Basal Steroidogenic Activity of Adrenocortical Cells Is Increased 10-Fold by Coculture with Chromaffin Cells*

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419

261

Obesity has become an epidemic problem in western societies, contributing to metabolic diseases, hypertension, and cardiovascular disease. Overweight and obesity are frequently associated with increased plasma levels of aldosterone. Recent evidence suggests that human fat is a highly active endocrine tissue. Therefore, we tested the hypothesis that adipocyte secretory products directly stimulate adrenocortical aldosterone secretion. Secretory products from isolated human adipocytes strongly stimulated steroidogenesis in human adrenocortical cells (NCI-H295R) with a predominant effect on mineralocorticoid secretion. Aldosterone secretion increased 7-fold during 24 h of incubation. This stimulation was comparable to maximal stimulation of these cells with forskolin (2 ؋ 10 ؊5 M). On the molecular level, there was a 10-fold increase in the expression of steroid acute regulatory peptide mRNA. This effect was independent of adipose angiotensin II as revealed by the stimulatory effect of fat cell-conditioned medium even in the presence of the angiotensin type 1 receptor antagonist, valsartan. None of the recently defined adipocytokines accounted for the effect. Mineralocorticoid-stimulating activity was heat sensitive and could be blunted by heating fat cell-conditioned medium to 99°C. Centrifugal filtration based on molecular mass revealed at least two releasing factors: a heat sensitive fraction (molecular mass >50 kDa) representing 60% of total activity, and an inactive fraction (molecular mass <50 kDa). However, the recovery rate increased to 92% when combining these two fractions, indicating the interaction of at least two factors. In conclusion, human adipocytes secrete potent mineralocorticoidreleasing factors, suggesting a direct link between obesity and hypertension.

Section: Discussionmentioning

confidence: 99%

Human adipocytes secrete mineralocorticoid-releasing factors

Ehrhart‐Bornstein

Lamounier-Zepter²,

Schraven³

et al. 2003

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419

261

“…For these experiments, cortical cells were incubated with the above described adenoviral mutants or purified viral capsids in 24-well plates for 24 h. After this procedure, plates were gently washed with serum-free medium, fresh culture medium was added, and cells were cultivated for 3 more days. Cells were then incubated in serumfree medium containing 5 ϫ 10 Ϫ3 M ascorbic acid, 0.001% wt͞vol transferrin, and 0.01% wt͞vol bacitracin (23,24) in the absence (basal steroidogenesis) or presence (stimulated steroidogenesis) of different concentrations of ACTH (from 10 Ϫ10 M to 10 Ϫ8 M). After 24 h, supernatants were collected and cortical cells were lysed in 0.1% Triton X-100.…”

Section: Cell Proliferation Cell Proliferation Was Assayed By [mentioning

confidence: 99%

“…Therefore, we transduced bovine adrenal cortical cells (BACCs) in primary culture with different adenoviral deletion mutants and studied their effect on cell morphology, ultrastructure, proliferation, and steroidogenesis under both basal and corticotropin (ACTH)-stimulated conditions. isolated as described (23,24). Briefly, adrenals were submerged in 70% ethanol for 10 sec and freed of fat and connective tissue.…”

mentioning

confidence: 99%

Adenoviral vectors can impair adrenocortical steroidogenesis: Clinical implications for natural infections and gene therapy

Alesci

Ramsey

Bornstein

et al. 2002

Recombinant adenoviral vectors are effective in transferring foreign genes to a variety of cells and tissue types, both in vitro and in vivo. However, during the gene transfer, they may alter the principal function and local environment of transfected cells. Increasing evidence exists for a selective adrenotropism of adenovirus during infections and gene transfer. Therefore, using bovine adrenocortical cells in primary culture, we analyzed the influence of different adenoviral deletion mutants on cell morphology and physiology. Transfection of cells with an E1͞E3-deleted adenoviral vector, engineered to express a modified form of the Aequorea victoria green fluorescent protein, was highly efficient, as documented by fluorescent microscopy. Ultrastructural analysis, however, demonstrated nuclear fragmentation and mitochondrial alterations in addition to intranuclear viral particles. Basal secretion of 17-OH-progesterone, 11-deoxycortisol, and cortisol was significantly increased by E1͞E3-deleted vectors; yet, the corticotropinstimulated release of these steroids was decreased. Interestingly, neither purified viral capsids nor E3͞E4-deleted adenoviral mutants altered basal and stimulated steroidogenesis of adrenocortical cells. An intact adrenal response is crucial for adaptation to stress and survival. Therefore, the implications of our findings need to be considered in patients with adenoviral infections and those undergoing clinical studies using adenoviral gene transfer. At the same time, the high level of transfection in adrenocortical cells might make appropriately modified adenoviral vectors suitable for gene therapy of adrenocortical carcinomas with poor prognosis.

“…Conversely, catecholamines and neuropeptides produced by the adrenal medulla regulate adrenocortical steroidogenesis (1,(9)(10)(11). Data supporting the notion of reciprocal control are as follows: basal cortisol production is 10 times higher in bovine adrenocortical cells cocultured with chromaffin cells than in cultures of pure adrenocortical cells (12). Therefore this interaction is of relevance to the capacity of the cortex to produce glucocorticoids.…”

mentioning

confidence: 94%

Deletion of tyrosine hydroxylase gene reveals functional interdependence of adrenocortical and chromaffin cell system in vivo

Bornstein

Tian

Haidan

et al. 2000

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Catecholamines are produced in the medulla of the adrenal gland and may participate in the intraglandular regulation of its cortex. We analyzed the adrenal structure and function of albino tyrosine hydroxylase-null (TH-null) mice that are deficient in adrenal catecholamine production. Adrenal catecholamines were markedly reduced, and catecholamine histofluorescence was abrogated in 15-day-old TH-null mice. Chromaffin cell structure was strikingly altered at the ultrastructural level with a depletion of chromaffin vesicles and an increase in rough endoplasmic reticulum compared with wild-type mice. Remaining chromaffin vesicles lined up proximally to the cell membrane in preparation for exocytosis providing a ''string-ofpearls'' appearance. There was a 5-fold increase in the expression of proenkephalin mRNA (502.8 ؎ 142% vs. 100 ؎ 17.5%, P ‫؍‬ 0.016) and a 2-fold increase in the expression of neuropeptide Y (213.4 ؎ 41.2% vs. 100 ؎ 59.9%, P ‫؍‬ 0.014) in the TH-null animals as determined by quantitative TaqMan (Perkin-Elmer) PCR. Accordingly, immunofluorescence for met-enkephalin and neuropeptide tyrosine in these animals was strongly enhanced. The expression of phenylethanolamine N-methyl transferase and chromogranin B mRNA was similar in TH-null and wild-type mice. In TH-null mice, adrenocortical cells were characterized by an increase in liposomes and by tubular mitochondria with reduced internal membranes, suggesting a hypofunctional state of these steroid-producing cells. In accordance with these findings, plasma corticosterone levels were decreased. Plasma ACTH levels were not significantly different in TH-null mice. In conclusion, both the adrenomedullary and adrenocortical systems demonstrate structural and functional changes in catecholaminedeficient TH-null mice, underscoring the great importance of the functional interdependence of these systems in vivo.