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Yan L, Tang Q, Quan X, Ren H, Chen W, Xia H, Luo H. Effects of exendin-4 on colonic motility in rats and its underlying mechanism. Neurogastroenterol Motil 2019; 31:e13482. [PMID: 30303298 DOI: 10.1111/nmo.13482] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 09/01/2018] [Accepted: 09/04/2018] [Indexed: 01/17/2023]
Abstract
BACKGROUND Glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) agonists modulate gastrointestinal motility; however, the effects of GLP-1R agonists on colonic motility are still controversial, and the molecular mechanism is unclear. Exendin-4 shares 53% homology with GLP-1 and is a full agonist of GLP-1R. In this study, our aims were to explore the role and mechanism of exendin-4 in isolated rat colonic tissues and cells. METHODS An organ bath system was used to examine the spontaneous contractions of smooth muscle strips. The whole-cell patch-clamp technique was used to investigate the currents of L-type voltage-dependent calcium channels and large conductance Ca2+ -activated K+ (BKCa ) channels in smooth muscle cells. KEY RESULTS Exendin-4 decreased both the amplitude and frequency of spontaneous contractions of smooth muscle strips in a concentration-dependent manner. The inhibitory effect was completely blocked by exendin-4(9-39), a GLP-1R antagonist. Moreover, this effect was partially abolished by tetrodotoxin (TTX), a blocker of neuronal voltage-dependent Na+ channels, Nω-Nitro-l-arginine (L-NNA), a nitric oxide synthase (NOS) inhibitor, apamin, an inhibitor of small-conductance Ca2+ -activated K+ (SK) channels. Whole-cell patch-clamp recordings revealed that exendin-4 inhibited the peak current of L-type calcium channels in colonic smooth muscle cells, but did not change the shape of the current-voltage (I-V) curves. The steady-state activation and steady-state inactivation of L-type calcium channels were not affected. Likewise, BKCa currents were significantly inhibited by exendin-4. CONCLUSIONS Exendin-4 indirectly inhibits colonic muscle activity via a nitrergic and a purinergic neural pathway through NO and ATP release and inhibits L-type voltage-dependent calcium channels and BKCa channels in smooth muscle cells.
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Affiliation(s)
- Lin Yan
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Qincai Tang
- Department of Pathology, China Three Gorges University College of Medicine, Yichang, China
| | - Xiaojing Quan
- Department of Gastroenterology, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Haixia Ren
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Wei Chen
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Hong Xia
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China.,Department of Gastroenterology, Renmin Hospital of Wuhan University, Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China
| | - Hesheng Luo
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China
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Jia M, Lu X, Wang Z, Zhao L, Zhang S. Effects of Fengliao-Changweikang in Diarrhea-predominant Irritable Bowel Syndrome Rats and Its Mechanism Involving Colonic Motility. J Neurogastroenterol Motil 2018; 24:479-489. [PMID: 29715711 PMCID: PMC6034674 DOI: 10.5056/jnm17093] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 10/21/2017] [Accepted: 11/20/2017] [Indexed: 12/13/2022] Open
Abstract
Background/Aims This study was designed to investigate the effect of Fengliao-Changweikang (FLCWK) in diarrhea-predominant irritable bowel syndrome (IBS-D) rats and explore its underlying mechanisms. Methods IBS-D model rats were induced by neonatal maternal separation (NMS) combined with restraint stress (RS). In in vivo experiments, the model rats were randomly divided into 5 groups: NMS + RS, FLCWK (low dose, middle dose, and high dose), and pinaverium bromide. The normal control (no handling) rats were classified as the NH group. The therapeutic effect of FLCWK was evaluated by fecal characteristics, electromyographic response and abdominal withdrawal reflex scores. In in vitro experiments, the model rats were randomly divided into 2 groups: NMS + RS, FLCWK (middle dose), and no handling rats were used as the NH group. The differences in basic tension and ACh-induced tension of isolated colonic longitudinal smooth muscle strips (CLSMs) among the 3 groups were observed. In addition, different inhibitors (nifedipine, TMB-8, L-NAME, methylene blue, and 4-AP) were pretreated to explore the underlying mechanisms. Results In in vivo experiments, fecal characteristics, electromyographic response, and abdominal withdrawal reflex scores significantly improved in the FLCWK group, compared with the NMS + RS group. In in vitro experiments, the basic tension and ACh-induced tension of CLSMs in IBS-D rats were significantly inhibited by FLCWK. After pre-treatment with different inhibitors, the ACh-induced tension of CLSMs in each group showed no significant difference. Conclusions FLCWK manifested curative effect in IBS-D rats by inhibiting colonic contraction. The underlying mechanisms may be related to regulatory pathway of nitric oxide/cGMP/Ca2+ and specific potassium channels.
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Affiliation(s)
- Mengdi Jia
- Digestive Disease Center, Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, Beijing, China
| | - Xiaofang Lu
- Digestive Disease Center, Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, Beijing, China
| | - Zhengfang Wang
- Digestive Disease Center, Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, Beijing, China
| | - Luqing Zhao
- Digestive Disease Center, Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, Beijing, China
| | - Shengsheng Zhang
- Digestive Disease Center, Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, Beijing, China
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Yefimenko OY, Savchenko YO, Falalyeyeva TM, Beregova TV, Zholobak NM, Spivak MY, Shcherbakov OB, Bubnov RV. Nanocrystalline cerium dioxide efficacy for gastrointestinal motility: potential for prokinetic treatment and prevention in elderly. EPMA J 2015; 6:6. [PMID: 25815090 PMCID: PMC4374531 DOI: 10.1186/s13167-015-0029-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/18/2015] [Indexed: 12/13/2022]
Abstract
BACKGROUND Constipation is a common condition, with prevalence after 65 years, is a major colorectal cancer risk factor. Recent works have demonstrated advances in personalized, preventive nanomedicine, leading to the construction of new materials and nanodrugs, in particular, nanocrystalline cerium dioxide (NCD), having strong antioxidative prebiotic effect. The aim of our study was to investigate the influence of NCD on motor function of the stomach and colon in vivo and contractive activity of smooth muscles in different year-old rats. METHODS We included 80 rats: 3- (weight 130-160 g, n = 40) and 24-month old (weight 390-450 g, n = 40), divided into four groups as follows: І-control group; rats of II-ІV groups were injected intragastrically one injection per day during 10 days, 3 ml of water 3 ml/kg stabilizing solution, аnd 1 mmol/ml NCD, respectively. In all animals, we recorded spontaneous and carbachol-stimulated (0.01 mg/kg) gastrointestinal tract motor activity. We used the index of motor activity (IMA), expressed in cmH2O, for characterization of the motor function. We investigated smooth muscle contraction by tenzometric method, studied the spontaneous and stimulated motility by ballonographic method. RESULTS IMA reduced by 21.1 + 0.2% (p < 0.01) in the old rats of the control group compared with the young rats. A 10-day administration of NCD increased IMA in the stomach of young rats by 9.3% (р < 0.001) vs the control group. The exposure of NCD increased the amplitude of contraction to 34.2 ± 5.4 mN (n = 10) in the stomach of old rats and increased by 32.1 ± 2.4% vs the control group (p < 0.05). NCD did not influence acetylcholine (ACh) contractions in the stomach of young rats; however, in the stomach of old rats, V nr increased by 90 ± 15.2% (р < 0.001). CONCLUSIONS The index of motor activity is decreased in old rats. Nanocrystalline cerium dioxide increased the index of motor activity in all groups of rats and also evoked a significant increase of colon contractions in old rats.
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Affiliation(s)
- Olena Yu Yefimenko
- />Taras Shevchenko National University of Kyiv, Volodymyrska Str., 64/13, 01601 Kyiv, Ukraine
| | - Yuliya O Savchenko
- />Taras Shevchenko National University of Kyiv, Volodymyrska Str., 64/13, 01601 Kyiv, Ukraine
| | - Tetyana M Falalyeyeva
- />Taras Shevchenko National University of Kyiv, Volodymyrska Str., 64/13, 01601 Kyiv, Ukraine
| | - Tetyana V Beregova
- />Taras Shevchenko National University of Kyiv, Volodymyrska Str., 64/13, 01601 Kyiv, Ukraine
| | - Nadiya M Zholobak
- />Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Zabolotny Str., 154, 03680 Kyiv, Ukraine
| | - Mykola Ya Spivak
- />Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Zabolotny Str., 154, 03680 Kyiv, Ukraine
- />LCL ‘DIAPROF’, Svitlycky Str., 35, 04123 Kyiv, Ukraine
| | - Oleksandr B Shcherbakov
- />Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Zabolotny Str., 154, 03680 Kyiv, Ukraine
| | - Rostyslav V Bubnov
- />Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Zabolotny Str., 154, 03680 Kyiv, Ukraine
- />Clinical Hospital ‘Pheophania’ of State Affairs Department, Zabolotny Str., 21, 03680 Kyiv, Ukraine
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Abstract
The present review is an attempt to put into perspective the available information on the putative changes in cellular mechanisms of the contractile properties of the aging gastrointestinal (GI) smooth muscle. Information on smooth muscle of the GI tract is scanty. Smooth muscle cells from old rats (32 months old) exhibit limited cell length distribution and diminished contractility. The observed reduced contractile response may be due to the effect of aging on signal transduction pathways, especially an inhibition of the tyrosine kinase-Src kinase pathway, a reduced activation of the PKCalpha pathway, a reduced association of contractile proteins (HSP27-tropomyosin, HSP27-actin, and actin-myosin). Levels of HSP27-phosphorylation are also reduced compared to adult rats. Regulation of GI motility is a complex mechanism of signal transduction and interaction of signaling and contractile proteins. It is suggested that further studies to elucidate the role of HSP27 in aging smooth muscle of the GI tract are needed.
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Affiliation(s)
- Khalil N Bitar
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, MI 48109, USA.
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Bitar KN. Aging and neural control of the GI tract: V. Aging and gastrointestinal smooth muscle: from signal transduction to contractile proteins. Am J Physiol Gastrointest Liver Physiol 2003; 284:G1-7. [PMID: 12488230 DOI: 10.1152/ajpgi.00264.2002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The object of this theme is to offer new perspectives on the effect of aging on signal-transduction pathways associated with agonist-induced contraction of smooth muscle cells from the colon. Smooth muscle cells from old rats (32 mo old) exhibit limited cell length distribution and diminished contractility. The observed reduced contractile response may be due to the effect of aging on signal-transduction pathways, especially an inhibition of the tyrosine kinase-Src kinase pathway, a reduced activation of the PKC pathway, and a reduced association of contractile proteins [heat shock protein 27 (HSP27)-tropomyosin, HSP27-actin, actin-myosin]. Levels of HSP27 phosphorylation are also reduced compared with adult rats.
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Affiliation(s)
- Khalil N Bitar
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor 48109-0656, USA.
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Camilleri M, Lee JS, Viramontes B, Bharucha AE, Tangalos EG. Insights into the pathophysiology and mechanisms of constipation, irritable bowel syndrome, and diverticulosis in older people. J Am Geriatr Soc 2000; 48:1142-50. [PMID: 10983917 DOI: 10.1111/j.1532-5415.2000.tb04793.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVES To review the epidemiology, pathophysiology and mechanisms of irritable bowel syndrome (IBS), constipation, and diverticulosis, for the purpose of addressing these three common conditions in older adults (>65 years of age). DESIGN Using a MEDLINE search, we identified original English language journal articles and reviews from 1965 to December 1998. We also selected articles published before 1965 or after 1998 that were cross-referenced or pertinent to the topics researched. RESULTS The prevalence of constipation and diverticulosis is higher in older than in younger adults. Significant risk factors for constipation in older women are failure of the anorectal angle to open or excessive perineal descent, which represent disturbances of pelvic floor function and rectal evacuation. In contrast, the prevalence of IBS is no greater than in younger adults. Nevertheless, these syndromes impact on the patient's functional status and quality of life. The mechanisms resulting in these gastrointestinal syndromes are unclear. Uncoordinated colonic activity and colonic segmentation may lead to IBS and diverticulosis, respectively, and these pathophysiological findings suggest disorders of inhibitory control of neuromuscular function. The total number of neurons in the myenteric plexus is decreased, and collagen deposited in the distal colon is increased with aging in humans. Animal studies suggest that senescent colonic muscle responds less to excitatory factors in vitro, and neural injury in older animals may result from apoptosis, defects of mitochondrial metabolism, and inadequate levels or response to neurotrophins. Future investigations will reveal whether similar mechanisms underlie human disease. Currently, treatment is aimed at relief of symptoms of IBS or constipation or dealing with the complications of diverticulosis. CONCLUSIONS Constipation, IBS, and diverticulosis are common problems of aging. There is a need for further systematic research of the basic mechanisms in neuromuscular dysfunction with aging, including the studies of physical characteristics of the colonic wall, pelvic floor function (particularly in women with excessive perineal descent), and neurohormonal control of motility and sensation. Insights on the pathophysiology and mechanisms of neural injury may lead to more specific treatments in the future, e.g., serotonergic agents and neurotrophins. Meanwhile, collaborations between primary care physicians, geriatricians, and gastroenterologists can optimize management of these three common conditions that significantly impact the quality of life of older adults.
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Affiliation(s)
- M Camilleri
- Gastroenterology Research Unit, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA
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Abstract
1. Electromechanical coupling in smooth muscle serves to coordinate the contractile activity of the syncytium. Electrical activity of smooth muscle of the gut is generated by ionic conductances that regulate and in turn are regulated by the membrane potential of smooth muscle cells. This activity determines the extent of Ca2+ entry into smooth muscle cells, and thus, the timing and intensity of contractions. 2. Potassium channels play an important role in regulating the excitability of the syncytium. The different types of K+ channel are characterized by different sensitivities to membrane potential, to intracellular Ca2+ levels and to modulation by agonists. 3. This review highlights the different types of K+ channels found in gut smooth muscle and describes their possible roles in regulating the electrical activity of the muscle.
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Affiliation(s)
- F Vogalis
- Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria, Australia
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Properties, regulation, and role of potassium channels of smooth muscle. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1569-2590(00)08010-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
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Bolton TB, Prestwich SA, Zholos AV, Gordienko DV. Excitation-contraction coupling in gastrointestinal and other smooth muscles. Annu Rev Physiol 1999; 61:85-115. [PMID: 10099683 DOI: 10.1146/annurev.physiol.61.1.85] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The main contributors to increases in [Ca2+]i and tension are the entry of Ca2+ through voltage-dependent channels opened by depolarization or during action potential (AP) or slow-wave discharge, and Ca2+ release from store sites in the cell by the action of IP3 or by Ca(2+)-induced Ca(2+)-release (CICR). The entry of Ca2+ during an AP triggers CICR from up to 20 or more subplasmalemmal store sites (seen as hot spots, using fluorescent indicators); Ca2+ waves then spread from these hot spots, which results in a rise in [Ca2+]i throughout the cell. Spontaneous transient releases of store Ca2+, previously detected as spontaneous transient outward currents (STOCs), are seen as sparks when fluorescent indicators are used. Sparks occur at certain preferred locations--frequent discharge sites (FDSs)--and these and hot spots may represent aggregations of sarcoplasmic reticulum scattered throughout the cytoplasm. Activation of receptors for excitatory signal molecules generally depolarizes the cell while it increases the production of IP3 (causing calcium store release) and diacylglycerols (which activate protein kinases). Activation of receptors for inhibitory signal molecules increases the activity of protein kinases through increases in cAMP or cGMP and often hyperpolarizes the cell. Other receptors link to tyrosine kinases, which trigger signal cascades interacting with trimeric G-protein systems.
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Affiliation(s)
- T B Bolton
- Department of Pharmacology and Clinical Pharmacology, St George's Hospital Medical School, London, United Kingdom.
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Abstract
Ion channels are the unitary elements that underlie electrical activity of gastrointestinal smooth muscle cells and of interstitial cells of Cajal. The result of ion channel activity in the gastrointestinal smooth muscle layers is a rhythmic change in membrane potential that in turn underlies events leading to organized motility patterns. Gastrointestinal smooth muscle cells and interstitial cells of Cajal express a wide variety of ion channels that are tightly regulated. This review summarizes 20 years of data obtained from patch-clamp studies on gastrointestinal smooth muscle cells and interstitial cells, with a focus on regulation.
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Affiliation(s)
- G Farrugia
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota 55905, USA.
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