title: Triclosan impairs swimming behavior and alters expression of excitation-contraction coupling proteins in fathead minnow (Pimephales promelas).
abstract: Triclosan (TCS), a high volume chemical widely used in consumer products, is a known aquatic contaminant found in fish inhabiting polluted watersheds. Mammalian studies have recently demonstrated that TCS disrupts signaling between the ryanodine receptor (RyR) and the dihydropyridine receptor (DHPR), two proteins essential for excitation-contraction (EC) coupling in striated muscle. We investigated the swimming behavior and expression of EC coupling proteins in larval fathead minnows (Pimephales promelas) exposed to TCS for up to 7 days. Concentrations as low as 75 μg L(-1) significantly altered fish swimming activity after 1 day; which was consistent after 7 days of exposure. The mRNA transcription and protein levels of RyR and DHPR (subunit CaV1.1) isoforms changed in a dose and time dependent manner. Crude muscle homogenates from exposed larvae did not display any apparent changes in receptor affinity toward known radioligands. In nonexposed crude muscle homogenates, TCS decreased the binding of [(3)H]PN20-110 to the DHPR and decreased the binding of [(3)H]-ryanodine to the RyR, demonstrating a direct impact at the receptor level. These results support TCS's impact on muscle function in vertebrates further exemplifying the need to re-evaluate the risks this pollutant poses to aquatic environments.
authors.affiliation: Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616, USA. ebholland@ucdavis.edu
authors.forename: Erika B
authors.initials: EB
authors.lastname: Fritsch
authors.forename: Richard E
authors.initials: RE
authors.lastname: Connon
authors.forename: Inge
authors.initials: I
authors.lastname: Werner
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Davies
authors.forename: Sebastian
authors.initials: S
authors.lastname: Beggel
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.forename: Isaac N
authors.initials: IN
authors.lastname: Pessah
mesh_terms: D000818:Animals; D000891:Anti-Infective Agents, Local / Q000633:toxicity*; D001522:Behavior, Animal / Q000187:drug effects*; D015415:Biomarkers / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism; D003530:Cyprinidae; D056966:Excitation Contraction Coupling / Q000187:drug effects*; D015870:Gene Expression / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects*; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D013550:Swimming; D014260:Triclosan / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D000891:Anti-Infective Agents, Local; D015415:Biomarkers; D020746:Calcium Channels, L-Type; D019837:Ryanodine Receptor Calcium Release Channel; D014874:Water Pollutants, Chemical; D014260:Triclosan