Revista de Biología Tropical ISSN Impreso: 0034-7744 ISSN electrónico: 2215-2075

Action of heparin and acetylcholine modulators on the neurotoxicity of the toad Rhinella schneideri (Anura: Bufonidae) in Brazil


amphibian poison
paratoid gland secretion
chick biventer cervicis preparation
neuromuscular blockade
veneno de anfibio
secreción de la glándula parótida
preparaciones de biventer cervicis de pollos
bloqueo neuromuscular

How to Cite

Rostelato-Ferreira, S., Vettorazzo, O. B., Tribuiani, N., Leal, A. P., Dal Belo, C. A., Rodrigues-Simioni, L., Floriano, R. S., & Oshima-Franco, Y. (2021). Action of heparin and acetylcholine modulators on the neurotoxicity of the toad Rhinella schneideri (Anura: Bufonidae) in Brazil. Revista De Biología Tropical, 69(2), 545–556.


Introduction: Rhinella schneideri is a toad widely distributed in South America and its poison is characterized by inducing cardiotoxicity and neurotoxicity. Objective: In this work, we investigated pharmacological strategies to attenuate the peripheral neurotoxicity induced by R. schneideri poison in avian neuromuscular preparation. Methods: The experiments were carried out using isolated chick biventer cervicis preparation subjected to field stimulation for muscle twitches recordings or exposed to acetylcholine and potassium chloride for contracture responses. Results: Poison (10 μg/ml) produced complete neuromuscular blockade in chick biventer cervicis preparation within approximately 70 min incubation (times for 50 and 90 % blockade: 15 ± 3 min and 40 ± 2 min, respectively; P < 0.05, N= 5); contracture responses to exogenous acetylcholine and KCl were unaffected by poison indicating no specificity with postsynaptic receptors or myotoxicity, respectively. Poison (10 μg/ml)-induced neuromuscular blockade was not prevented by heparin (5 and 150 IU/ml) under pre- or post-treatment conditions. Incubation at low temperature (23-25 °C) abolished the neuromuscular blockade; after raising the temperature to 37 °C, the complete neuromuscular blockade was slightly slower than that seen in preparations directly incubated at 37 °C (times for 50 and 90 % blockade: 23 ± 2 min and 60 ± 2.5 min, respectively; P < 0.05, N= 4). Neostigmine (3.3 μM) did not reverse the neuromuscular blockade in BC preparation whereas 3,4-diaminopyridine (91.6 μM) produced a partial and sustained reversal of the twitch responses (29 ± 7.8 % of maximal reversal reached in approximately 40 min incubation; P < 0.05, N= 4). Conclusions: R. schneideri poison induces potent peripheral neurotoxicity in vitro which can be partially reversible by 3,4-diaminopyridine.



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