Journal ArticleDOI
The effect of different hormone replacement therapy regimens on the mechanical properties of rat vertebrae.
Debbie Chachra,Debbie Chachra,M. Kasra,M. Kasra,Carla M. Vanin,Neil J. MacLusky,Robert F. Casper,Marc D. Grynpas,Marc D. Grynpas +8 more
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It is found that all three estrogen/progestin regimens maintain bone density and all mechanical properties at a level indistinguishable from the control, however, the cyclic and continuous NET treatment results were, with the exception of density, also indistinguishable from those of the ovariectomized group.Abstract:
The purpose of this study was to examine the effects of estrogen replacement, in concert with three different progestin regimens, on the mechanical properties of rat lumbar vertebrae. Ninety-two Sprague-Dawley rats (11 months old) were divided into six groups for treatment. The first group was an intact control, the second group (OVX) was ovariectomized only, and the third group (estrogen-only) was ovariectomized and received continuous estrogen through a 17 beta-estradiol implant. The remaining groups were ovariectomized and received estrogen and progestin (norethindrone, NET) therapy; 3 micrograms of NET was injected daily (estrogen plus continuous NET), or 6 micrograms of NET was injected for 14 consecutive days of a 28-day cycle (estrogen plus cyclic NET), or for 3 consecutive days of a 6-day cycle (estrogen plus interrupted NET). The animals were sacrificed after 6 months, and the vertebrae were dissected out. The vertebral processes of the fourth lumbar vertebrae were removed, and the density of the vertebral bodies was determined. They were then subjected to compression testing. We found that all three estrogen/progestin regimens maintain bone density and all mechanical properties at a level indistinguishable from the control. However, the cyclic and continuous NET treatment results were, with the exception of density, also indistinguishable from those of the ovariectomized group. The estrogen plus interrupted NET group on the other hand, has a significantly greater compressive modulus and density than the ovariectomized group. In conclusion, with respect to the ovariectomized group, the estrogen plus interrupted NET treatment resulted in a superior density and compressive modulus.(ABSTRACT TRUNCATED AT 250 WORDS)read more
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Evidence of estrogen receptors in normal human osteoblast-like cells
Erik Fink Eriksen,Douglas S. Colvard,Nicholas J. Berg,Mark L. Graham,Kenneth G. Mann,Thomas C. Spelsberg,B. Lawrence Rlggs +6 more
TL;DR: The data suggest that estrogen acts directly on human bone cells through a classical estrogen receptor-mediated mechanism, indicating an induction of functional progesterone receptors.
Journal ArticleDOI
Standardized bending and breaking test for the normal and osteoporotic metaphyseal tibias of the rat: effect of estradiol, testosterone, and raloxifene.
E.K. Stürmer,Dana Seidlova-Wuttke,Stephan Sehmisch,T. Rack,Joern Wille,K.-H. Frosch,Wolfgang Wuttke,Klaus Michael Stürmer +7 more
TL;DR: A highly sensitive three‐point bending test for the metaphyseal tibias in rats to evaluate stiffness and strength was developed and validated in a right‐left comparison and a bioassay with soy‐free food, estradiol, raloxifene, and testosterone in orchidectomized rats.
Journal ArticleDOI
Effects of the steroidal aromatase inhibitor exemestane and the nonsteroidal aromatase inhibitor letrozole on bone and lipid metabolism in ovariectomized rats.
TL;DR: EXE and 17-H-EXE significantly prevent bone loss, enhance bone mechanical strength, and lower serum cholesterol and low-density lipoprotein levels in OVX rats, and these protective effects on end-organ function are not seen with the nonsteroidal inhibitor LET.
Journal ArticleDOI
The steroidal aromatase inhibitor exemestane prevents bone loss in ovariectomized rats.
Paul E. Goss,S Qi,Robert G. Josse,Kenneth P.H. Pritzker,Kenneth P.H. Pritzker,M Mendes,H Hu,Stephen D. Waldman,Marc D. Grynpas,Marc D. Grynpas +9 more
TL;DR: The positive results of EXE on bone and lipid metabolism in the OVX rat model merit further investigation of the effects of exemestane in postmenopausal women.
Journal ArticleDOI
Early Estrogen Replacement Therapy Reverses the Rapid Loss of Trabecular Bone Volume and Prevents Further Deterioration of Connectivity in the Rat
TL;DR: It is demonstrated that ERT can restore the lost trabecular bone, but not trabECular connectivity, that occurs soon after OVX by allowing bone formation to continue in previously activated bone remodeling units while suppressing the production of new remodelingunits.
References
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Journal ArticleDOI
The effects of ovarian steroids on food and water intake and body weight in the female rat.
M. F. Tarttelin,R. A. Gorski +1 more
TL;DR: Oestrogen, but not progesterone, is the ovarian hormone active in the regulation of intake parameters and body weight in the female rat, and OB treatment was found to decrease the increased FI seen during pseudopregnancy by a proportion similar to the effect of oestrogen in the long-term ovariectomized animal.
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The anabolic effects of human parathyroid hormone (hPTH) on rat vertebral body mass are also reflected in the quality of bone, assessed by biomechanical testing: a comparison study between hPTH-(1-34) and hPTH-(1-84).
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Journal ArticleDOI
Uncoupling of bone formation and resorption by combined oestrogen and progestagen therapy in postmenopausal osteoporosis.
C. Christiansen,C. Christiansen,C. Christiansen,L. Nilas,L. Nilas,L. Nilas,Bente Juel Riis,Bente Juel Riis,Bente Juel Riis,P. Rødbro,P. Rødbro,P. Rødbro,Leonard J. Deftos,Leonard J. Deftos,Leonard J. Deftos +14 more
TL;DR: Serum alkaline phosphatase and bone Gla protein increased during progestagen administration, whereas urinary excretion of calcium and hydroxyproline fell significantly during treatment, independently of progestogen intake, leading to a positive calcium balance.
Journal ArticleDOI
Steroid receptor levels in intact and ovariectomized estrogen-treated rats: an examination of quantitative, temporal and endocrine factors influencing the efficacy of an estradiol stimulus.
TL;DR: The results indicate that the effectiveness of anEstradiol stimulus to elicit lordosis or luteinizing hormone release depends on at least three factors: the magnitude of the increment in serum estradiol and brain and pituitary cell nuclear Estradiol receptor levels; the duration over which these increments area maintained; and the interval from previous exposure to estrogen.
Journal ArticleDOI
Glucocorticoid receptors and inhibition of bone cell growth in primary culture.
TL;DR: Primary culture of fetal rat calvaria cells provides evidence for receptor mediated inhibitory effects of glucocorticoids directly at the level of the bone cell, and dexamethasone inhibits the growth of these cells.