title: Central and peripheral neurotoxicity induced by the Jack Bean Urease (JBU) in Nauphoeta cinerea cockroaches.
abstract: BACKGROUND
  Ureases of Canavalia ensiformis are natural insecticides with a still elusive entomotoxic mode of action. We have investigated the mechanisms involved in the neurotoxicity induced by Jack Bean Urease (JBU) in Nauphoeta cinerea (Olivier).
  
  
  METHODS
  To carry out this study we have employed biochemical and neurophysiological analysis of different cockroach organ systems.
  
  
  CONCLUSIONS
  The injection of the insects with JBU (0.75-6μg/g animal), although not lethal within 24h, caused significant inhibition of the brain acetylcholinesterase activity (60±5%, p<0.05, n=6). JBU (1.5μg/200μL), acetylcholine (0.3μg/200μL) or neostigmine (0.22μg/200μL), induced a positive cardiac chronotropism (∼25%) in the cockroaches (p<0.05, n=9). JBU (6μg/g) increased the insects' grooming activity (137±7%), similarly to octopamine (15μg/g) (p<0.05, n=30, respectively). Pretreating the insects with phentolamine (0.1μg/g) prevented the JBU- or octopamine-induced increase of grooming activity. JBU (6μg/g) caused 65±9% neuromuscular blockade in the cockroaches, an effect prevented by bicuculline (5μg/g) (p<0.05, n=6). JBU (6μg/g) decreased the frequency whilst increasing the amplitude of the spontaneous neural compound action potentials (1425±52.60min-1, controls 1.102±0.032mV, p<0.05, n=6, respectively). Altogether the results indicate that JBU induces behavioral alterations in Nauphoeta cinerea cockroaches probably by interfering with the cholinergic neurotransmission. The neuromuscular blocking activity of JBU suggests an interplay between acetylcholine and GABA signaling.
  
  
  CONCLUSIONS
  The search for novel natural molecules with insecticide potential has become a necessity more than an alternative. Understanding the mode of action of candidate molecules is a crucial step towards the development of new bioinsecticides. The present study focused on the neurotoxicity of Canavalia ensiformis urease, a natural insecticide, in cockroaches and revealed interferences on the cholinergic, octopaminergic and GABA-ergic pathways as part of its entomotoxic mode of action.
authors.affiliation: Graduate Program in Cell and Molecular Biology, Biotechnology Center, Federal University of Rio Grande do Sul, Porto Alegre, Brazil; Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil; Laboratory of Neurotoxins, Laneurotox, Brain Institute of Rio Grande do Sul, InsCer, PUCRS, Porto Alegre, RS, Brazil.
authors.forename: Thiago
authors.initials: T
authors.lastname: Carrazoni
authors.affiliation: Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil.
authors.forename: Marines
authors.initials: M
authors.lastname: de Avila Heberle
authors.affiliation: Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil.
authors.forename: Ana Paula Artusi
authors.initials: AP
authors.lastname: Perin
authors.affiliation: Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Zanatta
authors.affiliation: Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil.
authors.forename: Polyana Veloso
authors.initials: PV
authors.lastname: Rodrigues
authors.affiliation: Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil.
authors.forename: Fabiola Duarte Machado
authors.initials: FD
authors.lastname: Dos Santos
authors.affiliation: Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil; Laboratory of Neurotoxins, Laneurotox, Brain Institute of Rio Grande do Sul, InsCer, PUCRS, Porto Alegre, RS, Brazil.
authors.forename: Carlos Gabriel Moreira
authors.initials: CG
authors.lastname: de Almeida
authors.affiliation: Laboratory of Neurotoxins, Laneurotox, Brain Institute of Rio Grande do Sul, InsCer, PUCRS, Porto Alegre, RS, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Vaz Breda
authors.affiliation: Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil; Laboratory of Neurotoxins, Laneurotox, Brain Institute of Rio Grande do Sul, InsCer, PUCRS, Porto Alegre, RS, Brazil; Graduate Program in Biological Sciences: Biochemical Toxicology, Federal University of Santa Maria, Santa Maria, Brazil.
authors.forename: Douglas Silva
authors.initials: DS
authors.lastname: Dos Santos
authors.affiliation: Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil; Laboratory of Neurotoxins, Laneurotox, Brain Institute of Rio Grande do Sul, InsCer, PUCRS, Porto Alegre, RS, Brazil.
authors.forename: Paulo Marcos
authors.initials: PM
authors.lastname: Pinto
authors.affiliation: Laboratory of Neurotoxins, Laneurotox, Brain Institute of Rio Grande do Sul, InsCer, PUCRS, Porto Alegre, RS, Brazil.
authors.forename: Jaderson Costa
authors.initials: JC
authors.lastname: da Costa
authors.affiliation: Graduate Program in Cell and Molecular Biology, Biotechnology Center, Federal University of Rio Grande do Sul, Porto Alegre, Brazil; Laboratory of Neurotoxins, Laneurotox, Brain Institute of Rio Grande do Sul, InsCer, PUCRS, Porto Alegre, RS, Brazil. Electronic address: celia.carlini@pucrs.br.
authors.forename: Celia Regina
authors.initials: CR
authors.lastname: Carlini
authors.affiliation: Laboratory of Neurobiology and Toxinology, Lanetox, Federal University of Pampa, São Gabriel, RS, Brazil; Laboratory of Neurotoxins, Laneurotox, Brain Institute of Rio Grande do Sul, InsCer, PUCRS, Porto Alegre, RS, Brazil; Graduate Program in Biological Sciences: Biochemical Toxicology, Federal University of Santa Maria, Santa Maria, Brazil. Electronic address: charistonbelo@unipampa.edu.br.
authors.forename: Cháriston André
authors.initials: CA
authors.lastname: Dal Belo
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D032449:Canavalia / Q000201:enzymology*; D003058:Cockroaches; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D007306:Insecticides / Q000494:pharmacology*; D008297:Male; D009388:Neostigmine / Q000494:pharmacology; D009420:Nervous System / Q000187:drug effects; D009498:Neurotoxins / Q000494:pharmacology*; D014510:Urease / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D009498:Neurotoxins; D009388:Neostigmine; D000110:Acetylcholinesterase; D014510:Urease; D000109:Acetylcholine
keywords: Acetylcholinesterase; Behavior modulation; Nauphoeta cinerea; Neurotoxicity; Plant ureases