Biosynthetic and morphological evidence for inhibition of aldosterone production following administration of ACTH to sheep

1980 ◽  
Vol 94 (4) ◽  
pp. 559-570 ◽  
Author(s):  
John G. McDougal ◽  
Aldona Butkus ◽  
John P. Coghlan ◽  
Derek A. Denton ◽  
Jürg Müller ◽  
...  
Keyword(s):  
Time Course ◽  
Cell Number ◽  
Zona Glomerulosa ◽  
Morphological Evidence ◽  
Zona Fasciculata ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
17 Hydroxyprogesterone ◽  
Zona Glomerulosa Cells

Abstract. The effect of ACTH administration for 1—5 days on the morphology and steroidogenic capability of sheep adrenal tissue has been examined. During this period of treatment there was a gradual decline in the in vitro conversion of 3H-labelled precursors to products of solely zona glomerulosa origin (aldosterone and 18-hydroxycorticosterone) while conversion to products of zona fasciculata origin (17-hydroxyprogesterone, 11-deoxycortisol and cortisol) was stimulated throughout. Conversion to DOC, 18-hydroxydeoxycorticosterone and corticosterone (steroids produced by both the zona glomerulosa and the zona fasciculata) declined after initial stimulation. Within 2—3 days of the commencement of treatment, the zona glomerulosa showed a progressive decrease in cell number associated with disruption of cords and cell separation. Ultrastructurally, it was found that typical zona glomerulosa cells had almost disappeared. The majority of residual cells in this area had a structure intermediate between zona glomerulosa and zona fasciculata cells. The similarity in time-course of the alterations in both the morphological and biosynthetic characteristics suggests that the decline in aldosterone output caused by ACTH administration to sheep results from the loss of adrenal zona glomerulosa cells, predominantly due to selective cellular degeneration.

Inhibition of aldosterone release by hypoxia in vitro: interaction with carbon monoxide

1994 ◽  
Vol 76 (2) ◽  
pp. 689-693 ◽  
Author(s):  
H. Raff ◽  
B. Jankowski
Keyword(s):  
Carbon Monoxide ◽  
Angiotensin Ii ◽  
Zona Glomerulosa ◽  
Michaelis Constant ◽  
Aldosterone Synthase ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
In Vitro Interaction ◽  
Zona Glomerulosa Cells

We have demonstrated that the aldosteronogenic pathway of the zona glomerulosa is unusually sensitive to modest changes in PO2 (Michaelis constant for O2 approximately 95 Torr). The current study evaluated the interaction of CO (the classic ligand for P-450 enzymes) and the decreases in O2 on aldosteronogenesis in vitro. Bovine adrenocortical zona glomerulosa cells were incubated for 2 h and stimulated with either adenosine 3′,5′-cyclic monophosphate (cAMP) or angiotensin II. Ten and 20% CO led to significant decreases in cAMP- and angiotensin II-stimulated aldosteronogenesis. The combination of 20% CO and moderate decreases in PO2 (from approximately 140 to approximately 100 Torr) led to an interactive decrease in aldosterone production. The conversion of corticosterone to aldosterone catalyzed by aldosterone synthase, which is the site of O2 sensitivity, was not significantly inhibited by CO. We conclude that the aldosterone pathway is not exceptionally sensitive to CO compared with other steroidogenic pathways. This observation suggests that the unique O2-sensitive properties of the aldosterone pathway located primarily within aldosterone synthase may not reside in its CO binding site (i.e., heme).

Roles of type I and type II isoenzymes of cyclic AMP-dependent protein kinase in steroidogenesis in rat adrenal cells

1994 ◽  
Vol 12 (2) ◽  
pp. 195-202 ◽  
Author(s):  
B J Whitehouse ◽  
D R E Abayasekara
Keyword(s):  
Cyclic Amp ◽  
Cell Function ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
Type I ◽  
Type Ii ◽  
Aldosterone Production ◽  
Dependent Protein ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

ABSTRACT The role played by cyclic AMP (cAMP)-dependent protein kinases (PKAs) in rat adrenal steroidogenesis has been investigated using cAMP analogues which show partial selectivity for the type I and type II PKA isoenzymes. These were aminohexylamino-cAMP (AHA-cAMP; selective for site 1 on type I PKA), N6-benzoyl-cAMP (BZ-cAMP; selective for site 2 on PKA types I and II) and 8-thiomethyl-cAMP (TM-cAMP; selective for site 1 on type II PKA). Positive cooperativity exists between the two nucleotide-binding sites, thus the presence of type I PKA was inferred when synergistic increases in corticosteroid production were obtained with AHA-cAMP plus BZ-cAMP and that of type II PKA when synergistic increases were obtained with TM-cAMP plus BZ-cAMP. The effects of AHA-cAMP, TM-cAMP and BZ-cAMP (10–100 μmol/l) on aldosterone production by glomerulosa cell preparations and corticosterone production by fasciculata/reticularis cell preparations were compared. Dose-related stimulation of steroid production was obtained with each cAMP analogue in both types of cell preparation. Experiments were performed using the cAMP analogues in combination at doses which gave minimal stimulation individually. Cells were incubated with AHA-cAMP (66 and 100 μmol/l) or TM-cAMP (15, 30 and 45 μmol/l) in the presence and absence of 15μmol BZ-cAMP/l. Synergistic responses were obtained with both analogue pairs in both cell types. The synergism ratio in fasciculata/reticularis cell preparations for the type I PKA selective pair of analogues (100 μmol AHA-cAMP/l plus 15μmol BZ-cAMP/l) was significantly higher (P<0·01) than that for the type II selective pair (45μmol TM-cAMP/l plus 15μmol BZ-cAMP/l; 7·9±1·2 (mean±s.e.m.) and 2·6±0·3 respectively). In zona glomerulosa preparations the ratio was higher (P<0·05) for the type II selective pair (1·6±0·1 for AHA-cAMP plus BZ-cAMP and 2·8±0·4 for TM-cAMP plus BZ-cAMP). The effects of 100μmol AHA-cAMP/l and 45μmol TM-cAMP/l on the response to ACTH (1 pmol/l–10 nmol/l) were examined. Synergistic responses were obtained in fasciculata/reticularis cells with both analogues in combination with low concentrations of ACTH (10 and 100 pmol/l). In zona glomerulosa cells only the addition of TM-cAMP (45 μmol/l) in combination with 10 pmol ACTH/1 gave rise to synergistic increases in aldosterone production, which suggests that there may be some compartmentalization of the cAMP-dependent pathway in these cells. The results indicate that both isoenzymes of PKA are present in rat adrenocortical cells and can play a part in the control of steroidogenesis. Type I PKA activity appears dominant in the control of zona fasciculata/reticularis cell function whereas modulation of type II PKA activity plays a more significant role in the responses of zona glomerulosa cells.

Inhibition of corticosteroid production by sodium pentobarbitone in rat adrenocortical preparations

1993 ◽  
Vol 136 (1) ◽  
pp. 75-83 ◽  
Author(s):  
B. J. Whitehouse ◽  
S. J. Purdy ◽  
D. R. E. Abayasekara
Keyword(s):  
Intact Animal ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
Steroid Production ◽  
Adrenal Cells ◽  
Glomerulosa Cells ◽  
Pituitary Adrenal Axis ◽  
Zona Glomerulosa Cells ◽  
Stimulation Of

ABSTRACT It is possible that some of the effects of sodium pentobarbitone on the hypothalamo-pituitary-adrenal axis in the intact animal may be attributable to direct actions on the adrenal cortex. The effects of the barbiturate on steroid production by rat adrenal preparations in vitro have therefore been examined. In zona glomerulosa cells, pentobarbitone inhibited basal steroid production in a dose-related fashion. For aldosterone and corticosterone, the doses required for 50% inhibition of production (IC50) were 1·2 mmol pentobarbitone/l and 3·7 mmol/l respectively. Steroidogenesis was inhibited at lower levels of pentobarbitone in the presence of 1 nmol ACTH/l (IC50 = 0·5 mmol pentobarbitone/l for aldosterone and 2·2 mmol/l for corticosterone). In zona fasciculata/reticularis cells, production of corticosterone was similarly reduced with an IC50 of 2·8 mmol pentobarbitone/l for basal production and 1·3 mmol/l for ACTH-stimulated production. The dose-related increases in corticosterone production produced by ACTH (0·1–1000 pmol/l) or dibutyryl cyclic AMP (0·1–1·0 mmol/l) were also eliminated in the presence of 2 mmol pentobarbitone/l. The effects of pentobarbitone (1–4 mmol/l) on the production of pregnenolone and deoxycorticosterone (DOC) were also studied. In zona fasciculata/reticularis cells, the responses of both pregnenolone and DOC were bell-shaped with increases at 1 mmol pentobarbitone/l, which fell back to control levels at 4 mmol pentobarbitone/l. Stimulation of DOC, accompanied by decreases in aldosterone and corticosterone production, was also seen in zona glomerulosa cells at 1 mmol pentobarbitone/l. The effect of 1 mmol pentobarbitone/l on the conversion of 22(R)-hydroxycholesterol (5-cholestene-3β,22(R)-diol), pregnenolone, progesterone and DOC to corticosterone and aldosterone by zona glomerulosa preparations was studied. There was a comparable reduction in the conversion of these precursors (2 μmol/l) to aldosterone with yields decreased to 20–30% of those found in the absence of pentobarbitone. The dose required for 50% reduction of the conversion of progesterone (2 μmol/l) to aldosterone was 0·55 mmol pentobarbitone/l and for corticosterone the dose was 1·75 mmol pentobarbitone/l. The results obtained show that pentobarbitone is an effective inhibitor of corticosteroid biosynthesis in rat adrenal cells, and suggest that its effects are brought about by inhibition of cytochrome P450-mediated hydroxylations. Journal of Endocrinology (1993) 136, 75–83

Potassium-induced aldosterone biosynthesis in cultured rat zona glomerulosa cells

1989 ◽  
Vol 256 (4) ◽  
pp. E475-E482
Author(s):  
J. Muller ◽  
M. Lauber ◽  
C. Schmid
Keyword(s):  
Molecular Mechanisms ◽  
Primary Cultures ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
High Potassium ◽  
Primary Monolayer ◽  
Glomerulosa Cells ◽  
Potassium Restriction ◽  
Zona Glomerulosa Cells

Rat adrenal zona glomerulosa cells lost their ability to produce aldosterone from either endogenous precursors or added deoxycorticosterone within 2 days of primary monolayer culture in a medium with a potassium concentration of 6.3 mmol/l. The lost corticosterone methyl oxidase I and II activities were totally regenerated when the ambient potassium concentrations was raised to 31 mmol/l. The conversions of deoxycorticosterone to 18-hydroxycorticosterone and aldosterone were completely restored by culture in a high-potassium medium also in zona glomerulosa cells of rats in which aldosterone biosynthesis had been suppressed by potassium restriction and sodium loading. However, these conversions were not induced in zona fasciculata-reticularis cells. The induction of aldosterone biosynthesis was associated with the appearance of a mitochondrial 49,000 protein cross-reacting with an antibody raised against bovine adrenal cytochrome P-450(11) beta. Thus primary cultures of zona glomerulosa cells are promising models for studying in vitro the molecular mechanisms of long-term adaptation of aldosterone biosynthesis to sodium and potassium intake.

scholarly journals Guinea pig adrenocortical cells: in vitro characterization of separated zonal cell types.

1982 ◽  
Vol 94 (2) ◽  
pp. 241-252 ◽  
Author(s):  
P Miao ◽  
V H Black
Keyword(s):  
Guinea Pig ◽  
Morphological Characteristics ◽  
Zona Glomerulosa ◽  
Equilibrium Density ◽  
Zona Fasciculata ◽  
Adrenocortical Cells ◽  
Steroid Production ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

This paper reports a quick, relatively simple and reproducible technique for obtaining populations of zona fasciculata and zona glomerulosa cells up to 80-90% pure, which can be maintained in vitro for study of adrenocortical cell function. Isolated guinea pig adrenocortical cells were separated on a 1-28% bovine serum albumin/Ca++, Mg++-free buffer gradient (wt/vol at 4% increments) using equilibrium density centrifugation (570 g, 30 min). Over 60% of the 8 x 10(5) viable cells/adrenal obtained in the total isolate were recovered after separation. 80% of the zona glomerulosa cells were found in the lower three bands of the gradient. 78% of the zona fasciculata cells were found in the top three bands. Of the cells in the first two bands, 78-91% were zona fasciculata cells, whereas of the cells in the bottom two bands 92-95% were zona glomerulosa cells. The cells retained the morphological characteristics of cells in situ and could be maintained in vitro for periods up to 11 d. They produced a wide variety of steroids, cortisol, corticosterone, aldosterone, 11-beta-hydroxyandrostenedione, deoxycortisol, deoxycorticosterone, cortisone, 18-hydroxycorticosterone, and a product tentatively identified as dehydroepiandrosterone, and they responded to ACTH in a dose-responsive manner with enhanced levels of steroid output. Zona glomerulosa-enriched populations differed from zona fasciculata-enriched populations in their abundant production of aldosterone and in the pattern of steroid production. None of the cultures responded to angiotensin II (100 pg/ml) with increased steroid production.

Effect of composition of incubation medium on aldosterone and corticosterone production by isolated rat zona glomerulosa cells

1982 ◽  
Vol 94 (2) ◽  
pp. 211-224 ◽  
Author(s):  
D. J. Campbell
Keyword(s):  
Angiotensin Ii ◽  
Cyclic Amp ◽  
Incubation Medium ◽  
Zona Glomerulosa ◽  
Bicarbonate Buffer ◽  
Angiotensin Ii Antagonist ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

The role of the composition of the incubation medium in determining the steroidogenic responsiveness of collagenase-dispersed rat zona glomerulosa cells was examined by studying the effect on production of aldosterone and corticosterone of (1) changes in the bovine serum albumin (BSA) concentration in Krebs–Ringer bicarbonate buffer (KRBGA), (2) dialysis of the BSA and (3) comparison of KRBGA with 'modified' Medium 199. Medium 199 was modified so that its electrolytic content was identical to that of KRBGA. Compared with 0·1–0·2% BSA in KRBGA, BSA concentrations of 0·5 and 4% caused inhibition of both basal and K+-stimulated, but not angiotensin II-stimulated steroidogenesis. This inhibitory property of BSA was not removed by dialysis. The BSA did, however, contain a dialysable factor which increased both basal steroidogenesis and the steroidogenic response to maximal K+ and angiotensin II stimulation. Both incubation media contained 0·2% BSA for the comparison of KRBGA with modified Medium 199. Modified Medium 199 increased both basal steroidogenesis and the aldosterone response to K+ stimulation (per cent increase above basal) by two- to threefold compared with KRBGA, with smaller increases in the response to ACTH and 5-hydroxytryptamine (5-HT) and a decrease in the response to cyclic AMP. In contrast, modified Medium 199 increased the aldosterone response to angiotensin II by sevenfold, from 60% (in KRBGA) to 420%. In KRBGA, angiotensin II inhibited K+-stimulated aldosterone production. This effect was produced by concentrations of angiotensin II below the threshold for steroidogenesis and could be reproduced with the angiotensin II antagonist [Sar1, Ileu8]-angiotensin II. Angiotensin II did not inhibit K+-stimulated aldosterone production in modified Medium 199. These data emphasize the importance of the composition of the incubation medium in determining the steroidogenic responsiveness of rat zona glomerulosa cells in vitro. Furthermore, these data indicate that the steroidogenic response to angiotensin II, compared with K+, ACTH, 5-HT and cyclic AMP, is more readily influenced by other, as yet unidentified, factors in the incubation medium, and are consistent with recent evidence that angiotensin II and K+ do not share a common mode of action on steroidogenesis by these cells.

Effect of exposure to hypoxia from birth on aldosterone in rabbits: role of unesterified fatty acids

1997 ◽  
Vol 272 (4) ◽  
pp. R1084-R1087 ◽  
Author(s):  
H. Raff ◽  
B. M. Jankowski ◽  
T. L. Goodfriend ◽  
J. E. Baker ◽  
P. E. Papanek
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Zona Glomerulosa ◽  
Hypoxic Hypoxia ◽  
Adrenocortical Function ◽  
Total Serum ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

Hypoxia and fluid and electrolyte disturbances are serious risks to normal postnatal development. Because a decrease in inspired O2 (hypoxic hypoxia) inhibits aldosterone synthesis in the adult and aldosterone controls water and electrolyte balance, we studied adrenocortical function in rabbits exposed to normobaric normoxia or hypoxic hypoxia (fraction of inspired O2 0.09) from birth. At 21 days of age, rabbits were anesthetized, the adrenals were rapidly removed, and the adrenal capsules containing mostly zona glomerulosa cells were separated. Cells were dispersed with collagenase and studied in vitro. Hypoxia in vivo resulted in a 73% decrease in basal aldosterone release and a 86% decrease in adenosine 3',5'-cyclic monophosphate-stimulated aldosterone release in vitro. We hypothesized that increased unesterified fatty acids could be partly responsible for inhibition of aldosterone synthesis. Total serum unesterified fatty acids in hypoxic kits were significantly increased (298 +/- 14 micromol/l) compared with normoxic kits (184 +/- 31 micromol/l). When cells from hypoxic rabbits were washed with fatty acid-free albumin and studied under conditions devoid of fatty acids, aldosterone production was partially restored. Corticosterone production was not affected by washing. Washing had no effect on aldosterone synthesis by cells from normoxic rats. Finally, exposing washed zona glomerulosa cells to oleic acid (10-50 microM) inhibited aldosteronogenesis. We conclude that exposure to hypoxia from birth attenuates aldosterone production in part due to an increase in levels of unesterified fatty acid levels.

Relation of Intracellular K+ and Steroidogenesis in Isolated Adrenal Zona Glomerulosa and Fasciculata Cells

1975 ◽  
Vol 49 (1) ◽  
pp. 13-26
Author(s):  
F. A. Mendelsohn ◽  
C. Mackie
Keyword(s):  
Potassium Concentration ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
High Potassium ◽  
External Potassium ◽  
Glomerulosa Cells ◽  
Unit Gravity Sedimentation ◽  
Zona Glomerulosa Cells ◽  
Stimulation Of

1. Intracellular K+ content, water spaces and corticosterone output were measured in isolated zona glomerulosa and zona fasciculata-reticularis cell suspensions of rat adrenal cortex, after incubations in vitro under conditions designed to alter steroidogenesis. 2. Intracellular K+ of unpurified zona glomerulosa cells was not altered after stimulation of corticosterone output with serotonin. Similarly, with zona glomerulosa cells purified by unit gravity sedimentation, no change in intracellular K+ was detected after stimulation of steroidogenesis with serotonin or angiotensin II. 3. In high-potassium medium (final concentration 84 mmol/l), parallel increases in intracellular K+ and corticosterone output were observed with both unpurified and purified zona glomerulosa cells. However, a similar increase in intracellular K+ also occurred in high-potassium medium with zona fasciculata cells, whose steroid output is unresponsive to external potassium concentration ([K+]). 4. Ouabain at 10−5 mol/l depressed the intracellular [K+] of glomerulosa cells but did not alter basal or stimulated corticosterone output. Similar results were obtained with fasciculata cells. 5. Ouabain at 5×10−4 mol/l further depressed intracellular [K+] of glomerulosa cells and inhibited basal and stimulated corticosterone output. However, this concentration of ouabain also inhibited steroidogenesis in fasciculata cells. 6. These results demonstrate a variety of situations where changes in intracellular [K+] are dissociated from those in corticosterone output and indicate that intracellular [K+] cannot be the sole mechanism regulating steroidogenesis under these conditions.

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