Vitamin D3Metabolism in Immature Japanese Quail: Effects of Ovarian Hormones1

Abstract

The possible influence of exogenous estradiol and progesterone injection on in vitro renal metabolism of 25-hydroxyvitamin D3 was investigated in immature (4 wk old) female and male Japanese quail. Estradiol benzoate was injected (3 mg/kg) for 3 consecutive days in 1 female and 1 male group (5 birds/group). One female and 1 male control group received corn oil only. Progesterone (5 mg/kg) and oil were injected similarly in 4 groups of quail. All injections were given i.m. Birds were placed on a normal Ca diet (2.3 to 3.3% Ca) during the treatment period. On the 4th day kidneys were incubated with [3H]-25-(OH)D3 substrate for 20 min. Separation of the vitamin D3 metabolites was done using Sephadex LH-20 and chloroform: Skellysolve B (65:35) solvent system. Heparinized plasma was analyzed for Ca and phosphate. Oviduct, testis and defatted, dried femur weights were recorded. Both females and males treated with estradiol had significantly (P < 0.01) increased production of 1,25-dihydroxyvitamin D3. In the progesterone treated groups, 24,25-(OH)2D3 was the predominant metabolite, although some 1,25-(OH)2D3 was also produced. Plasma Ca and P levels were significantly (P < 0.01) higher only in the estradiol-treated groups. Femur weights (mg/cm) were higher in both estradiol- and progesterone-treated groups but the increase was significant (P < 0.05) only in males. Estrogen can directly or indirectly influence vitamin D3 metabolism in birds.