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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thyrotropin releasing hormone (TRH) administration is known to induce a greater TSH response in normal subjects than in obese subjects. In obesity even GH and PRL response to various stimuli are blunted, presumably because of an augmented somatostatinergic tone in obese subjects. Further studies have shown that pyridostigmine (Pyr), an acetylcholinesterase inhibitor, is capable of augmenting GH in obesity by means of somatostatin inhibition. In order to evaluate the possible interference of an increased somatostatinergic tone on TSH secretion, we studied the TSH response to a TRH bolus in 5 obese children with or without a pyr pretreatment. Similarly, we tested a group of 10 obese adult subjects, with TRH alone or TRH plus pyr administration, 30 min or 60 min before TRH. All subjects had a body weight of 30-50% greater than I.B.W. Our data show that a pretreatment with pyr, 60 min before TRH administration, significantly augments the TSH response in adult obese subjects but not in children; the modality of pyr administration seems to be crucial to evidenciate such an alteration since the pyr pretreatment is not effective when administered 30 min before TRH. The absence of this pyr effect in obese children induces to hypothesize that somatostatinergic tone is differentially modulated in children vs adult obese subjects.
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PMID:Pyridostigmine effects on TSH response to TRH in adult and children obese subjects. 834 46

Dopaminergic system seems to influence the regulation of insulin secretion, although in man conflicting data are reported. Furthermore, bromocriptine (BRC), a dopaminergic agonist, has been recently found to inhibit the seasonally occurring hyperinsulinemia and the increase in body weight in the hamster. On this basis, we investigated the effect of BRC on spontaneous and stimulated insulin secretion in human obesity. Six obese (BMI: 33.2 +/- 1.6 Kg/m2) underwent the administration of: 1) arginine (ARG, 0.5 g/Kg iv in 30 min), 2) BRC (2.5 mg po), 3) ARG+BRC. In each test plasma glucose and serum insulin, growth hormone (GH) and prolactin levels were determined. BRC did not significantly reduce spontaneous and ARG-induced insulin release. Baseline and stimulated glucose levels were also unchanged. BRC determined an increase in GH levels (3.7 +/- 1.3 vs 0.5 +/- 0.3 microgram/l, p < 0.05), but failed to modify the somatotrope responsiveness to ARG. On the other hand, both spontaneous and stimulated PRL secretion were reduced by BRC (2.5 +/- 0.4 vs 6.7 +/- 1.1 micrograms/l, p < 0.05 and 0.8 +/- 1.9 vs 11.0 +/- 2.1 micrograms/l, p < 0.05, respectively). Our results show that in obese patients the acute activation of dopaminergic receptors by bromocriptine fails to modify both basal and ARG-induced insulin release, while inhibits spontaneous and stimulated PRL secretion. Our data also show that the low GH response to arginine in obesity is not improved by the coadministration of bromocriptine, in agreement with the hypothesis that both substances act by the same mechanism, i.e. inhibition of endogenous somatostatin release.
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PMID:Effect of bromocriptine on insulin, growth hormone and prolactin responses to arginine in obesity. 886 1

Obesity is associated with blunted GH secretion, unfavorable body composition, and increased cardiovascular mortality. The objective of this study was to investigate the effects of oral treatment with the GH secretagogue MK-677 on GH secretion and body composition in otherwise healthy obese males. The study was randomized, double blind, parallel, and placebo controlled. Twenty-four obese males, aged 18-50 yr, with body mass indexes greater than 30 kg/m2 and waist/hip ratios greater than 0.95, were treated with MK-677 25 mg (n = 12) or placebo (n = 12) daily for 8 weeks. Serum insulin-like growth factor I (IGF-I) increased approximately 40% with MK-677 treatment (P < 0.001 vs. placebo). Serum IGF-binding protein-3 was also significantly increased (P < or = 0.001 vs. placebo). GH and PRL (peak and area under the curve values) were significantly increased after the initial dose of MK-677. Significant increases, with the exception of peak PRL, persisted at 2 and 8 weeks of treatment. The increases in GH and PRL after the initial dose were significantly greater than the increase seen after multiple doses. Serum and urinary concentrations of cortisol were not increased at 2 and 8 weeks (P = NS, vs. placebo). Fat-free mass increased significantly in the MK-677 treatment group when determined with dual energy x-ray absorptiometry (P < 0.01) or using a four-compartment model (P < 0.05). Total and visceral fat were not significantly changed with active therapy. The basal metabolic rate was significantly increased at 2 weeks of MK-677 treatment (P = 0.01) but not at 8 weeks (P = 0.1). Fasting concentrations of glucose and insulin were unchanged, whereas an oral glucose tolerance test showed impairment of glucose homeostasis at 2 and 8 weeks. We conclude that 2-month treatment with MK-677 in healthy obese males caused a sustained increase in serum levels of GH, IGF-I, and IGF-binding protein-3. The effects on cortisol secretion were transient. Changes in body composition and energy expenditure were of an anabolic nature, with a sustained increase in fat-free mass and a transient increase in basal metabolic rate. Further studies are needed to evaluate whether a higher dose of MK-677 or a more prolonged treatment period can promote a reduction in body fat.
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PMID:Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. 946 42

Primary empty sella syndrome (ESS) is an anatomo-radiological picture characterized by the presence of an arachnoid herniation filled with liquor that compresses the pituitary against the sellar wall. ESS occurs particularly in obese, hypertensive, cephalgic women, it is often asymptomatic but it may be associated with ophthalmologic, neurologic and sometime non-characterizing endocrine disorders. We report here 71 cases of primary ESS observed and assessed during the last fourteen years. The following endocrinological diagnostic procedures were carried out: hormonal (RIA) basal profile: FT3, FT4, TSH, PRL, ACTH, FSH, LH, 8.00 a.m. and p.m. cortisolemia, Aldo, PRA, DHEA-S, FTe, E2, P, PTH, CT, and calcemia and phosphoremia; provocative tests: TRH, GnRH, insulin hypoglycemia, etc.; inhibition tests: "overnight" and high dose dexamethasone. Clinical, radiological (skull radiographs, CT and/or MRI) and ophthalmologic (fundus, visual fields) assessment were made. We found principally cephalgia (52/71: 73.2%), hypertension (42/71: 59.1%), obesity (47/71: 66.1%). But we found especially mental disorders (57/71: 80.2%), in our knowledge not previously reported in the literature, as anxiety or dysthymic disorders with behavioural disturbances (chiefly oral compulsion). We found endocrinopathies in 36/71 (50.7%), isolated or coexisting in some patients: hyperPRL (14%), hypopituitarism (10.4%), hypogonadism (7%), diabetes insipidus (2.8%), hyperACTH (1.4%), hypoGH (15.4%), pituitary adenomas (8.4%). Several hypothalamic illness show a clinical picture including mental disorders and obesity. The Authors hypothesize that the ESS may be a "new" hypothalamic syndrome (compression/stretching on hypophysis and/or hypophyseal stalk by arachnoidocele; disorder of some hormones and neurotransmitters as leptin, neuropeptide Y, orexins, POMC-derived peptides, etc).
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PMID:[Primary empty sella syndrome. Observations on 71 cases]. 1020 96

The discovery of the adipocyte-produced hormone leptin has greatly changed the field of obesity research and our understanding of energy homeostasis. It is now accepted that leptin is the afferent loop informing the hypothalamus about the state of fat stores, with hypothalamic efferents regulating appetite and energy expenditure. In addition, leptin has a role as a metabolic adaptator in overweight and fasting states. New and previously unsuspected neuroendocrine roles have emerged for leptin. In reproduction, leptin is implicated in fertility regulation, and it is a permissive factor for puberty. Relevant gender-based differences in leptin levels exist, with higher levels in women at birth, which persist throughout life. In adult life, there is experimental evidence that leptin is a permissive factor for the ovarian cycle, with a regulatory role exerted at the hypothalamic, pituitary, and gonadal levels, and with unexplained changes in pregnancy and postpartum. Leptin is present in human milk and may play a role in the adaptive responses of the newborn. Leptin plays a role in the neuroendocrine control of GH secretion, through a complex interaction at hypothalamic levels with GHRH and somatostatin. Leptin participates in the expression of CRH in the hypothalamus, interacts at the adrenal level with ACTH, and is regulated by glucocorticoids. Since leptin and cortisol show an inverse circadian rhythm, it has been suggested that a regulatory feedback is present. Finally, regulatory actions on TRH-TSH and PRL secretion have been found. Thus leptin reports the state of fat stores to the hypothalamus and other neuroendocrine areas, and the neuroendocrine systems adapt their function to the current status of energy homeostasis and fat stores.
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PMID:Neuroendocrine regulation and actions of leptin. 1056 81

In 1994, Zhang et al. of Rockefeller University in New York reported the first successful complementary DNA (cDNA) cloning of leptin by the positional cloning method. Leptin was identified as the gene of ob/ob mouse in genetic obesity syndromes. It has very strong food intake control, and body weight and energy expenditure. The name "leptin" derived from the Greek word leptos, meaning "thin." We hereby review major advances leading to our current finding of leptin, leptin receptor and its structure, the outline of homozygote, and also influence of leptin in the pituitary. (The structure of leptin) The mouse obese gene has been localized to chromosome 6. With human leptin gene on chromosome 7q31.3, its DNA has more than 15000 base pairs and consists of three exons and two introns. For bioactivation of leptin the importance of disulfide-binding site is suggested. Human leptin which replaced the 128-th arginine with glutamine has the function of an aldosteron antagonist, which is reported to have the function of athrocytosis inhibition. The resemblance of leptin precursor of human, mouse and rat is very high, i.e., mouse and rat homology is 96% and mouse and human homology is 83%. (The structure of leptin receptor) The mutant gene, which is the cause of obesity, was shown on map on diabetic mouse (db/db) chromosome 4, and it was proven to be the same as the leptin receptor gene cloned by Tartaglia et all. Further studies have found the Zucker fatty rat (fa/fa) to be incorporated into a linkage map of rat chromosome 5, whose region of rat is the equivalent to the region of conserved synteny of the db/db mouse gene. The leptin receptor is glycoprotein consisting of a single transmembrane-spanning component. The primary structure of leptin receptor belongs to the cytokine-class1 family, the single membrane-spanning receptor, and is highly related to the gp130 signal-transducing component of the interleukin-6 (IL-6) receptor, the granulocyte colony-stimulating factor (G-CSF) receptor, and the leukemia inhibitory factor (LIF) receptor. The leptin receptor is known to have at least six existing isoforms (Ob-Ra, b, c, d, e, f) from the difference in splicing. (Homozygote Mutation of Leptin and Leptin Receptor :Hormone Secretion Disorders) The point mutation of ob/ob mouse and the splicing mutation of db/db mouse show remarkable obesity and hyperphagia. These obesity models show a reproduction disorder with both the male and the female, and they develop with homozygote. The cause is thought to be the gonadotropin secretory abnormality in pituitary. Three family lines report the cases of this deficiency, and it is considered that the secretory abnormality in pituitary develops into hypogonadotropic. These patients show low value in plasma FSHbeta (follicle stimulating hormone-beta and LHbeta (luteinizing hormone-beta which are produced from pituitary, and the plasma GnRH (gonadotropin releasing hormone) level is also low. Furthermore, the leptin receptor deficient family line was reported in 1998, in which case only the homozygote developed. The plasma leptin concentration of normal human is about 8.0 ng/ml, and this case with leptin receptor deficiency has high value of 500-700 ng/ml, which is the equivalent to the db/db mouse. (Role of Leptin in Hypothalamus-Pituitary-Periphery Function) The role of leptin which regulates pituitary hormones suggests the promotion the GHRH (growth hormone releasing hormone) secretion in hypothalamus-pituitary axis, with the possibility of the rise in secretion of GH (growth hormone) in pituitary, i.e. effects of icv (intracerebroventricular) infusion of leptin has spontaneously stimulated GHRH, which promotes GH secretion in the normal rats. On the other hand, topical treatment of GH3 (derived from a rat pituitary GH-secreting cell line) with leptin directly inhibits cell proliferation. The obesity model animals (ob/ob, db/db, fa/fa) have equally plump body compared to the normal models, which shows signs of sufficient growth. (Localization and Functional Relevance of Leptin and Leptin Receptor in Rodents Pituitary) Aside from being the food intake inhibitor and the energy control factor, leptin takes part in controlling the pituitary hormones. Promoting the secretion of GH, PRL (prolactin), TSHbeta (thyroid stimulating hormone-beta, FSHbeta/LHbeta, and inhibiting the secretion of ACTH (adrenocorticotropic hormone) are the major changes of pituitary hormones which are brought on by leptin. The expressive localization is specific, and immunohistochemistry (IHC) method recognized leptin in granular state in FSHbeta, LHbeta and TSHbeta positive cells. In our biochemical examination, the bulk of the expression of leptin is recognized in fraction of the secretory granule. In particular, FSHbeta cells had the highest percentage rate of colocalized leptin in rat pituitary. On the other hand, leptin receptor has been reported to be found only in normal rat pituitary, human pituitary adenoma, and respective cell lines in pituitaries by the RT-PCR method until now, but we disclosed for the first time the localization of leptin receptor on the plasma membrane of GH-secreting cells with the IHC method that has not been cleared so far. These findings show that leptin and leptin receptor have been expressed in different cells, and that the rat pituitary glands entertain paracrine mechanism between leptin (FSHbeta/LHbeta cells) and leptin receptor (GH cells). The function of paracrine in this pituitary suggests a new point of view in hypothalamus-pituitary axis, and it shall be concerned with many aspects such as hormone secretions and proliferation/inhibition. (Human Pituitary Adenoma) Preliminary report of leptin and leptin-receptor relationship with pituitary adenoma that has secretion abnormality has been filed, and its manifestation is being observed by the RT-PCR. Leptin and leptin receptor are expressed in most adenoma, and it is thought to function by autocrine and paracrine pathway in the adenomas. Leptin has been located in ACTH-secreting adenoma most frequently, especially in ACTH carcinoma. The leptin receptor is detected in all adenomas with high percentage rate, with both long and short forms, and then many cases of nonfunctioning pituitary adenomas, compared with other adenomas, have been reported to be positive with both long and short forms of leptin receptor as detected by RT-PCR. The HP75 cell line is derived from the nonfunctioning pituitary adenoma, which produces FSHbeta and LHbeta. The expression of leptin receptor in nonfunctioning pituitary adenoma, and the suppression of HP75 multiplication may lead to the possible hypothesis of leptin becoming one factor for the treatment of pituitary adenoma, especially in gonadotropin adenomas.
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PMID:Leptin and the pituitary. 1182 4

We used longitudinal data from the Massachusetts Male Aging Study, a large population-based random-sample cohort of men aged 40-70 yr at baseline, to establish normative age trends for serum level of T and related hormones in middle-aged men and to test whether general health status affected the age trends. Of 1,709 men enrolled in 1987-1989, 1,156 were followed up 7-10 yr afterward. By repeated-measures statistical analysis, we estimated simultaneously the cross-sectional age trend of each hormone between subjects within the baseline data, the cross-sectional trend between subjects within the follow-up data, and the longitudinal trend within subjects between baseline and follow-up. Total T declined cross-sectionally at 0.8%/yr of age within the follow-up data, whereas both free and albumin-bound T declined at about 2%/yr, all significantly more steeply than within the baseline data. Sex hormone-binding globulin increased cross-sectionally at 1.6%/yr in the follow-up data, similarly to baseline. The longitudinal decline within subjects between baseline and follow-up was considerably steeper than the cross-sectional trend within measurement times for total T (1.6%/yr) and bioavailable T (2-3%/yr). Dehydroepiandrosterone, dehydroepiandrosterone sulfate, cortisol, and estrone showed significant longitudinal declines, whereas dihydrotestosterone, pituitary gonadotropins, and PRL rose longitudinally. Apparent good health, defined as absence of chronic illness, prescription medication, obesity, or excessive drinking, added 10-15% to the level of several androgens and attenuated the cross-sectional trends in T and LH but did not otherwise affect longitudinal or cross-sectional trends. The paradoxical finding that longitudinal age trends were steeper than cross-sectional trends suggests that incident poor health may accelerate the age-related decline in androgen levels.
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PMID:Age trends in the level of serum testosterone and other hormones in middle-aged men: longitudinal results from the Massachusetts male aging study. 1183 90

We report a 28-year-old-female who presented with primary amenorrhoea, absence of puberty, obesity and normal stature. The subject was clearly short as a child, with a height more than 2 SD below normal until the age of 15 years. The pubertal growth spurt failed to develop. She continued growing at a prepubertal rate until growth ceased at the age of 20 years, reaching her final adult height of 157 cm (SDS -0.86) without hormonal treatment. A combined pituitary hormone stimulation test of anterior pituitary function showed deficiencies of GH, LH and FSH, and low normal serum levels of TSH and PRL. Magnetic resonance imaging revealed a hypoplastic pituitary with markedly reduced pituitary height. In addition, a whole body dual energy X-ray absorptiometry scan showed high levels of body fat (54%). Combined pituitary hormone deficiencies with a hypoplastic pituitary suggested the diagnosis of a Prophet of Pit-1 (PROP1) gene mutation. Normal stature in this case, however, confounded this diagnosis. Sequencing of PROP1 revealed homozygosity for a single base-pair substitution (C to T), resulting in the replacement of an Arg by a Cys at codon 120 (R120C) in the third helix of the homeodomain of the Prop-1 protein. To our knowledge, this is the first report of a patient with a mutation in the PROP1 gene that attained normal height without hormonal treatment, indicating a new variability in the PROP1 phenotype, with important implications for the diagnosis of these patients. We suggest that this can be explained by (i) the presence of low levels of GH in the circulation during childhood and adolescence; (ii) the lack of circulating oestrogen delaying epiphyseal fusion, resulting in growth beyond the period of normal growth; and (iii) fusion of the epiphyseal plates, possibly as a result of circulating oestrogens originating from peripheral conversion of androgens by adipose tissue.
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PMID:A unique case of combined pituitary hormone deficiency caused by a PROP1 gene mutation (R120C) associated with normal height and absent puberty. 1215 92

GH and PRL are both implicated in adipose tissue development. Whilst direct effects of GH have been clearly demonstrated, direct effects of PRL have been subject to considerable debate. Recent studies have however provided compelling evidence for PRL receptors on adipocytes and in vitro effects on leptin and lipoprotein lipase activity have been demonstrated. Quantitatively however these effects of PRL are less significant than those of GH and the most pronounced effects of PRL on adipose tissue are indirect, for example, during lactation, when prolactin drives milk synthesis which results in a homeorhetic shift towards lipid mobilization from adipose tissue to support milk production. GH also exhibits such homeorhetic effects, most notably in ruminants, but also clearly has direct, insulin-antagonistic, metabolic effects. The roles of GH and PRL on adipocyte proliferation and differentiation have also been controversial, with GH stimulating adipocyte differentiation in vitro in cell lines whilst stimulating proliferation and inhibiting differentiation of primary cell cultures. Examination of adipose tissue development in PRLRko and GHRko mice has revealed roles for both hormones. PRLRko mice show impaired development of both internal and subcutaneous adipose tissue due to decreased numbers of adipocytes. In contrast, GHRko mice exhibit major decreases in the number of internal (parametrial) adipocytes whereas subcutaneous adipocytes develop almost normally. This leads to major changes in the sites of adipose tissue accretion and bears interesting parallels with the adipose tissue redistribution which occurs in HIV-induced lipodystrophy. Such individuals exhibit a central obesity which can be partially corrected by GH treatment. However, recent studies suggest that this may be a physiological response in which adipose tissue sites containing lymphoid tissue (such as mesenteric) show preservation of adipose tissue perhaps to support augmented immune responses.
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PMID:Effects of growth hormone and prolactin on adipose tissue development and function. 1470 19

We report a 45-year-old woman with Cushing's syndrome showing reversible pituitary dysfunction. Left adrenal tumor was incidentally discovered by a screening examination of abdominal computed tomography. Although this patient lacked typical Cushingoid features except hypertension and leg edema, endocrine examinations revealed moderate suppression of plasma ACTH (~6.3 pg/ml) with relatively high levels of serum cortisol (~22.9 microg/dl) without normal circadian rhythm. Plasma ACTH failed to respond to either CRH or metyrapone, and dexamethasone failed to suppress her daily steroid production. Surgical removal of left adrenocortical adenoma and 6-month replacement of hydrocortisone have ameliorated both ACTH and cortisol responses to CRH loading test. Postoperative responses of TSH and GH to TRH and GRH, respectively, were two fold higher than the preoperative levels. In contrast, basal and TRH-induced levels of serum PRL were decreased after surgery although both the basal and stimulated PRL levels were markedly high before surgery. In addition, gonadotropin response to GnRH examined in the same ovarian cycle was decreased in accordance with an increase in serum estradiol and progesterone levels after surgery. Improvement of hypercortisolemia even in a moderate case of Cushing's syndrome not only ameliorates hypertension, obesity and glucose intolerance, but also restores the accompanying dysfunctions of anterior pituitary, suggesting the clinical importance of early discovery and treatment of functioning adrenocortical incidentalomas.
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PMID:Reversible pituitary dysfunction in a patient with Cushing's syndrome discovered as adrenal incidentaloma. 1511 71


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