BACKGROUND: Postmenopausal osteoporosis (PMOP) is a bone disease resulting from estrogen deficiency. This investigation explores the impact of icariin (Ica) on PMOP.
METHODS: Bilateral ovariectomy was performed to establish an ovariectomized (OVX) mouse model, followed by Ica administration. Bone parameters were measured using micro computed tomography. Fat content were evaluated using hematoxylin-eosin staining. Osteogenic/adipogenic differentiation of mouse bone marrow mesenchymal stem cells (BMSCs) were analyzed by Alkaline Phosphatase, Alizarin Red S, and Oil Red O staining. Reverse transcription-quantitative polymerase chain reaction measured bone and lipid marker gene expression. Transcriptome sequencing and cell counting kit-8 were conducted, and the expression of AMPK-mTOR-autophagy pathway proteins and bone and lipid marker proteins was detected by immunohistochemistry and Western blot. Autophagy inhibitor 3-Methyladenine (3-MA) and AMPK inhibitor dorsomorphin were employed to validate the role of autophagy and AMPK in Ica treatment of PMOP.
RESULTS: Ica treatment raised bone mass while reducing fat content in OVX mice in a dose-dependent manner. Ica promoted osteogenesis and inhibited adipogenesis in BMSCs from OVX mice. Transcriptome sequencing showed that autophagy and mTOR pathways were involved in PMOP. Ica reduced mTOR and p62 expression and increased LC3 expression in OVX mice and their BMSCs, and 3-MA reversed this phenomenon. The AMPK pathway was downregulated in OVX mice and their BMSCs, but was activated following Ica treatment. The application of dorsomorphin altered the expression of AMPK-mTOR-autophagy pathway in Ica-treated BMSCs.
CONCLUSION: Ica alleviates PMOP by regulating osteogenic/adipogenic differentiation of BMSCs, which may involve the AMPK-mTOR-autophagy pathway.
