title: Vitamin D-dependent calcium-binding protein of rat intestine: changes during postnatal development and sensitivity to 1,25-dihydroxycholecalciferol.
abstract: To study the role of the vitamin D-endocrine system during the perinatal period, we monitored vitamin D-dependent calcium-binding protein (CaBP) in rat intestine by radial immunodiffusion and polyacrylamide disc gel electrophoresis. Small amounts of CaBp were present 2 days before birth; these levels increased 74-fold by day 38 after birth. Approximately 80% of the increase in CaBP concentration occurred in a 5-day period at the time of weaning (days 17--22 after birth). Before this period, the concentration of CaBP was comparable to that found in rachitic (adult) rats. Administration of 1,25-dihydroxycholecalciferol to suckling rats on days 15 and/or 16 was followed by a premature increase in the amount of intestinal CaBP. These data demonstrate that although vitamin D-dependent CaBP is low in preweaned rats, the rat intestine is responsive to exogeneous 1,25-dihydroxyvitamin D3 at least as early as day 15 after birth. The close temporal correspondence between the increases in CaBP and previously reported changes in calcium transport and vitamin D metabolism suggest that the vitamin D-endocrine system plays a role in postnatal intestinal maturation and adaptation during the weaning period.
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000097:blood; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D005260:Female; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D007421:Intestine, Small / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*
chemical_list: D002135:Calcium-Binding Proteins; D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D064030:S100 Calcium Binding Protein G; D002118:Calcium