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Kim M, Oh BY, Lee JS, Yoon D, Chun W, Son IT. A systematic review of translation and experimental studies on internal anal sphincter for fecal incontinence. Ann Coloproctol 2022; 38:183-196. [PMID: 35678021 PMCID: PMC9263305 DOI: 10.3393/ac.2022.00276.0039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 05/10/2022] [Indexed: 12/05/2022] Open
Abstract
The complexity in the molecular mechanism of the internal anal sphincter (IAS) limits preclinical or clinical outcomes of fecal incontinence (FI) treatment. So far, there are no systematic reviews of IAS translation and experimental studies that have been reported. This systematic review aims to provide a comprehensive understanding of IAS critical role in FI. Previous studies revealed the key pathway for basal tone and relaxation of IAS in different properties as follows; calcium, Rho-associated, coiled-coil containing serine/threonine kinase, aging-associated IAS dysfunction, oxidative stress, renin-angiotensin-aldosterone, cyclooxygenase, and inhibitory neurotransmitters. Previous studies have reported improved functional outcomes of cellular treatment for regeneration of dysfunctional IAS, using various stem cells, but did not demonstrate the interrelationship between those results and basal tone or relaxation-related molecular pathway of IAS. Furthermore, these results have lower specificity for IAS-incontinence due to the included external anal sphincter or nerve injury regardless of the cell type. An acellular approach using bioengineered IAS showed a physiologic response of basal tone and relaxation response similar to human IAS. However, in both cellular and acellular approaches, the lack of human IAS data still hampers clinical application. Therefore, the IAS regeneration presents more challenges and warrants more advances.
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Affiliation(s)
- Minsung Kim
- Department of Surgery, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea
| | - Bo-Young Oh
- Department of Surgery, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea
| | - Ji-Seon Lee
- Burn Institute, Hangang Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Dogeon Yoon
- Burn Institute, Hangang Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Wook Chun
- Burn Institute, Hangang Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.,Department of Surgery, Hangang Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Il Tae Son
- Department of Surgery, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea.,Institute for Regenerative Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea
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Hannigan KI, Bossey AP, Foulkes HJL, Drumm BT, Baker SA, Ward SM, Sanders KM, Keef KD, Cobine CA. A novel intramuscular Interstitial Cell of Cajal is a candidate for generating pacemaker activity in the mouse internal anal sphincter. Sci Rep 2020; 10:10378. [PMID: 32587396 PMCID: PMC7316801 DOI: 10.1038/s41598-020-67142-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 06/03/2020] [Indexed: 12/14/2022] Open
Abstract
The internal anal sphincter (IAS) generates phasic contractions and tone. Slow waves (SWs) produced by interstitial cells of Cajal (ICC) underlie phasic contractions in other gastrointestinal regions. SWs are also present in the IAS where only intramuscular ICC (ICC-IM) are found, however the evidence linking ICC-IM to SWs is limited. This study examined the possible relationship between ICC-IM and SWs by recording Ca2+ transients in mice expressing a genetically-encoded Ca2+-indicator in ICC (Kit-Cre-GCaMP6f). A role for L-type Ca2+ channels (CavL) and anoctamin 1 (ANO1) was tested since each is essential for SW and tone generation. Two distinct ICC-IM populations were identified. Type I cells (36% of total) displayed localised asynchronous Ca2+ transients not dependent on CavL or ANO1; properties typical of ICC-IM mediating neural responses in other gastrointestinal regions. A second novel sub-type, i.e., Type II cells (64% of total) generated rhythmic, global Ca2+ transients at the SW frequency that were synchronised with neighbouring Type II cells and were abolished following blockade of either CavL or ANO1. Thus, the spatiotemporal characteristics of Type II cells and their dependence upon CavL and ANO1 all suggest that these cells are viable candidates for the generation of SWs and tone in the IAS.
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Affiliation(s)
- Karen I Hannigan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Aaron P Bossey
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Holly J L Foulkes
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Kathleen D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA.
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Cobine CA, Hannigan KI, McMahon M, Bhraonain EPN, Baker SA, Keef KD. Rhythmic calcium transients in smooth muscle cells of the mouse internal anal sphincter. Neurogastroenterol Motil 2020; 32:e13746. [PMID: 31625250 PMCID: PMC7047590 DOI: 10.1111/nmo.13746] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/22/2019] [Accepted: 09/26/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND The internal anal sphincter (IAS) exhibits slow waves (SWs) and tone that are dependent upon L-type Ca2+ channels (CavL ) suggesting that phasic events (ie, SWs) play a fundamental role in tone generation. The present study further examined phasic activity in the IAS by measuring the spatiotemporal properties of Ca2+ transients (CTs) in IAS smooth muscle cells (SMCs). METHODS Ca2+ transients were recorded with spinning disk confocal microscopy from the IAS of SM-GCaMP mice. Muscles were pinned submucosal surface up at two different lengths. Drugs were applied by inclusion in the superfusate. KEY RESULTS Ca2+ transients displayed ongoing rhythmic firings at both lengths and were abolished by nifedipine and the KATP channel activator pinacidil indicating their dependence upon CavL . Like SWs, CTs were greatest in frequency (average 70.6 cpm) and amplitude at the distal extremity and conducted proximally. Removal of the distal IAS reduced but did not abolish CTs. The time constant for clearing cytoplasmic Ca2+ averaged 0.46 seconds and basal Ca2+ levels were significantly elevated. CONCLUSIONS & INFERENCES The similarities in spatiotemporal and pharmacological properties of CTs and SWs suggest that SW gives rise to CTs while muscle stretch is not required. Elevated relative basal Ca2+ in the IAS is likely due to the inability of cells to clear or sequester Ca2+ between rapid frequency voltage-dependent Ca2+ entry events, that is, conditions that will lead to tone development. The conduction of CTs from distal to proximal IAS will lead to orally directed contractions and likely contribute to the maintenance of fecal continence.
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Affiliation(s)
- Caroline A Cobine
- Corresponding Author: Caroline Cobine, Ph.D., Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, 1664 N. Virginia St., MS 352, Reno, NV 89557, USA, Phone: 1-775-682-8840, Fax: 1-775-784-6903,
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Generation of Spontaneous Tone by Gastrointestinal Sphincters. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019. [PMID: 31183822 DOI: 10.1007/978-981-13-5895-1_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
An important feature of the gastrointestinal (GI) muscularis externa is its ability to generate phasic contractile activity. However, in some GI regions, a more sustained contraction, referred to as "tone," also occurs. Sphincters are muscles oriented in an annular manner that raise intraluminal pressure, thereby reducing or blocking the movement of luminal contents from one compartment to another. Spontaneous tone generation is often a feature of these muscles. Four distinct smooth muscle sphincters are present in the GI tract: the lower esophageal sphincter (LES), the pyloric sphincter (PS), the ileocecal sphincter (ICS), and the internal anal sphincter (IAS). This chapter examines how tone generation contributes to the functional behavior of these sphincters. Historically, tone was attributed to contractile activity arising directly from the properties of the smooth muscle cells. However, there is increasing evidence that interstitial cells of Cajal (ICC) play a significant role in tone generation in GI muscles. Indeed, ICC are present in each of the sphincters listed above. In this chapter, we explore various mechanisms that may contribute to tone generation in sphincters including: (1) summation of asynchronous phasic activity, (2) partial tetanus, (3) window current, and (4) myofilament sensitization. Importantly, the first two mechanisms involve tone generation through summation of phasic events. Thus, the historical distinction between "phasic" versus "tonic" smooth muscles in the GI tract requires revision. As described in this chapter, it is clear that the unique functional role of each sphincter in the GI tract is accompanied by a unique combination of contractile mechanisms.
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Keef KD, Cobine CA. Control of Motility in the Internal Anal Sphincter. J Neurogastroenterol Motil 2019; 25:189-204. [PMID: 30827084 PMCID: PMC6474703 DOI: 10.5056/jnm18172] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/28/2018] [Accepted: 12/09/2018] [Indexed: 12/14/2022] Open
Abstract
The internal anal sphincter (IAS) plays an important role in the maintenance of fecal continence since it generates tone and is responsible for > 70% of resting anal pressure. During normal defecation the IAS relaxes. Historically, tone generation in gastrointestinal muscles was attributed to mechanisms arising directly from smooth muscle cells, ie, myogenic activity. However, slow waves are now known to play a fundamental role in regulating gastrointestinal motility and these electrical events are generated by the interstitial cells of Cajal. Recently, interstitial cells of Cajal, as well as slow waves, have also been identified in the IAS making them viable candidates for tone generation. In this review we discuss four different mechanisms that likely contribute to tone generation in the IAS. Three of these involve membrane potential, L-type Ca2+ channels and electromechanical coupling (ie, summation of asynchronous phasic activity, partial tetanus, and window current), whereas the fourth involves the regulation of myofilament Ca2+ sensitivity. Contractile activity in the IAS is also modulated by sympathetic motor neurons that significantly increase tone and anal pressure, as well as inhibitory motor neurons (particularly nitrergic and vasoactive intestinal peptidergic) that abolish contraction and assist with normal defecation. Alterations in IAS motility are associated with disorders such as fecal incontinence and anal fissures that significantly decrease the quality of life. Understanding in greater detail how tone is regulated in the IAS is important for developing more effective treatment strategies for these debilitating defecation disorders.
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Affiliation(s)
- Kathleen D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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Cobine CA, McKechnie M, Brookfield RJ, Hannigan KI, Keef KD. Comparison of inhibitory neuromuscular transmission in the Cynomolgus monkey IAS and rectum: special emphasis on differences in purinergic transmission. J Physiol 2018; 596:5319-5341. [PMID: 30198065 DOI: 10.1113/jp275437] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 09/07/2018] [Indexed: 01/04/2023] Open
Abstract
KEY POINTS Inhibitory neuromuscular transmission (NMT) was compared in the internal anal sphincter (IAS) and rectum of the Cynomolgus monkey, an animal with high gene sequence identity to humans. Nitrergic NMT was present in both muscles while purinergic NMT was limited to the rectum and VIPergic NMT to the IAS. The profile for monkey IAS more closely resembles humans than rodents. In both muscles, SK3 channels were localized to PDGFRα+ cells that were closely associated with nNOS+ /VIP+ nerves. Gene expression levels of P2RY subtypes were the same in IAS and rectum while KCNN expression levels were very similar. SK3 channel activation and inhibition caused faster/greater changes in contractile activity in rectum than IAS. P2Y1 receptor activation inhibited contraction in rectum while increasing contraction in IAS. The absence of purinergic NMT in the IAS may be due to poor coupling between P2Y1 receptors and SK3 channels on PDGFRα+ cells. ABSTRACT Inhibitory neuromuscular transmission (NMT) was compared in the internal anal sphincter (IAS) and rectum of the Cynomolgus monkey, an animal with a high gene sequence identity to humans. Electrical field stimulation produced nitric oxide synthase (NOS)-dependent contractile inhibition in both muscles whereas P2Y1-dependent purinergic NMT was restricted to rectum. An additional NOS-independent, α-chymotrypsin-sensitive component was identified in the IAS consistent with vasoactive intestinal peptide-ergic (VIPergic) NMT. Microelectrode recordings revealed slow NOS-dependent inhibitory junction potentials (IJPs) in both muscles and fast P2Y1-dependent IJPs in rectum. The basis for the difference in purinergic NMT was investigated. PDGFRα+ /SK3+ cells were closely aligned with nNOS+ /VIP+ neurons in both muscles. Gene expression of P2RY was the same in IAS and rectum (P2RY1>>P2RY2-14) while KCNN3 expression was 32% greater in rectum. The SK channel inhibitor apamin doubled contractile activity in rectum while having minimal effect in the IAS. Contractile inhibition elicited with the SK channel agonist CyPPA was five times faster in rectum than in the IAS. The P2Y1 receptor agonist MRS2365 inhibited contraction in rectum but increased contraction in the IAS. In conclusion, both the IAS and the rectum have nitrergic NMT whereas purinergic NMT is limited to rectum and VIPergic NMT to the IAS. The profile in monkey IAS more closely resembles that of humans than rodents. The lack of purinergic NMT in the IAS cannot be attributed to the absence of PDGFRα+ cells, P2Y1 receptors or SK3 channels. Rather, it appears to be due to poor coupling between P2Y1 receptors and SK3 channels on PDGFRα+ cells.
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Affiliation(s)
- C A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - M McKechnie
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - R J Brookfield
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - K I Hannigan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - K D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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Fidalgo S, Patel BA, Ranson RN, Saffrey MJ, Yeoman MS. Changes in murine anorectum signaling across the life course. Neurogastroenterol Motil 2018; 30:e13426. [PMID: 30062757 PMCID: PMC6175477 DOI: 10.1111/nmo.13426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 06/18/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND Increasing age is associated with an increase in the incidence of chronic constipation and fecal impaction. The contribution of the natural aging process to these conditions is not fully understood. This study examined the effects of increasing age on the function of the murine anorectum. METHODS The effects of increasing age on cholinergic, nitrergic, and purinergic signaling pathways in the murine anorectum were examined using classical organ bath assays to examine tissue function and electrochemical sensing to determine age-related changes in nitric oxide and acetylcholine release. KEY RESULTS Nitrergic relaxation increased between 3 and 6 months, peaked at 12 months and declined in the 18 and 24 months groups. These changes were in part explained by an age-related decrease in nitric oxide (NO) release. Cholinergic signaling was maintained with age by an increase in acetylcholine (ACh) release and a compensatory decrease in cholinesterase activity. Age-related changes in purinergic relaxation were qualitatively similar to nitrergic relaxation although the relaxations were much smaller. Increasing age did not alter the response of the anorectum smooth muscle to exogenously applied ACh, ATP, sodium nitroprusside or KCl. Similarly, there was no change in basal tension developed by the anorectum. CONCLUSIONS AND INFERENCES The decrease in nitrergic signaling with increasing age may contribute to the age-related fecal impaction and constipation previously described in this model by partially obstructing defecation.
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Affiliation(s)
- S. Fidalgo
- School of Pharmacy and Biomolecular ScienceCentre for Stress and Age‐Related DiseaseUniversity of BrightonBrightonUK
| | - B. A. Patel
- School of Pharmacy and Biomolecular ScienceCentre for Stress and Age‐Related DiseaseUniversity of BrightonBrightonUK
| | - R. N. Ranson
- Department of Applied SciencesFaculty of Health and Life SciencesNorthumbria UniversityNewcastle upon TyneUK
| | - M. J. Saffrey
- School of Life, Health and Chemical SciencesThe Open UniversityMilton KeynesUK
| | - M. S. Yeoman
- School of Pharmacy and Biomolecular ScienceCentre for Stress and Age‐Related DiseaseUniversity of BrightonBrightonUK
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Cobine CA, Hannah EE, Zhu MH, Lyle HE, Rock JR, Sanders KM, Ward SM, Keef KD. ANO1 in intramuscular interstitial cells of Cajal plays a key role in the generation of slow waves and tone in the internal anal sphincter. J Physiol 2017; 595:2021-2041. [PMID: 28054347 DOI: 10.1113/jp273618] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/16/2016] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS The internal anal sphincter develops tone important for maintaining high anal pressure and continence. Controversy exists regarding the mechanisms underlying tone development. We examined the hypothesis that tone depends upon electrical slow waves (SWs) initiated in intramuscular interstitial cells of Cajal (ICC-IM) by activation of Ca2+ -activated Cl- channels (ANO1, encoded by Ano1) and voltage-dependent L-type Ca2+ channels (CavL , encoded by Cacna1c). Measurement of membrane potential and contraction indicated that ANO1 and CavL have a central role in SW generation, phasic contractions and tone, independent of stretch. ANO1 expression was examined in wildtype and Ano1/+egfp mice with immunohistochemical techniques. Ano1 and Cacna1c expression levels were examined by quantitative PCR in fluorescence-activated cell sorting. ICC-IM were the predominant cell type expressing ANO1 and the most likely candidate for SW generation. SWs in ICC-IM are proposed to conduct to smooth muscle where Ca2+ entry via CavL results in phasic activity that sums to produce tone. ABSTRACT The mechanism underlying tone generation in the internal anal sphincter (IAS) is controversial. We examined the hypothesis that tone depends upon generation of electrical slow waves (SWs) initiated in intramuscular interstitial cells of Cajal (ICC-IM) by activation of Ca2+ -activated Cl- channels (encoded by Ano1) and voltage-dependent L-type Ca2+ channels (encoded by Cacna1c). Phasic contractions and tone in the IAS were nearly abolished by ANO1 and CavL antagonists. ANO1 antagonists also abolished SWs as well as transient depolarizations that persisted after addition of CavL antagonists. Tone development in the IAS did not require stretch of muscles, and the sensitivity of contraction to ANO1 antagonists was the same in stretched versus un-stretched muscles. ANO1 expression was examined in wildtype and Ano1/+egfp mice with immunohistochemical techniques. Dual labelling revealed that ANO1 expression could be resolved in ICC but not smooth muscle cells (SMCs) in the IAS and rectum. Ano1, Cacna1c and Kit gene expression were the same in extracts of IAS and rectum muscles. In IAS cells isolated with fluorescence-activated cell sorting, Ano1 expression was 26.5-fold greater in ICC than in SMCs while Cacna1c expression was only 2-fold greater in SMCs than in ICC. These data support a central role for ANO1 and CavL in the generation of SWs and tone in the IAS. ICC-IM are the probable cellular candidate for ANO1 currents and SW generation. We propose that ANO1 and CavL collaborate to generate SWs in ICC-IM followed by conduction to adjacent SMCs where phasic calcium entry through CavL sums to produce tone.
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Affiliation(s)
- C A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - E E Hannah
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - M H Zhu
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - H E Lyle
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - J R Rock
- Department of Anatomy, UCSF School of Medicine, San Francisco, CA, 94143, USA
| | - K M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - S M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - K D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
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Mañé N, Jiménez-Sábado V, Jiménez M. BPTU, an allosteric antagonist of P2Y1 receptor, blocks nerve mediated inhibitory neuromuscular responses in the gastrointestinal tract of rodents. Neuropharmacology 2016; 110:376-385. [PMID: 27496690 DOI: 10.1016/j.neuropharm.2016.07.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 06/28/2016] [Accepted: 07/26/2016] [Indexed: 12/28/2022]
Abstract
P2Y1 receptors mediate nerve mediated purinergic inhibitory junction potentials (IJP) and relaxations in the gastrointestinal (GI) tract in a wide range of species including rodents and humans. A new P2Y1 antagonist, with a non-nucleotide structure, BPTU, has recently been described using X-ray crystallography as the first allosteric G-protein-coupled receptor antagonist located entirely outside of the helical bundle. In this study, we tested its effect on purinergic responses in the gastrointestinal tract of rodents using electrophysiological and myographic techniques. BPTU concentration dependently inhibited purinergic inhibitory junction potentials and inhibition of spontaneous motility induced by electrical field stimulation in the colon of rats (EC50 = 0.3 μM) and mice (EC50 = 0.06 μM). Mechanical inhibitory responses were also concentration-dependently blocked in the stomach of both species. Compared to MRS2500, BPTU displays a lower potency. In the rat colon nicotine induced relaxation was also blocked by BPTU. BPTU also blocked the cessation of spontaneous contractility elicited by ADPβS and the P2Y1 agonist MRS2365. We conclude that BPTU is a novel antagonist with different structural and functional properties than nucleotidic antagonists that is able to block the P2Y1 receptor located at the neuromuscular junction of the GI tract.
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Affiliation(s)
- Noemí Mañé
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.
| | - Verónica Jiménez-Sábado
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Barcelona, Spain.
| | - Marcel Jiménez
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain.
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Zhang CH, Wang P, Liu DH, Chen CP, Zhao W, Chen X, Chen C, He WQ, Qiao YN, Tao T, Sun J, Peng YJ, Lu P, Zheng K, Craige SM, Lifshitz LM, Keaney JF, Fogarty KE, ZhuGe R, Zhu MS. The molecular basis of the genesis of basal tone in internal anal sphincter. Nat Commun 2016; 7:11358. [PMID: 27101932 PMCID: PMC4844698 DOI: 10.1038/ncomms11358] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 03/16/2016] [Indexed: 02/06/2023] Open
Abstract
Smooth muscle sphincters exhibit basal tone and control passage of contents through organs such as the gastrointestinal tract; loss of this tone leads to disorders such as faecal incontinence. However, the molecular mechanisms underlying this tone remain unknown. Here, we show that deletion of myosin light-chain kinases (MLCK) in the smooth muscle cells from internal anal sphincter (IAS-SMCs) abolishes basal tone, impairing defecation. Pharmacological regulation of ryanodine receptors (RyRs), L-type voltage-dependent Ca2+ channels (VDCCs) or TMEM16A Ca2+-activated Cl− channels significantly changes global cytosolic Ca2+ concentration ([Ca2+]i) and the tone. TMEM16A deletion in IAS-SMCs abolishes the effects of modulators for TMEM16A or VDCCs on a RyR-mediated rise in global [Ca2+]i and impairs the tone and defecation. Hence, MLCK activation in IAS-SMCs caused by a global rise in [Ca2+]i via a RyR-TMEM16A-VDCC signalling module sets the basal tone. Targeting this module may lead to new treatments for diseases like faecal incontinence. The molecular basis of the basal tone generated by internal anal sphincters (IAS) is largely unknown. Here, the authors show that the tone arises from a global rise in intracellular Ca2+ in smooth muscle cells via a Ryanodine receptor-TMEM16A-L-type Ca2+ channel-MLC kinase pathway, suggesting a potential therapy for IAS motility disorders.
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Affiliation(s)
- Cheng-Hai Zhang
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China.,Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Pei Wang
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Dong-Hai Liu
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Cai-Ping Chen
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Wei Zhao
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Xin Chen
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Chen Chen
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Wei-Qi He
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China.,CAM-SU Genomic Resource Center, Soochow University, Suzhou 215123, China
| | - Yan-Ning Qiao
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Tao Tao
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Jie Sun
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Ya-Jing Peng
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Ping Lu
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Kaizhi Zheng
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Siobhan M Craige
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Lawrence M Lifshitz
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - John F Keaney
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Kevin E Fogarty
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Ronghua ZhuGe
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Min-Sheng Zhu
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China.,Innovation Center for Cardiovascular Disorders, Beijing 100029, China
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11
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Abstract
The role of adenosine 5'-triphosphate (ATP) as a major intracellular energy source is well-established. In addition, ATP and related nucleotides have widespread extracellular actions via the ionotropic P2X (ligand-gated cation channels) and metabotropic P2Y (G protein-coupled) receptors. Numerous experimental techniques, including myography, electrophysiology and biochemical measurement of neurotransmitter release, have been used to show that ATP has several major roles as a neurotransmitter in peripheral nerves. When released from enteric nerves of the gastrointestinal tract it acts as an inhibitory neurotransmitter, mediating descending muscle relaxation during peristalsis. ATP is also an excitatory cotransmitter in autonomic nerves; 1) It is costored with noradrenaline in synaptic vesicles in postganglionic sympathetic nerves innervating smooth muscle preparations, such as the vas deferens and most arteries. When coreleased with noradrenaline, ATP acts at postjunctional P2X1 receptors to evoke depolarisation, Ca(2+) influx, Ca(2+) sensitisation and contraction. 2) ATP is also coreleased with acetylcholine from postganglionic parasympathetic nerves innervating the urinary bladder and again acts at postjunctional P2X1 receptors, and possibly also a P2X1+4 heteromer, to elicit smooth muscle contraction. In both cases the neurotransmitter actions of ATP are terminated by dephosphorylation by extracellular, membrane-bound enzymes and soluble nucleotidases released from postganglionic nerves. There are indications of an increased contribution of ATP to control of blood pressure in hypertension, but further research is needed to clarify this possibility. More promising is the upregulation of P2X receptors in dysfunctional bladder, including interstitial cystitis, idiopathic detrusor instability and overactive bladder syndrome. Consequently, these roles of ATP are of great therapeutic interest and are increasingly being targeted by pharmaceutical companies.
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Affiliation(s)
- Charles Kennedy
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, United Kingdom.
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12
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Ranson RN, Saffrey MJ. Neurogenic mechanisms in bladder and bowel ageing. Biogerontology 2015; 16:265-84. [PMID: 25666896 PMCID: PMC4361768 DOI: 10.1007/s10522-015-9554-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 01/28/2015] [Indexed: 01/18/2023]
Abstract
The prevalence of both urinary and faecal incontinence, and also chronic constipation, increases with ageing and these conditions have a major impact on the quality of life of the elderly. Management of bladder and bowel dysfunction in the elderly is currently far from ideal and also carries a significant financial burden. Understanding how these changes occur is thus a major priority in biogerontology. The functions of the bladder and terminal bowel are regulated by complex neuronal networks. In particular neurons of the spinal cord and peripheral ganglia play a key role in regulating micturition and defaecation reflexes as well as promoting continence. In this review we discuss the evidence for ageing-induced neuronal dysfunction that might predispose to neurogenic forms of incontinence in the elderly.
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Affiliation(s)
- Richard N Ranson
- Department of Applied Sciences (Biomedical Sciences), Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK,
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13
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Mutafova-Yambolieva VN, Durnin L. The purinergic neurotransmitter revisited: a single substance or multiple players? Pharmacol Ther 2014; 144:162-91. [PMID: 24887688 PMCID: PMC4185222 DOI: 10.1016/j.pharmthera.2014.05.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 05/23/2014] [Indexed: 12/20/2022]
Abstract
The past half century has witnessed tremendous advances in our understanding of extracellular purinergic signaling pathways. Purinergic neurotransmission, in particular, has emerged as a key contributor in the efficient control mechanisms in the nervous system. The identity of the purine neurotransmitter, however, remains controversial. Identifying it is difficult because purines are present in all cell types, have a large variety of cell sources, and are released via numerous pathways. Moreover, studies on purinergic neurotransmission have relied heavily on indirect measurements of integrated postjunctional responses that do not provide direct information for neurotransmitter identity. This paper discusses experimental support for adenosine 5'-triphosphate (ATP) as a neurotransmitter and recent evidence for possible contribution of other purines, in addition to or instead of ATP, in chemical neurotransmission in the peripheral, enteric and central nervous systems. Sites of release and action of purines in model systems such as vas deferens, blood vessels, urinary bladder and chromaffin cells are discussed. This is preceded by a brief discussion of studies demonstrating storage of purines in synaptic vesicles. We examine recent evidence for cell type targets (e.g., smooth muscle cells, interstitial cells, neurons and glia) for purine neurotransmitters in different systems. This is followed by brief discussion of mechanisms of terminating the action of purine neurotransmitters, including extracellular nucleotide hydrolysis and possible salvage and reuptake in the cell. The significance of direct neurotransmitter release measurements is highlighted. Possibilities for involvement of multiple purines (e.g., ATP, ADP, NAD(+), ADP-ribose, adenosine, and diadenosine polyphosphates) in neurotransmission are considered throughout.
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Affiliation(s)
| | - Leonie Durnin
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, United States
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14
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Smith TK, Park KJ, Hennig GW. Colonic migrating motor complexes, high amplitude propagating contractions, neural reflexes and the importance of neuronal and mucosal serotonin. J Neurogastroenterol Motil 2014; 20:423-46. [PMID: 25273115 PMCID: PMC4204412 DOI: 10.5056/jnm14092] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/05/2014] [Accepted: 09/08/2014] [Indexed: 12/15/2022] Open
Abstract
The colonic migrating motor complex (CMMC) is a critical neurally mediated rhythmic propulsive contraction observed in the large intestine of many mammals. It seems to be equivalent to the high amplitude propagating contractions (HAPCs) in humans. This review focuses on the probable neural mechanisms involved in producing the CMMC or HAPC, their likely dependence on mucosal and neuronal serotonin and pacemaker insterstitial cells of Cajal networks and how intrinsic neural reflexes affect them. Discussed is the possibility that myenteric 5-hydroxytryptamine (5-HT) neurons are not only involved in tonic inhibition of the colon, but are also involved in generating the CMMC and modulation of the entire enteric nervous system, including coupling motility to secretion and blood flow. Mucosal 5-HT appears to be important for the initiation and effective propagation of CMMCs, although this mechanism is a longstanding controversy since the 1950s, which we will address. We argue that the slow apparent propagation of the CMMC/HAPC down the colon is unlikely to result from a slowly conducting wave front of neural activity, but more likely because of an interaction between ascending excitatory and descending (serotonergic) inhibitory neural pathways interacting both within the myenteric plexus and at the level of the muscle. That is, CMMC/HAPC propagation appears to be similar to esophageal peristalsis. The suppression of inhibitory (neuronal nitric oxide synthase) motor neurons and mucosal 5-HT release by an upregulation of prostaglandins has important implications in a number of gastrointestinal disorders, especially slow transit constipation.
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Affiliation(s)
- Terence K Smith
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Kyu Joo Park
- Department of Surgery, School of Medicine, Seoul National University, Seoul Korea
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, USA
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15
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Jiménez M, Clavé P, Accarino A, Gallego D. Purinergic neuromuscular transmission in the gastrointestinal tract; functional basis for future clinical and pharmacological studies. Br J Pharmacol 2014; 171:4360-75. [PMID: 24910216 DOI: 10.1111/bph.12802] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/14/2014] [Accepted: 05/24/2014] [Indexed: 12/13/2022] Open
Abstract
Nerve-mediated relaxation is necessary for the correct accomplishment of gastrointestinal (GI) motility. In the GI tract, NO and a purine are probably released by the same inhibitory motor neuron as inhibitory co-transmitters. The P2Y1 receptor has been recently identified as the receptor responsible for purinergic smooth muscle hyperpolarization and relaxation in the human gut. This finding has been confirmed in P2Y1 -deficient mice where purinergic neurotransmission is absent and transit time impaired. However, the mechanisms responsible for nerve-mediated relaxation, including the identification of the purinergic neurotransmitter(s) itself, are still debatable. Possibly different mechanisms of nerve-mediated relaxation are present in the GI tract. Functional demonstration of purinergic neuromuscular transmission has not been correlated with structural studies. Labelling of purinergic neurons is still experimental and is not performed in routine pathology studies from human samples, even when possible neuromuscular impairment is suspected. Accordingly, the contribution of purinergic neurotransmission in neuromuscular diseases affecting GI motility is not known. In this review, we have focused on the physiological mechanisms responsible for nerve-mediated purinergic relaxation providing the functional basis for possible future clinical and pharmacological studies on GI motility targeting purine receptors.
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Affiliation(s)
- Marcel Jiménez
- Department of Cell Biology, Physiology and Immunology, Neurosciences Institute, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
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16
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Martínez-Cutillas M, Gil V, Gallego D, Mañé N, Clavé P, Martín MT, Jiménez M. α,β-meATP mimics the effects of the purinergic neurotransmitter in the human and rat colon. Eur J Pharmacol 2014; 740:442-54. [PMID: 24998877 DOI: 10.1016/j.ejphar.2014.06.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 06/13/2014] [Accepted: 06/17/2014] [Indexed: 02/05/2023]
Abstract
The purine receptor involved in inhibitory responses in the gastrointestinal tract has been recently identified. P2Y1 receptor activation mediates the fast component of the inhibitory junction potential (IJPf) and the non-nitrergic relaxation. The aim of the present work has been to investigate which purinergic agonist better mimics endogenous responses. We used different agonist and antagonist of P2 receptors. Contractility and microelectrode experiments were used to compare the effects of exogenously added purines and electrical field stimulation (EFS)-induced nerve mediated effects in rat and human colonic strips. In rat colon, the IJPf and EFS-induced inhibition of contractions were concentration-dependently inhibited by the P2Y1 antagonist MRS2500 but not by iso-PPADS or NF023 (P2X antagonists) up to 1 μM. In samples from human colon, EFS-induced inhibition of contractions was inhibited by either MRS2500 or apamin (1 μM) but not by iso-PPADS. In both species, α,β-meATP, a stable analog of ATP, caused inhibition of spontaneous contractions. α,β-meATP effect was concentration-dependent (EC50: 2.7 μM rat, 4.4 μM human) and was antagonized by either MRS2500 or apamin but unaffected by P2X antagonists. ATP, ADP, β-NAD and ADP-ribose inhibited spontaneous contractions but did not show the same sensitivity profile to purine receptor antagonists as EFS-induced inhibition of contractions. The effect of α,β-meATP is due to P2Y1 receptor activation leading the opening of sKca channels. Accordingly, α,β-meATP mimics the endogenous purinergic mediator. In contrast, exogenously added putative neurotransmitters do not exactly mimic the endogenous mediator. Quick degradation by ecto-nuclease or different distribution of receptors (junctionally vs extrajunctionally) might explain these results.
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Affiliation(s)
- Míriam Martínez-Cutillas
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Víctor Gil
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Diana Gallego
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
| | - Noemí Mañé
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Pere Clavé
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain; Fundació de Gastroenterologia Dr Vilardell and Department of Surgery, Hospital de Mataró, Mataró, Barcelona, Spain
| | - María Teresa Martín
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
| | - Marcel Jiménez
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain.
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17
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Hall KA, Ward SM, Cobine CA, Keef KD. Spatial organization and coordination of slow waves in the mouse anorectum. J Physiol 2014; 592:3813-29. [PMID: 24951622 DOI: 10.1113/jphysiol.2014.272542] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The internal anal sphincter (IAS) develops tone and is important for maintaining a high anal pressure while tone in the rectum is less. The mechanisms responsible for tone generation in the IAS are still uncertain. The present study addressed this question by comparing the electrical properties and morphology of the mouse IAS and distal rectum. The amplitude of tone and the frequency of phasic contractions was greater in the IAS than in rectum while membrane potential (Em) was less negative in the IAS than in rectum. Slow waves (SWs) were of greatest amplitude and frequency at the distal end of the IAS, declining in the oral direction. Dual microelectrode recordings revealed that SWs were coordinated over a much greater distance in the circumferential direction than in the oral direction. The circular muscle layer of the IAS was divided into five to eight 'minibundles' separated by connective tissue septa whereas few septa were present in the rectum. The limited coordination of SWs in the oral direction suggests that the activity in adjacent minibundles is not coordinated. Intramuscular interstitial cells of Cajal and platelet-derived growth factor receptor alpha-positive cells were present in each minibundle suggesting a role for one or both of these cells in SW generation. In summary, three important properties distinguish the IAS from the distal rectum: (1) a more depolarized Em; (2) larger and higher frequency SWs; and (3) the multiunit configuration of the muscle. All of these characteristics may contribute to greater tone generation in the IAS than in the distal rectum.
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Affiliation(s)
- K A Hall
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - S M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - C A Cobine
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - K D Keef
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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18
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Burnstock G. Purinergic signalling in the gastrointestinal tract and related organs in health and disease. Purinergic Signal 2014; 10:3-50. [PMID: 24307520 PMCID: PMC3944042 DOI: 10.1007/s11302-013-9397-9] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/24/2013] [Indexed: 01/04/2023] Open
Abstract
Purinergic signalling plays major roles in the physiology and pathophysiology of digestive organs. Adenosine 5'-triphosphate (ATP), together with nitric oxide and vasoactive intestinal peptide, is a cotransmitter in non-adrenergic, non-cholinergic inhibitory neuromuscular transmission. P2X and P2Y receptors are widely expressed in myenteric and submucous enteric plexuses and participate in sympathetic transmission and neuromodulation involved in enteric reflex activities, as well as influencing gastric and intestinal epithelial secretion and vascular activities. Involvement of purinergic signalling has been identified in a variety of diseases, including inflammatory bowel disease, ischaemia, diabetes and cancer. Purinergic mechanosensory transduction forms the basis of enteric nociception, where ATP released from mucosal epithelial cells by distension activates nociceptive subepithelial primary afferent sensory fibres expressing P2X3 receptors to send messages to the pain centres in the central nervous system via interneurons in the spinal cord. Purinergic signalling is also involved in salivary gland and bile duct secretion.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK,
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19
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Proteinase-activated receptor-1 (PAR1) and PAR2 mediate relaxation of guinea pig internal anal sphincter. ACTA ACUST UNITED AC 2014; 189:46-50. [PMID: 24631471 DOI: 10.1016/j.regpep.2014.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 03/03/2014] [Accepted: 03/04/2014] [Indexed: 01/22/2023]
Abstract
Activation of proteinase-activated receptor-1 (PAR1) and PAR2 stimulates contraction of the rat but relaxation of the guinea pig colon. The aim of the present study was to investigate PAR effects on internal anal sphincter (IAS) motility. We measured relaxation of isolated muscle strips from the guinea pig IAS caused by PAR agonists using isometric transducers. Reverse transcription polymerase chain reaction (RT-PCR) was performed to determine the existence of PAR. In the IAS, thrombin and PAR1 peptide agonists TFLLR-NH2 and SFLLRN-NH2 evoked moderate to marked relaxation in a concentration-dependent manner. In addition, trypsin and PAR2 peptide agonists 2-furoyl-LIGRLO-NH2, SLIGRL-NH2 and SLIGKV-NH2 produced relaxation. In contrast, both PAR1 and PAR2 inactive control peptides did not elicit relaxation. Furthermore, the selective PAR1 antagonist vorapaxar and PAR2 antagonist GB 83 specifically inhibited thrombin and trypsin-induced relaxations, respectively. RT-PCR revealed the presence of PAR1 and PAR2 in the IAS. This indicates that PAR1 and PAR2 mediate the IAS relaxation. The relaxant responses of TFLLR-NH2 and trypsin were attenuated by N(omega)-Nitro-L-arginine (L-NNA), indicating involvement of NO. These responses were not affected by tetrodotoxin, implying that the PAR effects are not neurally mediated. On the other hand, PAR4 agonists GYPGKF-NH2, GYPGQV-NH2 and AYPGKF-NH2 did not cause relaxation or contraction, suggesting that PAR4 is not involved in the sphincter motility. Taken together, these results demonstrate that both PAR1 and PAR2 mediate relaxation of the guinea pig IAS through the NO pathway. PAR1 and PAR2 may regulate IAS tone and might be potential therapeutic targets for anal motility disorders.
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20
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Wang C, Houghton MJ, Gamage PPKM, Collins HE, Patel BA, Yeoman MS, Ranson RN, Saffrey MJ. Changes in the innervation of the mouse internal anal sphincter during aging. Neurogastroenterol Motil 2013; 25:e469-77. [PMID: 23634828 DOI: 10.1111/nmo.12144] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 03/28/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND The innervation of the mouse internal anal sphincter (IAS) has been little studied, and how it changes during aging has not previously been investigated. The aim of this study was therefore to characterize the distribution and density of subtypes of nerve fibers in the IAS and underlying mucosa in 3-, 12- to 13-, 18- and 24- to 25-month-old male C57BL/6 mice. METHODS Nerve fibers were immunolabeled with antibodies against protein gene product 9.5 (PGP9.5), neuronal nitric oxide synthase (nNOS), vasoactive intestinal polypeptide (VIP), substance P (SP), calcitonin gene-related peptide (CGRP), and calretinin (CR). Immunoreactivity in nerve fibers in the circular muscle and mucosa was quantified using Image J software. KEY RESULTS In young adult (3 month) mice, nNOS-immunoreactive (IR) nerve fibers were densely distributed in the circular muscle, but relatively few in the mucosa; VIP-IR nerve fibers were abundant in the circular muscle and common in the mucosa; SP-IR nerve fibers were common in circular muscle and mucosa; CGRP- and CR-IR nerve fibers were dense in mucosa and sparse in circular muscle. The density of PGP9.5 immunoreactivity (IRY) was not significantly reduced with age, but a significant reduction in nNOS-IRY and SP-IRY with age was found in the IAS circular muscle. Neuronal nitric oxide synthase-, VIP-, and SP-IRY in the anal mucosa were significantly reduced with age. CGRP-IRY in both circular muscle and mucosa was increased in 18-month-old animals. CONCLUSIONS & INFERENCES The density of immunoreactivity of markers for some types of IAS nerve fibers decreases during aging, which may contribute to age-related ano-rectal dysfunction.
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Affiliation(s)
- C Wang
- Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes, UK
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21
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Gil V, Martínez-Cutillas M, Mañé N, Martín MT, Jiménez M, Gallego D. P2Y(1) knockout mice lack purinergic neuromuscular transmission in the antrum and cecum. Neurogastroenterol Motil 2013; 25:e170-82. [PMID: 23323764 DOI: 10.1111/nmo.12060] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Pharmacological studies using selective P2Y(1) antagonists, such as MRS2500, and studies with P2Y(1)(-/-) knockout mice have demonstrated that purinergic neuromuscular transmission is mediated by P2Y(1) receptors in the colon. The aim of the present study was to test whether P2Y(1) receptors are involved in purinergic neurotransmission in the antrum and cecum. METHODS Microelectrode recordings were performed on strips from the antrum and cecum of wild type animals (WT) and P2Y(1)(-/-) mice. KEY RESULTS In the antrum, no differences in resting membrane potential and slow wave activity were observed between groups. In WT animals, electrical field stimulation elicited a MRS2500-sensitive inhibitory junction potential (IJP). In P2Y(1)(-/-) mice, a nitrergic IJP (N(ω) -nitro-l-arginine-sensitive), but not a purinergic IJP was recorded. This IJP was equivalent to the response obtained in strips from WT animals previously incubated with MRS2500. Similar results were obtained in the cecum: 1- the purinergic IJP (MRS2500-sensitive) recorded in WT animals was absent in P2Y(1)(-/-) mice 2- nitrergic neurotransmission was preserved in both groups. Moreover, 1- spontaneous IJP (MRS2500-sensitive) could be recorded in WT, but not in P2Y(1)(-/-) mice 2- MRS2365 a P2Y(1) agonist caused smooth muscle hyperpolarization in WT, but not in P2Y(1) (-/-) animals, and 3- β-NAD caused smooth muscle hyperpolarization both in WT and P2Y(1)(-/-) animals. CONCLUSIONS & INFERENCES 1- P2Y(1) receptor is the general mechanism of purinergic inhibition in the gastrointestinal tract, 2- P2Y(1)(-/-) mouse is a useful animal model to study selective impairment of purinergic neurotransmission and 3- P2Y(1)(-/-) mouse might help in the identification of purinergic neurotransmitter(s).
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Affiliation(s)
- V Gil
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Bellaterra, Spain
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22
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Gallego D, Gil V, Martínez-Cutillas M, Mañé N, Martín MT, Jiménez M. Purinergic neuromuscular transmission is absent in the colon of P2Y(1) knocked out mice. J Physiol 2012; 590:1943-56. [PMID: 22371472 DOI: 10.1113/jphysiol.2011.224345] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Purinergic and nitrergic co-transmission is the dominant mechanism responsible for neural-mediated smooth muscle relaxation in the gastrointestinal tract. The aim of the present paper was to test whether or not P2Y(1) receptors are involved in purinergic neurotransmission using P2Y(1)(−/−) knock-out mice. Tension and microelectrode recordings were performed on colonic strips. In wild type (WT) animals, electrical field stimulation (EFS) caused an inhibitory junction potential (IJP) that consisted of a fast IJP (MRS2500 sensitive, 1 μm) followed by a sustained IJP (N(ω)-nitro-L-arginine (L-NNA) sensitive, 1 mm). The fast component of the IJP was absent in P2Y(1)(−/−) mice whereas the sustained IJP (L-NNA sensitive) was recorded. In WT animals, EFS-induced inhibition of spontaneous motility was blocked by the consecutive addition of L-NNA and MRS2500. In P2Y(1)(−/−) mice, EFS responses were completely blocked by L-NNA. In WT and P2Y(1)(−/−) animals, L-NNA induced a smooth muscle depolarization but ‘spontaneous' IJP (MRS2500 sensitive) could be recorded in WT but not in P2Y(1)(−/−) animals. Finally, in WT animals, 1 μm MRS2365 caused a smooth muscle hyperpolarization that was blocked by 1 μm MRS2500. In contrast, 1 μm MRS2365 did not modify smooth muscle resting membrane potential in P2Y(1)(−/−) mice. β-Nicotinamide adenine dinucleotide (β-NAD, 1 mm) partially mimicked the effect of MRS2365. We conclude that P2Y(1) receptors mediate purinergic neurotransmission in the gastrointestinal tract and β-NAD partially fulfils the criteria to participate in rodent purinergic neurotransmission. The P2Y(1)(−/−) mouse is a useful animal model to study the selective loss of purinergic neurotransmission.
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Affiliation(s)
- Diana Gallego
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd) Instituto de Salud Carlos III, Barcelona, Spain
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Duffy AM, Cobine CA, Keef KD. Changes in neuromuscular transmission in the W/W(v) mouse internal anal sphincter. Neurogastroenterol Motil 2012; 24:e41-55. [PMID: 22074497 PMCID: PMC3245326 DOI: 10.1111/j.1365-2982.2011.01806.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Intramuscular interstitial cells of Cajal (ICC-IM) have been shown to participate in nitrergic neuromuscular transmission (NMT) in various regions of the gastrointestinal (GI) tract, but their role in the internal anal sphincter (IAS) is still uncertain. Contractile studies of the IAS in the W/W(v) mouse (a model in which ICC-IM numbers are markedly reduced) have reported that nitrergic NMT persists and that ICC-IM are not required. However, neither the changes in electrical events underlying NMT nor the contributions of other non-nitrergic neural pathways have been examined in this model. METHODS The role of ICC-IM in NMT was examined by recording the contractile and electrical events associated with electrical field stimulation (EFS) of motor neurons in the IAS of wildtype and W/W(v) mice. Nitrergic, purinergic, and cholinergic components were identified using inhibitors of these pathways. KEY RESULTS Under NANC conditions, purinergic and nitrergic pathways both contribute to EFS-induced inhibitory junction potentials (IJPs) and relaxation. Purinergic IJPs and relaxation were intact in the W/W(v) mouse IAS, whereas nitrergic IJPs were reduced by 50-60% while relaxation persisted. In the presence of L-NNA (NOS inhibitor) and MRS2500 (P2Y1 receptor antagonist), EFS gave rise to cholinergic depolarization and contractions that were abolished by atropine. Cholinergic depolarization was absent in the W/W(v) mouse IAS while contraction persisted. CONCLUSIONS & INFERENCES ICC-IM significantly contributes to the electrical events underlying nitrergic and cholinergic NMT, whereas contractile events persist in the absence of ICC-IM. The purinergic inhibitory neural pathway appears to be independent of ICC-IM.
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Affiliation(s)
| | | | - KD Keef
- Individual to whom correspondences should be addressed: Kathleen Keef, Ph.D., Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, , 1-775-784-4302
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Gallego D, Gil V, Aleu J, Martinez-Cutillas M, Clavé P, Jimenez M. Pharmacological characterization of purinergic inhibitory neuromuscular transmission in the human colon. Neurogastroenterol Motil 2011; 23:792-e338. [PMID: 21585621 DOI: 10.1111/j.1365-2982.2011.01725.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND In the present study, we further characterize the purinergic receptors mediating the inhibitory junction potential (IJP) and smooth muscle relaxation in the human colon using a new, potent and selective agonist (MRS2365), and antagonists (MR2279 and MRS2500) of the P2Y(1) receptor. The P2Y(12) antagonist AR-C66096 was tested as well. Using this pharmacological approach, we tested whether β-nicotinamide adenine dinucleotide (β-NAD) fulfilled the criteria to be considered an inhibitory neurotransmitter in the human colon. METHODS We carried out muscle bath and microelectrode experiments on circular strips from the human colon and calcium imaging recordings on HEK293 cells, which constitutively express the human P2Y(1) receptor. KEY RESULTS Both the fast component of IJP and non-nitrergic relaxation was concentration-dependently inhibited by MRS2279 and MRS2500. This antagonism was confirmed in HEK293 cells. However, AR-C66096 did not modify either inhibitory response. Adenosine 5'-Ο-2-thiodiphosphate and MRS2365 caused a smooth muscle hyperpolarization and transient inhibition of spontaneous motility that was antagonized by MRS2279 and MRS2500. β-Nicotinamide adenine dinucleotide inhibited the spontaneous motility (IC(50) = 3.3 mmol L(-1) ). Nevertheless, this effect was not antagonized by high concentrations of P2Y(1) antagonists. CONCLUSIONS & INFERENCES Inhibitory purinergic neuromuscular transmission in the human colon was pharmacologically assessed by the use of new P2Y(1) receptor antagonists MRS2179, MRS2279, and MRS2500. The rank order of potency of the P2Y(1) antagonists is MRS2500 > MRS2279 > MRS2179. We found that β-NAD partially fulfills the criteria to be considered an inhibitory neurotransmitter in the human colon, but the relative contribution of each purine (ATP/ADP vsβ-NAD) requires further studies.
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Affiliation(s)
- D Gallego
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
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Relationship between interstitial cells of Cajal, fibroblast-like cells and inhibitory motor nerves in the internal anal sphincter. Cell Tissue Res 2011; 344:17-30. [PMID: 21337122 DOI: 10.1007/s00441-011-1138-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 01/19/2011] [Indexed: 12/15/2022]
Abstract
Interstitial cells of Cajal (ICC) have been shown to participate in nitrergic neurotransmission in various regions of the gastrointestinal (GI) tract. Recently, fibroblast-like cells, which are positive for platelet-derived growth factor receptor α (PDGFRα(+)), have been suggested to participate additionally in inhibitory neurotransmission in the GI tract. The distribution of ICC and PDGFRα(+) cell populations and their relationship to inhibitory nerves within the mouse internal anal sphincter (IAS) are unknown. Immunohistochemical techniques and confocal microscopy were therefore used to examine the density and arrangement of ICC, PDGFRα(+) cells and neuronal nitric-oxide-synthase-positive (nNOS(+)) nerve fibers in the IAS of wild-type (WT) and W/W ( v ) mice. Of the total tissue volume within the IAS circular muscle layer, 18% consisted in highly branched PDGFRα(+) cells (PDGFRα(+)-IM). Other populations of PDGFRα(+) cells were observed within the submucosa and along the serosal and myenteric surfaces. Spindle-shaped intramuscular ICC (ICC-IM) were present in the WT mouse IAS but were largely absent from the W/W ( v ) IAS. The ICC-IM volume (5% of tissue volume) in the WT mouse IAS was significantly smaller than that of PDGFRα(+)-IM. Stellate-shaped submucosal ICC (ICC-SM) were observed in the WT and W/W ( v ) IAS. Minimum surface distance analysis revealed that nNOS(+) nerve fibers were closely aligned with both ICC-IM and PDGFRα(+)-IM. An even closer association was seen between ICC-IM and PDGFRα(+)-IM. Thus, a close morphological arrangement exists between inhibitory motor neurons, ICC-IM and PDGFRα(+)-IM suggesting that some functional interaction occurs between them contributing to inhibitory neurotransmission in the IAS.
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Rattan S, Singh J. Basal internal anal sphincter tone, inhibitory neurotransmission, and other factors contributing to the maintenance of high pressures in the anal canal. Neurogastroenterol Motil 2011; 23:3-7. [PMID: 21188800 PMCID: PMC5547999 DOI: 10.1111/j.1365-2982.2010.01629.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Maintenance of the basal tone in the internal anal sphincter (IAS) is critical for rectoanal continence. Effective evacuation requires a fully functional rectoanal inhibitory reflex (RAIR)-mediated relaxation of the IAS via inhibitory neurotransmission (INT). Systematic studies examining the nature of the INT in different species have identified nitric oxide (NO) as the major inhibitory neurotransmitter. However, other mediators such as vasoactive intestinal polypeptide (VIP), ATP, and carbon monoxide (CO) may also play species-specific role under certain experimental conditions. Measurements of the intraluminal pressures in the IAS along with the force of the isolated IAS tissues are the mainstay in the basic studies for the molecular mechanisms underlying the basal tone and in the nature of the INT. The identification of NO as the inhibitory neurotransmitter has led to major advances in the diagnosis and treatment of a number of rectoanal motility disorders associated with the IAS dysfunction. Besides the IAS, the high pressures in the anal canal are affected by the external anal sphincter (EAS) function, and its malfunction may also lead to rectoanal incontinence. Different approaches including biofeedback have been attempted to improve the EAS function, with variable outcomes. There is a dire need for the innovative ways to improve the week high pressures zone in the anal canal. This viewpoint focuses on two studies that extend the above concept of multiplicity of inhibitory neurotransmitters (Neurogastroenterol Motil 2011 23 e11–25), and that high pressures in the anal canal can be improved by the EAS plication (Neurogastroenterol Motil 2011 23 70–5).
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Affiliation(s)
- S Rattan
- Department of Medicine, Division of Gastroenterology & Hepatology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA, USA.
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Opazo A, Lecea B, Gil V, Jiménez M, Clavé P, Gallego D. Specific and complementary roles for nitric oxide and ATP in the inhibitory motor pathways to rat internal anal sphincter. Neurogastroenterol Motil 2011; 23:e11-25. [PMID: 20939852 DOI: 10.1111/j.1365-2982.2010.01602.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND The neurotransmitters mediating inhibitory pathways to internal anal sphincter (IAS) have not been fully characterized. Our aim was to assess the putative release of nitric oxide, purines and vasoactive intestinal peptide (VIP) from inhibitory motor neurons (MNs) and their role in the myogenic tone, resting membrane potential (RMP) of smooth muscle cells (SMC), spontaneous inhibitory junction potentials (sIJP), mechanical relaxation, and IJP induced by electrical field stimulation (EFS) or nicotine. METHODS Rat IAS strips were studied using organ baths, microelectrodes, and immunohistochemistry. KEY RESULTS Internal anal sphincter strips developed active myogenic tone (0.31 g), enhanced and stabilized by prostaglandin F(2α) (PGF2α). L-NNA (1 mmol L(-1)) depolarized SMC and increased tone but did not modify sIJP. In contrast, the specific P2Y(1) receptor antagonist MRS2500 (1 μmol L(-1)) did not modify the RMP or the basal tone but abolished sIJP. Electrical field stimulation and nicotine (10 μmol L(-1)) caused IAS relaxation (-45.9%VS-52.2%), partially antagonized by L-NNA (35%-45%, P ≤ 0.05) and fully abolished by MRS2500 (P ≤ 0.001). Electrical field stimulation induced a biphasic inhibitory junction potential (IJP), the initial fast component was selectively blocked by MRS2500 and the sustained slow component was blocked by L-NNA. Vasoactive intestinal peptide 6-28 (0.1 μmol L(-1)) or α-chymotrypsin (10 U mL(-1)) did not modify the RMP, sIJP, EFS-induced IJP, or relaxation. P2Y(1) receptors were immunolocalized in the circular SMC of IAS. CONCLUSIONS & INFERENCES The effects of inhibitory MNs on rat IAS are mediated by a functional co-transmission process involving nitrergic and purinergic pathways through P2Y(1) receptors with specific and complementary roles on the control of tone, sIJP, and hyperpolarization and relaxation of IAS following stimulation of inhibitory MNs.
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Affiliation(s)
- A Opazo
- Department of Surgery, Hospital de Mataró, Barcelona, Spain
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Raghavan S, Miyasaka EA, Hashish M, Somara S, Gilmont RR, Teitelbaum DH, Bitar KN. Successful implantation of physiologically functional bioengineered mouse internal anal sphincter. Am J Physiol Gastrointest Liver Physiol 2010; 299:G430-9. [PMID: 20558766 PMCID: PMC2928530 DOI: 10.1152/ajpgi.00269.2009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 06/09/2010] [Indexed: 01/31/2023]
Abstract
We have previously developed bioengineered three-dimensional internal anal sphincter (IAS) rings from circular smooth muscle cells isolated from rabbit and human IAS. We provide proof of concept that bioengineered mouse IAS rings are neovascularized upon implantation into mice of the same strain and maintain concentric smooth muscle alignment, phenotype, and IAS functionality. Rings were bioengineered by using smooth muscle cells from the IAS of C57BL/6J mice. Bioengineered mouse IAS rings were implanted subcutaneously on the dorsum of C57BL/6J mice along with a microosmotic pump delivering fibroblast growth factor-2. The mice remained healthy during the period of implantation, showing no external signs of rejection. Mice were killed 28 days postsurgery and implanted IAS rings were harvested. IAS rings showed muscle attachment, neovascularization, healthy color, and no external signs of infection or inflammation. Assessment of force generation on harvested IAS rings showed the following: 1) spontaneous basal tone was generated in the absence of external stimulation; 2) basal tone was relaxed by vasoactive intestinal peptide, nitric oxide donor, and nifedipine; 3) acetylcholine and phorbol dibutyrate elicited rapid-rising, dose-dependent, sustained contractions repeatedly over 30 min without signs of muscle fatigue; and 4) magnitudes of potassium chloride-induced contractions were 100% of peak maximal agonist-induced contractions. Our preliminary results confirm the proof of concept that bioengineered rings are neovascularized upon implantation. Harvested rings maintain smooth muscle alignment and phenotype. Our physiological studies confirm that implanted rings maintain 1) overall IAS physiology and develop basal tone, 2) integrity of membrane ionic characteristics, and 3) integrity of membrane associated intracellular signaling transduction pathways for contraction and relaxation by responding to cholinergic, nitrergic, and VIP-ergic stimulation. IAS smooth muscle tissue could thus be bioengineered for the purpose of implantation to serve as a potential graft therapy for dysfunctional internal anal sphincter in fecal incontinence.
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Affiliation(s)
- Shreya Raghavan
- Department of Pediatrics-Gastroenterology, University of Michigan Medical School, Ann Arbor, 48109-0658, USA
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Grasa L, Gil V, Gallego D, Martín MT, Jiménez M. P2Y(1) receptors mediate inhibitory neuromuscular transmission in the rat colon. Br J Pharmacol 2010; 158:1641-52. [PMID: 19906120 DOI: 10.1111/j.1476-5381.2009.00454.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE Inhibitory junction potentials (IJP) are responsible for smooth muscle relaxation in the gastrointestinal tract. The aim of this study was to pharmacologically characterize the neurotransmitters [nitric oxide (NO) and adenosine triphosphate (ATP)] and receptors involved at the inhibitory neuromuscular junctions in the rat colon using newly available P2Y(1) antagonists. EXPERIMENTAL APPROACH Organ bath and microelectrode recordings were used to evaluate the effect of drugs on spontaneous mechanical activity and resting membrane potential. IJP and mechanical relaxation were studied using electrical field stimulation (EFS). KEY RESULTS N(omega)-nitro-L-arginine (L-NNA) inhibited the slow component of the IJP and partially inhibited the mechanical relaxation induced by EFS. MRS2179, MRS2500 and MRS2279, all selective P2Y(1) receptor antagonists, inhibited the fast component of the IJP without having a major effect on the relaxation induced by EFS. The combination of both L-NNA and P2Y(1) antagonists inhibited the fast and the slow components of the IJP and completely blocked the mechanical relaxation induced by EFS. Sodium nitroprusside caused smooth muscle hyperpolarization and cessation of spontaneous motility that was prevented by oxadiazolo[4,3-alpha]quinoxalin-1-one. Adenosine 5'-O-2-thiodiphosphate, a preferential P2Y agonist, hyperpolarized smooth muscle cells and decreased spontaneous motility. This effect was inhibited by P2Y(1) antagonists. CONCLUSIONS AND IMPLICATIONS The co-transmission process in the rat colon involves ATP and NO. P2Y(1) receptors mediate the fast IJP and NO the slow IJP. The rank order of potency of the P2Y(1) receptor antagonists is MRS2500 greater than MRS2279 greater than MRS2179. P2Y(1) receptors might be potential pharmacological targets for the regulation of gastrointestinal motility.
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Affiliation(s)
- Laura Grasa
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Spain
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Zhang Y, Lomax AE, Paterson WG. P2Y1 receptors mediate apamin-sensitive and -insensitive inhibitory junction potentials in murine colonic circular smooth muscle. J Pharmacol Exp Ther 2010; 333:602-11. [PMID: 20103587 DOI: 10.1124/jpet.109.160978] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Purinergic inhibitory neuromuscular transmission plays an important role in the control of intestinal motility. In most tissues this neurotransmission is apamin-sensitive, but recent studies in human colonic circular smooth muscle (CSM) suggest the presence of apamin-insensitive purinergic inhibitory junction potentials (IJPs). The current studies used conventional intracellular recordings on colonic CSM strips to characterize the purinergic IJPs in murine colonic CSM. P2Y1 receptor expression was examined by using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. The IJP induced by nerve stimulation (NS) of one and four pulses in neuronal nitric-oxide synthase knockout mice consists of an apamin-sensitive and a dominant apamin-resistant component. These are identical to the IJPs in wild-type and CD1 mice in the presence of N(omega)-nitro-l-arginine methyl ester (200 microM) and were significantly inhibited by alpha,beta-methylene ATP (50 microM), an analog of ATP. IJPs were not affected by the P2X receptor antagonist 2',3'-o-(2,4,6-trinitrophenyl)-ATP (10 microM). Furthermore, apamin-resistant IJPs induced by single-pulse NS were abolished by pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (100 microM), a P2 receptor antagonist; 2'-deoxy-N6-methyl adenosine 3,5-diphosphate (MRS-2179; 10 microM), a selective P2Y1 receptor antagonist; and tetrodotoxin (1 microM). Aboral NS induced apamin-sensitive purinergic IJPs, whereas oral and circumferential NS produced apamin-sensitive and -resistant IJPs, with the latter predominating. RT-PCR and immunohistochemistry confirmed the presence of P2Y1 receptors on smooth muscle and in the myenteric plexus. These data suggest that, depending on stimulus location, activation of P2Y1 receptors produces both apamin-sensitive and apamin-resistant IJPs in murine colonic CSM.
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Affiliation(s)
- Yong Zhang
- Gastrointestinal Diseases Research Unit, Queen's University, Kingston, Ontario, Canada
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Opazo A, Lecea B, Admella C, Fantova MJ, Jiménez M, Martí-Ragué J, Clavé P. A comparative study of structure and function of the longitudinal muscle of the anal canal and the internal anal sphincter in pigs. Dis Colon Rectum 2009; 52:1902-11. [PMID: 19966640 DOI: 10.1007/dcr.0b013e3181b160be] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
PURPOSE This study aims to compare the physiology of the longitudinal muscle of the anal canal with the internal anal sphincter in pigs. METHODS Histology and in vitro studies were performed to compare the effect of neural responses induced by electric stimulation and through nicotinic, purinergic, and serotoninergic receptors. RESULTS The longitudinal muscle and the internal anal sphincter are constituted exclusively by smooth muscle. Strips from the internal anal sphincter a) developed myogenic tone; b) responded to electric stimulation with an "on" relaxation antagonized by nitric oxide synthase inhibitors and purinergic P2Y1 antagonists, and with an "off" contraction antagonized by atropine and phentolamine; and c) responded to stimulation of nicotinic receptors with a relaxation antagonized by nitrergic and purinergic P2Y1 antagonists, responded to stimulation of serotoninergic 5-hydroxytryptamine 3 receptors with a contraction, and relaxed to carbachol and purinergic P2X agonists. Strips from the longitudinal muscle a) did not develop tone, b) responded to electric stimulation with an "on" contraction antagonized by atropine, and c) did not respond to stimulation of nicotinic or serotoninergic 5-hydroxytryptamine 3 receptors, and carbachol and purinergic P2X agonists induced a contraction. CONCLUSIONS The motility of the internal anal sphincter includes myogenic tone, relaxation mediated by nitric oxide and purinergic P2Y1 receptors, and contraction mediated by cholinergic motor neurons and sympathetic fibers. The motility of the longitudinal muscle is limited to a contraction mediated by cholinergic neurons, suggesting that longitudinal muscle contracts during relaxation of the internal sphincter, shortening the anal canal. Nicotinic, muscarinic, and serotoninergic receptors might be therapeutic targets for anal motor disorders.
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Affiliation(s)
- Alvaro Opazo
- Department of Surgery, Hospital de Mataró, Universitat Autònoma de Barcelona, 08304, Mataró, Spain
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Tanaka C, Domae K, Hashitani H, Suzuki H. Modulation of slow waves by transmural nerve stimulation of smooth muscle tissue isolated from the corpus of the guinea-pig stomach. J Smooth Muscle Res 2009; 45:109-24. [DOI: 10.1540/jsmr.45.109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Chiharu Tanaka
- Department of Physiology, Nagoya City University Medical School
| | - Kazumasa Domae
- Department of Physiology, Nagoya City University Medical School
| | | | - Hikaru Suzuki
- Department of Physiology, Nagoya City University Medical School
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