AJP - Endocrinology and Metabolism, Vol 241, Issue 4 275-E280, Copyright © 1981 by American Physiological Society
Vitamin D metabolism in aged Japanese quail: dietary calcium and estrogen effects
S. N. Baksi and A. D. Kenny
The influence of estrogen treatment (estradiol benzoate, 1 mg/kg daily for
5 days) on the in vitro renal metabolism of 25-[3H]hydroxyvitamin D3 has
been studied in young adult (8-wk-old) and aged (108-wk-old) female and
male Japanese quail maintained either on a normal calcium diet or on a
low-calcium diet for 4 wk. It is concluded that senescence leads to reduced
production of 1,25-dihydroxyvitamin D2 [1,25(OH)2D3] in untreated birds of
both sexes and under both dietary conditions. Nevertheless, the renal
vitamin D-endocrine system in aged birds has the capacity, when stimulated
under appropriate conditions (estradiol-treated, calcium-deprived aged
males), for operating at a very high production rate (315 +/- 21 pmol .
min-1 . g kidney-1). The latter rate is not far below the maximal rate (393
+/- 25 pmol . min-1 . g kidney-1) observed in young adult birds that had
been stimulated by calcium deprivation.
