Biosynthesis of 16-androstene steroids and testosterone by porcine testis tissue in vitro: effect of age and relationships with fat 5 alpha-androstenone levels in vivo.

The relationships between testicular 16-androstene and testosterone formation in young pigs and levels of 5 alpha-androstenone in fat exhibited at older ages were investigated. Testis tissue samples were taken from Large White male pigs at 75, 100 and 125 days of age (8 pigs per age group) and incubated with a mixture of [3H]progesterone and [14C]pregnenolone. 5 alpha-androstenone levels in fat were measured in all 24 pigs at 125, 145 and 170 days of age. Less androstadienone, more 3 alpha-androstenol and 11-fold more 3 beta-androstenol + androstadienol were synthesized from pregnenolone than from progesterone. 5 alpha-androstenone synthesis increased significantly between 100 and 125 days, whereas that of androstadienone declined between 75 and 100 days of age. Litter had a significant effect on all 16-androstene rates of formation. Fat 5 alpha-androstenone levels were positively correlated with 5 alpha-androstenone formation from both precursors. They were correlated with 3 beta-androstenol + androstadienol (positively) and testosterone (negatively) rates of synthesis from progesterone. It is concluded that in vitro measurements of 5 alpha-androstenone formation by testis tissue could be used as an early predictor of fat 5 alpha-androstenone levels exhibited at older ages.