High levels of mineralocorticoids in preovulatory follicular fluid could contribute to oocyte development.

OBJECTIVE To identify aldosterone and precursors in ovarian follicles and to relate levels of mineralocorticoids to previously described renin-angiotensin system follicular fluid content. DESIGN Experimental. SETTING Academic laboratory and affiliated large private practice. PATIENT(S) Women undergoing oocyte retrieval for in vitro fertilization (IVF). MAIN OUTCOME MEASURE(S) The concentrations of mineralocorticoids were measured in plasma and follicular fluid. Granulosa cell mRNA expression and oocyte receptor content were evaluated. RESULT(S) High concentrations of preovulatory aldosterone and corticosterone were measured in follicular fluid (419.5±122.2 and 218,383±124,143 pg/mL, respectively). Increased mineralocorticoid levels are found in follicular fluid compared with in plasma and in large follicles compared with in small. Plasma aldosterone levels increase before ovulation. Granulosa cell gene expression that promotes aldosterone production and accumulation of corticosterone is increased in younger patients. Aldosterone receptors are localized to the surface of human oocytes. CONCLUSION(S) High levels of aldosterone and its precursor, corticosterone, were found in ovarian follicles. This combined with the presence of aldosterone receptors on oocytes suggests a possible role for aldosterone in oocyte development.