title: Effects of high doses of vitamin D3 and 1,25-dihydroxyvitamin D3 in lactating rats on milk composition and calcium homeostasis of the suckling pups.
abstract: Changes in serum Ca and phosphorus and in kidney Ca were determined in lactating rats and their suckling pups after the mothers received high doses of vitamin D3 or 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. High dietary vitamin D3 intake (300 IU/g diet) or daily oral doses of vitamin D3 (1 microgram/g BW) to vitamin I)-replete (+D) lactating rats for 8 or 12 days caused significant increases in serum Ca in the mothers (1-2 mg/dl) and in their suckling pups (1.5 mg/dl). Daily oral doses of 1,25-(OH)2D3 (2 ng/g BW) to +D lactating rats caused a similar increase in serum Ca in the mothers, but did not affect the serum Ca of the pups. The administration of a high dose of 1,25-(OH)2D3 to vitamin D-deficient lactating rats or high doses of vitamin D3 to +D rats, caused no change in milk Ca, Mg, or phosphorus. Milk from +D rats given high doses of [3H]vitamin D3 (1 microgram/g BW) contained mostly [3H]vitamin D3 (85%) and a small amount of [3H]25-hydroxyvitamin D3 (6%). The results indicate that high doses of vitamin D3, but not 1,25-(OH)2D3, given to +D lactating rats can cause hypercalcemia in the suckling pups. The hypercalcemic effect on the pups observed after vitamin D3 treatment of the mother is probably a result of transport of toxic amounts of primarily vitamin D3 into the milk and is not due to altered mineral composition of the milk.
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002762:Cholecalciferol / Q000494:pharmacology*; D005260:Female; D006706:Homeostasis / Q000187:drug effects*; D007774:Lactation / Q000187:drug effects*; D008892:Milk / Q000187:drug effects / Q000378:metabolism*; D008903:Minerals / Q000032:analysis; D011247:Pregnancy; D051381:Rats; D014807:Vitamin D / Q000097:blood / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000378:metabolism
chemical_list: D008903:Minerals; D014807:Vitamin D; D002762:Cholecalciferol; D002117:Calcitriol; D002118:Calcium