Abstract: Objective To investigate whether glaucocalyxin A can reduce inflammatory response in rats with traumatic fracture. Methods The rats were randomly divided into control group, model group, low GLA (GLA-L), high GLA dose group (GLA-H) and GLA-H+YC-1 (HIF-1α inhibitor) group. The level of TNF-α, IL-6, CTX-Ⅰ, CTX-Ⅱ, S-Ca, S-P, BGP and the activities of iNOS and ALP were detected by ELISA. The density and thickness of bone trabeculae were measured by computed tomography. Apoptosis of femur tissue was detected by TUNEL. The cartilage morphology was observed by saffranin O-fast green staining. Western blot was applied to detect the expression of HIF-1α, VEGF, CD31, BMP-2, and collagenⅠ proteins in femoral tissue. Results Compared with the control group, the cartilage morphology of rats in the model group was significantly damaged, the level of serum TNF-α, IL-6, CTX-Ⅰ, CTX-Ⅱ, iNOS activity and apoptosis rate of femur tissue were increased. Serum S-Ca, S-P, BGP levels, ALP activity, bone trabecular density and thickness, HIF-1α, VEGF, CD31, BMP-2, collagen Ⅰ protein expression levels in femur tissue were all decreased(P＜0.05). The morphology of cartilage tissue in GLA-L and GLA-H groups was significantly improved, and the level of serum TNF-α, IL-6, CTX-Ⅰ, CTX-Ⅱ, iNOS activity and apoptosis rate of femur tissue were all significantly decreased. Serum levels of S-Ca, S-P, BGP, ALP activity, bone trabecular density and thickness, HIF-1α, VEGF, CD31, BMP-2, collagenⅠ protein expression level in femur tissue were significantly increased(P＜0.05). YC-1 was able to weaken the therapeutic effect of GLA on traumatic fracture rats (P＜0.05). Conclusions GLA alleviates inflammation and cartilage damage in rats with traumatic fractures, promotes angiogenesis and improves femoral morphology, possibly by activating the HIF-1α/VEGF signaling pathway.

Key words: glaucocalyxin A, traumatic fractures, inflammatory reaction, CD31