Inhibition of Ligand-Gated TRPA1 by General Anesthetics. 2020

Hoai T Ton, and Thieu X Phan, and Gerard P Ahern
Department of Pharmacology and Physiology, Georgetown University, Washington DC (H.T.T., T.X.P., G.P.A.) and Department of Biology, Vinh University, Vinh city, Nghe An, Vietnam (H.T.T., T.X.P.) gpa3@georgetown.edu.

Several general anesthetics (GAs) produce pain or irritation upon administration, and this occurs predominantly through the activation of the nociceptive ion channel, transient receptor potential ankyrin type 1 (TRPA1). However, the effects of GAs on agonist-mediated TRPA1 activity are unclear. Here we show that a diverse range of noxious and non-noxious volatile anesthetics, at clinically relevant concentrations, inhibit ligand-activated TRPA1 currents. These effects are species-specific; GAs blocks rodent TRPA1 without affecting the Drosophila ortholog. Furthermore, propofol inhibits rodent but not human TRPA1. Analysis of chimeric TRPA1 proteins and mutagenesis combined reveals two amino acid residues located in the S5 domain, Ser876 and Thr877, that are critical for the inhibitory effects of isoflurane and propofol. Introduction of these residues into Drosophila TRPA1 confers anesthetic inhibition. Furthermore, several residues lining the presumptive binding pocket for noxious GAs are not required for the inhibitory effects of GAs. We conclude that anesthetics inhibit TRPA1 by interacting at a site distinct from the activation site. The inhibitory effects of GAs at TRPA1 may contribute to the diverse pharmacological action of these drugs. SIGNIFICANCE STATEMENT: We show that both noxious and non-noxious general anesthetics inhibit agonist-evoked transient receptor potential ankyrin type 1 (TRPA1) activity and identify critical amino acid residues located in the pore domain. Inhibition of TRPA1 may affect pain and vascular signaling during anesthesia.

UI MeSH Term Description Entries
D006993 Hypnotics and Sedatives Drugs used to induce drowsiness or sleep or to reduce psychological excitement or anxiety. Hypnotic,Sedative,Sedative and Hypnotic,Sedatives,Hypnotic Effect,Hypnotic Effects,Hypnotics,Sedative Effect,Sedative Effects,Sedatives and Hypnotics,Effect, Hypnotic,Effect, Sedative,Effects, Hypnotic,Effects, Sedative,Hypnotic and Sedative
D007530 Isoflurane A stable, non-explosive inhalation anesthetic, relatively free from significant side effects.
D009154 Mutation Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations. Mutations
D004331 Drosophila melanogaster A species of fruit fly frequently used in genetics because of the large size of its chromosomes. D. melanogaster,Drosophila melanogasters,melanogaster, Drosophila
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000072417 Protein Domains Discrete protein structural units that may fold independently of the rest of the protein and have their own functions. Peptide Domain,Protein Domain,Domain, Peptide,Domain, Protein,Domains, Peptide,Domains, Protein,Peptide Domains
D000074025 TRPA1 Cation Channel A highly conserved, non-selective TRP cation channel that contains 14-17 ANKYRIN REPEATS. It functions in cold sensation and NOCICEPTION of endogenous inflammatory factors and volatile irritants. TRPA1 is also activated by CANNABINOIDS and may play a role in sound perception by hair cells of the inner ear. TRPA1 Channel,Transient Receptor Potential Cation Channel Subfamily A, Member 1,Cation Channel, TRPA1,Channel, TRPA1,Channel, TRPA1 Cation
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013045 Species Specificity The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species. Species Specificities,Specificities, Species,Specificity, Species
D015742 Propofol An intravenous anesthetic agent which has the advantage of a very rapid onset after infusion or bolus injection plus a very short recovery period of a couple of minutes. (From Smith and Reynard, Textbook of Pharmacology, 1992, 1st ed, p206). Propofol has been used as ANTICONVULSANTS and ANTIEMETICS. Disoprofol,2,6-Bis(1-methylethyl)phenol,2,6-Diisopropylphenol,Aquafol,Diprivan,Disoprivan,Fresofol,ICI-35,868,ICI-35868,Ivofol,Propofol Abbott,Propofol Fresenius,Propofol MCT,Propofol Rovi,Propofol-Lipuro,Recofol,2,6 Diisopropylphenol,ICI 35,868,ICI 35868,ICI35,868,ICI35868

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