Bisphosphonates have also been shown to influence the degree of mineralization of bone tissue due to decreased bone turnover rates and the subsequent prolongation of secondary mineralization [14, 15], which may lead to more brittle mechanical

behavior [16–19]. Crystallinity of bone tissue has been shown to influence www.selleckchem.com/products/LY2603618-IC-83.html monotonic and fatigue mechanical properties in human cortical bone [20]. Microcracks and diffuse damage are commonly seen in human bone [21–23] and may act as a stimulus for bone remodeling [24]. Studies in dogs have shown that low resorption rates induced by bisphosphonates lead to accumulation of microcracks and diffuse damage [25]. It is unknown whether these increases in mineralization and microdamage resulting from bisphosphonates influence the mechanical properties of bone when cyclically loaded. Compressive and tensile fatigue behavior has been well documented for cortical bone from humans as well as animals [26–29]. More recently, the fatigue behavior of trabecular bone in animals and humans has been found to exhibit similar characteristics as

cortical bone [30–33]. Although these studies have provided fundamental information regarding bone fatigue MK-0457 cell line behavior, the integral function of cortical and trabecular bone, i.e., the way they act together, which plays an important role in the vertebra, has not yet been determined. Moreover, drug efficacy studies in rats generally focus on click here changes in bone mass, structure, and static mechanical strength, whereas fatigue behavior, which may play an important role in vertebral fractures, may respond differently to pharmacologic intervention than Thymidylate synthase other statically determined mechanical parameters. Our primary aim was to develop an experimental approach to determine compressive fatigue mechanical properties in whole rat vertebra. We then used this method to compare fatigue properties in ovariectomized rats treated with zoledronic acid to

SHAM, ovariectomized controls, which exhibited similar structural and static, compressive properties. Materials and methods Seventeen female, 35-week-old, Wistar rats were used from a previous study described elsewhere [12]. At week 0, eight rats were ovariectomized (OVX-ZOL), and nine rats were SHAM-ovariectomized (SHAM-OVX). Zoledronic acid was kindly provided as the disodium salt hydrate by Novartis Pharma AG (Basel, Switzerland) and was dissolved in a saline vehicle prior to injection. It was administered at a single dose of 20 μg/kg body weight s.c. at the time of OVX to all rats of the OVX-ZOL group. The dose was chosen based on a dose–response study in rats, in which 20 μg/kg body weight was found to be most effective [34]. Rats were humanely sacrificed 16 weeks later, and whole L4 vertebrae were dissected, soaked in 0.9% saline solution gauze, and frozen at −20°C.