Distribution of 3β-hydroxysteroid dehydrogenase during development of the rat adrenal cortex and capsule

Abstract

Fibroblasts of the adult adrenal cortex are considered to be nonsteroidogenic connective-tissue cells. However, it has been reported that in response to regenerative stimuli, adrenocorticotropic hormone (ACTH), and transformation to malignancy, these cells acquire characteristics of parenchymal cells, which includes Δ5, 3β-hydroxysteroid-dehydrogenase (Δ5, 3β-HSD) activity. To determine whether such A5, 3β-HSD activity in adult adrenocortical fibroblasts was due to the activation or augmentation of gene expression normally occurring during embryogenesis, a histochemical study of adrenocortical development, with particular attention to the connective-tissue capsule, was undertaken. Cryostat sections of rat embryos, from 14-days postconception (PC) to birth, and of adrenal glands 1–8, 44 and 90 days after birth were tested histochemically for Δ5, 3β-HSD. The same or adjacent sections were stained for PAS-positive material and reticulin, and with hematoxylin and eosin. Δ 3β-HSD activity overlapped with fibro-blast-like cells and with extracellular connective-tissue components in the periphery of the glands from day-17 PC onward. Δ5, 3β-HSD activity over the capsule diminished shortly after birth and was absent in the adult. Appropriate controls showed that the staining within the capsule was specific and not an artifact. 3β-HSD activity in the capsule was more intensive when dehydroepiandrosterone (DHEA) was replaced by etiocholan-3β-ol-l7-one (ETIO) as the steroid substrate. Furthermore, the spatial distribution of 3β-HSD activity in the cortex differed depending on the substrate used, and the distribution patterns changed with developmental age. The results support the hypothesis that embryonic adrenocortical fibroblasts transiently express a steroidogenic phenotype which is reexpressed by adult cells in regeneration and malignancy. The variation in the distribution of 3β-dehydrogenatior1, depending on the substrate used, indicates that there are at least two enzymes that catalyze this step in developing steroidogenic organs.