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Zhao Q, Liu J, Chen L, Gao Z, Lin M, Wang Y, Xiao Z, Chen Y, Huang X. Phytomedicine Fructus Aurantii-derived two absorbed compounds unlock antidepressant and prokinetic multi-functions via modulating 5-HT 3/GHSR. J Ethnopharmacol 2024; 323:117703. [PMID: 38185260 DOI: 10.1016/j.jep.2024.117703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 12/02/2023] [Accepted: 01/02/2024] [Indexed: 01/09/2024]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Fructus Aurantii (FA), a well-known phytomedicine, has been employed to evoke antidepressant and prokinetic multi-functions. Therein, systematically identifying bioactive components and the referred mechanism is essential for FA. AIM OF THE STUDY This study was planned to answer "2 W" (What and Why), such as which components and pathways contribute to FA's multi-functions. We aimed to identify bioactive compounds as the key for opening the lock of FA's multi-functions, and the molecule mechanisms are their naturally matched lock cylinder. MATERIALS AND METHODS The phytochemical content of FA extract was determined, and the compounds were identified in rats pretreated with FA using liquid chromatography with mass spectrometry (LC-MS). The contribution strategy was used to assess bioactive compounds' efficacy (doses = their content in FA) in model rats with the mechanism. The changes in functional brain regions were determined via 7.0 T functional magnetic resonance imaging-blood oxygen level-dependent (fMRI-BOLD). RESULT Eight phytochemicals' content was detected, and merely six components were identified in rats in vivo. Meranzin hydrate + hesperidin (MH), as the primary contributor of FA, exerted antidepressant and prokinetic effects (improvement of indexes for immobility time, gastric emptying, intestinal transit, CRH, ghrelin, ACTH, DA, NA, 5-HT, CORT, and 5-HT3) by regulating 5-HT3/Growth hormone secretagogue receptor (GHSR) pathway. These results were validated by 5-HT2A, 5-HT3, and GHSR receptor antagonists combined with molecule docking. MH restored the excessive BOLD activation of the left accumbens nucleus, left corpus callosum and hypothalamus preoptic region. CONCLUSION Absorbed MH accounts for FA's anti-depressant and prokinetic efficacy in acutely-stressed rats, primarily via 5-HT3/GHSR shared regulation.
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Affiliation(s)
- Qiulong Zhao
- Institute of TCM-Related Comorbid Depression, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Jin Liu
- Medical College, Xiamen University, School of Medicine, Xiamen, 361102, China
| | - Li Chen
- Institute of TCM-Related Comorbid Depression, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Zhao Gao
- Institute of TCM-Related Comorbid Depression, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Muhai Lin
- Medical College, Xiamen University, School of Medicine, Xiamen, 361102, China
| | - Yun Wang
- Medical College, Xiamen University, School of Medicine, Xiamen, 361102, China
| | - Zhe Xiao
- Medical College, Xiamen University, School of Medicine, Xiamen, 361102, China
| | - Yi Chen
- Medical College, Xiamen University, School of Medicine, Xiamen, 361102, China
| | - Xi Huang
- Institute of TCM-Related Comorbid Depression, Nanjing University of Chinese Medicine, Nanjing 210023, China; Medical College, Xiamen University, School of Medicine, Xiamen, 361102, China.
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Rodriguez Araujo N, Hernando G, Corradi J, Bouzat C. The nematode serotonin-gated chloride channel MOD-1: A novel target for anthelmintic therapy. J Biol Chem 2022; 298:102356. [PMID: 35952761 PMCID: PMC9471462 DOI: 10.1016/j.jbc.2022.102356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 10/29/2022] Open
Abstract
Anthelmintics are used to treat human and veterinary parasitic diseases, as well as to reduce crop and livestock production loss associated with parasitosis. The free-living nematode Caenorhabditis elegans, a model system for anthelmintic drug discovery, has a serotonin (5-HT)-gated chloride channel, MOD-1, which belongs to the Cys-loop receptor family and modulates locomotory and behavioral functions. Since MOD-1 is unique to nematodes, it is emerging as an attractive anthelmintic drug target, but details of MOD-1 function are unclear. Here, we revealed novel aspects of MOD-1 function from the molecular level to the organism level and identified compounds targeting this receptor, which may provide new directions for anthelmintic drug discovery. We used whole-cell current recordings from heterologously expressed MOD-1 to show that tryptamine, a weak partial agonist of vertebrate 5-HT3 receptors, efficaciously activates MOD-1. A screen for modulators revealed that GABAergic ligands piperazine and muscimol reduce 5-HT-elicited currents, thus identifying novel MOD-1 allosteric inhibitors. Next, we performed locomotor activity assays, and we found 5-HT and tryptamine rapidly decrease worm motility, which is reversible only at low 5-HT concentrations. Mutants lacking MOD-1 are partially resistant to both drugs, demonstrating its key role in locomotion. Acting as an antagonist of MOD-1, we showed piperazine reduces the locomotor effects of exogenous 5-HT. Therefore, tryptamine- and piperazine-derived compounds, acting at MOD-1 through different molecular mechanisms, emerge as promising anthelmintic agents. This study enhances our knowledge of the function and drug selectivity of Cys-loop receptors and postulates MOD-1 as a potential target for anthelmintic therapy.
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Affiliation(s)
- Noelia Rodriguez Araujo
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Guillermina Hernando
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Jeremías Corradi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.
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Promdam N, Khuituan P, Panichayupakaranant P. Effects of standardized [6]-gingerol extracts and [6]-gingerol on isolated ileum and lower esophageal sphincter contractions in mice. Food Chem 2022; 378:132077. [PMID: 35042108 DOI: 10.1016/j.foodchem.2022.132077] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 02/08/2023]
Abstract
Standardized [6]-gingerol extracts were prepared by microwave-assisted extraction using 20% v/v glycerin in ethanol and 20% v/v eutectic mixture of sucrose and citric acid in ethanol as alternative green solvents. The extracts obtained from 20% v/v glycerin in ethanol (GEE) and 20% v/v eutectic mixture of sucrose and citric acid in ethanol (EMSCEE) were standardized by HPLC to contain 17.0 mg/g of [6]-gingerol. The effects of the extracts on mouse ileal contractions via M3 and 5-HT3 receptors as well as lower esophageal sphincter (LES) contraction were determined in vitro relative to the marker compound, [6]-gingerol. [6]-Gingerol, GEE and EMSCEE demonstrated significant and concentration-dependent inhibitory effects on ileal contraction in mice via M3 and 5-HT3 receptors in a noncompetitive manner. In addition, [6]-gingerol and EMSCEE tend to increase the LES tone. These results indicated the potential of GEE and EMSCEE to attenuate nausea and vomiting and might be used as nutraceuticals.
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Affiliation(s)
- Nantaporn Promdam
- Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand
| | - Pissared Khuituan
- Division of Health and Applied Sciences, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand; Gut Biology and Microbiota Research Unit, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand
| | - Pharkphoom Panichayupakaranant
- Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand; Phytomedicine and Pharmaceutical Biotechnology Excellence Center, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand.
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Leino T, Lehtimäki J, Koivisto A, Haapalinna A, Pesonen U. Fadolmidine - Favourable adverse effects profile for spinal analgesia suggested by in vitro and in vivo models. Eur J Pharmacol 2020; 882:173296. [PMID: 32592769 DOI: 10.1016/j.ejphar.2020.173296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 06/02/2020] [Accepted: 06/17/2020] [Indexed: 11/18/2022]
Abstract
Fadolmidine is an α2-adrenoceptor full agonist developed for spinal analgesia with a local mode of action. The purpose of this study was to demonstrate the safety of fadolmidine on known α2-adrenoceptor-related effects: kidney function, urodynamics and cardiovascular variables. Furthermore, the binding affinity of fadolmidine for the 5-HT3 receptor prompted functional studies on 5-HT3. According to the binding affinity data, fadolmidine demonstrated partial agonism on the 5-HT3 receptor in transfected cells and in guinea pig ileum preparation. However, intravenous (IV) fadolmidine did not produce any 5-HT3-related hemodynamic effects in anaesthetised rats. In urodynamic studies, intrathecal (IT) fadolmidine interrupted volume-evoked voiding cycles and induced overflow incontinence at high concentrations in anaesthetised rats; however, at the analgesic dose range, the effects were mild. The effects of fadolmidine on kidney function were studied in conscious rats after IV and IT dosing. While IT fadolmidine increased dose-dependent urine output, sodium ion concentration, IV doses increased only sodium ion concentration The effects of IT fadolmidine on heart rate (HR), mean arterial pressure (MAP) and sedation were evaluated in the home cage and in the open field using a telemetry system. In resting conditions, fadolmidine decreased HR dose-dependently and increased initial MAP, whereas in actively moving rats, there were no effects at analgesic doses. The results suggest that at anticipated analgesic clinical doses, IT fadolmidine provides analgesia without significant adverse effects on sedation, MAP or HR and with only modest effects on kidney function and urodynamics.
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Affiliation(s)
- Tiina Leino
- Orion Corporation Orion Pharma, R&D, P.O. Box 425, FI-20101, Turku, Finland
| | - Jyrki Lehtimäki
- Orion Corporation Orion Pharma, R&D, P.O. Box 425, FI-20101, Turku, Finland.
| | - Ari Koivisto
- Orion Corporation Orion Pharma, R&D, P.O. Box 425, FI-20101, Turku, Finland
| | - Antti Haapalinna
- Orion Corporation Orion Pharma, R&D, P.O. Box 425, FI-20101, Turku, Finland
| | - Ullamari Pesonen
- Institute of Biomedicine, Faculty of Medicine, University of Turku, Kiinanmyllynkatu 10, FI-20520, Turku, Finland
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Nakamura Y, Kondo M, Koyama Y, Shimada S. Yokukansan-induced reduction of ethanol preference is associated with antagonism of 5-HT3 receptors. Phytomedicine 2019; 59:152897. [PMID: 30974311 DOI: 10.1016/j.phymed.2019.152897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 12/10/2018] [Accepted: 03/19/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND We recently reported that alkaloids in Uncaria hook (a constituent of yokukansan) contribute to antagonism of 5-HT3 receptors. Many studies have reported that 5-HT3 receptor antagonists reduce alcohol preference. However, the effect of yokukansan on alcohol preference is not clear. PURPOSE This study was performed to investigate the direct effect of yokukansan on alcohol preference and the effect of 5-HT3 receptors on the preference. STUDY DESIGN We examined ethanol preference effected by yokukansan. Next, we analyzed the contribution of 5-HT3 receptors to the effect of yokukansan. METHODS Ethanol preference was measured using the two-bottle preference test in mice fed with or without yokukansan diet. Next, the contribution of 5-HT3 receptors to ethanol preference was investigated using 5-HT3 receptor-deficient mice. RESULTS Reduction of ethanol preference by yokukansan was not observed using 5-HT3 receptor deficient mice. CONCLUSION Yokukansan contributes to reduced ethanol preference and antagonism of 5-HT3 receptors is associated with the effect.
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Affiliation(s)
- Yukiko Nakamura
- Department of Neuroscience and Cell Biology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Makoto Kondo
- Department of Neuroscience and Cell Biology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoshihisa Koyama
- Department of Neuroscience and Cell Biology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shoichi Shimada
- Department of Neuroscience and Cell Biology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan
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Patel R, Dickenson AH. Modality selective roles of pro-nociceptive spinal 5-HT 2A and 5-HT 3 receptors in normal and neuropathic states. Neuropharmacology 2018; 143:29-37. [PMID: 30240783 PMCID: PMC6277848 DOI: 10.1016/j.neuropharm.2018.09.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 08/23/2018] [Accepted: 09/17/2018] [Indexed: 12/20/2022]
Abstract
Descending brainstem control of spinal nociceptive processing permits a dynamic and adaptive modulation of ascending sensory information. Chronic pain states are frequently associated with enhanced descending excitatory drive mediated predominantly through serotonergic neurones in the rostral ventromedial medulla. In this study, we examine the roles of spinal 5-HT2A and 5-HT3 receptors in modulating ascending sensory output in normal and neuropathic states. In vivo electrophysiology was performed in anaesthetised spinal nerve ligated (SNL) and sham-operated rats to record from wide dynamic range neurones in the ventral posterolateral thalamus. In sham rats, block of spinal 5-HT3Rs with ondansetron revealed tonic facilitation of noxious punctate mechanical stimulation, whereas blocking 5-HT2ARs with ketanserin had minimal effect on neuronal responses to evoked stimuli. The inhibitory profiles of both drugs were altered in SNL rats; ondansetron additionally inhibited neuronal responses to lower intensity punctate mechanical stimuli and noxious heat evoked responses, whereas ketanserin inhibited innocuous and noxious evaporative cooling evoked responses. Neither drug had any effect on dynamic brush evoked responses nor on spontaneous firing rates in both sham and SNL rats. These data identify novel modality and intensity selective facilitatory roles of spinal 5-HT2A and 5-HT3 receptors on sensory neuronal processing within the spinothalamic-somatosensory cortical pathway.
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Affiliation(s)
- Ryan Patel
- University College London, Gower Street, Department of Neuroscience, Physiology and Pharmacology, London, WC1E 6BT, UK.
| | - Anthony H Dickenson
- University College London, Gower Street, Department of Neuroscience, Physiology and Pharmacology, London, WC1E 6BT, UK
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Nakamura Y, Ishida Y, Kondo M, Shimada S. Yokukansan contains compounds that antagonize the 5-HT 3 receptor. Phytomedicine 2018; 43:120-125. [PMID: 29747744 DOI: 10.1016/j.phymed.2018.04.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 02/23/2018] [Accepted: 04/15/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND We recently focused on alkaloids in Uncaria hook (a constituent of the Kampo medicine, yokukansan) and identified the pharmacological action of geissoschizine methyl ether on several G protein-coupled receptors. However, the functions of other identified alkaloids in Uncaria hook, including hirsutine, hirsuteine, rhynchophylline, isorhynchophylline, corynoxeine, isocorynoxeine, are not clear. PURPOSE To evaluate the effect of seven alkaloids in Uncaria hook (hirsutine, hirsuteine, rhynchophylline, isorhynchophylline, corynoxeine, isocorynoxeine and geissoschizine methyl ether) on the hydroxytryptamine type-3 (5-HT3) receptor ion channel. STUDY DESIGN We examined the effect of these alkaloids on the current of human 5-HT3 receptors expressed in Xenopus laevis oocytes. METHODS The human 5-HT3A subunit alone for the 5-HT3A receptor, or 5-HT3A and 5-HT3B subunits for the 5-HT3AB receptor, were expressed in Xenopus laevis oocytes. The 5-HT current was measured with or without alkaloid application using a two-electrode voltage clamp. RESULTS Each alkaloid, except for geissoschizine methyl ether, weakly inhibited the 5-HT-mediated 5-HT3A and/or 5-HT3AB receptor current, but co-application of these seven alkaloids inhibited the current strongly. CONCLUSION Each alkaloid contributes to antagonism of the 5-HT3 receptor.
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Affiliation(s)
- Yukiko Nakamura
- Department of Neuroscience and Cell Biology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Yusuke Ishida
- Department of Neuroscience and Cell Biology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Makoto Kondo
- Department of Neuroscience and Cell Biology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shoichi Shimada
- Department of Neuroscience and Cell Biology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan
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Su YS, Mei HR, Wang CH, Sun WH. Peripheral 5-HT 3 mediates mirror-image pain by a cross-talk with acid-sensing ion channel 3. Neuropharmacology 2017; 130:92-104. [PMID: 29196182 DOI: 10.1016/j.neuropharm.2017.11.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/10/2017] [Accepted: 11/27/2017] [Indexed: 12/21/2022]
Abstract
Mirror-image pain (MIP), which occurs along with complex regional pain syndrome, rheumatoid arthritis and chronic migraine, is characterized by increased pain sensitivity of healthy body regions other than the actual injured or inflamed sites. A high level of peripheral inflammation may activate central or peripheral glia, triggering mirror-image pain. However, which receptors mediate inflammatory signals to contribute glial activation remains unclear. Intraplantarly injecting mice with 5-hydroxytryptamine (5-HT) or acidic buffer (proton) caused only unilateral hyperalgesia, but co-injection of 5-HT/acid induced bilateral hyperalgesia (MIP). Blocking 5-HT3 or acid-sensing ion channel 3 (ASIC3) abolished satellite glial activation, inhibiting MIP. Interestingly, intraplantar administration of a 5-HT3 agonist induced MIP, and 5-HT3-mediated MIP can be reversed by a 5-HT3 antagonist or an ASIC3 blocker. Similar results were found using a ASIC3 agonist. Furthermore, 5-HT3 was observed to co-localize with ASIC3 in DRG neurons; 5-HT3 activation-induced an increase in intracellular calcium that was inhibited by an ASIC3 blocker and vice versa. A cross-talk between 5-HT3 and ASIC3 mediates satellite glial activation, thereby triggering mirror-image pain.
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Affiliation(s)
- Yeu-Shiuan Su
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan city, Taiwan.
| | - Hao-Ruei Mei
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan city, Taiwan.
| | - Chun-Hung Wang
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan city, Taiwan.
| | - Wei-Hsin Sun
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan city, Taiwan; Department of Biomedical Sciences and Engineering, National Central University, Zhongli District, Taoyuan city, Taiwan.
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Ruepp MD, Wei H, Leuenberger M, Lochner M, Thompson AJ. The binding orientations of structurally-related ligands can differ; A cautionary note. Neuropharmacology 2017; 119:48-61. [PMID: 28137449 PMCID: PMC5464333 DOI: 10.1016/j.neuropharm.2017.01.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 01/13/2017] [Accepted: 01/24/2017] [Indexed: 11/19/2022]
Abstract
Crystal structures can identify ligand-receptor interactions and assist the development of novel therapeutics, but experimental challenges sometimes necessitate the use of homologous proteins. Tropisetron is an orthosteric ligand at both 5-HT3 and α7 nACh receptors and its binding orientation has been determined in the structural homologue AChBP (pdbid: 2WNC). Co-crystallisation with a structurally-related ligand, granisetron, reveals an almost identical orientation (pdbid; 2YME). However, there is a >1000-fold difference in the affinity of tropisetron at 5-HT3 versus α7 nACh receptors, and α7 nACh receptors do not bind granisetron. These striking pharmacological differences prompt questions about which receptor the crystal structures most closely represent and whether the ligand orientations are correct. Here we probe the binding orientation of tropisetron and granisetron at 5-HT3 receptors by in silico modelling and docking, radioligand binding on cysteine-substituted 5-HT3 receptor mutants transiently expressed in HEK 293 cells, and synthetic modification of the ligands. For 15 of the 23 cysteine substitutions, the effects on tropisetron and granisetron were different. Structure-activity relationships on synthesised derivatives of both ligands were also consistent with different orientations, revealing that contrary to the crystallographic evidence from AChBP, the two ligands adopt different orientations in the 5-HT3 receptor binding site. Our results show that even quite structurally similar molecules can adopt different orientations in the same binding site, and that caution may be needed when using homologous proteins to predict ligand binding. The drugs granisetron and tropisetron are structurally similar. Crystals of them bound to AChBP suggest they have similar binding orientations. At 5-HT3R, the effects of mutagenesis indicate that their orientations differ. SAR on both of these drugs also supports different orientations.
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Affiliation(s)
- Marc-David Ruepp
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Hao Wei
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Michele Leuenberger
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Martin Lochner
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland; Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.
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Pratt WE, Lin P, Pierce-Messick Z, Ilesanmi AO, Clissold KA. Contrasting effects of 5-HT 3 receptor stimulation of the nucleus accumbens or ventral tegmentum on food intake in the rat. Behav Brain Res 2017; 323:15-23. [PMID: 28115218 DOI: 10.1016/j.bbr.2017.01.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 01/17/2017] [Accepted: 01/18/2017] [Indexed: 11/22/2022]
Abstract
Although serotonin (5-HT) signaling is known to regulate food intake and energy homeostasis, the roles of the 5-HT3 receptor in feeding processes have been elusive. 5-HT3 receptors are found throughout mesolimbic circuitry that promote feeding not only in response to hunger, but also to the palatable and rewarding properties of food. These experiments examined if stimulation or blockade of the 5-HT3 receptor of the nucleus accumbens (NAcc) or ventral tegmentum affected food intake in the rat in response to hunger or the presence of a palatable diet. Rats (N=6-9/group) received bilateral injections of the 5-HT3 agonist m-chlorophenylbiguanide hydrochloride (mCPBG; at 0.0, 10.0, or 20.0μg/0.5μl/side) or the 5-HT3 antagonist ondansetron hydrochloride (at 0.0, 1.0, 2.0, or 5.0μg/0.5μl/side) into either the NAcc or the ventral tegmentum. NAcc 5-HT3 receptor stimulation significantly increased 2-h food intake in food-deprived animals offered rat chow and in a separate group of unrestricted rats offered a sweetened fat diet. In contrast to the feeding increase seen with NAcc treatments, stimulation of 5-HT3 receptors of the ventral tegmentum significantly reduced food and water intake in food-restricted animals; reductions of intake in non-restricted rats offered the palatable diet did not approach significance. Blockade of the 5-HT3 receptor had no effect on feeding in either brain region. These data support a functional role for serotonergic signaling in the mesolimbic pathway on motivated behavior, and demonstrate that 5-HT3 receptors differentially modulate food consumption in a region-dependent manner.
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Lochner M, Thompson AJ. The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT3 receptors. Neuropharmacology 2016; 108:220-8. [PMID: 27108935 PMCID: PMC4920643 DOI: 10.1016/j.neuropharm.2016.04.027] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 03/09/2016] [Accepted: 04/20/2016] [Indexed: 11/30/2022]
Abstract
Scopolamine is a high affinity muscarinic antagonist that is used for the prevention of post-operative nausea and vomiting. 5-HT3 receptor antagonists are used for the same purpose and are structurally related to scopolamine. To examine whether 5-HT3 receptors are affected by scopolamine we examined the effects of this drug on the electrophysiological and ligand binding properties of 5-HT3A receptors expressed in Xenopus oocytes and HEK293 cells, respectively. 5-HT3 receptor-responses were reversibly inhibited by scopolamine with an IC50 of 2.09 μM. Competitive antagonism was shown by Schild plot (pA2 = 5.02) and by competition with the 5-HT3 receptor antagonists [(3)H]granisetron (Ki = 6.76 μM) and G-FL (Ki = 4.90 μM). The related molecule, atropine, similarly inhibited 5-HT evoked responses in oocytes with an IC50 of 1.74 μM, and competed with G-FL with a Ki of 7.94 μM. The reverse experiment revealed that granisetron also competitively bound to muscarinic receptors (Ki = 6.5 μM). In behavioural studies scopolamine is used to block muscarinic receptors and induce a cognitive deficit, and centrally administered concentrations can exceed the IC50 values found here. It is therefore possible that 5-HT3 receptors are also inhibited. Studies that utilise higher concentrations of scopolamine should be mindful of these potential off-target effects.
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Affiliation(s)
- Martin Lochner
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland.
| | - Andrew J Thompson
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK.
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Miles TF, Lester HA, Dougherty DA. Allosteric activation of the 5-HT3AB receptor by mCPBG. Neuropharmacology 2014; 91:103-8. [PMID: 25541413 DOI: 10.1016/j.neuropharm.2014.12.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 10/16/2014] [Accepted: 12/10/2014] [Indexed: 10/25/2022]
Abstract
The 5-HT3AB receptor contains three A and two B subunits in an A-A-B-A-B order. However, serotonin function at the 5-HT3AB receptor has been shown to depend solely on the A-A interface present in the homomeric receptor. Using mutations at sites on both the primary (E122) and complementary (Y146) faces of the B subunit, we demonstrate that meta-chlorophenyl biguanide (mCPBG), a 5-HT3 selective agonist, is capable of binding to and activating the 5-HT3AB receptor at all five subunit interfaces of the heteromer. Further, mCPBG is capable of allosterically modulating the activity of serotonin from these sites. While these five binding sites are similar enough that they conform to a monophasic dose - response relationship, we uncover subtle differences in the heteromeric binding sites. We also find that the A-A interface appears to contribute disproportionately to the efficacy of 5-HT3AB receptor activation.
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Affiliation(s)
- Timothy F Miles
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA.
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Thompson AJ, Verheij MHP, Verbeek J, Windhorst AD, de Esch IJP, Lummis SCR. The binding characteristics and orientation of a novel radioligand with distinct properties at 5-HT3A and 5-HT3AB receptors. Neuropharmacology 2014; 86:378-88. [PMID: 25174552 PMCID: PMC4220016 DOI: 10.1016/j.neuropharm.2014.08.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 07/22/2014] [Accepted: 08/09/2014] [Indexed: 12/22/2022]
Abstract
VUF10166 (2-chloro-3-(4-methyl piperazin-1-yl)quinoxaline) is a ligand that binds with high affinity to 5-HT3 receptors. Here we synthesise [(3)H]VUF10166 and characterise its binding properties at 5-HT3A and 5-HT3AB receptors. At 5-HT3A receptors [(3)H]VUF10166 displayed saturable binding with a Kd of 0.18 nM. Kinetic measurements gave monophasic association (6.25 × 10(7) M(-1) min(-1)) and dissociation (0.01 min(-1)) rates that yielded a similar Kd value (0.16 nM). At 5-HT3AB receptors two association (6.15 × 10(-7), 7.23 M(-1) min(-1)) and dissociation (0.024, 0.162 min(-1)) rates were seen, yielding Kd values (0.38 nM and 22 nM) that were consistent with values obtained in saturation (Kd = 0.74 nM) and competition (Ki = 37 nM) binding experiments respectively. At both receptor types, specific binding was inhibited by classical 5-HT3 receptor-selective orthosteric ligands (5-HT, allosetron, d-tubocurarine, granisetron, mCPBG, MDL72222, quipazine), but not by non-competitive antagonists (bilobalide, ginkgolide B, picrotoxin) or competitive ligands of other Cys-loop receptors (ACh, bicuculline, glycine, gabazine). To explore VUF10166 ligand-receptor interactions we used in silico modelling and docking, and tested the predictions using site directed mutagenesis. The data suggest that VUF10166 adopts a similar orientation to 5-HT3 receptor agonists bound in AChBP (varenicline) and 5HTBP (5-HT) crystal structures.
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Affiliation(s)
| | - Mark H P Verheij
- Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | - Joost Verbeek
- VU University Medical Center, Dept Radiology & Nuclear Medicine, Amsterdam, The Netherlands
| | - Albert D Windhorst
- VU University Medical Center, Dept Radiology & Nuclear Medicine, Amsterdam, The Netherlands
| | - Iwan J P de Esch
- Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | - Sarah C R Lummis
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
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Rock EM, Parker LA. Suppression of lithium chloride-induced conditioned gaping (a model of nausea-induced behaviour) in rats (using the taste reactivity test) with metoclopramide is enhanced by cannabidiolic acid. Pharmacol Biochem Behav 2013; 111:84-9. [PMID: 24012649 DOI: 10.1016/j.pbb.2013.08.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 08/19/2013] [Accepted: 08/28/2013] [Indexed: 10/26/2022]
Abstract
We aimed to determine the potential of various doses of metoclopramide (MCP, a dopamine antagonist) to reduce lithium chloride (LiCl)-induced conditioned gaping (a nausea-induced behaviour) in rats, using the taste reactivity test. We then evaluated whether an ineffective low dose of cannabidiolic acid (CBDA, 0.1 μg/kg, Rock and Parker, 2013), the potent acidic precursor of cannabidiol (CBD, a non-psychoactive component of cannabis) could enhance the anti-nausea effects of an ineffective low dose of MCP. MCP (3.0 mg/kg) reduced conditioned gaping responses. Coadministration of ineffective doses of MCP (0.3 mg/kg) and CBDA (0.1 μg/kg) enhanced the suppression of conditioned gaping, over that of either drug alone, without interfering with conditioned taste avoidance. MCP dose-dependently reduced nausea-induced conditioned gaping in rats. As well, the suppression of conditioned gaping was enhanced when ineffective doses of MCP and CBDA were coadministered. These data suggest that CBDA could be a powerful adjunct treatment to anti-emetic regimens for chemotherapy-induced nausea.
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Li Q, Guo D, Dong Z, Zhang W, Zhang L, Huang SM, Polli JE, Shu Y. Ondansetron can enhance cisplatin-induced nephrotoxicity via inhibition of multiple toxin and extrusion proteins (MATEs). Toxicol Appl Pharmacol 2013; 273:100-9. [PMID: 24001450 DOI: 10.1016/j.taap.2013.08.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 08/12/2013] [Accepted: 08/23/2013] [Indexed: 12/23/2022]
Abstract
The nephrotoxicity limits the clinical application of cisplatin. Human organic cation transporter 2 (OCT2) and multidrug and toxin extrusion proteins (MATEs) work in concert in the elimination of cationic drugs such as cisplatin from the kidney. We hypothesized that co-administration of ondansetron would have an effect on cisplatin nephrotoxicity by altering the function of cisplatin transporters. The inhibitory potencies of ondansetron on metformin accumulation mediated by OCT2 and MATEs were determined in the stable HEK-293 cells expressing these transporters. The effects of ondansetron on drug disposition in vivo were examined by conducting the pharmacokinetics of metformin, a classical substrate for OCTs and MATEs, in wild-type and Mate1-/- mice. The nephrotoxicity was assessed in the wild-type and Mate1-/- mice received cisplatin with and without ondansetron. Both MATEs, including human MATE1, human MATE2-K, and mouse Mate1, and OCT2 (human and mouse) were subject to ondansetron inhibition, with much greater potencies by ondansetron on MATEs. Ondansetron significantly increased tissue accumulation and pharmacokinetic exposure of metformin in wild-type but not in Mate1-/- mice. Moreover, ondansetron treatment significantly enhanced renal accumulation of cisplatin and cisplatin-induced nephrotoxicity which were indicated by increased levels of biochemical and molecular biomarkers and more severe pathohistological changes in mice. Similar increases in nephrotoxicity were caused by genetic deficiency of MATE function in mice. Therefore, the potent inhibition of MATEs by ondansetron enhances the nephrotoxicity associated with cisplatin treatment in mice. Potential nephrotoxic effects of combining the chemotherapeutic cisplatin and the antiemetic 5-hydroxytryptamine-3 (5-HT3) receptor antagonists, such as ondansetron, should be investigated in patients.
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Affiliation(s)
- Qing Li
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, MD, USA; Institute of Clinical Pharmacology, Central South University, Hunan 410078, China
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Swartz MM, Linn DM, Linn CL. Tropisetron as a neuroprotective agent against glutamate-induced excitotoxicity and mechanisms of action. Neuropharmacology 2013; 73:111-21. [PMID: 23727438 DOI: 10.1016/j.neuropharm.2013.05.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 04/23/2013] [Accepted: 05/07/2013] [Indexed: 11/30/2022]
Abstract
The objective of this study was to determine the neuroprotective role of tropisetron on retinal ganglion cells (RGCs) as well as to explore the possible mechanisms associated with alpha7 nAChR-induced neuroprotection. Adult pig RGCs were isolated from all other retinal tissue using a two-step panning technique. Once isolated, RGCs were cultured for 3 days under control untreated conditions, in the presence of 500 μM glutamate to induce excitotoxicity, and when tropisetron was applied before glutamate to induce neuroprotection. 500 μM glutamate decreased RGC survival by an average of 62% compared to control conditions. However, RGCs pretreated with 100 nM tropisetron before glutamate increased cell survival to an average of 105% compared to controls. Inhibition studies using the alpha7 nAChR antagonist, MLA (10 nM), support the hypothesis that tropisetron is an effective neuroprotective agent against glutamate-induced excitotoxicity; mediated by α7 nAChR activation. ELISA studies were performed to determine if signaling cascades normally associated with excitotoxicity and neuroprotection were up- or down-regulated after tropisetron treatment. Tropisetron had no discernible effects on pAkt levels but significantly decreased p38 MAPK levels associated with excitotoxicity from an average of 15 ng/ml to 6 ng/ml. Another mechanism shown to be associated with neuroprotection involves internalization of NMDA receptors. Double-labeled immunocytochemistry and electrophysiology studies provided further evidence that tropisetron caused internalization of NMDA receptor subunits. The findings of this study suggest that tropisetron could be an effective therapeutic agent for the treatment of degenerative disorders of the central nervous system that involves excitotoxicity.
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Affiliation(s)
- Michael M Swartz
- Western Michigan University, Department of Biological Sciences, Kalamazoo, MI 49008, USA
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