Fig. 5.

Age-related changes in renal α-Klotho gene expression could affect renal Cyp27b1 and Cyp24a1 gene expression and plasma 1,25(OH)₂D levels upon intake of the HP diet. When the FGF23/α-Klotho system functions normally, HP diet intake increases plasma FGF23 levels, and decreases plasma 1,25(OH)₂D levels. In this study, it was suggested that 13 month-old mice is FGF23/α-Klotho system malfunction state due to decrease of renal α-Klotho gene expression, and the 1,25(OH)₂D synthesis inhibiting action by HP diet intake may be attenuated.