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Xue Z, Patel K, Bhatia P, Miller CL, Shergill RS, Patel BA. 3D-Printed Microelectrodes for Biological Measurement. Anal Chem 2024. [PMID: 39039062 DOI: 10.1021/acs.analchem.4c01585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Microelectrodes are useful electrochemical sensors that can provide spatial biological monitoring. Carbon fiber has been by far the most widely used microelectrode; however, a vast number of different materials and modification strategies have been developed to broaden the scope of microelectrodes. Carbon composite electrodes provide a simple approach to making microelectrodes with a wide range of materials, but manufacturing strategies are complex. 3D printing can provide the ability to make microelectrodes with high precision. We used fused filament fabrication to print single strands of carbon black/polylactic acid (CB/PLA) and multiwall carbon nanotube/polylactic acid (MWCNT/PLA), which were then made into microelectrodes. Microelectrodes ranged from 70 μm in diameter to 400 μm in diameter and were assessed using standard redox probes. MWCNT/PLA electrodes exhibited greater sensitivity, a lower limit of detection, and stability for the measurement of serotonin (5-HT). Both CB/PLA and MWCNT/PLA microelectrodes were able to monitor 5-HT overflow from the ex vivo ileum tissue. MWCNT/PLA microelectrodes were utilized to show differences in 5-HT overflow from ex vivo ileum and colon following exposure to odorants present in spices. These findings highlight that any conductive thermoplastic material can be fabricated into a microelectrode. This simple strategy can utilize a wide range of materials to make 3D-printed microelectrodes for a diverse range of applications.
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Affiliation(s)
- Zehao Xue
- School of Applied Sciences, University of Brighton, Brighton, East Sussex BN2 4GJ, U.K
| | - Kanisha Patel
- School of Applied Sciences, University of Brighton, Brighton, East Sussex BN2 4GJ, U.K
| | - Paankhuri Bhatia
- School of Applied Sciences, University of Brighton, Brighton, East Sussex BN2 4GJ, U.K
| | - Chloe L Miller
- School of Applied Sciences, University of Brighton, Brighton, East Sussex BN2 4GJ, U.K
- Centre for Lifelong Health, University of Brighton, Brighton, East Sussex BN2 4GJ, U.K
| | - Ricoveer Singh Shergill
- School of Applied Sciences, University of Brighton, Brighton, East Sussex BN2 4GJ, U.K
- Centre for Lifelong Health, University of Brighton, Brighton, East Sussex BN2 4GJ, U.K
| | - Bhavik Anil Patel
- School of Applied Sciences, University of Brighton, Brighton, East Sussex BN2 4GJ, U.K
- Centre for Lifelong Health, University of Brighton, Brighton, East Sussex BN2 4GJ, U.K
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2
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Yeoman MS, Fidalgo S, Marcelli G, Patel BA. Amperometry approach curve profiling to understand the regulatory mechanisms governing the concentration of intestinal extracellular serotonin. Sci Rep 2024; 14:10479. [PMID: 38714793 PMCID: PMC11076564 DOI: 10.1038/s41598-024-61296-9] [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: 12/28/2023] [Accepted: 05/03/2024] [Indexed: 05/10/2024] Open
Abstract
Enterochromaffin (EC) cells located within the intestinal mucosal epithelium release serotonin (5-HT) to regulate motility tones, barrier function and the immune system. Electroanalytical methodologies have been able to monitor steady state basal extracellular 5-HT levels but are unable to provide insight into how these levels are influenced by key regulatory processes such as release and uptake. We established a new measurement approach, amperometry approach curve profiling, which monitors the extracellular 5-HT level at different electrode-tissue (E-T) distances. Analysis of the current profile can provide information on contributions of regulatory components on the observed extracellular 5-HT level. Measurements were conducted from ex vivo murine ileum and colon using a boron-doped diamond (BDD) microelectrode. Amperometry approach curve profiling coupled with classical pharmacology demonstrated that extracellular 5-HT levels were significantly lower in the colon when compared to the ileum. This difference was due to a greater degree of activity of the 5-HT transporter (SERT) and a reduced amount of 5-HT released from colonic EC cells. The presence of an inhibitory 5-HT4 autoreceptor was observed in the colon, where a 40% increase in extracellular 5-HT was the half maximal inhibitory concentration for activation of the autoreceptor. This novel electroanalytical approach allows estimates of release and re-uptake and their contribution to 5-HT extracellular concentration from intestinal tissue be obtained from a single series of measurements.
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Affiliation(s)
- Mark S Yeoman
- School of Applied Sciences, University of Brighton, Huxley Building, Brighton, BN2 4GJ, UK
- Centre for Lifelong Health, University of Brighton, Huxley Building, Brighton, BN2 4GJ, UK
| | - Sara Fidalgo
- School of Applied Sciences, University of Brighton, Huxley Building, Brighton, BN2 4GJ, UK
- Centre for Lifelong Health, University of Brighton, Huxley Building, Brighton, BN2 4GJ, UK
| | - Gianluca Marcelli
- School of Engineering, University of Kent, Jennison Building, Canterbury, CT2 7NZ, UK
| | - Bhavik Anil Patel
- School of Applied Sciences, University of Brighton, Huxley Building, Brighton, BN2 4GJ, UK.
- Centre for Lifelong Health, University of Brighton, Huxley Building, Brighton, BN2 4GJ, UK.
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3
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Brooks EL, Hussain KK, Kotecha K, Abdalla A, Patel BA. Three-Dimensional-Printed Electrochemical Multiwell Plates for Monitoring Food Intolerance from Intestinal Organoids. ACS Sens 2023; 8:712-720. [PMID: 36749605 DOI: 10.1021/acssensors.2c02245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Common symptoms of food intolerance are caused by chemical components within food that have a pharmacological activity to alter the motility of the gastrointestinal tract. Food intolerance is difficult to diagnose as it requires a long-term process of eliminating foods that are responsible for gastrointestinal symptoms. Enterochromaffin (EC) cells are key intestinal epithelium cells that respond to luminal chemical stimulants by releasing 5-HT. Changes in 5-HT levels have been shown to directly alter the motility of the intestinal tract. Therefore, a rapid approach for monitoring the impact of chemicals in food components on 5-HT levels can provide a personalized insight into food intolerance and help stratify diets. Within this study, we developed a three-dimensional (3D)-printed electrochemical multiwell plate to determine changes in 5-HT levels from intestinal organoids that were exposed to varying chemical components found in food. The carbon black/poly-lactic acid (CB/PLA) electrodes had a linear range in physiological concentrations of 5-HT (0.1-2 μM) with a limit of detection of 0.07 μM. The electrodes were stable for monitoring 5-HT overflow from intestinal organoids. Using the electrochemical multiwell plate containing intestinal organoids, increases in 5-HT were observed in the presence of 0.1 mM cinnamaldehyde and 10 mM quercetin but reduction in 5-HT levels was observed in 1 mM sorbitol when compared to control. These changes in the presence of chemicals commonly found in food were verified with ex vivo ileum tissue measurements using chromatography and amperometry with boron-doped diamond electrodes. Overall, our 3D electrochemical multiwell plate measurements with intestinal organoids highlight an approach that can be a high-throughput platform technology for rapid screening of food intolerance to provide personalized nutritional diet.
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Affiliation(s)
- Emily L Brooks
- School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, U.K.,Centre of Stress and Age-Related Diseases, University of Brighton, Brighton BN2 4GJ, U.K
| | - Khalil K Hussain
- School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, U.K.,Centre of Stress and Age-Related Diseases, University of Brighton, Brighton BN2 4GJ, U.K
| | - Khushboo Kotecha
- School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, U.K
| | - Aya Abdalla
- School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, U.K.,Centre of Stress and Age-Related Diseases, University of Brighton, Brighton BN2 4GJ, U.K
| | - Bhavik Anil Patel
- School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, U.K.,Centre of Stress and Age-Related Diseases, University of Brighton, Brighton BN2 4GJ, U.K
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Perez F, Kotecha N, Lavoie B, Mawe GM, Patel BA. Monitoring Gut Epithelium Serotonin and Melatonin Overflow Provides Spatial Mapping of Inflammation. Chembiochem 2023; 24:e202200334. [PMID: 36394122 PMCID: PMC9909162 DOI: 10.1002/cbic.202200334] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 11/07/2022] [Indexed: 11/18/2022]
Abstract
Electrochemical arrays were used to measure the overflow of serotonin (5-HT) and melatonin (MEL) from the entire colon of healthy mice and mice with chemical-induced inflammatory bowel disease (IBD), to understand the interplay between inflammation and colonic function. We show that 5-HT overflow is increased, whilst MEL levels are reduced, in inflamed tissues. The levels of MEL are increased at the interface between healthy and inflamed regions within the colon and may limit the spread of inflammation. Understanding the interplay between inflammation and mucosal epithelial signalling can provide key insight into colonic function and aid the development of effective therapeutic strategies to treat gastrointestinal diseases.
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Affiliation(s)
- Fernando Perez
- Centre for Stress and Age-Related Disease, School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Nikki Kotecha
- Centre for Stress and Age-Related Disease, School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Brigitte Lavoie
- Department of Neurological Sciences, The University of Vermont, Burlington, VT, 05405 USA
| | - Gary M. Mawe
- Department of Neurological Sciences, The University of Vermont, Burlington, VT, 05405 USA
| | - Bhavik Anil Patel
- Centre for Stress and Age-Related Disease, School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
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Liu YL, Chen Y, Fan WT, Cao P, Yan J, Zhao XZ, Dong WG, Huang WH. Mechanical Distension Induces Serotonin Release from Intestine as Revealed by Stretchable Electrochemical Sensing. Angew Chem Int Ed Engl 2020; 59:4075-4081. [PMID: 31829491 DOI: 10.1002/anie.201913953] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 12/04/2019] [Indexed: 12/17/2022]
Abstract
The role of endogenous serotonin (5-HT) in gastrointestinal motility is still highly controversial. Although electrochemical techniques allow for direct and real-time recording of biomolecules, the dynamic monitoring of 5-HT release from elastic and tubular intestine during motor reflexes remains a great challenge because of the specific peristalsis patterns and inevitable passivation of the sensing interface. A stretchable sensor with antifouling and decontamination properties was assembled from gold nanotubes, titanium dioxide nanoparticles, and carbon nanotubes. The sandwich-like structure endowed the sensor with satisfying mechanical stability and electrochemical performance, high resistance against physical adsorption, and superior efficiency in the photodegradation of biofouling molecules. Insertion of the sensor into the lumen of rat ileum (the last section of the small intestine) successfully mimics intestinal peristalsis, and simultaneous real-time monitoring of distension-evoked 5-HT release was possible for the first time. Our results unambiguously reveal that mechanical distension of the intestine induces endogenous 5-HT overflow, and 5-HT level is closely associated with the physiological or pathological states of the intestine.
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Affiliation(s)
- Yan-Ling Liu
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072, China
| | - Yan Chen
- Key Laboratory of Hubei Province for Digestive System Disease, Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Wen-Ting Fan
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072, China
| | - Pan Cao
- Key Laboratory of Hubei Province for Digestive System Disease, Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Jing Yan
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072, China
| | - Xing-Zhong Zhao
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, 430072, China
| | - Wei-Guo Dong
- Key Laboratory of Hubei Province for Digestive System Disease, Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Wei-Hua Huang
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072, China
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6
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Liu Y, Chen Y, Fan W, Cao P, Yan J, Zhao X, Dong W, Huang W. Mechanical Distension Induces Serotonin Release from Intestine as Revealed by Stretchable Electrochemical Sensing. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201913953] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Yan‐Ling Liu
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education) College of Chemistry and Molecular Sciences Wuhan University Wuhan 430072 China
| | - Yan Chen
- Key Laboratory of Hubei Province for Digestive System Disease Department of Gastroenterology Renmin Hospital of Wuhan University Wuhan 430060 China
| | - Wen‐Ting Fan
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education) College of Chemistry and Molecular Sciences Wuhan University Wuhan 430072 China
| | - Pan Cao
- Key Laboratory of Hubei Province for Digestive System Disease Department of Gastroenterology Renmin Hospital of Wuhan University Wuhan 430060 China
| | - Jing Yan
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education) College of Chemistry and Molecular Sciences Wuhan University Wuhan 430072 China
| | - Xing‐Zhong Zhao
- Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education School of Physics and Technology Wuhan University Wuhan 430072 China
| | - Wei‐Guo Dong
- Key Laboratory of Hubei Province for Digestive System Disease Department of Gastroenterology Renmin Hospital of Wuhan University Wuhan 430060 China
| | - Wei‐Hua Huang
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education) College of Chemistry and Molecular Sciences Wuhan University Wuhan 430072 China
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Gunn D, Garsed K, Lam C, Singh G, Lingaya M, Wahl V, Niesler B, Henry A, Hall IP, Whorwell P, Spiller R. Abnormalities of mucosal serotonin metabolism and 5-HT 3 receptor subunit 3C polymorphism in irritable bowel syndrome with diarrhoea predict responsiveness to ondansetron. Aliment Pharmacol Ther 2019; 50:538-546. [PMID: 31342534 PMCID: PMC6772086 DOI: 10.1111/apt.15420] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 03/10/2019] [Accepted: 06/25/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Irritable bowel syndrome with diarrhoea (IBS-D) is a common condition, greatly reducing the quality of life with few effective treatment options available. AIM To report the beneficial response shown in our trial with the 5-hydroyxtryptamine (5-HT) receptor 3 antagonist, ondansetron in IBS-D METHODS: A randomised, placebo-controlled, cross-over trial of 5 weeks of ondansetron versus placebo in 125 patients meeting modified Rome III criteria for IBS-D as previously described. Patients were compared to 21 healthy controls. 5-HT and 5-HIAA were measured in rectal biopsies. Whole gut transit time was assessed using a radio-opaque marker technique. Whole blood DNA was genotyped for an insertion polymorphism in the promoter region of the serotonin transporter gene SLC6A4, as well as single nucleotide polymorphisms (SNPs) of the tryptophan hydroxylase gene TPH1 and 5-HT3 receptor genes HTR3A, C and E. RESULTS Patients' biopsies showed significantly higher 5-HIAA levels (2.1 (1.2-4.2) pmol/mg protein vs 1.1 (0.4-1.5) in controls, P < .0001). 39 patients used < 4 mg/d ("super-responders") while 55 required ≥ 4 mg/d. 5-HT concentrations in rectal biopsies were significantly lower in super-responders (21.3 (17.0-31.8) vs 37.7 (21.4-61.4), P = .0357) and the increase in transit time on ondansetron was significantly greater (15.6 (1.8-31) hours vs 3.9 (-5.1-17.9) hours). Stool consistency responders were more likely to carry the CC genotype of the SNP p.N163K rs6766410 of the HTR3C gene (33% vs 14%, P = .0066). CONCLUSION IBS-D patients have significant abnormalities in mucosal 5-HT metabolism. Those with the lowest concentration of 5-HT in rectal biopsies showed the greatest responsiveness to ondansetron.
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Affiliation(s)
- David Gunn
- NIHR Nottingham Biomedical Research CentreNottingham University Hospitals NHS Trust and the University of NottinghamNottinghamUK,Nottingham Digestive Diseases Centre, School of MedicineUniversity of NottinghamNottinghamUK
| | | | - Ching Lam
- Northern General Hospital, Sheffield Teaching Hospitals NHS Foundation TrustSheffieldUK
| | - Gulzar Singh
- NIHR Nottingham Biomedical Research CentreNottingham University Hospitals NHS Trust and the University of NottinghamNottinghamUK,Nottingham Digestive Diseases Centre, School of MedicineUniversity of NottinghamNottinghamUK
| | - Melanie Lingaya
- NIHR Nottingham Biomedical Research CentreNottingham University Hospitals NHS Trust and the University of NottinghamNottinghamUK,Nottingham Digestive Diseases Centre, School of MedicineUniversity of NottinghamNottinghamUK
| | - Verena Wahl
- Department of Human Molecular Genetics, Institute of Human GeneticsUniversity Hospital Heidelberg and Interdisciplinary Center for Neurosciences (IZN), University of HeidelbergHeidelbergGermany
| | - Beate Niesler
- Department of Human Molecular Genetics, Institute of Human GeneticsUniversity Hospital Heidelberg and Interdisciplinary Center for Neurosciences (IZN), University of HeidelbergHeidelbergGermany
| | - Amanda Henry
- Department of Therapeutics and Molecular MedicineNIHR Nottingham Biomedical Research CentreNottinghamUK
| | - Ian P. Hall
- Department of Therapeutics and Molecular MedicineNIHR Nottingham Biomedical Research CentreNottinghamUK
| | - Peter Whorwell
- Department of NeurogastroenterologyUniversity of South Manchester Wythenshawe General HospitalManchesterUK
| | - Robin Spiller
- NIHR Nottingham Biomedical Research CentreNottingham University Hospitals NHS Trust and the University of NottinghamNottinghamUK,Nottingham Digestive Diseases Centre, School of MedicineUniversity of NottinghamNottinghamUK
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8
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Hamzah HH, Keattch O, Yeoman MS, Covill D, Patel BA. Three-Dimensional-Printed Electrochemical Sensor for Simultaneous Dual Monitoring of Serotonin Overflow and Circular Muscle Contraction. Anal Chem 2019; 91:12014-12020. [DOI: 10.1021/acs.analchem.9b02958] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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9
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MacEachern SJ, Keenan CM, Papakonstantinou E, Sharkey KA, Patel BA. Alterations in melatonin and 5-HT signalling in the colonic mucosa of mice with dextran-sodium sulfate-induced colitis. Br J Pharmacol 2018; 175:1535-1547. [PMID: 29447434 DOI: 10.1111/bph.14163] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 01/16/2018] [Accepted: 02/03/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND PURPOSE Inflammatory bowel disease (IBD) is characterized by pain, bleeding, cramping and altered gastrointestinal (GI) function. Changes in mucosal 5-HT (serotonin) signalling occur in animal models of colitis and in humans suffering from IBD. Melatonin is co-released with 5-HT from the mucosa and has a wide variety of actions in the GI tract. Here, we examined how melatonin signalling is affected by colitis and determined how this relates to 5-HT signalling. EXPERIMENTAL APPROACH Using electroanalytical approaches, we investigated how 5-HT release, reuptake and availability as well as melatonin availability are altered in dextran sodium sulfate (DSS)-induced colitis in mice. Studies were conducted to explore if melatonin treatment during active colitis could reduce the severity of colitis. KEY RESULTS We observed an increase in 5-HT and a decrease in melatonin availability in DSS-induced colitis. A significant reduction in 5-HT reuptake was observed in DSS-induced colitis animals. A reduction in the content of 5-HT was observed, but no difference in tryptophan levels were observed. A reduction in deoxycholic acid-stimulated 5-HT availability and a significant reduction in mechanically-stimulated 5-HT and melatonin availability were observed in DSS-induced colitis. Orally or rectally administered melatonin once colitis was established did not significantly suppress inflammation. CONCLUSION AND IMPLICATIONS Our data suggest that DSS-induced colitis results in a reduction in melatonin availability and an increase in 5-HT availability, due to a reduction/loss of tryptophan hydroxylase 1 enzyme, 5-HT content and 5-HT transporters. Mechanosensory release was more susceptible to inflammation when compared with chemosensory release.
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Affiliation(s)
- Sarah J MacEachern
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.,Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Catherine M Keenan
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.,Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | | | - Keith A Sharkey
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.,Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Bhavik Anil Patel
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Brighton, UK.,Centre for Stress and Age-related Diseases, University of Brighton, Huxley Building, Brighton, UK
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Patel N, Fagan-Murphy A, Covill D, Patel BA. 3D Printed Molds Encompassing Carbon Composite Electrodes To Conduct Multisite Monitoring in the Entire Colon. Anal Chem 2017; 89:11690-11696. [DOI: 10.1021/acs.analchem.7b03148] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Nirav Patel
- School
of Pharmacy and Biomolecular Sciences, ‡Centre for Stress and Age-Related
Diseases, and §School of Computing, Engineering and Mathematics, University of Brighton, Brighton BN2 4AT, U.K
| | - Aidan Fagan-Murphy
- School
of Pharmacy and Biomolecular Sciences, ‡Centre for Stress and Age-Related
Diseases, and §School of Computing, Engineering and Mathematics, University of Brighton, Brighton BN2 4AT, U.K
| | - Derek Covill
- School
of Pharmacy and Biomolecular Sciences, ‡Centre for Stress and Age-Related
Diseases, and §School of Computing, Engineering and Mathematics, University of Brighton, Brighton BN2 4AT, U.K
| | - Bhavik Anil Patel
- School
of Pharmacy and Biomolecular Sciences, ‡Centre for Stress and Age-Related
Diseases, and §School of Computing, Engineering and Mathematics, University of Brighton, Brighton BN2 4AT, U.K
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Smith TK, Koh SD. A model of the enteric neural circuitry underlying the generation of rhythmic motor patterns in the colon: the role of serotonin. Am J Physiol Gastrointest Liver Physiol 2017; 312:G1-G14. [PMID: 27789457 PMCID: PMC5283906 DOI: 10.1152/ajpgi.00337.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 10/19/2016] [Indexed: 01/31/2023]
Abstract
We discuss the role of multiple cell types involved in rhythmic motor patterns in the large intestine that include tonic inhibition of the muscle layers interrupted by rhythmic colonic migrating motor complexes (CMMCs) and secretomotor activity. We propose a model that assumes these motor patterns are dependent on myenteric descending 5-hydroxytryptamine (5-HT, serotonin) interneurons. Asynchronous firing in 5-HT neurons excite inhibitory motor neurons (IMNs) to generate tonic inhibition occurring between CMMCs. IMNs release mainly nitric oxide (NO) to inhibit the muscle, intrinsic primary afferent neurons (IPANs), glial cells, and pacemaker myenteric pacemaker interstitial cells of Cajal (ICC-MY). Mucosal release of 5-HT from enterochromaffin (EC) cells excites the mucosal endings of IPANs that synapse with 5-HT descending interneurons and perhaps ascending interneurons, thereby coupling EC cell 5-HT to myenteric 5-HT neurons, synchronizing their activity. Synchronized 5-HT neurons generate a slow excitatory postsynaptic potential in IPANs via 5-HT7 receptors and excite glial cells and ascending excitatory nerve pathways that are normally inhibited by NO. Excited glial cells release prostaglandins to inhibit IMNs (disinhibition) to allow full excitation of ICC-MY and muscle by excitatory motor neurons (EMNs). EMNs release ACh and tachykinins to excite pacemaker ICC-MY and muscle, leading to the simultaneous contraction of both the longitudinal and circular muscle layers. Myenteric 5-HT neurons also project to the submucous plexus to couple motility with secretion, especially during a CMMC. Glial cells are necessary for switching between different colonic motor behaviors. This model emphasizes the importance of myenteric 5-HT neurons and the likely consequence of their coupling and uncoupling to mucosal 5-HT by IPANs during colonic motor behaviors.
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Affiliation(s)
- Terence Keith Smith
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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