Induction of osteoporosis with its influence on osteoporotic determinants and their interrelationships in rats by DEXA

Abstract

SummaryBackgroundAs women are the population most affected by multifactorial osteoporosis, research is focused on unraveling the underlying mechanism of osteoporosis induction in rats by combining ovariectomy (OVX) either with calcium, phosphorus, vitamin C and vitamin D2/D3 deficiency, or by administration of glucocorticoid (dexamethasone).Material/MethodsDifferent skeletal sites of sham, OVX-Diet and OVX-Steroid rats were analyzed by Dual Energy X-ray Absorptiometry (DEXA) at varied time points of 0, 4 and 12 weeks to determine and compare the osteoporotic factors such as bone mineral density (BMD), bone mineral content (BMC), area, body weight and percent fat among different groups and time points. Comparative analysis and interrelationships among osteoporotic determinants by regression analysis were also determined.ResultsT scores were below-2.5 in OVX-Diet rats at 4 and 12 weeks post-OVX. OVX-diet rats revealed pronounced osteoporotic status with reduced BMD and BMC than the steroid counterparts, with the spine and pelvis as the most affected skeletal sites. Increase in percent fat was observed irrespective of the osteoporosis inducers applied. Comparative analysis and interrelationships between osteoporotic determinants that are rarely studied in animals indicate the necessity to analyze BMC and area along with BMD in obtaining meaningful information leading to proper prediction of probability of osteoporotic fractures.ConclusionsEnhanced osteoporotic effect observed in OVX-Diet rats indicates that estrogen dysregulation combined with diet treatment induces and enhances osteoporosis with time when compared to the steroid group. Comparative and regression analysis indicates the need to determine BMC along with BMD and area in osteoporotic determination.

Quantification of calcium content in bone by using ToF-SIMS–a first approach

“…The osteoporotic induction applied over several months allows a tracking of the degradation of the bone which comes along with a reduction of the bone mineral content and density [18]. In a previous study these results were confirmed by a semi quantitative analysis of the Ca content [11].…”

“…Beside this a remarkable and statistical significant reduction of about 50% of the HAP content for the osteoporotic animals (OVX + diet group) can be found. However, the extreme reduction revealed by ToF-SIMS measurements is plausible and a qualitative comparison with BMD evaluated by DEXA measurements shows the same tendencies although not to this extent [18]. Due to the experimental conditions, like the Ca and Vitamin D deficient diet, wide regions of the trabeculae are not mineralised anymore, which indicates rather osteomalacia than osteoporosis.…”

“…A31/2009). The protocol and procedures employed in the animal experiment were reported previously in detail [18].…”

Characterization of Bone-Marrow-Derived Stem Cells in Osteoporotic Models of the Rat

“…In a previous study we have shown that enhanced osteoporotic effects ( scores below −2,5, reduced bone mineral density and bone mineral content measured by means of Dual Energy X-ray Absorptiometry, DEXA) could be seen in rats by combining ovariectomy with calcium, phosphorus, vitamin c, and vitamin D2/D3 deficiency over a period of 12 weeks [4]. However, little information is available about mesenchymal stem cells (MSCs) residing in the bone marrow of the "osteoporotic" rats.…”

“…In this study, we therefore focused on characterization of rat MSC three months after osteoporosis had been induced experimentally [4]. Investigations in vitro have been done in order to evaluate putative cellular changes of rat MSC regarding their proliferation, migration, and differentiation capacity.…”