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Estrogen Regulation of Intestinal Calcium Absorption in the Intact and Ovariectomized Adult Rat
Author(s) -
ten Bolscher Marieke,
Netelenbos J. Coen,
Barto Rob,
van Buuren Lotti M.,
van der vijgh Wim J. F.
Publication year - 1999
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1999.14.7.1197
Subject(s) - ovariectomized rat , calcitriol , medicine , endocrinology , calcium , estrogen , calcium metabolism , estrogen receptor , estradiol benzoate , cholecalciferol , chemistry , biology , cancer , breast cancer
Abstract Studies were carried out to examine the mechanism of action of estrogen on intestinal calcium absorption in the rat. Three‐month‐old Wistar rats were sham‐operated or ovariectomized (OVX). They were fed a diet containing 0.4% Ca, 0.4% P, and 2000 IU vitamin D 3 /kg. Eight weeks after operation, both OVX and sham‐operated rats were randomly assigned to eight treatment groups. Five groups received per 100 g of body weight 12.5 ng calcitriol (1,25‐dihydroxyvitamin D 3 ); 7.5 μg of estradiol‐benzoate; 7.5 μg of estradiol‐benzoate and 0.1 mg of ICI 182780; 12.5 ng of calcitriol and 0.1 mg of ICI 182780; and 0.1 mg of ICI 182780, respectively. Three groups received the various vehicles used. Intestinal calcium absorption was measured in vivo using single pass perfusion of the duodenum. OVX did not change intestinal calcium absorption. A pharmacological dose of estradiol‐benzoate caused a significant increase in intestinal absorption of calcium, which was comparable to that of a pharmacological dose of calcitriol in both OVX and sham‐operated rats. Estrogen‐induced rise in intestinal calcium absorption was completely blocked to basal level by the pure estrogen receptor (ER) antagonist ICI 182780. In contrast, ICI 182780 did not antagonize calcitriol‐enhanced intestinal calcium absorption. Our findings suggest that estrogen stimulates intestinal calcium absorption via an ER.