ABSTRACT
The purpose of this chapter is to introduce the process of steroidogenesis and describe the numerous aspects underlying physiologic control of steroidogenesis in different tissues and species. Rather than focus in detail on any one enzyme or aspect of steroidogenesis, our aim here is to emphasize that control of steroidogenesis can occur at many steps including enzyme levels, subcellular localization, cholesterol transport, relative substrate preferences, accessory proteins, control of electron supply, phosphorylation and selective inhibition by soluble gases. In particular, we assert that the concept of a single rate limiting step in steroidogenesis is hard to support and indeed any such rate limiting step so identified in vivo may quickly change with altered physiologic state. Finally, we attempt to place in context the lessons learned from knockout models, pregnancy and parturition. The goal is to leave the reader with a more complete understanding of how steroidogenesis as a whole is a finely controlled integrated process but at the same time is adaptable to a wide variety of different physiologic needs.
