Mechanism of Rhinella icterica (Spix, 1824) toad poisoning using in vitro neurobiological preparations

• Published in: Neurotoxicology (Park Forest South) 2018-03, Vol.65, p.264-271
• Main Authors: Oliveira, Raquel Soares, Leal, Allan Pinto, Ogata, Barbara, Moreira de Almeida, Carlos Gabriel, dos Santos, Douglas Silva, Lorentz, Leandro Homrich, Moreira, Cleci Menezes, de Castro Figueiredo Bordon, Karla, Arantes, Eliane Candiani, dos Santos, Tiago Gomes, Dal Belo, Cháriston André, Vinadé, Lúcia
• Format: Article
• Language: English
• Subjects: Acetylcholinesterase; Amphibian Venoms - toxicity; Animal tissues; Animals; Biological activity; Brain slice preparation; Bufonidae; Calcium; Calcium channels; Cell Survival - drug effects; Central nervous system; Chickens; Cholinesterase Inhibitors - toxicity; Curare; Curare - antagonists & inhibitors; Curare - pharmacology; Data processing; Deprivation; Digoxin; Digoxin - pharmacology; Dose-Response Relationship, Drug; Heart; Heart diseases; Hippocampus; Hippocampus - drug effects; Incubation; Ischemia - prevention & control; Male; Mice; Muscle strength; Muscles; Myocardium - metabolism; Na+/K+-exchanging ATPase; Neostigmine; Neuromuscular blockade; Neuromuscular Blocking Agents - pharmacology; Neuromuscular Junction - drug effects; Neuromuscular Junction - metabolism; Neuromuscular junctions; Neuroprotection; Neurotransmission; Ouabain; Ouabain - pharmacology; Pharmacology; Poisonous species; Poisons; Rats; Rhinella icterica; Secretion; Sodium-Potassium-Exchanging ATPase - antagonists & inhibitors; Toad poison; Toads; Toxicity; Vertebrates
• ISSN: 0161-813X; 1872-9711
• DOI: 10.1016/j.neuro.2017.11.006

•Rhinella icterica poison induces neuromuscular blockade.•Rhinella icterica poison induces central neurotoxicity.•Rhinella icterica poison presents bufalin.•The poison mechanisms relay on biochemical and ionic channels interactions. The biological activity of Rhinella icterica toxic secretion (RITS) was evaluated on chick neuromuscular junctions, rat heart́s tissue and mice hippocampal slices. At chick biventer cervicis preparation, RITS (5, 10 and 20μg/mL) produced a concentration-independent irreversible neuromuscular blockade, which was preceded by a transitory increase of muscle twitch tension with the lowest concentration, in 120min recordings. In this set of experiments, RITS incubation partially prevented the curare neuromuscular blockade. The assessment of chick biventer cervicis muscle acetylcholinesterase (AChE) in the presence of RITS showed a significant inhibition of the enzyme, similarly to neostigmine. The incubation of muscles with digoxin or ouabain mimicked the poison activity by increasing the amplitude of the twitches followed by a progressive depression of the muscle strength. In addition, RITS demonstrated a digitalic-like activity, by inhibiting significantly the cardiac Na+, K+-ATPase. When the central nervous system was accessed, RITS induced an increase in the cell viability, in the lowest concentration. In addition, the poison protected slices subject to oxygen/glucose deprivation. Altogether, these data indicate that the poisonous extract of R. icterica is able to interfere with peripheral and central neurotransmission, probably due to a direct interaction with AChE, calcium channels and Na+, K+-ATPase. A further investigation upon the poison toxic components will unveil the components involved in such a pharmacological activity and the potential biotechnological application of this poison.