title: Androgens contribute to the stimulation of cancellous bone formation by ovarian hormones in female rats.
abstract: 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.
authors.affiliation: Department of Histopathology, St. George's Hospital Medical School, London, United Kingdom.
authors.forename: A C
authors.initials: AC
authors.lastname: Gallagher
authors.forename: T J
authors.initials: TJ
authors.lastname: Chambers
authors.forename: J H
authors.initials: JH
authors.lastname: Tobias
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001862:Bone Resorption / Q000517:prevention & control; D001842:Bone and Bones / Q000187:drug effects / Q000502:physiology*; D013196:Dihydrotestosterone / Q000494:pharmacology*; D004164:Diphosphonates / Q000494:pharmacology; D005260:Female; D005485:Flutamide / Q000494:pharmacology*; D009929:Organ Size / Q000187:drug effects; D010010:Osteoclasts / Q000187:drug effects / Q000502:physiology*; D010052:Ovariectomy; D000077268:Pamidronate; D051381:Rats; D017208:Rats, Wistar; D013977:Tibia; D014599:Uterus / Q000187:drug effects / Q000502:physiology
chemical_list: D004164:Diphosphonates; D013196:Dihydrotestosterone; D005485:Flutamide; D000077268:Pamidronate