Effects of acute triclosan exposure on gill and liver tissues of zebrafish (Danio rerio)

Triclosan (TCS) is a broad-spectrum antimicrobial agent found in personal care, household, veterinary, medical, and industrial products. TCS has been detected in soil, sediment, and surface water. In the current work, the effects of acute exposure to TCS on gill and liver tissues of zebrafish were evaluated. Adult zebrafish were treated with sublethal concentrations of TCS (34, 85, and 170 μg/L) for 120 h. Gill and liver samples were removed and embedded in paraffin for histopathological investigations. TCS induced aneurysm, capillary dilation, lamellar disorganization, hyperplasia, epithelial lifting, and desquamation in the gills. Liver specimens showed sinusoidal dilation, congestion, vacuolization, hepatocellular degeneration, and necrosis. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to observe the apoptotic effect of TCS. Accordingly, no apoptotic cells were detected in the specimens of 34 μg/L of TCS exposed gills, while the slides of 85 and 170 μg/L of TCS treated gills showed a high number of TUNEL-positive cells. In the liver, no TUNEL-positive cells were identified in 34 μg/L of TCS treated samples of zebrafish. 85 and 170 μg/L of TCS exposed livers showed few hepatic parenchymal cells undergoing apoptosis.