Stimulation by hCRF of C-peptide release in type 2 diabetics during concomitant opioid receptor blockade

Summary Administration of synthetic human corticotropin-releasing factor (hCRF, 2 µg/kg body weight) during simultaneous application of the opioid antagonist naloxone (1.6 mg i.v. bolus, followed by an infusion at a rate of 1.2 mg/h) produced a significant increase in plasma C-peptide levels of six male Type 2 diabetic patients which even exceeded the postprandial values. This stimulatory effect of hCRF/naloxone on plasma C-peptide was less pronounced in six healthy men. hCRF alone did not provoke any reaction of plasma C-peptide in either group.The possibility of a paracrine, CRF-dependent mechanism in pancreatic islets which somehow involves inhibitory opioid receptors is preferentially discussed. Such a mechanism may underlie the stimulatory action of hCRF/naloxone on B cells and would explain the absent reaction of peripheral venous plasma C-peptide to hCRF alone as well as the amplifying effect of simultaneous opioid receptor blockade.Abbreviations ACTH adrenocorticotropic hormone - C-peptide connecting-peptide - CRF corticotropin-releasing factor - hCRF human CRF - oCRF ovine CRF - min minutes - S.D. standard deviation - S.E.M. standard error of the mean This study was supported by the Deutsche Forschungsgemeinschaft (Go 299/3-2)Dedicated to Professor Dr. N. Zöllner on the occasion of his 65th birthday     

Effects of synthetic corticotropin-releasing factor in normal individuals and in patients with hypothalamic-pituitary-adrenocortical disorders

Plasma adrenocortical hormone (ACTH) and cortisol response to four dose levels (25, 50, 100 and 300 micrograms) corticotropin-releasing factor (CRF) were studied in 5 healthy men, and the response to 100 micrograms CRF in 12 patients with various disorders of the hypothalamic-pituitary-adrenocortical function. In normals, mean plasma ACTH and cortisol concentration rose at all dose levels of CRF and peaked at 30 and 60 min respectively. The increment in plasma cortisol at 60 and 90 min was significantly higher on 100 and 300 micrograms CRF than on 25 micrograms, but the total cortisol concentration was not. Seven patients had Cushing's syndrome. In 2 patients with adrenocortical carcinoma the basal plasma ACTH was suppressed. After CRF a small increase was seen in plasma ACTH and cortisol in one patient successfully treated with mitotane, while the other patient did not respond. In 1 patient with ectopic ACTH syndrome an increase in plasma ACTH 15 min after CRF was not accompanied by any increase in plasma cortisol. One patient with bilateral multinodular adrenocortical hyperplasia did not respond to CRF. The plasma ACTH and cortisol response to CRF was supernormal in 2 patients with Cushing's disease, while a third patient responded in the normal range. In 2 patients with Nelson's syndrome the plasma ACTH response was excessive. Two out of three hypophysectomized patients did not respond to CRF, while one patient with a slightly positive response to hypoglycemia also responded (subnormally) to CRF. Our data indicate that CRF in doses of 50-100 micrograms will be a valuable substance in the differential diagnosis of Cushing's syndrome. Some overlap in the response is, however, seen between patients with Cushing's disease and other patients with Cushing' syndrome. CRF will possibly be of value also for the diagnosis of secondary adrenocortical failure.     

The corticotropin-releasing factor stimulation test. An aid in the evaluation of patients with Cushing's syndrome

We investigated the effect of exogenous corticotropin-releasing factor on plasma levels of ACTH and cortisol in 13 patients with ACTH-secreting pituitary adenomas (Cushing's disease) and in 9 patients with other forms of Cushing's syndrome. In all patients with Cushing's disease, ovine corticotropin-releasing factor, given intravenously as a bolus injection (1 microgram per kilogram of body weight), caused a further increase in the already elevated levels of ACTH and cortisol. Successful transphenoidal adenomectomy was followed as early as one week after surgery by normalization or near-normalization of the ACTH and cortisol responses to corticotropin-releasing factor. On the other hand, patients with the ectopic ACTH syndrome, who also had high basal plasma concentrations of ACTH and cortisol, had no ACTH or cortisol responses to corticotropin-releasing factor. This difference in responsiveness between these two patient groups cannot be explained on the basis of different metabolic clearance rates of exogenous corticotropin-releasing factor, as shown by similar disappearance curves of immunoreactive corticotropin-releasing factor from plasma. Patients with Cushing's syndrome of adrenal origin who were hypercortisolemic during testing had undetectable plasma levels of ACTH and no ACTH or cortisol responses to corticotropin-releasing factor. We conclude that stimulation of the pituitary-adrenal axis with corticotropin-releasing factor may be useful in differentiating pituitary from ectopic causes of Cushing's syndrome.     

The role of vasopressin in the nicotine-induced stimulation of ACTH and cortisol in men

Summary Experimental evidence indicates that arginine vasopressin (AVP) contributes to the release of ACTH under certain conditions. The present study investigates the role of vasopressin as a secretagogue of ACTH during cigarette smoking or nicotine infusion with additional injection of corticotropin releasing hormone (CRH) and using the specific AVP antagonist d(CH₂)₅Tyr(Me)-AVP. We first tested the effect of the AVP antagonist (10 g/kg body weight i.v.) on ACTH and cortisol release following cigarette smoking in 15 healthy young male smokers. Smoking led to marked increments in plasma nicotine and to a small rise in plasma ACTH and cortisol. Mean plasma ACTH and cortisol levels were at no time significantly altered by the antagonist. This might be due to a slight agonistic effect of the AVP antagonist, to high interindividual variability of the ACTH and cortisol responses after smoking or to a neglegible role of AVP in smoking-induced ACTH release. In a second study we performed the following tests in six healthy male non-smokers: (1) nicotine infusion (1.0 g/kg body weight per min); (2) CRH i.v. (100 g); (3) AVP antagonist i.v. (5 g/ kg); (4) nicotine infusion plus CRH i.v.; (5) nicotine infusion plus AVP antagonist i.v. ; (6) nicotine infusion plus CRH and AVP antagonist i.v.; and (7) sham infusion. Nicotine infusion led to greater increments of AVP, ACTH and cortisol than smoking without causing nausea. Peak nicotine levels after nicotine infusion were lower than after smoking. The AVP antagonist in the reduced dosage given alone had no effect on hormone levels. However, it slightly attenuated the effect of nico tite on ACTH and cortisol (P<0.05, ANOVA). Nicotine and CRH given together stimulated AACH and cortisol in a less than additive manner. The combined effect of nicotine and CRH was not inhibited by the antagonist. Our results indicate that the effect of nicotine on ACTH and cortisol may be partly mediated by hypothalamic AVP. Nicotine may also enhance CRH release by stimulating acetylcholine receptors of hypothalamic CRH neurons.Abbreviations ACTH adrenocorticotropic hormone - ANOVA analysis of variance - AVP arginin vasopressin - CRH corticotropin releasing hormone - K⁺a potassium; d (CH₂)₅ Tyr(Me)- - AVP vasopressin (V₁)-antagonist Supported by a grant from Forschungsrat Rauchen und Gesundheit     

Naloxone in treatment of circulatory shock resistant to conventional therapy

Summary The effect of naloxone (4.4–5.9 mg i.v.) was evaluated in 10 patients with circulatory shock (sepsis,n=7; intoxication,n=1; cardiogenic shock,n=2) not responding to full conventional therapy. In addition, we measured plasma ACTH and immunoreactive -endorphin before and 60 min after administration of naloxone and compared the results with hormone concentrations in 10 intensive care patients without shock. Only in two patient with septic shock a transient increase (duration 15 min and 60 min, respectively) of systolic blood pressure was observed, while naloxone was ineffective in the remaining eight patients. No adverse effects of naloxone were found. Plasma ACTH and immunoreactive -endorphin concentrations in patients with shock were not different from those in controls (ACTH, 79±28 vs 120±60 pg/ml; immunoreactive -endorphin, 952±262 vs 1,070±378 pg/ml).Our findings suggest that naloxone in a single dose of 4.4–5.9 mg i.v. does not improve the management of circulatory shock unresponsive to conventional treatment. -endorphin seems to play no major role in the hypotension of shock.Abbreviations ACTH Adrenocorticotrophic hormone - HD intermittent hemodialysis - HF heart rate - ir immunoreactive - RR_syst systolic blood pressure Supported by Landesamt für Forschung, NRW     

Plasma cortisol activity in rats under conditions of chronic stress supplemented with resveratrol

Objective:

To determine the activity of cortisol in rats treated with exogenous adrenocorticotropic hormone (ACTH) and a resveratrol supplement.

Methods:

Forty-eight adult female rats and 16 male rats of the strain (Rattus norvegicus) that were three months old and with body weights ranging from 200 to 250 g for females and 300 to 350 g for males were used and kept in controlled environmental conditions: temperature of 20±2° C and light-dark cycles of 14 and 10 hours. They were fed a balanced diet and had free access to water. The rats were randomly divided into four groups: group 1 - was treated with 5 µg/kg of ACTH i.p. every twelve hours; group 2 - received the same treatment with ACTH plus a grape extract supplement (resveratrol) of 40 mg/kg; group 3 - only received grape extract (resveratrol); and group 4 - received a saline solution (0.9%) i.p. and oral, and served as controls. The experimental design was a 2×2 factorial with two levels ACTH and two polyphenol levels (grape extract).

Results:

No significant differences were found in blood cortisol concentrations, by day and gender, or by treatment effects (0.75 µg/dL ± 0.11; p <0.001).

Conclusion:

Results suggest that chronic stress and consumption of resveratrol did not directly alter levels of plasmatic cortisol in either stressed or unstressed rats. It was concluded that the given dosage levels of ACTH possibly did not produce sufficient stimulation of the adrenal gland for these animals.     

Effects of high-dose inhaled fluticasone propionate on the hypothalamic-pituitary-adrenal axis in asthmatic patients with severely impaired lung function.

BACKGROUND: The effects of high-dose fluticasone propionate therapy on dynamic cortisol stimulation in severe asthma are unknown. OBJECTIVE: To evaluate the human corticotropin-releasing factor (hCRF)-stimulated plasma cortisol response to fluticasone propionate therapy in severe asthmatic patients with impaired airway caliber (forced expiratory volume in 1 second [FEV1] < 60% of predicted) and in control subjects. METHODS: Ten severe asthmatic patients (mean FEV1, 47% of predicted) and 10 controls (mean FEV1, 104% of predicted) received fluticasone propionate, 2,000 microg/d, via a 750-mL primed spacer for 2 weeks. Plasma cortisol levels before and after hCRF stimulation and overnight 10-hour urinary cortisol excretion corrected for creatinine concentration (OUCC) were measured at baseline after washout and 12 hours after the last dose of fluticasone propionate. RESULTS: Baseline values before fluticasone propionate use were not significantly different in asthmatic patients vs controls for plasma cortisol before and after hCRF stimulation and OUCC. Comparing values at baseline vs after fluticasone propionate use, there was no significant suppression of plasma cortisol levels before (378.2 vs 357.4 nmol/L) or after (510.5 vs 507.9 nmol/L) hCRF stimulation or OUCC (8.2 vs 7.5 nmoL/mmoL) in asthmatic patients. In controls, all outcomes were significantly suppressed comparing values before vs after fluticasone propionate therapy: plasma cortisol levels before (423.5 vs 200.2 nmol/L; P = .002) and after (503.5 vs 291.1 nmol/L; P = .001) hCRF stimulation and OUCC (6.5 vs 2.4 nmol/mmol; P = .002). CONCLUSION: Patients with severe persistent asthma and impaired airway caliber seem to be protected from developing systemic adverse effects with high-dose fluticasone propionate therapy, as evaluated by basal and dynamic measures of hypothalamic-pituitary-adrenal axis activity.     

Stress induces CRF release in the paraventricular nucleus, and both CRF and GABA release in the amygdala

In the hypothalamus, corticotropin-releasing factor (CRF) initiates the hypothalamic-pituitary-adrenal (HPA) axis response to stress, resulting in the release of glucocorticoids, including cortisol. Extrahypothalamic CRF, particularly in the limbic system, also appears to play a role in the stress response. To further define brain CRF response to stress, immunosensor-based microdialysis probes were used to measure the extracellular levels of CRF in the paraventricular nucleus of the hypothalamus (PVN) and in the amygdala of sheep during a predator (dog) exposure stress. In addition, gamma amino butyric acid (GABA) was measured in the amygdala and cortisol was measured in venous blood. Exposure to the predator stress increased CRF in the PVN and both CRF and GABA in the amygdala. These were followed in time by a rise in venous cortisol. Application of a CRF antagonist to the amygdala, immediately prior to stress, had a small effect on the subsequent observed stress responses. This treatment, however, significantly reduced the responses to a repeat stress administered 2 days later, compared to nontreated animals. Application of a GABA antagonist to the amygdala prior to stress had no effect on the subsequent observed stress response but increased the response to the stress repeated 2 days later. Perfusion with 4-aminopyridine, a neuronal depolarising agent, into the PVN induced a release of CRF accompanied shortly thereafter by a small increase in CRF in the amygdala, and 5-10 min later by an increase in venous cortisol. Perfusion into the amygdala increased the levels of both CRF and GABA but had no effect on either PVN CRF or venous cortisol. These data support roles for both the PVN and amygdala in stress responsiveness. It suggests further that actions at the amygdala can strongly influence subsequent responsiveness to a further stress, mediated in part by both CRF and GABA actions.     

Synergistic interaction of corticotropin releasing factor and arginine vasopressin on adrenocorticotropin and cortisol secretion in Macaca fuscata

Plasma immunoreactive CRF measured by radioimmunoassay decreased rapidly after intravenous injection of synthetic ovine corticotropin releasing factor (CRF) and showed a bi-exponential decay curve in five macaca fuscatas. Half lives of plasma immunoreactive CRF were 5.8 +/- 1.4 (Mean +/- SEM) min for the fast component and 38.3 +/- 2.4 min for the slow component. A bolus injection of 5 micrograms/kg CRF significantly increased the plasma cortisol level. CRF at 5 micrograms/kg induced a delayed response of ACTH and cortisol. Arginine vasopressin (AVP) at 0.5 micrograms/kg induced a slight increase in plasma ACTH and cortisol, but AVP at 0.1 micrograms/kg evoked no significant increase. When 0.5 micrograms/kg CRF and 0.1 micrograms/kg AVP were administered simultaneously, significant ACTH and cortisol responses occurred. The results indicate that CRF and AVP act synergistically to stimulate ACTH secretion in vivo.     

Endocrine activity of the “silent” adrenocortical adenoma is uncovered by response to corticotropin-releasing hormone

Summary The purpose of this study was to ascertain whether the pituitary-adrenal responses to human corticotropin-releasing hormone (hCRH) in non-functioning adrenocortical adenoma would uncover a functional activity in these adrenal nodules. Eleven patients with incidentally discovered silent adrenocortical adenoma and eleven controls were studied. The initial clinical and laboratory examination, including an overnight 1 mg dexamethasone suppression test, revealed no abnormalities in any of the subjects. IR-ACTH and serum steroids (F, S, P, 17OHP, 18OHB, and aldosterone) were normal in both controls and patients. After pulse IV injection of 100 g hCRH, the cortisol response was significantly exaggerated (P=0.01). Stimulated plasma ACTH levels were, however, significantly lower in patients than in controls (P=0.01), indicating counter-feedback regulation of cortisol. The peak cortisol/peak ACTH ratio (F_max/ACTH_max) in the patients was significantly elevated (26.8±4.37 nmol/ng vs. 14.6±2.16 nmol/ ng,P=0.02). Two further patients with incidentally discovered pre-Cushing's adrenocortical adenoma displayed an even higher ratio (43.5 and 45.5 nmol/ng). In established Cushing's syndrome due to an autonomous adrenocortical adenoma, suppression of ACTH and of the ACTH response to hCRH occurs with a very high basal cortisol/ basal ACTH ratio. Our findings suggest some functional activity even in clinically silent adrenocortical adenoma. Response to hCRH uncovers a continuous spectrum between adrenocortical adenoma, pre-Cushing's, and Cushing's syndrome.Abbreviations ACA adrenocortical adenoma - ACTH adrenocorticotropin - DHEAS Dehydroepiandrosterone sulfate - F cortisol - hCRH human corticotropin releasing hormone - P progesterone - S 11-deoxycortisol - 17OHP 17-hydroxyprogesterone - 18OHB 18-hydroxy-corticosterone     

Central CRF, urocortins and stress increase colonic transit via CRF1 receptors while activation of CRF2 receptors delays gastric transit in mice

Recently characterized selective agonists and developed antagonists for the corticotropin releasing factor (CRF) receptors are new tools to investigate stress-related functional changes. The influence of mammalian CRF and related peptides injected intracerebroventricularly ( i.c.v. ) on gastric and colonic motility, and the CRF receptor subtypes involved and their role in colonic response to stress were studied in conscious mice. The CRF₁/CRF₂ agonists rat urocortin 1 (rUcn 1) and rat/human CRF (r/h CRF), the preferential CRF₁ agonist ovine CRF (oCRF), and the CRF₂ agonist mouse (m) Ucn 2, injected i.c.v. inhibited gastric emptying and stimulated distal colonic motor function (bead transit and defecation) while oCRF_9–33OH (devoid of CRF receptor affinity) showed neither effects. mUcn 2 injected peripherally had no colonic effect. The selective CRF₂ antagonist astressin₂-B ( i.c.v. ), at a 20 : 1 antagonist: agonist ratio, blocked i.c.v. r/hCRF and rUcn 1 induced inhibition of gastric transit and reduced that of mUcn 2, while the CRF₁ antagonist NBI-35965 had no effect. By contrast, the colonic motor stimulation induced by i.c.v. r/hCRF and rUcn 1 and 1h restraint stress were antagonized only by NBI-35965 while stimulation induced by mUcn 2 was equally blocked by both antagonists. None of the CRF antagonists injected i.c.v. alone influenced gut transit. These data establish in mice that brain CRF₁ receptors mediate the stimulation of colonic transit induced by central CRF, urocortins (1 and 2) and restraint stress, while CRF₂ receptors mediate the inhibitory actions of these peptides on gastric transit.     

Different therapeutic efficacy of ketoconazole in patients with Cushing's syndrome

Summary The property of ketoconazole to inhibit adrenal biosynthesis of cortisol was used in a clinical study of 14 patients with Cushing's syndrome (pituitary-dependent Cushing's disease,n=10; adrenocortical adenoma,n=2; adrenocortical carcinoma,n=1; ectopic ACTH syndrome,n=1). Five patients were treated in a short-term manner (1000 mg over 24 h) and nine patients for a longer period (600 mg/die from 1 week up to 12 months). After short-term administration of ketoconazole, serum cortisol levels fell distinctly only in the patient with adrenocortical adenoma, but not at all or only slightly in the other patients, whereas serum levels of progesterone and 11-deoxy-compounds increased markedly in all patients, with the exception of the patient with adrenocortical carcinoma. Plasma ACTH levels increased in the patients with Cushing's disease but not in the patients with tumor. After long-term treatment of three patients with Cushing's disease over 3, 10, and 12 months, the clinical signs of hypercortisolism persisted or were only slightly ameliorated. In these three patients as well as in three other patients with Cushing's disease treated for a shorter period of 1 to 4 weeks, serum and urinary cortisol levels decreased, but were not normalized, whereas plasma ACTH levels increased variably. Only in one patient with Cushing's disease, in the second patient with adrenocortical adenoma, and in the patient with ectopic ACTH syndrome, serum and urinary cortisol levels returned to normal. We concluded from our data, that the antimycotic drug inhibits biosynthesis of cortisol by blocking adrenal 11- and 17-hydroxylase activity. This effect was compensated in part by a rebound increase of pituitary ACTH secretion in most patients with Cushing's disease. Therefore, ketoconazole treatment is above all effective in patients with Cushing's syndrome due to an adrenal tumor or in patients with ectopic ACTH syndrome, who cannot respond with an increased pituitary ACTH secretion.Abbreviations ACTH Adrenocorticotropic hormone - AA Adrenocortical adenoma - AC Adrenocortical carcinoma - B Corticosterone - CRH Corticotropin-releasing hormone - EAS Ectopic ACTH syndrome - PDCD Pituitary-dependent Cushing's disease - P Progesterone - 17OH-P 17-hydroxyprogesterone - RIA Radioimmunoassay - S 11-deoxycortisol - DOC 11-deoxycorticosterone     

Human corticotropin-releasing factor (hCRF) is a potent respiratory analeptic

Summary During intravenous corticotropin-releasing factor stimulation tests we observed a deepening of the tidal volume in 35 patients. To investigate this presumed respiratory stimulation we measured respiratory parameters in 12 healthy male volunteers in a single-blind placebo-controlled trial. The intravenous 60-s infusion of 100 µg of human corticotropin-releasing factor induced a very potent respiratory stimulation in every subject: respiratory minute volume (mean ± S.D.) increased by 81% from 6.319±0.577 to 11.464±1.264 liters per min (P<0.001), whereas there was only a slight rise in the mean respiratory rate from 12.4±3.0 to 14.7±2.7 breaths per min (P<0.001). Mean tidal volume increased from 531±105 to 809±175 ml (P<0.001). Mean end-tidal partial pressure of carbon dioxide decreased (P<0.001) from 40.3±1.2 to 33.4±1.2 mmHg, whereas mean end-tidal partial pressure of oxygen increased (P<0.001) from 93.2±5.4 to 113.5±5.4 mmHg. After 10 to 20 min both end-tidal carbon dioxide and oxygen partial pressures returned to the baseline values. The placebo had no measurable effects.We conclude that human corticotropin-releasing factor is a potent respiratory stimulant. With 100 µg the resting respiratory minute volume increases by 81%. These data point to the possible importance of the corticotropin-releasing factor as a useful adjunct in the management of patients with alveolar hypoventilation.Abbreviations hCRF human corticotropin-releasing factor - P_ETCO₂ end-tidal partial pressure of carbon dioxide (the last portion of the V_T during expiration, called end-tidal volume, contains CO₂ from the alveolar region) - P_ETO₂ end-tidal partial pressure of oxygen - minute volume - V_T respiratory tidal volume     

Effect of selection for behavior on pituitary-adrenal axis and proopiomelanocortin gene expression in silver foxes (Vulpes vulpes)

Silver foxes from a commercial population (farm bred or unselected for behavior control) and from populations selected for tame behavior and enhanced aggressiveness towards man have been investigated. Plasma cortisol and adrenocorticotropic hormone (ACTH) levels, pituitary ACTH levels, POMC gene expression in the anterior pituitary, and corticotropin-releasing factor (CRF) gene expression in the hypothalamus were assessed. The results indicate that the males from the tame-behavior group have lower plasma cortisol and ACTH levels and POMC gene expression in the anterior pituitary in response to capture and handling in comparison with unselected ones. Foxes from the aggressive behavior group also have lower POMC expression, although plasma cortisol and ACTH levels remain the same as in unselected ones. The three groups of animals show no significant changes in the ACTH level in the pituitary and CRF expression in the hypothalamus.     

Presence of pro-opiomelanocortin peptides and corticotropin-releasing factor in human placenta

Immunoreactive adrenocorticotropin (ACTH), beta-endorphin (BEP) and corticotropin-releasing factor (CRF) were detected in human term placenta obtained from elective Caesarian surgery. The concentrations of ACTH, BEP and CRF in placenta detected by radioimmunoassay (RIA) were 2.83 +/- 0.36, 0.52 +/- 0.05 and 0.56 +/- 0.15 ng/g wet weight of tissue respectively. Pro-opiomelanocortin (POMC) peptides were also detected in the amnion and chorion membranes and in the decidua. The concentrations of ACTH were 1.72 +/- 0.20, 4.43 +/- 0.39 and 5.80 +/- 0.17 ng/g and the levels of BEP were 0.42 +/- 0.18, 0.65 +/- 0.20 and 3.66 +/- 1.10 ng/g in the amnion, chorion and decidua respectively. In contrast to placenta, immunoreactive CRF was not detected in the amnion, chorion and decidua. Immunoreactive N-acetylated BEP was also not detected in all the placental subfractions. Comparison of the amounts of both ACTH and BEP in the various placental components indicated the following distribution: decidua > chorion > placenta > amnion. In decidua, POMC peptides were present in an equi-molar ratio but in the other three placental fractions, ACTH levels were three to five-fold higher than BEP. In immunohistochemical studies, only a positive staining for ACTH was obtained for decidua. Our results confirm the presence of POMC peptides and CRF in placenta and their physiological roles in pregnancy and parturition.     

Corticotropin releasing factor (CRF)-stimulation test in normal controls and patients with disturbances of the hypothalamo-pituitary-adrenal axis

Summary Intravenous application of 100 µg synthetic ovine corticotropin releasing factor (CRF) led to stimulation of ACTH-secretion in nine normal controls, with a maximum 30 min after CRF. Cortisol, corticosterone, cortisone and 11-deoxycortisol increased with a maximum at 60 min after CRF, whereas no rise was seen in aldosterone, 11-deoxycorticosterone, 17--hydroxyprogesterone, progesterone, DHEA-S and testosterone. The specificity of CRF-stimulation was also shown by unchanged TSH, LH, FSH, hGH, prolactin and thyroid hormone levels, als well as unchanged insulin and gastrin levels. No serious side-effects were observed during the test period and afterwards.CRF-tests were performed in ten patients with disturbances of the hypothalamo pituitary adrenal axis (HPAA). Preliminary findings show hyperresponsiveness of ACTH in all situations of ACTH-hypersecretion (two patients with Cushing's disease, one patient with Nelson's syndrome, and one with Addison's disease). In contrast, one patient with successful microadenomectomy showed no response of ACTH to CRF, whereas in another patient with a macroadenoma ACTH and cortisol-levels still increased postoperatively. Divergent patterns in ACTH-responsiveness to CRF were seen in four patients with secondary adrenal insufficiency, allowing the localization of the defect. These data point to the possible importance of the CRF-test as a differential diagnostic tool and prognostic factor in diseases of the HPAA.Mit Unterstützung der Deutschen Forschungsgemeinschaft (Sonderforschungsbereich 51)     

Adrenocorticotropin hormone, beta-endorphin and cortisol responses to oCRF in melancholic patients.

Several authors have reported attenuated adrenocorticotropin hormone (ACTH) responses to corticotropin releasing factor (CRF) administration in melancholic patients as compared with healthy controls. In order to explore the integrity of the hypothalamic-pituitary-adrenal (HPA)-axis in melancholics, we examined the following parameters in 98 subjects: the ACTH; beta-endorphin; and cortisol responses to ovine CRF (oCRF) (100 micrograms/i.v.); and the postdexamethasone cortisol values. We found significant lower CRF-induced ACTH responses in melancholic patients as opposed to healthy controls and minor depressives, while major depressives occupied an intermediate position. The psychopathological correlates of the blunted CRF-induced ACTH responses were feelings of worthlessness, self-reproach, or excessive guilt. The CRF-stimulated beta-endorphin and cortisol response did not differ between the study samples. Higher baseline plasma cortisol was associated with attenuated CRF-induced ACTH responses, but these effects were not pertinent to melancholia. There were no relationships between the disordered oCRF test results, and postdexamethasone cortisol values, age, body size, sex and severity of illness. The diagnostic power of the oCRF and the dexamethasone suppression test for melancholia is enhanced when both test results are combined.     

Corticotropin-releasing factor receptor antagonist infused into the locus coeruleus attenuates immobilization stress-induced defensive withdrawal in rats

It has been proposed that corticotropin-releasing factor (CRF) released during stress in the region of the locus coeruleus (LC) induces changes in behavior that are typical indices of anxiety. The experiments tested the ability of a CRF antagonist, hCRF_9–41, to attenuate stress-induced defensive withdrawal in rats. 1 μg of hCRF in 300 nl was infused bilaterally in the LC of rats 10 min prior to 30 min immobilization. The apparatus consisted of a small chamber set on one side of a 1 m open field, into which the rat was placed to start the test. Restraint induced defensive withdrawal in rats familiar with the apparatus and significantly increased latency time to emerge from the chamber, total time and mean time spent in the chamber. Infusion of hCRF into the LC prior to restraint significantly decreased total and mean time spent in the chamber comparing to stressed animals. These results are consistent with anatomical, electrophysiological and neurochemical evidence that CRF receptors located in, or close to, the LC region influence behaviors induced by stress.     

Nonhypnotic low-dose etomidate for rapid correction of hypercortisolaemia in cushing's syndrome

Summary We determined the adrenostatic potential of low-dose nonhypnotic etomidate in six patients with Cushing's syndrome (ectopic Cushing's syndrome,n=2; Cushing's disease,n=3; bilateral adrenal adenoma,n=1). Etomidate was given as a continuous infusion for 32 h in a dose of 2.5 mg/h (n=5) or 0.3 mg/kg/h (n=3), respectively. Saline was given during a control period. The responsiveness to exogenous ACTH was studied during placebo and 7 and 31 h after commencing etomidate by administration of 250 µg 1–24 ACTH i.v. Etomidate (2.5 mg/h) led to a consistent decrease in serum cortisol in all patients from a mean of 39.4±13.3 to 21.1±5.7 µg/dl after 7 h (P<0.05 compared with placebo). After 24 h cortisol was reduced further to a mean steady state concentration of 12.3±5.7 µg/dl (P<0.05). At the end of the infusion period the cortisol increase in response to ACTH was reduced but not abolished. In contrast, a dose of 0.3 mg/kg/h etomidate induced unresponsiveness of serum cortisol to exogenous ACTH within 7 h. However, sedation was observed in two out of three patients at this dose, while during etomidate in a dose of 2.5 mg/h no side effects were seen. We conclude that low-dose non-hypnotic etomidate reduces serum cortisol to within the normal range in patients with Cushing's syndrome. The possibility to dissociate the adrenostatic effect of etomidate from its hypnotic action, the absence of side effects, and the i.v. route suggest that etomidate in a dose of 0.04–0.05 mg/kg/h may become the drug of choice for rapid initial control of hypercortisolism.Abbreviations ACTH adrenocorticotrophic hormone - CD Cushing's disease - CS Cushing's syndrome     

Combined dexamethasone suppression–corticotrophin-releasing hormone stimulation test in medication-free major depression and healthy volunteers

Background

The hypothalamic–pituitary–adrenal (HPA) axis is dysfunctional in a subgroup of mood disorders.

Methods

We compared cortisol and adrenocorticotropic hormone (ACTH) responses in major depression and healthy volunteers to the combined dexamethasone suppression–corticotrophin-releasing hormone stimulation (DEX–CRH) test. Unlike other published studies, the study patients were medication-free and the healthy volunteers did not have first-degree relatives with a mood or psychotic disorder. Demographics, DSM-IV diagnoses and other clinical parameters were evaluated in major depressive disorder (MDD) and healthy control groups. Participants received an oral dose of 1.5 mg dexamethasone at 11 pm the day before CRH administration. On the following day, at 3 pm, 100 µg of ovine CRH was infused. Blood samples for determination of cortisol and ACTH were collected every 15 min from 3 pm to 4:15 pm. Cortisol and ACTH responses were calculated as areas under the curve.

Results

Controlling for age, baseline (i.e., post-dexamethasone) ACTH levels were higher in depressed patients compared to controls (p=0.01). There was a trend for higher ACTH responses in depressed patients compared to the control group (p=0.08). In depressed patients, cortisol and ACTH responses correlated positively with age, duration of illness and number of hospitalizations.

Limitations

Because of the cross-sectional study design we can only evaluate the nature of potential HPA axis disturbances that were present in patients when they are acutely depressed.

Conclusions

Feedback inhibition of ACTH secretion by cortisol is compromised in MDD, and this is independent of an age effect on the HPA axis function.