Lithium prevents glucocorticoid‐induced osteonecrosis of the femoral head by regulating autophagy.

Autophagy may play an important role in the occurrence and development of glucocorticoid‐induced osteonecrosis of the femoral head (GC‐ONFH). Lithium is a classical autophagy regulator, and lithium can also activate osteogenic pathways, making it a highly promising therapeutic agent for GC‐ONFH. We aimed to evaluate the potential therapeutic effect of lithium on GC‐ONFH. For in vitro experiments, primary osteoblasts of rats were used for investigating the underlying mechanism of lithium's protective effect on GC‐induced autophagy levels and osteogenic activity dysfunction. For in vivo experiments, a rat model of GC‐ONFH was used for evaluating the therapeutic effect of oral lithium on GC‐ONFH and underlying mechanism. Findings demonstrated that GC over‐activated the autophagy of osteoblasts and reduced their osteogenic activity. Lithium reduced the over‐activated autophagy of GC‐treated osteoblasts through PI3K/AKT/mTOR signalling pathway and increased their osteogenic activity. Oral lithium reduced the osteonecrosis rates in a rat model of GC‐ONFH, and restrained the increased expression of autophagy related proteins in bone tissues through PI3K/AKT/mTOR signalling pathway. In conclusion, lithium can restrain over‐activated autophagy by activating PI3K/AKT/mTOR signalling pathway and up‐regulate the expression of genes for bone formation both in GC induced osteoblasts and in a rat model of GC‐ONFH. Lithium may be a promising therapeutic agent for GC‐ONFH. However, the role of autophagy in the pathogenesis of GC‐ONFH remains controversial. Studies are still needed to further explore the role of autophagy in the pathogenesis of GC‐ONFH, and the efficacy of lithium in the treatment of GC‐ONFH and its underlying mechanisms. [ABSTRACT FROM AUTHOR]