On the in vitro metabolism of androstenedione and progesterone in human testicular tissue from fetal age to senescence.
The conversion of [3H]-androstenedione to testosterone regulated by the enzyme 17 beta-ketosteroid reductase and the conversion of [3H]-progesterone to 17 alpha-hydroxyprogesterone and onwards along the delta 4 metabolic pathway was studied in vitro in human testicular tissue from 32 males (2 fetuses, 25 adult, infertile men and 5 elderly men with prostatic carcinoma). Additionally, two prepubertal boys were studied with respect to the conversion of [3H]-androstenedione to testosterone in vitro, whereas another seven boys were studied with reference to the conversion of [3H]-progesterone in vitro. It appeared, that in all cases, the conversion of androstenedione to testosterone was larger than the conversion of progesterone to 17 alpha-hydroxyprogesterone by way of the 17 alpha-hydroxylase and onwards along the delta 4 metabolic pathway. It is thus concluded that the 17 beta ketosteroid reductase is not a rate-limiting enzyme along the delta 4 metabolic pathway. No case of deficient 17 beta-ketosteroid reductase was found among the 25 infertile patients studied.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D000735:Androstenedione / Q000378:metabolism*; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D005260:Female; D005333:Fetus / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011374:Progesterone / Q000378:metabolism*; D013737:Testis / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism
D013739:Testosterone; D000735:Androstenedione; D011374:Progesterone