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Trevizan-Baú P, Ringuet MT, Stebbing MJ, McAllen RM, Furness JB, Mueller SN. Protocol for the isolation of the mouse sympathetic splanchnic-celiac-superior mesenteric ganglion complex. STAR Protoc 2024; 5:103036. [PMID: 38676927 PMCID: PMC11067456 DOI: 10.1016/j.xpro.2024.103036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/21/2024] [Accepted: 04/10/2024] [Indexed: 04/29/2024] Open
Abstract
Neurons that originate from pre-vertebral sympathetic ganglia, the splanchnic-celiac-superior mesenteric ganglion complex (SCSMG) in mouse, have important roles in control of organs of the upper abdomen. Here, we present a protocol for the isolation of the mouse sympathetic SCSMG. We describe steps for surgical incision, ganglia isolation, ganglia fine dissection, and whole-mount SCSMG after clearing-enhanced 3D (Ce3D) clearing method and immunohistochemistry. Given the importance of mice in studies of that control, this protocol aims to assist biomedical researchers in the dissection of the mouse SCSMG.
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Affiliation(s)
- Pedro Trevizan-Baú
- The Florey Institute, The University of Melbourne, Melbourne, VIC, Australia; Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC, Australia; Department of Physiological Sciences, University of Florida, Gainesville, FL, USA.
| | - Mitchell Ty Ringuet
- The Florey Institute, The University of Melbourne, Melbourne, VIC, Australia; Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC, Australia
| | - Martin J Stebbing
- The Florey Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Robin M McAllen
- The Florey Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - John B Furness
- The Florey Institute, The University of Melbourne, Melbourne, VIC, Australia; Department of Anatomy and Physiology, University of Melbourne, Parkville, VIC, Australia
| | - Scott N Mueller
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC, Australia.
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Di Natale MR, Hunne B, Stebbing MJ, Wang X, Liu Z, Furness JB. Characterization of neuromuscular transmission and projections of muscle motor neurons in the rat stomach. Am J Physiol Gastrointest Liver Physiol 2024; 326:G78-G93. [PMID: 37987773 PMCID: PMC11208016 DOI: 10.1152/ajpgi.00194.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/09/2023] [Accepted: 11/14/2023] [Indexed: 11/22/2023]
Abstract
The stomach is the primary reservoir of the gastrointestinal tract, where ingested content is broken down into small particles. Coordinated relaxation and contraction is essential for rhythmic motility and digestion, but how the muscle motor innervation is organized to provide appropriate graded regional control is not established. In this study, we recorded neuromuscular transmission to the circular muscle using intracellular microelectrodes to investigate the spread of the influence of intrinsic motor neurons. In addition, microanatomical investigations of neuronal projections and pharmacological analysis were conducted to investigate neuromuscular relationships. We found that inhibitory neurotransmission to the circular muscle is graded with stimulus strength and circumferential distance from the stimulation site. The influence of inhibitory neurons declined between 1 and 11 mm from the stimulation site. In the antrum, corpus, and fundus, the declines at 11 mm were about 20%, 30%, and 50%, respectively. Stimulation of inhibitory neurons elicited biphasic hyperpolarizing potentials often followed by prolonged depolarizing events in the distal stomach, but only hyperpolarizing events in the proximal stomach. Excitatory neurotransmission influence varied greatly between proximal stomach, where depolarizing events occurred, and distal stomach, where no direct electrical effects in the muscle were observed. Structural studies using microlesion surgeries confirmed a dominant circumferential projection. We conclude that motor neuron influences extend around the gastric circumference, that the effectiveness can be graded by the recruitment of different numbers of motor neuron nerve terminals to finely control gastric motility, and that the ways in which the neurons influence the muscle differ between anatomical regions.NEW & NOTEWORTHY This study provides a detailed mapping of nerve transmission to the circular muscle of the different anatomical regions of rat stomach. It shows that excitatory and inhibitory influences extend around the gastric circumference and that there is a summation of neural influence that allows for finely graded control of muscle tension and length. Nerve-mediated electrical events are qualitatively and quantitatively different between regions, for example, excitatory neurons have direct effects on fundus but not antral muscle.
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Affiliation(s)
- Madeleine R Di Natale
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Billie Hunne
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Victoria, Australia
| | - Martin J Stebbing
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Xiaokai Wang
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, United States
| | - Zhongming Liu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, United States
| | - John B Furness
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
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Mayr S, Schliep R, Elfers K, Mazzuoli-Weber G. Mechanosensitive enteric neurons in the guinea pig gastric fundus and antrum. Neurogastroenterol Motil 2023; 35:e14674. [PMID: 37702071 DOI: 10.1111/nmo.14674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 07/16/2023] [Accepted: 08/28/2023] [Indexed: 09/14/2023]
Abstract
BACKGROUND Coping with the ingested food, the gastric regions of fundus, corpus, and antrum display different motility patterns. Intrinsic components of such patterns involving mechanosensitive enteric neurons (MEN) have been described in the guinea pig gastric corpus but are poorly understood in the fundus and antrum. METHODS To elucidate mechanosensitive properties of myenteric neurons in the gastric fundus and antrum, membrane potential imaging using Di-8-ANEPPS was applied. A small-volume injection led to neuronal compression. We analyzed the number of MEN and their firing frequency in addition to the involvement of selected mechanoreceptors. To characterize the neurochemical phenotype of MEN, we performed immunohistochemistry. KEY RESULTS In the gastric fundus, 16% of the neurons reproducibly responded to mechanical stimulation and thus were MEN. Of those, 83% were cholinergic and 19% nitrergic. In the antrum, 6% of the neurons responded to the compression stimulus, equally distributed among cholinergic and nitrergic MEN. Defunctionalizing the sensory extrinsic afferents led to a significant drop in the number of MEN in both regions. CONCLUSION We provided evidence for MEN in the gastric fundus and antrum and further investigated mechanoreceptors. However, the proportions of the chemical phenotypes of the MEN differed significantly between both regions. Further investigations of synaptic connections of MEN are crucial to understand the hardwired neuronal circuits in the stomach.
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Affiliation(s)
- Sophia Mayr
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Ronja Schliep
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Kristin Elfers
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Gemma Mazzuoli-Weber
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
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Wang X, Cao J, Han K, Choi M, She Y, Scheven UM, Avci R, Du P, Cheng LK, Natale MRD, Furness JB, Liu Z. Diffeomorphic Surface Modeling for MRI-Based Characterization of Gastric Anatomy and Motility. IEEE Trans Biomed Eng 2023; 70:2046-2057. [PMID: 37018592 PMCID: PMC10443119 DOI: 10.1109/tbme.2023.3234509] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Gastrointestinal magnetic resonance imaging (MRI) provides rich spatiotemporal data about the movement of the food inside the stomach, but does not directly report muscular activity on the stomach wall. Here we describe a novel approach to characterize the motility of the stomach wall that drives the volumetric changes of the ingesta. METHODS A neural ordinary differential equation was optimized to model a diffeomorphic flow that ascribed the deformation of the stomach wall to a continuous biomechanical process. Driven by this diffeomorphic flow, the surface of the stomach progressively changes its shape over time, while preserving its topology and manifoldness. RESULTS We tested this approach with MRI data collected from 10 rats under a lightly anesthetized condition, and demonstrated accurate characterization of gastric motor events with an error in the order of sub-millimeters. Uniquely, we characterized gastric anatomy and motility with a surface coordinate system common at both individual and group levels. Functional maps were generated to reveal the spatial, temporal, and spectral characteristics of muscle activity and its coordination across different regions. The peristalsis at the distal antrum had a dominant frequency and peak-to-peak amplitude of [Formula: see text] cycles per minute and [Formula: see text] mm, respectively. The relationship between muscle thickness and gastric motility was found to be distinct between two functional regions in the proximal and distal stomach. CONCLUSION These results demonstrate the efficacy of using MRI to model gastric anatomy and function. SIGNIFICANCE The proposed approach is expected to enable non-invasive and accurate mapping of gastric motility for preclinical and clinical studies.
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Michel K, Kuch B, Dengler S, Demir IE, Zeller F, Schemann M. How big is the little brain in the gut? Neuronal numbers in the enteric nervous system of mice, Guinea pig, and human. Neurogastroenterol Motil 2022; 34:e14440. [PMID: 35929768 DOI: 10.1111/nmo.14440] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 05/23/2022] [Accepted: 07/21/2022] [Indexed: 02/08/2023]
Abstract
BACKGROUND Despite numerous studies on the enteric nervous system (ENS), we lack fundamental knowledge on neuronal densities or total neuron numbers in different species. There are more anecdotal than actual figures on nerve counts. METHODS We used standardized preparation techniques and immunohistochemistry with validated panneuronal markers (human or mouse anti-HuD/C) to determine neuronal densities in specimen from the entire gastrointestinal tract of mice, guinea pig, and humans. In parallel, we measured the dimensions of the gastrointestinal regions in mouse and guinea pig. For humans, we had to rely on literature data. KEY RESULTS The average neuronal densities along the gastrointestinal tract were 35,011 ± 25,017 1/cm2 for the myenteric and 16,685 ± 9098 1/cm2 for the submucous plexus in mice, 24,315 ± 16,627 and 11,850 ± 6122 1/cm2 for guinea pig myenteric and submucous plexus, respectively, and 21,698 ± 9492 and 16,367 ± 5655 1/cm2 for human myenteric and submucous plexus, respectively. The total number of neurons in the ENS was 2.6 million for mice, 14.6 million for guinea pig, and 168 million for human. CONCLUSIONS & INFERENCES This study reports the first comprehensive nerve cell count in mice, guinea pig, and human ENS. Neuronal densities were comparable between the three species and the differences in the total numbers of enteric neurons are likely due to body size and intestinal length. The number of enteric neurons is comparable to the number of neurons in the spinal cord for all three species.
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Affiliation(s)
- Klaus Michel
- Human Biology, Technical University of Munich, Freising, Germany
| | - Birgit Kuch
- Human Biology, Technical University of Munich, Freising, Germany
| | - Sophie Dengler
- Human Biology, Technical University of Munich, Freising, Germany
| | - Ihsan Ekin Demir
- Surgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | | | - Michael Schemann
- Human Biology, Technical University of Munich, Freising, Germany
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