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Ringuet MT, Koo A, Furness SGB, McDougall SJ, Furness JB. Sites and mechanisms of action of colokinetics at dopamine, ghrelin and serotonin receptors in the rodent lumbosacral defecation centre. J Physiol 2023; 601:5195-5211. [PMID: 37772438 PMCID: PMC10952827 DOI: 10.1113/jp285217] [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: 07/04/2023] [Accepted: 09/13/2023] [Indexed: 09/30/2023] Open
Abstract
Agonists of dopamine D2 receptors (D2R), 5-hydroxytryptamine (5-HT, serotonin) receptors (5-HTR) and ghrelin receptors (GHSR) activate neurons in the lumbosacral defecation centre, and act as 'colokinetics', leading to increased propulsive colonic motility, in vivo. In the present study, we investigated which neurons in the lumbosacral defecation centre express the receptors and whether dopamine, serotonin and ghrelin receptor agonists act on the same lumbosacral preganglionic neurons (PGNs). We used whole cell electrophysiology to record responses from neurons in the lumbosacral defecation centre, following colokinetic application, and investigated their expression profiles and the chemistries of their neural inputs. Fluorescence in situ hybridisation revealed Drd2, Ghsr and Htr2C transcripts were colocalised in lumbosacral PGNs of mice, and immunohistochemistry showed that these neurons have closely associated tyrosine hydroxylase and 5-HT boutons. Previous studies showed that they do not receive ghrelin inputs. Whole cell electrophysiology in adult mice spinal cord revealed that dopamine, serotonin, α-methylserotonin and capromorelin each caused inward, excitatory currents in overlapping populations of lumbosacral PGNs. Furthermore, dopamine caused increased frequency of both IPSCs and EPSCs in a cohort of D2R neurons. Tetrodotoxin blocked the IPSCs and EPSCs, revealing a post-synaptic excitatory action of dopamine. In lumbosacral PGNs of postnatal day 7-14 rats, only dopamine's postsynaptic effects were observed. Furthermore, inward, excitatory currents evoked by dopamine were reduced by the GHSR antagonist, YIL781. We conclude that lumbosacral PGNs are the site where the action of endogenous ligands of D2R and 5-HT2R converge, and that GHSR act as a cis-modulator of D2R expressed by the same neurons. KEY POINTS: Dopamine, 5-hydroxytryptamine (5-HT, serotonin) and ghrelin (GHSR) receptor agonists increase colorectal motility and have been postulated to act at receptors on parasympathetic preganglionic neurons (PGNs) in the lumbosacral spinal cord. We aimed to determine which neurons in the lumbosacral spinal cord express dopamine, serotonin and GHSR receptors, their neural inputs, and whether agonists at these receptors excite them. We show that dopamine, serotonin and ghrelin receptor transcripts are contained in the same PGNs and that these neurons have closely associated tyrosine hydroxylase and serotonin boutons. Whole cell electrophysiology revealed that dopamine, serotonin and GHSR receptor agonists induce an inward excitatory current in overlapping populations of lumbosacral PGNs. Dopamine-induced excitation was reversed by GHSR antagonism. The present study demonstrates that lumbosacral PGNs are the site at which actions of endogenous ligands of dopamine D2 receptors and 5-HT type 2 receptors converge. Ghrelin receptors are functional, but their role appears to be as modulators of dopamine effects at D2 receptors.
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Affiliation(s)
- Mitchell T. Ringuet
- Department of Anatomy & PhysiologyUniversity of MelbourneMelbourneVICAustralia
| | - Ada Koo
- Department of Anatomy & PhysiologyUniversity of MelbourneMelbourneVICAustralia
| | - Sebastian G. B. Furness
- School of Biomedical SciencesUniversity of QueenslandBrisbaneQLDAustralia
- Monash Institute of Pharmaceutical SciencesMelbourneVICAustralia
| | - Stuart J. McDougall
- Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVICAustralia
| | - John B. Furness
- Department of Anatomy & PhysiologyUniversity of MelbourneMelbourneVICAustralia
- Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVICAustralia
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2
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Bukhari SNA. An insight into the multifunctional role of ghrelin and structure activity relationship studies of ghrelin receptor ligands with clinical trials. Eur J Med Chem 2022; 235:114308. [PMID: 35344905 DOI: 10.1016/j.ejmech.2022.114308] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 02/06/2022] [Accepted: 03/18/2022] [Indexed: 11/30/2022]
Abstract
Ghrelin is a multifunctional gastrointestinal acylated peptide, primarily synthesized in the stomach and regulates the secretion of growth hormone and energy homeostasis. It plays a central role in modulating the diverse biological, physiological and pathological functions in vertebrates. The synthesis of ghrelin receptor ligands after the finding of growth hormone secretagogue developed from Met-enkephalin led to reveal the endogenous ligand ghrelin and the receptors. Subsequently, many peptides, small molecules and peptidomimetics focusing on the ghrelin receptor, GHS-R1a, were derived. In this review, the key features of ghrelin's structure, forms, its bio-physiological functions, pathological roles and therapeutic potential have been highlighted. A few peptidomimetics and pseudo peptide synthetic perspectives have also been discussed to make ghrelin receptor ligands, clinical trials and their success.
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Affiliation(s)
- Syed Nasir Abbas Bukhari
- Department of Pharmaceutical Chemistry, College of Pharmacy, Jouf University, Sakaka, Aljouf, 2014, Saudi Arabia.
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3
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Giorgioni G, Del Bello F, Quaglia W, Botticelli L, Cifani C, Micioni Di Bonaventura E, Micioni Di Bonaventura MV, Piergentili A. Advances in the Development of Nonpeptide Small Molecules Targeting Ghrelin Receptor. J Med Chem 2022; 65:3098-3118. [PMID: 35157454 PMCID: PMC8883476 DOI: 10.1021/acs.jmedchem.1c02191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ghrelin is an octanoylated peptide acting by the activation of the growth hormone secretagogue receptor, namely, GHS-R1a. The involvement of ghrelin in several physiological processes, including stimulation of food intake, gastric emptying, body energy balance, glucose homeostasis, reduction of insulin secretion, and lipogenesis validates the considerable interest in GHS-R1a as a promising target for the treatment of numerous disorders. Over the years, several GHS-R1a ligands have been identified and some of them have been extensively studied in clinical trials. The recently resolved structures of GHS-R1a bound to ghrelin or potent ligands have provided useful information for the design of new GHS-R1a drugs. This perspective is focused on the development of recent nonpeptide small molecules acting as GHS-R1a agonists, antagonists, and inverse agonists, bearing classical or new molecular scaffolds, as well as on radiolabeled GHS-R1a ligands developed for imaging. Moreover, the pharmacological effects of the most studied ligands have been discussed.
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Affiliation(s)
- Gianfabio Giorgioni
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy
| | - Fabio Del Bello
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy
| | - Wilma Quaglia
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy
| | - Luca Botticelli
- School of Pharmacy, Pharmacology Unit, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, Italy
| | - Carlo Cifani
- School of Pharmacy, Pharmacology Unit, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, Italy
| | - E Micioni Di Bonaventura
- School of Pharmacy, Pharmacology Unit, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, Italy
| | - M V Micioni Di Bonaventura
- School of Pharmacy, Pharmacology Unit, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, Italy
| | - Alessandro Piergentili
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy
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Furness JB, Pustovit RV, Syder AJ, Ringuet MT, Yoo EJ, Fanjul A, Wykosky J, Fothergill LJ, Whitfield EA, Furness SGB. Dopamine and ghrelin receptor co-expression and interaction in the spinal defecation centers. Neurogastroenterol Motil 2021; 33:e14051. [PMID: 33264473 DOI: 10.1111/nmo.14051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 10/20/2020] [Accepted: 11/12/2020] [Indexed: 12/24/2022]
Abstract
BACKGROUND Dopamine receptor 2 (DRD2) and ghrelin receptor (GHSR1a) agonists both stimulate defecation by actions at the lumbosacral defecation center. Dopamine is in nerve terminals surrounding autonomic neurons of the defecation center, whereas ghrelin is not present in the spinal cord. Dopamine at D2 receptors generally inhibits neurons, but at the defecation center, its effect is excitatory. METHODS In vivo recording of defecation and colorectal propulsion was used to investigate interaction between DRD2 and GHSR1a. Localization studies were used to determine sites of receptor expression in rat and human spinal cord. KEY RESULTS Dopamine, and the DRD2 agonist, quinpirole, directly applied to the lumbosacral cord, caused defecation. The effect of intrathecal dopamine was inhibited by the GHSR1a antagonist, YIL781, given systemically, but YIL781 was not an antagonist at DRD2. The DRD2 agonist, pramipexole, administered systemically caused colorectal propulsion that was prevented when the pelvic nerves were cut. Drd2 and Ghsr were expressed together in autonomic preganglionic neurons at the level of the defecation centers in rat and human. Behaviorally induced defecation (caused by water avoidance stress) was reduced by the DRD2 antagonist, sulpiride. We had previously shown it is reduced by YIL781. CONCLUSIONS AND INFERENCES Our observations imply that dopamine is a transmitter of the defecation pathways whose actions are exerted through interacting dopamine (D2) and ghrelin receptors on lumbosacral autonomic neurons that project to the colorectum. The results explain the excitation by dopamine agonists and the conservation of GHSR1a in the absence of ghrelin.
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Affiliation(s)
- John B Furness
- Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia.,Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Vic., Australia
| | - Ruslan V Pustovit
- Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia.,Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Vic., Australia
| | - Andrew J Syder
- Gastroenterology Drug Discovery Unit, Takeda Pharmaceutical Company Limited, San Diego, CA, USA
| | - Mitchell T Ringuet
- Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia.,Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Vic., Australia
| | - Eun Ji Yoo
- Gastroenterology Drug Discovery Unit, Takeda Pharmaceutical Company Limited, San Diego, CA, USA
| | - Andrea Fanjul
- Gastroenterology Drug Discovery Unit, Takeda Pharmaceutical Company Limited, San Diego, CA, USA
| | - Jill Wykosky
- Gastroenterology Drug Discovery Unit, Takeda Pharmaceutical Company Limited, San Diego, CA, USA
| | - Linda J Fothergill
- Florey Institute of Neuroscience and Mental Health, Parkville, Vic., Australia.,Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
| | - Emily A Whitfield
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
| | - Sebastian G B Furness
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic., Australia
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Lange T, Thomas A, Görgens C, Bidlingmaier M, Schilbach K, Fichant E, Delahaut P, Thevis M. Comprehensive insights into the formation of metabolites of the ghrelin mimetics capromorelin, macimorelin and tabimorelin as potential markers for doping control purposes. Biomed Chromatogr 2021; 35:e5075. [PMID: 33458843 DOI: 10.1002/bmc.5075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/11/2021] [Accepted: 01/14/2021] [Indexed: 12/25/2022]
Abstract
Analytical methods to determine the potential misuse of the ghrelin mimetics capromorelin (CP-424,391), macimorelin (macrilen, EP-01572) and tabimorelin (NN703) in sports were developed. Therefore, different extraction strategies, i.e. solid-phase extraction, protein precipitation, as well as a "dilute-and-inject" approach, from urine and EDTA-plasma were assessed and comprehensive in vitro/in vivo experiments were conducted, enabling the identification of reliable target analytes by means of high resolution mass spectrometry. The drugs' biotransformation led to the preliminary identification of 51 metabolites of capromorelin, 12 metabolites of macimorelin and 13 metabolites of tabimorelin. Seven major metabolites detected in rat urine samples collected post-administration of 0.5-1.0 mg of a single oral dose underwent in-depth characterization, facilitating their implementation into future confirmatory test methods. In particular, two macimorelin metabolites exhibiting considerable abundances in post-administration rat urine samples were detected, which might contribute to an improved sensitivity, specificity, and detection window in case of human sports drug testing programs. Further, the intact drugs were implemented into World Anti-Doping Agency-compliant initial testing (limits of detection 0.02-0.60 ng/ml) and confirmation procedures (limits of identification 0.18-0.89 ng/ml) for human urine and blood matrices. The obtained results allow extension of the test spectrum of doping agents in multitarget screening assays for growth hormone-releasing factors from human urine.
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Affiliation(s)
- Tobias Lange
- Center for Preventive Doping Research/Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, Cologne, 50933, Germany
| | - Andreas Thomas
- Center for Preventive Doping Research/Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, Cologne, 50933, Germany
| | - Christian Görgens
- Center for Preventive Doping Research/Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, Cologne, 50933, Germany
| | - Martin Bidlingmaier
- Endocrine Laboratory, Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Ziemssenstraße 1, Munich, 80336, Germany
| | - Katharina Schilbach
- Endocrine Laboratory, Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Ziemssenstraße 1, Munich, 80336, Germany
| | - Eric Fichant
- Département Santé, CER Groupe, Rue du Point du Jour 8, Marloie, 6900, Belgium
| | - Philippe Delahaut
- Département Santé, CER Groupe, Rue du Point du Jour 8, Marloie, 6900, Belgium
| | - Mario Thevis
- Center for Preventive Doping Research/Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, Cologne, 50933, Germany.,European Monitoring Center for Emerging Doping Agents, Am Sportpark Müngersdorf 6, Cologne, 50933, Germany
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6
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Chai XY, Diwakarla S, Pustovit RV, McQuade RM, Di Natale M, Ermine CM, Parish CL, Finkelstein DI, Furness JB. Investigation of nerve pathways mediating colorectal dysfunction in Parkinson's disease model produced by lesion of nigrostriatal dopaminergic neurons. Neurogastroenterol Motil 2020; 32:e13893. [PMID: 32512642 DOI: 10.1111/nmo.13893] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/02/2020] [Accepted: 05/04/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND Gastrointestinal (GI) dysfunction, including constipation, is a common non-motor symptom of Parkinson's disease (PD). The toxin 6-hydroxydopamine (6OHDA) produces the symptoms of PD, surprisingly including constipation, after it is injected into the medial forebrain bundle (MFB). However, the mechanisms involved in PD-associated constipation caused by central application of 6OHDA remain unknown. We investigated effects of 6OHDA lesioning of the MFB on motor performance and GI function. METHODS Male Sprague Dawley rats were unilaterally injected with 6OHDA in the MFB. Colorectal propulsion was assessed by bead expulsion after 4 weeks and by recording colorectal contractions and propulsion after 5 weeks. Enteric nervous system (ENS) neuropathy was examined by immunohistochemistry. KEY RESULTS When compared to shams, 6OHDA-lesioned rats had significantly increased times of bead expulsion from the colorectum, indicative of colon dysmotility. Administration of the colokinetic, capromorelin, that stimulates defecation centers in the spinal cord, increased the number of contractions and colorectal propulsion in both groups compared to baseline; however, the effectiveness of capromorelin in 6OHDA-lesioned rats was significantly reduced in comparison with shams, indicating that 6OHDA animals have reduced responsiveness of the spinal defecation centers. Enteric neuropathy was observed in the distal colon, revealing that lesion of the MFB has downstream effects at the cellular level, remote from the site of 6OHDA administration. CONCLUSIONS & INFERENCES We conclude that there are trans-synaptic effects of the proximal, forebrain, lesion of pathways from the brain that send signals down the spinal cord, at the levels of the defecation centers and the ENS.
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Affiliation(s)
- Xin-Yi Chai
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Vic, Australia
| | - Shanti Diwakarla
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Vic, Australia
| | - Ruslan V Pustovit
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Vic, Australia.,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Vic, Australia
| | - Rachel M McQuade
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Vic, Australia.,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Vic, Australia
| | - Madeleine Di Natale
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Vic, Australia.,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Vic, Australia
| | - Charlotte M Ermine
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Vic, Australia
| | - Clare L Parish
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Vic, Australia
| | - David I Finkelstein
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Vic, Australia
| | - John B Furness
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Vic, Australia.,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Vic, Australia
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Holmes GM, Blanke EN. Gastrointestinal dysfunction after spinal cord injury. Exp Neurol 2019; 320:113009. [PMID: 31299180 PMCID: PMC6716787 DOI: 10.1016/j.expneurol.2019.113009] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 06/13/2019] [Accepted: 07/07/2019] [Indexed: 12/12/2022]
Abstract
The gastrointestinal tract of vertebrates is a heterogeneous organ system innervated to varying degrees by a local enteric neural network as well as extrinsic parasympathetic and sympathetic neural circuits located along the brainstem and spinal axis. This diverse organ system serves to regulate the secretory and propulsive reflexes integral to the digestion and absorption of nutrients. The quasi-segmental distribution of the neural circuits innervating the gastrointestinal (GI) tract produces varying degrees of dysfunction depending upon the level of spinal cord injury (SCI). At all levels of SCI, GI dysfunction frequently presents life-long challenges to individuals coping with injury. Growing attention to the profound changes that occur across the entire physiology of individuals with SCI reveals profound knowledge gaps in our understanding of the temporal dimensions and magnitude of organ-specific co-morbidities following SCI. It is essential to understand and identify these broad pathophysiological changes in order to develop appropriate evidence-based strategies for management by clinicians, caregivers and individuals living with SCI. This review summarizes the neurophysiology of the GI tract in the uninjured state and the pathophysiology associated with the systemic effects of SCI.
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Affiliation(s)
- Gregory M Holmes
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, United states of America.
| | - Emily N Blanke
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, United states of America
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Ruan W, Ning G, Feng S, Gao S, Hao Y. MicroRNA‑381/Hes1 is a potential therapeutic target for spinal cord injury. Int J Mol Med 2018; 42:1008-1017. [PMID: 29750292 DOI: 10.3892/ijmm.2018.3658] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 01/17/2018] [Indexed: 11/06/2022] Open
Abstract
The aim of the present study was to investigate whether microRNA‑381 is a potential therapeutic target for spinal cord injury (SCI) and its possible mechanism. Reverse transcription quantitative polymerase chain reaction (qPCR) for mRNA expression was used to analyze the changes of microRNA-381 expression. Cell viability and cell apoptosis were measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry. Caspase‑3 activity was measured using caspase‑3 activity kit, and western blot analysis was used to measure the protein expression of neurogenic locus notch homolog protein 1 (Notch1), notch 1 intracellular domain (NICD) and transcription factor HES-1 (Hes1). The data showed that microRNA‑381 expression of model SCI rats was downregulated compared with that of control rats. Overexpression of microRNA‑381 promoted cell proliferation, and inhibited apoptosis and caspase‑3 and apoptosis regulator BAX (Bax) protein expression in neurocytes. Overexpression of microRNA‑381 also increased Wnt and β‑catenin protein expression, and suppressed the protein expression of Notch1, NICD and Hes1 in neurocytes. Wnt inhibitor, Wnt‑C59 (1 µmol/l), inhibited cell proliferation, promoted apoptosis and caspase‑3 and Bax protein expression, suppressed β‑catenin protein expression and induced Hes1 protein expression in neurocytes following microRNA‑381 overexpression. Notch inhibitor, FLI‑06 (1 µmol/l), promoted cell proliferation, inhibited apoptosis and caspase‑3 and Bax protein expression, and suppressed NICD and Hes1 protein expression in neurocytes following microRNA‑381 overexpression. Thus, this study showed that overexpression of microRNA‑381 promotes cell proliferation of neurocytes in SCI via Hes1 expression, which may be a novel important mechanism for SCI in clinical applications.
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Affiliation(s)
- Wendong Ruan
- Department of Orthopedics, The General Hospital of Tianjin Medical University, Heping, Tianjin 300052, P.R. China
| | - Guangzhi Ning
- Department of Orthopedics, The General Hospital of Tianjin Medical University, Heping, Tianjin 300052, P.R. China
| | - Shiqing Feng
- Department of Orthopedics, The General Hospital of Tianjin Medical University, Heping, Tianjin 300052, P.R. China
| | - Shijie Gao
- Department of Orthopedics, The General Hospital of Tianjin Medical University, Heping, Tianjin 300052, P.R. China
| | - Yan Hao
- Department of Orthopedics, The General Hospital of Tianjin Medical University, Heping, Tianjin 300052, P.R. China
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9
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Pustovit RV, Callaghan B, Ringuet MT, Kerr NF, Hunne B, Smyth IM, Pietra C, Furness JB. Evidence that central pathways that mediate defecation utilize ghrelin receptors but do not require endogenous ghrelin. Physiol Rep 2018; 5:5/15/e13385. [PMID: 28801520 PMCID: PMC5555902 DOI: 10.14814/phy2.13385] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 07/17/2017] [Accepted: 07/20/2017] [Indexed: 01/24/2023] Open
Abstract
In laboratory animals and in human, centrally penetrant ghrelin receptor agonists, given systemically or orally, cause defecation. Animal studies show that the effect is due to activation of ghrelin receptors in the spinal lumbosacral defecation centers. However, it is not known whether there is a physiological role of ghrelin or the ghrelin receptor in the control of defecation. Using immunohistochemistry and immunoassay, we detected and measured ghrelin in the stomach, but were unable to detect ghrelin by either method in the lumbosacral spinal cord, or other regions of the CNS. In rats in which the thoracic spinal cord was transected 5 weeks before, the effects of a ghrelin agonist on colorectal propulsion were significantly enhanced, but defecation caused by water avoidance stress (WAS) was reduced. In knockout rats that expressed no ghrelin and in wild‐type rats, WAS‐induced defecation was reduced by a ghrelin receptor antagonist, to similar extents. We conclude that the ghrelin receptors of the lumbosacral defecation centers have a physiological role in the control of defecation, but that their role is not dependent on ghrelin. This implies that a transmitter other than ghrelin engages the ghrelin receptor or a ghrelin receptor complex.
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Affiliation(s)
- Ruslan V Pustovit
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Victoria, Australia.,Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Brid Callaghan
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Victoria, Australia
| | - Mitchell T Ringuet
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Victoria, Australia.,Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Nicole F Kerr
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Victoria, Australia
| | - Billie Hunne
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Victoria, Australia
| | - Ian M Smyth
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria, Australia
| | - Claudio Pietra
- Helsinn Research and Preclinical Department, Lugano, Switzerland
| | - John B Furness
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Victoria, Australia .,Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
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10
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Neural pathways for colorectal control, relevance to spinal cord injury and treatment: a narrative review. Spinal Cord 2017; 56:199-205. [PMID: 29142293 DOI: 10.1038/s41393-017-0026-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 10/02/2017] [Accepted: 10/03/2017] [Indexed: 02/08/2023]
Abstract
STUDY DESIGN Narrative review. OBJECTIVES The purpose is to review the organisation of the nerve pathways that control defecation and to relate this knowledge to the deficits in colorectal function after SCI. METHODS A literature review was conducted to identify salient features of defecation control pathways and the functional consequences of damage to these pathways in SCI. RESULTS The control pathways for defecation have separate pontine centres under cortical control that influence defecation. The pontine centres connect, separately, with autonomic preganglionic neurons of the spinal defecation centres and somatic motor neurons of Onuf's nucleus in the sacral spinal cord. Organised propulsive motor patterns can be generated by stimulation of the spinal defecation centres. Activation of the somatic neurons contracts the external sphincter. The analysis aids in interpreting the consequences of SCI and predicts therapeutic strategies. CONCLUSIONS Analysis of the bowel control circuits identifies sites at which bowel function may be modulated after SCI. Colokinetic drugs that elicit propulsive contractions of the colorectum may provide valuable augmentation of non-pharmacological bowel management procedures.
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Abstract
Ghrelin and motilin are released from gastrointestinal endocrine cells during hunger, to act through G protein-coupled receptors that have closely related amino acid sequences. The actions of ghrelin are more complex than motilin because ghrelin also exists outside the GI tract, it is processed to des-acyl ghrelin which has activity, ghrelin can exist in truncated forms and retain activity, the ghrelin receptor can have constitutive activity and is subject to biased agonism and finally additional ghrelin-like and des-acyl ghrelin receptors are proposed. Both ghrelin and motilin can stimulate gastric emptying, acting via different pathways, perhaps influenced by biased agonism at the receptors, but research is revealing additional pathways of activity. For example, it is becoming apparent that reduction of nausea may be a key therapeutic target for ghrelin receptor agonists and perhaps for compounds that modulate the constitutive activity of the ghrelin receptor. Reduction of nausea may be the mechanism through which gastroparesis symptoms are reduced. Intriguingly, a potential ability of motilin to influence nausea is also becoming apparent. Ghrelin interacts with digestive function through its effects on appetite, and ghrelin antagonists may have a place in treating Prader-Willi syndrome. Unlike motilin, ghrelin receptor agonists also have the potential to treat constipation by acting at the lumbosacral defecation centres. In conclusion, agonists of both ghrelin and motilin receptors hold potential as treatments for specific subsets of digestive system disorders.
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Mosińska P, Zatorski H, Storr M, Fichna J. Future Treatment of Constipation-associated Disorders: Role of Relamorelin and Other Ghrelin Receptor Agonists. J Neurogastroenterol Motil 2017; 23:171-179. [PMID: 28238253 PMCID: PMC5383112 DOI: 10.5056/jnm16183] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 12/19/2016] [Accepted: 01/08/2017] [Indexed: 12/22/2022] Open
Abstract
There is an unmet need for effective pharmacological therapies for constipation, a symptom that significantly deteriorates patients’ quality of life and impacts health care. Ghrelin is an endogenous ligand for the growth hormone secretagogue receptor and has been shown to exert prokinetic effects on gastrointestinal (GI) motility via the vagus and pelvic nerves. The pharmacological potential of ghrelin is hampered by its short half-life. Ghrelin receptor (GRLN-R) agonists with enhanced pharmacokinetics were thus developed. Centrally penetrant GRLN-R agonists stimulate defecation and improve impaired lower GI transit in animals and humans. This review summarizes the current knowledge on relamorelin, a potent ghrelin mimetic, and other GRLN-R analogs which are in preclinical or clinical stages of development for the management of disorders with underlying GI hypomotility, like constipation.
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Affiliation(s)
- Paula Mosińska
- Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
| | - Hubert Zatorski
- Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
| | - Martin Storr
- Center of Endoscopy, Starnberg, Germany and Walter-Brendel-Centre, Ludwig-Maximilians University Munich, Munich, Germany
| | - Jakub Fichna
- Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
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Dinning PG, Sia TC, Kumar R, Mohd Rosli R, Kyloh M, Wattchow DA, Wiklendt L, Brookes SJH, Costa M, Spencer NJ. High-resolution colonic motility recordings in vivo compared with ex vivo recordings after colectomy, in patients with slow transit constipation. Neurogastroenterol Motil 2016; 28:1824-1835. [PMID: 27282132 DOI: 10.1111/nmo.12884] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/11/2016] [Indexed: 12/13/2022]
Abstract
BACKGROUND The pathogenesis of slow transit constipation (STC) remains poorly understood, with intrinsic and extrinsic abnormalities implicated. Here, we present high-resolution colonic manometry recordings from four STC patients recorded before total colectomy, and subsequently, ex vivo, after excision. METHODS In four female, treatment-resistant STC patients (median age 35.5 years), a fiber-optic manometry catheter (72 sensors spaced at 1 cm intervals) was placed with the aid of a colonoscope, to the mid-transverse colon. Colonic manometry was recorded 2 h before and after a meal. After the colectomy, ex vivo colonic manometry was recorded in an organ bath. Ex vivo recordings were also made from colons from 4 patients (2 male; median age 67.5 years) undergoing anterior resection for nonobstructive carcinoma ('control' tissue). KEY RESULTS A large increase in 'short single propagating contractions' was recorded in STC colon ex vivo compared to in vivo (ex vivo 61.3 ± 32.7 vs in vivo 2.5 ± 5/h). In STC patients, in vivo, the dominant frequency of contractile activity was 2-3 cycle per minute (cpm), whereas 1-cpm short-single propagating contractions dominated ex vivo. This same 1-cpm frequency was also dominant in control colons ex vivo. CONCLUSIONS & INFERENCES In comparison to control adults, the colon of STC patients demonstrates significantly less propagating motor activity. However, once the STC colon is excised from the body it demonstrates a regular and similar frequency of propagating activity to control tissue. This paper provides interesting insights into the control of colonic motor patterns.
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Affiliation(s)
- P G Dinning
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia.,Departments of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - T C Sia
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia.,Departments of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - R Kumar
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia.,Departments of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - R Mohd Rosli
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia.,Departments of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - M Kyloh
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - D A Wattchow
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia.,Departments of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - L Wiklendt
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - S J H Brookes
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - M Costa
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - N J Spencer
- Disciplines of Human Physiology, Flinders University, Bedford Park, SA, Australia
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Spencer NJ, Dinning PG, Brookes SJ, Costa M. Insights into the mechanisms underlying colonic motor patterns. J Physiol 2016; 594:4099-116. [PMID: 26990133 PMCID: PMC4967752 DOI: 10.1113/jp271919] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 02/26/2016] [Indexed: 12/28/2022] Open
Abstract
In recent years there have been significant technical and methodological advances in our ability to record the movements of the gastrointestinal tract. This has led to significant changes in our understanding of the different types of motor patterns that exist in the gastrointestinal tract (particularly the large intestine) and in our understanding of the mechanisms underlying their generation. Compared with other tubular smooth muscle organs, a rich variety of motor patterns occurs in the large intestine. This reflects a relatively autonomous nervous system in the gut wall, which has its own unique population of sensory neurons. Although the enteric nervous system can function independently of central neural inputs, under physiological conditions bowel motility is influenced by the CNS: if spinal pathways are disrupted, deficits in motility occur. The combination of high resolution manometry and video imaging has improved our knowledge of the range of motor patterns and provided some insight into the neural and mechanical factors underlying propulsion of contents. The neural circuits responsible for the generation of peristalsis and colonic migrating motor complexes have now been identified to lie within the myenteric plexus and do not require inputs from the mucosa or submucosal ganglia for their generation, but can be modified by their activity. This review will discuss the recent advances in our understanding of the different patterns of propagating motor activity in the large intestine of mammals and how latest technologies have led to major changes in our understanding of the mechanisms underlying their generation.
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Affiliation(s)
- Nick J Spencer
- Department of Human Physiology and Centre for Neuroscience, Flinders University of South Australia, Adelaide, Australia
| | - Phil G Dinning
- Department of Human Physiology and Centre for Neuroscience, Flinders University of South Australia, Adelaide, Australia
- Departments of Gastroenterology and Surgery, Flinders Medical Centre, Adelaide, Australia
| | - Simon J Brookes
- Department of Human Physiology and Centre for Neuroscience, Flinders University of South Australia, Adelaide, Australia
| | - Marcello Costa
- Department of Human Physiology and Centre for Neuroscience, Flinders University of South Australia, Adelaide, Australia
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Abstract
The gastrointestinal tract is the major source of the related hormones ghrelin and motilin, which act on structurally similar G protein-coupled receptors. Nevertheless, selective receptor agonists are available. The primary roles of endogenous ghrelin and motilin in the digestive system are to increase appetite or hedonic eating (ghrelin) and initiate phase III of gastric migrating myoelectric complexes (motilin). Ghrelin and motilin also both inhibit nausea. In clinical trials, the motilin receptor agonist camicinal increased gastric emptying, but at lower doses reduced gastroparesis symptoms and improved appetite. Ghrelin receptor agonists have been trialled for the treatment of diabetic gastroparesis because of their ability to increase gastric emptying, but with mixed results; however, relamorelin, a ghrelin agonist, reduced nausea and vomiting in patients with this disorder. Treatment of postoperative ileus with a ghrelin receptor agonist proved unsuccessful. Centrally penetrant ghrelin receptor agonists stimulate defecation in animals and humans, although ghrelin itself does not seem to control colorectal function. Thus, the most promising uses of motilin receptor agonists are the treatment of gastroparesis or conditions with slow gastric emptying, and ghrelin receptor agonists hold potential for the reduction of nausea and vomiting, and the treatment of constipation. Therapeutic, gastrointestinal roles for receptor antagonists or inverse agonists have not been identified.
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Naitou K, Mamerto TP, Pustovit RV, Callaghan B, Rivera LR, Chan AJ, Ringuet MT, Pietra C, Furness JB. Site and mechanism of the colokinetic action of the ghrelin receptor agonist, HM01. Neurogastroenterol Motil 2015; 27:1764-71. [PMID: 26416336 DOI: 10.1111/nmo.12688] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 08/23/2015] [Indexed: 02/06/2023]
Abstract
BACKGROUND It has been recently demonstrated that the ghrelin receptor agonist, HM01, caused defecation in rats that were treated to provide a model for the constipation of Parkinson's disease. HM01 significantly increased fecal output and increased Fos activity in neurons of the hypothalamus and hindbrain, but not in the spinal defecation center. Other ghrelin agonists act on the defecation center. METHODS Receptor pharmacology was examined in ghrelin receptor (GHSR1a) transfected cells. Anesthetized rats were used to investigate sites and mechanisms of action. KEY RESULTS HM01 activated rat GHSR1a at nanomolar concentrations and was antagonized by the GHSR1a antagonist, YIL781. HM01, intravenous, was potent to activate propulsive colorectal contractions. This was prevented by pelvic nerve section and by intravenous YIL781, but not by spinal cord section rostral to the defecation centers. Direct intrathecal application of HM01 to the defecation center at spinal level L6-S1 initiated propulsive contractions of the colorectum. CONCLUSIONS & INFERENCES HM01 stimulates GHSR1a receptors on neurons in the lumbosacral defecation centers to cause propulsive contractions and emptying of the colorectum. It has greater potency when given systemically, compared with other GHSR1a agonists.
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Affiliation(s)
- K Naitou
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, VIC, Australia.,Department of Basic Veterinary Science, Laboratory of Physiology, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - T P Mamerto
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - R V Pustovit
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - B Callaghan
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - L R Rivera
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - A J Chan
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - M T Ringuet
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - C Pietra
- Helsinn Research and Preclinical Department, Lugano, Switzerland
| | - J B Furness
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, VIC, Australia.,Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
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Sessenwein JL, Lomax AE. Ghrelin receptors as targets for novel motility drugs. Neurogastroenterol Motil 2015; 27:589-93. [PMID: 25903396 DOI: 10.1111/nmo.12562] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 03/10/2015] [Indexed: 12/17/2022]
Abstract
Constipation arises from a multitude of causes, including aging, spinal cord injury (SCI), and dietary issues. The heterogeneity of inciting factors has made the treatment of constipation particularly challenging. Agonists of ghrelin receptors have beneficial effects on delayed gastric emptying, but less is known about their ability to improve colorectal motility. Recent publications indicate that the activation of the ghrelin receptors in the spinal cord can alleviate constipation due to dietary causes, Parkinsonism, and SCI in rodents. Ghrelin-responsive neurons in the intermediolateral cell column of the lumbosacral spinal cord can activate enteric microcircuits that coordinate propulsive colorectal contractions, leading to defecation. Learning more about the properties of neurons in the spinal defecation center and the roles of ghrelin receptors in the defecation reflex will accelerate the development of improved treatments of constipation.
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Affiliation(s)
- J L Sessenwein
- Gastrointestinal Diseases Research Unit, Queen's University, Kingston, ON, Canada
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