Delineation of the mechanism of action of presynaptic excitatory peptides from Bothrops bilineatus smaragdinus (Viperidae: Crotalinae) venom on the ion channels modulation of peripheral neurons

• Grant number: 23/18237-9
• Support Opportunities: Scholarships abroad - Research
• Start date: February 01, 2025
• End date: January 31, 2026
• Field of knowledge: Biological Sciences - Pharmacology - Toxicology
• Principal Investigator: Rafael Stuani Floriano
• Grantee: Rafael Stuani Floriano
• Host Investigator: Robert Maxwell Drummond
• Host Institution: Pró-Reitoria de Pesquisa e Pós-Graduação. Universidade do Oeste Paulista (UNOESTE). Presidente Prudente , SP, Brazil
• Institution abroad: University of Strathclyde, Scotland

Abstract

Bothrops bilineatus smaragdinus (Viperidae: Crotalinae) venom induces two phenomena in mammalian nerve-muscle preparation: 1) neuromuscular facilitation, mediated by a peptide fraction (P8), immediately followed by 2) irreversible neuromuscular blockade, mostly mediated by a presynaptically active fosfolipase A2 (Bbil-TX). The toxinology of the P8 fraction of this venom has not been systematically studied. In this work, we intend to delineate the mechanism of action of two presynaptic excitatory peptides (P8-1 and P8-2) from B. b. smaragdinus venom on the ion channels modulation of peripheral neurons using electrophysiological approaches (perineural currents and whole cell patch-clamp recordings) and cellular assays (mobilization of intracellular Ca2+) in tissues and cell culture exposed to the peptides. Specifically, regarding the period to be spent abroad, the major aim will be to improve skills and gain experience in the design and execution of patch-clamp experiments. This will be achieved by investigating the presynaptic activity of the peptides on the peripheral neurotransmission, following such aspects: (1) cultured DRG cells will be used to examine the activity of the peptides on isolated channel currents (Na+, K+ and Ca2+) in a whole-cell patch-clamp configuration, (2) DRG cells and mouse triangularis sterni nerve-muscle preparations will be used to assess the role of intracellular Ca2+ mobilization in response to the peptides by using fluorescent Ca2+ imaging, and (3) mouse triangularis sterni nerve-muscle preparations will be used to examine the action of the peptides on the perineural currents. The results obtained in this study should contribute to the understanding of the mechanisms involved in the presynaptic excitatory activity of peptides isolated from this venom.