Steroid metabolism in foetal tissues—IV conversion of testosterone to 5α-dihydrotestosterone in human foetal brain

Abstract

This study reports the measurement of the conversion of testosterone to 5α-dihydrotestosterone by a double isotope method in vitro in hypothalamic and cerebral tissue of 23 human foetuses age 12–26 weeks of gestation. The following percentages of conversion by 100 mg of tissue were found: male hypothalamus 4.36% ± 0.77 (SEM) n = 13, male cerebrum 1.36% ± 0.27 (SEM) n = 13; female hypothalamus 3.73% ± 0.82 (SEM) n = 10, female cerebrum 1.90% ± 0.48 (SEM) n = 10. These data indicate that 5α-dihydrotestosterone formation in the brain of the human foetus is regionally different with higher conversion in the hypothalamus than in the cerebrum. These differences are statistically significant. A correlation between 5α-reductase activity in the human foetal male hypothalamus and cerebrum was found. The data are discussed in relation to the development of the neuroendocrine functions in the human foetal brain.