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Context: Adrenocorticotropic hormone (ACTH) can contribute to aldosterone excess in primary aldosteronism (PA) via increased melanocortin type 2 receptor expression. Dynamic manipulation of the hypothalamic-pituitary-adrenal (HPA) axis could assist PA subtyping, but a direct comparison of dynamic tests is lacking., Objective: To investigate plasma steroid differences between aldosterone-producing adenoma (APA) and bilateral PA (BPA) relative to ACTH variations., Methods: We conducted comprehensive dynamic testing in 80 patients: 40 with APA and 40 with BPA. Peripheral plasma was collected from each patient at 6 time points: morning; midnight; after 1 mg dexamethasone suppression; and 15, 30, and 60 minutes after ACTH stimulation. We quantified 17 steroids by mass spectrometry in response to ACTH variations in all patients and compared their discriminative power between the 2 PA subtypes., Results: Patients with APA had higher morning and midnight concentrations of 18-hydroxycortisol, 18-oxocortisol, aldosterone, and 18-hydroxycorticosterone than those with BPA (P < 0.001 for all). In response to cosyntropin stimulation, the APA group had larger increments of aldosterone, 18-oxocortisol, 11-deoxycorticosterone, corticosterone, and 11-deoxycortisol (P < 0.05 for all). Following dexamethasone suppression, the APA group had larger decrements of aldosterone, 18-hydroxycortisol, and 18-oxocortisol (P < 0.05 for all), but their concentrations remained higher than in the BPA group (P < 0.01 for all). The highest discriminatory performance between the PA subtypes was achieved using steroids measured 15 minutes post-ACTH stimulation (area under receiver operating characteristic curve 0.957)., Conclusion: Steroid differences between APA and BPA are enhanced by dynamic HPA testing; such noninvasive tests could circumvent the need for adrenal vein sampling in a subset of patients with PA., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Context: Serum free cortisol (SFF) responses to cosyntropin simulation test (CST) may more accurately assess adrenal function than total cortisol (TF)., Objective: The objective of the study was to evaluate the diagnostic utility of SFF responses during a 250-μg CST., Design: We recruited healthy volunteers (HV; n = 27), patients with primary and secondary adrenal insufficiency (n = 19 and n = 24, respectively), and subjects with Child-Pugh class A cirrhosis (CH; n = 15). Each received 250 μg cosyntropin with measurement of ACTH and corticosteroid binding globulin (CBG) at time 0 and TF and SFF at 0, 30, and 60 minutes. Salivary cortisol was measured at all time points in CH subjects., Results: Peak SFF and TF were significantly higher in HVs vs both AI groups (P < .05). Peak SFF and TF (6.8 μg/dL vs 2.2 μg/dL; [188 nmol/L vs 62 nmol/L]; P < .01) were significantly higher in the secondary adrenal insufficiency vs primary adrenal insufficiency patients. The optimal peak SFF criterion to identify adrenal insufficiency patients vs HV was 0.9 μg/dL (25 nmol/L) (sensitivity of 95%, specificity of 100%). Mean CBG and albumin levels were similar among all four groups. CH patients had a higher peak SFF than HV (2.4 vs 2.0 μg/dL; P = .02. In the CH patients, peak salivary cortisol levels correlated well with peak SFF (rs = 0.84, P = .005). CBG levels were similar among the groups., Conclusion: We provide normative data for SFF values in HV and AI during the CST. Normal CBG levels in mild cirrhosis did not affect the interpretation of the CST.

Context: The diagnostic value of tests for detecting hypothalamic-pituitary adrenal insufficiency (HPAI) is controversial., Objective: Our objective was to compare standard-dose and low-dose corticotropin tests for diagnosing HPAI., Data Sources: We searched the PubMed database from 1966-2006 for studies reporting diagnostic value of standard-dose or low-dose corticotropin tests, with patient-level data obtained from original investigators., Study Selection: Eligible studies had more than 10 patients. All subjects were evaluated because of suspicion for chronic HPAI, and patient-level data were available. We excluded studies with no accepted reference standard for HPAI (insulin hypoglycemia or metyrapone test) if test subjects were in the intensive care unit or if only normal healthy subjects were used as controls., Data Extraction: We constructed receiver operator characteristic (ROC) curves using patient-level data from each study and then merged results to create summary ROC curves, adjusting for study size and cortisol assay method. Diagnostic value of tests was measured by calculating area under the ROC curve (AUC) and likelihood ratios., Data Synthesis: Patient-level data from 13 of 23 studies (57%; 679 subjects) were included in the metaanalysis. The AUC were as follows: low-dose corticotropin test, 0.92 (95% confidence interval 0.89-0.94), and standard-dose corticotropin test, 0.79 (95% confidence interval 0.74-0.84). Among patients with paired data (seven studies, 254 subjects), diagnostic value of low-dose corticotropin test was superior to standard-dose test (AUC 0.94 and 0.85, respectively; P<0.001)., Conclusions: Low-dose corticotropin test was superior to standard-dose test for diagnosing chronic HPAI, although it has technical limitations.

Chronic dysregulation of hypothalamus-pituitary-adrenal axis activity is related to several stress-related disorders. Evidence suggests that polymorphisms in the glucocorticoid receptor (GR) gene may have an impact on this neuroendocrine system. In the present investigation, 112 healthy males were studied to estimate the impact of three GR gene polymorphisms (BclI RFLP, N363S, ER22/23EK) on cortisol and ACTH responses to psychosocial stress (Trier Social Stress Test) and pharmacological stimulation (1 microg ACTH(1-24), 0.5 mg dexamethasone). Because only four ER22/23EK heterozygotes were identified, these subjects were not statistically analyzed. Compared with subjects with the wild-type GR genotype (n = 36), 363S allele carriers (n = 10) showed significantly increased salivary cortisol responses to stress, whereas the BclI genotype GG (n = 18) was associated with a diminished cortisol response. BclI heterozygotes and homozygotes (GG) exhibited a trend toward lower ACTH responses, compared with wild-type subjects and 363S carriers. The cortisol response to ACTH(1-24) administration was not significantly different between genotypes. After dexamethasone ingestion, 363S carriers showed a trend toward an enhanced cortisol suppression. This is the first report documenting an impact of GR gene polymorphisms on cortisol (and perhaps ACTH) responses to psychosocial stress. These variants may contribute to the individual vulnerability for hypothalamus-pituitary-adrenal-related disorders.

To determine the efficiency of transmucosal absorption of ACTH, we measured serum cortisol, aldosterone, dehydroepiandrosterone (DHEA), and DHEA sulfate (DHEA-S) levels after intranasal (in) vs. iv administration of ACTH-(1-24) (250 microg) in 12 healthy adult men (mean age, 24.3 +/- 3.2 yr; range, 21-31 yr), who had received no prior medication and had no symptoms of rhinitis. Blood was collected at 0, 30, 60, 120, and 180 min after administration of ACTH-(1-24), and the levels of adrenocortical steroids were measured by specific RIAs. There were no side-effects associated with in or iv ACTH administration. After in administration, serum cortisol and aldosterone increased rapidly by 224.7 +/- 39.2% and 147.2 +/- 50.5%, respectively, peaking 30 min after ACTH-(1-24) administration, and decreasing to basal levels within 120 min. These increases in serum cortisol and aldosterone were lower than those obtained after iv administration. Thirty minutes after in or iv administration of ACTH-(1-24), DHEA increased by 49.1 +/- 27.2% and 81.6 +/- 17.1%, respectively, and remained elevated for 180 min. Serum DHEA-S levels did not change after in administration of ACTH-(1-24) and increased only slightly after iv injection. Adrenocortical steroid levels did not increase after in administration of saline. These data demonstrate that adrenocortical steroids are stimulated by in administration of ACTH-(1-24). We suggest that intranasal administration of ACTH offers both a diagnostic approach as an adrenal function test and a therapeutic approach as ACTH replacement therapy in patients with ACTH deficiency. The latter may be more physiological than glucocorticoid replacement.

Excess adrenal androgen (AA) levels are observed in 25--50% of women with the polycystic ovary syndrome (PCOS), and AA excess in PCOS may represent selection bias. Thus, it is possible that AA secretion among the general population is highly variable, and that those women who are predisposed to secreting greater amounts of AA have a greater probability of having PCOS. We now hypothesize that the levels of AAs are highly variable among normal nonhyperandrogenic women, and that this heterogeneity is the result of a variable response of AAs to ACTH stimulation. To test this hypothesis we prospectively studied the response of dehydroepiandrosterone (DHA) and cortisol (F) to a 60-min acute stimulation with ACTH-(1--24) in 56 healthy eumenorrheic nonhirsute healthy women with a mean age of 28.9 yr (range, 20--37 yr.) and a mean body mass index (BMI) of 29.2 kg/m(2) (18.2--46.2 kg/m(2)). Baseline samples and poststimulation samples were assayed for DHA and F. The basal and ACTH-stimulated levels of DHA, but not those of F, were negatively correlated with age, although neither the basal nor ACTH-stimulated responses of DHA and F varied with BMI. After controlling for age, the basal F level was negatively correlated to its net increment (i.e. Delta F; r = -0.54; P < 0.001), whereas there was no significant relationship between basal DHA and Delta DHA. We also compared the intersubject variability (coefficient of variation) for basal and stimulated levels of DHA and F. For basal (DHA(0)), 60 min (DHA(60)), and net increment in (Delta DHA) DHA levels, the coefficients of variation were 67.9%, 61.4%, and 76.0%, respectively; for F(0), F(60), and Delta F, they were 40.4%, 16.9%, and 31.3%, respectively. The variance in Delta DHA was significantly higher, and the variance in F(60) was significantly lower than that in all other variables; DHA(0), DHA(60), F(0), and Delta F had similar variances. In conclusion, in our population of healthy reproductive-aged women we observed that both basal and ACTH-stimulated levels of DHA after ACTH-(1--24) stimulation had significantly greater intersubject variance (approximately 60--70%) compared with the basal and poststimulation levels of F (approximately 15--40%). These data support the hypothesis that among normal women, AA (i.e. DHA) levels are highly variable compared to those of F. In addition, the intersubject variability in DHA levels is at least in part due to a variable response of AAs to ACTH stimulation. Whether the AA excess frequently observed in PCOS is due to the greater risk of those women with higher AA levels, basally and after ACTH stimulation, remains to be confirmed.

Although stress is known to inhibit the hypothalamic-pituitary-gonadal axis, recent studies in the monkey show that, under certain conditions, in the presence of estrogen, stress may actually stimulate LH release. We investigated the effects of a mild inflammatory stress (2.0-3.0 ng/kg endotoxin) on LH release in five postmenopausal women with and without transdermal estradiol (E2, 0.1 mg) replacement. In another five E2-treated women, LH release was studied when the adrenal was stimulated directly by a 3-h ACTH infusion (Cortrosyn, 50 microg/h). Mean E2 levels were less than 12 pg/mL in the unreplaced subjects and were 86 +/- 10 pg/mL and 102 +/- 18 pg/mL in the two groups of E2-replaced subjects. Blood was sampled every 15-20 min for 2 h before and for 7 h after endotoxin or ACTH injection. Mean cortisol and progesterone levels increased in all three groups over time (P < 0.001). In the women without E2 replacement, basal LH was 26.8 +/- 5.3 mIU/mL and did not change significantly, over time, after endotoxin (P = 0.58). In the same women on E2, however, a significant increase in LH occurred after endotoxin (P = 0.02), from a mean hourly baseline of 15.3 +/- 5.4 mIU/mL to a peak of 50.0 +/- 25.2 mIU/mL. During the ACTH infusion, there was a significant stimulation of LH release in the E2-replaced subjects (P < 0.001), from a mean hourly baseline of 13.3 +/- 3.0 mIU/mL to a peak of 44.1 +/- 11.7 mIU/mL. In both groups, this increase occurred 2-4 h after the initial rise in progesterone and persisted to the end. We conclude that, in the presence of sufficient estrogen, activation of the hypothalamic-pituitary-adrenal axis leads to a stimulation of LH release. This is likely related to a rise in adrenal progesterone and its known stimulatory effect on LH release in the presence of E2. These studies provide a potential mechanism in the human by which an acute stress during the follicular phase of the menstrual cycle might lead to a premature LH surge and thereby interfere with follicular maturation and ovulation.

The dose of 250 microg used in the standard short synacthen test is supraphysiological and lower doses may provide a more sensitive test. We examined steroid responses to 125ng/m2, 250ng/m2 and 500 ng/m2 (1-24)ACTH in 6 normal males, looking at effects of dose and the within- and between-subject coefficients of variation (CV). Subjects were given each dose 3 times, blood samples were taken at 10 minute intervals. There was a dose response relationship between dose of (1-24)ACTH and peak values for cortisol and 17OHP (p<0.05). There was no difference between peaks of A4 at different doses and no clear peaks were reached for DHEAS. 86% of the peaks for 17OHP, 63% for A4 and 25% for cortisol were at 10 minutes and 14%, 29% and 65% respectively at 20 mins (p=0.001). Within-subject CV for cortisol was 12.6% and between subject 10.1%. Tests of adrenal function using low doses of (1-24)ACTH have acceptable between- and within-subject CV for peak values with a dose as low as 125 ng/m2 (1-24)ACTH. Protocols for low dose synacthen tests, with traditional sampling at zero, 30 and 60 minutes or even as shown here at 10 minute intervals, fail to fully define the changes in steroid levels following adrenal stimulation. More frequent blood sampling will be needed to accurately detect peak levels in particular of 17OHP and A4.

Aging in women is associated with reduced production of adrenal androgens (AAs); this decrease may in part be the result of menopausal hypoestrogenism. To determine the effects of physiological concentrations of estradiol (E2) on adrenocortical sensitivity and responsiveness in postmenopausal women, we determined steroid responses to a continuous incremental ACTH-(1-24) infusion (0, 20, 40 80, 160, 320, 640, and 1280 ng/1.5 m2/h), followed by an ACTH-(1-24) bolus of 0.25 mg, after overnight dexamethasone suppression before and after 3 months of E2 therapy (transdermal E2, 0.05 mg/day) in 14 postmenopausal women. After E2 treatment, subjects demonstrated an increase in serum E2 concentrations from 29.8 +/- 2.6 to 49.9 +/- 6.0 pg/mL (P < 0.005) and a decline in mean FSH levels from 83.1 +/- 24.4 to 57.5 +/- 17.3 mIU/mL (P < 0.004). E2 administration had no effect on basal, postdexamethasone, or maximally stimulated serum levels of cortisol (F), dehydroepiandrosterone (DHEA), androstenedione (A4), or 17-hydroxyprogesterone (17-OHP). Furthermore, E2 did not affect adrenal sensitivity or responsiveness to ACTH-(1-24) stimulation. Finally, the steroid ratios reflecting 3 beta-hydroxysteroid dehydrogenase (i.e. the A4/DHEA ratio) and delta 417,20-lyase (i.e. the A4/17-OHP ratio) activities also were unaffected by E2 therapy. The responsiveness of F to ACTH was significantly greater than that of DHEA, A4, or 17-OHP regardless of the circulating E2 levels. Furthermore, F and A4 were significantly more sensitive to ACTH stimulation than were 17-OHP and DHEA, and this was not altered by E2 administration. We conclude that transdermal E2 replacement to postmenopausal women does not significantly alter AA sensitivity or responsiveness to ACTH. Hence, it is unlikely that the hypoestrogenism of menopause contributes to the decline in AAs noted with age. Furthermore, menopausal estrogen replacement, at least in physiological amounts administered transdermally, cannot be expected to reverse the suppressed production of these androgens.

In several species, including the human fetus, insulin-like growth factors (IGF-I and IGF-II) have been reported to modulate adrenal steroidogenesis, thus contributing to adrenal cortical differentiation. In the present study, we examined the long term effects of IGF-I and -II on human adult adrenal fasciculata-reticularis cells cultured in a chemically defined medium and compared them to the effects of insulin, human GH, and ACTH. Treatment for 3 days with IGF-I or -II at nanomolar concentrations or with insulin at micromolar concentrations slightly increased the production of androstenedione, cortisol, and dehydroepiandrosterone about 1.5-fold over that by control cells. Moreover, the acute steroidogenic response to ACTH of cells pretreated with IGF-I, IGF-II, or insulin was 3- to 6-fold higher than that of control cells. For each hormone, these effects of IGF-I and -II were dose dependent between 0.1-26 nmol/L (1-200 ng/mL). The secretion of androstenedione was more potently stimulated than that of dehydroepiandrosterone and cortisol, and this effect was more clearly yielded by pretreatment with IGF-II than with IGF-I or insulin. Human GH had no effect on these cells. In cells treated with IGF-I or -II, the messenger ribonucleic acid (mRNA) levels of cytochrome P450 17 alpha-hydroxylase and of 3 beta-hydroxysteroid dehydrogenase were increased, and the abundance of ACTH receptor mRNA was also slightly enhanced, but the mRNA of cytochrome P450 cholesterol side-chain cleavage enzyme was unchanged. In conclusion, IGFs enhance the steroidogenesis and ACTH responsiveness of human adrenocortical cells in culture. We speculate, that by this mechanism, IGFs may contribute to clinical states with hyperandrogenemia.

Some investigators have suggested that "dysregulation" of cytochrome P450c17 alpha may result in the exaggerated secretion of ovarian androgens in hyperandrogenism. Although the majority of hyperandrogenic (HA) patients demonstrate an ovarian source for their androgens, approximately 50% also display adrenocortical hyperactivity and adrenal androgen excess. To determine whether 17-hydroxylase (17-OH) and/or 17,20-lyase dysregulation is responsible for the adrenocortical abnormalities noted in many HA patients, we studied 92 consecutive women with hirsutism and/or HA oligomenorrhea; 26 healthy eumenorrheic nonhirsute women served as controls. The basal levels of total and free testosterone (T), sex hormone-binding globulin, and dehydroepiandrosterone sulfate were measured, and pregnenolone, 17-hydroxypregnenolone, progesterone, 17-hydroxyprogesterone, dehydroepiandrosterone, and androstenedione were measured 0 and 60 min after the acute iv administration of ACTH-(1-24). Controls and HA patients did not differ in mean age or body mass, but HA women had higher basal T, free T, dehydroepiandrosterone sulfate, androstenedione, and LH/FSH and lower sex hormone-binding globulin levels. The mean estimated basal 17-OH activity was higher among HA patients than in controls. Although 52 HA patients demonstrated solely an exaggerated basal delta 5-17-OH activity estimate, few HA patients had an exaggerated estimate for either basal delta 4-17-OH or ACTH-stimulated 17-OH activity. No HA patient demonstrated an exaggerated 17,20-lyase basal activity, whereas 14 demonstrated an exaggerated delta 4-17,20-lyase ACTH-stimulated activity only. There was no association between these estimates of 17-OH and 17,20-lyase activities and the circulating adrenal androgen levels in HA women. Importantly, none of the patients demonstrated an increase in the basal activities of both 17-OH and 17,20-lyase, and only 4 patients demonstrated an exaggerated ACTH-stimulated activity of both 17-OH and 17,20-lyase. In conclusion, the steroidogenic profile observed in this population of HA women before and after ACTH-(1-24) stimulation is not consistent with dysregulation of cytochrome P450c17 alpha and probably represents a generalized alteration of adrenocortical control or biosynthesis.

Patients with glucocorticoid-remediable aldosteronism (GRA) possess a chimeric gene resulting from fusion of the genes encoding steroid aldosterone synthase and 11 beta-hydroxylase. In the adrenal zona fasciculata, this may lead to ectopic expression under ACTH control of aldosterone synthase activity and increased formation of cortisol C18 oxidation products. We assessed mineralocorticoid and glucocorticoid pathways in three patients with GRA. Baseline plasma progesterone, 17 alpha-hydroxyprogesterone, corticosterone, and cortisol were normal in all patients, whereas 11-deoxycorticosterone, aldosterone, and 11-deoxycortisol were above normal. The ratios of both corticosterone/11-deoxycorticosterone and cortisol/11-deoxycortisol were abnormally low, and decreased further 60 min after administration of ACTH-(1-24) (250 micrograms) as an i.v. bolus. A low corticosterone/11-deoxycorticosterone ratio is consistent with an increased aldosterone synthase activity forming aldosterone by corticosterone. Similarly, a decreased cortisol/11-deoxycortisol ratio could reflect enhanced cortisol C18 oxidation. Our findings are in agreement with a hyperfunction of the 11 beta-hydroxylase/aldosterone synthase complex in the adrenal zona fasciculata of GRA induced by the new chimeric gene.

New therapeutic indications based on the antiprogesterone action of RU 486 (Mifepristone) are emerging which require long term administration and raise the question of its safety because of the antiglucocorticoid action of the drug. A trial was designed to assess the antiglucocorticoid effect of RU 486, possible manifestations of peripheral cortisol deprivation, and the adrenocortical and corticotroph reserves. Ten normal male volunteers (aged 21-29 yr) were given RU 486 (200 mg/day) or placebo between 0800-0900 h for 8 consecutive days in a randomized, double blind, cross-over design, with a 1-month interval between the two periods. RU 486 induced overactivation of the pituitary-adrenal axis; baseline values (mean +/- SEM) before and at end of treatment were, respectively: 0800 h plasma cortisol, 147.3 +/- 15.5 and 257.6 +/- 8.8 ng/mL; 0800 h salivary cortisol, 5.8 +/- 1.2 and 15.2 +/- 0.8 ng/mL; nocturnal (2200-0800 h) urinary cortisol, 8.4 +/- 1.5 and 33.7 +/- 11.1 micrograms; and 0800 h plasma ACTH, 29.2 +/- 3.7 and 60.2 +/- 8.4 pg/mL. All of these variations were significantly different from those during placebo treatment (0.0001 < P < 0.03) and disappeared within 4 days after the end of treatment. A daily record of subjective clinical symptoms, body weight and temperature, blood pressure, and heart rate showed neither side-effects nor any significant variation during treatment. Blood electrolyte and eosinophil counts were unchanged; fasting blood glucose was slightly higher at the end of treatment (5.0 +/- 0.2 vs. 4.7 +/- 0.1 mmol/L; P = 0.04). The adrenocortical response to Cortrosyn (0.25 mg, im) was exaggerated during RU 486 treatment (P < 0.006): peak values before and at the end of treatment were, respectively: plasma cortisol, 272.5 +/- 15.2 and 347.1 +/- 20.6 ng/mL; and salivary cortisol, 17.0 +/- 2.2 and 31.1 +/- 3.1 ng/mL. Direct pituitary stimulation (100 micrograms ovine CRH, followed by 1 IU lysine vasopressin over 15 min) also induced exaggerated corticotroph and adrenocortical responses (P < 0.005); peak values before and at the end of treatment were, respectively: plasma ACTH, 147.7 +/- 24.6 and 254.0 +/- 41.3 pg/mL; and plasma cortisol, 231.6 +/- 7.3 and 319.2 +/- 12.3 ng/mL. These data show that 8-day treatment with 200 mg RU 486 daily induces a hormonally detectable antiglucocorticoid effect without clinical symptoms. This state results from reversible cortisol overproduction with preservation of adrenocortical and pituitary reserves.

"Steroid burst therapy" is commonly used for various acute medical conditions, but its suppressive effect on hypothalamic-pituitary-adrenocortical (HPA) function and the time period for recovery of HPA function is not fully known. We therefore evaluated the HPA function in 10 normal adults before and after a short burst of Prednisone (40 mg/three times daily for 3 days, then tapered over the next 4 days). HPA function was evaluated by iv administration of 100 micrograms of ovine CRH (oCRH) and blood samples for ACTH and cortisol assay were obtained at -30,0,10,15,30,60,90, and 120 min. On another day, 250 micrograms synthetic ACTH (Cosyntropin) were given iv and blood samples for cortisol were obtained at 0,30,60, and 90 min. Basal and peak levels of ACTH and cortisol before and 1,2, and 3 weeks after discontinuation of prednisone in response to oCRH iv are shown below (see Table 1). All values are mean (SEM). Peak levels of cortisol after iv administration of Cosyntropin at week 0 were 922(56.8), week 1 899(63.7), week 2 861(70.9), and week 3 855(53.0). There was no significant difference noted in the levels of ACTH and cortisol in response to oCRH before and after prednisone treatment. Pre- and posttreatment responses of cortisol to Cosyntropin administration were also similar. In addition, cumulative responses (area under the curve) and the change from baseline (delta) before and after administration of prednisone were similar for ACTH and cortisol. We conclude that HPA function is normal 1 week after discontinuation of a short burst of prednisone. These findings suggest that administration of additional steroids may not be required during periods of "stress" for those patients who have previously received similar steroid burst therapy, if at least 1 week has elapsed after such treatment was given.

The aim of this double blind placebo-controlled cross-over study was to evaluate the effects of fadrozole, a new oral nonsteroidal aromatase inhibitor, on basal and stimulated cortisol and aldosterone secretion at a daily dosage of 4 mg given for 14 days to eight healthy men. After 2 weeks of treatment, fadrozole, compared with placebo, effectively suppressed plasma estrogen levels (P less than 0.05 at 0800 h), but did not affect glucocorticoid secretion either under basal conditions or after stimulation with ACTH. Basal plasma aldosterone levels were not significantly different with fadrozole treatment compared to those after placebo treatment. However, compared with pretreatment values, basal aldosterone secretion appeared impaired (P less than 0.05). A statistically significant blunting of the responses of plasma aldosterone to ACTH (P less than 0.01) and upright posture (P less than 0.01) after fadrozole compared with placebo treatment further indicated that fadrozole impaired basal aldosterone secretion. This attenuation of aldosterone secretion was accompanied by a rise of PRA in the basal condition (P = 0.05) and after stimulation by 40 mg furosemide (P less than 0.01) and upright posture (P less than 0.01). An increase in deoxycorticosterone was observed after fadrozole treatment compared with pretreatment values (P less than 0.01) and after stimulation with ACTH compared with placebo (P less than 0.05). This study confirms that fadrozole given in daily doses of 4 mg is an effective aromatase inhibitor which does not affect glucocorticoid secretion. However, this dose may induce an impairment of aldosterone secretion which is modest and revealed mainly under specific stimulatory conditions, and does not lead to clinical symptoms of hemodynamic dysregulation or a relevant disturbance of serum electrolytes.

Experimentally induced hyperinsulinemia reduces serum adrenal androgen levels in man, but does not alter cortisol secretion. To determine whether insulin might selectively inhibit adrenal androgen production by suppressing 17,20-lyase activity, ACTH-stimulated androgen secretion was assessed in 10 normal men after an insulin infusion (hyperinsulinemic-euglycemic clamp) or a control saline infusion. For the insulin clamp study, each man received a 2-U (14.4-nmol) insulin bolus dose, followed by a 2.0-mU/kg.min (14.4-pmol/kg.min) insulin infusion for 5 h. An average insulin level of 746 +/- 35 (+/- SE) pmol/L was achieved; serum glucose was maintained at 4.96 +/- 0.03 mmol/L. At the end of the insulin infusion, an ACTH stimulation test was performed, and serum steroid levels were determined 30 and 60 min later. Subjects returned 1-3 weeks later for control studies, during which 0.45% saline was infused at rates matched exactly to the rates of the dextrose and insulin infusions during the insulin clamp studies, and an ACTH stimulation test was performed after 5 h of saline infusion. After the insulin infusion, stimulation by ACTH resulted in a significant rise in the serum molar ratio of 17 alpha-hydroxyprogesterone to androstenedione (from 0.914 +/- 0.110 at zero time to 1.388 +/- 0.278 60 min after ACTH; P less than 0.05), whereas no change occurred in the ACTH-stimulated ratio of these steroids after the saline infusion (1.067 +/- 0.109 at zero time to 1.060 +/- 0.109 60 min after ACTH; P = NS). The insulin-induced change in this steroid ratio was due to a relative increase in precursor (17 alpha-hydroxyprogesterone) and decrease in product (androstenedione) responsiveness to ACTH. Similarly, insulin treatment resulted in a greater than 100% rise in the difference from baseline in the serum molar ratio of 17 alpha-hydroxypregnenolone to dehydroepiandrosterone 30-60 min after ACTH (P less than 0.004), whereas no change in this difference was observed after the saline infusion (P = 0.71). Again, the insulin-induced change in this steroid ratio was due to a relative increase in precursor (17 alpha-hydroxypregnenolone) and decrease in product (dehydroepiandrosterone) responsiveness to ACTH. Of note, insulin treatment altered neither cortisol responsiveness to ACTH nor 17 alpha-hydroxylase activity, as indicated by similar ACTH-stimulated responses in the serum molar ratio of progesterone to 17 alpha-hydroxyprogesterone after the insulin and saline infusions (P = 0.71). Hence, the results of this study indicate that the acute elevation of serum insulin levels into the high physiological range selectively inhibits adrenal 17,20-lyase activity in man.

One to 2% of hyperandrogenic women demonstrate a 17-hydroxyprogesterone (17-HP) level greater than 36.3 nmol/L (1200 ng/dL) after acute ACTH-(1-24) adrenal stimulation, consistent with 21-hydroxylase (21-OH) deficient late-onset adrenal hyperplasia (LOAH). The following study was undertaken to endocrinologically and genetically define hyperandrogenic patients with an exaggerated 17-HP response to ACTH stimulation, and which do not represent LOAH. Of 265 consecutive patients suffering from hirsutism and/or hyperandrogenic oligomenorrhea, 23 (8.7%) demonstrated a 17-HP level 30 min post stimulation greater than 9.6 nmol/L or 316 ng/dL (the upper 95th percentile in 41 eumenorrheic nonhirsute healthy control women). Seven patients or five separate families (1.8% of total) demonstrated poststimulation 17-HP levels consistent with LOAH. Of the remaining 16 patients, the net increment in 17-HP (delta 17-HP0-30) was within normal limits in seven (2.6%) and these women were assumed to have a normal 17-HP adrenocortical response superimposed on an elevated basal level of nonadrenal (e.g. ovarian) origin. In the remaining nine hyperandrogenic patients (3.4%) various abnormalities of adrenal response were noted in all but one patient, consistent with adrenal hyper-responsiveness. One patient demonstrated an 11-deoxycortisol poststimulation level greater than 3-fold the upper 95th percentile of normal, consistent with 11-hydroxylase LOAH and was excluded from further study. Six of these women were available for further genetic characterization, all Caucasian and unrelated. Three were heterozygotes for HLA-B14, three for B40, and one for B35 antigen, HLA-types associated with the inheritance of 21-OH deficiencies. Although, normally there are two 21-OH genes (a pseudogene and a functional gene) present in a 1:1 ratio, we have previously reported a high frequency of 21-OH gene ratio abnormalities in LOAH. All but one of our patients demonstrated an abnormal 21-OH gene ratio. In conclusion, 3.4% of our hyperandrogenic population demonstrated an exaggerated 17-HP increment after ACTH stimulation, not consistent with LOAH or increased extraadrenal 17-HP production. The increased prevalence of HLA alleles known to be linked to inherited defects of 21-OH function and the increased frequency in 21-OH gene ratio abnormalities suggest that a majority of these individuals may be carriers for these genetic disorders. However, the adrenocortical abnormalities noted were more consistent with a generalized hyperreactivity of the adrenal to ACTH stimulation, than a specific enzyme deficiency, implying that carrier status for 21-OH deficiency may be incidental to the hyperandrogenism.

Adrenal response to iv administration of 1-24 ACTH (250 micrograms) was examined in normal volunteers under various conditions. The effect of basal cortisol levels was examined by performing the tests at 0800 h with and without pretreatment with dexamethasone. The effect of time of day was evaluated by performing the tests at 0800 h and at 1600 h, eliminating possible basal cortisol influence by pretreatment with dexamethasone. In the first set of tests, despite significantly different baseline levels, 30-min cortisol levels were not different (618 +/- 50 vs. 590 +/- 52 nmol/L). Afternoon cortisol levels in response to ACTH were found to be significantly higher than morning levels at 5 min (254 +/- 50 vs. 144 +/- 36 nmol/L, p less than 0.01) and at 15 min (541 +/- 61 vs. 433 +/- 52 nmol/L, p less than 0.02). This difference in response was no longer notable at 30 min (629 +/- 52 and 591 +/- 52 nmol/L). We tried also to determine the lowest ACTH dose which will elicit a maximal cortisol response. No difference was found in cortisol levels at 30 and 60 min in response to 250 and 5 micrograms 1-24 ACTH. Using 1 micrograms ACTH, the 30-min response did not differ from that to 250 micrograms (704 +/- 72 vs. 718 +/- 55 nmol/L, respectively). However, the 60-min response to 1 microgram was significantly lower (549 +/- 61 vs. 842 +/- 110 nmol/L, p less than 0.01). Using this low dose ACTH test (1 microgram, measuring 30-min cortisol level), we were able to develop a much more sensitive ACTH test, which enabled us to differentiate a subgroup of patients on long-term steroid treatment who responded normally to the regular 250 micrograms test, but had a reduced response to 1 microgram. The stability of 1-24 ACTH in saline solution, kept at 4 C, was checked. ACTH was found to be fully stable after 2 hs in a concentration of 5 micrograms/ml in glass tube and 0.5 micrograms/ml in plastic tube. It was also found to be fully stable, both immunologically and biologically, for 4 months, under these conditions. We conclude that the 30-min cortisol response to ACTH is constant, unrelated to basal cortisol level or time of day. It is therefore the best criterion for measuring adrenal response in the short ACTH test. The higher afternoon responses at 5 and 15 min suggest greater adrenal sensitivity in the afternoon, but further studies are needed to clarify this issue.(ABSTRACT TRUNCATED AT 400 WORDS)

The putative stimulation of adrenal steroid production by immunoglobulins (Igs) of five patients with pigmented adrenocortical micronodular dysplasia and clinical Cushing's syndrome was investigated. Ascorbate depletion, a process linked to steroid production, was measured by a cyto-chemical bioassay employing guinea pig adrenal explants in organ culture and exposed to IgG from the patients and normal subjects. We also measured cortisol production by these segments during a 5-h culture period using a RIA. For positive reference values we studied the effects of ACTH-(1-39), ACTH-(1-24), ACTH-(11-24), and ACTH-(18-39) on in vitro ascorbate depletion and cortisol production. Both ACTH-(1-39) and ACTH-(1-24) depleted ascorbate and stimulated cortisol production in adrenal cells. The dose-response kinetics of the peptides were bell-shaped; maximal responses were reached in both instances at 1 fmol/L to 10 pmol/L. In all tests, stimulation of in vitro cortisol production was paralleled by ascorbate depletion. ACTH-(18-39) also stimulated ascorbate depletion and cortisol production, but at one concentration only (100 fmol/L), and TSH and LH had no effect. Protein-A-Sepharose-purified IgG preparations of the five patients stimulated ascorbate depletion and/or cortisol production in a dose-dependent fashion; however, the responses occurred over a narrow concentration range (15-150 micrograms IgG/mL culture fluid). These observations support the hypothesis that the hypercortisolism of the syndrome of pigmented adrenocortical micronodular dysplasia is due to circulating Igs that stimulate adrenal steroidogenesis.

Stimulation of aldosterone and corticosterone production by pituitary peptides structurally or biosynthetically related to ACTH was investigated in suspensions of isolated rat adrenal glomerulosa and fasciculata cells, respectively. Three different preparations of highly purified ovine (Li) or human (Chrétien and Orth) beta-lipotropin (beta LPH) were tested. In contrast to synthetic ACTH-(1-24), which stimulated aldosterone secretion at concentrations of 10(-12)-10(-11) M, beta LPH concentrations of 10(-8)-10(-6) M were required for significant stimulation. Stimulation of corticosterone production by beta LPH preparations generally paralleled their aldosterone-stimulating activity, and most steroidogenic activity could be accounted for by immunoreactive ACTH, as determined in two ACTH RIAs. Synthetic human beta LPH-(37-58), which contains the 47-53 heptapeptide sequence common to beta LPH and ACTH, had aldosterone- and corticosterone-stimulating activities similar to those of equimolar concentrations of beta LPH, whereas synthetic fragments of the COOH-terminal (61-91) portion of beta LPH had no steroidogenic activity. These data indicate that part of the slight steroidogenic activity of purified beta LPH preparations is due to contaminating ACTH, and part is due to the intrinsic ACTH-like activity conferred upon beta LPH by the amino acid sequence shared with ACTH. In contrast to ACTH, the concentrations of beta LPH required to stimulate adrenal steroidogenesis were 10(2)-10(5) times greater than normal plasma levels, indicating that physiological pituitary beta LPH secretion has no direct role in regulating the secretion of aldosterone.

The existence of feedback inhibition of ACTH on its own secretion has been postulated. To investigate its existence in man, the effects of synthetic ACTH 1-24 on endogenous ACTH secretion were tested in 13 patients with Addison's disease. Plasma ACTH was measured using an immunoradiometric assay, specific for endogenous ACTH 1-39. Ten patients were given 50 micrograms ACTH 1-24 as a bolus iv dose followed by a 50-microgram infusion in 90 min. Blood samples for ACTH and cortisol assay were obtained at 0, 15, 30, 60, 90, and 120 min. As a control, a saline infusion was given 2 days earlier. Three other patients were given 100 micrograms ovine corticotropin-releasing hormone (oCRH) iv and ACTH 1-24 as described above. Blood samples for ACTH and cortisol assay were drawn every 15 min for 2 hours. A CRH test was performed during saline infusion as a control 2 days earlier. In all patients steroid replacement therapy was maintained during the studies. ACTH 1-24 caused a significant decrease (P less than 0.01) in endogenous plasma ACTH at 15 min compared to saline. oCHR administration markedly stimulated ACTH release in the three patients tested, and the ACTH response to oCRH was completely inhibited by the simultaneous administration of ACTH 1-24. These findings strongly support the presence of ACTH autoregulation in man. The complete inhibition of the ACTH response to oCRH by exogenous ACTH 1-24 provides evidence for ultra-short feed-back inhibition at the pituitary level.

The effect of ACTH administration on plasma CRH levels was studied. In five patients with Addison's disease and three patients with hypopituitarism, bolus iv injection of 0.25 and 0.5 mg ACTH-(1-24) reduced plasma CRH levels (that had become elevated 48 h after discontinuation of corticosteroid replacement) to near-normal levels at 30-60 min in a dose-dependent manner. Plasma immunoreactive beta-endorphin levels were similarly decreased in patients with Addison's disease. ACTH-(1-24) (0.25 and 0.5 mg) injection failed to inhibit plasma CRH levels in five normal subjects. Basal CRH release from the rat hypothalamic median eminence in vitro was inhibited by 0.22 and 2.2 nM ACTH-(1-24) and ACTH-(1-39) in a dose-dependent manner. These results suggest that in the absence of negative feedback control of ACTH secretion by glucocorticoids, ACTH can regulate its secretion by inhibition of hypothalamic CRH release.

A case of fluctuating Cushing's syndrome due to an adrenal adenoma is described. Plasma corticosteroids were frequently low and urinary steroids fluctuated markedly over a 15-month period. Only the response to dexamethasone was consistently abnormal and indicative of Cushings's syndrome.

Controversy surrounds the issue of whether beta-endorphin affects adrenal steroidogenesis. Recent work has both supported and refuted the claim that beta-endorphin stimulates a rise in serum aldosterone. We investigated the role of beta-endorphin in adrenal steroidogenesis by examining its potential modulation of the response of serum cortisol to exogenous ACTH (Cosyntropin). Four of five normal men received: 1) synthetic beta-endorphin (1 microgram/kg X min) for 30 min, followed by a bolus dose of 0.2 micrograms ACTH; 2) beta-endorphin (100 micrograms, iv), followed by 0.2 micrograms ACTH iv; 3) 0.2 micrograms ACTH iv; and 4) beta-endorphin (100 micrograms iv) alone. The integrated cortisol response to exogenous ACTH, calculated as the area under the cortisol response curve, was significantly less when the ACTH infusion was preceded by the 30-min beta-endorphin infusion than when administered alone [163 +/- 50 (SE) microgram/dl X min vs. 282 +/- 51 micrograms/dl X min, respectively; P less than 0.01]. By contrast, there was no difference between the integrated cortisol response to exogenous ACTH alone and exogenous ACTH after the bolus dose of beta-endorphin (282 +/- 51 vs. 293 +/- 39 micrograms/dl X min, respectively). Beta-Endorphin (30-min infusion or 100-micrograms bolus dose alone) caused no change in serum aldosterone, dehydroepiandrosterone, or PRA. Serum PRL levels, however, were raised significantly (P less than 0.05) by the 30-min infusion of beta-endorphin. The infusion and bolus doses of beta-endorphin raised plasma beta-endorphin levels to over 100,000 pg/ml and 5,000 pg/ml, respectively. We conclude that very high plasma levels of beta-endorphin may influence the response of cortisol to ACTH through a direct effect on the adrenal cortex. However, even in disease states such as Addison's and Nelson's diseases, such levels of plasma beta-endorphin are not known to be achieved.

In vitro application of the morphinomimetic met-enkephalin resulted in inhibition of mineralocorticoid production by aldosterone-producing adenomas. Aldosterone, deoxycorticosterone, and corticosterone production by adrenocortical cells isolated from aldosteronomas has been studied under basal conditions and after stimulation with ACTH-(1-24). The blocking effect of met-enkephalin on the rate of aldosterone, deoxycorticosterone, and corticosterone release was significant at a concentration as low as 10(-11) M (P less than 0.001, P less than 0.01, and P less than 0.001, respectively). Dose-dependent inhibition of steroid biosynthesis became more apparent with increasing amounts of met-enkephalin in the incubation medium (10(-11)-10(-5) M); at a concentration of 10(-5) M, met-enkephalin decreased the production of aldosterone by 45%, that of deoxycorticosterone by 51%, and that of corticosterone by 44%. Increased steroid biosynthesis stimulated by ACTH-(1-24) was also significantly blocked by met-enkephalin. In a concentration of 10(-5) M, met-enkephalin produced significant decreases in aldosterone (P less than 0.001), deoxycorticosterone (P less than 0.05), and corticosterone (P less than 0.001) production compared to the peak values obtained after stimulation with 0.85 X 10(-10) M ACTH-(1-24). These data allow us to conclude that the inhibitory effect of met-enkephalin on mineralocorticoid production exerted at the level of the adrenals might be complementary to the factor(s) thought to be involved in the regulation of adrenal steroid production, playing a role similar to that of the biogenic amines originating in the adrenal medulla and regulating the adrenal cortex by a peripheral neurohumoral paracrine mechanism.

Adrenal effluent concentrations of aldosterone were measured along with testosterone, androstenedione, and cortisol in 17 women with idiopathic hirsutism. In the basal state, aldosterone secretion (higher concentrations vs peripheral blood) was demonstrated in 14 out of 16 of the women, in contrast to 8 out of 16 who demonstrated cortisol gradients. Nine women received 0.25 mgm beta 1-24 ACTH im and serial adrenal venous blood samples were obtained over the next 30 minutes. Parallel 30-40-fold increments were noted in aldosterone, androstenedione, and cortisol; testosterone increased only 8-fold. These marked changes in adrenal effluents were not observed in simultaneously monitored peripheral blood. Minimal changes in these steroid concentrations were noted in adrenal and peripheral blood in 7 women who received 2,000 IU hCG. One woman received a pressor dose of angiotensin II, resulting in a marked increase in adrenal vein aldosterone and a simultaneous decrease in cortisol. Since adrenal androgen secretion parallels cortisol, quantification of adrenal androgen secretion rates can be achieved by sampling the adrenal effluent and relating the androgen gradient to that of cortisol at any given time. In contrast, aldosterone secretion is often independent of cortisol, and thus cannot be estimated by comparison of adrenal gradients. ACTH administration, however, invariably stimulated aldosterone secretion, enabling us to quantify the "ACTH-related aldosterone secretion rate" from a comparison of maximal adrenal gradients of aldosterone vs cortisol. In 6 women, "ACTH-related aldosterone" secretion rate averaged 40 mug/day, roughly 20% of the total daily aldosterone secretion rate.

This study describes the interactions between cortisol peaks due to spontaneous episodic release and peaks provoked by external stimuli. Successive and equidistant transitory rises of similar amplitude and duration were produced either by muscular exercise (30 min, 75% VO2max) or by injecting ACTH1-24 (Synacthen: 250 ng) before and after the midday meal-related peak. ACTH1-24 was also injected during sleep before the nocturnal sequence of the major secretory episodes. In all instances, cortisol levels had reverted to basal levels when the second stimulus was applied. ACTH-induced cortisol peaks depressed the subsequent meal-related peaks, the exercise-induced peaks, and the spontaneous secretory episodes at the end of the night, and thus had a strong depressor capacity. When exercise was the prior stimulus, the subsequent meal-related peaks were depressed, but the response to later exercise was not affected. Meal-related peaks and the spontaneous diurnal or nocturnal peaks did not depress the subsequent secretory episodes. These quantitatively comparable cortisol episodes were preceded by ACTH rises whose amplitude and duration were not identical: spontaneous and meal-related ACTH peaks were smaller than the provoked one; exercise-induced ACTH peaks were of longer duration than those after ACTH1-24 injection. The different depressor capacities of similar sized cortisol episodes and the lack of proportionality between spontaneous and provoked ACTH and cortisol peaks suggest that there are separate adrenocortical activation channels, which depend on the origin of the stimulation.

Receptor-mediated uptake of low density lipoproteins (LDL) provides an important source of cholesterol for corticosteroid synthesis by human adrenocortical cells grown in tissue culture. Recent studies have indicated an impaired adrenocortical response to prolonged ACTH stimulation in patients with abetalipoproteinemia (who lack plasma LDL) and in patients with homozygous familial hypercholesterolemia (FH), who have a virtual absence of high affinity LDL receptors. In the present study we examined parameters of adrenocortical function in four women with well characterized heterozygous FH to assess whether a 50% reduction in the number of LDL receptors measured in vitro influenced the response of the adrenal cortex to prolonged stimulation with ACTH. Biochemical studies of the binding, internalization, and degradation of [125I]LDL were undertaken in cultured skin fibroblasts from each patient, and all patients had reduced LDL receptor activity. The adrenocortical response to a 36-h iv infusion of alpha ACTH-(1-24) (Cortrosyn) was evaluated in the four patients with heterozygous FH and in five normal women. Stimulation with iv ACTH resulted in rapid increases in the serum concentrations of cortisol in both groups and plateau concentrations of 55-60 micrograms/dl. The rates of increase and the plateau concentrations were similar in the control and FH patients. Similarly, rates of excretion of 17-hydroxycorticosteroids and cortisol were similar in the normal subjects and FH patients. These results indicate that a 50% reduction in the number of high affinity LDL receptors due to the presence of one abnormal gene at the LDL receptor locus does not result in any impairment in the delivery of cholesterol to the adrenal cortex during conditions of maximal corticosteroid production.

The alpha ACTH-(1-24) threshold dose and the response slope were determined for cortisol (F), delta 4-androstenedione (A), and dehydroepiandrosterone (DHEA) in 10 normal and 16 obese eumenorrheic nonhirsute women matched for age. Each woman received 1 mg dexamethasone at 2300 h and again at 0700 h the next morning. At 0700 h, a continuous alpha ACTH-(1-24) infusion was begun at an initial dose of 30 ng/1.5 m2 body surface area X hr. The ACTH infusion rate was doubled every hour for 5 consecutive h to a maximum dose of 480 ng/1.5 m2 X h. Blood samples were collected for steroid assays before the infusion and at the end of each hour. The ACTH threshold dose was defined as the dose that produced a steroid response significantly above the basal level. The ACTH threshold dose for serum F and DHEA stimulation was not different between the groups, but the threshold dose for A was significantly lower in the obese women. Basal and stimulated serum DHEA to F ratios were significantly higher in the obese women. In both groups, the mean F response slope was significantly higher than that for DHEA, which in turn, was significantly higher than that for A. The mean DHEA response slope was significantly greater in the obese women. The F and A response slopes were not different between the groups. We conclude that the relative responsivity of the steroids to ACTH was the same in both groups: F greater than DHEA greater than A; in the obese women, the ACTH threshold dose for F stimulation was lower (greater sensitivity) than for DHEA or A stimulation; and in the obese women, the ACTH threshold dose for A was significantly lower (increased sensitivity) and the slope of the DHEA response to ACTH was steeper (greater responsivity) than in normal women.

The effect upon steroidogenesis of adding various steroids produced by the placenta was studied in short term cultures of human fetal adrenal cells. The addition of high concentrations (10(3) ng/ml) of estrone or estriol inhibited the production of cortisol, but only the former elicited a parallel increase in dehydroepiandrosterone (DHA) production. Estradiol was effective in inhibiting delta-4-3-ketosteroid production at concentrations of 10-100 ng/ml, levels which approach those found in the fetal circulation, while DHA production was increased at concentrations of 1 microgram/ml. The addition of progesterone (4 microgram/ml) to the medium caused increased production of cortisol and corticosterone, but had no effect on DHA production. Pregnenolone (4 microgram/ml) increased the basal production of DHA and slightly impaired both basal and ACTH-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that the many fetal and placental factors which have been studied to date, only ACTH and estrogens can interact to produce the characteristic fetal pattern of steroidogenesis. Preliminary studies indicate that this effect-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that the many fetal and placental factors which have been studied to date, only ACTH and estrogens can interact to produce the characteristic fetal pattern of steroidogenesis. Preliminary studies indicate that this effect-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that the many fetal and placental factors which have been studied to date, only ACTH and estrogens can interact to produce the characteristic fetal pattern of steroidogenesis. Preliminary studies indicate that this effect of estrogen is not influenced by other peptide hormones such as hCG, human prl, beta-lipotropin, corticotropin-like intermediate lobe peptide, or beta-endorphin. A revised model of the fetoplacental steroidogenic unit is presented which may explain both normal and fetal hyperplasia and postnatal involution of the adrenal cortex and the variations from this pattern seen in apituitary children.

beta-Endorphin recently was proposed as a possible physiological stimulus of aldosterone secretion based on studies in animals. Since human beta-endorphin (beta h-endorphin) does not contain the ACTH-(4-10) homology common to other ACTH-related neuropeptides that stimulate aldosterone, its mechanism of stimulation might differ from that of the other peptides. In the present study, we infused beta h-endorphin into six normal subjects under carefully controlled conditions at dosage levels several orders of magnitude higher than endogenous levels. No increase in plasma aldosterone was found in these subjects ingesting a normal sodium intake despite the fact that other biological actions of beta h-endorphin were manifest. By contrast, an equimolar infusion of ACTH-(1-24) caused a significant increase in plasma aldosterone. These studies do not support a significant role for beta h-endorphin in control of aldosterone secretion in man and are consistent with the concept that the ACTH-(4-10) amino acid sequence, common to ACTH, beta-lipotropin, gamma-lipotropin, beta MSH, and alpha MSH, is a major determinant of their aldosterone-stimulating capacity.

This study was performed to assess the relative contributions of the fetal and definitive zones of the human fetal adrenal gland to "corticoid" (cortisol and perhaps other corticosteroids) and dehydroepiandrosterone sulfate (DHAS) production, and the possible regulatory role of ACTH and the fetal pituitary in the secretion of of these steroids. Corticoid and radioimmunoassayable DHAS or total aromatizable androgen secretion by the isolated definitive and fetal zones of the human fetal adrenal gland between 10-20 weeks gestation has been studied in a superfusion system. Different functional capacities of the two zones were seen; corticoids were found to be secreted primarily by the definitive zone, while DHAS was found to be the main secretory product of the fetal zone. Addition of ACTH (250 ng/ml) or fetal pituitary homogenate produced a 2- to 5-fold stimulation of corticoid production by the definitive zone at all gestational ages studied. DHAS secretion by the fetal zone was also stimulated by ACTH. These results indicate that the definitive and fetal zones of the human fetal adrenal gland at midgestation have the capacity to respond to ACTH with increased corticoid or DHAS secretion, respectively.