Palytoxin toxicity after acute oral administration in mice.

The acute oral toxicity of palytoxin (PLTX), a highly toxic compound associated with seafood intoxication in tropical and subtropical areas, was investigated in mice. After gavage administration (300-1697 microg/kg) to groups of five female CD-1 mice, signs of toxicity and lethality were recorded for 24 h. The LD(50) was 767 microg/kg (95% confidence limits: 549-1039 microg/kg) and the main symptoms observed were scratching, jumping, respiratory distress and paralysis. Hematoclinical analyses showed increased levels of creatine phosphokinase and lactate dehydrogenase at doses of 600 microg/kg and above, and aspartate transaminase at 848 microg/kg and above. Histological analysis revealed acute inflammation of the forestomach in mice surviving up to 24h after administration (424-1200 microg/kg). Other histological alterations were observed in the liver and pancreas, while cardiac and skeletal muscle cells revealed only ultrastructural alterations visible by transmission electron microscopy. Ultrastructural and hematoclinical findings suggest an involvement of skeletal and/or cardiac muscle as targets of PLTX, according to the observed human symptoms. A NOEL of 300 microg/kg can be estimated from this acute oral toxicity study.