BACKGROUND: Ghrelin exerts a wide range of metabolic functions. In contrast to the body of information accumulated on the role of ghrelin on energy balance, the possible relevance of the peptide on GH secretion in physiological and pathological conditions has so far been poorly investigated. AIM: The aim of the present study was to evaluate circulating ghrelin levels in acromegalic patients in basal conditions and in response to oral glucose tolerance test (OGTT). PATIENTS: Serum ghrelin, insulin and leptin levels were measured in 31 healthy normal weight subjects as controls, 25 patients with simple obesity and 17 non-diabetic acromegalic patients. Ghrelin and insulin response to OGTT was evaluated in six controls, four obese and six acromegalic patients. RESULTS: The acromegalic patients showed ghrelin levels lower than those observed in normal weight subjects (201+/-20 vs 329+/-32 pmol/l, P<0.05) and similar to those found in obese subjects (165+/-14 pmol/l, P=not significant). Both obese and acromegalic patients had insulin levels significantly higher than controls, while high levels of leptin were detected only in obese subjects. Serum ghrelin levels showed a significant negative correlation with insulin, leptin and body mass index (P<0.05) in normal and obese subjects. No correlation was observed in acromegalic patients, although those with severe insulin resistance showed the lowest ghrelin values (161+/-20 pmol/l). In controls and obese subjects, ghrelin levels showed a significant decrease (25-40%) during OGTT, while no effect was detectable in acromegalic patients. CONCLUSIONS: This study reports that patients with active acromegaly show low levels of circulating ghrelin that are not further reduced by OGTT, this pattern of secretion probably depending on both GH-induced insulin resistance and the putative GH/IGF-I negative feedback control on ghrelin secretion.
V Cappiello, C Ronchi, PS Morpurgo, P Epaminonda, M Arosio, P Beck-Peccoz and A Spada
D Cortelazzi, V Cappiello, PS Morpurgo, S Ronzoni, MS Nobile De Santis, I Cetin, P Beck-Peccoz and A Spada
OBJECTIVE: Ghrelin is a GH secretagog isolated recently from rat stomach and involved in the stimulation of food intake and adiposity in rodents and humans. Moreover, subsequent studies showed that ghrelin is expressed in rat and human placenta, suggesting a possible influence of the peptide on fetal growth. The aim of this study was to evaluate circulating levels of ghrelin in appropriate for gestational age (AGA) or intrauterine growth-restricted (IUGR) fetuses. SUBJECTS AND METHODS: Ghrelin levels between 20 and 39 weeks of gestation were measured in 16 AGA and nine IUGR fetuses in whom blood was collected by cordocentesis performed for prenatal diagnosis of different diseases or during elective cesarean section. In most samples, GH, cortisol and leptin levels were also evaluated. Results are expressed as means+/-S.D. Differences were tested using the Student's t-test with Welch correction. P<0.05 was considered significant. RESULTS: All fetuses showed levels of ghrelin in the umbilical venous blood (100+/-99 pmol/l) that did not correlate with the gestational age or the maternal ghrelin levels. No difference was found between umbilical venous and arterial concentrations, suggesting that fetal tIssues are a source of ghrelin. Ghrelin levels in IUGR fetuses were significantly higher than those found in AGA fetuses (176+/-125 vs 58+/-44 pmol/l; P<0.005). Moreover, in samples obtained at birth, ghrelin concentrations correlated negatively with birth weight (P<0.05). In IUGR fetuses, GH and cortisol concentrations were higher and leptin levels lower than in AGA fetuses, although no significant correlation between these parameters and ghrelin levels was found. CONCLUSION: The presence of ghrelin in the fetal circulation as well as its increase in IUGR fetuses suggest a role of this peptide during intrauterine development.
CL Ronchi, S Corbetta, V Cappiello, PS Morpurgo, C Giavoli, P Beck-Peccoz, M Arosio and A Spada
OBJECTIVE: Adiponectin (ApN) is an adipocytokine expressed in human adipose cells with anti-atherogenic and anti-inflammatory properties that plays a role in the pathophysiology of insulin resistance, metabolic syndrome and coronary artery disease. The aim of the study was to evaluate ApN secretion in patients with acromegaly, a chronic disease associated with insulin resistance and increased cardiovascular mortality, and to correlate ApN levels with hormonal, metabolic and cardiovascular parameters. DESIGN AND METHODS: The study included 32 patients with active acromegaly (11 male and 21 female, aged 48+/-11 years, duration of disease: 8+/-6 years, GH: 9.2+/-9.8 microg/l, IGF-I: 80+/-33 nmol/l (means+/-s.d.)) and 38 control subjects sex- and body mass index (BMI)-matched. In all subjects, serum ApN, leptin and ghrelin levels, BMI, waist circumference, insulin resistance (assessed by homeostasis model assessment and the quantitative insulin check index), lipid profile and blood pressure values were evaluated. RESULTS: Acromegalic patients and control subjects had similar ApN levels (9.4+/-3.5 vs 9.5+/-4.0 mg/l, NS), while when considering obese subjects acromegalic patients had ApN levels significantly higher than controls (10.2+/-4 vs 7.5+/-3 mg/l, P<0.05). No significant correlation between ApN and GH/IGF-I levels or duration of disease was found. ApN concentrations negatively correlated with BMI, waist circumference, glucose and diastolic blood pressure and positively with high-density lipoprotein cholesterol and ghrelin in controls, while all these correlations were lost in acromegalic patients. CONCLUSIONS: We provide evidence that, although metabolic and cardiovascular abnormalities are present in most acromegalic patients, in these subjects ApN levels are not reduced and, contrary to what is found in BMI-matched controls, do not correlate with cardiovascular risk factors. These data support the view that atherosclerosis is not the main determinant of cardiovascular mortality in acromegaly and suggest a permissive action of GH and/or IGF-I excess on ApN secretion.
MM Ciulla, P Epaminonda, R Paliotti, MV Barelli, C Ronchi, V Cappiello, A Sartorio, V Buonamici, F Magrini, P Beck-Peccoz and M Arosio
OBJECTIVES: Cardiac echoreflectivity is a noninvasive tool for evaluating cardiac fibrosis. The present paper aimed to study the modifications of cardiac echoreflectivity in a group of acromegalic patients before and after therapy, and to assess possible correlations with serum levels of procollagen III (PIIINP), a peripheral index of collagen synthesis. DESIGN AND METHODS: Cardiac echoreflectivity (as assessed by analyzing 2-D echocardiograms digitized off-line onto a personal computer) and PIIINP levels were evaluated in 16 acromegalic patients of new diagnosis not affected by arterial hypertension (10 males, six females, age+/-s.d.: 38+/-10 years), and in a group of 16 sex- and age-matched healthy subjects. All the patients were re-evaluated after surgical and/or medical therapy for acromegaly. The echo patterns were analyzed by software that supplies the derived collagen volume fraction (dCVF), an index of fibrosis. RESULTS: At baseline, acromegalic patients showed significantly higher dCVF values and PIIINP levels than healthy controls (3.1+/-0.5% vs 1.6+/-0.3%, P<0.01 and 8.7+/-2.2 vs 3.1+/-1.1 ng/ml, P<0.05, respectively, by unpaired Student's t-test). After therapy, dCVF and PIIINP levels normalized in the six controlled patients (that is, GH of <2.5 microg/l and IGF-I within normal range) (dCVF from 2.8+/-0.4% to 1.4+/-0.2%, P<0.001; PIIINP from 8+/-2.7 to 3.3+/-1.9 ng/ml, P<0.05), while no significant changes were found in noncontrolled patients (dCVF from 3.3+/-0.6% to 2.9+/-1.2% and PIIINP from 9.1+/-1.9 to 7.9+/-3.5 ng/ml, P=NS). A positive correlation between dCVF and PIIINP (r=0.75, P<0.001) and between IGF-I and both dCVF and PIIINP (r=0.65 and 0.61 respectively, P<0.05) was found in acromegalic patients. CONCLUSIONS: Cardiac echoreflectivity, which may be a reflection of heart collagen content, is increased in patients with active acromegaly and correlates with PIIINP concentrations. After cure or adequate control of the disease, both parameters revert to normal. Echoreflectivity analysis could be a useful adjuvant parameter in the assessment of the activity of acromegalic disease.
M Arosio, CL Ronchi, C Gebbia, S Pizzinelli, D Conte, V Cappiello, P Epaminonda, BM Cesana, P Beck-Peccoz and M Peracchi
OBJECTIVE: Ghrelin, a gut-brain peptide involved in the control of energy homeostasis, affects antero-pituitary and gastro-entero-pancreatic (GEP) hormone secretion in healthy subjects. We aimed to verify whether such hormonal responses are retained in acromegaly, a disease characterized by high GH, subnormal ghrelin and abnormal GEP hormone levels. DESIGN AND METHODS: The effect of ghrelin (3.3 microg/kg given after overnight fasting as an i.v. bolus) on GH, prolactin (PRL), adrenocorticotropin (ACTH), cortisol, insulin, glucose, total somatostatin (SS) and pancreatic polypeptide (PP) circulating levels were evaluated in seven non-diabetic patients with newly diagnosed acromegaly and in nine healthy controls. RESULTS: Ghrelin elicited a prompt, marked increase of serum GH and PRL levels in all normal (from 1.6+/-0.6 to 52.9+/-7.8 and from 9.7+/-0.8 to 24.2+/-4.8 microg/l (means+/-S.E.M.), respectively) and acromegalic subjects (from 11.2+/-4.9 to 91.6+/-21.0 and from 42.9+/-26.1 to 113.8+/-79.0 microg/l, respectively). Both plasma ACTH and serum cortisol levels rose significantly in the controls, whereas the cortisol response was blunted in the acromegalic patients. Glucose levels rose earlier and insulin levels fell later in all subjects, with a significantly greater net insulin decrease in acromegalic than in healthy subjects (-80+/-21 vs -17+/-4 pmol/l, P<0.01). A prompt PP rise and a biphasic SS response occurred in all controls, whereas in the acromegalic group the PP response (from 26.1+/-5.0 to 92.2+/-39.0 pmol/l) and the SS response (from 11.9+/-3.0 to 19.7+/-4.0 ng/l) were quite variable. CONCLUSIONS: Ghrelin affects both pituitary and GEP hormones in acromegalic patients as in normal subjects. These findings suggest that ghrelin actions on the energy balance are mediated by complex interactive endocrine loops that involve also the gut and pancreas.