1
|
Parkar N, Spencer NJ, Wiklendt L, Olson T, Young W, Janssen P, McNabb WC, Dalziel JE. Novel insights into mechanisms of inhibition of colonic motility by loperamide. Front Neurosci 2024; 18:1424936. [PMID: 39268036 PMCID: PMC11390470 DOI: 10.3389/fnins.2024.1424936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 08/05/2024] [Indexed: 09/15/2024] Open
Abstract
Background It is well known that opiates slow gastrointestinal (GI) transit, via suppression of enteric cholinergic neurotransmission throughout the GI tract, particularly the large intestine where constipation is commonly induced. It is not clear whether there is uniform suppression of enteric neurotransmission and colonic motility across the full length of the colon. Here, we investigated whether regional changes in colonic motility occur using the peripherally-restricted mu opioid agonist, loperamide to inhibit colonic motor complexes (CMCs) in isolated mouse colon. Methods High-resolution video imaging was performed to monitor colonic wall diameter on isolated whole mouse colon. Regional changes in the effects of loperamide on the pattern generator underlying cyclical CMCs and their propagation across the full length of large intestine were determined. Results The sensitivity of CMCs to loperamide across the length of colon varied significantly. Although there was a dose-dependent inhibition of CMCs with increasing concentrations of loperamide (10 nM - 1 μM), a major observation was that in the mid and distal colon, CMCs were abolished at low doses of loperamide (100 nM), while in the proximal colon, CMCs persisted at the same low concentration, albeit at a significantly slower frequency. Propagation velocity of CMCs was significantly reduced by 46%. The inhibitory effects of loperamide on CMCs were reversed by naloxone (1 μM). Naloxone alone did not change ongoing CMC characteristics. Discussion The results show pronounced differences in the inhibitory action of loperamide across the length of large intestine. The most potent effect of loperamide to retard colonic transit occurred between the proximal colon and mid/distal regions of colon. One of the possibilities as to why this occurs is because the greatest density of mu opioid receptors are located on interneurons responsible for neuro-neuronal transmission underlying CMCs propagation between the proximal and mid/distal colon. The absence of effect of naloxone alone on CMC characteristics suggest that the mu opioid receptor has little ongoing constitutive activity under our recording conditions.
Collapse
Affiliation(s)
- Nabil Parkar
- AgResearch, Palmerston North, New Zealand
- Riddet Institute, Massey University, Palmerston North, New Zealand
- School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand
| | - Nick J Spencer
- College of Medicine and Public Health, Flinders Health and Medical Research Institute, Adelaide, SA, Australia
| | - Luke Wiklendt
- College of Medicine and Public Health, Flinders Health and Medical Research Institute, Adelaide, SA, Australia
| | | | - Wayne Young
- AgResearch, Palmerston North, New Zealand
- Riddet Institute, Massey University, Palmerston North, New Zealand
| | - Patrick Janssen
- School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand
| | - Warren C McNabb
- Riddet Institute, Massey University, Palmerston North, New Zealand
| | - Julie E Dalziel
- AgResearch, Palmerston North, New Zealand
- Riddet Institute, Massey University, Palmerston North, New Zealand
| |
Collapse
|
2
|
Yeoman MS, Fidalgo S, Hobby I, Hafeez A, Ranson RN, Saffrey MJ, Patel BA. Decreases in mucosally-evoked tachykinin signaling pathways can explain age-related reductions in murine colonic motility patterns. Neurogastroenterol Motil 2024:e14891. [PMID: 39155460 DOI: 10.1111/nmo.14891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 06/19/2024] [Accepted: 07/29/2024] [Indexed: 08/20/2024]
Abstract
BACKGROUND Increasing age increases the incidence of chronic constipation and fecal impaction. The contribution of the natural aging process to this phenotype is unclear. This study explored the effects of age on key motility patterns in the murine colon and determined the contribution that altered neurokinin 2 (NK2) -mediated signaling made to the aging phenotype. METHODS Mucosal reflexes, colonic migrating motor complexes (CMMCs) and colonic motility assays were explored in isolated ex vivo colons from 3, 12-14, 18- and 24-months old mice and the NK2-mediated response determined. Electrical field stimulation (EFS) or exogenous drug application were used to explore the role of the mucosa in colonic segments. KEY RESULTS Aging reduced the force of contraction of the distal colon mucosal reflex, the frequency and force of contraction of CMMCs and the NK2-mediated component of both motility patterns. Ondansetron, a 5-HT3 receptor antagonist, blocked a component of both motility patterns in full thickness but not in mucosa-free segments of the distal colon. 5, hydroxytryptamine (5-HT) and EFS-evoked NK2-dependent contractions were reduced with increasing age. Smooth muscle sensitivity to 5-HT or neurokinin A (NKA) was not altered with age. In isolated colon motility assays application of NKA decreased transit time in 24-months colon and the NK2 antagonist GR159897 increased transit times in both 3- and 24-months old colons. CONCLUSIONS AND INFERENCES Aging impairs key motility patterns in the murine colon. These changes involve a decrease in mucosally-evoked NK2-mediated signaling. Targeting NK2-mediated signaling may provide a novel approach to treating age-related motility disorders in the lower bowel.
Collapse
Affiliation(s)
- Mark S Yeoman
- Centre for Lifelong Health, School of Applied Sciences, University of Brighton, Brighton, UK
| | - Sara Fidalgo
- Centre for Lifelong Health, School of Applied Sciences, University of Brighton, Brighton, UK
| | - India Hobby
- Centre for Lifelong Health, School of Applied Sciences, University of Brighton, Brighton, UK
| | - Ali Hafeez
- Centre for Lifelong Health, School of Applied Sciences, University of Brighton, Brighton, UK
| | - Rachel N Ranson
- Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - M Jill Saffrey
- Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Bhavik Anil Patel
- Centre for Lifelong Health, School of Applied Sciences, University of Brighton, Brighton, UK
| |
Collapse
|
3
|
Knez E, Kadac-Czapska K, Grembecka M. The importance of food quality, gut motility, and microbiome in SIBO development and treatment. Nutrition 2024; 124:112464. [PMID: 38657418 DOI: 10.1016/j.nut.2024.112464] [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: 04/05/2023] [Revised: 03/18/2024] [Accepted: 04/04/2024] [Indexed: 04/26/2024]
Abstract
The prevalence of small intestinal bacterial overgrowth (SIBO) is rising worldwide, particularly in nations with high rates of urbanization. Irritable bowel syndrome, inflammatory bowel illnesses, and nonspecific dysmotility are strongly linked to SIBO. Moreover, repeated antibiotic therapy promotes microorganisms' overgrowth through the development of antibiotic resistance. The primary cause of excessive fermentation in the small intestine is a malfunctioning gastrointestinal motor complex, which results in the gut's longer retention of food residues. There are anatomical and physiological factors affecting the functioning of the myoelectric motor complex. Except for them, diet conditions the activity of gastrointestinal transit. Indisputably, the Western type of nutrition is unfavorable. Some food components have greater importance in the functioning of the gastrointestinal motor complex than others. Tryptophan, an essential amino acid and precursor of the serotonin hormone, accelerates intestinal transit, and gastric emptying, similarly to fiber and polyphenols. Additionally, the effect of food on the microbiome is important, and diet should prevent bacterial overgrowth and exhibit antimicrobial effects against pathogens. Therefore, knowledge about proper nutrition is essential to prevent the development and recurrence of SIBO. Since the scientific world was unsure whether there was a long-term or potential solution for SIBO until quite recently, research on a number of the topics included in the article should be performed. The article aimed to summarize current knowledge about proper nutrition after SIBO eradication and the prevention of recurrent bacterial overgrowth. Moreover, a connection was found between diet, gut dysmotility, and SIBO.
Collapse
Affiliation(s)
- Eliza Knez
- Department of Bromatology, Medical University of Gdańsk, Gdańsk, Poland
| | | | | |
Collapse
|
4
|
Spencer NJ, Kyloh MA, Travis L, Hibberd TJ. Identification of vagal afferent nerve endings in the mouse colon and their spatial relationship with enterochromaffin cells. Cell Tissue Res 2024; 396:313-327. [PMID: 38383905 PMCID: PMC11144134 DOI: 10.1007/s00441-024-03879-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 02/13/2024] [Indexed: 02/23/2024]
Abstract
Understanding how the gut communicates with the brain, via sensory nerves, is of significant interest to medical science. Enteroendocrine cells (EEC) that line the mucosa of the gastrointestinal tract release neurochemicals, including the largest quantity of 5-hydroxytryptamine (5-HT). How the release of substances, like 5-HT, from enterochromaffin (EC) cells activates vagal afferent nerve endings is unresolved. We performed anterograde labelling from nodose ganglia in vivo and identified vagal afferent axons and nerve endings in the mucosa of whole-mount full-length preparations of mouse colon. We then determined the spatial relationship between mucosal-projecting vagal afferent nerve endings and EC cells in situ using 3D imaging. The mean distances between vagal afferent nerve endings in the mucosa, or nearest varicosities along vagal afferent axon branches, and the nearest EC cell were 29.6 ± 19.2 μm (n = 107, N = 6) and 25.7 ± 15.2 μm (n = 119, N = 6), respectively. No vagal afferent endings made close contacts with EC cells. The distances between EC cells and vagal afferent endings are many hundreds of times greater than known distances between pre- and post-synaptic membranes (typically 10-20 nm) that underlie synaptic transmission in vertebrates. The absence of any close physical contacts between 5-HT-containing EC cells and vagal afferent nerve endings in the mucosa leads to the inescapable conclusion that the mechanism by which 5-HT release from ECs in the colonic mucosa occurs in a paracrine fashion, to activate vagal afferents.
Collapse
Affiliation(s)
- Nick J Spencer
- Visceral Neurophysiology Laboratory, Flinders Health and Medical Research Institute & College of Medicine and Public Health, Flinders University of South Australia, GPO Box 2100, Bedford Park, Adelaide, South Australia, 5042, Australia.
| | - Melinda A Kyloh
- Visceral Neurophysiology Laboratory, Flinders Health and Medical Research Institute & College of Medicine and Public Health, Flinders University of South Australia, GPO Box 2100, Bedford Park, Adelaide, South Australia, 5042, Australia
| | - Lee Travis
- Visceral Neurophysiology Laboratory, Flinders Health and Medical Research Institute & College of Medicine and Public Health, Flinders University of South Australia, GPO Box 2100, Bedford Park, Adelaide, South Australia, 5042, Australia
| | - Timothy J Hibberd
- Visceral Neurophysiology Laboratory, Flinders Health and Medical Research Institute & College of Medicine and Public Health, Flinders University of South Australia, GPO Box 2100, Bedford Park, Adelaide, South Australia, 5042, Australia
| |
Collapse
|
5
|
Kaniecki T, Hughes M, McMahan Z. Managing gastrointestinal manifestations in systemic sclerosis, a mechanistic approach. Expert Rev Clin Immunol 2024; 20:603-622. [PMID: 38406978 PMCID: PMC11098704 DOI: 10.1080/1744666x.2024.2320205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 02/14/2024] [Indexed: 02/27/2024]
Abstract
INTRODUCTION Systemic sclerosis (SSc) is a connective tissue disease with heterogeneous presentation. Gastrointestinal (GI) complications of SSc are characterized by esophageal reflux, abnormal motility, and microbiome dysbiosis, which impact patient quality of life and mortality. Preventative therapeutics are lacking, with management primarily aimed at symptomatic control. AREAS COVERED A broad literature review was conducted through electronic databases and references from key articles. We summarize the physiology of gastric acid production and GI motility to provide context for existing therapies, detail the current understanding of SSc-GI disease, and review GI medications studied in SSc. Finally, we explore new therapeutic options. We propose a management strategy that integrates data on drug efficacy with knowledge of disease pathophysiology, aiming to optimize future therapeutic targets. EXPERT OPINION SSc-GI complications remain a challenge for patients, clinicians, and investigators alike. Management presently focuses on treating symptoms and minimizing mucosal damage. Little evidence exists to suggest immunosuppressive therapy halts progression of GI involvement or reverses damage, leaving many unanswered questions about the optimal clinical approach. Further research focused on identifying patients at risk for GI progression, and the underlying mechanism(s) that drive disease will provide opportunities to prevent long-term damage, and significantly improve patient quality of life.
Collapse
Affiliation(s)
- Timothy Kaniecki
- Division of Rheumatology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Michael Hughes
- Department of Rheumatology, Northern Care Alliance NHS Foundation Trust, Salford Care Organisation, Salford, US
- Division of Musculoskeletal and Dermatological Sciences, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK
| | - Zsuzsanna McMahan
- Division of Rheumatology, UTHealth Houston McGovern Medical School, Houston, TX
| |
Collapse
|
6
|
Chen W, Chen Q, Huang J, Shen X, Zhang L, Jiang G, Wu T, Wang F, Cheng X. Huanglian-banxia promotes gastric motility of diabetic rats by modulating brain-gut neurotransmitters through MAPK signaling pathway. Neurogastroenterol Motil 2024; 36:e14779. [PMID: 38488234 DOI: 10.1111/nmo.14779] [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: 04/20/2023] [Revised: 11/13/2023] [Accepted: 03/02/2024] [Indexed: 04/25/2024]
Abstract
BACKGROUND Gastric motility disorder is an increasingly common problem among people with diabetes. Neurotransmitters have been recognized as critical regulators in the process of gastric motility. Previous study has shown that herb pair huanglian-banxia (HL-BX) can improve gastric motility, but the underlying mechanism is still unclear. The aim of this study was to further investigate the role of HL-BX in modulating brain-gut neurotransmission to promote gastric motility in diabetic rats, and to explore its possible mechanism. METHODS The diabetic rats were divided into five groups. Gastric emptying rate, intestinal propulsion rate, body weight, and average food intake were determined. Substance P (SP), 5- hydroxytryptamine (5-HT), and glucagon-like peptide -1 (GLP-1) in the serum were measured by enzyme-linked immunosorbent assay. Dopamine (DA) and norepinephrine (NE) in the brain were analyzed by high-pressure liquid chromatography with a fluorescence detector. Protein expression of the tissues in the stomach and brain was determined by Western blot. KEY RESULTS HL-BX reduced average food intake significantly, increased body weight, and improved gastric emptying rate and intestinal propulsion rate. HL-BX administration caused a significant increase in SP, GLP-1, and 5-HT, but a significant decrease in DA and NE. Interestingly, HL-BX regulated simultaneously the different expressions of MAPK and its downstream p70S6K/S6 signaling pathway in the stomach and brain. Moreover, berberine exhibited a similar effect to HL-BX. CONCLUSIONS These results indicated that HL-BX promoted gastric motility by regulating brain-gut neurotransmitters through the MAPK signaling pathway. HL-BX and MAPK provide a potential therapeutic option for the treatment of gastroparesis.
Collapse
Affiliation(s)
- Wei Chen
- Central Laboratory, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, Jiangsu, China
- Clinical Pharmaceutical Laboratory of Traditional Chinese Medicine, Suzhou Academy of Wumen Chinese Medicine, Suzhou, Jiangsu, China
| | - Qiong Chen
- Central Laboratory, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, Jiangsu, China
- Clinical Pharmaceutical Laboratory of Traditional Chinese Medicine, Suzhou Academy of Wumen Chinese Medicine, Suzhou, Jiangsu, China
| | - Jiayi Huang
- Central Laboratory, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, Jiangsu, China
- Clinical Pharmaceutical Laboratory of Traditional Chinese Medicine, Suzhou Academy of Wumen Chinese Medicine, Suzhou, Jiangsu, China
| | - Xianmin Shen
- Department of Gastroenterology, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, Jiangsu, China
| | - Lurong Zhang
- Central Laboratory, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, Jiangsu, China
- Clinical Pharmaceutical Laboratory of Traditional Chinese Medicine, Suzhou Academy of Wumen Chinese Medicine, Suzhou, Jiangsu, China
| | - Guorong Jiang
- Central Laboratory, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, Jiangsu, China
- Clinical Pharmaceutical Laboratory of Traditional Chinese Medicine, Suzhou Academy of Wumen Chinese Medicine, Suzhou, Jiangsu, China
| | - Tingting Wu
- Department of Gastroenterology, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, Jiangsu, China
| | - Fei Wang
- Central Laboratory, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, Jiangsu, China
- Clinical Pharmaceutical Laboratory of Traditional Chinese Medicine, Suzhou Academy of Wumen Chinese Medicine, Suzhou, Jiangsu, China
| | - Xudong Cheng
- Department of Pharmacy, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, Jiangsu, China
| |
Collapse
|
7
|
Raouf Z, Steinway SN, Scheese D, Lopez CM, Duess JW, Tsuboi K, Sampah M, Klerk D, El Baassiri M, Moore H, Tragesser C, Prindle T, Wang S, Wang M, Jang HS, Fulton WB, Sodhi CP, Hackam DJ. Colitis-Induced Small Intestinal Hypomotility Is Dependent on Enteroendocrine Cell Loss in Mice. Cell Mol Gastroenterol Hepatol 2024; 18:53-70. [PMID: 38438014 PMCID: PMC11127033 DOI: 10.1016/j.jcmgh.2024.02.017] [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: 09/20/2023] [Revised: 02/23/2024] [Accepted: 02/26/2024] [Indexed: 03/06/2024]
Abstract
BACKGROUND & AIMS The abdominal discomfort experienced by patients with colitis may be attributable in part to the presence of small intestinal dysmotility, yet mechanisms linking colonic inflammation with small-bowel motility remain largely unexplored. We hypothesize that colitis results in small intestinal hypomotility owing to a loss of enteroendocrine cells (EECs) within the small intestine that can be rescued using serotonergic-modulating agents. METHODS Male C57BL/6J mice, as well as mice that overexpress (EECOVER) or lack (EECDEL) NeuroD1+ enteroendocrine cells, were exposed to dextran sulfate sodium (DSS) colitis (2.5% or 5% for 7 days) and small intestinal motility was assessed by 70-kilodalton fluorescein isothiocyanate-dextran fluorescence transit. EEC number and differentiation were evaluated by immunohistochemistry, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining, and quantitative reverse-transcriptase polymerase chain reaction. Mice were treated with the 5-hydroxytryptamine receptor 4 agonist prucalopride (5 mg/kg orally, daily) to restore serotonin signaling. RESULTS DSS-induced colitis was associated with a significant small-bowel hypomotility that developed in the absence of significant inflammation in the small intestine and was associated with a significant reduction in EEC density. EEC loss occurred in conjunction with alterations in the expression of key serotonin synthesis and transporter genes, including Tph1, Ddc, and Slc6a4. Importantly, mice overexpressing EECs revealed improved small intestinal motility, whereas mice lacking EECs had worse intestinal motility when exposed to DSS. Finally, treatment of DSS-exposed mice with the 5-hydroxytryptamine receptor 4 agonist prucalopride restored small intestinal motility and attenuated colitis. CONCLUSIONS Experimental DSS colitis induces significant small-bowel dysmotility in mice owing to enteroendocrine loss that can be reversed by genetic modulation of EEC or administering serotonin analogs, suggesting novel therapeutic approaches for patients with symptomatic colitis.
Collapse
Affiliation(s)
- Zachariah Raouf
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Steve N Steinway
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Daniel Scheese
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Carla M Lopez
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Johannes W Duess
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Koichi Tsuboi
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Maame Sampah
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Daphne Klerk
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mahmoud El Baassiri
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hannah Moore
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Cody Tragesser
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Thomas Prindle
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sanxia Wang
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Menghan Wang
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hee-Seong Jang
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - William B Fulton
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chhinder P Sodhi
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
| | - David J Hackam
- Division of Pediatric Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
| |
Collapse
|
8
|
Londregan A, Alexander TD, Covarrubias M, Waldman SA. Fundamental Neurochemistry Review: The role of enteroendocrine cells in visceral pain. J Neurochem 2023; 167:719-732. [PMID: 38037432 PMCID: PMC10917140 DOI: 10.1111/jnc.16022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/03/2023] [Accepted: 11/15/2023] [Indexed: 12/02/2023]
Abstract
While visceral pain is commonly associated with disorders of the gut-brain axis, underlying mechanisms are not fully understood. Dorsal root ganglion (DRG) neurons innervate visceral structures and undergo hypersensitization in inflammatory models. The characterization of peripheral DRG neuron terminals is an active area of research, but recent work suggests that they communicate with enteroendocrine cells (EECs) in the gut. EECs sense stimuli in the intestinal lumen and communicate information to the brain through hormonal and electrical signaling. In that context, EECs are a target for developing therapeutics to treat visceral pain. Linaclotide is an FDA-approved treatment for chronic constipation that activates the intestinal membrane receptor guanylyl cyclase C (GUCY2C). Clinical trials revealed that linaclotide relieves both constipation and visceral pain. We recently demonstrated that the analgesic effect of linaclotide reflects the overexpression of GUCY2C on neuropod cells, a specialized subtype of EECs. While this brings some clarity to the relationship between linaclotide and visceral analgesia, questions remain about the intracellular signaling mechanisms and neurotransmitters mediating this communication. In this Fundamental Neurochemistry Review, we discuss what is currently known about visceral nociceptors, enteroendocrine cells, and the gut-brain axis, and ongoing areas of research regarding that axis and visceral pain.
Collapse
Affiliation(s)
- Annie Londregan
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Tyler D. Alexander
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
- Vicki & Jack Farber Institute of Neuroscience at Jefferson Health, Philadelphia, Pennsylvania 19107
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Manuel Covarrubias
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
- Vicki & Jack Farber Institute of Neuroscience at Jefferson Health, Philadelphia, Pennsylvania 19107
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Scott A. Waldman
- Department of Pharmacology, Physiology, and Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| |
Collapse
|
9
|
Tough IR, Lund ML, Patel BA, Schwartz TW, Cox HM. Paracrine relationship between incretin hormones and endogenous 5-hydroxytryptamine in the small and large intestine. Neurogastroenterol Motil 2023; 35:e14589. [PMID: 37010838 PMCID: PMC10909488 DOI: 10.1111/nmo.14589] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 02/13/2023] [Accepted: 03/21/2023] [Indexed: 04/04/2023]
Abstract
BACKGROUND Enterochromaffin (EC) cell-derived 5-hydroxytryptamine (5-HT) is a mediator of toxin-induced reflexes, initiating emesis via vagal and central 5-HT3 receptors. The amine is also involved in gastrointestinal (GI) reflexes that are prosecretory and promotile, and recently 5-HT's roles in chemosensation in the distal bowel have been described. We set out to establish the efficacy of 5-HT signaling, local 5-HT levels and pharmacology in discrete regions of the mouse small and large intestine. We also investigated the inter-relationships between incretin hormones, glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) and endogenous 5-HT in mucosal and motility assays. METHODS Adult mouse GI mucosae were mounted in Ussing chambers and area-specific studies were performed to establish the 5-HT3 and 5-HT4 pharmacology, the sidedness of responses, and the inter-relationships between incretins and endogenous 5-HT. Natural fecal pellet transit in vitro and full-length GI transit in vivo were also measured. KEY RESULTS We observed the greatest level of tonic and exogenous 5-HT-induced ion transport and highest levels of 5-HT in ascending colon mucosa. Here both 5-HT3 and 5-HT4 receptors were involved but elsewhere in the GI tract epithelial basolateral 5-HT4 receptors mediate 5-HT's prosecretory effect. Exendin-4 and GIP induced 5-HT release in the ascending colon, while L cell-derived PYY also contributed to GIP mucosal effects in the descending colon. Both peptides slowed colonic transit. CONCLUSIONS & INFERENCES We provide functional evidence for paracrine interplay between 5-HT, GLP-1 and GIP, particularly in the colonic mucosal region. Basolateral epithelial 5-HT4 receptors mediated both 5-HT and incretin mucosal responses in healthy colon.
Collapse
Affiliation(s)
- Iain R. Tough
- Wolfson Centre for Age‐Related Diseases, Institute of Psychology, Psychiatry and NeuroscienceKing's College LondonHodgkin Building, Guy's CampusLondonSE1 1ULUK
| | - Mari L. Lund
- The Novo Nordisk Foundation Centre for Basic Metabolic Research, Section for Metabolic Receptology and EnteroendocrinologyUniversity of CopenhagenCopenhagenDK‐2200Denmark
- Present address:
Chr. Hansen A/S, Human Health ResearchHoersholmDK‐2970Denmark
| | - Bhavik A. Patel
- Centre for Stress and Age‐Related Diseases, School of Applied SciencesUniversity of BrightonBrightonUK
| | - Thue W. Schwartz
- The Novo Nordisk Foundation Centre for Basic Metabolic Research, Section for Metabolic Receptology and EnteroendocrinologyUniversity of CopenhagenCopenhagenDK‐2200Denmark
| | - Helen M. Cox
- Wolfson Centre for Age‐Related Diseases, Institute of Psychology, Psychiatry and NeuroscienceKing's College LondonHodgkin Building, Guy's CampusLondonSE1 1ULUK
| |
Collapse
|
10
|
Martin AM, Jones LA, Wei L, Spencer NJ, Sanders KM, Ro S, Keating DJ. Distinguishing the contributions of neuronal and mucosal serotonin in the regulation of colonic motility. Neurogastroenterol Motil 2022; 34:e14361. [PMID: 35313053 DOI: 10.1111/nmo.14361] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 01/24/2022] [Accepted: 03/07/2022] [Indexed: 12/31/2022]
Abstract
BACKGROUND Specialized enterochromaffin (EC) cells within the mucosal lining of the gut synthesize and secrete almost all serotonin (5-hydroxytryptamine, 5-HT) in the body. Significantly lower amounts of 5-HT are made by other peripheral tissues and serotonergic neurons within the enteric nervous system (ENS). EC cells are in close proximity to 5-HT receptors in the ENS, and the role of 5-HT as a modulator of gut motility, particularly colonic motor complexes, has been well defined. However, the relative contribution of neuronal 5-HT to this process under resting and stimulus-evoked conditions is unclear. METHODS In this study, we combined the use of the selective serotonin transporter (SERT) inhibitor, fluoxetine, with two models of mucosal 5-HT depletion-surgical removal of the mucosa and our Tph1Cre/ERT2 ; Rosa26DTA mouse line-to determine the relative contribution of neuronal and mucosal 5-HT to resting and distension-evoked colonic motility. KEY RESULTS Fluoxetine significantly reduced the frequency of colonic migrating complexes (CMCs) in flat-sheet preparations with the mucosa present and in intact control Tph1-DTA colons in which EC cells were present. No such effect was observed in mucosa-free preparations or in intact Tph1-DTA preparations lacking EC cell 5-HT. CONCLUSIONS AND INFERENCES We demonstrate that mucosal 5-HT release plays an important role in distension-evoked colonic motility, and that SERT inhibition no longer alters gut motility when EC cells are absent, thus demonstrating that ENS 5-HT does not play a role in regulating gut motility.
Collapse
Affiliation(s)
- Alyce M Martin
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Lauren A Jones
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Lai Wei
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Nick J Spencer
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Seungil Ro
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Damien J Keating
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| |
Collapse
|
11
|
Spencer NJ, Keating DJ. Role of 5-HT in the enteric nervous system and enteroendocrine cells. Br J Pharmacol 2022. [PMID: 35861711 DOI: 10.1111/bph.15930] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 07/09/2022] [Accepted: 07/12/2022] [Indexed: 11/29/2022] Open
Abstract
Since the 1950s, considerable circumstantial evidence had been presented that endogenous 5-HT (serotonin) synthesized from within the wall of the gastrointestinal (GI) tract played an important role in GI motility and transit. However, identifying the precise functional role of gut-derived 5-HT has been difficult to ascertain, for a number of reasons. Over the past decade, as recording techniques have advanced significantly and access to new genetically modified animals improved, there have been major new insights and major changes in our understanding of the functional role of endogenous 5-HT in the GI tract. Data from many different laboratories have shown that major patterns of GI motility and transit still occur with minor or no, change when all endogenous 5-HT is pharmacologically or genetically ablated from the gut. Furthermore, antagonists of 5-HT3 receptors are equally, or more potent at inhibiting GI motility in segments of intestine that are completely depleted of endogenous 5-HT. Here, the most recent findings are discussed with regard to the functional role of endogenous 5-HT in enterochromaffin cells and enteric neurons in gut motility and more broadly in some major homeostatic pathways.
Collapse
Affiliation(s)
- Nick J Spencer
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University of South Australia, Adelaide, Australia
| | - Damien J Keating
- College of Medicine and Public Health and Centre for Neuroscience, Flinders University of South Australia, Adelaide, Australia
| |
Collapse
|
12
|
Wan Y, Zhang B. The Impact of Zinc and Zinc Homeostasis on the Intestinal Mucosal Barrier and Intestinal Diseases. Biomolecules 2022; 12:biom12070900. [PMID: 35883455 PMCID: PMC9313088 DOI: 10.3390/biom12070900] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/06/2022] [Accepted: 06/11/2022] [Indexed: 02/04/2023] Open
Abstract
Zinc is an essential trace element for living organisms, and zinc homeostasis is essential for the maintenance of the normal physiological functions of cells and organisms. The intestine is the main location for zinc absorption and excretion, while zinc and zinc homeostasis is also of great significance to the structure and function of the intestinal mucosal barrier. Zinc excess or deficiency and zinc homeostatic imbalance are all associated with many intestinal diseases, such as IBD (inflammatory bowel disease), IBS (irritable bowel syndrome), and CRC (colorectal cancer). In this review, we describe the role of zinc and zinc homeostasis in the intestinal mucosal barrier and the relevance of zinc homeostasis to gastrointestinal diseases.
Collapse
|
13
|
Immunohistochemical visualisation of the enteric nervous system architecture in the germ-free piglets. J Mol Histol 2022; 53:773-780. [PMID: 35689149 DOI: 10.1007/s10735-022-10079-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 05/23/2022] [Indexed: 10/18/2022]
Abstract
The enteric nervous system (ENS), considered as separate branch of the autonomic nervous system, is located throughout the length of the gastrointestinal tract as a series of interconnected ganglionic plexuses. Recently, the ENS is getting more in the focus of gastrointestinal research. For years, the main interest and research was aimed to the enteric neurons and their functional properties in normal conditions, less attention has been paid to the germ-free animals. Germ-free (GF) piglets have clear microbiological background and are reared in sterile environment. GF piglets are regarded as clinically relevant models for studying of human diseases, as these piglets' manifest similar clinical symptoms to humans. In this study we briefly summarised the main characteristics in immunohistochemical distribution of ENS elements in the wall of jejunum and colon of germ-free piglets.
Collapse
|
14
|
Jones LA, Jin B, Martin AM, Wei L, Ro S, Keating DJ. Diminished Piezo2-Dependent Tactile Sensitivity Occurs in Aging Human Gut and Slows Gastrointestinal Transit in Mice. Gastroenterology 2022; 162:1755-1757.e2. [PMID: 35122761 DOI: 10.1053/j.gastro.2022.01.043] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 12/02/2022]
Affiliation(s)
- Lauren A Jones
- Flinders Health and Medical Research Institute, Flinders University, South Australia, Australia
| | - Byungchang Jin
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Alyce M Martin
- Flinders Health and Medical Research Institute, Flinders University, South Australia, Australia
| | - Lai Wei
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | | | - Seungil Ro
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Damien J Keating
- Flinders Health and Medical Research Institute, Flinders University, South Australia, Australia.
| |
Collapse
|
15
|
Feng J, Hibberd TJ, Luo J, Yang P, Xie Z, Travis L, Spencer NJ, Hu H. Modification of Neurogenic Colonic Motor Behaviours by Chemogenetic Ablation of Calretinin Neurons. Front Cell Neurosci 2022; 16:799717. [PMID: 35317196 PMCID: PMC8934436 DOI: 10.3389/fncel.2022.799717] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/31/2022] [Indexed: 12/31/2022] Open
Abstract
How the enteric nervous system determines the pacing and propagation direction of neurogenic contractions along the colon remains largely unknown. We used a chemogenetic strategy to ablate enteric neurons expressing calretinin (CAL). Mice expressing human diphtheria toxin receptor (DTR) in CAL neurons were generated by crossing CAL-ires-Cre mice with Cre-dependent ROSA26-DTR mice. Immunohistochemical analysis revealed treatment with diphtheria toxin incurred a 42% reduction in counts of Hu-expressing colonic myenteric neurons (P = 0.036), and 57% loss of CAL neurons (comprising ∼25% of all Hu neurons; P = 0.004) compared to control. As proportions of Hu-expressing neurons, CAL neurons that contained nitric oxide synthase (NOS) were relatively spared (control: 15 ± 2%, CAL-DTR: 13 ± 1%; P = 0.145), while calretinin neurons lacking NOS were significantly reduced (control: 26 ± 2%, CAL-DTR: 18 ± 5%; P = 0.010). Colonic length and pellet sizes were significantly reduced without overt inflammation or changes in ganglionic density. Interestingly, colonic motor complexes (CMCs) persisted with increased frequency (mid-colon interval 111 ± 19 vs. 189 ± 24 s, CAL-DTR vs. control, respectively, P < 0.001), decreased contraction size (mid-colon AUC 26 ± 24 vs. 59 ± 13 gram/seconds, CAL-DTR vs. control, respectively, P < 0.001), and lacked preferential anterograde migration (P < 0.001). The functional effects of modest calretinin neuron ablation, particularly increased neurogenic motor activity frequencies, differ from models that incur general enteric neuron loss, and suggest calretinin neurons may contribute to pacing, force, and polarity of CMCs in the large bowel.
Collapse
Affiliation(s)
- Jing Feng
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
- Center for Neurological and Psychiatric Research and Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Tim J. Hibberd
- College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Adelaide, SA, Australia
| | - Jialie Luo
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Pu Yang
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Zili Xie
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Lee Travis
- College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Adelaide, SA, Australia
| | - Nick J. Spencer
- College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Adelaide, SA, Australia
- *Correspondence: Nick J. Spencer,
| | - Hongzhen Hu
- Center for the Study of Itch and Sensory Disorders, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
- Hongzhen Hu,
| |
Collapse
|
16
|
Treichel AJ, Finholm I, Knutson KR, Alcaino C, Whiteman ST, Brown MR, Matveyenko A, Wegner A, Kacmaz H, Mercado-Perez A, Bedekovicsne Gajdos G, Ordog T, Grover M, Szurzewski J, Linden DR, Farrugia G, Beyder A. Specialized Mechanosensory Epithelial Cells in Mouse Gut Intrinsic Tactile Sensitivity. Gastroenterology 2022; 162:535-547.e13. [PMID: 34688712 PMCID: PMC8792331 DOI: 10.1053/j.gastro.2021.10.026] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/30/2021] [Accepted: 10/12/2021] [Indexed: 01/07/2023]
Abstract
BACKGROUND AND AIMS The gastrointestinal (GI) tract extracts nutrients from ingested meals while protecting the organism from infectious agents frequently present in meals. Consequently, most animals conduct the entire digestive process within the GI tract while keeping the luminal contents entirely outside the body, separated by the tightly sealed GI epithelium. Therefore, like the skin and oral cavity, the GI tract must sense the chemical and physical properties of the its external interface to optimize its function. Specialized sensory enteroendocrine cells (EECs) in GI epithelium interact intimately with luminal contents. A subpopulation of EECs express the mechanically gated ion channel Piezo2 and are developmentally and functionally like the skin's touch sensor- the Merkel cell. We hypothesized that Piezo2+ EECs endow the gut with intrinsic tactile sensitivity. METHODS We generated transgenic mouse models with optogenetic activators in EECs and Piezo2 conditional knockouts. We used a range of reference standard and novel techniques from single cells to living animals, including single-cell RNA sequencing and opto-electrophysiology, opto-organ baths with luminal shear forces, and in vivo studies that assayed GI transit while manipulating the physical properties of luminal contents. RESULTS Piezo2+ EECs have transcriptomic features of synaptically connected, mechanosensory epithelial cells. EEC activation by optogenetics and forces led to Piezo2-dependent alterations in colonic propagating contractions driven by intrinsic circuitry, with Piezo2+ EECs detecting the small luminal forces and physical properties of the luminal contents to regulate transit times in the small and large bowel. CONCLUSIONS The GI tract has intrinsic tactile sensitivity that depends on Piezo2+ EECs and allows it to detect luminal forces and physical properties of luminal contents to modulate physiology.
Collapse
Affiliation(s)
- Anthony J. Treichel
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Isabelle Finholm
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Kaitlyn R. Knutson
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Constanza Alcaino
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Sara T. Whiteman
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Matthew R. Brown
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Aleksey Matveyenko
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Andrew Wegner
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Halil Kacmaz
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Arnaldo Mercado-Perez
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota,Medical Scientist Training Program, Mayo Clinic, Rochester, Minnesota
| | - Gabriella Bedekovicsne Gajdos
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Tamas Ordog
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Madhusudan Grover
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | - Joseph Szurzewski
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - David R. Linden
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Gianrico Farrugia
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota,Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Arthur Beyder
- Enteric Neuroscience Program, Mayo Clinic, Rochester, Minnesota; Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota.
| |
Collapse
|
17
|
Chiocchetti R, Galiazzo G, Giancola F, Tagliavia C, Bernardini C, Forni M, Pietra M. Localization of the Serotonin Transporter in the Dog Intestine and Comparison to the Rat and Human Intestines. Front Vet Sci 2022; 8:802479. [PMID: 35071391 PMCID: PMC8766808 DOI: 10.3389/fvets.2021.802479] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 12/10/2021] [Indexed: 12/23/2022] Open
Abstract
Serotonin is crucial in gastrointestinal functions, including motility, sensitivity, secretion, and the inflammatory response. The serotonin transporter (SERT), responsible for serotonin reuptake and signaling termination, plays a prominent role in gastrointestinal physiology, representing a promising therapeutic target in digestive disorders. Serotonin transporter expression has been poorly investigated in veterinary medicine, under both healthy and pathological conditions, including canine chronic enteropathy, in which the serotonin metabolism seems to be altered. The aim of the present study was to determine the distribution of SERT immunoreactivity (SERT-IR) in the dog intestine and to compare the findings with those obtained in the rat and human intestines. Serotonin transporter-IR was observed in canine enterocytes, enteric neurons, lamina propria cells and the tunica muscularis. Data obtained in dogs were consistent with those obtained in rats and humans. Since the majority of the serotonin produced by the body is synthesized in the gastrointestinal tract, SERT-expressing cells may exert a role in the mechanism of serotonin reuptake.
Collapse
Affiliation(s)
- Roberto Chiocchetti
- Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, Ozzano dell'Emilia, Italy
| | - Giorgia Galiazzo
- Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, Ozzano dell'Emilia, Italy
| | - Fiorella Giancola
- Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, Ozzano dell'Emilia, Italy
| | - Claudio Tagliavia
- Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, Ozzano dell'Emilia, Italy
| | - Chiara Bernardini
- Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, Ozzano dell'Emilia, Italy
| | - Monica Forni
- Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, Ozzano dell'Emilia, Italy
| | - Marco Pietra
- Department of Veterinary Medical Sciences (UNI EN ISO 9001:2008), University of Bologna, Ozzano dell'Emilia, Italy
| |
Collapse
|
18
|
The Shaggy Dog Story of Enteric Signaling: Serotonin, a Molecular Megillah. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:307-318. [PMID: 36587168 DOI: 10.1007/978-3-031-05843-1_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Historically and quantitatively, the enteric site of serotonin (5-HT) storage has primacy over those of any other organ. 5-HT, by the name of "enteramine", was first discovered in the bowel, and the gut produces most of the body's 5-HT. Not only does the bowel secrete 5-HT prodigiously but it also expresses a kaleidoscopic abundance of 5-HT receptors. The larger of two enteric 5-HT stores is mucosal, biosynthetically dependent upon tryptophan hydroxylase1 (TPH1), and located in EC cells. Mechanical stimuli, nutrients, luminal bacteria, and neurotransmitters such as acetylcholine and norepinephrine are all able to stimulate EC cells. Paracrine actions of 5-HT allow the mucosa to signal to neurons to initiate peristaltic and secretory reflexes as well as to inflammatory cells to promote intestinal inflammation. Endocrine effects of 5-HT allow EC cells to influence distant organs, including bone, liver, and endocrine pancreas. The smaller enteric 5-HT store is biosynthetically dependent upon TPH2 and is located within a small subset of myenteric neurons. 5-HT is responsible for slow excitatory neurotransmission manifested primarily in type II/AH neurons. Importantly, neuronal 5-HT also promotes enteric nervous system (ENS) neurogenesis, both pre- and postnatally, through 5-HT2B and especially 5-HT4 receptors. The early birth of serotonergic neurons allows these cells to function as sculptors of the mature ENS. The inactivation of secreted 5-HT depends on transmembrane transport mediated by a serotonin transporter (SERT; SLC6A4). The importance of SERT in control of 5-HT's function means that pharmacological inhibition of SERT, as well as gain- or loss-of-function mutations in SLC6A4, can exert profound effects on development and function of the ENS. Extra-enteric, TPH1-derived 5-HT from yolk sac and placenta promotes neurogenesis before enteric neurons synthesize 5-HT and contribute to ENS patterning. The impressive multi-functional nature of enteric 5-HT has made the precise identification of individual physiological roles difficult and sometimes controversial.
Collapse
|
19
|
New Concepts of the Interplay Between the Gut Microbiota and the Enteric Nervous System in the Control of Motility. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:55-69. [PMID: 36587146 DOI: 10.1007/978-3-031-05843-1_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Propulsive gastrointestinal (GI) motility is critical for digestive physiology and host defense. GI motility is finely regulated by the intramural reflex pathways of the enteric nervous system (ENS). The ENS is in turn regulated by luminal factors: diet and the gut microbiota. The gut microbiota is a vast ecosystem of commensal bacteria, fungi, viruses, and other microbes. The gut microbiota not only regulates the motor programs of the ENS but also is critical for the normal structure and function of the ENS. In this chapter, we highlight recent research that has shed light on the microbial mechanisms of interaction with the ENS involved in the control of motility. Toll-like receptor signaling mechanisms have been shown to maintain the structural integrity of the ENS and the neurochemical phenotypes of enteric neurons, in part through the production of trophic factors including glia-derived neurotrophic factor. Microbiota-derived short-chain fatty acids and/or single-stranded RNA regulates the synthesis of serotonin in enterochromaffin cells, which are involved in the initiation of enteric reflexes, among other functions. Further evidence suggests a crucial role for microbial modulation of serotonin in maintaining the integrity of the ENS through enteric neurogenesis. Understanding the microbial pathways of enteric neural control sheds new light on digestive health and provides novel treatment strategies for GI motility disorders.
Collapse
|
20
|
Spencer NJ, Costa M. Rhythmicity in the Enteric Nervous System of Mice. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:295-306. [PMID: 36587167 DOI: 10.1007/978-3-031-05843-1_27] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The enteric nervous system (ENS) is required for many cyclical patterns of motor activity along different regions of the gastrointestinal (GI) tract. What has remained mysterious is precisely how many thousands of neurons within the ENS are temporally activated to generate cyclical neurogenic contractions of GI-smooth muscle layers. This has been an especially puzzling conundrum, since the ENS consists of an extensive network of small ganglia, with each ganglion consisting of a heterogeneous population of neurons, with diverse cell soma morphologies, neurochemical and biophysical characteristics, and neural connectivity. Neuronal imaging studies of the mouse large intestine have provided major new insights into how the different classes of myenteric neurons are activated during cyclical neurogenic motor patterns, such as the colonic motor complex (CMC). It has been revealed that during CMCs (in the isolated mouse whole colon), large populations of myenteric neurons, across large spatial fields, coordinate their firing, via bursts of fast synaptic inputs at ~2 Hz. This coordinated firing of many thousands of myenteric neurons synchronously over many rows of interconnected ganglia occurs irrespective of the functional class of neuron. Aborally directed propulsion of content along the mouse colon is due, in large part, to polarity of the enteric circuits including the projections of the intrinsic excitatory and inhibitory motor neurons but still involves the fundamental ~2 Hz rhythmic activity of specific classes of enteric neurons. What remains to be determined are the mechanisms that initiate and terminate the patterned firing of large ensembles of enteric neurons during cyclic activity. This remains an exciting challenge for future studies.
Collapse
Affiliation(s)
- Nick J Spencer
- Visceral Neurophysiology Laboratory, Department of Physiology, College of Medicine and Public Health & Centre for Neuroscience, Flinders University, Bedford Park, SA, Australia.
| | - Marcello Costa
- Visceral Neurophysiology Laboratory, Department of Physiology, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
| |
Collapse
|
21
|
Costa M, Wiklendt L, Hibberd T, Dinning P, Spencer NJ, Brookes S. Analysis of Intestinal Movements with Spatiotemporal Maps: Beyond Anatomy and Physiology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:271-294. [PMID: 36587166 DOI: 10.1007/978-3-031-05843-1_26] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Over 150 years ago, methods for quantitative analysis of gastrointestinal motor patterns first appeared. Graphic representations of physiological variables were recorded with the kymograph after the mid-1800s. Changes in force or length of intestinal muscles could be quantified, however most recordings were limited to a single point along the digestive tract.In parallel, photography and cinematography with X-Rays visualised changes in intestinal shape, but were hard to quantify. More recently, the ability to record physiological events at many sites along the gut in combination with computer processing allowed construction of spatiotemporal maps. These included diameter maps (DMaps), constructed from video recordings of intestinal movements and pressure maps (PMaps), constructed using data from high-resolution manometry catheters. Combining different kinds of spatiotemporal maps revealed additional details about gut wall status, including compliance, which relates forces to changes in length. Plotting compliance values along the intestine enabled combined DPMaps to be constructed, which can distinguish active contractions and relaxations from passive changes. From combinations of spatiotemporal maps, it is possible to deduce the role of enteric circuits and pacemaker cells in the generation of complex motor patterns. Development and application of spatiotemporal methods to normal and abnormal motor patterns in animals and humans is ongoing, with further technical improvements arising from their combination with impedance manometry, magnetic resonance imaging, electrophysiology, and ultrasonography.
Collapse
Affiliation(s)
- Marcello Costa
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia.
| | - Luke Wiklendt
- Department of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - Tim Hibberd
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - Phil Dinning
- Department of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - Nick J Spencer
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - Simon Brookes
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia
| |
Collapse
|
22
|
Barth BB, Spencer NJ, Grill WM. Activation of ENS Circuits in Mouse Colon: Coordination in the Mouse Colonic Motor Complex as a Robust, Distributed Control System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:113-123. [PMID: 36587151 DOI: 10.1007/978-3-031-05843-1_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The characteristic motor patterns of the colon are coordinated by the enteric nervous system (ENS) and involve enterochromaffin (EC) cells, enteric glia, smooth muscle fibers, and interstitial cells. While the fundamental control mechanisms of colonic motor patterns are understood, greater complexity in the circuitry underlying motor patterns has been revealed by recent advances in the field. We review these recent advances and new findings from our laboratories that provide insights into how the ENS coordinates motor patterns in the isolated mouse colon. We contextualize these observations by describing the neuromuscular system underling the colonic motor complex (CMC) as a robust, distributed control system. Framing the colonic motor complex as a control system reveals a new perspective on the coordinated motor patterns in the colon. We test the control system by applying electrical stimulation in the isolated mouse colon to disrupt the coordination and propagation of the colonic motor complex.
Collapse
Affiliation(s)
- Bradley B Barth
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Nick J Spencer
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
| |
Collapse
|
23
|
Chronic Intestinal Pseudo-Obstruction: Is There a Connection with Gut Microbiota? Microorganisms 2021; 9:microorganisms9122549. [PMID: 34946150 PMCID: PMC8703706 DOI: 10.3390/microorganisms9122549] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 12/23/2022] Open
Abstract
Chronic intestinal pseudo-obstruction (CIPO) is a rare clinical syndrome characterized by severe impairment of gastrointestinal (GI) motility, and its symptoms are suggestive of partial or complete intestinal obstruction in the absence of any lesion restricting the intestinal lumen. Diagnosis and therapy of CIPO patients still represent a significant challenge for clinicians, despite their efforts to improve diagnostic workup and treatment strategies for this disease. The purpose of this review is to better understand what is currently known about the relationship between CIPO patients and intestinal microbiota, with a focus on the role of the enteric nervous system (ENS) and the intestinal endocrine system (IES) in intestinal motility, underling the importance of further studies to deeply understand the causes of gut motility dysfunction in these patients.
Collapse
|
24
|
Sgro M, Kodila ZN, Brady RD, Reichelt AC, Mychaisuk R, Yamakawa GR. Synchronizing Our Clocks as We Age: The Influence of the Brain-Gut-Immune Axis on the Sleep-Wake Cycle Across the Lifespan. Sleep 2021; 45:6425072. [PMID: 34757429 DOI: 10.1093/sleep/zsab268] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/11/2021] [Indexed: 11/12/2022] Open
Abstract
The microbes that colonize the small and large intestines, known as the gut microbiome, play an integral role in optimal brain development and function. The gut microbiome is a vital component of the bi-directional communication pathway between the brain, immune system, and gut, also known as the brain-gut-immune axis. To date there has been minimal investigation into the implications of improper development of the gut microbiome and the brain-gut-immune axis on the sleep-wake cycle, particularly during sensitive periods of physical and neurological development, such as childhood, adolescence, and senescence. Therefore, this review will explore the current literature surrounding the overlapping developmental periods of the gut microbiome, brain, and immune system from birth through to senescence, while highlighting how the brain-gut-immune axis affects maturation and organisation of the sleep-wake cycle. We also examine how dysfunction to either the microbiome or the sleep-wake cycle negatively affects the bidirectional relationship between the brain and gut, and subsequently the overall health and functionality of this complex system. Additionally, this review integrates therapeutic studies to demonstrate when dietary manipulations, such as supplementation with probiotics and prebiotics, can modulate the gut microbiome to enhance health of the brain-gut-immune axis and optimize our sleep-wake cycle.
Collapse
Affiliation(s)
- Marissa Sgro
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Zoe N Kodila
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Rhys D Brady
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Amy C Reichelt
- Department of Medical Sciences, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
| | - Richelle Mychaisuk
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Glenn R Yamakawa
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| |
Collapse
|
25
|
Najjar SA, Edwards BS, Albers KM, Davis BM, Smith-Edwards KM. Optogenetic activation of the distal colon epithelium engages enteric nervous system circuits to initiate motility patterns. Am J Physiol Gastrointest Liver Physiol 2021; 321:G426-G435. [PMID: 34468219 PMCID: PMC8560371 DOI: 10.1152/ajpgi.00026.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 08/18/2021] [Accepted: 08/23/2021] [Indexed: 02/07/2023]
Abstract
Digestive functions of the colon depend on sensory-motor reflexes in the enteric nervous system (ENS), initiated by intrinsic primary afferent neurons (IPANs). IPAN terminals project to the mucosal layer of the colon, allowing communication with epithelial cells comprising the colon lining. The chemical nature and functional significance of this epithelial-neural communication in regard to secretion and colon motility are of high interest. Colon epithelial cells can produce and release neuroactive substances such as ATP and 5-hydroxytryptamine (5-HT), which can activate receptors on adjacent nerve fibers, including IPAN subtypes. In this study, we examined if stimulation of epithelial cells alone is sufficient to activate neural circuits that control colon motility. Optogenetics and calcium imaging were used in ex vivo preparations of the mouse colon to selectively stimulate the colon epithelium, measure changes in motility, and record activity of neurons within the myenteric plexus. Light-mediated activation of epithelial cells lining the distal, but not proximal, colon caused local contractions and increased the rate of colonic migrating motor complexes. Epithelial-evoked local contractions in the distal colon were reduced by both ATP and 5-HT receptor antagonists. Our findings indicate that colon epithelial cells likely use purinergic and serotonergic signaling to initiate activity in myenteric neurons, produce local contractions, and facilitate large-scale coordination of ENS activity responsible for whole colon motility patterns.NEW & NOTEWORTHY Using an all-optical approach to measure real-time cell-to-cell communication responsible for colon functions, we show that selective optogenetic stimulation of distal colon epithelium produced activity in myenteric neurons, as measured with red genetically encoded calcium indicators. The epithelial-induced neural response led to local contractions, mediated by both purinergic and serotonergic signaling, and facilitated colonic motor complexes that propagate from proximal to distal colon.
Collapse
Affiliation(s)
- Sarah A Najjar
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Brian S Edwards
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kathryn M Albers
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Brian M Davis
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kristen M Smith-Edwards
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
| |
Collapse
|
26
|
Aikiyo S, Kishi K, Kaji N, Mikawa S, Kondo M, Shimada S, Hori M. Contribution of Serotonin 3A Receptor to Motor Function and Its Expression in the Gastrointestinal Tract. Digestion 2021; 102:516-526. [PMID: 32726781 DOI: 10.1159/000509209] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/31/2020] [Indexed: 02/04/2023]
Abstract
INTRODUCTION The serotonin 3A receptor (5-HT3AR) is involved in vomiting and gastrointestinal motility. However, it is not well understood the expression pattern of 5-HT3AR in the gut immunohistochemically and how much contribution of 5-HT3AR to upper or lower intestinal motility. OBJECTIVES We investigated the contribution of 5-HT3AR to gastrointestinal motor function by using 5-HT3AR KO mice and sought to identify 5-HT3AR-expressing cells via immunohistochemical staining using 5-HT3AR-GFP reporter mice. METHODS The expression of 5-HT3AR was measured in each section of the gut through real-time PCR. The motor function of the stomach and colon was assessed via the 13C-octanoic acid breath test and colonic bead expulsion test, respectively, using 5-HT3AR KO mice. 5-HT3AR-expressing cells in the muscle layer of the gut were identified by immunohistochemical staining using 5-HT3AR-GFP reporter mice. RESULTS 5-HT3AR was expressed throughout the digestive tract, and 5-HT3AR expression in the stomach and lower digestive tract was higher than that in the other sections. Motor function in the stomach and colon was lower in 5-HT3AR KO mice than in WT mice. As a result of immunohistochemical staining using GFP reporter mice, cholinergic neurons and PDGFRα+ cells were shown to express 5-HT3AR. In contrast, 5-HT3AR indicated by GFP fluorescence was rarely detected in ICC and smooth muscle cells. CONCLUSIONS These results show that 5-HT3AR is highly expressed in the stomach and large intestine and that the activation of 5-HT3AR accelerates gastric emptying and large intestine transit. Additionally, 5-HT3AR is highly expressed in cholinergic neurons and some interstitial cells, such as PDGFRα+ cells.
Collapse
Affiliation(s)
- Satoshi Aikiyo
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Kazuhisa Kishi
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, University of Tokyo, Tokyo, Japan
| | - Noriyuki Kaji
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, University of Tokyo, Tokyo, Japan.,Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Azabu University, Kanagawa, Japan
| | - Shoma Mikawa
- Laboratory of Veterinary Clinical Pathology, Faculty of Veterinary Medicine, Okayama University of Science, Ehime, Japan
| | - Makoto Kondo
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Shoichi Shimada
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Masatoshi Hori
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, University of Tokyo, Tokyo, Japan,
| |
Collapse
|
27
|
Jin B, Ha SE, Wei L, Singh R, Zogg H, Clemmensen B, Heredia DJ, Gould TW, Sanders KM, Ro S. Colonic Motility Is Improved by the Activation of 5-HT 2B Receptors on Interstitial Cells of Cajal in Diabetic Mice. Gastroenterology 2021; 161:608-622.e7. [PMID: 33895170 PMCID: PMC8532042 DOI: 10.1053/j.gastro.2021.04.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 04/15/2021] [Accepted: 04/17/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Constipation is commonly associated with diabetes. Serotonin (5-HT), produced predominantly by enterochromaffin (EC) cells via tryptophan hydroxylase 1 (TPH1), is a key modulator of gastrointestinal (GI) motility. However, the role of serotonergic signaling in constipation associated with diabetes is unknown. METHODS We generated EC cell reporter Tph1-tdTom, EC cell-depleted Tph1-DTA, combined Tph1-tdTom-DTA, and interstitial cell of Cajal (ICC)-specific Kit-GCaMP6 mice. Male mice and surgically ovariectomized female mice were fed a high-fat high-sucrose diet to induce diabetes. The effect of serotonergic signaling on GI motility was studied by examining 5-HT receptor expression in the colon and in vivo GI transit, colonic migrating motor complexes (CMMCs), and calcium imaging in mice treated with either a 5-HT2B receptor (HTR2B) antagonist or agonist. RESULTS Colonic transit was delayed in males with diabetes, although colonic Tph1+ cell density and 5-HT levels were increased. Colonic transit was not further reduced in diabetic mice by EC cell depletion. The HTR2B protein, predominantly expressed by colonic ICCs, was markedly decreased in the colonic muscles of males and ovariectomized females with diabetes. Ca2+ activity in colonic ICCs was decreased in diabetic males. Treatment with an HTR2B antagonist impaired CMMCs and colonic motility in healthy males, whereas treatment with an HTR2B agonist improved CMMCs and colonic motility in males with diabetes. Colonic transit in ovariectomized females with diabetes was also improved significantly by the HTR2B agonist treatment. CONCLUSIONS Impaired colonic motility in mice with diabetes was improved by enhancing HTR2B signaling. The HTR2B agonist may provide therapeutic benefits for constipation associated with diabetes.
Collapse
Affiliation(s)
- Byungchang Jin
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Se Eun Ha
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Lai Wei
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Rajan Singh
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Hannah Zogg
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Brooke Clemmensen
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Dante J Heredia
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Thomas W Gould
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Seungil Ro
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada.
| |
Collapse
|
28
|
Guo X, Lv J, Xi R. The specification and function of enteroendocrine cells in Drosophila and mammals: a comparative review. FEBS J 2021; 289:4773-4796. [PMID: 34115929 DOI: 10.1111/febs.16067] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/26/2021] [Accepted: 06/09/2021] [Indexed: 12/13/2022]
Abstract
Enteroendocrine cells (EECs) in both invertebrates and vertebrates derive from intestinal stem cells (ISCs) and are scattered along the digestive tract, where they function in sensing various environmental stimuli and subsequently secrete neurotransmitters or neuropeptides to regulate diverse biological and physiological processes. To fulfill these functions, EECs are specified into multiple subtypes that occupy specific gut regions. With advances in single-cell technology, organoid culture experimental systems, and CRISPR/Cas9-mediated genomic editing, rapid progress has been made toward characterization of EEC subtypes in mammals. Additionally, studies of genetic model organisms-especially Drosophila melanogaster-have also provided insights about the molecular processes underlying EEC specification from ISCs and about the establishment of diverse EEC subtypes. In this review, we compare the regulation of EEC specification and function in mammals and Drosophila, with a focus on EEC subtype characterization, on how internal and external regulators mediate EEC subtype specification, and on how EEC-mediated intra- and interorgan communications affect gastrointestinal physiology and pathology.
Collapse
Affiliation(s)
- Xingting Guo
- National Institute of Biological Sciences, Beijing, China
| | - Jiaying Lv
- National Institute of Biological Sciences, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Rongwen Xi
- National Institute of Biological Sciences, Beijing, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China
| |
Collapse
|
29
|
Wei L, Singh R, Ha SE, Martin AM, Jones LA, Jin B, Jorgensen BG, Zogg H, Chervo T, Gottfried-Blackmore A, Nguyen L, Habtezion A, Spencer NJ, Keating DJ, Sanders KM, Ro S. Serotonin Deficiency Is Associated With Delayed Gastric Emptying. Gastroenterology 2021; 160:2451-2466.e19. [PMID: 33662386 PMCID: PMC8532026 DOI: 10.1053/j.gastro.2021.02.060] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 02/22/2021] [Accepted: 02/25/2021] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Gastrointestinal (GI) motility is regulated by serotonin (5-hydroxytryptamine [5-HT]), which is primarily produced by enterochromaffin (EC) cells in the GI tract. However, the precise roles of EC cell-derived 5-HT in regulating gastric motility remain a major point of conjecture. Using a novel transgenic mouse line, we investigated the distribution of EC cells and the pathophysiologic roles of 5-HT deficiency in gastric motility in mice and humans. METHODS We developed an inducible, EC cell-specific Tph1CreERT2/+ mouse, which was used to generate a reporter mouse line, Tph1-tdTom, and an EC cell-depleted line, Tph1-DTA. We examined EC cell distribution, morphology, and subpopulations in reporter mice. GI motility was measured in vivo and ex vivo in EC cell-depleted mice. Additionally, we evaluated 5-HT content in biopsy and plasma specimens from patients with idiopathic gastroparesis (IG). RESULTS Tph1-tdTom mice showed EC cells that were heterogeneously distributed throughout the GI tract with the greatest abundance in the antrum and proximal colon. Two subpopulations of EC cells were identified in the gut: self-renewal cells located at the base of the crypt and mature cells observed in the villi. Tph1-DTA mice displayed delayed gastric emptying, total GI transit, and colonic transit. These gut motility alterations were reversed by exogenous provision of 5-HT. Patients with IG had a significant reduction of antral EC cell numbers and 5-HT content, which negatively correlated with gastric emptying rate. CONCLUSIONS The Tph1CreERT2/+ mouse provides a powerful tool to study the functional roles of EC cells in the GI tract. Our findings suggest a new pathophysiologic mechanism of 5-HT deficiency in IG.
Collapse
Affiliation(s)
- Lai Wei
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Rajan Singh
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Se Eun Ha
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Alyce M Martin
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Lauren A Jones
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Byungchang Jin
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Brian G Jorgensen
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Hannah Zogg
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Tyler Chervo
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Andres Gottfried-Blackmore
- Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California
| | - Linda Nguyen
- Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California
| | - Aida Habtezion
- Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California
| | - Nick J Spencer
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Damien J Keating
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada
| | - Seungil Ro
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada.
| |
Collapse
|
30
|
Malik A, Saha S, Morya RK, Bhadada SK, Rana SV. Impact of serotonin transporter gene polymorphism on gut motility in patients with type 2 Diabetes mellitus. J Neurogastroenterol Motil 2021; 27:240-247. [PMID: 33526751 PMCID: PMC8026373 DOI: 10.5056/jnm20211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/29/2020] [Accepted: 11/29/2020] [Indexed: 11/20/2022] Open
Abstract
Background/Aims The pathogenesis of gastrointestinal (GI) symptoms in patients with type 2 diabetes mellitus (T2DM) is yet to be delineated clearly. Serotonin, a monoamine neurotransmitter, resides primarily in the gut and plays a vital role in GI system. However, no study has been documented the role of serotonin and serotonin transporter gene (SLC6A4) polymorphism in the development of GI symptoms in T2DM patients. Methods Three hundred diabetes patients attending diabetes clinic at Postgraduate Institute of Medical Education and Research, Chandigarh, and matched healthy controls were enrolled for this study. Plasma from collected blood sample was used for serotonin measurement by enzyme-linked immunosorbent assay method and buffy coat was used for isolation of DNA by phenol chloroform method. Serotonin transporter gene polymorphism was analyzed by polymerase chain reaction method. Results The frequency of short allele (S) and SS genotype was significantly higher in patients with T2DM than controls and was associated with increased risk of T2DM. The frequency of LS genotype showed an association with protection from the disease. Regarding GI symptoms, 78.2% of patients with constipation showed LL and LS genotypes, and 97.7% of patients with diarrhea had SS genotype. The patients without GI symptoms did not show any association of gut motility with genotype. Furthermore, serotonin was significantly higher in diabetic patients who belonged to SS genotype compared to LS or LL genotype and who presented with diarrhea. Conclusion SS genotypes are prone to develop diarrhea because of faster gut motility resulting from higher serotonin levels as compared to LS and LL genotype in T2DM patients.
Collapse
Affiliation(s)
- Aastha Malik
- Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Sarama Saha
- Department of Biochemistry, All India Institute of Medical Sciences Rishikesh, Uttarakhand, India
| | - Rajesh K Morya
- Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Sanjay K Bhadada
- Department of Endocrinology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Satya V Rana
- Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.,Department of Biochemistry, All India Institute of Medical Sciences Rishikesh, Uttarakhand, India
| |
Collapse
|
31
|
Gibbs E, Chakrapani S. Structure, Function and Physiology of 5-Hydroxytryptamine Receptors Subtype 3. Subcell Biochem 2021; 96:373-408. [PMID: 33252737 DOI: 10.1007/978-3-030-58971-4_11] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
5-hydroxytryptamine receptor subtype 3 (5-HT3R) is a pentameric ligand-gated ion channel (pLGIC) involved in neuronal signaling. It is best known for its prominent role in gut-CNS signaling though there is growing interest in its other functions, particularly in modulating non-serotonergic synaptic activity. Recent advances in structural biology have provided mechanistic understanding of 5-HT3R function and present new opportunities for the field. This chapter gives a broad overview of 5-HT3R from a physiological and structural perspective and then discusses the specific details of ion permeation, ligand binding and allosteric coupling between these two events. Biochemical evidence is summarized and placed within a physiological context. This perspective underscores the progress that has been made as well as outstanding challenges and opportunities for future 5-HT3R research.
Collapse
Affiliation(s)
- Eric Gibbs
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA.
| | - Sudha Chakrapani
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA. .,Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106-4970, USA.
| |
Collapse
|
32
|
Abstract
The release from cells of signaling molecules through the controlled process of exocytosis involves multiple coordinated steps and is essential for the proper control of a multitude of biological pathways across the endocrine and nervous systems. However, these events are minute both temporally and in terms of the minute amounts of neurotransmitters, hormones, growth factors, and peptides released from single vesicles during exocytosis. It is therefore difficult to measure the kinetics of single exocytosis events in real time. One noninvasive method of measuring the release of molecules from cells is carbon-fiber amperometry. In this chapter, we will describe how we undertake such measurements from both single cells and in live tissue, how the subsequent data are analyzed, and how we interpret these results in terms of their relevant physiology.
Collapse
|
33
|
Spencer NJ, Costa M, Hibberd TJ, Wood JD. Advances in colonic motor complexes in mice. Am J Physiol Gastrointest Liver Physiol 2021; 320:G12-G29. [PMID: 33085903 DOI: 10.1152/ajpgi.00317.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The primary functions of the gastrointestinal (GI) tract are to absorb nutrients, water, and electrolytes that are essential for life. This is accompanied by the capability of the GI tract to mix ingested content to maximize absorption and effectively excrete waste material. There have been major advances in understanding intrinsic neural mechanisms involved in GI motility. This review highlights major advances over the past few decades in our understanding of colonic motor complexes (CMCs), the major intrinsic neural patterns that control GI motility. CMCs are generated by rhythmic coordinated firing of large populations of myenteric neurons. Initially, it was thought that serotonin release from the mucosa was required for CMC generation. However, careful experiments have now shown that neither the mucosa nor endogenous serotonin are required, although, evidence suggests enteroendocrine (EC) cells modulate CMCs. The frequency and extent of propagation of CMCs are highly dependent on mechanical stimuli (circumferential stretch). In summary, the isolated mouse colon emerges as a good model to investigate intrinsic mechanisms underlying colonic motility and provides an excellent preparation to explore potential therapeutic agents on colonic motility, in a highly controlled in vitro environment. In addition, during CMCs, the mouse colon facilitates investigations into the emergence of dynamic assemblies of extensive neural networks, applicable to the nervous system of different organisms.
Collapse
Affiliation(s)
- N J Spencer
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - M Costa
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - T J Hibberd
- Visceral Neurophysiology Laboratory, College of Medicine and Public Health, Centre for Neuroscience, Flinders University, Bedford Park, South Australia, Australia
| | - J D Wood
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio
| |
Collapse
|
34
|
Lee HA, Ju Moon S, Yoo H, Kyung Kim M, Bok Jang S, Lee S, Kim S, Lee H. YH12852, a Potent and Selective Receptor Agonist of 5-hydroxytryptamine, Increased Gastrointestinal Motility in Healthy Volunteers and Patients With Functional Constipation. Clin Transl Sci 2020; 14:625-634. [PMID: 33202093 PMCID: PMC7993265 DOI: 10.1111/cts.12924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/07/2020] [Indexed: 12/23/2022] Open
Abstract
Gastrointestinal (GI) motility disorders are common, decreases quality of life, and imposes a substantial economic burden. YH12852 is a novel agonist of 5‐hydroxytryptamine for the treatment of GI motility disorders. This phase I/IIa study assessed the tolerability, pharmacodynamic (PD) and pharmacokinetic (PK) profiles of YH12852. In the multiple dose (MD) cohort, healthy subjects and patients with functional constipation were randomized and received orally YH12852 at 0.3, 0.5, 1, 2, or 3 mg or prucalopride 2 mg or their matching placebo, once daily for 14 days after breakfast. In the multiple low‐dose cohort (MLD), healthy subjects randomly received once‐daily oral doses of YH12852 at 0.05 or 0.1 mg for 14 days after breakfast. Questionnaires, gastric emptying breath test for PDs, and plasma samples for PKs were collected. In the MD cohort, a total of 56 subjects (29 healthy volunteers and 27 patients with functional constipation) were randomized, of whom 48 completed the study. In the MLD cohort, a total of 16 healthy subjects were randomized, and 15 subjects completed the study. YH12852 increased the average weekly frequency of spontaneous bowel movements and loosened the stool. In addition, YH12852 increased quality of life satisfaction, and decreased severity of constipation symptom and GI symptoms. YH12852 was safe and well‐tolerated up to 3 mg and showed nearly dose proportional PKs. In conclusion, YH12852 was safe and enhanced GI motility. YH12852 can be developed as an effective treatment option for GI motility disorders, including functional constipation. Further studies are warranted to confirm this possibility.
Collapse
Affiliation(s)
- Hyun A Lee
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea.,Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Korea
| | - Seol Ju Moon
- Center for Clinical Pharmacology, Biomedical Research Institute, Chonbuk National University Hospital, Jeonju, Korea
| | - Hyounggyoon Yoo
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea
| | - Mi Kyung Kim
- Yuhan Research & Development Institute, Yuhan Corporation, Seoul, Korea
| | - Seong Bok Jang
- Yuhan Research & Development Institute, Yuhan Corporation, Seoul, Korea
| | - Seoungoh Lee
- Yuhan Research & Development Institute, Yuhan Corporation, Seoul, Korea
| | - Sohee Kim
- Yuhan Research & Development Institute, Yuhan Corporation, Seoul, Korea
| | - Howard Lee
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea.,Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Korea.,Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Korea
| |
Collapse
|
35
|
Martin AM, Jones LA, Jessup CF, Sun EW, Keating DJ. Diet differentially regulates enterochromaffin cell serotonin content, density and nutrient sensitivity in the mouse small and large intestine. Neurogastroenterol Motil 2020; 32:e13869. [PMID: 32378785 DOI: 10.1111/nmo.13869] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 04/03/2020] [Accepted: 04/09/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Enterochromaffin (EC) cells are specialized enteroendocrine cells lining the gastrointestinal (GI) tract and the source of almost all serotonin (5-hydroxytryptamine; 5-HT) in the body. Gut-derived 5-HT has a plethora of physiological roles, including regulation of gastrointestinal motility, and has been implicated as a driver of obesity and metabolic disease. This is due to 5-HT influencing key metabolic processes, such as hepatic gluconeogenesis, adipose tissue lipolysis and hindering thermogenic capacity. Increased circulating 5-HT occurs in humans with obesity and type 2 diabetes. However, despite the known metabolic roles of gut-derived 5-HT, the mechanisms underlying the cellular-level change in EC cells under obesogenic conditions remains unknown. METHODS We use a mouse model of diet-induced obesity (DIO) to identify the regional changes that occur in primary EC cells from the duodenum and colon. Transcriptional changes in the nutrient sensing profile of primary EC cells were assessed, and responses to nutrient stimuli in culture were determined by 5-HT ELISA. KEY RESULTS We find that obesogenic conditions affect EC cells in a region-dependent manner. Duodenal EC cells from DIO mice have impaired sugar sensing even in the presence of increased 5-HT content per cell, while colonic EC cell numbers are significantly increased, but have unaltered nutrient sensing capacity. CONCLUSIONS & INFERENCES Our findings from this study add novel insights into the mechanisms by which functional changes to EC cells occur at a cellular level, which may contribute to the altered circulating 5-HT seen with obesity and metabolic disease, and associated gastrointestinal disorders.
Collapse
Affiliation(s)
- Alyce M Martin
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, Australia
| | - Lauren A Jones
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, Australia
| | - Claire F Jessup
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, Australia
| | - Emily W Sun
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, Australia
| | - Damien J Keating
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Adelaide, Australia
| |
Collapse
|
36
|
Spencer NJ, Hu H. Enteric nervous system: sensory transduction, neural circuits and gastrointestinal motility. Nat Rev Gastroenterol Hepatol 2020; 17:338-351. [PMID: 32152479 PMCID: PMC7474470 DOI: 10.1038/s41575-020-0271-2] [Citation(s) in RCA: 288] [Impact Index Per Article: 72.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/27/2020] [Indexed: 02/07/2023]
Abstract
The gastrointestinal tract is the only internal organ to have evolved with its own independent nervous system, known as the enteric nervous system (ENS). This Review provides an update on advances that have been made in our understanding of how neurons within the ENS coordinate sensory and motor functions. Understanding this function is critical for determining how deficits in neurogenic motor patterns arise. Knowledge of how distension or chemical stimulation of the bowel evokes sensory responses in the ENS and central nervous system have progressed, including critical elements that underlie the mechanotransduction of distension-evoked colonic peristalsis. Contrary to original thought, evidence suggests that mucosal serotonin is not required for peristalsis or colonic migrating motor complexes, although it can modulate their characteristics. Chemosensory stimuli applied to the lumen can release substances from enteroendocrine cells, which could subsequently modulate ENS activity. Advances have been made in optogenetic technologies, such that specific neurochemical classes of enteric neurons can be stimulated. A major focus of this Review will be the latest advances in our understanding of how intrinsic sensory neurons in the ENS detect and respond to sensory stimuli and how these mechanisms differ from extrinsic sensory nerve endings in the gut that underlie the gut-brain axis.
Collapse
Affiliation(s)
- Nick J Spencer
- College of Medicine and Public Health & Centre for Neuroscience, Flinders University, Adelaide, Australia.
| | - Hongzhen Hu
- Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, St Louis, MO, USA
| |
Collapse
|
37
|
De Deurwaerdère P, Bharatiya R, Chagraoui A, Di Giovanni G. Constitutive activity of 5-HT receptors: Factual analysis. Neuropharmacology 2020; 168:107967. [DOI: 10.1016/j.neuropharm.2020.107967] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/26/2019] [Accepted: 01/12/2020] [Indexed: 12/16/2022]
|
38
|
Tan W, Lee G, Chen JH, Huizinga JD. Relationships Between Distention-, Butyrate- and Pellet-Induced Stimulation of Peristalsis in the Mouse Colon. Front Physiol 2020; 11:109. [PMID: 32132933 PMCID: PMC7040375 DOI: 10.3389/fphys.2020.00109] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 01/30/2020] [Indexed: 12/12/2022] Open
Abstract
Background/Aims Luminal factors such as short-chain fatty acids are increasingly recognized for playing a regulatory role in peristaltic activity. Our objective was to understand the roles of butyrate and propionate in regulating peristaltic activity in relation to distention-induced activities. Methods Butyrate and propionate were perfused intraluminally under varying intraluminal pressures in murine colons bathed in Krebs solution. We used video recording and spatiotemporal maps to examine peristalsis induced by the intrinsic rhythmic colonic motor complex (CMC) as well as pellet-induced peristaltic reflex movements. Results The CMC showed several configurations at different levels of excitation, culminating in long distance contractions (LDCs) which possess a triangular shape in murine colon spatiotemporal maps. Butyrate increased the frequency of CMCs but was a much weaker stimulus than distention and only contributed to significant changes under low distention. Propionate inhibited CMCs by decreasing either their amplitudes or frequencies, but only in low distention conditions. Butyrate did not consistently counteract propionate-induced inhibition likely due to the multiple and distinct mechanisms of action for these signaling molecules in the lumen. Pellet movement occurred through ongoing CMCs as well as pellet induced peristaltic reflex movements and butyrate augmented both types of peristaltic motor patterns to decrease the amount of time required to expel each pellet. Conclusions Butyrate is effective in promoting peristalsis, but only when the level of colonic activity is low such as under conditions of low intraluminal pressure. This suggests that it may play a significant role in patients with poor fiber intake, where there is low mechanical stimulation in the lumen.
Collapse
Affiliation(s)
- Wei Tan
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China.,Department of Medicine, Division of Gastroenterology, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Grace Lee
- Department of Medicine, Division of Gastroenterology, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Ji-Hong Chen
- Department of Medicine, Division of Gastroenterology, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Jan D Huizinga
- Department of Medicine, Division of Gastroenterology, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| |
Collapse
|
39
|
Sandoval-Talamantes AK, Gómez-González BA, Uriarte-Mayorga DF, Martínez-Guzman MA, Wheber-Hidalgo KA, Alvarado-Navarro A. Neurotransmitters, neuropeptides and their receptors interact with immune response in healthy and psoriatic skin. Neuropeptides 2020; 79:102004. [PMID: 31902596 DOI: 10.1016/j.npep.2019.102004] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 12/22/2019] [Accepted: 12/22/2019] [Indexed: 02/06/2023]
Abstract
Psoriasis is a chronic inflammatory disease with a multifactorial origin that affects the skin. It is characterized by keratinocyte hyperproliferation, which results in erythemato-squamous plaques. Just as the immune system plays a fundamental role in psoriasis physiopathology, the nervous system maintains the inflammatory process through the neuropeptides and neurotransmitters synthesis, as histamine, serotonin, calcitonin gene-related peptide, nerve growth factor, vasoactive intestinal peptide, substance P, adenosine, glucagon-like peptide, somatostatin and pituitary adenylate cyclase polypeptide. In patients with psoriasis, the systemic or in situ expression of these chemical mediators and their receptors are altered, which affects the clinical activity of patients due to its link to the immune system, provoking neurogenic inflammation. It is important to establish the role of the nervous system since it could represent a therapeutic alternative for psoriasis patients. The aim of this review is to offer a detailed review of the current literature about the neuropeptides and neurotransmitters involved in the physiopathology of psoriasis.
Collapse
Affiliation(s)
- Ana Karen Sandoval-Talamantes
- Centro de Reabilitación Infantil Teletón de Occidente, Copal 4575, Col. Arboledas del Sur, 44980 Guadalajara, Jalisco, México
| | - B A Gómez-González
- Instituto Dermatológico de Jalisco "Dr. José Barba Rubio", Av. Federalismo Norte 3102, Col. Atemajac del Valle, 45190 Zapopan, Jalisco, México
| | - D F Uriarte-Mayorga
- Instituto Dermatológico de Jalisco "Dr. José Barba Rubio", Av. Federalismo Norte 3102, Col. Atemajac del Valle, 45190 Zapopan, Jalisco, México
| | - M A Martínez-Guzman
- Unima Diagnósticos de México, Paseo de los Mosqueteros 4181, Col. Villa Universitaria, 45110 Zapopan, Jalisco, México
| | - Katia Alejandra Wheber-Hidalgo
- Instituto Dermatológico de Jalisco "Dr. José Barba Rubio", Av. Federalismo Norte 3102, Col. Atemajac del Valle, 45190 Zapopan, Jalisco, México
| | - Anabell Alvarado-Navarro
- Centro de Investigación en Inmunología y dermatología, Universidad de Guadalajara, México, Sierra Mojada 950, Col. Independencia, 44340, Guadalajara, Jalisco, México.
| |
Collapse
|
40
|
Hao MM, Fung C, Boesmans W, Lowette K, Tack J, Vanden Berghe P. Development of the intrinsic innervation of the small bowel mucosa and villi. Am J Physiol Gastrointest Liver Physiol 2020; 318:G53-G65. [PMID: 31682159 DOI: 10.1152/ajpgi.00264.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Detection of nutritional and noxious food components in the gut is a crucial component of gastrointestinal function. Contents in the gut lumen interact with enteroendocrine cells dispersed throughout the gut epithelium. Enteroendocrine cells release many different hormones, neuropeptides, and neurotransmitters that communicate either directly or indirectly with the central nervous system and the enteric nervous system, a network of neurons and glia located within the gut wall. Several populations of enteric neurons extend processes that innervate the gastrointestinal lamina propria; however, how these processes develop and begin to transmit information from the mucosa is not fully understood. In this study, we found that Tuj1-immunoreactive neurites begin to project out of the myenteric plexus at embryonic day (E)13.5 in the mouse small intestine, even before the formation of villi. Using live calcium imaging, we discovered that neurites were capable of transmitting electrical information from stimulated villi to the plexus by E15.5. In unpeeled gut preparations where all layers were left intact, we also mimicked the basolateral release of 5-HT from enteroendocrine cells, which triggered responses in myenteric cell bodies at postnatal day (P)0. Altogether, our results show that enteric neurons extend neurites out of the myenteric plexus early during mouse enteric nervous system development, innervating the gastrointestinal mucosa, even before villus formation in mice of either sex. Neurites are already able to conduct electrical information at E15.5, and responses to 5-HT develop postnatally.NEW & NOTEWORTHY How enteric neurons project into the gut mucosa and begin to communicate with the epithelium during development is not known. Our study shows that enteric neurites project into the lamina propria as early as E13.5 in the mouse, before development of the submucous plexus and before formation of intestinal villi. These neurites are capable of transmitting electrical signals back to their cell bodies by E15.5 and respond to serotonin applied to neurite terminals by birth.
Collapse
Affiliation(s)
- Marlene M Hao
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, University of Leuven, Belgium.,Department of Anatomy and Neuroscience, the University of Melbourne, Australia
| | - Candice Fung
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, University of Leuven, Belgium
| | - Werend Boesmans
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, University of Leuven, Belgium.,Department of Pathology, GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.,Biomedical Research Institute, Hasselt University, Hasselt, Belgium
| | - Katrien Lowette
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, University of Leuven, Belgium
| | - Jan Tack
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, University of Leuven, Belgium
| | - Pieter Vanden Berghe
- Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, University of Leuven, Belgium
| |
Collapse
|
41
|
Martin AM, Sun EW, Keating DJ. Mechanisms controlling hormone secretion in human gut and its relevance to metabolism. J Endocrinol 2019; 244:R1-R15. [PMID: 31751295 PMCID: PMC6892457 DOI: 10.1530/joe-19-0399] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 11/18/2019] [Indexed: 12/16/2022]
Abstract
The homoeostatic regulation of metabolism is highly complex and involves multiple inputs from both the nervous and endocrine systems. The gut is the largest endocrine organ in our body and synthesises and secretes over 20 different hormones from enteroendocrine cells that are dispersed throughout the gut epithelium. These hormones include GLP-1, PYY, GIP, serotonin, and CCK, each of whom play pivotal roles in maintaining energy balance and glucose homeostasis. Some are now the basis of several clinically used glucose-lowering and weight loss therapies. The environment in which these enteroendocrine cells exist is also complex, as they are exposed to numerous physiological inputs including ingested nutrients, circulating factors and metabolites produced from neighbouring gut microbiome. In this review, we examine the diverse means by which gut-derived hormones carry out their metabolic functions through their interactions with different metabolically important organs including the liver, pancreas, adipose tissue and brain. Furthermore, we discuss how nutrients and microbial metabolites affect gut hormone secretion and the mechanisms underlying these interactions.
Collapse
Affiliation(s)
- Alyce M Martin
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Emily W Sun
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Damien J Keating
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
- Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
- Correspondence should be addressed to D J Keating:
| |
Collapse
|
42
|
Gwynne RM, Bornstein JC. Luminal 5-HT 4 receptors-A successful target for prokinetic actions. Neurogastroenterol Motil 2019; 31:e13708. [PMID: 31524331 DOI: 10.1111/nmo.13708] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/06/2019] [Accepted: 08/07/2019] [Indexed: 02/08/2023]
Abstract
The prokinetic effects of 5-HT4 receptor (5-HT4 R) agonists have been utilized clinically for almost three decades to relieve symptoms of constipation. Surprisingly, the mechanism(s) of action of these compounds is still being debated. Recent studies highlight luminal 5-HT4 Rs as an alternative and effective target for these prokinetic agents. These include the study by Shokrollahi et al (2019, Neurogastroenterol Motil, e13598) published in the current issue of Neurogastroenterology and Motility, who found that activation of mucosal 5-HT4 Rs by intraluminal prucalopride, significantly enhanced propulsive motor patterns in rabbit colon. The authors highlight the idea that development of agonists targeting luminal 5-HT4 Rs in the colonic mucosa might be more effective and safer in achieving prokinetic effects on intestinal motility. The purpose of this mini-review is to discuss the evidence for luminal 5-HT4 Rs as an emerging target for prokinetic agents in facilitating propulsive motor patterns in the colon.
Collapse
Affiliation(s)
- Rachel M Gwynne
- Department of Physiology, University of Melbourne, Parkville, Vic., Australia
| | - Joel C Bornstein
- Department of Physiology, University of Melbourne, Parkville, Vic., Australia
| |
Collapse
|
43
|
Gould TW, Swope WA, Heredia DJ, Corrigan RD, Smith TK. Activity within specific enteric neurochemical subtypes is correlated with distinct patterns of gastrointestinal motility in the murine colon. Am J Physiol Gastrointest Liver Physiol 2019; 317:G210-G221. [PMID: 31268770 PMCID: PMC6734370 DOI: 10.1152/ajpgi.00252.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The enteric nervous system in the large intestine generates two important patterns relating to motility: 1) propagating rhythmic peristaltic smooth muscle contractions referred to as colonic migrating motor complexes (CMMCs) and 2) tonic inhibition, during which colonic smooth muscle contractions are suppressed. The precise neurobiological substrates underlying each of these patterns are unclear. Using transgenic animals expressing the genetically encoded calcium indicator GCaMP3 to monitor activity or the optogenetic actuator channelrhodopsin (ChR2) to drive activity in defined enteric neuronal subpopulations, we provide evidence that cholinergic and nitrergic neurons play significant roles in mediating CMMCs and tonic inhibition, respectively. Nitrergic neurons [neuronal nitric oxide synthase (nNOS)-positive neurons] expressing GCaMP3 exhibited higher levels of activity during periods of tonic inhibition than during CMMCs. Consistent with these findings, optogenetic activation of ChR2 in nitrergic neurons depressed ongoing CMMCs. Conversely, cholinergic neurons [choline acetyltransferase (ChAT)-positive neurons] expressing GCaMP3 markedly increased their activity during the CMMC. Treatment with the NO synthesis inhibitor Nω-nitro-l-arginine also augmented the activity of ChAT-GCaMP3 neurons, suggesting that the reciprocal patterns of activity exhibited by nitrergic and cholinergic enteric neurons during distinct phases of colonic motility may be related.NEW & NOTEWORTHY Correlating the activity of neuronal populations in the myenteric plexus to distinct periods of gastrointestinal motility is complicated by the difficulty of measuring the activity of specific neuronal subtypes. Here, using mice expressing genetically encoded calcium indicators or the optical actuator channelrhodopsin-2, we provide compelling evidence that cholinergic and nitrergic neurons play important roles in mediating coordinated propagating peristaltic contractions or tonic inhibition, respectively, in the murine colon.
Collapse
Affiliation(s)
- Thomas W. Gould
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada
| | - William A. Swope
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada
| | - Dante J. Heredia
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada
| | - Robert D. Corrigan
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada
| | - Terence K. Smith
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada
| |
Collapse
|
44
|
Yabut JM, Crane JD, Green AE, Keating DJ, Khan WI, Steinberg GR. Emerging Roles for Serotonin in Regulating Metabolism: New Implications for an Ancient Molecule. Endocr Rev 2019; 40:1092-1107. [PMID: 30901029 PMCID: PMC6624793 DOI: 10.1210/er.2018-00283] [Citation(s) in RCA: 206] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 03/18/2019] [Indexed: 12/12/2022]
Abstract
Serotonin is a phylogenetically ancient biogenic amine that has played an integral role in maintaining energy homeostasis for billions of years. In mammals, serotonin produced within the central nervous system regulates behavior, suppresses appetite, and promotes energy expenditure by increasing sympathetic drive to brown adipose tissue. In addition to these central circuits, emerging evidence also suggests an important role for peripheral serotonin as a factor that enhances nutrient absorption and storage. Specifically, glucose and fatty acids stimulate the release of serotonin from the duodenum, promoting gut peristalsis and nutrient absorption. Serotonin also enters the bloodstream and interacts with multiple organs, priming the body for energy storage by promoting insulin secretion and de novo lipogenesis in the liver and white adipose tissue, while reducing lipolysis and the metabolic activity of brown and beige adipose tissue. Collectively, peripheral serotonin acts as an endocrine factor to promote the efficient storage of energy by upregulating lipid anabolism. Pharmacological inhibition of serotonin synthesis or signaling in key metabolic tissues are potential drug targets for obesity, type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD).
Collapse
Affiliation(s)
- Julian M Yabut
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada.,Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada
| | - Justin D Crane
- Department of Biology, Northeastern University, Boston, Massachusetts
| | - Alexander E Green
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada.,Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada
| | - Damien J Keating
- College of Medicine and Public Health, Flinders University, Bedford Park, South Australia, Australia
| | - Waliul I Khan
- Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada.,Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Gregory R Steinberg
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada.,Centre for Metabolism, Obesity and Diabetes Research, McMaster University, Hamilton, Ontario, Canada.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| |
Collapse
|
45
|
Treichel AJ, Farrugia G, Beyder A. The touchy business of gastrointestinal (GI) mechanosensitivity. Brain Res 2019; 1693:197-200. [PMID: 29903622 DOI: 10.1016/j.brainres.2018.02.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 02/06/2018] [Accepted: 02/24/2018] [Indexed: 12/26/2022]
Abstract
The gastrointestinal (GI) tract's normal function depends on its ability to propel, mix, and store contents in a highly coordinated fashion. An ability to sense mechanical forces is therefore fundamental to normal GI tract operation. There are several mechanosensory circuits distributed throughout the GI tract. These circuits rely on a range of proposed specialized and non-specialized mechanosensory cells that include epithelial enterochromaffin (EC) cells, both intrinsic and extrinsic sensory neurons, glia, interstitial cells of Cajal (ICC), and smooth muscle cells. While the anatomy of these circuits is established, the molecular mechanisms and functions are still poorly understood. In this review, we focus on the neuro-epithelial mechanosensory circuit in the gut, composed of epithelial EC cells and sensory neurons, both intrinsic and extrinsic. Intriguingly, this circuit closely resembles the light touch circuit in the skin that is composed of an epithelial Merkel cell and an afferent sensory neuron, suggesting that the basic building blocks may be retained in diverse mechanosensory systems. We compare the gross and molecular anatomy and physiology of these circuits and dissect the roles of GI neuro-epithelial mechanosensory, or "GI touch", circuitry in GI health and disease.
Collapse
Affiliation(s)
- Anthony J Treichel
- Enteric Neuroscience Program, Division of Gastroenterology & Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, 200 First Street SW, Rochester, MN, USA
| | - Gianrico Farrugia
- Enteric Neuroscience Program, Division of Gastroenterology & Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, 200 First Street SW, Rochester, MN, USA
| | - Arthur Beyder
- Enteric Neuroscience Program, Division of Gastroenterology & Hepatology, Department of Physiology & Biomedical Engineering, Mayo Clinic, 200 First Street SW, Rochester, MN, USA.
| |
Collapse
|
46
|
Martin AM, Sun EW, Rogers GB, Keating DJ. The Influence of the Gut Microbiome on Host Metabolism Through the Regulation of Gut Hormone Release. Front Physiol 2019; 10:428. [PMID: 31057420 PMCID: PMC6477058 DOI: 10.3389/fphys.2019.00428] [Citation(s) in RCA: 206] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/27/2019] [Indexed: 12/17/2022] Open
Abstract
The microbial community of the gut conveys significant benefits to host physiology. A clear relationship has now been established between gut bacteria and host metabolism in which microbial-mediated gut hormone release plays an important role. Within the gut lumen, bacteria produce a number of metabolites and contain structural components that act as signaling molecules to a number of cell types within the mucosa. Enteroendocrine cells within the mucosal lining of the gut synthesize and secrete a number of hormones including CCK, PYY, GLP-1, GIP, and 5-HT, which have regulatory roles in key metabolic processes such as insulin sensitivity, glucose tolerance, fat storage, and appetite. Release of these hormones can be influenced by the presence of bacteria and their metabolites within the gut and as such, microbial-mediated gut hormone release is an important component of microbial regulation of host metabolism. Dietary or pharmacological interventions which alter the gut microbiome therefore pose as potential therapeutics for the treatment of human metabolic disorders. This review aims to describe the complex interaction between intestinal microbiota and their metabolites and gut enteroendocrine cells, and highlight how the gut microbiome can influence host metabolism through the regulation of gut hormone release.
Collapse
Affiliation(s)
- Alyce M Martin
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Emily W Sun
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Geraint B Rogers
- Microbiome Research Laboratory, Flinders University, Adelaide, SA, Australia.,Infection and Immunity, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Damien J Keating
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia.,Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| |
Collapse
|
47
|
What is the role of endogenous gut serotonin in the control of gastrointestinal motility? Pharmacol Res 2019; 140:50-55. [DOI: 10.1016/j.phrs.2018.06.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 06/17/2018] [Accepted: 06/18/2018] [Indexed: 12/26/2022]
|
48
|
Serotonin, hematopoiesis and stem cells. Pharmacol Res 2019; 140:67-74. [DOI: 10.1016/j.phrs.2018.08.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 07/27/2018] [Accepted: 08/08/2018] [Indexed: 02/08/2023]
|
49
|
Sugar Responses of Human Enterochromaffin Cells Depend on Gut Region, Sex, and Body Mass. Nutrients 2019; 11:nu11020234. [PMID: 30678223 PMCID: PMC6412251 DOI: 10.3390/nu11020234] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/15/2018] [Accepted: 01/14/2019] [Indexed: 12/12/2022] Open
Abstract
Gut-derived serotonin (5-HT) is released from enterochromaffin (EC) cells in response to nutrient cues, and acts to slow gastric emptying and modulate gastric motility. Rodent studies also evidence a role for gut-derived 5-HT in the control of hepatic glucose production, lipolysis and thermogenesis, and in mediating diet-induced obesity. EC cell number and 5-HT content is increased in the small intestine of obese rodents and human, however, it is unknown whether EC cells respond directly to glucose in humans, and whether their capacity to release 5-HT is perturbed in obesity. We therefore investigated 5-HT release from human duodenal and colonic EC cells in response to glucose, sucrose, fructose and α-glucoside (αMG) in relation to body mass index (BMI). EC cells released 5-HT only in response to 100 and 300 mM glucose (duodenum) and 300 mM glucose (colon), independently of osmolarity. Duodenal, but not colonic, EC cells also released 5-HT in response to sucrose and αMG, but did not respond to fructose. 5-HT content was similar in all EC cells in males, and colonic EC cells in females, but 3 to 4-fold higher in duodenal EC cells from overweight females (p < 0.05 compared to lean, obese). Glucose-evoked 5-HT release was 3-fold higher in the duodenum of overweight females (p < 0.05, compared to obese), but absent here in overweight males. Our data demonstrate that primary human EC cells respond directly to dietary glucose cues, with regional differences in selectivity for other sugars. Augmented glucose-evoked 5-HT release from duodenal EC is a feature of overweight females, and may be an early determinant of obesity.
Collapse
|
50
|
Martin AM, Sun EW, Rogers GB, Keating DJ. The Influence of the Gut Microbiome on Host Metabolism Through the Regulation of Gut Hormone Release. Front Physiol 2019. [PMID: 31057420 DOI: 10.3389/fphys.2019.00428/bibtex] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
The microbial community of the gut conveys significant benefits to host physiology. A clear relationship has now been established between gut bacteria and host metabolism in which microbial-mediated gut hormone release plays an important role. Within the gut lumen, bacteria produce a number of metabolites and contain structural components that act as signaling molecules to a number of cell types within the mucosa. Enteroendocrine cells within the mucosal lining of the gut synthesize and secrete a number of hormones including CCK, PYY, GLP-1, GIP, and 5-HT, which have regulatory roles in key metabolic processes such as insulin sensitivity, glucose tolerance, fat storage, and appetite. Release of these hormones can be influenced by the presence of bacteria and their metabolites within the gut and as such, microbial-mediated gut hormone release is an important component of microbial regulation of host metabolism. Dietary or pharmacological interventions which alter the gut microbiome therefore pose as potential therapeutics for the treatment of human metabolic disorders. This review aims to describe the complex interaction between intestinal microbiota and their metabolites and gut enteroendocrine cells, and highlight how the gut microbiome can influence host metabolism through the regulation of gut hormone release.
Collapse
Affiliation(s)
- Alyce M Martin
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Emily W Sun
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Geraint B Rogers
- Microbiome Research Laboratory, Flinders University, Adelaide, SA, Australia
- Infection and Immunity, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Damien J Keating
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
- Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| |
Collapse
|