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Idrizaj E, Biagioni C, Traini C, Vannucchi MG, Baccari MC. Glucagon-like Peptide-2 Depresses Ileal Contractility in Preparations from Mice through Opposite Modulatory Effects on Nitrergic and Cholinergic Neurotransmission. Int J Mol Sci 2024; 25:1855. [PMID: 38339131 PMCID: PMC10855646 DOI: 10.3390/ijms25031855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 01/26/2024] [Accepted: 01/31/2024] [Indexed: 02/12/2024] Open
Abstract
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.
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Affiliation(s)
- Eglantina Idrizaj
- Section of Physiological Sciences, Department of Experimental & Clinical Medicine, University of Florence, 50139 Florence, Italy;
| | - Cristina Biagioni
- Research Unit of Histology & Embryology, Department of Experimental & Clinical Medicine, University of Florence, 50139 Florence, Italy; (C.B.); (C.T.)
| | - Chiara Traini
- Research Unit of Histology & Embryology, Department of Experimental & Clinical Medicine, University of Florence, 50139 Florence, Italy; (C.B.); (C.T.)
| | - Maria Giuliana Vannucchi
- Research Unit of Histology & Embryology, Department of Experimental & Clinical Medicine, University of Florence, 50139 Florence, Italy; (C.B.); (C.T.)
| | - Maria Caterina Baccari
- Section of Physiological Sciences, Department of Experimental & Clinical Medicine, University of Florence, 50139 Florence, Italy;
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Skov-Jeppesen K, Christiansen CB, Hansen LS, Windeløv JA, Hedbäck N, Gasbjerg LS, Hindsø M, Svane MS, Madsbad S, Holst JJ, Rosenkilde MM, Hartmann B. Effects of exogenous GIP and GLP-2 on bone turnover in individuals with type 2 diabetes. J Clin Endocrinol Metab 2024:dgae022. [PMID: 38217866 DOI: 10.1210/clinem/dgae022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 12/11/2023] [Accepted: 01/09/2024] [Indexed: 01/15/2024]
Abstract
CONTEXT Individuals with type 2 diabetes (T2D) have an increased risk of bone fractures despite normal or increased bone mineral density (BMD). The underlying causes are not well understood but may include disturbances in the gut-bone axis, in which both glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-2 (GLP-2) are regulators of bone turnover. Thus, in healthy fasting participants, both exogenous GIP and GLP-2 acutely reduce bone resorption. OBJECTIVE The objective of this study was to investigate the acute effects of subcutaneously administered GIP and GLP-2 on bone turnover in individuals with T2D. METHODS We included 10 men with T2D. Participants met fasting in the morning on three separate test days and were injected subcutaneously with GIP, GLP-2, or placebo in a randomized crossover design. Blood samples were drawn at baseline and regularly after injections. Bone turnover was estimated by circulating levels of collagen type 1 C-terminal telopeptide (CTX), procollagen type 1 N-terminal propeptide (P1NP), sclerostin, and PTH. RESULTS GIP and GLP-2 significantly reduced CTX to (mean ± SEM) 66 ± 7.8% and 74 ± 5.9% of baseline, respectively, compared with after placebo (p = 0.001). In addition, P1NP and sclerostin increased acutely after GIP whereas a decrease in P1NP was seen after GLP-2. PTH levels decreased to 67 ± 2.5% of baseline after GLP-2 and to only 86 ± 3.4% after GIP. CONCLUSION Subcutaneous GIP and GLP-2 affect CTX and P1NP in individuals with T2D to the same extent as previously demonstrated in healthy individuals.
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Affiliation(s)
- Kirsa Skov-Jeppesen
- Department of Biomedical Sciences, University of Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Denmark
| | - Charlotte B Christiansen
- Department of Biomedical Sciences, University of Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Denmark
| | - Laura S Hansen
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
| | - Johanne A Windeløv
- Department of Biomedical Sciences, University of Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Denmark
| | - Nora Hedbäck
- Department of Endocrinology, Hvidovre University Hospital, Denmark
| | - Lærke S Gasbjerg
- Department of Biomedical Sciences, University of Copenhagen, Denmark
| | - Morten Hindsø
- Department of Endocrinology, Hvidovre University Hospital, Denmark
| | - Maria S Svane
- Department of Endocrinology, Hvidovre University Hospital, Denmark
| | - Sten Madsbad
- Department of Endocrinology, Hvidovre University Hospital, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, University of Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Denmark
| | | | - Bolette Hartmann
- Department of Biomedical Sciences, University of Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Denmark
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Gabe MBN, von Voss L, Hunt JE, Gadgaard S, Gasbjerg LS, Holst JJ, Kissow H, Hartmann B, Rosenkilde MM. Biased GLP-2 agonist with strong G protein-coupling but impaired arrestin recruitment and receptor desensitization enhances intestinal growth in mice. Br J Pharmacol 2023. [PMID: 36683195 DOI: 10.1111/bph.16040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 12/04/2022] [Accepted: 01/15/2023] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND AND PURPOSE Glucagon-like peptide-2 (GLP-2) is secreted postprandially by enteroendocrine L-cells and stimulates growth of the gut and bone. One GLP-2 analogue is approved for short bowel syndrome (SBS). To improve therapeutic efficacy, we developed biased GLP-2 receptor (GLP-2R) agonists through N-terminal modifications. EXPERIMENTAL APPROACH Variants with Ala and Trp substitutions of the first seven positions of GLP-2(1-33) were studied in vitro for affinity, G protein activation (cAMP accumulation), recruitment of β-arrestin 1 and 2, and internalization of the human and mouse GLP-2R. The intestinotrophic actions of the most efficacious (cAMP) biased variant were examined in mice. KEY RESULTS Ala substitutions had more profound effects than Trp substitutions. For both, alterations at positions 1, 3 and 6 most severely impaired activity. β-arrestin recruitment was more affected than cAMP accumulation. Among Ala substitutions, [H1A], [D3A] and [F6A] impaired potency (EC50 ) for cAMP-accumulation >20-fold and efficacy (Emax ) to 48%-87%, and were unable to recruit arrestins. The Trp substitutions, [A2W], [D3W] and [G4W] were partial agonists (Emax of 46%-59%) with 1.7-12-fold decreased potencies in cAMP and diminished β-arrestin recruitment. The biased variants, [F6A], [F6W] and [S7W] induced less GLP-2R internalization compared with GLP-2, which induced internalization in a partly arrestin-independent manner. In mice, [S7W] enhanced gut trophic actions with increased weight of the small intestine, increased villus height and crypt depth compared with GLP-2. CONCLUSION AND IMPLICATIONS G protein-biased GLP-2R agonists with diminished receptor desensitization have superior intestinotrophic effects and may represent improved treatment of intestinal insufficiency including SBS.
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Affiliation(s)
- Maria Buur Nordskov Gabe
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Liv von Voss
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jenna Elizabeth Hunt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sarina Gadgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Laerke Smidt Gasbjerg
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Juul Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hannelouise Kissow
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mette Marie Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Baldassano S, Gasbjerg LS, Kizilkaya HS, Rosenkilde MM, Holst JJ, Hartmann B. Increased Body Weight and Fat Mass After Subchronic GIP Receptor Antagonist, but Not GLP-2 Receptor Antagonist, Administration in Rats. Front Endocrinol (Lausanne) 2019; 10:492. [PMID: 31447774 PMCID: PMC6691063 DOI: 10.3389/fendo.2019.00492] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/08/2019] [Indexed: 12/20/2022] Open
Abstract
Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-2 (GLP-2) are hormones secreted from the enteroendocrine cells after a meal. They exert their actions through activation of G protein-coupled receptors (R), the GIPR and GLP-2R, respectively. Both have been reported to influence metabolism. The purpose of the study was to investigate the role of the hormones in the regulation of lipid and bone homeostasis by subchronic treatment with novel GIPR and GLP-2R antagonists. Rats were injected once daily with vehicle, GIPR, or GLP-2R antagonists for 3 weeks. Body weight, food intake, body composition, plasma lipoprotein lipase (LPL), adipokines, triglycerides and the marker of bone resorption carboxy-terminal collagen crosslinks (CTX), were examined. In rats, subchronic treatment with GIPR antagonist, rat GIP (3-30)NH2, did not modify food intake and bone resorption, but significantly increased body weight, body fat mass, triglycerides, LPL, and leptin levels compared with vehicle treated rats. Subchronic (Pro3)GIP (a partial GIPR agonist), GLP-2(11-33), and GLP-2(3-33) (GLP-2R antagonists) treatment did not affect any parameter. The present results would be consistent with a role for GIP, but not GLP-2, in the maintenance of lipid homeostasis in rats, while neither GIPR nor GLP-2R antagonism appeared to influence bone resorption in rats.
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Affiliation(s)
- Sara Baldassano
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Università di Palermo, Palermo, Italy
| | - Lærke Smidt Gasbjerg
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Jens Juul Holst
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
- *Correspondence: Bolette Hartmann
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