# Oxidative Stress Signaling and Regenerative Responses in a Larval Zebrafish Model of Retinal Light Damage

## TL;DR

This study explores how oxidative stress influences retinal regeneration in larval zebrafish after light-induced damage, revealing key signaling pathways involved in early repair processes.

## Contribution

The study introduces a validated larval zebrafish model for investigating oxidative stress and early regenerative responses to retinal light damage.

## Key findings

- Larval light-induced retinal damage activates apoptotic and regeneration-associated pathways similar to adult models.
- Oxidative stress modulation affects retinal injury responses, reducing apoptosis and influencing growth signaling.
- Transcriptomic profiling reveals prominent regulation of oxidative stress and antioxidant pathways in larval retinal regeneration.

## Abstract

The zebrafish (Danio rerio) is a widely used model for studying retinal regeneration. In adults, light-induced retinal damage (LIRD) serves as an environmental phototoxic stressor that induces photoreceptor degeneration and regenerative responses, whereas larval models remain comparatively underexplored. In this study, we validate a larval LIRD paradigm as a versatile system for studying acute phototoxic injury and early regeneration-associated transcriptomic responses. Using high-throughput RNA sequencing, we profiled retinal transcriptional changes 48 h post-LIRD and complemented these findings with targeted pharmacological modulation of redox signaling. Larval LIRD induced robust activation of canonical apoptotic and regeneration-associated pathways, recapitulating key features of adult LIRD models while engaging previously underexplored gene-regulatory networks. Among these, pathways related to oxidative stress responses, antioxidant enzymes, and oxygen metabolism were prominently regulated. Functional attenuation of oxidative stress using the N-acetylcysteine reduced phototoxic injury-induced apoptosis and proliferation, while inflammatory markers remained largely unaffected. Conversely, subtoxic intra-retinal hydrogen peroxide exposure was sufficient to induce proliferative markers without eliciting apoptosis response. At the signaling level, modulation of oxidative stress influenced components of growth-associated signaling pathways activated during early injury response. Together, these findings support a role for oxidative stress as a key component of early injury-associated signaling in larval retinal regeneration. This study integrates histological, transcriptomic, and pharmacological analyses to interrogate early regenerative programs and provides a comprehensive transcriptomic resource for exploring redox-associated mechanisms in retinal injury and repair.