| Objective To investigate the effects and mechanism of Schizandrin B (SchB) on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) under high glucose (HG) conditions. Methods Rat BMSCs were isolated and screened for experimental concentrations of SchB. BMSCs were divided into normal (NC) group, high glucose (HG) group, HG+10 μmol/L SchB group, HG+20 μmol/L SchB group, HG +40 μmol/L SchB group, and HG+40 μmol/L SchB+AMPK inhibitor Compound C (CC) group. Cell viability was detected with CCK-8 method. Alkaline phosphatase (ALP) activity assay and Alizarin red staining were performed to evaluate the osteogenic differentiation ability of BMSCs. qRT-PCR was used to detect the expression of osteogenic differentiation-related genes (RUNX2, COl1a1, OCN, BMP2) in BMSCs. The number of autophagosomes was observed with transmission electron microscopy (TEM). Western blotting was used to detect the expression of autophagy (LC3A/B, Beclin-1, P62) and AMPK/mTOR signaling pathway-related proteins. Results HG environment inhibited the proliferation and osteogenic differentiation of BMSCs, reduced the number of autophagosomes, Beclin-1 protein level and LC3II/LC3I, p-AMPK/AMPK ratio, increased P62 protein level and p-mTOR/mTOR ratio (all P<0.05), and inhibited autophagy mediated by AMPK/mTOR pathway. SchB promoted the proliferation and osteogenic differentiation of BMSCs under HG condition, increased the number of autophagosomes, Beclin-1 protein level and LC3II/LC3I, p-AMPK/AMPK ratio, decreased P62 protein level and p-mTOR/mTOR ratio (all P<0.05), and activated AMPK/mTOR pathway-mediated autophagy. CC blocked the promoting effects of SchB on BMSCs proliferation, osteogenic differentiation, and autophagy under HG condition. Conclusion SchB may promote the proliferation and osteogenic differentiation of BMSCs under HG condition by activating AMPK/mTOR-mediated autophagy. |