Rapid and functional neurobiochemical assays for marine algal toxins using mouse brain synaptoneurosomes

Regular monitoring of the levels of marine biotoxins in shellfish has become an essential activity in view of the serious human health consequences of contaminated shellfish consumption.The most commonly encountered marine biotoxins are the saxitoxin (STX) and brevetoxin (PbTx) types, responsible for paralytic shellfish poisoning (PSP) and neurotoxic shellfish poisoning (NSP) respectively.Traditionally, these biotoxins are quantitated by the mouse injection bioassay, which has come under criticisms for a number of reasons.As a potential replacement for the PSP toxin toxicity test, a rapid functional assay using mouse brain synaptoneurosomes has been recently developed and validated by comparison with mouse toxicity data (Nicholson et al., 2002).There were three aims of the present research.Firstly, to investigate the potential of veratrine as a substitute for veratridine to open sodium channels in the synaptoneurosomal PSP toxin assay.Secondly, to further validate the synaptoneurosomal PSP toxin assay using Atlantic mussels spiked with STX and examine the assay's ability to quantitate PSP toxin content of plankton samples.Thirdly, to examine the possibility of configuring and validating synaptoneurosomal assay for NSP toxin quantitation.Concentration-dependent inhibition by STX of veratridine-induced = 4 nM) and veratrine-induced (ICSo = 2 nM) synaptoneurosomal depolarization was observed.Assays of spiked mussel extracts revealed a strong relationship between STX added and STX detected when either veratridine (r2 = 0.998) or veratrine (r2 = 0.997) was used.Veratrine therefore represents a valid alternative to veratridine in this assay.Low PSP toxin levels in plankton samples could also be detected.