Ciguatoxins and brevetoxin

This chapter summarizes recent work on the molecular basis of the toxic actions of ciguatoxin and brevetoxins. It is shown (i) that the molecular target for these toxins is the voltage-dependent Na channel of excitable tissues arid (ii) that ciguatoxin and brevetoxins share a common receptor site on the Na channel. 

All these results are clear indications that CTx and PbTx have similar modes of action and that they increase the membrane permability of excitable cells to Na ions by opening voltage-dependent Na channels. This action fully accounts for the toxicity of ciguatoxin and brevetoxins. 

Ciguatoxins are produced by Gambierdiscus toxicus. Lipid-soluble ciguatoxins and brevetoxins have immunologic cross reactivity, and thus have similar epitopic sites and mechanisms of action, as described in the previous section. 

Manger, R. L., Leja, L. S., Lee, S. Y. et al.. Detection of sodium channel toxins directed cytotoxicity assays of purified ciguatoxins, brevetoxins, saxitoxins, and seafood extracts, J. AOAC Int. 78, 521, 1995 Dechraoui, M. Y, Naar, J., PauUlac, S. et al., Ciguatoxins and brevetoxins, neurotoxic polyether compounds active on sodium chaimels, Toxicon 37, 125, 1999. 

Lombet, A., Bidard, J. N., and Lazdunski, M., Ciguatoxin and brevetoxins share a common receptor site on the neuronal voltage-dependent Na-l- channel, FEBS Lett. 219, 355, 1987. 

Dechraoui, M.Y. et al., Ciguatoxins and brevetoxins, neurotoxic polyether compounds active on sodium channels, Toxicon, 37, 125, 1999. 

Citotoxicity assays using murine neuroblastoma cells (Neuro-2A) have been proposed for the assessment of ciguatoxins and brevetoxins. The simplest method is based in the ability of metabolically active cells to reduce the tetrazolium compound MTT. After incubation with serial dilutions of test samples, cells are exposed to MTT and formation of color due to MTT reduction is read using a spectrophotometer. A new cytotoxicity assay is based on a c-fos-luciferase reporter gene that uses luciferase-catalyzed light generation as an endpoint and a microplate luminometer for quantification. After... 

Ciguatoxins and brevetoxins induce dysfimction of the sodium channels and thus have similar modes of action (Dechraoui-Bottein et al, 1999). 

Dechraoui, M.Y., Tiedeken, J.A., Persad, R., Wang, Z., Granade, H.R., Dickey, R.W., and Ramsdell, J.S., Use of two detection methods to discriminate ciguatoxins from brevetoxins application to great barracuda from Florida Keys. Toxicon, 46, 261, 2005. 

Ecobiology of the Brevetoxin, Ciguatoxin, and Cyclic Imine Producers... 

Trainer, V.L. and Poh, M.A., Assays for dinoflagellate toxins, specifically brevetoxin, ciguatoxin, and saxitoxin, in Animal Toxins. Tools in Cell Biology. A Laboratory Companion, Rochat, FI. and Martin-Euclaire, M.-F, Eds, Chapman and Hall, Weinheim, Germany, 2000. 

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