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23 Congress of the International Union for Biochemistry and Molecular Biology
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44 Annual Meeting of the Brazilian Society for Biochemistry and Molecular Biology
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Foz do Iguaçu, PR, Brazil, August 24 to 28 , 2015
ANALYSIS OF THE NEUROTOXICITY OF JACK BEAN UREASE (JBU) IN RODENT
MODELS
Authors: Almeida, C.G.M 1,2, Corrado, A.P3, Oliveira, R.S1, Vinadé, L.H1, Floriano,
R.S5, Rowan, E.G5, Santos, D.S 1,4, Carlini, C.R 2,6, Dal Belo, C. A 1,2,4.
1
LANETOX, Universidade Federal do Pampa, São Gabriel, Brazil; 2 LaNeurotox Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil; 3Faculdade
de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil; 4
PPGBioTox, Universidade Federal de Santa Maria, Santa Maria, Brazil; 5SIPBS,
University of Strathclyde, Glasgow, UK. 6Center of Biotechnology, Universidade Federal
do Rio Grande do Sul, UFRGS, Porto Alegre Brazil.
Key words: Ureases, seizures, compound action potentials.
Ureases, metalloenzymes that hydrolyze urea producing NH3 and CO2, present several
enzyme-independent biological activities, including neurotoxicity (Olivera-Severo et al,
(2006), Braz. J. Med. Biol. Res. 39, 851–861). Here, we explored the neurotoxic
activities of JBU by analyzing its convulsive-like activities in vivo, peripheral
neurotoxicity ex vivo and cytotoxicity in vitro in mouse and rats nerve preparations.
Adult Wistar rats and Swiss albine mice uses were approved by the local Animal Care
Committee. Electroencephalographic (EEG) recordings were carried out in rats,
essentially as described by Bueno-Junior et al., (2012), Plos One 7(10). Extracellular
recordings of mouse sciatic nerve compound action potentials (CAPs) were carried out
as described by Dal Belo et al., (2005), Toxicon 46, 736–750. The MTT colorimetric
assay was performed as described by Dal Belo et al., (2013), Biomed Research
International, 943520, 2013). Statistical analysis employed Student “t” test. The EEG
recordings of local field potentials, from electrodes implanted in the hippocampal CA1
area, showed that the intrahippocampal administration of JBU (9µl, 10nM) induced an
absence-like epilepsy crisis (n=3), characterized by a spike and EEG wave of ~2.5ms
transitory duration. The incubation of mouse sciatic nerve with different concentrations
of JBU (10, 100 and 1000 nM) induced a concentration and time-dependent decrease in
the amplitude of the CAPs (59±2, 74±4 and 83±1%), p<0.05, respectively, in 120min of
recordings. MTT assay of mice hippocampus incubated with JBU (1, 10 and 100nM),
showed no significant decrease in the cell viability n=3, p>0.05. The results corroborate
previous findings showing that the administration of Canavalia ensiformis ureases, JBU
and Canatoxin, induce convulsive crisis by systemic routes. The decrease in sciatic
nerve CAP amplitude suggests a direct activity on voltage-gated sodium channels. The
MTT analysis showed that JBU induces its neurotoxicity without developing decrease in
neuronal viability.
Acknowledgements: Edital Toxinologia CAPES 063/2010.
Brazilian Society for Biochemistry and
Molecular Biology (SBBq)