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Leptin Increases: Physiological Roles in the Control of Sympathetic Nerve Activity, Energy Balance, and the Hypothalamic-Pituitary-Thyroid Axis. Int J Mol Sci 2023; 24:ijms24032684. [PMID: 36769012 PMCID: PMC9917048 DOI: 10.3390/ijms24032684] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/17/2023] [Accepted: 01/21/2023] [Indexed: 02/04/2023] Open
Abstract
It is well established that decreases in plasma leptin levels, as with fasting, signal starvation and elicit appropriate physiological responses, such as increasing the drive to eat and decreasing energy expenditure. These responses are mediated largely by suppression of the actions of leptin in the hypothalamus, most notably on arcuate nucleus (ArcN) orexigenic neuropeptide Y neurons and anorexic pro-opiomelanocortin neurons. However, the question addressed in this review is whether the effects of increased leptin levels are also significant on the long-term control of energy balance, despite conventional wisdom to the contrary. We focus on leptin's actions (in both lean and obese individuals) to decrease food intake, increase sympathetic nerve activity, and support the hypothalamic-pituitary-thyroid axis, with particular attention to sex differences. We also elaborate on obesity-induced inflammation and its role in the altered actions of leptin during obesity.
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Blonde GD, Mathes CM, Inui T, Hamel EA, Price RK, Livingstone MBE, Le Roux CW, Spector AC. Oromotor and somatic taste reactivity during sucrose meals reveals internal state and stimulus palatability after gastric bypass in rats. Am J Physiol Regul Integr Comp Physiol 2022; 322:R204-R218. [PMID: 35043683 PMCID: PMC8858674 DOI: 10.1152/ajpregu.00285.2021] [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: 11/19/2021] [Revised: 01/07/2022] [Accepted: 01/12/2022] [Indexed: 11/22/2022]
Abstract
After Roux-en-Y gastric bypass (RYGB), rats consume less high-energy foods and fluids, though whether this reflects a concomitant change in palatability remains unclear. By measuring behavior during intraorally delivered liquid meals across days (1 water, 8 sucrose sessions), we showed that RYGB rats (RYGB, n = 8/sex) consumed less 1.0 M sucrose than their sham surgery counterparts (SHAM, n = 8 males, n = 11 females) but displayed similarly high levels of ingestive taste reactivity responses at the start of infusions. Relative to water, both groups increased intake of sucrose, and ingestive responses were dominated by tongue protrusions rather than mouth movements. Thus, RYGB animals still found sucrose palatable despite consuming less than the SHAM group. As the intraoral infusion progressed but before meal termination, aversive behavior remained low and both RYGB and SHAM animals showed fewer ingestive responses, predominantly mouth movements as opposed to tongue protrusions. This shift in responsiveness unrelated to surgical manipulation suggests negative alliesthesia, or a decreased palatability, as rats approach satiation. Notably, only in RYGB rats, across sessions, there was a striking emergence of aversive behavior immediately after the sucrose meal. Thus, although lower intake in RYGB rats seems independent of the hedonic taste properties of sucrose, taste reactivity behavior in these animals immediately after termination of a liquid meal appears to be influenced by postoral events and reflects a state of nimiety or excessive consumption. Measurement of taste reactivity behaviors during an intraorally delivered meal represents a promising way to make inferences about internal state in nonverbal preclinical models.
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Affiliation(s)
- Ginger D Blonde
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
| | - Clare M Mathes
- Department of Neuroscience, Baldwin Wallace University, Berea, Ohio
| | - Tadashi Inui
- Department of Oral Physiology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan
| | - Elizabeth A Hamel
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
| | - Ruth K Price
- Nutrition Innovation Centre for Food and Health (NICHE), School of Biomedical Sciences, Ulster University, Coleraine, United Kingdom
| | - M Barbara E Livingstone
- Nutrition Innovation Centre for Food and Health (NICHE), School of Biomedical Sciences, Ulster University, Coleraine, United Kingdom
| | - Carel W Le Roux
- Diabetes Complications Research Centre, Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
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Chen J, Haase N, Haange SB, Sucher R, Münzker J, Jäger E, Schischke K, Seyfried F, von Bergen M, Hankir MK, Krügel U, Fenske WK. Roux-en-Y gastric bypass contributes to weight loss-independent improvement in hypothalamic inflammation and leptin sensitivity through gut-microglia-neuron-crosstalk. Mol Metab 2021; 48:101214. [PMID: 33741533 PMCID: PMC8095174 DOI: 10.1016/j.molmet.2021.101214] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/20/2021] [Accepted: 03/12/2021] [Indexed: 12/13/2022] Open
Abstract
Objective Hypothalamic inflammation and endoplasmic reticulum (ER) stress are extensively linked to leptin resistance and overnutrition-related diseases. Surgical intervention remains the most efficient long-term weight-loss strategy for morbid obesity, but mechanisms underlying sustained feeding suppression remain largely elusive. This study investigated whether Roux-en-Y gastric bypass (RYGB) interacts with obesity-associated hypothalamic inflammation to restore central leptin signaling as a mechanistic account for post-operative appetite suppression. Methods RYGB or sham surgery was performed in high-fat diet-induced obese Wistar rats. Sham-operated rats were fed ad libitum or by weight matching to RYGB via calorie restriction (CR) before hypothalamic leptin signaling, microglia reactivity, and the inflammatory pathways were examined to be under the control of gut microbiota-derived circulating signaling. Results RYGB, other than CR-induced adiposity reduction, ameliorates hypothalamic gliosis, inflammatory signaling, and ER stress, which are linked to enhanced hypothalamic leptin signaling and responsiveness. Mechanistically, we demonstrate that RYGB interferes with hypothalamic ER stress and toll-like receptor 4 (TLR4) signaling to restore the anorexigenic action of leptin, which most likely results from modulation of a circulating factor derived from the altered gut microbial environment upon RYGB surgery. Conclusions Our data demonstrate that RYGB interferes with hypothalamic TLR4 signaling to restore the anorexigenic action of leptin, which most likely results from modulation of a circulating factor derived from the post-surgical altered gut microbial environment. RYGB surgery-related weight loss independently restores hypothalamic leptin signaling and action in diet-induced obesity. RGYB modulates hypothalamic TLR4-mediated pro-inflammatory signaling and ER stress to restore leptin's anorexigenic action. Humoral factors contribute to modulated microglia-POMC neuron interaction, which appears specific to the RYGB procedure. Altering the gut microbiota environment by antibiotics deteriorates leptin's feeding suppressive action after RYGB.
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Affiliation(s)
- Jiesi Chen
- Medical Department III, Endocrinology, Nephrology, and Rheumatology, University Hospital of Leipzig, Leipzig, Germany
| | - Nadine Haase
- Medical Department III, Endocrinology, Nephrology, and Rheumatology, University Hospital of Leipzig, Leipzig, Germany
| | - Sven-Bastiaan Haange
- Department of Molecular Systems Biology, Helmholtz Center for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Robert Sucher
- Division of Bariatric Surgery, Clinic of Visceral, Transplant, Thoracic, and Vascular Surgery, University Hospital, Liebigstraße 20, D-4015, Leipzig, Germany
| | - Julia Münzker
- Medical Department III, Endocrinology, Nephrology, and Rheumatology, University Hospital of Leipzig, Leipzig, Germany
| | - Elisabeth Jäger
- Medical Department III, Endocrinology, Nephrology, and Rheumatology, University Hospital of Leipzig, Leipzig, Germany
| | - Kristin Schischke
- Medical Department III, Endocrinology, Nephrology, and Rheumatology, University Hospital of Leipzig, Leipzig, Germany
| | - Florian Seyfried
- Department of General, Visceral, Transplant, Vascular, and Pediatric Surgery, University Hospital, Würzburg, Germany
| | - Martin von Bergen
- Department of Molecular Systems Biology, Helmholtz Center for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany; Institute of Biochemistry, Faculty of Life Sciences, University of Leipzig, Talstraße 33, 04103 Leipzig, Germany
| | - Mohammed K Hankir
- Department of Experimental Surgery, University Hospital Würzburg, 97080 Würzburg, Germany
| | - Ute Krügel
- Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstraße 16-18, 04107 Leipzig, Germany
| | - Wiebke K Fenske
- Medical Department III, Endocrinology, Nephrology, and Rheumatology, University Hospital of Leipzig, Leipzig, Germany; Division of Endocrinology, Diabetes, and Metabolism, Medical Department I, University Hospital of Bonn, Bonn, Germany.
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Abstract
Reviewed here are multiple mouse models of vertical sleeve gastrectomy (VSG) and Roux-en Y gastric bypass (RYGB) that have emerged over the past decade. These models use diverse approaches to both operative and perioperative procedures. Scrutinizing the benefits and pitfalls of each surgical model and what to expect in terms of post-operative outcomes will enhance our assessment of studies using mouse models, as well as advance our understanding of their translational potential. Two mouse models of bariatric surgery, VSG-lembert and RYGB-small pouch, demonstrate low mortality and most closely recapitulate the human forms of surgery. The use of liquid diets can be minimized, and in mice, RYGB demonstrates more reliable and longer lasting effects on weight loss compared to that of VSG.
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Hankir MK, Seyfried F, Miras AD, Cowley MA. Brain Feeding Circuits after Roux-en-Y Gastric Bypass. Trends Endocrinol Metab 2018; 29:218-237. [PMID: 29475578 DOI: 10.1016/j.tem.2018.01.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 01/17/2018] [Accepted: 01/25/2018] [Indexed: 12/12/2022]
Abstract
Metabolic surgical procedures, such as Roux-en-Y gastric bypass (RYGB), uniquely reprogram feeding behavior and body weight in obese subjects. Clinical neuroimaging and animal studies are only now beginning to shed light on some of the underlying central mechanisms. We present here the roles of key brain neurotransmitter/neuromodulator systems in food choice, value, and intake at various stages after RYGB. In doing so, we elaborate on how known signals emanating from the reorganized gut, including peptide hormones and microbiota products, impinge on newly mapped homeostatic and hedonic brain feeding circuits. Continued progress in the rapidly evolving field of metabolic surgery will inform the design of more effective weight-loss compounds.
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Affiliation(s)
- Mohammed K Hankir
- Department of Experimental Surgery, University Hospital Wuerzburg, Wuerzburg, Bavaria 97080, Germany; German Research Foundation Collaborative Research Center in Obesity Mechanisms, University of Leipzig, Leipzig, Saxony 04103, Germany.
| | - Florian Seyfried
- Department of Experimental Surgery, University Hospital Wuerzburg, Wuerzburg, Bavaria 97080, Germany
| | - Alexander D Miras
- Department of Investigative Science, Imperial College London Academic Healthcare Centre, London W12 0NN, UK
| | - Michael A Cowley
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Victoria 3800, Australia; Department of Physiology, Monash University, Victoria 3800, Australia
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Monomeric GLP-1/GIP/glucagon triagonism corrects obesity, hepatosteatosis, and dyslipidemia in female mice. Mol Metab 2017; 6:440-446. [PMID: 28462078 PMCID: PMC5404097 DOI: 10.1016/j.molmet.2017.02.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 02/06/2017] [Accepted: 02/08/2017] [Indexed: 12/21/2022] Open
Abstract
Objective Obesity is a major health threat that affects men and women equally. Despite this fact, weight-loss potential of pharmacotherapies is typically first evaluated in male mouse models of diet-induced obesity (DIO). To address this disparity we herein determined whether a monomeric peptide with agonism at the receptors for glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon is equally efficient in correcting DIO, dyslipidemia, and glucose metabolism in DIO female mice as it has been previously established for DIO male mice. Methods Female C57BL/6J mice and a cohort of fatmass-matched C57BL/6J male mice were treated for 27 days via subcutaneous injections with either the GLP-1/GIP/glucagon triagonist or PBS. A second cohort of C57BL/6J male mice was included to match the females in the duration of the high-fat, high-sugar diet (HFD) exposure. Results Our results show that GLP-1/GIP/glucagon triple agonism inhibits food intake and decreases body weight and body fat mass with comparable potency in male and female mice that have been matched for body fat mass. Treatment improved dyslipidemia in both sexes and reversed diet-induced steatohepatitis to a larger extent in female mice compared to male mice. Conclusions We herein show that a recently developed unimolecular peptide triagonist is equally efficient in both sexes, suggesting that this polypharmaceutical strategy might be a relevant alternative to bariatric surgery for the treatment of obesity and related metabolic disorders. Unimolecular GLP-1/GIP/glucagon triagonist normalizes body weight in obese female mice. Triagonist treatment ameliorates steatohepatitis more potently in female mice. GLP-1/GIP/glucagon triagonist potentially as effective as bariatric surgery for men and women.
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