AJP - Endocrinology and Metabolism, Vol 270, Issue 3 E407-E412, Copyright © 1996 by American Physiological Society
Androgens contribute to the stimulation of cancellous bone formation by ovarian hormones in female rats
A. C. Gallagher, T. J. Chambers and J. H. Tobias
Department of Histopathology, St. George's Hospital Medical School, London, United Kingdom.
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. Ovariectomized animals were
administered 5alpha-dihydrotestosterone (DHT; 10 and 100 microgram/kg) by
daily subcutaneous 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. We
found that ovariectomy markedly suppressed cancellous bone formation, which
was partially prevented by DHT (100 microgram/kg). To further address
whether androgens contribute to the stimulation of bone formation by
ovarian hormones, we treated intact and ovariectomized female rats with the
androgen antagonist flutamide (15 mg/kg/day) for 28 days. Whereas flutamide
had no effect in ovariectomized rats, it 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.
