Presynaptic effect of a methanolic extract of toad (Rhinella schneideri) poison in avian neuromuscular preparation

Research Report

J Venom Res (2011), Vol 2, 32-36

Published online: 22 September 2011

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Sandro Rostelato-Ferreira † , Cháriston A Dal Belo ‡ , Maria Alice da Cruz-Höfling §, Stephen Hyslop † and Léa Rodrigues-Simioni †*

† Departamento de Farmacologia, Faculdade de Ciências Médicas, CP 6111, Universidade Estadual de Campinas – UNICAMP, Brasil

‡ Centro de Ciências Rurais de São Gabriel, Universidade Federal do Pampa (UNIPAMPA), São Gabriel, RS, Brazil

§ Departamento de Histologia e Embriologia, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, 13083-970, Campinas, SP, Brazil

*Correspondence to: Léa Rodrigues-Simioni, E-mail: (LRS), or Sandro Rostelato-Ferreira, (SRF) , Tel: +55 19 35219533, Fax: +55 19 32892968

Received: 27 May 2011, Revised: 29 August 2011, Accepted: 11 September 2011

© Copyright The Authors


The neurotoxicity of a methanolic extract of toad (Rhinella schneideri) poison was examined in chick biventer cervicis preparations. The methanolic extract (1, 3, 10 and 30µg/ml) caused concentration-dependent blockade at the three highest concentrations (time for 50% blockade, mean±SEM: 84±10, 51±3 and 12±0.8min for 3, 10 and 30µg/ml, respectively; n=6-8 each) that was preceded by significant, transient facilitation at 10 m g/ml. Contractures to exogenous ACh (110mM) or KCl (20mM) were unaffected by the blockade. In curarized (d-Tc, 1mg/ml) preparations, the extract (10µg/ml) caused complete, irreversible blockade that persisted after extensive washing. The extract did not significantly alter the creatine kinase release or morphology of biventer cervicis muscle. These results indicate that the methanolic extract of R. schneideri poison acts primarily presynaptically to enhance neurotransmitter release in this avian preparation.

KEYWORDS: Neuromuscular blockade, neurotransmitter release, presynaptic, Rhinella schneideri, toad poison