Abstract: Objective:To investigate the expression of vascular endothelial growth factor (VEGF) during the healing process of tooth extraction, and to clarify the effect of panax notoginseng saponins(PNS) in promoting the healing of extraction and its mechanism. Methods:Forty-five SD male rats were randomly divided into control group(not given any drugs),chitosan thermosensitive gels group(given chitosan thermosensitive gels without panax notoginseng saponins), 0.5 g·L^-1 PNS group(given chitosan thermosensitive gels and 0.5 g·L^-1 PNS),1.0 g·L^-1 PNS group (given chitosan thermosensitive gels and 1.0 g·L^-1 PNS),and 1.5 g·L^-1 PNS group(given chitosan thermosensitive gels and 1.5 g·L^-1 PNS), with 9 rats in each group.After the middle incisors of right lower jaw were removed, about 20 μL of chitosan thermosensitive gels containing different concentrations of PNS was injected into the each tooth extraction wound of the rats in other groups,except control group. The rats were sacrificed at 1, 2, and 4 weeks after administration, and the specimens were prepared.HE staining was used to observe the healing status of tooth extraction wounds at 1, 2, and 4 weeks after administration.Immunohistochemical staining was performed to detect the number of VEGF positive cells and the expression levels of VEGF protein at 1,2, and 4 weeks after administration. Results:The HE staining resuls showed that the healing status of tooth extraction wounds in chitosan thermosensitive gels group was similar to that in control group;compared with control group, the osteoblasts and vascular endothelial cells were highly differentiated and migrated and the number of bone trabecula was increased. Compared with control group, at 1,2, and 4 weeks after administration, there were no significant differences in the number of VEGF positive cells and the protein expression level of VEGF in the tooth extraction wound tissue of the rats in chitosan gel group (P>0.05); the number of VEGF positive cells and the protein expression level of VEGF of the rats in 0.5,1.0,and 1.5 g·L^-1 PNS groups were significantly increased (P<0.05). Conclusion:PNS can up-regulate the expressions of VEGF in vascular endothelial cells and osteoblasts in tooth extraction wounds of the rats, induce the differentiation of vascular endothelial cells and osteoblasts, increase the number of migration and aggregation of cells, and achieve the effect of promoting the tooth extraction wound healing.

Key words: panax notoginseng saponins, chitosan, bone formation, vascular endothelial growth factor