Anti‑osteoporotic effects of tetramethylpyrazine via promoting osteogenic differentiation and inhibiting osteoclast formation

Abstract Long‑term glucocorticoid therapy results in various side effects, including a high incidence of glucocorticoid‑induced osteoporosis (GIOP), which is the most common form of secondary osteoporosis. Excess glucocorticoids reduce the viability of bone marrow‑derived mesenchymal stem cells (BMSCs) and prolong osteoclast survival. These two types of cell are essential in the balance between bone formation and resorption. Tetramethylpyrazine (TMP), the pharmacologically active component extracted from Chuanxiong, has been reported to protect BMSCs from glucocorticoid‑induced apoptosis. In the present study, the protective effects of TMP on BMSC differentiation and osteoclasts maturation in GIOP were investigated in vivo and in vitro. The immunostaining of osterix (OSX) and tartrate‑resistant acid phosphatase (TRAP) staining indicated that TMP promoted osteogenesis and inhibited osteoclastogenesis in a rat model of GIOP. Treatment with 10‑6 M dexamethasone (Dex) significantly inhibited BMSC differentiation and increased TRAP‑positive cells in vitro. However, different concentrations of TMP (50, 100 and 200 µM) ameliorated the negative effects of Dex by promoting the activity of alkaline phosphatase (ALP) and the calcium mineralization of BMSCs following osteogenic induction, which increased the expression levels of osteogenic genes, including ALP, collagen type I α1, osteocalcin and OSX, and decreased osteoclastogenesis‑related genes, including TRAP, nuclear factor of T‑cells cytoplasmic 1 and cathepsin K. In addition, it was found that the inhibition of receptor activator of nuclear factor‑κB ligand and intereleukin‑6 in BMSCs may be a possible mechanism for the protective effects of TMP against glucocorticoid‑induced osteoclastogenesis. These results are the first, to the best of our knowledge, to demonstrate that TMP promotes BMSC differentiation and inhibits osteoclastogenesis to ameliorate bone mass change in GIOP.