Acute Toxicity and Oxidative Stress Responses in Tadpole of Skittering Frog, Euphlyctis cyanophlyctis (Schneider, 1799) to Sodium Fluoride Exposure.

Abstract

This study evaluated the acute toxicity and oxidative stress responses to sodium fluoride (NaF) exposure in tadpoles of the skittering frog, Euphlyctis cyanophlyctis (Schneider 1799). The 96h LC50 value was found to be 647mg/L. Biochemical tests were conducted at 10%, 20%, 30%, 40%, 50%, 60%, 70% and 80% of the 96h LC50 dose. Cholinesterase (ChE) activity was unaffected. Lipid peroxidation levels significantly increased (p < 0.05) at lower concentrations, but decreased significantly with increasing NaF concentrations. Glutathione S-transferase (GST) activity also increased significantly with increasing NaF concentrations. Alkaline phosphatase levels steadily decreased with increasing concentrations of NaF. The responses for the biochemical tests were summarized using an integrated biomarker response (IBR) index approach, which indicated that lower NaF exposures caused higher levels of oxidative stress responses overall. These findings suggest that the IBR index approach may be useful for the quantitative monitoring of NaF toxicity in amphibians.