O COMPORTAMENTO COMO UM SINAL PRECOCE DE TOXICIDADE E LESÕES NO SISTEMA RESPIRATÓRIO INDUZIDAS POR CÁDMIO EM ZEBRAFISH

The aim of the present study was to determine the validity of behavior as an early sign of toxicity and respiratory injuries induced by acute exposure to cadmium in adult zebrafish (Danio rerio). The effects of three cadmium concentrations (35, 45, and 55 µg/L) on zebrafish behavior (i.e., general activity, exploratory/motor behavior, climbing to the water surface, tremors, and erratic movements) and gill histology after 1 h of exposure was assessed.  Compared with controls, cadmium exposure increased the number of climbs to the water surface and total time spent at the water surface, increased the percentage and intensity of tremors, and increased erratic movements. Cadmium exposure also caused stage I injury to the gills, with the presence of chloride cells in secondary lamellae, dilation of the capillaries, hyperplasia of the gill epithelium, and fusion of the secondary gill lamellae. These effects were observed mainly at concentrations of 45 and 55 µg/L. Our results indicate that 45 and 55 µg/L cadmium induces behavioral dysfunction and 55 µg/L significant gill injury, even with only 1 h exposure, revealing respiratory system impairments. The present model may be an interesting tool for analyzing early toxicity and respiratory injuries  in fish.