cholecystokinin and tyrosyltyrosine

We are currently facing an obesity pandemic, with worldwide obesity rates having tripled since 1975. Obesity is one of the main risk factors for the development of non-communicable diseases, which are now the leading cause of death worldwide. This calls for urgent action towards understanding the underlying mechanisms behind the development of obesity as well as developing more effective treatments and interventions. Appetite is carefully regulated in humans via the interaction between the central nervous system and peripheral hormones. This involves a delicate balance in external stimuli, circulating satiating and appetite stimulating hormones, and correct functioning of neuronal signals. Any changes in this equilibrium can lead to an imbalance in energy intake versus expenditure, which often leads to overeating, and potentially weight gain resulting in overweight or obesity. Several lines of research have shown imbalances in gut hormones are found in those who are overweight or obese, which may be contributing to their condition. Therefore, this review examines the evidence for targeting gut hormones in the treatment of obesity by discussing how their dysregulation influences food intake, the potential possibility of altering the circulating levels of these hormones for treating obesity, as well as the role of short chain fatty acids and protein as novel treatments.

Topics: Acetic Acid; Animals; Appetite; Appetite Regulation; Butyrates; Central Nervous System; Cholecystokinin; Dipeptides; Energy Intake; Energy Metabolism; Fatty Acids, Volatile; Gastrointestinal Hormones; Gastrointestinal Tract; Ghrelin; Glucagon-Like Peptide 1; Humans; Hyperphagia; Mice; Neuropeptide Y; Obesity; Overweight; Oxyntomodulin; Pancreatic Polypeptide; Propionates; Satiation

The vagal link between the gastrointestinal tract and the central nervous system (CNS) has numerous vital functions for maintaining homeostasis. The regulation of energy balance is one which is attracting more and more attention due to the potential for exploiting peripheral hormonal targets as treatments for conditions such as obesity. While physiologically, this system is well tuned and demonstrated to be effective in the regulation of both local function and promoting/terminating food intake the neural connection represents a susceptible pathway for disruption in various disease states. Numerous studies have revealed that obesity in particularly is associated with an array of modifications in vagal afferent function from changes in expression of signaling molecules to altered activation mechanics. In general, these changes in vagal afferent function in obesity further promote food intake instead of the more desirable reduction in food intake. It is essential to gain a comprehensive understanding of the mechanisms responsible for these detrimental effects before we can establish more effective pharmacotherapies or lifestyle strategies for the treatment of obesity and the maintenance of weight loss.

Topics: Animals; Cholecystokinin; Dipeptides; Eating; Gastrointestinal Tract; Ghrelin; Glucagon-Like Peptide 1; Humans; Leptin; Microbiota; Neuronal Plasticity; Obesity; Satiation; Signal Transduction; Vagus Nerve

Childhood obesity is a global epidemic and associated with an increased risk of hypertension, diabetes mellitus, and coronary heart disease, in addition to psychological disorders. Interventions such as bariatric surgery are highly invasive and lifestyle modifications are often unsuccessful because of disturbed perceptions of satiety. New signaling peptides discovered in recent years that are produced in peripheral tissues such as the gut, adipose tissue, and pancreas communicate with brain centers of energy homeostasis, such as the hypothalamus and hindbrain. This review discusses the major known gut- and adipose tissue-derived hormones involved in the regulation of food intake and energy homeostasis and their serum levels in childhood obesity before and after weight loss as well as their relationship to consequences of obesity. Since most of the changes of gastrointestinal hormones and adipokines normalize in weight loss, pharmacological interventions based on these hormones will likely not solve the obesity epidemic in childhood. However, a better understanding of the pathways of body weight- and food intake-regulating gut- and adipose tissue-derived hormones will help to find new strategies to treat obesity and its consequences.

Topics: Adipokines; Adipose Tissue; Child; Cholecystokinin; Diabetes Mellitus, Type 2; Dipeptides; Enteropeptidase; Exercise; Glucagon-Like Peptide 1; Health Behavior; Health Promotion; Humans; Hypothalamus; Life Style; Obesity; Oxyntomodulin; Pancreatic Polypeptide; Rhombencephalon; Weight Loss

Sugar consumption is associated with a whole range of negative health effects and should be reduced and the natural sweetener xylitol might be helpful in achieving this goal. The present study was conducted as a randomized, placebo-controlled, double-blind, cross-over trial. Twelve healthy, lean volunteers received intragastric solutions with 7, 17 or 35 g xylitol or tap water on four separate days. We examined effects on: gut hormones, glucose, insulin, glucagon, uric acid, lipid profile, as well as gastric emptying rates, appetite-related sensations and gastrointestinal symptoms. We found: (i) a dose-dependent stimulation of cholecystokinin (CCK), active glucagon-like peptide-1 (aGLP-1), peptide tyrosine tyrosine (PYY)-release, and decelerated gastric emptying rates, (ii) a dose-dependent increase in blood glucose and insulin, (iii) no effect on motilin, glucagon, or glucose-dependent insulinotropic peptide (GIP)-release, (iv) no effect on blood lipids, but a rise in uric acid, and (v) increased bowel sounds as only side effects. In conclusion, low doses of xylitol stimulate the secretion of gut hormones and induce a deceleration in gastric emptying rates. There is no effect on blood lipids and only little effect on plasma glucose and insulin. This combination of properties (low-glycemic sweetener which stimulates satiation hormone release) makes xylitol an attractive candidate for sugar replacement.

Topics: Adult; Blood Glucose; Cholecystokinin; Cross-Over Studies; Dipeptides; Double-Blind Method; Female; Gastric Emptying; Gastric Inhibitory Polypeptide; Gastrointestinal Hormones; Glucagon; Glucagon-Like Peptide 1; Humans; Insulin; Lipids; Male; Sweetening Agents; Uric Acid; Xylitol; Young Adult

Polydextrose (PDX) reduces subsequent energy intake (EI) when administered at midmorning in single-blind trials of primarily normal-weight men. However, it is unclear if this effect also occurs when PDX is given at breakfast time. Furthermore, for ecological validity, it is desirable to study a female population, including those at risk for obesity. We studied the effects of PDX, served as part of a breakfast or midmorning preload, on subsequent EI and other appetite-related parameters in healthy normal-weight and overweight females. Per earlier studies, the primary outcome was defined as the difference in subsequent EI when PDX was consumed at midmorning versus placebo. Thirty-two volunteers were enrolled in this acute, double-blind, placebo-controlled, randomized, and crossover trial to examine the effects of 12.5 g of PDX, administered as part of a breakfast or midmorning preload, on subsequent EI, subjective feelings of appetite, well-being, and mood. Gastric emptying rates and the blood concentrations of glucose, insulin, cholecystokinin, ghrelin, glucagon-like peptide 1 (GLP-1), and peptide tyrosine-tyrosine were measured in the group that received PDX as part of their breakfast. There were no differences in EI between volunteers who were fed PDX and placebo. PDX intake with breakfast tended to elevate blood glucose (P = 0.06) during the postabsorptive phase, significantly lowered insulin by 15.7% (P = 0.04), and increased GLP-1 by 39.9% (P = 0.02); no other effects on blood parameters or gastric emptying rates were observed. PDX intake at midmorning reduced hunger by 31.4% during the satiation period (P = 0.02); all other subjective feelings of appetite were unaffected. Volunteers had a uniform mood profile during the study. PDX was well tolerated, causing one mild adverse event throughout the trial.

Topics: Adult; Appetite; Blood Glucose; Breakfast; Cholecystokinin; Cross-Over Studies; Dipeptides; Double-Blind Method; Eating; Energy Intake; Female; Food Additives; Gastric Emptying; Ghrelin; Glucagon-Like Peptide 1; Glucans; Humans; Hunger; Overweight; Postprandial Period; Satiation; Young Adult

Weight loss after pharmacotherapy varies greatly. We aimed to examine associations of quantitative gastrointestinal and psychological traits with obesity, and to validate the ability of these traits to predict responses of obese individuals to pharmacotherapy.. In a prospective study, we measured gastric emptying of solids and liquids, fasting and postprandial gastric volume, satiation by nutrient drink test (volume to fullness and maximal tolerated volume), satiety after an ad libitum buffet meal, gastrointestinal hormones, and psychological traits in 328 normal-weight, overweight, or obese adults. We also analyzed data from 181 previously studied adults to assess associations betwecen a subset of traits with body mass index and waist circumference. Latent dimensions associated with overweight or obesity were appraised by principal component analyses. We performed a proof of concept, placebo-controlled trial of extended-release phentermine and topiramate in 24 patients to validate associations between quantitative traits and response to weight-loss therapy.. In the prospective study, obesity was associated with fasting gastric volume (P = .03), accelerated gastric emptying (P < .001 for solids and P = .011 for liquids), lower postprandial levels of peptide tyrosine tyrosine (P = .003), and higher postprandial levels of glucagon-like peptide 1 (P < .001). In a combined analysis of data from all studies, obesity was associated with higher volume to fullness (n = 509; P = .038) and satiety with abnormal waist circumference (n = 271; P = .016). Principal component analysis identified latent dimensions that accounted for approximately 81% of the variation among overweight and obese subjects, including satiety or satiation (21%), gastric motility (14%), psychological factors (13%), and gastric sensorimotor factors (11%). The combination of phentermine and topiramate caused significant weight loss, slowed gastric emptying, and decreased calorie intake; weight loss in response to phentermine and topiramate was significantly associated with calorie intake at the prior satiety test.. Quantitative traits are associated with high body mass index; they can distinguish obesity phenotypes and, in a proof of concept clinical trial, predicted response to pharmacotherapy for obesity. ClinicalTrials.gov Number: NCT01834404.

Topics: Adult; Aged; Anti-Obesity Agents; Anxiety; Body Image; Body Mass Index; Cholecystokinin; Cohort Studies; Delayed-Action Preparations; Depression; Dipeptides; Drug Combinations; Fasting; Female; Fructose; Gastric Emptying; Ghrelin; Glucagon-Like Peptide 1; Humans; Male; Middle Aged; Obesity; Organ Size; Overweight; Peptide YY; Phentermine; Postprandial Period; Principal Component Analysis; Prospective Studies; Satiation; Self Efficacy; Stomach; Topiramate; Treatment Outcome

Recent evidence suggests bile acids (BAs) are involved in the glycemic control via TGR5 activation with the subsequent release of gut peptides and farnesoid X receptor activation with ensuing release of fibroblast growth factors (FGFs).. We hypothesized that intraduodenal infusions of chenodeoxycholic acid (CDCA) would stimulate FGF and gut peptide secretion, thereby positively influencing glucose homeostasis.. This randomized, double-blind, placebo-controlled, crossover trial included 12 healthy volunteers who received intraduodenal infusions (2.0 mL/min for 180 minutes) of saline, CDCA (5 or 15 mmol/L), and a fatty acid (sodium oleate), either alone or with 5 mmol/L CDCA. After 60 minutes, an oral glucose tolerance test (oGTT) was performed.. Plasma levels of glucagon-like peptide-1 (GLP-1), peptide tyrosine tyrosine, cholecystokinin (CCK), total BAs, FGF19, FGF21, C-peptide, insulin, glucose, and glucagon were measured.. Within the first 60 minutes, high-concentration CDCA induced a small but significant increase in GLP-1 and CCK secretion (P = .016 and P =.011), whereas plasma C-peptide, insulin, and glucose were not affected. Attenuated C-peptide and insulin release was observed after the oGTT with 15 mmol/L CDCA (P = .013 and P =.011). Plasma BA and FGF19 levels significantly increased after CDCA administration (P = .001 and P < .001).. CDCA modulates GLP-1 and CCK secretion; the effect is small and does not influence glucose levels. The marked increase in plasma BAs and the attenuated insulin release after the oGTT indicate the role of BAs in glycemic control, independent of the incretin axis, and suggest involvement of farnesoid X receptor activation pathways.

Topics: Adult; Bile Acids and Salts; C-Peptide; Chenodeoxycholic Acid; Cholecystokinin; Dipeptides; Double-Blind Method; Fibroblast Growth Factors; Glucagon; Glucagon-Like Peptide 1; Humans; Insulin; Male; Young Adult

Topics: Appetite; Cholecystokinin; Dipeptides; Dyspepsia; Ghrelin; Humans; Intestinal Mucosa

Hypoxia has been shown to reduce energy intake and lead to weight loss, but the underlying mechanisms are unclear. The aim was therefore to assess changes in eating after rapid ascent to 4,559 m and to investigate to what extent hypoxia, acute mountain sickness (AMS), food preferences and satiation hormones influence eating behavior.. Participants (n = 23) were studied at near sea level (Zurich (ZH), 446 m) and on two days after rapid ascent to Capanna Margherita (MG) at 4,559 m (MG2 and MG4). Changes in appetite, food preferences and energy intake in an ad libitum meal were assessed. Plasma concentrations of cholecystokinin, peptide tyrosine-tyrosine, gastrin, glucagon and amylin were measured. Peripheral oxygen saturation (SpO(2)) was monitored, and AMS assessed using the Lake Louis score.. Energy intake from the ad libitum meal was reduced on MG2 compared to ZH (643 ± 308 vs. 952 ± 458 kcal, p = 0.001), but was similar to ZH on MG4 (890 ± 298 kcal). Energy intake on all test days was correlated with hunger/satiety scores prior to the meal and AMS scores on MG2 but not with SpO(2) on any of the 3 days. Liking for high-fat foods before a meal predicted subsequent energy intake on all days. None of the satiation hormones showed significant differences between the 3 days.. Reduced energy intake after rapid ascent to high altitude is associated with AMS severity. This effect was not directly associated with hypoxia or changes in gastrointestinal hormones. Other peripheral and central factors appear to reduce food intake at high altitude.

Topics: Adult; Altitude; Altitude Sickness; Appetite; Body Mass Index; Cholecystokinin; Dexamethasone; Dipeptides; Eating; Energy Intake; Feeding Behavior; Female; Food Preferences; Gastrins; Glucagon; Humans; Hunger; Islet Amyloid Polypeptide; Male; Middle Aged; Satiation; Surveys and Questionnaires; Weight Loss; Young Adult

The regional distribution and relative frequency of endocrine cells in the gastrointestinal tract of the camel, Camelus bactrianus, were investigated using immunohistochemical methods. Ten types of immunoreactive (IR) endocrine cells were identified in this study. Among these cell types, only serotonin- and somatostatin-IR cells were detected in almost all regions of the gastrointestinal tract. Most of the cell types showed peak density in the pyloric gland region. The others showed restricted distribution: gastrin, cholecystokinin (CCK), motilin, bovine pancreatic polypeptide (BPP), and (gastric) substance P in the stomach; gastrin, CCK, BPP, gastric inhibitory polypeptide (GIP), glucagon, peptide tyrosine tyrosine (PYY) and substance P in the small intestine; and CCK, motilin, BPP, and PYY in the large intestine. Fundamentally the distribution pattern of endocrine cells in the gastrointestinal tract of the camel is similar to that of cattle. The distribution and frequency of endocrine cells in the glandular sac region are the same as those of the cardiac gland.

Topics: Animals; Camelus; Cholecystokinin; Digestive System; Dipeptides; Enteroendocrine Cells; Female; Gastric Inhibitory Polypeptide; Gastrins; Glucagon; Immunohistochemistry; Male; Motilin; Serotonin; Somatostatin; Substance P

Peptide tyrosine tyrosine/pancreatic polypeptide (PYY/PP)- and C-terminal gastrin/cholecystokinin (G/CCK)-immunoreactive cells were investigated in the intestine of the lizard Podarcis hispanica, using immunocytochemistry with light and electron microscopy. Immunolabeling of consecutive semithin sections revealed coexistence of PYY/PP- and C-terminal G/CCK-like substances in some cells, while in others only PYY/PP or G/CCK immunoreactivity was found. Appropriate absorption controls excluded cross-reactivity between the antisera used. Ultrastructurally G/CCK+, PYY/PP+ cells were similar to G/CCK+, PYY/PP- cells but different from PYY/PP+, G/CCK- cells. Although virtually nothing is known concerning the physiological effects of these peptides in reptiles, their colocalization in the same cells in the intestine of Podarcis hispanica suggests a close relationship between them in the regulation of the digestive process.

Topics: Amino Acid Sequence; Animals; Cholecystokinin; Cross Reactions; Dipeptides; Gastrins; Immunohistochemistry; Intestine, Small; Lizards; Microscopy, Electron; Molecular Sequence Data; Pancreatic Polypeptide

To investigate the enterotrophic effects of bolus doses of long chain triglycerides, two groups of eight female Wistar rats were fed identical diets with 48.2% total calories as the essential fatty acid rich oil Efamol. To one group the oil was given in twice daily bolus doses by gavage, while for the other group the oil was mixed with the remainder of the feed and thus consumed over 24 hours. The animals were killed after 20 to 22 days. Bolus dosing significantly increased parameters of mucosal mass along the length of the small intestine in association with an increase in two hour accumulation of vincristine arrested metaphases in small intestinal crypts. In a second experiment, four replicate studies were carried out, each involving two groups of 12 rats respectively fed as described above. After 21 days one animal from each group was killed every two hours, providing regular plasma samples over 24 hours for measurement of gastrin, cholecystokinin, peptide tyrosine-tyrosine and enteroglucagon. Bolus dosing markedly enhanced release of peptide tyrosine-tyrosine and enteroglucagon, but not of gastrin or cholecystokinin. Thus, the enhanced enterotrophic effects of bolus doses of long chain triglycerides could be mediated by release of a distally located gut peptide, perhaps enteroglucagon.

Topics: Animals; Cholecystokinin; Dietary Fats; Dipeptides; Energy Intake; Fatty Acids, Essential; Female; gamma-Linolenic Acid; Gastrins; Gastrointestinal Hormones; Glucagon-Like Peptides; Intestinal Mucosa; Intestine, Small; Linoleic Acids; Oenothera biennis; Organ Size; Plant Oils; Rats; Rats, Inbred Strains