Okadaic Acid Is at Least as Toxic as Dinophysistoxin-1 after Repeated Administration to Mice by Gavage

Okadaic acid (OA) and its analogues cause diarrhetic shellfish poisoning (DSP) in humans, risk assessments of these toxins require toxicity equivalency factors (TEFs), which represent the relative toxicities analogues. However, no human death by DSP toxin has been reported, current TEF value is based on acute lethality. To properly reflect symptoms DSP, such as diarrhea without death, chronic at sublethal doses should be considered. In this study, we obtained oral LD50 values for OA dinophysistoxin-1 (DTX-1) (1069 897 μg/kg, respectively) to set doses. Mice were treated with DTX-1 7 days. The mice lost body weight, disease activity index intestinal crypt depths increased. Furthermore, changes more severe OA-treated than DTX-1-treated mice. Strikingly, ascites was observed, severity greater OA. Our findings suggest that least toxic after repeated administration a low dose. This first study compare dosing toxins. Further sub-chronic studies are warranted determine appropriate