Dynamic changes in circulating 1,25-dihydroxyvitamin D during reproduction in rats.
The concentrations of 1,25-dihydroxyvitamin D [1,25-(OH)2D], calcium, and phosphorus were measured in the serum of rats during pregnancy and at various stages of lactation. The concentration of 1,25-(OH)2D hormone increased almost two-fold during pregnancy and the latter part of lactation, but decreased to control levels or very low values immediately after birth and weaning, respectively. Furthermore, the concentration of 1,25-(OH)2D was inversely correlated with the concentration of calcium, suggesting that circulating 1,25-(OH)2D fluctuates in concert with calcium demands during the reproductive cycle. Parathyroidectomy in lactating rats caused a 70 percent inhibition of the normally observed 1,25-(OH)2D increase, indicating that parathyroid hormone, in response to changes in serum calcium, is a primary modulator of 1,25-(OH)2D during lactation.
D000818:Animals; D002118:Calcium / Q000097:blood; D004100:Dihydroxycholecalciferols / Q000097:blood*; D005260:Female; D006887:Hydroxycholecalciferols / Q000097:blood*; D007774:Lactation; D010280:Parathyroid Glands / Q000502:physiology; D010281:Parathyroid Hormone / Q000502:physiology; D010758:Phosphorus / Q000097:blood; D011247:Pregnancy; D011270:Pregnancy, Animal; D051381:Rats
D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D010758:Phosphorus; D002118:Calcium