Developmental changes in steroidogenic enzymes in human postnatal adrenal cortex: immunohistochemical studies

OBJECTIVE Adrenarche is considered to occur as a result of intra-adrenal changes in steroidogenic enzymes involved in C-19 steroid production. The present study was conducted because developmental changes in steroidogenic enzymes have not been examined well in human postnatal adrenal. PATIENTS AND MEASUREMENTS Twenty-four specimens of nonpathological human adrenals from 7 months to 62 years retrieved from autopsy files. Immunohistochemistry for P450 side-chain cleavage (P450scc), 17 alpha hydroxylase (P450c17), dehydroepiandrosterone sulfotransferase (DHEA-ST), P450 oxidoreductase, cytochrome b5, and 3 beta -hydroxysteroid dehydrogenase (3 beta HSD) was performed in these specimens, and the immuno-intensity was evaluated using CAS 200 computed image analysis system. RESULTS Immunoreactivity of P450scc was marked in the tons glomerulosa, fasciculata and reticularis in the adrenal glands of all the cases examined. P450c17 and DHEA-ST immunoreactivity was weak in the zona fasciculata and reticularis in the adrenals of age 7 months to 5 years, but thereafter became prominent In the tons reticularis, Immunoreactivity of P450 oxidoreductase and cytochrome b5, components of the electron transfer system hypothesized to regulate the 17-20 lyase activity of P450c17, was weak in all three zones of adrenal cortex from 7 months to 5 years, and became more marked in the zona reticularis after age 5 years, 3 beta HSD immunoreactivity was marked in all three zones of the adrenal cortex from 7 months to 8 years but thereafter decreased in the zona reticularis, CONCLUSIONS These data suggest that the human adrenal zona reticularis markedly begins to develop morphologically and functionally at around 5 years of age. The increased level of P450c17, DHEA-ST, P450 oxidoreductase, and cytochrome b5, and the decreased level of 3 beta HSD in the reticularis is likely to contribute to increased C-19 steroid production during adrenarche.