Androgens contribute to the stimulation of cancellous bone
formation by ovarian hormones in female rats.
Ac, Gallagher, Chambers Tj, and Tobias Jh.
Department of Histopathology, St George's Hospital Medical School,
London SW17 0RE
APStracts 2:0221E, 1995.
We investigated whether androgens, for which the ovaries are the major
source in female rats, contribute to the stimulation of cancellous
bone formation by ovarian hormones in female rats. Ovariectomised
animals were administered 5[alpha]-dihydrotestosterone (DHT; 10 and
100[mu]g/kg) by daily sc injection for 13 days, after which
histomorphometric analysis was performed at the proximal tibial
metaphysis. To prevent ovariectomy from stimulating bone turnover,
and hence complicating the interpretation of changes in bone
formation, animals were also given the resorption-inhibitor 3-amino
-1-hydroxypropylidene-1-bisphosphonate (AHPrBP). We found that
ovariectomy markedly suppressed cancellous bone formation, which was
partially prevented by DHT 100[mu]g/kg. To further address whether
androgens contribute to the stimulation of bone formation by ovarian
hormones, we treated intact and ovariectomised female rats with the
androgen antagonist flutamide (15mg/kg/day) for 28 days. While
flutamide had no effect in ovariectomised rats, this significantly
reduced cancellous bone formation in intact animals. We conclude
that, in the female rat, androgens contribute under physiological
conditions to the stimulation of cancellous bone formation by ovarian
hormones.
Received 2 May 1995; accepted in final form 26 October 1995.
APS Manuscript Number E201-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95