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Zhao C, Zhou X, Shi X. The influence of Nav1.9 channels on intestinal hyperpathia and dysmotility. Channels (Austin) 2023; 17:2212350. [PMID: 37186898 DOI: 10.1080/19336950.2023.2212350] [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: 05/17/2023] Open
Abstract
The Nav1.9 channel is a voltage-gated sodium channel. It plays a vital role in the generation of pain and the formation of neuronal hyperexcitability after inflammation. It is highly expressed in small diameter neurons of dorsal root ganglions and Dogiel II neurons in enteric nervous system. The small diameter neurons in dorsal root ganglions are the primary sensory neurons of pain conduction. Nav1.9 channels also participate in regulating intestinal motility. Functional enhancements of Nav1.9 channels to a certain extent lead to hyperexcitability of small diameter dorsal root ganglion neurons. The hyperexcitability of the neurons can cause visceral hyperalgesia. Intestinofugal afferent neurons and intrinsic primary afferent neurons in enteric nervous system belong to Dogiel type II neurons. Their excitability can also be regulated by Nav1.9 channels. The hyperexcitability of intestinofugal afferent neurons abnormally activate entero-enteric inhibitory reflexes. The hyperexcitability of intrinsic primary afferent neurons disturb peristaltic waves by abnormally activating peristaltic reflexes. This review discusses the role of Nav1.9 channels in intestinal hyperpathia and dysmotility.
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Affiliation(s)
- Chenyu Zhao
- Department of Gastroenterology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
- Department of Gastroenterology, The Second Xiangya Hospital, Central South University, Changsha, China
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Xi Zhou
- The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Xiaoliu Shi
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, China
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Fung C, Vanden Berghe P. Functional circuits and signal processing in the enteric nervous system. Cell Mol Life Sci 2020; 77:4505-4522. [PMID: 32424438 PMCID: PMC7599184 DOI: 10.1007/s00018-020-03543-6] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/13/2020] [Accepted: 04/27/2020] [Indexed: 02/06/2023]
Abstract
The enteric nervous system (ENS) is an extensive network comprising millions of neurons and glial cells contained within the wall of the gastrointestinal tract. The major functions of the ENS that have been most studied include the regulation of local gut motility, secretion, and blood flow. Other areas that have been gaining increased attention include its interaction with the immune system, with the gut microbiota and its involvement in the gut-brain axis, and neuro-epithelial interactions. Thus, the enteric circuitry plays a central role in intestinal homeostasis, and this becomes particularly evident when there are faults in its wiring such as in neurodevelopmental or neurodegenerative disorders. In this review, we first focus on the current knowledge on the cellular composition of enteric circuits. We then further discuss how enteric circuits detect and process external information, how these signals may be modulated by physiological and pathophysiological factors, and finally, how outputs are generated for integrated gut function.
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Affiliation(s)
- Candice Fung
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium
| | - Pieter Vanden Berghe
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium.
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Simulations of Myenteric Neuron Dynamics in Response to Mechanical Stretch. COMPUTATIONAL INTELLIGENCE AND NEUROSCIENCE 2020; 2020:8834651. [PMID: 33123188 PMCID: PMC7582074 DOI: 10.1155/2020/8834651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/20/2020] [Accepted: 09/25/2020] [Indexed: 12/02/2022]
Abstract
Background Intestinal sensitivity to mechanical stimuli has been studied intensively in visceral pain studies. The ability to sense different stimuli in the gut and translate these to physiological outcomes relies on the mechanosensory and transductive capacity of intrinsic intestinal nerves. However, the nature of the mechanosensitive channels and principal mechanical stimulus for mechanosensitive receptors are unknown. To be able to characterize intestinal mechanoelectrical transduction, that is, the molecular basis of mechanosensation, comprehensive mathematical models to predict responses of the sensory neurons to controlled mechanical stimuli are needed. This study aims to develop a biophysically based mathematical model of the myenteric neuron with the parameters constrained by learning from existing experimental data. Findings. The conductance-based single-compartment model was selected. The parameters in the model were optimized by using a combination of hand tuning and automated estimation. Using the optimized parameters, the model successfully predicted the electrophysiological features of the myenteric neurons with and without mechanical stimulation. Conclusions The model provides a method to predict features and levels of detail of the underlying physiological system in generating myenteric neuron responses. The model could be used as building blocks in future large-scale network simulations of intrinsic primary afferent neurons and their network.
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Koussoulas K, Gwynne RM, Foong JPP, Bornstein JC. Cholera Toxin Induces Sustained Hyperexcitability in Myenteric, but Not Submucosal, AH Neurons in Guinea Pig Jejunum. Front Physiol 2017; 8:254. [PMID: 28496413 PMCID: PMC5406514 DOI: 10.3389/fphys.2017.00254] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/10/2017] [Indexed: 01/04/2023] Open
Abstract
Background and Aims: Cholera toxin (CT)-induced hypersecretion requires activation of secretomotor pathways in the enteric nervous system (ENS). AH neurons, which have been identified as a population of intrinsic sensory neurons (ISNs), are a source of excitatory input to the secretomotor pathways. We therefore examined effects of CT in the intestinal lumen on myenteric and submucosal AH neurons. Methods: Isolated segments of guinea pig jejunum were incubated for 90 min with saline plus CT (12.5 μg/ml) or CT + neurotransmitter antagonist, or CT + tetrodotoxin (TTX) in their lumen. After washing CT away, submucosal or myenteric plexus preparations were dissected keeping circumferentially adjacent mucosa intact. Submucosal AH neurons were impaled adjacent to intact mucosa and myenteric AH neurons were impaled adjacent to, more than 5 mm from, and in the absence of intact mucosa. Neuronal excitability was monitored by injecting 500 ms current pulses through the recording electrode. Results: After CT pre-treatment, excitability of myenteric AH neurons adjacent to intact mucosa (n = 29) was greater than that of control neurons (n = 24), but submucosal AH neurons (n = 33, control n = 27) were unaffected. CT also induced excitability increases in myenteric AH neurons impaled distant from the mucosa (n = 6) or in its absence (n = 5). Coincubation with tetrodotoxin or SR142801 (NK3 receptor antagonist), but not SR140333 (NK1 antagonist) or granisetron (5-HT3 receptor antagonist) prevented the increased excitability induced by CT. Increased excitability was associated with a reduction in the characteristic AHP and an increase in the ADP of these neurons, but not a change in the hyperpolarization-activated inward current, Ih. Conclusions: CT increases excitability of myenteric, but not submucosal, AH neurons. This is neurally mediated and depends on NK3, but not 5-HT3 receptors. Therefore, CT may act to amplify the secretomotor response to CT via an increase in the activity of the afferent limb of the enteric reflex circuitry.
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Affiliation(s)
- Katerina Koussoulas
- Enteric Neuroscience Laboratory, Department of Physiology, University of MelbourneParkville, VIC, Australia
| | - Rachel M Gwynne
- Enteric Neuroscience Laboratory, Department of Physiology, University of MelbourneParkville, VIC, Australia
| | - Jaime P P Foong
- Enteric Neuroscience Laboratory, Department of Physiology, University of MelbourneParkville, VIC, Australia
| | - Joel C Bornstein
- Enteric Neuroscience Laboratory, Department of Physiology, University of MelbourneParkville, VIC, Australia
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Lomax AE, Pradhananga S, Bertrand PP. Plasticity of neuroeffector transmission during bowel inflammation 1. Am J Physiol Gastrointest Liver Physiol 2017; 312:G165-G170. [PMID: 28082285 DOI: 10.1152/ajpgi.00365.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 01/03/2017] [Accepted: 01/03/2017] [Indexed: 01/31/2023]
Abstract
Altered gastrointestinal (GI) function contributes to the debilitating symptoms of inflammatory bowel diseases (IBD). Nerve circuits contained within the gut wall and outside of the gut play important roles in modulating motility, mucosal fluid transport, and blood flow. The structure and function of these neuronal populations change during IBD. Superimposed on this plasticity is a diminished responsiveness of effector cells - smooth muscle cells, enterocytes, and vascular endothelial cells - to neurotransmitters. The net result is a breakdown in the precisely orchestrated coordination of motility, fluid secretion, and GI blood flow required for health. In this review, we consider how inflammation-induced changes to the effector innervation of these tissues, and changes to the tissues themselves, contribute to defective GI function in models of IBD. We also explore the evidence that reversing neuronal plasticity is sufficient to normalize function during IBD.
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Affiliation(s)
- Alan E Lomax
- Gastrointestinal Disease Research Unit, Queen's University, Kingston, Ontario, Canada; and
| | - Sabindra Pradhananga
- Gastrointestinal Disease Research Unit, Queen's University, Kingston, Ontario, Canada; and
| | - Paul P Bertrand
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria, Australia
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Kugler EM, Michel K, Zeller F, Demir IE, Ceyhan GO, Schemann M, Mazzuoli-Weber G. Mechanical stress activates neurites and somata of myenteric neurons. Front Cell Neurosci 2015; 9:342. [PMID: 26441520 PMCID: PMC4569744 DOI: 10.3389/fncel.2015.00342] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 08/18/2015] [Indexed: 12/24/2022] Open
Abstract
The particular location of myenteric neurons, sandwiched between the 2 muscle layers of the gut, implies that their somata and neurites undergo mechanical stress during gastrointestinal motility. Existence of mechanosensitive enteric neurons (MEN) is undoubted but many of their basic features remain to be studied. In this study, we used ultra-fast neuroimaging to record activity of primary cultured myenteric neurons of guinea pig and human intestine after von Frey hair evoked deformation of neurites and somata. Independent component analysis was applied to reconstruct neuronal morphology and follow neuronal signals. Of the cultured neurons 45% (114 out of 256, 30 guinea pigs) responded to neurite probing with a burst spike frequency of 13.4 Hz. Action potentials generated at the stimulation site invaded the soma and other neurites. Mechanosensitive sites were expressed across large areas of neurites. Many mechanosensitive neurites appeared to have afferent and efferent functions as those that responded to deformation also conducted spikes coming from the soma. Mechanosensitive neurites were also activated by nicotine application. This supported the concept of multifunctional MEN. 14% of the neurons (13 out of 96, 18 guinea pigs) responded to soma deformation with burst spike discharge of 17.9 Hz. Firing of MEN adapted rapidly (RAMEN), slowly (SAMEN), or ultra-slowly (USAMEN). The majority of MEN showed SAMEN behavior although significantly more RAMEN occurred after neurite probing. Cultured myenteric neurons from human intestine had similar properties. Compared to MEN, dorsal root ganglion neurons were activated by neurite but not by soma deformation with slow adaptation of firing. We demonstrated that MEN exhibit specific features very likely reflecting adaptation to their specialized functions in the gut.
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Affiliation(s)
- Eva M Kugler
- Human Biology, Technische Universitaet Muenchen Freising, Germany
| | - Klaus Michel
- Human Biology, Technische Universitaet Muenchen Freising, Germany
| | - Florian Zeller
- Department of Surgery, Klinikum Freising Freising, Germany
| | - Ihsan E Demir
- Department of Surgery, Klinikum Rechts der Isar, Technische Universitaet Muenchen Munich, Germany
| | - Güralp O Ceyhan
- Department of Surgery, Klinikum Rechts der Isar, Technische Universitaet Muenchen Munich, Germany
| | - Michael Schemann
- Human Biology, Technische Universitaet Muenchen Freising, Germany
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Ranson RN, Saffrey MJ. Neurogenic mechanisms in bladder and bowel ageing. Biogerontology 2015; 16:265-84. [PMID: 25666896 PMCID: PMC4361768 DOI: 10.1007/s10522-015-9554-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 01/28/2015] [Indexed: 01/18/2023]
Abstract
The prevalence of both urinary and faecal incontinence, and also chronic constipation, increases with ageing and these conditions have a major impact on the quality of life of the elderly. Management of bladder and bowel dysfunction in the elderly is currently far from ideal and also carries a significant financial burden. Understanding how these changes occur is thus a major priority in biogerontology. The functions of the bladder and terminal bowel are regulated by complex neuronal networks. In particular neurons of the spinal cord and peripheral ganglia play a key role in regulating micturition and defaecation reflexes as well as promoting continence. In this review we discuss the evidence for ageing-induced neuronal dysfunction that might predispose to neurogenic forms of incontinence in the elderly.
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Affiliation(s)
- Richard N Ranson
- Department of Applied Sciences (Biomedical Sciences), Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK,
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Brumovsky PR, La JH, Gebhart GF. Distribution across tissue layers of extrinsic nerves innervating the mouse colorectum - an in vitro anterograde tracing study. Neurogastroenterol Motil 2014; 26:1494-507. [PMID: 25185752 PMCID: PMC4200533 DOI: 10.1111/nmo.12419] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 07/27/2014] [Indexed: 01/16/2023]
Abstract
BACKGROUND Anterograde in vitro tracing of the pelvic nerve (PN) and visualization in the horizontal plane in whole mount preparations has been fundamental in the analysis of distribution of peripheral nerves innervating the colorectum. Here, we performed a similar analysis, but in cryostat sections of the mouse colorectum, allowing for a more direct visualization of nerve distribution in all tissue layers. METHODS Colorectum with attached PNs was dissected from adult male BalbC mice. Presence of active afferents was certified by single fiber recording of fine PN fibers. This was followed by 'bulk' (all fibers) anterograde tracing using biotinamide (BTA). Histo- and immunohistochemical techniques were used for visualization of BTA-positive nerves, and evaluation of co-localization with calcitonin gene-related peptide (CGRP), respectively. Tissue was analyzed using confocal microscopy on transverse or longitudinal colorectum sections. KEY RESULTS Abundant BTA-positive nerves spanning all layers of the mouse colorectum and contacting myenteric plexus neurons, distributing within the muscle layer, penetrating deeper into the organ and contacting blood vessels, submucosal plexus neurons or even penetrating the mucosa, were regularly detected. Several traced axons co-localized CGRP, supporting their afferent nature. Finally, anterograde tracing of the PN also exposed abundant BTA-positive nerves in the major pelvic ganglion. CONCLUSIONS & INFERENCES We present the patterns of innervation of extrinsic axons across layers in the mouse colorectum, including the labile mucosal layer. The proposed approach could also be useful in the analysis of associations between morphology and physiology of peripheral nerves targeting the different layers of the colorectum.
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Affiliation(s)
- Pablo R. Brumovsky
- School of Biomedical Sciences, Austral University, Pilar 1629, Buenos Aires, Argentina,CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas), Buenos Aires, Argentina,Pittsburgh Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213
| | - Jun-Ho La
- Pittsburgh Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213
| | - G. F. Gebhart
- Pittsburgh Center for Pain Research, Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213
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Ellis M, Chambers JD, Gwynne RM, Bornstein JC. Serotonin and cholecystokinin mediate nutrient-induced segmentation in guinea pig small intestine. Am J Physiol Gastrointest Liver Physiol 2013; 304:G749-61. [PMID: 23392236 DOI: 10.1152/ajpgi.00358.2012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Segmentation is an important process in nutrient mixing and absorption; however, the mechanisms underlying this motility pattern are poorly understood. Segmentation can be induced by luminal perfusion of fatty acid in guinea pig small intestine in vitro and mimicked by the serotonin (5-HT) reuptake inhibitor fluoxetine (300 nM) and by cholecystokinin (CCK). Serotonergic and CCK-related mechanisms underlying nutrient-induced segmentation were investigated using selective 5-HT and CCK receptor antagonists on isolated segments of small intestine luminally perfused with 1 mM decanoic acid. Motility patterns were analyzed using video imaging and spatiotemporal maps. Segmenting activity mediated by decanoic acid was depressed following luminal application of the 5-HT receptor antagonists granisetron (5-HT(3), 1 μM) and SB-207266 (5-HT(4), 10 nM) and the CCK receptor antagonists devazepide (CCK-1, 300 nM) and L-365260 (CCK-2, 300 nM), but these antagonists did not further depress segmentation when combined. The P2 receptor antagonist pyridoxal phosphate-6-azophenyl-2',4'-disulfonate (10 μM) had no effect on activity. Serosal application of 5-HT antagonists had little effect on segmentation in the duodenum but reduced activity in the jejunum when granisetron and SB-207266 were applied together. These results reveal that 5-HT(3) and 5-HT(4) receptors, as well as CCK-1 and CCK-2 receptors, are critical in regulating decanoic acid-induced segmentation. Computational simulation indicated that these data are consistent with decanoic acid activating two pathways in the mucosa that converge within the enteric neural circuitry, while contraction-induced release of 5-HT from the mucosa provides feedback into the neural circuit to set the time course of the overall contractile activity.
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Affiliation(s)
- Melina Ellis
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
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McVey Neufeld KA, Mao YK, Bienenstock J, Foster JA, Kunze WA. The microbiome is essential for normal gut intrinsic primary afferent neuron excitability in the mouse. Neurogastroenterol Motil 2013. [PMID: 23181420 DOI: 10.1111/nmo.12049] [Citation(s) in RCA: 199] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND The role of intestinal microbiota in the development and function of host physiology is of high interest, especially with respect to the nervous system. While strong evidence has accrued that intestinal bacteria alter host nervous system function, mechanisms by which this occurs have remained elusive. For this reason, we have carried out experiments examining the electrophysiological properties of neurons in the myenteric plexus of the enteric nervous system (ENS) in germ-free (GF) mice compared with specific pathogen-free (SPF) control mice and adult germ-free mice that have been conventionalized (CONV-GF) with intestinal bacteria. METHODS Segments of jejunum from 8 to 12 week old GF, SPF, and CONV-GF mice were dissected to expose the myenteric plexus. Intracellular recordings in current-clamp mode were made by impaling cells with sharp microelectrodes. Action potential (AP) shapes, firing thresholds, the number of APs fired at 2× threshold, and passive membrane characteristics were measured. KEY RESULTS In GF mice, excitability was decreased in myenteric afterhyperpolarization (AH) neurons as measured by a lower resting membrane potential and by the number of APs generated at 2× threshold. The post AP slow afterhyperpolarization (sAHP) was prolonged for GF compared with SPF and CONV-GF animals. Passive membrane characteristics were also altered in GF mice by a decrease in input resistance. CONCLUSIONS & INFERENCES Here, we report the novel finding that commensal intestinal microbiota are necessary for normal excitability of gut sensory neurons and thus provide a potential mechanism for the transfer of information between the microbiota and nervous system.
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Affiliation(s)
- K A McVey Neufeld
- McMaster Brain-Body Institute at St Joseph's Healthcare, Hamilton ON, Canada.
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Kondo Y, To M, Saruta J, Hayashi T, Sugiyama H, Tsukinoki K. Role of TrkB expression in rat adrenal gland during acute immobilization stress. J Neurochem 2012; 124:224-32. [PMID: 23017014 PMCID: PMC3563005 DOI: 10.1111/jnc.12030] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 09/19/2012] [Accepted: 09/19/2012] [Indexed: 11/29/2022]
Abstract
Expression of tyrosine receptor kinase B (TrkB), a receptor for brain-derived neurotrophic factor (BDNF), is markedly elevated in the adrenal medulla during immobilization stress. Catecholamine release was confirmed in vitro by stimulating chromaffin cells with recombinant BDNF. We investigated the role of TrkB and the localization of BDNF in the adrenal gland during immobilization stress for 60 min. Blood catecholamine levels increased after stimulation with TrkB expressed in the adrenal medulla during 60-min stress; however, blood catecholamine levels did not increase in adrenalectomized rats. Furthermore, expression of BDNF mRNA and protein was detected in the adrenal medulla during 60-min stress. Similarly, in rats undergoing sympathetic nerve block with propranolol, BDNF mRNA and protein were detected in the adrenal medulla during 60-min stress. These results suggest that signal transduction of TrkB in the adrenal medulla evokes catecholamine release. In addition, catecholamine release was evoked by both the hypothalamic–pituitary–adrenal axis and autocrine signaling by BDNF in the adrenal gland. BDNF–TrkB interaction may play a role in a positive feedback loop in the adrenal medulla during immobilization stress.
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Affiliation(s)
- Yusuke Kondo
- Department of Environmental Pathology and Research Institute of Salivary Gland and Health Medicine, Graduate School of Kanagawa Dental College, Yokosuka, Japan
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Kulkarni S, Zou B, Hanson J, Micci MA, Tiwari G, Becker L, Kaiser M, Xie X(S, Pasricha PJ. Gut-derived factors promote neurogenesis of CNS-neural stem cells and nudge their differentiation to an enteric-like neuronal phenotype. Am J Physiol Gastrointest Liver Physiol 2011; 301:G644-55. [PMID: 21817062 PMCID: PMC3191554 DOI: 10.1152/ajpgi.00123.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Recent studies have explored the potential of central nervous system-derived neural stem cells (CNS-NSC) to repopulate the enteric nervous system. However, the exact phenotypic fate of gut-transplanted CNS-NSC has not been characterized. The aim of this study was to investigate the effect of the gut microenvironment on phenotypic fate of CNS-NSC in vitro. With the use of Transwell culture, differentiation of mouse embryonic CNS-NSC was studied when cocultured without direct contact with mouse intestinal longitudinal muscle-myenteric plexus preparations (LM-MP) compared with control noncocultured cells, in a differentiating medium. Differentiated cells were analyzed by immunocytochemistry and quantitative RT-PCR to assess the expression of specific markers and by whole cell patch-clamp studies for functional characterization of their phenotype. We found that LM-MP cocultured cells had a significant increase in the numbers of cells that were immune reactive against the panneuronal marker β-tubulin, neurotransmitters neuronal nitric oxide synthase (nNOS), choline acetyltransferase (ChAT), and neuropeptide vasoactive intestinal peptide (VIP) and showed an increase in expression of these genes, compared with control cells. Whole cell patch-clamp analysis showed that coculture with LM-MP decreases cell excitability and reduces voltage-gated Na(+) currents but significantly enhances A-current and late afterhyperpolarization (AHP) and increases the expression of the four AHP-generating Ca(2+)-dependent K(+) channel genes (KCNN), compared with control cells. In a separate experiment, differentiation of LM-MP cocultured CNS-NSC produced a significant increase in the numbers of cells that were immune reactive against the neurotransmitters nNOS, ChAT, and the neuropeptide VIP compared with CNS-NSC differentiated similarly in the presence of neonatal brain tissue. Our results show that the gut microenvironment induces CNS-NSC to produce neurons that share some of the characteristics of classical enteric neurons, further supporting the therapeutic use of these cells for gastrointestinal disorders.
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Affiliation(s)
- Subhash Kulkarni
- 1Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California;
| | - Bende Zou
- 1Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California; ,2AfaSci Research Laboratory, Redwood City, California;
| | - Jesse Hanson
- 2AfaSci Research Laboratory, Redwood City, California; ,5Genentech, Inc., South San Francisco, California
| | - Maria-Adelaide Micci
- 3Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas;
| | - Gunjan Tiwari
- 1Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California;
| | - Laren Becker
- 1Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California;
| | - Martin Kaiser
- 4Department of Computer Science and Microsystems Technology, UAS, Kaiserlautern, Germany; and
| | - Xinmin (Simon) Xie
- 1Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California; ,2AfaSci Research Laboratory, Redwood City, California;
| | - Pankaj Jay Pasricha
- 1Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California;
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Balemba OB, Bhattarai Y, Stenkamp-Strahm C, Lesakit MSB, Mawe GM. The traditional antidiarrheal remedy, Garcinia buchananii stem bark extract, inhibits propulsive motility and fast synaptic potentials in the guinea pig distal colon. Neurogastroenterol Motil 2010; 22:1332-9. [PMID: 20718943 PMCID: PMC2975827 DOI: 10.1111/j.1365-2982.2010.01583.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Garcinia buchananii bark extract is a traditional African remedy for diarrhea, dysentery, abdominal discomfort, and pain. We investigated the mechanisms and efficacy of this extract using the guinea pig distal colon model of gastrointestinal motility. METHODS Stem bark was collected from G. buchananii trees in their natural habitat of Karagwe, Tanzania. Bark was sun dried and ground into fine powder, and suspended in Krebs to obtain an aqueous extract. Isolated guinea pig distal colon was used to determine the effect of the G. buchananii bark extract on fecal pellet propulsion. Intracellular recording was used to evaluate the extract action on evoked fast excitatory postsynaptic potentials (fEPSPs) in S-neurons of the myenteric plexus. KEY RESULTS Garcinia buchananii bark extract inhibited pellet propulsion in a concentration-dependent manner, with an optimal concentration of ∼10 mg powder per mL Krebs. Interestingly, washout of the extract resulted in an increase in pellet propulsion to a level above basal activity. The extract reversibly reduced the amplitude of evoked fEPSPs in myenteric neurons. The extract's inhibitory action on propulsive motility and fEPSPs was not affected by the opioid receptor antagonist, naloxone, or the alpha- 2 adrenoceptor antagonist, yohimbine. The extract inhibited pellet motility in the presence of gamma-aminobutyric acid (GABA), GABA(A) and GABA(B) receptor antagonists picrotoxin and phaclofen, respectively. However, phaclofen and picrotoxin inhibited recovery rebound of motility during washout. CONCLUSIONS & INFERENCES Garcinia buchananii extract has the potential to provide an effective, non-opiate antidiarrheal drug. Further studies are required to characterize bioactive components and elucidate the mechanisms of action, efficacy, and safety.
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Affiliation(s)
- O B Balemba
- Department of Biological Sciences/WWAMI, University of Idaho, Moscow, ID 83844–3051, USA.
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14
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Schemann M, Mazzuoli G. Multifunctional mechanosensitive neurons in the enteric nervous system. Auton Neurosci 2010; 153:21-5. [DOI: 10.1016/j.autneu.2009.08.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 07/28/2009] [Accepted: 08/10/2009] [Indexed: 12/28/2022]
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Abstract
The gastrointestinal (GI) tract must balance ostensibly opposite functions. On the one hand, it must undertake the process of digestion and absorption of nutrients. At the same time, the GI tract must protect itself from potential harmful antigenic and pathogenic material. Central to these processes is the ability to 'sense' the mechanical and chemical environment in the gut wall and lumen in order to orchestrate the appropriate response that facilitates nutrient assimilation or the rapid expulsion through diarrhoea and/or vomiting. In this respect, the GI tract is richly endowed with sensory elements that monitor the gut environment. Enteric neurones provide one source of such sensory innervation and are responsible for the ability of the decentralized gut to perform complex reflex functions. Extrinsic afferents not only contribute to this reflex control, but also contribute to homeostatic mechanisms and can give rise to sensations, under certain circumstances. The enteric and extrinsic sensory mechanisms share a number of common features but also some remarkably different properties. The purpose of this review is to summarize current views on sensory processing within both the enteric and extrinsic innervation and to specifically address the pharmacology of nociceptive extrinsic sensory pathways.
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Affiliation(s)
- L A Blackshaw
- Nerve Gut Research Laboratory, Hanson Institute, Royal Adelaide Hospital, University of Adelaide, Adelaide, SA, Australia
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16
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Bertrand PP. Real-time measurement of serotonin release and motility in guinea pig ileum. J Physiol 2006; 577:689-704. [PMID: 16959854 PMCID: PMC1890433 DOI: 10.1113/jphysiol.2006.117804] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Enterochromaffin (EC) cells are sensors that detect chemical or mechanical stimuli and respond with release of serotonin (5-HT). 5-HT activates local motor reflexes, but whether local motor reflexes also evoke 5-HT release is unknown. The aim of the present study was to establish the relationship between the release of 5-HT and the enteric neural circuits controlling the movements of the intestine. Recordings were made from full-thickness preparations of guinea pig ileum using electrochemical techniques with carbon fibre electrodes to measure local concentrations of 5-HT. The tension in the circular muscle (CM) and longitudinal muscle (LM) was recorded with force transducers. The release of 5-HT from the EC cells was detected selectively and the timing of the events quantified. Pressure-evoked peristalsis caused detectable 5-HT release only when the recording site was invaded by a ring of CM contraction. Spontaneous and stretch-evoked reflex contraction of the CM and LM occurred simultaneously with 5-HT release. Paralysis of the smooth muscle significantly reduced the stretch-evoked release. Muscarinic agonists evoked reflexes that were associated with increases in tension in CM and LM simultaneous with 5-HT release. Tetrodotoxin abolished the coordination between the CM contraction and 5-HT release but not the direct activation of the CM and EC cells by the agonists. In conclusion, the correlation between local motor reflexes and 5-HT release observed in the present study is caused primarily by the contraction of the smooth muscle and subsequent deformation of the mucosa. The EC cell is, thus, a site of convergence for mechanical forces that contribute to the release of 5-HT during motor reflexes.
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Affiliation(s)
- Paul P Bertrand
- Department of Physiology and Cell Biology, University of Nevada, School of Medicine, Reno, NV 89557, USA.
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Mao Y, Wang B, Kunze W. Characterization of Myenteric Sensory Neurons in the Mouse Small Intestine. J Neurophysiol 2006; 96:998-1010. [PMID: 16899648 DOI: 10.1152/jn.00204.2006] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We recorded from myenteric AH/Dogiel type II cells, demonstrated mechanosensitive responses, and characterized their basic properties. Recordings were obtained using the mouse longitudinal muscle myenteric plexus preparation with patch-clamp and sharp intracellular electrodes. The neurons had an action potential hump and a slow afterhyperpolarization (AHP) current. The slow AHP was carried by intermediate conductance Ca2+-dependent K+-channel currents sensitive to charybdotoxin and clotrimazole. All possessed a hyperpolarization-activated current that was blocked by extracellular cesium. They also expressed a TTX-resistant Na+ current with an onset near the resting potential. Pressing on the ganglion containing the patched neuron evoked depolarizing potentials in 17/18 cells. The potentials persisted after synaptic transmission was blocked. Volleys of presynaptic electrical stimuli evoked slow excitatory postsynaptic potentials (EPSPs) in 9/11 sensory neurons, but 0/29 cells received fast EPSP input. The slow EPSP was generated by removal of a voltage-insensitive K+ current. Patch-clamp recording with a KMeSO4-containing, but not a conventional KCl-rich, intracellular solution reproduced the single-spike slow AHPs and low input resistances seen with sharp intracellular recording. Cell-attached recording of intermediate conductance potassium channels supported the conclusion that the single-spike slow AHP is an intrinsic property of intestinal AH/sensory neurons. Unitary current recordings also suggested that the slow AHP current probably does not contribute significantly to the high resting background conductance seen in these cells. The characterization of mouse myenteric sensory neurons opens the way for the study of their roles in normal and pathological physiology.
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Affiliation(s)
- Yukang Mao
- Brain-Brody Institute, McMaster University, Hamilton, Ontario, Canada
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18
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Herrera-Ruiz M, González-Cortazar M, Jiménez-Ferrer E, Zamilpa A, Alvarez L, Ramírez G, Tortoriello J. Anxiolytic effect of natural galphimines from Galphimia glauca and their chemical derivatives. JOURNAL OF NATURAL PRODUCTS 2006; 69:59-61. [PMID: 16441069 DOI: 10.1021/np050305x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The anxiolytic effects of galphimine B (1), galphimine A (2), and galphimine E (3), natural nor-secofriedelanes isolated from Galphimia glauca, as well as derivatives obtained by acetylation (4), hydrogenation of the C-1/C-2 double bond (5), basic hydrolysis followed by hydrogenation of the C-1/C-2 double bond (6), and deacetylation (7) of galphimine E (3), were evaluated on ICR mice exposed to the elevated plus-maze test. This study also included the evaluation of a galphimines-rich fraction (GRF) with a known concentration of 1-3, obtained from the dry leaves of G. glauca. Intraperitoneal administration of 15 mg/kg of 1, 2, 6, and GRF (1 h before testing) caused an anxiolytic-like effect in the animals, increasing significantly (p <0.001) the percentage of time of permanence and the number of crossings toward the open arms of the plus-maze. No activity was detected after administration of compounds 3, 4, 5, and 7. These results showed that GRF had activity similar to the most active pure galphimines (1 and 2) and that, like for the spasmolytic activity previously reported, the main determining factor responsible for the anxiolytic activity of the compounds was the presence of free hydroxyl groups at C-4, C-6, and C-7 and the presence of the double bond in the A ring.
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Affiliation(s)
- Maribel Herrera-Ruiz
- Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social, Argentina No. 1, Centro, 62790 Xochitepec, Morelos, México
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