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Shcherbina L, Lindqvist A, Thorén Fischer AH, Ahlqvist E, Zhang E, Falkmer SE, Renström E, Koffert J, Honka H, Wierup N. Intestinal CART is a regulator of GIP and GLP-1 secretion and expression. Mol Cell Endocrinol 2018; 476:8-16. [PMID: 29627317 DOI: 10.1016/j.mce.2018.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 03/26/2018] [Accepted: 04/05/2018] [Indexed: 12/20/2022]
Abstract
Impaired incretin effect is a culprit in Type 2 Diabetes. Cocaine- and amphetamine-regulated transcript (CART) is a regulatory peptide controlling pancreatic islet hormone secretion and beta-cell survival. Here we studied the potential expression of CART in enteroendocrine cells and examined the role of CART as a regulator of incretin secretion and expression. CART expression was found in glucose-dependent insulinotropic polypeptide (GIP)-producing K-cells and glucagon-like peptide-1 (GLP-1)-producing L-cells in human duodenum and jejunum and circulating CART levels were increased 60 min after a meal in humans. CART expression was increased by fatty acids and GIP, but unaffected by glucose in GLUTag and STC-1 cells. Exogenous CART had no effect on GIP and GLP-1 expression and secretion in GLUTag or STC-1 cells, but siRNA-mediated silencing of CART reduced GLP-1 expression and secretion. Furthermore, acute intravenous administration of CART increased GIP and GLP-1 secretion during an oral glucose-tolerance test in mice. We conclude that CART is a novel constituent of human K- and L-cells with stimulatory actions on incretin secretion and that interfering with the CART system may be a therapeutic avenue for T2D.
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Affiliation(s)
| | - A Lindqvist
- Lund University Diabetes Centre, Malmö, Sweden
| | | | - E Ahlqvist
- Lund University Diabetes Centre, Malmö, Sweden
| | - E Zhang
- Lund University Diabetes Centre, Malmö, Sweden
| | - S E Falkmer
- Department of Clinical Pathology, Ryhov Hospital, Jönköping, Sweden
| | - E Renström
- Lund University Diabetes Centre, Malmö, Sweden
| | - J Koffert
- Turku PET Centre, University of Turku, Turku, Finland
| | - H Honka
- Turku PET Centre, University of Turku, Turku, Finland
| | - N Wierup
- Lund University Diabetes Centre, Malmö, Sweden.
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Karlsson HK, Tuulari JJ, Tuominen L, Hirvonen J, Honka H, Parkkola R, Helin S, Salminen P, Nuutila P, Nummenmaa L. Weight loss after bariatric surgery normalizes brain opioid receptors in morbid obesity. Mol Psychiatry 2016; 21:1057-62. [PMID: 26460230 DOI: 10.1038/mp.2015.153] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 08/05/2015] [Accepted: 08/10/2015] [Indexed: 12/13/2022]
Abstract
Positron emission tomography (PET) studies suggest opioidergic system dysfunction in morbid obesity, while evidence for the role of the dopaminergic system is less consistent. Whether opioid dysfunction represents a state or trait in obesity remains unresolved, but could be assessed in obese subjects undergoing weight loss. Here we measured brain μ-opioid receptor (MOR) and dopamine D2 receptor (D2R) availability in 16 morbidly obese women twice-before and 6 months after bariatric surgery-using PET with [(11)C]carfentanil and [(11)C]raclopride. Data were compared with those from 14 lean control subjects. Receptor-binding potentials (BPND) were compared between the groups and between the pre- and postoperative scans among the obese subjects. Brain MOR availability was initially lower among obese subjects, but weight loss (mean=26.1 kg, s.d.=7.6 kg) reversed this and resulted in ~23% higher MOR availability in the postoperative versus preoperative scan. Changes were observed in areas implicated in reward processing, including ventral striatum, insula, amygdala and thalamus (P's<0.005). Weight loss did not influence D2R availability in any brain region. Taken together, the endogenous opioid system plays an important role in the pathophysiology of human obesity. Because bariatric surgery and concomitant weight loss recover downregulated MOR availability, lowered MOR availability is associated with an obese phenotype and may mediate excessive energy uptake. Our results highlight that understanding the opioidergic contribution to overeating is critical for developing new treatments for obesity.
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Affiliation(s)
- H K Karlsson
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - J J Tuulari
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - L Tuominen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.,Department of Psychiatry, University of Turku and Turku University Hospital, Turku, Finland
| | - J Hirvonen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.,Medical Imaging Centre of Southwest Finland, Turku, Finland.,Department of Radiology, University of Turku and Turku University Hospital, Turku, Finland
| | - H Honka
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - R Parkkola
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.,Department of Radiology, University of Turku and Turku University Hospital, Turku, Finland
| | - S Helin
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - P Salminen
- Department of Digestive Surgery, University of Turku and Turku University Hospital, Turku, Finland
| | - P Nuutila
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.,Department of Endocrinology, Turku University Hospital, Turku, Finland
| | - L Nummenmaa
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.,Department of Neuroscience and Biomedical Engineering, School of Science, Aalto University, Espoo, Finland.,Department of Psychology, University of Turku, Turku, Finland
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Honka H, Mäkinen J, Hannukainen JC, Tarkia M, Oikonen V, Teräs M, Fagerholm V, Ishizu T, Saraste A, Stark C, Vähäsilta T, Salminen P, Kirjavainen A, Soinio M, Gastaldelli A, Knuuti J, Iozzo P, Nuutila P. Validation of [18F]fluorodeoxyglucose and positron emission tomography (PET) for the measurement of intestinal metabolism in pigs, and evidence of intestinal insulin resistance in patients with morbid obesity. Diabetologia 2013; 56:893-900. [PMID: 23334481 DOI: 10.1007/s00125-012-2825-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 12/17/2012] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS The role of the intestine in the pathogenesis of metabolic diseases is gaining much attention. We therefore sought to validate, using an animal model, the use of positron emission tomography (PET) in the estimation of intestinal glucose uptake (GU), and thereafter to test whether intestinal insulin-stimulated GU is altered in morbidly obese compared with healthy human participants. METHODS In the validation study, pigs were imaged using [(18)F]fluorodeoxyglucose ([(18)F]FDG) and the image-derived data were compared with corresponding ex vivo measurements in tissue samples and with arterial-venous differences in glucose and [(18)F]FDG levels. In the clinical study, GU was measured in different regions of the intestine in lean (n = 8) and morbidly obese (n = 8) humans at baseline and during euglycaemic hyperinsulinaemia. RESULTS PET- and ex vivo-derived intestinal values were strongly correlated and most of the fluorine-18-derived radioactivity was accumulated in the mucosal layer of the gut wall. In the gut wall of pigs, insulin promoted GU as determined by PET, the arterial-venous balance or autoradiography. In lean human participants, insulin increased GU from the circulation in the duodenum (from 1.3 ± 0.6 to 3.1 ± 1.1 μmol [100 g](-1) min(-1), p < 0.05) and in the jejunum (from 1.1 ± 0.7 to 3.0 ± 1.5 μmol [100 g](-1) min(-1), p < 0.05). Obese participants failed to show any increase in insulin-stimulated GU compared with fasting values (NS). CONCLUSIONS/INTERPRETATION Intestinal GU can be quantified in vivo by [(18)F]FDG PET. Intestinal insulin resistance occurs in obesity before the deterioration of systemic glucose tolerance.
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Affiliation(s)
- H Honka
- Turku PET Centre, University of Turku, PL 52, FIN-20520 Turku, Finland
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