William A. Cisneros

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.

Voltage-gated sodium channels (VGSCs) play pivotal roles in cellular function, particularly in the regulation of electrical signaling. Structural defects in these channels cause deleterious effects in a myriad of cell types, leading to various diseases, like epilepsy, cardiac arrythmias, kidney disease, and certain cancers. Over the past decade, significant efforts have been geared toward developing drugs that target the pore domains of these channels, called pore-blocking agents. This approach has seen several setbacks, commonly due to the lack of isoform-specific binding. Alternative targeting strategies are being used to reduce or eliminate the side effects of pore-blocking agents. Transgenic mouse models have proven useful in such studies, and subtype-selective inhibitors were developed. The zebrafish model system was also used to explore neurological, cardiovascular, and metabolic diseases caused by voltage-gated sodium channel dysfunction. Here, we delve into the growing literature on the structure and function of voltage-gated sodium channels, their role in epilepsy and its comorbidities, and the advancement in the use of zebrafish as a model system to explore these channels as therapeutic targets.