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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Scorpion venom increases acetylcholine release by prolonging the duration of somatic nerve action potentials

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Author(s):
Collaco, Rita de Cassia O. [1, 2] ; Hyslop, Stephen [2] ; Dorce, Valquiria A. C. [3] ; Antunes, Edson [2] ; Rowan, Edward G. [1]
Total Authors: 5
Affiliation:
[1] Univ Strathclyde, Strathclyde Inst Pharm & Biomed Sci, Robertson Trust Wing Bldg, Room 601, Glasgow G4 0RE, Lanark - Scotland
[2] State Univ Campinas UNICAMP, Fac Med Sci, Dept Pharmacol, Rua Tessalia Vieira de Camargo 126, BR-13083887 Campinas, SP - Brazil
[3] Butantan Inst, Div Sci Dev, Pharmacol Lab, Ave Vital Brazil 1500, BR-05503900 Sao Paulo, SP - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Neuropharmacology; v. 153, p. 41-52, JUL 15 2019.
Web of Science Citations: 0
Abstract

Scorpionism is frequently accompanied by a massive release of catecholamines and acetylcholine from peripheral nerves caused by neurotoxic peptides present in these venoms, which have high specificity and affinity for ion channels. Tityus bahiensis is the second most medically important scorpion species in Brazil but, despite this, its venom remains scarcely studied, especially with regard to its pharmacology on the peripheral (somatic and autonomic) nervous system. Here, we evaluated the activity of T. bahiensis venom on somatic neurotransmission using myographic (chick and mouse neuromuscular preparations), electrophysiological (MEPP, EPP, resting membrane potentials, perineural waveforms, compound action potentials) and calcium imaging (on DRG neurons and muscle fibres) techniques. Our results show that the major toxic effects of T. bahiensis venom on neuromuscular function are presynaptically driven by the increase in evoked and spontaneous neurotransmitter release. Low venom concentrations prolong the axonal action potential, leading to a longer depolarization of the nerve terminals that enhances neurotransmitter release and facilitates nerve-evoked muscle contraction. The venom also stimulates the spontaneous release of neurotransmitters, probably through partial neuronal depolarization that allows calcium influx. Higher venom concentrations block the generation of action potentials and resulting muscle twitches. These effects of the venom were reversed by low concentrations of TTX, indicating voltage-gated sodium channels as the primary target of the venom toxins. These results suggest that the major neuromuscular toxicity of T. bahiensis venom is probably mediated mainly by alpha- and beta-toxins interacting with presynaptic TTX-sensitive ion channels on both axons and nerve terminals. (AU)

FAPESP's process: 16/11319-6 - The somatic and autonomic activities of Tityus bahiensis scorpion venom and its isolated fractions.
Grantee:Rita de Cássia de Oliveira Collaço
Support Opportunities: Scholarships in Brazil - Doctorate
FAPESP's process: 16/23829-9 - Tityus bahiensis scorpion venom and its isolated fractions: an electrophysiological and calcium-imaging study on somatic and autonomic nerve-muscle systems.
Grantee:Rita de Cássia de Oliveira Collaço
Support Opportunities: Scholarships abroad - Research Internship - Doctorate
FAPESP's process: 17/15175-1 - Modulation of soluble guanylate cyclase and the intracellular levels of cyclic nucleotides in the lower urinary tract and prostate
Grantee:Edson Antunes
Support Opportunities: Research Projects - Thematic Grants