1α,25-Dihydroxyvitamin D3 Reduces Cerebral Amyloid-β Accumulation and Improves Cognition in Mouse Models of Alzheimer's Disease

We demonstrate a role of the vitamin D receptor (VDR) in reducing cerebral soluble and insoluble amyloid-beta (A beta peptides. Short-term treatment of two human amyloid precursor protein-expressing models, Tg2576 and TgCRND8 mice, with 1 alpha,25-dihydroxyvitamin D-3 [1,25(OH)(2)D-3], the endogenous active ligand of VDR, resulted in higher brain P-glycoprotein (P-gp) and lower soluble A beta levels, effects negated with coadministration of elacridar, a P-gp inhibitor. Long-term treatment of TgCRND8 mice with 1,25(OH)(2)D-3 during the period of plaque formation reduced soluble and insoluble plaque-associated A beta, particularly in the hippocampus in which the VDR is abundant and P-gp induction is greatest after 1,25(OH)(2)D-3 treatment, and this led to improved conditioned fear memory. In mice fed a vitamin D-deficient diet, lower cerebral P-gp expression was observed, but levels were restored on replenishment with VDR ligands. The composite data suggest that the VDR is an important therapeutic target in the prevention and treatment of Alzheimer's disease.