Chronic adult-onset of growth hormone/IGF-I hypersecretion improves cognitive functions and LTP and promotes neuronal differentiation in adult rats.

AIM: Besides their metabolic and endocrine functions, the growth hormone (GH) and its mediated factor, the insulin-like growth factor I (IGF-I), have been implicated in different brain functions, including neurogenesis. Long-lasting elevated GH and IGF-I levels result in non-reversible somatic, endocrine and metabolic morbidities. However, the subcutaneous implantation of the GH-secreting (GH-S) GC cell line in rats leads to the controllable over-secretion of GH and elevated IGF-I levels, allowing the experimental study of their short-term effects on brain functions. METHODS: Adult rats were implanted with GC cells and checked 10 weeks later, when a GH/IGF-I-secreting tumour was already formed. RESULTS: Tumour-bearing rats acquired different operant conditioning tasks faster and better than controls and tumour-resected groups. They also presented better retentions of long-term memories in the passive avoidance test. Experimentally evoked long-term potentiation (LTP) in the hippocampus was also larger and longer lasting in the tumour bearing than in the other groups. Chronic adult-onset of GH/IGF-I hypersecretion caused an acceleration of early progenitors, facilitating a faster neural differentiation, maturation and integration in the dentate gyrus, and increased the complexity of dendritic arbours and spine density of granule neurons. CONCLUSION: Thus, adult-onset hypersecretion of GH/IGF-I improves neurocognitive functions, long-term memories, experimental LTP and neural differentiation, migration and maturation.

The Molecular Registry of Pituitary Adenomas (REMAH): A bet of Spanish Endocrinology for the future of individualized medicine and translational research. / El Registro Molecular de Adenomas Hipofisarios (REMAH): una apuesta de futuro de la Endocrinología española por la medicina individualizada y la investigación traslacional.

Pituitary adenomas are uncommon, difficult to diagnose tumors whose heterogeneity and low incidence complicate large-scale studies. The Molecular Registry of Pituitary Adenomas (REMAH) was promoted by the Andalusian Society of Endocrinology and Nutrition (SAEN) in 2008 as a cooperative clinical-basic multicenter strategy aimed at improving diagnosis and treatment of pituitary adenomas by combining clinical, pathological, and molecular information. In 2010, the Spanish Society of Endocrinology and Nutrition (SEEN) extended this project to national level and established 6 nodes with common protocols and methods for sample and clinical data collection, molecular analysis, and data recording in a common registry (www.remahnacional.com). The registry combines clinical data with molecular phenotyping of the resected pituitary adenoma using quantitative real-time PCR of expression of 26 genes: Pituitary hormones (GH-PRL-LH-FSH-PRL-ACTH-CGA), receptors (somatostatin, dopamine, GHRH, GnRH, CRH, arginine-vasopressin, ghrelin), other markers (Ki67, PTTG1), and control genes. Until 2015, molecular information has been collected from 704 adenomas, out of 1179 patients registered. This strategy allows for comparative and relational analysis between the molecular profile of the different types of adenoma and the clinical phenotype of patients, which may provide a better understanding of the condition and potentially help in treatment selection. The REMAH is therefore a unique multicenter, interdisciplinary network founded on a shared database that provides a far-reaching translational approach for management of pituitary adenomas, and paves the way for the conduct of combined clinical-basic innovative studies on large patient samples.

The Effects of Bariatric Surgery-Induced Weight Loss on Adipose Tissue in Morbidly Obese Women Depends on the Initial Metabolic Status.

BACKGROUND: Adipose tissue (AT) dysfunction in obesity is commonly linked to insulin resistance and promotes the development of metabolic disease. Bariatric surgery (BS) represents an effective strategy to reduce weight and to improve metabolic health in morbidly obese subjects. However, the mechanisms and pathways that are modified in AT in response to BS are not fully understood, and few information is still available as to whether these may vary depending on the metabolic status of obese subjects. METHODS: Abdominal subcutaneous adipose tissue (SAT) samples were obtained from morbidly obese women (n = 18) before and 13.3 ± 0.37 months after BS. Obese women were stratified into two groups: normoglycemic (NG; Glu < 100 mg/dl, HbA1c <5.7 %) or insulin resistant (IR; Glu 100-126 mg/dl, HbA1c 5.7-6.4 %) (n = 9/group). A multi-comparative proteomic analysis was employed to identify differentially regulated SAT proteins by BS and/or the degree of insulin sensitivity. Serum levels of metabolic, inflammatory, and anti-oxidant markers were also analyzed. RESULTS: Before surgery, NG and IR subjects exhibited differences in AT proteins related to inflammation, metabolic processes, the cytoskeleton, and mitochondria. BS caused comparable weight reductions and improved glucose homeostasis in both groups. However, BS caused dissimilar changes in metabolic enzymes, inflammatory markers, cytoskeletal components, mitochondrial proteins, and angiogenesis regulators in NG and IR women. CONCLUSIONS: BS evokes significant molecular rearrangements indicative of improved AT function in morbidly obese women at either low or high metabolic risk, though selective adaptive changes in key cellular processes occur depending on the initial individual's metabolic status.

Molecular Characterization of Growth Hormone-producing Tumors in the GC Rat Model of Acromegaly.

Acromegaly is a disorder resulting from excessive production of growth hormone (GH) and consequent increase of insulin-like growth factor 1 (IGF-I), most frequently caused by pituitary adenomas. Elevated GH and IGF-I levels results in wide range of somatic, cardiovascular, endocrine, metabolic, and gastrointestinal morbidities. Subcutaneous implantation of the GH-secreting GC cell line in rats leads to the formation of tumors. GC tumor-bearing rats develop characteristics that resemble human acromegaly including gigantism and visceromegaly. However, GC tumors remain poorly characterized at a molecular level. In the present work, we report a detailed histological and molecular characterization of GC tumors using immunohistochemistry, molecular biology and imaging techniques. GC tumors display histopathological and molecular features of human GH-producing tumors, including hormone production, cell architecture, senescence activation and alterations in cell cycle gene expression. Furthermore, GC tumors cells displayed sensitivity to somatostatin analogues, drugs that are currently used in the treatment of human GH-producing adenomas, thus supporting the GC tumor model as a translational tool to evaluate therapeutic agents. The information obtained would help to maximize the usefulness of the GC rat model for research and preclinical studies in GH-secreting tumors.

Genetically engineered mouse models of pituitary tumors.

Animal models constitute valuable tools for investigating the pathogenesis of cancer as well as for preclinical testing of novel therapeutics approaches. However, the pathogenic mechanisms of pituitary-tumor formation remain poorly understood, particularly in sporadic adenomas, thus, making it a challenge to model pituitary tumors in mice. Nevertheless, genetically engineered mouse models (GEMMs) of pituitary tumors have provided important insight into pituitary tumor biology. In this paper, we review various GEMMs of pituitary tumors, highlighting their contributions and limitations, and discuss opportunities for research in the field.

Desmopressin test in the diagnosis and follow-up of cyclical Cushing's disease.

OBJECTIVE: To assess the utility of the desmopressin (DDAVP) test in the diagnosis and follow-up of a cyclical Cushing's disease (CCS) case. MATERIAL AND METHODS: Laboratory tests included morning and midnight serum cortisol levels, 24h urine free cortisol excretion, midnight salivary cortisol levels, serum cortisol levels after low (1 mg) and high (8 mg) dexamethasone, plasma ACTH and serum cortisol levels after DDAVP. Magnetic resonance imaging (MRI) was used to assess the presence of a pituitary adenoma. The resected tumor specimen was studied by histological, immunohistochemical and cell biology techniques. RESULTS: A patient was referred to our unit with a diagnosis of Cushing's syndrome (CS) for further evaluation and treatment. However, no biochemical evidence of hypercortisolism was observed in the follow-up evaluations. Furthermore, the typical features of CS fluctuated throughout this period. A consistent positive response to the DDAVP stimulation test was observed during the diagnostic work-up, even when overt clinical features of CS were not apparent, raising suspicion for CCS. After two years of follow-up a definitive diagnosis of hypercortisolism was established. An MRI scan revealed a pituitary adenoma, as the source of ACTH production. After transphenoidal surgery, clinical signs of CS resolved and the response to DDAVP became negative. DDAVP induced a significant increase in ACTH levels in cultured pituitary adenoma cells, consistent with the in vivo DDAVP test results. CONCLUSIONS: Our case illustrates the utility of the DDAVP test in the evaluation of patients with suspected CCS. The DDAVP test could facilitate the management of CCS by shortening the time of diagnosis.

Neurocognitive function in acromegaly after surgical resection of GH-secreting adenoma versus naïve acromegaly.

Patients with active untreated acromegaly show mild to moderate neurocognitive disorders that are associated to chronic exposure to growth hormone (GH) and insulin-like growth factor (IGF-I) hypersecretion. However, it is unknown whether these disorders improve after controlling GH/IGF-I hypersecretion. The aim of this study was to compare neurocognitive functions of patients who successfully underwent GH-secreting adenoma transsphenoidal surgery (cured patients) with patients with naive acromegaly. In addition, we wanted to determine the impact of different clinical and biochemical variables on neurocognitive status in patients with active disease and after long-term cure. A battery of six standardized neuropsychological tests assessed attention, memory and executive functioning. In addition, a quantitative electroencephalography with Low-Resolution Electromagnetic Tomography (LORETA) solution was performed to obtain information about the neurophysiological state of the patients. Neurocognitive data was compared to that of a healthy control group. Multiple linear regression analysis was also conducted using clinical and hormonal parameters to obtain a set of independent predictors of neurocognitive state before and after cure. Both groups of patients scored significantly poorer than the healthy controls on memory tests, especially those assessing visual and verbal recall. Patients with cured acromegaly did not obtain better cognitive measures than naïve patients. Furthermore memory deficits were associated with decreased beta activity in left medial temporal cortex in both groups of patients. Regression analysis showed longer duration of untreated acromegaly was associated with more severe neurocognitive complications, regardless of the diagnostic group, whereas GH levels at the time of assessment was related to neurocognitive outcome only in naïve patients. Longer duration of post-operative biochemical remission of acromegaly was associated with better neurocognitive state. Overall, this data suggests that the effects of chronic exposure to GH/IGF-I hypersecretion could have long-term effects on brain functions.

Rationale and design of PATRO Adults, a multicentre, noninterventional study of the long-term efficacy and safety of Omnitrope(®) for the treatment of adult patients with growth hormone deficiency.

OBJECTIVE: To describe the rationale and design of PATRO Adults, a postmarketing surveillance study of the long-term efficacy and safety of somatropin (Omnitrope(®)) for the treatment of adult patients with growth hormone deficiency (GHD). METHODS: PATRO Adults is an observational, multicentre, open, longitudinal, noninterventional study being conducted in hospitals and specialized endocrinology clinics across several European countries. The primary objective is to assess the safety and efficacy of Omnitrope(®) in adults treated in routine clinical practice. Eligible patients are male or female adults who are receiving treatment with Omnitrope(®) and who have provided informed consent. Patients who have been treated with another human growth hormone (hGH) product before starting Omnitrope(®) therapy will also be eligible for inclusion. Efficacy assessments will be based on the analysis of the following: insulin-like growth factor-1 levels within age- and gender-adjusted normal ranges; anthropometric measures (weight, waist circumference, total fat mass, lean body mass, total body water); bone mineral density; lipids; effects on cardiovascular risk factors such as glucose metabolism, blood pressure and inflammatory markers (e.g. C-reactive protein); and quality of life. All adverse events will be monitored and recorded. Particular emphasis will be placed on long-term safety, the recording of malignancies, the occurrence and clinical impact of antirecombinant hGH antibodies, the incidence, severity and duration of hyperglycaemia, and the development of diabetes during treatment with Omnitrope(®). CONCLUSIONS: PATRO Adults is a large, long-term, postmarketing surveillance study that will extend the safety database for Omnitrope(®), as well as contributing to the available data for all recombinant hGH products. Of particular interest, the study will provide important data on the impact of long-term GH replacement therapy on the development of diabetes mellitus, the recurrence/regrowth of hypothalamic-pituitary tumours, and de novo malignancy or recurrence of other (non-hypothalamic-pituitary) tumours.

Measurement of oxidative stress and endothelial dysfunction in patients with hypopituitarism and severe deficiency adult growth hormone deficiency.

Patients with adult GH deficiency (AGHD) have a high cardiovascular risk and probably an alteration of the oxidative balance, although evidence is lacking. To evaluate the presence of endothelial dysfunction and oxidative stress in patients with AGHD. Biochemical parameters of oxidative stress and endothelial dysfunction were compared in 25 patients with previously untreated AGHD and 25 healthy controls matched by age and sex. Multivariate analysis was performed to identify independent predictors of oxidative stress. Vascular function of subcutaneous resistance arteries was also analyzed by means of wire myography in 7 patients with untreated AGHD and in 7 healthy controls with similar characteristics. The values of C-reactive protein, interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-α), were higher in the AGHD group (4.6 vs. 0.2 µg/L, P = 0.02; 5.6 vs. 1.2 pg/mL, P = 0.001; 6.7 vs. 2.1 pg/mL, P = 0.04; respectively). The levels of type-1 vascular cell adhesion molecule, total anti-oxidant state, oxidized LDL (LDL-ox) were also greater in AGHD patients (678 vs. 423 ng/mL, P = 0.004; 1235.6 vs. 1002.3 µmol/L, P = 0.01; 172.2.5 vs. 42.3 ng/mL, P = 0.02; respectively). Nitric oxide (NO), reduced glutathione (GSH) and reduced/oxidized glutathione ratio (GSH/GSSG) values were lower than controls (18.7 vs. 31.6 mmol/mg protein, P = 0.01; 372.2 vs. 756.2 µmol/L, P = 0.03; 17.2 vs. 38.4, P = 0.04; respectively). Multiple regression analysis showed that AGHD was an independent predictor of increased LDL-ox (P = 0.002) and decreased GSH (P = 0.000). Furthermore, the degree of vascular relaxation to repeated exposure of acetylcholine was lower in AGHD (P = 0.025). Patients with AGHD have an increased degree of oxidative stress and endothelial dysfunction that could already be present in early stages of the disease. Studies with a greater number of patients are needed in order to confirm our findings.

Expression of functional KISS1 and KISS1R system is altered in human pituitary adenomas: evidence for apoptotic action of kisspeptin-10.

CONTEXT: KISS1 was originally identified as a metastasis-suppressor gene able to inhibit tumor progression. KISS1 gene products, the kisspeptins, bind to a G-protein-coupled receptor (KISS1R, formerly GPR54), which is highly expressed in placenta, pituitary, and pancreas, whereas KISS1 mRNA is mainly expressed in placenta, hypothalamus, striatum, and pituitary. OBJECTIVE AND DESIGN: KISS1/KISS1R pituitary expression profile, coupled to their anti-tumoral capacities, led us to hypothesize that this system may be involved in the biology of pituitary tumors. To explore this notion, expression levels of KISS1R and KISS1 were evaluated in normal and adenomatous pituitaries. Additionally, functionality of this system was assessed by treating dispersed pituitary adenoma cells in primary culture with kisspeptin-10 and evaluating intracellular calcium kinetics and apoptotic rate. RESULTS: Both KISS1 and KISS1R were expressed in normal pituitary, whereas this simultaneous expression was frequently lost in pituitary tumors, where diverse patterns of KISS1/KISS1R expression were observed that differed among distinct types of pituitary adenomas. Measurement of calcium kinetics revealed that kisspeptin-10 elicits a remarkable increase in [Ca(2+)](i) in individual cells from four out of the five GH-producing adenomas studied, whereas cells derived from non-functioning pituitary adenomas (NFPA, n=45) did not respond. In contrast, kisspeptin-10 treatment increased the apoptotic rate in cells derived from both GH-producing and NFPA. CONCLUSIONS: These results provide primary evidence that KISS1 and KISS1R expression can be differentially lost in pituitary tumor subtypes, where this system can exert functional, proapoptotic actions, and thereby offer novel insights to investigate the biology and therapeutic options to treat these tumors.

[Neuroendocrine dysfunction and brain damage. A consensus statement]. / Disfunción neuroendocrina y agresión cerebral. Reunión de consenso.

This consensus statement aims to enhance awareness of the incidence and risks of hypopituitarism in patients with traumatic brain injury (TBI) and/or brain hemorrhages among physicians treating patients with brain damage. The importance of this problem is related not only to the frequency of TBI but also to its prevalence in younger populations. The consequences of TBI are characterized by a series of symptoms that depend on the type of sequels related to neuroendocrine dysfunction. The signs and symptoms of hypopituitarism are often confused with those of other sequels of TBI. Consequently, patients with posttraumatic hypopituitarism may receive suboptimal rehabilitation unless the underlying hormone deficiency is identified and treated. This consensus is based on the recommendation supported by expert opinion that patients with a TBI and/or brain hemorrhage should undergo endocrine evaluation in order to assess pituitary function and, if deficiency is detected, should receive hormone replacement therapy.

[The medical management of Cushing's syndrome]. / Tratamiento farmacológico y seguimiento del síndrome de Cushing.

Cushing's syndrome results from prolonged exposure to excessive circulating glucocorticosteroids and is associated with significant morbidity and mortality. While the treatment of choice in most patients is surgical, the metabolic consequences of this syndrome, including hypertension and diabetes mellitus, increase the risks of such surgery. Hypercortisolemia and its sequelae can be efficiently reversed or controlled using medical therapy, either as a temporary measure prior to definitive treatment or as a longer-term treatment in some particularly difficult cases. Drug treatment has been targeted at the hypothalamic/pituitary level, the adrenal glands and at glucocorticoid receptors. The present review discusses the pharmacotherapeutic agents that have been used in Cushing's syndrome and the criteria for their use, as well as recent drugs that may improve the medical treatment of this complex endocrinological disorder in the future. Finally, the short-and long-term follow-up of patients with Cushing's syndrome after surgery is also discussed.

A clinical profile of memory impairment in humans due to endogenous glucocorticoid excess.

OBJECTIVE: Glucocorticoid excess is commonly related to neuropsychiatric and neurological disorders, with memory impairment typically found among these disorders. The objective of this study is to offer a clinical profile of memory deficits resulting from exposure to chronic stress-level elevations of endogenous glucocorticoids in patients with Cushing's Syndrome (CS). STUDY SUBJECTS: Thirty female participants of matching age and education level were studied: 15 had untreated CS (mean age 38 +/- 14) and 15 were healthy. In all patients, CS was confirmed by histology of the lesion after surgery. DESIGN: Different learning and memory processes were assessed using an adapted version of Luria's Memory Words-Revised task (LMW-R). Participants' performances were measured in an immediate condition and, 30 min later, in a delayed condition. Attentional and executive functions were also evaluated. RESULTS: Our data show that chronic exposure to elevated levels of cortisol is clinically associated with significant working memory deficits, which included less shot-term memory volume, slow learning rate, memory contamination and no accurate perception of own performance. Patients also show impairment in the delayed recall task. No relation was detected between learning and delayed conditions. CS group did not differ significantly from control group in basic attentional and executive functioning. CONCLUSIONS: Our clinical profile of memory deficits related to CS relates chronic exposure to hypercortisolemia to impaired attentional-dependent working memory and delayed recall process, suggesting that cortisol levels play a critical role in the modulation of learning and memory. Possible damage to hippocampus and extrahippocampal areas is discussed.

Rab18 is reduced in pituitary tumors causing acromegaly and its overexpression reverts growth hormone hypersecretion.

CONTEXT: Rab proteins regulate the sequential steps of intracellular membrane transport. Alterations of these GTPases and their associated proteins are emerging as the underlying cause for several human diseases involving dysregulated secretory activities. OBJECTIVE: Herein we investigated the role of Rab18, which negatively regulates hormone secretion by interacting with secretory granules, in relation to the altered functioning of tumoral pituitary somatotropes causing acromegaly. PATIENTS: A total of 18 patients diagnosed with pituitary tumors causing acromegaly (nine patients) or nonfunctioning adenomas (nine patients) underwent endoscopic transsphenoidal surgery. Adenomas were subsequently processed to evaluate Rab18 production in relation to GH secretion. RESULTS: We found that somatotropinoma cells are characterized by a high secretory activity concomitantly with a remarkably reduced Rab18 expression (15%) and protein content levels (30%), as compared with cells from nonfunctioning pituitary adenomas derived from patients with normal or reduced GH plasma levels (100%). Furthermore, immunoelectron microscopy revealed that Rab18 association with the surface of GH-containing secretory granules was significantly lower in somatotropes from acromegalies than nonfunctioning pituitary adenomas. Finally, we provide evidence that modulation of Rab18 gene expression can revert substantially the hypersecretory activity of cells because Rab18 overexpression reduced by 40% the capacity of cells from acromegalies to respond to GHRH stimulation. CONCLUSION: These results suggest that molecular alterations affecting individual components of the secretory granule traffic machinery can contribute to maintain a high level of GH in plasma. Accordingly, Rab18 constitutes a valuable target as a diagnostic, prognostic, and/or therapeutic tool for human acromegaly.

Intragastric balloon-induced satiety is not mediated by modification in fasting or postprandial plasma ghrelin levels in morbid obesity.

BACKGROUND: The BioEnterics Intragastric Balloon (BIB) has been proposed as an adjuvant therapy for the short-term treatment of obesity. The temporal pattern of BIB-induced satiety and whether this effect is mediated by modification of ghrelin levels is unknown. METHODS: Patients with treatment-resistant morbid obesity were invited to participate in a randomized, double-blind, sham-controlled trial of 4-month duration. Anthropometric and biochemical parameters, estimation of energy intake, and pre- and postprandial evaluation of satiety were required monthly. Ghrelin response after a standard mixed meal was scheduled prior to and 4 weeks after the endoscopic procedure. RESULTS: 21 out of 22 enrolled patients completed the study (17 women, 5 men; 35.9 +/- 9.9 years; BMI 50.4 +/- 7.8 kg/m2). Pre-intervention weight decreased from 143.8 +/- 31.2 kg to 131.1 +/- 32.6 kg in Group Balloon (P < 0.001) and from 138.8 +/- 24.5 kg to 129.9 +/- 25.6 kg in Group Sham (P < 0.01) at the end of the study. Weight loss was not significantly different in Group Balloon and Group Sham at any time-point of the follow-up. Only patients from Group Balloon showed a temporary increased pre- and postprandial satiety, which was maximal at 4 weeks after the intervention. Total area under the curve, fasting and postprandial plasma ghrelin were not significantly different between groups at inclusion or 4 weeks after follow-up. No correlation was found between any of the satiety scores at any time-point with their comparable ghrelin levels. CONCLUSION: BIB induces a temporary sense of satiety in morbidly obese patients which is not mediated by modification of fasting or postprandial levels of plasma ghrelin.

Ghrelin is produced by and directly activates corticotrope cells from adrenocorticotropin-secreting adenomas.

CONTEXT: In Cushing's disease, ACTH hypersecretion by pituitary corticotrope adenoma cells and resulting hypercortisolism is accompanied by a severely blunted GH secretory response. Interestingly, in Cushing's disease, ghrelin markedly increases plasma ACTH, whereas its stimulatory action on GH secretion is reduced. Although the reported expression of ghrelin receptors (GHS-R) in corticotrope tumors offers a potential mechanism for ghrelin-induced ACTH hypersecretion, studies on the direct effects of synthetic GH secretagogues on corticotropinoma cells offered contradictory results. OBJECTIVE AND DESIGN: To evaluate the direct action of ghrelin on corticotropinoma cells from two patients with Cushing's disease, we measured its effect on free cytosolic calcium concentration ([Ca(2+)](i)). Additionally, expression of GHS-R and its ligand ghrelin was examined in these cells and in five additional corticotropinomas. RESULTS: Ghrelin (10(-6) m) induced a marked [Ca(2+)](i) increase in 89.5% (case 1; n = 19 cells) and 85% (case 2; n = 13 cells) of corticotropinoma cells. Moreover, RT-PCR showed that expression of GHS-R isoforms is accompanied by that of ghrelin in all seven corticotrope adenomas examined. Importantly, double immunogold electron microscopy revealed that ghrelin is costored within ACTH secretory vesicles in densely granulated adenomatous corticotropes. CONCLUSIONS: These results constitute the first demonstration that ghrelin acts directly on corticotrope tumor cells derived from patients with Cushing's disease. The presence of ghrelin and GHS-R suggests that pituitary ghrelin may play an autocrine/paracrine role in regulating ACTH release in Cushing's disease. Our findings provide a plausible cellular basis for the exaggerated ACTH response to ghrelin in Cushing's disease and suggest novel research strategies to develop medical treatments for this disease.

Prevalence of hypopituitarism and growth hormone deficiency in adults long-term after severe traumatic brain injury.

OBJECTIVE: Traumatic brain injury (TBI) has been associated with hypopituitarism and GH deficiency. However, TBI-mediated hypopituitarism may be more frequent than previously thought. The present work, performed in patients with severe TBI at least 1 year before, had three aims: (i) to evaluate the prevalence of hypopituitarism, (ii) in particular to evaluate the prevalence of GH deficiency, and (iii) to compare three different tests of GH reserve in this cohort. DESIGN AND PATIENTS: From a nonselected group of 249 patients admitted to our Clinical Centre for severe TBI over the last 5 years, 200 of them answered a custom made questionnaire of symptoms of hypopituitarism enclosed in the invitation letter to participate in the study. A total of 170 (99 men and 14 women), accepted to participate in the study (study cohort); 57 had normal questionnaires and were not further studied, 14 discontinued the study, and 99 attended the hospital for dynamic tests of pituitary hormone deficiencies. From these, 44 subjects with IGF-I in the lower range were tested with GHRH+GHRP-6; ITT; and glucagon tests of GH reserve, on three different occasions. MEASUREMENTS: Pituitary hormones plus IGF-I and target gland hormones were analysed. RESULTS: With regard to the initial cohort of 170 subjects (100%), three (1.7%) showed diabetes insipidus; 10 (5.8%) TSH deficiency, 11 (6.4%) ACTH deficiency and 29 (17%) gonadotrophin deficiency. In 10 subjects (5.8%), GH deficiency was diagnosed by strict criteria. Finally, 15 (8.8%) showed combined deficit of several hormones. CONCLUSION: After severe head trauma, gonadotrophin deficiency was the most common pituitary deficit. GH deficiency showed a prevalence similar to ACTH and TSH deficits, i.e. near 6% of the cohort. Taken together, 24.7% of the subjects studied showed any type of pituitary hormone deficiency.

Marked GH secretion after ghrelin alone or combined with GH-releasing hormone (GHRH) in obese patients.

OBJECTIVES: Ghrelin is a 28-amino-acid peptide, predominantly produced by the stomach. It displays a strong GH-releasing activity mediated by the hypothalamus-pituitary GH secretagogue (GHS)-receptor (GHS-R). There are different studies that suggest the importance of ghrelin in feeding and weight homeostasis. In obesity there is a markedly decreased GH secretion. For both children and adults, the greater the body mass index (BMI), the lower the GH response to provocative stimuli, including the response to GHRH. However, the response to the natural GH secretaogogue ghrelin is unclear at the present time. The aim of the present study was to evaluate the GH response to ghrelin alone or combined with GHRH in a group of obese patients, in order to further understand the deranged GH secretory mechanisms in obesity and to clarify the mechanism of action of ghrelin. PATIENTS AND MEASUREMENTS: Six obese female patients (31 +/- 3.4 years) with a BMI of 36.1 +/- 7.7 kg/m(2) were studied. As a control group, six normal nonobese female subjects of similar age and sex were studied. Four tests were performed: placebo, GHRH [1 micro g/kg, no more than 100 micro g, intravenous (i.v.)], ghrelin (1 micro g/kg, no more than 100 micro g, i.v.) and GHRH (1 micro g/kg, no more than 100 micro g, i.v.) plus ghrelin (1 micro g/kg, no more than 100 micro g, i.v.). Blood samples were taken at appropriate intervals for determination of GH. Statistical analyses were performed by Wilcoxon and by Mann-Whitney tests. RESULTS: After GHRH, the median peak GH secretion in obese patients was 2.4 micro g/l (range 0.9-8.9 micro g/l). Ghrelin-induced GH secretion showed in obese patients a median peak of 24.4 micro g/l (range 7.4-85.0 micro g/l), significantly greater than the response after GHRH (P < 0.05). After the combined administration of GHRH plus ghrelin in obese patients the median peak GH secretion was 39.9 micro g/l (range 19.2-120.0 micro g/l), significantly greater than the response after GHRH (P < 0.05) or ghrelin (P < 0.05). GHRH-induced GH secretion in normal control subjects showed a median peak of 25.0 micro g/l (range 16.5-33.4 micro g/l). Ghrelin-induced GH secretion in normal showed a median peak of 68.5 micro g/l (range 22.5-119.5 micro g/l), significantly greater than the response after GHRH (P < 0.05). After the combined administration of GHRH plus ghrelin, in normal subjects the median peak GH secretion was 117.8 micro g/l (range 77.5-280.1 micro g/l), significantly greater than the response after GHRH or ghrelin alone (P < 0.05). When we compare the response of normal and obese patients, after GHRH alone, it was markedly decreased in obese people when compared with normal patients (P < 0.05) with a median GH peak of 25.0 micro g/l (range 16.5-33.4 micro g/l) and 2.4 micro g/l (range 0.9-8.9 micro g/l) for normal and obese patients, respectively. When we compare the response of normal and obese patients, after ghrelin alone or GHRH plus ghrelin, it was only blunted in obese subjects when compared with normal subjects with a median GH peak of 68.5 micro g/l (range 22.5-119.5 micro g/l) and 24.4 micro g/l (range 7.4-85 micro g/l) for normal and obese subjects, respectively, after ghrelin alone (P < 0.05) and a median GH peak of 117.8 micro g/l (range 77.5-280.1 micro g/l) and 39.9 micro g/l (range 19.2-120.0 micro g/l) for normal and obese patients, respectively, after GHRH plus ghrelin (P < 0.05). CONCLUSIONS: This study has demonstrated a massive GH response to ghrelin alone or combined with GHRH in obese patients, suggesting that altered ghrelin secretion could play a major role in the blunted GH secretion present in obese patients.