Human neuronal cell based assay: A new in vitro model for toxicity evaluation of ciguatoxin

•Ciguatoxin (P-CTX-3C) shows powerful cytotoxic effects in human SH-SY5Y-neurons.•P-CTX-3C cytotoxicity requires neurons co-incubation with Veratridine and Ouabain.•The required Ouabain doses simulate physio-pathological endogenous levels in humans.•Effects occur after short- and long-term exposure to CTX picomolar concentrations.•SH-SY5Y appears a suitable species-specific cell-based-model to evaluate CTX cytotoxicity.

Ciguatoxins (CTXs) are emerging marine neurotoxins representing the main cause of ciguatera fish poisoning, an intoxication syndrome which configures a health emergency and constitutes an evolving issue constantly changing due to new vectors and derivatives of CTXs, as well as their presence in new non-endemic areas.The study applied the neuroblastoma cell model of human origin (SH-SY5Y) to evaluate species-specific mechanistic information on CTX toxicity. Metabolic functionality, cell morphology, cytosolic Ca2+i responses, neuronal cell growth and proliferation were assessed after short- (4-24 h) and long-term exposure (10days) to P-CTX-3C.In SH-SY5Y, P-CTX-3C displayed a powerful cytotoxicity requiring the presence of both Veratridine and Ouabain. SH-SY5Y were very sensitive to Ouabain: 10 and 0.25 nM appeared the optimal concentrations, for short- and long-term toxicity studies, respectively, to be used in co-incubation with Veratridine (25 μM), simulating the physiological and pathological endogenous Ouabain levels in humans.P-CTX-3C cytotoxic effect, on human neurons co-incubated with OV (Ouabain + Veratridine) mix, was expressed starting from 100 pM after short- and 25 pM after long-term exposure. Notably, P-CTX-3C alone at 25 nM induced cytotoxicity after 24 h and prolonged exposure.This human brain-derived cell line appears a suitable cell-based-model to evaluate cytotoxicity of CTX present in marine food contaminated at low toxic levels and to characterize the toxicological profile of other/new congeners.

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