Developmental sub-chronic exposure to chlorpyrifos reduces anxiety-related behavior in zebrafish larvae

Abstract

Neurobehavioral disorders such as anxiety, autism, and attention deficit hyperactivity disorders are typically influenced by genetic and environmental factors. Although several genetic risk factors have been identified in recent years, little is known about the environmental factors that either cause neurobehavioral disorders or contribute to their progression in genetically predisposed individuals. One environmental factor that has raised concerns is chlorpyrifos, an organophosphate pesticide that is widely used in agriculture and is found ubiquitously in the environment. In the present study, we examined the effects of sub-chronic chlorpyrifos exposure on anxiety-related behavior during development using zebrafish larvae. We found that sub-chronic exposure to 0.01 or 0.1 μM chlorpyrifos during development induces specific behavioral defects in 7-day-old zebrafish larvae. The larvae displayed decreases in swim speed and thigmotaxis, yet no changes in avoidance behavior were seen. Exposure to 0.001 μM chlorpyrifos did not affect swimming, thigmotaxis, or avoidance behavior and exposure to 1 μM chlorpyrifos induced behavioral defects, but also induced defects in larval morphology. Since thigmotaxis, a preference for the edge, is an anxiety-related behavior in zebrafish larvae, we propose that sub-chronic chlorpyrifos exposure interferes with the development of anxiety-related behaviors. The results of this study provide a good starting point for examination of the molecular, cellular, developmental, and neural mechanisms that are affected by environmentally relevant concentrations of organophosphate pesticides. A more detailed understanding of these mechanisms is important for the development of predictive models and refined health policies to prevent toxicant-induced neurobehavioral disorders.

Automated High-throughput Behavioral Analyses in Zebrafish Larvae

“…Many trials have been performed to optimize the results of the assay, such as color of stimulus used, ideal number of larvae per lane, and length of behavioral assay. Previously, we used multi-well plates (with 6 or 12 wells) 15,17,18 . However, recently we have created the novel lane mold to create a larger swimming space for the larvae allowing us to gather a larger number of behavioral measures in a single assay 16 ( Figure 5).…”

“…A PowerPoint presentation is used as an aversive stimulus for the larvae. In the past moving red balls were shown to zebrafish larvae in 6 or 12 multi-well plates 15,17,18 . The current PowerPoint starts with a blank white background for 15 min, followed by 15 min of a moving red bar on the top half of the plate (Figure 4).…”

“…The system allows us to quickly and efficiently test subtle behavioral abnormalities after embryonic exposure to a number of pharmaceuticals and environmental toxicants [16][17][18] .…”

The Effect of Chronic Intoxication With Low Doses of Chlorpyrifos on the Behavioral Parameters of Female Rats

“…Можливість негативного впливу ХПФ на функціонування нервової системи показана у дослідах з тваринами різних видів та класів. Субхронічне введення невеликих доз (0,01 та 0,1 мкмоль/л) ХПФ малькам акваріумних риб Danio rerio змінює їхню поведінку, що виражається, зокрема, у зниженні швидкості плавання, тигмотак-сисі, зростанні тривожності [7]. Показано, що вплив невеликих доз ХПФ на мишенят протягом неонатального періоду спричиняє порушення розвитку їхнього мозку та по-силення статевих відмінностей поведінки [8].…”

Zebrafish as a Model to Study Autism Spectrum Disorder Caused by Environmental Chemicals Exposure

“…WSF significantly increases anxiety and locomotor activity, decreases repetitive behavior in the open field test, and reduces the level of serotonin [35]. Many studies prove that maternal exposure to neurotoxic environmental contaminants, such as chlorpyrifos, nickel chloride, and arsenic impair the movement activity of zebrafish larvae [36][37][38]. However, co-exposure to WSF/Pb decreased behavioral activity and shoaling behavior and increased cycle swimming and edge preference.…”