Acyl ghrelin and metabolic hormones in pregnant and lactating sows.

Ghrelin, the endogenous ligand of the growth hormone (GH) secretagogue receptor, is considered a pleiotropic regulator involved in a large array of functions, including control of energy balance, regulation of food intake and, more recently, modulation of the reproductive axis. The present study was aimed at determining the changes in plasma concentrations of acyl-ghrelin in pregnant and lactating sows, with special emphasis on the relationship with the levels of GH, leptin, non-esterified fatty acids (NEFA) and insulin-like growth factor (IGF-1). Blood samples were collected via jugular venipuncture from 22 multiparous sow 30, 60 and 90 days after artificial insemination, 7 and 21 days after farrowing and at first oestrus post-weaning. Plasma concentrations of acyl-ghrelin, leptin, GH and IGF-1 were quantified by validated radioimmunoassay; NEFA were determined using a colorimetric procedure. Plasma acyl ghrelin levels were highest at 30 days of pregnancy and decreased thereafter and during lactation. At the beginning of lactation, GH, IGF-1 and NEFA concentrations significantly increased, while a significant reduction occurred in leptin. In conclusion, ghrelin concentrations in sow maternal circulation does not seem to play an important role in maintaining circulating GH levels during lactation; moreover, ghrelin is not associated with leptin, NEFA and IGF-1 levels.

Gastric immunolocalization and plasma profiles of acyl-ghrelin in fasted and fasted-refed prepuberal gilts.

Ghrelin is a peripheral circulating hormone, mainly released from the stomach, which can stimulate food intake. We studied fed, fasted and fasted-refed prepuberal gilts in order to outline possible changes in gastric mucosal ghrelin cells and in plasma ghrelin profiles in response to food deprivation. Acyl-ghrelin-immunoreactive cells were numerous in oxyntic glands, less abundant in cardiac glands and least frequent in pyloric glands, with the addition of a minor population of labelled cells in the gastric pit mucosa. When fed and fasted animals were compared (72-h fast versus fed; n = 4 each), no clear-cut differences were revealed in labelled cell numbers, nor in their staining intensity. An RIA for plasma porcine acyl-ghrelin (n-octanoylated at Ser-3), not recognizing des-acyl-ghrelin, was validated. Plasma acyl-ghrelin progressively increased upon fasting (over 6, 12, 24 and 48 h); ghrelin levels significantly (P<0.05) higher than those prefast were reached at 72 h. After refeeding, plasma ghrelin was rapidly restored to basal values by 6 h. In the same animals, plasma insulin was significantly reduced throughout the fasting period (6-72 h), while rapidly increasing after refeeding. Non-esterified fatty acid levels increased during fasting (12-72 h) and rapidly returned to low values after refeeding. In conclusion, the present study demonstrates that starvation and refeeding influence ghrelin plasma level in prepuberal gilts. The absence of detectable changes in ghrelin cells, as seen in immunohistochemistry, could be due to a large intracellular storage of potentially releasable acylghrelin.

Coexistence of different phenotypes in a family with glucocorticoid-remediable aldosteronism.

In glucocorticoid-remediable aldosteronism (GRA), there is a large interfamily variation of phenotype. We report three subjects with GRA in a single family (parents, two brothers and two sisters), of whom only one (proband) displayed classical features of the mineralocorticoid excess. The proband was a man found to be hypertensive and hypokalaemic at the age of 24 years. Plasma renin activity was suppressed and plasma aldosterone was repeatedly elevated. Blood pressure and aldosterone levels normalized within 5 days of dexamethasone therapy. The presence of a chimaeric CYP11B1/CYP11B2 gene was demonstrated by long-PCR and Southern blotting (crossover site at the end of intron 3) in the proband, in the younger sister (sibling 1) and in the father. In these patients, sequencing of the chimaeric portion of CYP11B1 did not reveal any mutation, while sequencing of the chimaeric portion of CYP11B2 showed a V386A polymorphism in exon 7, known to cause only a minimal impairment of enzymatic activity. Sibling 1 was normotensive, normokalaemic and had normal PRA and aldosterone. The father had normal blood pressure and potassium, low-normal PRA and normal aldosterone. All three subjects had elevated levels of urinary 18-hydroxycortisol and 18-oxocortisol. Baseline 11-deoxycorticosterone (DOC), corticosterone (B) and aldosterone were high in the proband and normal in the father and sibling 1; 11-deoxycortisol (S) and cortisol (F) were normal. ACTH induced a normal increase of B, DOC, S and F, and an excessive aldosterone increase in all three patients. Abnormalities in the chimaeric portions of CYB11B1 or CYP11B2 genes did not account for the phenotypic disparity of the different members in a single GRA family. Altered regulation of the chimaeric gene may be responsible for differences in its activity.

Low ghrelin concentrations in nonalcoholic fatty liver disease are related to insulin resistance.

Several physiological and pathophysiological conditions, including changes in body fat, food intake, and insulin resistance, are known to be associated with variations in plasma ghrelin concentrations. We tested the hypothesis that insulin resistance exerts a primary role by measuring ghrelin in 86 patients with nonalcoholic fatty liver disease (NAFLD), a condition in which insulin resistance is relatively independent of obesity. Compared with 40 matched healthy subjects, patients with NAFLD had similar glucose levels and higher plasma insulin and insulin resistance [homeostasis model assessment (HOMA)-R index] by over 60%. Ghrelin was reduced (mean +/- SD, 226 +/- 72 pmol/liter in NAFLD vs. 303 +/- 123 in controls; P < 0.0001). In relation to quartiles of body mass index, ghrelin progressively decreased in controls (P = 0.003), but not in patients (P = 0.926). In relation to quartiles of HOMA-R, ghrelin decreased in both groups, and significantly correlated with HOMA-R. After adjustment for age and sex, HOMA-R was the sole factor significantly associated with low ghrelin in the whole group (odds ratio, 5.79; 95% confidence interval, 2.62-12.81; P < 0.0001) and specifically in NAFLD (2.96; 1.12-7.79; P = 0.028). The study suggests that insulin resistance is a major factor controlling ghrelin levels in subjects with and without NAFLD.

Anti-androgen treatment increases circulating ghrelin levels in obese women with polycystic ovary syndrome.

In a previous study we were the first to describe a negative correlation between circulating ghrelin concentrations and androgen levels in human plasma, suggesting an interaction between ghrelin and the endocrine regulation of reproductive physiology. We now investigated a potential direct regulatory influence of circulating androgens on plasma ghrelin levels. Fourteen obese women with polycystic ovary syndrome (PCOS) on a hypocaloric diet were randomly assigned to treatment groups (open-labeled design), receiving either placebo (no.=7) or the antiandrogen flutamide (no.=7) for 6 months. Anthropometry, visceral (VAT) and subcutaneous (SAT) adipose tissue (quantified by computerized tomography), plasma hormone levels, insulin sensitivity indexes (Quantitative Insulin-Sensitivity Check Index-QUICKI) and Homeostatic Model Assessment applied to the oral glucose tolerance test (HOMA(OGTT)) were evaluated at baseline and at the end of the study. Body weight decreased and insulin resistance indexes improved in both groups. A tendency toward a greater loss of VAT was observed in the flutamide group. Only in the flutamide group was a significant reduction of androgens levels observed. Plasma ghrelin levels significantly increased following treatment with flutamide, while ghrelin remained unchanged in the placebo group. We observed a negative correlation between changes of ghrelin levels and changes of androgen plasma concentration in the flutamide-treated group. In the same group a positive correlation was found between plasma ghrelin changes and insulin sensitivity as expressed by HOMA(OGTT). Analysis in a multiple regression model, however, showed that plasma ghrelin changes were mainly due to changes of androgen levels rather than improved insulin sensitivity. We, therefore, conclude that androgens are independent modulators of circulating ghrelin concentrations.

Improved confirmation of weak lupus anticoagulants by employing sensitive and insensitive reagents to the lupus anticoagulant.

Detection of a lupus anticoagulant (LA) is of major importance to detect a thrombotic tendency. Confirmation of its phospholipid dependency may represent a tricky step in the diagnostic algorithm for LA, as several tests may yield borderline results of little diagnostic help. To improve on this point, we had previously employed a procedure comparing sensitive [rabbit brain kaolin (RBK)] and insensitive [soy bean phosphatides (SBP)] reagents to LA to screen and confirm LA at the same time in activated partial thromboplastin systems (aPTT). Here we compared its performance against a platelet neutralization procedure (PNP). To allow comparisons of our procedures with the PNP, a percentage ratio correction was calculated according to the following formula: [(RBK ratio - SBP ratio) x 100]/ RBK ratio. Similarly for the PNP: percentage ratio correction = [(buffer ratio - platelet phospholipid ratio) x 100]/buffer ratio. On 44 known LA plasmas, the PNP, expressed in seconds, yielded 15 (34%) negative or borderline results. After ratio transformation, the PNP still yielded 10 of 15 (66%) uncertain results, whereas the RBK/SBP procedure did not give any uncertain results (P = 0.0002). The mean percentage ratio correction was far superior for the RBK/SBP procedure than for the PNP (53.24 +/- 15.93 versus 20.28 +/- 12.15%, P < 0.0001). The use of sensitive and insensitive reagents to the lupus anticoagulant increases the confirmatory yield of LA in aPTT systems and may deserve inclusion amongst the confirmatory procedures for its diagnosis.

Diagnostic value of plasma chromogranin A in neuroendocrine tumours.

AIM: The aim of this study was to assess the value of plasma chromogranin A (CgA), a protein produced by neuroendocrine cells, in the diagnosis of neuroendocrine tumours. METHODS: Eighty subjects with neuroendocrine tumours were studied. Thirty-four had carcinoids, 21 nonfunctioning endocrine pancreatic tumours, 17 multiple endocrine neoplasia type 1 (MEN 1) (six of these also had gastrinomas), and eight had functioning pancreatic tumours (four gastrinomas, two glucagonomas, two somatostatinomas). Twenty-eight healthy subjects were studied as controls. A fasting plasma sample was obtained from each subject, and CgA plasma levels were measured by the ELISA method using a kit (Dako A/S, Denmark). RESULTS: In control subjects, plasma CgA values were below 5 U/l. Among the patients, 20 of the 34 with carcinoid tumours, 12 of the 21 with nonfunctioning pancreatic tumours, nine of the 17 with MEN 1 (including the six with gastrinomas), and the four gastrinomas of the eight functioning pancreatic tumours, i.e. overall, 45 of the 80 patients (56.3%) had abnormally high CgA values (22-961 U/l). Most of the patients with elevated CgA values, except nine of the 10 with gastrinomas, had multiple liver metastasis. CONCLUSIONS: The results show that the diagnostic value of plasma CgA in neuroendocrine tumours is relatively low; it may be of some interest only in patients with advanced disease and liver metastasis. Gastrinoma seems to be an exception, because in this tumour high CgA values are generally found even in the absence of liver metastasis.

Mechanisms of hypertension in patients with chronic obstructive pulmonary disease and acute respiratory failure.

PURPOSE: To investigate the effects of hypoxemia, hypercapnia, and cardiovascular hormones (norepinephrine, endothelin-1, and atrial natriuretic factor) on blood pressure during acute respiratory failure. PATIENTS AND METHODS: Patients with chronic obstructive pulmonary disease and acute respiratory failure were divided into four groups of 10 patients each: hypoxemia-normocapnia, hypoxemia-hypercapnia, hypoxemia-hypocapnia, and normoxemia-hypercapnia. Plasma norepinephrine levels were determined by high-performance liquid chromatography with electrochemical detection. Plasma endothelin-1 and atrial natriuretic factor levels were radioimmunoassayed after chromatographic preextraction. RESULTS: Systolic blood pressure and cardiovascular hormone levels were greater in patients with hypercapnia (whether or not they also had hypoxemia) than in those with normocapnia and hypoxemia. For example, in patients with hypercapnia and normoxemia, the mean (+/- SD) systolic blood pressure was 183+/-31 mm Hg and the mean norepinephrine level was 494+/-107 pg/mL, as compared with 150+/- 6 mm Hg and 243+/-58 pg/mL in those with normocapnia and hypoxemia (both P<0.05). Similar results were seen for endothelin-1 and atrial natriuretic factor levels, and for the comparisons of hypoxemic patients who were hypercapnic with those who were normocapnic. CONCLUSIONS: These results suggest that blood carbon dioxide levels, rather than oxygen levels, are responsible for hypertension during acute respiratory failure, perhaps as a result of enhanced sympatho-adrenergic activity.

Low serum inhibin B levels as a marker of testicular damage after treatment for a childhood malignancy.

UNLABELLED: The aim of this study was to evaluate the role of inhibin B and the determination of its concentration to diagnose testicular damage after treatment for a childhood malignancy. Thirty-seven males treated for Hodgkin disease (n = 11) or non-Hodgkin lymphoma (n = 26) were examined at a mean age of 16.9+/-2.9 years. Mean age at the stop of therapy was 11.3+/-3.0 years and in most cases the chemotherapy regimen included gonadal damaging alkylating agents. Thirty-three normal males (mean age 17.9+/-4.1 years) were examined as controls. Serum samples were collected for determination of inhibin B, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone. Median inhibin values were significantly lower in patients than in controls (96.0 vs. 225.0 pg/ml, P<0.0001) and a strong negative correlation was found between inhibin B and FSH (r = -0.86, P<0.0001), a weak correlation with LH (r = -0.32, P<0.05) and no correlation with testosterone. In post-pubertal patients (i.e., over 16 years) a positive correlation was found between testicular size and inhibin level (r = 0.53, P<0.05), but not between testicular size and testosterone level. Pathological low levels (values that differed by more than 2 SD from the mean value of control subjects) were found in 20 patients for inhibin B and 8 for testosterone (P<0.01) and pathological high values in 19 patients for FSH and 3 for LH. CONCLUSION: This study confirms the role that inhibin B plays in the regulation of FSH secretion and provides further evidence of the utility of its evaluation as a direct indicator of male gonadal dysfunction.

Insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) concentrations compared to stimulated growth hormone (GH) in the evaluation of children treated for malignancy.

OBJECTIVE: The aim of this investigation was to evaluate the utility of IGF-I and IGFBP-3 determinations in screening for GH deficiency (GHD) in children previously submitted to treatment for childhood malignancy. PATIENTS AND METHODS: We compared the GH responses to two pharmacological tests (arginine and levo-dopa) with the IGF-I and IGFBP-3 levels in 48 patients (29 boys) who had undergone bone marrow transplantation (BMT) (36 patients) or treatment for a solid cranial tumor (12 patients). RESULTS: 22 patients (45.8%) showed GHD (i.e. GH peak < 8 ng/ml in both tests), and only three (13.6%) of the GHD patients had concomitant low IGF-I levels (i.e. -2 SD below the normal mean) and only one (4.5%) an abnormal IGFBP-3 value (i.e. -2 SD below the normal mean). Among the 26 children with normal GH secretion, 21 (80.8%) also showed normal IGF-I and IGFBP-3 levels, three (11.5%) had a concomitant low IGF-I value and two (7.7%) a concomitant low IGFBP-3 value. A significant correlation was found between GH secretion and age at diagnosis (r = 0.26, P < 0.05), and between IGF-I and IGFBP-3 (r = 0.52, P < 0.0001), but not between GH and IGF-I or IGFBP-3. Comparing the growth pattern of these patients from diagnosis to the first year after therapy or BMT, we found that while individual height changes did not correlate with the GH peak, a significant correlation was found between height SDS decrease and IGF-I (r = 0.31, P < 0.05) or IGFBP-3 SDS (r = 0.37, P < 0.01). CONCLUSION: Our results indicate that the cut-off of -2 SD for IGF-I and IGFBP-3 was insensitive in screening for GHD. A normal value did not exclude a subnormal GH response to provocative tests and therefore although IGF-I and IGFBP-3 levels may be indicators of the growth pattern, they cannot be used alone as a tool for identifying GHD children after treatment for childhood malignancy.

Low growth hormone-binding protein in infants with congenital hypothyroidism.

We evaluated the circulating levels of GH, insulin-like growth factor I (IGF-I), GH-binding protein (GHBP), and IGF-binding protein-3 (IGFBP-3) before L-T4 therapy in 19 infants with congenital hypothyroidism (CH), aged 12-29 days, diagnosed by neonatal screening and in a group of age- and sex-matched control infants. The same parameters were reevaluated after several months of treatment. Serum GHBP was measured by the high performance liquid chromatography-gel filtration method; serum GH, IGF-I, and IGFBP-3 levels were determined by commercial kits. The hypothyroid patients, before beginning therapy, presented significantly lower GHBP values than controls (P < 0.0001); during treatment, these values increased significantly; however, after 6 months they were still significantly lower than control values (P < 0.01). The pretreatment levels of GH were not significantly different from control values; after 1 month of treatment, GH did not show the decrease observed in controls and, therefore, was significantly higher (P < 0.01). The pretreatment levels of IGF-I were not significantly different from control values, but were lower in patients with severe than in those with mild hypothyroidism. They decreased at about 4 months of life and became significantly lower than control values at about 7 months of age (P < 0.05). In conclusion, it may be hypothesized that the condition of CH induces a change in GHBP expression, perhaps beginning in fetal life. The intrauterine production of IGF-I seems to be independent of the levels of GHBP and partially affected by fetal thyroid function.

Opioid peptides in response to mental stress in asymptomatic dilated cardiomyopathy.

Fourteen asymptomatic dilated cardiomyopathy patients showing normal plasma levels of beta-endorphin, Met-enkephalin, dynorphin B, norepinephrine and endothelin-1 but elevated atrial natriuretic factor (ANF) levels underwent two Mental Arithmetic Tests (MAT), with placebo and naloxone hydrochloride infusion, respectively. MAT significantly (p < 0.01) increased blood pressure, heart rate, opioid peptides, norepinephrine, ANF, but not endothelin-1. Naloxone infusion significantly (p < 0.05) attenuated the increments produced by MAT in all measured parameters during placebo infusion. These results indicate that in asymptomatic dilated cardiomyopathy the endogenous opioid system, activated by stress-induced sympathoadrenergic hyperactivity, may further increase the sympathetic tone in a positive feedback that is interrupted by naloxone.

Endogenous opioid peptides and mental stress in congestive heart failure patients.

Two groups of patients with acute congestive heart failure (CHF), New York Heart Association class III, presenting elevated plasma values of beta-endorphin, norepinephrine, atrial natriuretic factor (ANF) and endothelin-1, underwent the Mental Arithmetic Test (MAT) during placebo (n = 10) and naloxone hydrochloride (n = 10) infusion. The MAT during placebo significantly (p < 0.01) increased blood pressure, heart rate, plasma levels of Met-enkephalin, dynorphin B, beta-endorphin, norepinephrine, ANF and endothelin-1. The increases in norepinephrine, ANF and hemodynamics after the MAT during naloxone infusion were higher (p < 0.01) than those during placebo; thus, the transient upregulation of the endogenous opioid system during stress in CHF patients attenuates the hemodynamic response by reducing norepinephrine release.

Relationship between plasma endothelin-1 levels and myocardial ischemia induced by exercise testing.

At peak exercise, plasma endothelin-1 concentration increases in patients with effort angina as well as thallium-201 radionuclide perfusion defects; the opposite occurs in patients with normal scans and in healthy volunteers. It is concluded that exercise-induced ischemia correlates with enhanced endothelin-1 production.

Pressor effects of endogenous opioid system during acute episodes of blood pressure increases in hypertensive patients.

To investigate the involvement of endogenous opioids in acute increases in blood pressure and their functional relationship with atrial natriuretic factor and endothelin-1, we assessed plasma levels of beta-endorphin, met-enkephalin, dynorphin B, catecholamines, atrial natriuretic factor, and endothelin-1 before and after administration of the opioid antagonist naloxone hydrochloride (8 mg i.v.) in 28 hypertensive patients with a stress-induced acute increase in blood pressure. Ten patients with established mild or moderate essential hypertension and 10 normotensive subjects served as control groups. Opioids, atrial natriuretic factor, and endothelin-I were radioimmunoassayed after chromatographic preextraction; catecholamines were determined by high-performance liquid chromatography with electrochemical detection. Patients with an acute increase in blood pressure (systolic, 203.2 +/- 2.2 mm Hg; diastolic, 108.4 +/- 1.3) had plasma opioid, catecholamine, and atrial natriuretic factor levels significantly (P < .01) higher than hypertensive control patients (systolic pressure, 176.4 +/- 1.0 mm Hg; diastolic, 100.0 +/- 1.4), who had a hormonal pattern similar to that of normotensive subjects (systolic pressure, 123.2 +/- 1.5 mm Hg; diastolic, 75.0 +/- 2.0). Endothelin-1 did not differ in any group. In patients with an acute increase in blood pressure, naloxone significantly (P < .01) reduced blood pressure, heart rate, opioids, catecholamines, and atrial natriuretic factor 10 minutes after administration. Naloxone effects on blood pressure, heart rate, opioids, and catecholamines wore off within 20 minutes. In control groups, naloxone failed to modify any of the considered parameters. Our findings suggest that pressor effects of opioid peptides mediated by the autonomic nervous system during stress-induced acute episodes of blood pressure increase in hypertensive patients.

Opioid peptide modulation of circulatory and endocrine response to mental stress in humans.

Healthy subjects were classified according to their percent increase in systolic blood pressure (SBP) after mental arithmetic test (MAT) as low (delta SBP 9.3-15.1%, n = 15) and high (delta SBP 35.1-45.4%, n = 15) responders. During MAT, low responders showed significantly (p < 0.01) increased plasma levels of beta-endorphin, cortisol, catecholamines, and atrial natriuretic factor (ANF) and decreased levels of endothelin-1, whereas high responders showed increased (p < 0.01) levels of Metenkephalin, dynorphin B, and catecholamines. Pretreatment with naloxone hydrochloride enhanced (p < 0.01) SBP, heart rate, noradrenaline, cortisol, and endothelin-1 levels, and reduced (p < 0.01) ANF in low responders in response to MAT, whereas it decreased (p < 0.01) hemodynamic parameters, noradrenaline, and endothelin-1 in high responders. The individual differences in hemodynamic and endocrine responses to MAT may depend on a different activation of the endogenous opioid system.

Developmental pattern of fetal growth hormone, insulin-like growth factor I, growth hormone binding protein and insulin-like growth factor binding protein-3.

AIMS: To evaluate the developmental pattern of fetal growth hormone (GH), insulin-like growth factor I (IGF-I), GH binding protein (GHBP) and IGF binding protein-3 (IGF-3); to determine the implications for fetal growth. METHODS: Serum GH, IGF-I, GHBP and IGFBP-3 were measured in 53 fetuses, 41 aged 20-26 weeks (group A) and 12 aged 31-38 weeks (group B). Fetal blood samples were obtained by direct puncture of the umbilical vein in utero. Fetal blood samples were taken to rule out beta thalassaemia, chromosome alterations, mother to fetus transmissible infections, and for maternal rhesus factor. GHBP was determined by gel filtration chromatography of serum incubated overnight with 125I-GH. GH, IGF-I and IGFBP-3 were determined by radioimmunoassay. RESULTS: Fetal serum GH concentrations in group A (median 29 micrograms/l, range 11-92) were significantly higher (P < 0.01) than those of group B (median 16.7 micrograms/l, range 4.5-29). IGF-I in group A (median 20 micrograms/l, range 4.1-53.3) was significantly lower (P < 0.01) than in group B (median 75.2 micrograms/l, range 27.8-122.3). Similarly, IGFBP-3 concentrations in group A (median 950 micrograms/l, range 580-1260) were significantly lower than those of group B (median 1920 micrograms/l, range 1070-1770). There was no significant difference between GHBP values in group A (median 8.6%, range 6.6-12.6) and group B (median 8.3%, range 6-14.3). Gestational age correlated positively with IGF-I concentrations (P < 0.0001) and IGFBP-3 (P < 0.0001) and negatively with GH (P < 0.0001). GHBP values did not correlate with gestational age. Multiple regression analysis showed a negative correlation between GH:IGF-I ratio and fetal growth indices CONCLUSIONS: The simultaneous evaluation of fetal GH, IGF-I, IGFBP-3 and GHBP suggests that the GH-IGF-I axis might already be functional in utero. The progressive improvement in the efficiency of this axis in the last part of gestation does not seem to be due to an increase in GH receptors.

[Effects of naloxone on plasma levels of atrial natriuretic factor and noradrenaline during water load in moderate heart failure]. / Effetti del naloxone sui livelli plasmatici del fattore natriuretico atriale e della noradrenalina durante carico idrico nello scompenso cardiaco moderato.

BACKGROUND: The aim of our study was to evaluate the effects of endogenous opioids on the secretion of atrial natriuretic factor (ANF) in moderate chronic heart failure (HF). METHODS: We evaluated the effects of i.v. volume load (NaCl 0.9% at 0.25 ml/Kg/min for 60 minutes) on heart rate (HR), on mean arterial pressure (MAP) and on the plasma levels of beta-endorphin (beta-end), met-enkephalin (Met-enk), dynorphin (Dyn), atrial natriuretic factor (ANF) and noradrenaline (NA) in 10 patients (age 58 +/- 9) with HF in NYHA class II (group I) and in 8 healthy control subjects (age 54 +/- 10) group II). The volume load was repeated after at least three days during infusion of naloxone (2 micrograms/Kg/min), evaluating the above mentioned hemodynamic and hormonal parameters. RESULTS: The acute volume expansion caused an increase in ANF concentration (from 51.7 +/- 19.7 to 67.4 +/- 36.9 pg/ml; p < 0.05) and in beta-end (from 11.9 +/- 5.3 to 16.6 +/- 7.5 fmol/ml; p < 0.05), In group I. In group II an isolated increase in ANF was observed (from 14.1 +/- 7.8 to 21.9 +/- 7.9 pg/ml; p < 0.02). No significant changes were detected for HR, MAP, Dyn, Met-enk and NA. In group I the percent increase of ANF is less than in group II (30 vs 55%; p < 0.05). The volume load infused during naloxone infusion caused a significant increase in HR (from 73 +/- 6 to 78 +/- 9 bpm; p < 0.05) and in NA (from 311 +/- 123 to 415 +/- 142 pg/ml; p < 0.05) In group I. In group II, an increase in ANF was detected (from 13.8 +/- 6.0 to 23.6 +/- 5.0 pg/ml; p < 0.01). CONCLUSIONS: Our data suggest that in moderate HF beta-end stimulates the secretion of ANF and inhibits the activity of the sympatho-adrenergic system during acute volume expansion.

Nitrendipine treatment in women with polycystic ovarian syndrome: evidence for a lack of effects of calcium channel blockers on insulin, androgens, and sex hormone-binding globulin.

It has been shown that in vitro calcium channel blockers may regulate insulin secretion, and in vivo studies have demonstrated that they can reduce the degree of hyperinsulinemia and ameliorate the insulin-resistant state in subjects (particularly men) with obesity and hypertension. It is also commonly accepted that hyperinsulinemia may be an important factor responsible for the development of hyperandrogenism in obese women with polycystic ovarian syndrome (PCOS). We, therefore, investigated whether the administration of nitrendipine, a widely used calcium channel blocker, may improve both insulin levels and hyperandrogenism in a group of seven insulin-resistant hyperinsulinemic women with obesity and PCOS. They were treated for 7-8 days with oral nitrendipine (10 mg, twice daily) or placebo using a double blind, cross-over design. Before and after treatment, blood samples were obtained for androgen and sex hormone-binding globulin determinations, and an oral glucose tolerance test was performed, measuring glucose and insulin. Both nitrendipine and placebo failed to decrease basal and stimulated insulin levels. Moreover, no significant variations in testosterone, dehydroepiandrosterone sulfate, or sex hormone-binding globulin concentrations were observed after either treatment. Therefore, these data fail to support previous suggestions that calcium channel blockers may play a role in the treatment of hyperandrogenism and hyperinsulinemia in obese women with PCOS.

Insulin regulates testosterone and sex hormone-binding globulin concentrations in adult normal weight and obese men.

There are no studies in vivo on the effects of insulin on androgens and sex hormone-binding globulin (SHBG) in men. We, therefore, investigated the effects of insulin suppression on testosterone and SHBG in two groups of eight nondiabetic adult obese men and six healthy normal weight men who underwent diazoxide treatment (100 mg, three times daily) for 7 days. Blood samples for hormone determination were obtained before the subjects had been selected for the study, immediately before diazoxide administration, and on the last day of treatment. A 24-h oral glucose tolerance test was also performed for glucose, insulin, and C-peptide determinations before and on the last day of treatment. Only one subject experienced significant side-effects, and no significant changes in mean body weight were found during the treatment. Diazoxide administration worsened glucose tolerance in several subjects and reduced fasting and glucose-stimulated insulin levels by approximately 50% in both control and obese subjects. No significant difference was present between historical and pretreatment hormone values in either group. Moreover, there were no differences in pretreatment gonadotropin and SHBG concentrations between the two groups, whereas testosterone (free and total) levels were lower in the obese than in the control subjects. After diazoxide administration, testosterone (free and total) decreased slightly, but significantly, whereas LH and SHBG significantly increased in both groups. Diazoxide treatment increased estradiol levels in controls, but not in obese men. In conclusion, these results indicate that in vivo, insulin is capable of stimulating testosterone production and, simultaneously, of inhibiting SHBG concentrations in both normal weight and obese men.