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The Isolated Mouse Jejunal Afferent Nerve Assay as a Tool to Assess the Effect of Botulinum Neurotoxins in Visceral Nociception. Toxins (Basel) 2022; 14:toxins14030205. [PMID: 35324702 PMCID: PMC8953691 DOI: 10.3390/toxins14030205] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/04/2022] [Accepted: 03/08/2022] [Indexed: 12/10/2022] Open
Abstract
For the past two decades, botulinum neurotoxin A (BoNT/A) has been described as a strong candidate in the treatment of pain. With the production of modified toxins and the potential new applications at the visceral level, there is a real need for tools allowing the assessment of these compounds. In this study, we evaluated the jejunal mesenteric afferent nerve assay to investigate BoNT/A effects on visceral nociception. This ex vivo model allowed the continuous recording of neuronal activity in response to various stimuli. BoNT/A was applied intraluminally during three successive distensions, and the jejunum was distended every 15 min for 3 h. Finally, samples were exposed to external capsaicin. BoNT/A intoxication was validated at the molecular level with the presence of cleaved synaptosomal-associated protein of 25 (SNAP25) in nerve terminals in the mucosa and musculosa layers 3 h after treatment. BoNT/A had a progressive inhibitory effect on multiunit discharge frequency induced by jejunal distension, with a significant decrease from 1 h after application without change in jejunal compliance. The capsaicin-induced discharge was also affected by the toxin. This assay allowed the description of an inhibitory effect of BoNT/A on afferent nerve activity in response to distension and capsaicin, suggesting BoNT/A could alleviate visceral nociception.
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Barki N, Bolognini D, Börjesson U, Jenkins L, Riddell J, Hughes DI, Ulven T, Hudson BD, Ulven ER, Dekker N, Tobin AB, Milligan G. Chemogenetics defines a short-chain fatty acid receptor gut-brain axis. eLife 2022; 11:73777. [PMID: 35229717 PMCID: PMC8887895 DOI: 10.7554/elife.73777] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 02/10/2022] [Indexed: 12/12/2022] Open
Abstract
Volatile small molecules, including the short-chain fatty acids (SCFAs), acetate and propionate, released by the gut microbiota from the catabolism of nondigestible starches, can act in a hormone-like fashion via specific G-protein-coupled receptors (GPCRs). The primary GPCR targets for these SCFAs are FFA2 and FFA3. Using transgenic mice in which FFA2 was replaced by an altered form called a Designer Receptor Exclusively Activated by Designer Drugs (FFA2-DREADD), but in which FFA3 is unaltered, and a newly identified FFA2-DREADD agonist 4-methoxy-3-methyl-benzoic acid (MOMBA), we demonstrate how specific functions of FFA2 and FFA3 define a SCFA-gut-brain axis. Activation of both FFA2/3 in the lumen of the gut stimulates spinal cord activity and activation of gut FFA3 directly regulates sensory afferent neuronal firing. Moreover, we demonstrate that FFA2 and FFA3 are both functionally expressed in dorsal root- and nodose ganglia where they signal through different G proteins and mechanisms to regulate cellular calcium levels. We conclude that FFA2 and FFA3, acting at distinct levels, provide an axis by which SCFAs originating from the gut microbiota can regulate central activity.
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Affiliation(s)
- Natasja Barki
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Daniele Bolognini
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Ulf Börjesson
- Discovery Sciences, Biopharmaceutical R&D, AstraZeneca, Gothenburg, Sweden
| | - Laura Jenkins
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - John Riddell
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - David I Hughes
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Trond Ulven
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken, Copenhagen, Denmark
| | - Brian D Hudson
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Elisabeth Rexen Ulven
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken, Copenhagen, Denmark
| | - Niek Dekker
- Discovery Sciences, Biopharmaceutical R&D, AstraZeneca, Gothenburg, Sweden
| | - Andrew B Tobin
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Graeme Milligan
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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West CL, Neufeld KAM, Mao YK, Stanisz AM, Forsythe P, Bienenstock J, Barbut D, Zasloff M, Kunze WA. Identification of SSRI-evoked antidepressant sensory signals by decoding vagus nerve activity. Sci Rep 2021; 11:21130. [PMID: 34702901 PMCID: PMC8548562 DOI: 10.1038/s41598-021-00615-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/11/2021] [Indexed: 12/25/2022] Open
Abstract
The vagus nerve relays mood-altering signals originating in the gut lumen to the brain. In mice, an intact vagus is required to mediate the behavioural effects of both intraluminally applied selective serotonin reuptake inhibitors and a strain of Lactobacillus with antidepressant-like activity. Similarly, the prodepressant effect of lipopolysaccharide is vagus nerve dependent. Single vagal fibres are broadly tuned to respond by excitation to both anti- and prodepressant agents, but it remains unclear how neural responses encode behaviour-specific information. Here we demonstrate using ex vivo experiments that for single vagal fibres within the mesenteric neurovascular bundle supplying the mouse small intestine, a unique neural firing pattern code is common to both chemical and bacterial vagus-dependent antidepressant luminal stimuli. This code is qualitatively and statistically discernible from that evoked by lipopolysaccharide, a non-vagus-dependent antidepressant or control non-antidepressant Lactobacillus strain and are not affected by sex status. We found that all vagus dependent antidepressants evoked a decrease in mean spike interval, increase in spike burst duration, decrease in gap duration between bursts and increase in intra-burst spike intervals. Our results offer a novel neuronal electrical perspective as one explanation for mechanisms of action of gut-derived vagal dependent antidepressants. We expect that our ex vivo individual vagal fibre recording model will improve the design and operation of new, extant electroceutical vagal stimulation devices currently used to treat major depression. Furthermore, use of this vagal antidepressant code should provide a valuable screening tool for novel potential oral antidepressant candidates in preclinical animal models.
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Affiliation(s)
- Christine L West
- Brain-Body Institute, St. Joseph's Healthcare, Hamilton, ON, Canada.,Department of Biology, McMaster University, Hamilton, ON, Canada
| | - Karen-Anne McVey Neufeld
- Brain-Body Institute, St. Joseph's Healthcare, Hamilton, ON, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Yu-Kang Mao
- Brain-Body Institute, St. Joseph's Healthcare, Hamilton, ON, Canada
| | - Andrew M Stanisz
- Brain-Body Institute, St. Joseph's Healthcare, Hamilton, ON, Canada
| | - Paul Forsythe
- Brain-Body Institute, St. Joseph's Healthcare, Hamilton, ON, Canada.,Department of Medicine, McMaster University, Hamilton, ON, Canada.,Firestone Institute for Respiratory Health, St. Joseph's Healthcare, Hamilton, ON, Canada
| | - John Bienenstock
- Brain-Body Institute, St. Joseph's Healthcare, Hamilton, ON, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.,Department of Medicine, McMaster University, Hamilton, ON, Canada
| | | | - Michael Zasloff
- Enterin, Inc., Philadelphia, PA, USA.,MedStar-Georgetown Transplant Institute, Georgetown University School of Medicine, Washington, DC, USA
| | - Wolfgang A Kunze
- Brain-Body Institute, St. Joseph's Healthcare, Hamilton, ON, Canada. .,Department of Biology, McMaster University, Hamilton, ON, Canada. .,Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada.
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Grayson M, Nagle-Pinkham D, Gokhman D, Ruparel S. Automated analyses for single-fiber electrophysiological recordings using a newly developed Microsoft Excel application and graphical user interface. J Neurosci Methods 2021; 362:109312. [PMID: 34371025 DOI: 10.1016/j.jneumeth.2021.109312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 07/30/2021] [Accepted: 08/03/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND Electrophysiological recordings of isolated sensory afferents are commonly used in the field of pain research to investigate peripheral mechanisms of nociception in various pain models. The method involves skillful and tedious recordings of teased fibers from nerve preparations as well as time-consuming post-recording analyses. To increase efficiency and productivity of data analyses of recorded action potentials, we developed and validated a novel, easy-to-use Microsoft Excel-based application using Visual Basic Programming. NEW METHOD A code for the novel program, shigraspike1.0, was written to create a module to include customizable subroutines for analyses for electrical and mechanical responses. Using previously recorded action potentials with tongue-lingual nerve preparations, the program was validated for appropriate execution, ease-of-use, accuracy of the output data and time taken for analyses. RESULTS We observed appropriate execution of shigraspike1.0 on Windows and iOS desktop platforms that included computation of response latency of the spike of interest using electrical stimulus as well as estimation of the number of impulses at each force with a step-and-hold mechanical ramp of 10-200mN. Output data obtained by shigrapsike1.0 for both stimulus types were accurate and statistically insignificant from manual analyses. COMPARISON WITH EXISTING METHOD The novel application shigraspike1.0, allows for rapid analyses for single-fiber recordings and takes less than half the time to analyze electrical and mechanical responses compared to manual analyses. CONCLUSIONS The newly developed shigraspike1.0 application can be a very productive tool to be routinely used for efficient analyses of single-fiber electrophysiology in pain research.
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Affiliation(s)
- Max Grayson
- Department of Endodontics, University of Texas Health San Antonio, TX, USA
| | | | - Dmitry Gokhman
- Department of Mathematics, University of Texas at San Antonio, TX, USA
| | - Shivani Ruparel
- Department of Endodontics, University of Texas Health San Antonio, TX, USA.
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Gehwolf P, Renz O, Brenner E, Cardini B, Lorenz A, Wykypiel H. Laparoscopic fundoplication and new aspects of neural anatomy at the oesophagogastric junction. BJS Open 2020; 4:400-404. [PMID: 32134571 PMCID: PMC7260418 DOI: 10.1002/bjs5.50271] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Accepted: 02/03/2020] [Indexed: 11/23/2022] Open
Abstract
Background In fundoplication, mobilization of the distal oesophagus and proximal stomach is essential to obtain a sufficient tension‐free intra‐abdominal oesophageal length for creation of an efficient antireflux barrier. Most surgical literature and anatomical illustrations do not describe nerve branches running from the diaphragm to the stomach. After observing small nerve branches at laparoscopic fundoplication, penetrating the left crus of the diaphragm lateral to the hiatus and apparently running into the stomach, an anatomical cadaver study was undertaken to identify the origin and target organ of these nerves. Methods Fifty‐three human cadavers (23 men, 30 women; age range 35–103 years) were dissected with special attention to the nerves that penetrate the left crus of the diaphragm. The entire course of these nerves was documented with standardized drawings and photos. Results Small nerve branches penetrating the diaphragm lateral to the left crus of the hiatus were found in 17 (32 per cent) of the 53 cadavers. In 14 of these 17 cadavers, one or two splanchnic nerve branches were identified, and in ten of the 17 the nerve branches were found to be phrenic nerves. In seven of these 17 cadavers, two different nerve branches were found and assigned to both splanchnic and phrenic nerves. Conclusion Nerves penetrating the left crus with splanchnic origin or phrenic origin have been identified. Their function remains unclear and their relationship to postfundoplication symptoms remains to be determined.
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Affiliation(s)
- P Gehwolf
- Department of Visceral, Transplant and Thoracic Surgery, Centre for Operative Medicine, Innsbruck, Austria
| | - O Renz
- Department of Visceral, Transplant and Thoracic Surgery, Centre for Operative Medicine, Innsbruck, Austria
| | - E Brenner
- Department of Anatomy, Histology and Embryology, Division of Clinical and Functional Anatomy, Medical University of Innsbruck, Innsbruck, Austria
| | - B Cardini
- Department of Visceral, Transplant and Thoracic Surgery, Centre for Operative Medicine, Innsbruck, Austria
| | - A Lorenz
- Department of Visceral, Transplant and Thoracic Surgery, Centre for Operative Medicine, Innsbruck, Austria
| | - H Wykypiel
- Department of Visceral, Transplant and Thoracic Surgery, Centre for Operative Medicine, Innsbruck, Austria
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Meng Y, Dong L, Sun B, Luo P, Zhang G, Rong W. In Vitro Characterization of the Electrophysiological Properties of Colonic Afferent Fibers in Rats. J Vis Exp 2017. [PMID: 28994815 DOI: 10.3791/56090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Dysfunction of the colonic sensory nerves has been implicated in the pathophysiology of several common conditions, including functional and inflammatory bowel diseases and diabetes. Here, we describe a protocol for the in vitro characterization of the electrophysiological properties of colonic afferents in rats. The colorectum, with the intact pelvic ganglion (PG) attached, is removed from the rat; superfused with carbogenated Krebs solution in the recording chamber; and cannulated at the oral and anal ends to allow for distension. A fine nerve bundle emanating from the PG is identified, and the multiunit afferent nerve activity is recorded using a suction electrode. Distension of the colonic segment elicits gradual increases in multiunit discharge. A principal component analysis is conducted to differentiate the low-threshold, the high-threshold, and the wide-dynamic range afferent fibers. Chemical sensitivity of colonic afferents can be studied through the bath or intraluminal administration of test compounds. This protocol can be modified for application to other species, such as mice and guinea pigs, and to study the differences in the electrophysiological properties of thoracolumbar/hypogastric and lumbosacral/pelvic afferents of the descending colon in normal and pathological conditions.
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Affiliation(s)
- Youqiang Meng
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Li Dong
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Biying Sun
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Ping Luo
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Guohua Zhang
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine
| | - Weifang Rong
- Hongqiao International Institute of Medical Research, Tongren Hospital and Department of Physiology, Faculty of Basic Medical Sciences, Shanghai Jiaotong University School of Medicine;
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