AZA-deoxycytidine stimulates proopiomelanocortin gene expression and ACTH secretion in human pituitary ACTH-secreting tumors.

PURPOSE: It is well known that methylation plays an important role in regulating tissue expression of proopiomelanocortin (POMC) and recent studies have shown that demethylation can occur also in vitro in neuroendocrine tumors. Aim of the present study was to evaluate whether inhibition of methylation modulates POMC expression and ACTH secretion by human corticotrope tumors. METHODS: Twenty two ACTH-secreting pituitary tumors were incubated with 5-AZA-2'-deoxycytidine (AZA), an inhibitor of DNA-methyltransferases, with or without 10 nM corticotropin-releasing hormone (CRH). Both dose response (100 nM-10 µM AZA) and time course (4-96 h) experiments were carried out for measurement of ACTH secretion and POMC gene expression. RESULTS: Incubation with AZA increased constitutive POMC expression and ACTH secretion by human corticotrope adenomas. The effect appeared most notable at 24 and 48 h with 1 µM AZA. Incubation with AZA did not exert an additional stimulatory effect on CRH-stimulated POMC and ACTH. CONCLUSIONS: The present study shows that AZA increases POMC gene expression and ACTH secretion in human pituitary ACTH-secreting tumors. This can be taken to indicate that mechanisms set into motion by AZA play a role in the regulation of ACTH secretion/POMC expression in tumoral corticotropes and paves the way to further studies in Cushing's disease.

Differential patterns of regional neuroadrenergic cardiovascular drive in acromegalic disease.

It has been shown that acromegaly is characterized by an autonomic imbalance and by marked sympathoinhibition. However, there is no information available as to whether adrenergic inhibition is confined to selected vascular districts or, rather, is generalized. We examined 17 newly diagnosed active acromegalic patients without hyperprolactinaemia, pituitary hormone deficiencies, obstructive sleep apnoea and cardiac hypertrophy and 14 healthy subjects matched for age, sex and body mass index. For each subject, we collected information regarding anthropometric parameters and echocardiography, and collected plasma samples to investigate anterior pituitary function, glucose and lipid metabolism and plasma leptin levels. Beat-to-beat mean arterial pressure, heart rate and efferent post-ganglionic muscle and skin sympathetic nerve traffic (MSNA and SSNA, respectively; determined by microneurography) were measured. Both MSNA and SSNA were recorded in a randomized sequence over two 30 min periods. Measurements also included evaluation of SSNA responses to emotional stimulus. In addition to significant reductions in plasma leptin levels, acromegalic patients had markedly decreased MSNA compared with the healthy controls. There were no significant differences in SSNA between the two groups, either under basal conditions or in responses to arousal stimuli. There was a significant and direct correlation between MSNA and plasma leptin levels, but not between plasma leptin and SSNA. These data provide the first evidence that the sympathetic inhibition characterizing the early phase of acromegaly is not generalized to the entire cardiovascular system.

Clinical relevance of cardiac structure and function abnormalities in patients with Cushing's syndrome before and after cure.

OBJECTIVES: Sustained hypercortisolism impacts cardiac function, and, indeed, cardiac disease is one of the major determinants of mortality in patients with Cushing's syndrome. The aim of this study was to assess the clinical relevance of cardiac structure and function alterations by echocardiography in patients with active Cushing's syndrome and after disease remission. STUDY DESIGN: Seventy-one patients (61 women, 10 men) with Cushing's syndrome and 70 age-, sex- and blood pressure-matched controls were enrolled. Echocardiography was performed in 49 patients with active disease and at several time points after remission in 44 patients (median follow-up 46.4 months), and prevalence of abnormal left ventricular mass measurements and systolic and diastolic functions indices was compared between patients with active disease, after remission and controls. Twenty-two patients were evaluated both before and after remission. RESULTS: Up to 70% of patients with active Cushing's syndrome presented abnormal left ventricular mass parameters; 42% presented concentric hypertrophy and 23% concentric remodelling. Major indices of systolic and diastolic functions, i.e. ejection fraction and E/A ratio, respectively, were normal. Upon remission of hypercortisolism, left ventricular mass parameters ameliorated considerably, although abnormal values were still more frequent than in controls. Both cortisol excess and hypertension contribute to cardiac mass alterations and increase the prevalence of target organ damage. CONCLUSIONS: Cushing's syndrome is associated with an increased risk for abnormalities of cardiac mass, which ameliorates, but does not fully disappear after remission. Systolic and diastolic functions are largely within the normal range in these patients.

Postprandial triglyceride profile after a standardized oral fat load is altered in growth hormone (GH)-deficient adult patients and is not improved after short-term GH replacement therapy.

OBJECTIVE: Adult growth hormone deficiency (GHD) has detrimental effects on metabolic profile, leading to an increased cardiovascular mortality and morbidity. Above all, disturbance in postprandial triglyceride metabolism is of major concern because of the crucial role of triglyceride-rich lipoproteins in atherogenesis. The majority of previous studies on GH replacement have shown favourable changes in the fasting lipid profile. Aim of this study is to investigate whether this beneficial effect is exerted also on postprandial triglyceride (TG) metabolism. PATIENTS AND METHODS: We challenged nine GHD patients with a standardized fat loading meal at baseline and after 6 months of GH replacement therapy. Nine healthy control subjects were similarly tested under baseline conditions. Blood samples were obtained before and up to 8 h after fat loading for serum lipid analysis. RESULTS: We found that GHD patients with fasting TG level in the normal range (1·29 ± 0·31 mm) had a delayed postprandial TG clearance compared to healthy controls (triglyceride level at 8 h, 3·82 ± 0·83 vs 1 ± 0·06 mm P < 0·01), and the postprandial hypertriglyceridaemia was not corrected by 6 months of GH therapy. CONCLUSIONS: This study has shown for the first time that GHD adult patients have a higher postprandial triglyceridaemia compared to healthy controls when challenged by a standardized fat load and that this atherogenic feature is not normalized by short-term GH treatment despite a decrease in visceral fat mass described during the replacement therapy.

Von Willebrand factor and fibrinolytic parameters during the desmopressin test in patients with Cushing's disease.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Desmopressin is a known haemostatic agent and is also being used, albeit at lower doses, during the diagnostic work-up of Cushing's syndrome, a condition characterized by excess cortisol concentrations and frequent thromboembolic events. No study has yet evaluated whether administration of desmopressin for diagnostic purposes induces significant, adverse changes in endothelial cell markers in these patients. WHAT THIS STUDY ADDS: Administration of desmopressin to patients with Cushing's disease induces changes in endothelial cell markers comparable with those observed in obese and normal weight subjects. It follows, that desmopressin testing does not induce disease-specific untoward changes in coagulatory markers in patients with endogenous hypercortisolism and its use in this context appears safe. AIMS: Desmopressin, a vasopressin analogue, is used for various clinical purposes, including haemostasis and, in recent times, the diagnostic work-up of patients with Cushing's syndrome, a condition associated with a known prothrombotic profile. We decided to evaluate whether and to what extent a diagnostic dose of desmopressin induces significant changes in endothelial parameters in patients with Cushing's disease (CD) and obese and normal weight controls. METHODS: Twelve patients with CD, 10 obese and five normal weight controls were studied. Von Willebrand antigen (VWF:Ag), tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) were measured at baseline and up to 4 h after 10 µg desmopressin i.v. RESULTS: Desmopressin 10 µg transiently increased VWF:Ag and t-PA and decreased PAI-1 in all subjects. The magnitude of the VWF:Ag and t-PA increases after desmopressin was comparable in the three groups (VWF:Ag peak-to-basal ratio 1.9 ± 0.17, 1.5 ± 0.11 and 1.8 ± 0.13 and t-PA peak-to-basal ratio 1.6 ± 0.18, 1.6 ± 0.20 and 1.8 ± 0.24 for CD, obese and controls, respectively, all NS). The PAI-1 decrease observed in patients with CD was comparable with obese (0.7 ± 0.07 and 0.6 ± 0.09, NS) and controls (0.7 ± 0.07 vs. 0.4 ± 0.09, P= 0.08). CONCLUSIONS: Administration of desmopressin to patients with CD for diagnostic purposes induces a transitory increase in VWF:Ag counterbalanced by a decrease in PAI-1 and increase in t-PA. The magnitude of these changes is largely comparable with that observed in obese and normal weight controls. Our data show that testing with desmopressin does not induce disease-specific changes in endothelial markers in patients with CD.

Cushing's disease due to double pituitary ACTH-secreting adenomas: the first case report.

Double pituitary adenomas are rare occurrences in autoptical, surgical and neuroradiological series and are mostly due to non-functioning pituitary adenomas, GH-secreting and prolactin-secreting adenomas. ACTH secreting tumours are more rare and, to our knowledge, two distinct ACTH-producing adenomas within the same pituitary have never been reported. We herewith describe a 56 year old woman with Cushing' s disease due to two clearly distinct ACTH-secreting pituitary adenomas. She presented with signs and symptoms of hypercortisolism and hormonal testing was indicative for pituitary-dependent Cushing' s syndrome. Sellar MRI visualized an asymmetric pituitary gland with suspect lesions in both the right and the left pituitary lobes. Both lesions were removed during transsphenoidal surgery and remission of hypercortisolism ensued. Pathology confirmed the existence of two distinct adenomas located in different sites in the gland. Both presented ACTH immunoreactivity but displayed distinct morphological features. Our case indicates that double ACTH-secreting pituitary adenomas may occur in patients with Cushing' s disease. Careful radiological, surgical and pathological examination is necessary to recognize this condition and avoid surgical failure.

Potential role of type I interferons in the treatment of pituitary adenomas.

Cytokines, particularly those endowed with pro-inflammatory properties, are known to influence the release of anterior pituitary hormones by a direct and indirect action at the level of pituitary gland and hypothalamus. Type I interferons (IFNs) represent a group of cytokines that act through a common receptor composed by two chains (IFNAR-1 and IFNAR-2). Several in vitro and in vivo studies underline the fact that type I IFNs are involved in the regulation of the immune-endocrine circuitry. Treatment with type I IFNs of patients affected by chronic viral hepatitis, multiple sclerosis and tumors influences the secretion of pituitary hormones. This article reviews the current knowledge about the effects of IFN-alpha and IFN-beta on hypothalamic-pituitary function and describes the potential role of type I IFNs in the treatment of pituitary adenomas.

Differential diagnosis of ACTH-dependent hypercortisolism: imaging versus laboratory.

Differential diagnosis of ACTH-dependent Cushing's syndrome often presents major difficulties. Diagnostic troubles are increased by suboptimal specificity of endocrine tests, the rarity of ectopic ACTH secretion and the frequent incidental discovery of pituitary adenomas. A 43-year-old female reported with mild signs and symptoms of hypercortisolism, and initial hormonal tests and results of pituitary imaging (7-mm adenoma) were suggestive for Cushing's disease. However, inadequate response to corticotrophin-releasing hormone and failure to suppress after 8 mg dexamethasone pointed towards an ectopic source. Total body CT scan visualized only a small, non-specific nodule in the right posterior costophrenic excavation. Inferior petrosal sinus sampling revealed an absent center:periphery ACTH gradient but octreoscan and (18)F-FDG-PET-CT failed to detect abnormal tracer accumulation. We weighed results of the laboratory with those of imaging and decided to remove the lung nodule. Pathology identified a typical, ACTH-staining carcinoid and the diagnosis was confirmed by postsurgical hypoadrenalism. In conclusion, imaging may prove unsatisfactory or even misleading for the etiologial diagnosis of ACTH-dependent Cushing's syndrome and should therefore be interpreted only in context with results of hormonal dynamic testing.

Bone demineralization in adult thalassaemic patients: contribution of GH and IGF-I at different skeletal sites.

BACKGROUND AND OBJECTIVE: GH and IGF-I exert an important role in the control of bone formation, as shown by decreased bone mineral density and increased fracture risk in adult hypopituitary patients untreated for GH deficiency (GHD). Different degrees of bone demineralization are frequently reported in patients affected by beta-thalassaemia. Considering the high prevalence of GHD recently observed by our group among adult thalassaemic patients, we elected to study the possible role of GH-IGF-I abnormalities in the pathogenesis of the osteopenia/osteoporosis of this disease. DESIGN: Sixty-four adult thalassaemic patients (49 with thalassaemia major and 15 with thalassaemia intermedia, 23 men and 41 women, aged 31.4 +/- 6.8 years) were studied. METHODS: Bone mineral density was assessed by dual energy X-ray absorptiometry at lumbar spine in 62 patients and at proximal femur in 58. All patients underwent GHRH (1 microg/kg as an i.v. bolus) plus arginine (0.5 g/kg as a 30-min i.v. infusion) testing. Severe GHD was defined by GH peaks < 9 microg/l, whereas partial GHD was defined by GH peaks ranging from 9 to 16.5 microg/l. Blood samples for IGF-I measurement were collected. RESULTS: Lumbar osteoporosis and osteopenia were demonstrated in 46/62 (74.1%) and 14/62 (22.5%) patients, respectively. Femoral osteoporosis and osteopenia were documented in 22/58 (37.9%) and 32/58 (55.1%) patients, respectively. Severe GHD was demonstrated in 16/64 patients (25%), while 11 additional patients (17.1%) displayed partial GHD. IGF-I standard deviation score (SDS) was low, that is, below -1.88, in the majority (54.6%) of patients. Lumbar T-score values were not correlated with either GH peaks or IGF-I SDS values. Femoral T-score values were positively correlated with GH peaks (r = 0.38, P < 0.005) and IGF-I SDS values (r = 0.39, P < 0.005). Multiple regression analysis pointed to both GH peak and IGF-I SDS as predictors of femoral T-score. Furthermore, mean femoral T-score was significantly lower in patients with severe GHD than in those with normal GH secretion (-2.94 +/- 0.25 vs.-2.15 +/- 0.12, P < 0.01). CONCLUSION: This study, while confirming the high prevalence of both osteopenia/osteoporosis and somatotropin-somatomedin deficiency in adult thalassaemic patients, indicates that defective GH secretion and diminished serum IGF-I levels may contribute to femoral demineralization in these patients. Further studies are worth carrying out to evaluate the efficacy of biosynthetic GH administration on bone abnormalities of GH-deficient thalassaemic adults.

Low insulin-like growth factor I and leukopenia in anorexia nervosa.

OBJECTIVE: Considering that leukopenia and anemia are commonly observed in anorexia nervosa (AN) and that growth hormone (GH) and insulin-like growth factor-I (IGF-I) markedly influence the activation, growth and survival of hemopoietic cells, we sought for possible relationships between hematologic parameters and the GH-IGF-I axis in a group of patients with AN. METHOD: Twenty patients were studied. Leukocyte and erythrocyte counts, as well as baseline serum GH levels and IGF-I standard deviation score (SDS) values, were determined in each participant and correlations between parameters were searched. RESULTS: Leukocyte and erythrocyte counts, as well as IGF-I SDS values, were significantly lower, conversely GH was significantly higher in AN patients than in normal weight participants. In patients, IGF-I SDS values were positively correlated with leukocyte count and BMI, whereas no correlation was found between IGF-I SDS and hemoglobin or erythrocytes. CONCLUSION: The demonstration of a positive correlation between leukocyte number and circulating IGF-I in AN suggests a likely pathogenetic role of IGF-I deficiency in this hematologic abnormality.

Neuroendocrine control of food intake.

Appetite is regulated by a complex system of central and peripheral signals which interact in order to modulate the individual response to nutrient ingestion. Peripheral regulation includes satiety signals and adiposity signals, while central control is accomplished by several effectors, including the neuropeptidergic, monoaminergic and endocannabinoid systems. Satiety signals, including cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), originate from the gastrointestinal (GI) tract during a meal and, through the vagus nerve, reach the nucleus tractus solitarius (NTS) in the caudal brainstem. From NTS afferents fibers project to the arcuate nucleus (ARC), where satiety signals are integrated with adiposity signals, namely leptin and insulin, and with several hypothalamic and supra-hypothalamic inputs, thus creating a complex network of neural circuits which finally elaborate the individual response to a meal. As for the neuropeptidergic system, ARC neurons secrete orexigenic substances, such as neuropeptide Y (NPY) and agouti-related peptide (AGRP), and anorexigenic peptides such as pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART). Other brain areas involved in the control of food intake are located downstream the ARC: among these, the paraventricular nucleus (PVN), which produces anorexigenic peptides such as thyrotropin releasing hormone (TRH), corticotrophin releasing hormone (CRH) and oxytocin, the lateral hypothalamus (LHA) and perifornical area (PFA), secreting the orexigenic substances orexin-A (OXA) and melanin concentrating hormone (MCH). A great interest in endocannabinoids, important players in the regulation of food intake, has recently developed. In conclusion, the present work reviews the most recent insights into the complex and redundant molecular mechanisms regulating food intake, focusing on the most encouraging perspectives for the treatment of obesity.

Role of the ubiquitin/proteasome system on ACTH turnover in rat corticotropes.

PURPOSE: A large number of studies has investigated proopiomelanocortin processing in anterior pituitary corticotropes but little is known on proopiomelanocortin/ACTH degradation within these cells. The ubiquitin-proteasome system is an intracellular protein degradation pathway which has garnered considerable interest in recent times, given its role in maintenance of protein homeostasis. Aim of the present study was to evaluate the role of the ubiquitin-proteasome system in proopiomelanocortin/ACTH turnover in pituitary corticotropes. METHODS: Rat anterior pituitary primary cultures were treated with 0.01-100 nM MG132, a proteasome inhibitor, or 0.1-100 nM K48R, an inhibitor of polyubiquitylation, for 4 and 24 h and ACTH concentrations in medium and cell lysates estimated by immunometric assay. Co-immunoprecipitation for ubiquitin and ACTH was carried out to establish ubiquitin-tagged protein products. RESULTS: Inhibition of proteasome-mediated degradation with MG132 lead to an increase in ACTH concentrations, both as regards secretion and cell content. Likewise, inhibition of polyubiquitylation was associated with increased ACTH secretion and cell content. Ubiquitin/ACTH co-immunoprecipitation revealed that proopiomelanocortin was a target of ubiquitylation. CONCLUSIONS: We provide the first evidence that the ubiquitin-proteasome system is involved in proopiomelanocortin/ACTH degradation in corticotropes. Indeed, proopiomelanocortin is a target of ubiquitylation and modulation of ubiquitin-proteasome system affects ACTH turnover. This study shows that regulation of ACTH proteolytic degradation may represent a means to control ACTH secretion.

Gene expression profiling in human corticotroph tumours reveals distinct, neuroendocrine profiles.

Adrenocorticotrophic hormone (ACTH)-secreting pituitary adenomas give rise to a severe endocrinological disorder, comprising Cushing's disease, with multifaceted clinical presentation and treatment outcomes. Experimental studies suggest that the disease variability is inherent to the pituitary tumour, thus indicating the need for further studies into tumour biology. The present study evaluated transcriptome expression pattern in a large series of ACTH-secreting pituitary adenoma specimens in order to identify molecular signatures of these tumours. Gene expression profiling of formalin-fixed, paraffin-embedded specimens from 40 human ACTH-secreting pituitary adenomas revealed the significant expression of genes involved in protein biosynthesis and ribosomal function, in keeping with the neuroendocrine cell profile. Unsupervised cluster analysis identified 3 distinct gene profile clusters and several genes were uniquely overexpressed in a given cluster, accounting for different molecular signatures. Of note, gene expression profiles were associated with clinical features, such as the age and size of the tumour. Altogether, the findings of the present study show that corticotroph tumours are characterised by a neuroendocrine gene expression profile and present subgroup-specific molecular features.

Specificity of first-line tests for the diagnosis of Cushing's syndrome: assessment in a large series.

CONTEXT: The diagnosis of Cushing's syndrome requires highly sensitive screening tests. Therefore, diagnostic cutoffs have been lowered to maximize sensitivity and identify all patients. However, few studies have investigated the impact of these refinements on the specificity of first-line tests. OBJECTIVE: The aim of the study was the assessment of the specificity of three widely used screening tests in a large series of Cushing's syndrome suspects referred to our endocrine service. PATIENTS: We retrospectively reviewed the results of urinary free cortisol (UFC), 1-mg dexamethasone suppression test [overnight suppression test (OST)], and serum cortisol at midnight in 3,461, 357, and 864 patients, respectively, with clinical features suggestive of Cushing's syndrome but in whom this diagnosis was subsequently excluded. RESULTS: UFC and OST at the 5-microg/dl cutoff exhibited the highest specificities [91% (95% confidence intervals [CI] 90.2-92.1%) and 97% (95% CI 96.3-98.5%), respectively]. Conversely, midnight serum cortisol yielded 87% (95% CI 84.3-91.1%) specificity only with the 7.5-microg/dl cutoff, whereas the 1.8-microg/dl threshold resulted in an unacceptably high proportion of false positives at only 20% specificity (95% CI 16.0-24.4%). Gender and age may lead to misleading results in all three screening tests. CONCLUSIONS: Specificity of tests for Cushing's syndrome varies considerably, with OST and UFC presenting the best performances, and circadian rhythm appearing heavily impaired by lowering of diagnostic cutoffs. Indeed, the vast majority of individuals in our series presented midnight serum cortisol values greater than 1.8 microg/dl; thus, caution has to be exercised when this criterion is used to exclude Cushing's syndrome.

Aryl hydrocarbon receptor-interacting protein gene mutations in familial isolated pituitary adenomas: analysis in 73 families.

CONTEXT: An association between germline aryl hydrocarbon receptor-interacting protein (AIP) gene mutations and pituitary adenomas was recently shown. OBJECTIVE: The objective of the study was to assess the frequency of AIP gene mutations in a large cohort of patients with familial isolated pituitary adenoma (FIPA). DESIGN: This was a multicenter, international, collaborative study. SETTING: The study was conducted in 34 university endocrinology and genetics departments in nine countries. PATIENTS: Affected members from each FIPA family were studied. Relatives of patients with AIP mutations underwent AIP sequence analysis. MAIN OUTCOME MEASURES: Presence/absence and description of AIP gene mutations were the main outcome measures. INTERVENTION: There was no intervention. RESULTS: Seventy-three FIPA families were identified, with 156 patients with pituitary adenomas; the FIPA cohort was evenly divided between families with homogeneous and heterogeneous tumor expression. Eleven FIPA families had 10 germline AIP mutations. Nine mutations, R16H, G47_R54del, Q142X, E174frameshift, Q217X, Q239X, K241E, R271W, and Q285frameshift, have not been described previously. Tumors were significantly larger (P = 0.0005) and diagnosed at a younger age (P = 0.0006) in AIP mutation-positive vs. mutation-negative subjects. Somatotropinomas predominated among FIPA families with AIP mutations, but mixed GH/prolactin-secreting tumors, prolactinomas, and nonsecreting adenomas were also noted. Approximately 85% of the FIPA cohort and 50% of those with familial somatotropinomas were negative for AIP mutations. CONCLUSIONS: AIP mutations, of which nine new mutations have been described here, occur in approximately 15% of FIPA families. Although pituitary tumors occurring in association with AIP mutations are predominantly somatotropinomas, other tumor types are also seen. Further study of the impact of AIP mutations on protein expression and activity is necessary to elucidate their role in pituitary tumorigenesis in FIPA.

Significant GH deficiency after long-term cure by surgery in adult patients with Cushing's disease.

OBJECTIVE: Impaired GH secretion usually accompanies Cushing's syndrome and a variable proportion of patients reportedly fail to recover normal GH secretion after successful treatment. This wide variability is most probably due to differences in the treatment (i.e. surgery and/or radiotherapy), timing of patient re-evaluation after surgery and dynamic tests employed to challenge GH secretion, and hinders a precise assessment of risk of GH deficiency after cure. The aim of the present study is to evaluate GH secretory status after long-term cure of Cushing's disease achieved by surgery alone. DESIGN AND METHODS: We studied 34 patients (27 females and 7 males, age range 21-68 years) formerly affected by Cushing's disease. Patients were studied 2-20 years (median 3.3 years) following remission of hypercortisolism; all patients underwent transsphenoidal surgery with the removal of an ACTH-secreting adenoma; repeat pituitary surgery for relapse was performed in two patients while bilateral adrenalectomy was necessary in two patients. In all subjects, the GH response to GHRH+arginine stimulation was evaluated. At the time of testing, 13 patients were still on steroid replacement therapy. RESULTS: In long-term surgical remission, 22 patients (65.0%) presented subnormal GH secretion; partial GH deficiency (GH peak <16.5 microg/l) was found in 11 patients and severe GH deficiency (GH peak <9 microg/l) in another 11. Male gender and length of hypercortisolism were risk factors for postsurgical GH deficiency. CONCLUSIONS: This study demonstrates the presence of GH deficiency in a high percentage of patients with Cushing's disease after long-term remission of hypercortisolism obtained by surgery alone. Male gender and length of hypercortisolism are the most significant predictors of postsurgical GH deficiency. This finding is significant as it highlights that even the most favourable therapeutical course, i.e. remission achieved by surgery alone, is accompanied by impaired GH secretion. Assessment of GH secretion is therefore recommended for all patients cured from Cushing's disease, even if not submitted to radiotherapy. Studies on the clinical impact of GH deficiency and the use of GH replacement therapy seem warranted in patients cured from Cushing's disease.

Proopiomelanocortin, glucocorticoid, and CRH receptor expression in human ACTH-secreting pituitary adenomas.

ACTH-secreting pituitary tumors are by definition partially autonomous, i.e., secrete ACTH independent of physiological control. However, only few, small-sized studies on proopiomelanocortin (POMC) and its regulation by corticotropin-releasing hormone (CRH) or glucocorticoids are available. Objective of the present study was to report on constitutive and CRH- and dexamethasone-regulated POMC, CRH (CRH-R1), and glucocorticoid receptor (NR3C1) gene expression in a large series of human corticotrope adenomas. Fifty-three ACTH-secreting adenomas were incubated with 10 nM CRH or 10 nM dexamethasone for 24 h. POMC, CRH-R1, NR3C1, and its alpha and beta isoforms were quantified and medium ACTH measured. Constitutive POMC expression proved extremely variable, with macroadenomas exhibiting higher levels than microadenomas. POMC increased during CRH in most specimens; conversely, changes induced by dexamethasone were varied, ranging from decrease to paradoxical increase. No correlation between POMC and ACTH was detected in any experimental condition. CRH-R1 expression was not linked to the response to CRH while NR3C1 was expressed at greater levels in specimens who failed to inhibit during dexamethasone; glucocorticoid receptor α was the more abundant isoform and subject to down-regulation by dexamethasone. Our results demonstrate a considerable variability in POMC expression among tumors and no correlation between POMC and ACTH, suggesting that POMC peptide processing/transport plays a major role in modulating ACTH secretion. Further, CRH-R1 and NR3C1 expression were not linked to the expected ligand-induced outcome, indicating that receptor signaling rather than abundance determines corticotrope responses. Our findings pave the way to new avenues of research into Cushing's disease pathophysiology.

Usefulness of desmopressin testing to predict relapse during long-term follow-up in patients in remission from Cushing's disease.

Recurrence of Cushing's disease after successful transsphenoidal surgery occurs in some 30% of the patients and the response to desmopressin shortly after surgery has been proposed as a marker for disease recurrence. The aim of the present study was to evaluate the response to desmopressin over time after surgery. We tested 56 patients with Cushing's disease in remission after transsphenoidal surgery with desmopressin for up to 20 years after surgery. The ACTH and cortisol response to desmopressin over time was evaluated in patients on long-term remission or undergoing relapse; an increase by at least 27 pg/mL in ACTH levels identified responders. The vast majority of patients who underwent successful adenomectomy failed to respond to desmopressin after surgery and this response pattern was maintained over time in patients on long-term remission. Conversely, a response to desmopressin reappeared in patients who subsequently developed a recurrence of Cushing's disease, even years prior to frank hypercortisolism. It appears therefore that a change in the response pattern to desmopressin proves predictive of recurrence of Cushing's disease and may indicate which patients require close monitoring.

Hypopituitarism.

Hypopituitarism is the partial or complete insufficiency of anterior pituitary hormone secretion and may result from pituitary or hypothalamic disease. The reported incidence (12-42 new cases per million per year) and prevalence (300-455 per million) is probably underestimated if its occurrence after brain injuries (30-70% of cases) is considered. Clinical manifestations depend on the extent of hormone deficiency and may be non specific, such as fatigue, hypotension, cold intolerance, or more indicative such as growth retardation or impotence and infertility in GH and gonadotropin deficiency, respectively.A number of inflammatory, granulomatous or neoplastic diseases as well as traumatic or radiation injuries involving the hypothalamic-pituitary region can lead to hypopituitarism. Several genetic defects are possible causes of syndromic and non syndromic isolated/multiple pituitary hormone deficiencies. Unexplained gonadal dysfunctions, developmental craniofacial abnormalities, newly discovered empty sella and previous pregnancy-associated hemorrhage or blood pressure changes may be associated with defective anterior pituitary function.The diagnosis of hypopituitarism relies on the measurement of basal and stimulated secretion of anterior pituitary hormones and of the hormones secreted by pituitary target glands. MR imaging of the hypothalamo-pituitary region may provide essential information. Genetic testing, when indicated, may be diagnostic.Secondary hypothyroidism is a rare disease. The biochemical diagnosis is suggested by low serum FT4 levels and inappropriately normal or low basal TSH levels that do not rise normally after TRH. L-thyroxine is the treatment of choice. Before starting replacement therapy, concomitant corticotropin deficiency should be excluded in order to avoid acute adrenal insufficiency. Prolactin deficiency is also very rare and generally occurs after global failure of pituitary function. Prolactin deficiency prevents lactation. Hypogonadotropic hypogonadism in males is characterized by low testosterone with low or normal LH and FSH serum concentrations and impaired spermatogenesis. Hyperprolactinemia as well as low sex hormone binding globulin concentrations enter the differential diagnosis. Irregular menses and amenorrhea with low serum estradiol concentration (<100 pmol/l) and normal or low gonadotropin concentrations are the typical features of hypogonadotropic hypogonadism in females. In post menopausal women, failure to detect high serum gonadotropin values is highly suggestive of the diagnosis. In males, replacement therapy with oral or injectable testosterone results in wide fluctuations of serum hormone levels. More recently developed transdermal testosterone preparations allow stable physiological serum testosterone levels. Pulsatile GnRH administration can be used to stimulate spermatogenesis in men and ovulation in women with GnRH deficiency and normal gonadotropin secretion. Gonadotropin administration is indicated in cases of gonadotropin deficiency or GnRH resistance but is also an option, in alternative to pulsatile GnRH, for patients with defective GnRH secretion.

Acromegaly.

Acromegaly is a slowly progressive disease characterized by 30% increase of mortality rate for cardiovascular disease, respiratory complications and malignancies. The estimated prevalence of the disease is 40 cases/1000000 population with 3-4 new cases/1000000 population per year. The biochemical diagnosis is based upon the demonstration of high circulating levels of GH and IGF-I. A random GH level lower than 0.4 microg/l and an IGF-I value in the age- and sex-matched normal range makes the diagnosis of acromegaly unlikely. In doubtful cases, the lack of GH suppressibility below 1 microg/l (0.3 microg/l according to recent reports) after an oral glucose load will confirm the diagnosis. A pituitary adenoma is demonstrated in most cases by CT scan or MRI. A negative X-ray finding or the presence of empty sella do not exclude the diagnosis. Cardiovascular complications (acromegalic cardiomyopathy and arterial hypertension) should be looked for and, if present, followed-up by echocardiography and 24h-electrocardiogram. Sleep apnoea, when clinically suspicious, should be confirmed by polisomnography. At the moment of diagnosis all patients should undergo colonscopy. Lipid profile should be obtained and glucose tolerance evaluated. Surgery, radiotherapy and medical treatment represent the therapeutic options for acromegaly. The outcome of transsphenoidal surgery is far better for microadenomas (80-90%) than for macroadenomas (less than 50%), which unluckily represent more than 70% of all GH-secreting pituitary tumours. Therefore, pituitary surgery is the first line treatment for microadenomas. Medical therapy is based on GH-lowering drugs (somatostatin receptor agonists and, in some cases, dopaminergic agents) and GH receptor antagonists (pegvisomant). The former are traditionally indicated after unsuccessful surgery and while awaiting the effectiveness of radiation therapy. However, GH-lowering drugs are also used as primary therapy when surgery is contraindicated or in the case of large GH-secreting macroadenomas which are not likely to be completely removed by surgery. These compounds may also be indicated in the preoperative management of some acromegalic patients in order to lower the risk of surgical and anaesthetic complications. For the moment pegvisomant is indicated for patients resistant to the GH-lowering drugs and there is no evidence for drug-induced enlargement of the pituitary tumour. In order to avoid this possibility, however, a combination of pegvisomant and GH-lowering compound can also be conceived. With pegvisomant, IGF-I plasma levels are the marker of therapeutic efficacy and normalize in 97% of patients. Radiotherapy is employed sparingly due to the number of side effects (80% of hypopituitarism). It is indicated after unsuccessful surgical and/or medical treatment and allows the control of hormonal secretion and tumour growth in approx. 40% and 100% of cases, respectively. Acromegaly is defined as controlled when, in the absence of clinical activity, IGF-I levels are in the age- and sex-matched normal range and GH is normally suppressible by the oral glucose load.