Effect of Ovariectomy, Malnutrition and Glucocorticoid Application on Bone Properties in Sheep: A Pilot Study

Lill, C. A.; Fluegel, Alexa Katrin; Schneider, Erich

doi:10.1007/s001980200058

Cited by 79 publications

(93 citation statements)

References 21 publications

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“…In addition, these medications also increase bone porosity (Po.tot 19%, Po.cl 18%, Po.op 20%, BS/BV 6%). These results are confirmed by Lill et al (2002) where they state that glucocorticosteroids in sheep lead to a reduced number of bone trabeculae (Tb.N), and decreased consistency and number of connections (ConnD down). In contrast, in humans they reduce the thickness of bone trabeculae (Tb.Th down) and do not cause changes in their consistency (Fig.…”

Section: Resultssupporting

confidence: 57%

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The experimental osteoporosis in sheep – clinical approach

Kiełbowicz¹,

Piątek²,

Bieżyński³

et al. 2015

Polish Journal of Veterinary Sciences

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The implementation of new methods of oseoporotic therapy requires tests on an animal model. One of the best is the sheep, whose numerous advantages over other models are described in the literature. The aim of this study was induction of osteoporosis using steroids and ovariorectomy methods in sheep and description of the change in parameters with regard to healthy sheep. The study was performed on female "merino" breed sheep divided into three groups: Negative control (NC) healthy animals, positive control (PC) ovariorectomised animals and steroid group (SC) where methylprednisolone was implemented. Blood tests, diagnostic arthroscopy, quantitative computed tomography and X-Ray micro-tomography of bone were carried out. Blood tests revealed a decreased level of estrogens, progesterone and increased parathormone and cortisol levels in the SC group. A decrease in bone turnover markers and an increase in bone resorption markers in all groups were also noted. Diagnostic arthroscopy revealed osteoarthrosis in PC and SC groups. Radiological density tests showed a slight decrease in PC and NC groups whereas there was more than a triple decrease in SC. Results obtained from microCT showed quickly developing osteoporosis in the SC group, which is reflected in numerous parameters analysed in this study. The best effects for osteoporosis induction were obtained using ovariorectomised sheep with methylprednisolone injections.

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Section: Resultssupporting

confidence: 57%

“…Lill et al (2002) in their studies noted 5.5% decline in bone density in the group of sheep treated with ovariectomy. Also Turner et al (1995), Turner (2002) and Newman et al (1995) noted a reduced level of bone density of 3% -8%.…”

Section: Discussionmentioning

confidence: 92%

The experimental osteoporosis in sheep – clinical approach

Kiełbowicz¹,

Piątek²,

Bieżyński³

et al. 2015

Polish Journal of Veterinary Sciences

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“…The current study was undertaken in an attempt to achieve more substantial bone loss in the lumbar spine of domestic sheep, a large animal that is frequently used for experimental studies. Based on an existing osteoporosis-induction protocol [18][19][20] that showed the greatest extent of bone loss further modifications were made in the Australian Merino sheep, in particular to the diet but perhaps more importantly to the type of steroid administered, with special emphasis on the dosing regimen. The harmful effects of corticosteroids on bone physiology are well documented but the combination of Dexafort Ò and dexamethasone sodium phosphate used in this study, providing both rapid onset and prolonged activity, effectively reduces the daily dose by 25% as well as reducing the stress associated with the daily injections.…”

Section: Discussionmentioning

confidence: 99%

Validation of the sheep as a large animal model for the study of vertebral osteoporosis

Zarrinkalam¹,

Beard²,

Schultz

et al. 2008

Eur Spine J

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Rats have long been the animal of choice for research in the field of osteoporosis. In the search for a complementary large animal model the sheep appears useful but hitherto the extent of bone loss from the spine has failed to reach a level that is generally accepted as osteoporotic in humans. Osteoporosis was induced in ten sheep using ovariectomy, low calcium diet and steroid injection for 6 months. Bone samples of iliac crest (IC), lumbar spine (LS), and proximal femur (PF) from the osteoporotic sheep were compared with those from four normal sheep using densitometry, histomorphometry, biochemistry and basic mechanical testing. The differences were examined using an analysis of variance with Tukey-Kramer test. Overall, the bone mineral density at LS and PF decreased more than 25% after treatment. Trabecular bone volume decreased by 29.2, 33.4 and 42.6% in IC, LS and PF, respectively. The failure load of the LS in axial compression was reduced to 2,003 from 6,140 N. The extent of bone loss was sufficient to categorise these sheep as osteoporotic although the pattern of bone loss varied between sites. Reduced mechanical competence in LS confirmed the suitability of this model for evaluation of potential treatments for osteoporosis.

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“…9 The sheep is often used as an animal model for studying different aspects of orthopedic research. [10][11][12][13][14][15][16][17][18][19] The OVX sheep has been found to be a particularly useful model for human bone turnover and remodeling activity. 11,20,21 In this study, we used an OVX sheep model to study the effects of increased bone turnover on compact bone mechanical and material properties.…”

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confidence: 99%

Effects of ovariectomy on bone turnover, porosity, and biomechanical properties in ovine compact bone 12 months postsurgery

Kennedy

Brennan

Rackard

et al. 2009

Journal Orthopaedic Research

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Compact bone makes up approximately 80% of the human skeleton by mass; but there are little data available on the effects of increased bone turnover on compact bone mechanical and material properties. This study addresses this question by measuring intracortical remodeling, resorption cavity number, and porosity in an ovariectomized (OVX) sheep model, and measures changes in biomechanical properties. Thirty-eight sheep were divided into two groups. Group 1 were controls (n ¼ 19), and Group 2 were ovariectomized (OVX; n ¼ 19). Fluorochrome dyes were administered intravenously to both groups at five time points over 12 months post-OVX to label sites of bone turnover. At 12 months post-OVX all animals were euthanized. Samples were harvested from the left metatarsal and were analyzed for intracortical bone turnover at five time points, the number of resorption cavities, and the level of intracortical porosity. The effects of these parameters on bone biomechanical properties were then measured. Bone turnover was increased in the OVX group at 6, 9, and 12 months (p < 0.05). Resorption was also higher in the OVX group at 12 months (p < 0.05). Furthermore, porosity was significantly increased in the OVX group at 12 months (p < 0.05). Stiffness and yield strength were reduced in the OVX group compared to controls (p ¼ 0.05). Ultimate compressive strength and work to fracture did not differ between groups. These findings provide new insights into the mechanisms and effects of increased bone turnover on bone material and microstructural properties. Keywords: bone turnover; porosity; ovariectomy; ovine animal model Bone turnover is an important determinant of the structural integrity of bone. It is a crucial process of tissue renewal that normally occurs at an optimal physiological rate for maximum bone strength in a healthy individual. 1 Any change to the optimal bone turnover rate, such as the increase that occurs following ovariectomy (OVX) or menopause, has the potential to dramatically change the bone at microstructural and material levels. High bone turnover can have the effect of increasing remodeling spaces, accelerating bone loss, increasing stress concentrations, and increasing cortical porosity, each of which can undermine bone mechanical properties. A precise definition of bone quality remains elusive, however; bone turnover and microarchitecture are considered to be two important contributors to this phenomenon along with mineralization, microdamage, and collagen content. Thus, these parameters are important considerations in the pathophysiology of skeletal diseases such as osteoporosis and the mechanisms that underlie fracture. 2 Previous studies have shown that bone turnover has a direct influence on fracture risk. 3 It is thought that compact bone is affected by accelerated turnover in two ways. First, more mineralized bone is removed and replaced with younger, less mineralized bone, which reduces the material's local stiffness. Second, the presence of more resorption cavities creates stress concen...

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Effect of Ovariectomy, Malnutrition and Glucocorticoid Application on Bone Properties in Sheep: A Pilot Study

Cited by 79 publications

References 21 publications

The experimental osteoporosis in sheep – clinical approach

The experimental osteoporosis in sheep – clinical approach

Validation of the sheep as a large animal model for the study of vertebral osteoporosis

Effects of ovariectomy on bone turnover, porosity, and biomechanical properties in ovine compact bone 12 months postsurgery

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