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Stinson RJ, Morice AH, Sadofsky LR. Modulation of transient receptor potential (TRP) channels by plant derived substances used in over-the-counter cough and cold remedies. Respir Res 2023; 24:45. [PMID: 36755306 PMCID: PMC9907891 DOI: 10.1186/s12931-023-02347-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 01/27/2023] [Indexed: 02/10/2023] Open
Abstract
BACKGROUND Upper respiratory tract infections (URTIs) impact all age groups and have a significant economic and social burden on society, worldwide. Most URTIs are mild and self-limiting, but due to the wide range of possible causative agents, including Rhinovirus (hRV), Adenovirus, Respiratory Syncytial Virus (RSV), Coronavirus and Influenza, there is no single and effective treatment. Over-the-counter (OTC) remedies, including traditional medicines and those containing plant derived substances, help to alleviate symptoms including inflammation, pain, fever and cough. PURPOSE This systematic review focuses on the role of the major plant derived substances in several OTC remedies used to treat cold symptoms, with a particular focus on the transient receptor potential (TRP) channels involved in pain and cough. METHODS Literature searches were done using Pubmed and Web of Science, with no date limitations, using the principles of the PRISMA statement. The search terms used were 'TRP channel AND plant compound', 'cough AND plant compound', 'cough AND TRP channels AND plant compound', 'cough AND P2X3 AND plant compound' and 'P2X3 AND plant compound' where plant compound represents menthol or camphor or eucalyptus or turpentine or thymol. RESULTS The literature reviewed showed that menthol activates TRPM8 and may inhibit respiratory reflexes reducing irritation and cough. Menthol has a bimodal action on TRPA1, but inhibition may have an analgesic effect. Eucalyptus also activates TRPM8 and inhibits TRPA1 whilst down regulating P2X3, aiding in the reduction of cough, pain and airway irritation. Camphor inhibits TRPA1 and the activation of TRPM8 may add to the effects of menthol. Activation of TRPV1 by camphor, may also have an analgesic effect. CONCLUSIONS The literature suggests that these plant derived substances have multifaceted actions and can interact with the TRP 'cough' receptors. The plant derived substances used in cough and cold medicines have the potential to target multiple symptoms experienced during a cold.
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Affiliation(s)
- Rebecca J. Stinson
- grid.9481.40000 0004 0412 8669Centre for Biomedicine, Hull York Medical School, The University of Hull, Cottingham Road, Hull, HU6 7RX UK
| | - Alyn H. Morice
- grid.413631.20000 0000 9468 0801Clinical Sciences Centre, Hull York Medical School, Castle Hill Hospital, Cottingham, Hull, HU16 5JQ UK
| | - Laura R. Sadofsky
- grid.9481.40000 0004 0412 8669Centre for Biomedicine, Hull York Medical School, The University of Hull, Cottingham Road, Hull, HU6 7RX UK
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Hernandez-Leon A, Moreno-Pérez GF, Martínez-Gordillo M, Aguirre-Hernández E, Valle-Dorado MG, Díaz-Reval MI, González-Trujano ME, Pellicer F. Lamiaceae in Mexican Species, a Great but Scarcely Explored Source of Secondary Metabolites with Potential Pharmacological Effects in Pain Relief. Molecules 2021; 26:7632. [PMID: 34946714 PMCID: PMC8705283 DOI: 10.3390/molecules26247632] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/05/2021] [Accepted: 12/09/2021] [Indexed: 02/07/2023] Open
Abstract
The search for molecules that contribute to the relief of pain is a field of research in constant development. Lamiaceae is one of the most recognized families world-wide for its use in traditional medicine to treat diseases that include pain and inflammation. Mexico can be considered one of the most important centers of diversification, and due to the high endemism of this family, it is crucial for the in situ conservation of this family. Information about the most common genera and species found in this country and their uses in folk medicine are scarcely reported in the literature. After an extensive inspection in bibliographic databases, mainly Sciencedirect, Pubmed and Springer, almost 1200 articles describing aspects of Lamiaceae were found; however, 217 articles were selected because they recognize the Mexican genera and species with antinociceptive and/or anti-inflammatory potential to relieve pain, such as Salvia and Agastache. The bioactive constituents of these genera were mainly terpenes (volatile and non-volatile) and phenolic compounds such as flavonoids (glycosides and aglycone). The aim of this review is to analyze important aspects of Mexican genera of Lamiaceae, scarcely explored as a potential source of secondary metabolites responsible for the analgesic and anti-inflammatory properties of these species. In addition, we point out the possible mechanisms of action involved and the modulatory pathways investigated in different experimental models. As a result of this review, it is important to mention that scarce information has been reported regarding species of this family from Mexican genera. In fact, despite Calosphace being one of the largest subgenera of Salvia in the world, found mainly in Mexico, it has been barely investigated regarding its potential biological activities and recognized bioactive constituents. The scientific evidence regarding the different bioactive constituents found in species of Lamiaceae demonstrates that several species require further investigation in preclinical studies, and of course also in controlled clinical trials evaluating the efficacy and safety of these natural products to support their therapeutic potential in pain relief and/or inflammation, among other health conditions. Since Mexico is one of the most important centers of diversification, and due to the high endemism of species of this family, it is crucial their rescue, in situ conservation, and investigation of their health benefits.
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Affiliation(s)
- Alberto Hernandez-Leon
- Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (A.H.-L.); (G.F.M.-P.); (F.P.)
| | - Gabriel Fernando Moreno-Pérez
- Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (A.H.-L.); (G.F.M.-P.); (F.P.)
- Programa de Posgrado en Ciencias Biológicas, Facultad de Medicina, Universidad Autónoma de México, Ciudad Universitaria, Mexico City 04510, Mexico
| | - Martha Martínez-Gordillo
- Herbario de la Facultad de Ciencias, Departamento de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City 04510, Mexico;
| | - Eva Aguirre-Hernández
- Laboratorio de Productos Naturales, Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City 04510, Mexico;
| | - María Guadalupe Valle-Dorado
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City 04510, Mexico;
| | - María Irene Díaz-Reval
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima 28045, Mexico;
| | - María Eva González-Trujano
- Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (A.H.-L.); (G.F.M.-P.); (F.P.)
| | - Francisco Pellicer
- Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (A.H.-L.); (G.F.M.-P.); (F.P.)
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Moriyama H, Nomura S, Imoto H, Inoue T, Fujiyama Y, Haji K, Maruta Y, Ishihara H, Suzuki M. Suppressive Effects of Transient Receptor Potential Melastatin 8 Agonist on Epileptiform Discharges and Epileptic Seizures. Front Pharmacol 2021; 12:766782. [PMID: 34658898 PMCID: PMC8517222 DOI: 10.3389/fphar.2021.766782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 09/16/2021] [Indexed: 01/12/2023] Open
Abstract
Epilepsy is a relatively common condition, but more than 30% of patients have refractory epilepsy that is inadequately controlled by or is resistant to multiple drug treatments. Thus, new antiepileptic drugs based on newly identified mechanisms are required. A previous report revealed the suppressive effects of transient receptor potential melastatin 8 (TRPM8) activation on penicillin G-induced epileptiform discharges (EDs). However, it is unclear whether TRPM8 agonists suppress epileptic seizures or affect EDs or epileptic seizures in TRPM8 knockout (TRPM8KO) mice. We investigated the effects of TRPM8 agonist and lack of TRPM8 channels on EDs and epileptic seizures. Mice were injected with TRPM8 agonist 90 min after or 30 min before epilepsy-inducer injection, and electrocorticograms (ECoGs) were recorded under anesthesia, while behavior was monitored when awake. TRPM8 agonist suppressed EDs and epileptic seizures in wildtype (WT) mice, but not in TRPM8KO mice. In addition, TRPM8KO mice had a shorter firing latency of EDs, and EDs and epileptic seizures were deteriorated by the epilepsy inducer compared with those in WT mice, with the EDs being more easily propagated to the contralateral side. These findings suggest that TRPM8 activation in epileptic regions has anti-epileptic effects.
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Affiliation(s)
- Hiroshi Moriyama
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Sadahiro Nomura
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan.,Epilepsy Center, Yamaguchi University Hospital, Ube, Japan
| | - Hirochika Imoto
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan.,Epilepsy Center, Yamaguchi University Hospital, Ube, Japan
| | - Takao Inoue
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Yuichi Fujiyama
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Kohei Haji
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Yuichi Maruta
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Hideyuki Ishihara
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Michiyasu Suzuki
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
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Wang G. Ligand-stereoselective allosteric activation of cold-sensing TRPM8 channels by an H-bonded homochiral menthol dimer with head-to-head or head-to-tail. Chirality 2021; 33:783-796. [PMID: 34596287 DOI: 10.1002/chir.23364] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 11/07/2022]
Abstract
Both menthol and its analog WS-12 share the same hydrophobic intra-subunit binding pocket between a voltage-sensor-like domain and a TRP domain in a cold-sensing TRPM8 channel. However, unlike WS-12, menthol upregulates TRPM8 with a low efficacy but a high coefficient of a dose response at membrane hyperpolarization and with ligand stereoselectivity at membrane depolarization. The underlying mechanisms are unknown. Here, this in silico research suggested that the ligand-stereoselective sequential cooperativity between two menthol molecules in the WS-12 pocket is required for allosteric activation of TRPM8. Furthermore, two H-bonded homochiral menthol dimers with both head-to-head and head-to-tail can compete for the WS-12 site via non-covalent interactions. Although both dimers can form an H-bonding network with a voltage sensor S4 to disrupt a S3-S4 salt bridge in the voltage-sensor-like domain to release a "parking brake," only one dimer may drive channel opening by pushing a "gas pedal" in the TRP domain away from the S6 gate against S4. In this way, the efficacy is decreased, but the cooperativity is increased for the menthol effect at membrane hyperpolarization. Therefore, this review may extend a new pathway for ligand-stereoselective allosteric regulation of other voltage- and ligand-gated ion channels by menthol.
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Affiliation(s)
- Guangyu Wang
- Department of Drug Research and Development, Institute of Biophysical Medico-chemistry, Reno, NV, USA
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Revealing the Pharmacological Mechanism of Acorus tatarinowii in the Treatment of Ischemic Stroke Based on Network Pharmacology. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2020; 2020:3236768. [PMID: 33178313 PMCID: PMC7648688 DOI: 10.1155/2020/3236768] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/15/2020] [Accepted: 09/26/2020] [Indexed: 02/04/2023]
Abstract
Aim Stroke is the second significant cause for death, with ischemic stroke (IS) being the main type threatening human being's health. Acorus tatarinowii (AT) is widely used in the treatment of Alzheimer disease, epilepsy, depression, and stroke, which leads to disorders of consciousness disease. However, the systemic mechanism of AT treating IS is unexplicit. This article is supposed to explain why AT has an effect on the treatment of IS in a comprehensive and systematic way by network pharmacology. Methods and Materials ADME (absorbed, distributed, metabolized, and excreted) is an important property for screening-related compounds in AT, which were screening out of TCMSP, TCMID, Chemistry Database, and literature from CNKI. Then, these targets related to screened compounds were predicted via Swiss Targets, when AT-related targets database was established. The gene targets related to IS were collected from DisGeNET and GeneCards. IS-AT is a common protein interactive network established by STRING Database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were analysed by IS-AT common target genes. Cytoscape software was used to establish a visualized network for active compounds-core targets and core target proteins-proteins interactive network. Furthermore, we drew a signal pathway picture about its effect to reveal the basic mechanism of AT against IS systematically. Results There were 53 active compounds screened from AT, inferring the main therapeutic substances as follows: bisasaricin, 3-cyclohexene-1-methanol-α,α,4-trimethyl,acetate, cis,cis,cis-7,10,13-hexadecatrienal, hydroxyacoronene, nerolidol, galgravin, veraguensin, 2′-o-methyl isoliquiritigenin, gamma-asarone, and alpha-asarone. We obtained 398 related targets, 63 of which were the same as the IS-related genes from targets prediction. Except for GRM2, remaining 62 target genes have an interactive relation, respectively. The top 10 degree core target genes were IL6, TNF, IL1B, TLR4, NOS3, MAPK1, PTGS2, VEGFA, JUN, and MMP9. There were more than 20 terms of biological process, 7 terms of cellular components, and 14 terms of molecular function through GO enrichment analysis and 13 terms of signal pathway from KEGG enrichment analysis based on P < 0.05. Conclusion AT had a therapeutic effect for ischemic via multicomponent, multitarget, and multisignal pathway, which provided a novel research aspect for AT against IS.
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Ghosh M, Schepetkin IA, Özek G, Özek T, Khlebnikov AI, Damron DS, Quinn MT. Essential Oils from Monarda fistulosa: Chemical Composition and Activation of Transient Receptor Potential A1 (TRPA1) Channels. Molecules 2020; 25:E4873. [PMID: 33105614 PMCID: PMC7659962 DOI: 10.3390/molecules25214873] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 10/18/2020] [Accepted: 10/19/2020] [Indexed: 12/11/2022] Open
Abstract
Little is known about the pharmacological activity of Monarda fistulosa L. essential oils. To address this issue, we isolated essential oils from the flowers and leaves of M. fistulosa and analyzed their chemical composition. We also analyzed the pharmacological effects of M. fistulosa essential oils on transient receptor potential (TRP) channel activity, as these channels are known targets of various essential oil constituents. Flower (MEOFl) and leaf (MEOLv) essential oils were comprised mainly of monoterpenes (43.1% and 21.1%) and oxygenated monoterpenes (54.8% and 77.7%), respectively, with a high abundance of monoterpene hydrocarbons, including p-cymene, γ-terpinene, α-terpinene, and α-thujene. Major oxygenated monoterpenes of MEOFl and MEOLv included carvacrol and thymol. Both MEOFl and MEOLv stimulated a transient increase in intracellular free Ca2+ concentration ([Ca2+]i) in TRPA1 but not in TRPV1 or TRPV4-transfected cells, with MEOLv being much more effective than MEOFl. Furthermore, the pure monoterpenes carvacrol, thymol, and β-myrcene activated TRPA1 but not the TRPV1 or TRPV4 channels, suggesting that these compounds represented the TRPA1-activating components of M. fistulosa essential oils. The transient increase in [Ca2+]i induced by MEOFl/MEOLv, carvacrol, β-myrcene, and thymol in TRPA1-transfected cells was blocked by a selective TRPA1 antagonist, HC-030031. Although carvacrol and thymol have been reported previously to activate the TRPA1 channels, this is the first report to show that β-myrcene is also a TRPA1 channel agonist. Finally, molecular modeling studies showed a substantial similarity between the docking poses of carvacrol, thymol, and β-myrcene in the binding site of human TRPA1. Thus, our results provide a cellular and molecular basis to explain at least part of the therapeutic properties of these essential oils, laying the foundation for prospective pharmacological studies involving TRP ion channels.
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Affiliation(s)
- Monica Ghosh
- Department of Biological Sciences, School of Biological Sciences, Kent State University, Kent, OH 44242, USA; (M.G.); (D.S.D.)
| | - Igor A. Schepetkin
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA;
| | - Gulmira Özek
- Department of Pharmacognosy, Faculty of Pharmacy, Anadolu University, 26470 Eskisehir, Turkey; (G.Ö.); (T.Ö.)
| | - Temel Özek
- Department of Pharmacognosy, Faculty of Pharmacy, Anadolu University, 26470 Eskisehir, Turkey; (G.Ö.); (T.Ö.)
- Medicinal Plant, Drug and Scientific Research and Application Center (AUBIBAM), Anadolu University, 26470 Eskişehir, Turkey
| | - Andrei I. Khlebnikov
- National Research Tomsk Polytechnic University, Tomsk 643050, Russia;
- Faculty of Chemistry, Tomsk State University, 634050 Tomsk, Russia
| | - Derek S. Damron
- Department of Biological Sciences, School of Biological Sciences, Kent State University, Kent, OH 44242, USA; (M.G.); (D.S.D.)
| | - Mark T. Quinn
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA;
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Effect of Alpha 1-Adrnoceptor Antagonists on Postsynaptic Sensitivity in Substantia Gelatinosa Neurons From Lumbosacral Spinal Cord in Rats Using Slice Patch-Clamp Technique for mEPSC. Int Neurourol J 2020; 24:135-143. [PMID: 32615675 PMCID: PMC7332821 DOI: 10.5213/inj.1938250.125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 02/18/2020] [Indexed: 02/02/2023] Open
Abstract
Purpose Alpha1-adrenoceptors participate in improving storage symptoms of male lower urinary tract symptoms (LUTS). However, the mechanism of action of these compounds remains unclear. To clarify the mechanism of the α1-adrenoceptor antagonists, the amplitude of miniature excitatory postsynaptic currents (mEPSCs) was analyzed in the lumbosacral spinal cord in rats. Methods Male adult Sprague-Dawley rats were used. Blind whole-cell patch-clamp recordings were performed on substantia gelatinosa (SG) neurons in spinal cord slice preparations. The amplitude of mEPSCs was recorded in individual SG neurons to which α1-adrenoceptors (100μM naftopidil, 100μM tamsulosin, and 30μM silodosin) were applied sequentially with intervening washout periods. Individual amplitudes were analyzed. Results Pearson correlation coefficients (r) for the amplitudes of mEPSCs between the baseline and postadministration of α1-adrenoceptor antagonists indicated changes of the amplitude ranked in the order of naftopidil (r =0.393), tamsulosin (r=0.738), and silodosin (r=0.944). Together, the α1-adrenoceptor antagonists yielded significant increases in the amplitude of mEPSCs in SG neurons (n=108, P=0.012). However, the effects of each α1-adrenoceptor antagonist on the amplitude were as follows (relative to the baseline; n=36 each): naftopidil, P=0.129; tamsulosin, P=0.201; and silodosin, P=0.005. The rate of response to naftopidil for the outward current was relatively high among the α1-adrenoceptor blockers. An inward current was observed only with the naftopidil application. Conclusions Alpha1-adrenoceptor antagonists changed the amplitudes of mEPSCs in a subset of SG neurons in slices prepared from the L6–S1 levels of rat spine. Although the α1-adrenoceptor antagonists generated inward or outward currents in the SG neurons, different rates of response were observed with each antagonist. These results are important for understanding the mechanisms of action (at the spinal level) of α1-adrenoceptor antagonists for the storage symptoms of male LUTS.
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Zolfaghari Z, Vatanparast J. Thymol provokes burst of action potentials in neurons of snail Caucasotachea atrolabiata. Comp Biochem Physiol C Toxicol Pharmacol 2020; 228:108654. [PMID: 31683013 DOI: 10.1016/j.cbpc.2019.108654] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/27/2019] [Accepted: 10/29/2019] [Indexed: 12/15/2022]
Abstract
Thymol, a phenolic monoterpene, is well known for its antimicrobial, antifungal and antioxidant properties. In spite of wide use in oral care products, pharmaceutical and cosmetic preparation and in food industry, the effects of thymol on the neuronal activity and intrinsic properties have not been well studied. We studied the effects of thymol on the spontaneous activity and action potential properties of central neurons of snail Caucasotachea atrolabiata. Thymol (1 mM) altered action potentials characteristics and provoked epileptiform burst firing in snail neurons, which were partially reversible after washout. Before burst firing, action potentials had lower amplitude and maximum rising slope, while the threshold voltage was raised. These results suggest the inhibition of ion channels underlying action potential initiation and upstroke. The maximum falling slope and afterhyperpolarization were also considerably reduced, suggesting the inhibition of potassium channels. Thymol (0.5 mM) that was not able to induce burst firing in snail neurons, synergistically acted with potassium channel blocker, tetraethyl ammonium, to induce burst firing, which also supports the importance of potassium channel inhibition, especially delayed rectifier potassium channels, to the thymol-induced alteration of firing pattern. The thymol-induced burst firing seems to be dependent on both sodium and calcium currents. Our findings provide evidences for the ability of thymol in altering the firing mode of central neurons of snail, which apparently involves the inhibition of calcium and potassium currents. These results further support the interaction of thymol with ion channels and emphasize on the vulnerability of nervous system to this compound.
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Talavera K, Startek JB, Alvarez-Collazo J, Boonen B, Alpizar YA, Sanchez A, Naert R, Nilius B. Mammalian Transient Receptor Potential TRPA1 Channels: From Structure to Disease. Physiol Rev 2019; 100:725-803. [PMID: 31670612 DOI: 10.1152/physrev.00005.2019] [Citation(s) in RCA: 218] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The transient receptor potential ankyrin (TRPA) channels are Ca2+-permeable nonselective cation channels remarkably conserved through the animal kingdom. Mammals have only one member, TRPA1, which is widely expressed in sensory neurons and in non-neuronal cells (such as epithelial cells and hair cells). TRPA1 owes its name to the presence of 14 ankyrin repeats located in the NH2 terminus of the channel, an unusual structural feature that may be relevant to its interactions with intracellular components. TRPA1 is primarily involved in the detection of an extremely wide variety of exogenous stimuli that may produce cellular damage. This includes a plethora of electrophilic compounds that interact with nucleophilic amino acid residues in the channel and many other chemically unrelated compounds whose only common feature seems to be their ability to partition in the plasma membrane. TRPA1 has been reported to be activated by cold, heat, and mechanical stimuli, and its function is modulated by multiple factors, including Ca2+, trace metals, pH, and reactive oxygen, nitrogen, and carbonyl species. TRPA1 is involved in acute and chronic pain as well as inflammation, plays key roles in the pathophysiology of nearly all organ systems, and is an attractive target for the treatment of related diseases. Here we review the current knowledge about the mammalian TRPA1 channel, linking its unique structure, widely tuned sensory properties, and complex regulation to its roles in multiple pathophysiological conditions.
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Affiliation(s)
- Karel Talavera
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Justyna B Startek
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Julio Alvarez-Collazo
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Brett Boonen
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Yeranddy A Alpizar
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Alicia Sanchez
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Robbe Naert
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Bernd Nilius
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain and Disease Research, Leuven, Belgium
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Luo Y, Sun W, Feng X, Ba X, Liu T, Guo J, Xiao L, Jiang J, Hao Y, Xiong D, Jiang C. (-)-menthol increases excitatory transmission by activating both TRPM8 and TRPA1 channels in mouse spinal lamina II layer. Biochem Biophys Res Commun 2019; 516:825-830. [PMID: 31262448 DOI: 10.1016/j.bbrc.2019.06.135] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Accepted: 06/23/2019] [Indexed: 11/15/2022]
Abstract
(-)-menthol, a major form of menthol, is one of the most commonly used chemicals. Many studies have demonstrated that (-)-menthol produces analgesic action through peripheral mechanisms which are mainly mediated by activation of TRPM8. Moreover, intrathecal injection of menthol induces analgesia as well. However, the central actions and mechanisms of (-)-menthol remain unclear. Here, we have investigated the action of (-)-menthol on excitatory synaptic transmission in spinal lamina II layer which plays a pivotal role in modulating nociceptive transmission from the periphery by using patch-clamp technique in mice spinal cord. We found that (-)-menthol increased miniature excitatory postsynaptic current frequency. The frequency increases which (-)-menthol induced were in a dose-dependent manner (EC50: 0.1079 mM). However, neither genetic knockout nor pharmacological inhibition of TRPM8 could block (-)-menthol-induced effects entirely. Furthermore, this increase was also impaired by TRPA1 antagonist HC030031, but abolished utterly by co-application of TRPM8 and TRPA1 antagonist. Our results indicate that (-)-menthol increases the excitatory synaptic transmission by activating either TRPA1 or TRPM8 channels in spinal lamina II layer.
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Affiliation(s)
- Yuhui Luo
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Shenzhen Nanshan People's Hospital and the 6th Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen, 518060, China
| | - Wuping Sun
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Shenzhen Nanshan People's Hospital and the 6th Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen, 518060, China
| | - Xiaojin Feng
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, 330006, China
| | - Xiyuan Ba
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Shenzhen Nanshan People's Hospital and the 6th Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen, 518060, China
| | - Tao Liu
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, 330006, China
| | - Jing Guo
- Department of Endocrinology & Metabolism, Shenzhen University General Hospital and Shenzhen University Academy of Clinical Medical Sciences, Shenzhen University, Shenzhen, 518060, China
| | - Lizu Xiao
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Shenzhen Nanshan People's Hospital and the 6th Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen, 518060, China
| | - Jin Jiang
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Shenzhen Nanshan People's Hospital and the 6th Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen, 518060, China
| | - Yue Hao
- School of Pharmaceutical Sciences, Health Science Center, Shenzhen University, Shenzhen, 518060, China
| | - Donglin Xiong
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Shenzhen Nanshan People's Hospital and the 6th Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen, 518060, China
| | - Changyu Jiang
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Shenzhen Nanshan People's Hospital and the 6th Affiliated Hospital of Shenzhen University, Health Science Center, Shenzhen, 518060, China.
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11
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Rojas-Armas J, Arroyo-Acevedo J, Ortiz-Sánchez M, Palomino-Pacheco M, Castro-Luna A, Ramos-Cevallos N, Justil-Guerrero H, Hilario-Vargas J, Herrera-Calderón O. Acute and Repeated 28-Day Oral Dose Toxicity Studies of Thymus vulgaris L. Essential Oil in Rats. Toxicol Res 2019; 35:225-232. [PMID: 31341551 PMCID: PMC6629444 DOI: 10.5487/tr.2019.35.3.225] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 12/22/2018] [Accepted: 01/16/2019] [Indexed: 12/20/2022] Open
Abstract
Thymus vulgaris L. is widely used as an ingredient in cooking and in herbal medicine. However, there is little information about its toxicity. The present study was performed to evaluate the acute and repeated 28-day oral dose toxicity of thyme essential oil in rats. For the acute toxicity test, two groups of three rats were used. The rats received a single dose of essential oil: 300 or 2,000 mg/kg of body weight (bw). The rats were observed individually during the first four hours, and then daily until day 14. For the toxicity test with repeated doses, four groups of 10 rats were used. Doses of 100, 250, and 500 mg/kg/day were tested for 28 days. At the end of the experiment, blood was collected and the animals were sacrificed. Histopathological examination showed that in the lungs of rats given the 2,000 mg/kg bw dose, polymorph nuclear infiltrates, hemosiderin macrophages, and interstitial space thickening were present. In the repeated dose study, all rats survived the 28-day treatment period and apparently showed no signs of toxicity. The hematological and biochemical parameters were not altered. The histopathological study of the organs showed severe changes in the lung, with the dose of 500 mg/kg/day; in the other organs, no alterations were observed or the changes were slight. The body weight was only altered in male rats given the 500 mg/kg dose. The relative weight of the organs did not show any significant changes. Our studies revealed that the essential oil of Thymus vulgaris has moderate oral toxicity according to the results of the acute test, whereas the results of the 28-day oral toxicity test suggest that the no-observed-adverse effect level (NOAEL) is greater than 250 mg/kg/day.
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Affiliation(s)
- Juan Rojas-Armas
- Laboratory of Experimental Pharmacology, Institute of Clinical Research, Faculty of Medicine, National University of San Marcos, Lima, Peru
| | - Jorge Arroyo-Acevedo
- Laboratory of Experimental Pharmacology, Institute of Clinical Research, Faculty of Medicine, National University of San Marcos, Lima, Peru
| | - Manuel Ortiz-Sánchez
- Section of Physiology, Faculty of Medicine, National University of San Marcos, Lima, Peru
| | | | - Américo Castro-Luna
- Faculty of Pharmacy and Biochemistry, National University of San Marcos, Lima, Peru
| | - Norma Ramos-Cevallos
- Faculty of Pharmacy and Biochemistry, National University of San Marcos, Lima, Peru
| | - Hugo Justil-Guerrero
- Laboratory of Experimental Pharmacology, Institute of Clinical Research, Faculty of Medicine, National University of San Marcos, Lima, Peru
| | - Julio Hilario-Vargas
- Department of Physiology, School of Medicine, National University of Trujillo, Trujillo, Peru
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12
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Luo P, Wang L, Luo L, Wang L, Yang K, Shu G, Wang S, Zhu X, Gao P, Jiang Q. Ca2+-Calcineurin-NFAT pathway mediates the effect of thymol on oxidative metabolism and fiber-type switch in skeletal muscle. Food Funct 2019; 10:5166-5173. [DOI: 10.1039/c8fo02248h] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Thymol is a major component of thyme, and it has been reported that thymol administration reduces body weight, plasma insulin and blood glucose in type-2 diabetes.
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13
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Wang C, Yu T, Fujita T, Kumamoto E. Moieties of plant-derived compounds responsible for outward current production and TRPA1 activation in rat spinal substantia gelatinosa. Pharmacol Rep 2018; 71:67-72. [PMID: 30471518 DOI: 10.1016/j.pharep.2018.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 08/02/2018] [Accepted: 09/05/2018] [Indexed: 01/12/2023]
Abstract
BACKGROUND Transient receptor potential ankyrin-1 (TRPA1) channels expressed in the central terminal of dorsal root ganglion neurons in the spinal substantia gelatinosa (SG) play a role in modulating nociceptive transmission. Although plant-derived compounds exhibiting antinociception (such as eugenol, carvacrol and thymol) activate TRPA1 channels to enhance spontaneous excitatory transmission while hyperpolarizing membranes in SG neurons without TRPA1 activation, specific chemical moieties involved in synaptic modulation are unknown. METHODS We examined the effects of other plant-derived compounds (guaiacol, vanillin, vanillic acid and p-cymene) on holding current and spontaneous excitatory transmission at -70 mV by applying the whole-cell patch-clamp technique to SG neurons in adult rat spinal cord slices. RESULTS None of the compounds affected the frequency or amplitude of spontaneous excitatory postsynaptic current. Guaiacol and vanillic acid had no effect on holding currents, while vanillin and p-cymene produced an inward and outward current, respectively, in some neurons tested. Synaptic modulation was also observed within the same neuron as the activities of eugenol, carvacrol, thymol, and the chemically-related plant-derived compound zingerone occurred. CONCLUSION A substituted group in eugenol and zingerone, but not in guaiacol, vanillin or vanillic acid, as well as an OH bound to the benzene ring of carvacrol and thymol, but not p-cymene, play a role in producing outward current and TRPA1 activation. Thus, the binding of such chemical moeties to the benzene ring of plant-derived compounds appears necessary to modulate nociceptive transmission in the SG. This information provides insight for the development of new analgesics based on plant-derived compounds.
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Affiliation(s)
- Chong Wang
- Department of Physiology, Saga Medical School, Nabeshima, Saga, Japan
| | - Ting Yu
- Department of Physiology, Saga Medical School, Nabeshima, Saga, Japan
| | - Tsugumi Fujita
- Department of Physiology, Saga Medical School, Nabeshima, Saga, Japan
| | - Eiichi Kumamoto
- Department of Physiology, Saga Medical School, Nabeshima, Saga, Japan.
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14
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Wang ZJ, Heinbockel T. Essential Oils and Their Constituents Targeting the GABAergic System and Sodium Channels as Treatment of Neurological Diseases. Molecules 2018; 23:E1061. [PMID: 29724056 PMCID: PMC6099651 DOI: 10.3390/molecules23051061] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 03/28/2018] [Accepted: 04/27/2018] [Indexed: 12/27/2022] Open
Abstract
Essential oils and the constituents in them exhibit different pharmacological activities, such as antinociceptive, anxiolytic-like, and anticonvulsant effects. They are widely applied as a complementary therapy for people with anxiety, insomnia, convulsion, pain, and cognitive deficit symptoms through inhalation, oral administration, and aromatherapy. Recent studies show that essential oils are emerging as a promising source for modulation of the GABAergic system and sodium ion channels. This review summarizes the recent findings regarding the pharmacological properties of essential oils and compounds from the oils and the mechanisms underlying their effects. Specifically, the review focuses on the essential oils and their constituents targeting the GABAergic system and sodium channels, and their antinociceptive, anxiolytic, and anticonvulsant properties. Some constituents target transient receptor potential (TRP) channels to exert analgesic effects. Some components could interact with multiple therapeutic target proteins, for example, inhibit the function of sodium channels and, at the same time, activate GABAA receptors. The review concentrates on perspective compounds that could be better candidates for new drug development in the control of pain and anxiety syndromes.
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Affiliation(s)
- Ze-Jun Wang
- Department of Anatomy, Howard University College of Medicine, 520 W Str., NW, Washington, DC 20059, USA.
| | - Thomas Heinbockel
- Department of Anatomy, Howard University College of Medicine, 520 W Str., NW, Washington, DC 20059, USA.
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15
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Analgesic-Like Activity of Essential Oil Constituents: An Update. Int J Mol Sci 2017; 18:ijms18122392. [PMID: 29232831 PMCID: PMC5751100 DOI: 10.3390/ijms18122392] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 11/03/2017] [Accepted: 11/03/2017] [Indexed: 12/18/2022] Open
Abstract
The constituents of essential oils are widely found in foods and aromatic plants giving characteristic odor and flavor. However, pharmacological studies evidence its therapeutic potential for the treatment of several diseases and promising use as compounds with analgesic-like action. Considering that pain affects a significant part of the world population and the need for the development of new analgesics, this review reports on the current studies of essential oils’ chemical constituents with analgesic-like activity, including a description of their mechanisms of action and chemical aspects.
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16
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Nagoor Meeran MF, Javed H, Al Taee H, Azimullah S, Ojha SK. Pharmacological Properties and Molecular Mechanisms of Thymol: Prospects for Its Therapeutic Potential and Pharmaceutical Development. Front Pharmacol 2017; 8:380. [PMID: 28694777 PMCID: PMC5483461 DOI: 10.3389/fphar.2017.00380] [Citation(s) in RCA: 236] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 05/31/2017] [Indexed: 12/22/2022] Open
Abstract
Thymol, chemically known as 2-isopropyl-5-methylphenol is a colorless crystalline monoterpene phenol. It is one of the most important dietary constituents in thyme species. For centuries, it has been used in traditional medicine and has been shown to possess various pharmacological properties including antioxidant, free radical scavenging, anti-inflammatory, analgesic, antispasmodic, antibacterial, antifungal, antiseptic and antitumor activities. The present article presents a detailed review of the scientific literature which reveals the pharmacological properties of thymol and its multiple therapeutic actions against various cardiovascular, neurological, rheumatological, gastrointestinal, metabolic and malignant diseases at both biochemical and molecular levels. The noteworthy effects of thymol are largely attributed to its anti-inflammatory (via inhibiting recruitment of cytokines and chemokines), antioxidant (via scavenging of free radicals, enhancing the endogenous enzymatic and non-enzymatic antioxidants and chelation of metal ions), antihyperlipidemic (via increasing the levels of high density lipoprotein cholesterol and decreasing the levels of low density lipoprotein cholesterol and low density lipoprotein cholesterol in the circulation and membrane stabilization) (via maintaining ionic homeostasis) effects. This review presents an overview of the current in vitro and in vivo data supporting thymol's therapeutic activity and the challenges concerning its use for prevention and its therapeutic value as a dietary supplement or as a pharmacological agent or as an adjuvant along with current therapeutic agents for the treatment of various diseases. It is one of the potential candidates of natural origin that has shown promising therapeutic potential, pharmacological properties and molecular mechanisms as well as pharmacokinetic properties for the pharmaceutical development of thymol.
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Affiliation(s)
- Mohamed Fizur Nagoor Meeran
- Department of Pharmacology and Therapeutics, College of Medicine and Health Science, United Arab Emirates UniversityAl Ain, United Arab Emirates
| | - Hayate Javed
- Department of Biochemistry, College of Medicine and Health Science, United Arab Emirates UniversityAl Ain, United Arab Emirates
| | - Hasan Al Taee
- Department of Pharmacology and Therapeutics, College of Medicine and Health Science, United Arab Emirates UniversityAl Ain, United Arab Emirates
| | - Sheikh Azimullah
- Department of Pharmacology and Therapeutics, College of Medicine and Health Science, United Arab Emirates UniversityAl Ain, United Arab Emirates
| | - Shreesh K. Ojha
- Department of Pharmacology and Therapeutics, College of Medicine and Health Science, United Arab Emirates UniversityAl Ain, United Arab Emirates
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Denner AC, Vogler B, Messlinger K, De Col R. Role of transient receptor potential ankyrin 1 receptors in rodent models of meningeal nociception - Experiments in vitro. Eur J Pain 2016; 21:843-854. [PMID: 27977070 DOI: 10.1002/ejp.986] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND The TRP channel ankyrin type 1 (TRPA1) is a nonselective cation channel known to be activated by environmental irritants, cold and endogenous mediators of inflammation. Activation of TRPA1 in trigeminal afferents innervating meningeal structures has recently been suggested to be involved in the generation of headaches. METHODS Two in vitro models of meningeal nociception were employed using the hemisected rodent head preparation, (1) recording of single meningeal afferents and (2) release of calcitonin gene-related peptide (CGRP) from the cranial dura mater. The role of TRPA1 was examined using the TRPA1 agonists acrolein and mustard oil (MO). BCTC, an inhibitor of TRP vanilloid type 1 receptor channels (TRPV1), and the TRPA1 inhibitor HC030031 as well as mice with genetically deleted TRPA1 and TRPV1 proteins, were used to differentiate between effects. RESULTS Acrolein did not cause discharge activity in meningeal Aδ- or C-fibres but increased the electrical activation threshold. Acrolein was also effective in releasing CGRP from the dura of TRPV1-/- but not of TRPA1-/- mice. MO increased the discharge activity of afferent fibres from rat as well as C57 wild-type and TRPA1-/- but not TRPV1-/- mice. The effect was higher in C57 compared to TRPA1-/- mice. CONCLUSION Sole TRPA1 receptor channel activation releases CGRP and increases the activation threshold of meningeal afferents but does not generate propagated activity, and so would be capable of causing local effects like vasodilatation but not pain generation. In contrast, combined TRPA1 and TRPV1 activation may be rather pronociceptive supporting headache generation. SIGNIFICANCE Sole activation of TRPA1 receptor channels increases the activation threshold but does not cause propagated action potentials in meningeal afferents. TRPA1 agonists cause CGRP release from rodent dura mater. Peripheral TRPA1 receptors may have a pronociceptive function in trigeminal nociception only in combination with TRPV1.
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Affiliation(s)
- A C Denner
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Germany
| | - B Vogler
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Germany
| | - K Messlinger
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Germany
| | - R De Col
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Germany
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Enhancement by citral of glutamatergic spontaneous excitatory transmission in adult rat substantia gelatinosa neurons. Neuroreport 2016; 27:166-71. [PMID: 26720890 DOI: 10.1097/wnr.0000000000000518] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Although citral, which is abundantly present in lemongrass, has various actions including antinociception, how citral affects synaptic transmission has not been examined as yet. Citral activates in heterologous cells transient receptor potential vanilloid-1, ankyrin-1, and melastatin-8 (TRPV1, TRPA1, and TRPM8, respectively) channels, the activation of which in the spinal lamina II [substantia gelatinosa (SG)] increases the spontaneous release of L-glutamate from nerve terminals. It remains to be examined what types of transient receptor potential channel in native neurons are activated by citral. With a focus on transient receptor potential activation, we examined the effect of citral on glutamatergic spontaneous excitatory transmission using the whole-cell patch-clamp technique to SG neurons in adult rat spinal cord slices. Bath-applied citral for 3 min increased the frequency of spontaneous excitatory postsynaptic current in a concentration-dependent manner (half-maximal effective concentration=0.58 mM), with a small increase in its amplitude. The spontaneous excitatory postsynaptic current frequency increase produced by citral was repeated at a time interval of 30 min, albeit this action recovered with a slow time course after washout. The presynaptic effect of citral was inhibited by TRPA1 antagonist HC-030031, but not by voltage-gated Na-channel blocker tetrodotoxin, TRPV1 antagonist capsazepine, and TRPM8 antagonist BCTC. It is concluded that citral increases spontaneous L-glutamate release in SG neurons by activating TRPA1 channels. Considering that the SG plays a pivotal role in modulating nociceptive transmission from the periphery, the citral activity could contribute toward at least a part of the modulation.
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Differential Activation of TRP Channels in the Adult Rat Spinal Substantia Gelatinosa by Stereoisomers of Plant-Derived Chemicals. Pharmaceuticals (Basel) 2016; 9:ph9030046. [PMID: 27483289 PMCID: PMC5039499 DOI: 10.3390/ph9030046] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 06/19/2016] [Accepted: 07/25/2016] [Indexed: 02/07/2023] Open
Abstract
Activation of TRPV1, TRPA1 or TRPM8 channel expressed in the central terminal of dorsal root ganglion (DRG) neuron increases the spontaneous release of l-glutamate onto spinal dorsal horn lamina II (substantia gelatinosa; SG) neurons which play a pivotal role in regulating nociceptive transmission. The TRP channels are activated by various plant-derived chemicals. Although stereoisomers activate or modulate ion channels in a distinct manner, this phenomenon is not fully addressed for TRP channels. By applying the whole-cell patch-clamp technique to SG neurons of adult rat spinal cord slices, we found out that all of plant-derived chemicals, carvacrol, thymol, carvone and cineole, increase the frequency of spontaneous excitatory postsynaptic current, a measure of the spontaneous release of l-glutamate from nerve terminals, by activating TRP channels. The presynaptic activities were different between stereoisomers (carvacrol and thymol; (-)-carvone and (+)-carvone; 1,8-cineole and 1,4-cineole) in the extent or the types of TRP channels activated, indicating that TRP channels in the SG are activated by stereoisomers in a distinct manner. This result could serve to know the properties of the central terminal TRP channels that are targets of drugs for alleviating pain.
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