Incretins Beyond the Pancreas: Exploring the Impact of GIP and GLP-1/2 on Bone Remodeling.

Incretin hormones, such as glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 and 2 (GLP-1, 2), belong to the group of gastrointestinal hormones. Their actions occur through interaction with GIP and GLP-1/2 receptors, which are present in various target tissues. Apart from their well-established roles in pancreatic function and insulin regulation, incretins elicit significant effects that extend beyond the pancreas. Specifically, these hormones stimulate osteoblast differentiation and inhibit osteoclast activity, thereby promoting bone anabolism. Moreover, they play a pivotal role in bone mineralization and overall bone quality and function, making them potentially therapeutic for managing bone health. Thus, this review provides a summary of the crucial involvement of incretins in bone metabolism, influencing both bone formation and resorption processes. While existing evidence is persuasive, further studies are necessary for a comprehensive understanding of the therapeutic potential of incretins in modifying bone health.

Glucagon-like Peptide-2 Depresses Ileal Contractility in Preparations from Mice through Opposite Modulatory Effects on Nitrergic and Cholinergic Neurotransmission.

Glucagon-like peptide-2 (GLP-2) has been reported to influence gastrointestinal motor responses, exerting a modulatory role on enteric neurotransmission. To our knowledge, no data on GLP-2 effects on the motility of the isolated ileum are available; therefore, we investigated whether GLP-2 affects the contractile activity of mouse ileal preparations and the neurotransmitters engaged. Ileal preparations showed tetrodotoxin (TTX)- and atropine-insensitive spontaneous contractile activity, which was unaffected by the nitric oxide synthesis inhibitor, L-NNA. GLP-2 depressed the spontaneous contractility, an effect that was abolished by TTX or L-NNA and not influenced by atropine. Electrical field stimulation induced TTX- and atropine-sensitive contractile responses, which were reduced in amplitude by GLP-2 even in the presence of L-NNA. Immunohistochemical results showed a significant increase in nNOS-positive fibers in the ileal muscle wall and a significant decrease in ChAT-positive myenteric neurons in GLP-2-exposed preparations. The present results offer the first evidence that GLP-2 acts on ileal preparations. The hormone appears to depress ileal contractility through a dual opposite modulatory effect on inhibitory nitrergic and excitatory cholinergic neurotransmission. From a physiological point of view, it could be hypothesized that GLP-2 inhibitory actions on ileal contractility can increase transit time, facilitating nutrient absorption.

Use of Teduglutide in the Management of Gastrointestinal Graft-versus-Host Disease in Children and Young Adults.

Loss of intestinal L cells and reduced levels of glucagon-like peptide-2 (GLP-2) have been implicated in acute graft-versus-host disease (GVHD) in murine models. Teduglutide, a human recombinant GLP-2 analog, may be beneficial in acute gastrointestinal (GI) GVHD owing to its known tissue protective and regenerative functions. We retrospectively reviewed patients who received teduglutide for treatment of GI GVHD. Endoscopy was performed at diagnosis and at completion of the teduglutide course. GLP-1 immunohistochemistry (IHC) was performed at diagnosis and the end of teduglutide therapy in 2 patients to evaluate L cells. We initiated daily teduglutide 0.05 mg/kg subcutaneously as adjunctive therapy in 3 pediatric patients with refractory GI GVHD. All 3 patients had resolution of GI GVHD following completion of the teduglutide course, as evidenced by reduced apoptosis and regenerative changes on post-treatment endoscopy. Reportable GLP-1 IHC in 2 patients demonstrated increased L cells at the end of teduglutide treatment compared to at diagnosis. No adverse effects to teduglutide were observed. Teduglutide is a promising adjunctive and non-immune suppressive agent for managing acute GI GVHD.

Low dietary carbohydrate induces structural alterations in enterocytes of the chicken ileum.

We investigated the role of dietary carbohydrates in the maintenance of the enterocyte microvillar structure in the chicken ileum. Male chickens were divided into the control and three experimental groups, and the experimental groups were fed diets containing 50%, 25%, and 0% carbohydrates of the control diet. The structural alterations in enterocytes were examined using transmission electron microscopy and immunofluorescent techniques for ß-actin and villin. Glucagon-like peptide (GLP)-2 and proglucagon mRNA were detected by immunohistochemistry and in situ hybridization, respectively. Fragmentation and wide gap spaces were frequently observed in the microvilli of the 25% and 0% groups. The length, width, and density of microvilli were also decreased in the experimental groups. The experimental groups had shorter terminal web extensions, and there were substantial changes in the mitochondrial density between the control and experimental groups. Intensities of ß-actin and villin immunofluorescence observed on the apical surface of enterocytes were lower in the 0% group. The frequency of GLP-2-immunoreactive and proglucagon mRNA-expressing cells decreased with declining dietary carbohydrate levels. This study revealed that dietary carbohydrates contribute to the structural maintenance of enterocyte microvilli in the chicken ileum. The data from immunohistochemistry and in situ hybridization assays suggest the participation of GLP-2 in this maintenance system.

Release of Lipids Stored in the Intestine by Glucagon-Like Peptide-2 Involves a Gut-Brain Neural Pathway.

BACKGROUND: The gut hormone GLP-2 (glucagon-like peptide-2) plays important roles in lipid handling in the intestine. During postabsorptive stage, it releases preformed chylomicrons stored in the intestine, the underlying mechanisms of which are not well understood. Previous studies implicate the involvement of neural pathways in GLP-2's actions on lipid absorption in the intestine, but the role of such mechanisms in releasing postabsorptive lipid storage has not been established. METHODS: Here, in mesenteric lymph duct cannulated rats, we directly tested whether gut-brain neural communication mediates GLP-2's effects on postabsorptive lipid mobilization in the intestine. We performed total subdiaphragmatic vagotomy to disrupt the gut-brain neural communication and analyzed lipid output 5 hours after a lipid load in response to intraperitoneal GLP-2 or saline. RESULTS: Peripheral GLP-2 administration led to increased lymph lipid output and activation of proopiomelanocortin neurons in the arcuate nucleus of hypothalamus. Disruption of gut-brain neural communication via vagotomy blunted GLP-2's effects on promoting lipid release in the intestine. CONCLUSIONS: These results, for the first time, demonstrate a novel mechanism in which postabsorptive mobilization of intestinal lipid storage by GLP-2 enlists a gut-brain neural pathway.

Associations between feeding and glucagon-like peptide-2 in healthy ponies.

BACKGROUND: Gastrointestinal peptides, such as glucagon-like peptide-2 (GLP-2), could play a direct role in the development of equine hyperinsulinaemia. OBJECTIVES: To describe the secretory pattern of endogenous GLP-2 over 24 h in healthy ponies and determine whether oral administration of a synthetic GLP-2 peptide increases blood glucose or insulin responses to feeding. STUDY DESIGN: A cohort study followed by a randomised, controlled, cross-over study. METHODS: In the cohort study, blood samples were collected every 2 h for 24 h in seven healthy ponies and plasma [GLP-2] was measured. In the cross-over study, 75 µg/kg bodyweight of synthetic GLP-2, or carrier only, was orally administered to 10 ponies twice daily for 10 days. The area under the curve (AUC0-3h ) of post-prandial blood glucose and insulin were determined before and after each treatment. RESULTS: Endogenous [GLP-2] ranged from <0.55 to 1.95 ± 0.29 [CI 0.27] ng/mL with similar peak concentrations in response to meals containing 88-180 g of non-structural carbohydrate, that were ~4-fold higher (P < 0.001) than the overnight nadir. After GLP-2 treatment peak plasma [GLP-2] increased from 1.1 [0.63-1.37] ng/mL to 1.54 [1.1-2.31] ng/mL (28.6%; P = 0.002), and AUC0-3h was larger (P = 0.01) than before treatment. The peptide decreased (7%; P = 0.003) peak blood glucose responses to feeding from 5.33 ± 0.45 mmol/L to 5.0 ± 0.21 mmol/L, but not AUC0-3h (P = 0.07). There was no effect on insulin secretion. MAIN LIMITATIONS: The study only included healthy ponies and administration of a single dose of GLP-2. CONCLUSIONS: The diurnal pattern of GLP-2 secretion in ponies was similar to other species with no apparent effect of daylight. Although GLP-2 treatment did not increase post-prandial glucose or insulin responses to eating, studies using alternative dosing strategies for GLP-2 are required.

A specific gut microbiota signature is associated with an enhanced GLP-1 and GLP-2 secretion and improved metabolic control in patients with type 2 diabetes after metabolic Roux-en-Y gastric bypass.

Objective: To determine changes in incretins, systemic inflammation, intestinal permeability and microbiome modifications 12 months after metabolic RYGB (mRYGB) in patients with type 2 diabetes (T2D) and their relationship with metabolic improvement. Materials and methods: Prospective single-center non-randomized controlled study, including patients with class II-III obesity and T2D undergoing mRYGB. At baseline and one year after surgery we performed body composition measurements, biochemical analysis, a meal tolerance test (MTT) and lipid test (LT) with determination of the area under the curve (AUC) for insulin, C-peptide, GLP-1, GLP-2, and fasting determinations of succinate, zonulin, IL-6 and study of gut microbiota. Results: Thirteen patients aged 52.6 ± 6.5 years, BMI 39.3 ± 1.4 kg/m2, HbA1c 7.62 ± 1.5% were evaluated. After mRYGB, zonulin decreased and an increase in AUC after MTT was observed for GLP-1 (pre 9371 ± 5973 vs post 15788 ± 8021 pM, P<0.05), GLP-2 (pre 732 ± 182 vs post 1190 ± 447 ng/ml, P<0.001) and C- peptide, as well as after LT. Species belonging to Streptococaceae, Akkermansiacea, Rickenellaceae, Sutterellaceae, Enterobacteriaceae, Oscillospiraceae, Veillonellaceae, Enterobacterales_uc, and Fusobacteriaceae families increased after intervention and correlated positively with AUC of GLP-1 and GLP-2, and negatively with glucose, HbA1c, triglycerides and adiposity markers. Clostridium perfringens and Roseburia sp. 40_7 behaved similarly. In contrast, some species belonging to Lachnospiraceae, Erysipelotricaceae, and Rumnicocaceae families decreased and showed opposite correlations. Higher initial C-peptide was the only predictor for T2D remission, which was achieved in 69% of patients. Conclusions: Patients with obesity and T2D submitted to mRYGB show an enhanced incretin response, a reduced gut permeability and a metabolic improvement, associated with a specific microbiota signature.

Predictive Potential of Biomarkers of Intestinal Barrier Function for Therapeutic Management with Teduglutide in Patients with Short Bowel Syndrome.

INTRODUCTION: The human intestinal tract reacts to extensive resection with spontaneous intestinal adaptation. We analyzed whether gene expression analyses or intestinal permeability (IP) testing could provide biomarkers to describe regulation mechanisms in the intestinal barrier in short bowel syndrome (SBS) patients during adaptive response or treatment with the glucagon-like peptide-2 analog teduglutide. METHODS: Relevant regions of the GLP-2 receptor gene were sequenced. Gene expression analyses and immunohistochemistry were performed from mucosal biopsies. IP was assessed using a carbohydrate oral ingestion test. RESULTS: The study includes 59 SBS patients and 19 controls. Increases in gene expression with teduglutide were received for sucrase-isomaltase, sodium/glucose cotransporter 1, and calcium/calmodulin serine protein kinase. Mannitol recovery was decreased in SBS but elevated with teduglutide (Δ 40%), showed a positive correlation with remnant small bowel and an inverse correlation with parenteral support. CONCLUSIONS: Biomarkers predicting clinical and functional features in human SBS are very limited. Altered specific gene expression was shown for genes involved in nutrient transport but not for genes controlling tight junctions. However, mannitol recovery proved useful in describing the absorptive capacity of the gut during adaptation and treatment with teduglutide.

Glucagon-like peptide-1 and glucagon-like peptide-2 regulation during human liver regeneration.

Accumulating evidence suggests that metabolic demands of the regenerating liver are met via lipid metabolism and critical regulators of this process. As such, glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) critically affect hepatic regeneration in rodent models. The present study aimed to evaluate potential alterations and dynamics of circulating GLP-1 and GLP-2 in patients undergoing liver resections, focusing on post-hepatectomy liver failure (PHLF). GLP-1, GLP-2, Interleukin-6 (IL-6) and parameters of lipid metabolism were determined perioperatively in fasting plasma of 46 patients, who underwent liver resection. GLP-1 and GLP-2 demonstrated a rapid and consistently inverse time course during hepatic regeneration with a significant decrease of GLP-1 and increase of GLP-2 on POD1. Importantly, these postoperative dynamics were significantly more pronounced when PHLF occurred. Of note, the extent of resection or development of complications were not associated with these alterations. IL-6 mirrored the time course of GLP-2. Assessing the main degradation protein dipeptidyl peptidase 4 (DPP4) no significant association with either GLP-1 or -2 could be found. Additionally, in PHLF distinct postoperative declines in plasma lipid parameters were present and correlated with GLP-2 dynamics. Our data suggest dynamic inverse regulation of GLP-1 and GLP-2 during liver regeneration, rather caused by an increase in expression/release than by changes in degradation capacity and might be associated with inflammatory responses. Their close association with circulating markers of lipid metabolism and insufficient hepatic regeneration after liver surgery suggest a critical involvement during these processes in humans.

Plasma glucagon-like peptide-2 concentrations are lower in dogs with chronic enteropathies than in healthy dogs.

OBJECTIVE: To compare plasma glucagon-like peptide-2 (GLP-2) concentrations in dogs with treatment-naïve chronic enteropathies to healthy dogs and describe changes over time in dogs with chronic enteropathies (CE). ANIMALS: 18 client-owned dogs with treatment-naïve CE and 17 client-owned healthy control dogs. METHODS: This was a prospective study. Fasting, 1-hour, and 3-hour postprandial plasma GLP-2 concentrations were measured using a commercial immunoassay in healthy dogs and dogs with uncontrolled, untreated CE. Repeated fasting and postprandial plasma concentrations were measured in dogs with CE after initiating directed treatment for gastrointestinal disease. RESULTS: There was no significant difference between fasting and postprandial GLP-2 concentrations in either group. Dogs with treatment-naïve CE had lower fasting (mean, 424 ± SD 176 pg/mL) plasma GLP-2 concentrations than healthy dogs (1184 ± 435 pg/mL; P < .0001). Fasted plasma GLP-2 concentrations (624 ± 314 pg/mL) remained lower in dogs with CE than in healthy dogs at recheck. CLINICAL RELEVANCE: Dogs with CE have disrupted GLP-2 secretion. Future studies are required to evaluate subsets of CE and changes in response to therapy.

Post-prandial secretion of glucagon-like peptide-2 (GLP-2) after carbohydrate-, fat- or protein enriched meals in healthy subjects.

Glucagon-like peptide 2 (GLP-2) is an important regulator of intestinal growth and function. In adherable mixed meals the macronutrient composition with the best potential for stimulating GLP-2 secretion is not known. We compared the effect of 3 iso-energetic meals, where approximately 60 % of the energy ratio was provided as either carbohydrate, fat, or protein, respectively, on the post-prandial endogenous GLP-2 secretion. The responses were compared to secretion profiles of peptide YY (PYY), and glucose-dependent insulinotropic peptide (GIP). Ten healthy subjects were admitted on three occasions, at least a week apart, after a night of fasting. In an open-label, crossover design, they were randomized to receive a high carbohydrate (HC), high fat (HF) or high protein (HP) meal. The meals were approximately ∼3.9 MJ. Venous blood was collected for 240 min, and plasma concentrations of GLP-2, GIP and PYY were measured with specific radioimmunoassays. Mean GLP-2 levels peaked already at 30 min for the HC meal, however the HP meal induced the highest mean GLP-2 peaking levels, resulting in significantly higher mean GLP-2 area under the curve (AUC) from baseline of 7279 pmol*min/L, 95 %-CI [6081;8477] compared to the HC meal: 4764 pmol*min/L, 95 %-CI [3498;6029], p = 0.020 and the HF meal: 4796 pmol*min/L, [3385;6207], p = 0.011. Findings were similar for the PYY. The HC meal provided a greater AUC for GIP compared to the HP- and HF meals. The HP meal was most effective with respect to stimulation of the postprandial GLP-2 and PYY secretion, whereas the HC meal was more effective for GIP.

Revisión sobre la experiencia en vida real de teduglutida / Review of real-life teduglutide experience

Introducción: la teduglutida es un agonista del péptido relacionado con glucagón (aGLP2) eficaz como tratamiento de pacientes con síndrome de intestino corto (SIC) una entidad que afecta a la calidad de vida, suele precisar de nutrición parenteral domiciliaria (NPD) y genera importantes costes sanitarios. El objetivo de la presente revisión narrativa fue evaluar la experiencia en vida real reportada con teduglutida. Métodos y resultados: en vida real un metaanálisis y estudios publicados con 440 pacientes, indican que teduglutida es efectivo pasado el periodo de adaptación intestinal posterior a la cirugía, reduciendo las necesidades de NPD y en algunos casos permite incluso suspenderla. La respuesta es heterogénea, aumenta progresivamente hasta 2 años después del inicio del tratamiento y alcanza el 82 % en algunas series. La presencia de colon en continuidad es factor predictivo negativo de respuesta precoz, pero un factor predictivo positivo para la retirada de NPD. Los efectos adversos más frecuentes son de origen gastrointestinal en las primeras etapas del tratamiento. Hay complicaciones tardías relacionadas con el estoma o con la aparición de pólipos de colon, aunque la frecuencia de estas últimas es muy baja. En adultos son escasos los datos en mejoría de calidad de vida y en coste eficacia. Conclusiones: teduglutida es efectivo y seguro confirmándose en vida real los datos de los ensayos pivotales para tratamiento de pacientes con SIC y permite reducir o incluso suspender en algunos casos la NPD. Aunque parece coste efectivo son necesarios más estudios para identificar aquellos pacientes con mayor beneficio.(AU)

Background: teduglutide is an agonist of glucagon-related peptide (aGLP2) effective as a treatment for patients with short bowel syndrome (SBS), an entity that affects quality of life, usually requires home parenteral nutrition (HPN) and generates significant health costs. The objective of the present narrative review was to assess the real-life experience reported with teduglutide.Methods and results: in real life, one meta-analysis and studies published with 440 patients indicate that Teduglutide is effective after the period of intestinal adaptation after surgery, reducing the need for HPN and in some cases even allowing it to be suspended. The response is heterogeneous, increasing progressively up to 2 years after the start of treatment and reaching 82 % in some series. The presence of colon in continuity is a negative predictor of early response, but a positive predictive factor for the withdrawal of HPN. The most common side effects are gastrointestinal in the early stages of treatment. There are late complications related to the stoma or the occurrence of colon polyps, although the frequency of the latter is very low. In adults, data on improved quality of life and cost-effectiveness are scarce. Conclusions: teduglutide is effective and safe and data from pivotal trials for the treatment of patients with SBS are confirmed in real life and can reduce or even stop HPN in some cases. Although it seems cost-effective, more studies are needed to identify those patients with the greatest benefit.(AU)

The indications and results of the use of teduglutide in patients with short bowel.

Short bowel syndrome (SBS) is a rare condition defined as a reduced residual functional small intestinal length to less than 200 cm often resulting from extensive intestinal resection, and can lead to chronic intestinal failure (CIF). Patients with SBS-CIF are unable to absorb sufficient nutrients or fluids to maintain metabolic homeostasis through oral or enteral intake and require long-term parenteral nutrition and/or fluids and electrolytes. However, complications may arise from both SBS-IF and life-sustaining intravenous support, such as intestinal failure-associated liver disease (IFALD), chronic renal failure, metabolic bone disease and catheter-related complications. An interdisciplinary approach is required to optimize intestinal adaptation and decrease complications. In the last two decades, glucagon-like peptide 2 (GLP-2) analogs have sparked pharmacological interest as a potential disease-modifying therapy for SBS-IF. Teduglutide (TED) is the first developed and marketed GLP-2 analog for SBS-IF. It is approved in the United States, Europe, and Japan for use in adults and children with SBS-IF who are intravenous supplementation dependent. This article discusses the indications, candidacy criteria and results of the use of TED in patients with SBS.

Computational Design of Potent and Selective d-Peptide Agonists of the Glucagon-like Peptide-2 Receptor.

Here, we designed three d-GLP-2 agonists that activated the glucagon-like peptide-2 receptor (GLP-2R) cyclic adenosine monophosphate (cAMP) accumulation without stimulating the glucagon-like peptide-1 receptor (GLP-1R). All the d-GLP-2 agonists increased the protein kinase B phosphorylated (p-AKT) expression levels in a time- and concentration-dependent manner in vitro. The most effective d-GLP-2 analogue boosted the AKT phosphorylation 2.28 times more effectively compared to the native l-GLP-2. The enhancement in the p-AKT levels induced by the d-GLP-2 analogues could be explained by GLP-2R's more prolonged activation, given that the d-GLP-2 analogues induce a lower ß-arrestin recruitment. The higher stability to protease degradation of our d-GLP-2 agonists helps us envision their potential applications in enhancing intestinal absorption and treating inflammatory bowel illness while lowering the high dosage required by the current treatments.

Characterization of the Pharmacokinetic and Pharmacodynamic Profile of Apraglutide, a Glucagon-Like Peptide-2 Analog, in Healthy Volunteers.

Apraglutide (FE 203799) is a glucagon-like peptide-2 (GLP-2) analog under development for the treatment of intestinal failure associated with short bowel syndrome (SBS-IF) and graft-versus-host disease (GvHD). Compared with native GLP-2, apraglutide has slower absorption, reduced clearance, and higher protein binding, enabling once-weekly dosing. This study evaluated the pharmacokinetic (PK) and pharmacodynamic (PD) profile of apraglutide in healthy adults. Healthy volunteers were randomized to receive 6 weekly subcutaneous administrations of 1, 5, or 10 mg apraglutide or placebo. PK and citrulline (an enterocyte mass PD marker) samples were collected at multiple time points. Kinetic parameters of apraglutide and citrulline were calculated using noncompartmental analysis; repeated PD measures were analyzed with a mixed model of covariance. A population PK/PD model was developed that also included data from a previous phase 1 study in healthy volunteers. Twenty-four subjects were randomized; 23 received all study drug administrations. Mean estimated apraglutide clearance was 16.5-20.7 l/day, and mean volume of distribution was 55.4-105.0 liters. A dose-dependent increase in citrulline plasma concentration was observed, with 5-mg and 10-mg doses inducing higher citrulline levels than 1-mg doses and placebo. PK/PD analysis showed that weekly 5-mg apraglutide induced the maximal citrulline response. Increased plasma citrulline levels were sustained for 10-17 days after the final apraglutide administration. Apraglutide displays predictable dose-dependent PK and PD profiles, with a 5-mg dose showing significant PD effects. Results suggest that apraglutide has early and enduring effects on enterocyte mass and supports the continued development of weekly subcutaneous apraglutide for SBS-IF and GvHD patient populations. SIGNIFICANCE STATEMENT: Once-weekly subcutaneous apraglutide results in dose-dependent elevations of plasma citrulline (an enterocyte mass pharmacodynamic marker) with parameters suggesting that apraglutide has lasting effects on enterocyte mass and the potential to provide therapeutic benefits. This is the first report of a model relating glucagon-like peptide-2 (GLP-2) agonism and its effects in intestinal mucosa, affording not only the ability to predict pharmacologic effects of GLP-2 analogs but also the exploration of optimal dosing regimens for this drug class across populations with different body weights.

Glucagon-Like Peptide-1 Is Involved in the Thermic Effects of Dietary Proteins in Male Rodents.

Protein intake potently increases body temperature and energy expenditure, but the underlying mechanism thereof remains incompletely understood. Simultaneously, protein intake potently stimulates glucagon-like peptide-1 (GLP-1) secretion. Here, we examined the involvement of GLP-1 in the thermic effects of dietary proteins in rodents by measuring rectal temperature and energy expenditure and modulating GLP-1 signaling. Rectal temperature of rats or mice fasted for 4 or 5 hours were measured using a thermocouple thermometer before and after an oral administration of nutrients. Oxygen consumption after oral protein administration was also measured in rats. Rectal temperature measurements in rats confirmed an increase in core body temperature after refeeding, and the thermic effect of the oral administration of protein was greater than that of a representative carbohydrate or lipid. Among the five dietary proteins examined (casein, whey, rice, egg, and soy), soy protein had the highest thermic effect. The thermic effect of soy protein was also demonstrated by increased oxygen consumption. Studies using a nonselective ß-adrenergic receptor antagonist and thermal camera suggested that brown adipose tissue did not contribute to soy protein-induced increase in rectal temperature. Furthermore, the thermic effect of soy protein was completely abolished by antagonism and knockout of the GLP-1 receptor, yet potentiated via augmentation of intact GLP-1 levels through inhibition of dipeptidyl peptidase-4 activity. These results indicate that GLP-1 signaling is essential for the thermic effects of dietary proteins in rats and mice, and extend the metabolic actions of GLP-1 ensuing from nutrient ingestion to encompass the thermic response to ingested protein.

RYGB surgery has modest effects on intestinal morphology and gut hormone populations in the bypassed biliopancreatic limb but causes reciprocal changes in GLP-2 and PYY in the alimentary limb.

Roux-en-Y gastric-bypass (RYGB) induced alterations in intestinal morphology and gut-cell hormone expression profile in the bypassed biliopancreatic-limb (BPL) versus the alimentary-limbs (AL) are poorly characterised. This pilot study has therefore explored effects following RYGB in high-fat-diet (HFD) and normal-diet (ND) rats. Female Wistar rats (4-week-old) were fed HFD or ND for 23-weeks prior to RYGB or sham surgeries. Immunohistochemical analysis of excised tissue was conducted three-weeks post-surgery. After RYGB, intestinal morphology of the BPL in both HFD and ND groups was unchanged with exception of a small decrease in villi width in the ND-RYGB and crypt depth in the HFD-RYGB group. However, in the AL, villi width was decreased in ND-RYGB rats but increased in the HFD-RYGB group. In addition, crypt depth decreased after RYGB in the AL of HFD rats. GIP positive cells in either limb of both groups of rats were unchanged by RYGB. Similarly, there was little change in GLP-1 positive cells, apart from a small decrease of numbers in the villi of the BPL in HFD rats. RYGB increased GLP-2 cell numbers in the AL of ND-RYGB rats, including in both crypts and villi. This was associated with decreased numbers of cells expressing PYY in the AL of ND-RYGB rats. The BPL appears to maintain normal morphology and unchanged enteroendocrine cell populations despite being bypassed in RYGB-surgery. In contrast, in the AL, villi area is generally enhanced post-RYGB in ND rats with increased numbers of GLP-2 positive cells and decreased expression of PYY.

Circulating levels of proglucagon-derived peptides are differentially regulated by the glucagon-like peptide-1 agonist liraglutide and the centrally acting naltrexone/bupropion and can predict future weight loss and metabolic improvements: A 6-month long interventional study.

AIM: To investigate the changes of circulating levels of all proglucagon-derived peptides (PGDPs) in individuals with overweight or obesity receiving liraglutide (3 mg) or naltrexone/bupropion (32/360 mg), and to explore the association between induced changes in postprandial PGDP levels and body composition, as well as metabolic variables, after 3 and 6 months on treatment. MATERIALS AND METHODS: Seventeen patients with obesity or with overweight and co-morbidities, but without diabetes, were assigned to receive once-daily oral naltrexone/bupropion 32/360 mg (n = 8) or once-daily subcutaneous liraglutide 3 mg (n = 9). Participants were assessed before treatment initiation and after 3 and 6 months on treatment. At the baseline and 3-month visits, participants underwent a 3-hour mixed meal tolerance test to measure fasting and postprandial levels of PGDPs, C-peptide, hunger and satiety. Clinical and biochemical indices of metabolic function, magnetic resonance-assessed liver steatosis and ultrasound-assessed liver stiffness were measured at each visit. RESULTS: Both medications improved body weight and composition, carbohydrate and lipid metabolism, and liver fat and function. Naltrexone/bupropion produced a weight-independent increase in the levels of proglucagon (P < .001) and decreases in glucagon-like peptide-2 (GLP-2), glucagon and the major proglucagon fragment (P ≤ .01), whereas liraglutide markedly upregulated total glucagon-like peptide-1 (GLP-1) levels in a weight-independent manner (P = .04), and similarly downregulated the major proglucagon fragment, GLP-2 and glucagon (P < .01). PGDP levels at the 3-month visit were positively and independently correlated with improvements in fat mass, glycaemia, lipaemia and liver function, and negatively with reductions in fat-free mass, at both the 3- and 6-month visits. CONCLUSIONS: PGDP levels in response to liraglutide and naltrexone/bupropion are associated with improvements in metabolism. Our study provides support for the administration of the downregulated members of the PGDP family as replacement therapy (e.g. glucagon), in addition to the medications currently in use that induced their downregulation (e.g. GLP-1), and future studies should explore whether the addition of other PGDPs (e.g. GLP-2) could offer additional benefits.

Anatomical and physiological considerations in short bowel syndrome: Emphasis on intestinal adaptation and the role of enterohormones.

Short bowel syndrome (SBS)-associated intestinal failure (IF) is a complex, life-threatening condition that requires complex care of multiple factors impacting the patient's long-term prognosis. Various etiologies result in SBS-IF, with three primary anatomical subtypes occurring following intestinal resection. Depending on the extent and segment(s) of the intestine resected, malabsorption can be nutrient specific or sweeping; however, such issues and the associated prognosis for the patient can be predicted with analysis of the residual intestine, along with baseline nutrient and fluid deficits and extent of malabsorption. The provision of parenteral nutrition/intravenous (PN-IV) fluids and antisymptomatic agents is fundamental; however, optimal management should focus on intestinal rehabilitation, wherein intestinal adaptation is prioritized and PN-IV fluids are weaned over time. Key strategies to maximize intestinal adaptation include hyperphagic consumption of an individualized SBS diet and the appropriate use of trophic agents, such as a glucagon-like peptide 2 analog.