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Functional Assays and Alternative Species: Using Larval Zebrafish in Developmental Neurotoxicity Screening**
Citation:
Padilla, S., M. Culbreth, R. MacPhail, D. Hunter, K. Jarema, K. Jensen, J. Olin, AND A. Tennant. Functional Assays and Alternative Species: Using Larval Zebrafish in Developmental Neurotoxicity Screening**. Presented at Society of Toxicology Meeting, Phoenix, AZ, March 23 - 27, 2014.
Impact/Purpose:
This assay simultaneously tests individual zebrafish under both light and dark conditions in a 96-well plate using a video tracking system.
Description:
The U.S. Environmental Protection Agency is evaluating methods to screen and prioritize large numbers of chemicals for developmental toxicity. As such, we are exploring a behavioral testing paradigm, which can assess the effect of sublethal and subteratogenic concentrations of developmental neurotoxicants on 6 day larval zebrafish (Danio rerio). This assay simultaneously tests individual zebrafish under both light and dark conditions in a 96-well plate using a video tracking system. By controlling the duration and intensity of light, we are able to detect changes in locomotion during light-dark transitions, and adaptation to both light and dark during the approximate 1.5 hour testing period. Multiple chemicals at several concentrations (<120 uM nominal concentration) can be tested in large numbers of larvae using this method. We have evaluated a training set of chemicals (n=22) that are generally considered positive(n=16) or negative (n=6) controls for developmental neurotoxicity in mammals. Many of the developmentally neurotoxic compounds perturbed behavior at subteratogenic doses (e.g, lead, heptachlor, chlorpyrifos, chlorpyrifos oxon), while many non-neurotoxic compounds did not (e.g., acetaminophen, saccharin, glyphosate). Exposure to developmental neurotoxicants altered the overall activity level in light and dark conditions, and/or the activity pattern. The zebrafish neurodevelopmental assay using this training set of chemicals had a sensitivity of 0.875 and a specificity of 0.833. The training set results, therefore, indicate that careful evaluation of zebrafish larvae behavior is capable of identifying mammalian developmental neurotoxicants. This abstract may not necessarily reflect official Agency policy.