A magnesium (Mg) deficiency induces changes in calcium (Ca) and phosphorus (P) metabolism; however, the mechanisms responsible for these effects remain unclear. Since 1,25-dihydroxyvitamin D3 and type II sodium-phosphate (Na/Pi) cotransporters are essential regulators of Ca and P metabolism, this study examined the effects of Mg deficiency on the mRNA expression of vitamin D metabolizing enzymes (25-hydroxyvitamin D-1α-hydroxylase (1α(OH)ase) and 25-hydroxyvitamin D-24-hydroxylase (24(OH)ase)), and Na/Pi cotransporters (type IIa and IIc) in the rat kidney. Rats were divided into two groups and fed a control diet (Mg concentration: 0.05%) or a Mg-deficient diet (Mg concentration: Mg-free) for 21 days. 1α(OH)ase mRNA levels were significantly decreased in rats fed the Mg-deficient diet, while 24(OH)ase mRNA levels were significantly increased, compared to rats fed the control diet. Type IIa and IIc Na/Pi cotransporter mRNA levels in rats fed the Mg-deficient diet were significantly decreased compared to rats fed the control diet. These results suggest that Mg deficiency induces downregulation of 1α(OH)ase and type IIa and IIc Na/Pi cotransporters, and upregulation of 24(OH)ase in the kidney.
Keywords: Na/Pi cotransporter; magnesium deficiency; rats; vitamin D metabolizing enzyme.