Effects of hypoxia on the expression of HIF-1α and VEGF in rat mandibular condylar chondrocytes

Objective: To investigate the expression of hypoxia inducible factor-1α(HIF-1α) and vascular endothelial growth factor(VEGF) in rat mandibular condylar chondrocytes cultured under hypoxic and normoxia conditions for different time periods.Methods: The condylar chondrocytes were in vitro cultured from SD rats aged 3 weeks.Cobalt chloride(CoCl2) was used as a chemical hypoxia-inducible reagent to mimic hypoxic microenvironment.HIF-1α and VEGF mRNA were detected by real-time PCR at 12,24 and 48 hours after initiation of hypoxia and normoxia conditions.Results: HIF-1α and VEGF mRNA were increased at 12,24 and 48 h after hypoxia(P0.05).There were significantly differences of the expressions of HIF-1α(P0.05)and VEGF(P0.05) mRNA between 12 and 24 h,12 h and 48 h,24 h and 48 h respectively after hypoxia.In hypoxia culture HIF-1α mRNA expression was gradually increased.While VEGF mRNA reached peak at 12h,and then decreased,however,it was higher than normoxia condition at all time points.Conclusion: The expressions of HIF-1α and VEGF mRNA are up-regulated under early hypoxia in mandibular condylar chondrocytes.HIF-1α increases with the time lasting and may play a role in cartilage vascularization and development.