Molecular Biology and Developmental Regulation of the Enzymes Involved in the Biosynthesis and Metabolism of Neurosteroids

Abstract

The synthesis of steroid hormones in the adrenal, gonad, and placenta, considered “classic” endocrine tissues, results from a series of enzymatic steps that involves both P450 and non-P450 enzymes. The tissue-specific expression of the different enzymes dictates which steroids will be synthesized. However, the initial steps in the synthesis of all steroids are common to all steroidogenic tissues. Recent demonstration of steroid synthesis in the brain suggests that these steroids may be synthesized using the same steroidogenic enzymes found in classic steroidogenic tissue. The cloning of cDNAs and genes for all the steroidogenic enzymes over the past decade has enabled investigators to establish unequivocally that the brain expresses the same steroidogenic genes as classic steroidogenic tissues. Furthermore, through the work of many investigators, it has been established that the genes encoding the steroidogenic enzymes are expressed in multiple species, from frogs to human beings, in a developmental, regional, and tissue-specific fashion in the central and peripheral nervous systems. Although the genes expressed in neural and in classic steroidogenic tissues may be the same, recent work indicates that the nuclear factors regulating the transcription of the genes for one steroidogenic enzyme are different in neural vs classic steroidogenic tissue.KeywordsP450 ReductaseSteroidogenic EnzymeHydroxy Steroid DehydrogenaseSteroidogenic TissueSteroid DehydrogenaseThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.