Diverse Bone Matrix and Mineral Alterations in Osteoporosis with Different Causes: A Solid-State NMR Study

Osteoporosis (OP), which is a common skeletal disease with different causes, is prevalent in the aging population. Postmenopause women generally suffer from OP with bone loss due to estrogen deficiency. Diabetes is also associated with OP by complex metabolic mechanisms. Bone qualities of OP caused by aging were compared with those of the ovariectomy (OVX) model and the Type 2 diabetic model using Sprague-Dawley (SD) rats in our study. Combining with micro-computed tomography (μ-CT) and solid-state NMR (SSNMR) methods, this research studied bone changes in SD rats from tissue level to the molecular level. The studies revealed bone loss was most significant for cancellous bones but not for cortical bones in OP rats. However, at the molecular level, the content of HAP in cortical bone increased with aging, contributing to the brittleness of the bone. Triglyceride, as a senescence maker of osteocyte in cortical bone, was also identified to be closely associated with OP in aging and OVX rats but not in diabetic rats. This research suggests that changes of bone quality at the molecular level more objectively reflect the bone tissue reconstruction of OP with various causes rather than mere bone loss revealed by μ-CT analysis.