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Neural signalling of gut mechanosensation in ingestive and digestive processes. Nat Rev Neurosci 2022; 23:135-156. [PMID: 34983992 DOI: 10.1038/s41583-021-00544-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2021] [Indexed: 12/29/2022]
Abstract
Eating and drinking generate sequential mechanosensory signals along the digestive tract. These signals are communicated to the brain for the timely initiation and regulation of diverse ingestive and digestive processes - ranging from appetite control and tactile perception to gut motility, digestive fluid secretion and defecation - that are vital for the proper intake, breakdown and absorption of nutrients and water. Gut mechanosensation has been investigated for over a century as a common pillar of energy, fluid and gastrointestinal homeostasis, and recent discoveries of specific mechanoreceptors, contributing ion channels and the well-defined circuits underlying gut mechanosensation signalling and function have further expanded our understanding of ingestive and digestive processes at the molecular and cellular levels. In this Review, we discuss our current understanding of the generation of mechanosensory signals from the digestive periphery, the neural afferent pathways that relay these signals to the brain and the neural circuit mechanisms that control ingestive and digestive processes, focusing on the four major digestive tract parts: the oral and pharyngeal cavities, oesophagus, stomach and intestines. We also discuss the clinical implications of gut mechanosensation in ingestive and digestive disorders.
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Tran PTH, Lee YH, Bhattarai JP, Park SJ, Yi HK, Han SK. Existence of ATP sensitive potassium currents on human periodontal ligament cells. Arch Oral Biol 2017; 76:48-54. [PMID: 28119170 DOI: 10.1016/j.archoralbio.2017.01.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 01/11/2017] [Accepted: 01/12/2017] [Indexed: 10/20/2022]
Abstract
OBJECTIVE Potassium channels of the ATP-sensitive family (KATP channel) are inhibited by increase in intracellular ATP. Electrophysiological studies have demonstrated that the kinetics and pharmacological properties of KATP channels vary among different tissues, suggesting structurally and functionally distinct types. There are studies showing human periodontal ligament (PDL) cells respond to mechanical stress by increasing ATP release, which participates in bone resorption or bone homeostasis. So, in this study we investigated the existence of KATP channel subunit and their single channel properties in human periodontal ligaments. MATERIALS & METHOD The human PDL cells were isolated from healthy erupted third molar. For patch-clamp experiments, human PDL fibroblasts were seeded on 3.5cm plastic dishes. The inside-out patch clamp recordings were performed under voltage clamp mode. Reverse transcriptase polymerase chain reaction (RT-PCR) was conducted to identify the channel subunits. All pair-wise comparisons were performed by Paired t-test. A P value <0.05 was considered significant. RESULTS We observed mRNA transcripts for Kir6.1, Kir6.2 and Sur2B subuits in the human PDL cells. In inside-out patch mode, the single channel conductance was 163pS at symmetrical K+ concentration of 140mM and inward rectification was seen in ATP-free bath solution. The reversal potential of the currents was found to be 0mV at symmetrical concentration (140mM) of K+ in bath solution. The single channel currents were almost blocked by adding 5mM ATP in the bath solution. However, the currents were not blocked by 100μM glibenclamide, a subunit specific KATP channel blocker. CONCLUSIONS These results indicate that human PDL cells express KATP channels subunit including Sur2B and Kir6.1 and Kir6.2 which are sensitive to ATP but insensitive to glibenclamide.
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Affiliation(s)
- Phuong Thi Huyen Tran
- Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea
| | - Young Hee Lee
- Department of Oral Biochemistry, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea
| | - Janardhan Prasad Bhattarai
- Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea
| | - Soo Joung Park
- Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea
| | - Ho-Keun Yi
- Department of Oral Biochemistry, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea
| | - Seong Kyu Han
- Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea.
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Jin Y, Li J, Wang Y, Ye R, Feng X, Jing Z, Zhao Z. Functional role of mechanosensitive ion channel Piezo1 in human periodontal ligament cells. Angle Orthod 2016; 85:87-94. [PMID: 24810489 DOI: 10.2319/123113-955.1] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
OBJECTIVE To evaluate the function of Piezo1, an evolutionarily conserved mechanically activated channel, in periodontal ligament (PDL) tissue homeostasis under compressive loading. MATERIALS AND METHODS Primary human PDL cells (hPDLCs) were isolated, cultured, and then subjected to 2.0 g/cm(2) static compressive loading for 0.5, 3, 6, and 12 hours, respectively. The expressions of Piezo1 and osteoclastogenesis marker gene were assessed by semiquantitative reverse transcription-polymerase chain reaction. In addition, Piezo1 inhibitor, GsMTx4, was used to block the function of Piezo1, and tumor necrosis factor-α was also used as a positive control. After 12 hours of compressive loading the PDLCs were co-cultured with murine monocytic cell line RAW264.7. Immunofluorescence, western blot, enzyme-linked immunosorbent assay, and tartrate-resistant acid phosphatase staining were also used to test the potency of PDLCs to induce osteoclastogenesis and the activation of nuclear factor (NF)-κB. RESULTS Piezo1, cyclooxygenase-2, receptor activator of NF-κB ligand, and prostaglandin E2 were significantly upregulated under static compressive stimuli. GsMTx4 repressed osteoclastogenesis in the mechanical stress-pretreated PDLCs-RAW264.7 co-culture system. Furthermore, NF-κB signaling pathway was involved in the mechanical stress-induced osteoclastogenesis. CONCLUSIONS Piezo1 exerts a transduction role in mechanical stress-induced osteoclastogenesis in hPDLCs.
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Affiliation(s)
- Ying Jin
- a PhD Candidate, Department of Orthodontics, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, West China School of Stomatology, Sichuan University, China
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Son GY, Yang YM, Park WS, Chang I, Shin DM. Hypotonic stress induces RANKL via transient receptor potential melastatin 3 (TRPM3) and vaniloid 4 (TRPV4) in human PDL cells. J Dent Res 2015; 94:473-81. [PMID: 25595364 DOI: 10.1177/0022034514567196] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Bone remodeling occurs in response to various types of mechanical stress. The periodontal ligament (PDL) plays an important role in mechanical stress-mediated alveolar bone remodeling. However, the underlying mechanism at the cellular level has not been extensively studied. In this study, we investigated the effect of shear stress on the expression of bone remodeling factors, including receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL) and osteoprotegerin (OPG), as well as its upstream signaling pathway in primary human PDL cells. We applied hypotonic stress to reproduce shear stress to PDL cells. Hypotonic stress induced the messenger RNA (mRNA) and protein expression of RANKL but not OPG. It also increased intracellular Ca(2+) concentration ([Ca(2+)]i). Extracellular Ca(2+) depletion and nonspecific plasma membrane Ca(2+) channel blockers completely inhibited the increase in both [Ca(2+)]i and RANKL mRNA expression. We identified the expression and activation of transient receptor potential melastatin 3 (TRPM3) and vaniloid 4 (TRPV4) channels in PDL cells. Pregnenolone sulfate (PS) and 4α-phorbol 12, 13-didecanoate (4α-PDD), which are agonists of TRPM3 and TRPV4, augmented Ca(2+) influx and RANKL mRNA expression. Both pharmacological (2-aminoethoxydiphenyl borate [2-APB], ruthenium red [RR], ononetin [Ono], and HC 067047 [HC]) and genetic (small interfering RNA [siRNA]) inhibitors of TRPM3 and TRPV4 reduced the hypotonic stress-mediated increase in [Ca(2+)]i and RANKL mRNA expression. Our study shows that hypotonic stress induced RANKL mRNA expression via TRPM3- and TRPV4-mediated extracellular Ca(2+) influx and RANKL expression. This signaling pathway in PDL cells may play a critical role in mechanical stress-mediated alveolar bone remodeling.
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Affiliation(s)
- G Y Son
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Korea BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Korea
| | - Y M Yang
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Korea
| | - W S Park
- Department of Advanced General Dentistry, Yonsei University College of Dentistry, Seoul, Korea
| | - I Chang
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Korea
| | - D M Shin
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Korea BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Korea
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Lu L, Wang W, Peng Y, Li J, Wang L, Wang X. Electrophysiology and pharmacology of tandem domain potassium channel TREK-1 related BDNF synthesis in rat astrocytes. Naunyn Schmiedebergs Arch Pharmacol 2014; 387:303-12. [PMID: 24402080 DOI: 10.1007/s00210-013-0952-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/18/2013] [Indexed: 01/06/2023]
Abstract
In the present study, the functional properties and pharmacology of two-pore domain potassium channel (K2P) TREK-1 in primary cultured rat brain astrocytes were investigated. Western blot, patch clamping techniques, and ELISA were used to detect the distribution and function of TREK-1 as well as the expression of brain-derived neurotrophic factor (BDNF) on the primary cultured astrocytes. It was shown that TREK-1 protein expressed in astrocytes was 2.4-fold higher than it was expressed in microglia. Single channel recording via patch clamping showed that the TREK-1 outward currents in astrocytes could be activated by arachidonic acid (AA) or chloroform with the conductance of 113 ± 14 and 120 ± 13 pS, respectively. The current was also sensitive to mechanical stretch and intracellular acidification. Negative pressure (-30 cm H2O) and acidification of intracellular solution (pH 6.8 or 6.3) both enhanced TREK-1 channel open probability significantly. Further pharmacological studies showed that TREK-1 antagonist penfluridol inhibited AA-induced currents, and both penfluridol and methionine (TREK-1 blockers) significantly increased BDNF level in astrocytes by 50 %. These results indicated that TREK-1 channel current was a major component of K2P currents in astrocytes. TREK-1 channels might play important roles in regulating the function of astrocytes and might be used as a drug target for neuroprotection.
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Affiliation(s)
- Li Lu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Xiannongtan Street, Xicheng District, Beijing, 100050, China
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Heyman NS, Cowles CL, Barnett SD, Wu YY, Cullison C, Singer CA, Leblanc N, Buxton ILO. TREK-1 currents in smooth muscle cells from pregnant human myometrium. Am J Physiol Cell Physiol 2013; 305:C632-42. [PMID: 23804201 PMCID: PMC3761174 DOI: 10.1152/ajpcell.00324.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 06/24/2013] [Indexed: 01/05/2023]
Abstract
The mechanisms governing maintenance of quiescence during pregnancy remain largely unknown. The current study characterizes a stretch-activated, tetraethylammonium-insensitive K(+) current in smooth muscle cells isolated from pregnant human myometrium. This study hypothesizes that these K(+) currents can be attributed to TREK-1 and that upregulation of this channel during pregnancy assists with the maintenance of a negative cell membrane potential, conceivably contributing to uterine quiescence until full term. The results of this study demonstrate that, in pregnant human myometrial cells, outward currents at 80 mV increased from 4.8 ± 1.5 to 19.4 ± 7.5 pA/pF and from 3.0 ± 0.8 to 11.8 ± 2.7 pA/pF with application of arachidonic acid (AA) and NaHCO3, respectively, causing intracellular acidification. Similarly, outward currents were inhibited following application of 10 μM fluphenazine by 51.2 ± 9.8% after activation by AA and by 73.9 ± 4.2% after activation by NaHCO3. In human embryonic kidney (HEK-293) cells stably expressing TREK-1, outward currents at 80 mV increased from 91.0 ± 23.8 to 247.5 ± 73.3 pA/pF and from 34.8 ± 8.9 to 218.6 ± 45.0 pA/pF with application of AA and NaHCO3, respectively. Correspondingly, outward currents were inhibited 89.5 ± 2.3% by 10 μM fluphenazine following activation by AA and by 91.6 ± 3.4% following activation by NaHCO3. Moreover, currents in human myometrial cells were activated by stretch and were reduced by transfection with small interfering RNA or extracellular acidification. Understanding gestational regulation of expression and gating of TREK-1 channels could be important in determining appropriate maintenance of uterine quiescence during pregnancy.
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Affiliation(s)
- Nathanael S Heyman
- Department of Pharmacology, Center for Molecular Medicine, University of Nevada School of Medicine, Reno, Nevada
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Yamamoto T, Ohara A, Nishikawa M, Yamamoto G, Saeki Y. Dexamethasone-induced up-regulation of two-pore domain K+ channel genes, TASK-1 and TWIK-2, in cultured human periodontal ligament fibroblasts. In Vitro Cell Dev Biol Anim 2011; 47:273-9. [PMID: 21359819 DOI: 10.1007/s11626-011-9388-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 01/26/2011] [Indexed: 12/25/2022]
Abstract
Two-pore domain K(+) channels are widely expressed in many types of cells, and have various important functions, especially maintaining the resting membrane potential. In the previous report, we have confirmed the presence of several kinds of two-pore domain K(+) channels in the periodontal ligament (PDL) fibroblasts. It is well known that dexamethasone (Dex) regulates the functions of various kinds of ion channels. In this work, we investigate if Dex affects the gene expressions of the two-pore domain K(+) channels in the PDL fibroblasts. We also examined the effects of other steroid hormones on the K(+) channels gene expression. The mRNA levels of two-pore domain K(+) channels in human PDL fibroblasts were examined in the presence or absence of Dex by RT-PCR. The effects of other steroid hormones (aldosterone, estrogen, 1α,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)], and retinoic acid) were also examined. Dex significantly induced the expression of TASK-1 and TWIK-2 in mRNA levels in both a dose- and a time-dependent manner. The stimulatory effects of Dex were completely abolished by a glucocorticoid receptor antagonist. 1,25-(OH)(2)D(3) also increased the TASK-1 mRNA levels but had no effect on TWIK-2 expression. Dex, one of the potent glucocorticoid, probably have a protective role against external stimuli by maintaining the membrane potential of PDL fibroblasts through the up-regulation of TASK-1 and TWIK-2 K(+) channels.
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Affiliation(s)
- Takahiro Yamamoto
- Department of Oral and Maxillofacial Surgery, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
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Saeki Y, Ohara A, Nishikawa M, Yamamoto T, Yamamoto G. The presence of arachidonic acid-activated K+ channel, TREK-1, in human periodontal ligament fibroblasts. Drug Metab Rev 2007; 39:457-65. [PMID: 17786632 DOI: 10.1080/03602530701498786] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Human periodontal ligament (PDL) fibroblasts expressed following two-pore-domain K(+) channels, TWIK-2 > TREK-1 > TWIK-1 >> TASK-1 > TRAAK > TASK-2. TREK-2 message was not detectable. We found the presence of arachidonic acid-activated and mechanical stress-sensitive K(+) channel, TREK-1, in the PDL fibroblasts by patch-clamp technique. It was also found the significant increase of intracellular concentration of arachidonic acid upon the application of cyclic stretch. Therefore, we suppose that the mechanical stretch due to the mastication activates phospholipase A(2) to release arachidonic acid (AA) from membrane, then, the released AA activates TREK-1. Thus, TREK-1 K(+) channels may play a protective role to maintain the negative membrane potential of PDL fibroblasts against the environmental stimuli.
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Affiliation(s)
- Yukikazu Saeki
- Department of Basic Science for Health and Nursing, Shiga University of Medical Science, Ohtsu, Shiga, Japan.
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