Follicular estradiol is produced by granulosa cells through conversion of precursor androgens.
This reaction is modulated by the P450 aromatase enzyme, which we are investigating in a novel cell culture system. Insulin also stimulates aromatase gene expression and enzyme activity, although we have shown that high concentrations of insulin alter the effects of FSH on thearomatase enzyme system. Under these conditions, FSH stimulates aromatase mRNA accumulation, but decreases aromatase activity. Thus there is an uncoupling of gene expression and enzyme activity. This may have important implications for diabetic women undergoing ovarian hyperstimulation treatments for subfertility.