Progesterone receptor binding of steroidal and nonsteroidal compounds.

Abstract

Since the isolation of progesterone from the corpus luteum in early 1930s, the problem of how progesterone elicits its specific physiological effect, has attracted both chemists and endocrinologists. The tissues which respond dramatically to this hormone are termed as its target organs. The progestational activity of this hormone on the target organs has been assayed in vivo (Clauberg’s assay) and it depends on the manner of administration [1,2]. For example, progesterone, when administered orally, has a low activity [1], possibly because of the metabolic inactivation of the steroid in the gastro-intestinal tract. Clauberg’s assay [3–5] has received wide acceptance and for almost two decades, from late 1950s to mid 1970s measurement of progestational activity was based on this method of assay. The early efforts of chemists to discover the key points in the chemical structure of progesterone which are responsible for its physiological effect, are indeed based on Clauberg’s assay. In 1970, Milgrom and Baulieu [6] observed that a progesterone-binding macromolecule is present in cytosol fraction of rat uterus. The existence of a similar macromolecule binding specifically to progesterone and not binding to non-progestational compounds in the cytosol fraction of the uteri of rat, rabbit and guinea pig has been reported by other workers [7, 8] also.