Ontogeny of 3 beta-hydroxysteroid dehydrogenase expression in the rat adrenal gland as studied by immunohistochemistry.

The enzyme 3 beta-hydroxysteroid dehydrogenase plays a crucial role in the steroidogenic process in the adrenal gland. In the present study we tried t o characterize its localization and developmental changes in the rat adrena l cortex during the postnatal period, using immunohistochemical methods. Th e development of the different zones evidenced specific particularities: th e zona glomerulosa almost lacked 3 beta-HSD in the first days after birth; then, 3 beta-HSD increased, attaining a maximum around day 20 and afterward s it decreased again and remained less intense than the neighbouring zona f asciculata up until adulthood (65 days of age). The zona fasciculata was al ready intensely stained at birth and the expression of 3 beta-HSD increased rapidly reaching a maximum after 2 weeks of life and that level was mainta ined from then on. The inner part of the zona fasciculata and the zona reti cularis both pf which develop postnatally were faintly immunostained before day 20. The expression of 3 beta-HSD increased after that age to become ap proximately as intense as in the outer zona fasciculata and so remaining un til day 90. The development of the zona glomerulosa was parallel to the sec retion of aldosterone. The same did not occur with the zona fasciculata as the intensity of staining during the first 14 postnatal days was accompanie d by very low levels of corticosterone.