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Sun Y, Sommerville NR, Liu JYH, Ngan MP, Poon D, Ponomarev ED, Lu Z, Kung JSC, Rudd JA. Intra-gastrointestinal amyloid-β1-42 oligomers perturb enteric function and induce Alzheimer's disease pathology. J Physiol 2020; 598:4209-4223. [PMID: 32617993 PMCID: PMC7586845 DOI: 10.1113/jp279919] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 06/12/2020] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS Alzheimer's disease (AD) patients and transgenic mice have beta-amyloid (Aβ) aggregation in the gastrointestinal (GI) tract. It is possible that Aβ from the periphery contributes to the load of Aβ in the brain, as Aβ has prion-like properties. The present investigations demonstrate that Aβ injected into the GI tract of ICR mice is internalised into enteric cholinergic neurons; at 1 month, administration of Aβ into the body of the stomach and the proximal colon was observed to partly redistribute to the fundus and jejunum; at 1 year, vagal and cerebral β-amyloidosis was present, and mice exhibited GI dysfunction and cognitive deficits. These data reveal a previously undiscovered mechanism that potentially contributes to the development of AD. ABSTRACT Alzheimer's disease (AD) is the most common age-related cause of dementia, characterised by extracellular beta-amyloid (Aβ) plaques and intracellular phosphorylated tau tangles in the brain. Aβ deposits have also been observed in the gastrointestinal (GI) tract of AD patients and transgenic mice, with overexpression of amyloid precursor protein. In the present studies, we investigate whether intra-GI administration of Aβ can potentially induce amyloidosis in the central nervous system (CNS) and AD-related pathology such as dementia. We micro-injected Aβ1-42 oligomers (4 μg per site, five sites) or vehicle (saline, 5 μl) into the gastric wall of ICR mice under general anaesthesia. Immunofluorescence staining and in vivo imaging showed that HiLyte Fluor 555-labelled Aβ1-42 had migrated within 3 h via the submucosa to nearby areas and was internalised into cholinergic neurons. At 1 month, HiLyte Fluor 555-labelled Aβ1-42 in the body of the stomach and proximal colon had partly re-distributed to the fundus and jejunum. At 1 year, the jejunum showed functional alterations in neuromuscular coupling (P < 0.001), and Aβ deposits were present in the vagus and brain, with animals exhibiting cognitive impairments in the Y-maze spontaneous alteration test (P < 0.001) and the novel object recognition test (P < 0.001). We found that enteric Aβ oligomers induce an alteration in gastric function, amyloidosis in the CNS, and AD-like dementia via vagal mechanisms. Our results suggest that Aβ load is likely to occur initially in the GI tract and may translocate to the brain, opening the possibility of new strategies for the early diagnosis and prevention of AD.
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Affiliation(s)
| | | | | | | | | | | | | | | | - John A. Rudd
- School of Biomedical Sciences
- Faculty of Medicine the Laboratory Animal Services CentreThe Chinese University of Hong KongNew TerritoriesHong Kong
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Du P, Liu JYH, Sukasem A, Qian A, Calder S, Rudd JA. Recent progress in electrophysiology and motility mapping of the gastrointestinal tract using multi-channel devices. J R Soc N Z 2020. [DOI: 10.1080/03036758.2020.1735455] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Peng Du
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
- Department of Engineering Science, The University of Auckland, Auckland, New Zealand
| | - Julia Y. H. Liu
- Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, People’s Republic of China
| | - Atchariya Sukasem
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Anna Qian
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Stefan Calder
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - John A. Rudd
- Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, People’s Republic of China
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Use of a microelectrode array to record extracellular pacemaker potentials from the gastrointestinal tracts of the ICR mouse and house musk shrew (Suncus murinus). Cell Calcium 2019; 80:175-188. [DOI: 10.1016/j.ceca.2019.05.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/23/2019] [Accepted: 05/08/2019] [Indexed: 12/17/2022]
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Huizinga JD. Recent advances in intestinal smooth muscle research: from muscle strips and single cells, via ICC networks to whole organ physiology and assessment of human gut motor dysfunction. J Smooth Muscle Res 2019; 55:68-80. [PMID: 31956167 PMCID: PMC6962316 DOI: 10.1540/jsmr.55.68] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 11/01/2019] [Indexed: 12/12/2022] Open
Abstract
Gastrointestinal smooth muscle research has evolved from studies on muscle strips to spatiotemporal mapping of whole organ motor and electrical activities. Decades of research on single muscle cells and small sections of isolated musculature from animal models has given us the groundwork for interpretation of human in vivo studies. Human gut motility studies have dramatically improved by high-resolution manometry and high-resolution electrophysiology. The details that emerge from spatiotemporal mapping of high-resolution data are now of such quality that hypotheses can be generated as to the physiology (in healthy subjects) and pathophysiology (in patients) of gastrointestinal (dys) motility. Such interpretation demands understanding of the musculature as a super-network of excitable cells (neurons, smooth muscle cells, other accessory cells) and oscillatory cells (the pacemaker interstitial cells of Cajal), for which mathematical modeling becomes essential. The developing deeper understanding of gastrointestinal motility will bring us soon to a level of precision in diagnosis of dysfunction that is far beyond what is currently available.
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Affiliation(s)
- Jan D. Huizinga
- Department of Medicine-Gastroenterology, McMaster University,
Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute,
Hamilton, Ontario, Canada
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Kaji N, Nakayama S, Horiguchi K, Iino S, Ozaki H, Hori M. Disruption of the pacemaker activity of interstitial cells of Cajal via nitric oxide contributes to postoperative ileus. Neurogastroenterol Motil 2018; 30. [PMID: 29542843 DOI: 10.1111/nmo.13334] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 02/11/2018] [Indexed: 12/21/2022]
Abstract
BACKGROUND Interstitial cells of Cajal (ICC) serve as intestinal pacemakers. Postoperative ileus (POI) is a gastrointestinal motility disorder that occurs following abdominal surgery, which is caused by inflammation-induced dysfunction of smooth muscles and enteric neurons. However, the participation of ICC in POI is not well understood. In this study, we investigated the functional changes of ICC in a mouse model of POI. METHODS Intestinal manipulation (IM) was performed to induce POI. At 24 h or 48 h after IM, the field potential of the intestinal tunica muscularis was investigated. Tissues were also examined by immunohistochemistry and electron microscopic analysis. KEY RESULTS Gastrointestinal transit was significantly decreased with intestinal tunica muscularis inflammation at 24 h after IM, which was ameliorated at 48 h after IM. The generation and propagation of pacemaker potentials were disrupted at 24 h after IM and recovered to the control level at 48 h after IM. ICC networks, detected by c-Kit immunoreactivity, were remarkably disrupted at 24 h after IM. Electron microscopic analysis revealed abnormal vacuoles in the ICC cytoplasm. Interestingly, the ICC networks recovered at 48 h after IM. Administration of aminoguanidine, an inducible nitric oxide synthase inhibitor, suppressed the disruption of ICC networks. Ileal smooth muscle tissue cultured in the presence of nitric oxide donor, showed disrupted ICC networks. CONCLUSIONS AND INFERENCES The generation and propagation of pacemaker potentials by ICC are disrupted via nitric oxide after IM, and this disruption may contribute to POI. When inflammation is ameliorated, ICC can recover their pacemaker function.
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Affiliation(s)
- N Kaji
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - S Nakayama
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - K Horiguchi
- Division of Anatomy and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - S Iino
- Division of Anatomy and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - H Ozaki
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - M Hori
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
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Iwata N, Fujimura T, Takai C, Odani K, Kawano S, Nakayama S. Dialysis membrane-enforced microelectrode array measurement of diverse gut electrical activity. Biosens Bioelectron 2017; 94:312-320. [PMID: 28319897 DOI: 10.1016/j.bios.2017.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/01/2017] [Accepted: 03/04/2017] [Indexed: 12/18/2022]
Abstract
A variety of electrical activities occur depending on the functional state in each section of the gut, but the application of microelectrode array (MEA) is rather limited. We thus developed a dialysis membranes-enforced technique to investigate diverse and complex spatio-temporal electrical activity in the gut. Muscle sheets isolated from the gastrointestinal (GI) tract of mice along with a piece of dialysis membrane were woven over and under the strings to fix them to the anchor rig, and mounted on an 8×8 MEA (inter-electrode distance=150µm). Small molecules (molecular weight <12,000) were exchanged through the membrane, maintaining a physiological environment. Low impedance MEA was used to measure electrical signals in a wide frequency range. We demonstrated the following examples: 1) pacemaker activity-like potentials accompanied by bursting spike-like potentials in the ileum; 2) electrotonic potentials reflecting local neurotransmission in the ileum; 3) myoelectric complex-like potentials consisting of slow and rapid oscillations accompanied by spike potentials in the colon. Despite their limited spatial resolution, these recordings detected transient electric activities that optical probes followed with difficulty. In Addition, propagation of pacemaker-like potential was visualized in the stomach and ileum. These results indicate that the dialysis membrane-enforced technique largely extends the application of MEA, probably due to stabilisation of the access resistance between each sensing electrode and a reference electrode and improvement of electric separation between sensing electrodes. We anticipate that this technique will be utilized to characterise spatio-temporal electrical activities in the gut in health and disease.
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Affiliation(s)
- Naoko Iwata
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Takumi Fujimura
- Department of Pediatric Surgery, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Chiho Takai
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Kei Odani
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Shin Kawano
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Shinsuke Nakayama
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
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Problems with extracellular recording of electrical activity in gastrointestinal muscle. Nat Rev Gastroenterol Hepatol 2016; 13:731-741. [PMID: 27756919 PMCID: PMC8325940 DOI: 10.1038/nrgastro.2016.161] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Motility patterns of the gastrointestinal tract are important for efficient processing of nutrients and waste. Peristalsis and segmentation are based on rhythmic electrical slow waves that generate the phasic contractions fundamental to gastrointestinal motility. Slow waves are generated and propagated actively by interstitial cells of Cajal (ICC), and these events conduct to smooth muscle cells to elicit excitation-contraction coupling. Extracellular electrical recording has been utilized to characterize slow-wave generation and propagation and abnormalities that might be responsible for gastrointestinal motility disorders. Electrode array recording and digital processing are being used to generate data for models of electrical propagation in normal and pathophysiological conditions. Here, we discuss techniques of extracellular recording as applied to gastrointestinal organs and how mechanical artefacts might contaminate these recordings and confound their interpretation. Without rigorous controls for movement, current interpretations of extracellular recordings might ascribe inaccurate behaviours and electrical anomalies to ICC networks and gastrointestinal muscles, bringing into question the findings and validity of models of gastrointestinal electrophysiology developed from these recordings.
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8
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Taniguchi M, Kajioka S, Shozib HB, Sawamura K, Nakayama S. Spatial analysis of slowly oscillating electric activity in the gut of mice using low impedance arrayed microelectrodes. PLoS One 2013; 8:e75235. [PMID: 24124480 PMCID: PMC3790767 DOI: 10.1371/journal.pone.0075235] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 08/13/2013] [Indexed: 01/25/2023] Open
Abstract
Smooth and elaborate gut motility is based on cellular cooperation, including smooth muscle, enteric neurons and special interstitial cells acting as pacemaker cells. Therefore, spatial characterization of electric activity in tissues containing these electric excitable cells is required for a precise understanding of gut motility. Furthermore, tools to evaluate spatial electric activity in a small area would be useful for the investigation of model animals. We thus employed a microelectrode array (MEA) system to simultaneously measure a set of 8×8 field potentials in a square area of ∼1 mm2. The size of each recording electrode was 50×50 µm2, however the surface area was increased by fixing platinum black particles. The impedance of microelectrode was sufficiently low to apply a high-pass filter of 0.1 Hz. Mapping of spectral power, and auto-correlation and cross-correlation parameters characterized the spatial properties of spontaneous electric activity in the ileum of wild-type (WT) and W/Wv mice, the latter serving as a model of impaired network of pacemaking interstitial cells. Namely, electric activities measured varied in both size and cooperativity in W/Wv mice, despite the small area. In the ileum of WT mice, procedures suppressing the excitability of smooth muscle and neurons altered the propagation of spontaneous electric activity, but had little change in the period of oscillations. In conclusion, MEA with low impedance electrodes enables to measure slowly oscillating electric activity, and is useful to evaluate both histological and functional changes in the spatio-temporal property of gut electric activity.
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Affiliation(s)
- Mizuki Taniguchi
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shunichi Kajioka
- Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Habibul B. Shozib
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kenta Sawamura
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shinsuke Nakayama
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
- * E-mail:
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9
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Paskaranandavadivel N, O’Grady G, Du P, Cheng LK. Comparison of filtering methods for extracellular gastric slow wave recordings. Neurogastroenterol Motil 2013; 25:79-83. [PMID: 22974243 PMCID: PMC3535517 DOI: 10.1111/nmo.12012] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Extracellular recordings are used to define gastric slow wave propagation. Signal filtering is a key step in the analysis and interpretation of extracellular slow wave data; however, there is controversy and uncertainty regarding the appropriate filtering settings. This study investigated the effect of various standard filters on the morphology and measurement of extracellular gastric slow waves. METHODS Experimental extracellular gastric slow waves were recorded from the serosal surface of the stomach from pigs and humans. Four digital filters: finite impulse response filter (0.05-1 Hz); Savitzky-Golay filter (0-1.98 Hz); Bessel filter (2-100 Hz); and Butterworth filter (5-100 Hz); were applied on extracellular gastric slow wave signals to compare the changes temporally (morphology of the signal) and spectrally (signals in the frequency domain). KEY RESULTS The extracellular slow wave activity is represented in the frequency domain by a dominant frequency and its associated harmonics in diminishing power. Optimal filters apply cutoff frequencies consistent with the dominant slow wave frequency (3-5 cpm) and main harmonics (up to ≈ 2 Hz). Applying filters with cutoff frequencies above or below the dominant and harmonic frequencies was found to distort or eliminate slow wave signal content. CONCLUSIONS & INFERENCES Investigators must be cognizant of these optimal filtering practices when detecting, analyzing, and interpreting extracellular slow wave recordings. The use of frequency domain analysis is important for identifying the dominant and harmonics of the signal of interest. Capturing the dominant frequency and major harmonics of slow wave is crucial for accurate representation of slow wave activity in the time domain. Standardized filter settings should be determined.
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Affiliation(s)
| | - Gregory O’Grady
- Auckland Bioengineering Institute, The University of Auckland, New Zealand,Department of Surgery, The University of Auckland, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, The University of Auckland, New Zealand
| | - Leo K Cheng
- Auckland Bioengineering Institute, The University of Auckland, New Zealand,Department of Surgery, Vanderbilt University, Nashville, Tennessee, USA
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Bayguinov O, Hennig GW, Sanders KM. Movement based artifacts may contaminate extracellular electrical recordings from GI muscles. Neurogastroenterol Motil 2011; 23:1029-42, e498. [PMID: 21951699 PMCID: PMC4793914 DOI: 10.1111/j.1365-2982.2011.01784.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Electrical slow waves drive peristaltic contractions in the stomach and facilitate gastric emptying. In gastroparesis and other disorders associated with altered gastric emptying, motility defects have been related to altered slow wave frequency and disordered propagation. Experimental and clinical measurements of slow waves are made with extracellular or abdominal surface recording. METHODS We tested the consequences of muscle contractions and movement on biopotentials recorded from murine gastric muscles with array electrodes and pairs of silver electrodes. KEY RESULTS Propagating biopotentials were readily recorded from gastric sheets composed of the entire murine stomach. The biopotentials were completely blocked by nifedipine (2 μmol L(-1) ) that blocked contractile movements and peristaltic contractions. Wortmannin, an inhibitor of myosin light chain kinase, also blocked contractions and biopotentials. Stimulation of muscles with carbachol increased the frequency of biopotentials in control conditions but failed to elicit biopotentials with nifedipine or wortmannin present. Intracellular recording with microelectrodes showed that authentic gastric slow waves occur at a faster frequency typically than biopotentials recorded with extracellular electrodes, and electrical slow waves recorded with intracellular electrodes were unaffected by suppression of movement. Electrical transients, equal in amplitude to biopotentials recorded with extracellular electrodes, were induced by movements produced by small transient stretches (<1 mm) of paralyzed or formalin fixed gastric sheets. CONCLUSIONS & INFERENCES These data demonstrate significant movement artifacts in extracellular recordings of biopotentials from murine gastric muscles and suggest that movement suppression should be an obligatory control when monitoring electrical activity and characterizing propagation and coordination of electrical events with extracellular recording techniques.
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Affiliation(s)
- O Bayguinov
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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Law JKY, Yeung CK, Li L, Rudd JA, Ingebrandt S, Chan M. The Use of SU-8 Topographically Guided Microelectrode Array in Measuring Extracellular Field Potential Propagation. Ann Biomed Eng 2011; 40:619-27. [DOI: 10.1007/s10439-011-0432-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 10/04/2011] [Indexed: 11/29/2022]
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Serotonin augments gut pacemaker activity via 5-HT3 receptors. PLoS One 2011; 6:e24928. [PMID: 21949791 PMCID: PMC3174222 DOI: 10.1371/journal.pone.0024928] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 08/19/2011] [Indexed: 12/21/2022] Open
Abstract
Serotonin (5-hydroxytryptamine: 5-HT) affects numerous functions in the gut, such as secretion, muscle contraction, and enteric nervous activity, and therefore to clarify details of 5-HT's actions leads to good therapeutic strategies for gut functional disorders. The role of interstitial cells of Cajal (ICC), as pacemaker cells, has been recognised relatively recently. We thus investigated 5-HT actions on ICC pacemaker activity. Muscle preparations with myenteric plexus were isolated from the murine ileum. Spatio-temporal measurements of intracellular Ca(2+) and electric activities in ICC were performed by employing fluorescent Ca(2+) imaging and microelectrode array (MEA) systems, respectively. Dihydropyridine (DHP) Ca(2+) antagonists and tetrodotoxin (TTX) were applied to suppress smooth muscle and nerve activities, respectively. 5-HT significantly enhanced spontaneous Ca(2+) oscillations that are considered to underlie electric pacemaker activity in ICC. LY-278584, a 5-HT(3) receptor antagonist suppressed spontaneous Ca(2+) activity in ICC, while 2-methylserotonin (2-Me-5-HT), a 5-HT(3) receptor agonist, restored it. GR113808, a selective antagonist for 5-HT(4), and O-methyl-5-HT (O-Me-5-HT), a non-selective 5-HT receptor agonist lacking affinity for 5-HT(3) receptors, had little effect on ICC Ca(2+) activity. In MEA measurements of ICC electric activity, 5-HT and 2-Me-5-HT caused excitatory effects. RT-PCR and immunostaining confirmed expression of 5-HT(3) receptors in ICC. The results indicate that 5-HT augments ICC pacemaker activity via 5-HT(3) receptors. ICC appear to be a promising target for treatment of functional motility disorders of the gut, for example, irritable bowel syndrome.
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Nakayama S, Atsuta S, Shinmi T, Uchiyama T. Pulse-driven magnetoimpedance sensor detection of biomagnetic fields in musculatures with spontaneous electric activity. Biosens Bioelectron 2011; 27:34-9. [PMID: 21741817 DOI: 10.1016/j.bios.2011.05.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2011] [Revised: 05/26/2011] [Accepted: 05/26/2011] [Indexed: 01/22/2023]
Abstract
We measured biomagnetic fields in musculatures with spontaneous electric activity using a pulse-driven magnetoimpedance (PMI) sensor with the sensitivity improved toward a pico-Tesla (pT) level. Due to the sufficiently short operation interval of 1 μs, this magnetic sensor enabled quasi-real time recordings of the magnetic field for biological electric activity. Isolated small musculatures from the guinea-pig stomach, taenia caeci, portal vein and urinary bladder were incubated in an organ bath at a body temperature. The improved PMI sensor mounted approximately 1mm below the preparations detected oscillatory magnetic fields reflecting spontaneous electric activities of musculature preparations. In the taenia caeci, application of tetraethyl ammonium (TEA), a K(+) channel blocker, significantly enhanced the magnetic activity estimated by histogram analysis. Also, in some musculature preparations, simultaneous measurements with electric activity revealed that the observed magnetic activities were attributed to biological electric activity. PMI technology is promising for applications in biology and medicine.
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Affiliation(s)
- Shinsuke Nakayama
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
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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.
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Affiliation(s)
- Miyako Takaki
- Department of Physiology II, Nara Medical University, 840 Shijo-cho, Kashihara 634-8521, Japan.
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