1
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Doms S, Fokt H, Rühlemann MC, Chung CJ, Kuenstner A, Ibrahim SM, Franke A, Turner LM, Baines JF. Key features of the genetic architecture and evolution of host-microbe interactions revealed by high-resolution genetic mapping of the mucosa-associated gut microbiome in hybrid mice. eLife 2022; 11:75419. [PMID: 35866635 PMCID: PMC9307277 DOI: 10.7554/elife.75419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 06/14/2022] [Indexed: 12/13/2022] Open
Abstract
Determining the forces that shape diversity in host-associated bacterial communities is critical to understanding the evolution and maintenance of metaorganisms. To gain deeper understanding of the role of host genetics in shaping gut microbial traits, we employed a powerful genetic mapping approach using inbred lines derived from the hybrid zone of two incipient house mouse species. Furthermore, we uniquely performed our analysis on microbial traits measured at the gut mucosal interface, which is in more direct contact with host cells and the immune system. Several mucosa-associated bacterial taxa have high heritability estimates, and interestingly, 16S rRNA transcript-based heritability estimates are positively correlated with cospeciation rate estimates. Genome-wide association mapping identifies 428 loci influencing 120 taxa, with narrow genomic intervals pinpointing promising candidate genes and pathways. Importantly, we identified an enrichment of candidate genes associated with several human diseases, including inflammatory bowel disease, and functional categories including innate immunity and G-protein-coupled receptors. These results highlight key features of the genetic architecture of mammalian host-microbe interactions and how they diverge as new species form. The digestive system, particularly the large intestine, hosts many types of bacteria which together form the gut microbiome. The exact makeup of different bacterial species is specific to an individual, but microbiomes are often more similar between related individuals, and more generally, across related species. Whether this is because individuals share similar environments or similar genetic backgrounds remains unclear. These two factors can be disentangled by breeding different animal lineages – which have different genetic backgrounds while belonging to the same species – and then raising the progeny in the same environment. To investigate this question, Doms et al. studied the genes and microbiomes of mice resulting from breeding strains from multiple locations in a natural hybrid zone between different subspecies. The experiments showed that 428 genetic regions affected the makeup of the microbiome, many of which were known to be associated with human diseases. Further analysis revealed 79 genes that were particularly interesting, as they were involved in recognition and communication with bacteria. These results show how the influence of the host genome on microbiome composition becomes more specialized as animals evolve. Overall, the work by Doms et al. helps to pinpoint the genes that impact the microbiome; this knowledge could be helpful to examine how these interactions contribute to the emergence of conditions such as diabetes or inflammatory bowel disease, which are linked to perturbations in gut bacteria.
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Affiliation(s)
- Shauni Doms
- Max Planck Institute for Evolutionary Biology, Plön, Germany.,Section of Evolutionary Medicine, Institute for Experimental Medicine, Kiel University, Kiel, Germany
| | - Hanna Fokt
- Max Planck Institute for Evolutionary Biology, Plön, Germany.,Section of Evolutionary Medicine, Institute for Experimental Medicine, Kiel University, Kiel, Germany
| | - Malte Christoph Rühlemann
- Institute for Clinical Molecular Biology (IKMB), Kiel University, Kiel, Germany.,Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany
| | - Cecilia J Chung
- Max Planck Institute for Evolutionary Biology, Plön, Germany.,Section of Evolutionary Medicine, Institute for Experimental Medicine, Kiel University, Kiel, Germany
| | - Axel Kuenstner
- Institute of Experimental Dermatology, University of Lübeck, Lübeck, Germany
| | - Saleh M Ibrahim
- Institute of Experimental Dermatology, University of Lübeck, Lübeck, Germany.,Sharjah Institute of Medical Research, Sharjah, United Arab Emirates
| | - Andre Franke
- Institute for Clinical Molecular Biology (IKMB), Kiel University, Kiel, Germany
| | - Leslie M Turner
- Milner Centre for Evolution, Department of Biology & Biochemistry, University of Bath, Bath, United Kingdom
| | - John F Baines
- Max Planck Institute for Evolutionary Biology, Plön, Germany.,Section of Evolutionary Medicine, Institute for Experimental Medicine, Kiel University, Kiel, Germany
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2
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Tanahashi Y, Komori S, Matsuyama H, Kitazawa T, Unno T. Functions of Muscarinic Receptor Subtypes in Gastrointestinal Smooth Muscle: A Review of Studies with Receptor-Knockout Mice. Int J Mol Sci 2021; 22:E926. [PMID: 33477687 PMCID: PMC7831928 DOI: 10.3390/ijms22020926] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/12/2021] [Accepted: 01/14/2021] [Indexed: 01/25/2023] Open
Abstract
Parasympathetic signalling via muscarinic acetylcholine receptors (mAChRs) regulates gastrointestinal smooth muscle function. In most instances, the mAChR population in smooth muscle consists mainly of M2 and M3 subtypes in a roughly 80% to 20% mixture. Stimulation of these mAChRs triggers a complex array of biochemical and electrical events in the cell via associated G proteins, leading to smooth muscle contraction and facilitating gastrointestinal motility. Major signalling events induced by mAChRs include adenylyl cyclase inhibition, phosphoinositide hydrolysis, intracellular Ca2+ mobilisation, myofilament Ca2+ sensitisation, generation of non-selective cationic and chloride currents, K+ current modulation, inhibition or potentiation of voltage-dependent Ca2+ currents and membrane depolarisation. A lack of ligands with a high degree of receptor subtype selectivity and the frequent contribution of multiple receptor subtypes to responses in the same cell type have hampered studies on the signal transduction mechanisms and functions of individual mAChR subtypes. Therefore, novel strategies such as genetic manipulation are required to elucidate both the contributions of specific AChR subtypes to smooth muscle function and the underlying molecular mechanisms. In this article, we review recent studies on muscarinic function in gastrointestinal smooth muscle using mAChR subtype-knockout mice.
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Affiliation(s)
- Yasuyuki Tanahashi
- Department of Advanced Life Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan;
| | - Seiichi Komori
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; (S.K.); (H.M.)
| | - Hayato Matsuyama
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; (S.K.); (H.M.)
| | - Takio Kitazawa
- Department of Veterinary Science, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan;
| | - Toshihiro Unno
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; (S.K.); (H.M.)
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3
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Tanahashi Y, Katsurada T, Inasaki N, Uchiyama M, Sakamoto T, Yamamoto M, Matsuyama H, Komori S, Unno T. Further characterization of the synergistic activation mechanism of cationic channels by M 2 and M 3 muscarinic receptors in mouse intestinal smooth muscle cells. Am J Physiol Cell Physiol 2019; 318:C514-C523. [PMID: 31875697 DOI: 10.1152/ajpcell.00277.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In mouse ileal myocytes, muscarinic receptor-mediated cationic current (mIcat) occurs mainly through synergism of M2 and M3 subtypes involving Gi/o-type GTP-binding proteins and phospholipase C (PLC). We have further studied the M2/M3 synergistic pathway. Carbachol-induced mIcat was markedly depressed by YM-254890, a Gq/11 protein inhibitor. However, the mIcat was unaffected by heparin, calphostin C, or chelerythrine, suggesting that mIcat activation does not involve signaling molecules downstream of phosphatidylinositol 4,5-bisphosphate (PIP2) breakdown. M2-knockout (KO) mice displayed a reduced mIcat (~10% of wild-type mIcat) because of the lack of M2-Gi/o signaling. The impaired mIcat was insensitive to neuropeptide Y possessing a Gi/o-stimulating activity. M3-KO mice also displayed a reduced mIcat (~6% of wild-type mIcat) because of the lack of M3-Gq/11 signaling, and the mIcat was insensitive to prostaglandin F2α possessing a Gq/11-stimulating activity. These results suggest the importance of Gq/11/PLC-hydrolyzed PIP2 breakdown itself in mIcat activation and also support the idea that the M2/M3 synergistic pathway represents a signaling complex consisting of M2-Gi/o and M3-Gq/11-PLC systems in which both G proteins are special for this pathway but not general in receptor coupling.
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Affiliation(s)
- Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| | - Taisuke Katsurada
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Noriko Inasaki
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Mai Uchiyama
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Takashi Sakamoto
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Masayuki Yamamoto
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Hayato Matsuyama
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Seiichi Komori
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
| | - Toshihiro Unno
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, Gifu, Japan
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4
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Metformin acutely lowers blood glucose levels by inhibition of intestinal glucose transport. Sci Rep 2019; 9:6156. [PMID: 30992489 PMCID: PMC6468119 DOI: 10.1038/s41598-019-42531-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 04/02/2019] [Indexed: 12/22/2022] Open
Abstract
Metformin is currently the most prescribed drug for treatment of type 2 diabetes mellitus in humans. It has been well established that long-term treatment with metformin improves glucose tolerance in mice by inhibiting hepatic gluconeogenesis. Interestingly, a single dose of orally administered metformin acutely lowers blood glucose levels, however, little is known about the mechanism involved in this effect. Glucose tolerance, as assessed by the glucose tolerance test, was improved in response to prior oral metformin administration when compared to vehicle-treated mice, irrespective of whether the animals were fed either the standard or high-fat diet. Blood glucose-lowering effects of acutely administered metformin were also observed in mice lacking functional AMP-activated protein kinase, and were independent of glucagon-like-peptide-1 or N-methyl-D-aspartate receptors signaling. [18F]-FDG/PET revealed a slower intestinal transit of labeled glucose after metformin as compared to vehicle administration. Finally, metformin in a dose-dependent but indirect manner decreased glucose transport from the intestinal lumen into the blood, which was observed ex vivo as well as in vivo. Our results support the view that the inhibition of transepithelial glucose transport in the intestine is responsible for lowering blood glucose levels during an early response to oral administration of metformin.
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5
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Alom F, Matsuyama H, Nagano H, Fujikawa S, Tanahashi Y, Unno T. Involvement of transient receptor potential melastatin 4 channels in the resting membrane potential setting and cholinergic contractile responses in mouse detrusor and ileal smooth muscles. J Vet Med Sci 2019; 81:217-228. [PMID: 30518701 PMCID: PMC6395210 DOI: 10.1292/jvms.18-0631] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Here, we investigated the effects of 9-hydroxyphenanthrene (9-phenanthrol), a potent and selective transient receptor potential melastatin 4 (TRPM4) channel blocker, on the resting membrane potential and cholinergic contractile responses to elucidate the functional role of TRPM4 channels in the contractile activities of mouse detrusor and ileal longitudinal smooth muscles. We observed that, 9-phenanthrol (3-30 µM) did not significantly inhibit high K+-induced contractions in both preparations; however, 9-phenanthrol (10 µM) strongly inhibited cholinergic contractions evoked by electrical field stimulation in detrusor preparations compared to inhibitions in ileal preparations. 9-Phenanthrol (10 µM) significantly inhibited the muscarinic agonist, carbachol-induced contractile responses and slowed the maximum upstroke velocities of the contraction in detrusor preparations. However, the agent (10 µM) did not inhibit the contractions due to intracellular Ca2+ release evoked by carbachol, suggesting that the inhibitory effect of 9-phenanthrol may primarily be due to the inhibition of the membrane depolarization process incurred by TRPM4 channels. On the other hand, 9-phenanthrol (10 µM) did not affect carbachol-induced contractile responses in ileal preparations. Further, 9-phenanthrol (10 µM) significantly hyperpolarized the resting membrane potential and decreased the basal tone in both detrusor and ileal muscle preparations. Taken together, our results suggest that TRPM4 channels are constitutively active and are involved in setting of the resting membrane potential, thereby regulating the basal tone in detrusor and ileal smooth muscles. Thus, TRPM4 channels play a significant role in cholinergic signaling in detrusor, but not ileal, smooth muscles.
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Affiliation(s)
- Firoj Alom
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hayato Matsuyama
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.,Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hiroshi Nagano
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Saki Fujikawa
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Toshihiro Unno
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.,Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
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6
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Wang B, Murakami Y, Ono M, Fujikawa S, Matsuyama H, Unno T, Naitou K, Tanahashi Y. Muscarinic suppression of ATP-sensitive K + channels mediated by the M 3/G q/11/phospholipase C pathway contributes to mouse ileal smooth muscle contractions. Am J Physiol Gastrointest Liver Physiol 2018; 315:G618-G630. [PMID: 30001145 DOI: 10.1152/ajpgi.00069.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
ATP-sensitive K+ (KATP) channels are expressed in gastrointestinal smooth muscles, and their activity is regulated by muscarinic receptor stimulation. However, the physiological significance and mechanisms of muscarinic regulation of KATP channels are not fully understood. We examined the effects of the KATP channel opener cromakalim and the KATP channel blocker glibenclamide on electrical activity of single mouse ileal myocytes and on mechanical activity in ileal segment preparations. To explore muscarinic regulation of KATP channel activity and its underlying mechanisms, the effect of carbachol (CCh) on cromakalim-induced KATP channel currents ( IKATP) was studied in myocytes of M2 or M3 muscarinic receptor-knockout (KO) and wild-type (WT) mice. Cromakalim (10 µM) induced membrane hyperpolarization in single myocytes and relaxation in segment preparations from WT mice, whereas glibenclamide (10 µM) caused membrane depolarization and contraction. CCh (100 µM) induced sustained suppression of IKATP in cells from both WT and M2KO mice. However, CCh had a minimal effect on IKATP in M3KO and M2/M3 double-KO cells. The Gq/11 inhibitor YM-254890 (10 μM) and PLC inhibitor U73122 (1 μM), but not the PKC inhibitor calphostin C (1 μM), markedly decreased CCh-induced suppression of IKATP in WT cells. These results indicated that KATP channels are constitutively active and contribute to the setting of resting membrane potential in mouse ileal smooth muscles. M3 receptors inhibit the activity of these channels via a Gq/11/PLC-dependent but PKC-independent pathways, thereby contributing to membrane depolarization and contraction of smooth muscles. NEW & NOTEWORTHY We systematically investigated the regulation of ATP-sensitive K+ channels by muscarinic receptors expressed on mouse ileal smooth muscles. We found that M3 receptors inhibit the activity of ATP-sensitive K+ channels via a Gq/11/PLC-dependent, but PKC-independent, pathway. This muscarinic suppression of ATP-sensitive K+ channels contributes to membrane depolarization and contraction of smooth muscles.
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Affiliation(s)
- Ban Wang
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University , Kyoto , Japan
| | - Yuri Murakami
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University , Kyoto , Japan
| | - Maiki Ono
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University , Kyoto , Japan
| | - Saki Fujikawa
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University , Kyoto , Japan
| | - Hayato Matsuyama
- Laboratory of Pharmacology, Department of Veterinary Medicine, Gifu University , Gifu , Japan
| | - Toshihiro Unno
- Laboratory of Pharmacology, Department of Veterinary Medicine, Gifu University , Gifu , Japan
| | - Kiyotada Naitou
- Department of Basic Veterinary Science, Joint Faculty of Veterinary Medicine, Kagoshima University , Kagoshima , Japan
| | - Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University , Kyoto , Japan
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7
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Alom F, Miyakawa M, Matsuyama H, Nagano H, Tanahashi Y, Unno T. Possible antagonistic effects of the TRPC4 channel blocker ML204 on M 2 and M 3 muscarinic receptors in mouse ileal and detrusor smooth muscles and atrial myocardium. J Vet Med Sci 2018; 80:1407-1415. [PMID: 29973432 PMCID: PMC6160885 DOI: 10.1292/jvms.18-0197] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ML204, a potent transient receptor potential canonical 4 (TRPC4) channel blocker, is often used to elucidate the involvement of TRPC4 channels in receptor-operated signaling processes in
visceral smooth muscles. In the present study, we investigated the possible antagonistic actions of ML204 on M2 and M3 muscarinic receptors, which mediate contractions
in mouse ileal and detrusor smooth muscles. In ileal and detrusor smooth muscle preparations, ML204 (3 or 10 µM) significantly inhibited electrical field stimulation
(EFS)-evoked cholinergic contractions. However, it did not significantly inhibit high K+-induced and EFS-evoked non-cholinergic contractions in the ileal preparations. When the
muscarinic agonist, carbachol was cumulatively applied, ML204 (1, 3 and 10 µM) caused a rightward parallel shift of the concentration-response curves of carbachol.
Additionally, ML204 (1, 3 and 10 µM) inhibited carbachol-induced negative chronotropic response in atrial preparations, which is mediated by M2 muscarinic
receptors. Furthermore, ML204 significantly inhibited the contractions evoked by carbachol-induced intracellular Ca2+ release, which is mediated by M3 muscarinic
receptors. These results suggested that ML204 might exhibit antagonistic actions on M2 and M3 muscarinic receptors; in addition, the inhibitory effects of ML204 against
EFS-induced cholinergic contractions might be attributed to this receptor antagonism rather than inhibition of TRPC4 channel activity. Therefore, these effects should be considered when
ML204 is used as a TRPC4 channel blocker.
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Affiliation(s)
- Firoj Alom
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Masumi Miyakawa
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hayato Matsuyama
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hiroshi Nagano
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Toshihiro Unno
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
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8
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McLean LP, Smith A, Cheung L, Urban JF, Sun R, Grinchuk V, Desai N, Zhao A, Raufman JP, Shea-Donohue T. Type 3 muscarinic receptors contribute to intestinal mucosal homeostasis and clearance of Nippostrongylus brasiliensis through induction of TH2 cytokines. Am J Physiol Gastrointest Liver Physiol 2016; 311:G130-41. [PMID: 27173511 PMCID: PMC4967171 DOI: 10.1152/ajpgi.00461.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/06/2016] [Indexed: 01/31/2023]
Abstract
Despite increased appreciation for the role of nicotinic receptors in the modulation of and response to inflammation, the contribution of muscarinic receptors to mucosal homeostasis, clearance of enteric pathogens, and modulation of immune cell function remains relatively undefined. Uninfected and Nippostrongylus brasiliensis-infected wild-type and type 3 muscarinic receptor (M3R)-deficient (Chrm3(-/-)) mice were studied to determine the contribution of M3R to mucosal homeostasis as well as host defense against the TH2-eliciting enteric nematode N. brasiliensis Intestinal permeability and expression of TH1/TH17 cytokines were increased in uninfected Chrm3(-/-) small intestine. Notably, in Chrm3(-/-) mice infected with N. brasiliensis, small intestinal upregulation of TH2 cytokines was attenuated and nematode clearance was delayed. In Chrm3(-/-) mice, TH2-dependent changes in small intestinal function including smooth muscle hypercontractility, increased epithelial permeability, decreased epithelial secretion and absorption, and goblet cell expansion were absent despite N. brasiliensis infection. These findings identify an important role for M3R in host defense and clearance of N. brasiliensis, and support the expanding role of cholinergic muscarinic receptors in maintaining mucosal homeostasis.
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MESH Headings
- Animals
- Cells, Cultured
- Cytokines/immunology
- Cytokines/metabolism
- Disease Models, Animal
- Genetic Predisposition to Disease
- Homeostasis
- Host-Pathogen Interactions
- Immunity, Mucosal
- Intestinal Mucosa/immunology
- Intestinal Mucosa/metabolism
- Intestinal Mucosa/parasitology
- Intestine, Small/immunology
- Intestine, Small/metabolism
- Intestine, Small/parasitology
- Macrophage Activation
- Macrophages/immunology
- Macrophages/metabolism
- Macrophages/parasitology
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Nippostrongylus/immunology
- Nippostrongylus/pathogenicity
- Phenotype
- Receptor, Muscarinic M3/deficiency
- Receptor, Muscarinic M3/genetics
- Receptor, Muscarinic M3/metabolism
- Strongylida Infections/genetics
- Strongylida Infections/immunology
- Strongylida Infections/metabolism
- Strongylida Infections/parasitology
- Th2 Cells/immunology
- Th2 Cells/metabolism
- Th2 Cells/parasitology
- Time Factors
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Affiliation(s)
- Leon P McLean
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Allen Smith
- Diet, Genomics, and Immunology Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland; and
| | - Lumei Cheung
- Diet, Genomics, and Immunology Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland; and
| | - Joseph F Urban
- Diet, Genomics, and Immunology Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland; and
| | - Rex Sun
- Division of Translational Radiation Sciences, Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Viktoriya Grinchuk
- Division of Translational Radiation Sciences, Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Neemesh Desai
- Division of Translational Radiation Sciences, Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Aiping Zhao
- Division of Translational Radiation Sciences, Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jean-Pierre Raufman
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Terez Shea-Donohue
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland; Division of Translational Radiation Sciences, Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
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9
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Tanahashi Y, Wang B, Murakami Y, Unno T, Matsuyama H, Nagano H, Komori S. Inhibitory effects of SKF96365 on the activities of K(+) channels in mouse small intestinal smooth muscle cells. J Vet Med Sci 2015; 78:203-11. [PMID: 26498720 PMCID: PMC4785108 DOI: 10.1292/jvms.15-0346] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In order to investigate the effects of SKF96365 (SKF), which is a non-selective cationic channel blocker, on
K+ channel currents, we recorded currents through ATP sensitive K+ (IKATP),
voltage-gated K+ (IKv) and Ca2+ activated K+ channels
(IBK) in the absence and presence of SKF in single small intestinal myocytes of mice with
patch-clamp techniques. SKF (10 µM) reversibly abolished IKATP that was induced by
cromakalim (10 µM), which is a selective ATP sensitive K+ channel opener. These
inhibitory effects were induced in a concentration-dependent and voltage-independent manner. The 50%
inhibitory concentration (IC50) was 0.85 µM, which was obviously lower than that
reported for the muscarinic cationic current. In addition, SKF (1 µM ≈ the IC50
value in IKATP suppression) reversibly inhibited the IKv that was induced by repetitive
depolarizing pulses from −80 to 20 mV. However, the extent of the inhibitory effects was only ~30%. In
contrast, SKF (1 µM) had no significant effects on spontaneous transient IBK and
caffeine-induced IBK. These results indicated that SKF inhibited ATP sensitive K+
channels and voltage-gated K+ channels, with the ATP sensitive K+ channels being more
sensitive than the voltage-gated K+ channels. These inhibitory effects on K+ channels
should be considered when SKF is used as a cationic channel blocker.
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Affiliation(s)
- Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto 603-8555, Japan
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10
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Vasconcelos LHC, Correia ACDC, de Souza ILL, Silva MDCC, Paredes-Gamero EJ, Santos BVDO, Cavalcante FDA, da Silva BA. Flavonoid galetin 3,6-dimethyl ether attenuates guinea pig ileum contraction through K(+) channel activation and decrease in cytosolic calcium concentration. Eur J Pharmacol 2015; 767:52-60. [PMID: 26452514 DOI: 10.1016/j.ejphar.2015.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 09/23/2015] [Accepted: 10/02/2015] [Indexed: 11/27/2022]
Abstract
Flavonoid galetin 3,6-dimethyl ether (FGAL) has been isolated from the aerial parts of Piptadenia stipulaceae and has shown a spasmolytic effect in guinea pig ileum. Thus, we aimed to characterize its relaxant mechanism of action. FGAL exhibited a higher relaxant effect on ileum pre-contracted by histamine (EC50=1.9±0.4×10(-7) M) than by KCl (EC50=2.6±0.5×10(-6) M) or carbachol (EC50=1.8±0.4×10(-6) M). The flavonoid inhibited the cumulative contractions to histamine, as well as to CaCl2 in depolarizing medium nominally Ca(2+)-free. The flavonoid relaxed the ileum pre-contracted by S-(-)-Bay K8644 (EC50=9.5±1.9×10(-6) M) but less potently pre-contracted by KCl or histamine. CsCl attenuated the relaxant effect of FGAL (EC50=1.1±0.3×10(-6) M), but apamin or tetraethylammonium (1mM) had no effect (EC50=2.6±0.2×10(-7) and 1.6±0.3×10(-7) M, respectively), ruling out the involvement of small and big conductance Ca(2+)-activated K(+) channels (SKCa and BKCa, respectively). Either 4-aminopyridine or glibenclamide attenuated the relaxant effect of FGAL (EC50=1.8±0.2×10(-6) and 1.5±0.5×10(-6) M, respectively), indicating the involvement of voltage- and ATP-sensitive K(+) channels (KV and KATP, respectively). FGAL did not alter the viability of intestinal myocytes in the MTT assay and decreased (88%) Fluo-4 fluorescence, indicating a decrease in cytosolic Ca(2+) concentration. Therefore, the relaxant mechanism of FGAL involves pseudo-irreversible noncompetitive antagonism of histaminergic receptors, KV and KATP activation and blockade of CaV1, thus leading to a reduction in cytosolic Ca(2+) levels.
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Affiliation(s)
- Luiz H C Vasconcelos
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, Campus I, 58051-970 João Pessoa, Paraíba, Brazil
| | - Ana C de C Correia
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, Campus I, 58051-970 João Pessoa, Paraíba, Brazil
| | - Iara L L de Souza
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, Campus I, 58051-970 João Pessoa, Paraíba, Brazil
| | - Maria da C C Silva
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, Campus I, 58051-970 João Pessoa, Paraíba, Brazil
| | - Edgar J Paredes-Gamero
- Departamento de Biofísca, Universidade Federal de São Paulo, 04021-001 São Paulo, São Paulo, Brazil
| | - Bárbara V de O Santos
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, Campus I, 58051-970 João Pessoa, Paraíba, Brazil; Departamento de Ciências Farmacêuticas, Universidade Federal da Paraíba, Campus I, 58051-900 João Pessoa, Paraíba, Brazil
| | - Fabiana de A Cavalcante
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, Campus I, 58051-970 João Pessoa, Paraíba, Brazil; Departamento de Fisiologia e Patologia, Universidade Federal da Paraíba, Campus I, 58051-900 João Pessoa, Paraíba, Brazil.
| | - Bagnólia A da Silva
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, Campus I, 58051-970 João Pessoa, Paraíba, Brazil; Departamento de Ciências Farmacêuticas, Universidade Federal da Paraíba, Campus I, 58051-900 João Pessoa, Paraíba, Brazil
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11
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Souza ILLD, Correia ACDC, Araujo LCDC, Vasconcelos LHC, Silva MDCC, Costa VCDO, Tavares JF, Paredes-Gamero EJ, Cavalcante FDA, Silva BAD. Essential oil from Xylopia frutescens Aubl. reduces cytosolic calcium levels on guinea pig ileum: mechanism underlying its spasmolytic potential. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 15:327. [PMID: 26376723 PMCID: PMC4573295 DOI: 10.1186/s12906-015-0849-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 09/03/2015] [Indexed: 11/10/2022]
Abstract
BACKGROUND Xylopia frutescens Aubl. (embira, semente-de-embira or embira-vermelha), is used in folk medicine as antidiarrheal. The essential oil from its leaves (XF-EO) has been found to cause smooth muscle relaxation. Thus, the aim of this study was to investigate the spasmolytic action by which XF-EO acts on guinea pig ileum. METHODS The components of the XF-EO were identified by gas chromatography-mass spectrometry. Segments of guinea pig ileum were suspended in organ bath containing modified Krebs solution at 37 °C, bubbled with carbogen mixture under a resting tension of 1 g. Isotonic contractions were registered using kymographs and isometric contractions using force transducer coupled to an amplifier and computer. Fluorescence measurements were obtained with a microplate reader using Fluo-4. RESULTS Forty-three constituents were identified in XF-EO, mostly mono- and sesquiterpenes. XF-EO has been found to cause relaxation on guinea pig ileum. The essential oil inhibited in a concentration-dependent manner both CCh- and histamine-induced phasic contractions, being more potent on histamine-induced contractions as well as antagonized histamine-induced cumulative contractions in a non-competitive antagonism profile. XF-EO relaxed in a concentration-dependent manner the ileum pre-contracted with KCl and histamine. Since the potency was smaller in organ pre-contracted with KCl, it was hypothesized that XF-OE would be acting as a K(+) channel positive modulator. In the presence of CsCl (non-selective K(+) channel blocker), the relaxant potency of XF-OE was not altered, indicating a non-participation of these channels. Moreover, XF-EO inhibited CaCl2-induced cumulative contractions in a depolarizing medium nominally without Ca(2+) and relaxed the ileum pre-contracted with S-(-)-Bay K8644 in a concentration-dependent manner, thus, was confirmed the inhibition of Ca(2+) influx through Cav1 by XF-EO. In cellular experiments, the viability of longitudinal layer myocytes from guinea pig ileum was not altered in the presence of XF-OE and the Fluo-4-associated fluorescence intensity in these intestinal myocytes stimulated by histamine was reduced by the essential oil, indicating a [Ca(2+)]c reduction. CONCLUSION Spasmolytic action mechanism of XF-EO on guinea pig ileum can involve histaminergic receptor antagonism and Ca(2+) influx blockade, which results in [Ca(2+)]c reduction leading to smooth muscle relaxation.
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Affiliation(s)
| | | | | | | | | | | | - Josean Fechine Tavares
- Centro de Ciências da Saúde/Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil.
- Instituto de Pesquisa em Fármacos e Medicamentos/Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil.
| | | | - Fabiana de Andrade Cavalcante
- Centro de Ciências da Saúde/Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil.
- Instituto de Pesquisa em Fármacos e Medicamentos/Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil.
- Universidade Federal da Paraíba, Centro de Ciências da Saúde/Pós-Graduação em Produtos Naturais e Sintéticos Bioativos/Laboratório de Farmacologia Funcional Prof. George Thomas, Cidade, Universitária, P.O. Box 5009, 58051-970, João Pessoa, Paraíba, Brazil.
| | - Bagnólia Araújo da Silva
- Centro de Ciências da Saúde/Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil.
- Instituto de Pesquisa em Fármacos e Medicamentos/Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil.
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Tanahashi Y, Ichimura Y, Kimura K, Matsuyama H, Iino S, Komori S, Unno T. Cholinergic neuromuscular transmission mediated by interstitial cells of Cajal in the myenteric layer in mouse ileal longitudinal smooth muscles. Naunyn Schmiedebergs Arch Pharmacol 2013; 387:377-88. [PMID: 24322587 DOI: 10.1007/s00210-013-0944-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 11/21/2013] [Indexed: 01/15/2023]
Abstract
To elucidate the roles played by the interstitial cells of Cajal in the myenteric layer (ICC-MY) in cholinergic neuromuscular transmission, we recorded mechanical and electrical activities in response to electrical field stimulation (EFS) of the ileal longitudinal muscle strips from WBB6F1-W/W(V) (W/W(V)) mutant mice, that lacked ICC-MY and compared with those in WBB6F1-+/+ (+/+) control mice. In +/+ muscle strips, EFS induced phasic contractions, which were abolished or strongly attenuated by atropine or tetrodotoxin. In W/W(V) preparations, EFS induced similar phasic contractions, but the cholinergic component was smaller than that in +/+ strips. This was despite of the fact that the contractions because of exogenous applications of carbachol and high K(+) solution in W/W(V) strips were comparable to or rather greater than those in the +/+ preparations. EFS induced atropine-sensitive excitatory junction potentials (EJPs) in the +/+ longitudinal smooth muscle cells but not in W/W(V) cells. In the presence of eserine, EFS induced atropine-sensitive EJPs in W/W(V) cells. These results suggest that ICC-MY mediate the cholinergic neuromuscular transmission in mouse ileal longitudinal smooth muscles. In addition, the other pathway in which ICC-MY are not involved can operate concomitantly.
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Affiliation(s)
- Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto, 603-8555, Japan,
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Tanahashi Y, Waki N, Unno T, Matsuyama H, Iino S, Kitazawa T, Yamada M, Komori S. Roles of M2 and M3 muscarinic receptors in the generation of rhythmic motor activity in mouse small intestine. Neurogastroenterol Motil 2013; 25:e687-97. [PMID: 23889852 DOI: 10.1111/nmo.12194] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 06/26/2013] [Indexed: 02/08/2023]
Abstract
BACKGROUND The roles of M2 and M3 muscarinic receptor subtypes in the regulation of gut motor activity were investigated. METHODS We simultaneously recorded changes in the intraluminal pressure (IP) and longitudinal tension (LT) in small intestinal segments from M2 or M3 receptor knockout (KO) and wild-type (WT) mice. KEY RESULTS In the WT preparations, luminal distension induced a continuous rhythmic contractile activity that was characterized by synchronous rises in IP and LT, occurring periodically at a constant interval. Tetrodotoxin completely abolished the response, whereas atropine either abolished or attenuated it. In the majority of the M2 KO preparations, however, no rhythmic activity was observed in response to the luminal distention, even though networks of enteric neurons and interstitial cells of Cajal (ICC) seemed to be intact. Where rhythmic activity did occur in M2 KO preparations, it was atropine resistant. In the M3 KO preparations, the IP and LT were synchronously changed by the luminal distention, but the changes occurred at irregular intervals. The W/W(v) mutant preparations, which lack ICC in the myenteric plexus (ICC-MY), showed results similar to those of the M3 KO preparations. In some of the M2 /M3 double-KO preparations, rhythmic activity was not observed, but in the others, an atropine-resistant rhythmicity appeared. CONCLUSIONS & INFERENCES These results suggest that M2 and M3 muscarinic receptors differentially regulate the intestinal motor activity: M2 receptors play an essential role in the generation of rhythmic motor activity, and M3 receptors have a modulatory role in controlling the periodicity of the rhythmic activity together with the ICC-MY.
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Affiliation(s)
- Y Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
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Santos RF, Martins IRR, Monteiro FDS, Travassos RDA, Janebro DI, Tavares JF, Silva MS, da Silva BA. Spasmolytic activity of trachylobanes ent-7α-acetoxytrachyloban-18-oic acid and ent-7α-hydroxytrachyloban-18-oic acid isolated from Xylopia langsdorfiana A. St-Hil. & Tul. (Annonaceae). Nat Prod Res 2012; 26:2335-9. [PMID: 22288518 DOI: 10.1080/14786419.2011.653974] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
We aimed to investigate the possible spasmolytic activity of ent-7α-acetoxytrachyloban-18-oic acid (1) and ent-7α-hydroxytrachyloban-18-oic acid (2) on smooth muscle models. In male rat aorta and rat uterus, both diterpenes were unable to trigger spasmolytic action. However, 2 relaxed guinea-pig trachea: Compounds 1 and 2 antagonised, significantly and concentration-dependently, carbachol- and histamine-induced phasic contractions in guinea-pig ileum. Moreover, they induced a significant and concentration-dependent relaxation in pre-contracted (KCl, carbachol or histamine) guinea-pig ileum, with 2 being 15 times more potent than 1 in histamine-contracted ileum. These dissimilar results may be due to chemical differences between them. Thus, we demonstrated that 1 and 2 seem to be promising spasmolytic agents, although further studies are required to elucidate the spasmolytic action mechanism.
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Affiliation(s)
- Rosimeire F Santos
- Laboratório de Tecnologia Farmacêutica Prof. Delby Fernandes de Medeiros, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
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Abstract
Schizophrenia is a devastating disease with several broad symptom clusters and the current monoamine-based treatments do not adequately treat the disease, especially negative and cognitive symptoms. A proposed alternative approach for treating schizophrenia is through the use of compounds that activate certain muscarinic receptor subtypes, the so-called muscarinic cholinergic hypothesis theory. This theory has been revitalized with a number of recent and provocative findings including postmortem reports in schizophrenia patients showing decreased numbers of muscarinic M(1) and M(4) receptors in brain regions associated with schizophrenia as well as decreased muscarinic receptors in an in vivo imaging study. Studies with M(4) knockout mice have shown that there is a reciprocal relationship between M(4) and dopamine receptor function, and a number of muscarinic agonists have shown antidopaminergic activity in a variety of preclinical assays predictive of antipsychotic efficacy in the clinic. Furthermore, the M(1)/M(4) preferring partial agonist xanomeline has been shown to have antipsychotic-like and pro-cognitive activity in preclinical models and in clinical trials to decrease psychotic-like behaviors in Alzheimer's patients and positive, negative, and cognitive symptoms in patients with schizophrenia. Therefore, we propose that an agonist with M(1) and M(4) interactions would effectively treat core symptom clusters associated with schizophrenia. Currently, research is focused on developing subtype-selective muscarinic agonists and positive allosteric modulators that have reduced propensity for parasympathetic side-effects, but retain the therapeutic benefit observed with their less selective predecessors.
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Affiliation(s)
- David L McKinzie
- Lilly Research Laboratories, Eli Lilly and Co., Indianapolis, IN 46285, USA.
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Santos RF, Martins IRR, Travassos RA, Tavares JF, Silva MS, Paredes-Gamero EJ, Ferreira AT, Nouailhetas VLA, Aboulafia J, Rigoni VLS, da Silva BA. Ent-7α-acetoxytrachyloban-18-oic acid and ent-7α-hydroxytrachyloban-18-oic acid from Xylopia langsdorfiana A. St-Hil. & Tul. modulate K(+) and Ca(2+) channels to reduce cytosolic calcium concentration on guinea pig ileum. Eur J Pharmacol 2011; 678:39-47. [PMID: 22214536 DOI: 10.1016/j.ejphar.2011.12.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 12/15/2011] [Accepted: 12/17/2011] [Indexed: 10/14/2022]
Abstract
In this study we investigated the mechanism underlying the spasmolytic action of ent-7α-acetoxytrachyloban-18-oic acid (trachylobane-360) and ent-7α-hydroxytrachyloban-18-oic acid (trachylobane-318), diterpenes obtained from Xylopia langsdorfiana, on guinea pig ileum. Both compounds inhibited histamine-induced cumulative contractions (slope=3.5±0.9 and 4.4±0.7) that suggests a noncompetitive antagonism to histaminergic receptors. CaCl(2)-induced contractions were nonparallelly and concentration-dependently reduced by both diterpenes, indicating blockade of calcium influx through voltage-dependent calcium channels (Ca(v)). The Ca(v) participation was confirmed since both trachylobanes equipotently relaxed ileum pre-contracted with S-(-)-Bay K8644 (EC(50)=3.5±0.7×10-(5) and 1.1±0.2×10-(5)M) and KCl (EC(50)=5.5±0.3×10-(5) and 1.4±0.2×10-(5)M). K(+) channels participation was confirmed since diterpene-induced relaxation curves were significantly shifted to right in the presence of 5mM tetraethylammonium (TEA(+)) (EC(50)=0.5±0.04×10-(4) and 2.0±0.5×10-(5)M). ATP-sensitive K(+) channel (K(ATP)), voltage activated K(+) channels (K(V)), small conductance calcium-activated K(+) channels (SK(Ca)) or big conductance calcium-activated K(+) channels (BK(Ca)) did not seem to participate of trachylobane-360 spasmolytic action. However trachylobane-318 modulated positively K(ATP), K(V) and SK(Ca) (EC(50)=1.1±0.3×10-(5), 0.7±0.2×10-(5) and 0.7±0.2×10-(5)M), but not BK(Ca). A fluorescence analysis technique confirmed the decrease of cytosolic calcium concentration ([Ca(2+)](c)) induced by both trachylobanes in ileal myocytes. In conclusion, trachylobane-360 and trachylobane-318 induced spasmolytic activity by K(+) channel positive modulation and Ca(2+) channel blockade, which results in [Ca(2+)](c) reduction at cellular level leading to smooth muscle relaxation.
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Affiliation(s)
- Rosimeire F Santos
- Departamento de Bioquímica e Farmacologia, Universidade Federal do Piauí (UFPI), Teresina, Piauí, Brazil
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Suguro M, Matsuyama H, Tanahashi Y, Unno T, Kitazawa T, Yamada M, Komori S. Muscarinic receptor subtypes mediating Ca2+ sensitization of intestinal smooth muscle contraction: studies with receptor knockout mice. J Vet Med Sci 2009; 72:443-51. [PMID: 20009428 DOI: 10.1292/jvms.09-0458] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
In the present study, we have characterized muscarinic receptor subtypes that mediate carbachol-induced Ca2+ sensitization of contraction in intestinal smooth muscle, using mutant mice lacking M(2) or M(3) muscarinic receptors or both receptor subtypes. In alpha-toxin-permeabilized muscle strips from wild-type (WT) mice, isometric tension responses to Ca2+ applied cumulatively (pCa 7.0-5.0) were increased when the muscarinic agonist carbachol (100 microM) was added to the medium, as judged from shifts of pCa-tension curves in both 50% effective concentration (EC(50)) and maximum response (E(max)) of pCa-tension curve. In preparations from M(2)-knockout (KO) mice, pCa-tension curves were also shifted by carbachol (100 microM), and the extents of the EC(50) and E(max) changes resembled those observed in preparations from WT mice. In preparations from M(3)-KO or M(2)/M(3)-double KO mice, however, no significant changes in pCa-tension curves were obtained after carbachol application. The G(q/11)-type G-protein inhibitor YM-254890 (1 microM) completely blocked the Ca2+ sensitization of contraction induced by carbachol in M(2)-KO or WT preparations. The results strongly support the idea that the muscarinic activation of Ca2+ sensitization in intestinal smooth muscles is mediated by the M(3) muscarinic receptor coupled to G(q/11)-type G-proteins, without any significant involvement of the other muscarinic receptor subtypes including M(2).
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Affiliation(s)
- Mayuko Suguro
- Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University
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