Protective effects of oridonin against osteoporosis by regulating immunity and activating the Wnt3a/β-catenin/VEGF pathway in ovariectomized mice

• Oridonin may play a role in the treatment of osteoporosis by positively regulating the Wnt3a/β-catenin/VEGF signaling pathway . • Oridonin may play a role in the treatment of osteoporosis by promoting angiogenesis , improving the immunity of mice, and maintaining the balance of the immune system . • Oridonin might have therapeutic potential for the treatment of bone lytic diseases caused by postmenopausal. This study was performed with the aim of investigating the effect of oridonin (ORI) on estrogen deprivation-induced osteoporosis in mice and its mechanism. Animal experiments were used in this work to validate the anti-osteoporotic efficacy of ORI. Morphometric analysis was performed by micro-CT. A special protein meter was used to detect the content of immunoglobulin lgM, immunoglobulin lgG, complement C3 and C4 in the serum of mice. The expression of CD4 + CD25 + Foxp3 + Treg cell and CD4 + /CD8 + lymphocyte subsets in mice was detected by flow cytometry. ELISA was used to detect the content of insulin-like growth factor (IGF-1), tumor necrosis factor (TNF-α), interleukin-1 (IL-1) and interleukin-6 (IL-6). In addition, key signaling molecules in the Wnt3a/β-catenin signaling pathway were detected by Western blotting. The results showed that compared with the model group, the contents of calcium and phosphorus in the femurs of mice in the ORI groups were increased, and the spleen coefficient was decreased. The ALP activity in the serum of mice in the high and medium dose ORI groups was decreased, and the uterine coefficient was increased. ORI significantly increased the maximum bending load and the maximum bending stress of the femurs of mice, increased the number of trabeculae, and repaired the bone microstructure. At the same time, ORI could significantly increase the levels of immunoglobulin (lgG and lgM) and complement (C3 and C4), increase the activity of peritoneal macrophages in mice, increase the expression of CD4 + CD25 + Foxp3 + Tregs and CD4 + /CD8 + in the spleen, increase the content of IGF-1, reduce the content of TNF-α, IL-1 and IL-6 and increase the expression levels of VEGF, Wnt3a, p-GSK3β/GSK3β and β-catenin/Lamin in the femoral tissue. These results indicated that ORI might regulate the expression of VEGF through the Wnt3a/β-catenin signaling pathway, improve the immunity of mice, maintain the balance of the immune system, and promote angiogenesis, thereby improving the bone mineral density and bone tissue morphology of mice and playing an anti-osteoporotic role.