Aluminium induced phenotypical alterations, apoptosis and oxidative stress in zebrafish larvae

Aluminium (Al) is among the most abundant metals in nature, and its presence in the environment has been further increasing by anthropogenic activities. In water bodies, the Al concentrations ranged from 0.001 until to 50 mg/L, raising concerns on environmental safety and human health. In this study, zebrafish was chosen as the model since is well suited for ecotoxicological studies. Embryos (6 hpf) were exposed for 72 hours at concentrations of 1.40, 2.80 and 5.60 mg/L of Al respectively and the effects of this metal were assessed on the development of phenotypic alterations and on the apoptosis by acridine orange staining. Moreover, having previously verified that Al altered neurobehavioral activity, it was also paid particular attention to induced oxidative stress, as potential mechanisms of Al toxicity. Precisely, it was analysed the involvement of ROS, the activity of the main antioxidant enzymes, metallothioneins contents, but also oxidative damage and enzymes involved in energy consumption and in neuromuscular transmission. Collected data showed that Al significantly affected the development of zebrafish inducing morphological alterations such as deviations of the axis and/or tail, swelling of yolk sac and pericardial edema and also the increase of cell death. As for the oxidative state of the larvae, the levels of ROS decreased with increasing Al concentration, while the activity of SOD, GST and the GSH/GSSG levels, remained mostly constant for all tested concentrations. Instead, the activity of GPx and AChE increased linearly with the concentrations, and ATPase activity was lower in all treated than controls. Finally, the lipidic and protein oxidative damage worsened in a dose-dependent manner, while metallothioneins' levels decreased dramatically only at higher concentration tested. The overall information obtained gives a realistic snapshot of Al toxicity and provide new information on the mechanism of action of this metal, as widespread as dangerous.