Search

The diagnosis of pituitary corticotroph adenoma relies on the demonstration of a loss of the normal feedback control of adrenocorticotropic hormone (ACTH) biosynthesis by cortisol. The marked variability in the degree of ACTH suppression by glucocorticoids in these tumors, however, greatly enhances the difficulty in distinguishing Cushing’s disease from other syndromes of glucocorticoid excess. To illustrate this variability, we describe the clinical, biochemical, and morphological characteristics of a pituitary corticotroph adenoma in a 63-year-old woman, who presented with symptoms of a sellar mass but did not initially have florid Cushing’s disease. Light and electron microscopy of the pituitary tumor showed a corticotroph adenoma with Crooke’s hyalinization of the tumor cells, characterized by the accumulation of keratin immunoreactive microfilaments similar to those observed in normal corticotrophs in the presence of excess glucocorticoids. This case illustrates an unusual clinical presentation that may be associated with pituitary corticotroph adenoma showing Crooke’s hyalinization.

Neuropeptide Y (NPY) is present in the brain, the adrenal medulla, and peripheral sympathetic nerves. This peptide is released together with catecholamines during sympathoadrenal activation. It possesses direct vasoconstrictor properties that are not dependent on simultaneous adrenergic activation. Moreover, it potentiates the vascular effect of several stimulatory substances and may contribute to the modulation of blood pressure responsiveness under a number of circumstances. NPY may also be indirectly involved in the control of blood pressure through regulating the release of hormones with well-established actions on the cardiovascular system. Am J Hypertens 1988;1:193-199

A sex steroid-dependent modulation of the immune function in mammals is accepted, and evidence suggests that while estrogens enhance, androgens inhibit the immune response. The aim of this study was to explore in the adult male rat the effect of either neonatal flutamide (FTM) treatment or prepubertal orchidectomy (ODX) on endocrine markers in the basal condition and peripheral tumor necrosis factor alpha (TNFα) levels during inflammatory stress. For these purposes, (1) 5-day-old male rats were subcutaneously injected with either sterile vehicle alone or containing 1.75 mg FTM, and (2) 25-day-old male rats were sham operated or had ODX. Rats were sacrificed (at 100 days of age) in the basal condition for determination of peripheral metabolite levels. Additional rats were intravenously injected with bacterial lipopolysaccharide (LPS; 25 μg/kg body weight, i.v.) and bled for up to 4 h. Data indicate that (1) ODX increased peripheral glucocorticoid levels and reduced those of testosterone, whereas FTM-treated rats displayed low circulating leptin concentrations, and (2) LPS-induced TNFα secretion in plasma was significantly enhanced in the FTM and ODX groups. Our study supports that neonatal FTM treatment affected adiposity function, and adds data maintaining that androgens have a suppressive role in proinflammatory cytokine release in plasma during inflammation. Fil: Ongaro Gambino, Luisina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; Argentina Fil: Castrogiovanni, Daniel Cayetano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; Argentina Fil: Giovambattista, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; Argentina Fil: Gaillard, Rolf C.. Lausanne University Hospital; Suiza Fil: Spinedi, Eduardo Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; Argentina

There are only a few studies on the ontogeny and differentiation process of the hypothalamic supraoptic-paraventriculo-neurohypophysial neurosecretory system. In vitro neuron survival improves if cells are of embryonic origin; however, surviving hypothalamic neurons in culture were found to express small and minimal amounts of arginine-vasopressin (AVP) and oxytocin (OT), respectively. The aim of this study was to develop a primary neuronal culture design applicable to the study of magnocellular hypothalamic system functionality. For this purpose, a primary neuronal culture was set up after mechanical dissociation of sterile hypothalamic blocks from 17-day-old Sprague–Dawley rat embryos (E17) of both sexes. Isolated hypothalamic cells were cultured with supplemented (B27)-NeuroBasal medium containing an agent inhibiting non-neuron cell proliferation. The neurosecretory process was characterized by detecting AVP and OT secreted into the medium on different days of culture. Data indicate that spontaneous AVP and OT release occurred in a culture day-dependent fashion, being maximal on day 13 for AVP, and on day 10 for OT. Interestingly, brain-derived neurotrophic factor (BDNF) and Angiotensin II (A II) were able to positively modulate neuropeptide output. Furthermore, on day 17 of culture, non-specific (high-KCl) and specific (Angiotensin II) stimuli were able to significantly (P < 0.05) enhance the secretion of both neuropeptides over respective baselines. This study suggests that our experimental design is useful for the study of AVP- and OT-ergic neuron functionality and that BDNF and A II are positive modulators of embryonic hypothalamic cell development.

An adverse endogenous environment during early life predisposes the organism to develop metabolic disorders. We evaluated the impact of intake of an iso-caloric fructose rich diet (FRD) by lactating mothers (LM) on several metabolic functions of their male offspring. On postnatal d 1, ad libitum eating, lactating Sprague-Dawley rats received either 10% F (wt/vol; FRD-LM) or tap water (controls, CTR-LM) to drink throughout lactation. Weaned male offspring were fed ad libitum a normal diet, and body weight (BW) and food intake were registered until experimentation (60 d of age). Basal circulating levels of metabolic markers were evaluated. Both iv glucose tolerance and hypothalamic leptin sensitivity tests were performed. The hypothalamus was dissected for isolation of total RNA and Western blot analysis. Retroperitoneal (RP) adipose tissue was dissected and either kept frozen for gene analysis or digested to isolate adipocytes or for histological studies. FRD rats showed increased BW and decreased hypothalamic sensitivity to exogenous leptin, enhanced food intake (between 49-60 d), and decreased hypothalamic expression of several anorexigenic signals. FRD rats developed increased insulin and leptin peripheral levels and decreased adiponectinemia; although FRD rats normally tolerated glucose excess, it was associated with enhanced insulin secretion. FRD RP adipocytes were enlarged and spontaneously released high leptin, although they were less sensitive to insulin-induced leptin release. Accordingly, RP fat leptin gene expression was high in FRD rats. Excessive fructose consumption by lactating mothers resulted in deep neuroendocrine-metabolic disorders of their male offspring, probably enhancing the susceptibility to develop overweight/obesity during adult life., Facultad de Ciencias Exactas, Facultad de Ciencias Médicas

The aim of this study was to evaluate the effect of ovariectomy on the acute-phase response of inflammatory stress. Ex vivo adrenocortical, peripheral mononuclear cell (PMNC) and adipocyte activities were studied in intact and ovariectomized mice. Endotoxemia was mimicked by intraperitoneal administration of bacterial lipopolysaccharide (LPS; 25 mg per mouse) to sham-operated and 21-day ovariectomized mice. Circulating corticosterone, tumor necrosis factor-α (TNFα) and leptin concentrations were monitored before and 30–120 min after the administration of LPS. Additionally, in vitro experiments were performed with isolated corticoadrenal cells, PMNCs and omental adipocytes from sham-operated and ovariectomized mice incubated with specific secretagogues. The results indicate that while ovariectomy enhanced TNFα secretion after in vivo administration of LPS, it reduced corticoadrenal response and abrogated LPS-elicited leptin secretion into the circulation. While the corticoadrenal sensitivity to ACTH stimulation was reduced by ovariectomy, the LPS-induced PMNC response was not affected. Exogenous leptin enhanced baseline PMNC function regardless of surgery. Finally, ovariectomy drastically reduced in vitro adipocyte functionality. Our data support the notion that ovariectomy modified neuroendocrine-immune-adipocyte axis function and strongly suggest that ovarian activity could play a pivotal role in the development of an adequate immune defense mechanism after injury.

The last decade has seen a proliferation in options for testosterone replacement. However, little is known as to the benefits of different treatment modalities. Our objective was to determine the testosterone prescription pattern and to examine the impact on various outcome measures.A total of 816 adult-onset hypopituitary males on stable pituitary replacement for at least 1 year were identified from the KIMS database. Patients were classified as either eugonadal (n = 106), or hypogonadal (n = 710) on intramuscular (IM, n = 558), oral (n = 74), transdermal (n = 61), and depot (n = 17) testosterone.After 1 year of stable pituitary replacement therapy, body composition, cardiovascular parameters, GH replacement and quality of life were not significantly different in androgen-replaced hypogonadal patients compared to eugonadal patients. There were no differences in outcome variables within the hypogonadal group according to the testosterone replacement regimen used and no difference in response to GH therapy.The majority of hypopituitary patients in the last decade have received IM testosterone. Body composition, cardiovascular parameters, GH replacement and quality of life were not different between eugonadal and hypogonadal patients and were not differentially affected by the mode of testosterone replacement. These findings are reassuring that there is no major difference in response to different testosterone replacement regimens.

Background/Aims: Endocrine features of polycystic ovary syndrome (PCOS) include altered ovarian steroidogenesis, hyperinsulinemia and abnormal luteinizing hormone (LH) secretion. This study was undertaken to further evaluate the role of insulin to modulate LH secretion in lean PCOS patients with normal insulin sensitivity and normal volunteers. Methods: The study was performed in five nonobese patients diagnosed with PCOS on the basis of amenorrhea and a polycystic morphology at ovarian ultrasound, and 5 normal controls in early to mid-follicular phase and matched for weight and age. All subjects were phenotyped, and then admitted for 12 h of frequent (q 10’) blood sampling on two separate occasions, once for a baseline study and the other time for a hyperinsulinemic and euglycemic clamp study. LH was measured in samples obtained throughout each admission in order to perform LH pulse analysis. Results: Baseline LH secretion in PCOS subjects was significantly different from controls: they had higher LH levels, higher LH/FSH ratios as well as a faster LH pulse frequency than normal women. Insulin administration did not affect the pattern of LH secretion of PCOS patients, whereas it significantly increased the LH pulse frequency while decreasing the LH interpulse intervals in the controls. Conclusions: These data confirm that an abnormal pattern of LH secretion characteristic of PCOS can be observed in lean patients, and appears independent of peripheral insulin levels. Furthermore, our results in lean controls provide the first direct evidence that peripheral insulin can modulate the activity of hypothalamic gonadotropin-releasing hormone (GnRH) neurons in the human.

Background Despite the increasing use of Roux-en-Y gastric bypass (RYGBP) in the treatment of morbid obesity, data about postoperative nutritional deficiencies and their treatment remain scarce. Objective The aim of this study was to evaluate the efficacy of a standard multivitamin preparation in the prevention and treatment of nutritional deficiencies in obese patients after RYGBP. Design This was a retrospective study of 2 y of follow-up of obese patients after RYGBP surgery. Between the first and the sixth postoperative months, a standardized multivitamin preparation was prescribed for all patients. Specific requirements for additional substitutive treatments were systematically assessed by a biologic workup at 3, 6, 9, 12, 18, and 24 mo. Results A total of 137 morbidly obese patients (110 women and 27 men) were included. The mean (+/-SD) age at the time of surgery was 39.9 +/- 10.0 y, and the body mass index (in kg/m(2)) was 46.7 +/- 6.5. Three months after RYGBP, 34% of these patients required at least one specific supplement in addition to the multivitamin preparation. At 6 and 24 mo, this proportion increased to 59% and 98%, respectively. Two years after RYGBP, a mean amount of 2.9 +/- 1.4 specific supplements had been prescribed for each patient, including vitamin B-12, iron, calcium + vitamin D, and folic acid. At that time, the mean monthly cost of the substitutive treatment was $34.83. Conclusion Nutritional deficiencies are very common after RYGBP and occur despite supplementation with the standard multivitamin preparation. Therefore, careful postoperative follow-up is indicated to detect and treat those deficiencies.

Carney triad (CT) describes the association of paragangliomas (PGLs) with gastrointestinal stromal tumors (GISTs) and pulmonary chondromas. Inactivating mutations of the mitochondrial complex II succinate dehydrogenase (SDH) enzyme subunits SDHB, SDHC, and SDHD are found in PGLs, gain-of-function mutations of c-kit (KIT), and platelet-derived growth factor receptor A (PDGFRA) in GISTs.Our objective was to investigate the possibility that patients with CT and/or their tumors may harbor mutations of the SDHB, SDHC, SDHD, KIT, and PDGFRA genes and identify any other genetic alterations in CT tumors.Three males and 34 females with CT were studied retrospectively. We sequenced the stated genes and performed comparative genomic hybridization on a total of 41 tumors.No patient had coding sequence mutations of the investigated genes. Comparative genomic hybridization revealed a number of DNA copy number changes: losses dominated among benign lesions, there were an equal number of gains and losses in malignant lesions, and the average number of alterations in malignant tumors was higher compared with benign lesions. The most frequent and greatest contiguous change was 1q12-q21 deletion, a region that harbors the SDHC gene. Another frequent change was loss of 1p. Allelic losses of 1p and 1q were confirmed by fluorescent in situ hybridization and loss-of-heterozygosity studies.We conclude that CT is not due to SDH-inactivating or KIT- and PDGFRA-activating mutations. GISTs and PGLs in CT are associated with chromosome 1 and other changes that appear to participate in tumor progression and point to their common genetic cause.

The oral antidiabetic agent metformin acts at least partially via an activation of AMP-activated kinase (AMPK) in liver and muscle cells. It has appeared recently that hypothalamic AMPK is a key regulator of feeding in mammals. Because metformin also exhibits anorectic effects in animal models as well as in humans, we hypothesized that AMPK may be a target of metformin in hypothalamic neurons. In this study, we show that, in primary cultures of rat hypothalamic neurons, low glucose levels stimulate the phosphorylation of AMPK, thus increasing neuropeptide Y (NPY) gene expression. The addition of metformin in low glucose conditions was found to block AMPK phosphorylation. Consistently, the stimulation of NPY observed in low glucose conditions was also inhibited by the drug. Proopiomelanocortin gene expression measured in parallel was inhibited under low glucose conditions, but in contrast to NPY, it was not dependent upon AMPK and not affected by metformin. Taken together, our data demonstrate that metformin can inhibit AMPK activity in hypothalamic neurons, thus modulating the expression of the orexigenic peptide NPY. These results provide, for the first time, a potential mechanism of action for the anorectic effects of metformin, a widely used drug that could represent a valuable adjunct to novel therapies aimed at modulating central feeding pathways.

Background: Laparoscopic adjustable gastric banding (LAGB) causes significant weight loss in morbidly obese adults. However, its consequences on nutritional status still remain unclear. This study aimed to investigate the effects of LAGB on body composition, metabolic profile and nutritional status in obese, premenopausal women. Methods: 36 obese, premenopausal women (age 24-52 years; mean BMI 43.8 kg/m2) who underwent LAGB were included. Body composition was measured using dual-X-ray absorptiometry at baseline, 6, 12 and 24 months after surgery. Blood pressure, total cholesterol, HDL-cholesterol, triglycerides, glucose, uric acid, total proteins, iron, ferritin, vitamin B12, folic acid, hemoglobin and mean corpuscular volume were measured at baseline, 6, 12, 18 and 24 months after surgery. Results: All patients lost weight over 24 months (range 16.0-71.9 kg): there was a significant loss of fat mass (−51.4%; P

Energy balance exerts a critical influence on reproduction via changes in the circulating levels of hormones such as insulin. This modulation of the neuroendocrine reproductive axis ultimately involves variations in the activity of hypothalamic neurons expressing GnRH. Here we studied the effects of insulin in primary hypothalamic cell cultures as well as a GnRH neuronal cell line that we generated by conditional immortalization of adult hypothalamic neurons. These cells, which represent the first successful conditional immortalization of GnRH neurons, retain many of their mature phenotypic characteristics. In addition, we show that they express the insulin receptor. Consistently, their stimulation with insulin activates both the phosphatidylinositol 3-kinase and the Erk1/2 MAPK signaling pathways and stimulates a rapid increase in the expression of c-fos, demonstrating their responsiveness to this hormone. Further work performed in parallel in immortalized GnRH-expressing cells and primary neuronal cultures containing non-GnRH-expressing neurons shows that insulin induces the expression of GnRH in both models. In primary cultures, inhibition of the Erk1/2 pathway abolishes the stimulation of GnRH expression by insulin, whereas blockade of the phosphatidylinositol 3-kinase pathway has no effect. In conclusion, these data strongly suggest that GnRH neurons are directly sensitive to insulin and implicate for the first time the MAPK Erk1/2 signaling pathway in the central effects of insulin on the neuroendocrine reproductive axis.

Various cytokines produced during the immune reaction can modulate the neuroendocrine reproductive axis, probably by inducing changes in the activity of hypothalamic GnRH neurons. However, the precise cellular and molecular effects of cytokines on these neurons have not been reported yet. To gain a better insight into these regulations, we first examined the pattern of expression of cytokine receptors in a novel neuronal cell line expressing GnRH (Gnv-4 cells). Among others, gp130 is expressed in Gnv-4 cells, together with the ligand receptor subunits specific for IL-6 as well as oncostatin M (OSM). Consistent with the latter observation, we show that OSM stimulates the expression of the immediate early genes c-fos and early growth response-1 in Gnv-4 cells, an effect dependent upon the activation of the MAPK Erk1/2 intracellular signaling pathway. Functional studies performed in parallel in Gnv-4 cells and in primary hypothalamic neuronal cell cultures show that OSM, although devoid of any effect of its own on GnRH gene expression, can inhibit dose-dependently the stimulation of GnRH expression by N-methyl-d-aspartic acid. In conclusion, these data demonstrate that a GnRH-expressing neuronal cell line can be modulated in vitro by cytokines implicated in the regulation of the reproductive axis. Moreover, they provide the first evidence of an involvement of OSM in these regulations.

We report here that PAC1 KO females display decreased fertility, whereas male fertility was normal. ICC on pituitary section showed that FSH, LH, and prolactin synthesis were not affected in KO mice. Moreover, the pituitary-gonadal axis responded properly to an acute fasting test in KO mice. Hence, the phenotype of PAC1 null mice provides clear evidence for the role of PAC1 receptor in reproduction process.

Summary Aim: To determine the long-term prognostic value of SPECT myocardial perfusion imaging (MPI) for the occurrence of cardiovascular events in diabetic patients. Patients, methods: SPECT MPI of 210 consecutive Caucasian diabetic patients were analysed using Kaplan-Meier event-free survival curves and independent predictors were determined by Cox multivariate analyses. Results: Follow-up was complete in 200 (95%) patients with a median period of 3.0 years (0.8-5.0). The population was composed of 114 (57%) men, age 65 ±10 years, 181 (90.5%) type 2 diabetes mellitus, 50 (25%) with a history of coronary artery disease (CAD) and 98 (49%) presenting chest pain prior to MPI. The prevalence of abnormal MPI was 58%. Patients with a normal MPI had neither cardiac death, nor myocardial infarction, independently of a history of coronary artery disease or chest pain. Among the independent predictors of cardiac death and myocardial infarction, the strongest was abnormal MPI (p 5-fold increase in cardiovascular events. This emphasizes the value of SPECT MPI in predicting and risk-stratifying cardiovascular events in diabetic patients.

Background: Inactivating mutations of DAX-1 give rise to the X-linked form of adrenal hypoplasia congenita (AHC). Affected fetuses are at risk of early postnatal Addisonian crisis, but the variable phenotypic expression of DAX-1 insufficiency renders this diagnosis challenging. Methods: We describe the familial transmission of AHC over several generations. The proband was diagnosed with adrenal insufficiency at age 3.5 years: molecular analysis revealed a novel, 373-bp deletion including the second exon of DAX-1. Given the familial history of several unexplained deaths in male infants related to the proband via his maternal great-grandmother, we hypothesized that all these boys had been affected with AHC. Another female member of the family being pregnant with a male fetus at the time, we performed DAX-1 analysis on the mother and the newborn. The mother was heterozygous for the deletion, and the newborn hemizygous: he presented an adrenal crisis at 10 days of life, and is now doing well on hormone replacement therapy. Conclusion: The unfortunate deaths of male infants at each generation of this family underlie the importance of early and precise diagnosis of this rare condition, stressing the value of genetic diagnosis in six potential female carriers of this family entering their reproductive years.

It has been proposed that ghrelin induces food intake by a mechanism due to the stimulation of hypothalamic NPY-ergic activity. It is recognized that bilateral adrenalectomy (ADX) enhances hypothalamic CRH-ergic function and reduces appetite. Thus, the aim of the present study was to test whether, icv-administered, ghrelin modulates NPY- and CRH-ergic functions after food restriction (FR) and glucocorticoid deprivation. For this purpose, 1 microg ghrelin was administered icv to ad libitum (AL) eating and to corticosterone (B)-depleted (ADX) and -replete (sham and ADX+B) male animals habituated, for 15 d, to FR. Food intake, hypothalamic function, and peripheral ghrelin, ACTH, and B concentrations were evaluated 2 h after ghrelin administration. Results indicate that while icv ghrelin treatment stimulated 2-h food intake in AL rats, it failed to do so in sham- and ADX+B-FR animals; moreover, 2-h food intake was inhibited by icv ghrelin treatment in ADX-FR rats. Regarding peripheral hormone levels: (a) basal circulating ghrelin levels, already enhanced (vs AL rats) by FR, significantly increased 2 h after icv ghrelin treatment in AL and sham-FR rats; (b) central ghrelin treatment stimulated ACTH secretion in circulation of AL and glucocorticoid-replete-FR rats; and (c) B circulating levels remained unchanged after ghrelin treatment, although they were in relation to the food intake condition of rats. Finally, hypothalamic NPY mRNA expression was enhanced by FR and, in response to icv ghrelin treatment, it decreased in ADX-FR rats only. ADX-enhanced hypothalamic CRH mRNA levels were reduced by ghrelin icv administration only when animals received B replacement therapy. Our data indicate an inhibitory effect of hypothalamic ghrelin on NPY-ergic activity in FR rats lacking endogenous glucocorticoid.

The plasma levels of either brain natriuretic peptide (BNP) or the N-terminal fragment of the prohormone (NT-proBNP) have recently gained extreme importance as markers of myocardial dysfunction. Patients with type 2 diabetes are at high risk of developing cardiovascular complications. This study was aimed to assess whether plasma NT-proBNP levels are at similar levels in type 2 diabetics with or without overt cardiovascular diseases.We assayed plasma NT-proBNP in 54 type 2 diabetics, 27 of whom had no overt macro- and/or microvascular complications, while the remaining ones had either or both. The same assay was carried out in 38 healthy control subjects age and sex matched as a group with the diabetics.Plasma NT-proBNP was higher in diabetics (median 121 pg/ml, interquartile range 50-240 pg/ml, ) than in those without complications (37 pg/ml, 21-54 pg/ml, P0.01). Compared with the controls (55 pg/ml, 40-79 pg/ml), only diabetics with vascular complications had significantly increased plasma NT-proBNP levels (P0.001). In the diabetics, coronary heart disease and nephropathy (defined according to urinary excretion of albumin) were each independently associated with elevated values of plasma NT-proBNP.In type 2 diabetes mellitus, patients with macro- and/or micro-vascular complications exhibit an elevation of plasma NT-proBNP levels compared to corresponding patients with no evidence of vascular disease. The excessive secretion of this peptide is independently associated with coronary artery disease and overt nephropathy. The measurement of circulating NT-proBNP concentration may therefore be useful to screen for the presence of macro- and/or microvascular disease.

Background: During the last 5 years, the performance of bariatric operations has doubled via our outpatient obesity clinic. Currently, 52% of the patients presenting for weight loss are interested in bariatric surgery. Gastric banding and Roux-en-Y gastric bypass are the two laparoscopic procedures proposed. The aim of this study was to evaluate the impact of preoperative teaching on the patients' surgical option. Methods: All the candidates for bariatric surgery were submitted to preoperative teaching and those between February 2001 and December 2002 are the subject of this study. The teaching consisted of 3 weekly interactive 2-hour sessions. During the first session, the patients were asked about the type of operation that they had in mind: gastric banding, gastric bypass, or not yet decided. The same questions were repeated at the end of the third session, with an additional possible answer: no surgery. Results: 297 consecutive patients with a BMI >35 kg/m2 with at least one severe co-morbidity, were submitted to preoperative teaching. 80% of the patients were women. Median age was 41 years. Before teaching, 68 patients (23%) were uncertain, 100 (34%) favored gastric banding, and 129 (43%) wanted a gastric bypass. After education, only 3 patients (1%) remained uncertain, 45 (15%) changed their surgical option, and 27 (9%) declined surgery. The proportion of patients opting for gastric banding decreased from 34% to 20%, whereas those electing bypass increased from 43% to 70%. Conclusions: Preoperative training provides an informed and better patient selection for bariatric surgery. It helps the patients understand the various surgical options, and makes their decision easier.

Methods: The aim of this study was to detect predictive factors of binge eating disorder (BED) in an out-patient obesity clinic. Eating behaviour, weight history and body composition were assessed in 138 consecutive patients. BED was diagnosed according to the criteria of appendix B of the Diagnostic and Statistical Manual of Mental Disorders. Results: The body mass index (BMI; p

The adipose tissue is playing an important role in the development of human obesity and its related comorbidities, but little is known about the mechanisms governing its differentiation and proliferation. In this work, we studied the expression of transcription factors involved in fat storage and metabolic regulations in adipose tissue of 50 well-characterized obese women. In multivariate analyses, 80% of c enhancer binding protein alpha (cEBP alpha), c and a sterol regulatory element binding protein 1 (c and a SREBP1), and retinoid X receptor (RXR alpha) levels in sc adipose tissue (SAT) could be explained by other transcription factors. In addition, RXR alpha was the major determinant of peroxisome proliferator and activated receptor-gamma 1 variability in SAT, with the two factors being involved in the determination of the variability of insulin resistance. In contrast, the levels of all these transcription factors, together with various phenotypic and biological characteristics of the patients, seemed to participate only marginally in the regulation of visceral adipose tissue activity. In similar multivariate analyses, they could explain only a minor part of the variability of cEBP alpha, c and a SREBP1, or RXR alpha, suggesting the involvement of other regulators. Overall, our results demonstrate a different regulation of visceral adipose tissue and SAT and a different role of both tissues in insulin resistance and lipid storage.

In October 2002, a workshop was held in Ancona, Italy, to reach a Consensus on the management of Cushing's syndrome. The workshop was organized by the University of Ancona and sponsored by the Pituitary Society, the European Neuroendocrine Association, and the Italian Society of Endocrinology. Invited international participants included almost 50 leading endocrinologists with specific expertise in the management of Cushing's syndrome. The consensus statement on diagnostic criteria and the diagnosis and treatment of complications of this syndrome reached at the workshop is hereby summarized.

BACKGROUND: The authors analyzed the trends in anthropometric and behavioral characteristics among patients seeking weight loss and the trends in choice of treatments, between 1997 and 2001 in an outpatient obesity clinic. PATIENTS AND METHODS: 138 and 128 consecutive patients attending the out-patient obesity clinic at University Hospital of Lausanne were screened in 1997 and in 2001 respectively. Eating habits, body composition and treatment used were assessed. RESULTS: Median BMI was 35 kg/m2 in 1997 and 38 kg/m2 in 2001 (P

Insulin and leptin are peripheral metabolic factors signaling the body needs in energy to the central nervous system. Because energy homeostasis and reproductive function are closely related phenomena, we investigated the respective roles played by insulin and leptin in the hypothalamic control of GnRH secretion. We observed that increasing circulating insulin levels, by performing hyperinsulinemic clamp studies in male mice, was associated with a significant rise in LH secretion. This effect of insulin is likely mediated at the hypothalamic level, because it was also found to stimulate the secretion and the expression of GnRH by hypothalamic neurons in culture. Leptin was found to potentiate the effect of insulin on GnRH secretion in vitro but was devoid of any effect on its own. These data represent the first evidence of direct insulin sensing by hypothalamic neurons involved in activating the neuroendocrine gonadotrope axis. They also demonstrate that these neurons can integrate different hormonal signals to modulate net hypothalamic GnRH output. We propose that such integration is an essential mechanism for the adaptation of reproductive function to changes in the metabolic status of an individual.

Data regarding the expression of peroxisome proliferator-activated receptor (PPAR)-γ1 and PPAR-γ2 in human visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) are conflicting. To clarify this issue, we studied 50 women who had a BMI >35 kg/m2 were undergoing gastric reduction surgery. Phenotyping included recording of anthropometric parameters and of a biological profile. Quantification of the expression of PPAR-γ1 and PPAR-γ2 in samples of VAT and SAT was performed by real-time RT-PCR. In both SAT and VAT, the level of expression of PPAR-γ2 were >20-fold that of PPAR-γ1 (P < 0.001 for both). However, only PPAR-γ1 was differentially expressed, its levels in SAT being 216 ± 34% those in VAT (P < 0.001). In a stepwise, multivariate regression analysis, the levels of PPAR-γ1 in both SAT and VAT were the major determinants of waist circumference (R2 = 21% for both; P < 0.01). Finally, leptin but not PPARs appeared as the single parameter explaining the largest part of the variability of BMI in our cohort of patients (R2 = 22%, P < 0.001). These results are consistent with the putative roles of PPAR-γ1 and PPAR-γ2 in carbohydrate metabolism and energy homeostasis, respectively. As such, they constitute an important step toward the identification of potential targets for novel therapeutic strategies in the fields of obesity.

OBJECTIVE: Functioning or non-functioning ectopic tumors may develop from pharyngeal pituitary remnants. They constitute

Les systemes immunitaire et endocrinien sont relies par un reseau d’interactions bidirectionnelles qui, d’une part, permettent aux hormones de moduler les fonctions immunologiques et, d’autre part, permettent au systeme immunitaire de produire des effets neuroendocriniens. Ainsi, des hormones tels les glucocorticoides, la corticoliberine (CRH), l’hormone de croissance, la prolactine et la somatostatine, sont des modulateurs de reponses immunitaires et inflammatoires, alors que les cytokines modulent la fonction des axes corticotrope, gonadotrope, thyreotrope et somatotrope. Ces interactions immuno-neuroendocriniennes sont donc impliquees dans de nombreuses situations physiologiques et physiopathologiques. Elles jouent ainsi un role dans l'hypogonadisme, l’hypothyroidie et l’arret de croissance qui surviennent lors de maladies infectieuses ou inflammatoires. Quant aux interactions avec l’axe hypothalamo-hypo- physo-surrenalien, elles permettent de controler la reponse inflammatoire afin d’eviter qu'une exageration de cette reponse ne mette en danger l’integrite de l’organisme.

Estradiol has been implicated in the regulation of food intake; however, its effect seems to be exerted in a bimodal fashion. We examined whether a single im injection of estradiol valerate (E2V), lastingly effective, could induce changes in parametrial fat function that further induce a new set point of leptin sensitivity in the female rat. E2V induced severe anorexia and loss of body weight between d 4 and 12 posttreatment. E2V rats recovered normal food intake and departing body weights on wk 2 and 3 posttreatment, respectively; however, they did not reach body weights of control rats. On d 61 posttreatment, we found that unfasting E2V, vs control, rats displayed increased E2 and leptin circulating levels; reduced plasma tumor necrosis factor-alpha(TNF-alpha) concentrations; similar circulating levels of glucose, insulin, and triglyceride; and lower parametrial fat mass containing a higher number of adipocytes that, although normal in size, in vitro released more leptin. Metabolic responses to fasting indicated that unlike control animals, E2V rats did not decrease triglyceride circulating levels, and that both groups decreased plasma glucose, leptin, and insulin, but not TNF-alpha, levels. High glucose load experiments indicated that E2V animals displayed a better insulin sensitivity than control rats; did not significantly increase circulating leptin concentrations as control rats did; and, unlike control, significantly decreased plasma triglyceride levels. Our data strongly support a potent acute anorectic effect of E2 and that, after several weeks, E2 modified parametrial fat function and insulin sensitivity, protecting the organism against future unfavorable metabolic conditions., Instituto Multidisciplinario de Biología Celular

We explored whether testosterone influences circulating leptin turnover in rats. Sham-operated male and female rats and 21-d gonadectomized rats treated or not treated with testosterone propionate were used. Anesthetized rats were implanted with an iv catheter, and then blood samples were drawn before and throughout a 60-min period following systemic leptin administration. Plasma testosterone, estradiol, and leptin concentrations were monitored. The results indicated that while gonadectomy blunted circulating concentrations of the homologous sex steroid, testosterone therapy, in gonadectomized rats, restored plasma testosterone concentrations to values found in normal male rats. Pharmacokinetic parameters evaluated during the test indicated the following: First, in the overall pharmacokinetic analyses, testosterone therapy in gonadectomized rats induced a more rapid disappearance of leptin from the circulation. Second, orchidectomy significantly enhanced the area under the curve (AUC) of circulating leptin, an effect fully reversed by testosterone treatment. Third, testosterone treatment in ovariectomized rats significantly decreased the AUC of leptin concentrations. Fourth, while gonadectomy alone did not modify circulating leptin half-life, conversely, testosterone therapy in gonadectomized rats decreased leptin half-life in the circulation. Finally, while orchidectomy reduced leptin body clearance, this parameter was increased by androgen therapy in gonadectomized rats. Our results strongly support that testosterone could play a main role in plasma leptin turnover by increasing leptin clearance rate and shortening plasma leptin half-life.

To date, there are no vasopressin (VP) agonists that exhibit a high affinity and selectivity for the VP V1b receptor with respect to the V1a, V2, and oxytocin receptors. In this study, we describe the synthesis and pharmacological properties of [1-deamino-4-cyclohexylalanine] arginine vasopressin (d[Cha4]AVP). Binding experiments performed on various membrane preparations revealed that d[Cha(4)]AVP exhibits a nanomolar affinity for V1b receptors from various mammalian species (rat, bovine, human). It exhibits high V1b/V1a and V1b/oxytocin selectivity for rat, human, and bovine receptors. Furthermore, it exhibits high V1b/V2 specificity for both bovine and human vasopressin receptors. Functional studies performed on biological models that naturally express V1b receptors indicate that d[Cha4]AVP is an agonist. Like VP, it stimulated basal and corticotropin-releasing factor-stimulated ACTH secretion and basal catecholamine release from rat anterior pituitary and bovine chromaffin cells, respectively. In vivo experiments performed in rat revealed that d[Cha4]AVP was able to stimulate both ACTH and corticosterone secretion and exhibits negligible vasopressor activity. It retains about 30% of the antidiuretic activity of VP. This long-sought selective VP V1b receptor ligand with nanomolar affinity will allow a better understanding of V1b-mediated VP physiological effects and is a promising new tool for V1b receptor structure-function studies.

DAX-1 [dosage-sensitive sex reversal, adrenal hypoplasia congenital (AHC) critical region on the X chromosome, gene 1] is a transcription factor expressed in the adrenal gland and at all levels of the gonadotrope axis. Inactivating mutations of DAX1 result in the X-linked form of AHC with associated hypogonadotropic hypogonadism. AHC usually reveals itself as adrenal failure in early infancy, although a wide range of phenotypic expression has been reported. We describe a patient who was diagnosed with adrenal failure at 6 wk of age, but who experienced recovery of adrenal function of several months' duration later in infancy. He subsequently failed to undergo puberty because of hypogonadotropic hypogonadism of pituitary origin, and he was also diagnosed with schizophrenia in early adulthood. Molecular genetic analyses revealed a complex rearrangement in DAX1, including a 2.2-kb deletion spanning the entire second exon and a small 27-bp insertion. The putative protein encoded by this mutated gene is 429 amino acids long. The initial 389 residues probably correspond to the wild-type DAX-1 sequence, whereas the last 40 amino acids are presumably completely unrelated, being transcribed from the intronic sequence adjacent to exon 1. In vitro functional analyses confirm the absence of repressor activity exerted by such mutant protein. These studies expand the genotypic and phenotypic spectrum of DAX-1 insufficiency in humans.

Marked changes in thyroid function occur during puberty as an adaptation to body and sexual development. Characteristics of thyroid growth were investigated in 259 healthy adolescents (110 girls and 149 boys), aged 11–17 yr, in an urban area of Switzerland with sufficient iodine supply. The thyroid volume determined by ultrasonography was correlated with chronological age, body weight, body height, cervical circumference, body mass index, and body surface area (BSA). Iodide concentration was measured in urine. The increase in thyroid volume mainly occurred between 11–15 yr (age at maximum thyroid growth rate, 12.5 yr) and was best correlated with BSA in both genders (girls, r2 = 0.38; boys, r2 = 0.49). The BSA-related thyroid growth was almost constant throughout puberty in boys and similar in girls up to menarche, but 14.5% larger in girls after menarche (P < 0.01). Percentiles of thyroid volume were lower than WHO reference values despite low normal urinary iodide concentration (median, 0.75 μmol/L). Th...

Aims/hypothesis. Paraoxonase is a member of a multigene family of three genes. Paraoxonase2 gene polymorphisms have been associated with coronary heart disease in non-diabetic patients and with an increased fasting glycaemia in patients with Type II (non-insulin-dependent) diabetes mellitus. We tested the hypothesis of whether paraoxonase1 and paraoxonase2 polymorphisms were associated with diabetic nephropathy.¶Methods. Our case-control study of 299 Swiss patients with Type II diabetes included 147 patients with confirmed diabetic nephropathy.¶Results. In univariate analyses the two paraoxonase2 polymorphisms were associated with diabetic nephropathy. When subjected to multivariate analyses, both paraoxonase2 polymorphisms remained statistically associated with diabetic nephropathy independent of traditional risk factors (paraoxonase2–148: OR = 2.53, p = 0.003; paraoxonase2–311: OR = 2.67, p = 0.002). In addition, BMI interacted with paraoxonase2 polymorphisms as a risk factor of nephropathy.¶Conclusions/interpretation. The paraoxonase2 gene polymorphisms were significantly associated with diabetic nephropathy independent of traditional risk factors in Type II diabetic patients. The susceptibility to diabetic nephropathy was intensified by the degree of obesity. Pathophysiological pathways should be investigated and could be involved in insulin resistance or lipids metabolism or both. [Diabetologia (2001) 44: 104–107]

Leptin, the product of the obesity gene, is a cytokine-like circulating protein acting as a peripheral satiety signal to the hypothalamus. It was initially described as a secreted product of white adipose cells, but more recent data have demonstrated its expression by endocrine and neuroendocrine tissues like the ovary and the hypothalamus, as well as several anterior pituitary cell types. The effects of leptin on body weight homeostasis are mediated via different hypothalamic neurotransmitters regulating appetite and energy expenditure. In addition, leptin participates to the modulation of the activity of the neuroendocrine thyrotrope, somatotrope, corticotrope and gonadotrope axes. These endocrine effects of leptin have progressively emerged as important physiological functions of this molecule. Its role as a permissive factor for puberty and normal reproductive function in adulthood is becoming widely recognized. In addition, leptin participates in the fine tuning of the corticotrope axis. Thus, by signalling body fat stores to the hypothalamus and other endocrine organs, leptin serves as a metabolic integrator of several neuroendocrine functions. The precise site of action and mode of regulation of the gonadotrope and somatotrope axes by leptin are reviewed.

The present study was designed to assess the effect of maternal undernutrition, during gestation and lactation, on the neuroendocrine [hypothalamo-pituitary-adrenal (HPA)]-immune axis response to endotoxin (LPS) administration. For this purpose, 21-day-old male rats from both well-nourished (WN) and undernourished (UN) mothers were examined 2 h after injection (i.p.) of vehicle alone (VEH) or containing LPS (130 µg/kg BW). Circulating levels of glucose (GLU), ACTH, corticosterone (B), tumor necrosis factor-alpha (TNFα) and leptin were explored. The results indicate that: (a) mother body weight was significantly (p < 0.05) reduced, as a consequence of UN, at the second and third weeks of pregnancy; (b) no differences in basal glycemia were found in the two groups of pups, and LPS treatment did not induce hypoglycemia, in either group; (c) basal plasma ACTH, B and TNFα levels were similar in the two groups, and LPS-induced ACTH, B and TNFα secretions, although severalfold higher than respective VEH values (p < 0.05) in pups from WN mothers, were fully (ACTH and B) and partially (TNFα) abolished in products from UN mothers; (d) both mean body weights and basal plasma leptin levels were significantly (p < 0.05) lower in pups from UN than from WN mothers, and LPS administration did not modify plasma leptin values in products from both groups. In addition, results of dispersed total adrenal cells incubated in vitro indicate that: (a) both basal and ACTH (22 pM)-induced B secretion were significantly (p < 0.05) lower in cells from UN than WN pups, and (b) leptin (100 nM) was able to inhibit partially ACTH-stimulated B output by adrenal gland (AG) cells from WN pups; however, it failed to inhibit ACTH-stimulated glucocorticoid release by AG cells from UN pups. The present results indicate that undernutrition in mothers, during the very critical periods of gestation and lactation, induces in their male pups at weaning: (a) reduced circulating leptin levels and body weight values; (b) metabolic adaptation to normal carbohydrate metabolism; (c) hyporesponsiveness of the HPA and immune (TNFα) axes during endotoxemia, and (d) leptin resistance at the adrenocortical level. This study strongly supports that undernutrition of mothers results in neuroendocrine immune dysfunction of their pups; however, adrenal resistance to the inhibitory effect of leptin on glucocorticoid output is developed, probably as an adaptive mechanism to counteract unfavorable metabolic conditions.

In this study, we describe a patient with a phenotype of complete hypogonadotropic hypogonadism who presented primary failure of pulsatile GnRH therapy, but responded to exogenous gonadotropin administration. This patient bore a novel point mutation (T for A) at codon 168 of the gene encoding the GnRH receptor (GnRH-R), resulting in a serine to arginine change in the fourth transmembrane domain of the receptor. This novel mutation was present in the homozygous state in the patient, whereas it was in the heterozygous state in both phenotypically normal parents. When introduced into the complementary DNA coding for the GnRH-R, this mutation resulted in the complete loss of the receptor-mediated signaling response to GnRH. In conclusion, we report the first mutation of the GnRH-R gene that can induce a total loss of function of this receptor and is associated with a phenotype of complete hypogonadotropic hypogonadism.

Changes in corticotropin (ACTH) and glucocorticoid secretion have been described during disturbances of body fluid homeostasis and attributed to alterations in arginine vasopressin (AVP) secretion from magnocellular hypothalamic neurons. In order to further characterize the mechanisms involved in the interactions between body fluid alterations and pituitary adrenal function, we manipulated osmolality and volemia in sheep under stimulation of the pituitary-adrenal axis by acute injection of endotoxin. We have recently shown that endotoxin injection induces a long-lasting release of both corticotropin releasing hormone (CRH) and AVP into hypophysial portal blood, and an early stimulation of AVP secretion into peripheral vessels, thus suggesting a joint activation of magnocellular and parvocellular neurons of the PVN. We used the same experimental model to investigate the effect of combined volume loading and plasma dilution (achieved by 1-deamino-8-D-arginine (dDAVP) administration together with infusion of 2 liters of 2.5% glucose solution) on CRH, AVP, ACTH and cortisol responses to endotoxin stimulation. In volume-loaded animals, ACTH and cortisol responses to endotoxin were significantly blunted and we observed a parallel decrease in portal CRH and jugular and portal AVP levels. These data show that hypoosmolality and/or hypervolemia reduce(s) ACTH and cortisol response to stress in sheep as in other species. They strongly suggest that this reduction in ACTH and cortisol responses to endotoxin involve not only magnocellular hypothalamic neurons secreting AVP, as usually assumed, but also PVN parvocellular neurons secreting both CRH and AVP.

The present study was designed to determine whether the glucocorticoid inhibitory feedback mechanism plays a role in the well-known tolerance of the neuroendocrine-immune axis response to repeated endotoxemia. Adult male rats underwent adrenalectomy (ADX) and were implanted with a subcutaneous corticosterone (compound B, CB, 75 mg) pellet, or sham operated and implanted with a placebo pellet. On the morning of day 8 after surgery (experimental day, D1), all rats received an intravenous injection of lipopolysaccharide (LPS) (25 µg/kg body weight) which was repeated daily until D5. Blood was drawn via intravenous indwelling catheters before (sample time zero) as well as 1, 2, 3 and 4 h after LPS treatment on D1, 3 and 5 for measurements of corticotropin (ACTH), CB, tumor necrosis factor-α (TNF-α) and leptin. In sham animals, tolerance to repeated LPS administration was complete by D5 for the corticotrope axis and the immune response. In addition, LPS was found to stimulate leptin secretion on day 1 in intact rats, an effect that also disappeared thereafter. ADX + CB rats showed only a partial tolerance of the corticotrope axis on D5, whereas tolerance of the immune response was similar to that found in sham animals. Interestingly, the acute stimulation of leptin secretion by LPS in ADX + CB rats was qualitatively similar to that of intact controls on D1, but plasma leptin levels were significantly reduced on D3 and 5 compared to controls. Our results demonstrate that the adrenal response tolerance of the hypothalamo-pituitary-adrenal axis to repeated endotoxemia. In addition, our finding that TNF-α secretion follows the same pattern in sham-operated and in adrenalectomized animals suggests that unlike the corticotrope axis, tolerance of the immune response does not depend upon stimulated CB levels. The decrease in circulating levels of leptin following ADX is consistent with the stimulatory effects of glucocorticoids on leptin secretion. However, our finding of an acute stimulation of leptin secretion by LPS in ADX + CB animals demonstrates that this effect of endotoxemia is at least partially glucocorticoid independent.

Different interactions have been described between glucocorticoids and the product of the ob gene leptin. Leptin can inhibit the activation of the hypothalamo-pituitary-adrenal axis by stressful stimuli, whereas adrenal glucocorticoids stimulate leptin production by the adipocyte. The present study was designed to investigate the potential direct effects of leptin to modulate glucocorticoid production by the adrenal. Human adrenal glands from kidney transplant donors were dissociated, and isolated primary cells were studied in vitro. These cells were preincubated with recombinant leptin (10(-10)-10(-7) M) for 6 or 24 h, and basal or ACTH-stimulated cortisol secretion was subsequently measured. Basal cortisol secretion was unaffected by leptin, but a significant and dose-dependent inhibition of ACTH-stimulated cortisol secretion was observed [down by 29 +/- 0.1% of controls with the highest leptin dose, P < 0.01 vs. CT (unrelated positive control)]. This effect of leptin was also observed in rat primary adrenocortical cells, where leptin inhibited stimulated corticosterone secretion in a dose-dependent manner (down by 46 +/- 0.1% of controls with the highest leptin dose, P < 0.001 vs. CT). These effects of leptin in adrenal cells are likely mediated by the long isoform of the leptin receptor (OB-R), because its transcript was found to be expressed in the adrenal tissue and leptin had no inhibitory effect in adrenal glands obtained from db/db mice. Therefore, leptin inhibits directly stimulated cortisol secretion from human and rat adrenal glands, and this may represent an important mechanism to modulate glucocorticoid levels in various metabolic states.

It is well established that sexual dimorphism exits within the immune system. Females have higher levels of immunoglobulins, greater antibody response to antigens, and higher incidence of autoimmune diseases, such as systemic lupus erythematosus, Grave’s disease, and Hashimoto thyroiditis than males. Spontaneous autoimmune syndromes in mice are more prevalent and of greater severity in females compared with males, and the course of the disease can be modulated by changes in levels of gonadal steroids. A sexual dimorphism is also present in the pituitary-adrenal function: females have higher corticosterone levels and higher corticosteroidogenesis. In the context of the immune-neuroendocrine interactions, we investigated the effects of gonadectomy and sex hormone therapy on endotoxin-stimulated hypothalamo-pituitary-adrenal axis. Whereas endotoxin-induced corticosterone release is invariable throughout the different stages of the oestrus cycle, gonadectomy in both male and female mice leads to enhanced adrenal and immune responses to endotoxin. Interestingly, these enhanced adrenal and immune responses can be completely reversed by testosterone treatment regardless of the sex of the mice. Studies performed over development confirm the role of endogenous testosterone in modulating the endotoxin-induced corticosterone secretion. Indeed, corticosterone response to endotoxin is maximal before puberty when endogenous testosterone levels are low and declines in postpubertal and adult mice. In conclusion, all these data support a sex steroid hormone basis for a neuroendocrine-immunologic sexual dimorphism.

We have previously shown that hexarelin, a novel GH-releasing peptide (GHRP), is able to elicit GH release when administered i.v., s.c. or by mouth and that it is a more potent GH secretagogue than GHRP-6. In the current study, we investigated the effects of hexarelin administered as repeated doses at 2 h intervals or as a continuous 6, 30 or 174 h infusion to conscious male rats. In the first experiment, adult male Sprague-Dawley rats were prepared with dual indwelling jugular catheters. On the day of experimentation, these animals received three 25 micrograms/kg i.v. boluses of hexarelin at 2 h intervals with blood sampling at 5, 10, 15, 30, 60, 90 and 120 min after each dose. The mean peak GH response and the mean area under the GH response curve (AUC) for the 30 min after each administration were calculated and are reported as the mean +/- S.E.M. For both the peak and AUC results there was a significant (P < 0.05) difference in the GH response noted between the first (peak 301 +/- 37 ng/ml; AUC 5585 +/- 700 ng/ml per 30 min) and second (peak 149 +/- 47 ng/ml; AUC 3056 +/- 908 ng/ml per 30 min) injections of hexarelin, but not between the first and third (peak 214 +/- 49 ng/ml; AUC 3862 +/- 844 ng/ml per 30 min). In a second series of experiments, adult male Sprague-Dawley rats received continuous infusions (100 micrograms/h) of hexarelin or saline (1 ml/h) for 6, 30 or 174 h. Blood samples were collected every 20 min for the duration of the 6 h infusion and for the last 6 h of the two longer hexarelin infusions. Plasma GH concentrations peaked within 40 min of the initiation of infusion, but soon returned to basal levels. Mean plasma GH concentrations did not differ between any of the treatment groups, nor did any of the parameters of pulsatile hormone release analyzed. No significant differences in plasma corticosterone concentrations were noted between any of the treatment groups. On the other hand, while neither the 6 h (941 +/- 70 ng/ml) nor the 30 h (954 +/- 70 ng/ml) hexarelin infusions resulted in a significant increase in the plasma IGF-I concentrations over those noted in the saline controls (935 +/- 65 ng/ml), a 174 h hexarelin infusion did elicit a significant increase (1289 +/- 42 ng/ml; P < 0.05). Thus it appears that, while continuous exposure to hexarelin does not disrupt normal GH cycling, it may (after up to 174 h of exposure) alter other components of the growth axis. In addition, since the character of pulsatile GH release remained unaltered in response to the hexarelin infusion, it appears that this GHRP may not act by suppression of functional somatostatin tone as has been suggested previously.

Cytokines are important partners in the bidirectional network interrelating the immune and the neuroendocrine systems. These substances and their specific receptors, initially thought to be exclusively present in the immune system, have recently been shown to be also expressed in the neuroendocrine system. Cytokines can modulate the responses of all endocrine axes by acting at both the central and the peripheral levels. To explain how systemic cytokines may gain access to the brain, several mechanisms have been proposed, including an active transport through the blood-brain barrier, a passage at the circumventricular organ level, as well as a neuronal pathway through the vagal nerve. The immune-neuroendocrine interactions are involved in numerous physiological and pathophysiological conditions and seem to play an important role to maintain homeostasis.

Summary: Neuropeptide Y in the hypothalamus is a potent physiological stimulator of feeding, and may contribute to the characteristic metabolic defects of obesity when hypothalamic levels remain chronically elevated. Since corticosterone and insulin are important regulators of fuel metabolism, the longitudinal effects of chronic (6 days) intracerebroventricular infusion of neuropeptide Y in normal rats on the hypothalamo-pituitary-adrenal axis and on insulin secretion were studied. Neuropeptide Y-infused rats were either allowed to eat ad libitum, or were pair-fed with normophagic control rats. Neuropeptide Y increased the basal plasma concentrations of adrenocorticotropic hormone and corticosterone during the first 2 days of its intracerebroventricular infusion and increased cold stress-induced plasma adrenocorticotropic hormone concentrations. After 4-6 days of central neuropeptide Y infusion, however, basal plasma adrenocorticotropic hormone and corticosterone concentrations were no different from control values (except in ad libitum-fed rats in which corticosteronaemia remained elevated), they were unaffected by the stress of cold exposure, and the hypothalamic content of corticotropin-releasing factor immunoreactivity was significantly decreased. A state of hyperinsulinaemia was present throughout the 6 days of intracerebroventricular neuropeptide Y infusion, being more marked in the ad libitum-fed than in the pair-fed group. The proportions of insulin, proinsulin, and conversion intermediates in plasma and pancreas were unchanged. Hyperinsulinaemia of the pair-fed neuropeptide Y-infused rats was accompanied by muscle insulin resistance and white adipose tissue insulin hyperresponsiveness, as assessed by the in vivo uptake of 2-deoxyglucose. Finally, bilateral subdiaphragmatic vagotomy prevented both the basal and the marked glucose-induced hyperinsulinaemia of animals chronically infused with neuropeptide Y, demonstrating that central neuropeptide Y-induced hyperinsulinaemia is mediated by the parasympathetic nervous system

Glucocorticoids play a critical role in the regulation of the hypothalamic-somatotropic-insulin-like growth factor axis. These steroids enhance growth hormone gene transcription and increase growth hormone-releasing hormone receptor synthesis. However, glucocorticoid excess inhibits somatic growth. Evidence to date suggests that this is in part due to impaired growth hormone secretion observed during hypercortisolism as well as impaired actions of growth hormone at the peripheral level. This includes impaired spontaneous growth hormone secretion, suppressed growth hormone responses to a number of stimuli, including growth hormone-releasing hormone, and increased insulin-like growth factor inhibitors and binding proteins. The inhibitory effect of the glucocorticoids appears to be due to increased hypothalamic somatostatin tone and inhibition of insulin-like growth factor bioactivity.

Hypothalamic neuropeptide Y (NPY) plays a central role in the control of food intake, energy balance, and modulation of neuroendocrine functions. In particular, an increase in NPY expression participates in the inhibition of the reproductive activity under poor nutritional conditions. The present study was designed to evaluate further the involvement of the Y1 subtype of NPY receptors in these effects. Food intake, body weight gain, and the onset of puberty were studied in groups of wild-type and Y1 deficient mice that were either fed ad libitum or subjected to a 30% restriction in food intake. This moderate feeding restriction induced a similar deficit in body weight gain in wild-type and in Y1 knockout mice. However, although wild-type mice experienced the expected delay of puberty, all mice in the food restriction group and lacking Y1 could go through puberty over the time of the experiment despite decreases in circulating leptin levels and increases in hypothalamic NPY expression. This observation demonstrates that the absence of Y1 impairs the perception of decreasing energy stores by the gonadotrope axis, demonstrating a physiological role for Y1 in the sensing of endogenous metabolic parameters by the hypothalamus.

Bidirectional interactions between the immune system and the hypothalamo-pituitary-adrenal (HPA) axis may represent an important mechanism that prevents overexuberant immune responses. In this network, cytokines play an important role in modulating the HPA axis response at all three levels: the hypothalamus, the pituitary gland, and the adrenals. Acute effects of cytokines are produced at the hypothalamic level by altered release of hypophysiotropic hormones, whereas pituitary and adrenal actions are slower but probably more important in response to prolonged release of cytokines, as it occurs in infection or inflammation. Further studies are needed to determine the precise mechanism through which circulating cytokines affect the HPA axis function within the central nervous system and to evaluate the relevance of these interactions in physiologic and pathophysiologic situations in humans.