Bone changes due to pregnancy and lactation: influence of vitamin D status.
The effects of pregnancy and lactation on endosteal bone formation and resorption were evaluated in vitamin D-depleted (-D) and vitamin D-repleted (+D) rats. Pregnancy induced a marked stimulation of osteoclastic bone resorption and of static and dynamic parameters of bone formation and mineralization. Bone resorption increased independently of vitamin D status and did not correlate with plasma 1,25-dihydroxyvitamin D3 [1,25(OH)2D] levels, but it was associated with increased plasma immunoreactive parathyroid hormone (iPTH) concentrations. Stimulation of the endosteal bone formation rate was mainly impaired in D-depleted rats, resulting in trabecular bone loss, which, in -D mother rats, was associated with decreased bone ash and total bone calcium. Lactation further stimulated bone resorption and reduced the trabecular bone volume; ash weight and bone calcium content were also decreased independently of the vitamin D status and changes in plasma iPTH levels. In presence of vitamin D, the bone formation rate increased fourfold during lactation but was unchanged in -D lactating rats. During lactation, vitamin D-depleted rats lost twofold more calcified bone than +D rats because of impaired mineralization. Thus, the present study shows that both the endosteal bone resorption and formation are stimulated by pregnancy and lactation and that vitamin D is required for normal bone mineralization during the reproductive period.
D000818:Animals; D001846:Bone Development; D001862:Bone Resorption; D001842:Bone and Bones / Q000378:metabolism; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000378:metabolism; D005260:Female; D007774:Lactation / Q000502:physiology*; D008903:Minerals / Q000378:metabolism; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D051381:Rats; D014808:Vitamin D Deficiency / Q000503:physiopathology*
D008903:Minerals; D010281:Parathyroid Hormone; D010710:Phosphates; D002117:Calcitriol; D002118:Calcium