Non-genomic action of estradiol and progesterone on cytosolic calcium concentrations in primary cultures of human granulosa-lutein cells

Abstract

The present study examined whether the sex steroids, estradiol and progesterone, could alter cytoplasmic calcium concentrations ([Ca(2+)](cyt)) in human granulosa-lutein cells. Human granulosa cells were obtained at the time of oocyte retrieval for IVF and cultured for 3-7 days. Cells were loaded with Fura-2 AM and changes in [Ca(2+)](cyt) of single cells were studied using a dynamic digital Ca(2+) imaging system. Both estradiol and progesterone stimulated elevations of [Ca(2+)](cyt) in Ca(2+)-containing medium within seconds of exposure of the granulosa-lutein cells to the steroid, but only estradiol caused an increase in [Ca(2+)](cyt) in Ca(2+)-free medium. Both ICI-182780 and RU 486 stimulated [Ca(2+)](cyt) increases and inhibited the effects of estradiol and progesterone, respectively. Tamoxifen also induced transient increases in [Ca(2+)](cyt) concentrations but inhibited the effects of both estradiol and progesterone. The inhibitory effects of tamoxifen, ICI-182780 and RU 4486 on [Ca(2+)](cyt) responses to estradiol and progesterone could be reversed with higher concentrations of estradiol and progesterone, respectively. The [Ca(2+)](cyt) effects induced with tamoxifen could not be eliminated by prior treatment with RU 486 or ICI-182780. These results provide strong evidence that both estradiol and progesterone as well as the steroid antagonists, tamoxifen, RU 486 and ICI-182780, can act on human granulosa-lutein cells through a non-genomic mechanism.