Adrenocorticotropin inhibition of mineralocorticoid hormone production

Partial 11 beta-hydroxylase activity suppression after dexamethasone in patients with major depression

Eleven beta-hydroxylase activity was assessed by measuring the cortisol to 11-deoxycortisol ratio in 20 control subjects, 38 patients with major depression, and five patients with Cushing's disease before and after 1 mg of dexamethasone. The mean levels of 11 beta-hydroxylase activity did not differ among groups before dexamethasone. After dexamethasone patients with Cushing's disease showed a nonsignificant increase in 11 beta-hydroxylase activity while patients with major depression and controls subjects both showed a decrease. Endogenous depressive patients were no more likely to show high 11 beta-hydroxylase activity than neurotic depressive patients; however, depressed patients with cortisol nonsuppression after dexamethasone were. Post-dexamethasone 11 beta-hydroxylase activity is positively correlated with age in both control subjects and patients with depression.

Stable adrenocorticotropin-stimulated 11-beta-hydroxylase activity but loss of age-related changes in patients with hypercortisolemia

Eleven-beta-hydroxylase activity was measured before and after acute adrenocorticotrophic hormone (ACTH) stimulation in 28 controls, 25 depressed Dexamethasone Suppression Test (DST) suppressors, 13 DST nonsuppressor patients, and 8 patients with Cushing's syndrome to investigate changes in states of cortisol hypersecretion. Eleven-beta-hydroxylase activity was equivalent among groups both before and after stimulation. Such 11-beta-hydroxylase stability, however, resulted in higher cortisol and 11-deoxycortisol poststimulation levels in both depressed DST nonsuppressors and Cushing's patients than in controls. Basal 11-beta-hydroxylase activity is positively correlated and 11-deoxycortisol is negatively correlated with age in controls and DST suppressors, but not in the patients tested with evidence of cortisol hypersecretion. These findings suggest that in vivo basal 11-beta-hydroxylase activity rises gradually with age, but does not rise after acute administration of exogenous ACTH. The age relationship is lost in states of cortisol hypersecretion, but the lack of response to acute exogenous ACTH is not affected.

Suppression and stimulation of mineralocorticoid hormones (MCH) in the simple virilizing form of congenital adrenal hyperplasia (CAH) evaluated by the quantitation in adrenal venous blood

Four untreated female patients with the nonsalt-losing form of congenital virilizing adrenal hyperplasia (21-hydroxylase deficiency) (21-OHD) maintained on a daily sodium intake of 120 m-equiv were studied by bilateral adrenal vein catheterization. Simultaneous right and left adrenal and peripheral blood samples were collected for determination of cortisol (F), progesterone (P), 17-hydroxyprogesterone (17-OHP), aldosterone (Aldo), and deoxycorticosterone (DOC). All patients were studied during sequential ACTH suppression (30 min after intravenous administration of 4 mg of dexamethasone) and stimulation (5 min after intravenous administration of 250 micrograms beta-ACTH [cosyntropin]). Basal peripheral concentrations of Aldo, DOC, P and 17-OHP were increased, whereas F concentrations were in the lower limit of the normal range. Dexamethasone suppressed adrenal secretion in all subjects. Subsequent adrenal stimulation by ACTH increased P, 17-OHP and DOC, whereas F returned to only control levels. DOC responses to ACTH in the adrenal vein effluents correlated significantly with Aldo responses but not with the 17-OHP increments, suggesting that the adrenal responses of Aldo and DOC to ACTH are events that probably occur in the same zone.

Blood pressure and metabolic effects of ACTH in normotensive and hypertensive man

ACTH administration (0.5 mg Synacthen Depot I/M 12 hourly for 5 days) significantly increased systolic blood pressure in normotensive subjects (n=6) and mild essential hypertensives (n=6) but not in 2 Addisonian women, indicating that the pressure rise was adrenally dependent. ACTH administration was associated with urinary sodium retention, hypokalaemia, elevation of fasting blood glucose, lymphopaenia and eosinopaenia. Body weight was increased only in the normotensive subjects. Plasma renin concentration fell and renin substrate rose. Inactive renin fell in the hypertensive subjects only. Plasma cortisol, 11-deoxycortisol, corticosterone, deoxycorticosterone, 17 alpha-hydroxyprogesterone and 17-hydroxy, 20-dihydroprogesterone were all increased by ACTH treatment. Plasma aldosterone rose initially in the normotensives but then fell. ACTH administration in man produces metabolic and hormonal changes similar to those produced by ACTH in sheep but the rise in blood pressure is systolic only in man. The steroid(s) responsible for the blood pressure rise with ACTH in man have not been defined.

Regulation of the mineralocorticoid hormones in adrenocortical disorders with adrenocorticotropin excess

Chronic stimulation by adrenocorticotropin (ACTH) of the adrenal cortex produces different plasma mineralocorticoid hormone (MCH) patterns, depending on the amount of glucocorticoid hormones (cortisol) concurrently generated and the degree of activation of the renin angiotensin system (RAS). Patients with Cushing's disease or the ectopic ACTH-excess syndrome have normal or low production of the MCHs, aldosterone and 18-hydroxycorticosterone (18-OHB), by the zona glomerulosa (ZG), elevated cortisol and deoxycorticosterone (DOC) levels, and high-normal to elevated production of the MCHs corticosterone (B) and 18-hydroxydeoxycorticosterone (18-OHDOC) by the zona fasciculata (ZF). Prolonged administration of superphysiologic doses of ACTH to normal subjects yields similar patterns. Patients with simple virilizing 21-hydroxylase deficiency (21-OHD) have impaired ZF production of B and 18-OHDOC and elevated DOC, 18-OHB, and aldosterone secretion secondary to the superimposed RAS stimulation of the ZG. Patients with 17 alpha-hydroxylase deficiency (17 alpha-OHD) have elevated levels of the ZF MCHs DOC, B, 18-OHDOC, and 18-OHB and a functionally suppressed ZG. Patients with 11 beta-hydroxylase deficiency (11 beta-OHD) have only elevated production of DOC by the ZF and suppressed RAS and aldosterone. A significant negative correlation between cortisol and aldosterone concentrations suggests that cortisol is involved in the ACTH-mediated inhibition of aldosterone formation.

Circadian secretion of ACTH, cortisol, and mineralocorticoids in Cushing's syndrome

The behaviour of plasma levels of ACTH was studied in five untreated patients with pituitary-dependent Cushing's syndrome, with blood samples taken every half an hour for a total period of 24 hours; plasma cortisol, corticosterone, deoxycorticosterone (DOC) and aldosterone were also measured simultaneously. In all cases, above normal secretory impulses of ACTH and cortisol, at approximately the same height, were present throughout the day, while between these peaks the levels were in the normal range. Few peaks of ACTH and cortisol were simultaneous and rare secretory impulses of corticosterone, and deoxycorticosterone were in synchrony with those of ACTH or cortisol. DOC levels were found to have some peaks above normal levels while corticosterone levels presented rare elevated peaks during the day. Plasma aldosterone values on the other hand, were extremely low in all except in one case, where the variations may be interpreted as pure fluctuations. These findings confirm that: 1) In a number of cases, multiple samples of ACTH and cortisol (during the 24 hrs.) appear to be essential in order to distinguish pituitary-dependent Cushing's syndrome from normal; 2) In conditions of ACTH excess, DOC and corticosterone secretion seems to become progressively less ACTH-dependent as we proceed down the biosynthetic chain towards aldosterone, which is suppressed in most cases.

Steroids as potential modulators of angiotensin receptors in bovine adrenal glomerulosa and kidney

To test the hypothesis that there is feedback inhibition of adrenal angiotensin receptors by substances released in response to the peptides, we measured binding of labeled angiotensins in the presence of various steroids. Approximately half of the 70 steroids tested inhibited binding of labeled angiotensin II and III to intact and broken cells from bovine adrenal glomerulosa and kidney, but the concentrations required for inhibition were relatively high. The most potent inhibitors were 3 alpha, 5 beta tetrahydroaldosterone and tetrahydrodeoxycorticosterone (ID50 = 8 x 10-5 M). Kinetic analysis showed that inhibition was mostly competitive. among steroids whose reduced congeners were tested, potency increased in the sequence: parent steroid less than 5 alpha dihydroderivative less than 5 beta dihydro derivative less than 3 alpha, 5 beta tetrahydro-derivative. Tetrahydrodeoxycorticosterone inhibited aldosteronogenesis by intact cells at concentrations that inhibited angiotensin binding. Steroids differentially inhibited binding of labeled angiotensins in II and III, and discriminated between receptors in adrenal glomerulosa and kidney. The results provide additional evidence for heterogeneity of angiotensin receptors, and lead to the prediction that any normal or pathological inhibition of angiotensin receptors by steroids will be mediated by reduced derivatives.