Pinoresinol diglucoside exhibits protective effect on dexamethasone-induced osteoporosis in rats

Purpose: To investigate the effect of pinoresinol diglucoside (PDG) on dexamethasone-induced osteoporosis in rats. Methods: Sixty Wistar rats were randomly and equally divided into normal, control, alendronate and PDG (10, 20 or 40 mg/kg) groups. Bone tissue parameters, including length, transverse diameter, weight, bone mineral content (BMC) and bone mineral density (BMD), were determined using vernier caliper, electronic balance and single photon bone mineral density meter. Serum biochemical indices, including Ca2+, inorganic phosphorus (IP), IL-6, TNF-alpha and alkaline phosphatase (ALP), were determined using colorimetry and enzyme-linked immunosorbent assay (ELISA). Osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL) proteins were detected by Western blot. Results: PDG (10, 20 or 40 mg/kg) increased significantly (p < 0.05 or 0.01) transverse diameter (3.64 - 3.79 vs. 3.31 mm), weight (0.73 - 0.78 vs. 0.67 g), BMC (0.16 - 0.23 vs. 0.12 g/cm), BMD (0.27 - 0.35 vs. 0.22 g/cm(2)) of right femur, serum Ca2+ level (2.16 - 2.39 vs. 1.94 mmol/L), and OPG level of left femur, compared with those in the control group. PDG (10, 20 or 40 mg/kg) reduced significantly (p < 0.05 or 0.01) serum IP (1.34 - 1.14 vs. 1.76 mmol/L), IL-6 (103.25 - 95.38 vs. 108.74 ng/L), TNF-alpha (87.46 - 82.05 vs. 92.38 ng/L), ALP (334.79 - 276.32 vs. 486.45 U/L) levels or activities, and RANKL level of left femur, compared with those in the control group. Conclusion: PDG exhibits a protective effect on dexamethasone-induced osteoporosis by increasing bone mass and regulating bone metabolism. Thus, PDG may be a candidate drug for treating osteoporosis.