Embryonic Methylene Chloride Exposure has a Concentration-Dependent Behavioral Effect on Embryonic Development of Zebrafish

Abstract

Methylene Chloride (CH2Cl2, MC) is a volatile chemical found in aerosol and pesticide products. Zebrafish swimming behaviors provide information on neurodevelopmental issues that may be present despite normal morphological development. Previous results in our lab found that 1) for zebrafish exposed to MC for 5 days post-fertilization (dpf), 80ppm MC is the no observable adverse effect level (NOAEL) for morphological phenotypes and 2) 80ppm MC exposure resulted in decreased swimming velocity and distance. Here we tested whether lower MC concentrations affect development of 5 dpf zebrafish swimming behavior. Video analysis of swimming velocities and distances were captured over an alternating light-dark cycle with a commercial motor tracking system (Noldus Danio Vision). Zebrafish were treated with MC concentrations of 0.08 ppm, 0.8 ppm, 8 ppb and vehicle solution. Zebrafish were treated with MC in a 12-well plate from 6 hours post-fertilization (hpf) through 5 dpf. 5 dpf zebrafish were placed into a 96 well plate to run the behavioral assay. We found that exposure of zebrafish embryos to these MC concentrations did not affect the swim velocity or distance traveled. These results suggest that embryonic MC exposure at these levels may not affect neurodevelopment and can inform MC environmental regulations.