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

Ghrelin stimulates appetite and plays a role in the neuroendocrine response to energy balance variations. Ghrelin levels are inversely associated with body mass index (BMI), increased by fasting and decreased by food intake, glucose load, insulin, and somatostatin. Ghrelin levels are reduced in obesity, a condition of hyperinsulinism, reduced GH secretion, and hypothalamus-pituitary-adrenal axis hyperactivity. We studied the endocrine and metabolic response to acute ghrelin administration (1.0 microg/kg i.v.) in nine obese women [OB; BMI (mean +/- SD) 36.3 +/- 2.3 kg/m(2)] and seven normal women (NW; BMI 20.3 +/- 1.7 kg/m(2)). Basal ghrelin levels in NW were higher than in OB (P < 0.05). In NW, ghrelin increased (P < 0.05) GH, prolactin (PRL), ACTH, cortisol, and glucose levels but did not modify insulin. In OB, ghrelin increased (P < 0.01) GH, PRL, ACTH, and cortisol levels. The GH response to ghrelin in OB was 55% lower (P < 0.02) than in NW, whereas the PRL, ACTH, and cortisol responses were similar. In OB, ghrelin increased glucose and reduced insulin (P < 0.05). Thus, obesity shows remarkable reduction of the somatotroph responsiveness to ghrelin, suggesting that ghrelin hyposecretion unlikely explains the impairment of somatotroph function in obesity. On the other hand, in obesity ghrelin shows preserved influence on PRL, ACTH, and insulin secretion as well as in glucose levels.
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PMID:Neuroendocrine and metabolic effects of acute ghrelin administration in human obesity. 1460 93

Ghrelin is a new orexigenic peptide primarily produced by the stomach but also present in the hypothalamus. It has adipogenic effects when it is chronically injected in rodents but in obese humans, its plasma concentration is decreased. It can reverse the anorectic effects of leptin when it is co-injected with this peptide in the brain ventricles. The Zucker fa/fa rat is a genetic model of obesity related to a default in the leptin receptor. It is characterized by a large dysregulation of numerous hypothalamic peptides but the ghrelin status of this rat has not yet been determined. Through several experiments, we determine in lean and obese Zucker rats its circulating form in the plasma, its tissue levels and/or expression, and studied the influence of different feeding conditions and its light/dark variations. Ghrelin expression was higher in the obese stomach and hypothalamus (P < 0.05 and P < 0.02, respectively). The ratio of [Octanoyl-Ser3]-ghrelin (active form) to [Des-Octanoyl-Ser3]-ghrelin (inactive form) was approximately 1:1 in the stomach and 2:1 in the plasma in lean and obese rats (no differences). After fasting, plasma ghrelin concentrations increased significantly in lean (+ 64%; P < 0.001) and obese (+ 60%; P < 0.02) rats. After 24 hours of refeeding, they returned to their initial ad lib levels. Ghrelin concentrations were higher in obese rats by 69% (P < 0.005), 65% (P < 0.02), and 73% (P < 0.005) in the ad libitum, fast, and refed states respectively. These results indicate that the obese Zucker rat is characterized by increases in the stomach mRNA expression and in peptide release in the circulation. They clearly support a role for ghrelin in the development of obesity in the absence of leptin signaling.
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PMID:Ghrelin and body weight regulation in the obese Zucker rat in relation to feeding state and dark/light cycle. 1461 Feb 50

Ghrelin has been discovered as a natural ligand of the receptor specific for synthetic GH secretagogues (GHS). Ghrelin as well as synthetic GHS not only possess a remarkable GH-releasing activity but are also endowed with other endocrine and nonendocrine activities including orexigenic action, influence on gastro-enteropancreatic functions, and cardiovascular and anti-proliferative effects. Based on these data, particular effort has been focused on the isolation of new putative natural ligands of the GHS-receptors (GHS-R) and on the identification of synthetic compounds endowed with agonistic or antagonistic activity. For instance, ghrelin analogs acting as agonists or antagonists would be able to enhance or reduce appetite and food intake; these molecules would receive obvious interest for treatment of eating disorders and obesity, respectively. Ghrelin and its orally active, agonistic analogs could have prespectives for diagnosis and treatment of GH insufficiency. In this context, EP1572, a selective, orally active, peptidomimetic GHS as well as cortistatin, another putative, natural ligand of the GHS-R, and its analogs, are currently under investigation.
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PMID:Targeting the ghrelin receptor: orally active GHS and cortistatin analogs. 1461 Feb 94

Ghrelin is a 28-amino-acid peptide predominantly produced by the stomach, while substantially lower amounts derive from other tissues including the pancreas. It is a natural ligand of the GH secretagogue (GHS) receptor (GHS-R1a) and strongly stimulates GH secretion, but acylation in serine 3 is needed for its activity. Ghrelin also possesses other endocrine and nonendocrine actions reflecting central and peripheral GHS-R distribution including the pancreas. The wide spectrum of ghrelin activities includes orexigenic effect, control of energy expenditure, and peripheral gastroenteropancreatic actions. Circulating ghrelin levels mostly reflect gastric secretion as indicated by evidence that they are reduced by 80% after gastrectomy and even after gastric by-pass surgery. Ghrelin secretion is increased in anorexia and cachexia but reduced in obesity, a notable exception being Prader-Willi syndrome. The negative association between ghrelin secretion and body weight is emphasized by evidence that weight increase and decrease reduces and augments circulating ghrelin levels in anorexia and obesity, respectively, and agrees with the clear negative association between ghrelin and insulin levels. In fact, ghrelin secretion is increased by fasting whereas it is decreased by glucose load as well as during euglycemic clamp but not after arginine or free fatty acid load in normal subjects; in physiological conditions, however, the most remarkable inhibitory input on ghrelin secretion is represented by somatostatin as well as by its natural analog cortistatin that concomitantly reduce beta-cell secretion. This evidence indicates that the endocrine pancreas plays a role in directly or indirectly modulating ghrelin secretion.
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PMID:Ghrelin and the endocrine pancreas. 1461 Feb 95

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.
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PMID:Low ghrelin concentrations in nonalcoholic fatty liver disease are related to insulin resistance. 1467 Nov 52

Ghrelin, leptin and adiponectin are three hormones which are frequently associated with metabolism, obesity and appetite. Recently, it has been shown that they may possess other physiologic roles, specially in connection with the circulation. Ghrelin infusion increases forearm blood-flow in a dose-dependent manner. Leptin has been shown to be involved not only in thermogenesis but angiogenesis as well. Adiponectin, apart from its insulin-sensitizing action, appears to modulate inflammation by inhibiting monocyte adhesion to endothelial cells. Six monkeys, which had been classified as being in the pre-diabetic state, where administered a triglyceride lowering regimen. Microvascular function was assessed using a laser Doppler flow-meter during a temperature provocation test. Percent change in flow from baseline following temperature elevation, as well as percent change in flow/degree rise in temperature were used to evaluate microvascular reserve and reactivity. Using univariate analysis, it appears that increased perfusion is significantly correlated with adiponectin, followed by leptin. Flow was also positively correlated with ghrelin, but the relationship did not attain significance. As expected, flow was also negatively and significantly correlated with fibrinogen. Trends show that flow was also negatively correlated to circulating triglyceride levels (p=0.08). The data indicate that the three hormones appear to possess microvascular actions that may impact on their other physiologic functions.
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PMID:Is microvascular flow rate related to ghrelin, leptin and adiponectin levels? 1472 68

Ghrelin is a gastric hormone that exerts a stimulatory effect on appetite and fat accumulation. Ser(3) octanoylation is regarded as a prerequisite for ghrelin biological activity, although des-octanoylated forms may retain biological functions in vitro. Circulating ghrelin levels are usually low in obesity and in states of positive energy balance. Hence, the aim of our study was to analyze plasma active and serum total ghrelin levels in 20 obese (ages, 22-42 yr; body mass index, 41.3 +/- 1.1 kg/m(2)) and 20 lean subjects (ages, 22-43 yr; body mass index, 22.4 +/- 0.6 kg/m(2)) as well as their relationship to measures of glucose homeostasis, body fat, and resting energy expenditure (REE). The measured/predicted REE percentage ratio was calculated to subdivide groups into those with positive (> or = 100% ) and negative (<100%) ratio values. In obese patients, plasma active (180 +/- 18 vs. 411 +/- 57 pg/ml; P < 0.001) and serum total ghrelin levels (3650 +/- 408 vs. 5263 +/- 643 pg/ml; P < 0.05) were significantly lower when compared with lean subjects. Hence, ghrelin activity, defined as the proportion of active over total ghrelin levels, was similarly reduced in the obese state (6.1 +/- 0.9% vs. 8.4 +/- 1%; P < 0.05). There was a significant correlation between active and total ghrelin (r = 0.62; P < 0.001), and between total ghrelin and insulin (r = -0.53; P < 0.001) or insulin resistance using the homeostatis model of assessment-insulin resistance (r = -0.49; P < 0.001) approach. Significantly higher active ghrelin levels (214 +/- 22 vs. 159 +/- 30 pg/ml; P < 0.05) and ghrelin activity (8 +/- 1.7% vs. 4.9 +/- 0.9%; P < 0.05) were observed in patients with positive compared with negative measured/predicted REE ratio values. Our study shows that obesity is associated with an impairment of the entire ghrelin system. The observation that ghrelin is further decreased in cases of abnormal energy profit adds new evidence to the relationship between ghrelin activity and energy balance in obesity.
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PMID:The relationship between active ghrelin levels and human obesity involves alterations in resting energy expenditure. 1476 17

Ghrelin, a stomach-derived orexigenic hormone, has stimulated great interest as a potential target for obesity control. Pharmacological evidence indicates that ghrelin's effects on food intake are mediated by neuropeptide Y (NPY) and agouti-related protein (AgRP) in the central nervous system. These include intracerebroventricular application of antibodies to neutralize NPY and AgRP, and the application of an NPY Y1 receptor antagonist, which blocks some of the orexigenic effects of ghrelin. Here we describe treatment of Agrp(-/-);Npy(-/-) and Mc3r(-/-);Mc4r(-/-) double knockout mice as well as Npy(-/-) and Agrp(-/-) single knockout mice with either ghrelin or an orally active nonpeptide ghrelin agonist. The data demonstrate that NPY and AgRP are required for the orexigenic effects of ghrelin, as well as the involvement of the melanocortin pathway in ghrelin signaling. Our results outline a functional interaction between the NPY and AgRP pathways. Although deletion of either NPY or AgRP caused only a modest or nondetectable effect, ablation of both ligands completely abolished the orexigenic action of ghrelin. Our results establish an in vivo orexigenic function for NPY and AgRP, mediating the effect of ghrelin.
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PMID:Orexigenic action of peripheral ghrelin is mediated by neuropeptide Y and agouti-related protein. 1514 Aug 38

The gastrointestinal tract and the pancreas release hormones regulating satiety and body weight. Ghrelin stimulates appetite, and glucagon-like peptide-1, oxyntomodulin, peptide YY, cholecystokinin, and pancreatic polypeptide inhibit appetite. These gut hormones act to markedly alter food intake in humans and rodents. Obesity is the current major cause of premature death in the United Kingdom, killing almost 1000 people per week. Worldwide, its prevalence is accelerating. There is currently no effective answer to the pandemic of obesity, but replacement of the low levels of peptide YY observed in the obese may represent an effective antiobesity therapy.
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PMID:Minireview: Gut peptides regulating satiety. 1504 53

Ghrelin levels are increased by fasting and energy restriction, decreased by food intake, glucose load and insulin but not by lipids and amino acids. Accordingly, ghrelin levels are elevated in anorexia and cachexia and reduced in obesity. Herein we compared the effects of a standardized light breakfast (SLB) on morning circulating ghrelin levels with those of oral glucose load (OGTT) in normal subjects. Specifically, 8 young adult volunteers [age (mean+/-SEM): 28.0+/-2.0 yr; body mass index (BMI): 22.4+/-0.6 kg/m2] underwent the following testing sessions: a) OGTT (100 g p.o. at 0 min, about 400 kcal); b) SLB (about 400 kcal, 45% carbohydrates, 13% proteins and 42% lipids at 0 min) on three different days; c) placebo (100 ml water p.o.). In all sessions, at baseline, blood samples were withdrawn twice at 5-min interval to characterize the inter- and intra-individual reproducibility of the variables assayed. After placebo and OGTT, blood samples were withdrawn every 15 min up to +120 min. After SLB, blood samples were taken at 60 min only. Ghrelin, insulin and glucose levels were assayed at each time point in all sessions. Similarly to insulin and glucose levels, at baseline, ghrelin showed remarkable intra-subject reproducibility both in the same sessions and among the different sessions. Placebo did not significantly modify ghrelin, insulin and glucose. OGTT increased (p<0.01) glucose (baseline vs peak: 80.0+/-3.6 vs 140.5+/-6.3 mg/dl) and insulin (20.2+/-6.2 vs 115.3+/-10.3 mU/l) levels. SLB increased (p<0.05) both insulin (16.3+/-1.8 vs 48.3+/-6.3 mU/l) and glucose (74.5+/-3.7 vs 82.9+/-3.1 mg/dl) levels. Notably both the insulin and glucose increases after OGTT were significantly higher (p<0.01) than that induced by SLB. After OGTT, ghrelin levels underwent a significant reduction (baseline vs nadir: 355.7+/-150.8 vs 243.3+/-98.8 pg/ml; p<0.05) reaching the nadir at time +60 min. Similarly, ghrelin levels 60 min after SLB (264.8+/-44.8 pg/ml) were significantly (p<0.01) lower than at baseline (341.4+/-54.9 pg/ml). No significant differences in the reduction of ghrelin levels after OGTT and SLB were observed. In conclusion, these findings show that light breakfast inhibits ghrelin secretion to the same extent of OGTT in adults despite lower variations in glucose and insulin levels.
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PMID:Standard light breakfast inhibits circulating ghrelin level to the same extent of oral glucose load in humans, despite different impact on glucose and insulin levels. 1505 73


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