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Pais ML, Crisóstomo J, Abrunhosa A, Castelo-Branco M. Central dopamine receptors: Radiotracers unveiling the Role of dopaminergic tone in obesity. J Mol Med (Berl) 2025; 103:21-32. [PMID: 39630278 PMCID: PMC11739276 DOI: 10.1007/s00109-024-02501-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2024] [Revised: 10/05/2024] [Accepted: 11/04/2024] [Indexed: 01/19/2025]
Abstract
Brain dopamine type 2 and 3 receptors (D2/3R) have been postulated to play a role in obesity. However, results from molecular neuroimaging studies exploring these receptors in obesity are not consensual. These inconsistencies may be due to the distinct characteristics of radiotracers that confound the interpretation of D2/3R assessment. Only three meta-analyses reported their results across radiotracers. Although all agree that obesity severity influences D2/3R availability, results vary for [11C]raclopride. Further, D2/3R assessment has been commonly interpreted as reflecting receptor density or availability. An alternative interpretation could be related to changes in endogenous central dopaminergic tone. The main question is whether the hypothesis of a quadratic relationship between dopaminergic tone and degree of obesity is suitable for the distinct characteristics of radiotracers. To answer this question and clarify the role of dopaminergic tone in obesity, we systematically reviewed this issue across radiotracers. Out of 514 articles, 15 articles were selected for review. Besides obesity severity, this study highlights the influence of radiotracer characteristics when assessing D2/3R. The tested hypothesis proved to be more suitable for radiotracers more susceptible to endogenous dopamine or with a lower affinity to D2/3R, supporting the quadratic relationship between dopaminergic tone and degree of obesity. While the role of D2/3R density in obesity may be relevant, dopaminergic tone seems to have a greater impact on the obesity-related differences found in these receptors. Finally, neuropsychological factors should be tested in addition to body mass index, as they may better reflect altered brain dopaminergic function.
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Affiliation(s)
- Marta Lapo Pais
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
- Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal
| | - Joana Crisóstomo
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal
- Champalimaud Research, Champalimaud Foundation, Lisbon, Portugal
| | - Antero Abrunhosa
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
| | - Miguel Castelo-Branco
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal.
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
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Dunn JP, Lamichhane B, Smith GI, Garner A, Wallendorf M, Hershey T, Klein S. Dorsal striatal response to taste is modified by obesity and insulin resistance. Obesity (Silver Spring) 2023; 31:2065-2075. [PMID: 37475685 PMCID: PMC10767984 DOI: 10.1002/oby.23799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 04/15/2023] [Accepted: 04/18/2023] [Indexed: 07/22/2023]
Abstract
OBJECTIVE In preclinical models, insulin resistance in the dorsal striatum (DS) contributes to overeating. Although human studies support the concept of central insulin resistance, they have not investigated its effect on consummatory reward-induced brain activity. METHODS Taste-induced activation was assessed in the caudate and putamen of the DS with blood oxygen level-dependent (BOLD) functional magnetic resonance imaging. Three phenotypically distinct groups were studied: metabolically healthy lean, metabolically healthy obesity, and metabolically unhealthy obesity (MUO; presumed to have central insulin resistance). Participants with MUO also completed a weight loss intervention followed by a second functional magnetic resonance imaging session. RESULTS The three groups were significantly different at baseline consistent with the design. The metabolically healthy lean group had a primarily positive BOLD response, the MUO group had a primarily negative BOLD response, and the metabolically healthy obesity group had a response in between the two other groups. Food craving was predicted by taste-induced activation. After weight loss in the MUO group, taste-induced activation increased in the DS. CONCLUSIONS These data support the hypothesis that insulin resistance and obesity contribute to aberrant responses to taste in the DS, which is only partially attenuated by weight loss. Aberrant responses to food exposure may be a barrier to weight loss.
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Affiliation(s)
- Julia P. Dunn
- VA St. Louis Health Care System, St. Louis, Missouri, USA
- Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Bidhan Lamichhane
- Department of Neurosurgery, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Gordon I. Smith
- Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Amy Garner
- VA St. Louis Health Care System, St. Louis, Missouri, USA
| | - Michael Wallendorf
- Division of Biostatistics, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Tamara Hershey
- Departments of Psychiatry and Radiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Samuel Klein
- Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
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Bini J. The historical progression of positron emission tomography research in neuroendocrinology. Front Neuroendocrinol 2023; 70:101081. [PMID: 37423505 PMCID: PMC10530506 DOI: 10.1016/j.yfrne.2023.101081] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 06/29/2023] [Accepted: 07/03/2023] [Indexed: 07/11/2023]
Abstract
The rapid and continual development of a number of radiopharmaceuticals targeting different receptor, enzyme and small molecule systems has fostered Positron Emission Tomography (PET) imaging of endocrine system actions in vivo in the human brain for several decades. PET radioligands have been developed to measure changes that are regulated by hormone action (e.g., glucose metabolism, cerebral blood flow, dopamine receptors) and actions within endocrine organs or glands such as steroids (e.g., glucocorticoids receptors), hormones (e.g., estrogen, insulin), and enzymes (e.g., aromatase). This systematic review is targeted to the neuroendocrinology community that may be interested in learning about positron emission tomography (PET) imaging for use in their research. Covering neuroendocrine PET research over the past half century, researchers and clinicians will be able to answer the question of where future research may benefit from the strengths of PET imaging.
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Affiliation(s)
- Jason Bini
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, United States.
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Janssen LK, Horstmann A. Molecular Imaging of Central Dopamine in Obesity: A Qualitative Review across Substrates and Radiotracers. Brain Sci 2022; 12:486. [PMID: 35448017 PMCID: PMC9031606 DOI: 10.3390/brainsci12040486] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 02/04/2023] Open
Abstract
Dopamine is a neurotransmitter that plays a crucial role in adaptive behavior. A wealth of studies suggests obesity-related alterations in the central dopamine system. The most direct evidence for such differences in humans comes from molecular neuroimaging studies using positron emission tomography (PET) and single-photon emission computed tomography (SPECT). The aim of the current review is to give a comprehensive overview of molecular neuroimaging studies that investigated the relation between BMI or weight status and any dopamine target in the striatal and midbrain regions of the human brain. A structured literature search was performed and a summary of the extracted findings are presented for each of the four available domains: (1) D2/D3 receptors, (2) dopamine release, (3) dopamine synthesis, and (4) dopamine transporters. Recent proposals of a nonlinear relationship between severity of obesity and dopamine imbalances are described while integrating findings within and across domains, after which limitations of the review are discussed. We conclude that despite many observed associations between obesity and substrates of the dopamine system in humans, it is unlikely that obesity can be traced back to a single dopaminergic cause or consequence. For effective personalized prevention and treatment of obesity, it will be crucial to identify possible dopamine (and non-dopamine) profiles and their functional characteristics.
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Affiliation(s)
- Lieneke Katharina Janssen
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany;
- Institute of Psychology, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany
| | - Annette Horstmann
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany;
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
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Kullmann S, Blum D, Jaghutriz BA, Gassenmaier C, Bender B, Häring HU, Reischl G, Preissl H, la Fougère C, Fritsche A, Reimold M, Heni M. Central Insulin Modulates Dopamine Signaling in the Human Striatum. J Clin Endocrinol Metab 2021; 106:2949-2961. [PMID: 34131733 DOI: 10.1210/clinem/dgab410] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Indexed: 01/17/2023]
Abstract
OBJECTIVE Activity in the dopaminergic pathways of the brain is highly sensitive to body weight and metabolic states. Animal studies show that dopamine neurons are important targets for the metabolic hormone insulin with abolished effects in the insulin-resistant state, leading to increases in body weight and food intake. In humans, the influence of central acting insulin on dopamine and effects of their interplay are still elusive. RESEARCH DESIGN AND METHODS We investigated whether central administered insulin influences dopaminergic activity in striatal regions and whole-brain neural activity. Using a positron emission tomography (PET)/magnetic resonance imaging (MRI) hybrid scanner, we simultaneously performed [11C]-raclopride-PET and resting-state functional MRI in 10 healthy normal-weight men after application of intranasal insulin or placebo on 2 separate days in a randomized, placebo-controlled, blinded, crossover trial. RESULTS In response to central insulin compared with placebo administration, we observed greater [11C]-raclopride binding potential in the bilateral ventral and dorsal striatum. This suggests an insulin-induced reduction in synaptic dopamine levels. Resting-state striatal activity was lower 15 and 30 minutes after nasal insulin compared with placebo. Functional connectivity of the mesocorticolimbic circuitry associated with differences in dopamine levels: individuals with a stronger insulin-induced effect on dopamine levels showed a stronger increase in functional connectivity 45 minutes after intranasal insulin. CONCLUSIONS This study indicates that central insulin modulates dopaminergic tone in the striatum, which may affect regional brain activity and connectivity. Our results deepen the understanding of the insulin-dopamine interaction and the complex network that underlies the regulation of whole-body metabolism.
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Affiliation(s)
- Stephanie Kullmann
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Dominik Blum
- Department of Nuclear Medicine and Clinical Molecular Imaging, Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Benjamin Assad Jaghutriz
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Christoph Gassenmaier
- Department of Internal Medicine, Division of Hematology, Oncology, Clinical Immunology and Rheumatology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Benjamin Bender
- Department of Diagnostic and Interventional Neuroradiology, University Hospital Tübingen, Tübingen, Germany
| | - Hans-Ulrich Häring
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Gerald Reischl
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Hubert Preissl
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- Department of Pharmacy and Biochemistry, Institute of Pharmaceutical Sciences, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Christian la Fougère
- Department of Nuclear Medicine and Clinical Molecular Imaging, Eberhard-Karls-University Tübingen, Tübingen, Germany
- Cluster of Excellence iFIT (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", University of Tübingen, Germany
| | - Andreas Fritsche
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Matthias Reimold
- Department of Nuclear Medicine and Clinical Molecular Imaging, Eberhard-Karls-University Tübingen, Tübingen, Germany
- Cluster of Excellence iFIT (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", University of Tübingen, Germany
| | - Martin Heni
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, Eberhard Karls University Tübingen, Tübingen, Germany
- Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital Tübingen, Tübingen, Germany
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Kullmann S, Kleinridders A, Small DM, Fritsche A, Häring HU, Preissl H, Heni M. Central nervous pathways of insulin action in the control of metabolism and food intake. Lancet Diabetes Endocrinol 2020; 8:524-534. [PMID: 32445739 DOI: 10.1016/s2213-8587(20)30113-3] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 01/22/2020] [Accepted: 03/20/2020] [Indexed: 12/18/2022]
Abstract
Insulin acts on the CNS to modulate behaviour and systemic metabolism. Disturbances in brain insulin action represent a possible link between metabolic and cognitive health. Current findings from human research suggest that boosting central insulin action in the brain modulates peripheral metabolism, enhancing whole-body insulin sensitivity and suppressing endogenous glucose production. Moreover, central insulin action curbs food intake by reducing the salience of highly palatable food cues and increasing cognitive control. Animal models show that the mesocorticolimbic circuitry is finely tuned in response to insulin, driven mainly by the dopamine system. These mechanisms are impaired in people with obesity, which might increase their risk of developing type 2 diabetes and associated diseases. Overall, current findings highlight the role of insulin action in the brain and its consequences on peripheral metabolism and cognition. Hence, improving central insulin action could represent a therapeutic option for people at an increased risk of developing metabolic and cognitive diseases.
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Affiliation(s)
- Stephanie Kullmann
- Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine, Division of Endocrinology, Diabetology, and Nephrology, Eberhard Karls University of Tübingen, Tübingen, Germany; German Center for Diabetes Research, Neuherberg, Germany.
| | - André Kleinridders
- German Center for Diabetes Research, Neuherberg, Germany; Central Regulation of Metabolism, German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany
| | - Dana M Small
- Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Psychiatry, Yale University, New Haven, CT, USA; Modern Diet and Physiology Research Centre, Yale University, New Haven, CT, USA
| | - Andreas Fritsche
- Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine, Division of Endocrinology, Diabetology, and Nephrology, Eberhard Karls University of Tübingen, Tübingen, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - Hans-Ulrich Häring
- Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; German Center for Diabetes Research, Neuherberg, Germany
| | - Hubert Preissl
- Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine, Division of Endocrinology, Diabetology, and Nephrology, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Pharmacy and Biochemistry, Interfaculty Centre for Pharmacogenomics and Pharma Research, Eberhard Karls University of Tübingen, Tübingen, Germany; German Center for Diabetes Research, Neuherberg, Germany; Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
| | - Martin Heni
- Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine, Division of Endocrinology, Diabetology, and Nephrology, Eberhard Karls University of Tübingen, Tübingen, Germany; German Center for Diabetes Research, Neuherberg, Germany
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