|
1
|
Peart LA, Draper M, Tarasov AI. The impact of GLP-1 signalling on the energy metabolism of pancreatic islet β-cells and extrapancreatic tissues. Peptides 2024; 178:171243. [PMID: 38788902 DOI: 10.1016/j.peptides.2024.171243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/19/2024] [Accepted: 05/21/2024] [Indexed: 05/26/2024]
Abstract
Glucagon-like peptide-1 signalling impacts glucose homeostasis and appetite thereby indirectly affecting substrate availability at the whole-body level. The incretin canonically produces an insulinotropic effect, thereby lowering blood glucose levels by promoting the uptake and inhibiting the production of the sugar by peripheral tissues. Likewise, GLP-1 signalling within the central nervous system reduces the appetite and food intake, whereas its gastric effect delays the absorption of nutrients, thus improving glycaemic control and reducing the risk of postprandial hyperglycaemia. We review the molecular aspects of the GLP-1 signalling, focusing on its impact on intracellular energy metabolism. Whilst the incretin exerts its effects predominantly via a Gs receptor, which decodes the incretin signal into the elevation of intracellular cAMP levels, the downstream signalling cascades within the cell, acting on fast and slow timescales, resulting in an enhancement or an attenuation of glucose catabolism, respectively.
Collapse
Affiliation(s)
- Leah A Peart
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Matthew Draper
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Andrei I Tarasov
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK.
| |
Collapse
|
|
2
|
Zheng H, López-Ferreras L, Krieger JP, Fasul S, Cea Salazar V, Valderrama Pena N, Skibicka KP, Rinaman L. A Cre-driver rat model for anatomical and functional analysis of glucagon (Gcg)-expressing cells in the brain and periphery. Mol Metab 2022; 66:101631. [PMID: 36368622 PMCID: PMC9677222 DOI: 10.1016/j.molmet.2022.101631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/02/2022] [Accepted: 11/03/2022] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVE The glucagon gene (Gcg) encodes preproglucagon, which is cleaved to form glucagon-like peptide 1 (GLP1) and other mature signaling molecules implicated in metabolic functions. To date there are no transgenic rat models available for precise manipulation of GLP1-expressing cells in the brain and periphery. METHODS To visualize and manipulate Gcg-expressing cells in rats, CRISPR/Cas9 was used to express iCre under control of the Gcg promoter. Gcg-Cre rats were bred with tdTomato reporter rats to tag Gcg-expressing cells. Cre-dependent AAVs and RNAscope in situ hybridization were used to evaluate the specificity of iCre expression by GLP1 neurons in the caudal nucleus of the solitary tract (cNTS) and intermediate reticular nucleus (IRt), and by intestinal and pancreatic secretory cells. Food intake was assessed in heterozygous (Het) Gcg-Cre rats after chemogenetic stimulation of cNTS GLP1 neurons expressing an excitatory DREADD. RESULTS While genotype has minimal effect on body weight or composition in chow-fed Gcg-Cre rats, homozygous (Homo) rats have lower plasma glucose levels. In neonatal and adult Gcg-Cre/tdTom rats, reporter-labeled cells are present in the cNTS and IRt, and in additional brain regions (e.g., basolateral amygdala, piriform cortex) that lack detectable Gcg mRNA in adults but display transient developmental or persistently low Gcg expression. Compared to wildtype (WT) rats, hindbrain Gcg mRNA and GLP1 protein in brain and plasma are markedly reduced in Homo Gcg-Cre rats. Chemogenetic stimulation of cNTS GLP1 neurons reduced overnight chow intake in males but not females, the effect in males was blocked by antagonism of central GLP1 receptors, and hypophagia was enhanced when combined with a subthreshold dose of cholecystokinin-8 to stimulate gastrointestinal vagal afferents. CONCLUSIONS Gcg-Cre rats are a novel and valuable experimental tool for analyzing the development, anatomy, and function of Gcg-expressing cells in the brain and periphery. In addition, Homo Gcg-Cre rats are a unique model for assessing the role of Gcg-encoded proteins in glucose homeostasis and energy metabolism.
Collapse
Affiliation(s)
- Huiyuan Zheng
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Lorena López-Ferreras
- Institute of Neuroscience and Physiology, Department of Physiology/Metabolic Physiology, The Sahlgrenska Academy at University of Gothenburg, Sweden
| | - Jean-Phillipe Krieger
- Institute of Neuroscience and Physiology, Department of Physiology/Metabolic Physiology, The Sahlgrenska Academy at University of Gothenburg, Sweden
| | - Stephen Fasul
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Valentina Cea Salazar
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Natalia Valderrama Pena
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Karolina P. Skibicka
- Department of Nutritional Sciences, College of Health and Human Development, Huck Institute, The Pennsylvania State University, University Park, PA, USA,Institute of Neuroscience and Physiology, Department of Physiology/Metabolic Physiology, The Sahlgrenska Academy at University of Gothenburg, Sweden,Corresponding author. Department of Nutritional Sciences, Pennsylvania State University, 204 Chandlee Lab, University Park, PA 16802, USA
| | - Linda Rinaman
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA,Corresponding author. Department of Psychology, Program in Neuroscience, Florida State University, 1107 W. Call Street, Tallahassee, FL 32306, USA.
| |
Collapse
|