Local Control of Steroid Hormone Biosynthesis

textabstractSteroids are essential for vertebrate physiology during pre- and postnatal life. Whereas the skeleton structure of cyclopenta[α]phenanthrene rings is common to all steroid molecules, differences occur in methyl- of ethylgroups attached to the four rings or the oxidation state of the carbon atoms in the rings (Figure 1).1 Endogenous production of steroids is realized in steroidogenic tissues. From these tissues, steroid molecules can be secreted into the circulation to act in an endocrine fashion. By binding to receptors in target tissues they manipulate gene transcription, influencing a wide variety of cellular functions. Steroids can also exert local effects in the steroidogenic tissues after secretion into the extracellular space (paracrine or autocrine) or directly within the cell in which they are produced (intracrine).