Extracts from plastrum testudinis reverse glucocorticoid-induced spinal osteoporosis of rats via targeting osteoblastic and osteoclastic markers

Extracts from plastrum testudinis (PTE), an important traditional Chinese medicine, have been demonstrated promotion of osteoblastic function in vitro. This study aims to investigate the protective effect of PTE on glucocorticoid-induced osteoporosis(GIOP) in vivo and analyze therapeutic targets of PTE on GIOP. SD rats were randomly assigned to two experiments: preventive and therapeutic experiments, in which rats respectively received oral PTE at the same time of glucocorticoid injection or after glucocorticoid injection inducing osteoporosis. BMD, microarchitecture, biomechanics, bone metabolism markers and histomorphology were evaluated. mRNA and protein expression of OPG, Runx2, CTSK and MMP9 were examined.Results showed bone quality and bone quantity were significantly elevated by PTE. Histomorphometry showed thicker and denser bone trabecularsand more osteoblasts and less osteoclasts in group of PTE intervention. The mRNA expression of OPG was significantly upregulated whereas expression of CTSK was significantly downregulatedin different groups of PTE intervention. Stronger immunostaining for Runx2 and weaker immunostaining for CTSK were observed in groups of PTE intervention. This demonstrated that PTE may reverse GIOP in prevention and management via targeting OPG, Runx2 and CTSK in mRNA and protein levels.