title: Ouabain exacerbates botulinum neurotoxin-induced muscle paralysis via progression of muscle atrophy in mice.
abstract: Botulinum neurotoxin serotype A (BoNT/A) inhibits acetylcholine release at the neuromuscular junction in isolated muscles, and ouabain can partially block its effect. However, it is not clear whether ouabain attenuates BoNT/A-induced neuromuscular paralysis in vivo. In this work, we investigated the effects of ouabain on BoNT/A-induced neuromuscular paralysis in mice. Ouabain was administered to mice intraperitoneally immediately after a single injection of BoNT/A into skeletal muscle. The effects of ouabain on BoNT/A-induced muscle paralysis were assessed by quantitative monitoring of muscle tension and digit abduction via the digit abduction scoring (DAS) assay. A single administration of ouabain significantly prolonged BoNT/A-induced neuromuscular paralysis. Moreover, consecutive daily injection of ouabain exacerbated BoNT/A-induced neuromuscular paralysis, and led to a significant decrease in both twitch and tetanic forces as assayed in isolated BoNT/A-injected muscles. We next looked at the effects of ouabain on BoNT/A-induced muscle atrophy. Administration of ouabain led to a decrease in the myofibrillar cross-sectional area (CSAs) by 14 post-BoNT/A injection. In addition, repeated administration of ouabain increased mRNA expression levels of ubiquitin ligases, which are markers of muscle atrophy, in BoNT/A-injected muscle. These results suggest that ouabain exacerbates BoNT/A-induced neuromuscular paralysis via a marked progression of BoNT/A-induced muscle atrophy.
authors.affiliation: Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: Ryu
authors.initials: R
authors.lastname: Fujikawa
authors.forename: Yoshikage
authors.initials: Y
authors.lastname: Muroi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Unno
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Ishii
mesh_terms: D000818:Animals; D019274:Botulinum Toxins, Type A / Q000633:toxicity*; D004357:Drug Synergism; D007273:Injections, Intramuscular; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009124:Muscle Proteins / Q000096:biosynthesis; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000201:enzymology; D009133:Muscular Atrophy / Q000139:chemically induced* / Q000150:complications / Q000201:enzymology; D010042:Ouabain / Q000633:toxicity*; D010243:Paralysis / Q000139:chemically induced* / Q000150:complications / Q000201:enzymology; D012313:RNA / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases / Q000096:biosynthesis
chemical_list: D009124:Muscle Proteins; D000070584:Tripartite Motif Proteins; D010042:Ouabain; D012313:RNA; C499084:Trim63 protein, mouse; D044767:Ubiquitin-Protein Ligases; D019274:Botulinum Toxins, Type A