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Martínez AL, Brea J, Domínguez E, Varela MJ, Allegue C, Cruz R, Monroy X, Merlos M, Burgueño J, Carracedo Á, Loza MI. Identification of Sodium Transients Through NaV1.5 Channels as Regulators of Differentiation in Immortalized Dorsal Root Ganglia Neurons. Front Cell Neurosci 2022; 16:816325. [PMID: 35465610 PMCID: PMC9018981 DOI: 10.3389/fncel.2022.816325] [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: 11/16/2021] [Accepted: 03/07/2022] [Indexed: 11/13/2022] Open
Abstract
Neuronal differentiation is a complex process through which newborn neurons acquire the morphology of mature neurons and become excitable. We employed a combination of functional and transcriptomic approaches to deconvolute and identify key regulators of the differentiation process of a DRG neuron-derived cell line, and we focused our study on the NaV1.5 ion channel (encoded by Scn5a) as a channel involved in the acquisition of DRG neuronal features. Overexpression of Scn5a enhances the acquisition of neuronal phenotypic features and increases the KCl-elicited hyperexcitability response in a DRG-derived cell line. Moreover, pharmacologic inhibition of the NaV1.5 channel during differentiation hinders the acquisition of phenotypic features of neuronal cells and the hyperexcitability increase in response to changes in the extracellular medium ionic composition. Taken together, these data highlight the relevance of sodium transients in regulating the neuronal differentiation process in a DRG neuron-derived cell line.
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Affiliation(s)
- Antón L. Martínez
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - José Brea
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Eduardo Domínguez
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - María J. Varela
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Catarina Allegue
- Grupo de Medicina Xenómica, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Raquel Cruz
- Grupo de Medicina Xenómica, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Xavier Monroy
- WeLab Barcelona, Parc Científic de Barcelona, Barcelona, Spain
| | - Manuel Merlos
- WeLab Barcelona, Parc Científic de Barcelona, Barcelona, Spain
| | - Javier Burgueño
- WeLab Barcelona, Parc Científic de Barcelona, Barcelona, Spain
- *Correspondence: Javier Burgueño,
| | - Ángel Carracedo
- Grupo de Medicina Xenómica, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
- Fundación Pública Galega de Medicina Xenómica, Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), SERGAS, Santiago de Compostela, Spain
| | - María Isabel Loza
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
- María Isabel Loza,
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Liu Y, Zhou S, Zhao L, Gu X. Identification of Neuronal Cells in Sciatic Nerves of Adult Rats. Front Cell Neurosci 2022; 16:816814. [PMID: 35401123 PMCID: PMC8991689 DOI: 10.3389/fncel.2022.816814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/14/2022] [Indexed: 11/13/2022] Open
Abstract
Prior research generally confirms that there are no neuronal cell bodies in the adult sciatic nerve. However, we occasionally find some neuronal cells in adult rat sciatic nerves, either intact or crush-injured. By whole-mount staining and optical imaging of the hyalinized sciatic nerves for Stmn2 (a specific marker for neuronal cells), we found those neuronal cells with irregular distribution in the sciatic nerves in both crushed model and normal rats. We investigated the identity of those cells and established a cultured sciatic nerve model. Immunohistochemistry evidence both in vivo and in vitro illustrated that some of those cells are mature neurons in sciatic nerves. With single-cell sequencing of neuronal cells in adeno-associated virus (AAV)-infected sciatic nerves, we identified that some of those cells are a kind of neuronal stem-like cells. Then we constructed a Nestin-CreERT 2 rat line and traced those cells with fluorescence labeling which was induced by tamoxifen. Interesting, we proved that neuronal stem-like cells could proliferate by combination of EdU incorporation with staining in the sciatic nerves of transgenic rats. Together, the discovery of neuronal cells in adult sciatic nerves will make us aware of the distribution of neurons in the peripheral nervous system. Especially our data suggest that neuronal stem-like cells could proliferate in the sciatic nerves of adult rats.
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Affiliation(s)
- Yisheng Liu
- Model Animal Research Center, Nanjing University, Nanjing, China
| | - Songlin Zhou
- Key Laboratory of Neuroregeneration, Ministry of Education and Jiangsu Province, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Lili Zhao
- Model Animal Research Center, Nanjing University, Nanjing, China
| | - Xiaosong Gu
- Model Animal Research Center, Nanjing University, Nanjing, China
- Key Laboratory of Neuroregeneration, Ministry of Education and Jiangsu Province, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
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Perelló M, Cornejo MP, De Francesco PN, Fernandez G, Gautron L, Valdivia LS. The controversial role of the vagus nerve in mediating ghrelin´s actions: gut feelings and beyond. IBRO Neurosci Rep 2022; 12:228-239. [PMID: 35746965 PMCID: PMC9210457 DOI: 10.1016/j.ibneur.2022.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/08/2022] [Accepted: 03/08/2022] [Indexed: 12/26/2022] Open
Abstract
Ghrelin is a stomach-derived peptide hormone that acts via the growth hormone secretagogue receptor (GHSR) and displays a plethora of neuroendocrine, metabolic, autonomic and behavioral actions. It has been proposed that some actions of ghrelin are exerted via the vagus nerve, which provides a bidirectional communication between the central nervous system and peripheral systems. The vagus nerve comprises sensory fibers, which originate from neurons of the nodose and jugular ganglia, and motor fibers, which originate from neurons of the medulla. Many anatomical studies have mapped GHSR expression in vagal sensory or motor neurons. Also, numerous functional studies investigated the role of the vagus nerve mediating specific actions of ghrelin. Here, we critically review the topic and discuss the available evidence supporting, or not, a role for the vagus nerve mediating some specific actions of ghrelin. We conclude that studies using rats have provided the most congruent evidence indicating that the vagus nerve mediates some actions of ghrelin on the digestive and cardiovascular systems, whereas studies in mice resulted in conflicting observations. Even considering exclusively studies performed in rats, the putative role of the vagus nerve in mediating the orexigenic and growth hormone (GH) secretagogue properties of ghrelin remains debated. In humans, studies are still insufficient to draw definitive conclusions regarding the role of the vagus nerve mediating most of the actions of ghrelin. Thus, the extent to which the vagus nerve mediates ghrelin actions, particularly in humans, is still uncertain and likely one of the most intriguing unsolved aspects of the field.
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Ye L, Rawls JF. Microbial influences on gut development and gut-brain communication. Development 2021; 148:dev194936. [PMID: 34758081 PMCID: PMC8627602 DOI: 10.1242/dev.194936] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 10/07/2021] [Indexed: 12/15/2022]
Abstract
The developmental programs that build and sustain animal forms also encode the capacity to sense and adapt to the microbial world within which they evolved. This is abundantly apparent in the development of the digestive tract, which typically harbors the densest microbial communities of the body. Here, we review studies in human, mouse, zebrafish and Drosophila that are revealing how the microbiota impacts the development of the gut and its communication with the nervous system, highlighting important implications for human and animal health.
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Wang YB, de Lartigue G, Page AJ. Dissecting the Role of Subtypes of Gastrointestinal Vagal Afferents. Front Physiol 2020; 11:643. [PMID: 32595525 PMCID: PMC7300233 DOI: 10.3389/fphys.2020.00643] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 05/20/2020] [Indexed: 12/22/2022] Open
Abstract
Gastrointestinal (GI) vagal afferents convey sensory signals from the GI tract to the brain. Numerous subtypes of GI vagal afferent have been identified but their individual roles in gut function and feeding regulation are unclear. In the past decade, technical approaches to selectively target vagal afferent subtypes and to assess their function has significantly progressed. This review examines the classification of GI vagal afferent subtypes and discusses the current available techniques to study vagal afferents. Investigating the distribution of GI vagal afferent subtypes and understanding how to access and modulate individual populations are essential to dissect their fundamental roles in the gut-brain axis.
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Affiliation(s)
- Yoko B Wang
- Vagal Afferent Research Group, Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia
| | - Guillaume de Lartigue
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, United States.,Center for Integrative Cardiovascular and Metabolic Disease, University of Florida, Gainesville, FL, United States
| | - Amanda J Page
- Vagal Afferent Research Group, Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia.,Nutrition, Diabetes and Gut Health, Lifelong Health Theme, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
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Besecker EM, Blanke EN, Deiter GM, Holmes GM. Gastric vagal afferent neuropathy following experimental spinal cord injury. Exp Neurol 2019; 323:113092. [PMID: 31697943 DOI: 10.1016/j.expneurol.2019.113092] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 09/11/2019] [Accepted: 10/23/2019] [Indexed: 01/01/2023]
Abstract
Dramatic impairment of gastrointestinal (GI) function accompanies high-thoracic spinal cord injury (T3-SCI). The vagus nerve contains mechano- and chemosensory fibers as well as the motor fibers necessary for the central nervous system (CNS) control of GI reflexes. Cell bodies for the vagal afferent fibers are located within the nodose gangla (NG) and the majority of vagal afferent axons are unmyelinated C fibers that are sensitive to capsaicin through activation of transient receptor potential vanilloid-1 (TRPV1) channels. Vagal afferent fibers also express receptors for GI hormones, including cholecystokinin (CCK). Previously, T3-SCI provokes a transient GI inflammatory response as well as a reduction of both gastric emptying and centrally-mediated vagal responses to GI peptides, including CCK. TRPV1 channels and CCK-A receptors (CCKar) expressed in vagal afferents are upregulated in models of visceral inflammation. The present study investigated whether T3-SCI attenuates peripheral vagal afferent sensitivity through plasticity of TRPV1 and CCK receptors. Vagal afferent response to graded mechanical stimulation of the stomach was significantly attenuated by T3-SCI at 3-day and 3-week recovery. Immunocytochemical labeling for CCKar and TRPV1 demonstrated expression on dissociated gastric-projecting NG neurons. Quantitative assessment of mRNA expression by qRT-PCR revealed significant elevation of CCKar and TRPV1 in the whole NG following T3-SCI in 3-day recovery, but levels returned to normal after 3-weeks. Three days after injury, systemic administration of CCK-8 s showed a significantly diminished gastric vagal afferent response in T3-SCI rats compared to control rats while systemic capsaicin infusion revealed a significant elevation of vagal response in T3-SCI vs control rats. These findings demonstrate that T3-SCI provokes peripheral remodeling and prolonged alterations in the response of vagal afferent fibers to the physiological signals associated with digestion.
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Affiliation(s)
- Emily M Besecker
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, United States of America; Department of Health Sciences, Gettysburg College, Gettysburg, PA 17325, United States of America
| | - Emily N Blanke
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, United States of America
| | - Gina M Deiter
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, United States of America
| | - Gregory M Holmes
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, United States of America.
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7
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Li W, Yang H, Lu Y. Capsaicin alleviates lipid metabolism disorder in high beef fat-fed mice. J Funct Foods 2019. [DOI: 10.1016/j.jff.2019.103444] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Walters KM, Boucher M, Boucher GG, Opsahl AC, Mouton PR, Liu CN, Ritenour CR, Kawabe TT, Pryski HN, Somps CJ. No Evidence of Neurogenesis in Adult Rat Sympathetic Ganglia Following Guanethidine-Induced Neuronal Loss. Toxicol Pathol 2019; 48:228-237. [PMID: 30987556 DOI: 10.1177/0192623319843052] [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] [Indexed: 11/15/2022]
Abstract
The potential for neurogenesis in the cranial (superior) cervical ganglia (SCG) of the sympathetic nervous system was evaluated. Eleven consecutive daily doses of guanethidine (100 mg/kg/d) were administered intraperitoneally to rats in order to destroy postganglionic sympathetic neurons in SCG. Following the last dose, animals were allowed to recover 1, 3, or 6 months. Right and left SCG from guanethidine-treated and age-matched, vehicle-treated control rats were harvested for histopathologic, morphometric, and stereologic evaluations. Both morphometric and stereologic evaluations confirmed neuron loss following guanethidine treatment. Morphometric analysis revealed a 50% to 60% lower number of tyrosine hydroxylase (TH)-positive neurons per unit area of SCG at both 3 and 6 months of recovery, compared to ganglia of age-matched controls, with no evidence of restoration of neuron density between 3 and 6 months. Reductions in TH-positive neurons following guanethidine treatment were corroborated by unbiased stereology of total hematoxylin and eosin-stained neuron numbers in SCG. Stereologic analyses revealed that total neuron counts were lower by 37% at 3 months of recovery when compared to age-matched vehicle controls, again with no obvious restoration between 3 and 6 months. Thus, no evidence was found that postganglionic neurons of the sympathetic nervous system in the adult rat have a neurogenic capacity.
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Affiliation(s)
- Karen M Walters
- Pfizer Drug Safety Research and Development, Groton, CT, USA
| | - Magalie Boucher
- Pfizer Drug Safety Research and Development, Groton, CT, USA
| | | | - Alan C Opsahl
- Pfizer Drug Safety Research and Development, Groton, CT, USA
| | - Peter R Mouton
- SRC Biosciences, Stereology Resource Center, Inc, Tampa, FL, USA
| | - Chang-Ning Liu
- Pfizer Drug Safety Research and Development, Groton, CT, USA
| | | | - Thomas T Kawabe
- Pfizer Drug Safety Research and Development, Groton, CT, USA
| | - Hayley N Pryski
- Pfizer Drug Safety Research and Development, Groton, CT, USA
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Minaya DM, Di Lorenzo PM, Hajnal A, Czaja K. Roux‑en‑Y gastric bypass surgery triggers rapid DNA fragmentation in vagal afferent neurons in rats. Acta Neurobiol Exp (Wars) 2019; 79:432-444. [PMID: 31885399 PMCID: PMC7033620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Previous studies have shown that Roux‑en‑Y gastric bypass (RYGB), one of the most effective weight loss treatments for obesity, results in neurodegenerative responses in vagal afferent gut‑brain connection reflected by microglia activation and reduced sensory input to the nucleus tractus solitarius (NTS). However, it is not known whether RYGB‑induced microglia activation is the cause or an effect of the reported neuronal damage. Therefore, the aim of this study was to establish the order of neurodegenerative responses in vagal afferents after RYGB in the nodose ganglia (NG) and NTS in male and female rats. Sprague‑Dawley rats were fed regular chow or an energy‑dense diet for two weeks followed by RYGB or sham surgery. Twenty‑four hours later, animals were sacrificed and NG and NTS were collected. Neuronal cell damage was determined by TUNEL assay. Microglia activation was determined by quantifying the fluorescent staining against the ionizing calcium adapter‑binding molecule 1. Reorganization of vagal afferents was evaluated by fluorescent staining against isolectin 4. Results of the study revealed significantly increased DNA fragmentation in vagal neurons in the NG when observed at 24 h after RYGB. The surgery did not produce rapid changes in the density of vagal afferents and microglia activation in the NTS. These data indicate that decreased density of vagal afferents and increased microglia activation in the NTS likely ensue as a res ult of RYGB‑induced neuronal damage.
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Affiliation(s)
- Dulce M Minaya
- Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia, Athens, USA
| | | | - Andras Hajnal
- Department of Neural and Behavioral Sciences, Pennsylvania State University, College of Medicine, Hershey, USA
| | - Krzysztof Czaja
- Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia, Athens, USA;
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Johnston S, Gallaher Z, Czaja K. Exogenous reference gene normalization for real-time reverse transcription-polymerase chain reaction analysis under dynamic endogenous transcription. Neural Regen Res 2015; 7:1064-72. [PMID: 25722696 PMCID: PMC4340019 DOI: 10.3969/j.issn.1673-5374.2012.14.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 02/24/2012] [Indexed: 12/21/2022] Open
Abstract
Quantitative real-time reverse transcription-polymerase chain reaction (qPCR) is widely used to investigate transcriptional changes following experimental manipulations to the nervous system. Despite the widespread utilization of qPCR, the interpretation of results is marred by the lack of a suitable reference gene due to the dynamic nature of endogenous transcription. To address this inherent deficiency, we investigated the use of an exogenous spike-in mRNA, luciferase, as an internal reference gene for the 2(-∆∆Ct) normalization method. To induce dynamic transcription, we systemically administered capsaicin, a neurotoxin selective for C-type sensory neurons expressing the TRPV-1 receptor, to adult male Sprague-Dawley rats. We later isolated nodose ganglia for qPCR analysis with the reference being either exogenous luciferase mRNA or the commonly used endogenous reference β-III tubulin. The exogenous luciferase mRNA reference clearly demonstrated the dynamic expression of the endogenous reference. Furthermore, variability of the endogenous reference would lead to misinterpretation of other genes of interest. In conclusion, traditional reference genes are often unstable under physiologically normal situations, and certainly unstable following the damage to the nervous system. The use of exogenous spike-in reference provides a consistent and easily implemented alternative for the analysis of qPCR data.
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Affiliation(s)
- Stephen Johnston
- Programs in Neuroscience and Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-6520, USA
| | - Zachary Gallaher
- Programs in Neuroscience and Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-6520, USA
| | - Krzysztof Czaja
- Programs in Neuroscience and Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-6520, USA
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Czaja K, Fornaro M, Geuna S. Neurogenesis in the adult peripheral nervous system. Neural Regen Res 2015; 7:1047-54. [PMID: 25722694 PMCID: PMC4340017 DOI: 10.3969/j.issn.1673-5374.2012.14.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 02/24/2012] [Indexed: 12/21/2022] Open
Abstract
Most researchers believe that neurogenesis in mature mammals is restricted only to the subgranular zone of the dentate gyrus and the subventricular zone of the lateral ventricle in the central nervous system. In the peripheral nervous system, neurogenesis is thought to be active only during prenatal development, with the exception of the olfactory neuroepithelium. However, sensory ganglia in the adult peripheral nervous system have been reported to contain precursor cells that can proliferate in vitro and be induced to differentiate into neurons. The occurrence of insult-induced neurogenesis, which has been reported by several investigators in the brain, is limited to a few recent reports for the peripheral nervous system. These reports suggest that damage to the adult nervous system induces mechanisms similar to those that control the generation of new neurons during prenatal development. Understanding conditions under which neurogenesis can be induced in physiologically non-neurogenic regions in adults is one of the major challenges for developing therapeutic strategies to repair neurological damage. However, the induced neurogenesis in the peripheral nervous system is still largely unexplored. This review presents the history of research on adult neurogenesis in the peripheral nervous system, which dates back more than 100 years and reveals the evidence on the under estimated potential for generation of new neurons in the adult peripheral nervous system.
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Affiliation(s)
- Krzysztof Czaja
- Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology (VCAPP), College of Veterinary Medicine, Washington State University, Pullman, WA 99163-6520, USA
| | - Michele Fornaro
- Department of Anatomy, Chicago College of Osteopathic Medicine (CCOM), Midwestern University, Downers Grove, IL 60515, USA
| | - Stefano Geuna
- Neuroscience Institute of the Cavalieri Ottolenghi Foundation (NICO) & Department of Clinical and Biological Sciences, University of Turin, Orbassano 10043, Italy
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Peters JH, Gallaher ZR, Ryu V, Czaja K. Withdrawal and restoration of central vagal afferents within the dorsal vagal complex following subdiaphragmatic vagotomy. J Comp Neurol 2014; 521:3584-99. [PMID: 23749657 DOI: 10.1002/cne.23374] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 04/19/2013] [Accepted: 05/23/2013] [Indexed: 12/21/2022]
Abstract
Vagotomy, a severing of the peripheral axons of the vagus nerve, has been extensively utilized to determine the role of vagal afferents in viscerosensory signaling. Vagotomy is also an unavoidable component of some bariatric surgeries. Although it is known that peripheral axons of the vagus nerve degenerate and then regenerate to a limited extent following vagotomy, very little is known about the response of central vagal afferents in the dorsal vagal complex to this type of damage. We tested the hypothesis that vagotomy results in the transient withdrawal of central vagal afferent terminals from their primary central target, the nucleus of the solitary tract (NTS). Sprague-Dawley rats underwent bilateral subdiaphragmatic vagotomy and were sacrificed 10, 30, or 60 days later. Plastic changes in vagal afferent fibers and synapses were investigated at the morphological and functional levels by using a combination of an anterograde tracer, synapse-specific markers, and patch-clamp electrophysiology in horizontal brain sections. Morphological data revealed that numbers of vagal afferent fibers and synapses in the NTS were significantly reduced 10 days following vagotomy and were restored to control levels by 30 days and 60 days, respectively. Electrophysiology revealed transient decreases in spontaneous glutamate release, glutamate release probability, and the number of primary afferent inputs. Our results demonstrate that subdiaphragmatic vagotomy triggers transient withdrawal and remodeling of central vagal afferent terminals in the NTS. The observed vagotomy-induced plasticity within this key feeding center of the brain may be partially responsible for the response of bariatric patients following gastric bypass surgery.
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Affiliation(s)
- James H Peters
- Program in Neuroscience, Integrative Physiology and Neuroscience (IPN), College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164
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Ronchi G, Ryu V, Fornaro M, Czaja K. Hippocampal plasticity after a vagus nerve injury in the rat. Neural Regen Res 2012; 7:1055-63. [PMID: 25722695 PMCID: PMC4340018 DOI: 10.3969/j.issn.1673-5374.2012.14.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 02/24/2012] [Indexed: 01/06/2023] Open
Abstract
Stimulation of the vagus nerve has been previously reported to promote neural plasticity and neurogenesis in the brain. Several studies also revealed plastic changes in the spinal cord after injuries to somatosensory nerves originating from both the brachial and lumbo-sacral plexuses. However, the neurogenic responses of the brain to the injury of the viscerosensory innervation are not as yet well understood. In the present study, we investigated whether cells in the dentate gyrus of the hippocampus respond to a chemical and physical damage to the vagus nerve in the adult rat. Intraperitoneal capsaicin administration was used to damage non-myelinated vagal afferents while subdiaphragmatic vagotomy was used to damage both the myelinated and non-myelinated vagal afferents. The 5-bromo-2-deoxyuridine (BrdU) incorporation together with cell-specific markers was used to study neural proliferation in subgranular zone, granule cell layer, molecular layer and hilus of the dentate gyrus. Microglia activation was determined by quantifying changes in the intensity of fluorescent staining with a primary antibody against ionizing calcium adapter-binding molecule 1. Results revealed that vagotomy decreased BrdU incorporation in the hilus 15 days after injury compared to the capsaicin group. Capsaicin administration decreased BrdU incorporation in the granular cell layer 60 days after the treatment. Capsaicin decreased the number of doublecortin-expressing cells in the dentate gyrus, whereas vagotomy did not alter the expression of doublecortin in the hippocampus. Both the capsaicin- and the vagotomy-induced damage to the vagus nerve decreased microglia activation in the hippocampus at 15 days after the injury. At 30 days post injury, capsaicin-treated and vagotomized rats revealed significantly more activated microglia. Our findings show that damage to the subdiaphragmatic vagus in adult rats is followed by microglia activation and long-lasting changes in the dentate gyrus, leading to alteration of neurogenesis.
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Affiliation(s)
- Giulia Ronchi
- Department of Clinical and Biological Sciences, University of Turin, Turin 10043, Italy
- Neuroscience Institute of the “Cavalieri Ottolenghi” Foundation (NICO), University of Turin, Turin 10043, Italy
| | - Vitaly Ryu
- Programs in Neuroscience and Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Michele Fornaro
- Department of Anatomy, Midwestern University, Downers Grove, IL60515, USA
| | - Krzysztof Czaja
- Programs in Neuroscience and Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
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Czaja K. The neural butterfly effect: The injury to peripheral nerves changes the brain. Neural Regen Res 2012; 7:1045-6. [PMID: 25722693 PMCID: PMC4340016 DOI: 10.3969/j.issn.1673-5374.2012.14.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 02/24/2012] [Indexed: 11/12/2022] Open
Affiliation(s)
- Krzysztof Czaja
- Programs in Neuroscience and Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-6520, USA
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