Neurobehavioral toxicity of zebrafish larvae caused by lead exposure at environmentally relevant concentrations

Abstract

Lead (Pb) is recognized as a neurological toxicant. Up to date, Pb neurotoxicity continues to be a major public health problem around the world,especially the link between early developmental Pb exposure and neurological alterations. Zebrafish is considered as a useful model for the identification of the association between early-life low-dose Pb exposure and neurological adverse outcomes. In this study zebrafish embryos/larvae were used as research object and the test methods of the behavioral effects including locomotor activity, rotation activity and social activity were established with Zebrabox, which can systematically evaluate the neurobehavioral toxicity of early-life low-dose Pb exposure (referred from e-waste disposal sites). The normal zebrafish embryos were selected and exposed to Pb at the concentrations of 0, 5, 10,20 μg·L-1 until 6 dpf. The developmental toxicity of zebrafish embryos/larvae was induced by Pb exposure, including the decline of hatching rates and survival rates, and the malformation of yolk-edema, pericardial edema and axial spinal curvature. Pb exposure had no significant impact on the locomotor activity and rotation activity of the zebrafish larvae during the light illumination period. However, in the dark conditions, the locomotor distance and the total rotation times of zebrafish larvae were decreased significantly after exposume to 20 μg·L-1 Pb, and the path angle and orientation preference did not change. Different from the locomotor activity and rotation activity, in the dark conditions, Pb exposure had no significant impact on the social activity of zebrafish larvae. However, the social activity especially the contact times of zebrafish larvae were changed significantly with 20 μg·L-1 Pb exposure. Our results suggest that the behavioral indicators are not only sensitive enough to evaluate the potential risk of Pb pollution at e-waste disposal sites, but can also be applied to establish novel early warning system for health risk assessment.