Trans-generational transmission of neurobehavioral impairments produced by developmental methylmercury exposure in zebrafish (Danio rerio).

Our previous study showed that embryonic exposures to methylmercury (MeHg) produced learning impairments in adult zebrafish. The present study investigated the persistency of learning impairments in the second (F2) and third (F3) generations of zebrafish developmentally exposed to MeHg as embryos using active avoidance conditioning as the behavioral paradigm. The results showed that the control zebrafish learned avoidance responses during training and significantly increased avoidance responses during testing. The F2 generation of zebrafish developmentally exposed to MeHg as embryos displayed no significant changes in avoidance responses from training to testing, showing persistent learning impairments, while the F3 generation of zebrafish developmentally exposed as embryos to only the higher concentration of MeHg showed persistent learning impairments. Results of the present study showed that learning impairments produced by embryonic MeHg exposure persisted for at least three generations, demonstrating trans-generational effects of embryonic exposure to MeHg.