[Mechanism of action of steroid hormones. I. Estrogens]

The steroid hormone are very versatile molecules: although they are related among them by their chemical structure, they have very diverse functions and including antagonic. Their action mechanism is not completely cleared. The estrogens participate in the regulation of practically all the reproductive and sexual events of the female, although the intracellular actions by which they take place are not well known and the proposed models do not adequately satisfy the questions. Currently it is accepted the existence of a cytoplasmic and/or nuclear receptor, without explaining satisfactorily how the hormones come to the nucleus. The endocrine events that are rapidly expressed (seconds) are due to a possible interaction with cellular membrane. The purpose of this review is to analyze and concilliate the reported data on the mechanism of action of estrogens.