Embryonic exposure to cadmium (II) and chromium (VI) induce behavioral alterations, oxidative stress and immunotoxicity in zebrafish (Danio rerio)

Cadmium (Cd) and chromium (Cr) are considered as the main environmental contaminants which have serious risks for health. Firstly, we observed that the hatchability was significantly decreased by exposure to 10 mu M Cd for 60 and 96 h post fertilization (hpf). And some abnormalities in embryos and larvae were observed especially in the 10 mu M Cd treated group. Moreover, the free swimming activities and the swimming behaviors of the larval zebrafish in response to the stimulation of light-to-dark photoperiod transition were significantly influenced by both Cd and Cr treatments. Secondly, Cd and Cr exposure induced the changes in oxidative stress of the larval zebrafish. The malondialdehyde (MDA) levels increased and the glutathione (GSH) contents decreased significantly after the exposure to Cd or Cr for 96 hpE Cd or Cr affected not only the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione S-transferase (GST), but also the transcriptional levels of their respective genes. Thirdly, with regard to the immune response, the mRNA levels of the main cytokines including tumor necrosis factor alpha (TNF alpha), interleukin-6 (IL-6) and interleukin-1 beta (IL-1 beta) in the larvae increased significantly after the exposure to Cd and Cr for 96 hpE Our results suggested that Cd and Cr have the potential to cause behavior alterations, oxidative stress and immunotoxicity in the larval zebrafish. (C) 2015 Elsevier Inc. All rights reserved.