CADMIUM EFFECTS AT A SUB-LETHAL CONCENTRATION IN EMBRYOS AND ADULTS OF DANIO RERIO

Cadmium is known as a biologically not essential-metal and as toxic agent for many organs, including brain. It is in fact in the list of top 20 hazardous substances. Cadmium can be toxic even at low doses since it accumulates and has a long biological halflife. In the last years, this metal has also been indicated as a possible etiological factor in neurodegenerative diseases1. Recently we demonstrated that cadmium accumulates in Danio rerio brain in which it induces evident histo-morphological damages and alterations of glial cells, key components of the protection and function of neurons2,3. In this study we have analysed the effects of cadmium on embryos and adult specimens of D. rerio exposed to 1mg/L of CdCl2. Embryos of 6hpf were exposed to CdCl2 and observed after 24 and 48 hours; adult were instead treated for 16 days and analysed at 2, 7 and 16 days. Acridine orange staining was used for the study of cell death in wholemount embryos; the Fluoro-Jade B histochemical stain and the immunohistochemical revelation of amyloid1-42 peptide were instead applied on sections of adult brains to observe the occurrence of degenerative processes. Western blotting experiments were also performed to verify the antibody specificity and to analyse quantitatively the accumulation levels of amyloid1-42 peptide in adult brains. Collected data show that at 1mg/L of CdCl2 cadmium induces neurodegeneration in the adult and an increase of cell death in embryos. Considering cadmium implications in neurodegenerative disorders, interestingly enough is the observation of the increased levels of amyloid1-42 peptide in treated fish brain. Since this peptide is the principal pathological agent in Alzheimer’s disease and other amyloidopathies this study might represent a starting point for discovering possible correlations between cadmium and neurological disorders using D. rerio as model organism.