Effect of 1,25(OH)2D3 and 24,25(OH)2D3 on experimental rickets

Abstract

The vitamin D3 metabolite 1,25(OH)2D3 alone may not be able to reverse defective bone mineralization, while a combination with another metabolite, 24,25(OH)2D3 might be necessary to display the known effect of vitamin D on bone. Growing rachitic rats were treated with 25 ng vitamin D3/d, 10 ng 1,25(OH)2D3/d, 10 ng 24,25(OH)2D3/d, 5 ng 1,25(OH)2D3/d and 5 ng 24,25(OH)2D3/d in combination and 10 ng 1,25(OH)2D3/d and 10 ng 24,25(OH)2D3/d in combination. After 10 days of treatment the epiphyseal plate width of femura and the distance of tetracycline fluorescence bands were measured microscopically on undecalcified sections of the bone. The calcium content of femur epiphysis was measured by neutron activation analysis. Neither parameter showed on greater effect of the combination of 1,25(OH)2D3 and 24,25(OH)2D3 than of 1,25(OH)2D3 alone.