Reversible skeletal neuromuscular paralysis induced by different lysophospholipids

Abstract

Lysophosphatidylcholine rapidly paralyses the neuromuscular junction (NMJ), similarly to snake phospholipase A2 neurotoxins, implicating a lipid hemifusion-pore transition in neuroexocytosis. The mode and kinetics of NMJ paralysis of different lysophospholipids (lysoPLs) in high or low [Mg 2+ ] was investigated. The following order of potency was found: lysophosphatidylcholine > lysophosphatidylethanolamine > lysophosphatidic acid > lysophosphatidylserine > lysophosphatidylglycerol. The latter two lysoPLs closely mimic the profile of paralysis caused by the toxins in high [Mg 2+ ]. This paralysis is fully reversed by albumin washing. These findings provide novel insights on the mode of action of snake neurotoxins and qualify lysoPLs as novel agents to study neuroexocytosis.

Cellular pathology induced by snake venom phospholipase A2 myotoxins and neurotoxins: common aspects of their mechanisms of action

“…These neurotoxins have been suggested to bind to the so-called active zones, i.e. those microdomains of the presynaptic membrane where synaptic vesicle neurotransmitter release takes place [16,50,53]. An alternative suggestion has been that they act on the internal membrane layer of synaptic vesicles, once they become exposed to the medium following exocytosis [54].…”

Mass spectrometry analysis of the phospholipase A2 activity of snake pre‐synaptic neurotoxins in cultured neurons

“…CGN neurons are highly sensitive to SPANs and develop a well-defined bulging at axon and dendrite terminals within few minutes from toxin addition; such morphological alteration is accompanied by cytosolic calcium increase at nerve terminals and glutamate release from neurons (Rigoni et al 2004(Rigoni et al , 2007. These effects are mimicked by the addition of an equimolar mixture of the PLA 2 hydrolysis products, lysophosphatidylcholine (LysoPC) + oleic acid, indicating that these molecules are the biochemical mediators of SPAN action (Rigoni et al 2005;Caccin et al 2006). Of the two lipid molecules, LysoPC was shown to be most effective (Caccin et al 2006(Caccin et al , 2009.…”

“…These neurotoxins are abbreviated here as snake pre-synaptic PLA 2 neurotoxins (SPANs). The role of their PLA 2 enzymatic activity in the blockade of the neuromuscular junction (NMJ) has been long debated (Rosenberg 1997;Kini 2003;Gutiérrez et al 2006), but recent results demonstrated that their phospholipid hydrolysis products, lysophospholipids (LysoPLs) and fatty acids (FAs), are sufficient to cause NMJ paralysis with the associated pathological changes (Rigoni et al 2005;Caccin et al 2006). Therefore, to define the pathological action of SPANs it is necessary to analyse their PLA 2 activity in vivo as a function of time.…”

“…These effects are mimicked by the addition of an equimolar mixture of the PLA 2 hydrolysis products, lysophosphatidylcholine (LysoPC) + oleic acid, indicating that these molecules are the biochemical mediators of SPAN action (Rigoni et al 2005;Caccin et al 2006). Of the two lipid molecules, LysoPC was shown to be most effective (Caccin et al 2006(Caccin et al , 2009. We have shown previously that LysoPC is by far the major class of LysoPL released by two SPANs (Rigoni et al 2005), but a comparative and detailed analysis of their kinetics of action including the other two major plasma membrane phospholipids [phosphatidylethanolamine (PE) and phosphatidylserine (PS)] is still lacking.…”

Cellular Mechanisms of Action of Snake Phospholipase A2 Toxins

“…Lysophospholipids induce a membrane curvature which favors membrane fusion of synaptic vesicles and, at the same time, inhibits endocytosis, thus explaining the typical features shown by electron microscopy, i.e., synaptic vesicle depletion and O-shaped plasma membrane figures. Indeed all the morphological and functional alterations induced by these snake neurotoxins can be reproduced by the addition of a mixture of fatty acids and lysophospholipids (Rigoni et al 2005;Caccin et al 2006). High amounts of lysophospholipids, such as those produced by Snake Venoms DOI 10.1007/978-94-007-6648-8_26-1 # Springer Science+Business Media Dordrecht 2015 these snake neurotoxins, destabilize membranes, and it was found that bulges are sites of calcium influx from the extracellular medium in the cytosol, which is then accumulated inside mitochondria causing loss of their membrane potential (Rigoni et al 2007(Rigoni et al , 2008.…”