DDT exposure of zebrafish embryos enhances seizure susceptibility: relationship to fetal p,p'-DDE burden and domoic acid exposure of California sea lions.
BACKGROUND
California sea lions have a large body burden of organochlorine pesticides, and over the last decade they have also been subject to domoic acid poisoning. Domoic acid poisoning, previously recognized in adult animals, is now viewed as a major cause of prenatal mortality. The appearance of a chronic juvenile domoic acid disease in the sea lions, characterized by behavioral abnormalities and epilepsy, is consistent with early life poisoning and may be potentiated by organochlorine burden.


OBJECTIVE
We investigated the interactive effect of DDT (dichlorodiphenyltrichloroethane) on neurodevelopment using a zebrafish (Danio rerio) model for seizure behavior to examine the susceptibility to domoic acid-induced seizures after completion of neurodevelopment.


METHODS
Embryos were exposed (6-30 hr postfertilization) to either o,p'-DDT or p,p'-DDE (dichlorodiphenyldichloroethylene) during neurodevelopment via a 0.1% dimethyl sulfoxide solution. These larval (7 days postfertilization) fish were then exposed to either the seizure-inducing drug pentylenetetrazol (PTZ) or domoic acid; resulting seizure behavior was monitored and analyzed for changes using cameras and behavioral tracking software.


RESULTS
Embryonic exposure to DDTs enhanced PTZ seizures and caused distinct and increased seizure behaviors to domoic acid, most notably a type of head-shaking behavior.


CONCLUSIONS
These studies demonstrate that embryonic exposure to DDTs leads to asymptomatic animals at completion of neurodevelopment with greater sensitivity to domoic acid-induced seizures. The body burden levels of p,p'-DDE are close to the range recently found in fetal California sea lions and suggest a potential interactive effect of p,p'-DDE embryonic poisoning and domoic acid toxicity.
Tiedeken
Jessica A
JA
Marine Biotoxins Program, Center for Coastal Environmental Health and Biomolecular Research, National Oceanic and Atmospheric Administration-National Ocean Service, Charleston, South Carolina, USA.
Ramsdell
John S
JS
D000818:Animals; D001822:Body Burden; D002140:California; D003634:DDT / Q000493:pharmacokinetics / Q000633:toxicity*; D003633:Dichlorodiphenyl Dichloroethylene / Q000493:pharmacokinetics*; D004781:Environmental Exposure; D005333:Fetus / Q000378:metabolism*; D007608:Kainic Acid / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000633:toxicity; D046070:Sea Lions; D012640:Seizures / Q000139:chemically induced*; D015027:Zebrafish / Q000196:embryology*
D003633:Dichlorodiphenyl Dichloroethylene; D003634:DDT; C012301:domoic acid; D007608:Kainic Acid