Estrogen-induced proteins: A new class of regulatory substances

The discovery of estrogen-induced growth factors (estromedins) identified a missing link in understanding endocrine regulation. Estromedins are probably not on in vitro mitogens or auto-/paracrine growth regulators but play an important endocrine regulatory role. A review of the literature and our own previous in vivo endocrine experiments with uterus and uterine extracts support this concept. We have also discussed the effects of some other newly discovered endocrine regulators on the synthesis/release and peripheral action of gonadotropins and lactogens. We conclude that our view on endocrine regulation is fundamentally changing. In addition to the classical endocrine axis (hypothalamus-pituitary-peripheral tissue) several new factors and conditions have to be taken into consideration to understand the regulation of an endocrine effect on a target organ.