Occurrence of paralytic shellfish toxins in Cambodian Mekong pufferfish Tetraodon turgidus:: Selective toxin accumulation in the skin

The toxicity of two species of wild Cambodian freshwater pufferfish of the genus Tetraodon, T turgidus and Tetraodon sp., was investigated. Tetraodon sp. was non-toxic. The toxicity of T turgidus was localized mainly in the skin and ovary. Paralytic shellfish toxins (PSTs), comprising saxitoxin (STX) and decarbamoylsaxitoxin (dcSTX), account for approximate to 85% of the total toxicity. Artificially reared specimens of the same species were non-toxic. When PST (dcSTX, 50 MU/individual) was administered intramuscularly into cultured specimens, toxins were transferred via the blood from the muscle into other body tissues, especially the skin. The majority (92.8%) of the toxin remaining in the body accumulated in the skin within 48 h. When the same dosage of tetrodotoxin (TTX) was similarly administered, all specimens died within 3-4 h, suggesting that this species is not resistant to TTX Toxin analysis in the dead specimens revealed that more than half of the administered TTX remained in the muscle and a small amount was transferred into the skin. The presence of both toxic and non-toxic wild specimens in the same species indicates that PSTs of T turgidus are derived from an exogenous origin, and are selectively transferred via the blood into the skin, where the toxins accumulate. (c) 2007 Elsevier Ltd. All rights reserved.