The Study On Proliferation, Apoptosis And Glucose-regulated Protein Changes In Rat Mandibular Cartilage After Class Ⅲ Orthopedic Treatment

Objective:To investigate the histological change, the ultrastructure, the proliferation and apoptosis, and the alteration of ERS related glucose-regulated protein such as GRP78and GRP94in mandibular cartilage of SD rats under the effect of Class Ⅲ orthopedic treatment.Methods:45male SD rats of6weeks were divided into three groups at random, including control group, light force group and heavy force group. The rats in experiment groups wore Class Ⅲ appliance we designed by ourselves, while the rats in the control group did not. Histological change of condyles was investigated by hematoxylin and eosin stain; ultrastructural change of chondrocytes was observed by transmission electron microscope (TEM); GRP78、GRP94, and cell proliferation antigen Ki67were observed by immunohistochemisty; and apoptosis of chondrocytes was detected by TUNEL analysis.Results:The histological change of condyles revealed that cartilage became thin under light force while had pathologic lesion under heavy force. The expansion of endoplasmic reticulum, vacuolar change within the chondrocytes and sparse collagen surrounding the chondrocytes were observed by TEM during the early time under Class Ⅲ orthopedic treatment, and these degenerated alteration recovered lately. The expression of GRP78, GRP94and Ki67decreased in the condylar chondrocytes under the effect of Class Ⅲ orthopedic treatment, with the protein expressing higher in heavy force group than light force group. The apoptosis of chondrocytes in light force group was obvious in the early time and gradually decreased, whereas apoptosis of chondrocytes in heavy force group increased.Conclusion:Growth of condyle was suppressed under the effect of Class Ⅲ orthopedic treatment. Early degeneration of chondrocytes can be observed by TEM. The reducing proliferation of chondrocytes was also detected. The apoptosis of chondrocytes in light force group was obvious in the early time and gradually decreased, whereas apoptosis of chondrocytes in heavy force group increased.GRP78and GRP94expressed lower in experimental groups than control group, especially in light force group. Glucose-regulated protein may play an important role in the modification of mandibular chondrocytes under the effect of Class Ⅲ orthopedic treatment.