title: Hormonal control of intestinal calcium-binding protein concentrations at weaning in rats.
abstract: In rats, the intestinal concentration of immunoreactive Ca-binding protein was shown to increase at weaning. We now report that injections of 1,25-dihydroxycholecalciferol (1,25(OH)2D3, 25 ng or 10 ng/day) in suckling rats on days 11, 12 and 13 induce a premature rise of the intestinal Ca-binding protein concentrations, associated with increased plasma Ca concentrations. No effect is seen after 25-hydroxycholecalciferol, or after hydrocortisone administration. L-Thyroxine, at high doses (50 micrograms/day) and at more physiological doses (2 micrograms/day) induces a significant rise of the intestinal Ca-binding protein concentrations and a decrease of plasma Ca concentrations. The association of 1,25(OH)2D3 (at 10 ng/day) and L-thyroxine (at 2 micrograms/day) does not cause an additive effect on Ca-binding protein concentrations and does not change plasma Ca. These results suggest that 1,25(OH)2D3 and thyroxine are probably involved in the regulatory mechanisms of the intestinal Ca-binding protein synthesis at weaning.
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D006854:Hydrocortisone / Q000502:physiology*; D006887:Hydroxycholecalciferols / Q000494:pharmacology; D007420:Intestine, Large / Q000378:metabolism*; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*; D013974:Thyroxine / Q000502:physiology*; D014886:Weaning
chemical_list: D002135:Calcium-Binding Proteins; D006887:Hydroxycholecalciferols; D064030:S100 Calcium Binding Protein G; D013974:Thyroxine; D002118:Calcium; D006854:Hydrocortisone