Abstract: Objective　　To explore the relationship between IhhPTHrP feedback pathway and the biological response to alteration of pressure microenvironment in the condylar chondrocytes.Methods　　The condylar chondrocytes from the temporomandibular joint of 4weekold New Zealand white rabbit were aseptically dissected and cultured in vitro.The monolayer of condylar chondrocytes was subjected to the static pressure of 100 kPa at different times (0 h,1 h,2 h,3 h and 4 h).Production of COL2A1,Ihh and PTHrP was examined by western blot and quantitative realtime PCR.The changes of condylar chondrocytes (100 kPa,3 h) morphology were analyzed by scanning electron microscope compared with the control group (100 kPa,0 h).Oneway ANOVA was performed using SPSS19.0 software package for statistical analysis.Results　　The western blot results showed that the exposure of chondrocytes to 100 kPa resulted in significant up regulation of COL2A1 after 3h.Increased expression of Ihh and PTHrP could be found in the condylar chondrocytes in respond to static pressure within 0～2h.Moreover,Ihh reduced in the condylar chondrocytes within 2～4h,whereas the expression of PTHrP maintained a high level after 2h′s treatment.The gene expression of Ihh and PTHrP was similar to the proteins.The result of scanning electron microscope showed that the process of the condylar chondrocytes prolonged after 3 hours treatment.Conclusions　　The condylar chondrocytes is good at adapting to the alteration of pressure microenvironment.It is sure that a suitable static pressure loading can accelerate chondrogenesis of condylar chondrocytes.IhhPTHrP feedback pathway is involved in the regulation of the alteration of pressure microenvironment in condylar chondrocytes.

Key words: TMJ, Condyle, Chondrocyte, Static pressure, Ihh, PTHrP, Rabbit