Peptide YY Concentrations Research Articles

Correlations of circulating peptide YY and ghrelin with body weight, rate of weight gain, and time required to achieve the recommended daily intake in preterm infants

The objective was to elucidate the relationships between serum concentrations of the gut hormone peptide YY (PYY) and ghrelin and growth development in infants for potential application to the clinical observation index. Serum concentrations of PYY and ghrelin were measured using radioimmunoassay from samples collected at the clinic. For each patient, gestational age, birth weight, time required to return to birth weight, rate of weight gain, time required to achieve recommended daily intake (RDI) standards, time required for full-gastric feeding, duration of hospitalization, and time of administration of total parenteral nutrition were recorded. Serum PYY and ghrelin concentrations were significantly higher in the preterm group (N = 20) than in the full-term group (N = 20; P < 0.01). Within the preterm infant group, the serum concentrations of PYY and ghrelin on postnatal day (PND) 7 (ghrelin = 1485.38 ± 409.24; PYY = 812.37 ± 153.77 ng/L) were significantly higher than on PND 1 (ghrelin = 956.85 ± 223.09; PYY = 545.27 ± 204.51 ng/L) or PND 3 (ghrelin = 1108.44 ± 351.36; PYY = 628.96 ± 235.63 ng/L; P < 0.01). Both serum PYY and ghrelin concentrations were negatively correlated with body weight, and the degree of correlation varied with age. Serum ghrelin concentration correlated negatively with birth weight and positively with the time required to achieve RDI (P < 0.05). In conclusion, serum PYY and ghrelin concentrations reflect a negative energy balance, predict postnatal growth, and enable compensation. Further studies are required to elucidate the precise concentration and roles of PYY and ghrelin in newborns and to determine the usefulness of measuring these hormones in clinical practice.

Fasting plasma peptide YY concentrations are increased in patients with major depression who associate weight loss.

Many patients with major depression refer a decreased appetite and weight loss among their symptoms. Peptide YY (PYY) and ghrelin belong to the family of peptides of the gut-brain axis implicated in the regulation of appetite and energy metabolism. PYY stimulates a powerful central satiety response and ghrelin increases food intake and weight gain. Brain-derived neurotrophic factor (BDNF) also contributes to the central control of food intake as an anorexigenic factor. To study fasting plasma total and acylated ghrelin, plasma PYY and serum BDNF levels in patients with major depression with weight loss as one of their symptoms and compare them with matched healthy controls. Fifteen adult patients, 9 male and 6 female, with recent diagnosis of major depression, and 16 healthy adult subjects, matched by age and anthropometric parameters were studied. All depressed patients referred weight loss and were not under antidepressant therapy. Fasting total PYY, total ghrelin and acylated ghrelin and BDNF were determined. Fasting total PYY was higher in patients than controls (2.01±0.09 vs 1.29±0.16 pmol/l). There were no differences in fasting total ghrelin, acylated ghrelin or BDNF levels. Major depressed patients, with weight loss at diagnosis, showed higher fasting plasma PYY levels that could contribute to their reduced appetite.

Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability of JNJ-38431055, a Novel GPR119 Receptor Agonist and Potential Antidiabetes Agent, in Healthy Male Subjects

The incidence of type 2 diabetes mellitus is increasing worldwide. Several G-protein-coupled receptor agonists are being studied for their efficacy as antidiabetes agents. JNJ-38431055 is a novel, potent, and orally available selective agonist of the glucose-dependent insulinotropic (GPR119) receptor. Double-blind, randomized, placebo-controlled studies were conducted to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of single oral doses of JNJ-38431055 (2.5-800 mg) in healthy male volunteers. The systemic exposure of JNJ-38431055 in plasma increased in proportion to the dose and was not influenced by coadministration of food. The terminal elimination half-life was ~13 h when administered as an oral suspension formulation. JNJ-38431055 was well tolerated and was not associated with hypoglycemia. As compared with placebo, single-dose oral JNJ-38431055 increased postmeal plasma glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and peptide YY (PYY) concentrations but did not significantly decrease glucose excursion or increase insulin secretion. However, in a graded glucose infusion study, JNJ-38431055 was shown to induce a higher insulin secretion rate (ISR) relative to placebo at elevated plasma glucose levels. These studies provide evidence for the potential efficacy of JNJ-38431055 as an antidiabetes agent in humans.

Ghrelin and PYY levels in adolescents with severe obesity: effects of weight loss induced by long-term exercise training and modified food habits

This study investigated (a) changes in ghrelin and peptide YY (PYY) concentrations during a weight reduction programme and (b) baseline ghrelin and PYY levels as predictors of weight loss in 32 severely obese adolescents (BMI z score = 4.1). Subjects spent an academic year in an institution for childhood obesity. Fasting ghrelin and PYY, leptin, insulin levels and insulin resistance were measured at baseline (month 0) and during the programme (months 3, 6, 9). In addition, 15 normal-weight teenagers served as reference for the baseline assessments. At baseline, obese teenagers had lower ghrelin and PYY concentrations than normal-weight adolescents (P < 0.05). Moreover, they showed significantly higher leptin, insulin levels and homeostasis model assessment (HOMA) (P < 0.0001). During the lifestyle modification, there was a significant decrease in body weight among obese teenagers, associated with an increase in ghrelin (apparent from month 6; P < 0.05), a decrease in leptin (from month 3; P < 0.05) and a decrease in insulin and HOMA (from month 3; P < 0.0001), without any significant change in PYY. Anthropometrical changes were correlated neither with baseline ghrelin levels nor with changes in ghrelin and PYY after the lifestyle modification. However, higher baseline PYY tended to correlate with greater anthropometrical changes (P < 0.1). In adolescents with severe obesity, a long-term combination of supervised aerobic exercises and a balanced diet led to weight reduction and increased ghrelin concentrations, without any change in PYY concentrations. Moreover, baseline PYY concentrations might be considered as predictors of weight loss.

Changes in Differential Functional Magnetic Resonance Signals in the Rodent Brain Elicited by Mixed-Nutrient or Protein-Enriched Meals

The hypothalamus and brain stem have important roles in regulating food intake; the roles of other nonhomeostatic centers in detecting nutrient content of ingested food have been poorly characterized. We used blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) to map brain regions that are responsive to intragastric infusion of isocaloric amounts of a mixed nutrient or protein, and assessed the role of blood glucose in the observed BOLD signal changes. Brain images were acquired, using a 9.4 T MRI system, from anesthetized rats during intragastric infusion of saline (n = 7), or 12 kcal of a mixed nutrient (n = 13) or protein (n = 6). Nutrient-induced changes in blood parameters and the effects of intravenous infusion of saline or glucose (n = 5/treatment) on BOLD fMRI signal changes were also evaluated. Intragastric nutrient infusion reduced the BOLD fMRI signal intensity in homeostatic (hypothalamus, nucleus tractus solitarius) and nonhomeostatic (thalamus, hippocampus, caudate putamen, cerebral cortex, cerebellum) centers; these effects were mimicked qualitatively by intravenous glucose. In contrast to a mixed meal, protein load reduced the BOLD fMRI signal in the amygdala. BOLD fMRI signal changes were inversely correlated with circulating concentrations of amylin, insulin, peptide YY, and glucagon-like peptide-1. The caloric content of a meal is signaled from the gut to the brain and affects activity in homeostatic and non-homeostatic centers; blood glucose concentrations have an important role. The satiety effects of protein are associated with activity changes specifically in the amygdala.

Exercising women with menstrual disturbances consume low energy dense foods and beverages

Women with exercise-associated menstrual cycle disturbances (EAMD) restrict energy intake. Reducing energy density (ED; kcals·g(-1) of food or beverage) may be a strategy employed by EAMD women to maintain lower energy intake. The purpose of this study was 3-fold: to determine whether EAMD women consume low ED diets; to identify food groups associated with low ED; and to determine concentrations of total peptide YY (PYY), a satiety factor. Twenty-five active females were divided into 2 groups, according to menstrual status: EAMD (n = 12) and ovulatory controls (OV) (n = 13). Two 3-day diet records were analyzed for ED and other parameters. Body composition, fitness, resting metabolic rate, and PYY were measured. Groups did not differ in age, age of menarche, body mass index, maximal aerobic capacity(), body fat (%), or amount of exercise per week. For fat mass (12.4± 1.7 vs. 14.9± 3.5kg; p = 0.046), energy availability (28.8± 11.5 vs. 42.1± 9.2kcal·kg(-1) FFM; p = 0.006), and energy intake (29.8± 9.2 vs. 36.3± 10.6 kcals·kg(-1) BW; p = 0.023), EAMD was lower than OV. ED was lower in EAMD than in OV (0.77± 0.06 vs. 1.06± 0.09kcal·g(-1); p = 0.018) when all beverages were included, but not when noncaloric beverages were excluded. Vegetable (p = 0.047) and condiment (p = 0.014) consumption and fasting PYY (pg·mL(-1)) (p = 0.006) were higher in EAMD. EAMD ate a lower ED diet through increased vegetable, condiment, and noncaloric beverage consumption, and exhibited higher PYY concentrations. These behaviors may represent a successful strategy to restrict calories and maximize satiety.

Slowly and Rapidly Digested Fat Emulsions Are Equally Satiating but Their Triglycerides Are Differentially Absorbed and Metabolized in Humans1,2

Little is known about the effect of dietary fat emulsion microstructure on plasma TG concentrations, satiety hormones, and food intake. The aim of this study was to structure dietary fat to slow digestion and flatten postprandial plasma TG concentrations but not increase food intake. Emulsions were stabilized by egg lecithin (control), sodium sterol lactylate, or sodium caseinate/monoglyceride (CasMag) with either liquid oil or a liquid oil/solid fat mixture. In a randomized, double-blind, crossover design, 4 emulsions containing 30 g of fat in a 350-mL preload were consumed by 10 men and 10 women (BMI = 25.1 ± 2.8 kg/m2; age = 58.8 ± 4.8 y). Pre- and postprandial plasma TG, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide YY (PYY) concentrations and food intake were measured. In a second experiment in a subset of the participants (n = 8, 4 men and 4 women), 13C-labeled mixed TG was incorporated into 2 different emulsions and breath 13C was measured over 6 h. In the first experiment, the postprandial rise in plasma TG concentrations following the CasMag-stabilized emulsion containing 30% solid fat was lower than all other emulsions at 90 and 120 min (P < 0.05). Plasma CCK (P < 0.0001), GLP-1 (P < 0.01), and PYY (P < 0.001) concentrations were also reduced following this emulsion compared with control. Food intake at a test meal, eaten 3 h after the preload, did not differ among the emulsions. In the second experiment, when measured by the 13C breath test, 25% of the TG in the CasMag emulsion was absorbed and metabolized compared with control. In conclusion, fat can be structured to decrease its effect on plasma TG concentrations without increasing food intake.

Effects of oral ingestion of sucralose on gut hormone response and appetite in healthy normal-weight subjects

The sweet-taste receptor (T1r2+T1r3) is expressed by enteroendocrine L-cells throughout the gastrointestinal tract. Application of sucralose (a non-calorific, non-metabolisable sweetener) to L-cells in vitro stimulates glucagon-like peptide (GLP)-1 secretion, an effect that is inhibited with co-administration of a T1r2+T1r3 inhibitor. We conducted a randomised, single-blinded, crossover study in eight healthy subjects to investigate whether oral ingestion of sucralose could stimulate L-cell-derived GLP-1 and peptide YY (PYY) release in vivo. Fasted subjects were studied on 4 study days in random order. Subjects consumed 50 ml of either water, sucralose (0.083% w/v), a non-sweet, glucose-polymer matched for sweetness with sucralose addition (50% w/v maltodextrin+0.083% sucralose) or a modified sham-feeding protocol (MSF=oral stimulation) of sucralose (0.083% w/v). Appetite ratings and plasma GLP-1, PYY, insulin and glucose were measured at regular time points for 120 min. At 120 min, energy intake at a buffet meal was measured. Sucralose ingestion did not increase plasma GLP-1 or PYY. MSF of sucralose did not elicit a cephalic phase response for insulin or GLP-1. Maltodextrin ingestion significantly increased insulin and glucose compared with water (P<0.001). Appetite ratings and energy intake were similar for all groups. At this dose, oral ingestion of sucralose does not increase plasma GLP-1 or PYY concentrations and hence, does not reduce appetite in healthy subjects. Oral stimulation with sucralose had no effect on GLP-1, insulin or appetite.

JTT-130, a Novel Intestine-Specific Inhibitor of Microsomal Triglyceride Transfer Protein, Suppresses Food Intake and Gastric Emptying with the Elevation of Plasma Peptide YY and Glucagon-Like Peptide-1 in a Dietary Fat-Dependent Manner

The microsomal triglyceride transfer protein (MTP) takes part in the mobilization and secretion of triglyceride-rich lipoproteins from enterocytes and hepatocytes. In this study, we investigated the effects of diethyl-2-({3-dimethylcarbamoyl-4-[(4'-trifluoromethylbiphenyl-2-carbonyl) amino] phenyl}acetyloxymethyl)-2-phenylmalonate (JTT-130), a novel intestine-specific MTP inhibitor, on food intake, gastric emptying, and gut peptides using Sprague-Dawley rats fed 3.1% fat, 13% fat, or 35% fat diets. JTT-130 treatment suppressed cumulative food intake and gastric emptying in rats fed a 35% fat diet, but not a 3.1% fat diet. In rats fed a 13% fat diet, JTT-130 treatment decreased cumulative food intake but not gastric emptying. In addition, treatment with orlistat, a lipase inhibitor, completely abolished the reduction of food intake and gastric emptying by JTT-130 in rats fed a 35% fat diet. On the other hand, JTT-130 treatment increased the plasma concentrations of gut peptides, peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) but not cholecystokinin, in the portal vein in rats fed a 35% fat diet. These elevations in PYY and GLP-1 were also abolished by treatment with orlistat. Furthermore, JTT-130 treatment in rats fed a 35% fat diet increased the contents of triglycerides and free fatty acids in the intestinal lumen, which might contribute to the elevation of PYY and GLP-1 levels. The present findings indicate that JTT-130 causes satiety responses, decreased food intake, and gastric emptying in a dietary fat-dependent manner, with enhanced production of gut peptides such as PYY and GLP-1 from the intestine.

The Influence of Higher Protein Intake and Greater Eating Frequency on Appetite Control in Overweight and Obese Men

The purpose of this study was to determine the effects of dietary protein intake and eating frequency on perceived appetite, satiety, and hormonal responses in overweight/obese men. Thirteen men (age 51 +/- 4 years; BMI 31.3 +/- 0.8 kg/m(2)) consumed eucaloric diets containing normal protein (79 +/- 2 g protein/day; 14% of energy intake as protein) or higher protein (138 +/- 3 g protein/day; 25% of energy intake as protein) equally divided among three eating occasions (3-EO; every 4 h) or six eating occasions (6-EO; every 2 h) on four separate days in randomized order. Hunger, fullness, plasma glucose, and hormonal responses were assessed throughout 11 h. No protein x eating frequency interactions were observed for any of the outcomes. Independent of eating frequency, higher protein led to greater daily fullness (P < 0.05) and peptide YY (PYY) concentrations (P < 0.05). In contrast, higher protein led to greater daily ghrelin concentrations (P < 0.05) vs. normal protein. Protein quantity did not influence daily hunger, glucose, or insulin concentrations. Independent of dietary protein, 6-EO led to lower daily fullness (P < 0.05) and PYY concentrations (P < 0.05). The 6-EO also led to lower glucose (P < 0.05) and insulin concentrations (P < 0.05) vs. 3-EO. Although the hunger-related perceived sensations and hormonal responses were conflicting, the fullness-related responses were consistently greater with higher protein intake but lower with increased eating frequency. Collectively, these data suggest that higher protein intake promotes satiety and challenge the concept that increasing the number of eating occasions enhances satiety in overweight and obese men.

Effects of Exercise on the Levels of Peptide YY and Ghrelin

Ghrelin and peptide YY (PYY) are brain-gut peptides that have a variety of physiological functions and are involved in energy regulation. Thus far, abnormalities in the expression and secretion of ghrelin and PYY are known to occur in lifestyle-related diseases, including obesity, and the improvement of these abnormalities has become an important challenge. Exercise has recently been reported to influence ghrelin and PYY concentrations. Exercise increases the PYY secretion. The effects of exercise on ghrelin levels vary with the study subject, timing of exercise, and duration of exercise. Here, we review the findings of recent studies on the association of PYY and ghrelin with obesity, particularly, on the influence of exercise on PYY and ghrelin levels.

Semisolid meal enriched in oat bran decreases plasma glucose and insulin levels, but does not change gastrointestinal peptide responses or short-term appetite in healthy subjects

Background and aims Dietary fibre (DF) may play an important role in weight control. The amount, type and way of processing of DF modify food structure and subsequent postprandial appetitive, metabolic and hormonal effects, but current understanding about the magnitude of effects that specific types and amounts of DF exert are still poorly understood. Methods and results We investigated the effects of wheat and oat brans alone and as combination in semisolid food matrix on postprandial appetite profile and gastrointestinal (GI) hormonal responses. Twenty healthy, normal-weight subjects (5 male/15 female, aged 23.3 ± 0.85 y) participated in the study. Isoenergetic and isovolumic (1250 kJ, 300 g) puddings with different insoluble and soluble DF content were tested in a randomised order: pudding with 1) no added fibre, 2) 10 g wheat bran DF, 3) 10 g oat bran DF and 4) combination including 5 g wheat bran DF + 5 g oat bran DF. Blood samples were drawn before and 15, 30, 45, 60, 90, 120 and 180 min after the test meals to determine plasma glucose, ghrelin, peptide YY (PYY) and serum insulin concentrations. Subjective profiles of appetite were assessed using visual analogue scales (VAS). Plasma glucose ( P = 0.001) and serum insulin ( P < 0.001) responses were the lowest after the pudding with the greatest amount of β-glucan. In contrast, postprandial ghrelin or PYY responses or appetite sensations did not differ among the meals. Conclusion Oat β-glucan decreased postprandial plasma glucose and serum insulin responses, yet had no significant effects on GI peptide responses or appetite ratings.

Comparison of the Effects of Roux-en-Y Gastric Bypass and Ileal Transposition Surgeries on Food Intake, Body Weight, and Circulating Peptide YY Concentrations in Rats

Roux-en-Y gastric bypass (RYGB) surgery is one of the most effective treatments for obesity producing long-term weight loss. The anorexia and weight loss from RYGB could be due to gastric restriction, malabsorption, enhanced lower gut stimulation, increased energy expenditure, and/or other metabolic adaptations. In ileal transposition (IT) surgery, a segment of the ileum is transposed to the upper jejunum with no gastric restriction or malabsorption. Our objective is to compare the effects of RYGB and IT surgeries on food intake, body weight, and plasma concentrations of the anorexigenic lower gut hormone Peptide YY (PYY) in rats. Adult male Sprague-Dawley rats were subjected to either RYGB (n = 9), IT (n = 9) or sham surgeries (n = 16). A subset of sham animals were either pair-fed to RYGB (n = 9) or ad lib fed (n = 7) on a highly palatable mixed nutrient liquid food (Ensure). Food intake, body weight and plasma PYY concentrations were measured. The data demonstrate that (1) RYGB produces a sustained reduction in food intake and weight gain, (2) the anorexic effects of IT are relatively transient lasting for 5 weeks, (3) the reduction in weight gain resulting from IT is similar to that of animals pair-fed to RYGB, and (4) RYGB and IT surgeries are associated with elevated postprandial plasma PYY concentrations. We demonstrate in our rat models that RYGB surgery produces a greater reduction in food intake and weight gain than IT surgery, and that both surgeries are associated with enhanced plasma concentrations of Peptide YY.

A Psyllium Fiber-Enriched Meal Strongly Attenuates Postprandial Gastrointestinal Peptide Release in Healthy Young Adults

Dietary fiber (DF) and protein are essential constituents of a healthy diet and are well known for their high satiety impact. However, little is known about their influence on postprandial gastrointestinal (GI) peptide release. Our aim in this single-blind, randomized, cross-over study was to investigate the effects of DF and/or protein enrichments on satiety-related metabolic and hormonal responses. Sixteen healthy, nonobese volunteers participated in the study and ingested 1 of 5 isoenergetic test meals in a randomized order on separate days. The test meals were as follows: 1) low in protein (2.8 g) and fiber (7.6 g); 2) low in protein (2.6 g) and high in soluble fiber (psyllium, 23.0 g); 3) high in protein (soy, 19.7 g) and low in fiber (6.2 g); 4) high in protein (18.4 g) and fiber (23.0 g); and 5) white wheat bread. Serum insulin and plasma glucose, ghrelin, glucagon-like peptide 1 (GLP-1), and peptide YY (PYY) concentrations were determined for 2 h following the meals. In addition, hunger and satiety ratings were collected. Postprandial glucose, insulin, ghrelin, GLP-1, and PYY responses all differed among the meals (P ≤ 0.05). Fiber-enriched meals decreased glucose, insulin, ghrelin, and PYY responses; in addition, PYY secretion was prolonged compared with the other meals. The postprandial GLP-1 concentration was significantly suppressed after a fiber- and protein-rich meal, in contrast to the initial increases following the other meals. However, postprandial ratings of appetite were mostly similar after the test meals. In conclusion, solid meals enriched with psyllium fiber strongly modified postprandial signals arising from the GI tract.

A High‐fat vs. a Moderate‐fat Meal in Obese Boys: Nutrient Balance, Appetite, and Gastrointestinal Hormone Changes

Meal composition is a contributing factor to fat gain. In this study, we investigated the relationship between postprandial nutrient balance, satiety, and hormone changes induced by a high-fat meal vs. a moderate-fat meal. Ten prepubertal obese boys (BMI z-score range: 1.3-3.0) were recruited. Two meals (energy: 590 kcal) were compared: (i) high-fat (HF) meal: 12% protein, 52% fat, 36% carbohydrates; (ii) moderate-fat (MF) meal: 12% protein, 27% fat, 61% carbohydrates. Pre- and postprandial (5 h) substrate oxidation (indirect calorimetry), appetite (visual analogue scale), biochemical parameters and gastrointestinal hormone concentrations were measured. Carbohydrate balance was significantly (P < 0.001) lower (31.3 (5.7) g/5 h vs. 66.9 (5.9) g/5 h) and fat balance was significantly (P < 0.001) higher (11.5 (3.3) g/5 h vs. -0.7 (2.9) g/5 h) after HF than MF meal. Appetite (area under the curve (AUC)) was significantly reduced after an MF than an HF meal (494 (55) cm.300 min vs. 595 (57) cm.300 min, P < 0.05). Postprandial triglyceride concentration (AUC) was significantly (P < 0.05) higher after an HF than an MF meal: 141.1 (30.3) mmol.300 min/l vs. 79.3 (23.8) mmol.300 min/l, respectively. Peptide YY (PYY), cholecystokinin (CCK), and ghrelin concentrations (AUC) were not significantly different after an HF and MF meal. Glucagon-like peptide-1 (GLP-1) was significantly (P < 0.05) higher after an HF than after an MF meal (72.3 (9.8) ng/ml vs. 22.7 (7.6) ng/ml, respectively), but it did not affect subjective appetite. In conclusion, an MF meal induced a better postprandial metabolic nutrient balance, triglyceride levels, and appetite suppression than an HF meal. Gastrointestinal hormones were not related to clinically assessed hunger suppression after both meals.

Actions of prolonged ghrelin infusion on gastrointestinal transit and glucose homeostasis in humans

Ghrelin is produced by enteroendocrine cells in the gastric mucosa and stimulates gastric emptying in healthy volunteers and patients with gastroparesis in short-term studies. The aim of this study was to evaluate effects of intravenous ghrelin on gastrointestinal motility and glucose homeostasis during a 6-h infusion in humans. Ghrelin (15 pmol kg(-1) min(-1)) or saline was infused intravenously for 360 min after intake of radio-opaque markers, acetaminophen, and lactulose after a standardized breakfast in 12 male volunteers. Gastric emptying, orocecal transit, colonic transit, postprandial plasma concentrations of glucose, insulin, glucagon-like peptide-1 (GLP-1), and peptide YY were assessed. In vitro studies of gastrointestinal muscle contractility were performed. The gastric emptying rate was faster for ghrelin compared to saline (P = 0.002) with a shorter half-emptying time (50.3 +/- 3.9 vs 59.9 +/- 4.4 min, P = 0.004). There was no effect of ghrelin on orocecal or colonic transit. Postprandial elevations of plasma glucose, insulin, and GLP-1 occurred 15 min earlier and were higher with ghrelin. The insulinogenic index did not change during ghrelin infusion. Basal in vitro contractility was unaffected by ghrelin. The effect of a 6-h ghrelin infusion on gastrointestinal motility is limited to the stomach without affecting orocecal or colonic transit. Plasma glucose, insulin, and GLP-1 are elevated postprandially, probably as a result of the hastened gastric emptying. Changes in glucose homeostasis as a consequence of stimulated gastric emptying and hormone release, need to be taken into account in the use of pharmacological stimulants for the treatment of motility disorders.

Bench-to-bedside review: The gut as an endocrine organ in the critically ill

In health, hormones secreted from the gastrointestinal tract have an important role in regulating gastrointestinal motility, glucose metabolism and immune function. Recent studies in the critically ill have established that the secretion of a number of these hormones is abnormal, which probably contributes to disordered gastrointestinal and metabolic function. Furthermore, manipulation of endogenous secretion, physiological replacement and supra-physiological treatment (pharmacological dosing) of these hormones are likely to be novel therapeutic targets in this group. Fasting ghrelin concentrations are reduced in the early phase of critical illness, and exogenous ghrelin is a potential therapy that could be used to accelerate gastric emptying and/or stimulate appetite. Motilin agonists, such as erythromycin, are effective gastrokinetic drugs in the critically ill. Cholecystokinin and peptide YY concentrations are elevated in both the fasting and postprandial states, and are likely to contribute to slow gastric emptying. Accordingly, there is a rationale for the therapeutic use of their antagonists. So-called incretin therapies (glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide) warrant evaluation in the management of hyperglycaemia in the critically ill. Exogenous glucagon-like peptide-2 (or its analogues) may be a potential therapy because of its intestinotropic properties.

Gut microbiota fermentation of prebiotics increases satietogenic and incretin gut peptide production with consequences for appetite sensation and glucose response after a meal

BackgroundWe have previously shown that gut microbial fermentation of prebiotics promotes satiety and lowers hunger and energy intake in humans. In rodents, these effects are associated with an increase in plasma gut peptide concentrations, which are involved in appetite regulation and glucose homeostasis. ObjectiveOur aim was to examine the effects of prebiotic supplementation on satiety and related hormones during a test meal for human volunteers by using a noninvasive micromethod for blood sampling to measure plasma gut peptide concentrations. DesignThis study was a randomized, double-blind, parallel, placebo-controlled trial. A total of 10 healthy adults (5 men and 5 women) were randomly assigned to groups that received either 16 g prebiotics/d or 16 g dextrin maltose/d for 2 wk. Meal tolerance tests were performed in the morning to measure the following: hydrogen breath test, satiety, glucose homeostasis, and related hormone response. ResultsWe show that the prebiotic treatment increased breath-hydrogen excretion (a marker of gut microbiota fermentation) by ≈3-fold and lowered hunger rates. Prebiotics increased plasma glucagon-like peptide 1 and peptide YY concentrations, whereas postprandial plasma glucose responses decreased after the standardized meal. The areas under the curve for plasma glucagon-like peptide 1 and breath-hydrogen excretion measured after the meal (0–60 min) were significantly correlated (r = 0.85, P = 0.007). The glucose response was inversely correlated with the breath-hydrogen excretion areas under the curve (0–180 min; r = −0.73, P = 0.02). ConclusionPrebiotic supplementation was associated with an increase in plasma gut peptide concentrations (glucagon-like peptide 1 and peptide YY), which may contribute in part to changes in appetite sensation and glucose excursion responses after a meal in healthy subjects.

Acute effect of environmental temperature during exercise on subsequent energy intake in active men

BackgroundThe performance of exercise while immersed in cold water has been shown to influence energy intake in the subsequent meal. However, the effect of ambient temperature during land-based exercise is not known. ObjectivesOur aims were to investigate the effect of exercise performed in the heat on energy intake in the subsequent meal and to determine concentrations of circulating appetite-related hormones. DesignIn a randomized, counterbalanced design, 11 active male participants completed 3 experimental trials in a fasted state: exercise in the heat (36°C), exercise in a neutral temperature (25°C), and a resting control (25°C). The exercise trials consisted of treadmill running for 40 min at 70% ▪O2peak. After each trial, participants were presented with a buffet-type breakfast of precisely known quantity and nutrient composition, which they could consume ad libitum. ResultsEnergy intake was greater after exercise in the neutral temperature compared with the control (P = 0.021) but was similar between exercise in the heat and the control and between the 2 exercise trials. When accounting for the excess energy expended during exercise, relative energy intake during exercise in the heat was lower than the control (P = 0.002) but was similar between exercise in the neutral temperature and the control and between exercise in the heat and in the neutral temperature. The lower relative energy intake after exercise in the heat was associated with an elevated tympanic temperature and circulating concentrations of peptide YY (P < 0.05). ConclusionExercise in a neutral environmental temperature is associated with higher energy intake in the subsequent meal compared with a control, whereas exercise in the heat is not.

β-Glucan-enriched bread reduces energy intake and modifies plasma ghrelin and peptide YY concentrations in the short term

Dietary fibre consumption may help to control appetite and to reduce calorie intake. Underlying molecular mechanisms were not fully investigated. The aim of this study was to evaluate the effect of barley β-glucans on short-term appetite and on satiety-related hormones in healthy subjects. Fourteen volunteers were selected and randomly assigned to have isocaloric breakfasts including a 3% β-glucan-enriched bread (βGB) or a control bread (CB). Post-breakfast individual self-records of appetite ratings and measure of calorie intake at an ad libitum lunch as well as measure of blood glucose, insulin, ghrelin and PYY concentrations, were performed. βGB determined a significant higher reduction of hunger and increase of fullness and satiety than CB. Accordingly, a 19% reduction of energy intake at lunch subsequent to βGB consumption compared to CB, was recorded. A 23% lower AUC 60–180 of plasma ghrelin and a 16% higher total AUC of PYY response after βGB than CB consumption, independent from insulin response, was found. Glucose response was also blunted by βGB vs CB. Barley β-glucans were able to control appetite in the short term by modulating sensations and reducing energy intake. Data suggested for the first time that satiety effect of β-glucans are mediated by ghrelin and PYY.