Non-genomic mechanisms of action of steroid hormones.

Sex steroid hormones are known to act through intracellular receptors and their cognate hormone response elements, located in the promoters of hormone-regulated genes. However, this classical mechanism of action cannot account for a variety of rapid effects of steroids (within seconds or minutes). In this review, non-genomic modes of target cell responses to sex steroids are described. The prototypical example is the resumption of meiosis in amphibian oocytes, triggered by progesterone at the plasma membrane level. Membrane effects of progesterone may also account for sperm maturation. Other membrane-mediated effects of steroids are reviewed. Whether a steroid hormone might elicit responses from a single cell through both genomic and membrane mechanisms remains an open question.