Beta-Ecdysone protects osteocytes from excess glucocorticoids via Akt1-mediated regulation of Connexin43

Glucocorticoid-induced osteoporosis (GIOP) is a leading cause of secondary osteoporosis (OP). β-Ecdysone (βEcd), a naturally occurring estrogen analog, was evaluated for its ability to mitigate the effects of glucocorticoids (GCs) on osteocytes, the crucial cells in bone remodeling. In GIOP mouse model induced by dexamethasone (Dex), micro-CT, biomechanical testing, silver nitrate staining, and hematoxylin-eosin (HE) staining were employed, demonstrating that βEcd effectively attenuated Dex-induced decreases in bone mass and strength, and alleviated Dex induced reduction in osteocyte dendrite and viability. Network pharmacology analysis predicted that the therapeutic efficacy of βEcd against GIOP is mediated through the crucial targets such as protein kinase B (Akt1), with significant enrichment in pathways including apoptosis and phosphoinositide 3-kinase (PI3K)-Akt signaling. In vitro, the osteocyte-like MLO-Y4 cells were treated with 10 μM Dex for 48 h in the presence or absence of βEcd or the PI3K inhibitor LY294002 (LY). Crystal violet staining and connexin43 (CX43) immunofluorescence (IF) staining were employed, and western blot was used to assess the levels of Akt1, phospho (p)-Akt, CX43, p-CX43, and apoptosis-related factors. Hoechst staining and annexin V/PI apoptosis assays were also used to evaluate apoptosis. The results demonstrated that βEcd counteracted Dex-induced apoptosis by modulating Akt1 and CX43 expression in MLO-Y4 cells, while inhibition of Akt activity reversed these effects, suggesting that βEcd targets the Akt1 gene. The findings indicate that βEcd protects osteocytes from GC-induced apoptosis through Akt-mediated regulation of CX43, highlighting its potential as a therapeutic approach for the prevention and treatment of GIOP.