Full length articleNeurobehavioral impairments produced by developmental lead exposure persisted for generations in zebrafish (Danio rerio)

- We investigated the effects of embryonic lead exposure on learning in adult zebrafish and the third generation of those fish.
- The zebrafish developmentally exposed to lead as embryos showed learning impairments in a concentration-dependent manner.
- The third generation of zebrafish developmentally exposed as embryos to the higher concentrations of lead showed persistent learning impairments.
- The present study showed that learning impairments produced by embryonic lead exposure persisted for generations.

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 10.0 μM Pb (2-24 h 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 0.1 μM Pb learned avoidance responses during training and displayed significantly increased avoidance responses during testing, while those hatched from embryos exposed to 1.0 or 10.0 μM 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 0.1 μM 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 10.0 μM 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.