1
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Lotierzo MCG, Casadei BR, de Castro RD, Malheiros B, Barbosa LRS. Cubic-to-inverted micellar and the cubic-to-hexagonal-to-micellar transitions on phytantriol-based cubosomes induced by solvents. Drug Deliv Transl Res 2020; 10:1571-1583. [PMID: 32783155 DOI: 10.1007/s13346-020-00828-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cubosomes are nanoparticles composed of a specific combination of some types of amphiphilic molecules like lipids, such as phytantriol (PHY), and a nonionic polymer, like poloxamer (F127). Cubosomes have a high hydrophobic volume (> 50%) and are good candidates for drug delivery systems. Due to their unique structure, these nanoparticles possess the ability to incorporate highly hydrophobic drugs. A challenge for the encapsulation of hydrophobic molecules is the use of organic solvents in the sample preparation process. In this study, we investigated the structural influence of four different solvents (acetone, ethanol, chloroform, and octane), by means of small-angle X-ray scattering and cryogenic electron microscopy techniques. In the presence of a high amount of acetone and ethanol (1:5 solvent:PHY volumetric ratio), for instance, a cubic-to-micellar phase transition was observed due to the high presence of these two solvents. Chloroform and octane have different effects over PHY-based cubosomes as compared to acetone and ethanol, both of them induced a cubic-to-inverse hexagonal phase transition. Those effects are attributed to the insertion of the solvent in the hydrophobic region of the cubosomes, increasing its volume and inducing such transition. Moreover, a second phase transition from reversed hexagonal-to-inverted micellar was observed for chloroform and octane. The data also suggest that after 24 h of solvent/cubosome incubation, some structural features of cubosomes change as compared to the freshly prepared samples. This study could shed light on drug delivery systems using PHY-based cubosomes to choose the appropriate solvent in order to load the drug into the cubosome.Graphical abstract.
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Affiliation(s)
- Mayra C G Lotierzo
- Department of Biochemical and Pharmaceutical Technology, University of São Paulo, Av. Prof. Lineu Prestes n 580 Bloco 16, São Paulo, SP, 05508-000, Brazil
| | - Bruna R Casadei
- Institute of Physics, University of São Paulo, Rua do Matão, 1371, São Paulo, 05508-090, Brazil
| | - Raphael Dias de Castro
- Department of Biochemical and Pharmaceutical Technology, University of São Paulo, Av. Prof. Lineu Prestes n 580 Bloco 16, São Paulo, SP, 05508-000, Brazil.,Institute of Physics, University of São Paulo, Rua do Matão, 1371, São Paulo, 05508-090, Brazil
| | - Barbara Malheiros
- Department of Biochemical and Pharmaceutical Technology, University of São Paulo, Av. Prof. Lineu Prestes n 580 Bloco 16, São Paulo, SP, 05508-000, Brazil
| | - Leandro R S Barbosa
- Department of Biochemical and Pharmaceutical Technology, University of São Paulo, Av. Prof. Lineu Prestes n 580 Bloco 16, São Paulo, SP, 05508-000, Brazil. .,Institute of Physics, University of São Paulo, Rua do Matão, 1371, São Paulo, 05508-090, Brazil.
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2
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Bosson C, Rendu J, Pelletier L, Abriat A, Chatagnon A, Brocard J, Brocard J, Figarella-Branger D, Ducreux S, van Coppenolle F, Sagui E, Marty I, Roux-Buisson N, Faure J. Variations in the TRPV1 gene are associated to exertional heat stroke. J Sci Med Sport 2020; 23:1021-1027. [PMID: 32471784 DOI: 10.1016/j.jsams.2020.04.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 04/20/2020] [Accepted: 04/23/2020] [Indexed: 10/24/2022]
Abstract
OBJECTIVES Exertional Heat Stroke (EHS) is one of the top three causes of sudden death in athletes. Extrinsic and intrinsic risk factors have been identified but the genetic causes still remain unclear. Our aim was to identify genes responsible for EHS, which is a necessary step to identify patients at risk and prevent crises. DESIGN Genetic and functional laboratory studies METHODS: Whole Exome Sequencing (WES) was performed to search for candidate genes in a cohort of 15 soldiers who had a documented EHS episode. In silico and in vitro functional studies were performed to evaluate the effect of mutations identified in the candidate gene TRPV1. RESULTS WES led to the identification of two missense variations in the TRPV1 gene. These variations were very rare or unreported in control databases and located in critical domains of the protein. In vitro functional studies revealed that both variations induce a strong modification of the channel response to one of its natural agonist, the capsaicin. CONCLUSIONS We evidenced mutations altering channel properties of the TRPV1 gene and demonstrated that TRPV1, which is involved in thermoregulation and nociception, is a new candidate gene for EHS. Our data provide the bases to explore genetic causes and molecular mechanisms governing the pathophysiology of EHS.
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Affiliation(s)
- Caroline Bosson
- CHU Grenoble Alpes IBP, Génétique Moléculaire : Maladies Héréditaires et Oncologie, France; Grenoble Institute of Neurosciences, Inserm U1216, Cellular Myology and Pathology, Grenoble Alpes, University, Grenoble, France
| | - John Rendu
- CHU Grenoble Alpes IBP, Génétique Moléculaire : Maladies Héréditaires et Oncologie, France; Grenoble Institute of Neurosciences, Inserm U1216, Cellular Myology and Pathology, Grenoble Alpes, University, Grenoble, France
| | - Laurent Pelletier
- Grenoble Institute of Neurosciences, Inserm U1216, Cellular Myology and Pathology, Grenoble Alpes, University, Grenoble, France
| | - Amandine Abriat
- Military Hospital Laveran, Service of Neurology, Marseille, France
| | - Amandine Chatagnon
- CHU Grenoble Alpes IBP, Génétique Moléculaire : Maladies Héréditaires et Oncologie, France
| | - Julie Brocard
- Grenoble Institute of Neurosciences, Inserm U1216, Cellular Myology and Pathology, Grenoble Alpes, University, Grenoble, France
| | - Jacques Brocard
- Grenoble Institute of Neurosciences, Inserm U1216, Cellular Myology and Pathology, Grenoble Alpes, University, Grenoble, France
| | - Dominique Figarella-Branger
- Aix-Marseille Univ, APHM, CNRS, INP, Inst Neurophysiopathol, Hôpital de la Timone, Service d'Anatomie Pathologique et de Neuropathologie, Marseille, France; Univ Aix-Marseille I, France
| | - Sylvie Ducreux
- Univ Lyon, CarMeN Laboratory, INSERM, INRA, INSA, Lyon, Université Claude Bernard, Bron, France
| | - Fabien van Coppenolle
- Univ Lyon, CarMeN Laboratory, INSERM, INRA, INSA, Lyon, Université Claude Bernard, Bron, France
| | | | - Isabelle Marty
- Grenoble Institute of Neurosciences, Inserm U1216, Cellular Myology and Pathology, Grenoble Alpes, University, Grenoble, France
| | - Nathalie Roux-Buisson
- CHU Grenoble Alpes IBP, Génétique Moléculaire : Maladies Héréditaires et Oncologie, France; Grenoble Institute of Neurosciences, Inserm U1216, Cellular Myology and Pathology, Grenoble Alpes, University, Grenoble, France.
| | - Julien Faure
- CHU Grenoble Alpes IBP, Génétique Moléculaire : Maladies Héréditaires et Oncologie, France; Grenoble Institute of Neurosciences, Inserm U1216, Cellular Myology and Pathology, Grenoble Alpes, University, Grenoble, France
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3
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Kelemen B, Lisztes E, Vladár A, Hanyicska M, Almássy J, Oláh A, Szöllősi AG, Pénzes Z, Posta J, Voets T, Bíró T, Tóth BI. Volatile anaesthetics inhibit the thermosensitive nociceptor ion channel transient receptor potential melastatin 3 (TRPM3). Biochem Pharmacol 2020; 174:113826. [PMID: 31987857 DOI: 10.1016/j.bcp.2020.113826] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 01/22/2020] [Indexed: 12/21/2022]
Abstract
BACKGROUND Volatile anaesthetics (VAs) are the most widely used compounds to induce reversible loss of consciousness and maintain general anaesthesia during surgical interventions. Although the mechanism of their action is not yet fully understood, it is generally believed, that VAs depress central nervous system functions mainly through modulation of ion channels in the neuronal membrane, including 2-pore-domain K+ channels, GABA and NMDA receptors. Recent research also reported their action on nociceptive and thermosensitive TRP channels expressed in the peripheral nervous system, including TRPV1, TRPA1, and TRPM8. Here, we investigated the effect of VAs on TRPM3, a less characterized member of the thermosensitive TRP channels playing a central role in noxious heat sensation. METHODS We investigated the effect of VAs on the activity of recombinant and native TRPM3, by monitoring changes in the intracellular Ca2+ concentration and measuring TRPM3-mediated transmembrane currents. RESULTS All the investigated VAs (chloroform, halothane, isoflurane, sevoflurane) inhibited both the agonist-induced (pregnenolone sulfate, CIM0216) and heat-activated Ca2+ signals and transmembrane currents in a concentration dependent way in HEK293T cells overexpressing recombinant TRPM3. Among the tested VAs, halothane was the most potent blocker (IC50 = 0.52 ± 0.05 mM). We also investigated the effect of VAs on native TRPM3 channels expressed in sensory neurons of the dorsal root ganglia. While VAs activated certain sensory neurons independently of TRPM3, they strongly and reversibly inhibited the agonist-induced TRPM3 activity. CONCLUSIONS These data provide a better insight into the molecular mechanism beyond the analgesic effect of VAs and propose novel strategies to attenuate TRPM3 dependent nociception.
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Affiliation(s)
- Balázs Kelemen
- Laboratory of Cellular and Molecular Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Erika Lisztes
- Laboratory of Cellular and Molecular Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Anita Vladár
- Laboratory of Cellular and Molecular Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Martin Hanyicska
- Laboratory of Cellular and Molecular Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - János Almássy
- Laboratory of Cellular and Molecular Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Oláh
- Laboratory of Cellular and Molecular Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Gábor Szöllősi
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zsófia Pénzes
- Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary; Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Posta
- Laboratory of Toxicology, Department of Forensic Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Thomas Voets
- Laboratory of Ion Channel Research, VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium; Department of Cellular and Molecular Medicine and TRP Research Platform Leuven (TRPLe), KU Leuven, Leuven, Belgium
| | - Tamás Bíró
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Hungarian Center of Excellence for Molecular Medicine, Szeged, Hungary
| | - Balázs István Tóth
- Laboratory of Cellular and Molecular Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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4
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Zhao P, Liu XM, Sun QC, Cui YF. Overactivation of the sodium-calcium exchanger and transient receptor potential in anesthesia-induced malignant hyperthermia. IUBMB Life 2019; 71:2048-2054. [PMID: 31381266 DOI: 10.1002/iub.2138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 07/11/2019] [Indexed: 11/09/2022]
Abstract
Malignant hyperthermia is a pharmacogenetic disorder, which is an uncommon but frequently fatal intricacy of inhalation anesthesia in man. It causes a quick rise in body temperature to highly irreversible levels, which causes death in around three of four cases. The trigger anesthetics cause an anomalous, continued ascent in myoplasmic calcium levels. Possible mechanisms by which continuous release of sodium, calcium from skeletal muscle plasma membrane and sarcoplasmic reticulum stores respectively can produce the profound hyperthermia are discussed.
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Affiliation(s)
- Peng Zhao
- Department of Anesthesiology, The Second Hospital of Jilin University, Changchun, Jilin, China
| | - Xiu-Min Liu
- Department of Clinical Laboratory, The Second Hospital of Jilin University, Changchun, Jilin, China
| | - Qian-Chuang Sun
- Department of Anesthesiology, The Second Hospital of Jilin University, Changchun, Jilin, China
| | - Yun-Feng Cui
- Department of Anesthesiology, The Second Hospital of Jilin University, Changchun, Jilin, China
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5
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Robering JW, Gebhardt L, Wolf K, Kühn H, Kremer AE, Fischer MJM. Lysophosphatidic acid activates satellite glia cells and Schwann cells. Glia 2019; 67:999-1012. [PMID: 30637823 DOI: 10.1002/glia.23585] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 12/14/2018] [Accepted: 12/20/2018] [Indexed: 12/16/2022]
Abstract
Pruritus is a common and disabling symptom in patients with hepatobiliary disorders, particularly in those with cholestatic features. Serum levels of lysophosphatidic acid (LPA) and its forming enzyme autotaxin were increased in patients suffering from hepatic pruritus, correlated with itch severity and response to treatment. Here we show that in a culture of dorsal root ganglia LPA 18:1 surprisingly activated a large fraction of satellite glia cells, and responses to LPA 18:1 correlated inversely with responses to neuronal expressed transient receptor potential channels. LPA 18:1 caused only a marginal activation of heterologously expressed TRPV1, and responses in dorsal root ganglion cultures from TRPV1-deficient mice were similar to controls. LPA 18:1 desensitized subsequent responsiveness to chloroquine and TGR5 agonist INT-777. The LPA 18:1-induced increase in cytoplasmatic calcium stems from the endoplasmatic reticulum. LPA receptor expression in dorsal root ganglia and Schwann cells, LPAR1 immunohistochemistry, and pharmacological results indicate a signaling pathway through LPA receptor 1. Peripheral rat Schwann cells, which are of glial lineage as the satellite glia cells, were also responsive to LPA 18:1. Summarizing, LPA 18:1 primarily activates rather glial cells than neurons, which may subsequently modulate neuronal responsiveness and sensory sensations such as itch and pain.
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Affiliation(s)
- Jan W Robering
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Lisa Gebhardt
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany.,Department of Medicine 1, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Katharina Wolf
- Department of Medicine 1, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Helen Kühn
- Department of Medicine 1, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas E Kremer
- Department of Medicine 1, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Michael J M Fischer
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany.,Center for Physiology and Pharmacology, University of Vienna, Vienna, Austria
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6
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Jorgensen C, Domene C. Location and Character of Volatile General Anesthetics Binding Sites in the Transmembrane Domain of TRPV1. Mol Pharm 2018; 15:3920-3930. [PMID: 30067911 DOI: 10.1021/acs.molpharmaceut.8b00381] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
It has been proposed that general anesthesia results from direct multisite interactions with multiple and diverse ion channels in the brain. An understanding of the mechanisms by which general anesthetics modulate ion channels is essential to clarify their underlying behavior and their role in reversible immobilization and amnesia. Despite the fact that volatile general anesthetics are drugs that primarily induce insensitivity to pain, they have been reported to sensitize and active the vanilloid-1 receptor, TRPV1, which is known to mediate the response of the nervous system to certain harmful stimuli and which plays a crucial role in the pain pathway. Currently, the mechanism of action of anesthetics is unknown and the precise molecular sites of interaction have not been identified. Here, using ∼2.5 μs of classical molecular dynamics simulations and metadynamics, we explore these enigmas. Binding sites are identified and the strength of the association is further characterized using alchemical free-energy calculations. Anesthetic binding/unbinding proceeds primarily through a membrane-embedded pathway, and subsequently, a complex scenario is established involving multiple binding sites featuring single or multiple occupancy states of two small volatile drugs. One of the five anesthetic binding sites reported was previously identified experimentally, and another one, importantly, is identical to that of capsaicin, one of the chemical stimuli that activate TRPV1. However, in contrast to capsaicin, isoflurane and chloroform binding free-energies render modest to no association compared to capsaicin, suggesting a different activation mechanism. Uncovering chloroform and isoflurane modulatory sites will further our understanding of the TRPV1 molecular machinery and open the possibility of developing site-specific drugs.
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Affiliation(s)
- Christian Jorgensen
- Department of Chemistry , King's College London , Britannia House, 7 Trinity Street , London SE1 1DB , U.K
| | - Carmen Domene
- Department of Chemistry , King's College London , Britannia House, 7 Trinity Street , London SE1 1DB , U.K.,Department of Chemistry , University of Bath , 1 South Building, Claverton Down , Bath BA2 7AY , U.K.,Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , U.K
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7
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Steinritz D, Stenger B, Dietrich A, Gudermann T, Popp T. TRPs in Tox: Involvement of Transient Receptor Potential-Channels in Chemical-Induced Organ Toxicity-A Structured Review. Cells 2018; 7:cells7080098. [PMID: 30087301 PMCID: PMC6115949 DOI: 10.3390/cells7080098] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/24/2018] [Accepted: 07/31/2018] [Indexed: 12/28/2022] Open
Abstract
Chemicals can exhibit significant toxic properties. While for most compounds, unspecific cell damaging processes are assumed, a plethora of chemicals exhibit characteristic odors, suggesting a more specific interaction with the human body. During the last few years, G-protein-coupled receptors and especially chemosensory ion channels of the transient receptor potential family (TRP channels) were identified as defined targets for several chemicals. In some cases, TRP channels were suggested as being causal for toxicity. Therefore, these channels have moved into the spotlight of toxicological research. In this review, we screened available literature in PubMed that deals with the role of chemical-sensing TRP channels in specific organ systems. TRPA1, TRPM and TRPV channels were identified as essential chemosensors in the nervous system, the upper and lower airways, colon, pancreas, bladder, skin, the cardiovascular system, and the eyes. Regarding TRP channel subtypes, A1, M8, and V1 were found most frequently associated with toxicity. They are followed by V4, while other TRP channels (C1, C4, M5) are only less abundantly expressed in this context. Moreover, TRPA1, M8, V1 are co-expressed in most organs. This review summarizes organ-specific toxicological roles of TRP channels.
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Affiliation(s)
- Dirk Steinritz
- Bundeswehr Institute of Pharmacology and Toxicology, 80937 Munich, Germany.
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität Munich, 80336 Munich, Germany.
| | - Bernhard Stenger
- Bundeswehr Institute of Pharmacology and Toxicology, 80937 Munich, Germany.
| | - Alexander Dietrich
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität Munich, 80336 Munich, Germany.
| | - Thomas Gudermann
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität Munich, 80336 Munich, Germany.
| | - Tanja Popp
- Bundeswehr Institute of Pharmacology and Toxicology, 80937 Munich, Germany.
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität Munich, 80336 Munich, Germany.
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8
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TRPV1 variants impair intracellular Ca 2+ signaling and may confer susceptibility to malignant hyperthermia. Genet Med 2018; 21:441-450. [PMID: 29930394 PMCID: PMC6752298 DOI: 10.1038/s41436-018-0066-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 05/04/2018] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Malignant hyperthermia (MH) is a pharmacogenetic disorder arising from uncontrolled muscle calcium release due to an abnormality in the sarcoplasmic reticulum (SR) calcium-release mechanism triggered by halogenated inhalational anesthetics. However, the molecular mechanisms involved are still incomplete. METHODS We aimed to identify transient receptor potential vanilloid 1 (TRPV1) variants within the entire coding sequence in patients who developed sensitivity to MH of unknown etiology. In vitro and in vivo functional studies were performed in heterologous expression system, trpv1-/- mice, and a murine model of human MH. RESULTS We identified TRPV1 variants in two patients and their heterologous expression in muscles of trpv1-/- mice strongly enhanced calcium release from SR upon halogenated anesthetic stimulation, suggesting they could be responsible for the MH phenotype. We confirmed the in vivo significance by using mice with a knock-in mutation (Y524S) in the type I ryanodine receptor (Ryr1), a mutation analogous to the Y522S mutation associated with MH in humans. We showed that the TRPV1 antagonist capsazepine slows the heat-induced hypermetabolic response in this model. CONCLUSION We propose that TRPV1 contributes to MH and could represent an actionable therapeutic target for prevention of the pathology and also be responsible for MH sensitivity when mutated.
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9
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Esancy K, Condon L, Feng J, Kimball C, Curtright A, Dhaka A. A zebrafish and mouse model for selective pruritus via direct activation of TRPA1. eLife 2018; 7:32036. [PMID: 29561265 PMCID: PMC5912907 DOI: 10.7554/elife.32036] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 03/19/2018] [Indexed: 11/13/2022] Open
Abstract
Little is known about the capacity of lower vertebrates to experience itch. A screen of itch-inducing compounds (pruritogens) in zebrafish larvae yielded a single pruritogen, the TLR7 agonist imiquimod, that elicited a somatosensory neuron response. Imiquimod induced itch-like behaviors in zebrafish distinct from those induced by the noxious TRPA1 agonist, allyl isothiocyanate. In the zebrafish, imiquimod-evoked somatosensory neuronal responses and behaviors were entirely dependent upon TRPA1, while in the mouse TRPA1 was required for the direct activation of somatosensory neurons and partially responsible for behaviors elicited by this pruritogen. Imiquimod was found to be a direct but weak TRPA1 agonist that activated a subset of TRPA1 expressing neurons. Imiquimod-responsive TRPA1 expressing neurons were significantly more sensitive to noxious stimuli than other TRPA1 expressing neurons. Together, these results suggest a model for selective itch via activation of a specialized subpopulation of somatosensory neurons with a heightened sensitivity to noxious stimuli. Itch is a common and uncomfortable sensation that creates a strong desire to scratch. This mechanism may have evolved so animals can remove harmful parasites or substances from themselves. Feelings like touch, pain, and itch arise when stimuli such as mechanical pressure, temperature, or chemicals activate groups of specialized neurons in the skin. This response takes place when certain proteins – or receptors – at the surface of the neurons are stimulated. For instance, TRP ion channels such as TRPA1 play an important role in both the itch and pain responses. In mammals, directly activating these channels elicits pain. Itch is felt when itch responsive receptors are activated on a distinct set of neurons, which in turn activate TRP receptors. Although these processes have been well-studied in mammals, little is known about the existence of itch sensation in other animals. To explore this, Esancy, Condon, Feng et al. exposed zebrafish to chemicals that induce itch in mammals, and found that imiquimod, a medicine used to treat certain skin conditions, can elicit itch in fish. When this chemical was injected into the lips of a fish, the animal rubbed them against the walls of its tank, akin to scratching an itch. Further experiments showed that imiquimod directly activated the pain-sensing ion channel TRPA1. In fact, this receptor was essential to the ‘scratching’ behavior: fish genetically engineered to lack TRPA1 did not react to the drug. Fluorescent proteins were then used to track when the neurons that carry TRPA1 were activated.This revealed that, in the skin of zebrafish, there are at least two functionally distinct populations neurons that express TRPA1. One population, whose activation is associated with the animal ‘scratching’, responds even when TRPA1 receives a low level of stimulation. The other population is less sensitive: it responds only to high-intensity stimuli and is associated with a pain response such as freezing and slower movements. Further experiments in the mouse suggest that this mechanism is present in mammals as well. This coding strategy explains how pain and itch can be experienced when the same receptors are being activated. Studying how animals like fish experience itch gives an insight into how detecting these sensations could have evolved. In turn, understanding this mechanism at the molecular and cellular levels may help find new ways to design better treatments for itch and pain disorders.
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Affiliation(s)
- Kali Esancy
- Department of Biological Structure, University of Washington, Seattle, United States.,Graduate Program in Neuroscience, University of Washington, Seattle, United States
| | - Logan Condon
- Department of Biological Structure, University of Washington, Seattle, United States
| | - Jing Feng
- Center for the Study of Itch, Washington University, St. Louis, United States
| | - Corinna Kimball
- Department of Biological Structure, University of Washington, Seattle, United States
| | - Andrew Curtright
- Department of Biological Structure, University of Washington, Seattle, United States
| | - Ajay Dhaka
- Department of Biological Structure, University of Washington, Seattle, United States.,Graduate Program in Neuroscience, University of Washington, Seattle, United States
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10
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Transient Receptor Potential Vanilloid 1 Antagonists Prevent Anesthesia-induced Hypothermia and Decrease Postincisional Opioid Dose Requirements in Rodents. Anesthesiology 2017; 127:813-823. [DOI: 10.1097/aln.0000000000001812] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Abstract
Background
Intraoperative hypothermia and postoperative pain control are two important clinical challenges in anesthesiology. Transient receptor potential vanilloid 1 has been implicated both in thermoregulation and pain. Transient receptor potential vanilloid 1 antagonists were not advanced as analgesics in humans in part due to a side effect of hyperthermia. This study tested the hypothesis that a single, preincision injection of a transient receptor potential vanilloid 1 antagonist could prevent anesthesia-induced hypothermia and decrease the opioid requirement for postsurgical hypersensitivity.
Methods
General anesthesia was induced in rats and mice with either isoflurane or ketamine, and animals were treated with transient receptor potential vanilloid 1 antagonists (AMG 517 or ABT-102). The core body temperature and oxygen consumption were monitored during anesthesia and the postanesthesia period. The effect of preincision AMG 517 on morphine-induced reversal of postincision hyperalgesia was evaluated in rats.
Results
AMG 517 and ABT-102 dose-dependently prevented general anesthesia-induced hypothermia (mean ± SD; from 1.5° ± 0.1°C to 0.1° ± 0.1°C decrease; P < 0.001) without causing hyperthermia in the postanesthesia phase. Isoflurane-induced hypothermia was prevented by AMG 517 in wild-type but not in transient receptor potential vanilloid 1 knockout mice (n = 7 to 11 per group). The prevention of anesthesia-induced hypothermia by AMG 517 involved activation of brown fat thermogenesis with a possible contribution from changes in vasomotor tone. A single preincision dose of AMG 517 decreased the morphine dose requirement for the reduction of postincision thermal (12.6 ± 3.0 vs. 15.6 ± 1.0 s) and mechanical (6.8 ± 3.0 vs. 9.5 ± 3.0 g) withdrawal latencies.
Conclusions
These studies demonstrate that transient receptor potential vanilloid 1 antagonists prevent anesthesia-induced hypothermia and decrease opioid dose requirements for the reduction of postincisional hypersensitivity in rodents.
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Integrating TRPV1 Receptor Function with Capsaicin Psychophysics. Adv Pharmacol Sci 2016; 2016:1512457. [PMID: 26884754 PMCID: PMC4738735 DOI: 10.1155/2016/1512457] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 12/10/2015] [Indexed: 01/17/2023] Open
Abstract
Capsaicin is a naturally occurring vanilloid that causes a hot, pungent sensation in the human oral cavity. This trigeminal stimulus activates TRPV1 receptors and stimulates an influx of cations into sensory cells. TRPV1 receptors function as homotetramers that also respond to heat, proinflammatory substances, lipoxygenase products, resiniferatoxin, endocannabinoids, protons, and peptide toxins. Kinase-mediated phosphorylation of TRPV1 leads to increased sensitivity to both chemical and thermal stimuli. In contrast, desensitization occurs via a calcium-dependent mechanism that results in receptor dephosphorylation. Human psychophysical studies have shown that capsaicin is detected at nanomole amounts and causes desensitization in the oral cavity. Psychophysical studies further indicate that desensitization can be temporarily reversed in the oral cavity if stimulation with capsaicin is resumed at short interstimulus intervals. Pretreatment of lingual epithelium with capsaicin modulates the perception of several primary taste qualities. Also, sweet taste stimuli may decrease the intensity of capsaicin perception in the oral cavity. In addition, capsaicin perception and hedonic responses may be modified by diet. Psychophysical studies with capsaicin are consistent with recent findings that have identified TRPV1 channel modulation by phosphorylation and interactions with membrane inositol phospholipids. Future studies will further clarify the importance of capsaicin and its receptor in human health and nutrition.
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Ferreira LGB, Faria RX. TRPing on the pore phenomenon: what do we know about transient receptor potential ion channel-related pore dilation up to now? J Bioenerg Biomembr 2016; 48:1-12. [PMID: 26728159 DOI: 10.1007/s10863-015-9634-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 12/02/2015] [Indexed: 01/06/2023]
Abstract
Ion channels allow for rapid ion diffusion through the plasma membrane. In some conditions, ion channels induce changes in the critical plasma membrane permeability that permit 900-Da solutes to enter cells. This process is known as the pore phenomenon. Some transient receptor potential (TRP) channel subtypes have been highlighted such as the P2X7 receptor, plasma membrane VDAC-1 channel, and pannexin hemichannels. The TRP ion channels are considered multimodal transducers that respond to several kinds of stimuli. In addition, many TRP channel subtypes are involved in physiological and pathophysiological processes such as inflammation, pain, and cancer. The TRPA1, TRPM8, and TRPV1-4 subtypes have been shown to promote large-molecular-weight solute uptake, including impermeable fluorescent dyes, QX-314 hydrophilic lidocaine derivative, gabapentin, and antineoplastic drugs. This review discusses the current knowledge of TRP-associated pores and encourages scientists to study their features and explore them as novel therapeutic tools.
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Affiliation(s)
- L G B Ferreira
- Laboratory of Inflammation, Oswaldo Cruz Institute, FIOCRUZ, Av. Brasil, n° 4365, Manguinhos, CEP 21045-900, Rio de Janeiro, Brazil.
| | - R X Faria
- Laboratory of Cellular Communication, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av. Brasil, n° 4365, Manguinhos, CEP 21045-900, Rio de Janeiro, Brazil
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