palytoxin and maitotoxin

Synapses are specialised structures where interneuronal communication takes place. Not only brain function is absolutely dependent on synaptic activity, but also most of our organs are intimately controlled by synaptic activity. Synapses re therefore an ideal target to act upon and poisonous species have evolved fascinating neurotoxins capable of shutting down neuronal communication by blocking or activating essential components of the synapse. By hijacking key proteins of the communication machinery, neurotoxins are therefore extremely valuable tools that have, in turn, greatly helped our understanding of synaptic biology. Moreover, analysis and understanding of the molecular strategy used by certain neurotoxins has allowed the design of entirely new classes of drugs acting on specific targets with high selectivity and efficacy. This chapter will discuss the different classes of marine neurotoxins, their effects on neurotransmitter release and how they act to incapacitate key steps in the process leading to synaptic vesicle fusion.

Topics: Acrylamides; Amino Acid Sequence; Animals; Calcium Channel Blockers; Calcium Channels; Ciguatoxins; Cnidarian Venoms; Ion Channels; Marine Toxins; Models, Molecular; Molecular Sequence Data; Neurotoxins; Neurotransmitter Agents; Oxocins; Potassium Channels; Saxitoxin; Sea Anemones; Synaptic Transmission; Tetrodotoxin

Biotoxins produced by harmful marine microalgae (phycotoxins) can be accumulated into seafood, representing a great risk for public health. Some of these phycotoxins are responsible for a variety of gastrointestinal disturbances; however, the relationship between their mechanism of action and toxicity in intestinal cells is still unknown. The actin cytoskeleton is an important and highly complicated structure in intestinal cells, and on that basis our aim has been to investigate the effect of representative phycotoxins on the enterocyte cytoskeleton. We have quantified for the first time the loss of enterocyte microfilament network induced by each toxin and recorded fluorescence images using a laser-scanning cytometer and confocal microscopy. Our data show that pectenotoxin-6, maitotoxin, palytoxin and ostreocin-D cause a significant reduction in the actin cytoskeleton. In addition, we found that the potency of maitotoxin, palytoxin and ostreocin-D to damage filamentous actin is related to Ca(2+) influx in enterocytes. Those results identify the cytoskeleton as an early target for the toxic effect of those toxins.

Topics: Acrylamides; Actins; Animals; Bridged Bicyclo Compounds, Heterocyclic; Calcium; Cnidarian Venoms; Cytoskeleton; Fluoresceins; Furans; Intestinal Mucosa; Laser Scanning Cytometry; Macrolides; Marine Toxins; Microscopy, Confocal; Oxocins; Pyrans; Rabbits