Influence of hCG treatment on the metabolism of progesterone and pregnenolone in vitro by the human undescended prepubertal testis.

Testicular biopsies were taken from 56 prepubertal and pubertal boys, aged 3-17 years, with undescended testes. The biopsies were incubated in vitro with 3H-progesterone or 3H-pregnenolone. Fifteen of the boys had been treated with human chorionic gonadotrophin (hCG) prior to operation. Nine boys were operated on within 1 week of the last injection of hCG while the others were operated on between 12 days and 2 years after hCG treatment. In non-treated prepubertal boys very small amounts of substrate were converted by means of the enzymes 3 beta-hydroxysteroid-dehydrogenase and 17 alpha-hydroxylase and virtually no testosterone was produced. Immediately after treatment with hCG there was a large increase in the conversion of substrate by 17 alpha-hydroxylase and 3 beta-hydroxysteroid-dehydrogenase. Considerable amounts of testosterone were formed, especially from pregnenolone, while smaller amounts were formed from progesterone. This suggests that testosterone production occurred primarily via the delta 5 pathway, at least beyond the 17 alpha-hydroxylase-step. Within 2 weeks of the last hCG injection, steroidogenic activity had decreased towards levels similar to those found in prepubertal testis from untreated boys. These observations indicate that hCG treatment of boys with undescended testes does not result in irreversible or even long-lasting stimulation of their steroidogenic function.