title: Presynaptic Proteins as Markers of the Neurotoxic Activity of BmjeTX-I and BmjeTX-II Toxins from Bothrops marajoensis (Marajó Lancehead) Snake Venom.
abstract: Neuromuscular preparations exposed to B. marajoensis venom show increases in the frequency of miniature end-plate potentials and twitch tension facilitation followed by presynaptic neuromuscular paralysis, without evidences of muscle damage. Considering that presynaptic toxins interfere into the machinery involved in neurotransmitter release (synaptophysin, synaptobrevin, and SNAP25 proteins), the main objective of this communication is to analyze, by immunofluorescence and western blotting, the expression of the synaptic proteins, synaptophysin, synaptobrevin, and SNAP25 and by myography, light, and transmission electron microscopy the pathology of motor nerve terminals and skeletal muscle fibres of chick biventer cervicis preparations (CBC) exposed in vitro to BmjeTX-I and BmjeTX-II toxins from B. marajoensis venom. CBC incubated with toxins showed irreversible twitch tension blockade and unaffected KCl- and ACh-evoked contractures, and the positive colabelling of acetylcholine receptors confirmed that their action was primarily at the motor nerve terminal. Hypercontraction and loose myofilaments and synaptic vesicle depletion and motor nerve damage indicated that the toxins displayed both myotoxic and neurotoxic effect. The blockade resulted from interference on synaptophysin, synaptobrevin, and SNAP25 proteins leading to the conclusion that BmjeTX-I and BmjeTX-II affected neurotransmitter release machinery by preventing the docking of synaptic vesicles to the axolemma of the nerve terminal.
authors.affiliation: Multidisciplinary Research Laboratory, São Francisco University (USF), Avenida São Francisco de Assis 218, Jardim São José, 12916-350 Bragança Paulista, SP, Brazil.
authors.forename: Antonio
authors.initials: A
authors.lastname: Lisboa
authors.affiliation: Multidisciplinary Research Laboratory, São Francisco University (USF), Avenida São Francisco de Assis 218, Jardim São José, 12916-350 Bragança Paulista, SP, Brazil.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Melaré
authors.affiliation: Multidisciplinary Research Laboratory, São Francisco University (USF), Avenida São Francisco de Assis 218, Jardim São José, 12916-350 Bragança Paulista, SP, Brazil.
authors.forename: Junia R B
authors.initials: JR
authors.lastname: Franco
authors.affiliation: Multidisciplinary Research Laboratory, São Francisco University (USF), Avenida São Francisco de Assis 218, Jardim São José, 12916-350 Bragança Paulista, SP, Brazil.
authors.forename: Carolina V
authors.initials: CV
authors.lastname: Bis
authors.affiliation: Multidisciplinary Research Laboratory, São Francisco University (USF), Avenida São Francisco de Assis 218, Jardim São José, 12916-350 Bragança Paulista, SP, Brazil.
authors.forename: Marta
authors.initials: M
authors.lastname: Gracia
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), Rua Monteiro Lobato, 255, Cidade Universitária Zeferino Vaz, 13083-365 Campinas, SP, Brazil.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Ponce-Soto
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), Rua Monteiro Lobato, 255, Cidade Universitária Zeferino Vaz, 13083-365 Campinas, SP, Brazil.
authors.forename: Sérgio
authors.initials: S
authors.lastname: Marangoni
authors.affiliation: Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo 126, Cidade Universitária Zeferino Vaz, 13083-881 Campinas, SP, Brazil.
authors.forename: Léa
authors.initials: L
authors.lastname: Rodrigues-Simioni
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), Rua Monteiro Lobato, 255, Cidade Universitária Zeferino Vaz, 13083-365 Campinas, SP, Brazil.
authors.forename: Maria Alice
authors.initials: MA
authors.lastname: da Cruz-Höfling
authors.affiliation: Multidisciplinary Research Laboratory, São Francisco University (USF), Avenida São Francisco de Assis 218, Jardim São José, 12916-350 Bragança Paulista, SP, Brazil; Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), Rua Monteiro Lobato, 255, Cidade Universitária Zeferino Vaz, 13083-365 Campinas, SP, Brazil.
authors.forename: Thalita
authors.identifier: 0000-0002-2731-9586
authors.initials: T
authors.lastname: Rocha