Induction of oxidative stress and related transcriptional effects of sodium fluoride in female zebrafish liver.

The effects of sodium fluoride (NaF) exposure on the induction of oxidative stress and alteration of gene expressions were studied in the liver of female zebrafish (Danio rerio). Zebrafish, exposed to 15 ppm NaF for 30 and 90 days, exhibited liver histopathology including hyperplassia, cytoplasmic degeneration and nuclear fragmentation. Antioxidant enzyme (GST, CAT, SOD) activities in the liver altered significantly; the mRNA levels for the genes encoding antioxidant proteins, such as Gst, Cat, Cu/ZnSod, MnSod as well as Gpx were significantly upregulated at 30 days NaF-treatment along with the stress marker gene Hsp70 and phase I detoxyfying gene Cyp1A1. Moreover, the transcriptional pattern of Ucp2, related to mitochondrial reactive oxygen species (ROS) production, upregulated significantly at 90 days NaF-treatment. ROS generation was evidensed by fluoroscence microscopy. The results of this study will help to understand the mechanism of oxidative stress induced by NaF in fish.