Alfonso Soto

Influence of Cortisol Status on Leptin Secretion

The discovery of the adipocyte-produced hormone leptin has changed the field of obesity research and our understanding of energy homeostasis. It is now accepted that leptin is the afferent loop informing the hypothalamus about the states of fat stores, with hypothalamic efferents regulating appetite and energy expenditure. I addition, leptin has a role as a metabolic adaptator in overweight and fasting states. New and previously unsuspected neuroendocrine roles have emerged for leptin. Leptin participates in the expression of CRH in the hypothalamus, interacts at the adrenal level with ACTH, and is regulated by glucocorticoids. Since leptin and cortisol show an inverse circadian rhythm, it has suggested that a regulatory feedback is present. However glucocorticoids appears to play a modulatory, but not essential roles in generating leptin diurnal rhythm. Glucocortiocids act directly on the adipose tissue and increase leptin syntesis and secretion in humans. Leptin levels are markedly increased in Cushings syndrome patients and in others pseudo-Cushings syndrome states. Glucocorticoids appears to act as a key modulator of body weight and food intake, promoting leptin secretion by adipocytes, limiting central leptin induced effects and favoring those of the NPY. Furthermore the modulatory role of glucocorticoids could be altered in obesity, but the precise mode of action remains to be established. The relevance of this finding merits further studies.

Ghrelin Is No Longer Able to Stimulate Growth Hormone Secretion in Patients with Cushing’s Syndrome but Instead Induces Exaggerated Corticotropin and Cortisol Responses

Growth and growth hormone (GH) secretion are blunted or severely impeded in chronic hypercortisolism and in patients with Cushing’s syndrome. A mechanistic explanation for the effect however has yet to be provided. On the other hand, several properties of ghrelin, a new peptide recently identified as the endogenous ligand of the GH secretagogue receptor, are still largely unknown. The two aims of this study were to observe whether ghrelin-mediated GH secretion was altered, and to characterize the corticotropin (ACTH) and cortisol response to this new stimulus in patients with Cushing’s disease. Ten patients with active Cushing’s disease (6 harboring microadenomas and 4 with macroadenomas) and 10 sex- and age-matched controls were studied. Ghrelin was administered at a dose of 1 µg/kg i.v. and GH, ACTH and cortisol analyzed in duplicate. In control women, ghrelin induced GH secretion to levels of 74.4 ± 12.8 µg/l, while chronic hypercortisolism severely reduced the ghrelin-mediated GH release in all patients with Cushing’s disease (peak values 17.7 ± 5.2 µg/l). The slightly, but significantly higher adiposity of patients vs. controls may have contributed to the effect, since a significant negative correlation (r = 0.639) was found between the amplitude of the GH peak and body mass index. In control women, ghrelin increased ACTH and cortisol levels, with peaks at 57.4 ± 19.0 ng/l and 162 ± 16 µg/l, respectively. This secretion was enhanced in Cushing’s syndrome patients, with ACTH and cortisol values of 380.7 ± 109.8 ng/l and 338 ± 81 µg/l respectively, both significantly higher than in controls. In conclusion, ghrelin-induced GH secretion was severely blunted in patients with active Cushing’s syndrome, in addition to a remarkable hyper-response in ACTH and cortisol secretion. These findings could have implications for the understanding of the physiology and physiopathology of interactions between GH and ACTH regulation.

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.

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.

Cost of Clinical Management of Acromegaly in Spain

AbstractIntroduction and Background: The cost of the therapeutic management of acromegaly depends on the selection of resources used, surgery and/or pharmacological treatment, by the specialist responsible for treatment, related to the characteristics of the patient and tumour. The objective of this work is to evaluate these costs for an illness that is rare but that is associated with a high morbidity in the context of routine clinical practice. Methods: This was an epidemiological, prospective, naturalistic, multicentre study in Spain, in which 38 endocrinologists participated. Adult patients with acromegaly and a pituitary microadenoma or macroadenoma were included in the study. Patients were assigned, according to first-line treatment, to the following two groups: surgery first-line group (surgery in the 6 months before inclusion or during the follow-up period) and pharmaceutical first-line group (treatment with somatostatin analogues [SAs] for at least 6 months and with or without surgery after starting treatment with SAs). Data were collected during routine visits made during a follow-up period of 2 years. All resources were estimated at 2009 prices (€) and adjusted according to the Spanish consumer price index in 2010. Results: Seventy-four patients were included, the majority of them with macroadenoma (70%). Eighty-eight percent of patients were treated surgically (76% as a first-line treatment), while 12% of patients received only SAs. Treatment with SAs was used at some point in the study by 85% of patients. The mean annual total cost of acromegaly is h9668 per patient (€9223 for the surgery group and €11 054 for the pharmaceutical group). Seventy-one percent of the direct cost of the disease corresponds to treatment with SAs. The cost of a patient treated only with surgery is €2501 on an annual basis, versus €9745 for a patient receiving only pharmacological treatment. In cases where a combination of both types of treatment is required, the annual total cost ranges from €10 866 to €12364. Conclusion: The annual direct cost per patients of acromegaly in Spain is €9668. Even though surgery is the preferred option for treatment for a great number of patients, SAs must be added to the treatment regimen of the majority of such patients. The costs associated with this treatment are greater than the cost of treatment with SAs alone.

Effect of withdrawal of somatostatin plus growth hormone (GH)-releasing hormone as a stimulus of GH secretion in Cushing's syndrome

Objective Somatostatin (SS) may not merely be inhibitory to GH secretion but, under appropriate temporal conditions, may act in a paradoxically positive manner to sensitize somatotroph responsiveness to GHRH. SS infusion withdrawal (SSIW) produces a rebound GH rise in humans and increases GHRH‐induced GH release. Theoretically SSIW leaves the somatotroph cell in a situation of low endogenous SS. In Cushings syndrome, GH secretion appears blunted to all stimuli. The mechanisms by which glucocorticoids impair GH secretion in Cushings syndrome are unknown. There are no data evaluating GH responsiveness to SSIW plus GHRH in Cushings syndrome patients. The aim of the present study was to evaluate the GH response to SSIW plus GHRH in a group of Cushings syndrome patients, in order to further understand the deranged GH secretory mechanisms in Cushings syndrome.

Escape and lipodystrophy in acromegaly during pegvisomant therapy, a retrospective multicentre Spanish study

Pegvisomant is an effective treatment for acromegaly.

Somatotropinomas, But Not Nonfunctioning Pituitary Adenomas, Maintain a Functional Apoptotic RET/Pit1/ARF/p53 Pathway That Is Blocked by Excess GDNF

Acromegaly is caused by somatotroph cell adenomas (somatotropinomas [ACROs]), which secrete GH. Human and rodent somatotroph cells express the RET receptor. In rodents, when normal somatotrophs are deprived of the RET ligand, GDNF (Glial Cell Derived Neurotrophic Factor), RET is processed intracellularly to induce overexpression of Pit1 [Transcription factor (gene : POUF1) essential for transcription of Pituitary hormones GH, PRL and TSHb], which in turn leads to p19Arf/p53-dependent apoptosis. Our purpose was to ascertain whether human ACROs maintain the RET/Pit1/p14ARF/p53/apoptosis pathway, relative to nonfunctioning pituitary adenomas (NFPAs). Apoptosis in the absence and presence of GDNF was studied in primary cultures of 8 ACROs and 3 NFPAs. Parallel protein extracts were analyzed for expression of RET, Pit1, p19Arf, p53, and phospho-Akt. When GDNF deprived, ACRO cells, but not NFPAs, presented marked level of apoptosis that was prevented in the presence of GDNF. Apoptosis was accompanied by RET processing, Pit1 accumulation, and p14ARF and p53 induction. GDNF prevented all these effects via activation of phospho-AKT. Overexpression of human Pit1 (hPit1) directly induced p19Arf/p53 and apoptosis in a pituitary cell line. Using in silico studies, 2 CCAAT/enhancer binding protein alpha (cEBPα) consensus-binding sites were found to be 100% conserved in mouse, rat, and hPit1 promoters. Deletion of 1 cEBPα site prevented the RET-induced increase in hPit1 promoter expression. TaqMan qRT-PCR (real time RT-PCR) for RET, Pit1, Arf, TP53, GDNF, steroidogenic factor 1, and GH was performed in RNA from whole ACRO and NFPA tumors. ACRO but not NFPA adenomas express RET and Pit1. GDNF expression in the tumors was positively correlated with RET and negatively correlated with p53. In conclusion, ACROs maintain an active RET/Pit1/p14Arf/p53/apoptosis pathway that is inhibited by GDNF. Disruption of GDNFs survival function might constitute a new therapeutic route in acromegaly.

Use of lanreotide in combination with cabergoline or pegvisomant in patients with acromegaly in the clinical practice: The ACROCOMB study.

PURPOSE To describe real-world use of lanreotide combination therapy for acromegaly. PATIENTS AND METHODS ACROCOMB is a retrospective observational Spanish study of patients with active acromegaly treated with lanreotide combination therapy between 2006 and 2011. 108 patients treated at 44 Spanish Endocrinology Departments were analyzed separately: 61 patients received lanreotide/cabergoline (cabergoline cohort) and 47 lanreotide/pegvisomant (pegvisomant cohort). RESULTS Patient median age was 50.8 years in the cabergoline cohort and 42.7 years in the pegvisomant cohort. Prior medical treatments were somatostatin analogue (SSA) monotherapy (40 [66%] patients) or dopamine agonists (7 [11%] patients) in the cabergoline cohort and SSA (29 [62%] patients) or pegvisomant monotherapy (16 [34%] patients) in the pegvisomant cohort. Across both cohorts 12 patients were previously untreated, and prior therapy was unknown/missing in 4 patients. Median duration of combined treatment was 1.6 years (0.1-6) and 2.1 years (0.4-6.3) in the cabergoline and pegvisomant cohorts, respectively. At baseline, median insulin growth factor (IGF)-I values were 149% upper limit of normal (ULN) (15-505%) in the cabergoline cohort and 156% ULN (15-534%) in the pegvisomant cohort, and decreased to 104% ULN (13-557%) p<0.001 and 86% ULN (23-345%) p<0.0001, respectively, at end of study (EOS). Normal age-adjusted values of IGF-I were obtained in 48% of lanreotide/cabergoline-treated patients and 70% of lanreotide/pegvisomant-treated patients at EOS. There were no significant changes in hepatic, cardiac or glycaemic parameters in either cohort. CONCLUSION In clinical practice lanreotide treatment combinations are useful options for patients with acromegaly when monotherapy is insufficient; particularly, the combination of lanreotide and pegvisomant in patients not controlled with either SSA or pegvisomant alone has high efficacy and is well-tolerated.

Índices antropométricos estimadores de la distribución adiposa abdominal y capacidad discriminante para el síndrome metabólico en población española

INTRODUCTION The metabolic syndrome (MS) carries an increased risk of cardiovascular disease and diabetes mellitus. Insulin resistance is probably the mechanism underlying the changes detected in lipid and carbohydrate metabolism in these patients, who have, as a common anthropometric feature, a predominantly increased abdominal fat distribution. PATIENTS AND METHODS A total of 3316 patients were studied, of whom 63.40% were female and 36.60 male, with a mean age of 42.36±14.63 years, and a body mass index (BMI) of 32.76±6.81kg/m(2). Weight, height and waist circumference (CC) were measured using standard techniques. The waist/height (ICA) was calculated using two indicators, expressed as waist in cm divided by height in m(2), and as waist divided by height, both in cm. The prevalence of metabolic syndrome in the sample was 33.70%. In order to assess the predictive ability of BMI, ICA and CC to detect the existence of MS, receiver operating curves (ROC) were constructed and the areas under the curve (AUC) calculated for each anthropometric parameter. RESULTS An AUC of 0.724 (95%CI: 0.706 to 0.742), P<.001, was obtained for CC, 0.709 (95%CI: 0.691 to 0.728), P<.001 for ICA with height in m(2), and 0.729 (95%CI: 0.711 to 0.747), P<.001 for ICA with height in cm, and for the BMI it was 0.680 (95%CI 0.661-0.699), P<.001. CONCLUSIONS Anthropometric indices that assess abdominal fat distribution have a better predictive capacity for detecting MS, compared to total adiposity indicators such as BMI.