Tetrodotoxin, an Extremely Potent Marine Neurotoxin: Distribution, Toxicity, Origin and Therapeutical Uses.

Tetrodotoxin (TTX) is a potent neurotoxin responsible for many human intoxications and fatalities each year. The origin of TTX is unknown, but in the pufferfish, it seems to be produced by endosymbiotic bacteria that often seem to be passed down the food chain. The ingestion of contaminated pufferfish, considered the most delicious fish in Japan, is the usual route of toxicity. This neurotoxin, reported as a threat to human health in Asian countries, has spread to the Pacific and Mediterranean, due to the increase of temperature waters worldwide. TTX, for which there is no known antidote, inhibits sodium channel producing heart failure in many cases and consequently death. In Japan, a regulatory limit of 2 mg eq TTX/kg was established, although the restaurant preparation of "fugu" is strictly controlled by law and only chefs qualified are allowed to prepare the fish. Due to its paralysis effect, this neurotoxin could be used in the medical field as an analgesic to treat some cancer pains.