Steroidogenic acute regulatory protein (StAR) in the ovaries of healthy women and those with polycystic ovary syndrome

Abstract

Objective: Polycystic ovary syndrome is the most common cause of oligo-ovulation, affecting approximately 4% of women. A primary defect of steroidogenesis resulting in increased ovarian and adrenal androgen production may be responsible for polycystic ovary syndrome, at least in some patients. Because the action of the steroidogenic acute regulatory protein (StAR) initiates the process of steroidogenesis, we proceeded to test the hypothesis that increased production or concentration of StAR may result in the abnormality of steroidogenesis found in polycystic ovary syndrome.

Study design: We examined the ovaries from 10 healthy women and 7 women with polycystic ovary syndrome, determining the relative concentration of StAR in total protein extracts by use of Western blotting, and the overall distribution and staining intensity of StAR in prepared tissue sections.

Results: Overall the ovaries of healthy women and women with polycystic ovary syndrome demonstrated a similar prevalence and size of follicular cysts, although the ovaries of women with polycystic ovary syndrome had a greater mean number of follicular cysts. In general, the distribution of StAR immunoreactivity within most of the ovarian structures was not different in the ovaries of women with polycystic ovary syndrome compared to those of the healthy ovaries. However, the ovaries from the cases demonstrated a significantly greater number of follicular cysts with staining for StAR immunoreactivity in the thecal cells than did the ovaries from healthy women (100% vs 38%, P <.05).

Conclusion: These data suggest that the exaggeration in androgen biosynthesis in the ovaries of patients with polycystic ovary syndrome may be occurring at its earliest step (ie, that involving StAR), such that an increased amount of cholesterol is made available for androgen biosynthesis in the polycystic ovary.