Abstract: Objective　To study the influence of tumor necrosis factor-alpha（TNF-α） on the secretion of testosterone and the proliferation in theca interna cells，and to investigate the role of TNF-α in the pathogenesis of polycystic ovary syndrome（PCOS）.   Methods　Different concentrations of TNF-α（10，100 and 1 000 pg/mL） were treated with theca interna cells. The secretion of testosterone in theca interna cells were detected by radioimmunoassay（RIA），and the proliferation of theca interna cells were detected by CFDA SE kit and flow cytometry. Results　The testosterone level had no difference among the groups（10，100 and 1 000 pg/mL）and the control group（0 pg/mL）at 24 h，48 h and 72 h in theca interna cells. After 72 h，the mean fluorescence intensities（MFI） in theca interna cells with TNF-α 100 pg/mL and 1 000 pg/mL were obviously lower than those in the control group（53.2±11.59 and 66.87±14.8，P＝0.013；47.55±7.31 and 66.87±14.8，P＝0.001）. Conclusions　Although TNF-α does not affect the secretion of testosterone，it can promote the proliferation of theca interna cells. This function may explain that PCOS usually accompanies thick ovarian tunica albuginea and proliferative theca cells.

Key words: Tumor necrosis factor, Theca interna cell, Polycystic ovary syndrome