Adrenocorticotropin Hormone Secretion Research Articles

Laparoscopic Bilateral Adrenalectomy with the Transabdominal Lateral Approach

Background: Laparoscopic adrenalectomy (LA) is a widely accepted method for most adrenal lesions. However, bilateral LA is performed less often than unilateral adrenalectomy. The most common indication for bilateral LA is adrenocorticotropin hormone (ACTH)-dependent Cushing’s syndrome, including persistent Cushing’s disease following unsuccessful transsphenoidal surgery and ectopic ACTH syndrome. Objectives: This retrospective study was conducted to assess the indications, safety, efficacy, and outcomes for bilateral LA with the transabdominal lateral approach. Methods: This retrospective study was conducted between January 2004 and February 2022. During the study period, transperitoneal LA was performed on 279 patients, among whom, 258 cases were unilateral LA. Therefore, our analysis included 21 consecutive patients who underwent laparoscopic bilateral LA with the transabdominal lateral approach. The surgery indication, tumor side and weight, operation time, conversion to open surgery, need for an additional trocar, complications, hospital stay, and follow-up information were analyzed. Results: Indications of bilateral LA were refractory Cushing’s disease (n=14), occult ectopic primary bilateral macronodular adrenal hyperplasia (n=5), ACTH secretion (n=1), and bilateral pheochromocytoma (n=1). The mean operative time was 207.8±21.3 min, including repositioning time. Intraoperative and postoperative complications were seen in 3 (14%) and 4 (19%) patients, respectively. No conversion to open surgery was observed. Median hospital stay was 7 (range, 5-10) days and median follow-up was 81 (range, 55-94.5) months. Three patients died at 62, 64, and 88 months after adrenalectomy due to heart failure, renal failure, and myocardial infarction, respectively. No adrenal insufficiency or signs of recurrent hypercortisolism was observed. Conclusion: Our results demonstrated that laparoscopic bilateral LA was safe and effective, allowing acceptable morbidity and hospital stay. The most common surgical indication was ACTH-dependent Cushing's syndrome, followed by ACTH-independent Cushing's syndrome. The lateral transperitoneal approach obtains an excellent anatomical view. In our series, operative time and conversion to open surgery rate were in line with the literature.

RF21 | PSAT77 ROLE OF THE TRANSCRIPTION FACTOR HHEX IN INNER ADRENAL CORTEX HOMEOSTASIS AND RESPONSE TO PROGESTERONE SIGNALING

Abstract Congenital adrenal hyperplasia (CAH) is a set of defects in cortisol synthesis due to mutations in genes encoding steroidogenic enzymes. Consequently, the loss of glucocorticoid-mediated negative feedback on the HPA axis leads to chronically elevated ACTH (Adrenocorticotropin Hormone) secretion. The sustained ACTH elevation, in turn, stimulates proliferation and hypertrophy of the adrenal cortex and leads to overproduction of androgens. To study the complexity of the ACTH-responsive cell population in the adrenal cortex, we performed single-cell RNA sequencing of the steroidogenic lineage in the adult mouse adrenal. We identified the transcription factor HHEX as a gene with restricted expression in the ACTH-responsive zona fasciculata. Although the role of HHEX in adrenal biology is completely unknown, a meta-analysis identified a germ-line variant of uncertain significance near the gene HHEX associated with increased DHEAS (adrenal-specific androgen) in human serum samples, which led us to hypothesize that HHEX contributes to the unique function of the ACTH-responsive inner cortex. To investigate the mechanisms by which HHEX controls adrenal differentiation and homeostasis, we generated genetically modified mice harboring a deletion of the Hhex gene in the adrenal cortex. Hhex KO mice exhibited progressive adrenomegaly by 15 weeks of age, accompanied by hypertrophy prominent in the inner cortex and disruption of the endothelial organization. Expression of the transcription factor Nr5a1/Sf-1 and steroidogenic enzymes involved in corticosterone production were significantly upregulated at 6 weeks old, prior to adenomegaly, suggesting a precocious increase in cell production of glucocorticoids. For insights into the signaling pathways controlled by HHEX, we analyzed global transcriptional changes during loss of Hhex and found dramatic downregulation of members of the membranous progesterone receptor family (PAQR). PAQR signaling has been implicated in the downregulation of cAMP, a primary mediator of ACTH signaling, and thereby could, in part, drive the increase in steroidogenesis in Hhex KO mice. These findings suggest that the inner cortex contains a progesterone-responsive cell population in which HHEX provides additional fine-tuning of ACTH-driven cAMP signaling by progesterone and derivatives. Since we observed an increase in Hhex expression in a mouse model of CAH, experiments are now ongoing to assess the implication of HHEX and autocrine progesterone signaling in contributing to the hypertrophy and steroidogenic phenotype observed in CAH. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Sunday, June 12, 2022 12:54 p.m. - 12:59 p.m.

Exploration biochimique de la corticosurrénale

AbstractPathologies affecting the adrenocortical gland may be due to an increase or a decrease in the secretion of the steroid hormones that produces, in particular cortisol. Cushing’s syndrome is associated to an excess production, while adrenal insufficiency is caused by a defect in this production. As the majority of clinical and biological signs are non-specific, the diagnosis of these pathologies is often delayed. These different pathologies can originate from the adrenal gland itself, with a dysfunction in the production of steroid hormones, or can be due to an alteration in the hypothalamic-pituitary axis. This leads to a variation in the secretion of adrenocorticotropin hormone (ACTH) which regulates cortisol production. To determine the origin of these pathologies, their biological exploration first assessed the secretion of cortisol, then of ACTH to specify their adrenal or hypothalamic-pituitary origin. Various dynamic stimulation or suppression tests are then used to determine the etiological origin of the disease.

Second-Line Tests in the Diagnosis of Adrenocorticotropic Hormone-Dependent Hypercortisolism.

Cushing’s syndrome (CS) is a rare disease caused by chronic and excessive cortisol secretion. When adrenocorticotropin hormone (ACTH) is measurable, autonomous adrenal cortisol secretion could be reasonably ruled out in a differential diagnosis of CS. ACTH-dependent CS accounts for 80%–85% of cases and involves cortisol production stimulated by uncontrolled pituitary or ectopic ACTH secretion. Pituitary adenoma is not detected in up to one-third of cases with pituitary ACTH secretion, whereas cases of CS due to ectopic ACTH secretion may be associated with either malignant neoplasia (such as small cell lung carcinoma) or less aggressive neuroendocrine tumors, exhibiting only the typical symptoms and signs of CS. Since the differential diagnosis of ACTH-dependent CS may be a challenge, many strategies have been proposed. Since none of the available tests show 100% diagnostic accuracy, a step-by-step approach combining several diagnostic tools and a multidisciplinary evaluation in a referral center is suggested. In this review, we present a clinical case to demonstrate the diagnostic work-up of ACTH-dependent CS. We describe the most commonly used dynamic tests, as well as the applications of conventional or nuclear imaging and invasive procedures.

MON-018 Fertility Rates in Rats Characterized by Increased Hypothalamic CRH Secretion

Certain strains of rats are characterized by hyperactive Hypothalamic-Pituitary-Adrenal axis responses to stress, increased hypothalamic Corticotropin-Releasing Hormone (CRH) production and decreased fertility rates. Activation of the HPA-axis and CRH secretion has been associated with suppression of the Hypothalamic-Pituitary-Ovarian axis primarily as a result of glucocorticoids. Here we examined the hypothesis that Fischer rats have decreased fertility rates because of hypothalamic CRH hypersecretion. Antalarmin, a CRH receptor type 1 antagonist, is known to suppress adrenocorticotropin hormone secretion and other CRH receptor type 1-mediated responses. Adult female Fischer rats were injected with antalarmin or placebo, twice a day, for 16 days. Mating was evidenced by the presence of spermatozoa in the vaginal smear performed every morning. After 16 days, 20% of rats (20%) treated with placebo became pregnant and 55% rats treated with antalarmin became pregnant. We have previously reported that administration of antalarmin after the first day of pregnancy does not affect blastocyst implantation in Fischer rats. Our data suggest that antalarmin improves fertility rates in Fischer rats by antagonizing the direct antireproductive role of hypothalamic CRH.

MON-408 Development of Rapidly Progressive Cushing's Disease Following Pituitary Apoplexy Several Years Prior

Cushing’s disease is characterized by hypersecretion of adrenocorticotropin hormone (ACTH), typically from a pituitary microadenoma, resulting in excess cortisol. It accounts for up to 70% of cases of Cushing’s syndrome and is associated with significant morbidity and increased mortality. We present a case of a patient with a history of pituitary apoplexy of a non-secretory adenoma who developed Cushing’s disease 4 years later. The patient is a 61-year-old woman with a history of hypertension, prediabetes, and renal cell carcinoma status post cryoablation who presented to our multidisciplinary skull-base clinic for management of a right parasagittal meningioma, left anterior clinoid nodule, and pituitary apoplexy that occurred 4 years prior. She had no signs or symptoms of pituitary hormone excess at that time. She also had an incidental 1 cm left adrenal adenoma that was recently seen on CT scan of the abdomen and she had not undergone biochemical evaluation at the time of her presentation to our clinic. As part of her evaluation of the adrenal incidentaloma, she underwent a 1 mg Dexamethasone suppression test with an 8 am cortisol of 71 ug/dL. 24 hour urine cortisol was also significantly elevated at 394 ug/24 hours (reference range <45 ug/24 hours). An ACTH level was measured to determine if the excess cortisol secretion was ACTH-dependent or ACTH-independent. The ACTH level was quite elevated at 166 pg/mL (reference range 0-46 pg/mL). MRI of the pituitary showed multinodular areas of enhancement within the sella and interval growth of tissue within the right cavernous sinus compared to an MRI obtained a year prior. While undergoing evaluation of the cortisol excess, the patient developed progressive proximal muscle weakness, worsening hypertension, easy bruising, mood swings, severe fatigue, and a 14 pound weight loss. The patient’s prediabetes progressed to diabetes with an A1c of 11%. Given the rapid progression of her symptoms, her prior history of carcinoma, her prior history of pituitary apoplexy and no definite pituitary lesion on MRI, the patient underwent inferior petrosal sinus sampling (IPSS) to determine if the source of ACTH was ectopic or from the pituitary. The results from IPSS revealed a pituitary source of excess ACTH secretion. The patient underwent endoscopic transsphenoidal resection of tissue on the right side of the pituitary. Surgical pathology was consistent with a pituitary adenoma with immunostaining positive for ACTH. Following surgical resection, the patient’s hyperglycemia and hypertension significantly improved. This case highlights a very rare presentation of Cushing’s disease following an episode of pituitary apoplexy. To our knowledge there is only one other reported case of a patient who developed Cushing’s disease in the setting of pituitary apoplexy. We will review the key clinical features and approach to diagnosis in patients with this rare presentation.

The Diagnostic Approach to Central Adrenocortical Insufficiency (CAI) in Thalassemia.

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Hormonal Secretion and Quality Of Life in Nelson Syndrome and Cushing Disease After Long Acting Repeatable Octreotide

Clinical management of persistent adrenocorticotropin hormone (ACTH) excess in Nelson syndrome (NS) and Cushing disease (CD) remains a challenge. Somatostatin and its analogs as octreotide decrease ACTH secretion through somatostatin receptors of pituitary cells. To our knowledge, there are no reports on the effect of long-acting repeatable octreotide (oct-lar) on hormonal secretion and quality of life in patients with NS and CD who failed conventional therapy. Herein, we describe the effects of treatment with oct-lar (20 mg/month intramurally) in 1 woman with NS and 2 women with persistent CD. Oct-lar therapy reduced ACTH secretion and improved the quality of life in NS patient. By contrast, in CD patients, it failed to control ACTH and cortisol secretion, and the quality of life remained unchanged.

Crowding stress inhibits serotonin 1A receptor-mediated increases in corticotropin-releasing factor mRNA expression and adrenocorticotropin hormone secretion in the Gulf toadfish

Stimulation of the serotonin 1A (5-HT1A) receptor subtype by 5-HT has been shown to result in an elevation in plasma corticosteroid levels in both mammals and several species of teleost fish, including the Gulf toadfish (Opsanus beta); however, in the case of teleost fish, it is not clearly known at which level of the hypothalamic-pituitary-interrenal axis the 5-HT1A receptor is stimulated. Additionally, previous investigations have revealed that chronic elevations of plasma cortisol mediate changes in brain 5-HT1Areceptor mRNA and protein levels via the glucocorticoid receptor (GR); thus, we hypothesized that the function of centrally activated 5-HT1A receptors is reduced or abolished as a result of chronically elevated plasma cortisol levels and that this response is GR mediated. Our results are the first to demonstrate that intravenous injection of the 5-HT1A receptor agonist, 8-OH-DPAT, stimulates a significant increase in corticotropin-releasing factor (CRF) precursor mRNA expression in the hypothalamic region and the release of adrenocorticotropic hormone (ACTH) from the pituitary of teleost fish compared to saline-injected controls. We also provide evidence that cortisol, acting via GRs, attenuates the 5-HT1A receptor-mediated secretion of both CRF and ACTH.

Recurrent Acute-Onset Cushing’s Syndrome 6 Years after Removal of a Thymic Neuroendocrine Carcinoma: From Ectopic ACTH to CRH

We describe a rare case of ectopic Cushing's syndrome that recurred 6 years after resection of a thymic neuroendocrine carcinoma. We discuss reasons for the differing clinical presentations, management, hormone profiles, as well as immunopathology. A 41-year-old male developed acute-onset Cushing's syndrome. Clinical presentation and laboratory results were compatible with ectopic adrenocorticotropin hormone (ACTH) production. Computerized tomography (CT) showed a 3.6 cm thymic tumor which was successfully resected. Plasma ACTH (P-ACTH) normalized the first postoperative day. Histopathology demonstrated a well-differentiated neuroendocrine carcinoma with diffuse positivity for ACTH and focal corticotropin-releasing hormone (CRH) reactivity in a few scattered cells. The patient was in remission for 6 years. He then again presented with acute-onset Cushing's syndrome. Fluorine-labeled dihydroxyphenylalanine ((18)F-DOPA) PET/CT showed local uptake in the mediastinum and he underwent repeat resection. However, P-ACTH remained increased (613 ng/l) and 24-h urinary cortisol was 36,720 nmol, suggesting incomplete tumor removal or metastatic spread. Metyrapone treatment was initiated but then withdrawn because the patient spontaneously recovered and cortisol metabolism gradually normalized within 3 weeks. Histopathology demonstrated a recurrent neuroendocrine carcinoma with the same features as the previous lesion but this time CRH was strongly positive in more numerous cells. Normalization of P-ACTH after primary surgery was compatible with ectopic ACTH production. However, the delayed fall in P-ACTH and serum cortisol is compatible with ectopic CRH production and stimulation of pituitary ACTH secretion, which gradually resolved. Although ectopic CRH production is very rare, the unusual dynamics illustrated here should raise the possibility of CRH production by a neuroendocrine tumor.

Treatment Options in Cushing's Disease

Endogenous Cushing’s syndrome is a grave disease that requires a multidisciplinary and individualized treatment approach for each patient. Approximately 80% of all patients harbour a corticotroph pituitary adenoma (Cushing’s disease) with excessive secretion of adrenocorticotropin-hormone (ACTH) and, consecutively, cortisol. The goals of treatment include normalization of hormone excess, long-term disease control and the reversal of comorbidities caused by the underlying pathology. The treatment of choice is neurosurgical tumour removal of the pituitary adenoma. Second-line treatments include medical therapy, bilateral adrenalectomy and radiation therapy. Drug treatment modalities target at the hypothalamic/pituitary level, the adrenal gland and at the glucocorticoid receptor level and are commonly used in patients in whom surgery has failed. Bilateral adrenalectomy is the second-line treatment for persistent hypercortisolism that offers immediate control of hypercortisolism. However, this treatment option requires a careful individualized evaluation, since it has the disadvantage of permanent hypoadrenalism which requires lifelong glucocorticoid and mineralocorticoid replacement therapy and bears the risk of developing Nelson’s syndrome. Although there are some very promising medical therapy options it clearly remains a second-line treatment option. However, there are numerous circumstances where medical management of CD is indicated. Medical therapy is frequently used in cases with severe hypercortisolism before surgery in order to control the metabolic effects and help reduce the anestesiological risk. Additionally, it can help to bridge the time gap until radiotherapy takes effect. The aim of this review is to analyze and present current treatment options in Cushing’s disease.

Role of Somatostatin Receptors in Normal and Tumoral Pituitary Corticotropic Cells

Normal and tumoral pituitary corticotropic cells express sst₂ and sst₅, of which sst₅ is the predominantly expressed receptor subtype. Somatostatin (SS) inhibits pituitary adrenocorticotropin hormone (ACTH) secretion in vitro, but the sensitivity to SS is strongly regulated by glucocorticoids. In pathological conditions of a low endogenous cortisol level, i.e. in patients with adrenal insufficiency and in patients with Nelson’s syndrome, SS and sst₂-preferring SS analogs (SSA), such as octreotide, are able to lower circulating ACTH and cortisol levels. On the other hand, sst₂-preferring SSA seem not effective in lowering ACTH and cortisol levels in patients with untreated Cushing’s disease (CD), in which circulating cortisol levels are high. This is likely due to the downregulation of sst₂ receptors by glucocorticoids. sst₅ receptor expression is more resistant to the inhibitory effect of glucocorticoids. In recent years, novel sst subtype-selective and universal SSA have been developed. In particular, SSA with a high sst₅-binding affinity are potent inhibitors of ACTH secretion by pituitary corticotropic adenoma cells. This knowledge has initiated clinical trials evaluating the efficacy of these novel SSA in patients with CD, with the aim to lower circulating ACTH and cortisol levels by targeting multiple ssts on the corticotropic adenoma cells. In this minireview, the effects of SS in the regulation of normal and tumoral ACTH secretion, the role of sst subtypes involved herein, as well as the potentials of novel SSA in the treatment of patients with recurrent or persisting CD are discussed.

Effects of sex and early maternal abuse on adrenocorticotropin hormone and cortisol responses to the corticotropin-releasing hormone challenge during the first 3 years of life in group-living rhesus monkeys.

In this study we investigated the development of the hypothalamic-pituitary-adrenal (HPA) axis in 21 group-living rhesus monkeys infants that were physically abused by their mothers in the first few months of life and in 21 nonabused controls. Cortisol and adrenocorticotropin hormone (ACTH) responses to a corticotropin-releasing hormone (CRH) challenge were assessed at 6-month intervals during the subjects' first 3 years of life. Abused infants exhibited greater cortisol responses to CRH than controls across the 3 years. Abused infants also exhibited blunted ACTH secretion in response to CRH, especially at 6 months of age. Although there were no significant sex differences in abuse experienced early in life, females showed a greater cortisol response to CRH than males at all ages. There were no significant sex differences in the ACTH response to CRH, or significant interactions between sex and abuse in the ACTH or cortisol response. Our findings suggest that early parental maltreatment results in greater adrenocortical, and possibly also pituitary, responsiveness to challenges later in life. These long-term alterations in neuroendocrine function may be one the mechanisms through which infant abuse results in later psychopathologies. Our study also suggests that there are developmental sex differences in adrenal function that occur irrespective of early stressful experience. The results of this study can enhance our understanding of the long-term effects of child maltreatment as well as our knowledge of the development of the HPA axis in human and nonhuman primates.

Treatment of Cushing disease: overview and recent findings

Endogenous Cushing syndrome is an endocrine disease caused by excessive secretion of adrenocorticotropin hormone in approximately 80% of cases, usually by a pituitary corticotroph adenoma (Cushing disease [CD]). It is a heterogeneous disorder requiring a multidisciplinary and individualized approach to patient management. The goals of treatment of CD include the reversal of clinical features, the normalization of biochemical changes with minimal morbidity, and long-term control without recurrence. Generally, the treatment of choice is the surgical removal of the pituitary tumor by transsphenoidal approach, performed by an experienced surgeon. Considering the high recurrence rate, other treatments should be considered. Second-line treatments include more radical surgery, radiation therapy, medical therapy, and bilateral adrenalectomy. Drug treatment has been targeted at the hypothalamic or pituitary level, at the adrenal gland, and also at the glucocorticoid receptor level. Frequently, medical therapy is performed before surgery to reduce the complications of the procedure, reducing the effects of severe hypercortisolism. Commonly, in patients in whom surgery has failed, medical management is often essential to reduce or normalize the hypercortisolemia, and should be attempted before bilateral adrenalectomy is considered. Medical therapy can be also useful in patients with CD while waiting for pituitary radiotherapy to take effect, which can take up to 10 years or more. So far, results of medical treatment of CD have not been particularly relevant; however, newer tools promise to change this scenario. The aim of this review is to analyze the results and experiences with old and new medical treatments of CD and to reevaluate medical therapies for complications of CD and hypopituitarism in patients with cured CD.

The role of the arginine vasopressin Avp1b receptor in the acute neuroendocrine action of antidepressants

In times of stress the hypothalamic-pituitary-adrenal (HPA) axis is activated and releases two neurohormones, corticotropin-releasing hormone (Crh) and arginine vasopressin (Avp), to synergistically stimulate the secretion of adrenocorticotropin hormone (ACTH) from the anterior pituitary, culminating in a rise in circulating glucocorticoids. Avp mediates its actions at the Avp V1b receptor (Avpr1b) present on pituitary corticotropes. Dysregulation of the stress response is associated with the pathophysiology of depression and a major treatment involves increasing the availability of monamines at the synaptic cleft. Acute administration of selective serotonin reuptake inhibitors (SSRI) and tricyclic antidepressants (TCA) has previously been shown to activate the HPA axis. The present study was undertaken to evaluate the involvement of the Avpr1b in the HPA axis response to acute SC administration of an SSRI (fluoxetine 10mg/kg) and a TCA (desipramine 10mg/kg). We measured plasma ACTH and corticosterone (CORT) levels and neuropeptide mRNA expression in the hypothalamic paraventricular nucleus (PVN) of Avpr1b knockout (KO) mice and wild-type controls. Fluoxetine and desipramine administration significantly attenuated plasma ACTH and CORT levels in male and female Avpr1b KO mice when compared to their wild-type counterparts. Avp, oxytocin (Oxt) and Crh mRNA expression in the PVN did not change in fluoxetine-treated male Avpr1b KO or wild-type mice. In contrast, fluoxetine treatment increased PVN Avp mRNA levels in female Avpr1b wild type but not KO animals. PVN Oxt mRNA levels increased in fluoxetine-treated female mice of both genotypes. The data suggests that the Avpr1b is required to drive the HPA axis response to acute antidepressant treatment and provides further evidence of a sexual dichotomy in the regulation of PVN Avp/Oxt gene expression following antidepressant administration.

The role of bilateral inferior petrosal sinus sampling in the diagnosis of Cushing's syndrome

Adrenocorticotropin hormone (ACTH)-dependent Cushing's syndrome is most often due to a pituitary corticotroph adenoma, with ectopic ACTH-secreting tumors representing approximately 15% of cases. Biochemical and radiological techniques have been established to help distinguish between these two entities, and thus aid in the localization of the neoplastic lesion for surgical resection. The test that offers the highest sensitivity and specificity is bilateral inferior petrosal sinus sampling (BIPSS). BIPSS is an interventional radiology procedure in which ACTH levels obtained from venous drainage very near the pituitary gland are compared to peripheral blood levels before and after corticotropin hormone (CRH) stimulation. A gradient between these two locations indicates pituitary Cushing's, whereas the absence of a gradient suggests ectopic Cushing's. Accurate BIPSS results require hypercortisolemia to suppress normal corticotroph ACTH production and hypercortisolemia at the time of the BIPSS to assure excessive ACTH secretion. In some cases, intrapituitary gradients from side-to-side can be helpful to localize small corticotroph adenomas within the sella. BIPSS has rare complications and is considered safe when performed at centers with experience in this specialized technique.

Glutamate agonists activate the hypothalamic–pituitary–adrenal axis through hypothalamic paraventricular nucleus but not through vasopressinerg neurons

The hypothalamic–pituitary–adrenal (HPA) axis plays a crucial role in the stress processes. The nucleus paraventricularis hypothalami (PVN) with corticotropin-releasing hormone (CRH)-containing and arginine vasopressin (AVP)-containing neurons is the main hypothalamic component of the HPA. The glutamate, a well-known excitatory neurotransmitter, can activate the HPA inducing adrenocorticotropin hormone (ACTH) elevation. The aim of our study was to examine the involvement of PVN and especially AVP in glutamate-induced HPA activation using agonists of the N-methyl- d-aspartate (NMDA) and kainate receptors. Two approaches were used: in male Wistar rats the PVN was lesioned, and AVP-deficient homozygous Brattleboro rats were also studied. Blood samples were taken through indwelling cannula and ACTH, and corticosterone (CS) levels were measured by radioimmunoassay. The i.v. administered NMDA (5 mg/kg) or kainate (2.5 mg/kg) elevated the ACTH and CS levels already at 5 min in control (sham-operated Wistar or heterozygous Brattleboro) rats. The PVN lesion had no influence on basal ACTH and CS secretion but blocked the NMDA- or kainate-induced ACTH and CS elevations. The lack of AVP in the Brattleboro animals had no significant influence on the basal or glutamate-agonists-induced ACTH and CS elevations. Our results suggest that NMDA and kainate may activate the HPA axis at central (PVN) level and not at the level of pituitary or adrenal gland and that AVP has minor role in glutamate–HPA axis interaction. The time course of the ACTH secretion was different with NMDA or kainate. If we compared the two curves, the results were not coherent with the general view that NMDA activation requires previous kainate activation. Although it has to be mentioned that the conclusion which can be drawn is limited, the bioavailability of the compounds could be different as well.

HPA axis activation determined by the CRH challenge test in patients with few versus multiple episodes of treatment?refractory depression

In clinical guidelines, risk factors for a malignant illness course include 3 or more lifetime episodes of depression. Our aim was to investigate the activation of the hypothalamic-pituitary-adrenal hormonal axis in treatment-refractory affective disorder in pauciepisodic (one or two episodes) versus multiepisodic (three or more episodes) patients. We evaluated the HPA axis in 37 patients with treatment-refractory affective disorder and in 27 healthy volunteers by measuring adrenocorticotropin hormone (ACTH) and cortisol responses following administration of corticotropin-releasing hormone (CRH). In retrospective life charts was recorded every previous illness episode for each patient. Seven of the patients were pauciepisodic and 30 were multiepisodic. The pauciepisodic patients had significantly larger peak and total ACTH responses to CRH compared to the multiepisodic patients as well as to the control group. Multiepisodic patients showed no difference compared to controls in ACTH secretion pre- and post-CRH. Cortisol secretion was the same in all three groups. The pituitary adrenocortical responses were stronger in pauciepisodic patients than in multiepisodic patients and in volunteers. This cross-sectional study suggests that the HPA axis, in refractory multiepisodic affective disorders, might weaken its original activity as the illness recurs with more episodes.

Identification of stimulatory and inhibitory inputs to the hypothalamic-pituitary-adrenal axis during hypoglycaemia or transport in ewes.

This study used the novel approach of statistical modelling to investigate the control of hypothalamic-pituitary-adrenal (HPA) axis and quantify temporal relationships between hormones. Two experimental paradigms were chosen, insulin-induced hypoglycaemia and 2 h transport, to assess differences in control between noncognitive and cognitive stimuli. Vasopressin and corticotropin-releasing hormone (CRH) were measured in hypophysial portal plasma, and adrenocorticotropin hormone (ACTH) and cortisol in jugular plasma of conscious sheep, and deconvolution analysis was used to calculate secretory rates, before modelling. During hypoglycaemia, the relationship between plasma glucose and vasopressin or CRH was best described by log10 transforming variables (i.e. a positive power-curve relationship). A negative-feedback relationship with log10 cortisol concentration 2 h previously was detected. Analysis of the "transport" stimulus suggested that the strength of the perceived stimulus decreased over time after accounting for cortisol facilitation and negative-feedback. The time course of vasopressin and CRH responses to each stimulus were different However, at the pituitary level, the data suggested that log10 ACTH secretion rate was related to log10 vasopressin and CRH concentrations with very similar regression coefficients and an identical ratio of actions (2.3 : 1) for both stimuli. Similar magnitude negative-feedback effects of log10 cortisol at -110 min (hypoglycaemia) or -40 min (transport) were detected, and both models contained a stimulatory relationship with cortisol at 0 min (facilitation). At adrenal gland level, cortisol secretory rates were related to simultaneously measured untransformed ACTH concentration but the regression coefficient for the hypoglycaemia model was 2.5-fold greater than for transport. No individual sustained maximum cortisol secretion for longer than 20 min during hypoglycaemia and 40 min during transport. These unique models demonstrate that corticosteroid negative-feedback is a significant control mechanism at both the pituitary and hypothalamus. The amplitude of HPA response may be related to stimulus intensity and corticosteroid negative-feedback, while duration depended on feedback alone.