods need to be optimised. Complete reporting of future studies based on available guidelines to improve confidence in research is encouraged.
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Affiliation(s)
- Nontawat Chuinsiri
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
| | - David Edwards
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Vsevolod Telezhkin
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Christopher J Nile
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Fréderic Van der Cruyssen
- Department of Oral and Maxillofacial Surgery, University Hospitals Leuven, Leuven, Belgium; OMFS-IMPATH Research Group, Department of Imaging and Pathology, Faculty of Medicine, University Leuven, Leuven, Belgium
| | - Justin Durham
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
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21
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Zheng DJ, Singh A, Phelps SM. Conservation and dimorphism in androgen receptor distribution in Alston's singing mouse (Scotinomys teguina). J Comp Neurol 2021; 529:2539-2557. [PMID: 33576501 DOI: 10.1002/cne.25108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 12/25/2020] [Accepted: 12/28/2020] [Indexed: 12/19/2022]
Abstract
Because of their roles in courtship and intrasexual competition, sexual displays are often sexually dimorphic, but we know little about the mechanisms that produce such dimorphism. Among mammals, one example is the vocalization of Alston's singing mouse (Scotinomys teguina), which consists of a series of rapidly repeated, frequency-modulated notes. The rate and duration of songs is sexually dimorphic and androgen responsive. To understand the neuronal mechanisms underlying this sexual dimorphism, we map the sites of androgen sensitivity throughout the brain, focusing analysis along a pathway that spans from limbic structures to vocal motor regions. We find widespread expression of AR immunoreactivity (AR-ir) throughout limbic structures important for social behavior and vocalization, including the lateral septum, extended amygdala, preoptic area and hypothalamus. We also find extensive AR staining along previously documented vocal motor pathways, including the periaqueductal gray, parabrachial nucleus, and nucleus ambiguus, the last of which innervates intrinsic laryngeal muscles. Lastly, AR-ir is also evident in sensory areas such as the medial geniculate, inferior, and superior colliculi. A quantitative analysis revealed that males exhibited more AR-ir than females, a pattern that was most pronounced in the hypothalamus. Despite the elaboration of vocalization in singing mice, comparison with prior literature suggests that the broad pattern of AR-ir may be conserved across a wide range of rodents. Together these data identify brain nuclei well positioned to shape the sexually dimorphic vocalization of S. teguina and suggest that such androgen modulation of vocalization is evolutionary conserved among rodents.
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Affiliation(s)
- Da-Jiang Zheng
- Department of Integrative Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Aditi Singh
- Department of Integrative Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Steven M Phelps
- Department of Integrative Biology, The University of Texas at Austin, Austin, Texas, USA
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22
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Benbow T, Cairns BE. Dysregulation of the peripheral glutamatergic system: A key player in migraine pathogenesis? Cephalalgia 2021; 41:1249-1261. [PMID: 34148407 PMCID: PMC8504403 DOI: 10.1177/03331024211017882] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Background Although the role of glutamate in migraine pathogenesis remains uncertain, there has been significant interest in the development of drug candidates that target glutamate receptors. Activation of trigeminovascular afferent fibers is now recognized as a crucial step to the onset of a migraine episode. New evidence suggests a dysfunction in peripheral glutamate regulation may play a role in this process. Objective To provide a narrative review of the role of peripheral glutamate dysfunction in migraine. Method A review of recent literature from neurobiological, pharmacological and genomic studies was conducted to support peripheral glutamate dysfunction as a potential element in migraine pathogenesis. Results Studies in rats suggest that elevated blood glutamate mechanically sensitizes trigeminal afferent fibers and stimulates the release of calcitonin-gene related peptide and other neuropeptides to promote and maintain neurogenic inflammation. These effects may be driven by upregulation of glutamate receptors, and modifications to reuptake and metabolic pathways of glutamate. Furthermore, genome wide association studies have found polymorphisms in glutamate receptor and transporter genes that are associated with migraine. Conclusion The role of peripheral glutamate signalling in the onset and maintenance of migraine is not completely elucidated and future studies are still needed to confirm its role in migraine pathogenesis.
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Affiliation(s)
- Tarique Benbow
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
| | - Brian E Cairns
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
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23
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Fortin SM, Chen J, Grill HJ, Hayes MR. The Mesencephalic Trigeminal Nucleus Controls Food Intake and Body Weight via Hindbrain POMC Projections. Nutrients 2021; 13:nu13051642. [PMID: 34068091 PMCID: PMC8152732 DOI: 10.3390/nu13051642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 04/30/2021] [Accepted: 05/10/2021] [Indexed: 12/20/2022] Open
Abstract
The mesencephalic trigeminal nucleus (Mes5) processes oral sensory–motor information, but its role in the control of energy balance remains unexplored. Here, using fluorescent in situ hybridization, we show that the Mes5 expresses the melanocortin-4 receptor. Consistent with MC4R activation in other areas of the brain, we found that Mes5 microinjection of the MC4R agonist melanotan-II (MTII) suppresses food intake and body weight in the mouse. Furthermore, NTS POMC-projecting neurons to the Mes5 can be chemogenetically activated to drive a suppression in food intake. Taken together, these findings highlight the Mes5 as a novel target of melanocortinergic control of food intake and body weight regulation, although elucidating the endogenous role of this circuit requires future study. While we observed the sufficiency of Mes5 MC4Rs for food intake and body weight suppression, these receptors do not appear to be necessary for food intake or body weight control. Collectively, the data presented here support the functional relevance of the NTS POMC to Mes5 projection pathway as a novel circuit that can be targeted to modulate food intake and body weight.
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Affiliation(s)
- Samantha M. Fortin
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.F.); (J.C.)
| | - Jack Chen
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.F.); (J.C.)
| | - Harvey J. Grill
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA;
| | - Matthew R. Hayes
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.F.); (J.C.)
- Correspondence:
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24
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Duarte LF, Reyes A, Farías MA, Riedel CA, Bueno SM, Kalergis AM, González PA. Crosstalk Between Epithelial Cells, Neurons and Immune Mediators in HSV-1 Skin Infection. Front Immunol 2021; 12:662234. [PMID: 34012447 PMCID: PMC8126613 DOI: 10.3389/fimmu.2021.662234] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 04/06/2021] [Indexed: 12/12/2022] Open
Abstract
Herpes simplex virus type 1 (HSV-1) infection is highly prevalent in humans, with approximately two-thirds of the world population living with this virus. However, only a fraction of those carrying HSV-1, which elicits lifelong infections, are symptomatic. HSV-1 mainly causes lesions in the skin and mucosae but reaches the termini of sensory neurons innervating these tissues and travels in a retrograde manner to the neuron cell body where it establishes persistent infection and remains in a latent state until reactivated by different stimuli. When productive reactivations occur, the virus travels back along axons to the primary infection site, where new rounds of replication are initiated in the skin, in recurrent or secondary infections. During this process, new neuron infections occur. Noteworthy, the mechanisms underlying viral reactivations and the exit of latency are somewhat poorly understood and may be regulated by a crosstalk between the infected neurons and components of the immune system. Here, we review and discuss the immune responses that occur at the skin during primary and recurrent infections by HSV-1, as well as at the interphase of latently-infected neurons. Moreover, we discuss the implications of neuronal signals over the priming and migration of immune cells in the context of HSV-1 infection.
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Affiliation(s)
- Luisa F Duarte
- Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Antonia Reyes
- Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mónica A Farías
- Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Claudia A Riedel
- Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Susan M Bueno
- Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexis M Kalergis
- Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Endocrinología, Facultad de Medicina, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pablo A González
- Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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25
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Dhar A, Kuramoto E, Fukushima M, Iwai H, Yamanaka A, Goto T. The Periodontium Damage Induces Neuronal Cell Death in the Trigeminal Mesencephalic Nucleus and Neurodegeneration in the Trigeminal Motor Nucleus in C57BL/6J Mice. Acta Histochem Cytochem 2021; 54:11-19. [PMID: 33731966 PMCID: PMC7947638 DOI: 10.1267/ahc.20-00036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 01/14/2021] [Indexed: 11/22/2022] Open
Abstract
Proprioception from masticatory apparatus and periodontal ligaments comes through the trigeminal mesencephalic nucleus (Vmes). We evaluated the effects of tooth loss on neurodegeneration of the Vmes and trigeminal motor nucleus (Vmo). Bilateral maxillary molars of 2-month-old C57BL/6J mice were extracted under anesthesia. Neural projections of the Vmes to the periodontium were confirmed by injecting Fluoro-Gold (FG) retrogradely into the extraction sockets, and for the anterograde labeling adeno-associated virus encoding green fluorescent protein (AAV-GFP) was applied. For immunohistochemistry, Piezo2, ATF3, Caspase 3, ChAT and TDP-43 antibodies were used. At 1 month after tooth extraction, the number of Piezo2-immunoreactive (IR) Vmes neurons were decreased significantly. ATF3-IR neurons were detected on day 5 after tooth extraction. Dead cleaved caspase-3-IR neurons were found among Vmes neurons on days 7 and 12. In the Vmo, neuronal cytoplasmic inclusions (NCIs) formation type of TDP-43 increased at 1 and 2 months after extraction. These indicate the existence of neural projections from the Vmes to the periodontium in mice and that tooth loss induces the death of Vmes neurons followed by TDP-43 pathology in the Vmo. Therefore, tooth loss induces Vmes neuronal cell death, causing Vmo neurodegeneration and presumably affecting masticatory function.
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Affiliation(s)
- Ashis Dhar
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University
| | - Eriko Kuramoto
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University
| | - Makoto Fukushima
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University
| | - Haruki Iwai
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University
| | - Atsushi Yamanaka
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University
| | - Tetsuya Goto
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University
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26
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Burns TF, Rajan R. Sensing and processing whisker deflections in rodents. PeerJ 2021; 9:e10730. [PMID: 33665005 PMCID: PMC7906041 DOI: 10.7717/peerj.10730] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/17/2020] [Indexed: 11/20/2022] Open
Abstract
The classical view of sensory information mainly flowing into barrel cortex at layer IV, moving up for complex feature processing and lateral interactions in layers II and III, then down to layers V and VI for output and corticothalamic feedback is becoming increasingly undermined by new evidence. We review the neurophysiology of sensing and processing whisker deflections, emphasizing the general processing and organisational principles present along the entire sensory pathway—from the site of physical deflection at the whiskers to the encoding of deflections in the barrel cortex. Many of these principles support the classical view. However, we also highlight the growing number of exceptions to these general principles, which complexify the system and which investigators should be mindful of when interpreting their results. We identify gaps in the literature for experimentalists and theorists to investigate, not just to better understand whisker sensation but also to better understand sensory and cortical processing.
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Affiliation(s)
- Thomas F Burns
- Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Ramesh Rajan
- Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
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27
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Iwata K, Sessle BJ. The Evolution of Neuroscience as a Research Field Relevant to Dentistry. J Dent Res 2020; 98:1407-1417. [PMID: 31746682 DOI: 10.1177/0022034519875724] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The field of neuroscience did not exist as such when the Journal of Dental Research was founded 100 y ago. It has emerged as an important scientific field relevant to dentistry in view of the many neurally based functions manifested in the orofacial area (e.g., pain, taste, chewing, swallowing, salivation). This article reviews many of the novel insights that have been gained through neuroscience research into the neural basis of these functions and their clinical relevance to the diagnosis and management of pain and sensorimotor disorders. These include the neural pathways and brain circuitry underlying each of these functions and the role of nonneural as well as neural processes and their "plasticity" in modulating these functions and allowing for adaptation to tissue injury and pain and for learning or rehabilitation of orofacial functions.
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Affiliation(s)
- K Iwata
- Department of Physiology, Nihon University, School of Dentistry, Tokyo, Japan
| | - B J Sessle
- Faculty of Dentistry and Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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28
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Lázár BA, Jancsó G, Sántha P. Modulation of Sensory Nerve Function by Insulin: Possible Relevance to Pain, Inflammation and Axon Growth. Int J Mol Sci 2020; 21:E2507. [PMID: 32260335 PMCID: PMC7177741 DOI: 10.3390/ijms21072507] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 03/31/2020] [Accepted: 04/02/2020] [Indexed: 12/16/2022] Open
Abstract
Insulin, besides its pivotal role in energy metabolism, may also modulate neuronal processes through acting on insulin receptors (InsRs) expressed by neurons of both the central and the peripheral nervous system. Recently, the distribution and functional significance of InsRs localized on a subset of multifunctional primary sensory neurons (PSNs) have been revealed. Systematic investigations into the cellular electrophysiology, neurochemistry and morphological traits of InsR-expressing PSNs indicated complex functional interactions among specific ion channels, proteins and neuropeptides localized in these neurons. Quantitative immunohistochemical studies have revealed disparate localization of the InsRs in somatic and visceral PSNs with a dominance of InsR-positive neurons innervating visceral organs. These findings suggested that visceral spinal PSNs involved in nociceptive and inflammatory processes are more prone to the modulatory effects of insulin than somatic PSNs. Co-localization of the InsR and transient receptor potential vanilloid 1 (TRPV1) receptor with vasoactive neuropeptides calcitonin gene-related peptide and substance P bears of crucial importance in the pathogenesis of inflammatory pathologies affecting visceral organs, such as the pancreas and the urinary bladder. Recent studies have also revealed significant novel aspects of the neurotrophic propensities of insulin with respect to axonal growth, development and regeneration.
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Affiliation(s)
| | - Gábor Jancsó
- Department of Physiology, University of Szeged, H-6720 Szeged, Hungary; (G.J.); (P.S.)
| | - Péter Sántha
- Department of Physiology, University of Szeged, H-6720 Szeged, Hungary; (G.J.); (P.S.)
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29
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Cross-talk signaling in the trigeminal ganglion: role of neuropeptides and other mediators. J Neural Transm (Vienna) 2020; 127:431-444. [PMID: 32088764 PMCID: PMC7148261 DOI: 10.1007/s00702-020-02161-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 02/12/2020] [Indexed: 11/08/2022]
Abstract
The trigeminal ganglion with its three trigeminal nerve tracts consists mainly of clusters of sensory neurons with their peripheral and central processes. Most neurons are surrounded by satellite glial cells and the axons are wrapped by myelinating and non-myelinating Schwann cells. Trigeminal neurons express various neuropeptides, most notably, calcitonin gene-related peptide (CGRP), substance P, and pituitary adenylate cyclase-activating polypeptide (PACAP). Two types of CGRP receptors are expressed in neurons and satellite glia. A variety of other signal molecules like ATP, nitric oxide, cytokines, and neurotrophic factors are released from trigeminal ganglion neurons and signal to neighboring neurons or satellite glial cells, which can signal back to neurons with same or other mediators. This potential cross-talk of signals involves intracellular mechanisms, including gene expression, that can modulate mediators of sensory information, such as neuropeptides, receptors, and neurotrophic factors. From the ganglia cell bodies, which are outside the blood–brain barrier, the mediators are further distributed to peripheral sites and/or to the spinal trigeminal nucleus in the brainstem, where they can affect neural transmission. A major question is how the sensory neurons in the trigeminal ganglion differ from those in the dorsal root ganglion. Despite their functional overlap, there are distinct differences in their ontogeny, gene expression, signaling pathways, and responses to anti-migraine drugs. Consequently, drugs that modulate cross-talk in the trigeminal ganglion can modulate both peripheral and central sensitization, which may potentially be distinct from sensitization mediated in the dorsal root ganglion.
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30
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Matsuka Y, Afroz S, Dalanon JC, Iwasa T, Waskitho A, Oshima M. The role of chemical transmitters in neuron-glia interaction and pain in sensory ganglion. Neurosci Biobehav Rev 2020; 108:393-399. [DOI: 10.1016/j.neubiorev.2019.11.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 09/20/2019] [Accepted: 11/25/2019] [Indexed: 01/10/2023]
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31
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Yuan H, Silberstein SD. The Use of Botulinum Toxin in the Management of Headache Disorders. Handb Exp Pharmacol 2020; 263:227-249. [PMID: 32562057 DOI: 10.1007/164_2020_365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Tremendous progress has been made in the past decades for the treatment of headache disorders. Chronic migraine is the most disabling type of headache and requires the use of acute and preventive medications, many of which are associated with adverse events that limit patient adherence. Botulinum toxin (BoNT) serotype A, a neurotoxin derived from certain strains of Clostridium, disrupts neuropeptide secretion and receptor translocation related to trigeminal nociception, thereby preventing pain sensitization through peripheral and possibly central mechanisms. Ever since the first randomized controlled trial on onabotulinumtoxinA (onabotA) for migraine was published two decades ago, onabotA has been the only BoNT formulation approved for use in the prevention of chronic migraine. Superior tolerability and efficacy have been demonstrated on multiple migraine endpoints in many controlled trials and real-life studies. OnabotA is a safe and efficacious treatment for chronic migraine and possibly high-frequency episodic migraine. Further research is still needed to understand its mechanism of action to fully develop its therapeutic potential.
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Affiliation(s)
- Hsiangkuo Yuan
- Jefferson Headache Center, Thomas Jefferson University, Philadelphia, PA, USA
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32
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The contribution of orexin receptors within the ventral tegmental area to modulation of antinociception induced by chemical stimulation of the lateral hypothalamus in the animal model of orofacial pain in the rats. Behav Pharmacol 2019; 31:500-509. [DOI: 10.1097/fbp.0000000000000531] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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33
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Propargylglycine decreases neuro-immune interaction inducing pain response in temporomandibular joint inflammation model. Nitric Oxide 2019; 93:90-101. [DOI: 10.1016/j.niox.2019.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 09/22/2019] [Accepted: 10/02/2019] [Indexed: 12/20/2022]
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34
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Dagistan Y, Kilinc E, Balci CN. Cervical sympathectomy modulates the neurogenic inflammatory neuropeptides following experimental subarachnoid hemorrhage in rats. Brain Res 2019; 1722:146366. [DOI: 10.1016/j.brainres.2019.146366] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 08/06/2019] [Accepted: 08/07/2019] [Indexed: 01/28/2023]
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35
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Circuit-Specific Early Impairment of Proprioceptive Sensory Neurons in the SOD1 G93A Mouse Model for ALS. J Neurosci 2019; 39:8798-8815. [PMID: 31530644 DOI: 10.1523/jneurosci.1214-19.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/24/2019] [Accepted: 09/02/2019] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which motor neurons degenerate, resulting in muscle atrophy, paralysis, and fatality. Studies using mouse models of ALS indicate a protracted period of disease development with progressive motor neuron pathology, evident as early as embryonic and postnatal stages. Key missing information includes concomitant alterations in the sensorimotor circuit essential for normal development and function of the neuromuscular system. Leveraging unique brainstem circuitry, we show in vitro evidence for reflex circuit-specific postnatal abnormalities in the jaw proprioceptive sensory neurons in the well-studied SOD1G93A mouse. These include impaired and arrhythmic action potential burst discharge associated with a deficit in Nav1.6 Na+ channels. However, the mechanoreceptive and nociceptive trigeminal ganglion neurons and the visual sensory retinal ganglion neurons were resistant to excitability changes in age-matched SOD1G93A mice. Computational modeling of the observed disruption in sensory patterns predicted asynchronous self-sustained motor neuron discharge suggestive of imminent reflexive defects, such as muscle fasciculations in ALS. These results demonstrate a novel reflex circuit-specific proprioceptive sensory abnormality in ALS.SIGNIFICANCE STATEMENT Neurodegenerative diseases have prolonged periods of disease development and progression. Identifying early markers of vulnerability can therefore help devise better diagnostic and treatment strategies. In this study, we examined postnatal abnormalities in the electrical excitability of muscle spindle afferent proprioceptive neurons in the well-studied SOD1G93A mouse model for neurodegenerative motor neuron disease, amyotrophic lateral sclerosis. Our findings suggest that these proprioceptive sensory neurons are exclusively afflicted early in the disease process relative to sensory neurons of other modalities. Moreover, they presented Nav1.6 Na+ channel deficiency, which contributed to arrhythmic burst discharge. Such sensory arrhythmia could initiate reflexive defects, such as muscle fasciculations in amyotrophic lateral sclerosis, as suggested by our computational model.
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36
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Epstein JB, Miaskowski C. Oral Pain in the Cancer Patient. J Natl Cancer Inst Monogr 2019; 2019:5551353. [DOI: 10.1093/jncimonographs/lgz003] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/07/2019] [Accepted: 04/01/2019] [Indexed: 01/02/2023] Open
Abstract
Abstract
Oral pain due to cancer and associated treatments is common. The prevalence and severity of oral cancer is high. Painful oral mucositis develops in head and neck cancer patients following surgery and associated radiation therapy and/or chemotherapy. In addition, oral pain, including pain from mucositis, occurs in patients receiving chemotherapy for cancers of the hematopoietic system and cancers at other anatomic sites. Despite pain management practices that include high-dose opioid analgesics, patients rarely obtain relief from either head and neck cancer pain or mucositis pain. Because oral pain in cancer patients is likely due to both nociceptive and neuropathic mechanisms, effective management of pain requires treatments for both processes. As knowledge of the pathophysiology of oral pain in cancer patients increases, new approaches for the prevention and management are anticipated. This article focuses on the emerging evidence that supports the molecular mechanisms and the unique oral micro-neuroanatomy that in combination produce the severe oral pain experienced by cancer patients. In addition, this article summarizes the current state of clinical management of oral mucositis pain.
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Affiliation(s)
- Joel B Epstein
- Department of Surgery, City of Hope, Duarte, CA
- Department of Surgery, Cedars-Sinai Health System, Los Angeles, CA
- Seattle Cancer Care Alliance, Seattle, WA
| | - Christine Miaskowski
- Department of Physiological Nursing, University of California San Francisco, San Francisco, CA
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37
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Liu X, Zhou KX, Yin NN, Zhang CK, Shi MH, Zhang HY, Wang DM, Xu ZJ, Zhang JD, Li JL, Wang MQ. Malocclusion Generates Anxiety-Like Behavior Through a Putative Lateral Habenula-Mesencephalic Trigeminal Nucleus Pathway. Front Mol Neurosci 2019; 12:174. [PMID: 31427925 PMCID: PMC6689965 DOI: 10.3389/fnmol.2019.00174] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 07/01/2019] [Indexed: 01/06/2023] Open
Abstract
Malocclusion is an important risk factor for temporomandibular disorder (TMD), a series of disorders characterized by dysfunction in the orofacial region involving the temporomandibular joint (TMJ) and jaw muscles. We recently showed that experimental unilateral anterior crossbite (UAC) produced masseter hyperactivity through a circuit involving the periodontal proprioception, trigeminal mesencephalic nucleus (Vme), and trigeminal motor nucleus (Vmo). Anxiety is a common complication in patients with TMD. The lateral habenula (LHb) is involved in emotional modulation and has direct projections to the Vme. Therefore, the present research examined whether UAC facilitates excitatory input from the LHb to the Vme and, subsequently, anxiety-like behaviors in rats. The LHb activation was evaluated by the electrophysiological recording, assessment of vesicular glutamate transporter-2 (VGLUT2) mRNA expression, and measurement of anxiety-like behaviors. The effects of LHb activity on Vme were evaluated by electrophysiological recording from Vme neurons and local changes in VGLUT2 protein density. UAC produced anxiety in modeled rats and increased neuronal activity in the LHb. VGLUT2 mRNA expression was also increased in the LHb. Further, VGLUT2-positive boutons were observed in close apposite upon parvalbumin (PV)-labeled Vme neurons. VGLUT2 protein expression was also increased in the Vme. Significantly, injection of VGLUT2-targeted shRNA into the LHb reduced the expression of VGLUT2 protein in the Vme, attenuated UAC-associated anxiety-like behaviors, and attenuated electrophysiological changes in the Vme neurons. In conclusion, we show that UAC activates the LHb neurons as well as the periodontal proprioceptive pathway to provide excitatory input to the Vme and produce anxiety in rats. These findings provide a rationale for suppressing activity of the LHb to attenuate both the physical and psychological effects of TMD.
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Affiliation(s)
- Xin Liu
- State Key Laboratory of Military Stomatology, Department of Oral Anatomy and Physiology, National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an, China.,Department of Stomatology, The 960th Hospital of People's Liberation Army, Jinan, China
| | - Kai-Xiang Zhou
- Department of Anatomy, Histology and Embryology and K.K. Leung Brain Research Center, The Fourth Military Medical University, Xi'an, China
| | - Nan-Nan Yin
- Department of Stomatology, The 960th Hospital of People's Liberation Army, Jinan, China
| | - Chun-Kui Zhang
- Department of Anatomy, Histology and Embryology and K.K. Leung Brain Research Center, The Fourth Military Medical University, Xi'an, China
| | - Ming-Hong Shi
- State Key Laboratory of Military Stomatology, Department of Oral Anatomy and Physiology, National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an, China
| | - Hong-Yun Zhang
- State Key Laboratory of Military Stomatology, Department of Oral Anatomy and Physiology, National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an, China
| | - Dong-Mei Wang
- Department of Oral Medicine, School of Stomatology, Xinxiang Medical University, Xinxiang, China
| | - Zi-Jun Xu
- School of Clinical Medicine, University of South China, Hengyang, China
| | - Jing-Dong Zhang
- Department of Anesthesiology, University of Cincinnati Medical College of Medicine, Cincinnati, OH, United States
| | - Jin-Lian Li
- Department of Anatomy, Histology and Embryology and K.K. Leung Brain Research Center, The Fourth Military Medical University, Xi'an, China
| | - Mei-Qing Wang
- State Key Laboratory of Military Stomatology, Department of Oral Anatomy and Physiology, National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an, China
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38
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Umatani C, Oka Y. Multiple functions of non-hypophysiotropic gonadotropin releasing hormone neurons in vertebrates. ZOOLOGICAL LETTERS 2019; 5:23. [PMID: 31367467 PMCID: PMC6647275 DOI: 10.1186/s40851-019-0138-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Accepted: 06/19/2019] [Indexed: 06/10/2023]
Abstract
Gonadotropin releasing hormone (GnRH) is a hypophysiotropic hormone that is generally thought to be important for reproduction. This hormone is produced by hypothalamic GnRH neurons and stimulates the secretion of gonadotropins. On the other hand, vertebrates also have non-hypophysiotropic GnRH peptides, which are produced by extrahypothalamic GnRH neurons. They are mainly located in the terminal nerve, midbrain tegmentum, trigeminal nerve, and spinal cord (sympathetic preganglionic nerves). In vertebrates, there are typically three gnrh paralogues (gnrh1, gnrh2, gnrh3). GnRH-expression in the non-hypophysiotropic neurons (gnrh1 or gnrh3 in the terminal nerve and the trigeminal nerve, gnrh2 in the midbrain tegmentum) occurs from the early developmental stages. Recent studies have suggested that non-hypophysiotropic GnRH neurons play various functional roles. Here, we summarize their anatomical/physiological properties and discuss their possible functions, focusing on studies in vertebrates. GnRH neurons in the terminal nerve show different spontaneous firing properties during the developmental stages. These neurons in adulthood show regular pacemaker firing, and it has been suggested that these neurons show neuromodulatory function related to the regulation of behavioral motivation, etc. In addition to their recognized role in neuromodulation in adult, in juvenile fish, these neurons, which show more frequent burst firing than in adults, are suggested to have novel functions. GnRH neurons in the midbrain tegmentum show regular pacemaker firing similar to that of the adult terminal nerve and are suggested to be involved in modulations of feeding (teleosts) or nutrition-related sexual behaviors (musk shrew). GnRH neurons in the trigeminal nerve are suggested to be involved in nociception and chemosensory avoidance, although the literature on their electrophysiological properties is limited. Sympathetic preganglionic cells in the spinal cord were first reported as peptidergic modulatory neurons releasing GnRH with a putative function in coordinating interaction between vasomotor and exocrine outflow in the sympathetic nervous system. The functional role of non-hypophysiotropic GnRH neurons may thus be in the global modulation of neural circuits in a manner dependent on internal conditions or the external environment.
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Affiliation(s)
- Chie Umatani
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Tokyo, 113-0033 Japan
| | - Yoshitaka Oka
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Tokyo, 113-0033 Japan
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McKay TB, Seyed-Razavi Y, Ghezzi CE, Dieckmann G, Nieland TJF, Cairns DM, Pollard RE, Hamrah P, Kaplan DL. Corneal pain and experimental model development. Prog Retin Eye Res 2019; 71:88-113. [PMID: 30453079 PMCID: PMC6690397 DOI: 10.1016/j.preteyeres.2018.11.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 11/03/2018] [Accepted: 11/13/2018] [Indexed: 12/13/2022]
Abstract
The cornea is a valuable tissue for studying peripheral sensory nerve structure and regeneration due to its avascularity, transparency, and dense innervation. Somatosensory innervation of the cornea serves to identify changes in environmental stimuli at the ocular surface, thereby promoting barrier function to protect the eye against injury or infection. Due to regulatory demands to screen ocular safety of potential chemical exposure, a need remains to develop functional human tissue models to predict ocular damage and pain using in vitro-based systems to increase throughput and minimize animal use. In this review, we summarize the anatomical and functional roles of corneal innervation in propagation of sensory input, corneal neuropathies associated with pain, and the status of current in vivo and in vitro models. Emphasis is placed on tissue engineering approaches to study the human corneal pain response in vitro with integration of proper cell types, controlled microenvironment, and high-throughput readouts to predict pain induction. Further developments in this field will aid in defining molecular signatures to distinguish acute and chronic pain triggers based on the immune response and epithelial, stromal, and neuronal interactions that occur at the ocular surface that lead to functional outcomes in the brain depending on severity and persistence of the stimulus.
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Affiliation(s)
- Tina B McKay
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Yashar Seyed-Razavi
- Center for Translational Ocular Immunology and Cornea Service, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - Chiara E Ghezzi
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Gabriela Dieckmann
- Center for Translational Ocular Immunology and Cornea Service, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - Thomas J F Nieland
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Dana M Cairns
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Rachel E Pollard
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Pedram Hamrah
- Center for Translational Ocular Immunology and Cornea Service, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA.
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40
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He Y, Fan W, Xu Y, Liu YL, He H, Huang F. Distribution and colocalization of melatonin 1a-receptor and NADPH-d in the trigeminal system of rat. PeerJ 2019; 7:e6877. [PMID: 31106073 PMCID: PMC6500374 DOI: 10.7717/peerj.6877] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 03/31/2019] [Indexed: 01/15/2023] Open
Abstract
Melatonin and nitric oxide (NO) are involved in orofacial signal processing in the trigeminal sensory system. The aim of the present study was to examine the distribution of melatonin 1a-receptor (MT1) and its colocalization with nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) in the spinal trigeminal nucleus (STN), the trigeminal ganglion (TG), and the mesencephalic trigeminal nucleus (MTN) in the rat, using histochemistry and immunohistochemistry. Our results show that MT1-positive neurons are widely distributed in the TG and the subnucleus caudalis of the STN. Furthermore, we found that MT1 colocalizes with NADPH-d throughout the TG and MTN, most extensively in the TG. The distribution pattern of MT1 and its colocalization with NADPH-d indicate that melatonin might play an important role in the trigeminal sensory system, which could be responsible for the regulation of NO levels.
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Affiliation(s)
- Yifan He
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China
| | - Wenguo Fan
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China
| | - Yue Xu
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China
| | - Yong Liang Liu
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Hongwen He
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China
| | - Fang Huang
- Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China
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Davoine F, Curti S. Response to coincident inputs in electrically coupled primary afferents is heterogeneous and is enhanced by H-current (IH) modulation. J Neurophysiol 2019; 122:151-175. [PMID: 31042413 DOI: 10.1152/jn.00029.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrical synapses represent a widespread modality of interneuronal communication in the mammalian brain. These contacts, by lowering the effectiveness of random or temporally uncorrelated inputs, endow circuits of coupled neurons with the ability to selectively respond to simultaneous depolarizations. This mechanism may support coincidence detection, a property involved in sensory perception, organization of motor outputs, and improvement signal-to-noise ratio. While the role of electrical coupling is well established, little is known about the contribution of the cellular excitability and its modulations to the susceptibility of groups of neurons to coincident inputs. Here, we obtained dual whole cell patch-clamp recordings of pairs of mesencephalic trigeminal (MesV) neurons in brainstem slices from rats to evaluate coincidence detection and its determinants. MesV neurons are primary afferents involved in the organization of orofacial behaviors whose cell bodies are electrically coupled mainly in pairs through soma-somatic gap junctions. We found that coincidence detection is highly heterogeneous across the population of coupled neurons. Furthermore, combined electrophysiological and modeling approaches reveal that this heterogeneity arises from the diversity of MesV neuron intrinsic excitability. Consistently, increasing these cells' excitability by upregulating the hyperpolarization-activated cationic current (IH) triggered by cGMP results in a dramatic enhancement of the susceptibility of coupled neurons to coincident inputs. In conclusion, the ability of coupled neurons to detect coincident inputs is critically shaped by their intrinsic electrophysiological properties, emphasizing the relevance of neuronal excitability for the many functional operations supported by electrical transmission in mammals. NEW & NOTEWORTHY We show that the susceptibility of pairs of coupled mesencephalic trigeminal (MesV) neurons to coincident inputs is highly heterogenous and depends on the interaction between electrical coupling and neuronal excitability. Additionally, upregulating the hyperpolarization-activated cationic current (IH) by cGMP results in a dramatic increase of this susceptibility. The IH and electrical synapses have been shown to coexist in many neuronal populations, suggesting that modulation of this conductance could represent a common strategy to regulate circuit operation supported by electrical coupling.
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Affiliation(s)
- Federico Davoine
- Instituto de Física e Instituto de Ingeniería Eléctrica, Facultad de Ingeniería, Universidad de la República , Montevideo , Uruguay
| | - Sebastian Curti
- Laboratorio de Neurofisiología Celular, Departamento de Fisiología, Facultad de Medicina, Universidad de la República , Montevideo , Uruguay
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Won J, Lee PR, Oh SB. Alpha 2 adrenoceptor agonist guanabenz directly inhibits hyperpolarization-activated, cyclic nucleotide-modulated (HCN) channels in mesencephalic trigeminal nucleus neurons. Eur J Pharmacol 2019; 854:320-327. [PMID: 31009638 DOI: 10.1016/j.ejphar.2019.04.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 04/03/2019] [Accepted: 04/18/2019] [Indexed: 10/27/2022]
Abstract
Alpha 2 (α2-) adrenoceptor agonists, such as clonidine or dexmedetomidine, have been found to inhibit hyperpolarization-activated, cyclic nucleotide-modulated (HCN) channels, not only by reducing intracellular cyclic AMP levels but also by directly blocking HCN channels. In this study, we examined the inhibitory effect of guanabenz, a centrally acting α2-adrenoceptor agonist with high specificity for α2A-subtype, on HCN channels in mesencephalic trigeminal nucleus (MTN) neurons which robustly express HCN channels and have been suggested to coexpress α2A-adrenoceptors. By performing whole-cell patch-clamp recording on MTN neurons in brainstem slices, hyperpolarization-activated inward current (Ih) was examined during guanabenz treatment. Guanabenz inhibited Ih in a dose-dependent manner, which was likely to be ZD7288-sensitive HCN current as it did not affect barium-sensitive inward rectifying potassium current. Guanabenz not only inhibited Ih but also shifted the voltage-dependent activation curve to hyperpolarizing potentials. Interestingly, Ih inhibition by guanabenz was not reversed by α2-adrenoceptor antagonist atipamezole treatment or by intracellular cyclic AMP perfusion, suggesting that the inhibition may not result from α2A-adrenoceptor signalling pathway but from direct inhibition of HCN channels. Coherent to our electrophysiological results, single-cell RT-PCR revealed that most MTN neurons lack α2A-adrenoceptor mRNA. Our study demonstrates that guanabenz can directly inhibit HCN channels in addition to its primary role of activating α2A-adrenoceptors.
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Affiliation(s)
- Jonghwa Won
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
| | - Pa Reum Lee
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
| | - Seog Bae Oh
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea; Dental Research Institute and Department of Neurobiology and Physiology, School of Dentistry, Seoul National University, Republic of Korea.
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García-Peña CM, Ávila-González D, Miquelajáuregui A, Lozano-Flores C, Mastick GS, Tamariz E, Varela-Echavarría A. Neurophilic Descending Migration of Dorsal Midbrain Neurons Into the Hindbrain. Front Neuroanat 2018; 12:96. [PMID: 30483071 PMCID: PMC6243072 DOI: 10.3389/fnana.2018.00096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/22/2018] [Indexed: 12/29/2022] Open
Abstract
Stereotypic cell migrations in the developing brain are fundamental for the proper patterning of brain regions and formation of neural networks. In this work, we uncovered in the developing rat, a population of neurons expressing tyrosine hydroxylase (TH) that migrates posteriorly from the alar plate of the midbrain, in neurophilic interaction with axons of the mesencephalic nucleus of the trigeminal nerve. A fraction of this population was also shown to traverse the mid-hindbrain boundary, reaching the vicinity of the locus coeruleus (LC) in rhombomere 1 (r1). This migratory population, however, does not have a noradrenergic (NA) phenotype and, in keeping with its midbrain origin, expresses Otx2 which is down regulated upon migration into the hindbrain. The interaction with the trigeminal mesencephalic axons is necessary for the arrangement and distribution of migratory cells as these aspects are dramatically altered in whole embryo cultures upon disruption of trigeminal axon projection by interfering with DCC function. Moreover, in mouse embryos in an equivalent developmental stage, we detected a cell population that also migrates caudally within the midbrain apposed to mesencephalic trigeminal axons but that does not express TH; a fraction of this population expresses calbindin instead. Overall, our work identified TH-expressing neurons from the rat midbrain alar plate that migrate tangentially over long distances within the midbrain and into the hindbrain by means of a close interaction with trigeminal mesencephalic axons. A different migratory population in this region and also in mouse embryos revealed diversity among the cells that follow this descending migratory pathway.
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Affiliation(s)
- Claudia M García-Peña
- Department of Developmental Neurobiology and Neurophysiology, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, México
| | - Daniela Ávila-González
- Department of Developmental Neurobiology and Neurophysiology, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, México
| | - Amaya Miquelajáuregui
- Department of Developmental Neurobiology and Neurophysiology, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, México
| | - Carlos Lozano-Flores
- Department of Developmental Neurobiology and Neurophysiology, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, México
| | - Grant S Mastick
- Department of Biology, University of Nevada, Reno, Reno, NV, United States
| | - Elisa Tamariz
- Department of Developmental Neurobiology and Neurophysiology, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, México
| | - Alfredo Varela-Echavarría
- Department of Developmental Neurobiology and Neurophysiology, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, México
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Fan W, Zhu X, He Y, Li H, Gu W, Huang F, He H. Peripheral sympathetic mechanisms in orofacial pain. J Pain Res 2018; 11:2425-2431. [PMID: 30425556 PMCID: PMC6200434 DOI: 10.2147/jpr.s179327] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Sympathetic nervous system (SNS) is a part of the autonomic nervous system which involuntarily regulates internal body functions. It appears to modulate the processing of nociceptive information. Many orofacial pain conditions involve inflammation of orofacial tissues and/or injury of nerve, some of which might be attributed to SNS. Thus, the aim of this review was to bring together the data available regarding the peripheral sympathetic mechanisms involved in orofacial pain. A clearer understanding of SNS–sensory interactions in orofacial pain may provide a basis for novel therapeutic strategies for conditions that respond poorly to conventional treatments.
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Affiliation(s)
- Wenguo Fan
- Institute of Stomatological Research, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China, .,Department of Anesthesiology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Xiao Zhu
- The Public Service Platform of South China Sea for R&D Marine Biomedicine Resources, Marine Biomedical Research Institute, Guangdong Medical University, Zhanjiang, China
| | - Yifan He
- Institute of Stomatological Research, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China,
| | - Hongmei Li
- Department of Pathology, Guangdong Medical University, Dongguan, China
| | - Wenzhen Gu
- Institute of Stomatological Research, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China,
| | - Fang Huang
- Institute of Stomatological Research, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China,
| | - Hongwen He
- Institute of Stomatological Research, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China,
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Frederiksen SD, Warfvinge K, Ohlsson L, Edvinsson L. Expression of Pituitary Adenylate Cyclase-activating Peptide, Calcitonin Gene-related Peptide and Headache Targets in the Trigeminal Ganglia of Rats and Humans. Neuroscience 2018; 393:319-332. [DOI: 10.1016/j.neuroscience.2018.10.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 09/28/2018] [Accepted: 10/02/2018] [Indexed: 11/16/2022]
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Huang P, Kuo PH, Lee MT, Chiou LC, Fan PC. Age-Dependent Anti-migraine Effects of Valproic Acid and Topiramate in Rats. Front Pharmacol 2018; 9:1095. [PMID: 30319425 PMCID: PMC6167431 DOI: 10.3389/fphar.2018.01095] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 09/07/2018] [Indexed: 01/18/2023] Open
Abstract
Background: Valproic acid (VPA) and topiramate (TPM), initially developed as antiepileptics, are approved for migraine prophylaxis in adults but not children. The differences in their antimigraine mechanism(s) by age remain unclear. Methods: A migraine model induced by intra-cisternal (i.c.) capsaicin instillation in pediatric (4–5 weeks) and adult (8–9 weeks) rats was pretreated with VPA (30, 100 mg/kg) or TPM (10, 30, 100 mg/kg). Noxious meningeal stimulation by the irritant capsaicin triggered trigeminovascular system (TGVS) activation mimicking migraine condition, which were assessed peripherally by the depletion of calcitonin gene-related peptide (CGRP) in sensory nerve fibers of the dura mater, the increased CGRP immunoreactivity at trigeminal ganglia (TG) and centrally by the number of c-Fos-immunoreactive (c-Fos-ir) neurons in the trigeminocervical complex (TCC). Peripherally, CGRP released from dural sensory nerve terminals of TG triggered pain signal transmission in the primary afferent of trigeminal nerve, which in turn caused central sensitization of the TGVS due to TCC activation and hence contributed to migraine. Results: In the VPA-treated group, the central responsiveness expressed by reducing the number of c-Fos-ir neurons, which had been increased by i.c. capsaicin, was significant in pediatric, but not adult, rats. Inversely, VPA was effective in peripheral inhibition of elevated CGRP immunoreactivity in the TG and CGRP depletion in the dura mater of adult, but not pediatric, rats. In TPM group, the central responsiveness was significant in both adult and pediatric groups. Peripherally, TPM significantly inhibited capsaicin-induced CGRP expression of TG in adult, but not pediatric, rats. Interestingly, the capsaicin-induced depletion of CGRP in dura was significantly rescued by TPM at high doses in adults, but at low dose in pediatric group. Conclusion: These results suggest VPA exerted peripheral inhibition in adult, but central suppression in pediatric migraine-rats. In contrast, TPM involves both central and peripheral inhibition of migraine with an optimal therapeutic window in both ages. These findings may clarify the age-dependent anti-migraine mechanism of VPA and TPM, which may guide the development of new pediatric anti-migraine drugs in the future.
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Affiliation(s)
- Pokai Huang
- Department of Pediatrics, E-da Dachang Hospital, Kaohsiung, Taiwan
| | - Ping-Hung Kuo
- Department of Internal Medicine, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ming Tatt Lee
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.,Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, Malaysia
| | - Lih-Chu Chiou
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
| | - Pi-Chuan Fan
- Department of Pediatrics, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
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Krishnamoorthy G, Narayana AI, Balkrishanan D. Mastication as a tool to prevent cognitive dysfunctions. JAPANESE DENTAL SCIENCE REVIEW 2018; 54:169-173. [PMID: 30302135 PMCID: PMC6175965 DOI: 10.1016/j.jdsr.2018.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 05/14/2018] [Accepted: 06/22/2018] [Indexed: 10/28/2022] Open
Abstract
Mastication as we all know has always been related to its primary function of digestion, but little do we know that it produces an enhancing effect on general health, especially the cognitive performance related aspects of memory. Recent studies have shown its association with activation of various brain regions, however little is known about its effects on neuronal activity in these specified regions. According to the enormous evidences collected so far, mastication has proved to be effective in conducting huge amount of sensory information to the brain, and maintaining learning and memory functions of hippocampus. Therefore it is essential that we maintain normal occlusion and preserve the masticatory function as long as possible to prevent the attenuation of hippocampus, caused by occlusal disharmony and reduced mastication. We provide an overview on how mastication activates various cortical areas of the brain and how an increase in the cerebral blood oxygen level of hippocampus and prefrontal cortex (PFC) accentuates the learning and memory process. We also justify why maintaining and establishing a normal occlusion is important from neurological point of view.
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Affiliation(s)
- Gayathri Krishnamoorthy
- Department of Prosthodontics and Crown & Bridge, Manipal College of Dental Sciences, Manipal University, Manipal, 576104 India
| | - Aparna I Narayana
- Department of Prosthodontics and Crown & Bridge, Manipal College of Dental Sciences, Manipal University, Manipal, 576104 India
| | - Dhanasekar Balkrishanan
- Department of Prosthodontics and Crown & Bridge, Manipal College of Dental Sciences, Manipal University, Manipal, 576104 India
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Messlinger K, Russo AF. Current understanding of trigeminal ganglion structure and function in headache. Cephalalgia 2018; 39:1661-1674. [PMID: 29989427 DOI: 10.1177/0333102418786261] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION The trigeminal ganglion is unique among the somatosensory ganglia regarding its topography, structure, composition and possibly some functional properties of its cellular components. Being mainly responsible for the sensory innervation of the anterior regions of the head, it is a major target for headache research. One intriguing question is if the trigeminal ganglion is merely a transition site for sensory information from the periphery to the central nervous system, or if intracellular modulatory mechanisms and intercellular signaling are capable of controlling sensory information relevant for the pathophysiology of headaches. METHODS An online search based on PubMed was made using the keyword "trigeminal ganglion" in combination with "anatomy", "headache", "migraine", "neuropeptides", "receptors" and "signaling". From the relevant literature, further references were selected in view of their relevance for headache mechanisms. The essential information was organized based on location and cell types of the trigeminal ganglion, neuropeptides, receptors for signaling molecules, signaling mechanisms, and their possible relevance for headache generation. RESULTS The trigeminal ganglion consists of clusters of sensory neurons and their peripheral and central axon processes, which are arranged according to the three trigeminal partitions V1-V3. The neurons are surrounded by satellite glial cells, the axons by Schwann cells. In addition, macrophage-like cells can be found in the trigeminal ganglion. Neurons express various neuropeptides, among which calcitonin gene-related peptide is the most prominent in terms of its prevalence and its role in primary headaches. The classical calcitonin gene-related peptide receptors are expressed in non-calcitonin gene-related peptide neurons and satellite glial cells, although the possibility of a second calcitonin gene-related peptide receptor in calcitonin gene-related peptide neurons remains to be investigated. A variety of other signal molecules like adenosine triphosphate, nitric oxide, cytokines, and neurotrophic factors are released from trigeminal ganglion cells and may act at receptors on adjacent neurons or satellite glial cells. CONCLUSIONS The trigeminal ganglion may act as an integrative organ. The morphological and functional arrangement of trigeminal ganglion cells suggests that intercellular and possibly also autocrine signaling mechanisms interact with intracellular mechanisms, including gene expression, to modulate sensory information. Receptors and neurotrophic factors delivered to the periphery or the trigeminal brainstem can contribute to peripheral and central sensitization, as in the case of primary headaches. The trigeminal ganglion as a target of drug action outside the blood-brain barrier should therefore be taken into account.
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Affiliation(s)
- Karl Messlinger
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Andrew F Russo
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA.,Iowa VA Health Care System, Iowa City, IA, USA
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Abd El-Aleem SA, Morales-Aza BM. In Situ Hybridisation Study of Neuronal Neuropeptides Expression in Models of Mandibular Denervation with or without Inflammation: Injury Dependant Neuropeptide Plasticity. ACTA ACUST UNITED AC 2018; 9. [PMID: 31192032 PMCID: PMC6561781 DOI: 10.4172/2157-7099.1000509] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neuronal expression of neuropeptides is altered following peripheral tissue injury associated with inflammation or nerve injury. This results in neuropathic pain with or without neurogenic inflammation which is a major health problem regularly seen in trigeminal neuralgia. Activation of the trigeminal system results in the release of vasoactive neuropeptides substance P and Calcitonin Gene-related Peptide (CGRP) which contribute to nociception, pain and neurogenic inflammation in injured tissues.
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Affiliation(s)
| | - Begonia M Morales-Aza
- Department of Physiology, School of Medical Sciences, University of Bristol, Bristol, UK
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Ter-Avetisyan G, Dumoulin A, Herrel A, Schmidt H, Strump J, Afzal S, Rathjen FG. Loss of Axon Bifurcation in Mesencephalic Trigeminal Neurons Impairs the Maximal Biting Force in Npr2-Deficient Mice. Front Cell Neurosci 2018; 12:153. [PMID: 29962937 PMCID: PMC6013911 DOI: 10.3389/fncel.2018.00153] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/16/2018] [Indexed: 11/13/2022] Open
Abstract
Bifurcation of axons from dorsal root ganglion (DRG) and cranial sensory ganglion (CSG) neurons is mediated by a cGMP-dependent signaling pathway composed of the ligand C-type natriuretic peptide (CNP), the receptor guanylyl cyclase Npr2 and the cGMP-dependent protein kinase I (cGKI). Here, we demonstrate that mesencephalic trigeminal neurons (MTN) which are the only somatosensory neurons whose cell bodies are located within the CNS co-express Npr2 and cGKI. Afferents of MTNs form Y-shaped branches in rhombomere 2 where the ligand CNP is expressed. Analyzing mouse mutants deficient for CNP or Npr2 we found that in the absence of CNP-induced cGMP signaling MTN afferents no longer bifurcate and instead extend either into the trigeminal root or caudally in the hindbrain. Since MTNs provide sensory information from jaw closing muscles and periodontal ligaments we measured the bite force of conditional mouse mutants of Npr2 (Npr2flox/flox;Engr1Cre ) that lack bifurcation of MTN whereas the bifurcation of trigeminal afferents is normal. Our study revealed that the maximal biting force of both sexes is reduced in Npr2flox/flox;Engr1Cre mice as compared to their Npr2flox/flox littermate controls. In conclusion sensory feedback mechanisms from jaw closing muscles or periodontal ligaments might be impaired in the absence of MTN axon bifurcation.
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Affiliation(s)
| | | | - Anthony Herrel
- Département Adaptations du Vivant, UMR 7179 Centre National de la Recherche Scientifique/MNHN, Paris, France
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