ACTH determination in a petrosal sinus venous specimen after corticotrophin releasing factor provides the best clue on the laterality of microadenoma in Cushing's disease

A 42-year-old woman with Cushing's disease was endocrinologically cured after transsphenoidal selective excision of a left-sided microadenoma. Simultaneous samplings from the bilateral inferior petrosal sinuses with ovine corticotrophin-releasing factor (CRF) stimulation were performed preoperatively to evaluate some relations between the localization of a possible microadenoma and the levels of ACTH in inferior petrosal sinuses. The data for the venous samplings were as follows:-(1) The basal levels of ACTH obtained simultaneously from both inferior petrosal sinuses and peripheral vein were about the same. (2) A significant difference, with a high level of ACTH from the ipsilateral side of the microadenoma, was demonstrated after CRF stimulation. (3) The magnitude of increase in ACTH on the contralateral side after CRF was similar to that of the peripheral response. It is recommended that all patients with ACTH dependent Cushing's syndrome and negative radiological findings should have bilateral simultaneous inferior petrosal venous sampling with CRF stimulation.     

Paradoxical Results after Inadvertent Use of Cosyntropin [Adrenocorticotropin Hormone (1-24)] Rather than Acthrel (Ovine Corticotropin Releasing Hormone) during Inferior Petrosal Sinus Sampling

ObjectiveThe use of ovine corticotropin releasing hormone (oCRH) maximizes the diagnostic accuracy of inferior petrosal sinus sampling (IPSS) in patients with adrenocorticotropin hormone (ACTH)-dependent Cushing’s syndrome (CS). oCRH is marketed as ACTHrel and, understandably, may be confused with cosyntropin [ACTH ^(1-24)]. The inadvertent substitution of synthetic ACTH^(1-24) for oCRH (ACTHrel) during IPSS may cause unexpected and misleading results. The aim of this report is to raise awareness of the potential confounding results created when synthetic ACTH^(1-24) is mistakenly used during IPSS.MethodsWe present 3 patients treated at 3 different centers with ACTH-dependent CS in whom ACTH^(1-24) was mistakenly substituted for oCRH (ACTHrel) during IPSS.ResultsIn all patients, there was an abrupt and unexpected decrease in plasma ACTH in the inferior petrosal sinus (IPS) samples after presumptive stimulation with oCRH. Re-evaluation of the patients’ pharmacy records confirmed that synthetic ACTH^(1-24) had been used rather than oCRH during each procedure. Because “sandwich” immunometric assays for ACTH measure the entire pool of endogenous ACTH, the administration of synthetic ACTH^(1-24) artifactually decreases the endogenous plasma ACTH^(1-39) measurement by binding only to the N-terminal antibody raised against ACTH^(1-17) and not to the C-terminal antibody raised against ACTH^(34-39). This results in a lack of a detectable sandwich complex and explains the apparent reduction in ACTH concentration.ConclusionAn abrupt decrease in ACTH during IPSS suggests that synthetic ACTH^(1-24) rather than oCRH (ACTHrel) has been administered. The labeling of oCRH as ACTHrel poses a potential patient safety problem about which endocrinologists, interventional radiologists, and pharmacists should be aware. (Endocr Pract. 2014;20: 646-649)     

Ectopic ACTH syndrome

Ectopic ACTH syndrome represents a cancer-induced amplification of a property [proopiomelanocortin (POMC) peptides production] normally present in the cells from which the cancer originated but with aberrant posttranslational processing of POMC resulting in a greatly elevated secretion of ACTH precursors. The classic ectopic ACTH-producing tumors described in the 1960s were highly malignant but more recently slowly growing tumors such as carcinoids are reported with increasing frequency. Clinical features of patients with ectopic ACTH were analyzed, including biochemical abnormalities, plasma ACTH, cortisol and urinary steroids. Dynamic tests such as high-dose dexamethasone suppression, metyrapone and ovine-CRH (oCRH) stimulation were explored, as well as inferior petrosal sinus ACTH sampling before and after oCRH. Among the tumor markers examined, elevation of ACTH precursors was uniformly present followed by increased output of calcitonin, gut hormones, oncofetal and placental hormones in decreasing order. Since more than 90% of ectopic ACTH tumors are neuroendocrine in nature exhibiting APUD characteristics, their 2 markers, neuron-specific enolase and chromogranins are very useful. The imaging procedures for localization of the tumor ranged from chest X-rays to computed tomography and magnetic resonance of the chest and abdomen. Abdominal ultrasonography was also useful. Finally somatostatin receptor scintigraphy permitted demonstration of unrecognized tumors and/or metastases, even when the tumors were occult. The ACTH content, immunostaining for APUD markers and altered POMC processing were evaluated in ectopic tumors and/or metastases. Occult ectopic ACTH syndrome of more than 4–6 months of symptoms without the emergence of an obvious source was reviewed. Since the tumors are often clinically and biochemically undistinguishable from pituitary-dependent Cushing's disease, inferior petrosal sinus sampling for ACTH after oCRH stimulation established the diagnosis in over 90% of the cases. 60% of the occult tumors were thoracic carcinoids (3/4 bronchial carcinoids), followed by small cell lung cancer and pancreatic neuroendocrine tumors. In 12% the primary etiology was not detected. The rare syndrome of ectopic CRH syndrome (6 published cases) leading to excessive stimulation of the pituitary which became hyperplastic and secreted excessive amounts of ACTH is discussed. Finally, the 12 published cases and 1 unreported patient with ectopic CRH-ACTH tumors were reviewed, the majority being metastatic small cell lung carcinomas, bronchial and thymic carcinoids.     

Ovine corticotropin-releasing hormone stimulation test in patients with chronic renal failure: pharmacokinetic properties, and plasma adrenocorticotropic hormone and serum cortisol responses

The data on the status of the hypothalamic-pituitary-adrenal (HPA) axis in haemodialysis (HD) patients are conflicting. Moreover, a state reminiscent of Cushing's syndrome has been reported in this group of patients. Corticotropin-releasing hormone (CRH), that is produced by the hypothalamus and modulates the secretion of adrenocorticotropic hormone (ACTH), has been shown to be useful as a provocative test of the HPA axis. We investigated the effect of exogenous ovine CRH (oCRH) on plasma levels of ACTH and cortisol in 13 chronic HD patients. The plasma concentrations of immunoreactive CRH following oCRH administration were similar in patients and controls. In all patients, oCRH given intravenously as bolus injection caused a further increase in the already elevated levels of cortisol. The mean basal plasma levels of ACTH were within the normal range. There was, however, a blunted ACTH response to oCRH. We conclude that the HPA axis in chronic HD patients retains the ability to respond to exogenous oCRH. The patterns of the ACTH and cortisol response to this peptide resemble those observed in chronic stress (depression, anorexia nervosa). Besides, the kinetics of disappearance of oCRH indicate that the kidney may not be the major organ that metabolizes oCRH.     

Seasonal effects on plasma cortisol concentrations in the Bedouin buck: circadian studies and response to ACTH

Our work aims at the exploration of cortisol secretion in the Bedouin goat, native to the Algerian Sahara desert, to understand the mechanisms of adaptation to extreme hot climates. In the present study, diurnal and seasonal variations of cortisol concentrations were measured in basal conditions, as well as the response to ACTH stimulation tests across seasons in bucks. The plasma concentrations of cortisol showed no diurnal cycle but a large variation across seasons. The highest levels occurred in summer and winter when the environmental conditions are at their extreme levels. The rectal temperature showed nychthemeral and seasonal variations, and BW was also different across seasons with highest values in summer and lowest in winter. The results obtained after administration of two doses (2 or 10 μg/kg BW) of synthetic ACTH to three different age groups (kids, adults and elderly animals) showed a strong increase in plasma cortisol concentrations under all conditions with maximum levels achieved between 15 and 120 min. The analysis of the area under the cortisol curve showed no significant difference between the responses to the two doses of ACTH and between age groups, but showed seasonal variations with the lowest response in autumn than in other seasons. We conclude that season significantly affects secretion of cortisol in both basal state and under ACTH stimulation. However, the variation of adrenal reactivity to ACTH is not sufficient to explain seasonal differences, and in particular the summer peak in basal circulating cortisol concentrations. Further research should focus on the respective contribution of environmental factors (such as day length, temperature, humidity) and the mechanisms involved in cortisol regulation.     

Evaluation of a method for determining ACTH concentration in samples of serum obtained by catheterization of inferior petrosal sinuses in diagnosis of Cushing's disease]

A method consisting in the catheterization of lower petrosal sinuses aimed at obtaining blood samples for the determination of ACTH concentration has been applied in diagnostically difficult cases of Cushing's disease. The appearance of ACTH concentration gradient between the blood originating from the immediate vicinity of pituitary and the peripheral venous blood confirmed the hypophyseal etiology of hypercortisolemia. The gradient of ACTH concentration between the two petrosal sinuses made possible the localization of a microadenoma in the anterior lobe of pituitary. The diagnostic conclusions obtained by the above method have been confirmed during the surgery.     

Reduction of False-Negative Results in Inferior Petrosal Sinus Sampling with Simultaneous Prolactin and Corticotropin Measurement

ObjectiveTo investigate the value of prolactin as an independent marker of catheter placement to improve the diagnostic accuracy of inferior petrosal sinus sampling (IPSS) in patients with corticotropin-dependent Cushing syndrome.MethodsIn this retrospective cohort study, we reviewed hospital records of patients who underwent IPSS procedures at the Cleveland Clinic between 1997 and 2009. Serum prolactin and plasma corticotropin levels were measured prospectively in peripheral and inferior petrosal sinus (IPS) samples.ResultsForty-one patients underwent 42 IPSS procedures at our institution during the study period. Among35 patients with Cushing disease, 1 patient had erroneous IPSS results: all pre-corticotropin-releasing hormone (CRH) and post-CRH IPS to peripheral (IPS:P) ACTH ratios were less than 2 and less than 3, respectively. Despite radiologic evidence of appropriate IPS catheter placement, concurrent IPS:P prolactin ratios indicated that successful IPS venous sampling was not achieved. A second case with equivocal IPSS results could also be explained by corresponding IPS:P prolactin ratios. During IPSS, all patients with an identifiable ACTH-staining adenoma localizing to 1 side of the pituitary gland (n = 22) who demonstrated absent IPS:P ACTH gradients (< 2 before or < 3 after CRH administration) on the ipsilateral side of the corticotroph adenoma had corresponding IPS:P prolactin ratios less than 1.3.ConclusionsMeasurement of prolactin during IPSS testing may reduce false-negative results in patients with Cushing disease who do not demonstrate an appropriate central-to-peripheral ACTH gradient. In our series, all false-negative IPS:P ACTH ratios had a corresponding IPS:P prolactin ratio less than 1.3. (Endocr Pract. 2011;17:33-40)     

Venous Sampling for Cushing Disease: Comparison of Internal Jugular Vein and Inferior Petrosal Sinus Sampling

Objective: Because magnetic resonance imaging (MRI) fails to detect many adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas, inferior petrosal sinus sampling (IPSS) is considered the gold standard to differentiate Cushing disease (CD) from ectopic ACTH secretion syndrome (EAS). Some authors have suggested internal jugular vein sampling (IJVS) as an alternative to IPSS.Methods: We simultaneously compared IJVS to IPSS in 30 consecutive patients referred for ACTH-dependent Cushing syndrome and equivocal MRI exams. Five sites were simultaneously sampled in each patient (right and left IPS, right and left IJV, and femoral vein) before and after the administration of corticotrophin-releasing hormone or desmopressin. The test was considered consistent with CD when the IPS to peripheral ratio was >2 at baseline or >3 after stimulus and the IJV to peripheral ratio was >1.7 at baseline or >2 after stimulus.Results: In 27 of 30 patients, IPSS results were consistent with a central source of ACTH. Two of the other 3 patients had EAS (one lung carcinoid and one occult), and 1 patient had pathology-proven CD. The sensitivity of IPSS was 96.4%. Only 64.2% of these patients had results meeting criteria for a central source of ACTH by IJVS criteria. Twenty patients with centralizing IPPS have undergone pituitary surgery. Of these, the central origin of excessive ACTH was confirmed with certainty in 16 patients. Among these 16 patients, the IPSS sensitivity was 93.8%, whereas 5 patients had false-negative IJVS (68.7% sensitivity).Conclusion: These results do not support the routine use of IJVS in establishing if the pituitary is the source of excessive ACTH.Abbreviations:ACTH = adrenocorticotropic hormoneCD = Cushing diseaseCRH = corticotrophin-releasing hormoneCS = Cushing syndromeDDAVP = desmopressinEAS = ectopic ACTH secretionIJVS = internal jugular vein samplingIPSS = inferior petrosal sinus samplingJVS = jugular venous samplingMRI = magnetic resonance imaging     

Steroid hormones in the adrenal venous effluents in idiopathic hirsutism under basal and stimulated conditions

Steroid hormone concentrations in the peripheral blood and the adrenal veins were measured in the basal state and after ACTH stimulation in 5 patients with idiopathic hirsutism. The basal concentrations of the steroids in the adrenal veins of the patients with idiopathic hirsutism were not significantly different from a control group of 5 patients catheterized for investigation of pheochromocytoma. Following ACTH stimulation, the concentrations of the steroids in the adrenal veins were also not significantly different in the hirsute and the control groups except for the concentrations of DHA and DHAS which were higher in the patients with idiopathic hirsutism. 17-hydroxyprogesterone (17-OHP) concentrations after ACTH stimulation were lower in the hirsute group compared to the control population. It is concluded that patients with idiopathic hirsutism have a defect in the biosynthesis of cortisol proximal to the action of the 11 beta- and 21-hydroxylase enzymes, deficiencies of which have been previously considered to be the usual causes of hirsutism due to an adrenocortical abnormality. The lower 17-OHP concentrations in the hirsute group can be explained on the basis of deficiency of substrate for the action of the 17-hydroxylating enzyme, consequent to the postulated deficiency of 3 beta-hydroxysteroid dehydrogenase.     

Relationship between plasma profiles of oxytocin and adrenocorticotropic hormone during suckling or breast stimulation in women.

Oxytocin (OT) administration has been shown to inhibit adrenocorticotropic hormone (ACTH)/cortisol secretion in several experimental conditions. In the present study, the plasma OT responses to suckling in 7 lactating women or to mechanical breast stimulation in 6 normally menstruating women (experimental tests) or to sham stimuli in the same subjects (control tests) were measured and correlated with the simultaneous changes in plasma ACTH/cortisol levels. All women showed similar basal levels of OT, ACTH and cortisol, which remained unmodified after sham stimulation. In contrast, both suckling and breast stimulation produced a significant increase in plasma OT levels and a significant decrease in plasma ACTH concentrations. When OT and ACTH data were considered together, a significant negative correlation was found between the OT increase and the simultaneous ACTH decline. Plasma cortisol levels were lower during suckling or breast stimulation than in control conditions. These data show an inverse relationship between plasma OT and ACTH levels during suckling and breast stimulation in humans, suggesting an inhibitory influence of OT on ACTH/cortisol secretion in a physiological condition.     

In vivo regulation of adrenocorticotrophin secretion in the immature ovine fetus. Modulation by ovine corticotrophin releasing hormone and arginine vasopressin

This study investigates the in vivo regulation of ACTH secretion in the immature ovine fetus by AVP and oCRH. Previously we have demonstrated that whilst AVP-containing neurones are present from 42 days, oCRH-containing neurones cannot be detected in the fetal paraventricular nucleus or median eminence until after 90 or 100 days respectively. In acutely exteriorized fetuses aged between 64-90 days (n = 5), a haemorrhagic stress elicited a significant increase (P less than 0.01) in ACTH values. There was also a significant correlation between plasma ACTH and AVP concentrations in these fetuses. In chronically cannulated fetuses less than 100 days (n = 6) injection of AVP (200 ng) significantly elevated fetal plasma ACTH values at 10 min (P less than 0.01) post injection. Simultaneous injection of AVP (200 ng) and oCRH (10 micrograms) into these fetuses produced a plasma ACTH value that was significantly greater at 10 min (P less than 0.05) than the summed response obtained with separate injection of oCRH and AVP. When AVP and oCRH were injection in equimolar amounts to fetuses between 101-118 days, AVP (2 micrograms) was found to have a greater effect on ACTH than was oCRH (2 micrograms). Pretreatment with a specific vascular antagonist of AVP-d(CH2)5Tyr(Me)AVP failed to significantly inhibit the increase in mean arterial pressure associated with AVP (2 micrograms) injection but partially antagonized (P = 0.04) the decrease in fetal heart rate. The antagonist however completely abolished any effect of AVP on fetal plasma ACTH values. This study suggests that AVP most likely acts through receptors in the fetal pituitary with V1 characteristics.     

ACTH sensitivity of isolated human pathological adrenocortical cells: variability of responses in aldosterone, corticosterone, deoxycorticosterone and cortisol production

In vitro aldosterone, deoxycorticosterone, corticosterone and cortisol production of human adrenocortical cells derived from adenomas (Conn's syndrome, Cushing's syndrome), from hyperplastic adrenals (Cushing's syndrome) and from adrenals surrounding aldosteronoma are described. Cells from adenomas causing either Cushing's syndrome or Conn's syndrome harboured the highest basal and ACTH-stimulated corticosteroid production. Adrenocortical cells derived from micronodular hyperplasia causing Cushing's syndrome and cells from cortisol producing adenoma displayed predominantly cortisol and corticosterone secretion both under basal conditions and following stimulation with ACTH. Aldosteronoma cells showed highly variable aldosterone, deoxycorticosterone, corticosterone and cortisol response to ACTH. However, in aldosteronoma cell suspensions, the basal and ACTH-stimulated ratios of aldosterone to cortisol were increased when compared to ratios of steroids produced by cells from other adrenal tissues. Chronic treatment with spironolactone of patients with Conn's syndrome before surgery was associated with a decreased ratio of aldosterone to corticosterone, revealing that 18-hydroxylase in aldosteronoma cells may be inhibited during long-term therapy. Non-tumorous cells isolated from adrenals surrounding aldosteronoma displayed less aldosterone prior to and after stimulation with ACTH than aldosteronoma cells.     

Secretion of 6beta-hydroxycortisol by normal human adrenals and adrenocortical adenomas

Although 6beta-hydroxycortisol (6betaOHF) is usually considered a cortisol metabolite produced by the liver, a few reports suggest that it may also originate from extrahepatic sources. To examine whether human adrenal cells are capable of 6beta-hydroxylating cortisol, we measured 6betaOHF secretion with a radioimmunoassay method in isolated human adrenal cell systems obtained from three normal adrenals, four nonhyperfunctioning adrenocortical adenomas, two adrenal adenomas causing Cushing's syndrome, and five aldosterone (Aldo)-producing adenomas. Cells were examined both under basal conditions and after stimulation with adrenocorticotrophic hormone (ACTH). In addition, 6betaOHF concentrations were determined in inferior vena cava and suprarenal vein plasma samples obtained from the side of nonhyperfunctioning adrenal adenomas (five patients) and aldosterone-producing adenomas (five patients). Under basal incubation conditions, 6betaOHF secretion, expressed as a percent of cortisol secretion, was between 0.5 and 2.0% in normal adrenal cells, between 1.0 and 7% in cells from nonhyperfunctioning adenomas, 12 and 15% in cells from Cushing's syndrome patients, and between 2.6 and 3.9% in cells from aldosterone-producing adenomas. In these cells, increasing doses of ACTH produced a dose-dependent stimulation of both 6betaOHF and cortisol secretion. The 6betaOHF concentration in suprarenal vein samples obtained from the side of adenomas was markedly increased; the suprarenal vein/inferior vena cava 6betaOHF ratios were 13.1+/-2.1 (mean+/-S.E.) in the case of nonhyperfunctioning adenomas and 17.8+/-4.5 in the case of aldosterone-producing adenomas. These results firmly suggest that 6betaOHF is not only a hepatic metabolite, but also a secretory product of human adrenals and that similarly to cortisol, its secretion may be controlled by ACTH.     

The pituitary response to ovine corticotropin-releasing hormone is enhanced in obese men and correlates with insulin resistance.

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis in central obesity has been demonstrated in women. We studied the corticotropin (ACTH) and cortisol response to ovine corticotropin releasing hormone (oCRH) and its association to parameters of adiposity and insulin resistance in a group of 19 healthy obese (BMI > 25 kg/m2) and 9 non-obese men. Relative insulin resistance was assessed by the homeostatic model assessment (HOMA IR). Baseline ACTH was similar, while cortisol was lower in the obese group. The ACTH response to oCRH was significantly higher in the obese group. ACTH incremental area under the curve (iAUC) correlated with age, HOMA IR, and sagittal diameter but not with leptin. In multiple regression analysis, only HOMA IR was an independent predictor of ACTH iAUC. In conclusion, obese men have hyperactivity of the HPA axis at the pituitary level, which appears to be linked to insulin resistance.     

Transfemoral catheterization of the cavernous sinus outflow with comparison of “central” and “peripheral” gonadotropin patterns in bonnet monkeys

Concentrations of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in central (C) samples obtained by transfemorally catheterizing the inferior petrosal sinus of female bonnet monkeys were compared with those in peripheral (P) samples obtained simultaneously from the saphenous veins of two intact and two oophorectomized bonnet monkeys, before, during, and after luteinizing hormone releasing hormone (LHRH) stimulation. Significant differences between central and peripheral gonadotropin concentrations were detected intermittently in the resting state, and tended to be magnified by LHRH administration. In one animal in which LHRH was fortuitously administered during the course of a spontaneous LH surge, a C/P ratio for LH of 12.71, the maximum observed, was obtained. Spectral analysis exhibited periodicity for LH and, to a lesser extent, for FSH in the oophorectomized, but not in the intact, animals.     

Clinical Presentation and Long-Term Outcome of Patients With Ectopic Acth Syndrome Due to Bronchial Carcinoid Tumors: A One-Center Experience

Objective: To describe the diagnostic features and long-term outcome of patients with bronchial carcinoid tumors with ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS), treated in our department.Methods: We studied 10 cases with EAS and histologically confirmed bronchial carcinoid tumors, diagnosed from 1992 until 2006. Diagnosis was based upon blood, urine, radiologic, and interventional tests. Disease status at the time of the last follow-up was the primary outcome measure.Results: Clinical manifestations included Cushingoid features (100%), psychiatric symptoms (90%), hypertension (70%), diabetes/impaired glucose tolerance (40%), osteoporosis (10%), and hypokalemia (10%). The average time from the onset of symptoms until diagnosis was 14.2 ± 17.0 months. None of the patients exhibited a positive cortisol or ACTH response to corticotropin-releasing hormone (CRH) test, and none showed a positive gradient on bilateral inferior petrosal sinus sampling (BIPSS). All tumors were identified by computed tomography and by octreotide scintigraphy in 8 patients. All patients underwent surgical resection of the tumor, and 2 patients had adjuvant radiation therapy. The mean follow-up was 126.6 ± 63.3 months. At latest follow-up, 8 patients were in remission and 2 had recurrence of the EAS; both had a multifocal tumor. The 2 patients submitted to adjuvant radiation therapy were in remission at their latest follow-up, despite local invasion and lymph node metastases.Conclusion: CRH test and BIPSS are the most useful methods in diagnosing EAS. For localization, repeated imaging studies are necessary. Surgical treatment is effective in most cases. Adjunctive radiotherapy may be useful in patients with lymph node metastases. Patients with multifocal disease should be monitored for potential recurrence.Abbreviations: ACTH = adrenocotricotropic hormone BC = bronchial carcinoid BIPSS = bilateral inferior petrosal sinus sampling CD = Cushing disease CRH = corticotropin-releasing hormone CS = Cushing syndrome CT = computed tomography EAS = ectopic ACTH syndrome HDDST = high-dose dexamethasone suppression test HPA = hypothalamic-pituitary-adrenal IPS:P = inferior petrosal sinus to periphery ratio MRI = magnetic resonance imaging     

Comparison of leucine enkephalin and adrenocorticotrophin effects on adrenal function in fetal and adult sheep

At Day 120-125 of gestation equimolar amounts of ACTH and leu-enkephalin injected in vivo provoked similar rises in plasma cortisol concentrations in chronically catheterized fetuses. There was no concomitant change in plasma DHEA concentrations, or in maternal cortisol concentrations. At term (Days 135-140) 2 out of 5 animals responded similarly to both leu-enkephalin and ACTH injections with a rise in plasma cortisol concentrations, but the other 3 animals, in which basal cortisol concentrations had already risen, showed no response to either agonist. In adult sheep, ACTH provoked a significant increase in the plasma cortisol concentrations, but equimolar amounts of leu-enkephalin were without effect. There was a significant output of cortisol in response to ACTH administration by collagenase-dispersed adrenal cells from term sheep fetuses in vitro. Leu-enkephalin had no effect on cortisol output from dispersed adrenal cells when added by itself, or with ACTH. We conclude that leu-enkephalin is able to function as a stimulator of pituitary-adrenal function during fetal life. The lack of effect of leu-enkephalin on adrenal cells implies that its action is exerted not directly at the adrenal gland, but indirectly at the level of the hypothalamus or pituitary through stimulation of the release of other corticotrophic substances.     

Chemical stimulation of the dorsomedial hypothalamus elevates plasma ACTH in conscious rats

The hallmark neuroendocrine response to stress is increased plasma ACTH. Inhibition of neurons in the region of the dorsomedial hypothalamus (DMH) attenuates experimental air stress-induced elevation of heart rate (HR), mean arterial pressure (MAP), and plasma ACTH. We hypothesized that, under basal conditions, stimulation of the DMH would mimic the neuroendocrine and cardiovascular response to air stress. We examined the effects of unilateral microinjection (100-nl vol) of bicuculline methiodide (BMI, 10 pmol), kainate (KA, 1 or 3 pmol), and N-methyl-D-aspartate (5 pmol) into the DMH or the paraventicular nucleus (PVN) on HR, MAP, locomotor activity, and plasma ACTH in conscious rats. Chemical stimulation of the DMH with KA or BMI produced increased locomotor activity and effects on HR, MAP, and plasma ACTH that together mimicked the pattern seen in experimental stress. Similar treatment in the PVN produced only small increases in MAP. Thus activation of neurons in the region of the DMH results in increased secretion of ACTH along with other changes typically seen in experimental stress.     

Effect of cortisol on testosterone production by immature pig Leydig cells.

The direct effects of hydrocortisone (HS) and adrenocorticotropin (ACTH) on testicular testosterone production were studied in purified immature pig Leydig cells in vitro. Leydig cells were obtained from 3- to 4-week-old piglet testes by enzymatical dispersion followed by discontinuous Percoll gradient centrifugation. Leydig cells were treated with HS and ACTH in the absence or presence of luteinizing hormone (LH) after 12 h of incubation. Media were collected 48 h later for testosterone and cyclic adenosine 3',5'-monophosphate (cAMP) measurement. Treatment of Leydig cells with increasing concentrations (0.001-10.0 micrograms/ml) of HS for 48 h resulted in a dose-dependent increase in basal and LH-stimulated testosterone production. Increasing duration (6-72 h) of treatment with HS (100 ng/ml) led to a time-dependent increase in basal and LH-stimulated testosterone production, achieving statistical significance by 48 and 24 h, respectively. HS increased LH-stimulated cAMP production. HS also increased testosterone production induced by (Bu)2 cAMP. Forskolin stimulated testosterone production to an extent comparable to that attained with LH, and HS augmented forskolin-stimulated testosterone production. HS enhanced the conversion of exogenous 17 alpha-hydroxyprogesterone to testosterone, but did not affect the conversion of pregnenolone and progesterone to testosterone, suggesting a specific stimulation of 17,20-desmolase. Porcine ACTH had no influence on basal and LH-stimulated testosterone production. These results suggest that HS directly stimulates immature pig Leydig cell steroidogenesis, at least in part via an enhancement of the generation of cAMP, leading to an increase in the activity of 17,20-desmolase.     

Adrenal contribution to circulating estrogens in woman.

To study the contribution of adrenal glands to circulating estrogens in woman, the concentrations of estrone (E1), estradiol-17 beta (E2), and estriol (E3) in adrenal and peripheral venous blood were measured by radioimmunoassay and the grandular secretion of estrogens after ACTH stimulation was investigated by analyzing the adrenal vein levels of these steroids in patients with breast cancer who were undergoing a therapeutic adrenal operation. Furthermore, adrenal secretion rates of estrogens and cortisol were estimated. It was shown that there existed greater concentrations of estrogens in adrenal vein than in peripheral blood; about 3 times higher for E1 (p less than 0.001), and 2 times higher for E2 and E3 (p less than 0.05). Administration of ACTH caused a significant increase of E1 and E2 concentrations in adrenal venous blood to mean 150% of the basal levels that was comparable to the increase of cortisol. Apparent adrenal secretion rates of estrogens estimated under surgical situation were calculated to be 7.7 +/- 1.7 (M +/- SE) microgram/day for E1, 1.9 +/- 0.3 microgram/day for E2, and 0.3 +/- 0.2 microgram/day for E3, while the secretion rate of cortisol was 52.7 +/- 8.2 microgram/min. The present study demonstrates that the direct adrenal secretion of not only E1, but E2 and E3 contributes to the circulating estrogen levels, and it is suggested that the adrenal glands might be responsible for the relatively important source of estrogen production in the aged woman.