Organophosphate pesticide exposure affects zebrafish developmental physiology

Abstract

Organophosphate pesticides are known to inhibit acetylcholine esterase, an enzyme that degrades acetylcholine at the cholinergic synapse. In this study zebrafish were used to understand the impact chlorpyrifos, dichlorvos, and diazanon on vertebrate developmental physiology. Pre‐epiboly zebrafish embryos were exposed pesticides at concentrations ranging from 1μM to 1mM. Survival, spontaneous movements, heart rate, swimming behavior, and physical abnormalities were examined. All three pesticides were found to be toxic to developing zebrafish embryos at concentrations at or above than 100 μM. However, disruption of physiological processes controlled by the cholinergic neurons was only seen in embryos exposed to chlorpyrifos and dichlorvos. Chlorpyrifos and dichlorvos exposed embryos exhibited increased spontaneous movements, decreased embryonic heart rate, and a transient decrease in larval swimming ability. Although diazanon was the most toxic, it had no effect on these physiological systems. The effects of organophosphate pesticide exposure on vertebrate development are diverse and may be mediated through pathways other than the inhibition of acetylcholine esterase.