TOXIC EFFECTS OF ALUMINUM ON ZEBRAFISH LARVAE

Aluminum is the most abundant metal in the Earth’s crust. Alzheimer’s diseaseand Parkinson’sdiseasehave been previously associated with the presence of this metal (Bondy S.C.,Neurotoxicology, 31, 575-581; 2010). In this work the toxicity of aluminum was evaluated on the developmentof the zebrafish nervous system.Zebrafish larvae at protruding mouthstage were exposed to different concentrations of aluminum chloride (AlCl3) for 72 hours to test the lethality index.The mortality and the phenotypic analysis were determined after 24, 48 and 72 hours of treatment.A reduction of the response to stimuli in live larvae was observed from 100 uM of AlCl3 just after 24 hours of the exposition and the severity of this abnormality was directly proportionate to the increase of the concentration used. Pericardial edema and impaired cardiac functionwere present in 50% of these larvae after 48 hours. In the light of these results sections of zebrafish larvae, after 48 hours of the exposure at 100 uM of AlCl3,were enclosedin paraffin and processed by ABC technique and TUNEL assay. The experiments of immunohistochemistry performed with a polyclonal antibody anti-GFAP, marker of glial cells, at a dilution of 1/300 showed a reduction of signal intensity in allareas of larvaebrainwith largest decreases in the hindbrain. An increase of the apoptotic cellswas also observed in the brain through TUNEL test.These data show a toxic effect exerted by aluminum on glial cells.Since the glia plays an important role on the functionality and protection of nerve cells, this effect could be the basis of the development ofneurological disordersinduced by this metal.