Abstract: The objective of this investigation was to study the effect of genistein (GEN) on the gene expression of steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc) and cytochrome P450 aromatase (CYP19) involved in steroid synthesis in ovarian tissue of young female rats. Forty female SD rats were selected and divided according to their body mass into control, low-, middle- and high- dose GEN, (15, 30 and 60 mg/(kg·d)), and negative control (NC, administered with diethylstilbestrol at 0.5 mg/(kg·d)) groups. The whole experiment was lasted for 30 d. The gene expression of StAR, P450scc and CYP19 mRNA was detected by real-time polymerase chain reaction. The protein expression of StAR and P450scc was detected by Western blot analysis. Compared with the NC group, the body mass of rats in the GEN groups showed no significant difference (P > 0.05); the expression levels of StAR, P450scc, CYP19 mRNA increased, especially in the middle- and high-dose groups (P < 0.05); the protein expression of StAR significantly increased in the high-dose group (P < 0.05); the protein expression of P450scc significantly increased in the middle- and high-dose groups (P < 0.05). Conclusively, GEN at a dose of 30–60 mg/kg can increase the expression of key enzymes involved in androgen synthesis in the ovaries of young female rats, and consequently affect the development and maturation of follicles.

Key words: genistein, steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc), cytochrome P450 aromatase (CYP19), young female rat