Temporal Dynamics of c-Fos Expression in a Zebrafish Larva Model of Pentylenetetrazole-Induced Seizures

The use of zebrafish (<i>Danio rerio</i>) larva as an experimental model has gained a lot of interest in epilepsy research due to its multiple advantages over mammalian models. The present study investigated the time-dependent expression of <i>c-fos</i>, an immediate early gene, and a marker of neuronal activation, following pentylenetetrazole (PTZ)-induced seizures in zebrafish larvae at 7-day post-fertilization . The larvae were exposed to 8 mM PTZ for a 15-min period, transferred to fish system water, and processed for c-Fos expression analysis at 15, 30, 45, 60, and 90 min of the start of the experiment. <i>c-fos</i> mRNA and c-Fos protein levels were quantified, and Pearson correlation analysis was conducted to assess their relationship. PTZ exposure induced seizure-like behavior and resulted in a dynamic temporal expression of c-Fos, with both mRNA and protein achieving peak levels at 45 min and declining by 90 min. This approach applied a fixed exposure duration and defined post-exposure time points, which allowed a more accurate temporal profiling. The observed peak expression at 45 min suggested an optimal window for evaluating c-Fos expression in the PTZ-induced seizures model of zebrafish larva. These findings provided a valuable reference for selecting experimental endpoints in zebrafish larva seizure studies and enhanced the reliability of c-Fos as a marker of neuronal activation.