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At least 19 recordsLinked to original sources
PubMed1979

Properties of rat adrenal zona reticularis cells: production and stimulation of certain steroids.

The outputs of corticosterone, deoxycorticosterone and androstenedione from dispersed, purified rat adrenal zona reticularis and zona fasciculata cells have been measured by radioimmunoassay. Preferential production of deoxycorticosterone by zona reticularis cells was demonstrated by their higher basal deoxycorticosterone : corticosterone ratio when compared with zona fasciculata cells. Adrencorticotrophin (ACTH) stimulated corticosterone output by all cell pools prepared by unit gravity (1 g) sedimentation, zona fasciculata cells being stimulated 130-fold compared with 20-fold for the zona reticularis cells in relation to their basal corticosterone output. In every cell pool, ACTH stimulated the output corticosterone more than it stimulated the output of deoxycorticosterone. In parallel cell preparations, it was shown that ACTH increased the conversion of tracer amounts of radioactive deoxycorticosterone to corticosterone and decreased the conversion of radioactive corticosterone to 11-dehydrocorticosterone. Adrenocorticotrophin did not increase the conversion of radioactive deoxycorticosterone to total 11-oxygenated steroids (corticosterone + 11-dehydrocorticosterone). It is unlikely therefore that ACTH stimulates 11 beta-hydroxylation. Data indicate that the ratio of deoxycorticosterone to total 11-oxygenated steroids (corticosterone + 11-dehydrocorticosterone) is characteristic for each cell type, and that this ratio will be relatively independent of ACTH stimulation or the amount of pregnenolone substrate available. Basal androstenedione outputs were similar for both types of cell, and ACTH stimulation was very small, being slightly greater for zona fasciculata than for zona reticularis cells. The contribution of the zona reticularis cells to the basal output of any steroid by the cells of the inner two zones of the adrenal cortex of the rat was relatively small (20% for deoxycorticosterone and 10% for corticosterone) and was even less after stimulation by ACTH. Unless a specific stimulus can be found, therefore, a significant role for the zona reticularis cannot yet be established.

Adrenal Glands↗
PubMed1978

Properties of rat adrenal zona reticularis cells: preparation by gravitational sedimentation.

An enriched fraction of zona reticularis cells was obtained by unit gravity sedimentation of decapsulated adrenal glands from female rats. From light microscopic and ultrastructural studies of the whole gland and the isolated cell fractions, the zona reticularis cells of the adrenal gland can be classified mainly on the bases of size, position and mitochondrial morphology. This cell population consists of two types of cell, the 'true' zoma reticularis cells (Type I, modal diameter 9 micrometer), which usually constitute 90% of the isolated reticularis fraction and 80% of the intact reticularis tissue, and cells (Type II, modal diameter 13 micrometer) with fasciculata-like properties (rich in lipid and spherical mitochondria with vesicular cristae). Staining of the cell preparation for 3beta-hydroxysteroid dehydrogenase activity also demonstrates the existence of two types of cell in the zona reticularis. The zona reticularis cell fraction, like the zona fasciculata cell fraction, was capable of producing the subsequent steroids from radioactive pregnenolone: corticosterone, deoxycorticosterone, 18-hydroxydeoxycorticosterone, 11-dehydrocorticosterone, progesterone and androstenedione. However, the pattern of steroid production differed markedly between the zona reticularis and zona fasciculata cells, particularly with respect to the production of deoxycorticosterone and corticosterone (and its correlated steroids, 11-dehydrocorticosterone and 18-hydroxydeoxycorticosterone). When R (the ratio of deoxycorticosterone : corticosterone plus 11-dehydrocorticosterone) for the purest preparation of reticularis cells was compared with R for the corresponding preparation of fasciculata cells, the normalized ratio was found to be 6.4, 16.4 and 20.1 in three experiments. The pattern of production of androstenedione per cell was similar in the reticularis and fasciculata cell fractions. The exact mechanism for the altered pattern of steroid metabolism remains to be elucidated. However, these results establish that the corticosteroids produced by the cells of the zona reticularis may be quantitatively, if not qualitatively, different from those produced by the zona fasciculata cells.

Adrenal Cortex↗
PubMed1975

Fat accumulation in tha adrenal gland: effect of oestradiol benzoate on the zona reticularis of the Mongolian gerbil adrenal gland.

Oestrogen promotes accumulation of abundant lipid droplets in the zona reticularis of the Mongolian gerbil. Lipid was observed in zona reticularis parenchymal cells but droplets were especially numerous in macrophages. Enlargement of lipid droplets was facilitated by an envelopment with lysosomal membranes. Focal areas or entire parenchymal cells may then undergo degeneration and necrosis and be incorporated into large macrophages recognizable by distinct areas of lipid-containing material as well as by small mitochondria with short cristae. Oestrogen may well act directly on zona reticularis cells inasmuch as nafoxidine, an antioestrogen, prevents these changes. Zona fasciculata cells were identical to those in controls and an intermediate region between the zona fasciculata and zona reticularis persists, although concentric whorls of rough endoplasmic reticulum seen in controls were replaced by disorganized, randomly dispersed cisternae of rough endoplasmic reticulum. Oestrogen does not elevate cortisol in the plasma.

Adrenal Cortex↗
PubMed1979

Effect of thyroparathyroidectomy (TPX) on the zona reticularis: a quantitative ultrastructural study.

Atrophy of zona reticularis cells was observed two weeks after surgical thyroparathyroidectomy (TPX). Quantitative morphological techniques for electron microscopy showed significant decreases in the volume of cytoplasm, nucleus, mitochondria, smooth endoplasmic reticulum and lipid droplets in the zona reticularis of TPX rats. In addition, many mitochnodria contained lipid droplets, some of which occupied virtually the entire matrix of mitochondria. The volume per cell of mitochondria with these inclusions increased significantly after TPX. The lipid droplets may well arise from cytoplasmic droplets by increased transport or reduced metabolism of cholesterol, or by direct incorporation of droplets into the mitochondrial matrix. The serum corticosterone level of TPX rats sacrificed under quiescent conditions did not differ significantly from that of controls. Hypothyroidism induced a significant increase in the volume of peroxisomes per cell in TPX animals which may be related to changes in lipid metabolism or transport.

Adrenal Cortex↗
PubMed1985

Opposed effects of chronic prolactin administration on the zona fasciculata and zona reticularis of the rat adrenal cortex: an ultrastructural stereological study.

The effects of a prolonged treatment with prolactin on the morphology and hormone secretion of rat adrenal zona fasciculata and zona reticularis, were investigated by coupled morphometric and radio-immunological techniques. Chronic prolactin administration provoked a notable atrophy of zona fasciculata cells and a small but significant increase in the corticosterone plasma level, which can be the result of the prolactin-induced inhibition of the intra-adrenal 5 alpha-reductase. Therefore, the atrophy of the zona fasciculata may be reasonably supposed to be not a direct effect of prolactin, but indirectly caused by a negative feed-back mechanism blocking ACTH release. On the contrary, prolonged prolactin treatment induced a conspicuous hypertrophy of zona reticularis cells, as well as a notable rise in the plasma concentration of testosterone, which cannot be due to gonad stimulation by prolactin since orchiectomized rats were employed. As the zona reticularis, like zona fasciculata, is ACTH-dependent, it must be concluded that prolactin exerts a direct stimulating effect on the growth of the zona reticularis, whose functional counterpart conceivably is an enhanced production of androgen hormones.

Adrenal Cortex↗
PubMed1983

Aging and the human zona reticularis.

Adrenal androgen levels and excretion increase during adrenarche and puberty. During this time the width of the adrenal zona reticularis has been reported to increase, and this fact is quoted as evidence for the common assumption that the major source of adrenal androgens is the zona reticularis. During human aging there is a marked decrease in adrenal androgen levels and excretion. In the present study, the width of the zona reticularis was studied single blind in multiple sections of the adrenals of 42 victims of sudden death 4 months to 93 years of age to discern a possible correlation between zona reticularis width and the declining adrenal androgen levels and excretion typical of aging. However, no correlation was found, which suggests that direct measurements of adrenal steroid secretion by the individual adrenal zones are necessary for the study of adrenal zonation.

Adolescent↗
PubMed1979

Zona reticularis in aging spontaneously hypertensive rats: a quantitative ultrastructural study of 70- and 95-week-old animals.

The zona reticularis of 70- and 95-week-old female Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) rats was studied by quantitative stereologic techniques. The zona reticularis in the adrenal gland of 70-week-old SH rats was virtually identical to that of 70-week-old WKY rats. In both SH and WKY rats at 95 weeks of age, however, there was hypertrophy of smooth endoplasmic reticulum reflected quantitatively in increased volume and surface area, as compared with that of WKY rats or SH rats at 70 weeks of age. Ninety-five-week-old WKY rats had a significantly greater mitochondrial volume/cell and surface area of mitochondrial membranes than SH rats. Inclusion of lipid droplets within mitochondria was seen in zona reticularis cells from SH and WKY rats at 70 weeks of age; mitochondria-lipid-droplet association was more frequent at 95 weeks of age. The volume of lipofuscin per cell was significantly greater in WKY than in SH rats at 95 weeks of age. Thus, by quantitative techniques, one can see that the zona reticularis of 95-week-old SH rats differs from that of WKY rats, principally in the presence of smaller cells with a smaller surface area of mitochondrial cristae and a reduced volume of mitochondria, lipofuscin, and lipid droplets.

Adrenal Cortex↗
PubMed1976

Effect of ACTH on the zona reticularis of the rat adrenal cortex: an ultrastructural stereologic study.

The effects of ACTH on the rat adrenal zona reticularis were investigated by stereologic methods. It was found that the zona reticularis cell responsiveness to ACTH is similar to that of the zona fasciculata elements. This excludes that the zona reticularis of the adult rat can only function as the site of destruction of worn-out elements migrating from the adrenal outer zones.

Adrenal Cortex↗
PubMed2001

Differentially expressed genes in zona reticularis cells of the human adrenal cortex.

The zona reticularis (ZR) cell in the human adrenal cortex is responsible for the secretion of dehydroepiandrosterone, but its biology, origin, and putative decrease in number during aging are poorly understood. In the present experiments, we investigated to what extent ZR and zona fasciculata (ZF) cells differ in patterns of gene expression. Both cell types were purified by microdissection from adult adrenal cortex specimens. After a brief period in culture, RNA was harvested from the cells and used to prepare radioactively labeled probes following amplification by PCR. Probes were used in hybridizations of arrays of cDNAs on nylon membranes (PCR products or plasmids obtained from an adrenal cDNA library). Analysis of hybridization intensities showed that 17 of the 750 genes studied differed in expression by more than 2-fold. Several genes expressed at higher levels in ZR cells encode components of the major histocompatibility complex or enzymes involved in peroxide metabolism. Members of the tubulin gene family were expressed at higher levels in ZF cells. Differential expression of four of the genes was confirmed by Northern blotting. These differences show that although ZR and ZF cells are similar in gene expression, ZR cells have a gene expression pattern related to the unique biology of this cell type.

Adult↗
PubMed1983

Steroid biosynthesis by zona fasciculata and zona reticularis cells purified from the mammalian adrenal cortex.

Steroidogenesis by zona reticularis (ZR) and zona fasciculata (ZF) cells from guinea-pig, macaque and human adrenals has been examined to establish the relative importance of the two cell types in the production of adrenal androgens. Microdissection and equilibrium density sedimentation of enzymically dispersed cells on Percoll gradients have been used to separate the two cell types with varying degrees of purity. Outputs of androstenedione and cortisol were measured for all the species studied and dehydroepiandrosterone sulphate (DHAS) for human adrenal cells. In all three species, the ZF cells produced more cortisol than the ZR cells. This production was stimulated to a greater extent in the ZF than the ZR cells in the guinea-pig, but to a similar extent in the macaque and human cells. Outputs of androstenedione were greater for ZF cells than ZR cells in the guinea-pig both basally and in response to an ACTH stimulus but basal production of this androgen was slightly greater from the ZR than the ZF in tissue incubations (1.6-fold), although cortisol output was still higher for ZF tissue by a factor of 2. Examination of androstenedione/cortisol ratios for all the species, both tissue and cells and in the presence or absence of ACTH, demonstrated clearly the inherent bias for ZR cells towards androgen synthesis by the fact that this ratio was always higher for ZR than for ZF cells or tissue. The most marked difference in this ratio was found in the human cells comparing the purest ZR and the purest ZF cell preparations even though the highest estimated purity of either cell type was only 80%. The difference in the ratio DHAS/cortisol was even greater comparing these human ZR and ZF cell preparations, ranging from 18- to 44-fold basally and in response to ACTH. The preliminary experiment on human adrenal cells indicates that the ZR cells are much more important than the ZF cells in the production of androgens even in the presence of ACTH, in contrast to the other species studied.

Adrenal Cortex↗
PubMed1990

The response of rat adrenal zona fasciculata and zona reticularis to oxytocin treatment.

The response of the adrenal zona fasciculata (ZF) and zona reticularis (ZR) to oxytocin (OT) was examined in male rats using a stereological method. The 10-day administration of 0.25 IU OT/100 g daily caused an enlargement of ZF due to cell hypertrophy associated with striking lipid accumulation. The volume of ZR was decreased, this change being the consequence of the reduced cell population. The possible site of OT action is discussed.

Adrenal Glands↗
PubMed1982

delta 4-Hydrogenase in guinea pig adrenal: evidence of localization in zona reticularis and age-related change.

The guinea pig adrenal increases in the size with age, yet cortisol secretion per gram adrenal declines. It has been suggested that this could be due to catabolism of cortisol by increased adrenal delta 4-hydrogenase. In this paper we show that delta 4-hydrogenase is localized in the zona reticularis and increases coincidently with the large increase in the volume of this zone with age. Glands were microdissected to give inner vs. outer cortices, and the postmitochondrial supernatants of these two portions were assayed for delta 4-hydrogenase activity. The enzyme was found almost solely in preparations from inner cortices, which were predominantly zona reticularis. Cells were isolated from each portion and assayed for delta 4-hydrogenase activity. Again, only those which contained zona reticularis cells, that is, those from the inner cortices, had activity. The activity was shown to be present in both microsomes and cytosol, although the latter was preferentially expressed in a 15,000 X g supernatant. When the metabolites were separated by thin layer chromatography, the products of the microsomal enzyme were 5 alpha- and 5 beta-dihydrocortisol (1:1) and that of the cytosolic enzyme was 5 beta-dihydrocortisol, whereas in the 15,000 X g supernatant the 5 beta-isomer was the predominant product. Its identity as 5 beta-dihydrocortisol was confirmed by mass spectroscopy. Tetrahydrocortisol comprised a minor portion of the products.

Adrenal Cortex↗
PubMed1976

Investigations on the turnover of adrenocortical mitochondria. IV. A stereological study of the effect of chronic treatment with ACTH on the size and number of rat zona reticularis mitochondria.

The effects of chronic administration of of ACTH (up to 36 consecutive days) on the mitochondria of the zona reticularis of the rat adrenal cortex were investigated by stereologic techniques. It was found that ACTH induces two phases of hypertrophy of mitochondria alternating with two proliferative stages, which are associated with a significant decrease in the average volume of the organelles. It is suggested that, as in the zona fasciculata, ACTH controls the processes of growth and division of mitochondria in the zona reticularis. The mechanism underlying this action of ACTH as well as the differences between the responses to ACTH of the mitochondrial population of the two adrenal zones are discussed in the light of evidence indicating that mitochondria contain a complete genetic apparatus largely independent of nuclear control.

Adrenal Cortex↗
PubMed1996

The zona reticularis is the site of biosynthesis of dehydroepiandrosterone and dehydroepiandrosterone sulfate in the adult human adrenal cortex resulting from its low expression of 3 beta-hydroxysteroid dehydrogenase.

Based on indirect evidence, it has often been assumed that the zona reticularis of the adult human adrenal cortex is the source of the adrenal androgens, dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS), but direct tests of this concept have been few. Using the techniques of cell culture, Northern blotting, and RIA, we compared the properties of separated adult zonal cells to those of fetal zone cells, a cell type well known to secrete large amounts of DHEA(S) due to its low expression of 3 beta-hydroxysteroid dehydrogenase (3 beta HSD). In nine glands from donors of a wide age range, the zona fasciculata and zona reticularis were separated and dissociated, and the cells were placed in culture. After 5 days, serum was removed by a 24-h period in serum-free defined medium followed by a 24-h exposure to cAMP analogs, with the optional addition of insulin, also in serum-free medium. The separated fasciculata and reticularis cells showed large differences in the DHEA(S)/cortisol (F) production ratios from added pregnenolone precursor, consistent with the synthesis of only F and essentially no DHEA(S) by fasciculata cells and with the synthesis of mostly DHEA(S) with little or no F by both reticularis cells and fetal zone cells. The different patterns of steroidogenesis were accompanied by a much lower level of expression of type II 3 beta HSD in reticularis cells, similar to that in fetal zone cells. In contrast, other genes were similarly regulated in the two adult zones and in the fetal zone by both cAMP and insulin. The levels of messenger ribonucleic acids for 17 alpha-hydroxylase, cholesterol side-chain cleavage enzyme, 21-hydroxylase, and 11 beta-hydroxylase responded to cAMP and insulin in both reticularis cells and fetal zone cells in the same pattern as that previously established in fasciculata cells. The central role of the limited expression of 3 beta HSD in the DHEA(S)-synthesizing property of reticularis cells was established by inhibition of 3 beta HSD in fasciculata cells with trilostane, which caused them to increase their DHEA/F production ratio to a level exceeding even that in fetal zone cells. There did not appear to any age-related changes in gene expression that could account for the large age-related decline in DHEA(S) biosynthesis in humans in either reticularis or fasciculata cells. Thus, the most likely cause of the age-related decline in adrenal androgen biosynthesis is an age-related decline in the number of functional reticularis cells, without a major change in the differentiated properties of the zonal cells as a function of age.

3-Hydroxysteroid Dehydrogenases↗
PubMed2004

Is reduced cell size the mechanism for shrinkage of the adrenal zona reticularis in aging?

In aging humans, corticosteroid production is preserved, or even increased, but there is an unexplained reduction in adrenal androgen secretion that likely has significant health implications. Preliminary analyses on adrenocortical morphology have revealed an age-associated reduction in the thickness of the zona reticularis (ZR), the cortical zone responsible for the majority of DHEA/DHEA sulfate production in the adult human, but no change in the overall thickness of the adrenal cortex. The ZR width could decrease in aging due to loss of ZR cells and/or to shrinkage of ZR cells. In the current study, we investigated whether there was a relation between thickness of the zona reticularis in young and old humans and the cell density in this zone. Paraffin-embedded sections of the adrenal cortex of 10 young (21-35 yr old) and 10 old (54-89 yr old) adults who had died suddenly as the result of trauma were stained with hematoxylin and eosin. These specimens were chosen from a larger cohort of samples for having a broad ZR in the young group and a narrower ZR in the older group. After determining the overall cortical thickness and the width of the ZR by use of computerized image analysis software, we counted the number of adrenocortical cells in two random high power fields of the ZR of each specimen. The ZR width of the older group (57 +/- 7 arbitrary units, Mean +/- SE) was significantly reduced compared to that of the young group (124 +/- 21), P < 0.001. On the other hand, the overall cortical width in the old group (232 +/- 17) was similar to that of the young adults (249 +/- 38). In the old group, the ZR comprised 24.7 +/- 3% of the total cortical width, whereas it was 50 +/- 2% of the cortical width in the young adrenals, P < 0.001. The cell density (cell number/60 x high power field) of the ZR of old adults (83 +/- 9) was similar to that of the young group (87 +/- 5). In summary, although the width of the ZR regresses with aging, cell size in this zone is preserved. Therefore, loss of trophic support for ZR cells would not appear to be the explanation for zonal shrinkage in aging. Rather, it is likely that aging effects may be due to increased cell loss in the ZR or else reduced rates of differentiation/migration of cells into this cortical zone.

Adult↗
PubMed1999

Lymphocytes stimulate dehydroepiandrosterone production through direct cellular contact with adrenal zona reticularis cells: a novel mechanism of immune-endocrine interaction.

Adrenal androgen production was reduced by 80% in patients receiving T lymphocyte-suppressive medications compared to that in age-matched controls. In vitro, however, neither tacrolimus nor cyclosporin A reduced dehydroepiandrosterone (DHEA) release by adrenocortical cells. Therefore, we examined the potential role of lymphocytes in adrenal androgen production, using cocultures of human T lymphocytes and adrenocortical primary or transformed cells. Co-cultures led to a 4-fold elevation of DHEA levels (490.4 +/- 94.8% over basal), which was greater than the increase observed after the addition of maximal concentrations of ACTH (117.4 +/- 14.8%). Separation of cells by semipermeable membranes abolished this effect, and transfer of leukocyte-conditioned medium had little androgen-stimulating effect. These data suggested that the observed stimulation of androgen secretion required cell contact rather than soluble paracrine factor(s). Furthermore, we examined human adrenal glands for the presence of T lymphocytes and contact between these cells and steroid-secreting cells of the zona reticularis. Indeed, T lymphocytes expressing CD4 and CD8 antigens were present within human adrenal zona reticularis by immunohistochemical subtyping. Electron microscopic analyses demonstrated direct cell-cell contact between T lymphocytes and adrenocortical cells in situ. This study provides evidence for a novel mechanism of immune-endocrine interactions of direct T lymphocyte-adrenocortical cell contact-mediated stimulation of adrenal androgen secretion.

Adrenocorticotropic Hormone↗
PubMed1984

Histochemical studies on the zona reticularis of stress-susceptible pigs.

During an investigation into the role of the adrenal gland in stress susceptibility of pigs, the large lipid masses in the inner zona reticularis were seen to be particularly related to sex differences, although stress-susceptible castrates had significantly more lipid in this zone than had stress-resistant castrates. Significant histochemical differences were also found in the activity of glucose-6-phosphate dehydrogenase and succinic dehydrogenase between the sexes and between castrates of differing susceptibility to stress. The differences in histochemical activity suggest a different origin for some of the adrenocortical cells in the inner zona reticularis.

Adrenal Cortex↗