[Effect and mechanism of Panlongqi Tablets in promoting tibial fractures in rats via improving...

By using a rat model of tibial transverse fracture,the effect of Panlongqi Tablets( PLQP) in promoting the vascularization-osteogenesis coupling of H-type vessels in fractured rats was observed. The related mechanism was explored through network pharmacology,molecular docking,and animal experiments. 72 SD rats were randomly divided into the sham operation group,the model group,the low-dose(0. 16 g·kg~(-1)),medium-dose(0. 32 g·kg~(-1)),and high-dose(0. 64 g·kg~(-1)) groups of PLQP,and Jieguqili Capsule group(0. 10 g·kg~(-1)). Each group had 12 rats. Except for the sham operation group,a tibial open fracture model was established. Each treatment group was given the drug for 21 days. The efficacy of PLQP in promoting fracture healing was evaluated by detecting the local pain and mechanical pain threshold of the affected foot,as well as methods such as X-ray of the fracture site,biomechanical testing,and HE staining. The corresponding targets of the chemical components of PLQP in the fracture transcriptome dataset of the GEO database were collected for network pharmacology analysis. Through molecular docking simulation,as well as immunofluorescence or Western blot detection,the expression levels of H-type vessel markers such as cell adhesion molecule(CD31~+) and endothelial protein(Emcn~+) generated in the fractured area,and the expression levels of the vascular endothelial growth factor(VEGF)-vascular endothelial growth factor receptor 2(VEGFR2)-Notch-1-Noggin signaling pathway molecules were detected. The results show that PLQP could significantly increase the mechanical pain and local pain thresholds after fracture in rats,promote the formation of callus at the fracture ends,improve the biomechanical characteristics of fractured rats,and promote the co-expression level of CD31~+Emcn~+Osterix~+ in the callus. Network pharmacology analysis reveals that VEGFR2 is the key target for PLQP to promote fracture healing,and it has good binding activity with the blood-distribution components of PLQP. Furthermore,Western blot and immunofluorescence experiments demonstrate that PLQP significantly increases the levels of VEGF,VEGFR2,Notch-1,and Noggin proteins,as well as the co-expression area of CD31~+Noggin~+,CD31~+Notch-1~+,and Osterix~+VEGFA~+ in the callus. The above results indicate that PLQP has analgesic and fracture healing-promoting effects and can promote the vascularization-osteogenesis coupling of Htype vessels by activating the VEGF-VEGFR2-Notch-1-Noggin signaling pathway. The related results are helpful for clarifying the efficacy content of PLQP from the perspective of vascularization-osteogenesis coupling,providing a scientific basis and theoretical support for guiding clinical application.