Embryonic Lead Acetate Exposure Induces Seizure-like Activity in Zebrafish Larvae.

Background/

Objectives

Despite the decades-old ban on lead in fuel, plumbing, consumer goods, industrial processes, and various materials, it remains a public health threat due to its persistent nature. Zebrafish (Danio rerio) are highly effective for modeling several disorders, including those affecting neurological and behavioral functions, and are well-suited for assessing the impact of environmental toxins like lead. This study aimed to investigate the neurodevelopmental effects of embryonic lead exposure using the zebrafish model system.

Methods

Embryos were exposed to lead acetate (PbAc) at concentrations ranging from 0.3 to 0.7 µg/mL using an exposure window of 6 to 48 h post-fertilization (hpf).

Results

PbAc exposure produced sublethal teratogenic effects in a subset of larvae across concentrations, including tail and spinal deformities, craniofacial abnormalities, and uninflated swim bladder observed at 7 dpf. At 3 days post-fertilization (dpf), spontaneous circle swimming behavior suspected to be seizure-like was observed in the lead-exposed larvae and was more pronounced under light conditions in a dose-dependent manner. Electrophysiological recordings confirmed that larvae exhibiting circle swimming behavior had heightened neural activity, indicating a potential seizure-like phenotype driven by lead exposure.

Conclusions

Our findings suggest that embryonic lead exposure leads to morphological defects and seizure susceptibility, demonstrating lead's neurotoxic potential during early development. Seizure-like behaviors occurred in a non-linear concentration-dependent manner with a photosensitive component, and elevated baseline neural excitability was confirmed by local field potential (LFP) recordings.