摘要:

Usingin situhybridisation we show that, in the rat adrenal. 11β-hydroxylase is confined to the inner zones, whereas aldosterone synthase is expressed exclusively in the glomerulosa. Immunoblotting methods identify an 18-hydroxydeoxycorticosterone (18-OH-DOC) in IEF gels of solubilised inner adrenocortical zone membrane preparations. This steroid, which can also be identified by immunocytochemistry, cannot be solvent extracted from the IEF gels unless the gel slices are first treated with trypsin. Preincubation of viable whole glandular tissue with trypsin significantly enhances aldosterone output, and eliminates the trypsin releasable 18-OH-DOC pool in IEF gels.The data suggest that 18-OH-DOC is synthesised and sequestered in inner zone cells, in a novel non-solvent extractable manner, but can be mobilised for utilisation as an aldosterone precursor in the glomerulosa.

ISSN:0743-5800    

DOI:10.3109/07435809509030416

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

Sympathoadrenal regulation of adrenocortical steroidogenesis was studied on a physiological, cellular, molecular and morphological level. The effects of nerve activation and of epinephrine (EPI) on adrenal corticosteroid release were compared in isolated perfused pig adrenals with preserved nerve supply. Splanchnic nerve activation as well as perfusion with EPI provoked a siginificant release of cortisol, aldosterone and androstenedione. In cultured bovine adrenocortical cells steroid secretion and accumulation of P450SCC, P45017α, P450c21and P45011βmRNAs were studied after stimulation with EPI with or without propranolol or phentolamine. Incubation with EPI stimulated steroidogenesis and increased the levels of all four P450-mRNAs. Theβ-adrenergic antagonist propranolol totally blocked the effects of EPI while theα-antagonist phentolamine had no effect. Using immunohistochemistry, adrenals were studied morphologically. The contact zones of the two cell types were investigated on an electron microscopical level. Cortical and medullary cells were closely interwoven with cortical and chromaffin cells in direct apposition, providing the possibility for paracrine interactions. It is concluded that the release of corticosteroids can be stimulated through the sympatho-adrenal system. The stimulatory action of EPI upon adrenal steroid formation and accumulation of all four P450-mRNAs requires C-adrenergic receptors. Taking into consideration the close colocalization of cortical and medullary tissue, this stimulation may be mediated by chromaffin cells in a paracrine manner.

ISSN:0743-5800    

DOI:10.3109/07435809509030417

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

The aim of these studies was to determine the intraadrenal mechanism of interleukin-1 (IL-1)-induced corticosterone release from the rat adrenal gland. To accomplish this, the role of catecholamines and eicosanoids on IL-1-induced corticosterone release was determined. Experiments were conducted on primary cultures of dispersed rat adrenal cells. Dose-dependent increases (P<0.05) in corticosterone concentration were observed when primary adrenal cells were incubated with different doses (10−10to 10−8M) of IL-1α. CL-1αand IL-1βelevated corticosterone release after a 24 hr incubation period. ACTH elevated corticosterone levels at 4 and 24 hr. The stimulatory effect of IL-1 on corticosterone release was mimicked by epinephrine (1μM), and was selectively blocked by theα-adrenergic antagonist, phentolamine (10μM). Theβ-adrenergic antagonist, propranolol (10μM), did not change IL-1 induced corticosterone release. Neither phentolamine nor propranolol had an effect on ACTH stimulated corticosterone release. Both IL-1αand IL-1βsignificantly elevated (P<0.05) epinephrine levels after a 24 hr incubation period compared to media-treated controls. Untreated adrenal cells fixed for immunohistochemical staining with a specific anti-rat tyrosine hydroxylase antibody indicate that the primary adrenal cell preparation contained 3.1±0.45% tyrosine hydroxylase positive cells. On the ultrastructural level, the chromaffin cells were found to be in direct cellular contact with cortical cells. Although IL-1αsignificantly increased (P<0.05) prostaglandin E2(PGE2) levels from primary adrenal cells, the presence of the cyclooxygenase inhibitor, indomethacin (10μM) significantly inhibited IL-1α-induced PGE2secretion without altering the effect of IL-1αon corticosterone release. Inhibitors of the lipoxygenase system (5-lipoxygenase, 10μM) and the lipoxygenase and cytochrome P450 monooxygenase systems (nordihydroguaiaretic acid, 10μM) did not effect IL-1α-induced corticosterone or PGE2release. These observations indicate that IL-1 stimulates the local release of catecholamines, which, in turn, stimulates corticosterone release through anα-adrenergic receptor; this mechanism is independent of PGE2.

ISSN:0743-5800    

DOI:10.3109/07435809509030418

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

In this review we defined and classified the neuropeptides (NPs) related to the adrenal gland, according to Palkovits (Frontiers Neuroendocrinol 10:1 1988). The concentration (RIA) and distribution (immunohistochemistry) of NPs, as well as the localization of the receptors (radioligand studies) were summarized. Direct effects of NPs on aldosterone and corticosterone synthesis obtained byin vivo, in situperfusion, andin vitroexperimental approaches were reviewed. Data (from different rat strains and genders) for 35 NPs are presented.

ISSN:0743-5800    

DOI:10.3109/07435809509030419

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

The effects of acetylcholine (ACh) on intracellular free calcium were studied in primary cultures of purified bovine adrenal zona fasciculata/reticularis (ZFR) cells. In fura-2 loaded single cells, concentrations of ACh which stimulated cortisol secretion and phosphoinositol production were found to promote an increase in free cytosolic calcium ([Ca2+]i). This response was heterogeneous, showing either (i) an initial increase in [Ca2+]i followed by a fall to a level above that in unstimulated cells, or (ii) an initial increase followed by oscillations about the original resting level or a higher resting level. The frequencies of [Ca2+]i oscillations to ACh showed a dose-dependent trend. The sustained [Ca2+]i oscillations were abolished by the muscarinic antagonist atropine, or by removal of extracellular Ca2+. These data demonstrate for the first time in adrenocortical cells that: (i) ACh can induce [Ca2+]i oscillations in single ZFR cells; (ii) these oscillations occur in a dose-dependent manner; (iii) the sustained oscillatory phase is dependent on influx of extracellular Ca2+. Thus, like cells of the zona glomerulosa, bovine ZFR cells are also capable of sustained dose-dependent oscillatory responses to agonists which activate phosphoinositidase C.

ISSN:0743-5800    

DOI:10.3109/07435809509030420

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

In the Y1 mouse adrenal tumor cell line, the 3β-hydroxysteroid dehydrogenase isomerase enzyme (3β-HSD) which catalyzes the transformation of 3β-hydroxy-5-ene steroids to 3-keto-4-ene steroids is active.The effect of typeβ1 transforming growth factor (TGFβ1), a potent modulator of adrenocortical differentiated functions, on the 3β-HSD enzyme was studied. Four isoforms of 3β-HSD yielding proteins of different mobility on SDS-PAGE were previously detected in the mouse; whereas only one form was present in the mouse adrenal, we detected two isoforms in the Y1 cells. An inhibition of the basal enzymatic activity was observed after TGFβ1 treatment which was correlated with a decrease in 3β-HSD protein (both isoforms) and m-RNA levels.

ISSN:0743-5800    

DOI:10.3109/07435809509030421

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

The enzyme, 3β-hydroxysteroid dehydrogenase/Δ5-4isomerase (3β-HSD) is an essential element in the biosynthetic pathway for potent adrenal steroid hormones that appear to regulate maturation of many tissues in utero and are critical for homeostasis after birth. The results of prior studies are suggestive that 3β-HSD activity in the human fetal adrenal (HFA) is very low and restricted to the outer zone of cortical cells, the neocortex (NC), during mid-gestation. Near the time of birth, however, there must be enhanced expression of this enzyme to allow for adaptation to extrauterine life. In the present study, we sought to characterize, by use of immunohistochemical methods, the cellular localization and developmental changes of 3β-HSD in the HFA during the interval of 11-41 wks gestation. Early in gestation, 11-15 wks, we noted considerable 3β-HSD in NC and in occasional fetal zone (FZ) cells as well. Thereafter until 24-25 wks, 3β-HSD was very low in NC cells and virtually absent from the FZ. Throughout the third trimester, the outer 1/2-2/3 of the NC was increasingly immunostained and clusters of immunoreactive cells also appeared near the central medullary vein of the adrenal. The NC cells and those located in the cortical cuff region that expressed 3β-HSD resembled zona glomerulosa cells. Among many other fetal tissues studied, only testicular Leydig cells (18,19 wks) and hilar cells of the ovary (26 wks) were found to contain 3β-HSD in quantities sufficient to be detected by immunohistochemistry. These results are suggestive of a heretofore undocumented stimulus to 3β-HSD in the HFA in early gestation followed by a suppression of the adrenal concentration of this enzyme during mid-gestation. High levels of 3β-HSD in early development may facilitate cortisol production, which is believed to play a role in differentiation of the medullary precursors during this developmental period. The control of adrenal 3β-HSD during human fetal development may be more complex than initially envisioned and requires further study.

ISSN:0743-5800    

DOI:10.3109/07435809509030422

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

It is now known that in some species (sheep, cow, pig, Ilama) the fetal adrenal cortex is capable of secreting cortisol both early and late in gestation, but not during some, variable, intermediate time period. In the sheep the fetal adrenal can secrete cortisol, and respond quickly to ACTH, both between 40-90 days of gestation, and from 120-150 days (term), but not between 90-120 days. The inability to secrete cortisol in this‘off’period is due to lack of adequate pituitary ACTH at this time to maintain expression of P-45017αand P-450ssc. Recent experiments demonstrate that the fetal pituitary does secrete adequate amounts of ACTH to keep these genes expressed, in the 40-90 day period. The question now becomes, therefore, what regulates the triphasic secretion pattern of ACTH during fetal sheep development.

ISSN:0743-5800    

DOI:10.3109/07435809509030423

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

The control of zonation in the adrenal cortex has been studied by measuring DNA synthesis using an analogue of thymidine, bromodeoxyuridine (BrDUrd). Groups of rats were infused with BrDUrd for 10-14 days whilst being treated with: high or low sodium diets; captopril; angiotensin II; dexamethasone; an inhibitor of nitric oxide synthesis, L-NAME. DNA synthesis in the zona glomerulosa was increased by low sodium food and angiotensin and was decreased by dexamethasone, captopril L-NAME and a high sodium diet. Dexamethasone, not manipulations of the renin-angiotensin system, affected DNA synthesis in the outer zona fasciculata. The BrDUrd index in the zona intermedia was unaffected by any of the treatments and was generally lower than in adjacent zona fasciculata and zona glomerulosa cells. Cells of the zona reticularis appeared to be regulated independent of the zona fasciculata. BrDUrd uptake in nuclei of the adrenal medulla was inversely related to blood pressure. We conclude that DNA synthesis in each adrenocortical zone is independently controlled. Migration of cells within zones after proliferation is likely.

ISSN:0743-5800    

DOI:10.3109/07435809509030424

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

CYP17 is not expressed in adult mouse adrenal glands but is expressed in a subset of fetal adrenocortical cells, indicating the potential to produce both corticosterone and cortisol during murine embryogenesis. CYP11A is expressed in the fetal adrenal but also in developing hindgut, which will form the colon, and in cells located beneath the skin of the embryo. Novel sites of expression of CYP17 and CYP11A in the mouse embryo suggest potential physiological roles for local production of steroids in diverse organs systems during development.

ISSN:0743-5800    

DOI:10.3109/07435809509030425

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor