TETRODOTOXIN

Description

Tetraodotoxin is a kind of extremely potent toxin which exists in the liver and sex organs of some fishes including pufferfish, porcupine fish, ocean sunfish, and toadfish as well as some kind of amphibian, octopus and shellfish species. It is also produced by some bacteria such as Pseudomonas and Vibrio. Tetraodotoxin is extremely toxic to human, interfering with the transmission of signals of nerves to muscles and further causing paralysis of the body muscle. It can be fatal in some cases. Its mechanism of action is inhibiting the firing of action potentials in nerves through binding to the voltage-gated sodium channels in nerve cell membrane and blocking the passages of sodium ions into the nerve cell. People should wear proper protective equipment upon operations and should be subject to proper treatment upon suffering from it. However, it has been under investigation on the treatment of chronic and breakthrough pain in advanced cancer patients.

References

https://www.cdc.gov/niosh/ershdb/emergencyresponsecard_29750019.html https://en.wikipedia.org/wiki/Tetrodotoxin

Description

Tetrodotoxin (TTX) is a selective sodium channel blocker nonprotein heat-stable toxin. The mechanism of toxicity is through the blockage of fast voltage-gated sodium channels. The consumption of toxic amounts of TTX results primarily in neurologic and gastrointestinal signs and symptoms. TTX is widely distributed in marine taxa such as pufferfish and porcupine fish (suborders of the Tetraodontiformes order), salamanders of the family Salamandridae, Central American frogs (genus Atelopus), shellfish, starfish, crabs, and some species of ribbonworm and octopus. However, in terrestrial taxa, it is limited to a single class of vertebrates (Amphibia). TTX is now known to be produced not by puffer but by bacteria, and reaches various species of animals via food chain.

Chemical Properties

white powder

Uses

Tetrodotoxin is a highly selective, reversible sodium channel blocker.

Uses

TTX is an extremely popular chemical tool in the physiological and pharmacological laboratories since discovery of its channel blocking action in the early 1960s. Some potential therapeutic uses include suppressing pain in cancer patients, preventing ischemic damage of the brain that follows stroke, relieving the symptoms of withdrawal in opiate addicts, and using it as anesthetic agent.

Definition

ChEBI: A quinazoline alkaloid that is a marine toxin isolated from fish such as puffer fish. It has been shown to exhibit potential neutotoxicity due to its ability to block voltage-gated sodium channels.

Biological Activity

Selective inhibitor of Na + channel conductance. Binding is reversible and of high affinity (K d = 1-10 nM). Blocks in a use-dependent manner.

Safety Profile

Poison by ingestion, intraperitoneal, subcutaneous, and intravenous routes. When heated to decomposition it emits toxic fumes of Nox.

storage

-20°C (desiccate)

Toxicity evaluation

TTX is a selective sodium channel blocker that can block nerve and muscle conductions; action potentials are blocked while resting membrane potentials and resting membrane resistance are not affected. TTX blocks axonal transmission by lowering the conductance of sodium at nodes of Ranvier. Vomiting occurs because the toxin can act directly at or near the chemoreceptor trigger zone. Respiratory depression is caused by either a specific action of tetrodotoxin on the brain’s respiratory center or because paralysis of respiratory nerves and muscles occurs.