A novel cell layer without corticosteroid-synthesizing enzymes in rat adrenal cortex: histochemical detection and possible physiological role

Abstract

A stratum of cells that did not contain both aldosterone synthase cytochrome P450 (cytochrome P450aldo) and cytochrome P45011 beta was found immunohistochemically between the zona glomerulosa and the zona fasciculata of the rat adrenal cortex. As cytochromes P450aldo and P45011 beta are the enzymes responsible for the biosynthesis of aldosterone and corticosterone, respectively, the cells there are considered to be incapable of synthesizing both aldosterone and corticosterone. Furthermore, the cells are regarded as inert in producing adrenal androgens, because rat adrenal cortex is known to lack steroid 17 alpha-hydroxylase. Thus, the stratum is composed of cells that do not synthesize any of the major corticosteroids in significant quantities. It was 5-10 cells thick under normal feeding conditions, but diminished to 4-5 cells thick when animals were maintained under Na restriction, which is known to stimulate the secretion of angiotensin-II. When the distribution of 5-bromo-2'-deoxyuridine-labeled nuclei in the adrenocortex from BrdU-administered rats was examined, the stained nuclei were concentrated in and around the cell stratum. The pulse-chase experiments showed that the labeled cells migrated out of this layer and into the zonae fasciculata-reticularis. On the basis of these findings, we suggest that the newly discovered cell layer is the progenitor cell zone of the rat adrenal cortex.

Gap junction proteins and cell-cell communication in the three functional zones of the adrenal gland

“…Bertholet 1980, Zajicek et al 1986. A functional transition zone has been described in the rat adrenal gland in which cells differ both morphologically and physiologically from either zona fasciculata or zona glomerulosa cell type (Mitani et al 1994). Certainly, if such a migration does occur a transition zone should exist in which both, or neither, zona glomerulosa and zona fasciculata type cells would be found.…”

Central effects of ghrelin on the adrenal cortex: a morphological and hormonal study

“…It is widely accepted that for functional purposes, zonation of the rat adrenal cortex can be separated into the ZG and ZF/ZR. This differentiation is associated with the exclusive presence of aldosterone synthase (CYP11B2) in the glomerulosa whereas 11β-hydroxylase (CYP11B1) is exclusively present in the rat ZF/ZR (Ogishima et al 1992;Mitani et al 1994). Enzymes that catalyze those steroidogenic pathways are biochemically essential to partitioning mineralocorticoid-active steroids of the glomerulosa from the glucocorticoid-producing steroids of the inner zones (Vinson 2003).…”

GH-receptor distribution in the ovine foetal adrenal gland: ontogenic and functional studies

“…Although the GH-receptor was present throughout the adrenocortical region, as seen in the foetal adrenal, a relatively higher level of gene and protein expression was confined to a distinct region at the interface of the zona glomerulosa and zona fasciculata. Studies in the adult rat have identified a novel cell layer devoid of both mineralocorticoid-and glucocorticoid-synthesizing enzymes between the zona glomerulosa and zona fasciculata, which is believed to be the progenitor cell zone of the rat adrenal cortex (Mitani et al 1994). A thin layer of cells (which may be analogous to the progenitor zone of the rat adrenal) has also been identified between the zona glomerulosa and zona fasciculata of the adult sheep adrenal cortex (McDougall et al 1980), the so called 'intermediate cells' of this zone possessing unique cellular morphology intermediate between typical zona glomerulosa and zona fasciculata cells.…”