ACTH Production Research Articles

Hypothalamic-Pituitary-Adrenal Axis Activation in Obstructive Sleep Apnea: The Effect of Continuous Positive Airway Pressure Therapy

Obstructive sleep apnea (OSA) is a common condition with significant cardiovascular and metabolic comorbidity. We hypothesized that these may result from OSA-induced perturbations of endogenous ultradian hypothalamic-pituitary-adrenal axis activity. The aim of the study was to investigate ACTH and cortisol ultradian patterns using an automated, repetitive blood sampling technique. Samples for ACTH and cortisol were collected from 10 patients with moderate to severe OSA under basal conditions, at 10-min intervals over 24 h, at diagnosis and 3 months after compliant continuous positive airway pressure (CPAP) therapy. Multiple-parameter deconvolution estimated specific measures of ACTH and cortisol pulsatile secretion from blood hormone concentrations. Mean total ACTH and cortisol production were elevated pre-CPAP compared to post-CPAP (ACTH, 1459.8 +/- 123.0 vs. 808.1 +/- 97.9 pg/ml, P < 0.001; cortisol, 5748.9 +/- 364.9 vs. 3817.7 +/- 351.7 nmol/liter, P < 0.001) as were mean total pulsatile production (ACTH, 764.1 +/- 86.3 vs. 383.5 +/- 50.0 pg/ml, P = 0.002; cortisol, 4715.9 +/- 253.3 vs. 3227.7 +/- 258.8 nmol/liter, P < 0.001). ACTH and cortisol secretory burst mean half-duration were higher at diagnosis (12.3 +/- 0.7 and 13.5 +/- 0.7 vs. 7.8 +/- 0.4 and 8.4 +/- 0.6 min, respectively, P < 0.001); thus, 95% of each ACTH secretion occurred in 21.0 +/- 1.2 vs. 12.9 +/- 0.8 min post-CPAP (P < 0.001) and for cortisol in 23.0 +/- 1.2 vs. 14.2 +/- 1.1 min post-CPAP (P < 0.001). Approximate entropy (ApEn) revealed greater disorderliness in both ACTH (P = 0.03) and cortisol (P = 0.001) time series pre-CPAP. Forward and reverse cross-ApEn suggested nodal disruption at central and adrenal levels pre-CPAP (P = 0.01). Significantly elevated cortisol responses to a single breath of 35% CO(2) occurred pre-CPAP (P = 0.006). Untreated compared to treated OSA is associated with marked disturbances in ACTH and cortisol secretory dynamics, resulting in prolonged tissue exposure to disordered, elevated hormone levels.

Curcumin acts as anti-tumorigenic and hormone-suppressive agent in murine and human pituitary tumour cells in vitro and in vivo

Curcumin (diferuloylmethane) is the active ingredient of the spice plant Curcuma longa and has been shown to act anti-tumorigenic in different types of tumours. Therefore, we have studied its effect in pituitary tumour cell lines and adenomas. Proliferation of lactosomatotroph GH3 and somatotroph MtT/S rat pituitary cells as well as of corticotroph AtT20 mouse pituitary cells was inhibited by curcumin in monolayer cell culture and in colony formation assay in soft agar. Fluorescence-activated cell sorting (FACS) analysis demonstrated curcumin-induced cell cycle arrest at G2/M. Analysis of cell cycle proteins by immunoblotting showed reduction in cyclin D(1), cyclin-dependent kinase 4 and no change in p27(kip). FACS analysis with Annexin V-FITC/7-aminoactinomycin D staining demonstrated curcumin-induced early apoptosis after 3, 6, 12 and 24 h treatment and nearly no necrosis. Induction of DNA fragmentation, reduction of Bcl-2 and enhancement of cleaved caspase-3 further confirmed induction of apoptosis by curcumin. Growth of GH3 tumours in athymic nude mice was suppressed by curcumin in vivo. In endocrine pituitary tumour cell lines, GH, ACTH and prolactin production were inhibited by curcumin. Studies in 25 human pituitary adenoma cell cultures have confirmed the anti-tumorigenic and hormone-suppressive effects of curcumin. Altogether, the results described in this report suggest this natural compound as a good candidate for therapeutic use on pituitary tumours.

Structure of the POMC promoter region in pituitary and extrapituitary ACTH producing tumors.

Proopiomelanocortin (POMC) is the common precursor of a variety of important endocrine peptides including ACTH. Transcription of the POMC gene is positively regulated by CRH through cAMP-responsive regions and is under negative feedback control by glucocorticoids which exert their inhibitory effect trough negative glucocorticoid responsive elements (nGRE). In vitro studies using the rat POMC promoter suggested that binding of the glucocorticoid receptor complex to a -63 bp binding site is correlated with repression of POMC gene transcription, and that specific mutations in this region abolish this effect. Impaired negative feedback regulation, though to a different degree, is a common feature of both corticotroph tumors (Cushing's disease) and extrapituitary ACTH producing tumors. We have analyzed the upstream promoter region of POMC gene from eleven patients with Cushing's disease, four of which had Nelson's syndrome, and from one patient with an ectopic ACTH syndrome secondary to a lung carcinoid for any possible mutations in the nGRE and/or cAMP-responsive sequences. DNA was purified from tumor tissue and was used as template for polymerase chain reaction (PCR). A segment between -371 and -19 bp of the POMC transcription start site was amplified and cloned into a plasmid vector. Sequencing was performed using the dideoxy chain termination procedure. Analysis of the 5'-flanking region revealed no defect in all tumors investigated. We conclude from our results that the defective glucocorticoid repression of POMC peptides production may be more likely due to aberrancies in other components of the complex transcriptional regulatory mechanism.

Immunohistochemistry of COUP-TFI: an adjuvant diagnostic tool for the identification of corticotroph microadenomas

Cushing's disease is caused by an ACTH-producing pituitary tumor, and accounts for 10-15% of pituitary tumors. The majority of corticotroph tumors are microadenomas (<10 mm), and accurate histologic identification of these tumors can be challenging because of their small size and the presence of nests of normal corticotroph cells in the anterior pituitary. Retinoic acid has been shown to inhibit ACTH production and induce apoptosis in corticotroph tumor cells. The expression of the orphan nuclear receptor COUP-TFI antagonizes retinoic acid signaling and has been shown to be expressed in normal corticotroph cells, but absent in corticotroph tumor cell lines. We analyzed 34 corticotroph tumor specimens by immunohistochemistry using a goat polyclonal IgG antibody with epitope mapping to the N-terminus of human COUP-TFI. Segments of normal pituitary in each of the 34 specimens demonstrate COUP-TFI immunoreactivity in normal corticotroph cells. Twenty-nine of 34 ACTH producing tumors were immunonegative for COUP-TFI. All of the tumors measuring less than 5 mm by preoperative MRI were COUP-TFI immunonegative. Two tumors, measuring 9 and 11 mm, showed consistent (>90%) expression of COUP-TFI, and three adenomas (5, 11, and 18 mm) showed heterogenous (20-80%) expression of COUP-TFI. Immunohistochemistry of COUP-TFI may be a useful adjuvant diagnostic tool in distinguishing corticotroph microadenomas from nests of normal corticotroph cells in the anterior pituitary. Furthermore, this study identifies two unique corticotroph tumor populations which differ in their expression of COUP-TFI, the presence of which occurs more frequently in macroadenomas.

The stimuli-specific role of vasopressin in the hypothalamus–pituitary–adrenal axis response to stress

Adaptation to a constantly changing environment is fundamental to every living organism. The hypothalamic-pituitary-adrenocortical (HPA) axis is a key component of the adaptation process. The present study tests the hypothesis that vasopressin (AVP) is required for the HPA response to acute stimuli. To accomplish this, naturally AVP-deficient Brattleboro rats were exposed to a wide range of stimuli and their HPA response was compared with heterozygous littermates. The circadian rhythmicity of plasma ACTH and corticosterone was not different between the two genotypes. The ACTH and corticosterone response to volume load, restraint or aggressive attack were decreased in AVP-deficient rats. The stress-induced increase in ACTH, but not corticosterone, was significantly impaired in AVP-deficient animals after novelty, elevated plus-maze, forced swim, hypoglycaemia, ulcerogenic cold immobilisation, lipopolysaccharide, hypertonic saline and egg white injection. The HPA response to social avoidance, ether inhalation and footshock was not different between the genotypes. In vitro, the hypophysis of AVP-deficient animals showed a reduction in stimulated ACTH production and their adrenal glands were hyporeactive to ACTH. A dissociation between the ACTH and corticosterone response was observed in several experiments and could not be explained by an earlier ACTH peak or enhanced adrenal sensitivity, suggesting the existence of paraadenohypophyseal neuroendocrine regulators. Loss of AVP affected the HPA response to a wide variety of stressors. Interestingly, the contribution of AVP to the HPA response was not specific for, nor limited to, a known stressor category. Thus, there is a context-specific requirement for AVP in stress-induced activation of the HPA axis.

Disordered and Increased Adrenocorticotropin Secretion with Diminished Adrenocorticotropin Potency in Obese in Premenopausal Women

The pituitary-adrenal ensemble of obese humans is marked by increased urinary excretion of cortisol and its metabolites in the face of normal circulating cortisol levels. For better understanding of the (patho) physiological meaning of these changes, the mechanistic underpinnings need to be clarified. We investigated 17 obese women [body mass index (BMI) 30-39.4 kg/m(2)] and 14 normal women (BMI, 18.3-24.8 kg/m(2)) who underwent 24-h blood sampling at 10-min intervals, and plasma ACTH and cortisol concentrations were measured with sensitive assays. Data were analyzed with a new deconvolution program, approximate entropy (ApEn) analyses, and cosinor regression. ACTH and cortisol production rates were higher in obese women than in controls and correlated with BMI. Secretion of ACTH correlated with leptin (R = 0.63; P = 0.0001) and insulin (R = 0.67; P = 0.0001). ACTH ApEn and forward ACTH-cortisol cross-ApEn were diminished in obese women. The half-maximal effective concentration (ED(50)) of ACTH pulses vs. cortisol pulses was higher in obese women (38.3 +/- 4.9 vs. 25.1 +/- 3.7 ng/liter; P = 0.03), indicating decreased potency of ACTH. The diurnal properties of ACTH and cortisol secretion were unchanged in obese females. Obese women exhibit enhanced ACTH and cortisol 24-h production compared with lean controls. The amplified ACTH drive is accompanied by decreased secretory regularity and diminished forward coupling between ACTH and cortisol. In addition, the potency of ACTH is decreased in obesity.

Human pituitary contains dual cathepsin L and prohormone convertase processing pathway components involved in converting POMC into the peptide hormones ACTH, alpha-MSH, and beta-endorphin.

The production of the peptide hormones ACTH, alpha-MSH, and beta-endorphin requires proteolytic processing of POMC which is hypothesized to utilize dual cysteine- and subtilisin-like protease pathways, consisting of the secretory vesicle cathepsin L pathway and the well-known subtilisin-like prohormone convertase (PC) pathway. To gain knowledge of these protease components in human pituitary where POMC-derived peptide hormones are produced, this study investigated the presence of these protease pathway components in human pituitary. With respect to the cathepsin L pathway, human pituitary contained cathepsin L of 27-29 kDa and aminopeptidase B of approximately 64 kDa, similar to those in secretory vesicles of related neuroendocrine tissues. The serpin inhibitor endopin 2, a selective inhibitor of cathepsin L, was also present. With respect to the PC pathway, human pituitary expresses PC1/3 and PC2 of approximately 60-65 kDa, which represent active PC1/3 and PC2; peptide hormone production then utilizes carboxypeptidase E (CPE) which is present as a protein of approximately 55 kDa. Analyses of POMC products in human pituitary showed that they resemble those in mouse pituitary which utilizes cathepsin L and PC2 for POMC processing. These findings suggest that human pituitary may utilize the cathepsin L and prohormone convertase pathways for producing POMC-derived peptide hormones.

Cushing's Syndrome Due to a Non-Adrenal Ectopic Adrenocorticotropin-Secreting Ewing's Sarcoma in a Child

Ectopic ACTH syndrome (EAS) is extremely rare in the pediatric age group. Sarcomatous tumors causing EAS are even rarer. We report a 9 year-old girl presenting with Cushing's syndrome caused by ectopic ACTH production by a Ewing's sarcoma. This case illustrates that rapid appearance of Cushingoid symptoms, absence of growth retardation and the presence of hypokalemia are suggestive clues for ectopic ACTH production as the source of Cushing's syndrome.

Síndrome de Cushing suprarrenal

Cushing’s syndrome is due to a chronic excess of glucocorticoids. It is rare (10 cases per million inhabitants per year); 70% of cases are caused by excessive ACTH production in the pituitary, 10% by ectopic ACTH production, and the remaining 20% by suprarenal Cushing’s syndrome due to adenomas (10%), carcinomas (10%) or primary bilateral hyperplasia (1). Surgery to correct Cushing’s syndrome has high morbimortality (greater than 10%), with wound infection, hemorrhage, pulmonary embolism, and respiratory problems being the most common complications (1). Laparoscopic adrenalectomy is the current treatment of choice for benign adrenal disease (2,3).

Premature differentiation and aberrant movement of pituitary cells lacking both Hes1 and Prop1

In the pituitary, the transition from proliferating progenitor cell into differentiated hormone producing cell is carefully regulated in a time-dependent and spatially-restricted manner. We report that two targets of Notch signaling, Hes1 and Prop1, are needed to maintain progenitors within Rathke's pouch and for the restriction of differentiated cells to the ventral pituitary. We observed ACTH and αGSU producing cells that had prematurely differentiated within Rathke's pouch along with correlated ectopic expression of Mash1 only when both Prop1 and Hes1 were lost. We also discovered that downregulation of N-cadherin expression in cells as they transition from Rathke's pouch to the anterior lobe appears to be essential for their movement. In the Prop1 mutant, cells are trapped in Rathke's pouch and N-cadherin expression remains high. Also, Slug, a marker of epithelial-to-mesenchymal transition, is absent in the dorsal anterior lobe. When Hes1 is lost in the Prop1 mutant, N-cadherin is downregulated and cells are able to exit Rathke's pouch but have lost their migrational cues and form ectopic foci surrounding Rathke's pouch. Our data reveal important overlapping functions of Hes1 and Prop1 in cell differentiation and movement that are critical for pituitary organogenesis.

Interferon-γ inhibits cellular proliferation and ACTH production in corticotroph tumor cells through a novel janus kinases–signal transducer and activator of transcription 1/nuclear factor-kappa B inhibitory signaling pathway

Interferon-gamma (IFNG) is a cytokine that exerts potent antiproliferative and tumoricidal effects in a variety of cancers. Moreover, IFNG modulates normal pituitary hormone secretion, and was shown to inhibit the expression of the ACTH precursor POMC in murine ACTH-secreting AtT-2010/21/2008 tumor cells. We have studied the functional role of IFNG on pituitary tumor cells, focusing on the involvement of IFNG in the molecular events leading to the control of POMC transcriptional repression. Herein, it is shown that IFNG inhibits AtT-20 tumor cell proliferation without inducing apoptosis. Unexpectedly, an activated janus kinases-signal transducer and activator of transcription (JAK-STAT1) cascade is required for IFNG inhibitory action on POMC promoter activity. Factor-kappa B (NF-kappaB) is necessary for the inhibitory action of IFNG on Pomc transcription, since loss of NF-kappaB activity with IkappaB super-repressor abolishes this effect. In addition, 1 and 2 IFNG receptor immunoreactivity was detected in human corticotropinoma cells. Interestingly, IFNG inhibits ACTH production from these cells in primary cell culture, without affecting basal ACTH biosynthesis in normal non-tumoral pituitary cells. In conclusion, our data show for the first time that POMC transcription can be negatively regulated by a JAK-STAT1 and NF-kappaB-dependent pathway.

Severe hypertension and hypokalemia as first clinical manifestations in ectopic Cushing's syndrome

Ectopic ACTH production occurs in about 10% of all cases of Cushing's syndrome, and about 25% of cases of ACTH-dependent Cushing's syndrome. Diverse tumor types are able to produce ACTH ectopically, including small cell lung carcinoma. Ectopic ACTH secretion by malignant neoplasm has been reported to have earlier and more aggressive metabolic effects. We report a 59-year-old male patient with severe hypertension, metabolic alkalosis and hypokalemia as the first clinical manifestations of an ACTH-secreting small cell lung carcinoma, although the typical phenotypic features of Cushing's syndrome were not present. Ectopic Cushing's syndrome should always be ruled out in patients with severe hypertension and hypokalemia.

The Ca2+ binding capacity of epidermal furin is disrupted by H2O2‐mediated oxidation in vitiligo

It was previously established that epidermal keratinocytes and melanosomes express the Ca2+‐dependent precursor convertase furin. All prohormone convertases including furin are regulated by Ca2+. Meanwhile, it is noteworthy that proopiomelanocortin (POMC) cleavage is processed by furin, in addition to the classical PC1 and PC2 convertases, leading to the production of ACTH, β‐LPH and β‐endorphin. Since numerous epidermal peptides and enzymes are affected by H2O2‐mediatedoxidation, including the POMC derived peptides α‐MSH and β‐endorphin, as shown in the epidermis of patients with vitiligo, it was of interest whether furin could also be a possible target for this oxidation mechanism. Confirming the presence of furin in epidermal keratinocytes and melanocytes using immunoflurescence, RT‐PCR, and Western blotting, we further demonstrate significantly decreased in situ immunoreactivity of furin in the epidermis of patients with progressive vitiligo suggesting H2O2‐mediated oxidation. This was substantiated by [45Ca2+] binding studies with human recombinant furin identifying the loss of one Ca2+‐binding site from the enzyme after oxidation with H2O2. Computer simulation supported alteration of one of the two Ca2+‐binding sites on furin. Overall, our results demonstrate that the Ca2+ dependent proteolytic activity of this convertase is a target for H2O2‐mediated oxidation which in turn could contribute to the reduced epidermal expression of the POMC derived peptides α‐MSH and β‐endorphin as documented earlier in patients with vitiligo.

Cushing’s syndrome due to ectopic ACTH production by (neuroendocrine) prostate carcinoma

Ectopic adrenocorticotropin (ACTH) secretion accounts for less than 10% of all causes of endogenous Cushing's syndrome (CS) and is usually associated with neuroendocrine tumors and small cell carcinoma of the lung. We report the case of a 62-year-old man with CS due to ectopic ACTH production by small cell carcinoma of the prostate. He presented with severe hypercortisolism and associated symptoms. Plasma neuron specific enolase (NSE) was grossly elevated. Despite performing a laparoscopic bilateral adrenalectomy, the patient died as a result of sepsis with multi-organ failure. Post-mortem immunohistochemical staining of prostate tumor tissue showed ACTH expression. ACTH staining was also performed in four additional patients with small cell carcinoma of the urinary tract without CS. None of these additional cases showed a positive staining for ACTH. Although a rare cause of ectopic ACTH production, neuroendocrine prostate carcinoma should be considered in male patients with Cushing's syndrome, in particular in those with an occult source of ACTH overproduction.

Consummatory behavior and metabolic indicators after central ghrelin injections in rats

Ghrelin, an endogenous ligand for the growth-hormone-secretagogue receptor, is a 28-amino acid peptide with a post-translational acyl modification necessary for its activity. It has central nervous system actions that affect appetite, body mass and energy balance. An intracerebroventricular (ICV) injection protocol of sub-nanomolar doses of ghrelin, known to alter the morphology of ACTH and GH producing pituicytes and plasma levels of these hormones, was used to provide an overview of metabolic changes linked to energy metabolism. Variables measured were: food intake (FI), water intake (WI), fecal mass, urine volume, body weight (BW), retroperitoneal (RP) and epididymal (EPI) white adipose tissue (WAT), and changes in serum leptin, insulin, triglycerides, cholesterol, and glucose. Five injections of rat ghrelin or PBS (n=8 per group) were given ICV every 24 h (1 μg/5 μL PBS) to adult male rats. Ghrelin had a positive and cumulative effect on FI, WI and BW (p<0.05), but not feces mass or urine volume (p>0.05). Centrally applied ghrelin clearly increased RP WAT (by 235%, p<0.001), EPI WAT (by 85%, p<0.05) and serum insulin levels (by 43%, p<0.05), and decreased serum leptin levels (by 77%, p<0.05) without (p>0.05) evoking changes in blood triglyceride cholesterol, or glucose levels.These data and the available literature clearly document that exposure of the brain of normal rats, over time, to sub-nanomolar doses of ghrelin results in metabolic dysregulation culminating in increased body mass, consummatory behavior, and lipid stores as well as changes in blood leptin/insulin levels. Thus, modulation of central ghrelin receptors may represent a pharmacological approach for controlling multiple factors involved in energy balance and obesity.

Resposta do ACTH plasmático ao estímulo com CRH ou CRH + desmopressina em pacientes com síndrome de Cushing ACTH- dependente submetidos a cateterismo bilateral simultâneo dos seios petrosos inferiores

OBJETIVO: Comparar a resposta do ACTH plasmático após estímulo com CRH ou CRH + desmopressina em pacientes com síndrome de Cushing ACTH-dependente que realizaram cateterismo bilateral simultâneo dos seios petrosos inferiores. MATERIAIS E MÉTODOS: O procedimento foi realizado em 21 pacientes - 14 mulheres e 7 homens - com síndrome de Cushing ACTH-dependente no período de janeiro de 1998 a dezembro de 2003. Após a cateterização de ambos os seios petrosos, amostras de sangue para ACTH foram colhidas, simultaneamente, nos seios petrosos e veia periférica, tanto no estado basal como após três e cinco minutos da administração de CRH humano (100 mg) (6 pacientes) ou CRH + desmopressina (100 mg + 10 mg) (15 pacientes). RESULTADOS: Aos três minutos, houve aumento percentual do ACTH tanto no grupo CRH (257,77 ± 240,36 no seio petroso direito e 718,78 ± 1.358,82 no seio petroso esquerdo [média ± desvio-padrão]) como no grupo CRH + desmopressina (1.263,35 ± 1.842,91 no seio petroso direito [p = 0,06] e 583,93 ± 1.020,03 no seio petroso esquerdo [p = 0,83]). Aos cinco minutos houve declínio percentual do ACTH no grupo do CRH (181,07 ± 217,39 no seio petroso direito e 188,25 ± 270,15 no seio petroso esquerdo) e aumento progressivo no grupo do CRH + desmopressina (1.365,29 ± 1.832,31 no seio petroso direito [p = 0,03] e 866,43 ± 1.431,72 no seio petroso esquerdo [p = 0,11]). Nos três pacientes com secreção ectópica não houve gradiente. CONCLUSÃO: A estimulação combinada CRH + desmopressina induziu maior produção de ACTH em adenomas corticotróficos em comparação ao CRH, o que pode melhorar a sensibilidade diagnóstica deste procedimento.

Cellular and molecular abnormalities of a macronodular adrenal hyperplasia causing beta-blocker-sensitive Cushing's syndrome

Cushing's syndrome due to ACTH-independent macronodular adrenal hyperplasia (AIMAH) can be associated with abnormal responses of aberrantly expressed adrenocortical receptors. This study aimed to characterize in vitro the pathophysiology of hypercortisolism in a beta-blocker-sensitive Cushing's syndrome due to AIMAH. Cortisol secretion profile under aberrant receptors stimulation revealed hyperresponsiveness to salbutamol (beta2-adrenoceptor agonist), cisapride (5-HT4 receptor agonist), and vasopressin in AIMAH cultured cells, but not in normal adrenocortical cells. By RT-PCR, AIMAH tissues revealed beta2-adrenoceptor overexpression rather than ectopical expression. MC2R expression was similar in both AIMAH and normal adrenocortical tissues. Curiously, cortisol levels of AIMAH cells under basal condition were 15-fold higher than those of control cells and were not responsive to ACTH. Analysis of culture medium from AIMAH cells could detect the presence of ACTH, which was immunohistochemically confirmed. Finally, the present study of AIMAH cells has identified: a) cortisol hyperresponsiveness to catecholamines, 5-HT4 and vasopressin in vitro, in agreement with clinical screening tests; b) abnormal expression of beta2-adrenoceptors in some areas of the hyperplastic adrenal tissue; c) autocrine loop of ACTH production. Altogether, the demonstration of aberrant responses to hormonal receptors and autocrine hormone production in the same tissue supports the assumption of multiple molecular alterations in adrenal macronodular hyperplasia.

In vitro effect of hormones on the hormone content of rat peritoneal and thymic cells. Is there an endocrine network inside the immune system?

The cells of the immune system contain hormones and receptors for hormones. However, the hormonal interactions between the cells are not elucidated. In the present experiments the effect of four hormones (insulin, oxytocin, gonadotropin and epidermal growth factor) on the production of three hormones (ACTH, endorphin, triiodothyronine) in immune cells was studied. Hormone content of peritoneal immune cells (lymphocytes, monocyte-macrophage-granulocyte group [mo-gran], mast cells) as well as thymic cells of 100 g male rats, in vitro-treated or not treated with hormones mentioned above, were determined by flow cytometry, using specific antibodies. All of the hormones studied influenced the hormone concentration of immune cells significantly. The width of the effects was different in the following order: oxytocin > gonadotropin > EGF > insulin. In the case of oxytocin, 8/12 of the hormone/cell group were affected, while treatment with insulin affected only 4/12. The reaction measured by the hormone production was also different: ACTH production was reduced everywhere except in the insulin-thymocyte setup. Endorphin and T3 production was always elevated. Cells of the mo-gran group were more sensitive to hormonal regulation than peritoneal lymphocytes. The results mean that immune cells can be regulated by the neuroendocrine system and could also be able to play a role in endocrine regulation. In addition, taking into account the localization of these cells in the immune organs, there is the possibility of autocrine and paracrine regulation inside the immune system. Considering that the hormones, contained or sensed by the cells of the immune system are influencing each other, the concept of a hormonal network within the immune system can be proposed.

Cushing's syndrome in pregnancy: an overview

Cushing's syndrome (CS) during pregnancy is a rare condition with fewer than 150 cases reported in the literature. Adrenal adenomas were found to be the commonest cause, followed by Cushing's disease. The gestation dramatically affects the maternal hypothalamic-pituitary-adrenal axis, resulting in increased hepatic production of corticosteroid-binding globulin (CBG), increased levels of serum, salivary and urinary free cortisol, lack of suppression of cortisol levels after dexamethasone administration and placental production of CRH and ACTH. Moreover, a blunted response of ACTH and cortisol to exogenous CRH may also occur. Therefore, the diagnosis of CS during pregnancy is much more difficult. Misdiagnosis of CS is also common, as the syndrome may be easily confused with preeclampsia or gestational diabetes. Because CS during pregnancy is usually associated with severe maternal and fetal complications, its early diagnosis and treatment are critical. Surgery is the treatment of choice for CS in pregnancy, except perhaps in the late third trimester, with medical therapy being a second choice. There does not seem to be a rationale for supportive treatment alone.

Imaging in Cushing's syndrome

Once the diagnosis of Cushing's syndrome (CS) has been established, the main step is to differentiate between ACTH dependent and independent disease. In adults, 80% of CS is due to ACTH-dependent causes and 20% due to adrenal causes. ACTH-secreting neoplasms cause ACTH-dependent CS. These are usually anterior pituitary microadenomas, which result in the classic Cushing's disease. Non-pituitary ectopic sources of ACTH, such as a small-cell lung carcinoma or carcinoid tumours, are the source of the remainder of ACTH-dependent disease. In the majority of patients presenting with clinical and biochemical evidence of CS, modern non-invasive imaging can accurately and efficiently provide the cause and the nature of the underlying pathology. Imaging is essential for determining the source of ACTH in ectopic ACTH production, locating the pituitary tumours and distinguishing adrenal adenomas, carcinomas and hyperplasias. In our chapter we review the adrenal appearances in ACTH-dependent and ACTH-independent CS. We also include a discussion on the use of MRI and CT for the detection and management of pituitary ACTH secreting adenomas. CT of the chest, abdomen and pelvis with intravenous injection of contrast medium is the most sensitive imaging modality for the identification of the ectopic ACTH source and detecting adrenal pathology. MRI is used for characterising adrenal adenomas, problem solving in difficult cases and for detecting ACTH-secreting pituitary adenomas.