1
|
Sanders KM, Drumm BT, Cobine CA, Baker SA. Ca 2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract. Physiol Rev 2024; 104:329-398. [PMID: 37561138 PMCID: PMC11281822 DOI: 10.1152/physrev.00036.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 06/29/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023] Open
Abstract
The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.
Collapse
Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
| | - Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caroline A Cobine
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Salah A Baker
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
| |
Collapse
|
2
|
Hwang SJ, Drumm BT, Kim MK, Lyu JH, Baker S, Sanders KM, Ward SM. Calcium transients in intramuscular interstitial cells of Cajal of the murine gastric fundus and their regulation by neuroeffector transmission. J Physiol 2022; 600:4439-4463. [PMID: 36057845 DOI: 10.1113/jp282876] [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: 05/13/2022] [Accepted: 08/15/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The cells responsible for mediating enteric neuroeffector transmission remain controversial. In the stomach intramuscular interstitial cells of Cajal (ICC-IM) were the first ICC reported to receive cholinergic and nitrergic neural inputs. Utilization of a cell specific calcium biosensor, GCaMP6f, the activity and neuroeffector responses of ICC-IM were examined. ICC-IM were highly active, generating stochastic intracellular Ca2+ -transients. Stimulation of enteric motor nerves abolished Ca2+ -transients in ICC-IM. This inhibitory response was preceded by a global rise in intracellular Ca2+ . Individual ICC-IM responded to nerve stimulation with a rise in Ca2+ followed by inhibition of Ca2+ -transients. Inhibition of Ca2+ -transients was blocked by the nitric oxide synthase antagonist, L-NNA. The global rise in Ca2+ was inhibited by the muscarinic antagonist, atropine. Simultaneous intracellular recordings with video imaging revealed that the global rise in intracellular Ca2+ and inhibition of Ca2+ -transients was temporally associated with rapid excitatory junction potentials followed by more sustained inhibitory junction potentials. The data presented support the premise of serial innervation of ICC-IM in excitatory and inhibitory neuroeffector transmission in the proximal stomach. ABSTRACT Enteric neurotransmission is critical for coordinating motility throughout the gastrointestinal (GI) tract. However, there is considerable controversy regarding the cells that are responsible for the transduction of these neural inputs. In the present study, utilization of a cell-specific calcium biosensor GCaMP6f, the spontaneous activity and neuroeffector responses of intramuscular ICC (ICC-IM) to motor neural inputs was examined. Simultaneous intracellular microelectrode recordings and high-speed video-imaging during nerve stimulation was used to reveal the temporal relationship between changes in intracellular Ca2+ and post-junctional electrical responses to neural stimulation. ICC-IM were highly active, generating intracellular Ca2+ -transients that occurred stochastically, from multiple independent sites in single ICC-IM. Ca2+ -transients were not entrained in single ICC-IM or between neighboring ICC-IM. Activation of enteric motor neurons produced a dominant inhibitory response that abolished Ca2+ -transients in ICC-IM. This inhibitory response was often preceded by a summation of Ca2+ -transients that led to a global rise in Ca2+ . Individual ICC-IM responded to nerve stimulation by a global rise in Ca2+ followed by inhibition of Ca2+ -transients. The inhibition of Ca2+ -transients was blocked by the nitric oxide synthase antagonist, L-NNA. The global rise in intracellular Ca2+ was inhibited by the muscarinic antagonist, atropine. Simultaneous intracellular microelectrode recordings with video-imaging revealed that the rise in Ca2+ was temporally associated with rapid excitatory junction potentials and the inhibition of Ca2+ -transients with inhibitory junction potentials. These data support the premise of serial innervation of ICC-IM in excitatory and inhibitory neuroeffector transmission in the proximal stomach. Abstract figure legend Intramuscular interstitial cells of Cajal (ICC-IM) of the gastric fundus receive nitrergic inhibitory and cholinergic excitatory neuroeffector motor inputs. Using a genetically encoded calcium sensor we demonstrate that ICC-IM are highly active cells generating stochastic intracellular Ca2 -transients. Stimulation of enteric motor nerves abolished Ca2 -transients in ICC-IM, produced an inhibitory junction potential (IJP) and muscle relaxation that was mediated by nitric oxide (left hand side of figure). This inhibitory response was often preceded by a global rise in intracellular Ca2 in ICC-IM, a rapid excitatory junction potential (EJP) and muscle contraction, that was mediated by acetylcholine (right hand side of figure). Individual ICC-IM could respond to both excitatory and inhibitory neural inputs. These data support the premise of serial innervation of ICC-IM in excitatory and inhibitory neuroeffector transmission in the proximal stomach. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Sung Jin Hwang
- Department of Physiology & Cell Biology, Reno School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Bernard T Drumm
- Department of Physiology & Cell Biology, Reno School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Min Kyung Kim
- Department of Physiology & Cell Biology, Reno School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Ju Hyeong Lyu
- Department of Physiology & Cell Biology, Reno School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Sal Baker
- Department of Physiology & Cell Biology, Reno School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Kenton M Sanders
- Department of Physiology & Cell Biology, Reno School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Sean M Ward
- Department of Physiology & Cell Biology, Reno School of Medicine, University of Nevada, Reno, NV, 89557, USA
| |
Collapse
|
3
|
Parsons SP, Huizinga JD. Nitric Oxide Is Essential for Generating the Minute Rhythm Contraction Pattern in the Small Intestine, Likely via ICC-DMP. Front Neurosci 2021; 14:592664. [PMID: 33488345 PMCID: PMC7817771 DOI: 10.3389/fnins.2020.592664] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/25/2020] [Indexed: 12/16/2022] Open
Abstract
Nitrergic nerves have been proposed to play a critical role in the orchestration of peristaltic activities throughout the gastrointestinal tract. In the present study, we investigated the role of nitric oxide, using spatiotemporal mapping, in peristaltic activity of the whole ex vivo mouse intestine. We identified a propulsive motor pattern in the form of propagating myogenic contractions, that are clustered by the enteric nervous system into a minute rhythm that is dependent on nitric oxide. The cluster formation was abolished by TTX, lidocaine and nitric oxide synthesis inhibition, whereas the myogenic contractions, occurring at the ICC-MP initiated slow wave frequency, remained undisturbed. Cluster formation, inhibited by block of nitric oxide synthesis, was fully restored in a highly regular rhythmic fashion by a constant level of nitric oxide generated by sodium nitroprusside; but the action of sodium nitroprusside was inhibited by lidocaine indicating that it was relying on neural activity, but not rhythmic nitrergic nerve activity. Hence, distention-induced activity of cholinergic nerves and/or a co-factor within nitrergic nerves such as ATP is also a requirement for the minute rhythm. Cluster formation was dependent on distention but was not evoked by a distention reflex. Block of gap junction conductance by carbenoxolone, dose dependently inhibited, and eventually abolished clusters and contraction waves, likely associated, not with inhibition of nitrergic innervation, but by abolishing ICC network synchronization. An intriguing feature of the clusters was the presence of bands of rhythmic inhibitions at 4-8 cycles/min; these inhibitory patches occurred in the presence of tetrodotoxin or lidocaine and hence were not dependent on nitrergic nerves. We propose that the minute rhythm is generated by nitric oxide-induced rhythmic depolarization of the musculature via ICC-DMP.
Collapse
Affiliation(s)
- Sean P. Parsons
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Jan D. Huizinga
- Department of Medicine and School of Biomedical Engineering, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| |
Collapse
|
4
|
Schneider S, Wright CM, Heuckeroth RO. Unexpected Roles for the Second Brain: Enteric Nervous System as Master Regulator of Bowel Function. Annu Rev Physiol 2019; 81:235-259. [DOI: 10.1146/annurev-physiol-021317-121515] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
At the most fundamental level, the bowel facilitates absorption of small molecules, regulates fluid and electrolyte flux, and eliminates waste. To successfully coordinate this complex array of functions, the bowel relies on the enteric nervous system (ENS), an intricate network of more than 500 million neurons and supporting glia that are organized into distinct layers or plexi within the bowel wall. Neuron and glial diversity, as well as neurotransmitter and receptor expression in the ENS, resembles that of the central nervous system. The most carefully studied ENS functions include control of bowel motility, epithelial secretion, and blood flow, but the ENS also interacts with enteroendocrine cells, influences epithelial proliferation and repair, modulates the intestinal immune system, and mediates extrinsic nerve input. Here, we review the many different cell types that communicate with the ENS, integrating data about ENS function into a broader view of human health and disease. In particular, we focus on exciting new literature highlighting relationships between the ENS and its lesser-known interacting partners.
Collapse
Affiliation(s)
- Sabine Schneider
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Christina M. Wright
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Robert O. Heuckeroth
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Abramson Research Center, The Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania 19104, USA
| |
Collapse
|
5
|
Sung TS, Hwang SJ, Koh SD, Bayguinov Y, Peri LE, Blair PJ, Webb TI, Pardo DM, Rock JR, Sanders KM, Ward SM. The cells and conductance mediating cholinergic neurotransmission in the murine proximal stomach. J Physiol 2018; 596:1549-1574. [PMID: 29430647 PMCID: PMC5924836 DOI: 10.1113/jp275478] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/26/2018] [Indexed: 12/23/2022] Open
Abstract
KEY POINTS Enteric neurotransmission is essential for gastrointestinal (GI) motility, although the cells and conductances responsible for post-junctional responses are controversial. The calcium-activated chloride conductance (CaCC), anoctamin-1 (Ano1), was expressed by intramuscular interstitial cells of Cajal (ICC-IM) in proximal stomach and not resolved in smooth muscle cells (SMCs). Cholinergic nerve fibres were closely apposed to ICC-IM. Conductances activated by cholinergic stimulation in isolated ICC-IM and SMCs were determined. A CaCC was activated by carbachol in ICC-IM and a non-selective cation conductance in SMCs. Responses to cholinergic nerve stimulation were studied. Excitatory junction potentials (EJPs) and mechanical responses were evoked in wild-type mice but absent or greatly reduced with knockout/down of Ano1. Drugs that block Ano1 inhibited the conductance activated by carbachol in ICC-IM and EJPs and mechanical responses in tissues. The data of the present study suggest that electrical and mechanical responses to cholinergic nerve stimulation are mediated by Ano1 expressed in ICC-IM and not SMCs. ABSTRACT Enteric motor neurotransmission is essential for normal gastrointestinal (GI) motility. Controversy exists regarding the cells and ionic conductance(s) that mediate post-junctional neuroeffector responses to motor neurotransmitters. Isolated intramuscular ICC (ICC-IM) and smooth muscle cells (SMCs) from murine fundus muscles were used to determine the conductances activated by carbachol (CCh) in each cell type. The calcium-activated chloride conductance (CaCC), anoctamin-1 (Ano1) is expressed by ICC-IM but not resolved in SMCs, and CCh activated a Cl- conductance in ICC-IM and a non-selective cation conductance in SMCs. We also studied responses to nerve stimulation using electrical-field stimulation (EFS) of intact fundus muscles from wild-type and Ano1 knockout mice. EFS activated excitatory junction potentials (EJPs) in wild-type mice, although EJPs were absent in mice with congenital deactivation of Ano1 and greatly reduced in animals in which the CaCC-Ano1 was knocked down using Cre/loxP technology. Contractions to cholinergic nerve stimulation were also greatly reduced in Ano1 knockouts. SMCs cells also have receptors and ion channels activated by muscarinic agonists. Blocking acetylcholine esterase with neostigmine revealed a slow depolarization that developed after EJPs in wild-type mice. This depolarization was still apparent in mice with genetic deactivation of Ano1. Pharmacological blockers of Ano1 also inhibited EJPs and contractile responses to muscarinic stimulation in fundus muscles. The data of the present study are consistent with the hypothesis that ACh released from motor nerves binds muscarinic receptors on ICC-IM with preference and activates Ano1. If metabolism of acetylcholine is inhibited, ACh overflows and binds to extrajunctional receptors on SMCs, eliciting a slower depolarization response.
Collapse
Affiliation(s)
- Tae Sik Sung
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Sung Jin Hwang
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Yulia Bayguinov
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Lauen E. Peri
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Peter J. Blair
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Timothy I. Webb
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - David M. Pardo
- Department of AnatomyUniversity of CaliforniaSan FranciscoCAUSA
| | - Jason R. Rock
- Center for Regenerative MedicineBoston University School of MedicineBostonMAUSA
| | - Kenton M. Sanders
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| | - Sean M. Ward
- Department of Physiology and Cell Biology, University of NevadaReno School of MedicineRenoNVUSA
| |
Collapse
|
6
|
Effect of acupuncture at points selected from different regions on SCF-kit signaling pathway in diabetic gastroparesis rats. JOURNAL OF ACUPUNCTURE AND TUINA SCIENCE 2017. [DOI: 10.1007/s11726-017-0978-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
7
|
Sanders KM, Kito Y, Hwang SJ, Ward SM. Regulation of Gastrointestinal Smooth Muscle Function by Interstitial Cells. Physiology (Bethesda) 2017; 31:316-26. [PMID: 27488743 DOI: 10.1152/physiol.00006.2016] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Interstitial cells of mesenchymal origin form gap junctions with smooth muscle cells in visceral smooth muscles and provide important regulatory functions. In gastrointestinal (GI) muscles, there are two distinct classes of interstitial cells, c-Kit(+) interstitial cells of Cajal and PDGFRα(+) cells, that regulate motility patterns. Loss of these cells may contribute to symptoms in GI motility disorders.
Collapse
Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada; and
| | - Yoshihiko Kito
- Department of Pharmacology, Faculty of Medicine, Saga University, Nabeshima, Japan
| | - Sung Jin Hwang
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada; and
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada; and
| |
Collapse
|
8
|
Goyal RK. CrossTalk opposing view: Interstitial cells are not involved and physiologically important in neuromuscular transmission in the gut. J Physiol 2016; 594:1511-3. [PMID: 26842563 DOI: 10.1113/jp271587] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Raj K Goyal
- Harvard Medical School and VA Boston Healthcare System, West Roxbury, MA, 02132, USA
| |
Collapse
|
9
|
Sanders KM, Ward SM, Friebe A. CrossTalk proposal: Interstitial cells are involved and physiologically important in neuromuscular transmission in the gut. J Physiol 2016; 594:1507-9. [PMID: 26842401 DOI: 10.1113/jp271600] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89511, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, 89511, USA
| | - Andreas Friebe
- Physiologisches Institut, Universität Würzburg, Würzburg, Germany
| |
Collapse
|
10
|
Groneberg D, Zizer E, Lies B, Seidler B, Saur D, Wagner M, Friebe A. Dominant role of interstitial cells of Cajal in nitrergic relaxation of murine lower oesophageal sphincter. J Physiol 2014; 593:403-14. [PMID: 25630261 DOI: 10.1113/jphysiol.2014.273540] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 10/24/2014] [Indexed: 12/20/2022] Open
Abstract
Oesophageal achalasia is a disease known to result from reduced relaxation of the lower oesophageal sphincter (LES). Nitric oxide (NO) is one of the main inhibitory transmitters. NO-sensitive guanylyl cyclase (NO-GC) acts as the key target of NO and, by the generation of cGMP, mediates nitrergic relaxation in the LES. To date, the exact mechanism of nitrergic LES relaxation is still insufficiently elucidated. To clarify the role of NO-GC in LES relaxation, we used cell-specific knockout (KO) mouse lines for NO-GC. These include mice lacking NO-GC in smooth muscle cells (SMC-GCKO), in interstitial cells of Cajal (ICC-GCKO) and in both SMC/ICC (SMC/ICC-GCKO). We applied oesophageal manometry to study the functionality of LES in vivo. Isometric force studies were performed to monitor LES responsiveness to exogenous NO and electric field stimulation of intrinsic nerves in vitro. Cell-specific expression/deletion of NO-GC was monitored by immunohistochemistry. Swallowing-induced LES relaxation is strongly reduced by deletion of NO-GC in ICC. Basal LES tone is affected by NO-GC deletion in either SMC or ICC. Lack of NO-GC in both cells leads to a complete interruption of NO-induced relaxation and, therefore, to an achalasia-like phenotype similar to that seen in global GCKO mice. Our data indicate that regulation of basal LES tone is based on a dual mechanism mediated by NO-GC in SMC and ICC whereas swallow-induced LES relaxation is mainly regulated by nitrergic mechanisms in ICC.
Collapse
Affiliation(s)
- Dieter Groneberg
- Physiologisches Institut I, Universität Würzburg, Würzburg, Germany
| | | | | | | | | | | | | |
Collapse
|
11
|
Sanders KM, Ward SM, Koh SD. Interstitial cells: regulators of smooth muscle function. Physiol Rev 2014; 94:859-907. [PMID: 24987007 DOI: 10.1152/physrev.00037.2013] [Citation(s) in RCA: 321] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Smooth muscles are complex tissues containing a variety of cells in addition to muscle cells. Interstitial cells of mesenchymal origin interact with and form electrical connectivity with smooth muscle cells in many organs, and these cells provide important regulatory functions. For example, in the gastrointestinal tract, interstitial cells of Cajal (ICC) and PDGFRα(+) cells have been described, in detail, and represent distinct classes of cells with unique ultrastructure, molecular phenotypes, and functions. Smooth muscle cells are electrically coupled to ICC and PDGFRα(+) cells, forming an integrated unit called the SIP syncytium. SIP cells express a variety of receptors and ion channels, and conductance changes in any type of SIP cell affect the excitability and responses of the syncytium. SIP cells are known to provide pacemaker activity, propagation pathways for slow waves, transduction of inputs from motor neurons, and mechanosensitivity. Loss of interstitial cells has been associated with motor disorders of the gut. Interstitial cells are also found in a variety of other smooth muscles; however, in most cases, the physiological and pathophysiological roles for these cells have not been clearly defined. This review describes structural, functional, and molecular features of interstitial cells and discusses their contributions in determining the behaviors of smooth muscle tissues.
Collapse
Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| |
Collapse
|
12
|
Huizinga JD, Chen JH. Interstitial cells of Cajal: update on basic and clinical science. Curr Gastroenterol Rep 2014; 16:363. [PMID: 24408748 DOI: 10.1007/s11894-013-0363-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The basic science and clinical interest in the networks of interstitial cells of Cajal (ICC) keep growing, and here, research from 2010 to mid-2013 is highlighted. High-resolution gastrointestinal manometry and spatiotemporal mapping are bringing exciting new insights into motor patterns, their function and their myogenic and neurogenic origins, as well as the role of ICC. Critically important knowledge is emerging on the partaking of PDGFRα+ cells in ICC pacemaker networks. Evidence is emerging that ICC and PDGFRα+ cells have unique direct roles in muscle innervation. Chronic constipation is associated with loss and injury to ICC, which is stimulating extensive research into maintenance and repair of ICC after injury. In gastroparesis, high-resolution electrical and mechanical studies are beginning to elucidate the pathophysiological role of ICC and the pacemaker system in this condition. Receptors and ion channels that play a role in ICC function are being discovered and characterized, which paves the way for pharmacological interventions in gut motility disorders through ICC.
Collapse
Affiliation(s)
- Jan D Huizinga
- Farncombe Family Digestive Health Research Institute, McMaster University, HSC-3N8, 1200 Main Street West, Hamilton, ON, Canada, L8N 3Z5,
| | | |
Collapse
|
13
|
Blair PJ, Rhee PL, Sanders KM, Ward SM. The significance of interstitial cells in neurogastroenterology. J Neurogastroenterol Motil 2014; 20:294-317. [PMID: 24948131 PMCID: PMC4102150 DOI: 10.5056/jnm14060] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/06/2014] [Accepted: 06/07/2014] [Indexed: 12/21/2022] Open
Abstract
Smooth muscle layers of the gastrointestinal tract consist of a heterogeneous population of cells that include enteric neurons, several classes of interstitial cells of mesenchymal origin, a variety of immune cells and smooth muscle cells (SMCs). Over the last number of years the complexity of the interactions between these cell types has begun to emerge. For example, interstitial cells, consisting of both interstitial cells of Cajal (ICC) and platelet-derived growth factor receptor alpha-positive (PDGFRα(+)) cells generate pacemaker activity throughout the gastrointestinal (GI) tract and also transduce enteric motor nerve signals and mechanosensitivity to adjacent SMCs. ICC and PDGFRα(+) cells are electrically coupled to SMCs possibly via gap junctions forming a multicellular functional syncytium termed the SIP syncytium. Cells that make up the SIP syncytium are highly specialized containing unique receptors, ion channels and intracellular signaling pathways that regulate the excitability of GI muscles. The unique role of these cells in coordinating GI motility is evident by the altered motility patterns in animal models where interstitial cell networks are disrupted. Although considerable advances have been made in recent years on our understanding of the roles of these cells within the SIP syncytium, the full physiological functions of these cells and the consequences of their disruption in GI muscles have not been clearly defined. This review gives a synopsis of the history of interstitial cell discovery and highlights recent advances in structural, molecular expression and functional roles of these cells in the GI tract.
Collapse
Affiliation(s)
- Peter J Blair
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA; and
| | - Poong-Lyul Rhee
- Division of Gastroenterology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA; and
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA; and
| |
Collapse
|
14
|
Blair PJ, Rhee PL, Sanders KM, Ward SM. The significance of interstitial cells in neurogastroenterology. J Neurogastroenterol Motil 2014. [PMID: 24948131 DOI: 10.5056/jnm140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Smooth muscle layers of the gastrointestinal tract consist of a heterogeneous population of cells that include enteric neurons, several classes of interstitial cells of mesenchymal origin, a variety of immune cells and smooth muscle cells (SMCs). Over the last number of years the complexity of the interactions between these cell types has begun to emerge. For example, interstitial cells, consisting of both interstitial cells of Cajal (ICC) and platelet-derived growth factor receptor alpha-positive (PDGFRα(+)) cells generate pacemaker activity throughout the gastrointestinal (GI) tract and also transduce enteric motor nerve signals and mechanosensitivity to adjacent SMCs. ICC and PDGFRα(+) cells are electrically coupled to SMCs possibly via gap junctions forming a multicellular functional syncytium termed the SIP syncytium. Cells that make up the SIP syncytium are highly specialized containing unique receptors, ion channels and intracellular signaling pathways that regulate the excitability of GI muscles. The unique role of these cells in coordinating GI motility is evident by the altered motility patterns in animal models where interstitial cell networks are disrupted. Although considerable advances have been made in recent years on our understanding of the roles of these cells within the SIP syncytium, the full physiological functions of these cells and the consequences of their disruption in GI muscles have not been clearly defined. This review gives a synopsis of the history of interstitial cell discovery and highlights recent advances in structural, molecular expression and functional roles of these cells in the GI tract.
Collapse
Affiliation(s)
- Peter J Blair
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Poong-Lyul Rhee
- Division of Gastroenterology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| |
Collapse
|
15
|
Lies B, Gil V, Groneberg D, Seidler B, Saur D, Wischmeyer E, Jiménez M, Friebe A. Interstitial cells of Cajal mediate nitrergic inhibitory neurotransmission in the murine gastrointestinal tract. Am J Physiol Gastrointest Liver Physiol 2014; 307:G98-106. [PMID: 24833707 DOI: 10.1152/ajpgi.00082.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nitric oxide (NO) is a major inhibitory neurotransmitter in the gastrointestinal (GI) tract. Its main effector, NO-sensitive guanylyl cyclase (NO-GC), is expressed in several GI cell types, including smooth muscle cells (SMC), interstitial cells of Cajal (ICC), and fibroblast-like cells. Up to date, the interplay between neurons and these cells to initiate a nitrergic inhibitory junction potential (IJP) is unclear. Here, we investigate the origin of the nitrergic IJP in murine fundus and colon. IJPs were determined in fundus and colon SMC of mice lacking NO-GC globally (GCKO) and specifically in SMC (SM-GCKO), ICC (ICC-GCKO), and both SMC/ICC (SM/ICC-GCKO). Nitrergic IJP was abolished in ICC-GCKO fundus and reduced in SM-GCKO fundus. In the colon, the amplitude of nitrergic IJP was reduced in ICC-GCKO, whereas nitrergic IJP in SM-GCKO was reduced in duration. These results were corroborated by loss of the nitrergic IJP in global GCKO. In conclusion, our results prove the obligatory role of NO-GC in ICC for the initiation of an IJP. NO-GC in SMC appears to enhance the nitrergic IJP, resulting in a stronger and prolonged hyperpolarization in fundus and colon SMC, respectively. Thus NO-GC in both cell types is mandatory to induce a full nitrergic IJP. Our data from the colon clearly reveal the nitrergic IJP to be biphasic, resulting from individual inputs of ICC and SMC.
Collapse
Affiliation(s)
- Barbara Lies
- Physiologisches Institut, Universität Würzburg, Würzburg, Germany
| | - Víctor Gil
- 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; and
| | - Dieter Groneberg
- Physiologisches Institut, Universität Würzburg, Würzburg, Germany
| | - Barbara Seidler
- II. Medizinische Klinik und Poliklinik, Technische Universität München, München, Germany
| | - Dieter Saur
- II. Medizinische Klinik und Poliklinik, Technische Universität München, München, Germany
| | | | - 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; and
| | - Andreas Friebe
- Physiologisches Institut, Universität Würzburg, Würzburg, Germany;
| |
Collapse
|
16
|
Sanders KM, Salter AK, Hennig GW, Koh SD, Perrino BA, Ward SM, Baker SA. Responses to enteric motor neurons in the gastric fundus of mice with reduced intramuscular interstitial cells of cajal. J Neurogastroenterol Motil 2014; 20:171-84. [PMID: 24840370 PMCID: PMC4015192 DOI: 10.5056/jnm.2014.20.2.171] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 01/26/2014] [Accepted: 01/28/2014] [Indexed: 12/31/2022] Open
Abstract
Background/Aims Interstitial cells of Cajal (ICC) play important functions in motor activity of the gastrointestinal tract. The role of ICC as pacemakers is well established, however their participation in neurotransmission is controversial. Studies using mutant animals that lack ICC have yielded variable conclusions on their importance in enteric motor responses. The purpose of this study was to: (1) clarify the role of intramuscular ICC (ICC-IM) in gastric motor-neurotransmission and (2) evaluate remodeling of enteric motor responses in W/WV mice. Methods Kit immunohistochemistry and post-junctional contractile responses were performed on fundus muscles from wild-type and W/WV mice and quantitative polymerase chain reaction (qPCR) was used to evaluate differences in muscarinic and neurokinin receptor expression. Results Although ICC-IM were greatly reduced in comparison with wild-type mice, we found that ICC-IM persisted in the fundus of many W/WV animals. ICC-IM were not observed in W/WV group 1 (46%) but were observed in W/WV group 2 (40%). Evoked neural responses consisted of excitatory and inhibitory components. The inhibitory component (nitrergic) was absent in W/WV group 1 and reduced in W/WV group 2. Enhanced excitatory responses (cholinergic) were observed in both W/WV groups and qPCR revealed that muscarinic-M3 receptor expression was significantly augmented in the W/WV fundus compared to wild-type controls. Conclusions This study demonstrates that ICC-IM mediate nitrergic inhibitory neurotransmission in the fundus and provides evidence of plasticity changes in neuronal responses that may explain discrepancies in previous functional studies which utilized mutant animals to examine the role of ICC-IM in gastric enteric motor responses.
Collapse
Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Anna K Salter
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Brian A Perrino
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| |
Collapse
|
17
|
Winston JH, Chen J, Shi XZ, Sarna SK. Inflammation induced by mast cell deficiency rather than the loss of interstitial cells of Cajal causes smooth muscle dysfunction in W/W(v) mice. Front Physiol 2014; 5:22. [PMID: 24550836 PMCID: PMC3912454 DOI: 10.3389/fphys.2014.00022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 01/09/2014] [Indexed: 01/19/2023] Open
Abstract
The initial hypothesis suggested that the interstitial cells of Cajal (ICC) played an essential role in mediating enteric neuronal input to smooth muscle cells. Much information for this hypothesis came from studies in W/Wv mice lacking ICC. However, mast cells, which play critical roles in regulating inflammation in their microenvironment, are also absent in W/Wv mice. We tested the hypothesis that the depletion of mast cells in W/Wv mice generates inflammation in fundus muscularis externa (ME) that impairs smooth muscle reactivity to Ach, independent of the depletion of ICC. We performed experiments on the fundus ME from wild type (WT) and W/Wv mice before and after reconstitution of mast cells by bone marrow transplant. We found that mast cell deficiency in W/Wv mice significantly increased COX-2 and iNOS expression and decreased smooth muscle reactivity to Ach. Mast cell reconstitution or concurrent blockade of COX-2 and iNOS restored smooth muscle contractility without affecting the suppression of c-kit in W/Wv mice. The expression of nNOS and ChAT were suppressed in W/Wv mice; mast cell reconstitution did not restore them. We conclude that innate inflammation induced by mast cell deficiency in W/Wv mice impairs smooth muscle contractility independent of ICC deficiency. The impairment of smooth muscle contractility and the suppression of the enzymes regulating the synthesis of Ach and NO in W/Wv mice need to be considered in evaluating the role of ICC in regulating smooth muscle and enteric neuronal function in W/Wv mice.
Collapse
Affiliation(s)
- John H Winston
- Division of Gastroenterology, Department of Internal Medicine, Enteric Neuromuscular Disorders and Visceral Pain Center, The University of Texas Medical Branch at Galveston Galveston, TX, USA
| | - Jinghong Chen
- Division of Gastroenterology, Department of Internal Medicine, Enteric Neuromuscular Disorders and Visceral Pain Center, The University of Texas Medical Branch at Galveston Galveston, TX, USA
| | - Xuan-Zheng Shi
- Division of Gastroenterology, Department of Internal Medicine, Enteric Neuromuscular Disorders and Visceral Pain Center, The University of Texas Medical Branch at Galveston Galveston, TX, USA
| | - Sushil K Sarna
- Division of Gastroenterology, Department of Internal Medicine, Enteric Neuromuscular Disorders and Visceral Pain Center, The University of Texas Medical Branch at Galveston Galveston, TX, USA
| |
Collapse
|
18
|
Interstitial cells of Cajal integrate excitatory and inhibitory neurotransmission with intestinal slow-wave activity. Nat Commun 2013; 4:1630. [PMID: 23535651 DOI: 10.1038/ncomms2626] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 02/20/2013] [Indexed: 12/27/2022] Open
Abstract
The enteric nervous system contains excitatory and inhibitory neurons, which control contraction and relaxation of smooth muscle cells as well as gastrointestinal motor activity. Little is known about the exact cellular mechanisms of neuronal signal transduction to smooth muscle cells in the gut. Here we generate a c-Kit(CreERT2) knock-in allele to target a distinct population of pacemaker cells called interstitial cells of Cajal. By genetic loss-of-function studies, we show that interstitial cells of Cajal, which generate spontaneous electrical slow waves and thus rhythmic contractions of the smooth musculature, are essential for transmission of signals from enteric neurons to gastrointestinal smooth muscle cells. Interstitial cells of Cajal, therefore, integrate excitatory and inhibitory neurotransmission with slow-wave activity to orchestrate peristaltic motor activity of the gut. Impairment of the function of interstitial cells of Cajal causes severe gastrointestinal motor disorders. The results of our study show at the genetic level that these disorders are not only due to loss of slow-wave activity but also due to disturbed neurotransmission.
Collapse
|
19
|
Bautista-Cruz F, Nair DG, Lourenssen S, Miller DV, Blennerhassett MG, Paterson WG. Impaired platelet-derived growth factor receptor expression and function in cultured lower esophageal sphincter circular smooth muscle cells from W/W(v) mutant mice. Can J Physiol Pharmacol 2013; 92:34-41. [PMID: 24383871 DOI: 10.1139/cjpp-2013-0254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously demonstrated that lower esophageal sphincter (LES) circular smooth muscle (CSM) is functionally impaired in W/W(v) mutant mice that lack interstitial cells of Cajal, and speculated that this could be due to altered smooth muscle differentiation. Platelet-derived growth factor (PDGF) is involved in the maturation and differentiation of smooth muscle. To determine whether PDGF expression and (or) function is altered in W/W(v) mutant mice, PDGF-Rβ expression was measured using RT-PCR, qPCR, and immunocytochemistry, and Ca(2+) imaging and perforated patch clamp recordings performed in isolated LES CSM cells. RT-PCR and immunocytochemistry showed significantly reduced PDGF-Rβ expression in the LES from mutant as opposed to wild-type mice. Quantitative comparison of CSM cell numbers in histological specimens revealed a significantly increased average cell size in the mutant tissue. The specific PDGF-Rβ ligand, PDGF-BB, caused a significant increase in intracellular Ca(2+) in cells from the wild-type mice compared with the mutants. Using a ramp protocol, PDGF-BB caused a 2-fold increase in outward K(+) currents in cells from the wild-type mice, whereas no significant increase was measured in the cells from the mutants. We conclude that the expression and function of PDGF-Rβ in LES CSM from W/W(v) mice is impaired, providing further evidence that LES CSM is abnormal in W/W(v) mutants.
Collapse
Affiliation(s)
- Francisco Bautista-Cruz
- a Gastrointestinal Disease Research Unit, Kingston General Hospital, 76 Stuart Street, Kingston ON K7L 2V7, Canada
| | | | | | | | | | | |
Collapse
|
20
|
Groneberg D, Lies B, König P, Jäger R, Seidler B, Klein S, Saur D, Friebe A. Cell-specific deletion of nitric oxide-sensitive guanylyl cyclase reveals a dual pathway for nitrergic neuromuscular transmission in the murine fundus. Gastroenterology 2013; 145:188-196. [PMID: 23528627 DOI: 10.1053/j.gastro.2013.03.042] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 02/26/2013] [Accepted: 03/18/2013] [Indexed: 01/29/2023]
Abstract
BACKGROUND & AIMS It is not clear how nitric oxide (NO) released from enteric neurons relaxes gastrointestinal (GI) smooth muscle. In analogy to the vascular system, NO might directly induce relaxation of smooth muscle cells (SMCs) by acting on its receptor, NO-sensitive guanylyl cyclase (NO-GC). Alternatively, intermediate cells, such as the interstitial cells of Cajal (ICCs), might detect nitrergic signals to indirectly regulate smooth muscle tone, and thereby regulate the motor function of the GI tract. We investigated the role of ICCs and SMCs in nitrergic relaxation using mice with cell-specific disruption of the gene encoding the β1 subunit of NO-GC (GUCY1B3). METHODS We created mice that lack NO-GC specifically in SMCs (SM-guanylyl cyclase knockout [GCKO]), ICCs (ICC-GCKO), or both (SM/ICC-GCKO). We investigated the effects of exogenous and endogenous NO on murine fundus using isometric force studies. Total gut transit time was measured to monitor the functional consequences of NO-GC deletion on GI motility in vivo. RESULTS NO-GC is expressed in ICC and SMC. Deletion of the NO receptor from SMCs incompletely reduced NO-induced fundus relaxation, which was hardly affected after ICC-specific deletion. Gut transit time did not change in SM-GCKO or ICC-GCKO mice compared with control mice. However, nitrergic relaxation was not observed in SM/ICC-GCKO mice, which had increased gut transit time compared with controls. CONCLUSIONS In mice, NO-GC is the only NO receptor to relax the fundus; deletion of NO-GC from the combination of SMCs and ICCs blocks nitrergic signaling. Therefore, ICCs and SMCs jointly mediate the relaxant effect of enteric NO.
Collapse
Affiliation(s)
- Dieter Groneberg
- Physiologisches Institut I, Universität Würzburg, Würzburg, Germany
| | - Barbara Lies
- Physiologisches Institut I, Universität Würzburg, Würzburg, Germany
| | - Peter König
- Institut für Anatomie, Zentrum für medizinische Struktur- und Zellbiologie, Universität zu Lübeck, Lübeck, Germany
| | - Ronald Jäger
- Physiologisches Institut I, Universität Würzburg, Würzburg, Germany
| | - Barbara Seidler
- II. Medizinische Klinik und Poliklinik, Technische Universität München, München, Germany
| | - Sabine Klein
- II. Medizinische Klinik und Poliklinik, Technische Universität München, München, Germany
| | - Dieter Saur
- II. Medizinische Klinik und Poliklinik, Technische Universität München, München, Germany
| | - Andreas Friebe
- Physiologisches Institut I, Universität Würzburg, Würzburg, Germany.
| |
Collapse
|
21
|
Bhetwal BP, Sanders KM, An C, Trappanese DM, Moreland RS, Perrino BA. Ca2+ sensitization pathways accessed by cholinergic neurotransmission in the murine gastric fundus. J Physiol 2013; 591:2971-86. [PMID: 23613531 DOI: 10.1113/jphysiol.2013.255745] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Ca(2+) sensitization of contraction has typically been investigated by bathing muscles in solutions containing agonists. However, it is unknown whether bath-applied agonists and enteric neurotransmission activate similar Ca(2+) sensitization mechanisms. We investigated protein kinase C (PKC)-potentiated phosphatase inhibitor protein of 17 kDa (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) phosphorylation in murine gastric fundus muscles stimulated by bath-applied carbachol (CCh) or cholinergic motor neurotransmission. CCh increased MYPT1 phosphorylation at Thr696 (pT696) and Thr853 (pT853), CPI-17 at Thr38 (pT38), and myosin light chain at Ser19 (pS19). Electrical field stimulation (EFS) only increased pT38. In the presence of neostigmine, EFS increased pT38, pT853 and pS19. In fundus muscles of W/W(v) mice, EFS alone increased pT38 and pT853. Atropine blocked all contractions and all increases in pT696, pT853, pT38 and pS19. The Rho kinase (ROCK) inhibitor SAR1x blocked increases in pT853 and pT696. The PKC inhibitors Go6976 and Gf109203x or nicardipine blocked increases in pT38 and pT696. These findings suggest that cholinergic motor neurotransmission activates PKC-dependent CPI-17 phosphorylation. Bath-applied CCh recruits additional ROCK-dependent MYPT1 phosphorylation due to exposure of the agonist to a wider population of muscarinic receptors. Intramuscular interstitial cells of Cajal (ICC-IMs) and cholinesterases restrict ACh accessibility to a select population of muscarinic receptors, possibly only those expressed by ICC-IMs. These results provide the first biochemical evidence for focalized (or synaptic-like) neurotransmission, rather than diffuse 'volume' neurotransmission in a smooth muscle tissue. Furthermore, these findings demonstrate that bath application of contractile agonists to gastrointestinal smooth muscles does not mimic physiological responses to cholinergic neurotransmission.
Collapse
Affiliation(s)
- Bhupal P Bhetwal
- University of Nevada School of Medicine, Physiology and Cell Biology, University of Nevada, Reno, CMM203E, Reno, NV 89557, USA
| | | | | | | | | | | |
Collapse
|
22
|
Sanders KM, Koh SD, Ro S, Ward SM. Regulation of gastrointestinal motility--insights from smooth muscle biology. Nat Rev Gastroenterol Hepatol 2012; 9:633-45. [PMID: 22965426 PMCID: PMC4793911 DOI: 10.1038/nrgastro.2012.168] [Citation(s) in RCA: 270] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Gastrointestinal motility results from coordinated contractions of the tunica muscularis, the muscular layers of the alimentary canal. Throughout most of the gastrointestinal tract, smooth muscles are organized into two layers of circularly or longitudinally oriented muscle bundles. Smooth muscle cells form electrical and mechanical junctions between cells that facilitate coordination of contractions. Excitation-contraction coupling occurs by Ca(2+) entry via ion channels in the plasma membrane, leading to a rise in intracellular Ca(2+). Ca(2+) binding to calmodulin activates myosin light chain kinase; subsequent phosphorylation of myosin initiates cross-bridge cycling. Myosin phosphatase dephosphorylates myosin to relax muscles, and a process known as Ca(2+) sensitization regulates the activity of the phosphatase. Gastrointestinal smooth muscles are 'autonomous' and generate spontaneous electrical activity (slow waves) that does not depend upon input from nerves. Intrinsic pacemaker activity comes from interstitial cells of Cajal, which are electrically coupled to smooth muscle cells. Patterns of contractile activity in gastrointestinal muscles are determined by inputs from enteric motor neurons that innervate smooth muscle cells and interstitial cells. Here we provide an overview of the cells and mechanisms that generate smooth muscle contractile behaviour and gastrointestinal motility.
Collapse
|
23
|
Gil V, Gallego D, Moha Ou Maati H, Peyronnet R, Martínez-Cutillas M, Heurteaux C, Borsotto M, Jiménez M. Relative contribution of SKCa and TREK1 channels in purinergic and nitrergic neuromuscular transmission in the rat colon. Am J Physiol Gastrointest Liver Physiol 2012; 303:G412-23. [PMID: 22636169 DOI: 10.1152/ajpgi.00040.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Purinergic and nitrergic neurotransmission predominantly mediate inhibitory neuromuscular transmission in the rat colon. We studied the sensitivity of both purinergic and nitrergic pathways to spadin, a TWIK-related potassium channel 1 (TREK1) inhibitor, apamin, a small-conductance calcium-activated potassium channel blocker and 1H-[1,2,4]oxadiazolo[4,3-α]quinoxalin-1-one (ODQ), a specific inhibitor of soluble guanylate cyclase. TREK1 expression was detected by RT-PCR in the rat colon. Patch-clamp experiments were performed on cells expressing hTREK1 channels. Spadin (1 μM) reduced currents 1) in basal conditions 2) activated by stretch, and 3) with arachidonic acid (AA; 10 μM). l-Methionine (1 mM) or l-cysteine (1 mM) did not modify currents activated by AA. Microelectrode and muscle bath studies were performed on rat colon samples. l-Methionine (2 mM), apamin (1 μM), ODQ (10 μM), and N(ω)-nitro-l-arginine (l-NNA; 1 mM) depolarized smooth muscle cells and increased motility. These effects were not observed with spadin (1 μM). Purinergic and nitrergic inhibitory junction potentials (IJP) were studied by incubating the tissue with l-NNA (1 mM) or MRS2500 (1 μM). Both purinergic and nitrergic IJP were unaffected by spadin. Apamin reduced both IJP with a different potency and maximal effect for each. ODQ concentration dependently abolished nitrergic IJP without affecting purinergic IJP. Similar effects were observed in hyperpolarizations induced by sodium nitroprusside (1 μM) and nitrergic relaxations induced by electrical stimulation. We propose a pharmacological approach to characterize the pathways and function of purinergic and nitrergic neurotransmission. Nitrergic neurotransmission, which is mediated by cyclic guanosine monophosphate, is insensitive to spadin, an effective TREK1 channel inhibitor. Both purinergic and nitrergic neurotransmission are inhibited by apamin but with different relative sensitivity.
Collapse
Affiliation(s)
- V Gil
- Department of Cell Biology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Bautista-Cruz F, Paterson WG. Evidence for altered circular smooth muscle cell function in lower esophageal sphincter of W/Wv mutant mice. Am J Physiol Gastrointest Liver Physiol 2011; 301:G1059-65. [PMID: 21885685 DOI: 10.1152/ajpgi.00020.2011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nitrergic neurotransmission to gut smooth muscle is impaired in W/W(v) mutant mice, which lack intramuscular interstitial cells of Cajal (ICC-IM). In addition, these mice have been reported to have smaller amplitude unitary potentials (UPs) and a more negative resting membrane potential (RMP) than control mice. These abnormalities have been attributed to absence of ICC-IM, but it remains possible that they are due to alterations at the level of the smooth muscle itself. Amphotericin-B-perforated patch-clamp recordings and Ca(2+) imaging (fura 2) were compared between freshly isolated single circular smooth muscle cells (CSM) from W/W(v) mutant and control mice lower esophageal sphincter (LES). There was no significant difference in seal resistance, capacitance, or input resistance in response to applied electrotonic current pulses between CSM cells from W/W(v) mutants and controls. Compared with control mice, RMP was more negative and UPs significantly smaller in CSM cells from mutant mice LES. Administration of caffeine induced an inward current in cells from both mutant and control mice, but the current density was significantly larger in cells from W/W(v) mutants. Membrane potential hyperpolarization induced by sodium nitroprusside was larger in cells from control mice vs. W/W(v) mutants. In addition, intracellular Ca(2+) transients induced by caffeine were significantly increased in cells from mutants. These findings indicate that LES CSM is abnormal in W/W(v) mutant mice. Thus some physiological functions attributed to ICC-IM based on experiments in smooth muscle of ICC deficient mice may need to be reconsidered.
Collapse
Affiliation(s)
- Francisco Bautista-Cruz
- Gastrointestinal Diseases Research Unit, Kingston General Hospital, Department of Medicine, Queen's University Kingston, Ontario, Canada
| | | |
Collapse
|
25
|
Zhang RX, Wang XY, Chen D, Huizinga JD. Role of interstitial cells of Cajal in the generation and modulation of motor activity induced by cholinergic neurotransmission in the stomach. Neurogastroenterol Motil 2011; 23:e356-71. [PMID: 21781228 DOI: 10.1111/j.1365-2982.2011.01753.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Interstitial cells of Cajal (ICC) are intimately linked to the enteric nervous system and a better understanding of the interactions between the two systems is going to advance our understanding of gut motor control. The objective of the present study was to investigate the role of ICC in the generation of gastric motor activity induced by cholinergic neurotransmission. METHODS Gastric motor activity was evoked through activation of intrinsic cholinergic neural activity, in in vitro muscle strips by electrical field stimulation, in the in vitro whole stomach by distension and in vivo by fluoroscopy after gavaging the stomach with barium sulfate. The cholinergic activity was assessed as that component of the effect of the stimulus that was sensitive to atropine. These experiments were carried out in wild-type and Ws/Ws rats that have few intramuscular ICC (ICC-IM) in the stomach. KEY RESULTS Under all three experimental conditions, cholinergic activity was prominent in both wild-type and W mutant rats providing evidence against the hypothesis that cholinergic neurotransmission to smooth muscle is primarily mediated by ICC-IM. Strong cholinergic activity in Ws/Ws rats was not due to upregulation of muscarinic receptors in ICC but possibly in smooth muscle of the antrum. CONCLUSIONS & INFERENCES Pacemaker ICC play a prominent role in the expression of motor activity induced by cholinergic activity and our data suggest that cholinergic neurotransmission to ICC affects the pacemaker frequency.
Collapse
Affiliation(s)
- R-X Zhang
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, ON, Canada
| | | | | | | |
Collapse
|
26
|
Huizinga JD, Martz S, Gil V, Wang XY, Jimenez M, Parsons S. Two independent networks of interstitial cells of cajal work cooperatively with the enteric nervous system to create colonic motor patterns. Front Neurosci 2011; 5:93. [PMID: 21833164 PMCID: PMC3153851 DOI: 10.3389/fnins.2011.00093] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 07/13/2011] [Indexed: 12/12/2022] Open
Abstract
Normal motility of the colon is critical for quality of life and efforts to normalize abnormal colon function have had limited success. A better understanding of control systems of colonic motility is therefore essential. We report here a hypothesis with supporting experimental data to explain the origin of rhythmic propulsive colonic motor activity induced by general distention. The theory holds that both networks of interstitial cells of Cajal (ICC), those associated with the submuscular plexus (ICC-SMP) and those associated with the myenteric plexus (ICC-MP), orchestrate propagating contractions as pacemaker cells in concert with the enteric nervous system (ENS). ICC-SMP generate an omnipresent slow wave activity that causes propagating but non-propulsive contractions ("rhythmic propagating ripples") enhancing absorption. The ICC-MP generate stimulus-dependent cyclic depolarizations propagating anally and directing propulsive activity ("rhythmic propulsive motor complexes"). The ENS is not essential for both rhythmic motor patterns since distention and pharmacological means can produce the motor patterns after blocking neural activity, but it supplies the primary stimulus in vivo. Supporting data come from studies on segments of the rat colon, simultaneously measuring motility through spatiotemporal mapping of video recordings, intraluminal pressure, and outflow measurements.
Collapse
Affiliation(s)
- Jan D Huizinga
- Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University Hamilton, ON, Canada
| | | | | | | | | | | |
Collapse
|
27
|
Sancho M, Triguero D, Garcia-Pascual A. Direct coupling through gap junctions is not involved in urethral neurotransmission. Am J Physiol Renal Physiol 2011; 300:F864-72. [DOI: 10.1152/ajprenal.00641.2010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interstitial cells of Cajal (ICC) are believed to participate in urethral neurotransmission and it was proposed that direct coupling of ICC and smooth muscle cells (SMC) through gap junctions (GJ) is involved, although this still remains unclear. Hence, we investigated the distribution of different connexins (Cx 43, Cx40, and Cx37) in the sheep and rat urethra, as well as their possible role in neurotransmission. Conventional PCR confirmed that three Cxs are expressed in the urethra. Moreover, both Cx43 and Cx37-immunoreactivity (-ir) were present in SMC, ICC, and the urothelium, although Cx37-ir was significantly weaker and Cx40-ir was limited to the endothelium. While these results indicate that GJ intercellular communication could occur between SMC and ICC, neither the contractile (noradrenergic) nor the relaxant (nitrergic) responses of the rat and sheep urethra to electrical field stimulation were significantly modified by two different GJ inhibitors: 18α-glycyrrhetinic acid and a cocktail of Cx mimetic peptides (Cx43Gap 26,Cx37, Cx43Gap 27, andCx40Gap 27). By contrast, contractions induced by high K+were effectively reduced by both blockers, evidence that they effectively inhibit intercellular communication. These results indicate that GJ are not implicated in urethral neurotransmission, although the question of whether ICC modulate neurotransmission through some other mechanism remains to be determined.
Collapse
Affiliation(s)
- Maria Sancho
- Department of Physiology, Veterinary Faculty, Complutense University, Madrid, Spain
| | - Domingo Triguero
- Department of Physiology, Veterinary Faculty, Complutense University, Madrid, Spain
| | | |
Collapse
|
28
|
Galligan JJ. Synchronicity, cycles and synaptic signalling in the colon. J Physiol 2010; 588:4611. [PMID: 21123204 DOI: 10.1113/jphysiol.2010.200766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- James J Galligan
- Department of Pharmacology & Toxicology and the Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA.
| |
Collapse
|
29
|
Sanders KM, Hwang SJ, Ward SM. Neuroeffector apparatus in gastrointestinal smooth muscle organs. J Physiol 2010; 588:4621-39. [PMID: 20921202 DOI: 10.1113/jphysiol.2010.196030] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Control of gastrointestinal (GI) movements by enteric motoneurons is critical for orderly processing of food, absorption of nutrients and elimination of wastes. Work over the past several years has suggested that motor neurotransmission is more complicated than simple release of transmitter from nerve terminals and binding of receptors on smooth muscle cells. In fact the 'neuro-effector' junction in the tunica muscularis might consist of synaptic-like connectivity with specialized cells, and contributions from multiple cell types in integrated post-junctional responses. Interstitial cells of Cajal (ICC) were proposed as potential mediators in motor neurotransmission based on reduced post-junctional responses observed in W mutants that have reduced populations of ICC. More recent studies on W mutants have contradicted the original findings, and suggested that ICC may not be significant players in motor neurotransmission. This review examines the evidence for and against the role of ICC in motor neurotransmission and outlines areas for additional investigation that would help further resolve this controversy.
Collapse
Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
| | | | | |
Collapse
|
30
|
Izbeki F, Asuzu DT, Lorincz A, Bardsley MR, Popko LN, Choi KM, Young DL, Hayashi Y, Linden DR, Kuro-o M, Farrugia G, Ordog T. Loss of Kitlow progenitors, reduced stem cell factor and high oxidative stress underlie gastric dysfunction in progeric mice. J Physiol 2010; 588:3101-17. [PMID: 20581042 PMCID: PMC2956948 DOI: 10.1113/jphysiol.2010.191023] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 06/24/2010] [Indexed: 12/15/2022] Open
Abstract
Gastrointestinal functions decline with ageing leading to impaired quality of life, and increased morbidity and mortality. Neurodegeneration is believed to underlie ageing-associated dysmotilities but the mechanisms have not been fully elucidated. We used progeric mice deficient in the anti-ageing peptide Klotho to investigate the contribution of key cell types of the gastric musculature to ageing-associated changes in stomach function and the underlying mechanisms. Klotho expression, enteric neurons, interstitial cells of Cajal (ICC), smooth muscle cells and electrical activity were assessed by immunofluorescence, confocal microscopy, 3-dimensional reconstruction, flow cytometry, quantitative RT-PCR, Western immunoblotting and intracellular recordings. Gastric emptying of solids was analysed by the [13C]octanoic acid breath test. Circulating and tissue trophic factors were measured by enzyme immunoassays and quantitative RT-PCR. The role of oxidative stress was investigated in organotypic cultures. Klotho expression was detected in gastric glands, myenteric neurons and smooth muscle cells. Progeric Klotho-deficient mice had profound loss of ICC and ICC stem cells without a significant decrease in neuron counts, expression of neuronal nitric oxide synthase or smooth muscle myosin. Slow wave amplitude and nitrergic inhibitory junction potentials were reduced while solid emptying was unchanged. Klotho-deficient mice were marantic and had low insulin, insulin-like growth factor-I and membrane-bound stem cell factor. Klotho deficiency accentuated oxidative stress and ICC loss. We conclude that Klotho-deficient, progeric mice display a gastric phenotype resembling human ageing and involving profound ICC loss. Klotho protects ICC by preserving their precursors, limiting oxidative stress, and maintaining nutritional status and normal levels of trophic factors important for ICC differentiation.
Collapse
Affiliation(s)
- Ferenc Izbeki
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Guggenheim 10, 200 1st Street SW, Rochester, MN 55906, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Fintl C, Hudson NPH. The interstitial cells of Cajal of the equine gastrointestinal tract: what we know so far. Equine Vet J 2010; 42:372-7. [PMID: 20525058 DOI: 10.1111/j.2042-3306.2010.00073.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Gastrointestinal motility disorders are a serious problem in both veterinary and human medicine and may represent a dysfunction of the neural, muscular or pacemaker components (interstitial cells of Cajal) of bowel control. The interstitial cells of Cajal are considered to be the pacemakers and mediators of certain forms of neurotransmission in the gastrointestinal tract. These cells have been implicated, either primarily or secondarily, in the pathogenesis of gastrointestinal disease processes in which there is a prominent element of disturbance to intestinal motility. In the horse, their involvement has been implicated in large intestinal obstructive colic and grass sickness (equine dysautonomia). This review highlights the properties of the interstitial cells of Cajal and the role these cells play in orchestrating gastrointestinal motility patterns. In addition, it examines their role in intestinal motility disorders and summarises our current understanding of their importance in the equine gastrointestinal tract.
Collapse
Affiliation(s)
- C Fintl
- Norwegian School of Veterinary Science, Department of Companion Animal Clinical Sciences, PO Box 8146 Dep., 0033 Oslo, Norway
| | | |
Collapse
|
32
|
Takaki M, Suzuki H, Nakayama S. Recent advances in studies of spontaneous activity in smooth muscle: ubiquitous pacemaker cells. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 102:129-35. [PMID: 20553741 DOI: 10.1016/j.pbiomolbio.2010.05.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Accepted: 05/19/2010] [Indexed: 02/08/2023]
Abstract
The general and specific properties of pacemaker cells, including Kit-negative cells, that are distributed in gastrointestinal, urethral and uterine smooth muscle tissues, are discussed herein. In intestinal tissues, interstitial cells of Cajal (ICC) are heterogeneous in both their forms and roles. ICC distributed in the myenteric layer (ICC-MY) act as primary pacemaker cells for intestinal mechanical and electrical activity. ICC distributed in muscle bundles play a role as mediators of signals from autonomic nerves to smooth muscle cells. A group of ICC also appears to act as a stretch sensor. Intracellular Ca2+ dynamics play a crucial role in ICC-MY pacemaking; intracellular Ca2+ ([Ca2+](i)) oscillations periodically activate plasmalemmal Ca2+-activated ion channels, such as Ca2+-activated Cl(-) channels and/or non-selective cation channels, although the relative contributions of these channels are not defined. With respect to gut motility, both the ICC network and enteric nervous system, including excitatory and inhibitory enteric neurons, play an essential role in producing highly coordinated peristalsis.
Collapse
Affiliation(s)
- Miyako Takaki
- Department of Physiology II, Nara Medical University, 840 Shijo-cho, Kashihara 634-8521, Japan.
| | | | | |
Collapse
|
33
|
Zhang Y, Carmichael SA, Wang XY, Huizinga JD, Paterson WG. Neurotransmission in lower esophageal sphincter of W/Wv mutant mice. Am J Physiol Gastrointest Liver Physiol 2010; 298:G14-24. [PMID: 19850967 DOI: 10.1152/ajpgi.00266.2009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To address the controversy surrounding the role of interstitial cells of Cajal (ICC) in nitrergic neurotransmission to gastrointestinal smooth muscle, circular smooth muscle from the lower esophageal sphincter (LES) of W/W(v) wild-type and mutant (ICC-deficient) mice were studied by using intracellular and tension recordings in vitro. Resting membrane potential was more negative, and the spontaneous unitary potentials diminished in mutant mice. In wild-type mice, nerve stimulation induced a biphasic inhibitory junction potential (IJP) consisting of a fast initial IJP followed by a long-lasting slow IJP (LSIJP). The IJP was markedly impaired in a significant proportion of mutant mice, whereas in others it was normal. Pharmacological studies in the mice with markedly impaired IJPs revealed that cholinergic and purinergic components of the nerve-mediated responses appeared intact. In wild-type mice, caffeine hyperpolarized smooth muscle cells, inhibited the initial fast IJP, and completely abolished the LSIJP. In mutant mice, caffeine depolarized smooth muscle cells and abolished the impaired LSIJP but did not affect the initial fast IJP. Immunohistochemical staining for c-Kit confirmed deficiency of ICC in mutant mice with a normal nitrergic IJP. Rings of LES circular smooth muscle from W/W(v) mutant mice generated significantly less spontaneous tone than controls. When tone was restored with carbachol, normal nitrergic LES relaxation was recorded. These data suggest that 1) there is significant variability in the generation of nitrergic neurotransmission in the LES of W/W(v) mutant mice, whereas purinergic and cholinergic neurotransmission are intact; 2) the altered nitrergic responses appear to be associated with abnormal Ca2+-dependent signaling initiated by spontaneous Ca2+ release from sarcoplasmic reticulum in smooth muscle cells; and 3) c-Kit-positive ICC are not essential for nitrergic neurotransmission in mouse LES smooth muscle.
Collapse
Affiliation(s)
- Y Zhang
- Division of Gastroenterology, Hotel Dieu Hospital, 166 Brock St., Kingston, Ontario K7L5G2, Canada
| | | | | | | | | |
Collapse
|
34
|
Goyal RK, Chaudhury A. Mounting evidence against the role of ICC in neurotransmission to smooth muscle in the gut. Am J Physiol Gastrointest Liver Physiol 2010; 298:G10-3. [PMID: 19892937 PMCID: PMC2806097 DOI: 10.1152/ajpgi.00426.2009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
How nerves transmit their signals to regulate activity of smooth muscle is of fundamental importance to autonomic and enteric physiology, clinical medicine, and therapeutics. A traditional view of neurotransmission to smooth muscles has been that motor nerve varicosities release neurotransmitters that act on receptors on smooth muscles to cause their contraction or relaxation via electromechanical and pharmacomechanical signaling pathways in the smooth muscle. In recent years, an old hypothesis that certain interstitial cells of Cajal (ICC) may transduce neural signals to smooth muscle cells has been resurrected. This later hypothesis is based on indirect evidence of closer proximity and presence of synapses between the nerve varicosities and ICC, gap junctions between ICC and smooth muscles, and presence of receptors and signaling pathways for the neurotransmitters and ICC. This indirect evidence is at best circumstantial. The direct evidence is based on the reports of loss of neurotransmission in mutant animals lacking ICC due to c-Kit receptor deficiency. However, a critical analysis of the recent data show that animals lacking ICC have normal cholinergic and purinergic neurotransmission and tachykinergic neurotransmission is actually increased. The status of nitrergic neurotransmission in c-Kit deficient animals has been controversial. However, reports suggest that 1) nitrergic neurotransmission in the internal anal sphincter does not require ICC and 2) the in vivo phenotype of ICC deficiency does not resemble nNOS deficiency. 3) The most recent report, in this issue of the Journal, concludes that impaired nitrergic neurotransmission may be due to smooth muscle defects associated with c-Kit receptor deficiency.
Collapse
Affiliation(s)
- Raj K. Goyal
- Center for Swallowing and Motility Disorders, Gastrointestinal Division, Veterans Affairs Boston Healthcare System and Harvard Medical School, Boston, Massachusetts
| | - Arun Chaudhury
- Center for Swallowing and Motility Disorders, Gastrointestinal Division, Veterans Affairs Boston Healthcare System and Harvard Medical School, Boston, Massachusetts
| |
Collapse
|
35
|
Huizinga JD, Zarate N, Farrugia G. Physiology, injury, and recovery of interstitial cells of Cajal: basic and clinical science. Gastroenterology 2009; 137:1548-56. [PMID: 19778538 PMCID: PMC2943431 DOI: 10.1053/j.gastro.2009.09.023] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In the last 15 years, our understanding of the cellular basis of gastrointestinal function has been altered irreversibly by the discovery that normal gastrointestinal motility requires interstitial cells of Cajal (ICC). Research in this relatively short time period has modified our original concept that the core unit that controls motility is made up of nerves and smooth muscle, to one that now includes ICC. This concept has now expanded to beyond the gastrointestinal tract, suggesting that it may be a fundamental property of the regulation of smooth muscle function that requires rhythmic contraction. ICC are distributed throughout the gastrointestinal tract, have important functions in the control of gastrointestinal motility and are often abnormal in diseased states. Recently, significant steps forward have been made in our understanding of the physiology of ICC as well as mechanisms of injury and recovery. These advances will be the focus of this review.
Collapse
Affiliation(s)
- Jan D. Huizinga
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton Canada
| | - Natalia Zarate
- Centre for Academic Surgery, Barts and The London School of Medicine and Dentistry, London UK
| | - Gianrico Farrugia
- Enteric Neuroscience Program, Mayo Clinic College of Medicine, Rochester USA
| |
Collapse
|
36
|
Wang XY, Huizinga JD, Diamond J, Liu LWC. Loss of intramuscular and submuscular interstitial cells of Cajal and associated enteric nerves is related to decreased gastric emptying in streptozotocin-induced diabetes. Neurogastroenterol Motil 2009; 21:1095-e92. [PMID: 19566589 DOI: 10.1111/j.1365-2982.2009.01336.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Interstitial cells of Cajal (ICC) are associated with afferent innervation and peristalsis of the stomach suggestive of a key role in the pathophysiology of gastroparesis. We studied changes in the density and ultrastructure of ICC and enteric nerves in the streptozotocin-induced diabetes mellitus (STZ-DM) in Wistar rats using immunohistochemistry and electron microscopy. Gastric emptying was studied in vivo by single-photon emission computed tomography. In the STZ-DM antrum, a marked reduction was observed in the density of the intramuscular ICC (ICC-IM) and ICC located at the submucosal border of the circular muscle layer of the antrum (ICC-SM). The surviving ICC showed lamellar bodies and partial vacuolation of the cytoplasm content, loss of connections between ICC-IM and nerves; it appeared that injured ICC-IM developed into fibroblast-like ICC. ICC associated with Auerbach's plexus (ICC-AP) in the antrum and ICC in the fundus were not affected significantly except for a loss of connections with nerve structures. Marked reduction in nerve tissue (Protein Gene Product-9.5 positivity) was also restricted to the muscle layers including nitrergic nerves (neuronal nitric oxide synthase positivity). In vivo assessed gastric emptying was markedly reduced in STZ-DM rats. Our data demonstrate in the STZ-DM rat stomach a decreased density of ICC limited to the antrum and to ICC-IM and ICC-SM, and structural degeneration in ICC-IM and associated nerves with a special emphasis on loss of synaptic connections, accompanied by a decrease in gastric emptying. Hence, in this model of gastroparetic diabetes, regional injury to subsets of ICC and nerves are associated with gastric motor dysfunction.
Collapse
Affiliation(s)
- X-Y Wang
- Department of Medicine, McMaster University, Farncombe Family Digestive Health Research Institute, ON, Canada
| | | | | | | |
Collapse
|
37
|
SOFFER E, ABELL T, LIN Z, LORINCZ A, MCCALLUM R, PARKMAN H, POLICKER S, ORDOG T. Review article: gastric electrical stimulation for gastroparesis--physiological foundations, technical aspects and clinical implications. Aliment Pharmacol Ther 2009; 30:681-94. [PMID: 19573170 PMCID: PMC3049171 DOI: 10.1111/j.1365-2036.2009.04082.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Application of electrical stimulation to the gut, primarily the stomach, has rapidly advanced in the last two decades, from mostly animal studies to the clinical arena. Most studies focused on the use of electrical stimulation for gastroparesis, the only approved indication for such intervention. AIM To review the physiological basis of gastric electrical activity and the technical aspects and clinical outcome of gastric electrical stimulation (GES) for gastroparesis. METHODS PubMed search from 1966 to 2009, using gastroparesis and GES as search terms. Areas in focus were systematically reviewed. RESULTS The literature consists of open-label studies, mostly from single centres, published in the last decade. Improvement in symptoms, quality of life and nutritional status was reported by most studies. Physiologically, stimulation parameters approved in clinical practice do not regulate gastric slow wave activity and have inconsistent effect on gastric emptying. The mechanism of action of GES is not fully known, but data support modulation of gastric biomechanical activity and afferent neural mechanisms. CONCLUSIONS Gastric electrical stimulation is a helpful intervention in recalcitrant gastroparesis. Controlled studies and better understanding of mechanisms of action of electrical stimulation are needed to evaluate further the clinical utility of this intervention and to exploit its therapeutic potential better.
Collapse
Affiliation(s)
- E. SOFFER
- Cedars Sinai Medical Center, Los Angeles, CA
| | - T. ABELL
- University of Mississippi, Jackson, MS
| | - Z. LIN
- University of Kansas Medical Center, Kansas City, KS
| | - A. LORINCZ
- Department of Physiology and Biomedical Engineering, Enteric Neuroscience Program and Miles and Shirley Fiterman Center for Digestive Diseases, Mayo Clinic, Rochester, MN
| | - R. MCCALLUM
- University of Kansas Medical Center, Kansas City, KS
| | | | | | - T. ORDOG
- Department of Physiology and Biomedical Engineering, Enteric Neuroscience Program and Miles and Shirley Fiterman Center for Digestive Diseases, Mayo Clinic, Rochester, MN
| |
Collapse
|
38
|
Wang XY, Albertí E, White EJ, Mikkelsen HB, Larsen JO, Jiménez M, Huizinga JD. Igf1r+/CD34+ immature ICC are putative adult progenitor cells, identified ultrastructurally as fibroblast-like ICC in Ws/Ws rat colon. J Cell Mol Med 2009; 13:3528-40. [PMID: 19220583 PMCID: PMC4516506 DOI: 10.1111/j.1582-4934.2009.00689.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 01/23/2009] [Indexed: 02/06/2023] Open
Abstract
The colon of Ws/Ws mutant rats shows impairment of pacemaker activity and altered inhibitory neurotransmission. The present study set out to find structural correlates to these findings to resolve mechanisms. In the colon of Ws/Ws rats, interstitial cells of Cajal associated with Auerbach's plexus (ICC-AP) were significantly decreased and ICC located at the submuscular plexus and intramuscular ICC were rarely observed based on immunohistochemistry and electron microscopy. Ultrastructural investigations revealed that there was no overall loss of all types of interstitial cells combined. Where loss of ICC was observed, a marked increase in fibroblast-like ICC (FL-ICC) was found at the level of AP. Immunoelectron microscopy proved FL-ICC to be c-Kit(-) but gap junction coupled to each other and to c-Kit(+) ICC; they were associated with enteric nerves and occupied space normally occupied by ICC in the wild-type rat colon, suggesting them to be immature ICC. In addition, a marked increase in immunoreactivity for insulin-like growth factor 1 receptor (Igf1r) occurred, co-localized with CD34 but not with c-Kit. A significantly higher number of Igf1r(+)/CD34(+) cells were found in Ws/Ws compared to wild-type rat colons. These CD34(+)/Igf1r(+) cells in the Ws/Ws colon occupied the same space as FL-ICC. Hence we propose that a subset of immature ICC (FL-ICC) consists of adult progenitor cells. Immunohistochemistry revealed a reduction of neurons positive for neuronal nitric oxide synthase. The functional capabilities of the immature ICC and the regenerative capabilities of the adult progenitor cells need further study. The morphological features described here show that the loss of pacemaker activity is not associated with failure to develop a network of interstitial cells around AP but a failure to develop this network into fully functional pacemaker cells. The reduction in nitrergic innervation associated with the Ws mutation may be the result of a reduction in nitrergic neurons.
Collapse
Affiliation(s)
- XY Wang
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster UniversityHamilton, Ontario, Canada
| | - E Albertí
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de BarcelonaBarcelona, Spain
- Centro de Investigación Biomédica en Red de enfermedades hepáticas y Digestivas(CIBERehd)
| | - EJ White
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster UniversityHamilton, Ontario, Canada
| | - HB Mikkelsen
- Department of Cellular and Molecular Medicine, University of Copenhagen, The Panum InstituteCopenhagen, Denmark
| | - JO Larsen
- Department of Neuroscience and Pharmacology, University of Copenhagen, The Panum InstituteCopenhagen, Denmark
| | - M Jiménez
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de BarcelonaBarcelona, Spain
| | - JD Huizinga
- Farncombe Family Digestive Health Research Institute, Department of Medicine, McMaster UniversityHamilton, Ontario, Canada
| |
Collapse
|
39
|
Lammers WJEP, Ver Donck L, Stephen B, Smets D, Schuurkes JAJ. Origin and propagation of the slow wave in the canine stomach: the outlines of a gastric conduction system. Am J Physiol Gastrointest Liver Physiol 2009; 296:G1200-10. [PMID: 19359425 DOI: 10.1152/ajpgi.90581.2008] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Slow waves are known to originate orally in the stomach and to propagate toward the antrum, but the exact location of the pacemaker and the precise pattern of propagation have not yet been studied. Using assemblies of 240 extracellular electrodes, simultaneous recordings of electrical activity were made on the fundus, corpus, and antrum in open abdominal anesthetized dogs. The signals were analyzed off-line, pathways of slow wave propagation were reconstructed, and slow wave velocities and amplitudes were measured. The gastric pacemaker is located in the upper part of the fundus, along the greater curvature. Extracellularly recorded slow waves in the pacemaker area exhibited large amplitudes (1.8 +/- 1.0 mV) and rapid velocities (1.5 +/- 0.9 cm/s), whereas propagation in the remainder of the fundus and in the corpus was slow (0.5 +/- 0.2 cm/s) with low-amplitude waveforms (0.8 +/- 0.5 mV). In the antrum, slow wave propagation was fast (1.5 +/- 0.6 cm/s) with large amplitude deflections (2.0 +/- 1.3 mV). Two areas were identified where slow waves did not propagate, the first in the oral medial fundus and the second distal in the antrum. Finally, recordings from the entire ventral surface revealed the presence of three to five simultaneously propagating slow waves. High resolution mapping of the origin and propagation of the slow wave in the canine stomach revealed areas of high amplitude and rapid velocity, areas with fractionated low amplitude and low velocity, and areas with no propagation; all these components together constitute the elements of a gastric conduction system.
Collapse
Affiliation(s)
- Wim J E P Lammers
- Dept. of Physiology, Faculty of Medicine and Health Sciences, P.O.Box 17666, Al Ain, United Arab Emirates University, United Arab Emirates.
| | | | | | | | | |
Collapse
|
40
|
Iino S, Horiguchi K, Nojyo Y. W(sh)/W(sh) c-Kit mutant mice possess interstitial cells of Cajal in the deep muscular plexus layer of the small intestine. Neurosci Lett 2009; 459:123-6. [PMID: 19427361 DOI: 10.1016/j.neulet.2009.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Revised: 05/01/2009] [Accepted: 05/02/2009] [Indexed: 11/19/2022]
Abstract
The c-Kit receptor tyrosine kinase regulates the development and differentiation of various progenitor cells. W mutant mice with spontaneous mutations in the c-kit gene show various phenotypes such as anemia, infertility, loss of coat color and mast cells. c-Kit also regulates the development of the interstitial cells of Cajal (ICC) that are responsible for the motility regulation of the gastrointestinal musculature. W(sh)/W(sh) mice possess an inversion mutation upstream of the c-kit promoter region; this mutation is responsible for reducing c-Kit activity, leading to a decrease in the number of mast cells, melanocytes, and ICC. We extensively examined the small intestine of W(sh)/W(sh) mice by using immunohistochemistry and electron microscopy. Although the musculature of the W(sh)/W(sh) mice did not show any c-Kit immunoreactivity, there were neurokinin 1 receptor (NK1R)-immunopositive cells that were associated with the nerve fibers in the deep muscular plexus (DMP) region. These NK1R-immunopositive cells showed a bipolar shape with long processes and were identified as ICC in the DMP layer (ICC-DMP). Electron microscopic analysis revealed that ICC-DMP had numerous mitochondria, caveolae, and gap junctions and were closely associated with nerve terminals. In contrast, ICC were not observed at the myenteric layer. In the small intestine of the W(sh)/W(sh) mice, we detected ICC-DMP that showed NK1R immunoreactivity and ultrastructural characters. This type of ICC may develop and maturate structurally without c-Kit expression and regulate gastrointestinal motility.
Collapse
MESH Headings
- Animals
- Caveolae/ultrastructure
- Electrical Synapses/ultrastructure
- Immunohistochemistry
- Intestine, Small/cytology
- Intestine, Small/metabolism
- Intestine, Small/ultrastructure
- Mice
- Mice, Inbred BALB C
- Mice, Mutant Strains
- Microscopy, Electron
- Mitochondria/ultrastructure
- Muscle, Smooth/cytology
- Muscle, Smooth/metabolism
- Muscle, Smooth/ultrastructure
- Mutation
- Neurons/cytology
- Neurons/metabolism
- Neurons/ultrastructure
- Proto-Oncogene Proteins c-kit/genetics
- Proto-Oncogene Proteins c-kit/metabolism
- Receptors, Neurokinin-1/metabolism
Collapse
Affiliation(s)
- Satoshi Iino
- Department of Morphological and Physiological Sciences, University of Fukui, Faculty of Medical Sciences, Matsuoka, Eiheiji, Fukui 910-1193, Japan.
| | | | | |
Collapse
|
41
|
Yin J, Chen JDZ. Roles of interstitial cells of Cajal in regulating gastrointestinal motility: in vitro versus in vivo studies. J Cell Mol Med 2008; 12:1118-29. [PMID: 18429936 PMCID: PMC3865654 DOI: 10.1111/j.1582-4934.2008.00352.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The aim of this article is to provide a better understanding of the roles of interstitial cells of Cajal (ICC) in regulating gastrointestinal motility by reviewing in vitro and in vivo physiological motility studies. Based on the in vitro studies, ICC are proposed to have the following functions: to generate slow waves, to mediate neurotransmission between the enteric nerves and the gastrointestinal muscles and to act as mechanoreceptors. However, there is limited evidence available for these hypotheses from the in vivo motility studies. In this review, we first introduce the major subtypes of ICC and their established functions. Three Kit mutant mouse and rodent models are presented and the loss of ICC subtypes in these mutants is reviewed. The physiological motility findings from various in vitroand in vivo experiments are discussed to give a critical review on the roles of ICC in generating slow waves, regulating gastrointestinal motility, mediating neural transmission and serving as mechanoreceptors. It is concluded that the role of ICC as pacemakers may be well established, but other cells may also be involved in the generation of slow waves; the theory that ICC are mediators of neurotransmission is challenged by the majority of the in vivo motility studies; the hypothesis that ICC are mechanoreceptors has not found supportive evidence from the in vivo studies yet. More studies are needed to explain discrepancies in motility findings between the in vitro and in vivo experiments.
Collapse
Affiliation(s)
- Jieyun Yin
- Division of Gastroenterology, Department of Medicine, University of Texas Medical Branch, Galveston, TX 77555-0632, USA
| | | |
Collapse
|
42
|
Yin J, Chen JDZ. Roles of interstitial cells of Cajal in regulating gastrointestinal motility: in vitro versus in vivo studies. J Cell Mol Med 2008. [PMID: 18429936 DOI: 10.1111/j.1582-4934.2008.00352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The aim of this article is to provide a better understanding of the roles of interstitial cells of Cajal (ICC) in regulating gastrointestinal motility by reviewing in vitro and in vivo physiological motility studies. Based on the in vitro studies, ICC are proposed to have the following functions: to generate slow waves, to mediate neurotransmission between the enteric nerves and the gastrointestinal muscles and to act as mechanoreceptors. However, there is limited evidence available for these hypotheses from the in vivo motility studies. In this review, we first introduce the major subtypes of ICC and their established functions. Three Kit mutant mouse and rodent models are presented and the loss of ICC subtypes in these mutants is reviewed. The physiological motility findings from various in vitro and in vivo experiments are discussed to give a critical review on the roles of ICC in generating slow waves, regulating gastrointestinal motility, mediating neural transmission and serving as mechanoreceptors. It is concluded that the role of ICC as pacemakers may be well established, but other cells may also be involved in the generation of slow waves; the theory that ICC are mediators of neurotransmission is challenged by the majority of the in vivo motility studies; the hypothesis that ICC are mechanoreceptors has not found supportive evidence from the in vivo studies yet. More studies are needed to explain discrepancies in motility findings between the in vitro and in vivo experiments.
Collapse
Affiliation(s)
- Jieyun Yin
- Division of Gastroenterology, Department of Medicine, University of Texas Medical Branch, Galveston, TX 77555-0632, USA
| | | |
Collapse
|
43
|
Huizinga JD, White EJ. Progenitor cells of interstitial cells of Cajal: on the road to tissue repair. Gastroenterology 2008; 134:1252-4. [PMID: 18395104 DOI: 10.1053/j.gastro.2008.02.074] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|