Neurotoxicity Assessment of Perfluoroundecanoic Acid (PFUnDA) in Developing Zebrafish (Danio rerio)

Aquatic species are exposed to several long-chain per- and polyfluoroalkyl substances (PFASs) in the environment but their potential toxicity is not well studied. In this study, we assessed the effects of perfluoroundecanoic acid (PFUnDA) exposure on developing zebrafish. To do this, we investigated the potential for oxidative stress and neurotoxicity by measuring reactive oxygen species, apoptosis, gene expression, and locomotor activity. Mortality was evident in fish exposed to 1000 µg/L PFUnDA, and apoptosis was indicated in fish exposed to 100 µg/L PFUnDA via an increase in <i>casp3</i> transcription. No change in reactive oxygen species in 7-day-old larval fish exposed to 0.01 up to 1000 µg/L PFUnDA was detected. Visual motor response analysis revealed hypoactivity in different light-dark periods that occurred in a concentration-specific manner. At the transcriptional level, several neurotoxicity-related genes (<i>casp3</i>, <i>bdnf</i>, <i>gfap</i>, <i>gmfb</i>, <i>nkx2-2a</i>) were significantly upregulated, further supporting neurotoxic effects. Overall, these findings indicate that PFUnDA disrupts neurodevelopment and behavior in zebrafish larvae, raising concerns for this long-chain PFAS.