The Effects of Tarasaponin IV on Bone Regeneration and Osteoclast Formation in Rats

This study investigates the effects of TRS (tarasaponin IV) on bone reconstruction and osteoclast formation in rats with AF (ankle fractures) via the BMP-2 (bone morphogenetic protein-2)/SMAD4 signaling path way. AF models were established in rats, which were then randomly divided into the AF group, TRS-L (low-con centration TRS) group, TRS-M (medium-concentration TRS) group, TRS-H (high-concentration TRS) group, and TRS-H+Noggin (BMP-specific inhibitor) group. Additionally, a sham operation group (Sham group) consisting of normal rats without fractures was included. ELISA (enzyme linked immunosorbent assay) was used to detect bone remodeling markers [Runx2 (Runt-related transcription factor 2), BMP-2, ALP (alkaline phosphatase), RANKL (re ceptor activator of nuclear factor kappa B ligand)] in serum of rats in each group. Micro-CT was used to detect the microstructural changes of bone trabeculae of rats in each group [BMD (bone mineral density), BV/TV (bone vol ume fraction), Tb.N (number of trabeculae), and Tb.Th (thickness of trabeculae)]. The HE (hematoxylin-eosin) and TRAP (tartrate resistant acid phosphatase) staining methods were used to detect the morphological and pathologi cal changes of callus tissue and the number of osteoclasts of rats in each group. Western blot was used to detect the Runx2, ALP, RANKL, BMP-2, and SMAD4 proteins in each group. Compared with the Sham group, the AF group showed great decreased in Runx2, BMP-2, ALP, SMAD4, BMD, BV/TV, Tb.N, Tb.Th, great increases in RANKL and osteoclast count, and conspicuous decreased in ankle stiffness and maximum load (P<0.05). Compared with the AF group, the TRS-L, TRS-M, and TRS-H groups showed gradual increases in Runx2, BMP-2, ALP, SMAD4, BMD, BV/TV, Tb.N, Tb.Th in rats, gradual decreased in RANKL and osteoclast count, and gradual increases in ankle stiffness and maximum load, and the degree of change in each indicator was directly proportional to TRS con centration (P<0.05). Compared with the TRS-H group, the TRS-H+Noggin group showed conspicuous decreased in Runx2, BMP-2, ALP, SMAD4, BMD, BV/TV, Tb.N, Tb.Th, conspicuous increased in RANKL and osteoclast count, and great decreases in ankle stiffness and maximum load (P<0.05). TRS may promote bone remodeling and inhibit osteoclast formation in AF rats by activating BMP-2/SMAD4 signaling pathway.

CSTR: 32200.14.cjcb.2025.11.0008