Objective · To investigate the effects of ox-LDL on the proliferation of rat theca cells and expression of LXR-α and StAR, two genes associated with androgen biosynthesis. Methods · The expression of LXR-α in the ovarian tissue of rats was determined by immunohistochemistry. Primary theca cells were isolated and collected from rat ovary and cultured in vitro. Furthermore, the theca cells were treated with 25, 50, 100, 150, 200, 300 and 400 mg/L ox-LDL,respectively. The variations in LXR-α mRNA were identified using real-time PCR. MTT assay was performed to detect cell viability. The expression of LXR-α and StAR was measured by Western blotting analysis. Results · The effect of ox-LDL on the proliferation of rat theca cells and the levels of LXR-α and StAR in theca cells was in a concentration-dependent manner. Following exposure to various concentration of ox-LDL for 24 h, the proliferation of theca cells was induced by low concentration of ox-LDL (25-150 mg/L), and 100 mg/L ox-LDL showed the most significant inducing effect. Moreover, the cell survival rate was diminished considerably following with ox-LDL concentration increasing, especially lowered by 400 mg/L ox-LDL. The mRNA level of LXR-α was increased with low concentration of ox-LDL (25-150 mg/L) and the impact of ox-LDL on the induced expression of LXR-α mRNA was considerably distinct at the concentration of 150 mg/L. On the other hand, the expression of LXR-α mRNA was reduced with high concentration of ox-LDL, and the impact of 400 mg/L

ox-LDLwas substantially distinct. The protein expression levels of LXR-α and StAR were increased with 150 mg/L ox-LDL, but StAR protein level in 150 mg/L
ox-LDL group revealed no significant difference when compared with control group. The expression of LXR-α and StAR protein was significantly inhibited with 400 mg/L ox-LDL in the rat theca cells. Conclusion · Low concentrations of ox-LDL can induce the proliferation of theca cells, and promote the expression of StAR and LXR-α. Whereas, high concentrations of ox-LDL can reduce the cell viability and inhibit the expression of StAR and LXR-α.