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Abstract Context A portion of ingested fats are retained in the intestine for many hours before they are mobilized and secreted in chylomicron (CM) particles. Factors such as glucagon-like peptide-2 (GLP-2) and glucose can mobilize these stored intestinal lipids and enhance CM secretion. We have recently demonstrated in rodents that GLP-2 acutely enhances CM secretion by mechanisms that do not involve the canonical CM synthetic assembly and secretory pathways. Objective To further investigate the mechanism of GLP-2's potent intestinal lipid mobilizing effect, we examined intracellular cytoplasmic lipid droplets (CLDs) in intestinal biopsies of humans administered GLP-2 or placebo. Design, setting, patients, and interventions A single dose of placebo or GLP-2 was administered subcutaneously 5 hours after ingesting a high-fat bolus. In 1 subset of participants, plasma samples were collected to quantify lipid and lipoprotein concentrations for 3 hours after placebo or GLP-2. In another subset, a duodenal biopsy was obtained 1-hour after placebo or GLP-2 administration for transmission electron microscopy and proteomic analysis. Results GLP-2 significantly increased plasma triglycerides by 46% (P = 0.009), mainly in CM-sized particles by 133% (P = 0.003), without reducing duodenal CLD size or number. Several proteins of interest were identified that require further investigation to elucidate their potential role in GLP-2-mediated CM secretion. Conclusions Unlike glucose that mobilizes enterocyte CLDs and enhances CM secretion, GLP-2 acutely increased plasma CMs without significant mobilization of CLDs, supporting our previous findings that GLP-2 does not act directly on enterocytes to enhance CM secretion and most likely mobilizes secreted CMs in the lamina propria and lymphatics.

Abstract Background and Objective Studies in humans and mice have demonstrated that the gut hormone glucagon-like peptide 2 (GLP-2) promotes gallbladder relaxation and refilling. Here, we assessed the effect of exogenous GLP-2 on gallbladder motility in the fasted state of healthy men with and without infusion of the potent gallbladder-contracting hormone cholecystokinin (CCK). Methods In a randomized, double-blind, placebo-controlled, crossover study, 15 male participants (mean [SD]: age 24.7 [3.6] years; body mass index 22.9 [1.6] kg/m2) underwent 4 experimental days receiving 2 infusions on each day: either CCK (0.4 pmol × kg−1 × min−1, time 0-180 minutes) + GLP-2 (10 pmol × kg−1 × min−1, time 30-240 minutes), CCK + placebo, placebo + GLP-2, or placebo + placebo, respectively. Gallbladder volume was measured at baseline and throughout the 4-hour study day using ultrasonography. Results Compared to placebo + placebo, GLP-2 + placebo did not affect gallbladder volume, but when infused in combination with CCK, GLP-2 completely abolished the strong gallbladder-contracting effect seen during CCK + placebo infusion, restoring baseline levels of gallbladder volume. Conclusion Exogenous GLP-2 counteracts exogenous CCK-induced gallbladder emptying in healthy men, pointing to a possible therapeutic potential for GLP-2 as a relaxing modulator of gallbladder smooth muscle tone (eg, as a bridge to surgery in biliary colic). The effect may also explain the gallbladder-related adverse events reported for GLP-2 receptor agonists used in the treatment of short bowel syndrome. Clinical Trial Registration number NCT04651868

The discovery, characterization, and clinical development of glucagon-like-peptide-1 (GLP-1) spans more than 30 years and includes contributions from multiple investigators, science recognized by the 2017 Harrington Award Prize for Innovation in Medicine. Herein, we provide perspectives on the historical events and key experimental findings establishing the biology of GLP-1 as an insulin-stimulating glucoregulatory hormone. Important attributes of GLP-1 action and enteroendocrine science are reviewed, with emphasis on mechanistic advances and clinical proof-of-concept studies. The discovery that GLP-2 promotes mucosal growth in the intestine is described, and key findings from both preclinical studies and the GLP-2 clinical development program for short bowel syndrome (SBS) are reviewed. Finally, we summarize recent progress in GLP biology, highlighting emerging concepts and scientific insights with translational relevance.

The gut hormone glucagon-like peptide-2 (GLP-2) plays important roles in regulating lipid handling and promoting anti-inflammatory functions in the intestine. During the postprandial state, it increases lipid absorption. During post-absorptive state, it mobilizes pre-formed chylomicrons. GLP-2 acts through vasoactive intestinal peptide (VIP) in reducing inflammation in rat ileum. However, this pathway has not yet been tested for GLP-2's effects on intestinal lipid handling. Here, in mesenteric lymph duct cannulated rats, we examined whether VIP signaling mediates GLP-2's effects on postprandial lipid absorption and post-absorptive lipid mobilization in the intestine. We administered a VIP receptor antagonist and analyzed lipid output in response to intraperitoneal GLP-2 or PBS during postprandial and post-absorptive states. VIP receptor antagonism reduced GLP-2 mediated lipid output in the post-absorptive state but had no effect during the postprandial state. These results show that GLP-2 functions differently during postprandial and post-absorptive states and VIP aids in GLP-2-mediated lipid output during the post-absorptive state.

Glucagon-like peptide-2 (GLP-2) has been reported to cause gastrointestinal relaxation by interfering with enteric inhibitory neurotransmitters, including vasoactive intestinal peptide (VIP). However, the involvement of VIP in the GLP-2's actions on isolated ileal preparations has never been explored. In this study, we investigated whether VIP contributes to the inhibitory effects of GLP-2 on spontaneous and neurally evoked contractions in mouse ileal segments. Functional experiments showed that VIP, as well as GLP-2, depresses both spontaneous and electrically induced contractile responses. The VIP antagonist, VIP 6-28, slightly increased the amplitude of the neurally induced contractile responses. VIP 6-28 did not alter the hormone's effects on the spontaneous activity, but reduced its inhibitory action on the neurally evoked contractions. In GLP-2-exposed specimens, immunohistochemistry showed a significant decrease in VIP-positivity in nerve fibers located in the muscle layers. These results provide the first evidence that in isolated mouse ileal preparations VIP contributes to the inhibitory effects of GLP-2 on the neurally induced contractile responses. From a physiological point of view, such depressant effects of the hormone may represent a mechanism aimed at slowing intestinal transit and optimizing nutrient absorption.

Background: Glucagon-like peptide-2 (GLP-2) is a gut hormone secreted in response to nutrient intake and regulates lipid metabolism in the gut. The present study aims to elucidate the underlying mechanism of GLP-2 in stimulating gut lipid secretion in the fasted state by testing whether GLP-2 signals through the brain’s GLP-2 receptor and melanocortin 4 receptor (MC4R). Methods: Sprague-Dawley rats were implanted with a mesenteric lymph duct cannula for measuring gut lipid secretion and an intracerebroventricular cannula for infusion of a GLP-2R antagonist (GLP-2(11-33)), an MC4R antagonist (SHU9119), or saline as a control. The rat received a lipid infusion into the small intestine and a peritoneal injection of GLP-2 five hours later. Results: Brain administration of a GLP-2R antagonist or an MC4R antagonist attenuated the stimulatory effects of peripheral GLP-2 on lymph triglyceride output. These effects were associated with differential changes in the expression of key genes in jejunal endothelial cells, smooth muscle cells, and neuronal cells. Conclusions: These results support the involvement of central GLP-2R and MC4R in a neural pathway for GLP-2 to mobilize lipids stored in the gut during the post-absorptive state.

Glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) are related intestinal L-cell derived secretory products. GLP-1 has been extensively studied in terms of its influence on metabolism, but less attention has been devoted to GLP-2 in this regard. The current study compares the effects of these proglucagon-derived peptides on pancreatic beta-cell function, as well as on glucose tolerance and appetite. The insulin secretory effects of GLP-1 and GLP-2 (10−12–10−6 M) were investigated in BRIN-BD11 beta-cells as well as isolated mouse islets, with the impact of test peptides (10 nM) on real-time cytosolic cAMP levels further evaluated in mouse islets. The impact of both peptides (10−8–10−6 M) on beta-cell growth and survival was also studied in BRIN BD11 cells. Acute in vivo (peptides administered at 25 nmol/kg) glucose homeostatic and appetite suppressive actions were then examined in healthy mice. GLP-1, but not GLP-2, concentration dependently augmented insulin secretion from BRIN-BD11 cells, with similar observations made in isolated murine islets. In addition, GLP-1 substantially increased [cAMP]cyt in islet cells and was significantly more prominent than GLP-2 in this regard. Both GLP-1 and GLP-2 promoted beta-cell proliferation and protected against cytokine-induced apoptosis. In overnight fasted healthy mice, as well as mice trained to eat for 3 h per day, the administration of GLP-1 or GLP-2 suppressed appetite. When injected conjointly with glucose, both peptides improved glucose disposal, which was associated with enhanced glucose-stimulated insulin secretion by GLP-1, but not GLP-2. To conclude, the impact of GLP-1 and GLP-2 on insulin secretion is divergent, but the effects of beta-cell signaling and overall health are similar. Moreover, the peripheral administration of either hormone in rodents results in comparable positive effects on blood glucose levels and appetite.

Glucagon-like peptide-2 (GLP-2) is a gut hormone that plays a pivotal role in regulating intestinal epithelial cell growth and function, making it a promising therapeutic agent for intestinal damage and bone-related diseases. Nonetheless, the therapeutic potential of GLP-2 is substantially diminished due to its inactivation by dipeptidyl peptidase 4 (DPP-4). In recent years, advancements have been made in developing dipeptidyl peptidase 4 (DPP-4) resistant GLP-2 analogues with an extended half-life. The murine model with extensive experimental bowel resection maintained on parenteral nutrition has been used for assessing the physiology and pharmacology of GLP-2, and for the preclinical validation of GLP-2 analogues. However, it possesses certain limitations, such as complex procedure, considerable variability, and time-consuming nature. Consequently, there is a pressing need for the development of a cell-based bioassay to assess GLP-2 analogues. Here, we successfully developed a mechanism-of-action (MOA)-reflective cell-based reporter gene assay (RGA), utilizing a stable HEK293 cell line expressing the GLP-2 receptor and a luciferase reporter gene. This innovative approach allows for precise quantification of the potency of GLP-2 analogues. The RGA demonstrated good accuracy, linearity, precision, and specificity, with potential applications in stability testing, drug screening, and therapeutic monitoring of GLP-2 analogues. Moreover, RNA sequencing reveals the multi-target regulatory effect of GLP-2 analogues. The establishment of this RGA provides a valuable tool for evaluating the potency of GLP-2 analogues and the screening of potential therapeutic drugs targeting to GLP-2 receptor.

We previously demonstrated that postruminal casein infusion and exogenous glucagon-like peptide 2 (GLP-2) administration independently stimulated growth and carbohydrase activity of the pancreas and jejunal mucosa in cattle. The objective of the current study was to profile the jejunal mucosal transcriptome of cattle using next-generation RNA sequencing in response to postruminal casein infusion and exogenous GLP-2. Twenty-four Holstein steers [250 ± 23.1 kg body weight (BW)] received a continuous abomasal infusion of 3.94 g raw corn starch/kg of BW combined with either 0 or 1.30 g casein/kg of BW for 7 d. Steers received subcutaneous injections at 0800 and 2000 h to provide either 0 or 100 μg GLP-2/kg of BW per day. At the end of the 7-d treatment period, steers were slaughtered for collection of the jejunal mucosa. Total RNA was extracted from jejunal mucosal tissue, strand-specific cDNA libraries were prepared, and RNA sequencing was conducted to generate 150-bp paired-end reads at a depth of 40 M reads per sample. Differentially expressed genes (DEG), KEGG pathway enrichment, and gene ontology enrichment were determined based on the FDR-corrected P -value ( padj ). Exogenous GLP-2 administration upregulated ( padj < 0.05) 667 genes and downregulated 1,101 genes of the jejunal mucosa. Sphingolipid metabolism, bile secretion, adherens junction, and galactose metabolism were among the top KEGG pathways enriched with upregulated DEG ( padj < 0.05) in response to exogenous GLP-2 administration. The top gene ontologies enriched with upregulated DEG ( padj < 0.05) in response to exogenous GLP-2 administration included nutrient metabolic processes, brush border and bicellular tight junction assembly, and enzyme and transporter activities. Exogenous GLP-2 administration increased or tended to increase ( padj < 0.10) brush border carbohydrase ( MGAM , LCT , TREH ), hexose transporter ( SLC5A1 , SLC2A2 ), and associated transcription factor ( HNF1 , GATA4 , KAT2B ) mRNA expression of the jejunal mucosa. Gene ontologies and KEGG pathways that were downregulated ( padj < 0.05) in response to exogenous GLP-2 were related to genetic information processing. Postruminal casein infusion downregulated ( padj < 0.05) 7 jejunal mucosal genes that collectively did not result in enriched KEGG pathways or gene ontologies. This study highlights some of the transcriptional mechanisms associated with increased growth, starch assimilation capacity, and barrier function of the jejunal mucosa in response to exogenous GLP-2 administration.

Glucagon-like peptide 2 (GLP-2) is derived from the proglucagon gene expressed in the intestines, pancreas and brain. Our previous study showed that GLP-2 improved lipopolysaccharide-induced memory impairments. The current study was designed to further investigated the potential of GLP-2 in memory impairment induced by intracerebroventricular administration of streptozotocin (ICV-STZ) in mice, which have been used as an animal model of sporadic Alzheimer’s disease (AD). STZ was administered on alternate days (Day-1 and Day-3) in order to induce dementia in male ddY mice. ICV-STZ-treated mice were administered GLP-2 (0.6 μg/mouse, ICV) for 5 days from 14 days after the first ICV administration of STZ. In these mice, we examined spatial working memory, the biochemical parameters of oxidative stress, or neurogenesis. The GLP-2 treatment restored spatial working memory in ICV-STZ-treated mice. ICV-STZ-treated mice showed markedly increased thiobarbituric acid reactive species (TBARS) and decreased glutathione (GSH) levels, and GLP-2 significantly restored these ICV-STZ-induced changes. GLP-2 also significantly restored neurogenesis in the subgranular zone of the dentate gyrus in ICV-STZ-treated mice. We herein demonstrated that GLP-2 significantly restored ICV-STZ-induced memory impairments as well as biochemical and histopathological alterations, and accordingly, propose that the memory restorative ability of GLP-2 is due to its potential to reduce oxidative stress.