The beneficial effect of Icaritin on osteoporotic bone is dependent on the treatment initiation timing in adult ovariectomized rats

• Published in: Bone (New York, N.Y.) N.Y.), 2013-07, Vol.55 (1), p.230-240
• Main Authors: Peng, Songlin, Zhang, Ge, Zhang, Bao-Ting, Guo, Baosheng, He, Yixin, Bakker, Anthony J, Pan, Xiaohua, Zhen, Wanxin, Hung, Leungkim, Qin, Ling, Leung, Wing-Nang
• Format: Article
• Language: English
• Subjects: Adipocytes - drug effects; Adipocytes - metabolism; Adipocytes - pathology; Aging - pathology; Animals; Biological and medical sciences; Biomarkers - metabolism; Biomechanical Phenomena - drug effects; Bone and Bones - drug effects; Bone and Bones - pathology; Bone and Bones - physiopathology; Bone biomechanical properties; Bone remodeling; Bone Resorption - drug therapy; Bone Resorption - genetics; Bone Resorption - pathology; Bone Resorption - physiopathology; Cell Differentiation - drug effects; Diseases of the osteoarticular system; Female; Flavonoids - pharmacology; Flavonoids - therapeutic use; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - drug effects; Icaritin; Medical sciences; Mesenchymal Stromal Cells - drug effects; Mesenchymal Stromal Cells - metabolism; Mesenchymal Stromal Cells - pathology; Orthopedics; Osteoblasts - drug effects; Osteoblasts - metabolism; Osteoblasts - pathology; Osteoclasts - drug effects; Osteoclasts - metabolism; Osteoclasts - pathology; Osteogenesis - drug effects; Osteogenesis - genetics; Osteoporosis; Osteoporosis - drug therapy; Osteoporosis - genetics; Osteoporosis - pathology; Osteoporosis - physiopathology; Osteoporosis. Osteomalacia. Paget disease; Ovariectomy; Rats; Rats, Sprague-Dawley; Skeleton and joints; Time Factors; Trabecular microarchitecture; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/j.bone.2013.02.012

Abstract Background Epimedium -derived flavonoids (EFs) have a potential to treat established osteoporosis in postmenopausal women. However, one of the main disadvantages of the compound is the high volume and dosage during long-term administration period. Meanwhile, the beneficial effect of EFs on osteoporotic bone depends greatly on the intervention timing. Whether Icaritin (ICT), an active molecular compound from EFs, can exert beneficial effect on osteoporotic bone and whether the beneficial effect is also dependent on the intervention timing remain unknown. Objective The objective of this study was to evaluate the effect of the early and late ICT treatment on bone turnover markers, trabecular architecture, bone remodeling, biomechanics, colony formation of bone marrow stromal cells and osteoblast, adipocyte and osteoclast-related gene expression in adult ovariectomized rats. Methods Eighty 9-month-old female rats (n = 8/group) were sham-operated (Sham) or ovariectomized (OVX). The OVX rats were subjected to ICT treatment initiation at 1 month (early treatment) and 3 months (late treatment) post-operation, respectively. The vehicle-treated Sham and OVX rats starting at month 1 and month 3 post-operation served as the corresponding controls (Sham and OVX controls) for early and late ICT treatment, respectively. Those Sham and OVX rats sacrificed immediately before early and late ICT treatment served as the pretreatment baseline controls. Both ICT and vehicle treatments lasted for 2 months. The bone turnover markers, trabecular architecture, bone remodeling and bone biomechanical properties were analyzed with biochemistry, microCT, histomorphometry and mechanical testing, respectively. The population of bone marrow stromal cells (BMSCs) and osteoblasts were evaluated with colony formation assays, respectively. The expression levels of osteoblast, adipocyte and osteoclast-related genes in bone marrow were assessed by real-time polymerase chain reaction (PCR), respectively. Results At the tissue level, early ICT treatment remarkably restored the trabecular bone mass, trabecular architecture and bone biomechanical properties towards pretreatment Sham levels, and significantly increased bone formation from pretreatment OVX level and markedly inhibited bone resorption towards pretreatment Sham level, whereas late ICT treatment failed to have any effect. At the cellular and molecular level, early ICT treatment significantly increased the number of osteoblastic