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Pena-Leon V, Perez-Lois R, Villalon M, Prida E, Muñoz-Moreno D, Fernø J, Quiñones M, Al-Massadi O, Seoane LM. Novel mechanisms involved in leptin sensitization in obesity. Biochem Pharmacol 2024; 223:116129. [PMID: 38490517 DOI: 10.1016/j.bcp.2024.116129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/21/2024] [Accepted: 03/12/2024] [Indexed: 03/17/2024]
Abstract
Leptin is a hormone that is secreted by adipocytes in proportion to adipose tissue size, and that informs the brain about the energy status of the body. Leptin acts through its receptor LepRb, expressed mainly in the hypothalamus, and induces a negative energy balance by potent inhibition of feeding and activation of energy expenditure. These actions have led to huge expectations for the development of therapeutic targets for metabolic complications based on leptin-derived compounds. However, the majority of patients with obesity presents elevated leptin production, suggesting that in this setting leptin is ineffective in the regulation of energy balance. This resistance to the action of leptin in obesity has led to the development of "leptin sensitizers," which have been tested in preclinical studies. Much research has focused on generating combined treatments that act on multiple levels of the gastrointestinal-brain axis. The gastrointestinal-brain axis secretes a variety of different anorexigenic signals, such as uroguanylin, glucagon-like peptide-1, amylin, or cholecystokinin, which can alleviate the resistance to leptin action. Moreover, alternative mechanism such as pharmacokinetics, proteostasis, the role of specific kinases, chaperones, ER stress and neonatal feeding modifications are also implicated in leptin resistance. This review will cover the current knowledge regarding the interaction of leptin with different endocrine factors from the gastrointestinal-brain axis and other novel mechanisms that improve leptin sensitivity in obesity.
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Affiliation(s)
- Veronica Pena-Leon
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Raquel Perez-Lois
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Maria Villalon
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Eva Prida
- Translational Endocrinology group, Endocrinology Section, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (IDIS/CHUS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Diego Muñoz-Moreno
- Translational Endocrinology group, Endocrinology Section, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (IDIS/CHUS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Johan Fernø
- Hormone Laboratory, Department of Biochemistry and Pharmacology, Haukeland University Hospital, 5201 Bergen, Norway
| | - Mar Quiñones
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; CIBER de Fisiopatología de la Obesidad y la Nutrición, Instituto de Salud Carlos III, Madrid, Spain
| | - Omar Al-Massadi
- Translational Endocrinology group, Endocrinology Section, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (IDIS/CHUS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; CIBER de Fisiopatología de la Obesidad y la Nutrición, Instituto de Salud Carlos III, Madrid, Spain.
| | - Luisa M Seoane
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; CIBER de Fisiopatología de la Obesidad y la Nutrición, Instituto de Salud Carlos III, Madrid, Spain.
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Leyderman M, Wilmore JR, Shope T, Cooney RN, Urao N. Impact of intestinal microenvironments in obesity and bariatric surgery on shaping macrophages. IMMUNOMETABOLISM (COBHAM, SURREY) 2023; 5:e00033. [PMID: 38037591 PMCID: PMC10683977 DOI: 10.1097/in9.0000000000000033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 10/26/2023] [Indexed: 12/02/2023]
Abstract
Obesity is associated with alterations in tissue composition, systemic cellular metabolism, and low-grade chronic inflammation. Macrophages are heterogenous innate immune cells ubiquitously localized throughout the body and are key components of tissue homeostasis, inflammation, wound healing, and various disease states. Macrophages are highly plastic and can switch their phenotypic polarization and change function in response to their local environments. Here, we discuss how obesity alters the intestinal microenvironment and potential key factors that can influence intestinal macrophages as well as macrophages in other organs, including adipose tissue and hematopoietic organs. As bariatric surgery can induce metabolic adaptation systemically, we discuss the potential mechanisms through which bariatric surgery reshapes macrophages in obesity.
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Affiliation(s)
- Michael Leyderman
- Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, NY, USA
| | - Joel R. Wilmore
- Department of Microbiology and Immunology, State University of New York Upstate Medical University, Syracuse, NY, USA
- Sepsis Interdisciplinary Research Center, State University of New York Upstate Medical University, Syracuse, NY, USA
| | - Timothy Shope
- Department of Surgery, State University of New York Upstate Medical University, Syracuse, NY, USA
| | - Robert N. Cooney
- Sepsis Interdisciplinary Research Center, State University of New York Upstate Medical University, Syracuse, NY, USA
- Department of Surgery, State University of New York Upstate Medical University, Syracuse, NY, USA
| | - Norifumi Urao
- Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, NY, USA
- Sepsis Interdisciplinary Research Center, State University of New York Upstate Medical University, Syracuse, NY, USA
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Harris RBS. Low-dose peripheral leptin infusion produces selective activation of ventromedial hypothalamic and hindbrain STAT3. Am J Physiol Endocrinol Metab 2023; 325:E72-E82. [PMID: 37285599 PMCID: PMC10292972 DOI: 10.1152/ajpendo.00083.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/03/2023] [Accepted: 06/05/2023] [Indexed: 06/09/2023]
Abstract
Previous studies have shown that very low dose, acute, single peripheral leptin injections fully activate arcuate nucleus signal transducer and activator of transcription 3 (STAT3), but ventromedial hypothalamus (VMH) pSTAT3 continues to increase with higher doses of leptin that inhibit food intake. The lowest dose that inhibited intake increased circulating leptin 300-fold whereas food intake is inhibited by chronic peripheral leptin infusions that only double circulating leptin. This study examined whether the pattern of hypothalamic pSTAT3 was the same in leptin-infused rats as in leptin-injected rats. Male Sprague-Dawley rats received intraperitoneal infusions of 0, 5, 10, 20, or 40 µg leptin/day for 9 days. The highest dose of leptin increased serum leptin by 50-100%, inhibited food intake for 5 days, but inhibited weight gain and retroperitoneal fat mass for 9 days. Energy expenditure, respiratory exchange ratio, and brown fat temperature did not change. pSTAT3 was quantified in hypothalamic nuclei and the nucleus of the solitary tract (NTS) when food intake was inhibited and when it had returned to control levels. There was no effect of leptin on pSTAT3 in the medial or lateral arcuate nucleus or in the dorsomedial nucleus of the hypothalamus. VMH pSTAT3 was increased only at day 4 when food intake was inhibited, but NTS pSTAT3 was increased at both 4 and 9 days of infusion. These results suggest that activation of leptin VMH receptors contributes to the suppression of food intake, but that hindbrain receptors contribute to a sustained change in metabolism that maintains a reduced weight and fat mass.NEW & NOTEWORTHY Low-dose, chronic peripheral infusions of leptin produced an initial, transient inhibition of food intake that correlated with signal transducer and activator of transcription 3 (STAT3) activation in the ventromedial hypothalamus (VMH) and nucleus of the solitary tract (NTS). When intake normalized, but weight remained suppressed, the NTS was the only area that remained activated. These data suggest that leptin's primary function is to reduce body fat, that hypophagia is a means of achieving this and that different areas of the brain are responsible for the progressive response.
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Affiliation(s)
- Ruth B S Harris
- Center for Neuroinflammation and Cardiometabolic Disease, Georgia State University, Atlanta, Georgia, United States
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Ahn W, Latremouille J, Harris RBS. Leptin receptor-expressing cells in the ventromedial nucleus of the hypothalamus contribute to enhanced CCK-induced satiety following central leptin injection. Am J Physiol Endocrinol Metab 2022; 323:E267-E280. [PMID: 35830689 PMCID: PMC9448279 DOI: 10.1152/ajpendo.00088.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 06/15/2022] [Accepted: 07/08/2022] [Indexed: 01/27/2023]
Abstract
Others have shown that leptin and cholecystokinin (CCK) act synergistically to suppress food intake. Experiments described here tested whether leptin in the ventromedial hypothalamus (VMH) contributes to the synergy with peripheral CCK in male Sprague Dawley rats. A subthreshold injection of 50-ng leptin into the VMH 1 h before a peripheral injection of 1 µg/kg CCK did not change the response to CCK in rats offered chow or low-fat purified diet, but did exaggerate the reduction in intake of high-fat diet 30 min and 1 h after injection in rats that had been food deprived for 8 h. By contrast, deletion of leptin receptor-expressing cells in the VMH using leptin-conjugated saporin (Lep-Sap) abolished the response to peripheral CCK in chow-fed rats. Lateral ventricle injection of 2-µg leptin combined with peripheral CCK exaggerated the inhibition of chow intake for up to 6 h in control rats treated with Blank-saporin, but not in Lep-Sap rats. Blank-Saporin rats offered low- or high-fat purified diet also demonstrated a dose-response inhibition of intake that reached significance with 1 µg/kg of CCK for both diets. CCK did not inhibit intake of Lep-Sap rats in either low- or high-fat-fed rats. Thus, although basal activation of VMH leptin receptors makes a significant contribution to the synergy with CCK, increased leptin activity in the VMH does not exaggerate the response to CCK in intact rats offered low-fat diets, but does enhance the response in those offered high-fat diet.NEW & NOTEWORTHY Leptin is a feedback signal in the control of energy balance, whereas cholecystokinin (CCK) is a short-term satiety signal that inhibits meal size. The two hormones synergize to promote satiety. We tested whether leptin receptors in the ventromedial nucleus of the hypothalamus (VMH) contribute to the synergy. The results suggest that there is a requirement for a baseline level of activation of leptin receptors in the VMH in order for CCK to promote satiety.
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Affiliation(s)
- WonMo Ahn
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - John Latremouille
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Ruth B S Harris
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia
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OUP accepted manuscript. Nutr Rev 2022; 80:1942-1957. [DOI: 10.1093/nutrit/nuac010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Harris RBS. Phosphorylation of STAT3 in hypothalamic nuclei is stimulated by lower doses of leptin than are needed to inhibit food intake. Am J Physiol Endocrinol Metab 2021; 321:E190-E201. [PMID: 34121448 PMCID: PMC8321824 DOI: 10.1152/ajpendo.00143.2021] [Citation(s) in RCA: 3] [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: 04/13/2021] [Revised: 06/03/2021] [Accepted: 06/07/2021] [Indexed: 01/08/2023]
Abstract
This experiment investigated which hypothalamic nuclei were activated by a dose of leptin that inhibited food intake. Foodnot intake, energy expenditure, respiratory exchange ratio (RER), and intrascapular brown adipose tissue (IBAT) temperature were measured in male and female Sprague Dawley rats for 36 h following an intraperitoneal injection of 0, 50, 200, 500, or 1,000 µg leptin/kg with each rat tested with each dose of leptin in random order. In both males and females, RER and 12-h food intake were inhibited only by 1,000 µg leptin/kg, but there was no effect on energy expenditure or IBAT temperature. At the end of the experiment, phosphorylated signal transducer and activator of transcription 3 (pSTAT3) immunoreactivity was measured 1 h after injection of 0, 50, 500, or 1,000 µg leptin/kg. In male rats, the lowest dose of leptin produced a maximal activation of STAT3 in the Arc and nucleus of the solitary tract (NTS). There was no response in the dorsomedial hypothalamus, but there was a progressive increase in ventromedial nucleus of the hypothalamus (VMH) pSTAT3 with increasing doses of leptin. In female rats, there was no significant change in Arc and pSTAT3 NTS activation was maximal with 500 mg leptin/kg, but only the highest dose of leptin increased VMH pSTAT3. These results suggest that the VMH plays an important role in the energetic response to elevations of circulating leptin but do not exclude the possibility that multiple nuclei provide the appropriate integrated response to hyperleptinemia.NEW & NOTEWORTHY The results of this experiment show that doses of leptin too small to inhibit food intake produce a maximal response to leptin in the arcuate nucleus. By contrast the VMH shows a robust response that correlates with inhibition of food intake. This suggests that the VMH plays an important role in the energetic response to hyperleptinemia.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia
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Dayarathne LA, Ranaweera SS, Natraj P, Rajan P, Lee YJ, Han CH. Restoration of the adipogenic gene expression by naringenin and naringin in 3T3-L1 adipocytes. J Vet Sci 2021; 22:e55. [PMID: 34313040 PMCID: PMC8318791 DOI: 10.4142/jvs.2021.22.e55] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/29/2021] [Accepted: 06/20/2021] [Indexed: 11/23/2022] Open
Abstract
Background Naringenin and its glycoside naringin are well known citrus flavonoids with several therapeutic benefits. Although the anti-adipogenic effects of naringenin and naringin have been reported previously, the detailed mechanism underlying their anti-adipogenesis effects is poorly understood. Objectives This study examined the anti-adipogenic effects of naringenin and naringin by determining differential gene expression patterns in these flavonoids-treated 3T3-L1 adipocytes. Methods Lipid accumulation and triglyceride (TG) content were determined by Oil red O staining and TG assay. Glucose uptake was measured using a 2-[N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-d-glucose fluorescent d-glucose analog. The phosphorylation levels of AMP-activated protein kinase (AMPK) and acetyl Co-A carboxylase (ACC) were observed via Western blot analysis. Differential gene expressions in 3T3-L1 adipocytes were evaluated via RNA sequencing analysis. Results Naringenin and naringin inhibited both lipid accumulation and TG content, increased phosphorylation levels of both AMPK and ACC and decreased the expression level of 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR) in 3T3-L1 adipocytes. RNA sequencing analysis revealed that 32 up-regulated (> 2-fold) and 17 down-regulated (< 0.6-fold) genes related to lipid metabolism, including Acaca, Fasn, Scd1, Mogat1, Dgat, Lipin1, Cpt1a, and Lepr, were normalized to the control level in naringenin-treated adipocytes. In addition, 25 up-regulated (> 2-fold) and 25 down-regulated (< 0.6-fold) genes related to lipid metabolism, including Acaca, Fasn, Fabp5, Scd1, Srebf1, Hmgcs1, Cpt1c, Lepr, and Lrp1, were normalized to the control level by naringin. Conclusions The results indicate that naringenin and naringin have anti-adipogenic potentials that are achieved by normalizing the expression levels of lipid metabolism-related genes that were perturbed in differentiated 3T3-L1 cells.
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Affiliation(s)
| | | | - Premkumar Natraj
- College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea
| | - Priyanka Rajan
- College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea
| | - Young Jae Lee
- College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea
| | - Chang Hoon Han
- College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea.
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8
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Harris RBS. Consuming sucrose solution promotes leptin resistance and site specifically modifies hypothalamic leptin signaling in rats. Am J Physiol Regul Integr Comp Physiol 2020; 320:R182-R194. [PMID: 33206557 DOI: 10.1152/ajpregu.00238.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rats consuming 30% sucrose solution and a sucrose-free diet (LiqS) become leptin resistant, whereas rats consuming sucrose from a formulated diet (HS) remain leptin responsive. This study tested whether leptin resistance in LiqS rats extended beyond a failure to inhibit food intake and examined leptin responsiveness in the hypothalamus and hindbrain of rats offered HS, LiqS, or a sucrose-free diet (NS). Female LiqS Sprague-Dawley rats initially only partially compensated for the calories consumed as sucrose, but energy intake matched that of HS and NS rats when they were transferred to calorimetry cages. There was no effect of diet on energy expenditure, intrascapular brown fat tissue (IBAT) temperature, or fat pad weight. A peripheral injection of 2 mg of leptin/kg on day 23 or day 26 inhibited energy intake of HS and NS but not LiqS rats. Inhibition occurred earlier in HS rats than in NS rats and was associated with a smaller meal size. Leptin had no effect on energy expenditure but caused a transient rise in IBAT temperature of HS rats. Leptin increased the phosphorylation of signal transducer and activator of transcription 3 (pSTAT3) in the hindbrain and ventromedial hypothalamus of all rats. There was a minimal effect of leptin in the arcuate nucleus, and only the dorsomedial hypothalamus showed a correlation between pSTAT3 and leptin responsiveness. These data suggest that the primary response to leptin is inhibition of food intake and the pattern of sucrose consumption, rather than calories consumed as sucrose, causes leptin resistance associated with site-specific differences in hypothalamic leptin signaling.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia
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Ewbank SN, Campos CA, Chen JY, Bowen AJ, Padilla SL, Dempsey JL, Cui JY, Palmiter RD. Chronic G q signaling in AgRP neurons does not cause obesity. Proc Natl Acad Sci U S A 2020; 117:20874-20880. [PMID: 32764144 PMCID: PMC7456117 DOI: 10.1073/pnas.2004941117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Maintaining energy homeostasis requires coordinating physiology and behavior both on an acute timescale to adapt to rapid fluctuations in caloric intake and on a chronic timescale to regulate body composition. Hypothalamic agouti-related peptide (AgRP)-expressing neurons are acutely activated by caloric need, and this acute activation promotes increased food intake and decreased energy expenditure. On a longer timescale, AgRP neurons exhibit chronic hyperactivity under conditions of obesity and high dietary fat consumption, likely due to leptin resistance; however, the behavioral and metabolic effects of chronic AgRP neuronal hyperactivity remain unexplored. Here, we use chemogenetics to manipulate Gq signaling in AgRP neurons in mice to explore the hypothesis that chronic activation of AgRP neurons promotes obesity. Inducing chronic Gq signaling in AgRP neurons initially increased food intake and caused dramatic weight gain, in agreement with published data; however, food intake returned to baseline levels within 1 wk, and body weight returned to baseline levels within 60 d. Additionally, we found that, when mice had elevated body weight due to chronic Gq signaling in AgRP neurons, energy expenditure was not altered but adiposity and lipid metabolism were both increased, even under caloric restriction. These findings reveal that the metabolic and behavioral effects of chronic Gq signaling in AgRP neurons are distinct from the previously reported effects of acute Gq signaling and also of leptin insensitivity.
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Affiliation(s)
- Sedona N Ewbank
- Department of Biochemistry, University of Washington, Seattle, WA 98195;
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195
| | - Carlos A Campos
- Department of Biochemistry, University of Washington, Seattle, WA 98195;
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195
| | - Jane Y Chen
- Department of Biochemistry, University of Washington, Seattle, WA 98195
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195
| | - Anna J Bowen
- Department of Biochemistry, University of Washington, Seattle, WA 98195
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195
| | - Stephanie L Padilla
- Department of Biochemistry, University of Washington, Seattle, WA 98195
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195
| | - Joseph L Dempsey
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195
| | - Julia Yue Cui
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195
| | - Richard D Palmiter
- Department of Biochemistry, University of Washington, Seattle, WA 98195;
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195
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Seoane-Collazo P, Martínez-Sánchez N, Milbank E, Contreras C. Incendiary Leptin. Nutrients 2020; 12:nu12020472. [PMID: 32069871 PMCID: PMC7071158 DOI: 10.3390/nu12020472] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/06/2020] [Accepted: 02/08/2020] [Indexed: 02/08/2023] Open
Abstract
Leptin is a hormone released by adipose tissue that plays a key role in the control of energy homeostasis through its binding to leptin receptors (LepR), mainly expressed in the hypothalamus. Most scientific evidence points to leptin’s satiating effect being due to its dual capacity to promote the expression of anorexigenic neuropeptides and to reduce orexigenic expression in the hypothalamus. However, it has also been demonstrated that leptin can stimulate (i) thermogenesis in brown adipose tissue (BAT) and (ii) the browning of white adipose tissue (WAT). Since the demonstration of the importance of BAT in humans 10 years ago, its study has aroused great interest, mainly in the improvement of obesity-associated metabolic disorders through the induction of thermogenesis. Consequently, several strategies targeting BAT activation (mainly in rodent models) have demonstrated great potential to improve hyperlipidemias, hepatic steatosis, insulin resistance and weight gain, leading to an overall healthier metabolic profile. Here, we review the potential therapeutic ability of leptin to correct obesity and other metabolic disorders, not only through its satiating effect, but by also utilizing its thermogenic properties.
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Affiliation(s)
- Patricia Seoane-Collazo
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
- CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain;
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
- Correspondence: (P.S.-C.); (N.M.-S.); (C.C.); Tel.: +81-298-533-301 (P.S.-C.); +34-913-941-650 (N.M.-S.); +44-01865285890 (C.C.)
| | - Noelia Martínez-Sánchez
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
- Correspondence: (P.S.-C.); (N.M.-S.); (C.C.); Tel.: +81-298-533-301 (P.S.-C.); +34-913-941-650 (N.M.-S.); +44-01865285890 (C.C.)
| | - Edward Milbank
- CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain;
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Cristina Contreras
- Department of Physiology, Pharmacy School, Complutense University of Madrid, 28040 Madrid, Spain
- Correspondence: (P.S.-C.); (N.M.-S.); (C.C.); Tel.: +81-298-533-301 (P.S.-C.); +34-913-941-650 (N.M.-S.); +44-01865285890 (C.C.)
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Seamon M, Ahn W, Li AJ, Ritter S, Harris RBS. Leptin receptor-expressing neurons in ventromedial nucleus of the hypothalamus contribute to weight loss caused by fourth ventricle leptin infusions. Am J Physiol Endocrinol Metab 2019; 317:E586-E596. [PMID: 31361549 PMCID: PMC6842917 DOI: 10.1152/ajpendo.00205.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/11/2019] [Accepted: 07/22/2019] [Indexed: 12/24/2022]
Abstract
Leptin administration into the hindbrain, and specifically the nucleus of the solitary tract, increases phosphorylated signal transducer and activator of transcription 3 (pSTAT3), a marker of leptin receptor activation, in hypothalamic nuclei known to express leptin receptors. The ventromedial nucleus of the hypothalamus (VMH) shows the greatest response, with a threefold increase in pSTAT3. This experiment tested the importance of VMH leptin receptor-expressing neurons in mediating weight loss caused by fourth ventricle (4V) leptin infusion. Male Sprague-Dawley rats received bilateral VMH 75-nL injections of 260 ng/μL of leptin-conjugated saporin (Lep-Sap) or blank-saporin (Blk-Sap). After 23 days they were fitted with 4V infusion cannulas and 1 wk later adapted to housing in a calorimeter before they were infused with 0.9 μg leptin/day for 14 days. There was no effect of VMH Lep-Sap on weight gain or glucose clearance before leptin infusion. Leptin inhibited food intake and respiratory exchange ratio in Blk-Sap but not Lep-Sap rats. Leptin had no effect on energy expenditure or brown adipose tissue temperature of either group. Inguinal and epididymal fat were significantly reduced in leptin-treated Blk-Sap rats, but the response was greatly attenuated in Lep-Sap rats. VMH pSTAT3 was increased in leptin-treated Blk-Sap but not Lep-Sap rats. These results support the concept that leptin-induced weight loss results from an integrated response across different brain areas. They also support previous reports that VMH leptin receptors do not play a significant role in maintaining energy balance in basal conditions but limit weight gain during positive energy balance.
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Affiliation(s)
- Marissa Seamon
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia
| | - WonMo Ahn
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia
| | - Ai-Jun Li
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, Washington
| | - Sue Ritter
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, Washington
| | - Ruth B S Harris
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia
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Leon Mercado L, Caron A, Wang Y, Burton M, Gautron L. Identification of Leptin Receptor-Expressing Cells in the Nodose Ganglion of Male Mice. Endocrinology 2019; 160:1307-1322. [PMID: 30907928 PMCID: PMC6482037 DOI: 10.1210/en.2019-00021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/18/2019] [Indexed: 12/29/2022]
Abstract
Leptin has been proposed to modulate viscerosensory information directly at the level of vagal afferents. In support of this view, broad expression for the leptin receptor (Lepr) has previously been reported in vagal afferents. However, the exact identity and distribution of leptin-sensitive vagal afferents has not been elucidated. Using quantitative PCR, we found that the whole mouse nodose ganglion was predominantly enriched in the short form of Lepr, rather than its long form. Consistent with this observation, the acute administration of leptin did not stimulate JAK-STAT signaling in the nodose ganglion. Using chromogenic in situ hybridization in wild-type mice and several reporter mouse models, we demonstrated that Lepr mRNA was restricted to nonneuronal cells in the epineurium and parenchyma of the nodose ganglion and a subset of vagal afferents, which accounted for only 3% of all neuronal profiles. Double labeling studies further established that Lepr-expressing vagal afferents were Nav1.8-negative fibers that did not supply the peritoneal cavity. Finally, double chromogenic in situ hybridization revealed that many Lepr-expressing neurons coexpressed the angiotensin 1a receptor (At1ar), which is a gene expressed in baroreceptors. Taken together, our data challenge the commonly held view that Lepr is broadly expressed in vagal afferents. Instead, our data suggest that leptin may exert a previously unrecognized role, mainly via its short form, as a direct modulator of a very small group of At1ar-positive vagal fibers.
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Affiliation(s)
- Luis Leon Mercado
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Alexandre Caron
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Yibing Wang
- Department of Biochemistry, Utah Southwestern Medical Center at Dallas, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Michael Burton
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas
| | - Laurent Gautron
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Correspondence: Laurent Gautron, PhD, Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390. E-mail:
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Xu JQ, Xu XM, Bi ZQ, Shi LL, Cao J, Zhao ZJ. The less weight loss due to modest food restriction drove more fat accumulation in striped hamsters refed with high-fat diet. Horm Behav 2019; 110:19-28. [PMID: 30790562 DOI: 10.1016/j.yhbeh.2019.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 02/07/2019] [Accepted: 02/13/2019] [Indexed: 12/11/2022]
Abstract
Food restriction (FR) has been commonly used to decrease body fat, reducing the risk of overweight in humans and animals. However, the lost weight has been shown to be followed by overweight when food restriction ends. It remains uncertain whether the weight loss drives the overweight, or not. In the present study, striped hamsters were restricted by 15%, 30% and 40% of ad libitum food intake for 2 weeks, followed by high-fat refeeding for 6 weeks (FR15%-Re, FR30%-Re and FR40%-Re). The hamsters in FR15%, FR30% and FR40% groups decreased by 21.1%, 37.8% and 50.0% in fat mass (P < 0.01), and 16.8%, 42.8% and 53.4% in leptin levels (P < 0.01) compared with the hamsters fed ad libitum. The FR15%-Re, FR30%-Re and FR40%-Re groups showed 77.0%, 37.2% and 23.7% more body fat than ad libitum group (P < 0.01). The FR15%-Re group showed considerable decreases in gene expression of arcuate nucleus co-expressing proopiomelanocortin (POMC), cocaine - and amphetamineregulated transcript (CART) and the long isoform of leptin receptor (LepRb) in the hypothalamus and of several genes associated with fatty acid transport to mitochondria and β-oxidation in brown adipose tissue and liver. It suggests that less weight loss is likely to drive more fat accumulation when food restriction ends, in which the impaired function of LepRb, POMC and CART in the brain and fatty acid oxidation in brown adipose tissue and liver may be involved.
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Affiliation(s)
- Jia-Qi Xu
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Xiao-Ming Xu
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Zhong-Qiang Bi
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Lu-Lu Shi
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Jing Cao
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Zhi-Jun Zhao
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China.
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Borges BC, Han X, Allen SJ, Garcia-Galiano D, Elias CF. Insulin signaling in LepR cells modulates fat and glucose homeostasis independent of leptin. Am J Physiol Endocrinol Metab 2019; 316:E121-E134. [PMID: 30376348 PMCID: PMC6417687 DOI: 10.1152/ajpendo.00287.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypothalamic neurons detect changes in circulating hormones such as leptin and insulin and put forward outputs to sustain energy and glucose homeostasis. Because leptin and insulin receptors colocalize in ~40-60% of neurons in the hypothalamus, we characterized the metabolic phenotype of mice with selective deletion of the insulin receptor (InsR) in LepR cells. LRΔInsR mice presented no difference in body weight and insulin levels but increased fat mass. In the light phase, LRΔInsR mice exhibited increased food intake, locomotor activity, carbon dioxide production, and respiratory exchange rate. These mice showed reduced fat oxidation and reduced expression of cluster of differentiation 36 and AMP-activated protein kinase-α1 in the liver, increased glucose oxidation in the light phase, and overall reduced basal glucose levels. To verify the impact of InsR deletion in LepR cells in obesity, we generated ob/ ob InsRfl, ob/ ob LRcre, and ob/ ob LRΔInsR mice. The ob/ ob LRΔInsR mice had higher body weight, fat mass, and expression of genes related to fat metabolism in the liver. No difference in food intake despite increased neuropeptide Y and agouti-related peptide expression, and no difference in energy expenditure, fat, or glucose oxidation was found in ob/ ob LRΔInsR compared with LRcre or LRΔInsR controls. Remarkably, basal glucose levels were reduced, and the expression of genes associated with glucose metabolism in the liver was higher. Insulin signaling in LepR cells is required for the proper fat and glucose oxidation. These effects are independent of leptin given that the leptin-deficient ob/ ob LRΔInsR mice also presented reduced glycemia and higher adiposity. The mechanisms underlying these responses remain to be unveiled.
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Affiliation(s)
- Beatriz C Borges
- Department of Molecular and Integrative Physiology, University of Michigan , Ann Arbor, Michigan
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo , Brazil
| | - Xingfa Han
- Department of Molecular and Integrative Physiology, University of Michigan , Ann Arbor, Michigan
- Isotope Research Laboratory, Sichuan Agricultural University, Ya'an, People's Republic of China
| | - Susan J Allen
- Department of Molecular and Integrative Physiology, University of Michigan , Ann Arbor, Michigan
| | - David Garcia-Galiano
- Department of Molecular and Integrative Physiology, University of Michigan , Ann Arbor, Michigan
| | - Carol F Elias
- Department of Molecular and Integrative Physiology, University of Michigan , Ann Arbor, Michigan
- Department of Obstetrics and Gynecology, University of Michigan , Ann Arbor, Michigan
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15
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Is leptin resistance the cause or the consequence of diet-induced obesity? Int J Obes (Lond) 2018; 42:1445-1457. [PMID: 29789721 DOI: 10.1038/s41366-018-0111-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 03/13/2018] [Accepted: 04/10/2018] [Indexed: 12/24/2022]
Abstract
BACKGROUND/OBJECTIVES Obesity is strongly associated with leptin resistance. It is unclear whether leptin resistance results from the (over)consumption of energy-dense diets or if reduced leptin sensitivity is also a pre-existing factor in rodent models of diet-induced obesity (DIO). We here tested whether leptin sensitivity on a chow diet predicts subsequent weight gain and leptin sensitivity on a free choice high-fat high-sucrose (fcHFHS) diet. METHODS Based upon individual leptin sensitivity on chow diet, rats were grouped in leptin sensitive (LS, n = 22) and leptin resistant (LR, n = 19) rats (P = 0.000), and the development of DIO on a fcHFHS diet was compared. The time-course of leptin sensitivity was measured over weeks in individual rats. RESULTS Both on a chow and a fcHFHS diet, high variability in leptin sensitivity was observed between rats, but not over time per individual rat. Exposure to the fcHFHS diet revealed that LR rats were more prone to develop DIO (P = 0.013), which was independent of caloric intake (p ≥ 0.320) and the development of diet-induced leptin resistance (P = 0.769). Reduced leptin sensitivity in LR compared with LS rats before fcHFHS diet exposure, was associated with reduced leptin-induced phosphorylated signal transducer and activator of transcription 3 (pSTAT3) levels in the dorsomedial and ventromedial hypothalamus (P ≤ 0.049), but not the arcuate nucleus (P = 0.558). CONCLUSIONS A pre-existing reduction in leptin sensitivity determines the susceptibility to develop excessive DIO after fcHFHS diet exposure. Rats with a pre-existing reduction in leptin sensitivity develop excessive DIO without eating more calories or altering their leptin sensitivity.
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16
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Siu JJ, Queen NJ, Liu X, Huang W, McMurphy T, Cao L. Molecular Therapy of Melanocortin-4-Receptor Obesity by an Autoregulatory BDNF Vector. Mol Ther Methods Clin Dev 2017; 7:83-95. [PMID: 29296625 PMCID: PMC5744069 DOI: 10.1016/j.omtm.2017.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 09/26/2017] [Indexed: 12/27/2022]
Abstract
Mutations in the melanocortin-4-receptor (MC4R) comprise the most common monogenic form of severe early-onset obesity, and conventional treatments are either ineffective long-term or contraindicated. Immediately downstream of MC4R-in the pathway for regulating energy balance-is brain-derived neurotrophic factor (BDNF). Our previous studies show that adeno-associated virus (AAV)-mediated hypothalamic BDNF gene transfer alleviates obesity and diabetes in both diet-induced and genetic models. To facilitate clinical translation, we developed a built-in autoregulatory system to control therapeutic gene expression mimicking the body's natural feedback systems. This autoregulatory approach leads to a sustainable plateau of body weight after substantial weight loss is achieved. Here, we examined the efficacy and safety of autoregulatory BDNF gene therapy in Mc4r heterozygous mice, which best resemble MC4R obese patients. Mc4r heterozygous mice were treated with either autoregulatory BDNF vector or YFP control and monitored for 30 weeks. BDNF gene therapy prevented the development of obesity and metabolic syndromes characterized by decreasing body weight and adiposity, suppressing food intake, alleviating hyperleptinemia and hyperinsulinemia, improving glucose and insulin tolerance, and increasing energy expenditure, without adverse cardiovascular function or behavioral disturbances. These safety and efficacy data provide preclinical evidence that BDNF gene therapy is a compelling treatment option for MC4R-deficient obese patients.
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Affiliation(s)
- Jason J. Siu
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
- Neuroscience Graduate Program, The Ohio State University, Columbus, OH 43210, USA
- Medical Scientist Training Program, The Ohio State University, Columbus, OH 43210, USA
| | - Nicholas J. Queen
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Xianglan Liu
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Wei Huang
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Travis McMurphy
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
| | - Lei Cao
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
- Neuroscience Graduate Program, The Ohio State University, Columbus, OH 43210, USA
- Medical Scientist Training Program, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
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17
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Evans MC, Anderson GM. Dopamine Neuron-Restricted Leptin Receptor Signaling Reduces Some Aspects of Food Reward but Exacerbates the Obesity of Leptin Receptor-Deficient Male Mice. Endocrinology 2017; 158:4246-4256. [PMID: 28938472 DOI: 10.1210/en.2017-00513] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/15/2017] [Indexed: 01/29/2023]
Abstract
The contribution of leptin-induced modulation of dopamine neurons to feeding behavior and energy homeostasis remains unclear. Midbrain dopamine neurons regulate the reward value of food, and direct leptin administration to the midbrain reduces food intake. However, selective deletion of leptin receptors (Leprs) from dopamine neurons has no effect on body weight, food intake, or hedonic responses, suggesting that leptin acts indirectly or demonstrating that sufficient compensation occurs to mask any direct leptin-dopamine effects. To further explore the role of direct Lepr-dopamine neuron signaling in the control of feeding behavior and energy homeostasis, we generated mice in which Leprs were expressed exclusively in dopamine transporter (DAT)-expressing neurons (LeprDAT). We then assessed weekly body weight, daily food intake, hyperphagic feeding, and leptin-induced suppression of feeding in the LeprDAT mice compared with their Lepr-deficient (LeprNULL) and wild-type control (LeprCON) littermates. We also used metabolic cages to characterize running wheel activity, home-cage activity, and total energy expenditure. As expected, LeprNULL mice exhibited increased body weight and food intake compared with LeprCON mice. LeprDAT male mice exhibited acute leptin-induced suppression of food intake and reduced hedonic feeding but also exhibited significantly increased postweaning body weight gain compared with the LeprNULL mice. This was associated with significantly reduced home-cage activity counts, although no differences in food intake were observed between the LeprDAT and LeprNULL mice. These data demonstrate that restoring Lepr signaling exclusively in dopamine neurons reduces some aspects of food reward and activity but does not ameliorate the obesity phenotype of Lepr-deficient mice.
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Affiliation(s)
- Maggie C Evans
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago School of Biomedical Sciences, New Zealand
| | - Greg M Anderson
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago School of Biomedical Sciences, New Zealand
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18
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19
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Bolze F, Mocek S, Zimmermann A, Klingenspor M. Aminoglycosides, but not PTC124 (Ataluren), rescue nonsense mutations in the leptin receptor and in luciferase reporter genes. Sci Rep 2017; 7:1020. [PMID: 28432296 PMCID: PMC5430635 DOI: 10.1038/s41598-017-01093-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/23/2017] [Indexed: 11/09/2022] Open
Abstract
In rare cases, monogenetic obesity is caused by nonsense mutations in genes regulating energy balance. A key factor herein is the leptin receptor. Here, we focus on leptin receptor nonsense variants causing obesity, namely the human W31X, murine Y333X and rat Y763X mutations, and explored their susceptibilities to aminoglycoside and PTC124 mediated translational read-through in vitro. In a luciferase based assay, all mutations - when analysed within the mouse receptor - were prone to aminoglycoside mediated nonsense suppression with the highest susceptibility for W31X, followed by Y763X and Y333X. For the latter, the corresponding rodent models appear valuable for in vivo experiments. When W31X was studied in the human receptor, its superior read-through susceptibility – initially observed in the mouse receptor – was eliminated, likely due to the different nucleotide context surrounding the mutation in the two orthologues. The impact of the surrounding context on the read-through opens the possibility to discover novel sequence elements influencing nonsense suppression. As an alternative to toxic aminoglycosides, PTC124 was indicated as a superior nonsense suppressor but inconsistent data concerning its read-through activity are reported. PTC124 failed to rescue W31X as well as different nonsense mutated luciferase reporters, thus, challenging its ability to induce translational read-through.
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Affiliation(s)
- Florian Bolze
- ZIEL - Institute for Food and Health, Technical University of Munich, Gregor-Mendel-Str. 2, 85354, Freising, Germany.,Chair of Molecular Nutritional Medicine, Technical University of Munich, EKFZ - Else Kröner-Fresenius-Center for Nutritional Medicine, Gregor-Mendel-Str. 2, 85354, Freising, Germany
| | - Sabine Mocek
- ZIEL - Institute for Food and Health, Technical University of Munich, Gregor-Mendel-Str. 2, 85354, Freising, Germany.,Chair of Molecular Nutritional Medicine, Technical University of Munich, EKFZ - Else Kröner-Fresenius-Center for Nutritional Medicine, Gregor-Mendel-Str. 2, 85354, Freising, Germany
| | - Anika Zimmermann
- ZIEL - Institute for Food and Health, Technical University of Munich, Gregor-Mendel-Str. 2, 85354, Freising, Germany.,Chair of Molecular Nutritional Medicine, Technical University of Munich, EKFZ - Else Kröner-Fresenius-Center for Nutritional Medicine, Gregor-Mendel-Str. 2, 85354, Freising, Germany
| | - Martin Klingenspor
- ZIEL - Institute for Food and Health, Technical University of Munich, Gregor-Mendel-Str. 2, 85354, Freising, Germany. .,Chair of Molecular Nutritional Medicine, Technical University of Munich, EKFZ - Else Kröner-Fresenius-Center for Nutritional Medicine, Gregor-Mendel-Str. 2, 85354, Freising, Germany.
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20
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Harris RBS, Desai BN. Fourth-ventricle leptin infusions dose-dependently activate hypothalamic signal transducer and activator of transcription 3. Am J Physiol Endocrinol Metab 2016; 311:E939-E948. [PMID: 27802966 PMCID: PMC5183885 DOI: 10.1152/ajpendo.00343.2016] [Citation(s) in RCA: 8] [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: 09/19/2016] [Revised: 10/18/2016] [Accepted: 10/25/2016] [Indexed: 12/16/2022]
Abstract
Previous studies have shown that very low-dose infusions of leptin into the third or the fourth ventricle alone have little effect on energy balance, but simultaneous low-dose infusions cause rapid weight loss and increased phosphorylation of STAT3 (p-STAT3) in hypothalamic sites that express leptin receptors. Other studies show that injecting high doses of leptin into the fourth ventricle inhibits food intake and weight gain. Therefore, we tested whether fourth-ventricle leptin infusions that cause weight loss are associated with increased leptin signaling in the hypothalamus. In a dose response study 14-day infusions of increasing doses of leptin showed significant hypophagia, weight loss, and increased hypothalamic p-STAT3 in rats receiving at least 0.9 μg leptin/day. In a second study 0.6 μg leptin/day transiently inhibited food intake and reduced carcass fat, but had no significant effect on energy expenditure. In a final study, we identified the localization of STAT3 activation in the hypothalamus of rats receiving 0, 0.3, or 1.2 μg leptin/day. The high dose of leptin, which caused weight loss in the first experiment, increased p-STAT3 in the ventromedial, dorsomedial, and arcuate nuclei of the hypothalamus. The low dose that increased brown fat UCP1 but did not affect body composition in the first experiment had little effect on hypothalamic p-STAT3. We propose that hindbrain leptin increases the precision of control of energy balance by lowering the threshold for leptin signaling in the forebrain. Further studies are needed to directly test this hypothesis.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Bhavna N Desai
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia
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21
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Ladyman SR, Grattan DR. Central Effects of Leptin on Glucose Homeostasis are Modified during Pregnancy in the Rat. J Neuroendocrinol 2016; 28. [PMID: 27623562 DOI: 10.1111/jne.12431] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 08/03/2016] [Accepted: 09/10/2016] [Indexed: 01/03/2023]
Abstract
Despite increased leptin concentrations during pregnancy, fat mass and food intake are increased. The satiety response to central leptin is suppressed, indicating a state of leptin insensitivity in the hypothalamus. Although the regulation of food intake is a major function of leptin, this hormone also influences a wide range of functions within the body. These actions include the regulation of glucose homeostasis, which undergoes major adaptation in the maternal body to generate optimal conditions for foetal development and growth. The present study aimed to investigate the effects of central leptin treatment on glucose homeostasis in pregnant rats to determine whether pregnancy-induced leptin insensitivity is functionally specific, and to further investigate changes in glucose homeostasis during pregnancy. After an overnight fast, nonpregnant and day 14 pregnant rats received an i.c.v. injection of leptin (100 ng or 4 μg) or vehicle then underwent a glucose tolerance test (GTT). Further groups of nonpregnant and day 14 pregnant rats were killed 30 min after leptin (doses ranging from 40 ng-4 μg) or vehicle i.c.v. injections for western blot analysis of phospho-signal transducer and activator of transcription 3 (STAT3) and phospho-Akt in various hypothalamic nuclei. Central leptin injection prior to a GTT lead to lowered basal insulin concentrations and impaired glucose tolerance in nonpregnant female rats, whereas the same doses of leptin had no significant effect on glucose tolerance in day 14 pregnant rats, indicating that, similar to the satiety actions of leptin, the effects of leptin on glucose homeostasis are suppressed during pregnancy. Furthermore, in the arcuate nucleus and ventromedial and dorsomedial nuclei of the hypothalamus, comprising three leptin-sensitive areas, there was no evidence that leptin induced Akt phosphorylation despite significant increases in phospho-STAT3, suggesting that leptin does not act through phospho-Akt in these areas in female rats.
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Affiliation(s)
- S R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago, Dunedin, New Zealand.
| | - D R Grattan
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago, Dunedin, New Zealand
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22
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Rosario W, Singh I, Wautlet A, Patterson C, Flak J, Becker TC, Ali A, Tamarina N, Philipson LH, Enquist LW, Myers MG, Rhodes CJ. The Brain-to-Pancreatic Islet Neuronal Map Reveals Differential Glucose Regulation From Distinct Hypothalamic Regions. Diabetes 2016; 65:2711-23. [PMID: 27207534 PMCID: PMC5001176 DOI: 10.2337/db15-0629] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 04/06/2016] [Indexed: 12/24/2022]
Abstract
The brain influences glucose homeostasis, partly by supplemental control over insulin and glucagon secretion. Without this central regulation, diabetes and its complications can ensue. Yet, the neuronal network linking to pancreatic islets has never been fully mapped. Here, we refine this map using pseudorabies virus (PRV) retrograde tracing, indicating that the pancreatic islets are innervated by efferent circuits that emanate from the hypothalamus. We found that the hypothalamic arcuate nucleus (ARC), ventromedial nucleus (VMN), and lateral hypothalamic area (LHA) significantly overlap PRV and the physiological glucose-sensing enzyme glucokinase. Then, experimentally lowering glucose sensing, specifically in the ARC, resulted in glucose intolerance due to deficient insulin secretion and no significant effect in the VMN, but in the LHA it resulted in a lowering of the glucose threshold that improved glucose tolerance and/or improved insulin sensitivity, with an exaggerated counter-regulatory response for glucagon secretion. No significant effect on insulin sensitivity or metabolic homeostasis was noted. Thus, these data reveal novel direct neuronal effects on pancreatic islets and also render a functional validation of the brain-to-islet neuronal map. They also demonstrate that distinct regions of the hypothalamus differentially control insulin and glucagon secretion, potentially in partnership to help maintain glucose homeostasis and guard against hypoglycemia.
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Affiliation(s)
- Wilfredo Rosario
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, IL
| | - Inderroop Singh
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, IL
| | - Arnaud Wautlet
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, IL
| | - Christa Patterson
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
| | - Jonathan Flak
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
| | - Thomas C Becker
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, NC
| | - Almas Ali
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, IL
| | - Natalia Tamarina
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, IL
| | - Louis H Philipson
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, IL
| | - Lynn W Enquist
- Department of Molecular Biology, Princeton University, Princeton, NJ
| | - Martin G Myers
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
| | - Christopher J Rhodes
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, IL
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23
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Denroche HC, Glavas MM, Tudurí E, Karunakaran S, Quong WL, Philippe M, Britton HM, Clee SM, Kieffer TJ. Disrupted Leptin Signaling in the Lateral Hypothalamus and Ventral Premammillary Nucleus Alters Insulin and Glucagon Secretion and Protects Against Diet-Induced Obesity. Endocrinology 2016; 157:2671-85. [PMID: 27183315 DOI: 10.1210/en.2015-1998] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leptin signaling in the central nervous system, and particularly the arcuate hypothalamic nucleus, is important for regulating energy and glucose homeostasis. However, the roles of extra-arcuate leptin responsive neurons are less defined. In the current study, we generated mice with widespread inactivation of the long leptin receptor isoform in the central nervous system via Synapsin promoter-driven Cre (Lepr(flox/flox) Syn-cre mice). Within the hypothalamus, leptin signaling was disrupted in the lateral hypothalamic area (LHA) and ventral premammillary nucleus (PMV) but remained intact in the arcuate hypothalamic nucleus and ventromedial hypothalamic nucleus, dorsomedial hypothalamic nucleus, and nucleus of the tractus solitarius. To investigate the role of LHA/PMV neuronal leptin signaling, we examined glucose and energy homeostasis in Lepr(flox/flox) Syn-cre mice and Lepr(flox/flox) littermates under basal and diet-induced obese conditions and tested the role of LHA/PMV neurons in leptin-mediated glucose lowering in streptozotocin-induced diabetes. Lepr(flox/flox) Syn-cre mice did not have altered body weight or blood glucose levels but were hyperinsulinemic and had enhanced glucagon secretion in response to experimental hypoglycemia. Surprisingly, when placed on a high-fat diet, Lepr(flox/flox) Syn-cre mice were protected from weight gain, glucose intolerance, and diet-induced hyperinsulinemia. Peripheral leptin administration lowered blood glucose in streptozotocin-induced diabetic Lepr(flox/flox) Syn-cre mice as effectively as in Lepr(flox/flox) littermate controls. Collectively these findings suggest that leptin signaling in LHA/PMV neurons is not critical for regulating glucose levels but has an indispensable role in the regulation of insulin and glucagon levels and, may promote the development of diet-induced hyperinsulinemia and weight gain.
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Affiliation(s)
- Heather C Denroche
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Maria M Glavas
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Eva Tudurí
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Subashini Karunakaran
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Whitney L Quong
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Marion Philippe
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Heidi M Britton
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Susanne M Clee
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
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Gong N, Jönsson E, Björnsson BT. Acute anorexigenic action of leptin in rainbow trout is mediated by the hypothalamic Pi3k pathway. J Mol Endocrinol 2016; 56:227-38. [PMID: 26667900 DOI: 10.1530/jme-15-0279] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 12/14/2015] [Indexed: 12/27/2022]
Abstract
Leptin (Lep) is an anorexigenic hormone and regulates appetite-related neuropeptides in mammals. A number of neuropeptides have also been linked to appetite regulation in teleost fish, but Lep signaling activation and effects on appetite-regulating neurons are poorly elucidated in early vertebrates. This study uses cellular, tissue and organismal approaches to elucidate the acute, central Lep action in rainbow trout. The results demonstrate that Lep activates phosphorylation of protein kinase B (Akt) and signal transducer and activator of transcription 3 in rainbow trout hypothalamus-derived cells, and that the phosphatidylinositol-3-kinase (Pi3k) inhibitor LY294002 can suppress the Lep-induced Akt phosphorylation. Intracerebroventricular (ICV) Lep administration strongly suppresses food intake at the doses of 0.05 and 0.5 µg Lep fish(-1) At low dose, Lep stimulates hypothalamic transcription of anorexigenic cocaine- and amphetamine-regulated transcript (Cart) and orexigenic neuropeptide Y. At high dose, Lep stimulates hypothalamic transcription of anorexigenic proopiomelanocortin (Pomc) A1, A2, and B, while coinjection with LY294002 reverses this upregulation. The data suggest that the anorexigenic action of Lep in rainbow trout is mediated through stimulation of the anorexigenic neuropeptides Pomc and Cart. Furthermore, ICV Lep treatment increases phosphor-Akt-immunoreactive cells in the nucleus lateralis tuberis, periventricular zone along infundibulum, and lateral recess surrounded by nucleus anterior tuberis, while LY294002 inhibits this effect. Lep receptor-immunoreactive cells are also predominant in these regions. These results demonstrate that Lep activates the Pi3k-Akt pathway in the lateral tuberal hypothalamus of rainbow trout for acute appetite regulation, indicating the conservation of anorexigenic Lep action in the mediobasal hypothalamus.
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Affiliation(s)
- Ningping Gong
- Fish Endocrinology LaboratoryDepartment of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Elisabeth Jönsson
- Fish Endocrinology LaboratoryDepartment of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Björn Thrandur Björnsson
- Fish Endocrinology LaboratoryDepartment of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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25
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Yang L, McKnight GS. Hypothalamic PKA regulates leptin sensitivity and adiposity. Nat Commun 2015; 6:8237. [PMID: 26381935 PMCID: PMC4576457 DOI: 10.1038/ncomms9237] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/30/2015] [Indexed: 12/17/2022] Open
Abstract
Mice lacking the RIIβ regulatory subunit of cyclic AMP-dependent protein kinase A (PKA) display reduced adiposity and resistance to diet-induced obesity. Here we show that RIIβ knockout (KO) mice have enhanced sensitivity to leptin's effects on both feeding and energy metabolism. After administration of a low dose of leptin, the duration of hypothalamic JAK/STAT3 signalling is increased, resulting in enhanced POMC mRNA induction. Consistent with the extended JAK/STAT3 activation, we find that the negative feedback regulator of leptin receptor signalling, Socs3, is inhibited in the hypothalamus of RIIβ KO mice. During fasting, RIIβ–PKA is activated and this correlates with an increase in CREB phosphorylation. The increase in CREB phosphorylation is absent in the fasted RIIβ KO hypothalamus. Selective inhibition of PKA activity in AgRP neurons partially recapitulates the leanness and resistance to diet-induced obesity of RIIβ KO mice. Our findings suggest that RIIβ–PKA modulates the duration of leptin receptor signalling and therefore the magnitude of the catabolic response to leptin. Mice lacking RIIβ, a regulatory subunit of protein kinase A, are lean and resistant to diet-induced obesity. Here, the authors show that RIIβ regulates leptin sensitivity, acting as a physiological brake on leptin responsiveness and the duration of leptin signalling in the hypothalamus.
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Affiliation(s)
- Linghai Yang
- Department of Pharmacology, University of Washington School of Medicine, 1959 North East Pacific Street, Box 357280, Seattle, Washington 98195, USA
| | - G Stanley McKnight
- Department of Pharmacology, University of Washington School of Medicine, 1959 North East Pacific Street, Box 357280, Seattle, Washington 98195, USA
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26
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Abstract
The pancreatic hormone insulin plays a well-described role in the periphery, based principally on its ability to lower circulating glucose levels via activation of glucose transporters. However, insulin also acts within the central nervous system (CNS) to alter a number of physiological outcomes ranging from energy balance and glucose homeostasis to cognitive performance. Insulin is transported into the CNS by a saturable receptor-mediated process that is proposed to be dependent on the insulin receptor. Transport of insulin into the brain is dependent on numerous factors including diet, glycemia, a diabetic state and notably, obesity. Obesity leads to a marked decrease in insulin transport from the periphery into the CNS and the biological basis of this reduction of transport remains unresolved. Despite decades of research into the effects of central insulin on a wide range of physiological functions and its transport from the periphery to the CNS, numerous questions remain unanswered including which receptor is responsible for transport and the precise mechanisms of action of insulin within the brain.
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Affiliation(s)
- Denovan P Begg
- School of Psychology, University of New South Wales (UNSW, Australia), Sydney, New South Wales, Australia.
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27
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Farr OM, Tsoukas MA, Mantzoros CS. Leptin and the brain: influences on brain development, cognitive functioning and psychiatric disorders. Metabolism 2015; 64:114-30. [PMID: 25092133 DOI: 10.1016/j.metabol.2014.07.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 06/16/2014] [Accepted: 07/05/2014] [Indexed: 12/20/2022]
Abstract
Receptors of leptin, the prototypical adipokine, are expressed throughout the cortex and several other areas of the brain. Although typically studied for its role in energy intake and expenditure, leptin plays a critical role in many other neurocognitive processes and interacts with various other hormones and neurotransmitters to perform these functions. Here, we review the literature on how leptin influences brain development, neural degradation, Alzheimer's disease, psychiatric disorders, and more complicated cognitive functioning and feeding behaviors. We also discuss modulators of leptin and the leptin receptor as they relate to normal cognitive functioning and may mediate some of the actions of leptin in the brain. Although we are beginning to better understand the critical role leptin plays in normal cognitive functioning, there is much to be discovered.
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Affiliation(s)
- Olivia M Farr
- Division of Endocrinology, Boston VA Healthcare System/Harvard Medical School, Boston, MA 02215.
| | - Michael A Tsoukas
- Division of Endocrinology, Boston VA Healthcare System/Harvard Medical School, Boston, MA 02215
| | - Christos S Mantzoros
- Division of Endocrinology, Boston VA Healthcare System/Harvard Medical School, Boston, MA 02215
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28
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Harris RBS, Apolzan JW. Hexosamine biosynthetic pathway activity in leptin resistant sucrose-drinking rats. Physiol Behav 2014; 138:208-18. [PMID: 25446204 DOI: 10.1016/j.physbeh.2014.09.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Revised: 09/21/2014] [Accepted: 09/23/2014] [Indexed: 12/30/2022]
Abstract
Rats offered 30% sucrose solution in addition to chow and water become leptin resistant therefore we investigated the effect of sucrose solution consumption on leptin signaling. In Experiment 1 rats were resistant to 3rd ventricle injections of1.5 μg leptin after 36 days of sucrose and western blot indicated that resistance was associated with increased basal levels of signal transducer and activator of transcription 3 phosphorylation (pSTAT3). In Experiment 2 rats were resistant to a peripheral injection of 2mg leptin/kg after 26 days of sucrose. Immunohistochemistry indicated that increased basal pSTAT3 was limited to the medial and lateral arcuate nucleus of the hypothalamus. Increased availability of glucose and fructose can stimulate the hexosamine biosynthetic pathway (HBP) which O-GlcNAc-modifies proteins. This has the potential to change protein bioactivity. We tested whether this pathway could account for the leptin resistance. There was no increase in the expression of HBP enzymes in tissues from sucrose rats in Experiment 1, however, direct activation of the HBP with a 3h intravenous infusion of 30 μmol/kg/min glucosamine significantly increased hypothalamic pSTAT3. Although sucrose consumption and activation of the HBP both increase hypothalamic pSTAT3 experiments described here did not provide evidence of a direct link between sucrose consumption, HBP activity and leptin resistance. Unexpectedly, we found that the HBP enzyme glutamine fructose-6-phosphate amidotransferase (GFAT) in liver and O-GlcNAcase in hypothalamus were increased 30min after leptin injection in leptin responsive animals, implying a complex interaction between activity of the HBP and leptin responsiveness.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, United States.
| | - John W Apolzan
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, United States
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Frank A, Brown LM, Clegg DJ. The role of hypothalamic estrogen receptors in metabolic regulation. Front Neuroendocrinol 2014; 35:550-7. [PMID: 24882636 PMCID: PMC4174989 DOI: 10.1016/j.yfrne.2014.05.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 05/03/2014] [Accepted: 05/16/2014] [Indexed: 01/23/2023]
Abstract
Estrogens regulate key features of metabolism, including food intake, body weight, energy expenditure, insulin sensitivity, leptin sensitivity, and body fat distribution. There are two 'classical' estrogen receptors (ERs): estrogen receptor alpha (ERS1) and estrogen receptor beta (ERS2). Human and murine data indicate ERS1 contributes to metabolic regulation more so than ESR2. For example, there are human inactivating mutations of ERS1 which recapitulate aspects of the metabolic syndrome in both men and women. Much of our understanding of the metabolic roles of ERS1 was initially uncovered in estrogen receptor α-null mice (ERS1(-/-)); these mice display aspects of the metabolic syndrome, including increased body weight, increased visceral fat deposition and dysregulated glucose intolerance. Recent data further implicate ERS1 in specific tissues and neuronal populations as being critical for regulating food intake, energy expenditure, body fat distribution and adipose tissue function. This review will focus predominantly on the role of hypothalamic ERs and their critical role in regulating all aspects of energy homeostasis and metabolism.
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Affiliation(s)
- Aaron Frank
- Department of Internal Medicine, Touchstone Diabetes Center, University of Texas Southwestern Medical Center, Dallas, TX 75390-8854, USA
| | - Lynda M Brown
- Food and Nutrition Sciences Program, North Carolina Agricultural and Technical State University, Greensboro, NC 27411-0002, USA
| | - Deborah J Clegg
- Department of Internal Medicine, Touchstone Diabetes Center, University of Texas Southwestern Medical Center, Dallas, TX 75390-8854, USA.
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Wang S, Chen J, Yue G, Bai M, Kou M, Jin Z. Neuropeptide Y and leptin receptor expression in the hypothalamus of rats with chronic immobilization stress. Neural Regen Res 2014; 8:1721-6. [PMID: 25206469 PMCID: PMC4145910 DOI: 10.3969/j.issn.1673-5374.2013.18.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 02/12/2013] [Indexed: 12/20/2022] Open
Abstract
In this study, Sprague-Dawley rats were immobilized to a frame for 3 hours a day for 21 days to establish a model of chronic immobilization stress. The body weight and food intake of rats subjected to chronic immobilization stress were significantly decreased compared with the control group. Dual-labeling immunofluorescence revealed that the expression of leptin receptor and the co-localization coeffient in these leptic receptor neurons in the arcuate nucleus of the hypothalamus were both upregulated, while the number of neuropeptide Y neurons was decreased. Chronic immobilization stress induced high expression of leptin receptor in the arcuate nucleus and suppressed the synthesis and secretion of neuropeptide Y, thereby disrupting the pathways in the arcuate nucleus that regulate feeding behavior, resulting in diminished food intake and reduced body weight.
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Affiliation(s)
- Shaoxian Wang
- School of Pre-clinical Medicine, Beijing University of Chinese Medicine, Beijing 100029, China ; Traditional Chinese Medicine College of Hebei Medical University, Shijiazhang 050000, Hebei Province, China
| | - Jiaxu Chen
- School of Pre-clinical Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Guangxin Yue
- Institute of Basic Theory in Chinese Medicine, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Minghua Bai
- School of Pre-clinical Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Meijing Kou
- School of Pre-clinical Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Zhongye Jin
- School of Pre-clinical Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
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31
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Huang G, Li J, Wang H, Lan X, Wang Y. Discovery of a novel functional leptin protein (LEP) in zebra finches: evidence for the existence of an authentic avian leptin gene predominantly expressed in the brain and pituitary. Endocrinology 2014; 155:3385-96. [PMID: 24823393 DOI: 10.1210/en.2014-1084] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Leptin (LEP) is reported to play important roles in controlling energy balance in vertebrates, including birds. However, it remains an open question whether an authentic "LEP gene" exists and functions in birds. Here, we identified and characterized a LEP gene (zebra finch LEP [zbLEP]) encoding a 172-amino acid precursor in zebra finches. Despite zbLEP showing limited amino acid sequence identity (26%-29%) to human and mouse LEPs, synteny analysis proved that zbLEP is orthologous to mammalian LEP. Using a pAH32 luciferase reporter system and Western blot analysis, we demonstrated that the recombinant zbLEP protein could potently activate finch and chicken LEP receptors (zbLEPR; cLEPR) expressed in human embryonic kidney 293 cells and enhance signal transducer and activator of transcription 3 phosphorylation, further indicating that zbLEP is a functional ligand for avian LEPRs. Interestingly, quantitative real-time RT-PCR revealed that zbLEP mRNA is expressed nearly exclusively in the pituitary and various brain regions but undetectable in adipose tissue and liver, whereas zbLEPR mRNA is widely expressed in adult finch tissues examined with abundant expression noted in pituitary, implying that unlike mammalian LEP, finch LEP may not act as an adipocyte-derived signal to control energy balance. As in finches, a LEP highly homologous to zbLEP was also identified in budgerigar genome. Strikingly, finch and budgerigar LEPs show little homology with chicken LEP (cLEP) previously reported, suggesting that the so-called cLEP is incorrect. Collectively, our data provide convincing evidence for the existence of an authentic functional LEP in avian species and suggest an important role of brain- and pituitary-derived LEP played in vertebrates.
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Affiliation(s)
- Guian Huang
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education (G.H., J.L., X.L., Y.W.) and Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province (J.L., H.W., Y.W.), College of Life Sciences, Sichuan University, Chengdu 610065, People's Republic of China
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32
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Sumita T, Ono H, Suzuki T, Sakai G, Inukai K, Katagiri H, Asano T, Katayama S, Awata T. Mediobasal hypothalamic PTEN modulates hepatic insulin resistance independently of food intake in rats. Am J Physiol Endocrinol Metab 2014; 307:E47-60. [PMID: 24824654 DOI: 10.1152/ajpendo.00361.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Phosphatase and tensin homolog (PTEN) dephosphorylates phosphatidylinositol (PI) 3,4,5-triphosphate and antagonizes PI 3-kinase. Insulin acts in the mediobasal hypothalamus (MBH) to not only suppress food intake and weight gain but also improve glucose metabolism via PI 3-kinase activation. Thus, the blocking of hypothalamic PTEN is a potential target for treating obesity as well as diabetes. However, genetic modification of PTEN in specific neuronal populations in the MBH yielded complex results, and no postnatal intervention for hypothalamic PTEN has been reported yet. To elucidate how postnatal modification of hypothalamic PTEN influences food intake as well as glucose metabolism, we bidirectionally altered PTEN activity in the MBH of rats by adenoviral gene delivery. Inhibition of MBH PTEN activity reduced food intake and weight gain, whereas constitutive activation of PTEN tended to induce the opposite effects. Interestingly, the effects of MBH PTEN intervention on food intake and body weight were blunted by high-fat feeding. However, MBH PTEN blockade improved hepatic insulin sensitivity even under high-fat-fed conditions. On the other hand, constitutive activation of MBH PTEN induced hepatic insulin resistance. Hepatic Akt phosphorylation and the G6Pase expression level were modulated bidirectionally by MBH PTEN intervention. These results demonstrate that PTEN in the MBH regulates hepatic insulin sensitivity independently of the effects on food intake and weight gain. Therefore, hypothalamic PTEN is a promising target for treating insulin resistance even in states of overnutrition.
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Affiliation(s)
- Takashi Sumita
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Hiraku Ono
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan;
| | - Tokuko Suzuki
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Gota Sakai
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Kouichi Inukai
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Hideki Katagiri
- Department of Metabolic Diseases, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan; and
| | - Tomoichiro Asano
- Department of Medical Science, Graduate School of Medicine, University of Hiroshima, Hiroshima, Japan
| | - Shigehiro Katayama
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Takuya Awata
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
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Fuente-Martin E, Garcia-Caceres C, Morselli E, Clegg DJ, Chowen JA, Finan B, Brinton RD, Tschöp MH. Estrogen, astrocytes and the neuroendocrine control of metabolism. Rev Endocr Metab Disord 2013; 14:331-8. [PMID: 24009071 PMCID: PMC3825572 DOI: 10.1007/s11154-013-9263-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Obesity, and its associated comorbidities such as type 2 diabetes, cardiovascular diseases, and certain cancers, represent major health challenges. Importantly, there is a sexual dimorphism with respect to the prevalence of obesity and its associated metabolic diseases, implicating a role for gonadal hormones. Specifically, estrogens have been demonstrated to regulate metabolism perhaps by acting as a leptin mimetic in the central nervous system (CNS). CNS estrogen receptors (ERs) include ER alpha (ERα) and ER beta (ERβ), which are found in nuclear, cytoplasmic and membrane sites throughout the brain. Additionally, estrogens can bind to and activate a G protein-coupled estrogen receptor (GPER), which is a membrane-associated ER. ERs are expressed on neurons as well as glia, which are known to play a major role in providing nutrient supply for neurons and have recently received increasing attention for their potentially important involvement in the CNS regulation of systemic metabolism and energy balance. This brief overview summarizes data focusing on the potential role of astrocytic estrogen action as a key component of estrogenic modulation responsible for mediating the sexual dimorphism in body weight regulation and obesity.
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Affiliation(s)
- E. Fuente-Martin
- Institute for Diabetes and Obesity, Helmholtz Zentrum München and Department of Medicine, Technische Universität München, Munich, Germany
| | - C. Garcia-Caceres
- Institute for Diabetes and Obesity, Helmholtz Zentrum München and Department of Medicine, Technische Universität München, Munich, Germany
| | - E. Morselli
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX USA
| | - D. J. Clegg
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX USA
| | - J. A. Chowen
- Hospital Infantil Universitario Niño Jesús, Department of Endocrinology, Instituto de Investigación La Princesa, Madrid, Spain
- Centro de Investigación Biomédica en Red (CIBER) de la Fisiopatología de Obesidad y Nutrición, Instituto de Salud Carlos III, Madrid, Spain
| | - B. Finan
- Institute for Diabetes and Obesity, Helmholtz Zentrum München and Department of Medicine, Technische Universität München, Munich, Germany
| | - R. D. Brinton
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA USA
| | - M. H. Tschöp
- Institute for Diabetes and Obesity, Helmholtz Zentrum München and Department of Medicine, Technische Universität München, Munich, Germany
- Institute for Diabetes and Obesity, Helmholtz Center Munich, HelmholtzZentrum München, German Research Center for Environmental Health (GmbH), Ingolstaedter Landstr. 1, 85764 Neuherberg/Munich, Germany
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34
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Gao S, Moran TH, Lopaschuk GD, Butler AA. Hypothalamic malonyl-CoA and the control of food intake. Physiol Behav 2013; 122:17-24. [PMID: 23988346 DOI: 10.1016/j.physbeh.2013.07.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 12/19/2022]
Abstract
Fatty acid metabolism is implicated in the hypothalamic control of food intake. In this regard, malonyl-CoA, an intermediate in fatty acid synthesis, is emerging as a key player. Malonyl-CoA in the hypothalamus has been proposed as an anorectic mediator in the central control of feeding. A large body of evidence demonstrates that modulating hypothalamic activities of malonyl-CoA metabolic enzymes impacts food intake. Malonyl-CoA action appears to play a significant role in the intracellular signaling pathways underlying leptin anorectic effect in the arcuate nucleus. Ghrelin's hypothalamic effect on feeding may also involve the change in malonyl-CoA metabolism. Hypothalamic malonyl-CoA levels are altered in response to fasting and refeeding, suggesting physiological relevance of the changes in malonyl-CoA level in the controls of feeding and energy balance. Malonyl-CoA inhibits the acyltransferase activity of carnitine palmitoyltransferase-1 (CPT-1), and CPT-1 was considered as a downstream effector in hypothalamic malonyl-CoA effect on feeding. However, recent evidence has not been entirely consistent with this notion. In the arcuate nucleus, the inhibition of CPT-1 acyltransferase activity does not play an important role in the feeding effect of either leptin or cerulenin (a fatty acid synthase inhibitor) that requires the increase in malonyl-CoA level. Alternatively, the brain isoform of CPT-1 (CPT-1c) may act as a downstream target in the malonyl-CoA signaling pathways. CPT-1c does not possess a typical acyltransferase activity, and the exact molecular function of this protein is currently unknown. Recent data indicate it is involved in ceramide metabolism. Of relevance, in the arcuate nucleus, CPT-1c may link malonyl-CoA to ceramide metabolism to affect food intake.
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Affiliation(s)
- Su Gao
- Department of Metabolism and Aging, Scripps Research Institute, Jupiter, FL 33458, USA.
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35
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Abstract
Leptin is secreted into the bloodstream by adipocytes and is required for the maintenance of energy homeostasis and body weight. Leptin deficiency or genetic defects in the components of the leptin signaling pathways cause obesity. Leptin controls energy balance and body weight mainly through leptin receptor b (LEPRb)-expressing neurons in the brain, particularly in the hypothalamus. These LEPRb-expressing neurons function as the first-order neurons that project to the second-order neurons located within and outside the hypothalamus, forming a neural network that controls the energy homeostasis and body weight. Multiple factors, including inflammation and endoplasmic reticulum (ER) stress, contribute to leptin resistance. Leptin resistance is the key risk factor for obesity. This review is focused on recent advance about leptin action, leptin signaling, and leptin resistance.
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Nordström V, Willershäuser M, Herzer S, Rozman J, von Bohlen Und Halbach O, Meldner S, Rothermel U, Kaden S, Roth FC, Waldeck C, Gretz N, de Angelis MH, Draguhn A, Klingenspor M, Gröne HJ, Jennemann R. Neuronal expression of glucosylceramide synthase in central nervous system regulates body weight and energy homeostasis. PLoS Biol 2013; 11:e1001506. [PMID: 23554574 PMCID: PMC3595213 DOI: 10.1371/journal.pbio.1001506] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 01/31/2013] [Indexed: 01/19/2023] Open
Abstract
Body weight and energy homeostasis are regulated by leptin receptor interactions with gangliosides, a class of plasma membrane lipids, in forebrain neurons of mice. Hypothalamic neurons are main regulators of energy homeostasis. Neuronal function essentially depends on plasma membrane-located gangliosides. The present work demonstrates that hypothalamic integration of metabolic signals requires neuronal expression of glucosylceramide synthase (GCS; UDP-glucose:ceramide glucosyltransferase). As a major mechanism of central nervous system (CNS) metabolic control, we demonstrate that GCS-derived gangliosides interacting with leptin receptors (ObR) in the neuronal membrane modulate leptin-stimulated formation of signaling metabolites in hypothalamic neurons. Furthermore, ganglioside-depleted hypothalamic neurons fail to adapt their activity (c-Fos) in response to alterations in peripheral energy signals. Consequently, mice with inducible forebrain neuron-specific deletion of the UDP-glucose:ceramide glucosyltransferase gene (Ugcg) display obesity, hypothermia, and lower sympathetic activity. Recombinant adeno-associated virus (rAAV)-mediated Ugcg delivery to the arcuate nucleus (Arc) significantly ameliorated obesity, specifying gangliosides as seminal components for hypothalamic regulation of body energy homeostasis. Obesity is a growing health threat that affects nearly half a billion people worldwide, and its incidence rates in lower income countries are rising dramatically. As obesity is a major risk factor for type II diabetes and cardiovascular disease, significant effort has been put into the exploration of causes, prevention, and potential treatment. Recent research has demonstrated that a region of the brain called the hypothalamus is a major integrator of metabolic and nutrient signals, adapting food intake and energy expenditure to current metabolic needs. Leptin or insulin receptors located in the plasma cell membrane of neurons sense energy signals from the body. They transmit this information inside the cell, which then regulates neuronal function. In this study, we show that leptin receptors interact with gangliosides, a class of plasma membrane lipids. This interaction is a prerequisite for proper receptor activation. Consequently, ganglioside loss in hypothalamic neurons inhibits leptin receptor signal transduction in response to energy metabolites. Furthermore, mice lacking gangliosides in distinct forebrain areas, amongst them the hypothalamus, develop progressive obesity and hypothermia. Our results suggest a previously unknown regulatory mechanism of plasma membrane lipids for hypothalamic control of body weight.
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Affiliation(s)
- Viola Nordström
- Department of Cellular and Molecular Pathology, German Cancer Research Center, Heidelberg, Germany.
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Williams KW, Elmquist JK. From neuroanatomy to behavior: central integration of peripheral signals regulating feeding behavior. Nat Neurosci 2012; 15:1350-5. [PMID: 23007190 PMCID: PMC3763714 DOI: 10.1038/nn.3217] [Citation(s) in RCA: 296] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Over the past two centuries, prevalent models of energy and glucose homeostasis have emerged from careful anatomical descriptions in tandem with an understanding of cellular physiology. More recent technological advances have culminated in the identification of peripheral and central factors that influence neural circuits regulating metabolism. This Review highlights contributions to our understanding of peripheral and central factors regulating food intake and energy expenditure.
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Affiliation(s)
- Kevin W Williams
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA.
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39
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Harwood HJ. The adipocyte as an endocrine organ in the regulation of metabolic homeostasis. Neuropharmacology 2012; 63:57-75. [DOI: 10.1016/j.neuropharm.2011.12.010] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/28/2011] [Accepted: 12/09/2011] [Indexed: 02/06/2023]
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Neuroanatomical determinants of the sympathetic nerve responses evoked by leptin. Clin Auton Res 2012; 23:1-7. [PMID: 22714900 DOI: 10.1007/s10286-012-0168-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/18/2012] [Indexed: 01/04/2023]
Abstract
Leptin is an adipocyte-derived hormone that relays a satiety signal to the brain. The effect of leptin on the sympathetic nervous system is an important aspect in the regulation of energy homeostasis as well as several other physiological functions. The arcuate nucleus of the hypothalamus is considered a major site for the regulation of physiological processes by leptin. However, there is growing recognition that other hypothalamic and extra-hypothalamic brain nuclei are important for leptin regulation of physiological processes including sympathetic nerve traffic. The current review discusses the various hypothalamic and extra-hypothalamic nuclei that have been implicated in leptin-induced increase in regional sympathetic nerve activity. The continuous rise in the prevalence of obesity underscores the importance of understanding the underlying neural mechanisms regulating sympathetic traffic to different tissues to design effective strategies to reverse obesity and associated diseases.
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Mizrahi M, Ben Ya'acov A, Ilan Y. Gastric stimulation for weight loss. World J Gastroenterol 2012; 18:2309-19. [PMID: 22654422 PMCID: PMC3353365 DOI: 10.3748/wjg.v18.i19.2309] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/02/2011] [Accepted: 04/28/2012] [Indexed: 02/06/2023] Open
Abstract
The prevalence of obesity is growing to epidemic proportions, and there is clearly a need for minimally invasive therapies with few adverse effects that allow for sustained weight loss. Behavior and lifestyle therapy are safe treatments for obesity in the short term, but the durability of the weight loss is limited. Although promising obesity drugs are in development, the currently available drugs lack efficacy or have unacceptable side effects. Surgery leads to long-term weight loss, but it is associated with morbidity and mortality. Gastric electrical stimulation (GES) has received increasing attention as a potential tool for treating obesity and gastrointestinal dysmotility disorders. GES is a promising, minimally invasive, safe, and effective method for treating obesity. External gastric pacing is aimed at alteration of the motility of the gastrointestinal tract in a way that will alter absorption due to alteration of transit time. In addition, data from animal models and preliminary data from human trials suggest a role for the gut-brain axis in the mechanism of GES. This may involve alteration of secretion of hormones associated with hunger or satiety. Patient selection for gastric stimulation therapy seems to be an important determinant of the treatment’s outcome. Here, we review the current status, potential mechanisms of action, and possible future applications of gastric stimulation for obesity.
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Abstract
The hypothalamus is one of the master regulators of various physiological processes, including energy balance and nutrient metabolism. These regulatory functions are mediated by discrete hypothalamic regions that integrate metabolic sensing with neuroendocrine and neural controls of systemic physiology. Neurons and nonneuronal cells in these hypothalamic regions act supportively to execute metabolic regulations. Under conditions of brain and hypothalamic inflammation, which may result from overnutrition-induced intracellular stresses or disease-associated systemic inflammatory factors, extracellular and intracellular environments of hypothalamic cells are disrupted, leading to central metabolic dysregulations and various diseases. Recent research has begun to elucidate the effects of hypothalamic inflammation in causing diverse components of metabolic syndrome leading to diabetes and cardiovascular disease. These new understandings have provocatively expanded previous knowledge on the cachectic roles of brain inflammatory response in diseases, such as infections and cancers. This review describes the molecular and cellular characteristics of hypothalamic inflammation in metabolic syndrome and related diseases as opposed to cachectic diseases, and also discusses concepts and potential applications of inhibiting central/hypothalamic inflammation to treat nutritional diseases.
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Affiliation(s)
- Dongsheng Cai
- Department of Molecular Pharmacology, Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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43
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Distinct roles for specific leptin receptor signals in the development of hypothalamic feeding circuits. J Neurosci 2012; 32:1244-52. [PMID: 22279209 DOI: 10.1523/jneurosci.2277-11.2012] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Circulating hormones influence multiple aspects of hypothalamic development and play a role in directing formation of neural circuits. Leptin is secreted by adipocytes and functions as a key developmental signal that promotes axon outgrowth from the arcuate nucleus (ARH) during a discrete developmental critical period. To determine the cellular mechanisms by which leptin impacts development of hypothalamic circuits, we examined roles for leptin receptor (LepRb) signals in neonatal mice. LepRb, ERK, and STAT3 signaling were required for leptin-stimulated neurite outgrowth from ARH explants in vitro. Neonatal mice with disrupted LepRb→ERK signaling displayed impaired ARH projections but were able to compensate by adulthood. LepRb→STAT3 signaling also plays a role in early circuit formation and controls the ultimate architecture of POMC, but not AgRP, projections. Thus, the developmental actions of leptin on feeding circuits are dependent on LepRb, and distinct signaling pathways are responsible for directing formation of NPY and POMC projections.
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Berglund ED, Vianna CR, Donato J, Kim MH, Chuang JC, Lee CE, Lauzon DA, Lin P, Brule LJ, Scott MM, Coppari R, Elmquist JK. Direct leptin action on POMC neurons regulates glucose homeostasis and hepatic insulin sensitivity in mice. J Clin Invest 2012; 122:1000-9. [PMID: 22326958 DOI: 10.1172/jci59816] [Citation(s) in RCA: 244] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 01/04/2012] [Indexed: 01/01/2023] Open
Abstract
Leptin action on its receptor (LEPR) stimulates energy expenditure and reduces food intake, thereby lowering body weight. One leptin-sensitive target cell mediating these effects on energy balance is the proopiomelano-cortin (POMC) neuron. Recent evidence suggests that the action of leptin on POMC neurons regulates glucose homeostasis independently of its effects on energy balance. Here, we have dissected the physiological impact of direct leptin action on POMC neurons using a mouse model in which endogenous LEPR expression was prevented by a LoxP-flanked transcription blocker (loxTB), but could be reactivated by Cre recombinase. Mice homozygous for the Lepr(loxTB) allele were obese and exhibited defects characteristic of LEPR deficiency. Reexpression of LEPR only in POMC neurons in the arcuate nucleus of the hypothalamus did not reduce food intake, but partially normalized energy expenditure and modestly reduced body weight. Despite the moderate effects on energy balance and independent of changes in body weight, restoring LEPR in POMC neurons normalized blood glucose and ameliorated hepatic insulin resistance, hyperglucagonemia, and dyslipidemia. Collectively, these results demonstrate that direct leptin action on POMC neurons does not reduce food intake, but is sufficient to normalize glucose and glucagon levels in mice otherwise lacking LEPR.
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Affiliation(s)
- Eric D Berglund
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical School, Dallas, Texas 75390-9051, USA
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Gamber KM, Huo L, Ha S, Hairston JE, Greeley S, Bjørbæk C. Over-expression of leptin receptors in hypothalamic POMC neurons increases susceptibility to diet-induced obesity. PLoS One 2012; 7:e30485. [PMID: 22276206 PMCID: PMC3262822 DOI: 10.1371/journal.pone.0030485] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 12/21/2011] [Indexed: 12/22/2022] Open
Abstract
Diet-induced obesity (DIO) in rodents is characterized by impaired activation of signal-transducer and activator of transcription 3 (STAT3) by leptin receptors (LepRb) within the hypothalamic arcuate nucleus. This signaling defect likely plays an important role in development of DIO. However, the neuro-chemical identity of the leptin-STAT3 resistant arcuate neurons has not been determined and the underlying mechanisms responsible for development of cellular leptin resistance remain unclear. To investigate this, we first measured arcuate gene expression of known key signaling components of the LepRb signaling pathway and tested whether specifically the critical arcuate pro-opiomelanocortin (POMC) neurons are resistant to LepRb-STAT3 signaling in mice given a high-fat-diet (HFD) compared to mice provided a low-fat control diet (LFD). We found that leptin-dependent STAT3 phosphorylation was decreased within POMC neurons of HFD mice. In addition, Leprb mRNA and suppressor of cytokine signaling 3 (Socs3) mRNA were elevated in the arcuate of HFD mice. To investigate whether increased LepRb expression per se in POMC neurons can influence development of DIO and Socs3 expression, we created mice that over-express LepRb selectively in POMC neurons (POMC-LepRb). No differences in body weight, fat mass or food intake were found between LFD POMC-LepRb mice and LFD controls. Surprisingly, body weight, fat mass and caloric intake of HFD POMC-LepRb mice was markedly higher than HFD control mice. In addition, arcuate Socs3 mRNA was increased in HFD POMC-LepRb mice compared to HFD controls. These data show that specifically POMC neurons of DIO mice are resistant to STAT3 activation by leptin, indicating that those cells might play a role in development of DIO. Furthermore, over-expression of LepRb selectively in POMC neurons increases susceptibility to the development of DIO. We propose a model where over-reactivity of the leptin-LepRb signaling system in arcuate neurons may play causal a role in development of diet-induced obesity.
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Affiliation(s)
- Kevin M. Gamber
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Lihong Huo
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sangdeuk Ha
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Joyce E. Hairston
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sarah Greeley
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Christian Bjørbæk
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Abstract
When administered into the brain, NPY acts at Y1 and Y5 receptors to increase food intake. The response occurs with a short latency and is quite robust, such that exogenous NPY is generally considered to be the most potent of a growing list of orexigenic compounds that act in the brain. The role of endogenous NPY is not so straightforward, however. Evidence from diverse types of experiments suggests that rather than initiating behavioral eating per se, endogenous NPY elicits autonomic responses that prepare the individual to better cope with consuming a calorically large meal.
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Affiliation(s)
- Adam P Chambers
- Departments of Medicine, University of Cincinnati, OH 45237, USA
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47
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Abstract
The hormone leptin, secreted predominantly from adipose tissue, plays a crucial role in the regulation of numerous neuroendocrine functions, from energy homeostasis to reproduction. Genetic deficiency as a consequence of leptin or leptin receptor mutations, although rare in humans, leads to early onset of chronic hyperphagia and massive obesity. In most human obesity, however, leptin levels are chronically elevated. Under these conditions of persistent hyperleptinaemia, and particularly when obesity is associated with a high-fat diet, leptin resistance develops, and signalling through the leptin receptor is curtailed, fuelling further weight gain. Here, we review the role of leptin receptors in the regulation of feeding and obesity development. Leptin receptors are found in each of the major components of the CNS "feeding" circuitry-the brainstem, hypothalamus and distributed reward centres. Through these receptors, leptin exerts influences on signalling and integration within these circuits to alter feeding behaviours. Although some progress is now being made with peptide analogues, the leptin receptor has not proved to be amenable to small molecule pharmacological intervention to date. Where clinical benefit from recombinant leptin administration has been achieved, this has been under circumstances of complete endogenous leptin deficiency or relative hypoleptinaemia such as in lipodystrophy.
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Affiliation(s)
- Elizabeth C Cottrell
- Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Scotland, EH16 4TH, UK
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Leinninger GM, Opland DM, Jo YH, Faouzi M, Christensen L, Cappellucci LA, Rhodes CJ, Gnegy ME, Becker JB, Pothos EN, Seasholtz AF, Thompson RC, Myers MG. Leptin action via neurotensin neurons controls orexin, the mesolimbic dopamine system and energy balance. Cell Metab 2011; 14:313-23. [PMID: 21907138 PMCID: PMC3183584 DOI: 10.1016/j.cmet.2011.06.016] [Citation(s) in RCA: 258] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 05/24/2011] [Accepted: 06/14/2011] [Indexed: 01/04/2023]
Abstract
Leptin acts on leptin receptor (LepRb)-expressing neurons throughout the brain, but the roles for many populations of LepRb neurons in modulating energy balance and behavior remain unclear. We found that the majority of LepRb neurons in the lateral hypothalamic area (LHA) contain neurotensin (Nts). To investigate the physiologic role for leptin action via these LepRb(Nts) neurons, we generated mice null for LepRb specifically in Nts neurons (Nts-LepRbKO mice). Nts-LepRbKO mice demonstrate early-onset obesity, modestly increased feeding, and decreased locomotor activity. Furthermore, consistent with the connection of LepRb(Nts) neurons with local orexin (OX) neurons and the ventral tegmental area (VTA), Nts-LepRbKO mice exhibit altered regulation of OX neurons and the mesolimbic DA system. Thus, LHA LepRb(Nts) neurons mediate physiologic leptin action on OX neurons and the mesolimbic DA system, and contribute importantly to the control of energy balance.
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Affiliation(s)
- Gina M. Leinninger
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
- Correspondence: Martin G. Myers, Jr., M.D., Ph.D. and Gina M. Leinninger, Ph.D. Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine University of Michigan Medical School 6317 Brehm Tower 1000 Wall St. Ann Arbor, MI 48105 PH: 734-647-9515 Fax: 734-232-8175 ;
| | - Darren M. Opland
- Neuroscience Program, University of Michigan, Ann Arbor, MI 48109
| | - Young-Hwan Jo
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Miro Faouzi
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Lyndsay Christensen
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
| | - Laura A. Cappellucci
- Department of Molecular Physiology and Pharmacology, Tufts University School of Medicine, Boston, MA 02111
| | | | - Margaret E. Gnegy
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109
| | - Jill B. Becker
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109
| | - Emmanuel N. Pothos
- Department of Molecular Physiology and Pharmacology, Tufts University School of Medicine, Boston, MA 02111
| | - Audrey F. Seasholtz
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109
| | - Robert C. Thompson
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109
- Department of Psychiatry, University of Michigan, Ann Arbor, MI 48109
| | - Martin G. Myers
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109
- Neuroscience Program, University of Michigan, Ann Arbor, MI 48109
- Correspondence: Martin G. Myers, Jr., M.D., Ph.D. and Gina M. Leinninger, Ph.D. Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine University of Michigan Medical School 6317 Brehm Tower 1000 Wall St. Ann Arbor, MI 48105 PH: 734-647-9515 Fax: 734-232-8175 ;
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Abstract
The central nervous system (CNS), generally accepted to regulate energy homeostasis, has been implicated in the metabolic perturbations that either cause or are associated with obesity. Normally, the CNS receives hormonal, metabolic, and neuronal input to assure adequate energy levels and maintain stable energy homeostasis. Recent evidence also supports that the CNS uses these same inputs to regulate glucose homeostasis and this aspect of CNS regulation also becomes impaired in the face of dietary-induced obesity. This review focuses on the literature surrounding hypothalamic regulation of energy and glucose homeostasis and discusses how dysregulation of this system may contribute to obesity and T2DM.
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50
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Gautron L, Elmquist JK. Sixteen years and counting: an update on leptin in energy balance. J Clin Invest 2011; 121:2087-93. [PMID: 21633176 DOI: 10.1172/jci45888] [Citation(s) in RCA: 245] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cloned in 1994, the ob gene encodes the protein hormone leptin, which is produced and secreted by white adipose tissue. Since its discovery, leptin has been found to have profound effects on behavior, metabolic rate, endocrine axes, and glucose fluxes. Leptin deficiency in mice and humans causes morbid obesity, diabetes, and various neuroendocrine anomalies, and replacement leads to decreased food intake, normalized glucose homeostasis, and increased energy expenditure. Here, we provide an update on the most current understanding of leptin-sensitive neural pathways in terms of both anatomical organization and physiological roles.
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Affiliation(s)
- Laurent Gautron
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
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