B. Hartmann

Glucagon-Like Peptide-2 Inhibits Centrally Induced Antral Motility in Pigs

BACKGROUND Glucagon-like peptide-2 is formed from proglucagon in the intestinal L-cells and is secreted postprandially in parallel with the insulinotropic hormone GLP-1 (glucagon-like peptide-1), which in addition acts to inhibit gastric motility (enterogastrone effect) by inhibiting central parasympathetic outflow. GLP-2 has no effect on the endocrine pancreas. We here tested the hypothesis that GLP-2 acts as an enterogastrone. METHODS Fourteen anesthetized pigs with their splanchnic nerves cut were subjected to insulin hypoglycemia, and force transducers were sutured to the antrum to record motility. GLP-2 was infused intravenously in doses from 1 to 6 pmol/kg/min after the onset of antral motility in response to hypoglycemia. RESULTS Insulin hypoglycemia invariably and greatly increased the frequency and amplitude of antral phasic contractions. Infusions of GLP-2 dose dependently (1-6 pmol/kg/min) inhibited antral motility. At 2 pmol/kg/min, resulting in plasma GLP-2 concentrations of 102.5+/-19 pmol/l (normal postprandial range, 30-82 pmol/l), the motility index was inhibited by 91%+/-14%. CONCLUSIONS Both of the intestinal glucagon-like peptides may operate as hormonal transmitters of the ileal brake effect.

Impaired meal stimulated glucagon-like peptide 2 response in ileal resected short bowel patients with intestinal failure

BACKGROUND Glucagon-like peptide 2 (GLP-2) is a growth factor for the intestinal epithelium in rodents and may affect intestinal transit. AIMS To study the GLP-2 response to nutrient ingestion in seven short bowel patients with intestinal failure and seven controls. METHODS The patients and controls were admitted twice for two test meals after a night of fasting. Meal A was liquid (300 ml, 1.88 MJ); meal B was a regular breakfast (755 g, 3.92 MJ). Plasma samples were collected for 180 minutes; GLP-2 immunoreactivity was measured with an NH2 terminal specific radioimmunoassay. RESULTS Both meals elicited significant increases in plasma GLP-2 in controls. The magnitude and duration of the responses were dependent on the meal size: the maximum median (25–75%) increases after meal A and B were 24 (3–28) and 48 (33–56) pmol/l. Plasma GLP-2 returned to basal concentrations 180 minutes after meal A, but remained at 50% of peak values after meal B. In the patients neither meal significantly changed the GLP-2 concentration; the maximum median elevation after meal B was 5 (2–8) pmol/l. There were significant differences between patients and controls with respect to the GLP-2 responses to meals A and B. CONCLUSION Identification of GLP-2 as a tissue specific intestinal growth factor and demonstration of an impaired meal stimulated GLP-2 response in short bowel patients raises the possibility that GLP-2 administration may constitute a new therapeutic strategy, enhancing jejunal adaptation in ileum resected short bowel patients with intestinal failure.

Gut hormones, early dumping and resting energy expenditure in patients with good and poor weight loss response after Roux-en-Y gastric bypass

Objective:To identify factors contributing to the variation in weight loss after Roux-en-Y gastric bypass (RYGB).Design:Cross-sectional study of patients with good (excess body mass index lost (EBL) >60%) and poor weight loss response (EBL <50%) >12 months after RYGB and a lean control group matched for age and gender.Materials and methods:Sixteen patients with good weight loss response, 17 patients with poor weight loss response, and eight control subjects were included in the study. Participants underwent dual energy X-ray absorptiometry scan, indirect calorimetry and a 9 h multiple-meal test with measurements of glucose, insulin, total bile acids (TBA), glucagon-like peptide (GLP)-1, peptide YY3–36 (PYY), cholecystokinin (CCK), ghrelin, neurotensin and pancreatic polypeptide (PP) as well as assessment of early dumping and appetite.Results:Suppression of hunger was more pronounced in the good than the poor responders in response to the multiple-meal test (P=0.006). In addition, the good responders had a larger release of GLP-1 (P=0.009) and a greater suppression of ghrelin (P=0.037) during the test, whereas the postprandial secretion of CCK was highest in the poor responders (P=0.005). PYY, neurotensin, PP and TBA release did not differ between the RYGB-operated groups. Compared with control subjects, patients had exaggerated release of GLP-1 (P<0.001), PYY (P=0.008), CCK (P=0.010) and neurotensin (P<0.001). Early dumping was comparable in the good and poor responders, but more pronounced than in controlled subjects. Differences in resting energy expenditure between the three groups were entirely explained by differences in body composition.Conclusion:Favorable meal-induced changes in hunger and gut hormone release in patients with good compared with poor weight loss response support the role of gut hormones in the weight loss after RYGB.

Glucagon-like peptide 2 (GLP-2) accelerates the growth of colonic neoplasms in mice

Background: Glucagon-like peptide 2 (GLP-2) is an intestinotrophic mediator with therapeutic potential in conditions with compromised intestinal capacity. However, growth stimulation of the intestinal system may accelerate the growth of existing neoplasms in the intestine. Aims: In the present study, the effects of GLP-2 treatment on the growth of chemically induced colonic neoplasms were investigated. Methods: In 210 female C57bl mice, colonic tumours were initially induced with the methylating carcinogen 1,2-dimethylhydrazine (DMH) and mice were then treated with GLP-2. Two months after discontinuation of the carcinogen treatment, 135 of the mice were allocated to one of six groups which were treated twice daily with 25 μg GLP-2, 25 μg Gly2-GLP-2 (stable analogue), or phosphate buffered saline for a short (10 days) or long (one month) period. The remaining 75 mice had a treatment free period of three months and were then allocated to groups subjected to long term treatment, as above. Results: Colonic polyps developed in 100% of the mice, regardless of treatment. Survival data revealed no statistical significant differences among the different groups but histopathological analysis demonstrated a clear and significant increase in tumour load of mice treated with Gly2-GLP-2. The tumour promoting effect of native GLP-2 was less pronounced but the number of small sized polyps increased following long term treatment. Conclusions: The present results clearly indicate that GLP-2 promotes the growth of mucosal neoplasms. Our findings highlight the need for future investigations on the effects of GLP-2 in conditions needing long time treatment or with increased gastrointestinal cancer susceptibility.

Short-term Administration of Glucagon-like Peptide-2. Effects on Bone Mineral Density and Markers of Bone Turnover in Short-Bowel Patients with No Colon

Background: Glucagon-like peptide 2 (GLP-2) is a newly discovered intestinotrophic hormone. We have recently reported that a 5-week GLP-2 treatment improved the intestinal absorptive capacity of shortbowel patients with no colon. Additionally, GLP-2 treatment was associated with changes in body composition that included a significant increase in total body bone mass. This article describes the effect of GLP-2 on spinal and hip bone mineral density (BMD) and biochemical markers of bone turnover in these patients. Methods: In an open-labelled pilot study, eight short-bowel patients (3M, 5F; mean age 49 years) with small-bowel resection and no colon received 400 μg s.c. of GLP-2 twice daily for 5 weeks. Four received home parenteral nutrition (mean length of residual jejunum 83 cm) and 4 did not (mean length of ileum resected 106 cm). The outcome measures were the mean percent change from baseline in spinal and hip BMD measured by dual-energy X-ray absorptiometry, changes in four biochemical markers of bone-turnover, PTH, 25-hydroxy vitamin-D, and the intestinal absorption of calcium. Results: Mean ± s x (SEM) percent changes in spinal and hip BMD were 1.1 ± 0.4% ( P < 0.05) and 1.9 ± 0.8% ( P = 0.06), respectively. The intestinal calcium absorption increased by 2.7% ( P = 0.87). Serum ionized calcium increased in 5/8 patients with a concomitant decrease in serum PTH values. Three of the four markers of bone turnover decreased. Conclusion: A 5-week GLP-2 administration significantly increased spinal BMD in short-bowel patients with no colon. The mechanism by which GLP-2 affects bone metabolism remains unclear, but may be related to an increased mineralization of bone resulting from an improved intestinal calcium absorption.

Peripheral administration of GLP-2 to humans has no effect on gastric emptying or satiety

Glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) are secreted in parallel to the circulation after a meal. Intravenous (IV) GLP-1 has an inhibitory effect on gastric emptying, hunger and food intake in man. In rodents, central administration of GLP-2 increases satiety similar to GLP-1. The aim of the present study was to assess the effect of IV administered GLP-2 on gastric emptying and feelings of hunger in human volunteers. In eight (five men) healthy subjects (age 31.1+/-2.9 years and BMI 24.1+/-1.0 kg m(-2)), scintigraphic solid gastric emptying, hunger ratings (VAS) and plasma concentrations of GLP-2 were studied during infusion of saline or GLP-2 (0.75 and 2.25 pmol kg(-1) min(-1)) for a total of 180 min. Concentrations of GLP-2 were elevated to a maximum of 50 and 110 pmol l(-1) for 0.75 and 2.25 pmol kg(-1) min(-1) infusion of GLP-2, respectively. There was no effect of GLP-2 on either the lag phase (29.5+/-4.4, 26.0+/-5.2 and 21.2+/-3.6 min for saline, GLP-2 0.75 or 2.25 pmol kg(-1) min(-1), respectively) or the half emptying time (84.5+/-6.1, 89.5+/-17.8 and 85.0+/-7.0 min for saline, GLP-2 0.75 or 2.25 pmol kg(-1) min(-1), respectively). The change in hunger rating after the meal to 180 min was also unaffected by infusion of GLP-2. GLP-2 does not seem to mediate the ileal brake mechanism.

No effect of physiological concentrations of glucagon-like peptide-2 on appetite and energy intake in normal weight subjects

OBJECTIVE: To examine the effect of a GLP-2 infusion on appetite sensations and ad libitum energy intake in healthy, normal weight humans.DESIGN: The experiment was performed in a randomised, blinded, and placebo-controlled crossover design. Placebo or GLP-2 was infused (infusion rate of 25 pmol/kg body wth) for 4.5 h.SUBJECTS: A total of 18 healthy, normal weight young subjects participated; eight women and 10 men.MEASUREMENTS: During the infusion, subjects recorded their appetite sensations every 30 min using visual analogue scales, and blood was sampled frequently. After 2 h of infusion, an ad libitum meal, consisting of sandwiches, was served.RESULTS: The concentration of GLP-2 was significantly higher during the GLP-2 infusion compared with placebo (P<0.0001) and increased further in both conditions in response to the meal. Neither appetite sensations, nor palatability of the test meals, or energy intake were different on the two occasions. Glucose, GLP-1, insulin, and GIP responses were also unaffected by the infusion, whereas glucagon levels were higher during the GLP-2 treatment (P<0.05).CONCLUSION: Circulating GLP-2 in physiological concentrations does not seem to play a significant role in human appetite regulation.

Diabetic intestinal growth adaptation and glucagon-like peptide 2 in the rat: effects of dietary fibre

BACKGROUND/AIMS Dietary fibre influence growth and function of the upper gastrointestinal tract. This study investigates the importance of dietary fibre in intestinal growth in experimental diabetes, and correlates intestinal growth with plasma levels of the intestinotrophic factor, glucagon-like peptide 2 (GLP-2). METHODS Male Wistar rats were randomised to the following groups: two streptozotocin-diabetic and two control groups fed either a fibre-containing or a fibre-free diet for three weeks. Intestinal weight, length, and morphometric data (villus height, villus area, crypt depth) were measured. Blood samples were obtained after two weeks for measurement of GLP-2 and enteroglucagon (glicentin, oxyntomodulin). RESULTS The mean daily consumption of food in the two diabetic groups was 40% higher than in controls. In diabetic rats fed fibre, the increase in intestinal weight from day 0 to 20 was sixfold greater than that of the controls and small intestine weight per cm length was increased by 50%. In the diabetic rats fed a fibre-free diet, intestinal growth was 30% less than in diabetic rats fed fibre, and intestinal weight increased only threefold compared with controls. Morphometric data showed that the intestinal increase in diabetic rats fed fibre was due primarily to growth of the mucosal layer. Villus height and crypt depth increased 60% and 40% respectively, but by only 20% in fibre-free diabetic rats. The plasma levels of GLP-2 parallelled diabetic intestinal growth, whereas plasma levels of enteroglucagon increased regardless of the extent of intestinal growth. CONCLUSIONS Intestinal growth in experimental diabetes is strongly influenced by the presence of dietary fibre. The effect may be mediated by GLP-2.

Specificity and sensitivity of commercially available assays for glucagon-like peptide-1 (GLP-1): implications for GLP-1 measurements in clinical studies

To evaluate the performances of commercially available glucagon‐like peptide‐1 (GLP‐1) assays and the implications for clinical studies.

Peptide YY and glucagon-like peptide-1 contribute to decreased food intake after Roux-en-Y gastric bypass surgery

Background/Objectives:Exaggerated postprandial secretion of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) may explain appetite reduction and weight loss after Roux-en-Y gastric bypass (RYGB), but causality has not been established. We hypothesized that food intake decreases after surgery through combined actions from GLP-1 and PYY. GLP-1 actions can be blocked using the GLP-1 receptor antagonist Exendin 9–39 (Ex-9), whereas PYY actions can be inhibited by the administration of a dipeptidyl peptidase-4 (DPP-4) inhibitor preventing the formation of PYY3–36.Subjects/Methods:Appetite-regulating gut hormones and appetite ratings during a standard mixed-meal test and effects on subsequent ad libitum food intake were evaluated in two studies: in study 1, nine patients with type 2 diabetes were examined prospectively before and 3 months after RYGB with and without Ex-9. In study 2, 12 RYGB-operated patients were examined in a randomized, placebo-controlled, crossover design on four experimental days with: (1) placebo, (2) Ex-9, (3) the DPP-4 inhibitor, sitagliptin, to reduce formation of PYY3–36 and (4) Ex-9/sitagliptin combined.Results:In study 1, food intake decreased by 35% following RYGB compared with before surgery. Before surgery, GLP-1 receptor blockage increased food intake but no effect was seen postoperatively, whereas PYY secretion was markedly increased. In study 2, combined GLP-1 receptor blockage and DPP-4 inhibitor mediated lowering of PYY3–36 increased food intake by ~20% in RYGB patients, whereas neither GLP-1 receptor blockage nor DPP-4 inhibition alone affected food intake, perhaps because of concomitant marked increases in the unblocked hormone.Conclusions:Blockade of actions from only one of the two L-cell hormones, GLP-1 and PYY3–36, resulted in concomitant increased secretion of the other, probably explaining the absent effect on food intake on these experimental days. Combined blockade of GLP-1 and PYY actions increased food intake after RYGB, supporting that these hormones have a role in decreased food intake postoperatively.