Comparative study of the effects of osteoprotegerin and testosterone on bone quality in male orchidectomised rats.

Aim: The aim of this work is to compare the effects of osteoprotegerin (OPG) and testosterone on bone quality in a model of orchidectomised (ORX) rats.Methods: Three-month-old ORX or SHAM operated groups (n = 15 each group) were used. The SHAM and ORX groups received saline. There were two ORX groups, receiving OPG-Fc (10 mg/kg twice weekly) (ORX + OPG-Fc) or testosterone cypionate (1.7 mg/kg/weekly) for 8 weeks. After sacrifice, bone analysis by femoral and lumbar dual-energy X-ray absorptiometry and micro-computed tomography in femora were performed. Histological sections of vertebrae were dyed with hematoxylin-eosin or safranin. Serum osteocalcin (BGP), total alkaline phosphatase (ALP), and C-terminal telopeptide of type I collagen (CTX) were analyzed.Results: ORX resulted in femoral and vertebral bone loss and in microarchitectural deterioration. Treatment with OPG-Fc and testosterone recovered lumbar (L) and femoral (F) bone mineral densitometry bone mineral density (BMD) to SHAM levels. Femoral BMD was significantly higher after treatment with OPG-Fc than after testosterone treatment due to the presence of osteopetrotic changes in the metaphyseal region of long bones. Serum levels of ALP and CTX increased, while OPG levels were unchanged in ORX rats. Treatment with OPG-Fc decreased the levels of BGP, ALP, and CTX. Treatment with testosterone maintained biochemical markers of bone turnover at levels similar to or higher than those of ORX rats.

Differential Modulation of Cancellous and Cortical Distal Femur by Fructose and Natural Mineral-Rich Water Consumption in Ovariectomized Female Sprague Dawley Rats.

Bone mineral density (BMD) and microstructure depend on estrogens and diet. We assessed the impact of natural mineral-rich water ingestion on distal femur of fructose-fed estrogen-deficient female Sprague Dawley rats. Ovariectomized rats drank tap or mineral-rich waters, with or without 10%-fructose, for 10 weeks. A sham-operated group drinking tap water was included (n = 6/group). Cancellous and cortical bone compartments were analyzed by microcomputed tomography. Circulating bone metabolism markers were measured by enzyme immunoassay/enzyme-linked immunosorbent assay or multiplex bead assay. Ovariectomy significantly worsened cancellous but not cortical bone, significantly increased circulating degradation products from C-terminal telopeptides of type I collagen and receptor activator of nuclear factor-kappaB ligand (RANKL), and significantly decreased circulating osteoprotegerin and osteoprotegerin/RANKL ratio. In ovariectomized rats, in cancellous bone, significant water effect was observed for all microstructural properties, except for the degree of anisotropy, and BMD (neither a significant fructose effect nor a significant interaction between water and fructose ingestion effects were observed). In cortical bone, it was observed a significant (a) water effect for medullary volume and cortical endosteal perimeter; (b) fructose effect for cortical thickness, medullary volume, cross-sectional thickness and cortical endosteal and periosteal perimeters; and (c) interaction effect for mean eccentricity. In blood, significant fructose and interaction effects were found for osteoprotegerin (no significant water effect was seen). For the first time in ovariectomized rats, the positive modulation of cortical but not of cancellous bone by fructose ingestion and of both bone locations by natural mineral-rich water ingestion is described.

Comparison of various SYSADOA for the osteoarthritis treatment: an experimental study in rabbits.

BACKGROUND: Osteoarthritis is thought to be the most prevalent chronic and disabling joint disease in animals and humans and its treatment is a major orthopaedic challenge because there is no ideal drug treatment to preserve joint structure and function, as well as to ameliorate the symptomatology of the disease. The aim of the present study was to assess, using histology, histomorphometry and micro-CT, the effects of the treatment with several drugs of the SYSADOA group and a bisphosphonate in a model of early osteoarthritis, comparing all the results obtained. METHODS: Osteoarthritis was surgically induced by anterior cruciate ligament transection and partial meniscectomy on one knee of 56 rabbits; treatment was started three weeks after surgery and lasted 8 weeks; at the end of this period, the animals were sacrificed. Animals were divided into seven groups (8 animals each), one for each regimen of treatment (glucosamine sulfate, chondroitin sulfate, hyaluronic acid, diacerein, risedronate and a combination of risedronate and glucosamine) and one for the control (placebo-treated) group. Following sacrifice, femoral osteochondral cylinders and synovial membrane samples were obtained for their evaluation by qualitative and quantitative histology and micro-CT. RESULTS: The model induced osteoarthritic changes in the knee joints and none of the treatments showed a significantly better efficacy over the others. Regarding cartilage thickness and volume, all the treatments achieved scores halfway between control groups, without statistical differences. Regarding the synovial membrane, diacerein and risedronate showed the best anti-inflammatory profile, whereas glucosamine and chondroitin did not present any effect standing the hyaluronic acid results between the others. Regarding the subchondral bone, there were no differences in thickness or volume, but risedronate, diacerein and hyaluronic acid seemed to have considerably modified the orientation of the trabecular lattice. CONCLUSIONS: Out of the different drugs evaluated in the study for OA treatment, diacerein and risedronate showed, in all the parameters measured, a better profile of effectiveness; hyaluronic acid ameliorated cartilage swelling and promoted bone formation, but with a poor synovial effect; and finally, chondroitin and glucosamine sulfate prevented cartilage swelling in a similar way to the others, but had no effect on cartilage surface, synovial membrane or subchondral bone.

Sirolimus and tacrolimus rather than cyclosporine A cause bone loss in healthy adult male rats.

The aim of this work was to study the effects of cyclosporine (CsA), tacrolimus (FK-506), and rapamycin (RAPA) on bone mass, femoral microstructure, femoral biomechanical properties, and bone remodeling in healthy adult male rats. Forty-eight 5-month-old male Wistar rats were used. CsA (2 mg/kg/day), FK-506 (3 mg/kg/day), RAPA (1.25 mg/kg/day), or water (0.5 ml/rat/day, control group) were administered orally for 3 months. After sacrifice, mean values of immunosuppressants in blood were: CsA (670.4 ng/ml), FK-506 (19.2 ng/ml), and RAPA (4.8 ng/ml). Levels of biochemical parameters were normal in all groups. Femoral BMD was decreased in FK-506 and RAPA groups and lumbar BMD in FK-506 group. Trabecular volume fraction (BV/TV) decreased only in FK-506 group. RAPA and CsA affected femoral cortical structure, but FK-506 did not. FK-506 produced an increase in bone remodeling, and CsA a decrease. FK-506 group showed a decrease in biomechanical parameters relative to all groups. RAPA group showed a decrease in ultimate stress vs control group, and CsA group presented an increase in biomechanical parameters versus control group. We found that administration of both RAPA and FK-506 as monotherapy for healthy rats produced osteopenia. CsA treatment only produces slight damages in the cortical zone of the femur.

Impact of estrogens on atherosclerosis and bone in the apolipoprotein E-deficient mouse model.

OBJECTIVE: The common inflammatory pathophysiology has nourished the hypothesis of a relationship between osteoporosis and cardiovascular disease. Estrogens are key agents in the modulation of both processes. We investigated whether induction of atherosclerosis affects bone and whether estrogens modulate both processes. METHODS: Female apolipoprotein E-deficient mice (a well-established model of atherogenesis) were ovariectomized or falsely operated and fed either standard diet or high-fat diet (HFD). Six animals were included in each of the four groups. To clarify mechanisms, we treated preosteoblastic MC3T3-E1 cells with mouse serum. RESULTS: Physiological levels of estrogens in falsely operated mice limited atherosclerotic burden in the thoracic aorta, but not in the aortic arch. Bone resorption, as assessed by C-telopeptides, was increased by ovariectomy in animals fed standard diet, but not in animals fed HFD. Bone microstructural properties at the distal femur showed deteriorated trabecular architecture in bone volumetric fraction and trabecular number after ovariectomy, but trabecular pattern factor, trabecular thickness, trabecular spacing, or the structural model index remained unchanged. Changes in cortical parameters were not significant. Volumetric bone mineral density was reduced in trabecular bone, but not in cortical bone, in ovariectomized mice fed standard diet. Preosteoblastic MC3T3-E1 cells exhibited increased cellular proliferation and viability and alkaline phosphatase activity after treatment with sera from animals fed HFD. CONCLUSIONS: Endogenous estrogens partially reduce atherogenic burden in female apolipoprotein E-deficient mice. Ovariectomy increases bone resorption, but not under exacerbated proatherogenic conditions induced by HFD. The absence of apolipoprotein E might have an influence on the asymmetric responses of atherogenesis and bone resorption.

Effect of lysophosphatidic acid receptor inhibition on bone changes in ovariectomized mice.

Pharmacological inhibition of signaling through lysophosphatidic acid (LPA) receptors reduces bone erosions in an experimental model of arthritis by mechanisms involving reduced osteoclast differentiation and bone resorption and increased differentiation of osteoblasts and bone mineralization. These results led us to hypothesize that LPA receptor inhibition would be beneficial in osteoporosis. Our aim was to test this hypothesis with the LPA receptor antagonist, Ki16425, in ovariectomized mice, a model of postmenopausal osteoporosis. Ovariectomized mice treated with Ki16425 showed bone loss similar to that observed in the controls. Osteoblast markers, Alpl, Bglap and Col1a1, were increased at the mRNA level but no changes were detected in serum. No additional difference was observed in the Ki16425-treated mice relative to the ovariectomized controls with regard to osteoclast function markers or assays of matrix mineralization or osteoclast differentiation. Thus, pharmacological inhibition of LPA receptor was not beneficial for preventing bone loss in ovariectomized mice, indicating that its favorable effect on bone remodeling is less general than hypothesized.

Effects of Nrf2 deficiency on bone microarchitecture in an experimental model of osteoporosis.

OBJECTIVE: Redox imbalance contributes to bone fragility. We have evaluated the in vivo role of nuclear factor erythroid derived 2-related factor-2 (Nrf2), an important regulator of cellular responses to oxidative stress, in bone metabolism using a model of postmenopausal osteoporosis. METHODS: Ovariectomy was performed in both wild-type and mice deficient in Nrf2 (Nrf2(-/-)). Bone microarchitecture was analyzed by µCT. Serum markers of bone metabolism were also measured. Reactive oxygen species production was determined using dihydrorhodamine 123. RESULTS: Sham-operated or ovariectomized Nrf2(-/-) mice exhibit a loss in trabecular bone mineral density in femur, accompanied by a reduction in cortical area in vertebrae. Nrf2 deficiency tended to increase osteoblastic markers and significantly enhanced osteoclastic markers in sham-operated animals indicating an increased bone turnover with a main effect on bone resorption. We have also shown an increased production of oxidative stress in bone marrow-derived cells from sham-operated or ovariectomized Nrf2(-/-) mice and a higher responsiveness of bone marrow-derived cells to osteoclastogenic stimuli in vitro. CONCLUSION: We have demonstrated in vivo a key role of Nrf2 in the maintenance of bone microarchitecture.

Microstructural trabecular bone from patients with osteoporotic hip fracture or osteoarthritis: its relationship with bone mineral density and bone remodelling markers.

Osteoporosis (OP) and osteoarthritis (OA) are the most prevalent musculoskeletal disorders in the elderly but the relationship between them is unclear. The purposes of this study are to analyze the bone turnover markers (BTM), bone mineral density (BMD) and the structural and mechanical properties of trabecular bone in patients with OP and OA, and to explore the relationship between these two diseases. We studied 12 OP patients and 13 OA patients. We analyzed BTM (ß-CrossLaps and PINP), BMD and microstructural and biomechanical parameters (micro-CT). Our results were: OP group has higher levels of ß-CrossLaps and lower BMD at the femoral neck. Also, OP patients have a decreased volume of trabecular bone and less trabecular number, with architecture showing prevalence of rod-like trabeculae and worse connectivity than OA patients. The biomechanical parameters were worse in OP patients. BMD was correlated with almost all the structural and biomechanical parameters. Moreover, ß-CrossLaps was negatively correlated with hip BMD and with bone surface density and positively with trabecular separation. BTM, BMD and bone microstructural changes in osteoporosis are opposite to those of OA. These findings justify a less resistant bone with higher risk of fragility fractures in OP patients. These histomorphometric and biomechanical changes may be suspected by measuring of BMD and ß-CrossLaps levels.

Bayesian adaptive designs in single ascending dose trials in healthy volunteers.

AIM: Recent publications indicate a strong interest in applying Bayesian adaptive designs in first time in humans (FTIH) studies outside of oncology. The objective of the present work was to assess the performance of a new approach that includes Bayesian adaptive design in single ascending dose (SAD) trials conducted in healthy volunteers, in comparison with a more traditional approach. METHODS: A trial simulation approach was used and seven different scenarios of dose-response were tested. RESULTS: The new approach provided less biased estimates of maximum tolerated dose (MTD). In all scenarios, the number of subjects needed to define a MTD was lower with the new approach than with the traditional approach. With respect to duration of the trials, the two approaches were comparable. In all scenarios, the number of subjects exposed to a dose greater than the actual MTD was lower with the new approach than with the traditional approach. CONCLUSIONS: The new approach with Bayesian adaptive design shows a very good performance in the estimation of MTD and in reducing the total number of healthy subjects. It also reduces the number of subjects exposed to doses greater than the actual MTD.

Effects of PTH (1-84) on bone quality in a validated model of osteoporosis due to androgenic deprivation.

AIM: The purpose of this study was to evaluate the effect of parathyroid hormone (PTH) (1-84) in a model of male osteoporosis induced by orchidectomy in rats. METHODS: Six-month-old Wistar rats were used as follows: SHAM (simulated orchidectomy), orchidectomized (ORX), ORX + PTH1 (ORX and treated with 10 µg/Kg/d of PTH 1-84) and ORX + PTH2 (ORX and treated with 50 µg/Kg/d of PTH 1-84) over 3 months, with treatment beginning three months after orchidectomy. RESULTS: Orchidectomy resulted in a decreased of femoral and lumbar bone mineral density (BMD), a worsening of trabecular and cortical microarchitecture and a decrease in biomechanical properties. Both doses of PTH (1-84) partially (low dose) or totally (high dose) restored the ORX-induced changes. Serum C-telopeptide of type I collagen/5b isoenzyme of tartrate-resistant acid phosphatase (CTX/TRAP) resorption index increased after orchidectomy. Osteocalcin (bone Gla protein; BGP) levels were not affected by orchidectomy. PTH (1-84) treatment did not produce any changes in the levels of CTX/TRAP with respect to the ORX group. BGP levels increased with PTH treatment. CONCLUSION: PTH (1-84) is able to restore the adverse effects of orchidectomy on bone as measured by BMD, microstructural and biomechanical properties and bone remodeling markers.

The deleterious effect of bariatric surgery on cortical and trabecular bone density in the femurs of non-obese, type 2 diabetic Goto-Kakizaki rats.

BACKGROUND: The effects of type 2 diabetes on bone mass and microstructure are not clear. The aim of this study was to evaluate bone microstructural properties and volumetric bone mineral density (vBMD) in type 2 diabetic Goto-Kakizaki non-obese rats after gastrojejunal bypass and their relationship with hormonal parameters. METHODS: We designed an experimental study in Goto-Kakizaki rats with and without gastrojejunal bypass, performing densitometric and microstructural studies of the distal femur using X-ray computed microtomography (micro-CT). Levels of insulin, glucagon, leptin, and glucagon-like peptide-1 (GLP-1) were also determined. RESULTS: We observed reduced cortical (1,488.92 ± 98.2 vs. 1,727.92 ± 133.45 mg/cm(3), p = 0.028) and trabecular (180.8 ± 9 vs. 261.23 ± 45.54 mg/cm(3), p = 0.036) vBMD in operated rats. Bone volume fraction (BV/TV) and trabecular connectivity were reduced in operated rats, while there was a reduction in cortical thickness and an increase in rod-like trabeculae at the expense of plate-like trabeculae. Leptin was reduced (1,042 ± 549 vs. 2,447 ± 1,035 pg/ml, p = 0.05) and GLP-1 increased (1.62 ± 0.32 vs. 0.96 ± 0.1 ng/ml, p = 0.008) but only leptin showed a significant association with vBMD CONCLUSIONS: In type 2 diabetic Goto-Kakizaki rats, gastrojejunal bypass produces a reduction in cortical and trabecular bone mineral density and a deterioration in bone quality that could be explained, in part, by the reduction in leptin levels.