scholarly journals Palm Tocotrienol Supplementation Enhanced Bone Formation in Oestrogen-Deficient Rats

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Ima Nirwana Soelaiman ◽  
Wang Ming ◽  
Roshayati Abu Bakar ◽  
Nursyahrina Atiqah Hashnan ◽  
Hanif Mohd Ali ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Formation ◽  
Type I Collagen ◽  
Formation Rate ◽  
Serum Levels ◽  
Female Rats ◽  
Mineral Apposition Rate ◽  
Type I ◽  
Bone Biomarkers ◽  
Bone Formation Rate

Postmenopausal osteoporosis is the commonest cause of osteoporosis. It is associated with increased free radical activity induced by the oestrogen-deficient state. Therefore, supplementation with palm-oil-derived tocotrienols, a potent antioxidant, should be able to prevent this bone loss. Our earlier studies have shown that tocotrienol was able to prevent and even reverse osteoporosis due to various factors, including oestrogen deficiency. In this study we compared the effects of supplementation with palm tocotrienol mixture or calcium on bone biomarkers and bone formation rate in ovariectomised (oestrogen-deficient) female rats. Our results showed that palm tocotrienols significantly increased bone formation in oestrogen-deficient rats, seen by increased double-labeled surface (dLS/Bs), reduced single-labeled surface (sLS/BS), increased mineralizing surface (MS/BS), increased mineral apposition rate (MAR), and an overall increase in bone formation rate (BFR/BS). These effects were not seen in the group supplemented with calcium. However, no significant changes were seen in the serum levels of the bone biomarkers, osteocalcin, and cross-linked C-telopeptide of type I collagen, CTX. In conclusion, palm tocotrienol is more effective than calcium in preventing oestrogen-deficient bone loss. Further studies are needed to determine the potential of tocotrienol as an antiosteoporotic agent.

The anabolic effect of 17β-oestradiol on the trabecular bone of adult rats is suppressed by indomethacin

1992 ◽  
Vol 133 (2) ◽  
pp. 189-195 ◽  
Author(s):  
J. W. M. Chow ◽  
J. M. Lean ◽  
T. Abe ◽  
T. J. Chambers
Keyword(s):  
Bone Formation ◽  
Trabecular Bone ◽  
Bone Growth ◽  
Formation Rate ◽  
Bone Volume ◽  
Female Rats ◽  
Mineral Apposition Rate ◽  
Adult Rats ◽  
Bone Formation Rate

ABSTRACT We have previously demonstrated that administration of oestrogen, at doses sufficient to raise serum concentrations to those seen in late pregnancy, increases trabecular bone formation in the metaphysis of adult rats. To determine whether prostaglandins (PGs), which have been shown to induce osteogenesis in vivo, play a role in the induction of bone formation by oestrogen, 13-week-old female rats were given daily doses of 4 mg 17β-oestradiol (OE2)/kg for 17 days, alone or with indomethacin (1 mg/kg). The rats were also given double fluorochrome labels and at the end of the experiment tibias were subjected to histomorphometric assessment. Treatment with OE2 suppressed longitudinal bone growth and increased uterine wet weight, as expected, and neither response was affected by indomethacin. Oestrogen also induced a threefold increase in trabecular bone formation in the proximal tibial metaphysis, which resulted in a substantial increase in trabecular bone volume. As previously observed, the increase in bone formation was predominantly due to an increase in osteoblast recruitment (as judged by an increase in the percentage of bone surface showing double fluorochrome labels), with only a minor increase in the activity of mature osteoblasts (as judged by the mineral apposition rate). Indomethacin abolished the increase in osteoblastic recruitment, but the activity of mature osteoblastic cells remained high. The bone formation rate and bone volume remained similar to controls. The results suggest that PG production may be necessary for the increased osteoblastic recruitment induced by oestrogen, but not to mediate the effects of oestrogen on the activity of mature osteoblasts. Journal of Endocrinology (1992) 133, 189–195

scholarly journals Leptin Modulates both Resorption and Formation while Preventing Disuse-Induced Bone Loss in Tail-Suspended Female Rats

Endocrinology ◽  
2005 ◽  
Vol 146 (8) ◽  
pp. 3652-3659 ◽  
Author(s):  
Aline Martin ◽  
Raphaël de Vittoris ◽  
Valentin David ◽  
Ricardo Moraes ◽  
Martine Bégeot ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Formation ◽  
Formation Rate ◽  
Female Rats ◽  
Tail Suspension ◽  
Delayed Effect ◽  
Mineral Density ◽  
Bone Formation Rate ◽  
Positive Effects

Abstract In vitro studies have demonstrated leptin-positive effects on the osteoblast lineage and negative effects on osteoclastogenesis. Therefore, we tested the hypothesis that leptin may prevent tail-suspension-induced bone loss characterized by an uncoupling pattern of bone remodeling, through both mechanisms. Female rats were randomly tail-suspended or not and treated either with ip administration of leptin or vehicle for 3, 7, and 14 d. As measured by dual energy x-ray absorptiometry, tail-suspension induced a progressive decrease in tibia-metaphysis bone mineral density, which was prevented by leptin. Histomorphometry showed that this was related to the prevention of the transient increase in osteoclast number observed with suspension at d 7. These effects could be mediated by the receptor activator of nuclear factor κB-ligand (RANKL)/osteoprotegerin (OPG) pathway since we observed using direct RT-PCR, a suspension-induced increase in RANKL gene expression in proximal tibia at d 3, which was counterbalanced by leptin administration with a similar 3-fold increase in OPG expression and a RANKL to OPG ratio close to nonsuspended conditions. In addition, leptin prevented the decrease in bone formation rate induced by tail-suspension at d 14. The latter could be related to the role of leptin in mediating the reciprocal differentiation between adipocytes and osteoblasts, because leptin concurrently blunted the disuse-induced increase in bone marrow adipogenesis. In summary, these data suggest that peripheral administration of leptin could prevent disuse-induced bone loss through, first, a major inhibitory effect on bone resorption and, second, a delayed effect preventing the decrease in bone formation.

Erythropoietin Stimulates Bone Resorption Via Direct Activation of the Monocytic Lineage and Via Increased RANKL Production By B Cells and Osteoblasts

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 247-247
Author(s):  
Sahar Hiram-Bab ◽  
Naamit Deshet ◽  
Tamar Liron ◽  
Moshe Mittelman ◽  
Max Gassmann ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
Bone Loss ◽  
Bone Formation ◽  
Formation Rate ◽  
Serum Levels ◽  
Bone Formation Rate ◽  
Negative Effect ◽  
Monocytic Lineage

Abstract The negative effect of hypoxia on bone metabolism is well established but its mechanism of action is not fully understood. Hypoxia triggers the production of erythropoietin (EPO), a hormone most recognized for its hematopoietic function. An increasing number of roles unrelated to red blood cell production have been attributed to EPO, many of which are mediated by non-erythroid cells. In light of the controversy on the effect of increased serum levels of EPO on the skeleton, we investigated here the effect of the hormone on bone metabolism using EPO overexpressing (Tg6), and EPO-administered adult mice. In these models, the increase in EPO levels is similar to its physiologic increase at high altitude without the confounding direct effect of hypoxia on bone cells. Using microcomputed tomography, histology and serum markers we found that high EPO levels result in a severe trabecular bone loss (-32 to -61% decrease in bone density in Tg6 and EPO-injected animals, respectively; p<0.05 versus their respective controls throughout), due to increased bone resorption (+28 to +18% in TRAP5b serum levels) and reduced bone formation rate (-19 to -74%). This bone loss consisted of reduced trabecular number, but not thickness, with no effect on the cortical bone compartment. A similar bone response was observed with high and low doses of EPO, with no difference between intermittent and continuous administration modes. Using flow cytometry analysis and specific cell surface markers, we found that EPO (both overexpression and injection) targets the monocytic lineage by increasing the number of CD115+CD265- monocytes/macrophages by 43 and 57% (p<0.05), CD115+ CD265+ pre-osteoclasts by 2 and 4-fold (p=0.02) and mature osteoclasts (TRAP positive) by 64 and 88% (p<0.05, Figure 1A) in bones, compared to WT and diluent controls, respectively. EPO has direct stimulatory effects in vitro on both macrophages and preosteoclasts thus coupling immune and skeletal systems, Activation of purified BM-derived macrophages with EPO, led to a 33% increase (p=0.01) in phagocytosis of 5T33 multiple myeloma cells. EPO strongly stimulated osteoclastogenesis (TRAP staining, Figure 1B) and pit resorption (measured in calcium-phosphate-coated wells) in a cell-autonomous manner. Furthermore, our data indicate that EPO receptor (EPO-R) signaling in osteoclast precursors involves the Jak2 and PI3K pathways, but is independent of the MAPK/MEK pathway. In addition to the direct effect of EPO on monocyte derived cells, high EPO also led to a 1.6 fold (p=0.03) increase in the transcript levels of the osteoclastogenic cytokine RANKL in total bone marrow. Notably, the major sources of RANKL are B cells and osteoblasts, and our data indicate that both cell types express EPO-R, suggesting that they are direct targets of EPO. Accordingly we found an EPO-related increase in membrane bound RANKL on B cells (1.8-fold, p=0.0003) and osteoblasts (1.16-fold, p=0.001) isolated from bone marrow (Figure 1C). To test whether EPO-R on osteoblasts also mediates the attenuation of bone formation, we treated isolated osteoblasts with EPO. However, EPO treatment in vitro did not inhibit osteoblast differentiation and activity, as demonstrated by RT-qPCR of marker genes and mineralization assays. Taken together, these findings demonstrate that EPO strongly regulates bone mass by stimulating osteoclastogenesis and attenuating bone formation. The osteoclastogenic action of EPO is mediated both directly by EPO-R on the monocytic lineage and indirectly via EPO-R signaling on B cells and osteoblasts. Regarding bone formation, the negative effect of EPO on bone formation rate in vivo was not reproduced in isolated cells, thus implying the involvement of cells beyond the osteoblastic lineage. We also propose a new mechanism for hypoxia-induced bone loss that involves EPO action on monocytic, B cell and osteoblastic lineages. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals Combined virgin coconut oil and tocotrienol-rich fraction protects against bone loss in osteoporotic rat model

2019 ◽  
Vol 12 (12) ◽  
pp. 2052-2060 ◽  
Author(s):  
Mohd Maaruf Abdul Malik ◽  
Faizah Othman ◽  
Farida Hussan ◽  
Ahmad Nazrun Shuid ◽  
Qodriyah Mohd Saad
Keyword(s):  
Bone Loss ◽  
High Fat Diet ◽  
Type I Collagen ◽  
Coconut Oil ◽  
Mineral Apposition Rate ◽  
Type I ◽  
High Fat ◽  
Virgin Coconut Oil ◽  
Bone Formation Rate ◽  
Tocotrienol Rich Fraction

Background and Aim: Both virgin coconut oil (VCO) and tocotrienol-rich fraction (TRF) are rich in antioxidants and may protect the bone against bone loss induced by ovariectomy and high-fat diet. The study aimed to determine the protective effects of combined therapy of VCO and TRF on osteoporosis in ovariectomized (OVX) rat fed with high-fat diet. Materials and Methods: Thirty-six female Sprague-Dawley rats were divided into six groups: Sham-operated (SHAM), OVX control, OVX and given Premarin at 64.5 μg/kg (OVX+E2), OVX and given VCO at 4.29 ml/kg (OVX+V), OVX and given TRF at 30 mg/kg (OVX+T), and OVX and given a combination of VCO at 4.29 ml/kg and TRF at 30 mg/kg (OVX+VT). Following 24 weeks of treatments, blood and femora samples were taken for analyses. Results: There were no significant differences in serum osteocalcin levels between the groups (p>0.05), while serum C-terminal telopeptide of Type I collagen levels of the OVX+VT group were significantly lower than the other groups (p<0.05). The dynamic bone histomorphometry analysis of the femur showed that the double-labeled surface/bone surface (dLS/BS), mineral apposition rate, and bone formation rate/BS of the OVX+E2, OVX+T, and OVX+VT groups were significantly higher than the rest of the groups (p<0.05). Conclusion: A combination of VCO and TRF has the potential as a therapeutic agent to restore bone loss induced by ovariectomy and high-fat diet.

scholarly journals Increased Sclerostin Serum Levels Associated with Bone Formation and Resorption Markers in Patients with Immobilization-Induced Bone Loss

2010 ◽  
Vol 95 (5) ◽  
pp. 2248-2253 ◽  
Author(s):  
Agostino Gaudio ◽  
Pietra Pennisi ◽  
Cornelia Bratengeier ◽  
Venerando Torrisi ◽  
Brigitte Lindner ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Formation ◽  
Postmenopausal Women ◽  
Quantitative Ultrasound ◽  
Type I Collagen ◽  
Mechanical Strain ◽  
Serum Levels ◽  
Type I ◽  
Ultrasound Measurements ◽  
Dickkopf 1

Abstract Context: Sclerostin, a Wnt signaling antagonist on the osteoblasts produced by osteocytes, is regulated by mechanical strain and is implicated in the pathogenesis of disuse bone loss. There are no data on sclerostin in humans. Objective: The aim of the study was to evaluate sclerostin in patients immobilized after stroke, compared with control subjects, and to analyze its relationship with markers of bone formation and resorption. Design: This was a cross-sectional study. Setting and patients: We studied 40 postmenopausal women immobilized after a single episode of stroke 6 months or longer after onset, and 40 postmenopausal women from the general community. Bone status was assessed by quantitative ultrasound measurements at the calcaneus. Bone alkaline phosphatase (b-AP), carboxy-terminal telopeptide of type I collagen (CrossLaps), and sclerostin were evaluated by ELISA. We also used ELISA to measure serum levels of Dickkopf-1, another soluble inhibitor of Wnt/β-catenin signaling, highly expressed by osteocytes. Results: Immobilized patients had higher sclerostin serum levels (median 0.975 ng/ml; 25th to 75th percentiles 0.662–1.490) than controls (median 0.300 ng/ml; 25th to 75th percentiles 0.165–0.400: P &lt; 0.0001) and an increased bone turnover with a more significant rise in bone resorption (CrossLaps) than formation (b-AP) markers. Sclerostin correlated negatively with b-AP (r = −0.911; P &lt; 0.0001) and positively with CrossLaps (r = 0.391; P = 0.012). Dickkopf-1 did not significantly differ between the groups. Patients also had quantitative ultrasound measurements index lower than controls (P &lt; 0.001). Conclusions: This study shows for the first time that long-term immobilized patients present hypersclerostinemia associated with reduced bone formation, and suggests that sclerostin could be a link between mechanical unloading and disuse osteoporosis in humans.

Dietary Calcium Supplementation Suppresses Bone Formation in Magnesium-Deficient Rats

2006 ◽  
Vol 76 (3) ◽  
pp. 111-116 ◽  
Author(s):  
Hiroshi Matsuzaki ◽  
Misao Miwa
Keyword(s):  
Bone Formation ◽  
Calcium Supplementation ◽  
Control Diet ◽  
Formation Rate ◽  
Dietary Calcium ◽  
Mineral Apposition Rate ◽  
Control Group ◽  
Deficient Diet ◽  
Bone Formation Rate ◽  
Male Wistar Rats

The purpose of this study was to clarify the effects of dietary calcium (Ca) supplementation on bone metabolism of magnesium (Mg)-deficient rats. Male Wistar rats were randomized by weight into three groups, and fed a control diet (control group), a Mg-deficient diet (Mg- group) or a Mg-deficient diet having twice the control Ca concentrations (Mg-2Ca group) for 14 days. Trabecular bone volume was significantly lower in the Mg - and Mg-2Ca groups than in the control group. Trabecular number was also significantly lower in the Mg - and Mg-2Ca groups than in the control group. Mineralizing bone surface, mineral apposition rate (MAR), and surface referent bone formation rate (BFR/BS) were significantly lower in the Mg - and Mg-2Ca groups than in the control group. Furthermore, MAR and BFR/BS were significantly lower in the Mg-2Ca group than in the Mg - group. These results suggest that dietary Ca supplementation suppresses bone formation in Mg-deficient rats.

scholarly journals Serum levels of bone formation and resorption markers in relation to vitamin D status in professional gymnastics and physically active men during upper and lower body high-intensity exercise

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Jan Mieszkowski ◽  
Andrzej Kochanowicz ◽  
Elżbieta Piskorska ◽  
Bartłomiej Niespodziński ◽  
Joanna Siódmiak ◽  
...  
Keyword(s):  
Vitamin D ◽  
Bone Formation ◽  
Bone Turnover ◽  
Bone Turnover Markers ◽  
Type I Collagen ◽  
Serum Levels ◽  
Type I ◽  
Vitamin D Metabolites ◽  
Physically Active ◽  
Turnover Markers

Abstract Purpose/introduction To compare serum levels of bone turnover markers in athletes and non-athletes, and to evaluate the relationship between serum levels of vitamin D metabolites and exercise-induced changes in biomarker levels. Methods Sixteen elite male artistic gymnasts (EG; 21.4 ± 0.8 years-old) and 16 physically active men (the control group, PAM; 20.9 ± 1.2 years-old) performed lower and upper body 30-s Wingate anaerobic tests (LBWT and UBWT, respectively). For biomarker analysis, blood samples were collected before, and 5 and 30 min after exercise. Samples for vitamin D levels were collected before exercise. N-terminal propeptide of type I collagen (PINP) was analysed as a marker of bone formation. C-terminal telopeptide of type I collagen (CTX) was analysed as a marker of bone resorption. Results UBWT fitness readings were better in the EG group than in the PAM group, with no difference in LBWT readings between the groups. UBWT mean power was 8.8% higher in subjects with 25(OH)D3 levels over 22.50 ng/ml and in those with 24,25(OH)2D3 levels over 1.27 ng/ml. Serum CTX levels increased after both tests in the PAM group, with no change in the EG group. PINP levels did not change in either group; however, in PAM subjects with 25(OH)D3 levels above the median, they were higher than those in EG subjects. Conclusion Vitamin D metabolites affect the anaerobic performance and bone turnover markers at rest and after exercise. Further, adaptation to physical activity modulates the effect of anaerobic exercise on bone metabolism markers.

scholarly journals Reduced Serum Levels of Bone Formation Marker P1NP in Psoriasis

2021 ◽  
Vol 8 ◽  
Author(s):  
Julia Mentzel ◽  
Tabea Kynast ◽  
Johannes Kohlmann ◽  
Holger Kirsten ◽  
Matthias Blüher ◽  
...  
Keyword(s):  
Bone Formation ◽  
Bone Metabolism ◽  
Type I Collagen ◽  
Skin Inflammation ◽  
Serum Levels ◽  
Serum Markers ◽  
Chronic Inflammatory Disease ◽  
Type I ◽  
Patient Counseling ◽  
Type I Procollagen

Psoriasis is a chronic inflammatory disease of the skin and joints. More recent data emphasize an association with dysregulated glucose and fatty acid metabolism, obesity, elevated blood pressure and cardiac disease, summarized as metabolic syndrome. TNF-α and IL-17, central players in the pathogenesis of psoriasis, are known to impair bone formation. Therefore, the relation between psoriasis and bone metabolism parameters was investigated. Two serum markers of either bone formation—N-terminal propeptide of type I procollagen (P1NP) or bone resorption—C-terminal telopeptide of type I collagen (CTX-I)—were analyzed in a cohort of patients with psoriasis vulgaris. In patients with psoriasis, P1NP serum levels were reduced compared to gender-, age-, and body mass index-matched healthy controls. CTX-I levels were indistinguishable between patients with psoriasis and controls. Consistently, induction of psoriasis-like skin inflammation in mice decreases bone volume and activity of osteoblasts. Moreover, efficient anti-psoriatic treatment improved psoriasis severity, but did not reverse decreased P1NP level suggesting that independent of efficient skin treatment psoriasis did affect bone metabolism and might favor the development of osteoporosis. Taken together, evidence is provided that bone metabolism might be affected by psoriatic inflammation, which may have consequences for future patient counseling and disease monitoring.

Bone modeling in bromocriptine-treated pregnant and lactating rats: possible osteoregulatory role of prolactin in lactation

2010 ◽  
Vol 299 (3) ◽  
pp. E426-E436 ◽  
Author(s):  
Panan Suntornsaratoon ◽  
Kannikar Wongdee ◽  
Suchandra Goswami ◽  
Nateetip Krishnamra ◽  
Narattaphol Charoenphandhu
Keyword(s):  
Bone Loss ◽  
Bone Formation ◽  
Trabecular Bone ◽  
Formation Rate ◽  
Bone Modeling ◽  
Mineral Density ◽  
Pregnant Rats ◽  
Bone Formation Rate ◽  
Bone Trabeculae ◽  
Bone Gain

The lactogenic hormone prolactin (PRL) directly regulates osteoblast functions in vitro and modulates bone remodeling in nulliparous rats, but its osteoregulatory roles in pregnant and lactating rats with physiological hyperprolactinemia remained unclear. Herein, bone changes were investigated in rats treated with bromocriptine (Bromo), an inhibitor of pituitary PRL release, or Bromo+PRL at different reproductive phases, from mid-pregnancy to late lactation. PRL receptors were strongly expressed in osteoblasts lining bone trabeculae, indicating bone as a target of PRL actions. By using dual energy X-ray absorptiometry, we found a significant increase in bone mineral density in the femora and vertebrae of pregnant rats. Such pregnancy-induced bone gain was, however, PRL independent and may have resulted from the increased cortical thickness. Bone trabeculae were modestly changed during pregnancy as evaluated by bone histomorphometry. On the other hand, lactating rats, especially in late lactation, showed massive bone loss in bone trabeculae but not in cortical shells. Further study in Bromo- and Bromo+PRL-treated rats suggested that PRL contributed to decreases in trabecular bone volume and number and increases in trabecular separation and eroded surface, as well as a paradoxical increase in bone formation rate in late lactation. Uncoupling of trabecular bone formation and resorption was evident in lactating rats, with the latter being predominant. In conclusion, pregnancy mainly induced cortical bone gain, whereas lactation led to trabecular bone loss in both long bones and vertebrae. Although PRL was not responsible for the pregnancy-induced bone gain, it was an important regulator of bone modeling during lactation.

scholarly journals New Bone Formation with Teriparatide [Human Parathyroid Hormone-(1–34)] Is Not Retarded by Long-Term Pretreatment with Alendronate, Estrogen, or Raloxifene in Ovariectomized Rats

Endocrinology ◽  
2003 ◽  
Vol 144 (5) ◽  
pp. 2008-2015 ◽  
Author(s):  
Yanfei L. Ma ◽  
Henry U. Bryant ◽  
Qingqiang Zeng ◽  
Allen Schmidt ◽  
Jennifer Hoover ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Formation ◽  
Formation Rate ◽  
Prior Exposure ◽  
Ovariectomized Rats ◽  
Mineral Density ◽  
Bone Formation Rate ◽  
Teriparatide Treatment ◽  
Antiresorptive Agents ◽  
Ovx Rats

With the ready availability of several osteoporosis therapies, teriparatide [human PTH-(1–34)] is likely to be prescribed to postmenopausal women with prior exposure to agents that prevent bone loss, such as bisphosphonates, estrogen, or selective estrogen receptor modulators. Therefore, we evaluated the ability of once daily teriparatide to induce bone formation in ovariectomized (Ovx) rats with extended prior exposure to various antiresorptive agents, such as alendronate (ABP), 17α-ethinyl estradiol (EE), or raloxifene (Ral). Sprague Dawley rats were Ovx and treated with ABP (28 μg/kg, twice weekly), EE (0.1 mg/kg·d), or Ral (1 mg/kg·d) for 10 months before switching to teriparatide 30 μg/kg·d for another 2 months. Analysis of the proximal tibial metaphysis showed that all three antiresorptive agents prevented ovariectomy-induced bone loss after 10 months, but were mechanistically distinct, as shown by histomorphometry. Before teriparatide treatment, ABP strongly suppressed activation frequency and bone formation rate to below levels in other treatment groups, whereas these parameters were not different from sham values for EE or Ral. Trabecular area for ABP, EE, and Ral were greater than that in Ovx controls. However, the trabecular bone effects of ABP were attributed not only to effects on the secondary spongiosa, but also to the preservation of primary spongiosa, which was prevented from remodeling. After 2 months of teriparatide treatment, lumbar vertebra showed relative bone mineral density increases of 18%, 7%, 11%, and 10% for vehicle/teriparatide, ABP/teriparatide, EE/teriparatide, and Ral/teriparatide, respectively, compared with 10 month levels. Histomorphometry showed that trabecular area was increased by 105%, 113%, 36%, and 48% for vehicle/teriparatide, ABP/teriparatide, EE/teriparatide, and Ral/teriparatide, respectively, compared with 10 month levels. Teriparatide enhanced mineralizing surface, mineral apposition rate, and bone formation rate in all groups. Compression testing of vertebra showed that teriparatide improved strength (peak load) and toughness in all groups to a proportionately similar extent compared with 10 month levels. These data showed a surprising ability of the rat skeleton to respond to teriparatide despite extensive pretreatment with ABP, EE, or Ral. Therefore, the mature skeleton of Ovx rats remains highly responsive to the appositional effects of teriparatide regardless of pretreatment status in terms of cancellous bone area or rate of bone turnover.

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