| Objective: Temporomandibular joint disorder(TMJ)is a common clinical oral disease characterized by pain and limited function,which affects the masticatory muscles,temporomandibular joint and related structures.The pathogenic factors of temporomandibular joint remain unclear.With the development of biaxial diagnostic criteria,psychosocial factors as a possible causative factor have received extensive attention.The evidence of the relationship between psychosocial factors and oral maxillary system diseases mainly comes from epidemiological studies,clinical reports or questionnaire surveys,but there is still a lack of direct evidence from animal related experimental studies.In this study,the effects of psychological stress on the tissue structure of the condylar cartilage of the temporomandibular joint and the expression of factors related to the degradation of extracellular matrix in the condylar cartilage of the temporomandibular joint were studied by constructing a rat model of chronic restraint stress.To explore the influence of psychosocial factors on TMJ,and to provide new medical theoretical basis for the prevention and treatment of oral and maxillofacial clinical diseases.Methods: In this study,48 male adult SD rats aged 8 weeks were randomly and evenly divided into two large groups(chronic restraint stress group and blank control group),with 24 rats in each group.Then each large group was divided into three subgroups of chronic restraint stress(14 days,21 days and 28 days),with 8 rats in each subgroup.1.Chronic restraint stress(CRS)method was used to establish psychological stress model.At each time point after chronic restraint stress,state and behavior changes of rats in each group were observed and body weight was measured.Meanwhile,open field experiment and serological indicators of adrenocorticotropic hormone(ACTH)and corticosterone(CORT)were measured.It was verified that the model of chronic restraint stress was successfully constructed.2.The rats in each group were sacrificed at each time point after chronic bondage stress,and the temporomandibular joint was separated for HE staining and the histological changes of condyle cartilage and subchondral bone were observed.3.The expression of MMP-2,MMP-13 and TIMP-2 in condylar cartilage at each time point after chronic restraint stress was detected by ELISA method.Results: 1.Compared with the control group,the body weight of rats in all chronic restraint stress groups was significantly reduced(P<0.05),the scores of open field experiment were significantly decreased(P<0.05),the expressions of ACTH and CORT in serum were significantly increased(P<0.001).2.In the control group,the surface of condyle cartilage was smooth and complete at each time point in the experiment,with obvious hierarchical boundaries and orderly arrangement of subchondral bone trabecula.After 14,21 and 28 days of chronic restraint stress,degenerative diseases and abnormal remodeling of subchondral bone were observed in the condyle cartilage to varying degrees,and the lesions became more and more severe as time went on.3.The expression levels of MMP-2 and TIMP-2 in condylar cartilage of rats in the 28-day group were significantly higher than those in the control group and the 14-day group(P<0.05).Conclusion: 1.Chronic restraint stress can make rats in a state of psychological stress,showing significant depression-like behavior and related hormonal changes.2.Chronic restraint stress can lead to obvious pathological changes in the condylar tissue structure of the temporomandibular joint in rats,which are mainly manifested as degenerative diseases of the condylar cartilage to varying degrees and abnormal bone remodeling of subchondral bone.With the extension of time,the extent of the lesions is aggravated.3.Chronic restraint stress can change the expression of MMP-2,MMP-13 and TIMP-2,which are related to the degradation of extracellular matrix in condylar cartilage of temporomandibular joint in rats. |
