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Howell JA, Edwards AA, Santollo J. The estrogenic reduction in water intake stimulated by dehydration involves estrogen receptor alpha and a potential role for GLP-1. Physiol Behav 2024; 276:114484. [PMID: 38331374 PMCID: PMC10896180 DOI: 10.1016/j.physbeh.2024.114484] [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: 11/21/2023] [Revised: 01/11/2024] [Accepted: 02/05/2024] [Indexed: 02/10/2024]
Abstract
It is well documented that estrogens inhibit fluid intake. Most of this research, however, has focused on fluid intake in response to dipsogenic hormone and/or drug treatments in euhydrated rats. Additional research is needed to fully characterize the fluid intake effects of estradiol in response to true hypovolemia. As such, the goals of this series of experiments were to provide a detailed analysis of water intake in response to water deprivation in ovariectomized female rats treated with estradiol. In addition, these experiments also tested if activation of estrogen receptor alpha is sufficient to reduce water intake stimulated by water deprivation and tested for a role of glucagon like peptide-1 in the estrogenic control of water intake. As expected, estradiol reduced water intake in response to 24 and 48 h of water deprivation. The reduction in water intake was associated with a reduction in drinking burst number, with no change in drinking burst size. Pharmacological activation of estrogen receptor alpha reduced intake. Finally, estradiol-treatment caused a leftward shift in the behavioral dose response curve of exendin-4, the glucagon like peptide-1 agonist. While the highest dose of exendin-4 reduced 10 min intake in both oil and estradiol-treated rats, the intermediate dose only reduced intake in rats treated with estradiol. Together, this series of experiments extends previous research by providing a more thorough behavioral analysis of the anti-dipsogenic effect of estradiol in dehydrated rats, in addition to identifying the glucagon like peptide-1 system as a potential bioregulator involved in the underlying mechanisms by which estradiol reduces water intake in the female rat.
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Affiliation(s)
- Julia A Howell
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA
| | - Andrea A Edwards
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA
| | - Jessica Santollo
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA.
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2
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Papamargaritis D, le Roux CW, Holst JJ, Davies MJ. New therapies for obesity. Cardiovasc Res 2024; 119:2825-2842. [PMID: 36448672 PMCID: PMC10874276 DOI: 10.1093/cvr/cvac176] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 09/16/2022] [Accepted: 10/19/2022] [Indexed: 02/17/2024] Open
Abstract
Obesity is a chronic disease associated with serious complications and increased mortality. Weight loss (WL) through lifestyle changes results in modest WL long-term possibly due to compensatory biological adaptations (increased appetite and reduced energy expenditure) promoting weight gain. Bariatric surgery was until recently the only intervention that consistently resulted in ≥ 15% WL and maintenance. Our better understanding of the endocrine regulation of appetite has led to the development of new medications over the last decade for the treatment of obesity with main target the reduction of appetite. The efficacy of semaglutide 2.4 mg/week-the latest glucagon-like peptide-1 (GLP-1) receptor analogue-on WL for people with obesity suggests that we are entering a new era in obesity pharmacotherapy where ≥15% WL is feasible. Moreover, the WL achieved with the dual agonist tirzepatide (GLP-1/glucose-dependent insulinotropic polypeptide) for people with type 2 diabetes and most recently also obesity, indicate that combining the GLP-1 with other gut hormones may lead to additional WL compared with GLP-1 receptor analogues alone and in the future, multi-agonist molecules may offer the potential to bridge further the efficacy gap between bariatric surgery and the currently available pharmacotherapies.
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Affiliation(s)
- Dimitris Papamargaritis
- Diabetes Research Centre, Leicester General Hospital, University of Leicester College of Medicine Biological Sciences and Psychology, Leicester LE5 4PW, UK
| | - Carel W le Roux
- Diabetes Complications Research Centre, Conway Institute, University College Dublin, Dublin 4, Ireland
- Diabetes Research Centre, Ulster University, Coleraine BT52 1SA, UK
| | - Jens J Holst
- Department of Biomedical Sciences and the NNF Center for Basic Metabolic Research, University of Copenhagen Panum Institute, Copenhagen 2200, Denmark
| | - Melanie J Davies
- Diabetes Research Centre, Leicester General Hospital, University of Leicester College of Medicine Biological Sciences and Psychology, Leicester LE5 4PW, UK
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Cawthon CR, Blonde GD, Nisi AV, Bloomston HM, Krubitski B, le Roux CW, Spector AC. Chronic Semaglutide Treatment in Rats Leads to Daily Excessive Concentration-Dependent Sucrose Intake. J Endocr Soc 2023; 7:bvad074. [PMID: 37388574 PMCID: PMC10306276 DOI: 10.1210/jendso/bvad074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Indexed: 07/01/2023] Open
Abstract
Context The glucagon-like peptide-1 receptor (GLP-1R) agonist semaglutide (SEMA) produces 15% weight loss when chronically administered to humans with obesity. Methods In 2 separate experiments, rats received daily injections of either vehicle (VEH) or SEMA starting at 7 µg/kg body weight (BW) and increasing over 10 days to the maintenance dose (70 µg/kg-BW), emulating clinical dose escalation strategies. Results During dose escalation and maintenance, SEMA rats reduced chow intake and bodyweight. Experiment 2 meal pattern analysis revealed that meal size, not number, mediated these SEMA-induced changes in chow intake. This suggests SEMA affects neural processes controlling meal termination and not meal initiation. Two-bottle preference tests (vs water) began after 10 to 16 days of maintenance dosing. Rats received either an ascending sucrose concentration series (0.03-1.0 M) and 1 fat solution (Experiment 1) or a 4% and 24% sucrose solution in a crossover design (Experiment 2). At lower sucrose concentrations, SEMA-treated rats in both experiments drank sometimes >2× the volume consumed by VEH controls; at higher sucrose concentrations (and 10% fat), intake was similar between treatment groups. Energy intake of SEMA rats became similar to VEH rats. This was unexpected because GLP-1R agonism is thought to decrease the reward and/or increase the satiating potency of palatable foods. Despite sucrose-driven increases in both groups, a significant bodyweight difference between SEMA- and VEH-treated rats remained. Conclusion The basis of the SEMA-induced overconsumption of sucrose at lower concentrations relative to VEH controls remains unclear, but the effects of chronic SEMA treatment on energy intake and BW appear to depend on the caloric sources available.
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Affiliation(s)
- Carolina R Cawthon
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Ginger D Blonde
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - A Valentina Nisi
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Haley M Bloomston
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Belle Krubitski
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
| | - Carel W le Roux
- Diabetes Complications Research Center, Conway Institute, School of Medicine, University College Dublin, Dublin, D04 C1P1, Ireland
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA
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Signaling pathways in obesity: mechanisms and therapeutic interventions. Signal Transduct Target Ther 2022; 7:298. [PMID: 36031641 PMCID: PMC9420733 DOI: 10.1038/s41392-022-01149-x] [Citation(s) in RCA: 78] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 07/26/2022] [Accepted: 08/08/2022] [Indexed: 12/19/2022] Open
Abstract
Obesity is a complex, chronic disease and global public health challenge. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine.
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Trapp S, Stanford SC. New developments in the prospects for GLP-1 therapy. Br J Pharmacol 2022; 179:489-491. [PMID: 35107170 DOI: 10.1111/bph.15788] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Stefan Trapp
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - S Clare Stanford
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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Holst JJ. Treatment of Type 2 Diabetes and Obesity on the Basis of the Incretin System: The 2021 Banting Medal for Scientific Achievement Award Lecture. Diabetes 2021; 70:2468-2475. [PMID: 34711671 PMCID: PMC8928930 DOI: 10.2337/dbi21-0026] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In my lecture given on the occasion of the 2021 Banting Medal for Scientific Achievement, I briefly described the history of the incretin effect and summarized some of the developments leading to current therapies of obesity and diabetes based on the incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). In the text below, I discuss in further detail the role of these two hormones for postprandial insulin secretion in humans on the basis of recent studies with antagonists. Their direct and indirect actions on the β-cells are discussed next as well as their contrasting actions on glucagon secretion. After a brief discussion of their effect on insulin sensitivity, I describe their immediate actions in patients with type 2 diabetes and emphasize the actions of GLP-1 on β-cell glucose sensitivity, followed by a discussion of their extrapancreatic actions, including effects on appetite and food intake in humans. Finally, possible mechanisms of action of GIP-GLP-1 coagonists are discussed, and it is concluded that therapies based on incretin actions are likely to change the current hesitant therapy of both obesity and diabetes.
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Affiliation(s)
- Jens Juul Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark
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Blonde GD, Price RK, le Roux CW, Spector AC. Meal Patterns and Food Choices of Female Rats Fed a Cafeteria-Style Diet Are Altered by Gastric Bypass Surgery. Nutrients 2021; 13:3856. [PMID: 34836110 PMCID: PMC8623594 DOI: 10.3390/nu13113856] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/21/2021] [Accepted: 10/26/2021] [Indexed: 12/28/2022] Open
Abstract
After Roux-en-Y gastric bypass surgery (RYGB), rats tend to reduce consumption of high-sugar and/or high-fat foods over time. Here, we sought to investigate the behavioral mechanisms underlying these intake outcomes. Adult female rats were provided a cafeteria diet comprised of five palatable foodstuffs varying in sugar and fat content and intake was monitored continuously. Rats were then assigned to either RYGB, or one of two control (CTL) groups: sham surgery or a nonsurgical control group receiving the same prophylactic iron treatments as RYGB rats. Post-sur-gically, all rats consumed a large first meal of the cafeteria diet. After the first meal, RYGB rats reduced intake primarily by decreasing the meal sizes relative to CTL rats, ate meals more slowly, and displayed altered nycthemeral timing of intake yielding more daytime meals and fewer nighttime meals. Collectively, these meal patterns indicate that despite being motivated to consume a cafeteria diet after RYGB, rats rapidly learn to modify eating behaviors to consume foods more slowly across the entire day. RYGB rats also altered food preferences, but more slowly than the changes in meal patterns, and ate proportionally more energy from complex carbohydrates and protein and proportionally less fat. Overall, the pattern of results suggests that after RYGB rats quickly learn to adjust their size, eating rate, and distribution of meals without altering meal number and to shift their macronutrient intake away from fat; these changes appear to be more related to postingestive events than to a fundamental decline in the palatability of food choices.
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Affiliation(s)
- Ginger D. Blonde
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA;
| | - Ruth K. Price
- Nutrition Innovation Centre for Food and Health (NICHE), School of Biomedical Sciences, Ulster University, Coleraine BT52 1SA, UK;
| | - Carel W. le Roux
- Diabetes Complications Research Centre, Conway Institute, School of Medicine, University College Dublin, D04 V1W8 Dublin, Ireland;
| | - Alan C. Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA;
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Trapp S, Brierley DI. Brain GLP-1 and the regulation of food intake: GLP-1 action in the brain and its implications for GLP-1 receptor agonists in obesity treatment. Br J Pharmacol 2021; 179:557-570. [PMID: 34323288 PMCID: PMC8820179 DOI: 10.1111/bph.15638] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/22/2021] [Accepted: 07/03/2021] [Indexed: 12/19/2022] Open
Abstract
This review considers the similarities and differences between the physiological systems regulated by gut-derived and neuronally produced glucagon-like peptide 1 (GLP-1). It addresses the questions of whether peripheral and central GLP-1 sources constitute separate, linked or redundant systems and whether the brain GLP-1 system consists of disparate sections or is a homogenous entity. This review also explores the implications of the answers to these questions for the use of GLP-1 receptor agonists as anti-obesity drugs.
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Affiliation(s)
- Stefan Trapp
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Daniel I Brierley
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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