[The effect of lowered serum levels of estrogen on the expression of ERα, ERβ, OPG and RANKL in rat mandibular condylar cartilage].

PURPOSE: To investigate lowered serum estrogen on the expression of ERα, ERβ, OPG and RANKL of rat condyle and explore the possible mechanisms of idiopathic condylar resorption(ICR).

METHODS

Thirty female SD rats were randomly divided into control group, oral contraceptives group and tripterygium glycosides tablets group. The model of lowered serum estrogen level and model of premature ovarian were established by gastric gavage with oral contraceptives pills and tripterygium wilfordii glycosides tablets, respectively. The serum levels of estradiol were detected respectively before experiment and 12 weeks after experiment. After experiment, the expression of ERα, ERβ, OPG and RANKL of condyle were detected by immunohistochemistry technology. SPSS16.0 software package was used for statistical analysis.

RESULTS

The serum levels of estradiol were significantly decreased in both experimental groups. ERα, ERβ, OPG and RANKL were expressed in the condylar cartilage in all groups, mainly distributed in the hypertrophic cartilage layer. In oral contraceptives group and tripterygium glycosides tablets group, rat condylar ERα, ERβ and OPG expression were decreased and RANKL expression was increased.

CONCLUSIONS

The lowered serum estrogen concentrations decrease the expression of ERα, ERβ and OPG, raise the expression of RANKL of condylar cartilage and reduce the proportion of OPG/RANKL. In the lowered serum levels of estrogen, estrogen may mediate condylar cartilage degeneration and the subchondral bone pathological reconstruction through ER pathway by regulating the ratio of OPG/RANKL.