The impact of menopause on antidepressant response: an explorative analysis from a real-world study

This study endeavors to deepen our understanding of the subject matter by exploring, within a real-world sample, the impact of menopausal status on the antidepressant treatments response. The whole sample included a total of 447 patients, 156 male and 291 female, 110 pre-menopause and 181 post-menopause. In our sample post-menopause women showed a worse response to antidepressants than pre-menopause women (p = 0.006), and this difference seems to be unrelated to age or brain aging.

How different definition criteria may predict clinical outcome in treatment resistant depression: Results from a prospective real-world study

Management of treatment-resistant depression (TRD) remains a major public health challenge, also due to the lack of a consensus around TRD definition. We investigated the impact of different definitions of TRD on identifying patients with distinct features in terms of baseline characteristics, treatment strategies, and clinical outcome. We conducted a prospective naturalistic study on 538 depressed inpatients. Patients were screened for treatment resistance by two TRD definitions: looser criteria (lTRD) and stricter criteria (sTRD). We compared baseline characteristics, treatment and clinical outcome between the TRD groups and their non-TRD counterparts. 52.97 % of patients were identified as lTRD, only 28.81 % met the criteria for sTRD. sTRD patients showed lower rates of remission and slower symptom reduction compared to non-TRD patients and received more challenging treatments. Surprisingly, patients identified as sTRD also exhibited lower rates of psychiatric comorbidities, including personality disorders, substance abuse, or alcohol misuse. Stricter TRD criteria identify patients with worse clinical outcomes. Looser criteria may lead to overdiagnosis and over treatment. Clinical features known to be possible risk factors for TRD, as psychiatric comorbidities, showed to be more suggestive of a "difficult to manage" depression rather than a proper TRD.

Association between NTRK2 Polymorphisms, Hippocampal Volumes and Treatment Resistance in Major Depressive Disorder

Despite the increasing availability of antidepressant drugs, a high rate of patients with major depression (MDD) does not respond to pharmacological treatments. Brain-derived neurotrophic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling is thought to influence antidepressant efficacy and hippocampal volumes, robust predictors of treatment resistance. We therefore hypothesized the possible role of BDNF and neurotrophic receptor tyrosine kinase 2 (NTRK2)-related polymorphisms in affecting both hippocampal volumes and treatment resistance in MDD. A total of 121 MDD inpatients underwent 3T structural MRI scanning and blood sampling to obtain genotype information. General linear models and binary logistic regressions were employed to test the effect of genetic variations related to BDNF and NTRK2 on bilateral hippocampal volumes and treatment resistance, respectively. Finally, the possible mediating role of hippocampal volumes on the relationship between genetic markers and treatment response was investigated. A significant association between one NTRK2 polymorphism with hippocampal volumes and antidepressant response was found, with significant indirect effects. Our results highlight a possible mechanistic explanation of antidepressant action, possibly contributing to the understanding of MDD pathophysiology.

GHRH + arginine test and body mass index: do we need to review diagnostic criteria for GH deficiency?

INTRODUCTION

The proportion of patients with low GH response to provocative tests increases with the number of other pituitary hormone deficiencies, reason why in panhypopituitary patients GH stimulation tests may be unnecessary to diagnose GH deficiency (GHD) PURPOSE: To re-evaluate the diagnostic cut-offs of GH response to GHRH + arginine (ARG) test related to BMI, considering the patients' pituitary function as the gold standard for the diagnosis of GHD.

METHODS

The GH responses to GHRH + ARG were studied in 358 patients with history of hypothalamic-pituitary disease. GHD was defined by the presence of at least 3 other pituitary deficits (n = 223), while a preserved somatotropic function was defined by the lack of other pituitary deficits and an IGF-I SDS ≥ 0 (n = 135). The cut-off with the best sensitivity (SE) and specificity (SP), was identified for each BMI category using the ROC curve analysis. To avoid over-diagnosis of GHD we subsequently searched for the cut-offs with a SP ≥ 95%.

RESULTS

The best GH cut-off was 8.0 μg/l (SE 95%, SP 100%) in lean, 7.0 μg/l (SE 97.3%, SP 82.8%) in overweight, and 2.8 μg/l (SE 84.3%, SP 91.7%) in obese subjects. The cut-off with a SP ≥ 95% was 2.6 μg/l (SE 68.5%, SP 96.6%) in overweight and 1.75 μg/l (SE 70.0%, SP 97.2%) in obese subjects.

CONCLUSIONS

This is the first study that evaluates the diagnostic cut-offs of GH response to GHRH + ARG related to BMI using a clinical definition of GHD as gold standard. Our results suggest that with this new approach, the GHRH + ARG cut-offs should be revised to avoid GHD over-diagnosis.

Add-On Treatment with Passiflora incarnata L., herba, during Benzodiazepine Tapering in Patients with Depression and Anxiety: A Real-World Study

Chronic and inappropriate benzodiazepine intake represents an important health and social concern worldwide. The aim of our study was to investigate the effectiveness of P. incarnata L., herba, in reducing benzodiazepine misuse in a real-world population of depressed and anxious patients in a long-term treatment with benzodiazepines. We conducted a retrospective naturalistic study on 186 patients undergoing benzodiazepine downtitration, 93 with the addition of a dry extract of P. incarnata L., herba (Group A), and 93 without any add-on treatment (Group B). Regarding the benzodiazepine dosage variation in the two groups, a repeated measure ANOVA showed a significant effect of time (p < 0.001), group (p = 0.018), and time x group interaction (p = 0.011). We found a significantly higher rate, i.e., of 50%, reduction in Group A vs. Group B at 1 month (p < 0.001) and at 3 months (p < 0.001) and complete benzodiazepine discontinuation at 1 month (p = 0.002) and at 3 months (p = 0.016). Our findings suggest the role of P. incarnata as an effective add-on treatment during benzodiazepine tapering. These findings highlight the need for further studies to better investigate the promising properties of P. incarnata in the management of such a relevant clinical and social issue.

Benefits of dual-release hydrocortisone treatment on central adiposity and health-related quality of life in secondary adrenal insufficiency

PURPOSE

Patients with secondary adrenal insufficiency (SAI) have an increased morbidity and an impaired health-related quality of life (HRQoL), which seems to primarily depend on the sub-optimal replacement of hypoadrenalism with standard glucocorticoid (GC) therapy, and on the inadequate correction of other associated pituitary deficiencies. A dual-release hydrocortisone (DR-HC) formulation has shown to exert positive effects on morbidity and HRQoL, mainly in patients with primary adrenal insufficiency. We assessed the variations of anthropometric and metabolic parameters and HRQoL in patients with SAI after switching from cortisone acetate (CA) or hydrocortisone (HC) to DR-HC.

METHODS

Twenty-one patients (17 M, 4 F) treated with CA (n = 16; 25 mg/day twice a day) or HC (n = 5; 20 mg/day three times a day), were evaluated for waist circumference, BMI, fasting glucose, HbA1c, insulin, HOMA-IR index, serum lipids, electrolytes, blood pressure and HRQoL at baseline, at 3, 6 and 12 months after switching from CA/HC to DR-HC.

RESULTS

The study showed a significant reduction of waist circumference and BMI (p = 0.04, for both), after 3 and 6months of DR-HC treatment, respectively. No significant changes were observed for fasting glucose, insulin, HOMA-IR index, HbA1c, total cholesterol, triglycerides, LDL cholesterol, electrolytes, and blood pressure. However, HDL cholesterol significantly decreased (p = 0.003). An improvement of AddiQoL total score was observed during DR-HC treatment (p = 0.01), mainly for the category "emotions". No predictors resulted for these changes.

CONCLUSION

DR-HC treatment provides some benefits in patients with SAI, reducing central adiposity and improving HRQoL; however, worsening of HDL cholesterol is observed during treatment with DR-HC.

Development and internal validation of a predictive score for the diagnosis of central adrenal insufficiency when morning cortisol is in the grey zone

BACKGROUND

When evaluating a patient for central adrenal insufficiency (CAI), there is a wide range of morning cortisol values for which no definite conclusion on hypothalamus-pituitary-adrenal (HPA) axis function can be drawn; in these cases, a stimulation test is required. Aim of this study was to develop an integrated model for CAI prediction when morning cortisol is in the grey zone, here defined as 40.0-160.0 μg/L.

METHODS

Overall, 119 patients with history of sellar tumour which underwent insulin tolerance test (ITT) for the evaluation of HPA axis were enrolled. Supervised regression techniques were used for model development.

RESULTS

An integrated predictive model was developed and internally validated, and showed a significantly better diagnostic performance than morning cortisol alone (AUC 0.811 vs 0.699, p = 0.003). A novel predictive score (CAI-score) was retrieved, on a 5.5-point scale, by considering morning cortisol (0 points if 130.1-160.0 μg/L, 1 point if 100.1-130.0 μg/L, 1.5 points if 70.1-100.0 μg/L, 2.5 points if 40.0-70.0 μg/L), other pituitary deficits (2 points if ≥ 3 deficits), and sex (1 point if male). A diagnostic algorithm integrating CAI-score and ITT was finally proposed, with an overall accuracy of 99%, and the possibility to avoid the execution of stimulation tests in 25% of patients.

CONCLUSIONS

This was the first study that proposed an integrated score for the prediction of CAI when morning cortisol is in the grey zone. This score might be helpful to reduce the number of patients who need a stimulation test for the assessment of HPA axis function.

Untreated adult GH deficiency is not associated with the development of metabolic risk factors: a long-term observational study

PURPOSE

Uncertainties exist about the predictors of the severity of the clinical picture of GH deficiency (GHD) syndrome. Aim of the study was to evaluate, in adult patients with GHD, the predictors of the development of hypercholesterolemia, hypertension, diabetes mellitus, and osteoporosis.

METHODS

We retrospectively studied 327 adult patients (age 47.1 ± 17.1 years) with untreated severe GHD (mean follow-up 110.9 ± 56.8 months). GHD was defined by GHRH + arginine test using BMI cut-offs. The possible development of hypercholesterolemia, hypertension, diabetes mellitus, and osteoporosis was investigated by Kaplan-Meier survival analysis. For each clinical outcome, either a univariate or multivariate analysis according to the Cox proportional-hazards model was performed to identify those factors that were associated with the development of the event.

RESULTS

GH secretion parameters were not associated with the outcomes. Hypercholesterolemia was positively and negatively predicted by a BMI ≥ 30 kg/m² (HR 2.50, p 0.00) and the dose of l-thyroxine possibly in place (HR 0.98, p 0.02), respectively. Hypertension was positively predicted by a BMI ≥ 30 kg/m² (HR 2.64, p 0.00) and IGF-I SDS values (HR 2.26, p 0.00). Diabetes mellitus was positively predicted by hypertension (HR 11.76, p 0.01). Osteoporosis was positively and negatively predicted by hypercholesterolemia (HR 3.25, p 0.01) and hypertension (HR 0.21, p 0.00), respectively.

CONCLUSIONS

The severity of the impairment of GH secretion does not predict the development of the clinical picture of GHD syndrome: untreated adult GHD does not increase the development of metabolic risk factors in hypopituitaric patients.

Retrospective observational analysis of non-irradiated non-functioning pituitary adenomas

PURPOSE

The management of choice of non-functioning pituitary adenomas (NFPAs) remains debulking surgery when symptomatic. However, patient series systematically reporting the NFPAs outcome that were not treated either surgically, medically or with radiotherapy during long follow-up thereby giving an indication of their natural history are limited. Aim of the present study was to evaluate the natural course of presumed NFPAs, the outcome of confirmed NFPAs during a long follow-up period.

METHODS

Between 1993 and 2013, 84 patients with presumed NFPA were studied retrospectively. Patients were enrolled based on the following criteria: imaging suggestive of pituitary adenoma, absence of any biochemical/clinical evidence of hormonal excess, exclusion of prolactinomas and at least one sequential imaging during the follow-up. Repeated assessment of the pituitary function, visual fields and imaging was performed at regular intervals. The follow-up duration was evaluated from the first and last imaging dates.

RESULTS

In group F (follow-up without surgery, 33 patients), the macroadenomas showed a 15% probability of tumor growth and reduction. Similar tumor size alterations were observed also for the microadenomas. In group S (surgery, 51 patients), both residual tumors (>1 and <1 cm) following initial surgical resection remain mainly stable until the last imaging.

CONCLUSIONS

Based on the given lack of approved medical treatment and the possible risks of surgical intervention in presence of significant comorbidities, our study proposes a conservative approach with a careful follow-up in patients with NFPAs without visual or neurological abnormalities.

Cardiovascular risk and metabolic syndrome in primary hyperparathyroidism and their correlation to different clinical forms

Cardiometabolic disorders have been associated with primary hyperparathyroidism (PHPT), while the relationship of cardiovascular risk score (CRS) and metabolic syndrome (MS) with different clinical presentation of PHPT remains undefined. Our aim was to evaluate CRS, MS and its components in PHPT looking for their correlation to different clinical forms. In 68 consecutive PHPT patients and 68 matched controls, CRS, MS and its components were assessed to perform an observational case-control study at an ambulatory referral center for Bone Metabolism Diseases. Patients were stratified in symptomatic and asymptomatic PHPT; these latter were divided in high-risk and low-risk subgroups for end-organ damage. An increased proportion of PHPT patients had intermediate-high CRS and MS (mean, 95 % Confidence Interval (CI) 51.5 %, 39.6-63.3 and 20.6 %, 11.0-30.2, respectively, p < 0.02 vs. controls). Intermediate-high CRS was prevalent both in symptomatic and low-risk asymptomatic PHPT while MS resulted prevalent in low-risk asymptomatic but not in symptomatic PHPT. Type 2 DM, IFG, mixed dyslipidemia, hypertriglyceridemia, HDL-hypocholesterolemia, and LDL-hypercholesterolemia predominated in low-risk asymptomatic, while only LDL-hypercholesterolemia prevailed also in symptomatic PHPT. In patients and controls without cardiometabolic risk factors, HOMA-IR index was significantly increased in PHPT vs. controls (p < 0.03) and associated to total calcium (R = 0.73; p < 0.001). By multivariate analysis low-risk asymptomatic PHPT predicted MS after adjusting for age, sex, and BMI. Our data show an increased frequency of intermediate-high CRS both in symptomatic and low-risk asymptomatic PHPT while MS prevails in low-risk asymptomatic PHPT, supporting the potential for cardiovascular morbidity and mortality also in this form.

Prevalence and characteristics of metabolic syndrome in primary hyperparathyroidism

AIMS

Primary hyperparathyroidism (pHPT) is characterized by an increased frequency of glucose tolerance abnormalities associated with insulin resistance. Few studies evaluated the prevalence of metabolic syndrome (MetS) in pHPT and whether there are differences between asymptomatic pHPT patients and symptomatic ones. Thus, we sought to investigate the prevalence of MetS in pHPT patients in comparison to the prevalence of MetS in Italian population.

SUBJECTS AND METHODS

We conducted a retrospective chart review of 294 pHPT patients, of these 154 [age (mean ± SD) 58.7 ± 13.3 yr, body mass index 25.6 ± 4.8 kg/m(2); serum calcium (11.3 ± 1.2 mg/dl) 2.8 ± 0.3 mmol/l; PTH 234.8 ± 224.3 ng/l] met the inclusion criteria. A modified National Cholesterol Educational Program (NCEP)/Adult Treatment Panel III (ATP III) definition of the MetS was used. Prevalence of MetS was compared with that reported for the Italian population (Progetto Cuore Study).

RESULTS

The prevalence of the MetS (34/154, 22.1%) was similar to that reported in the general Italian population. Asymptomatic pHPT patients were older (62.1 ± 12.7 vs 56.4 ± 13.2 yr, p<0.008) and showed higher prevalence of MetS than symptomatic ones (30.2% vs 16.5%, p<0.045). Moreover the prevalence of nephrolitiasis or overt bone disease was not different between patients MetS+pHPT compared to MetS-pHPT, whereas femoral bone mineral density (BMD) was higher in MetS+pHPT (p<0.003). In the logistic regression model age and femoral BMD were independent predictors of MetS.

CONCLUSIONS

The prevalence of MetS in pHPT is not increased in comparison to the general population, thus, its diagnosis is not an appropriate tool to identify the additional cardiovascular risk related to pHPT. Difference in age affects the increased prevalence of MetS in asymptomatic pHPT patients.

Effects of chronic slow release-lanreotide treatment on insulin-like growth factor system and metabolic parameters in acromegalic patients

Insulin and IGF binding protein (IGFBP)-1 are linked by negative association. Somatostatin (SS) reduces insulin secretion by acting on pancreatic β-cell and also by decreasing GH secretion. SS analogues in acromegaly reduce total IGF-I levels inhibiting GH hypersecretion, but they also reduce free IGF-I bioactivity increasing IGFBP-1 levels by inducing insulin decrease. In 13 acromegalic patients we studied GH, IGF system, insulin, and glucagon levels at baseline and at 7 days, 1 and 6 months under treatment with slow release (SR)-lanreotide (LAN) (60 mg im monthly). The hormonal and metabolic response to arginine (ARG) (0.5 g/kg iv in 30 min) was also studied at each time point. LAN decreased GH, total IGF-I, and IGFBP-3 levels at each time point. Insulin and glucagon levels were reduced, while IGFBP-1 and free IGF-I levels were increased by LAN at day 7 and after 1 month only. LAN did not modify the GH, insulin, glucagon, glucose, and IGFBP-1 responses to ARG. At each time point ARG-induced insulin increase was coupled to increase in glucagon and IGFBP-1 levels. This study shows that acromegalic patients under chronic treatment with LAN display: a) inhibition of GH and total IGF-I levels, not coupled to persistent decrease in free IGF-I levels; b) persistent decrease in IGFBP- 3 but transient decrease and increase in insulin and IGFBP- 1, respectively; c) unchanged hormonal and metabolic response to ARG. Our findings also show that ARG stimulates IGFBP-1 despite marked increase in insulin secretion; this escape from the negative relationship linking insulin and IGFBP- 1 would likely reflect the ARG-induced glucagon increase.

Long-term morphological, hormonal, and clinical follow-up in a single unit on 118 patients with adrenal incidentalomas

OBJECTIVE

To evaluate long-term morphological, functional, and clinical outcome in adrenal incidentalomas.

DESIGN AND METHODS

A total of 118 patients (77 F and 47 M; age 62.3+/-1.0 years) with adrenal incidentalomas were evaluated at baseline and followed-up for median 3 years (range 1-10 years) by clinical, biochemical, hormonal, and morphological evaluation. Among them, six patients with diagnosis of subclinical Cushing's syndrome (SCS) underwent surgery.

RESULTS

At entry, 86% (n=102) of tumors were nonfunctioning (NF) and 14% (n=16) showed SCS. Comparing NF with SCS patients, a significantly higher percentage of dyslipidemia was found in the group of SCS patients (50 vs 23%, P=0.033). During follow-up, adrenal function remained normal in all NF patients, none of them developed subclinical or overt endocrine disease. The cumulative risk of mass enlargement was globally low (25%), but progressive up to 8 years. SCS was confirmed in all patients, and none of them shifted to overt Cushing's syndrome. The cumulative risk of developing metabolic-cardiovascular abnormalities was globally low (22%), but progressive up to 8 years and new diseases were recorded in the group of NF patients only (three patients with dyslipidemia, four with impaired fasting glucose/impaired glucose tolerance, and three with diabetes mellitus). SCS patients who underwent surgery did not show any significant clinical improvement.

CONCLUSIONS

The risk of mass enlargement, hormonal, and metabolic impairment over time is globally low. Conservative management seems to be appropriate, but further prospective studies are needed to establish the long-term outcome of such patients, especially for metabolic status, cardiovascular risk profile and their relationship with endocrine function.

Growth hormone/insulin-like growth factor-I axis in obstructive sleep apnea syndrome: an update

Obstructive sleep apnea syndrome (OSAS) is a serious, prevalent condition that has significant mortality and morbidity when untreated. It is strongly associated with obesity and is characterized by changes in the serum levels or secretory patterns of several hormones. In particular, obese patients with OSAS show a peculiar reduction of both spontaneous and stimulated GH secretion coupled with reduced IGF-I concentrations and impaired peripheral sensitivity to GH. These endocrine abnormalities are more marked than those observed in non-apneic obese subjects, and are likely to be due to the effects of hypoxia and sleep fragmentation on hormone secretory pattern. The GH/IGF-I axis activity disruption can be responsible, at least in part, for metabolic alterations, which are common in OSAS and increase the risk of cardiovascular events as well as mortality. Effective assessment and management of OSAS may correct endocrine changes, improve quality of life, and prevent associated morbidity or death.

Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model

Lithium iron phosphate is one of the most promising positive-electrode materials for the next generation of lithium-ion batteries that will be used in electric and plug-in hybrid vehicles. Lithium deintercalation (intercalation) proceeds through a two-phase reaction between compositions very close to LiFePO(4) and FePO(4). As both endmember phases are very poor ionic and electronic conductors, it is difficult to understand the intercalation mechanism at the microscopic scale. Here, we report a characterization of electrochemically deintercalated nanomaterials by X-ray diffraction and electron microscopy that shows the coexistence of fully intercalated and fully deintercalated individual particles. This result indicates that the growth reaction is considerably faster than its nucleation. The reaction mechanism is described by a 'domino-cascade model' and is explained by the existence of structural constraints occurring just at the reaction interface: the minimization of the elastic energy enhances the deintercalation (intercalation) process that occurs as a wave moving through the entire crystal. This model opens new perspectives in the search for new electrode materials even with poor ionic and electronic conductivities.

Primary hyperaldosteronism is associated with derangement in the regulation of the hypothalamus-pituitary-adrenal axis in humans

Hippocampal mineralocorticoid receptors (MR) play a major role in the control of hypothalamus- pituitary-adrenal (HPA) axis. The functional profile of HPA axis and the impact of MR blockade under chronic exposure to mineralocorticoid excess are unknown. To clarify this issue, ACT H, cortisol, and aldosterone secretions were studied in 6 patients with primary hyperaldosteronism (HA) and 8 controls (NS) during placebo, placebo+human CR H (hCR H) (2 microg/kg iv bolus at 22:00 h), potassium canrenoate (CAN, 200 mg iv bolus at 20:00 h followed by 200 mg infused over 4 h) or CAN+hCR H. During placebo, both aldosterone and ACT H levels were higher (p<0.01) in HA than in NS, while cortisol levels were not significantly different. Both HA and NS showed significant ACT H and cortisol responses to hCR H (p<0.004), although the hormonal responses in HA were higher (p<0.02) than in NS. CAN infusion did not modify aldosterone levels in both HA and NS. Under CAN infusion, ACT H showed progressive rise in NS (p<0.05) but not in HA, while cortisol levels showed a significant (p<0.05) but less marked and delayed increase in HA compared to NS. CAN enhanced hCRH-induced ACTH and cortisol responses in NS (p<0.05), but not in HA. In conclusion, in humans primary hyperaldosteronism is associated with deranged function of the HPA axis. In fact, hyperaldosteronemic patients show basal and hCR H-stimulated HPA hyperactivity that is, at least partially, refractory to further stimulation by mineralocorticoid blockade with canrenoate. Whether this hormonal alteration can influence the clinical feature of hypertensive patients with primary hyperaldosteronism needs to be clarified.

Ghrelin and other gastrointestinal peptides involved in the control of food intake

The increasing prevalence of obesity has triggered intense research on its pharmacotherapy. Besides central neuroendocrine pathways, many peripheral endocrino-metabolic signals have been investigated, but only few are probably of some utility in weight loss. This review reports about ghrelin and other gastrointestinal peptides involved in hunger and satiety.

Histological and functional characteristics of peritoneal membrane in peritoneal sclerosis of PD patients

BACKGROUND

Function and structure of peritoneal membrane (PM) are impaired on peritoneal dialysis (PD). Peritoneal sclerosis is a common finding in peritoneal biopsies (PB) of PD patients. The aim of this study was to examine the impact of peritoneal sclerosis on peritoneal function and clinical parameters in PD patients submitted to peritoneal biopsy.

METHODS

A PB was performed on 31 PD patients during catheter removal due to malfunction or after drop-out from treatment. For each patient PM transport was evaluated by the last peritoneal equilibration test before PB. Each daily glucose load was calculated. Tissue was formalin-embedded and stained for histological and immunohistochemical studies.

RESULTS

Patients with submesothelial sclerosis and those with impairment of submesothelial basement membrane and subendothelial vascular membrane were submitted to a larger daily glucose load. Peritoneal sclerosis > 50 microns was more frequent in high transporters, who were exposed to larger daily glucose load compared to medium-high transporters. Mesothelial loss is correlated to peritoneal sclerosis and vascular injuries.

CONCLUSIONS

Peritoneal sclerosis is not constant in PD patients: it is related to the loss of mesothelium integrity, to the daily glucose load of PD treatment and to vascular injuries, but apparently not to the presence of inflammatory infiltrate. It remains a matter of debate how much the peritoneal sclerosis modifies the function of PM and how new more biocompatible PD solutions could reduce PM injury.

Ghrelin: more than a natural GH secretagogue and/or an orexigenic factor

Ghrelin, an acylated peptide produced predominantly by the stomach, has been discovered to be a natural ligand of the growth hormone secretagogue receptor type 1a (GHS-R1a). Ghrelin has recently attracted considerable interest as a new orexigenic factor. However, ghrelin exerts several other neuroendocrine, metabolic and also nonendocrine actions that are explained by the widespread distribution of ghrelin and GHS-R expression. The likely existence of GHS-R subtypes and evidence that the neuroendocrine actions, but not all the other actions, of ghrelin depend on its acylation in serine-3 revealed a system whose complexity had not been completely explored by studying synthetic GHS. Ghrelin secretion is mainly regulated by metabolic signals and, in turn, the modulatory action of ghrelin on the control of food intake and energy metabolism seems to be among its most important biological actions. However, according to a recent study, ghrelin-null mice are neither anorectics nor dwarfs and this evidence clearly depicts a remarkable difference from leptin null mice. Nevertheless, the original and fascinating story of ghrelin, as well as its potential pathophysiological implications in endocrinology and internal medicine, is not definitively cancelled by these data as GHS-R1a null aged mice show significant alterations in body composition and growth, in glucose metabolism, cardiac function and contextual memory. Besides potential clinical implications for natural or synthetic ghrelin analogues acting as agonists or antagonists, there are several open questions awaiting an answer. How many ghrelin receptor subtypes exist? Is ghrelin 'the' or just 'a' GHS-R ligand? That is, are there other natural GHS-R ligands? Is there a functional balance between acylated and unacylated ghrelin forms, potentially with different actions? Within the next few years suitable answers to these questions will probably be found, making it possible to gain a better knowledge of ghrelin's potential clinical perspectives.

[On-line hemodiafiltration with endogenous reinfusion (HFR). Experience of a Centre]

PURPOSE

Hemodiafiltration reinfusion (HFR) treatment is a dialysis technique that uses the endogenous reinfusion fluid and performs, simultaneously and separately, the three mechanisms of extracorporal depuration: diffusion, convection and adsorption. This study aimed to evaluate clinical and biochemical data of a group of six patients submitted to a dialytic HFR method for >6 months.

METHODS

Six patients with a mean age of 53.8 +/- 11 yrs (five males, one female), treated with standard bicarbonate dialysis for a mean of 79.2 months, underwent HFR for a mean period of 14.9 +/- 6 months. Filters used were: a) in all patients polysulfone with 0.7 m2 of surface for the convection; b) polysulfone with 1.7 m2 in one patient, and modified cellulose with 2.0 m2 in five patients for diffusion; c) hydrophobic interaction resin and uncovered mineral carbon 240 mL for the adsorption. For all patients dialysis duration was 240 min and the amount of reinfusion fluid was 2.5 L/h as a mean, calculated according to blood flow and hematocrit (Hct), keeping a filtration fraction <22%. We evaluated, at different times, the following parameters: a) patient weight; b) Hct and erythropoietin (EPO) doses; c) parathyroid hormone (PTH); d) phosphatemia and doses of administered vitamin D; e) homocysteine (Hcy) and Beta2-microglobulin (Beta2-m); f) and albuminemia and transferrinemia as nutritional parameters.

RESULTS

We observed an increase in Hct, with a reduction in EPO dosage, and an increase in albumin and transferrin levels, an improvement in nutritional indexes and in patient well-being. The mild increase in Hct with the same EPO dose was present in spite of a switch to intravenous (i.v.) administration from subcutaneous administration. There was low morbidity and only one hospitalization due to an infectious episode.

CONCLUSIONS

HFR allows an amino acid saving and pro-inflammatory middle molecule removal, resulting in a better clinical situation for progressively critical uremic patients.

Obese patients with obstructive sleep apnoea syndrome show a peculiar alteration of the corticotroph but not of the thyrotroph and lactotroph function

OBJECTIVE

Obstructive sleep apnoea syndrome (OSAS) is strongly associated with obesity (OB) and is characterized by several changes in endocrine functions, e.g. GH/IGF-I axis, adrenal and thyroid activity. It is still unclear whether these alterations simply reflect overweight or include peculiar hypoxia-induced hormonal alterations. Hormonal evaluations have been generally performed in basal conditions but we have recently reported that OSAS is characterized by a more severe reduction of the GH releasable pool in comparison to simple obesity. We aimed to extend our evaluation of anterior pituitary function to corticotroph, thyrotroph and lactotroph secretion under dynamic testing in OSAS in comparison with simply obese and normal subjects.

SUBJECTS AND METHODS

In 15 male patients with OSAS [age, mean +/- SEM 43.5 +/- 1.6 years; body mass index (BMI) 39.2 +/- 3.1 kg/m2; apnoea/hypopnoea index, (AHI) 53.4 +/- 8.7], 15 male patients with simple obesity (OB, age 39.7 +/- 1.2 years; BMI 41.2 +/- 2.0 kg/m2; AHI 3.1 +/- 1.2 events/h of sleep) and in 15 normal lean male subjects (NS, age 38.2 +/- 1.4 years; BMI 21.2 +/- 0.8 kg/m2; AHI 1.9 +/- 0.8 events/h of sleep) we evaluated: (a) the ACTH and cortisol responses to CRH [2 microg/kg intravenously (i.v.)] and basal 24 h UFC levels; (b) the TSH and PRL responses to TRH (5 microg/kg iv) as well as FT3 and FT4 levels.

RESULTS

Twenty-four-hour UFC levels in OSAS and OB were similar and within the normal range. Basal ACTH and cortisol levels were similar in all groups. However, the ACTH response to CRH in OSAS (Deltapeak: 30.3 +/- 3.8 pmol/l; DeltaAUC: 682.8 +/- 128.4 pmol*h/l) was markedly higher (P < 0.001) than in OB (Deltapeak: 9.3 +/- 1.4 pmol/l; DeltaAUC 471.5 +/- 97.3 pmol*h/l), which, in turn, was higher (P < 0.05) than in NS (Deltapeak: 3.3 +/- 0.9 pmol/l; DeltaAUC 94.7 +/- 76.7 pmol*h/l). On the other hand, the cortisol response to CRH was not significantly different in the three groups. Basal FT3 and FT4 levels as well as the TSH response to TRH were similar in all groups. Similarly, both basal PRL levels and the PRL response to TRH were similar in the three groups.

CONCLUSIONS

With respect to patients with simple abdominal obesity, obese patients with OSAS show a more remarkable enhancement of the ACTH response to CRH but a preserved TSH and PRL responsiveness to TRH. These findings indicate the existence of a peculiarly exaggerated ACTH hyper-responsiveness to CRH that would reflect hypoxia- and/or sleep-induced alterations of the neural control of corticotroph function; this further alteration is coupled to the previously described, peculiar reduction of somatotroph function.

Neuroendocrine and metabolic effects of acute ghrelin administration in human obesity

Ghrelin stimulates appetite and plays a role in the neuroendocrine response to energy balance variations. Ghrelin levels are inversely associated with body mass index (BMI), increased by fasting and decreased by food intake, glucose load, insulin, and somatostatin. Ghrelin levels are reduced in obesity, a condition of hyperinsulinism, reduced GH secretion, and hypothalamus-pituitary-adrenal axis hyperactivity. We studied the endocrine and metabolic response to acute ghrelin administration (1.0 microg/kg i.v.) in nine obese women [OB; BMI (mean +/- SD) 36.3 +/- 2.3 kg/m(2)] and seven normal women (NW; BMI 20.3 +/- 1.7 kg/m(2)). Basal ghrelin levels in NW were higher than in OB (P < 0.05). In NW, ghrelin increased (P < 0.05) GH, prolactin (PRL), ACTH, cortisol, and glucose levels but did not modify insulin. In OB, ghrelin increased (P < 0.01) GH, PRL, ACTH, and cortisol levels. The GH response to ghrelin in OB was 55% lower (P < 0.02) than in NW, whereas the PRL, ACTH, and cortisol responses were similar. In OB, ghrelin increased glucose and reduced insulin (P < 0.05). Thus, obesity shows remarkable reduction of the somatotroph responsiveness to ghrelin, suggesting that ghrelin hyposecretion unlikely explains the impairment of somatotroph function in obesity. On the other hand, in obesity ghrelin shows preserved influence on PRL, ACTH, and insulin secretion as well as in glucose levels.

Ageing, growth hormone and physical performance

Human ageing is associated to a declining activity of the GH/IGF-I axis and to several changes in body composition, function and metabolism which show strict similarities with those of younger adults with pathological GH deficiency. The age-related changes of the GH/IGF-I axis activity are mainly dependent on age-related variations in the hypothalamic control of somatotroph function, which is also affected by changes in peripheral hormones and metabolic input. The term "somatopause" indicates the potential link between the age-related decline in GH and IGF-I levels and changes in body composition, structural functions and metabolism which characterise ageing. Physical exercise is an important environmental regulator of the GH/IGF-I axis activity. Increased physical fitness and regular training increase GH production in adults, while the GH response to aerobic or resistance exercise is reduced with age. In older subjects regular exercise has the potential to improve overall fitness and quality of life and is also associated to decreased morbidity and increased longevity. Similar effects are seen following GH therapy in adult deficiency. This assumption led to clinical trials focusing on rhGH and/or rhlGF-I as potential anabolic drug interventions in elderly subjects. To restore the activity of GH/IGF-I axis with anabolic, anti-ageing purposes, attention has been also paid to GH-releasing molecules such as GHRH, orally active synthetic GH-secretagogues (GHS) and, more recently, to the endogenous natural GHS, ghrelin, which exerts several important biological actions, including the regulation of metabolic balance and orexigenic effects. At present, however, there is no definite evidence that "frail" elderly subjects really benefit from restoring GH and IGF-I levels within the young adult range by treatment with rhGH, rhlGF-I, GHRH or GHS. In this article the alteration of the GH/IGF-I axis activity during ageing is revised taking into account the role of physical activity as a regulator of the axis function and considering the effects of the restoration of GH and IGF-I circulating levels on body composition and physical performance.

Effects of ghrelin on the insulin and glycemic responses to glucose, arginine, or free fatty acids load in humans

Ghrelin possesses central and peripheral endocrine actions including influence on the endocrine pancreatic function. To clarify this latter ghrelin action, in seven normal young subjects [age (mean +/- SEM), 28.3 +/- 3.1 yr; body mass index, 21.9 +/- 0.9 kg/m(2)), we studied insulin and glucose levels after acute ghrelin administration (1.0 microg/kg i.v.) alone or combined with glucose [oral glucose tolerance test (OGTT), 100 g orally], arginine (ARG, 0.5 g/kg i.v.) or free fatty acid (FFA, Intralipid 10%, 250 ml). Ghrelin inhibited (P < 0.05) insulin and increased (P < 0.05) glucose levels. OGTT increased (P < 0.01) glucose and insulin levels. FFA increased (P < 0.05) glucose but did not modify insulin levels. ARG increased (P < 0.05) both insulin and glucose levels. Ghrelin did not modify both glucose and insulin responses to OGTT as well as the FFA-induced increase in glucose levels; however, ghrelin administration was followed by transient insulin decrease also during FFA. Ghrelin blunted (P < 0.05) the insulin response to ARG and enhanced (P < 0.05) the ARG-induced increase in glucose levels. In all, ghrelin induces transient decrease of spontaneous insulin secretion and selectively blunts the insulin response to ARG but not to oral glucose load. On the other hand, ghrelin raises basal glucose levels and enhances the hyperglycemic effect of ARG but not that of OGTT. These findings support the hypothesis that ghrelin exerts modulatory action of insulin secretion and glucose metabolism in humans.

[Morpho-functional study of peritoneum in peritoneal dialysis]

BACKGROUND

Peritoneal dialysis (PD) impairs both structure and function of the peritoneal membrane (PM). Aim of the study is to examine the relationship among dialytic, histological and functional parameters in PD patients.

METHODS

Thirty-one PD patients were submitted to peritoneal biopsy (PB) during catheter removal for malfunction or after dropping out of the treatment. For each patient PM transport was evaluated by the last peritoneal equilibration test (PET) prior to PB. Each daily glucose load was calculated. PB was performed at a distance of at least 5 cm from the catheter insertion point. The tissues were promptly embedded in formalin and stained for histological and immunohistochemical studies.

RESULTS

1) Patients with mesothelial impairment had longer treatment time. 2) Patients presenting submesothelial sclerosis (SS) and those with impairment of submesothelial basement membrane and subendothelial vascular membrane (SVM) were submitted to larger daily glucose loads. 3) High transporters were exposed to larger daily glucose loads and presented an SS thickness greater than 50 micron more frequently than medium-high transporters. 4) Mesothelial loss was correlated with SS and vascular alterations. 5) SS and vascular injuries were related to each other and not to inflammatory infiltrate.

CONCLUSION

Our study suggests that PD length seems to be mainly involved in mesothelial impairment; glucose load appears to damage mainly the submesothelial layer; SS is not a constant event in PD patients and in itself does not seem to be a decisive factor in PD drop out.

Both fasting-induced leptin reduction and GH increase are blunted in Cushing's syndrome and in simple obesity

BACKGROUND

Simple obesity and Cushing's syndrome (CS) are two clinical models of leptin hypersecretion coupled with GH hyposecretion. Fasting inhibits leptin while stimulating GH secretion in normal human subjects.

OBJECTIVES

To clarify the effect of fasting on leptin and GH secretion in obesity and CS. PATIENTS AND PROTOCOL: We studied six women with CS [age 17-66 years; body mass index (BMI) 28.6 kg/m2], seven women with visceral obesity (OB; 20-41 years; BMI 42.9 kg/m2) and seven normal women (NS; 25-31 years; BMI 19.3 kg/m2). The effects of 36-h fasting on 8-h diurnal mean leptin, GH, insulin and glucose concentrations (mLEPTc, mGHc, mINSc and mGLUc) as well as on the IGF/IGFBP system were studied.

RESULTS

Before fasting, mLEPTc in OB and in CS were similar and both were higher (P < 0.01) than in NS. OB and CS showed similar mGHc, which were lower (P < 0.05) than in NS. Fasting induced a reduction in mLEPTc that was significant in NS and CS (P < 0.04) but not in OB. The mLEPTc in OB and CS after fasting remained higher (P < 0.05) than in NS. After fasting, OB and CS showed no increase in mGHc, although this clearly increased (P < 0.02) in NS. IGF-I but not IGFBP-3 levels decreased in all groups (P < 0.05). Fasting reduced mINSc and mGLUc while increasing IGFBP-1 in all groups. After fasting, mINSc in OB and CS remained higher (P < 0.03) than in NS.

CONCLUSIONS

Short-term fasting has less inhibitory effect on leptin and no stimulatory effect on GH secretion in patients with Cushing's syndrome as well as simple obesity. After fasting, insulin levels in hypercortisolaemic and also in obese patients remained higher than in normal subjects suggesting that hyperinsulinism could play a role in the altered response of leptin and GH to starvation in these conditions.

Concomitant impairment of growth hormone secretion and peripheral sensitivity in obese patients with obstructive sleep apnea syndrome

To clarify the impairment of the GH/IGF-I axis in obstructive sleep apnea syndrome (OSAS), in 13 adult male patients with OSAS (OSA) as well as 15 weight-matched patients with simple obesity (OB) and 10 normal lean male subjects (NS), we studied: 1) the GH response to GHRH (1 micro g/kg iv) plus arginine (30 g iv); and 2) the IGF-I and IGF binding protein-3 responses to a very low dose recombinant human (rh)GH treatment (5.0 microg/kg sc per day for 4 d). The GH response to arginine plus GHRH in OSA was lower than in OB (P < 0.05), which in turn was lower than in NS (P < 0.001). Basal IGF-I levels in OSA were lower than in OB (P < 0.05), which in turn were lower than in NS (P < 0.03). As opposed to OB and NS, in OSA a very low rhGH dose did not affect IGF-I. Adjusting for age and basal values, rhGH-induced IGF-I rise in OSA was lower than in OB (P < 0.01). IGF binding protein-3, glucose, and insulin levels in the three groups were not modified by rhGH. OSA show a more marked impairment of the maximal secretory capacity of somatotroph cells together with reduced IGF-I sensitivity to rhGH stimulation. These findings suggest that OSAS is connoted by a concomitant impairment of GH secretion and sensitivity.

Glucagon administration elicits blunted GH but exaggerated ACTH response in obesity

Reduction in both spontaneous and stimulated GH secretion in obesity has been clearly demonstrated. Mild hyperactivity of hypothalamus-pituitary-adrenal (HPA) axis has been also reported. Glucagon, at least after im administration, induces clear increase in either GH or ACTH and F levels but its effect on somatotroph and corticotroph secretion in obesity has never been studied. In 7 patients with abdominal obesity (OB, aged 24-42 yr, BMI: 29.1-43.9 kg/m2, waist/hip ratio [WHR]: 0.86-1.00) we studied the GH, ACTH and F responses to the im administration of glucagon (0.017 mg/kg at 0 min). The results in OB were compared with those in a group of 6 age-matched controls normal subjects (Ns aged 26-32 yr, BMI 19.7-22.5 kg/m2). In Ns glucagon administration induced clear increase in GH (peak vs baseline, mean+/-SE: 11.6+/-3.4 vs 3.3+/-0.7 microg/l, p<0.02), and ACTH (52.9+/-15.2 vs 19.0+/-1.5 pg/ml, p<0.02) levels which peaked at +150 and +165 min, respectively. Increase in F levels (222.3+/-23.8 vs 158.3+/-7.0 ng/ml, p<0.05) was also recorded but peaked at +180 min. In OB glucagon administration induced GH response (7.4+/-2.3 vs 0.8+/-0.6 microg/l) lower (p<0.05) than that recorded in Ns; when the GH responses were evaluated by co-variance analysis, a significant difference between the 2 groups was recorded in term of peaks but not of AUCs. On the other hand, the ACTH response to glucagon in OB was higher than that in Ns (11452.6+/-2447.7 vs 4892.2+/-719.4 pg/ml x min, p<0.05). The F response to glucagon in OB and Ns was, however, similar (24057.9+/-4109.1 vs 29835.9+/-1566.0 ng/ml x min). In conclusion, this study demonstrates that in obese patients the im administration of glucagon elicits blunted GH response but exaggerated ACTH increase which is uncoupled with the adrenal response. These findings agree with the existence of concomitant GH insufficiency and altered corticotroph function in obesity.

Neuroendocrine and metabolic determinants of the adaptation of GH/IGF-I axis to obesity

Obese patients show marked impairment in spontaneous secretion as well as in the somatotroph responsiveness to all provocative stimuli. GH insufficiency in obese patients has been reported reversible after long-term diet and marked weight loss but somatotroph secretion is not restored by fasting. Among potential neuroendocrine causes, GHRH hypoactivity has been shown but it is likely that alterations in the influence of ghrelin, the gastric-derived natural ligand of the GHS-R, and or of the NPY/leptin interplay could have a role. Among metabolic alterations, the chronic elevation of FFA levels and hyperinsulinism probably have a key role in causing GH insufficiency in obesity. Despite marked GH insufficiency, total IGF-I levels are basically preserved while free IGF-I levels are even increased thus questioning real hypoactivity of GH/IGF-I axis in obesity. Peripheral GH hypersensitivity due to increased GH receptor status, hyperinsulinism and reduced IGFBP-I levels likely explain almost normal total IGF-I and increased free IGF-I levels which, in turn, probably exert an increased negative feedback action on somatotroph cells.

Thyroid function and anti-thyroid antibodies in MS patients screened for interferon treatment. A multicenter study

Interferon beta (IFNB) treatment for multiple sclerosis (MS) has been associated with thyroid disorders (TD), in particular in patients with subclinical TD or anti-thyroid (AT) autoantibodies (autoAb) before starting treatment. TD and AT autoAb frequency was reported increased in MS. To determine whether MS patients have subclinical thyroid function abnormalities or anti-thyroid autoimmunity predisposing to develop TD, we performed a prospective multicenter screening of thyroid function and autoimmunity in 152 relapsing-remitting (RR) MS patients selected to receive IFNB treatment and in 437 healthy normothyroidal controls. Thyroid-related hormones and anti-thyroid microsomal antigen (anti-TMA) autoAb were tested with sensitive immunoradiometric or chromatographic assays. Cases were stratified for different progressively decreasing or increasing cutoff values of thyroid-stimulating hormone (TSH) (0.3, 0.2, 0.1, 3 and 5 mIU/l), and odds ratios (OR) with 95% confidence intervals (CI) calculated using logistic regression adjusted for gender, age, and anti-TMA autoAb positivity. The frequency of cases below or above the TSH cutoff values was not significantly different in MS patients and controls, and the risk to have an abnormal TSH level was not significantly increased in MS patients (OR ranging 0.37-0.84; CI, 0.05-3.01), even if anti-TMA autoAb positive (OR ranging 0.35-0.85; CI, 0.04-3.00). Frequencies of subclinical hypothyroidism and of anti-TMA autoAb positivity were, however, trending higher in MS men (ranging 5-7%) than in controls (3%). MS patients do not have an increased risk of subtle thyroid function abnormalities, subclinical TD, or anti-TMA autoAb positivity that may predispose to develop thyroid dysfunction during IFNB treatment. The positive trend for subclinical hypothyroidism and anti-TMA autoAb positivity, however, advises a longitudinal study of thyroid function and autoimmunity during IFNB treatment to see whether patients with baseline subclinical thyroid dysfunction develop clinically significant alteration during treatment.

Enhancement of the peripheral sensitivity to growth hormone in adults with GH deficiency

OBJECTIVE

Adults with severe GH deficiency (GHD) need recombinant human growth hormone (rhGH) replacement to restore body composition, structure functions and metabolic abnormalities. The optimal rhGH dose for replacement has been progressively reduced to avoid side effects. The aim of the present study was to define the minimal rhGH dose able to increase both IGF-I and IGF binding protein (BP)-3 levels in GHD and to verify the possible change in GH sensitivity.

DESIGN AND PATIENTS

To this goal, we studied the effect of 4-day treatment with 3 rhGH doses (1.25, 2.5 and 5.0 microg/kg/day) on IGF-I and IGFBP-3 levels in 25 panhypopituitary adults with severe GHD (12 males and 13 females, age: 44.5+/-3.0 years, body mass index (BMI): 27.0+/-0.9 kg/m(2)) and 21 normal young adult volunteers (NV, 12 males and 9 females, age: 30.5+/-2.0 years, BMI: 20.8+/-0.5 kg/m(2)).

RESULTS

Basal IGF-I and IGFBP-3 levels in GHD were lower (P<0.001) than in NV. In NV the 1.25 microg/kg dose of rhGH did not modify IGF-I levels. The dose of 2.5 microg/kg rhGH significantly increased IGF-I levels in men (P<0.001) but not in women, while the 5.0 microg/kg dose increased IGF-I levels in both sexes (P<0.001). IGFBP-3 levels were not modified by any of the administered rhGH doses. In GHD patients, all rhGH doses increased IGF-I levels 12 h after both the first (P<0.01) and the fourth rhGH dose (P<0.001). At the end of treatment percentage increases in IGF-I were higher (P<0.001) in GHD patients than in NV. In contrast with NV, in GHD patients the IGF-I response to short-term stimulation with rhGH was independent of gender. Moreover, GHD patients showed increases in IGFBP-3 after the fourth administration of both 2.5 and 5.0 microg/kg rhGH.

CONCLUSION

The results of the present study demonstrate that the minimal rhGH dose able to increase IGF-I and IGFBP-3 levels in GHD patients is lower than in normal subjects, at least after a very short treatment. This evidence suggests an enhanced peripheral GH sensitivity in GH deprivation.

Effects of 36 hour fasting on GH/IGF-I axis and metabolic parameters in patients with simple obesity. Comparison with normal subjects and hypopituitary patients with severe GH deficiency

OBJECTIVE

Reduction of growth hormone (GH) secretion in obesity probably reflects neuroendocrine and metabolic abnormalities. Even short-term fasting stimulates GH secretion and distinguishes normal from hypopituitary subjects with growth hormone deficiency (GHD). Marked weight loss improves GH secretion in obesity but the effect of fasting is controversial. We studied the effects of a 36 h fasting on the GH/IGF-I axis and metabolic parameters in obesity.

SUBJECTS

We studied nine obese patients (OB; three male and six female; age, 29.2+/-4.8; range, 18-59 y; body mass index (BMI), 43.4+/-2.7 kg/m(2); WHR, 0.9+/-0.1). Fifteen normal subjects (NS; eight male and seven female 28.9+/-0.6, 25-35 y; 21.6+/-0.4 kg/m(2)) and 10 adult hypopituitary patients with severe GH deficiency (GHD; seven male and three female; 37.6+/-2.3, 29-50 y; 24.5+/-1.0 kg/m(2); GH peak<3 microg/l after ITT and/or<9 microg/l after GHRH+arginine) served as control groups.

STUDY DESIGN

We studied the effects of 36 h fasting on 8 h diurnal mean GH, insulin and glucose concentrations (mGHc, mINSc and mGLUc; assay every 30 min from 8.00 am to 4.00 pm) as well as on IGF-I, IGFBP-3, ALS, IGFBP-1, GHBP and free fatty acid (FFA) levels.

RESULTS

Before fasting, basal IGF-I and ALS levels in OB were similar to those in NS and both were higher (P<0.001) than those in GHD. IGFBP-3 levels in OB were lower (P<0.01) than in NS but higher (P<0.02) than in GHD. GHBP levels in OB and GHD were similar and both were higher (P<0.01) than in NS. Glucose levels were similar in all groups. FFA levels in OB were higher (P<0.01) than in NS but similar to those in GHD. IGFBP-1 in OB were lower (P<0.05) than in NS and GHD which, in turn, were similar. On the other hand, mINSc in OB was higher (P<0.01) than that in NS and GHD which, in turn, were similar. The mGHc in OB was similar to that in NS but only the latter was higher (P<0.05) than in GHD. The individual mGHc in the three groups overlapped. After fasting, IGF-I levels in GHD were unchanged while they decreased in OB (P=NS) as well as in NS (P<0.01). IGFBP-3 and ALS levels did not change. GHBP levels in OB and GHD were unchanged while they increased in NS (P<0.01). Glucose and FFA levels were reduced and increased, respectively, in all groups (P<0.02 and P<0.01). IGFBP-1 increased while mINSc decreased in all groups (P<0.02 and P<0.01); in OB they persisted lower and higher (P<0.01) respectively, than in NS and GHD. Fasting significantly increased mGHc in NS (P<0.001) but not in OB as well as in GHD. Individual mGHc in OB showed persistent overlap with GHD.

CONCLUSIONS

Short-term fasting does not increase GH secretion in obesity and does not distinguish somatotroph function in obese from that in severe GHD adults. Short-term fasting in obesity has attenuated effects on insulin and IGFBP-1 secretion while it normally increases free fatty acids in spite of any change in GH secretion.

Mineralocorticoid receptor blockade by canrenoate increases both spontaneous and stimulated adrenal function in humans

Animal studies indicate that mineralocorticoid receptors (MR) in the hippocampus play a major role in the glucocorticoid feedback control of the hypothalamo-pituitary-adrenal (HPA) axis. Specifically, MR mediate the proactive feedback of glucocorticoids in the maintenance of basal HPA activity. The stimulatory effect of intracerebroventricular and intrahippocampal MR blockade on the HPA axis in animals has been clearly shown, whereas the effect of systemic administration of mineralocorticoid antagonists in humans is still contradictory. To clarify this point, in seven normal young women (aged 25-32 yr; body mass index, 19.0-23.0 kg/m(2)) we studied the effects of canrenoate (CAN; 200 mg as iv bolus at 2000 h, followed by 200 mg infused in 500 mL saline over 4 h up to 2400 h) or placebo (saline, 1.0 mL as iv bolus at 2000 h, followed by 500 mL over 4 h up to 2400 h) on the spontaneous ACTH, cortisol, dehydroepiandrosterone (DHEA) and aldosterone secretion as well as on the ACTH, cortisol, and DHEA responses to human CRH (2.0 microg/kg as iv bolus at 2200 h) or arginine vasopressin (AVP; 0.17 U/kg as im bolus at 2200 h). Blood samples were taken every 15 min from 2000-2400 h. During placebo, spontaneous ACTH and cortisol levels showed progressive decreases (P < 0.05) from 2000-2400 h (baseline vs. nadir, mean +/- SEM, 2.0 +/- 0.3 vs. 1.4 +/- 0.2 pmol/L and 115.1 +/- 23.7 vs. 63.5 +/- 24.3 nmol/L), whereas DHEA and aldosterone levels did not change. CRH induced clear increases in ACTH, cortisol, and DHEA levels (peaks, mean +/- SEM, 7.1 +/- 1.1 vs. 1.6 +/- 0.2 pmol/L, 322.9 +/- 19.5 vs. 92.8 +/- 24.5 nmol/L, and 44.2 +/- 2.7 vs. 20.0 +/- 3.0 nmol/L; P < 0.05). Similarly, AVP elicited significant increases in ACTH, cortisol, and DHEA levels (3.8 +/- 0.3 vs. 1.5 +/- 0.1 pmol/L, 211.9 +/- 27.2 vs. 67.7 +/- 9.7 nmol/L, and 51.6 +/- 4.0 vs. 16.3 +/- 2.0 nmol/L; P < 0.05). During CAN treatment, ACTH, cortisol, and DHEA levels showed progressive rises, which begun at approximately 60 min and peaked between 2300 and 2400 h (ACTH, 3.4 +/- 0.4 vs. 1.1 +/- 0.3 pmol/L; cortisol, 314.5 +/- 49.6 vs. 123.3 +/- 13.2 nmol/L; DHEA, 52.0 +/- 8.8 vs. 21.0 +/- 2.3 nmol/L; P < 0.05 vs. baseline as well as vs. the same time points during placebo). Aldosterone secretion was not modified by CAN. The ACTH, cortisol, and DHEA responses to human CRH were enhanced by CAN (10.0 +/- 1.7 pmol/L, 462.2 +/- 36.9 nmol/L, and 66.3 +/- 8.8 nmol/L), although statistical significance (P < 0.05) was obtained for cortisol and DHEA only. Also the ACTH, cortisol and DHEA responses to AVP were amplified by CAN (8.0 +/- 2.6 pmol/L, 324.0 +/- 34.8 nmol/L, and 77.8 +/- 4.0 nmol/L); again, statistical significance (P < 0.05) was obtained for cortisol and DHEA only. In conclusion, our study shows that the blockade of MR by CAN significantly enhances the activity of the HPA axis in humans, indicating a physiological role for MR in its control. These results also suggest that the stimulatory effect of CAN on HPA axis is mediated by concomitant modulation of CRH and AVP release.

Effect of IGF-I administration on growth hormone secretion in obese subjects

OBJECTIVE

The reduction of spontaneous and stimulated growth hormone (GH) secretion in obesity could reflect an increase of the inhibitory effect of insulin growth factor I (IGF-I) on somatotroph secretion.

DESIGN

In the present study we aimed to verify the effect of low dose recombinant human IGF-I (20 microg/kg subcutaneously (s.c.) at 0 min) on 3 h-spontaneous GH secretion (mGHc, 0-180 min) and on the GH response to growth hormone releasing hormone (GHRH) (1 microg/kg i.v. at+180 min) in obesity.

SUBJECTS

Five obese women with abdominal adiposity (OB, age, mean+/-s.e.m.: 31+/-7.13 y; BMI: 32.04+/-3.69 kg/m(2)) and eight age-matched lean women (NW, 28.3+/-1.2 y; 20.1+/-0.5 kg/m(2)) were studied.

RESULTS

The mGHc and GHRH-induced GH response in OB (1.0+/-0.7 microg/l; AUC(180-270 min): 688.6+/-202.4 microg/l min, respectively) were lower than in NW (2.6+/-0.8 microg/l, 1315.9+/-189.9 microg/l min, respectively, P<0.05). The administration of rhIGF-I increased circulating IGF-I levels in OB and NW to the same extent (339.0+/-50.39 and 420.3+/-30.5 microg/l, respectively). The rhIGF-I administration did not affect mGHc in OB or NW (1.1+/-0.9 and 3.2+/-1.0 microg/l, respectively) but inhibited (P<0.05) the GH response to GHRH in OB (324.2+/-153.1 microg/l) and NW (730.2+/-288.1 microg/l).

CONCLUSIONS

Our study shows that the administration of low dose rhIGF-I reduces the somatotroph responsiveness to GHRH in obesity as well as in normal subjects.

Endocrine activities of ghrelin, a natural growth hormone secretagogue (GHS), in humans: comparison and interactions with hexarelin, a nonnatural peptidyl GHS, and GH-releasing hormone

An endogenous ligand for the GH secretagogue-receptor (GHS-receptor) has recently been isolated, from both the rat and the human stomach, and named ghrelin. It is a 28-amino-acid peptide showing a unique structure with an n-octanoyl ester at its third serine residue, which is essential for its potent stimulatory activity on somatotroph secretion. In fact, it has been demonstrated that ghrelin specifically stimulates GH secretion from both rat pituitary cells in culture and rats in vivo. The aim of the present study was to test the GH-releasing activity of ghrelin in humans and to compare it with that of GHRH and hexarelin (HEX), a nonnatural peptidyl GHS, which possesses strong GH-releasing activity but also significantly stimulates PRL, ACTH, and cortisol secretion. To clarify the mechanisms of action underlying the GH-releasing activity of ghrelin in humans, its interaction with GHRH and HEX was also studied. Seven normal young volunteers (7 men; 24-32 yr old; body mass index, 20-24 kg/m(2)) were studied. All subjects underwent the administration of ghrelin, HEX, and GHRH-29 (1.0 microg/kg i.v. at 0 min) as well as placebo (2 mL isotonic saline i.v. at 0 min). Six subjects also underwent the combined administration of ghrelin and GHRH or HEX. Blood samples were taken every 15 min from -15 up to +180 min. GH levels were assayed at each time point in all sessions; PRL, ACTH, cortisol, and aldosterone levels were also assayed after administration of ghrelin and/or HEX. Ghrelin administration induced a prompt and marked increase in circulating GH levels (Cmax, mean +/- SEM, 92.1 +/- 16.7 microg/L; area under the curve, 1894.9 +/- 347.8 microg/L.h). The GH response to ghrelin was clearly higher (P < 0.01) than the one recorded after GHRH (26.7 +/- 8.7 microg/L; 619.6 +/- 174.4 microg/L.h) and even significantly higher (P < 0.05) than after HEX (68.4 +/- 14.7 microg/L; 1546.9 +/- 380.0 microg/L x h). Ghrelin administration also induced an increase in PRL, ACTH, and cortisol levels; these responses were higher (P < 0.05) than those elicited by HEX. A significant increase in aldosterone levels was recorded after ghrelin but not after HEX. The endocrine responses to ghrelin were not modified by the coadministration of HEX. On the other hand, the coadministration of ghrelin and GHRH had a real synergistical effect (P < 0.05) on GH secretion (133.6 +/- 22.5 microg/L; 3374.3 +/- 617.3 microg/L x h). In conclusion, ghrelin, a natural ligand of GHS-receptor, exerts a strong stimulatory effect on GH secretion in humans, releasing more GH than GHRH and even more than a nonnatural GHS such as HEX. Ghrelin, as well as HEX, also stimulates lactotroph and corticotroph secretion. Ghrelin shows no interaction with HEX, whereas it has a synergistical effect with GHRH on GH secretion. Thus, ghrelin is a new hormone playing a major role in the control of somatotroph secretion in humans, and its effects are imitated by nonnatural GHS.