Characterization of a Δ⁵-3β-Hydroxy Pathway of Testosterone Synthesis in the Human Spermatozoa

Abstract

Sonicated specimens of freshly ejaculated sperm from two groups of husbands (n = 6, age 32–38 years; n = 7, age 27–38 years) of infertile couples in the range of sperm concentration between 237.5 and 568.5; 131.1 and 256.7 millions per ejaculate were separately incubated with [7n⁻³H]pregnenolone and [1,2,6,7- ³H]dehydroepiandrosterone. Using the reverse-isotope dilution technique [³H]dehydro-epiandrosterone and [³H]testosterone formed from the respective substrates were isolated and characterized, yielding 1.2 × 10⁻² to 4.6 × 10⁻²% and 7.1 × 10⁻² to 2.5 × 10⁻¹%. Such metabolites were not evident in the controls. These results provide evidence for metabolic transformation of pregnenolone to testosterone via the Δ5–3β-hydroxy route.

Key Words:

• dehydroepiandrosterone
• human spermatozoa
• male infertility
• testosterone
• testosterone synthesis
• 3β-hydroxysteroid dehydrogenase-5
• 4-ene isomerase
• 17α-hydroxylase
• 17β-hydroxysteroid oxidoreductase