Unusual Histomorphometric Changes in the Iliac Crest in Ovariectomized and Sham-operated Ewes

1995 ◽  
Vol 08 (04) ◽  
pp. 184-190
Author(s):  
A. R. Villanueva ◽  
M. R. Alvis ◽  
H. M. Aberman ◽  
A. S. Turner
Keyword(s):  
Bone Loss ◽  
Bone Formation ◽  
Cancellous Bone ◽  
Formation Rate ◽  
Large Animal Model ◽  
Seasonal Effect ◽  
Sham Operation ◽  
Large Animal ◽  
Bone Formation Rate ◽  
Oestrogen Deficiency

SummaryA large animal model to study cancellous bone loss and the effect of various therapeutic agents following oestrogen deficiency-related bone loss is needed. Following double fluorochrome labeling at the time of surgery, six and 12 months later, static and dynamic histomorphometry was performed on undecalcified sections of the iliac crests of 16 mature (4 to 5-yearold) ewes following ovariectomy (OVX; n = 8) or sham-operation (Sham; n = 8). We found a slight decrease in bone mass associated with oestrogen deficiency as indicated by a statistically significant increase in trabecular separation (Tb.Sp: +14%, p <0.05) and decrease in wall thickness (W.Th: -10%, p <0.05) in the OVX group. However, at six months, we saw evidence of complete cessation of bone formation in both OVX and Sham animals. At that time there was a statistically significant (p <0.05) decline in the following parameters in both the Sham and OVX animals respectively: osteoid surface (OS: -79%, -77%), osteoid thickness (O.Th: -40%, -30%), flat osteoblasts (Fl.Ob.S: -87%, -94%), cuboidal osteoblasts (Cu.Ob.S: -88%, -65%), osteoid surface as a percentage of the total cancellous bone perimeter (OS/BS: -82%, -80%), osteoblast surface as a percentage of total cancellous bone surface (Ob.S/BS: -94%, -77%), mineralizing surface as a percentage of double labels plus half single labels (MS/OS: -44%, -42%), osteoid volume as a percentage of total area of mineralized bone plus osteoid (OV/TV: -88%, -88%), osteoid as a percentage of mineralized bone (OV/BV: -87%, -86%), osteoid maturation time (Omt: -27%, -35%), bone formation rate, surface referent (BFR/BS: -90%, -87%), bone formation rate, volume referent (BFR/BV: -89%, -86%), and bone formation rate, tissue referent (BFR/TV: -91%, -88%). The data was compared to static and dynamic histomorphometry of three intact ewes (similar age, breed, source) whose biopsies were taken two months after the second biopsies in the present study. The data indicate that there is a slight loss of trabecular bone following OVX but we are unable to explain the dramatic depression of bone turnover with little change in bone resorption. The data resembles the response seen when sheep are given daily doses of methylprednisolone. We speculate that this phenomenon may be a response to endogenous corticosteroid release in a response to stresses of transport, and surgery. A seasonal effect may be another explanation fro these changes, whereas dietary alteration (e. g. poisonous plants), hormonal changes or response to changes in physical activity are unlikely causes.A large animal model to study cancellous bone loss and effect of various therapeutic agents following oestrogen deficiency – related bone loss is needed. Following double fluorochrome labeling at the time of surgery, six and 12 months later, static and dynamic histomorphome-try was performed on undecal-cified sections of the iliac crests of 16 mature (4 to 5-year-old) ewes following ovariectomy (OVX; n = 8) or sham-operation (Sham; n = 8). A slight decrease in bone mass associated with oestrogen deficiency was seen but there was also evidence of complete cessation of bone formation in both OVX and Sham animals. The data resembles the responses seen when sheep are given daily doses of methylpednisolone and may be a response to endogenous corticosteroid release. A seasonal effect may be another explanation for these changes, whereas dietary alteration (e. g. poisonous plants), hormonal changes or response to changes in physical activity are unlikely causes.

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.

scholarly journals DSS-induced colitis produces inflammation-induced bone loss while irisin treatment mitigates the inflammatory state in both gut and bone

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Corinne E. Metzger ◽  
S. Anand Narayanan ◽  
Jon P. Elizondo ◽  
Anne Michal Carter ◽  
David C. Zawieja ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Formation ◽  
Therapeutic Potential ◽  
Negative Impact ◽  
Formation Rate ◽  
Inflammatory Factors ◽  
Sprague Dawley ◽  
Mineral Density ◽  
Bone Formation Rate ◽  
Gut Inflammation

Abstract Chronic pediatric inflammatory bowel disease (IBD) leads to lack of bone accrual, bone loss, and increased fractures. Presently there is no cure, and many IBD treatments incur negative side effects. We previously discovered treatment with exogenous irisin resolved inflammatory changes in the colon, gut lymphatics, and bone in a mild IBD rodent model. Here we assess irisin treatment in severe IBD induced via dextran sodium sulfate (DSS). Male Sprague Dawley rats (2-mo-old) were untreated (Con) or given 2% DSS in drinking water. In week two, half of each group (Con + Ir and DSS + Ir) received injections of recombinant irisin (i.p., 2x/wk). After 4 weeks, gut inflammation was associated with declines in bone mineral density and cancellous bone volume. Furthermore, elevated osteocyte TNF-α, interleukin-6, RANKL, OPG, and sclerostin corresponded with higher osteoclast surfaces and lower bone formation rate in DSS animals as well as lower ultimate load. While irisin treatment improved colon inflammation, there were no improvements in bone density or bone mechanical properties; however, irisin elevated bone formation rate, decreased osteoclast surfaces, and reduced osteocyte pro-inflammatory factors. These data highlight the negative impact of chronic gut inflammation on bone as well as the therapeutic potential of irisin as an anti-inflammatory treatment.

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 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.

Lack of effect of spaceflight on bone mass and bone formation in group-housed rats

1998 ◽  
Vol 85 (1) ◽  
pp. 279-285 ◽  
Author(s):  
T. J. Wronski ◽  
M. Li ◽  
Y. Shen ◽  
S. C. Miller ◽  
B. M. Bowman ◽  
...  
Keyword(s):  
Bone Formation ◽  
Bone Mass ◽  
Cancellous Bone ◽  
Space Shuttle ◽  
Formation Rate ◽  
Lumbar Vertebrae ◽  
Sprague Dawley ◽  
Bone Formation Rate ◽  
Bone Changes ◽  
Space Shuttle Columbia

As part of an experiment to study the role of corticosteroids in bone changes during spaceflight, male Sprague-Dawley rats (6 wk old, 165 g body weight) were placed in orbit for 17 days, in groups of six, in animal-enclosure modules (AEMs) aboard the space shuttle Columbia (STS-78). Control rats were group housed in a similar manner in ground-based AEMs or standard vivarium cages. Adrenal hypertrophy occurred in flight rats, but bone histomorphometric analyses revealed a lack of significant changes in bone mass and bone formation in these animals. Cancellous bone volume and osteoblast surface in the proximal tibial metaphysis were nearly the same in flight and ground-based rats. Normal levels of cancellous bone mass and bone formation were also detected in the lumbar vertebrae and femoral necks of flight rats. In the tibial diaphysis, periosteal bone formation rate was found to be identical in flight and ground-based rats. The results indicate that, under conditions of group housing in AEMs, spaceflight has minimal effects on bone mass and bone formation in rapidly growing rats. These findings emphasize the need to investigate the importance of rat age, strain, and especially housing conditions for studies of the skeletal effects of spaceflight.

Effects of disrupted β1-integrin function on the skeletal response to short-term hindlimb unloading in mice

2005 ◽  
Vol 98 (2) ◽  
pp. 690-696 ◽  
Author(s):  
U. T. Iwaniec ◽  
T. J. Wronski ◽  
D. Amblard ◽  
Y. Nishimura ◽  
M. C. H. van der Meulen ◽  
...  
Keyword(s):  
Bone Formation ◽  
Cancellous Bone ◽  
Formation Rate ◽  
Dominant Negative ◽  
Hindlimb Unloading ◽  
Femoral Diaphysis ◽  
Short Term ◽  
Bone Formation Rate ◽  
Mechanical Unloading ◽  
Lumbar Vertebral Body

The study was designed to determine whether β1-integrin plays a role in mediating the acute skeletal response to mechanical unloading. Transgenic (TG) mice were generated to express a dominant negative form of β1-integrin under the control of the osteocalcin promoter, which targets expression of the transgene to mature osteoblasts. At 63 days of age, wild-type (WT) and TG mice were subjected to hindlimb unloading by tail suspension for 1 wk. Pair-fed, normally loaded WT and TG mice served as age-matched controls. Bone samples from each mouse were processed for quantitative bone histomorphometry and biomechanical testing. The skeletal phenotype of TG mice was characterized by lower cancellous bone mass in the distal femoral metaphysis (−52%) and lumbar vertebral body (−20%), reduced curvature of the proximal tibia (−20%), and decreased bone strength (−20%) and stiffness (−23%) of the femoral diaphysis with relatively normal indexes of cancellous bone turnover. Hindlimb unloading for only 1 wk induced a 10% decline in tibial curvature and a 30% loss of cancellous bone in the distal femur due to a combination of increased bone resorption and decreased bone formation in both WT and TG mice. However, the strength and stiffness of the femoral diaphysis were unaffected by short-term hindlimb unloading in both genotypes. The observed increase in osteoclast surface was greater in unloaded TG mice (92%) than in unloaded WT mice (52%). Cancellous bone formation rate was decreased in unloaded WT (−29%) and TG (−15%) mice, but, in contrast to osteoclast surface, the genotype by loading interaction was not statistically significant. The results indicate that altered integrin function in mature osteoblasts may enhance the osteoclastic response to mechanical unloading but that it does not have a major effect on the development of cancellous osteopenia in mice during the early stages of hindlimb unloading.

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