Abstract
The ability of human spermatozoa to metabolize pregnenolone to progesterone and progesterone to testosterone was assessed. Sonicated specimens of freshly ejaculated sperm from two groups of husbands (n= 6, age 32–38 years; n= 6, age 30–51 years) of infertile couples in the range of sperm concentration between 237.5 and 568.5, 100.1 and 248.8 millions per ejaculate, were separately incubated with [7n-3H]pregnenolone and [1,2,6,7,16,17-3H]progesterone. Using the classical reverse-isotope dilution technique the desired products [3H]progesterone and [3]testosterone formed from the respective substrates were isolated and characterized, yielding 1.4 to 12.2% and 3.1 × 10−2to 2.0 × 101%. Such metabolites were not evident in the controls. The results indicate that the human spermatozoa contain the enzymes necessary for the transformation of pregnenolone to testosterone via the Δ4-3-keto route.