Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adrenomedullin (AM), a recently discovered hypotensive peptide, is expressed in the endocrine pancreas of different species, as demonstrated by immunocytochemistry. Electron microscopic studies with double immunogold showed colocalization of AM and pancreatic polypeptide. A homogeneous expression of AM receptor was found throughout the islet using in situ hybridization. Six different insulin- producing cell lines have been analyzed by reverse transcription-PCR and showed expression of both AM and its receptor. Two experimental models have been used to study the effects of AM in pancreatic physiology. 1) Analysis of isolated rat islets shows that AM inhibits insulin secretion in a dose-dependent manner. The monoclonal antibody MoAb-G6, which neutralizes AM bioactivity, was able to increase insulin release 5-fold; this effect was reversed by the addition of synthetic AM. 2) Oral glucose tolerance tests showed that iv injection of AM reduces the levels of insulin in the bloodstream with a concomitant increase in circulating glucose. These studies implicate AM as a newly defined factor of the insulin regulatory system that could be involved in disorders such as diabetes and obesity.
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PMID:Regulation of insulin secretion and blood glucose metabolism by adrenomedullin. 864 Dec 17

The effect of Orlistat, a lipase inhibitor used in the treatment of obesity was studied on gastrointestinal transit time, on body composition and on hormones known to be influenced by the degree of hydrolysis of nutritional triglycerides or by reduced nutrient intake and absorption. After a placebo run-in period 14 patients were randomized to a 12-week treatment period on Orlistat 360 mg per day (mean body weight 93.1 +/- 9.8 kg) or placebo (mean body weight 90.7 +/- 10.5 kg). At randomization and after 12 weeks body weight, body composition, thyroid hormones, catecholamines, insulin-like growth factor I (IGF-I) and IGF-binding protein 3 were measured. During 4 hours after consumption of a liquid fat-rich mixed meal containing study medication, 15 g lactulose and 25 g xylose, blood levels of glucose, insulin, c-peptide, glucagon, triglycerides, free fatty acids, cholecystokinin, pancreatic polypeptide and xylose and expiration air levels of hydrogen were measured. Weight loss was 4.2 +/- 3.5 kg in the Orlistat group versus 3.0 +/- 1.9 kg in the placebo group. Fat mass decreased to an equal degree, whereas lean body mass remained stable. No differences were found for thyroid hormones, catecholamines, IGF-I and IGFBP-3 levels. By comparing the areas under the curve (AUC) and the peak levels at randomization (acute effects) of insulin and c-peptide a tendency was found to be increased in the Orlistat group, whereas those of xylose were increased significantly, suggesting faster gastric emptying after Orlistat. No differences were found in the other parameters. By comparing the changes in responses (longer term effects) no significant differences were found. In conclusion, the presence in the gut of undigested and unabsorbed fat does not seem to have a relevant influence on hormonal status and body composition in a small group of moderately obese patients.
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PMID:Lipase inhibition and hormonal status, body composition and gastrointestinal processing of a liquid high-fat mixed meal in moderately obese subjects. 865 34

Chronic pancreatitis (CP) is associated with lowered plasma levels and a blunted nutrient-induced release of pancreatic polypeptide (PP). To investigate the possible role of PP on glucose metabolism, we studied male patients with documented CP (n = 5) and obesity-matched control subjects (NL) (n = 6). Hepatic glucose production (HGP) and overall glucose disposal rates were determined by [3-3H]glucose infusion during a hyperinsulinemic-euglycemic clamp during three separate admissions. Basal rates of HGP were higher in CP patients. In response to an infusion of insulin (60 pmol.m-2.min-1), HGP fell 91 +/- 5% in NL subjects but only 68 +/- 8% in CP subjects (P < 0.05). One month later, the clamp was repeated during the final 2 h of an 8-h infusion of bovine PP (2 pmol.kg-1.min-1). HGP before the insulin infusion and its subsequent suppression (NL: 83 +/- 5%; CP: 86 +/- 15%) were nearly identical between groups. In follow-up studies 1 month after the PP infusion, HGP both basally and in response to insulin alone were similar to the first study. During oral glucose tolerance tests (OGTT) performed 18 h after the PP infusion, subjects with normal (n = 7) baseline OGTT responses showed no effect. All patients with diabetic (n = 3) or nondiagnostic (n = 1) OGTT responses, however, demonstrated lowered mean plasma glucose levels (approximately -2.3 mmol/L; range: -0.6 to -7.2 mmol/L). OGTTs repeated 1 month after the PP treatment showed a return to pretreatment responses. We conclude that chronic pancreatitis accompanied by PP deficiency is associated with partial hepatic resistance both in the basal state and in response to hyperinsulinemia. This impairment is reversed after iv PP administration. PP deficiency may therefore play a role in the development of pancreatogenic diabetes caused by pancreatic injury.
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PMID:Pancreatic polypeptide administration improves abnormal glucose metabolism in patients with chronic pancreatitis. 885 2

The pancreatic polypeptide (PP-fold) family of peptides consists of the endocrine peptides, pancreatic polypeptide (PP) and peptide YY (PYY), and the neuroneally derived peptide, neuropeptide Y (NPY). All three peptides are found in the circulation, with PP found primarily in the pancreas and PYY found principally in the gut. NPY is released into the circulation from neuroneal stores in response to stress. These peptides have broad peripheral actions on a number of organs. Not surprisingly, PYY and PP are believed to play an important role in the function of the gastrointestinal tract while NPY is a potent vasconstrictor and may have effects on the gut through the enteric nervous system. In the brain, NPY has been implicated in anxiety and depression, feeding and obesity, memory retention, neuroneal excitability, endocrine function, and metabolism. Recent advances in the molecular biology of the receptors for these peptides have resulted in the identification of at least six receptor subtypes with varying peptide pharmacology. Compared to other G-protein coupled receptor families, the PP-fold peptide receptors exhibit a relatively low level of sequence identity. Further advances in the development of selective agonists and antagonists for individual receptor subtypes will be needed to understand further their role in physiological function.
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PMID:Multiple receptors for the pancreatic polypeptide (PP-fold) family: physiological implications. 957 48

Amylase inhibition has gastrointestinal and metabolic effects that may aid in the treatment of diabetes and obesity. We tested whether 4 g of a commercially available wheat amylase inhibitor (WAI) affected postprandial carbohydrate (CHO) absorption and plasma glucose or hormones. Twelve persons (four lean and four obese nondiabetics and four obese type II diabetics) were studied on 2 separate days. After eating a weight maintenance diet (55% CHO, 20% protein, and 25% fat, as percentage of calories) for 3 days, subjects ate a breakfast containing 650 kcal, the same proportion of nutrients as calories, and in random order, either WAI or no WAI. Breath H2 and plasma glucose and hormones were measured every 15 and 30 min, respectively, for 7 h. WAI decreased the delta peak postprandial plasma glucose concentrations in 10 of 12 subjects (p < 0.05) and increased the breath H2 levels in 11 (p = 0.02); the increases in breath H2 were small, generally <20 ppm. No subject experienced a change in stools, diarrhea, or bloating. In response to WAI, gastric inhibitory peptide decreased (p < 0.05), peptide YY increased (p < 0.05), and there was a trend toward increased human pancreatic polypeptide (p = 0.07). Although WAI delays CHO absorption and reduces peak postprandial plasma glucose concentrations, overall CHO malabsorption is minimal (as reflected by breath hydrogen and hormones) and without symptoms. It, therefore, may be useful in treating type II diabetes mellitus.
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PMID:Acute postprandial gastrointestinal and metabolic effects of wheat amylase inhibitor (WAI) in normal, obese, and diabetic humans. 970 Sep 50

Palatable cephalic stimuli induce a simultaneous activation of gastrointestinal motility, gastric acid and pancreatic enzyme secretion, as well as, release of the gastrointestinal hormones gastrin and pancreatic polypeptide. Cholinergic neural input is the dominant mediator of these responses with cholecystokinin and gastrin acting as additional stimulatory modulators. Central cholinergic circuits, neuropeptide Y, and thyrotropin releasing hormone are candidate central stimulators of the cephalic phase. There are good arguments for glucagon-like peptide-1 and peptide YY to be physiological inhibitors of cephalic-phase responses with these peptides being released in the intestinal phase of digestion and putatively contributing to termination of the cephalically stimulated pattern. Cephalic-phase responses are used clinically as diagnostic tests to assess completeness of selective proximal vagotomy and to explore autonomic neuropathy. Pancreatic polypeptide secretion with sham feeding is an appropriate test of abdominal vagal function. Cephalically stimulated motor and secretory activity contribute greater than 50% of overall postprandial responses. Pharmacological inhibition of cephalic-vagal stimulation, resulting in reduced food intake, may be a novel approach to obesity management. Glucagon-like peptide-1 is a particular candidate because it inhibits the cephalic phase of digestion, diminishes food intake, and reduces the glycemic excursion after a meal by retarding gastric emptying, stimulating insulin and lowering glucagon release.
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PMID:Nutritional implications of cephalic phase gastrointestinal responses. 1074 9

The data concerning the cephalic phase of insulin secretion (CPIS) in human obesity are controversial. We investigated the effect of a variety of sensory challenges on CPIS in 17 non-diabetic obese patients (four males, 13 females, mean age 41.1 years, mean BMI 38.7). Water, saccharin, and lemon juice were used as oral stimuli, and a complete meal was simply presented as visual and olfactory stimulations. Twelve healthy normal-weight subjects (four men, eight women, mean age 39.9, mean BMI 22.5) also underwent oral stimulation as controls, and the patients who underwent the sight and smell stimulations were also tested for pancreatic polypeptide (PP) changes in order to verify the occurrence of truly cephalic reflex during the test. Insulin levels were measured before and after each stimulation (every min for the first 5 min, and then after 10, 20, and 30 min). None of the stimuli (saccharin, lemon juice or water retained in the mouth for 2 min and were then spat out; the combined and separate sight and smell of a meal for 2 min) led to a significant increase in insulin in the obese patients (except in the case of one woman after oral stimulation). The oral stimuli led to a variable CPIS in one female and three male controls. Despite the absence of CPIS, the five obese patients undergoing all three sensory stimulations related to the meal (combined sight and smell, sight alone and smell alone) showed an early and significant increase in plasma PP concentrations within the first 3 min; this was more pronounced after the combined than after the separate exposure. Although only preliminary, these results underline the variability but substantial lack of CPIS in obese patients, thus suggesting that it can be considered a relatively rare and unrelevant event even in the presence of a true brain-mediated reflex revealed by the rapid and consistent increase in PP found in our experiments.
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PMID:Food-related sensory stimuli are able to promote pancreatic polypeptide elevation without evident cephalic phase insulin secretion in human obesity. 1089 54

Food intake is a regulated system. Afferent signals provide information to the central nervous system, which is the centre for the control of satiety or food seeking. Such signals can begin even before food is ingested through visual, auditory and olfactory stimuli. One of the recent interesting findings is the demonstration that there are selective fatty acid taste receptors on the tongue of rodents. The suppression of food intake by essential fatty acids infused into the stomach and the suppression of electrical signals in taste buds reflect activation of a K rectifier channel (K 1.5). In animals that become fat eating a high-fat diet the suppression of this current by linoleic acid is less than that in animals that are resistant to obesity induced by dietary fat. Inhibition of fatty acid oxidation with either mercaptoacetate (which blocks acetyl-CoA dehydrogenase) or methylpalmoxirate will increase food intake. When animals have a choice of food, mercaptoacetate stimulates the intake of protein and carbohydrate, but not fat. Afferent gut signals also signal satiety. The first of these gut signals to be identified was cholecystokinin (CCK). When CCK acts on CCK-A receptors in the gastrointestinal tract, food intake is suppressed. These signals are transmitted by the vagus nerve to the nucleus tractus solitarius and thence to higher centres including the lateral parabrachial nucleus, amygdala, and other sites. Rats that lack the CCK-A receptor become obese, but transgenic mice lacking CCK-A receptors do not become obese. CCK inhibits food intake in human subjects. Enterostatin, the pentapeptide produced when pancreatic colipase is cleaved in the gut, has been shown to reduce food intake. This peptide differs in its action from CCK by selectively reducing fat intake. Enterostatin reduces hunger ratings in human subjects. Bombesin and its human analogue, gastrin inhibitory peptide (also gastrin-insulin peptide), reduce food intake in obese and lean subjects. Animals lacking bombesin-3 receptor become obese, suggesting that this peptide may also be important. Circulating glucose concentrations show a dip before the onset of most meals in human subjects and rodents. When the glucose dip is prevented, the next meal is delayed. The dip in glucose is preceded by a rise in insulin, and stimulating insulin release will decrease circulating glucose and lead to food intake. Pyruvate and lactate inhibit food intake differently in animals that become obese compared with lean animals. Leptin released from fat cells is an important peripheral signal from fat stores which modulates food intake. Leptin deficiency or leptin receptor defects produce massive obesity. This peptide signals a variety of central mechanisms by acting on receptors in the arcuate nucleus and hypothalamus. Pancreatic hormones including glucagon, amylin and pancreatic polypeptide reduce food intake. Four pituitary peptides also modify food intake. Vasopressin decreases feeding. In contrast, injections of desacetyl melanocyte-stimulating hormone, growth hormone and prolactin are associated with increased food intake. Finally, there are a group of miscellaneous peptides that modulate feeding. beta-Casomorphin, a heptapeptide produced during the hydrolysis of casein, stimulates food intake in experimental animals. In contrast, the other peptides in this group, including calcitonin, apolipoprotein A-IV, the cyclized form of histidyl-proline, several cytokines and thyrotropin-releasing hormone, all decrease food intake. Many of these peptides act on gastrointestinal or hepatic receptors that relay messages to the brain via the afferent vagus nerve. As a group they provide a number of leads for potential drug development.
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PMID:Afferent signals regulating food intake. 1099 53

Vagally-mediated hyperinsulinemia is a common abnormality in various rodent models of genetic and hypothalamic obesity that have a high propensity for type 2 diabetes. We hypothesized that Pima Indians, a population with a high prevalence of hyperinsulinemia, obesity, and type 2 diabetes also have an increased parasympathetic drive to the pancreas. To test this, we measured plasma concentrations of insulin and pancreatic polypeptide (PP), a surrogate marker of pancreatic vagal tone, in lean and obese Pima Indian and Caucasian children (n = 43, 26P/17C, 7 +/- 1 y) and adults (n = 92, 61P/31C, 31 +/- 5 y). Pima Indian children had approximately 2-fold higher fasting insulin and 57% higher fasting PP concentrations than age- and sex-matched Caucasian children (P < .05). Although there was no difference in fasting PP concentration between Pima Indian and Caucasian adults, in response to a mixed meal, Pima Indians had a 51% higher early (30 minutes) PP concentration and 2-fold higher early insulin concentration than Caucasians (P < .05). PP concentrations at 60 minutes and 120 minutes after the meal were also markedly higher in both lean and obese Pima Indians compared with lean and obese Caucasians. These results suggest that Pima Indians may have an increased parasympathetic drive to the pancreas, which could lead to a primary hypersecretion of insulin and contribute to their high propensity for obesity and diabetes, as is the case in various rodent models of obesity.
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PMID:Exaggerated pancreatic polypeptide secretion in Pima Indians: can an increased parasympathetic drive to the pancreas contribute to hyperinsulinemia, obesity, and diabetes in humans? 1122 33

Medium chain fatty acids (MCFA) are readily oxidized in the liver. Animal and human studies have shown that the fast rate of oxidation of MCFA leads to greater energy expenditure (EE). Most animal studies have also demonstrated that the greater EE with MCFA relative to long-chain fatty acids (LCFA) results in less body weight gain and decreased size of fat depots after several months of consumption. Furthermore, both animal and human trials suggest a greater satiating effect of medium-chain triglycerides (MCT) compared with long-chain triglycerides (LCT). The aim of this review is to evaluate existing data describing the effects of MCT on EE and satiety and determine their potential efficacy as agents in the treatment of human obesity. Animal studies are summarized and human trials more systematically evaluated because the primary focus of this article is to examine the effects of MCT on human energy metabolism and satiety. Hormones including cholescytokinin, peptide YY, gastric inhibitory peptide, neurotensin and pancreatic polypeptide have been proposed to be involved in the mechanism by which MCT may induce satiety; however, the exact mechanisms have not been established. From the literature reviewed, we conclude that MCT increase energy expenditure, may result in faster satiety and facilitate weight control when included in the diet as a replacement for fats containing LCT.
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PMID:Physiological effects of medium-chain triglycerides: potential agents in the prevention of obesity. 1188 May 49


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