Acteoside Derived from Cistanche Improves Glucocorticoid-Induced Osteoporosis by Activating PI3K/AKT/mTOR Pathway

Glucocorticoids are widely used in clinical practice; however, they can cause side effects, such as osteoporosis. Acteoside (ACT) from Cistanche has been used to combat a variety of diseases. The study was conducted to evaluate the efficacy of ACT in glucocorticoid-induced osteoporosis (GIOP) and its potential mechanism.Dexamethasone (Dex) was injected intramuscularly to induce osteoporosis in a rat model, and ACT was given orally. ACT was supplemented in vivo in Dex-stimulated osteoblastic MC3T3-E1 cells. RT-qPCR was performed to assess the mRNA levels of bone formation (Runx2, CoL1A1), and bone resorption (OPG and RANKL). A commercial ELISA kit was applied to assess serum OC and CTX levels. Western blot was performed to assess protein levels in the PI3K/AKT/mTOR signaling pathway. CCK-8 assay and flow cytometry were performed to assess osteoblast viability and apoptosis.ACT reduced Dex-induced bone microstructure deterioration, increased serum levels of OC, and decreased the levels of CTX (P < 0.05). In the MC3T3-E1 cells, Dex inhibited cell viability and promoted apoptosis; however, this effect was greatly attenuated by ACT (P < 0.05). Concurrently, ACT reversed the reduction in Runx2, osterix, CoL1A1, and OPG mRNA levels, ALP activity, and the promotion of RANKL by Dex. Additionally, ACT attenuated Dex-induced inhibition of p-AKT/AKT, p-mTOR/mTOR, and p-PI3K/PI3K protein levels by Dex (P < 0.05), while the PI3K/AKT/mTOR pathway inhibitor LY294002 diminished the potential effect of ACT (P < 0.05).ACT from Cistanche may exert osteoprotective effects by activating the PI3K/AKT/mTOR signaling pathway to alleviate Dex-induced osteoporosis.