The Effects of Oridonin on Periodontal Inflammation and Osteoclasts in Orthodontic Tooth Movement Model Rats by Adjusting the ERK/MAPK Signaling Pathway
SU Dawei1, LI Jiaxin2, QIU Chengyu2, AN Houpeng1 *
This article mainly investigates the effects of Ori (oridonin) on periodontal inflammation and osteoclasts in OTM (orthodontic tooth movement) model rats by regulating the ERK/MAPK (extracellular regulated protein kinase/mitogen-activated protein kinase) signaling pathway. After successfully establishing the OTM rat model, the modeled rats were randomly divided into five groups: OTM group, Ori-L group (Ori low-dose group), Ori-H group (Ori high-dose group), positive drug MTZ (metronidazole) group (MTZ group), and Ori high-dose+ERK/MAPK signaling pathway activator Anisomycin group (Ori-H+Anisomycin group). In addition, an equal number of normal rats were randomly selected as the Con group (Control group). The OTM distance in each group of rats was measured. The levels of serum inflammation related factors were detected. The pathological changes and osteoclast activity of periodontal tissues were assessed. The expression levels of OPG (osteoprotegerin), RANKL (receptor activator of nuclear factor kappa B ligand), BMP-2 (bone morphogenetic protein-2), and ERK/MAPK signaling pathway-related proteins in periodontal tissues were determined. Compared with the Con group, rats in the OTM group exhibited disordered arrangement of periodontal tissue fibers on the pressure side, with a large number of multinucleated osteoclasts accumulating in bone resorption lacunae; the OTM distance, serum levels of IL-6, IFN-γ and PGE2, osteoclast count, as well as the levels of RANKL, BMP-2, p-ERK1/2/ERK1/2, and p-p38 MAPK/p38 MAPK were significantly increased, while the expression level of OPG was significantly decreased (P<0.05). Compared with rats in the OTM group, rats in the Ori-L group, Ori-H group, and MTZ group showed restored arrangement of periodontal tissue fibers on the pressure side, reduced number of multinucleated osteoclasts, and alleviated pathological damage; the serum levels of IL-6, IFN-γ, PGE2, osteoclast count, as well as the levels of RANKL, pERK1/2/ERK1/2, p-p38 MAPK/p38 MAPK were significantly decreased, while the OTM distance and the expression levels of BMP-2, and OPG were significantly increased (P<0.05). Compared with rats in the Ori-H group, rats in the Ori-H+Anisomycin group showed aggravated pathological damage and disordered fiber arrangement of periodontal tissue fibers on the pressure side; the serum levels of IL-6, IFN-γ, PGE2, osteoclast count, as well as the levels of RANKL, p-ERK1/2/ERK1/2, p-p38 MAPK/p38 MAPK were significantly increased, while the OTM distance, the expression levels of BMP-2 and OPG were decreased (P<0.05). In conclusion, this study demonstrates that Ori can inhibit periodontal inflammation and osteoclast activation in OTM rats, thereby promoting OTM, which may be closely related to the inhibition of the ERK/MAPK signaling pathway.
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