TTx

TTX, or tetrodotoxin, is a highly potent neurotoxin most famously associated with pufferfish (fugu) but found in other marine and terrestrial species. The toxin occurs naturally in several pufferfish species and in some unrelated animals such as certain newts, salamanders, frogs, and flatworms. It is produced by symbiotic bacteria and concentrates in the tissues of these animals. It is heat-stable, and cooking does not reliably destroy it, so exposure can occur from prepared foods even when thoroughly cooked.

TTX acts by selectively blocking voltage-gated sodium channels (Nav) in nerve and muscle tissue. By binding to site 1 in the extracellular pore of these channels, it prevents sodium influx and stops action potential propagation. This disruption of neural signaling leads to tingling around the mouth and lips, numbness, dizziness, ataxia, weakness, and, in severe cases, paralysis of respiratory muscles and death from respiratory failure. The onset is typically within minutes to a few hours after ingestion, depending on amount and route.

There is no widely available antidote. Treatment is supportive and may require airway protection and mechanical ventilation. Early decontamination with activated charcoal may be considered where appropriate, and patients require close monitoring for progression of symptoms.

In research, tetrodotoxin is used as a tool to study sodium channels and nerve transmission. It has also been explored for potential therapeutic applications, though its use is limited by toxicity. Public health measures emphasize regulation of pufferfish preparation and education about the risks of TTX-containing foods.