Testicular Steroidogenesis

Abstract

Testosterone is the major androgen in circulation in male humans, produced primarily in the Leydig cells of the testis. Biosynthesis of testosterone from cholesterol occurs via a series of enzymatic reactions. Testosterone may be further metabolized into a more potent androgen, dihydrotestosterone. In recent years an alternate pathway of dihydrotestosterone biosynthesis without using testosterone as a precursor has emerged. Majority of classically studied effects of androgens are thought to be mediated via nuclear receptor-dependent long-term transcriptional effects, but there also exist membrane receptor-based effects of androgens which are being uncovered from recent studies that may explain rapid effects of androgens in many cases. In this chapter we are describing the biosynthesis, mechanism of action, and therapeutic effects of testosterone and related androgens.