Characterisation of element profile changes induced by long-term dietary supplementation of zinc in the brain and cerebellum of 3xTg-AD mice by alternated cool and normal plasma ICP-MS

Metal dyshomeostasis plays a crucial role in promoting several neurodegenerative diseases including Alzheimer's disease (AD), a condition that has been linked to deregulation of brain levels of Al, Fe, Mn, Cu, and Zn. Thus, quantitative multi-element profiling of brain tissues from AD models can be of great value in assessing the pathogenic role of metals as well as the value of therapeutic interventions aimed at restoring metal homeostasis in the brain. In this study, we employed low resolution inductively coupled plasma mass spectrometry (ICP-MS) to evaluate levels of ultra-trace, trace, and major elements in brains and cerebella of 3xTg-AD mice, a well characterized transgenic (Tg) AD model. This method is based on alternated cool and hot plasma ICP-MS. The essay fulfilled analytical requirements for the quantification of 14 elements in the Central Nervous System (CNS) of our Tg model. Quantification of Li, Al, Cr, and Co, a procedure that requires a pre-concentration step, was validated by high resolution ICP-MS. Changes in element profiles occurring in 3xTg-AD mice were compared to the ones observed in wild type (WT) mice. We also investigated variations in element profiles in 3xTg-AD mice receiving a long-term (17 months) dietary supplementation of Zn. Our data indicate that, compared to WT animals, 3xTg-AD mice displayed signs of altered brain metal homeostasis. We also found that long-term Zn administration promoted decreased brain levels of some metals (K, Ca, and Fe) and restored levels of Al, Cr, and Co to values found in WT mice.