We evaluated the effects of vitamin D<sub>3</sub> (VD<sub>3</sub>) supplementation on morphofunctional aspects and the repercussions on the presence and localization of Aβ<sub>42</sub>, methylenetetrahydrofolate reductase (MTHFR), caspase-3 p12, and P-glycoprotein (Pgp) in the renal tissue of DS mouse model.