[One year observation on effects of estrogen, tamoxifen combined with or without fluoride on preventing bone loss in ovariectomized rats].
OBJECTIVE
To compare the effects of one year treatment of estrogen and tamoxifen, either alone or combined with fluoride on bone metabolism in ovariectomized rats.


METHODS
One hundred and forty two virgin female Sprague-Dawley rats were ovariectomized (OVX) or sham operated at 6 months of age, and randomly divided into 7 groups (19 - 21 rats each): (1) sham-operated controls; (2) OVX vehicle controls; (3) estrogen group; (4) fluoride group; (5) tamoxifen group; (6) fluoride plus estrogen; (7) fluoride plus tamoxifen. The treatments lasted for one year. Bone mineral density (BMD) measurement, bone histomorphometry analysis (lumbar vertebrae) and biomechanical test (3-point-bending test on right femur) were performed before and after treatment. The histological change of uterus were also determined at the same time.


RESULTS
(1) Twelve months of ovariectomy, the OVX group had significantly lower total body (279 mg/cm(2)), lumbar vertebra (232 mg/cm(2)) than all other groups (total body 286 - 298 mg/cm(2), lumber 251 - 266 mg/cm(2), P < 0.05). Estrogen group (216 mg/cm(2)) had higher BMD than tamoxifene group (195 mg/cm(2)) in midshaft of femur. (2) After 4 months of ovariectomy, only the two combination groups kept the maximum load (145 N) of right femur over the level of OVX group (118 N); after 12 months of treatment, the maximum load of OVX group [(108 +/- 13) N] was significantly different from all other groups (132 - 155 N); both maximum load and elastic load of estrogen group were significantly higher than that of tamoxifen group. (3) No evidence of dysmineralization was found by bone histomorphometry.


CONCLUSIONS
Estrogen has more potent effects on keeping bone mass and bone strength as compared with tamoxifene. The combined therapy (estrogen + fluoride or tamoxifen + fluoride) resulted in better bone strength than the single ones.
Liu
Hui
H
Department of Obstetrics and Gynecology, General Hospital of People's Liberation Army, Beijing 100853, China.
Peng
Hongmei
H
Liu
Jianli
J
D000818:Animals; D018488:Bone Demineralization, Pathologic / Q000517:prevention & control*; D015519:Bone Density / Q000187:drug effects; D004359:Drug Therapy, Combination; D004965:Estrogen Antagonists / Q000627:therapeutic use; D004967:Estrogens / Q000627:therapeutic use*; D005260:Female; D005459:Fluorides / Q000627:therapeutic use*; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D013629:Tamoxifen / Q000627:therapeutic use*; D013997:Time Factors; D016896:Treatment Outcome
D004965:Estrogen Antagonists; D004967:Estrogens; D013629:Tamoxifen; D005459:Fluorides