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OBJECTIVE: The aim of this study was to determine the ability of undenatured native chicken type II collagen (UC-II) to prevent excessive articular cartilage deterioration in a rat model of osteoarthritis (OA). METHODS: Twenty male rats were subjected to partial medial meniscectomy tear (PMMT) surgery to induce OA. Immediately after the surgery 10 rats received vehicle and another 10 rats oral daily dose of UC-II at 0.66 mg/kg for a period of 8 weeks. In addition 10 naïve rats were used as an intact control and another 10 rats received sham surgery. Study endpoints included a weight-bearing capacity of front and hind legs, serum biomarkers of bone and cartilage metabolism, analyses of subchondral and cancellous bone at the tibial epiphysis and metaphysis, and cartilage pathology at the medial tibial plateau using histological methods. RESULTS: PMMT surgery produced moderate OA at the medial tibial plateau. Specifically, the deterioration of articular cartilage negatively impacted the weight bearing capacity of the operated limb. Immediate treatment with the UC-II preserved the weight-bearing capacity of the injured leg, preserved integrity of the cancellous bone at tibial metaphysis and limited the excessive osteophyte formation and deterioration of articular cartilage. CONCLUSION: Study results demonstrate that a clinically relevant daily dose of UC-II when applied immediately after injury can improve the mechanical function of the injured knee and prevent excessive deterioration of articular cartilage.
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Cartílago Articular/efectos de los fármacos , Colágeno Tipo II/farmacología , Articulación de la Rodilla/efectos de los fármacos , Osteoartritis de la Rodilla/patología , Administración Oral , Animales , Cartílago Articular/diagnóstico por imagen , Cartílago Articular/patología , Cartílago Articular/fisiopatología , Pollos , Colágeno Tipo II/administración & dosificación , Modelos Animales de Enfermedad , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/patología , Articulación de la Rodilla/fisiopatología , Masculino , Meniscectomía , Osteoartritis de la Rodilla/diagnóstico por imagen , Osteoartritis de la Rodilla/fisiopatología , Osteofito/diagnóstico por imagen , Osteofito/patología , Osteofito/fisiopatología , Ratas , Ratas Endogámicas Lew , Tibia/diagnóstico por imagen , Tibia/efectos de los fármacos , Tibia/patología , Soporte de Peso , Microtomografía por Rayos XRESUMEN
INTRODUCTION: Rheumatoid arthritis (RA) is characterized by joint pain, allodynia and hyperalgesia. The rat carrageenan model utilizes inflammation-associated pain following injection of the knee joint to model RA. Traditional assessment of pain in these models utilizes behavioral scoring or manual measurements, methods that are labor intensive and prone to subjective interpretation. This study utilizes the Digigait system to objectively quantify movement and gait dynamics in a monoarthritic rat model. MATERIAL AND METHODS: A pilot study in rats selected "natural" runners using Digigait, and also measured inter and intraday variability as well as effects of anesthesia on gait dynamics. In the main study, 12 female rats were tested at baseline, divided in two groups of 6 rats, briefly anesthetized with isoflurane and injected with 60 microl of 2% lambda carrageenan or vehicle; Digigait testing was repeated 2 and 4 hours post injection and data analyzed. RESULTS: Selection of "natural" runners significantly contributed to accuracy and reproducibility of gait parameters obtained by the Digigait system. There was minimal intra and inter day variation between individual rats and 4 minutes of isoflurane anesthesia had no effect on gait dynamic at 2 and 4 hours post administration. In the main study a highly reproducible gait signature in the injected limb, and well coordinated adaptation of gait during locomotion in the non-affected limbs were noted as short-term changes following carrageenan injection. CONCLUSION: Digigait system was found to be an objective and reliable method for quantification of early behavioral changes consistent with allodynia and hyperalgesia in an inflammatory pain model.
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Artritis Reumatoide/fisiopatología , Diagnóstico por Imagen/métodos , Marcha/fisiología , Animales , Artritis Reumatoide/inducido químicamente , Carragenina/toxicidad , Diagnóstico por Imagen/instrumentación , Modelos Animales de Enfermedad , Femenino , Procesamiento de Imagen Asistido por Computador , Inflamación/inducido químicamente , Inflamación/fisiopatología , Irritantes/toxicidad , Masculino , Proyectos Piloto , RatasRESUMEN
Intermittent combination of an anabolic agent to promote bone formation and an antiresorptive agent that would prevent further bone loss is a theoretically attractive approach for restoring bone mass. We tested the potential of intermittently dosed calcitriol and calcitonin (CT) to restore bone properties in ovariectomized (Ovx) rats. Rats had Ovx or sham surgery at 8 weeks old and 4 weeks later were assigned to experimental groups: (1) sham vehicle, (2) Ovx vehicle, (3) Ovx + parathyroid hormone (PTH, 40 microg/kg), and (4) Ovx + calcitriol (2 microg/kg) + CT (2 microg/kg). Group 3 received PTH every week throughout the study, and group 4 received calcitriol at weeks 1, 3, 5, and 7 and CT at weeks 2, 4, 6, and 8. Dosing was carried out for 8 weeks with serum, and micro-computed tomographic analysis was done at 0, 4, and 8 weeks. Femurs and tibias were used for radiological analyses and for mechanical testing. Dosing with PTH improved bone mass and structure of cancellous bone at metaphyses of tibias and femurs as well as properties of cortical bone including geometry and strength. Intermittent dosing with calcitriol and CT was less potent in correcting loss of cancellous bone relative to treatment with PTH and had no effect on cortical bone parameters. However, intermittent dosing with calcitriol and CT was robust enough to improve cancellous bone mass and structure through bone formation without causing deleterious side effects. Our data provide additional evidence that therapies can be devised to ameliorate the skeletal defects associated with established osteoporosis.
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Huesos/metabolismo , Calcitonina/metabolismo , Colecalciferol/metabolismo , Absorciometría de Fotón , Animales , Biomarcadores/metabolismo , Remodelación Ósea , Femenino , Fémur/patología , Ovario/fisiología , Ratas , Ratas Sprague-Dawley , Estrés Mecánico , Tibia/patología , Tomografía Computarizada por Rayos X/métodosRESUMEN
In both sexes, a reduction in sex steroid production with aging impairs the musculoskeletal system. The goal of our study was to test the ability of WH-9062, a novel non-steroidal small molecule inhibitor of the 17beta-Hydroxysteroid Dehydrogenase type 2 enzyme, to maintain or improve bone strength without raising serum levels of testosterone or estradiol. Mature, female cynomolgus monkeys with sealed growth plates were allocated into six groups: Sham controls, OVX controls, OVX+Premarin (15 mg/kg/d), and three groups of OVX monkeys receiving WH-9062 at 1, 5 and 25 mg/kg/day. All treatments were administered by daily oral dosing for 23 weeks. Changes in lipid profile caused by OVX were corrected with WH-9062 and included lowering total of cholesterol and non-HDL cholesterol, and maintenance of initial plasma levels of HDL cholesterol. Only the highest dose of WH-9062 lowered bone resorption relative to OVX controls. Elevated bone specific alkaline phosphatase, osteocalcin, BMC and dynamic bone histomorphometry data resulted in desirable bone balance and bone strength. The obtained results support our theory that inhibition of 17beta-HSD type 2 resulted in high local estrogen and/or testosterone levels leading to maintenance of bone formation and bone strength. Collectively, our data demonstrated that the treatment paradigm that utilizes tissue selectivity and receptor bioavailability in conversion of inactive hormones to active forms could be achieved and could result in desirable effects on target tissues such as bone and muscles.
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Huesos/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Ovariectomía , Pirrolidinonas/farmacología , Resistencia a la Tracción/efectos de los fármacos , Tiofenos/farmacología , 17-Hidroxiesteroide Deshidrogenasas/antagonistas & inhibidores , Administración Oral , Fosfatasa Alcalina/metabolismo , Animales , Densidad Ósea/efectos de los fármacos , Remodelación Ósea/efectos de los fármacos , Resorción Ósea , Esquema de Medicación , Inhibidores Enzimáticos/administración & dosificación , Estrógenos/administración & dosificación , Estrógenos/farmacología , Estrógenos Conjugados (USP)/administración & dosificación , Estrógenos Conjugados (USP)/farmacología , Femenino , Macaca fascicularis , Osteocalcina/metabolismo , Osteogénesis/efectos de los fármacos , Pirrolidinonas/administración & dosificación , Tiofenos/administración & dosificaciónRESUMEN
This manuscript reviews the theories behind the propensity of prostate cancer to cause bone metastases and skeletal implications of the prostate cancer biology and treatment modalities. The escape of tumor cells from the primary tumor in the prostate to secondary tumor sites in the axial skeleton probably occurs before the primary tumor is detected. Several theories offer explanations for the observed proclivity of prostate tumors to selectively colonize the axial skeleton. The interaction between the tumor cells and cells that populate bone marrow, in particular osteoblasts and osteoclasts, is important for creating a 'fertile' environment where tumor cells can establish and grow. Prostate cancer cells are capable of producing growth factors that can affect both osteoblasts, resulting in osteoblastic bone formation, and osteoclasts, resulting in excessive bone resorption. In addition to the capability to progress from testosterone-dependent to testosterone-independent phenotype, the hallmark of metastatic prostate cancer is osteosclerosis similar to one induced experimentally in nude rats using CWR22 human prostate cancer cell line. Metastatic bone disease caused by excessive bone formation and bone resorption is the major cause of morbidity in patients with prostate cancer. The most common symptoms include pain, pathological fractures, spinal cord compression, cranial nerve palsies, bone marrow suppression and hypercalcemia. The introduction of prostate-specific antigen in clinical practice created a shift to where more prostate cancer patients with early disease receive androgen ablation treatment, which in return causes more bone loss and cancer-associated osteoporosis. Introduction of third generation bisphosphonates to treat skeletal consequences of malignancy further stressed the important interaction between the bone marrow stroma and cancer cells. Nevertheless, animal models and human prostate tumor cell lines that mimic all aspects of skeletal conditions in prostate cancer patients including osteoblastic bone response are needed to develop and screen for novel therapeutic and diagnostic modalities.
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We investigated the utility of CWR22 human prostate cancer cells for modeling human metastatic prostate cancer, specifically their ability to induce bone formation following intra-tibial injections in the nude rat. Prostate cancer is unique in regard to its tropism for bone and ability to induce new bone formation. In contrast to humans, other mammalian species rarely develop prostatic cancer spontaneously upon aging and do not have the propensity for bone metastasis that is the hallmark of cancer malignancy in men. We chose human prostate cancer cell line CWR22 based on its properties, which closely resemble all of the features that characterize the early stages of prostatic cancer in human patients including slow growth rate, hormone dependence/independence and secretion of prostate-specific antigen. When CWR22 cells were injected directly into the proximal tibia of immunodeficient male rats, both osteoblastic and osteolytic features became evident after 4 to 6 weeks, with elevated levels of serum prostate-specific antigen. However, osteosclerosis dominates the skeletal response to tumor burden. Radiological and histological evidence revealed osteosclerotic lesions with trabeculae of newly formed bone lined by active osteoblasts and surrounded by tumor cells. Toward the end of the 7-week study, osteolytic bone lesions become more evident on X-rays. Paraffin and immunohistochemical evaluations revealed mature bone matrix resorption as evidenced by the presence of many tartrate resistant acid phosphatase positive multinucleated osteoclasts. We conclude that the CWR22 human prostate cell line used in an intra-tibial nude rat model provides a useful system to study mechanisms involved in osteoblastic and osteolytic bony metastases. This type of in vivo model that closely mimics all major features of metastatic disease in humans may provide a critical tool for drug development efforts focused on developing integrated systemic therapy targeting the tumor in its specific primary or/and metastatic microenvironments. In addition to targeting bone marrow stroma, this strategy will help to overcome classical drug resistance seen at the sites of prostate cancer metastasis to bones.
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Previous studies have suggested that 14-47% of the variation in bone mineral density (BMD) can be predicted using clinical risk factors. The aim of our study was to determine, for the first time, the importance of these factors in individuals with evidence of a genetic predisposition to the disease. The subjects studied were 147 female and 86 male Caucasians, all with a family history of osteoporosis. Linear regression was used to determine whether age, height, weight, and years of reduced estrogen exposure were significant predictors of BMD. Males and females were examined separately, and BMD was measured at the hip and spine. The results show that these risk factors, known to be at work in the general population, are equally important in those with a family history of osteoporosis. It is clear, therefore, that they must be taken into account, and corrected for in genetic studies of the disease.
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Densidad Ósea , Osteoporosis/genética , Osteoporosis/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Modelos Lineales , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Factores de RiesgoRESUMEN
Eighty mature Sprague-Dawley rats were weight matched before ovariectomy (Ovx) or Sham surgery (Sham). Sham rats had free access to food and water throughout the experiment, whereas Ovx rats were kept on the pair-fed diet. Rats were euthanized at 4, 8, and 12 weeks after surgery, and had received fluorochrome bone markers at 9 and 2 days prior to euthanasia. In addition 10 rats were euthanized at the time of surgery serving as baseline controls. All rats were also scanned for body composition and bone mineral parameters by DEXA before surgery and euthanasia. Left proximal femurs (femoral necks) were used for bone histomorphometry, whereas right femurs were used for in vitro DEXA measurements and mechanical testing. Despite pair-feeding, ovariectomized rats had increased body weights and fat body mass, whereas the percent lean body mass steadily declined throughout the experiment. Mineral density of the whole femur and femoral neck was significantly higher in the Sham rats relative to Ovx animals. Ovariectomy reduced trabecular number and thickness, and increased trabecular separation and bone marrow space at the femoral midneck location. The structure of the remaining trabeculae was dramatically changed toward simpler struts as revealed by nodal analyses. Cortical thickness in Ovx rats was reduced because of the high endocortical resorption, which, in addition to cancellous bone resorption, resulted in fewer endocortico-trabecular connections. Femoral necks obtained from ovariectomized rats had reduced strength and were less stiff relative to controls. Because of the enormous clinical significance of the proximal femur for osteoporosis in humans, and the opportunity for studying bone BMD, mass, structure, and strength at the same skeletal location, the femoral neck appears superior to other skeletal sites routinely used for bone histomorphometry or mechanical testing in the Ovx rat model.
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Composición Corporal/fisiología , Densidad Ósea/fisiología , Estrógenos/deficiencia , Cuello Femoral/patología , Cuello Femoral/fisiopatología , Absorciometría de Fotón , Animales , Fenómenos Biomecánicos , Peso Corporal/fisiología , Resorción Ósea/fisiopatología , Modelos Animales de Enfermedad , Femenino , Cuello Femoral/diagnóstico por imagen , Cuello Femoral/ultraestructura , Colorantes Fluorescentes/administración & dosificación , Humanos , Microscopía Electrónica de Rastreo , Osteoporosis Posmenopáusica/fisiopatología , Ovariectomía , Ratas , Ratas Sprague-DawleyRESUMEN
Because the ovariectomized rat model of postmenopausal osteoporosis is the most commonly used small animal model to investigate consequences of bone loss on bone structure and strength, or to assess benefits of the various therapeutic strategies to improve bone mass and strength, the attempt was made to compare histoanatomical and structural characteristics of the femoral neck between human and rat models. In addition to different biomechanics, there is a significant difference in gross- and microanatomy of the proximal femur between humans and rats. Percent of the cortical bone component is much higher in rats (72.5%) relative to humans (12.5%). Also, cortical bone at the femoral neck in rats is evenly distributed, whereas in humans there is a considerable difference in the amount of the cortical bone between the superior half of the femoral neck with cortical thickness being only 0.3 mm, and the inferior half of the neck having 6-mm-thick cortex. Humans have far more cancellous bone at the femoral neck (22.7% average) relative to rats (6.8%). In addition, cancellous bone at the femoral neck in humans is unevenly distributed between the bone center and its periphery. Human samples exhibited striking differences in the cancellous bone structure between weight-bearing and tensile trabecular groups exhibiting clear trabecular orientation consisting of plates and rods, and trabeculae around the neutral bone axis with little mechanical activity exhibiting rod-like trabeculae only. Although humans and rats have a periosteum covering the femoral neck, and each lacks the muscular attachment at intracapsular portions of the femoral neck, rats, in contrast to humans, have the ability to quickly adapt cortical thickness and increase inertia to meet mechanical needs via modeling-dependent periosteal apposition.
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Cuello Femoral/anatomía & histología , Fémur/anatomía & histología , Anciano , Animales , Femenino , Histocitoquímica , Humanos , Procesamiento de Imagen Asistido por Computador , Ovariectomía , Posmenopausia , Ratas , Ratas Sprague-DawleyRESUMEN
BACKGROUND: Hip fractures are the most devastating consequence of osteoporosis in humans. Since the ovariectomized (ovx) rat is a useful model of estrogen-deficient osteoporosis, the purposes of this study were to describe the histo-anatomical features of the rat hip and to determine changes in the proximal femur induced by ovariectomy to evaluate the use of this skeletal site for future bone studies. METHODS: Changes in body mass and composition and in bone mineral content and density were determined by DEXA at 12 weeks after ovariectomy. Gross and histo-anatomy of the rat hip was studied by light microscopy and histomorphometry. Cancellous and cortical bone changes induced by ovx at the femoral midneck were determine using dynamic, static, and structural histomorphometric techniques. The stiffness of the femoral neck was determined by biomechanical testing, and the results were correlated with histological observations and the histomorphometric data. RESULTS: The bony structures of the rat hip, articular cartilage, and muscular and capsular attachments are very similar to the human. Rats, however, have an active growth plate and a well-vascularized periosteum covering the intracapsular portion of the femoral neck, which is different from the adult humans. Rats in the sham and ovx groups exhibited similar biological variations in the thickness of the femoral neck and epiphyseal bone and cartilaginous composition. Ovariectomy promoted periosteal modeling and induced endocortical and cancellous bone remodeling, with a net loss of bone mass due to excess bone resorption. The ovx-induced increase in resorption resulted in reduced trabecular number, thickness, and endocortico-trabecular connectivity, which likely contributed to less bone stiffness in ovx rats relative to the sham controls. CONCLUSIONS: There are numerous similarities in the structure and histology of the rodent and human hip. Skeletal changes induced by ovariectomy in rats, particularly those at the endocortical surface and in the cancellous bone, are very similar to changes observed in the proximal femur in osteoporotic women. In addition, ovx in the rat had compromised the biomechanical properties at the femoral neck, similar to what occurs in the postmenopausal women. Data presented here confirmed responsiveness of the proximal femur in rat to ovarian hormone deficiency, which appears to be a useful and relevant site to investigate mechanisms and interventions relative to human disease.
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Huesos/anatomía & histología , Huesos/fisiología , Fémur/anatomía & histología , Ovariectomía , Ratas/anatomía & histología , Absorciometría de Fotón , Animales , Elasticidad , Femenino , Tamaño de los Órganos , Ratas Sprague-Dawley , Valores de ReferenciaRESUMEN
Sixteen-week-old Sprague-Dawley rats were ovariectomized (Ovx) or sham-operated and housed for 8 weeks to develop osteopenia prior to systemic administration of rhIGF-I (0.9 and 2.6 mg/kg) alone or the rhIGF-I/IGFBP-3 (0.9, 2.6 and 7.5 mg/kg) complex. After 8 weeks of treatment, proximal femurs were fixed, embedded, and cut through the midneck region. Structural and dynamic histomorphometric analyses were performed using standard techniques. Ovx increased endocortical resorption and modeling-dependent periosteal formation which resulted in decreased cortical bone area. Despite increased bone formation, trabecular number, thickness, and area were all reduced due to increased resorption. Structural changes following Ovx included fewer struts and nodes, a higher percentage of the simpler strut forms, and reduced endocortico-trabecular connectivity. Eight weeks of treatment with rhIGF-I or rhIGF-I/IGFBP-3 promoted periosteal and endocortical bone formation and reduced the endocortical resorption induced by Ovx. Both rhIGF-I formulations stimulated bone formation on existing trabecular surfaces which increased trabecular thickness and area but not trabecular number. These treatments prevented further deterioration of the trabecular network caused by Ovx and preserved endocortico-trabecular connectivity. In summary, changes in the femoral neck following Ovx appear to be similar in rats and humans. The highest dose of rhIGF-I/IGFBP-3 used in this study showed the best results in promoting cortical and cancellous bone formation, and appears to be promising therapy for human osteopenias.
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Densidad Ósea/efectos de los fármacos , Enfermedades Óseas Metabólicas/tratamiento farmacológico , Proteínas Portadoras/farmacología , Cuello Femoral/efectos de los fármacos , Factor I del Crecimiento Similar a la Insulina/farmacología , Animales , Desarrollo Óseo/efectos de los fármacos , Enfermedades Óseas Metabólicas/patología , Remodelación Ósea/efectos de los fármacos , Femenino , Cuello Femoral/patología , Fracturas de Cadera/etiología , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina , Masculino , Ovariectomía , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes/farmacologíaRESUMEN
The purpose of this study was to compare dose-related effects on cortical bone and lean body mass following subcutaneous administration of rhIGF-I alone, or bound to an equimolar amount of rhIGFBP-3 to adult Ovx rats. At the age of 16 weeks, rats were ovariectomized or sham-operated and were allowed 8 weeks to develop osteopenia. After being divided into control (saline treated) or treatment groups, rats were injected daily during an 8-week period with 0.9 and 2.6 mg/kg of rhIGF-I, or with 0.9, 2.6, and 7.5 mg/kg of rhIGF-I bound to rhIGFBP-3. Fluorescent bone markers were given 9 and 2 days prior to necropsy. Body weights and lean body mass were monitored throughout the experiment. Cortical bone histomorphometry was performed on tibial cross-sections at the tibiofibular junction, and endochondral bone growth was measured at the distal femoral metaphysis. All rats treated with rhIGF-I or the rhIGF-I/IGFBP-3 complex had increased body weights, corresponding to a dose-dependent increase in lean body mass. Endochondral growth was slightly increased in all experimental groups, but was not dose-dependent. A dramatic increase in periosteal, modeling-dependent formation, coupled with decreased or unchanged resorption on the endocortical envelope resulted in a dose-dependent increase in cortical thickness and cross-sectional area in groups treated with the complex of rhIGF-I/IGFBP-3. This complex appeared to be more effective in promoting positive musculoskeletal changes than rhIGF-I alone.(ABSTRACT TRUNCATED AT 250 WORDS)
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Densidad Ósea/efectos de los fármacos , Enfermedades Óseas Metabólicas/tratamiento farmacológico , Proteínas Portadoras/farmacología , Inhibidores de Crecimiento/farmacología , Factor I del Crecimiento Similar a la Insulina/farmacología , Absorciometría de Fotón , Animales , Peso Corporal/efectos de los fármacos , Desarrollo Óseo/efectos de los fármacos , Desarrollo Óseo/fisiología , Enfermedades Óseas Metabólicas/fisiopatología , Resorción Ósea/tratamiento farmacológico , Proteínas Portadoras/administración & dosificación , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Femenino , Inhibidores de Crecimiento/administración & dosificación , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina , Factor I del Crecimiento Similar a la Insulina/administración & dosificación , Músculo Esquelético/efectos de los fármacos , Ovariectomía , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/farmacología , Somatomedinas/administración & dosificación , Somatomedinas/farmacología , Tibia/efectos de los fármacos , Tibia/fisiologíaRESUMEN
The dose-related effects of systemically administered rhIGF-I and rhIGF-I/IGFBP-3 were monitored in the osteopenic rat skeleton at three different sites with cancellous bone: distal femoral metaphysis, epiphysis, and lumbar vertebral bodies. At the age of 16 weeks, rats were bilaterally ovariectomized (OVX) or sham operated (sham) and 8 weeks later divided into the control groups (sham OVX), and OVX groups treated with different doses of rhIGF-I or rhIGF-I/IGFBP-3 for 8 weeks. Fluorescent bone markers were given 9 and 2 days before necropsy. In addition, changes in designated bone sites as a result of ovariectomy alone were evaluated 8 and 16 weeks after surgery. High bone resorption, which dominates the postovariectomy remodeling process, resulted in a loss of cancellous bone at all measured sites. The highest trabecular bone loss was measured in the metaphyses (40%), compared with 22% in the lumbar vertebrae and 16% in the epiphyses. After 8 weeks of treatment with 7.5 mg/kg of rhIGF-I/IGFBP-3, bone formation rates were increased at all sites measured. Increased trabecular thickness was observed at the epiphyses and in the lumbar vertebral bodies. Increased bone resorption was restricted to the metaphyses of the rats that received the highest dose of rhIGF-I or rhIGF-I/IGFBP-3. Both formulations of rhIGF-I increased longitudinal bone growth similarly. This experiment demonstrates site-specific differences in cancellous bone reactions following ovariectomy. Epyphyses showed some advantages for cancellous bone histomorphometry over metaphyses and lumbar vertebral bodies. The data presented confirm the potential of rhIGF-I/IGFBP-3 complex to promote the bone formation process at various bone sites in osteoporotic rat skeleton.
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Desarrollo Óseo/efectos de los fármacos , Proteínas Portadoras/administración & dosificación , Factor I del Crecimiento Similar a la Insulina/administración & dosificación , Ovariectomía , Animales , Resorción Ósea/fisiopatología , Femenino , Fémur/efectos de los fármacos , Fémur/fisiología , Inyecciones Subcutáneas , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina , Vértebras Lumbares/efectos de los fármacos , Vértebras Lumbares/fisiología , Ratas , Ratas Sprague-DawleyRESUMEN
BACKGROUND: Ovariectomy (OVX) and immobilization (IMM) in rats are useful models of osteopenia, replicating some aspects of osteoporosis in humans. The purpose of this study was to compare changes in cancellous bone after OVX and/or IMM. METHODS: Differences in cancellous bone were determined at 6 and 12 weeks after OVX or IMM. Comparisons were also made when rats were ovariectomized or immobilized for 6 weeks and then immobilized (OVX/IMM) and ovariectomized (IMM/OVX), respectively, for 6 more weeks. The femurs were used to determine bone mineral content (BMC) using single photon absorptiometry (SPA) and for scanning electron microscopy (SEM). Tibias were collected for microradiography, image analysis, and histomorphometry of metaphyseal cancellous bone. RESULTS: Six and 12 weeks after OVX, there was less cancellous bone mass, compared with controls, as indicated by SPA, SEM, microradiography, image analyses, and histomorphometry. Bone was lost primarily from the central metaphyseal regions in the OVX animals, whereas the loss occurred throughout the metaphyses in the IMM animals. There were more rodlike bone spicules and fewer platelike trabeculae in the OVX and IMM groups compared with controls. Differences in the structural aspects of the cancellous bone, including differences in the types of bone struts and marrow star volumes, indicated less trabecular connectivity and greater trabecular separation in the OVX and IMM animals, compared with controls. Endochondral growth indices in the IMM groups tended to be less, whereas the OVX groups tended to be greater than controls. Cancellous bone formation rates were generally greater in the OVX groups but less in the IMM groups compared with controls. Osteoclastic resorption surfaces were substantially elevated in the IMM and OVX groups, particularly the IMM groups. Changes reflecting OVX and IMM, independently, were apparent in the OVX/IMM and IMM/OVX groups and indices of osteopenia were different from controls, including less bone mass, trabecular connectivity, and greater trabecular separation, bone turnover rates, and osteoclastic surface. CONCLUSIONS: These results demonstrate differences in the osteopenic changes that occur in cancellous bone following OVX or IMM. The changes were generally more dramatic in the IMM than in the OVX animals. When OVX and IMM were applied in combination, the osteopenic changes are particularly severe, emphasizing the importance of mechanical usage even with a deficiency of gonadal hormones.
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Enfermedades Óseas Metabólicas/fisiopatología , Inmovilización/efectos adversos , Ovariectomía/efectos adversos , Animales , Densidad Ósea , Enfermedades Óseas Metabólicas/etiología , Huesos/diagnóstico por imagen , Huesos/fisiopatología , Femenino , Fémur/fisiopatología , Microscopía Electrónica de Rastreo , Radiografía , Ratas , Ratas Sprague-Dawley , Tibia/fisiopatología , Factores de TiempoRESUMEN
Gonadal hormone deficiency following ovariectomy and skeletal unloading by limb immobilization are useful models of osteopenia. The purpose of this study was to compare changes in cortical bone after ovariectomy (OVX) or immobilization (IMM) for 6 and 12 weeks. Comparisons were also made when rats were ovariectomized or immobilized for 6 weeks and then immobilized (OVX/IMM) and ovariectomized (IMM/OVX), respectively, for 6 more weeks. Tibias and femurs were collected and static and dynamic cortical bone indices were determined by morphometric methods. Femurs from animals OVX or IMM for 12 weeks were tested for bone stiffness by torsional testing. Six and 12 weeks after OVX, there were increases in the periosteal perimeter, cortical area, and periosteal bone formation indices, indicating that ovariectomy increased modeling-dependent bone gain on the periosteal envelope, relative to controls. Contrarily, 6 and 12 weeks after IMM, there were decreases, compared with controls, in periosteal perimeter, cortical bone area, and periosteal bone formation indices. This indicates that immobilization decreased modeling-dependent bone gain on the periosteal envelope. These differences in modeling between the animals that were OVX and IMM resulted in a smaller cortical width and minimum cortical width in the IMM compared with the OVX animals. There were significant decreases in cortical bone stiffness and minimum cortical width at the fracture site following mechanical testing in the animals IMM for 12 weeks. Both ovariectomy and immobilization increased endocortical resorption surface, endocortical perimeter and expansion of the marrow cavity. Because of suppressed periosteal bone formation with increased endocortical resorption, immobilization had a greater effect on bone loss and decreased bone stiffness than did ovariectomy.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Huesos/patología , Inmovilización , Ovario/fisiología , Animales , Femenino , Ovariectomía , Ratas , Ratas Sprague-DawleyRESUMEN
A serum-free, fetal bone organ culture model that permits the simultaneous determination of modeling and growth parameters was used to examine the effects of a near physiologic and a pharmacologic dose of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3]. The fetuses of pregnant mice were removed on day 17 of gestation, and three medial metatarsal rudiments were cleaned and after preculturing were cultured as pair-matched groups for 4 days in MEM supplemented with 0.2% BSA. 1,25-(OH)2D3 was added to the cultures at concentrations of 10(-12) or 10(-6) M. Cultures treated with the carrier and devitalized bones served as controls. For resorption studies, pregnant mice were given 45Ca on day 17 of pregnancy and fetal metatarsals harvested 24 h later. Resorption was determined by the amount of 45Ca released into the media. DNA synthesis was estimated by determining the incorporation of [3H]thymidine, collagen synthesis by measuring the incorporation of [3H]proline, mineralization by the incorporation of 45Ca, and proteoglycan synthesis by the incorporation of 35S. The amount of radiolabel was detected in media, as well as in noncultured, dead, and cultured rudiments. The total length of the rudiments and length of the calcified diaphyses were measured daily. In addition, rudiments from all experimental groups were prepared for light and electron microscopy. The high dose (10(-6) M) of 1,25-(OH)2D3 suppressed total rudiment growth but not the growth of the calcified diaphysis, 1,25-(OH)2D3 also decreased DNA, collagen, and proteoglycan synthesis, reduced calcification, and increased bone resorption in a dose-related manner. There were morphologic and ultrastructural changes in the osseous tissues and cells, particularly with the high dose of vitamin D, that supported the biochemical findings of suppressed activity of the osteogenic and chondrogenic cells. However, the suppression of collagen production and bone cell proliferation observed with the pharmacologic dose of vitamin D may be partially attributable to the decrease in bone mass (from increased resorption), thus resulting in less osseous tissue surface for these events to occur as endochondral osteogenesis progressed. The lower dose of vitamin D, however, had effects on 35S and 45Ca incorporation that could not be attributed to a decreased osseous tissue mass. This study emphasizes the importance of measuring specialized activities of the various cell populations in bone rudiment culture models to more fully understand the changes in tissue metabolism that result in changes in rudiment growth and modeling.
Asunto(s)
Desarrollo Óseo/efectos de los fármacos , Calcitriol/farmacología , Osteogénesis/efectos de los fármacos , Animales , Resorción Ósea/tratamiento farmacológico , Calcio/metabolismo , Medio de Cultivo Libre de Suero , Relación Dosis-Respuesta a Droga , Feto , Huesos Metatarsianos/efectos de los fármacos , Huesos Metatarsianos/embriología , Huesos Metatarsianos/ultraestructura , Ratones , Microscopía Electrónica , Técnicas de Cultivo de ÓrganosRESUMEN
Osteopenia and mechanical incompetence are the defining features of osteoporosis, yet the effects of changes in bone structure on mechanical properties are not completely understood. The primary objective of this study was to determine if in a rodent model, changes in cortical bone structure, as measured by static morphometry, would correlate with functional properties, as measured by torsional testing. For this, cortical bone structure and stiffness were determined in overloaded and underloaded limbs in rats rendered ovarian hormone-deficient by ovariectomy (OVX). Rats were OVX and six weeks later a hind limb was immobilized by casting for an additional six weeks. In all cases the femur from the underloaded, casted limb was compared with that from the contralateral, overloaded limb. The success of this experimental protocol was confirmed by differences in femoral cancellous bone volume by microradiography and single photon absorptiometry, with the overloaded limb having a greater bone volume and bone mineral density than the contralateral, immobilized controls. Morphometric differences in the femoral diaphyseal cortical bone included greater endocortical perimeter and endocortical osteoclast surface, less cortical area, less minimum cortical width, and less minimum cortical width at fracture planes when the bones were tested for stiffness in the underloaded, compared with the contralateral, overloaded limbs. Using a torsional test, the ultimate torque to failure and stiffness were less in the underloaded femurs compared with the contralateral, overloaded femurs. These results emphasize the importance of mechanical loading on bones from a gonad-deficient animal.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Huesos/patología , Ovario/fisiología , Animales , Huesos/fisiopatología , Femenino , Fémur/patología , Fémur/fisiopatología , Ovariectomía , Ratas , Ratas Endogámicas , Restricción Física , Estrés Mecánico , Anomalía TorsionalRESUMEN
The morphology, ultrastructure, tartrate-resistance acid phosphatase reactivity, and calcitonin responsiveness of osteoclasts induced at sites of demineralized bone matrix (DBM) implant-induced osteogenesis in rats were determined. Osteoclasts at these ectopic sites had a morphologic and ultrastructural appearance similar to osteoclasts normally found in skeletal tissues. When observed by scanning electron microscopy, resorption surfaces on the implants had well-defined resorption pits (Howship's lacunae), indicative of active bone resorption. The osteoclasts stained intensely for tartrate-resistance acid phosphatase, an enzyme that is specific for osteoclasts. In response to human calcitonin, hypocalcemia occurred and osteoclasts lost their ruffled borders, indicating that these cells are responsive to exogenous hormonal stimulation. The osteoclasts induced by subcutaneous implantation of DBM had morphologic and functional characteristics similar to osteoclasts normally found in skeletal tissues.