Neurobehavioral impairments produced by developmental lead exposure persisted for generations in zebrafish (Danio...

The zebrafish has become a useful animal model for studying the effects of environmental contaminants on neurobehavioral development due to its ease of breeding, high number of eggs per female, short generation times, and a well-established avoidance conditioning paradigm. Using avoidance conditioning as the behavioral paradigm, the present study investigated the effects of embryonic exposure to lead (Pb) on learning in adult zebrafish and the third (F3) generation of those fish. In Experiment 1, adult zebrafish that were developmentally exposed to 0.0, 0.1, 1.0 or 10.0μM Pb (2-24h post fertilization) as embryos were trained and tested for avoidance responses. The results showed that adult zebrafish hatched from embryos exposed to 0.0 or 0.1μM Pb learned avoidance responses during training and displayed significantly increased avoidance responses during testing, while those hatched from embryos exposed to 1.0 or 10.0μM Pb displayed no significant increases in avoidance responses from training to testing. In Experiment 2, the F3 generation of zebrafish that were developmentally exposed to an identical exposure regimen as in Experiment 1 were trained and tested for avoidance responses. The results showed that the F3 generation of zebrafish developmentally exposed as embryos to 0.0 or 0.1μM Pb learned avoidance responses during training and displayed significantly increased avoidance responses during testing, while the F3 generation of zebrafish developmentally exposed as embryos to 1.0 or 10.0μM Pb displayed no significant changes in avoidance responses from training to testing. Thus, developmental Pb exposure produced learning impairments that persisted for at least three generations, demonstrating trans-generational effects of embryonic exposure to Pb.