Expressions of parathyroid hormone receptor 1 in condylar cartilage of rats with temporomandibular joint os-teoarthritis

YANG Jie; ZHUANG Qian-zhi; YU Yang; WANG Yan-xia

doi:10.19538/j.kq.2023.06.011

Abstract：Objective To study the expressions of parathyroid hormone receptor 1(PTH1R)in condylar cartilage of rats with temporomandibular joint osteoarthritis(TMJOA).Methods The study was conducted in the Experimental Animal Center of Weifang Medical University and Weifang Key Laboratory of Oral Biomedicine from July 2022 to January 2023.Totally 48 healthy male SD rats aged 8 weeks were selected and divided into experimental group and control group,with 24 rats in each group.The TMJOA animal model was constructed by the elevated occlusion in the experimental group of rats,and 6 rats were euthanized respectively at week 2,4,6 and 8 after modeling,and the bilateral condyles were dissected and isolated.The rats in control group only performed the same duration of open-mouth maneuver,and the rest of the operation was the same as that of the experimental group.He-matoxylin-eosin and safranine O-fast green staining were used to observe the histological changes of condylar cartilage in each group.According to the modified Mankin scoring system,the pathological changes of condylar cartilage and sub-chondral bone were photographed and scored.Quantitative real-time PCR(qRT-PCR)and immunohistochemistry were used to detect the expression of PTH1R mRNA and protein in the condylar cartilage of each group.Results Hematoxy-lin-eosin and safranine O-fast green staining results showed that the histological morphology of the condylar cartilage in the control group was homogeneous at all time points,whereas the inflammatory changes of the condylar cartilage in the experimental group showed a time-dependent pattern and the Mankin score increased with the duration of elevated occlu-sion.The qRT-PCR results showed that the relative expression of PTH1R mRNA in the condylar cartilage of rats in the experimental group was lower than that in the corresponding control group at week 2,4,6 and 8,and the differences were all statistically significant(all P＜0.001).Immunohistochemical staining results showed that the intensity of PTH1R staining in the condylar cartilage of rats in the experimental groups gradually weakened with the prolongation of elevated occlusion.The value of integral optical density of PTH1R in the condylar cartilage of each experimental group was lower than that of the corresponding control group at week 2,4,6 and 8,and the differences were all statistically significant(all P＜0.05).Mankin scores were negatively correlated with both the relative expressions of PTH1R mRNA and the values of integral optical density in the experimental group(all P＜0.05).Conclusion During the progression of TMJOA in rats,the expression of PTH1R shows a decreasing trend,which is negatively correlated with the degree of inflammation in the condylar cartilage.PTH1R may be an indicator for evaluating the state of inflammation progression or an important target for the treatment of TMJOA.