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LeDuc CA, Skowronski AA, Rosenbaum M. The Role of Leptin in the Development of Energy Homeostatic Systems and the Maintenance of Body Weight. Front Physiol 2021; 12:789519. [PMID: 34955895 PMCID: PMC8703217 DOI: 10.3389/fphys.2021.789519] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 11/17/2021] [Indexed: 12/12/2022] Open
Abstract
LEP is a pleiotropic gene and the actions of leptin extend well beyond simply acting as the signal of the size of adipose tissue stores originally proposed. This is a discussion of the multi-system interactions of leptin with the development of the neural systems regulating energy stores, and the subsequent maintenance of energy stores throughout the lifespan. The prenatal, perinatal, and later postnatal effects of leptin on systems regulating body energy stores and on the energy stores themselves are heavily influenced by the nutritional environment which leptin exposure occurs. This review discusses the prenatal and perinatal roles of leptin in establishing the neuronal circuitry and other systems relevant to the adiposity set-point (or “threshold”) and the role of leptin in maintaining weight homeostasis in adulthood. Therapeutic manipulation of the intrauterine environment, use of leptin sensitizing agents, and identification of specific cohorts who may be more responsive to leptin or other means of activating the leptin signaling pathway are ripe areas for future research.
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Affiliation(s)
- Charles A LeDuc
- Division of Molecular Genetics, Department of Pediatrics, Columbia University Irving Medical Center, New York, NY, United States
| | - Alicja A Skowronski
- Division of Molecular Genetics, Department of Pediatrics, Columbia University Irving Medical Center, New York, NY, United States
| | - Michael Rosenbaum
- Division of Molecular Genetics, Department of Pediatrics, Columbia University Irving Medical Center, New York, NY, United States
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2
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de F Rocha AR, de S Morais N, Priore SE, do C C Franceschini S. Inflammatory Biomarkers and Components of Metabolic Syndrome in Adolescents: a Systematic Review. Inflammation 2021; 45:14-30. [PMID: 34546513 DOI: 10.1007/s10753-021-01549-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 08/16/2021] [Indexed: 12/28/2022]
Abstract
Metabolic syndrome (MetS) has been prevalent among adolescents. The association between the concentration of inflammatory markers and the individual components of the metabolic syndrome indicates that inflammation, when there is no recent or ongoing disease, mediated by an inflammatory process, is an event that may precede the development of metabolic disorders in teenagers. The objective of this study is to verify the association of inflammatory biomarkers with the components of metabolic syndrome in adolescents. From a search of 3 databases, 13 articles met the study inclusion criteria. Two investigators independently extracted data from included studies. The evaluated inflammatory biomarkers are related to the components of MetS (insulin resistance, central and visceral obesity, arterial hypertension, dyslipidemia), which may increase the risk of developing the syndrome in adolescents. The results of this review are of clinical relevance, since the evaluation of inflammatory biomarkers in the presence of metabolic alterations can help to identify the risk factors that lead to the progression of MetS in adolescents.
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Affiliation(s)
- Ariane R de F Rocha
- Department of Nutrition and Health, Postgraduate Program in Nutrition Science, Universidade Federal de Viçosa (UFV), Av PH Rolfs, Minas Gerais, 36570-900, Viçosa, Brazil.
| | - Núbia de S Morais
- Department of Nutrition and Health, Postgraduate Program in Nutrition Science, Universidade Federal de Viçosa (UFV), Av PH Rolfs, Minas Gerais, 36570-900, Viçosa, Brazil
| | - Silvia E Priore
- Department of Nutrition and Health, Universidade Federal de Viçosa (UFV), Minas Gerais, 36570-900, Viçosa, Brazil
| | - Sylvia do C C Franceschini
- Department of Nutrition and Health, Universidade Federal de Viçosa (UFV), Minas Gerais, 36570-900, Viçosa, Brazil
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3
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Contreras-Chavez GG, Estrada JA, Contreras I. Changes in Appetite Regulation-Related Signaling Pathways in the Brain of Mice Supplemented with Non-nutritive Sweeteners. J Mol Neurosci 2020; 71:1144-1155. [PMID: 33128194 DOI: 10.1007/s12031-020-01737-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 10/19/2020] [Indexed: 10/23/2022]
Abstract
Non-nutritive sweeteners (NNSs) are commonly used to prevent weight gain and development of metabolic diseases associated with consumption of high-energy diets. Recent studies have demonstrated that these compounds may have unwanted detrimental effects under specific circumstances in vivo. In particular, an association between NNS consumption and changes in signaling pathways involved in the hunger-satiety system in the brain has been reported. Nonetheless, the extent of alterations in brain signaling pathways associated with consumption of these compounds has not been determined. The objective of this study was to determine the effect of frequent consumption of NNSs on the expression of proteins involved in signaling pathways related to appetite control in the brain in vivo. Eight-week-old BALB/c mice were supplemented with sucrose, sucralose, or steviol glycosides in their daily drinking water for 6 weeks. Subsequently, total brain protein extracts were used to analyze the expression of total and phosphorylated JAK2, STAT5, ERK 1/2, JNK, as well as SHP-2 and POMC, by western blot. Serum concentrations of leptin and α-MSH were quantified by ELISA. Results show that consumption of NNSs promotes significant changes in these signaling pathways, reducing the expression of pSTAT5/STAT5, pERK 1/2, SHP-2, and pJNK/JNK in male mice supplemented with steviol glycosides. Furthermore, consumption of steviol glycosides induced a decrease of α-MSH in male mice. In contrast, steviol glycosides induced overexpression of pSTAT5, pERK, and SHP-2 in females. These data suggest that chronic consumption of NNSs promotes sex-specific changes in signaling pathways related to the central hunger-satiety system in vivo.
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Affiliation(s)
- Gerson G Contreras-Chavez
- Laboratorio de Neuroquímica, Facultad de Medicina, Universidad Autónoma del Estado de México, Paseo Tollocan S/N Esq. Jesús Carranza, Colonia Moderna de La Cruz, Estado de México, 50180, Toluca, Mexico
| | - José A Estrada
- Laboratorio de Neuroquímica, Facultad de Medicina, Universidad Autónoma del Estado de México, Paseo Tollocan S/N Esq. Jesús Carranza, Colonia Moderna de La Cruz, Estado de México, 50180, Toluca, Mexico
| | - Irazú Contreras
- Laboratorio de Neuroquímica, Facultad de Medicina, Universidad Autónoma del Estado de México, Paseo Tollocan S/N Esq. Jesús Carranza, Colonia Moderna de La Cruz, Estado de México, 50180, Toluca, Mexico.
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Framnes SN, Arble DM. The Bidirectional Relationship Between Obstructive Sleep Apnea and Metabolic Disease. Front Endocrinol (Lausanne) 2018; 9:440. [PMID: 30127766 PMCID: PMC6087747 DOI: 10.3389/fendo.2018.00440] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/17/2018] [Indexed: 12/22/2022] Open
Abstract
Obstructive sleep apnea (OSA) is a common sleep disorder, effecting 17% of the total population and 40-70% of the obese population (1, 2). Multiple studies have identified OSA as a critical risk factor for the development of obesity, diabetes, and cardiovascular diseases (3-5). Moreover, emerging evidence indicates that metabolic disorders can exacerbate OSA, creating a bidirectional relationship between OSA and metabolic physiology. In this review, we explore the relationship between glycemic control, insulin, and leptin as both contributing factors and products of OSA. We conclude that while insulin and leptin action may contribute to the development of OSA, further research is required to determine the mechanistic actions and relative contributions independent of body weight. In addition to increasing our understanding of the etiology, further research into the physiological mechanisms underlying OSA can lead to the development of improved treatment options for individuals with OSA.
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Affiliation(s)
| | - Deanna M. Arble
- Department of Biological Sciences, Marquette University, Milwaukee, WI, United States
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5
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Nesrine Z, Haithem H, Imen B, Fadoua N, Asma O, Fadhel NM, Ali B. Leptin and Leptin receptor polymorphisms, plasma Leptin levels and obesity in Tunisian volunteers. Int J Exp Pathol 2018; 99:121-130. [PMID: 29893028 DOI: 10.1111/iep.12271] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 04/14/2018] [Indexed: 12/14/2022] Open
Abstract
Adipose tissue is an important endocrine organ that secretes a number of adipokines, like Leptin (LEP). The aim this study was to investigate the prevalence of single nucleotide polymorphisms in LEP gene (LEP 3'UTR A/C, -2548 G/A) and LEPR (K109R and Q223R) and their association with Leptin level and obesity. We recruited 169 non-obese (body mass index [BMI] = 24.51-3.69 kg/m2 ) and 160 obese (BMI = 36-4.78 kg/m2 ) patients. Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism, BMI was calculated, and Leptin level was measured by ELISA. Statistical analyses were performed by spss19.0. According to LEP 3'UTR A/C polymorphism, AC and CC genotype carriers had higher Leptin levels than AA genotype carriers, respectively, 31[0.05-148.8] (P = .008) vs 41[0.05-111.6] (P = .003). The K109R polymorphism was associated with obesity (P = .025) and seems to significantly decrease the LEP levels (P < .001). Concerning LEP G2548A polymorphism, our results showed that the OR of obesity associated with 2548 AA/GG was 1.87[1.106-2.78] P = .028 vs 1.41[1.035-1.85] P = .045 for 223AA/GG polymorphism. In our haplotype analysis, one haplotype seems to be the more protective and one other seems to be the highest risk to obesity. LEP 3'UTR A/C and LEPR K109R polymorphisms were associated with Leptin level and obesity.
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Affiliation(s)
- Zayani Nesrine
- Biochemistry Department, LR12SP11, Sahloul University Hospital, Sousse, Tunisia
| | - Hamdouni Haithem
- Biochemistry Department, LR12SP11, Sahloul University Hospital, Sousse, Tunisia
| | - Boumaiza Imen
- Biochemistry Department, LR12SP11, Sahloul University Hospital, Sousse, Tunisia
| | - Neffati Fadoua
- Laboratory of Biochemistry and Toxicology, Monastir's University Hospital, Monastir, Tunisia
| | - Omezzine Asma
- Biochemistry Department, LR12SP11, Sahloul University Hospital, Sousse, Tunisia
| | - Najjar Mohamed Fadhel
- Laboratory of Biochemistry and Toxicology, Monastir's University Hospital, Monastir, Tunisia
| | - Bouslama Ali
- Biochemistry Department, LR12SP11, Sahloul University Hospital, Sousse, Tunisia
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Shimabukuro M. Leptin Resistance and Lipolysis of White Adipose Tissue: An Implication to Ectopic Fat Disposition and Its Consequences. J Atheroscler Thromb 2017; 24:1088-1089. [PMID: 28781341 PMCID: PMC5684473 DOI: 10.5551/jat.ed083] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Michio Shimabukuro
- Department of Diabetes, Endocrinology and Metabolism, School of Medicine, Fukushima Medical University
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Madeira I, Bordallo MA, Rodrigues NC, Carvalho C, Gazolla F, Collett-Solberg P, Medeiros C, Bordallo AP, Borges M, Monteiro C, Ribeiro R. Leptin as a predictor of metabolic syndrome in prepubertal children. ARCHIVES OF ENDOCRINOLOGY AND METABOLISM 2017; 61:7-13. [PMID: 27598976 PMCID: PMC10522114 DOI: 10.1590/2359-3997000000199] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 01/04/2016] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Leptin has been suggested as a potential biomarker of cardiovascular risk. This paper aims to ascertain, based on a sample of prepubertal children, which serum leptin value best suited to identify metabolic syndrome (MS). SUBJECTS AND METHODS This observational, cross-sectional study recruited children from the outpatient pediatrics clinic, with the purpose of validating serum leptin level cutoffs to identify MS. All obese and overweight children who met eligibility criteria were included in the study, as was a sample of normal-weight children. The sample underwent clinical assessment and blood fasting glucose, lipid profile, insulin, and leptin were measured. Sensitivity and specificity were estimated for each leptin measurement, using MS as the outcome. These values were used to construct a receiver operating characteristic (ROC) curve. The association between MS and leptin was assessed using logistic models to predict MS. RESULTS A total of 65 normal weight, 46 overweight, and 164 obese children were analyzed (160 boys, 115 girls; age: 93.7 ± 17.8 months). The most appropriate leptin cutoff was 13.4 ng/mL (sensitivity 67.6%; specificity 68.9%; accuracy 72.1%). The logistic model indicated that leptin levels above 13.4 ng/dL were significantly associated with MS and that, for every 1 ng/dL increase in leptin levels, the odds of MS increase by 3% (p = 0.002; OR 1.03; 95% CI 1.01-1.05). CONCLUSIONS Leptin may be a useful biomarker of cardiovascular risk in prepubertal children, with an optimal cutoff of 13.4 ng/mL. Identification of potential new risk markers for cardiovascular disease in children could contribute to the development of preventive strategies.
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Affiliation(s)
- Isabel Madeira
- Faculdade de Ciências MédicasDepartamento de PediatriaUniversidade do Estado do Rio de JaneiroRio de JaneiroRJBrasilFaculdade de Ciências Médicas, Departamento de Pediatria, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ, Brasil
| | - Maria Alice Bordallo
- Faculdade de Ciências MédicasDepartamento de Medicina InternaUERJRio de JaneiroRJBrasilFaculdade de Ciências Médicas, Departamento de Medicina Interna, UERJ, Rio de Janeiro, RJ, Brasil
| | - Nádia Cristina Rodrigues
- Faculdade de Ciências MédicasDepartamento de Tecnologias da Informação e Educação em SaúdeUERJRio de JaneiroRJBrasilFaculdade de Ciências Médicas, Departamento de Tecnologias da Informação e Educação em Saúde, UERJ, Rio de Janeiro, RJ, Brasil
| | - Cecilia Carvalho
- Instituto de NutriçãoDepartamento de Nutrição AplicadaUERJRio de JaneiroRJBrasilInstituto de Nutrição, Departamento de Nutrição Aplicada, UERJ, Rio de Janeiro, RJ, Brasil
| | - Fernanda Gazolla
- Hospital Universitário Pedro ErnestoUnidade Docente Assistencial de Endocrinologia e MetabologiaUERJRio de JaneiroRJBrasilHospital Universitário Pedro Ernesto, Unidade Docente Assistencial de Endocrinologia e Metabologia, UERJ, Rio de Janeiro, RJ, Brasil
| | - Paulo Collett-Solberg
- Faculdade de Ciências MédicasDepartamento de Medicina InternaUERJRio de JaneiroRJBrasilFaculdade de Ciências Médicas, Departamento de Medicina Interna, UERJ, Rio de Janeiro, RJ, Brasil
| | - Clarice Medeiros
- Hospital Universitário Pedro ErnestoUnidade Docente Assistencial de Endocrinologia e MetabologiaUERJRio de JaneiroRJBrasilHospital Universitário Pedro Ernesto, Unidade Docente Assistencial de Endocrinologia e Metabologia, UERJ, Rio de Janeiro, RJ, Brasil
| | - Ana Paula Bordallo
- Hospital Universitário Pedro ErnestoUnidade Docente Assistencial de Endocrinologia e MetabologiaUERJRio de JaneiroRJBrasilHospital Universitário Pedro Ernesto, Unidade Docente Assistencial de Endocrinologia e Metabologia, UERJ, Rio de Janeiro, RJ, Brasil
| | - Marcos Borges
- Hospital Universitário Pedro ErnestoUnidade Docente Assistencial de Endocrinologia e MetabologiaUERJRio de JaneiroRJBrasilHospital Universitário Pedro Ernesto, Unidade Docente Assistencial de Endocrinologia e Metabologia, UERJ, Rio de Janeiro, RJ, Brasil
| | - Claudia Monteiro
- Hospital Universitário Pedro ErnestoUnidade Docente Assistencial de Endocrinologia e MetabologiaUERJRio de JaneiroRJBrasilHospital Universitário Pedro Ernesto, Unidade Docente Assistencial de Endocrinologia e Metabologia, UERJ, Rio de Janeiro, RJ, Brasil
| | - Rebeca Ribeiro
- Faculdade de Ciências MédicasUERJRio de JaneiroRJBrasilFaculdade de Ciências Médicas, UERJ, Rio de Janeiro, RJ, Brasil
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Shearrer GE, O'Reilly GA, Belcher BR, Daniels MJ, Goran MI, Spruijt-Metz D, Davis JN. The impact of sugar sweetened beverage intake on hunger and satiety in minority adolescents. Appetite 2016; 97:43-8. [PMID: 26606887 PMCID: PMC5266547 DOI: 10.1016/j.appet.2015.11.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 11/09/2015] [Accepted: 11/11/2015] [Indexed: 12/18/2022]
Abstract
Limited research has examined the effects of habitual SSB consumption on hunger/fullness ratings and gut hormones. This study hypothesized that high versus low intakes of habitual SSBs would result in greater hunger, decreased fullness, and a blunted gut hormone response, however the high versus low fiber group would exhibit decreased hunger and increased fullness. This was a randomized crossover feeding trial with 47 African American and Hispanic adolescents. The experiment included three 24-hour recalls to assess habitual dietary intake. During the test meal phase, subjects were served breakfast and lunch. During the ad libitum meal phase, subjects were fed an ad libitum dinner. During the test meal phase, blood was drawn every 30 minutes for 3 hours. During the ad libitum meal phase, hunger and fullness visual analogue scales were completed. For this analysis, subjects were grouped into the following habitual SSB categories: low SSB (≤1 SSB serv/day), medium SSB (>1 - <2 serv/day), and high SSB (≥2 serv/day). Fiber categories were created based on quartiles of intake. Mixed modeling was used to explore how SSB and fiber categories predicted ghrelin/PYY values and hunger/fullness ratings across time within and between test meals. The following a priori covariates included: sex, ethnicity, age, and obesity status. The low SSB group had higher fullness ratings over the ad libitum meal compared to the high SSB group (β =-0.49, CI=(-0.89, -0.08), p=0.02) and higher ghrelin concentrations than the medium and high SSB group over the test meal phase (β =-1.86, CI=(-2.81, -0.92), p<0.01). Habitual SSB intake appears to play a key role in moderating fullness responses possibly via ghrelin.
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Affiliation(s)
| | - Gillian A O'Reilly
- Center for Economic and Social Research, University of Southern California, USA
| | - Britini R Belcher
- Risk Factor Monitoring and Methods Branch, Applied Research Program, National Cancer Institute, Bethesda, MD, USA
| | - Michael J Daniels
- Department of Statistics and Computation, University of Texas, Austin, TX, USA
| | - Michael I Goran
- Institute for Prevention Research, Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Donna Spruijt-Metz
- Center for Economic and Social Research, University of Southern California, USA
| | - Jaimie N Davis
- Department of Nutrition, University of Texas, Austin, TX, USA.
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Abstract
The hyperphagia, low sympathetic nervous system tone, and decreased circulating concentrations of bioactive thyroid hormones that are common to states of congenital leptin deficiency and hypoleptinemia following and during weight loss suggest that the major physiological function of leptin is to signal states of negative energy balance and decreased energy stores. In weight-reduced humans, these phenotypes together with pronounced hypometabolism and increased parasympathetic nervous system tone create the optimal circumstance for weight regain. Based on the weight loss induced by leptin administration in states of leptin deficiency (obese) and observed similarity of phenotypes in states of congenital and dietary-induced states of hypoleptinemia (reduced obese), it has been suggested that exogenous leptin could potentially be useful in initiating, promoting, and sustaining weight reduction. However, the responses of human beings to exogenous leptin administration are dependent not only on extant energy stores but also on energy balance. Leptin administration to humans at usual weight has little, if any, effect on body weight while leptin administration during weight loss mitigates hunger, especially if given in supraphysiological doses during severe caloric restriction. Leptin repletion is most effective following weight loss by dietary restriction. In this state of weight stability but reduced energy stores, leptin at least partially reverses many of the metabolic, autonomic, neuroendocrine, and behavioral adaptations that favor weight regain. The major physiological function of leptin is to signal states of negative energy balance and decreased energy stores. Leptin, and pharmacotherapies affecting leptin signaling pathways, is likely to be most useful in sustaining weight loss.
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Affiliation(s)
- Michael Rosenbaum
- Division of Molecular GeneticsDepartments of Pediatrics and Medicine, College of Physicians and Surgeons, Columbia University, Russ Berrie Medical Science Pavilion, 6th Floor, 1150 St Nicholas Avenue, New York, New York 10032, USA
| | - Rudolph L Leibel
- Division of Molecular GeneticsDepartments of Pediatrics and Medicine, College of Physicians and Surgeons, Columbia University, Russ Berrie Medical Science Pavilion, 6th Floor, 1150 St Nicholas Avenue, New York, New York 10032, USA
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10
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Wagener EM, Aurich M, Aparicio-Siegmund S, Floss DM, Garbers C, Breusing K, Rabe B, Schwanbeck R, Grötzinger J, Rose-John S, Scheller J. The amino acid exchange R28E in ciliary neurotrophic factor (CNTF) abrogates interleukin-6 receptor-dependent but retains CNTF receptor-dependent signaling via glycoprotein 130 (gp130)/leukemia inhibitory factor receptor (LIFR). J Biol Chem 2014; 289:18442-50. [PMID: 24802752 DOI: 10.1074/jbc.m114.568857] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ciliary neurotrophic factor (CNTF) is a neurotrophic factor with therapeutic potential for neurodegenerative diseases. Moreover, therapeutic application of CNTF reduced body weight in mice and humans. CNTF binds to high or low affinity receptor complexes consisting of CNTFR·gp130·LIFR or IL-6R·gp130·LIFR, respectively. Clinical studies of the CNTF derivative Axokine revealed intolerance at higher concentrations, which may rely on the low-affinity binding of CNTF to the IL-6R. Here, we aimed to generate a CNTFR-selective CNTF variant (CV). CV-1 contained the single amino acid exchange R28E. Arg(28) is in close proximity to the CNTFR binding site. Using molecular modeling, we hypothesized that Arg(28) might contribute to IL-6R/CNTFR plasticity of CNTF. CV-2 to CV-5 were generated by transferring parts of the CNTFR-binding site from cardiotrophin-like cytokine to CNTF. Cardiotrophin-like cytokine selectively signals via the CNTFR·gp130·LIFR complex, albeit with a much lower affinity compared with CNTF. As shown by immunoprecipitation, all CNTF variants retained the ability to bind to CNTFR. CV-1, CV-2, and CV-5, however, lost the ability to bind to IL-6R. Although all variants induced cytokine-dependent cellular proliferation and STAT3 phosphorylation via CNTFR·gp130·LIFR, only CV-3 induced STAT3 phosphorylation via IL-6R·gp130·LIFR. Quantification of CNTF-dependent proliferation of CNTFR·gp130·LIFR expressing cells indicated that only CV-1 was as biologically active as CNTF. Thus, the CNTFR-selective CV-1 will allow discriminating between CNTFR- and IL-6R-mediated effects in vivo.
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Affiliation(s)
- Eva-Maria Wagener
- From the Institute of Biochemistry, Medical Faculty, Christian-Albrechts-University, 24098 Kiel, Germany and
| | - Matthias Aurich
- From the Institute of Biochemistry, Medical Faculty, Christian-Albrechts-University, 24098 Kiel, Germany and
| | - Samadhi Aparicio-Siegmund
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Doreen M Floss
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Christoph Garbers
- From the Institute of Biochemistry, Medical Faculty, Christian-Albrechts-University, 24098 Kiel, Germany and
| | - Kati Breusing
- From the Institute of Biochemistry, Medical Faculty, Christian-Albrechts-University, 24098 Kiel, Germany and
| | - Björn Rabe
- From the Institute of Biochemistry, Medical Faculty, Christian-Albrechts-University, 24098 Kiel, Germany and
| | - Ralf Schwanbeck
- From the Institute of Biochemistry, Medical Faculty, Christian-Albrechts-University, 24098 Kiel, Germany and
| | - Joachim Grötzinger
- From the Institute of Biochemistry, Medical Faculty, Christian-Albrechts-University, 24098 Kiel, Germany and
| | - Stefan Rose-John
- From the Institute of Biochemistry, Medical Faculty, Christian-Albrechts-University, 24098 Kiel, Germany and
| | - Jürgen Scheller
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany
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11
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Cheng MF. Hypothalamic neurogenesis in the adult brain. Front Neuroendocrinol 2013; 34:167-78. [PMID: 23684668 DOI: 10.1016/j.yfrne.2013.05.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 04/30/2013] [Accepted: 05/03/2013] [Indexed: 12/19/2022]
Abstract
Adult-born new neurons are continuously added to the hippocampus and the olfactory bulb to serve aspects of learning and perceptual functions. Recent evidence establishes a third neurogenic niche in the ventral hypothalamic parenchyma surrounding the third ventricle that ensures the plasticity of specific brain circuits to stabilize physiological functions such as the energy-balance regulatory system. Hypothalamic lesion studies have demonstrated that regions associated with reproduction-related functions are also capable of recruiting newborn neurons to restore physiological functions and courtship behavior. Induced by lesion or other stimulation, elevated neurotrophic factors trigger neurogenic cascades that contribute to remodeling of certain neural circuits to meet specific transient functions. This insight raises the possibility that event-specific changes, such as increased GnRH, may be mediated by courtship-sensitive neurotrophic factors. We will discuss the potentially integral and ubiquitous roles of neurogenesis in physiological and biological phenomena, roles that await future experimental exploration.
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Affiliation(s)
- Mei-Fang Cheng
- Department of Psychology, Rutgers University, 101 Warren Street, Newark, NJ, USA.
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12
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Krishnan S, Newman JW, Hembrooke TA, Keim NL. Variation in metabolic responses to meal challenges differing in glycemic index in healthy women: Is it meaningful? Nutr Metab (Lond) 2012; 9:26. [PMID: 22458475 PMCID: PMC3352098 DOI: 10.1186/1743-7075-9-26] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 03/29/2012] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Established clinical tests are commonly used in disease diagnosis, but tools that enhance identification of metabolic dysfunctions are needed. This study was conducted to identify typical and atypical metabolite temporal patterns in response to paired meal challenge tests. DESIGN Metabolic responses to high and low glycemic index (GI) meals were tested in 24 healthy pre-menopausal women, aged 20-50 y, with BMI of 25-30 kg/m2 using a cross-over design. On test days, blood glucose, insulin, leptin and non-esterified fatty acids were measured after an overnight fasting, and for 8 h following test meal consumption. The data were range scaled, and multivariate statistics were used to assess the presence of distinct response groups to the meal challenge tests. RESULTS As expected, participants showed higher circulating glucose and insulin in response to the high GI compared to the low GI meal challenge. However, using range-scaling and Principal Component Analysis, three distinct groups were identified based on differential responses to the paired challenges. Members of the most populated group (n = 18) displayed little deviation from the expected response to the two meal challenges. Two minor groups (n = 3/group) with distinct responses were observed, one suggestive of sub-clinical insulin resistance, and the other suggestive of hyperleptinemia. CONCLUSIONS The differential responses of glucose, insulin and leptin to low and high glycemic test meals revealed three response groups. Dietary intervention studies traditionally evaluate group responses, and aim to identify the overall effect in the population studied. In contrast, our study analyzed the variance in the meal challenge responses, using an integrated physiological approach, rather than a reductionist approach. This phenotyping approach may be useful for detecting subclinical metabolic dysfunctions, and it could contribute to improved personalized nutrition management. This study is registered in ClinicalTrials.gov, record #200210295.
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Affiliation(s)
- Sridevi Krishnan
- Department of Nutrition, University of California, Davis, CA, USA
| | - John W Newman
- Department of Nutrition, University of California, Davis, CA, USA
- USDA, Agricultural Research Service, Western Human Nutrition Research Center, Obesity and Metabolism Research Unit, Davis, CA, USA
| | - Tara A Hembrooke
- Department of Nutrition, University of California, Davis, CA, USA
- Platinum Performance Inc, Buellton, CA, USA
| | - Nancy L Keim
- Department of Nutrition, University of California, Davis, CA, USA
- USDA, Agricultural Research Service, Western Human Nutrition Research Center, Obesity and Metabolism Research Unit, Davis, CA, USA
- USDA, ARS, Western Human Nutrition Research Center, 430 W. Health Sciences Drive, Davis, CA 95616, USA
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Engineer DR, Garcia JM. Leptin in anorexia and cachexia syndrome. INTERNATIONAL JOURNAL OF PEPTIDES 2012; 2012:287457. [PMID: 22518191 PMCID: PMC3303568 DOI: 10.1155/2012/287457] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 10/25/2011] [Accepted: 10/28/2011] [Indexed: 12/31/2022]
Abstract
Leptin is a product of the obese (OB) gene secreted by adipocytes in proportion to fat mass. It decreases food intake and increases energy expenditure by affecting the balance between orexigenic and anorexigenic hypothalamic pathways. Low leptin levels are responsible for the compensatory increase in appetite and body weight and decreased energy expenditure (EE) following caloric deprivation. The anorexia-cachexia syndrome is a complication of many chronic conditions including cancer, chronic obstructive pulmonary disease, congestive heart failure, chronic kidney disease, and aging, where the decrease in body weight and food intake is not followed by a compensatory increase in appetite or decreased EE. Crosstalk between leptin and inflammatory signaling known to be activated in these conditions may be responsible for this paradox. This manuscript will review the evidence and potential mechanisms mediating changes in the leptin pathway in the setting of anorexia and cachexia associated with chronic diseases.
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Affiliation(s)
- Diana R. Engineer
- Division of Diabetes, Endocrinology and Metabolism, Michael E DeBakey Veterans Affairs Medical Center, Houston, TX 77030, USA
- Baylor College of Medicine, 2002 Holcombe Boulevored, Building 109, Room 210, Houston, TX 77030, USA
- Division of Diabetes, Department of Medicine, Endocrinology and Metabolism, St Luke's Episcopal Hospital, Houston, TX 77030, USA
| | - Jose M. Garcia
- Division of Diabetes, Endocrinology and Metabolism, Michael E DeBakey Veterans Affairs Medical Center, Houston, TX 77030, USA
- Baylor College of Medicine, 2002 Holcombe Boulevored, Building 109, Room 210, Houston, TX 77030, USA
- Huffington Center of Aging, Baylor College of Medicine, Houston, TX 77030, USA
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Wang Y, Asakawa A, Inui A, Kosai KI. Leptin gene therapy in the fight against diabetes. Expert Opin Biol Ther 2011; 10:1405-14. [PMID: 20690892 DOI: 10.1517/14712598.2010.512286] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
IMPORTANCE OF THE FIELD The incidence of diabetes is increasing worldwide, yet current treatments are not always effective for all patient or disease types. AREAS COVERED IN THIS REVIEW Here, we summarize the biologic and clinical roles of leptin in diabetes, and discuss candidate viral vectors that may be employed in the clinical use of central leptin gene therapy for diabetes. WHAT THE READER WILL GAIN We discuss how studies on leptin, a regulator of the insulin-glucose axis, have significantly advanced our understanding of the roles of energy homeostasis and insulin resistance in the pathogeneses of metabolic syndrome and diabetes. Recent studies have demonstrated the long-term therapeutic effects of central leptin gene therapy in obesity and diabetes via decreased insulin resistance and increased glucose metabolism. Many of these studies have employed viral vectors, which afford high in vivo gene transduction efficiencies compared with non-viral vectors. TAKE HOME MESSAGE Adeno-associated viral vectors are particularly well suited for central leptin gene therapy owing to their low toxicity and ability to drive transgene expression for extended periods.
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Affiliation(s)
- Yuqing Wang
- Kagoshima University Graduate School of Medical and Dental Sciences, Department of Gene Therapy and Regenerative Medicine, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan
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Kalra SP. Pivotal role of leptin-hypothalamus signaling in the etiology of diabetes uncovered by gene therapy: a new therapeutic intervention? Gene Ther 2011; 18:319-25. [PMID: 21209624 DOI: 10.1038/gt.2010.164] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The incidence of diabetes mellitus has soared to epidemic proportion worldwide. The debilitating chronic hyperglycemia is caused by either lack of insulin as in diabetes type 1 or its ineffectiveness as in diabetes type 2. Frequent replacement of insulin with or without insulin analogs for optimum glycemic control are the conventional cumbersome therapies. Recent application of leptin gene transfer technology has uncovered the participation of adipocytes-derived leptin-dependent hypothalamic neural signaling in glucose homeostasis and demonstrated that a breakdown in this communication due to leptin insufficiency in the hypothalamus underlies the etiology of chronic hyperglycemia. Reinstatement of central leptin sufficiency by hyperleptinemia produced either by intravenous leptin infusion or a single systemic injection of recombinant adenovirus vector encoding leptin gene suppressed hyperglycemia and evoked euglycemia only transiently in rodent models of diabetes type 1. In contrast, stable restoration of leptin sufficiency, solely in the hypothalamus, with biologically active leptin transduced by an intracerebroventicular injection of recombinant adeno-associated virus vector encoding leptin gene (rAAV-lep) abolished hyperglycemia and imposed euglycemia through the extended duration of experiment by stimulating glucose disposal in the periphery in models of diabetes type 1. Further, similar hypothalamic leptin transgene expression abrogated chronic hyperglycemia and hyperinsulinemia, the predisposing risk factors of the age and environmentally acquired diabetes type 2, and instituted euglycemia by independently activating relays that stimulate glucose metabolism and repress hyperinsulinemia and improve insulin sensitivity in the periphery. Consequently, this durable antidiabetic efficacy of one time rAAV-lep neurotherapy offers a potential novel substitute for insulin therapy following preclinical trials in subhuman primates and humans.
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Affiliation(s)
- S P Kalra
- Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610-0244, USA.
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Neuroendocrine Control of Energy Homeostasis: Update on New Insights. PROGRESS IN BRAIN RESEARCH 2010; 181:17-33. [DOI: 10.1016/s0079-6123(08)81002-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Kalra SP. Central leptin gene therapy ameliorates diabetes type 1 and 2 through two independent hypothalamic relays; a benefit beyond weight and appetite regulation. Peptides 2009; 30:1957-63. [PMID: 19647774 PMCID: PMC2755606 DOI: 10.1016/j.peptides.2009.07.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 07/22/2009] [Accepted: 07/23/2009] [Indexed: 01/12/2023]
Abstract
Although its role in energy homeostasis is firmly established, the evidence accumulated over a decade linking the adipocyte leptin-hypothalamus axis in the pathogenesis of diabetes mellitus has received little attention in the contemporary thinking. In this context various lines of evidence are collated here to show that (1) under the direction of leptin two independent relays emanating from the hypothalamus restrain insulin secretion from the pancreas and mobilize peripheral organs--liver, skeletal muscle and brown adipose tissue--to upregulate glucose disposal, and (2), leptin insufficiency in the hypothalamus produced by either leptinopenia or restriction of leptin transport across the blood brain barrier due to hyperleptinemia of obesity and aging, initiate antecedent pathophysiological sequalae of diabetes type 1 and 2. Further, we document here the efficacy of leptin replenishment in vivo, especially by supplying it to the hypothalamus with the aid of gene therapy, in preventing the antecedent pathophysiological sequalae--hyperinsulinemia, insulin resistance and hyperglycemia--in various animal models and clinical paradigms of diabetes type 1 and 2 with or without attendant obesity. Overall, the new insights on the long-lasting antidiabetic potential of two independent hypothalamic relays engendered by central leptin gene therapy and the preclinical safety indicators in rodents warrant further validation in subhuman primates and humans.
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Affiliation(s)
- Satya P Kalra
- Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, PO Box 100244, Gainesville, FL 32610-0244, United States.
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Abstract
There is increasing evidence of a causal relationship between sleep-disordered breathing and metabolic dysfunction. Metabolic syndrome (MetS), a cluster of risk factors that promote atherosclerotic cardiovascular disease, comprises central obesity, insulin resistance, glucose intolerance, dyslipidemia, and hypertension, manifestations of altered total body energy regulation. Excess caloric intake is indisputably the key driver of MetS, but other environmental and genetic factors likely play a role; in particular, obstructive sleep apnea (OSA), characterized by intermittent hypoxia (IH), may induce or exacerbate various aspects of MetS. Clinical studies show that OSA can affect glucose metabolism, cholesterol, inflammatory markers, and nonalcoholic fatty liver disease. Animal models of OSA enable scientists to circumvent confounders such as obesity in clinical studies. In the most widely used model, which involves exposing rodents to IH during their sleep phase, the IH alters circadian glucose homeostasis, impairs muscle carbohydrate uptake, induces hyperlipidemia, and upregulates cholesterol synthesis enzymes. Complicating factors such as obesity or a high-fat diet lead to progressive insulin resistance and liver inflammation, respectively. Mechanisms for these effects are not yet fully understood, but are likely related to energy-conserving adaptations to hypoxia, which is a strong catabolic stressor. Finally, IH may contribute to the morbidity of MetS by inducing inflammation and oxidative stress. Identification of OSA as a potential causative factor in MetS would have immense clinical impact and could improve the management and understanding of both disorders.
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Affiliation(s)
- Jonathan Jun
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
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CNTF: a target therapeutic for obesity-related metabolic disease? J Mol Med (Berl) 2008; 86:353-61. [DOI: 10.1007/s00109-007-0286-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Revised: 10/09/2007] [Accepted: 10/24/2007] [Indexed: 02/06/2023]
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Central leptin insufficiency syndrome: an interactive etiology for obesity, metabolic and neural diseases and for designing new therapeutic interventions. Peptides 2007; 29:127-38. [PMID: 18053615 DOI: 10.1016/j.peptides.2007.10.017] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Revised: 10/17/2007] [Accepted: 10/18/2007] [Indexed: 01/10/2023]
Abstract
This review critically reappraises recent scientific evidence concerning central leptin insufficiency versus leptin resistance formulations to explain metabolic and neural disorders resulting from subnormal or defective leptin signaling in various sites in the brain. Research at various fronts to unravel the complexities of the neurobiology of leptin is surveyed to provide a comprehensive account of the neural and metabolic effects of environmentally imposed fluctuations in leptin availability at brain sites and the outcome of newer technology to restore leptin signaling in a site-specific manner. The cumulative new knowledge favors a unified central leptin insufficiency syndrome over the, in vogue, central resistance hypothesis to explain the global adverse impact of deficient leptin signaling in the brain. Furthermore, the leptin insufficiency syndrome delineates a novel role of leptin in the hypothalamus in restraining rhythmic pancreatic insulin secretion while concomitantly enhancing glucose metabolism and non-shivering thermogenic energy expenditure, sequelae that would otherwise promote fat accrual to store excess energy resulting from consumption of energy-enriched diets. A concerted effort should now focus on development of newer technologies for delivery of leptin or leptin mimetics to specifically target neural pathways for remediation of diverse ailments encompassing the central leptin insufficiency syndrome.
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Abstract
A identificação da leptina, hormônio secretado pelos adipócitos, cujo efeito sobre o sistema nervoso simpático e a função endócrina confere participação ativa no controle do dispêndio energético, bem como do apetite, acrescentou às funções do tecido adiposo no organismo humano o papel de órgão multifuncional, produtor e secretor de inúmeros peptídeos e proteínas bioativas, denominadas adipocitocinas. Alterações na quantidade de tecido adiposo, como ocorrem na obesidade, afetam a produção da maioria desses fatores secretados pelos adipócitos. Ainda que essas alterações estejam freqüentemente associadas às inúmeras disfunções metabólicas e ao aumento do risco de doenças cardiovasculares, permanece sob investigação o envolvimento do tecido adiposo no desenvolvimento dessas complicações, considerada a sua função endócrina. As concentrações de várias adipocitocinas elevam-se na obesidade e têm sido relacionadas à hipertensão (angiotensinogênio), ao prejuízo da fibrinólise (inibidor do ativador de plasminogênio-1) e à resistência à insulina (proteína estimuladora de acilação, fator de necrose tumoral-alfa, interleucina-6 e resistina). De outro modo, leptina e adiponectina têm efeitos sobre a sensibilidade à insulina. Na obesidade, a resistência insulínica também está relacionada à resistência à leptina e aos teores plasmáticos reduzidos de adiponectina. Leptina e adiponectina ainda exercem efeitos orgânicos adicionais distintos: frente à participação da leptina no controle da ingestão alimentar, a adiponectina apresenta potente ação anti-aterogênica. Algumas drogas utilizadas no controle do diabetes elevam a produção endógena de adiponectina, em roedores e humanos, indicando que o desenvolvimento de novos medicamentos com alvo nas adipocitocinas pode representar uma alternativa terapêutica de prevenção da resistência insulínica e da aterosclerose em indivíduos obesos.
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Abstract
Obesity and its related cluster of pathophysiologic conditions including insulin resistance, glucose intolerance, dyslipidemia, and hypertension are recognized as growing threats to world health. It is now estimated that 10% of the world's population is overweight or obese. As a result, new therapeutic options for the treatment of obesity are clearly warranted. Recent research has focused on the role that gp130 receptor ligands may play as potential therapeutic targets in obesity. One cytokine in particular, ciliary neurotrophic factor (CNTF), acts both centrally and peripherally and mimics the biologic actions of the appetite control hormone leptin, but unlike leptin, CNTF appears to be effective in obesity and as such may have therapeutic potential. In addition, CNTF suppresses inflammatory signaling cascades associated with lipid accumulation in liver and skeletal muscle. This review examines the potential role of gp130 receptor ligands as part of a therapeutic strategy to treat obesity.
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Affiliation(s)
- Mark A Febbraio
- Cellular and Molecular Metabolism Laboratory, Division of Diabetes and Metabolism, Baker Heart Research Institute, Melbourne, Victoria, Australia.
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Kalra SP, Kalra PS. To subjugate NPY is to improve the quality of life and live longer. Peptides 2007; 28:413-8. [PMID: 17215061 PMCID: PMC1839846 DOI: 10.1016/j.peptides.2006.08.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Accepted: 08/09/2006] [Indexed: 10/23/2022]
Abstract
The interactive network of neuropeptide Y (NPY) and cohorts is necessary for integrating the hypothalamic regulation of appetite and energy expenditure with the endocrine and neuroendocrine systems on a daily basis. Genetic and environmental factors that produce an insufficiency of leptin restraint on NPY and cognate receptors deregulate the homeostasis to engender various life-threatening risk factors. Recent studies from our laboratory show that neurotherapy consisting of a single central administration of recombinant adeno-associated virus vector encoding the leptin gene can repress the hypothalamic NPY system for the lifetime of rodents. A major benefit of this stable tonic restraint is deceleration of pathophysiologic sequalae that shorten life span. These include suppression of weight gain, fat accumulation, circulating adipokines, amelioration of major symptoms of metabolic syndrome, improved reproduction and bone health. Thus, sustained repression of NPY signaling in the hypothalamus by leptin transgene expression can improve the quality of life and extend longevity.
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Affiliation(s)
- Satya P Kalra
- Department of Neuroscience, McKnight Brain Institute, University of Florida, PO Box 100244, Gainesville, FL 32610-0244, USA.
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Ambati S, Duan J, Duff E, Choi YH, Hartzell DL, Della-Fera MA, Baile CA. Gene expression in arcuate nucleus-median eminence of rats treated with leptin or ciliary neurotrophic factor. Biofactors 2007; 31:133-44. [PMID: 18806317 DOI: 10.1002/biof.5520310204] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ciliary neurotrophic factor (CNTF) and leptin are cytokine-like% hormones and act on their corresponding receptors in the hypothalamic arcuate nucleus (ARC). The present study was designed to assess effects of intracerebroventricular (ICV) injection of leptin and CNTF on gene expression in micropunched hypothalamic arcuate nucleus-median eminence (ARC-ME) complex samples from rats. Male Sprague Dawley rats were implanted with lateral cerebroventricular cannulas for administration of control, 10 microg/d leptin or 5 microg/d CNTF for four days. Real-time Taqmantrade mark RT-PCR was used to quantitatively compare the mRNA levels of selected genes in the ARC-ME complex. Leptin and CNTF increased ARC-ME mRNA levels of signal transducer and activator of transcription 3 (STAT3) by 64.5 and 124.7% (p<0.01), suppressor of cytokine signaling 3 (SOCS3) by 258.9 and 1063.9% (p<0.01), cocaine and amphetamine regulated transcript (CART) by 102.7 and 123.1% (p<0.01), and proopiomelanocortin (POMC2) by 374.1 and 264.9% (p<0.01), respectively. Leptin increased growth hormone releasing hormone (GHRH) by 309.9% (p<0.01), while CNTF increased janus kinase 2 (JAK2) mRNA by 31.7% (p<0.01) and decreased gonadotropin releasing hormone 1 (GNRH1) by 59.7% (p<0.01), mitogen activated protein kinase 1 (MAPK1) by 19.4% (p<0.05) and tyrosine hydroxylase (TH) by 74.5% (p<0.05). Significant reduction in daily food intake and body weights by both the treatments was observed. Also, decrease in weights of fat pads was concomitant with lowered serum insulin and leptin levels. Our findings show that leptin and CNTF engage both convergent and divergent pathways involved in feeding, cellular signaling, inflammation, and other related regulatory systems.
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Affiliation(s)
- Suresh Ambati
- Department of Animal and Dairy Science, University of Georgia, Athens, GA 30602-2771, USA
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Torto R, Boghossian S, Dube MG, Kalra PS, Kalra SP. Central leptin gene therapy blocks ovariectomy-induced adiposity. Obesity (Silver Spring) 2006; 14:1312-9. [PMID: 16988073 DOI: 10.1038/oby.2006.149] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE In this study, we tested the hypothesis that insufficiency of leptin restraint in the hypothalamus is responsible for promoting weight gain and adiposity after ovariectomy (ovx). Whether increasing leptin transgene expression can overcome the diminution in leptin restraint was evaluated in ovx rats. RESEARCH METHODS AND PROCEDURES Enhanced leptin or green fluorescent protein (GFP; control) transgene expression was induced by a single intracerebroventricular injection of recombinant adeno-associated viral vector encoding either leptin gene (rAAV-lep) or GFP gene (rAAV-GFP; control) in acutely and chronically ovx rats. Body weight and food intake responses were monitored weekly. White adipose tissue (WAT) mass and serum levels of WAT-derived hormones, leptin, and adiponectin were analyzed at termination of the experiments. RESULTS AND DISCUSSION An increase in leptin transgene expression in the hypothalamus initiated soon after ovx blocked hyperphagia and body weight gain and markedly suppressed WAT mass and adipokines, leptin, and adiponectin. Similar suppression of weight gain and adiposity and serum leptin and adiponectin levels after intracerebroventricular rAAV-lep injection in chronically ovx rats were observed concomitant with unchanged daily food intake. These findings are consistent with the hypothesis that in the absence of ovarian steroids, the existent insufficiency of leptin restraint at the hypothalamic level can be overcome with ectopic leptin expression, thereby reinstating central control on weight and adiposity.
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Affiliation(s)
- Rita Torto
- Departments of Physiology, University of Florida McKnight Brain Institute, P.O. Box 100244, Gainesville, FL 32610-0244, USA
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Kalra SP, Kalra PS. Subjugation of hypothalamic NPY and cohorts with central leptin gene therapy alleviates dyslipidemia, insulin resistance, and obesity for life-time. EXS 2006:157-69. [PMID: 16383005 DOI: 10.1007/3-7643-7417-9_12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
An interactive network comprised of neuropeptide Y (NPY) and cohorts is obligatory in the hypothalamic integration of appetite and energy expenditure on a minute-to-minute basis. High or low abundance of NPY and cognate receptors dysregulates the homeostatic milieu engendering hyperphagia, decreased energy expenditure, obesity and attendant metabolic syndrome cluster of dyslipidemia, glucose intolerance, insulin resistance and hyperinsulinemia, risk factors for type II diabetes and cardiovascular diseases. Increasing the supply of the endogenous repressor hormone leptin locally in the hypothalamus with the aid of leptin gene therapy, blocked age-related and dietary obesities, and the sequential development of dyslipidemia, hyperglycemia, and insulin resistance. Thus, sustained repression of NPY signaling with increased leptin selectively in the hypothalamus can avert environmental obesity and the risks of metabolic diseases.
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Affiliation(s)
- Satya P Kalra
- University of Florida McKnight Brain Institute, Department of Neuroscience, PO Box 100244, Gainesville, Florida 32610-0244, USA.
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Kalra SP, Kalra PS. Gene-transfer technology: a preventive neurotherapy to curb obesity, ameliorate metabolic syndrome and extend life expectancy. Trends Pharmacol Sci 2005; 26:488-95. [PMID: 16125798 DOI: 10.1016/j.tips.2005.08.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 07/25/2005] [Accepted: 08/12/2005] [Indexed: 11/29/2022]
Abstract
Leptin insufficiency at crucial target sites in the hypothalamic circuitries that integrate energy intake and expenditure underlies abnormal rates of fat accumulation. The payload of this "fat burden" is metabolic syndrome, a cluster of life-threatening metabolic afflictions, and a shorter lifespan. Currently available therapies employed to combat obesity have disadvantages such as poor compliance for lifestyle modification or transient effectiveness and undesirable side-effects of pharmacological interventions. Recent studies suggest that neurotherapy comprising a single central administration of recombinant adeno-associated virus vector encoding the leptin gene severely depletes fat and ameliorates the major symptoms of metabolic syndrome for extended periods in rodents. These persistent benefits avert the deleterious impact of the "fat burden" and extend life expectancy. Thus, the novel approach of central gene-transfer technology has distinct advantages over current therapies and has the potential to correct or slow the progression of inherited or acquired hypothalamic diseases.
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Affiliation(s)
- Satya P Kalra
- Department of Neuroscience, College of Medicine, University of Florida McKnight Brain Institute, Gainesville, FL 32610, USA.
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Król E, Duncan JS, Redman P, Morgan PJ, Mercer JG, Speakman JR. Photoperiod regulates leptin sensitivity in field voles, Microtus agrestis. J Comp Physiol B 2005; 176:153-63. [PMID: 16402185 DOI: 10.1007/s00360-005-0037-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Revised: 09/07/2005] [Accepted: 09/27/2005] [Indexed: 10/25/2022]
Abstract
We have previously shown that cold-acclimated (8 degrees C) male field voles (Microtus agrestis) transferred from short (SD, 8:16 h L:D) to long photoperiod (LD, 16:8 h L:D) exhibit increases in body mass, adiposity and food intake. To assess whether these increases were associated with decreased leptin sensitivity, we infused LD and SD voles with physiological doses of murine leptin (or saline) delivered peripherally for 7 days via mini-osmotic pumps. Measurements were made of body mass (weight-reducing effect of leptin), food intake (anorectic effect of leptin) and gene expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) (thermogenic effect of leptin). The SD animals were sensitive to the weight-reducing effects of leptin (mean body mass decrease of 1.2 g over 7 days) and appetite-reducing effect of leptin (mean food intake decrease of 2.5 g over 7 days), whereas LD voles were resistant to the hormone treatment. The switch from a leptin-sensitive to leptin-resistant state appears to act as a desensitisation mechanism that allows voles transferred from SD to LD to ignore elevated leptin levels generated by increased body fat and accumulate adipose tissue without stimulating compensatory changes opposing the weight gain. Neither SD nor LD voles responded to infusion of leptin by changes in BAT UCP1 gene expression, suggesting dissociation of anorectic and thermogenic effects of leptin, possibly related to chronic cold exposure. Our results indicate that cold-acclimated voles show photoperiod-regulated changes in leptin sensitivity and may provide an attractive model for elucidating molecular mechanisms of leptin resistance.
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Affiliation(s)
- E Król
- Aberdeen Centre for Energy Regulation and Obesity, School of Biological Sciences, University of Aberdeen, Zoology Building, Aberdeen, AB24 2TZ, UK.
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Abstract
Unexpended energy is stored as fat in the body and increased rate of fat accretion culminates in obesity. Obesity increases the risks of many diseases several folds and shortens life span. A progressive deficit in the central feedback effects of leptin, a peptide produced by fat cells and hypothalamus, results in increased weight gain and obesity. This article summarizes our experimental findings to show that a stable increase in leptin availability in the hypothalamus alone with the aid of leptin gene therapy suppresses fat accretion and metabolic hormones for nearly the lifetime of laboratory rodents. Consequently, central leptin gene therapy is a novel modality that offers a viable therapeutic option to reduce fat depots and attendant metabolic sequelae implicated in obesity-related illnesses.
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Affiliation(s)
- Stéphane Boghossian
- Department of Neuroscience, University of Florida McKnight Brain Institute, College of Medicine, PO Box 100244, Gainesville, FL 32610-0244, USA
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30
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Kalra SP, Kalra PS. NPY and cohorts in regulating appetite, obesity and metabolic syndrome: beneficial effects of gene therapy. Neuropeptides 2004; 38:201-11. [PMID: 15337372 DOI: 10.1016/j.npep.2004.06.003] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Accepted: 06/04/2004] [Indexed: 11/16/2022]
Abstract
Neuropeptide Y is the most potent physiological appetite transducer known. The NPY network is the conductor of the hypothalamic appetite regulating orchestra in the arcuate nucleus-paraventricular nucleus (ARC-PVN) of the hypothalamus. NPY and cohorts, AgrP, GABA and adrenergic transmitters, initiate appetitive drive directly through Y1, Y5, GABAA and alpha1 receptors, co-expressed in the magnocellular PVN (mPVN) and ARC neurons and by simultaneously repressing anorexigenic melanocortin signaling in the ARC-PVN axis. The circadian and ultradian rhythmicities in NPY secretion imprint the daily circadian and episodic feeding patterns. Although a number of afferent hormonal signals from the periphery can directly modulate NPYergic signaling, the reciprocal circadian and ultradian rhythmicities of anorexigenic leptin from adipocytes and orexigenic ghrelin from stomach, encode a corresponding pattern of NPY discharge for daily meal patterning. Subtle and progressive derangements produced by environmental and genetic factors in this exquisitely intricate temporal relationship between the two opposing humoral signals and the NPY network promote hyperphagia and abnormal rate of weight gain culminating in obesity and attendant metabolic disorders. Newer insights at cellular and molecular levels demonstrate that a breakdown of the integrated circuit due both to high and low abundance of NPY at target sites, underlies hyperphagia and increased adiposity. Consequently, interruption of NPYergic signaling at a single locus with NPY receptor antagonists may not be the most efficacious therapy to suppress hyperphagia and obesity. Central leptin gene therapy in rodents has been shown to subjugate, i.e. bring under homeostatic control, NPYergic signaling and suppress the age-related and dietary obesity for extended periods and thus shows promise as a newer treatment modality to curb the pandemic of obesity and metabolic syndrome.
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Affiliation(s)
- S P Kalra
- Department of Neuroscience, University of Florida, McKnight Brain Institute, PO Box 100244, Gainesville, FL 32610, USA.
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Abstract
Multidisciplinary research in recent years has delineated the hypothalamic hardcore wiring that encodes appetitive drive. The appetite regulating network (ARN) consisting of distinct orexigenic and anorexigenic circuitries operates in the arcuate nucleus-paraventricular nucleus axis of the hypothalamus to propagate and relay the appetitive drive, and is subject to modulation by excitatory and inhibitory messages from the lateral hypothalamus and ventromedial nucleus, respectively. Reciprocal afferent humoral signals, comprised of anorexigenic leptin from white adipose tissue and orexigenic ghrelin from stomach, to the ARN integrate the moment-to-moment regulation of energy homeostasis. Various loci in the ARN and afferent hormonal feedback circuitry in the rodent brain are important for food craving elicited by drugs of abuse. This convergence of neurochemical and hormonal signaling has now paved the way to address the fundamental question of whether cellular and molecular events that underlie the appetitive drive in response to diminished energy stores in the body are akin to drug craving during withdrawal in humans.
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Affiliation(s)
- Satya P Kalra
- Department of Neuroscience, University of Florida McKnight Brain Institute, PO Box 100244, Gainesville, FL 32610-0244, USA.
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32
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Rodrigues AM, Suplicy HL, Radominski RB. Controle neuroendócrino do peso corporal: implicações na gênese da obesidade. ACTA ACUST UNITED AC 2003. [DOI: 10.1590/s0004-27302003000400012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
O peso corporal é regulado por uma interação complexa entre hormônios e neuropeptídeos, sob o controle principal de núcleos hipotalâmicos. Mutações nos genes de hormônios e neuropeptídeos, de seus receptores ou de elementos regulatórios, têm sido descritas na espécie humana, mas são tidas como raras, não explicando as formas mais comuns de obesidade. No entanto, o estudo destas mutações tem propiciado um grande avanço nos conhecimentos sobre a base genética e a fisiopatologia da obesidade, possibilitando o estudo e abrindo perspectivas para o desenvolvimento de novas modalidades terapêuticas. Recentemente, demonstrou-se que mutações no receptor 4 da melanocortina podiam ser encontradas em até 5% dos casos de obesidade severa, representando até o presente momento a forma mais prevalente de obesidade monogênica na espécie humana. Nesta revisão, são discutidas as diversas mutações descritas nos seres humanos de elementos da rede neuroendócrina de controle do peso corporal, bem como as implicações dos mesmos na gênese da obesidade.
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Anderson KD, Lambert PD, Corcoran TL, Murray JD, Thabet KE, Yancopoulos GD, Wiegand SJ. Activation of the hypothalamic arcuate nucleus predicts the anorectic actions of ciliary neurotrophic factor and leptin in intact and gold thioglucose-lesioned mice. J Neuroendocrinol 2003; 15:649-60. [PMID: 12787049 DOI: 10.1046/j.1365-2826.2003.01043.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Similar to leptin, ciliary neurotrophic factor (CNTF) suppresses appetite and selectively reduces body fat in leptin-deficient ob/ob mice. To assess the relative importance of specific regions of the hypothalamus in mediating these effects, we administered a CNTF analogue (CNTFAx15) or leptin to mice made obese by administration of gold thioglucose (GTG), which destroys a well-defined portion of the medial basal hypothalamus. CNTFAx15 treatment reduced appetite and body weight in obese GTG-lesioned C57BL/6 mice, whereas leptin failed to effect similar changes regardless of whether treatment was initiated before or after the lesioned mice had become obese. Because leptin does not reduce food intake or body weight in most forms of obesity (a condition termed 'leptin resistance'), we also investigated the actions of leptin in GTG-lesioned leptin-deficient (ob/ob) mice. By contrast to C57BL/6 mice, leptin treatment reduced food intake and body weight in GTG-lesioned ob/ob mice, although the effect was attenuated. To further compare the neural substrates mediating the anorectic actions of leptin and CNTF, we determined the patterns of neurone activation induced by these proteins in the hypothalamus of intact and GTG-lesioned mice by staining for phosphorylated signal transducer and activator of transcription 3 (pSTAT3). CNTFAx15 stimulated robust pSTAT3 signalling in neurones of the medial arcuate nucleus in both intact and lesioned C57BL/6 and ob/ob mice. Leptin administration stimulated pSTAT3 signalling in only a few neurones of the medial arcuate nucleus in intact or lesioned C57BL/6 mice, but elicited a robust response in intact or lesioned ob/ob mice. By contrast to CNTFAx15, leptin treatment also resulted in prominent activation of STAT3 in several areas of the hypothalamus outside the medial arcuate nucleus. This leptin-induced pSTAT3 signal was at least as prominent in intact and GTG-lesioned C57BL/6 mice as it was in ob/ob mice, and thus was not correlated with appetite suppression or weight loss. These results indicate that the medial arcuate nucleus is a key mediator of appetite suppression and weight loss produced by CNTF and leptin, whereas GTG-vulnerable regions play a role only in leptin-induced weight loss. Other regions of hypothalamus in which pSTAT3 signal is induced by leptin may regulate energy metabolism through mechanisms other than appetite reduction.
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Affiliation(s)
- K D Anderson
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY10591-6707, USA.
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Kalra SP, Bagnasco M, Otukonyong EE, Dube MG, Kalra PS. Rhythmic, reciprocal ghrelin and leptin signaling: new insight in the development of obesity. REGULATORY PEPTIDES 2003; 111:1-11. [PMID: 12609743 DOI: 10.1016/s0167-0115(02)00305-1] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The hypothalamus integrates metabolic, neural and hormonal signals to evoke an intermittent appetitive drive in the daily management of energy homeostasis. Three major players identified recently in the feedback communication between the periphery and hypothalamus are leptin, ghrelin and neuropeptide Y (NPY). We propose that reciprocal circadian and ultradian rhythmicities in the afferent humoral signals, anorexigenic leptin from adipocytes and orexigenic ghrelin from stomach, encode a corresponding discharge pattern in the appetite-stimulating neuropeptide Y network in the hypothalamus. An exquisitely intricate temporal relationship among these signaling modalities with varied sites of origin is paramount in sustenance of weight control on a daily basis. Our model envisages that subtle and progressive derangements in temporal communication, imposed by environmental shifts in energy intake, impel a positive energy balance culminating in excessive weight gain and obesity. This conceptual advance provides a new target for designing pharmacologic or gene transfer therapies that would normalize the rhythmic patterns of afferent hormonal and efferent neurochemical messages.
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Affiliation(s)
- Satya P Kalra
- Department of Neuroscience, College of Medicine, University of Florida McKnight Brain Institute, PO Box 100244, Gainesville, FL 32610-0244, USA.
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Schuster B, Kovaleva M, Sun Y, Regenhard P, Matthews V, Grötzinger J, Rose-John S, Kallen KJ. Signaling of human ciliary neurotrophic factor (CNTF) revisited. The interleukin-6 receptor can serve as an alpha-receptor for CTNF. J Biol Chem 2003; 278:9528-35. [PMID: 12643274 DOI: 10.1074/jbc.m210044200] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Human ciliary neurotrophic factor (CNTF) is a neurotrophic cytokine that exerts a neuroprotective effect in multiple sclerosis and amyotrophic lateral sclerosis. Clinical application of human CNTF, however, was prevented by high toxicity at higher dosages. Human CNTF elicits cellular responses by induction of a receptor complex consisting of the CNTF alpha-receptor (CNTFR), which is not involved in signal transduction, and the beta-receptors gp130 and leukemia inhibitory factor receptor (LIFR). Previous studies with rat CNTF demonstrated that rat CNTF is unable to interact with the human interleukin-6 alpha-receptor, whereas at high concentrations, it can directly induce a signaling heterodimer of human gp130 and human LIFR in the absence of the CNTF receptor. Here, we demonstrate that human CNTF cannot directly induce a heterodimer of human gp130 and LIFR. However, human CNTF can use both the membrane-bound and the soluble human IL-6R as a substitute for its cognate alpha-receptor and thus widen the target spectrum of human CNTF. Engineering a CNTFR-specific human CNTF variant may therefore be a prerequisite to improving the safety profile of CNTF.
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Affiliation(s)
- Björn Schuster
- Biochemisches Institut, Christian Albrechts Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
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Liu Y, Gold MS. Human Functional Magnetic Resonance Imaging of Eating and Satiety in Eating Disorders and Obesity. Psychiatr Ann 2003. [DOI: 10.3928/0048-5713-20030201-09] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hamerman D. Molecular-based therapeutic approaches in treatment of anorexia of aging and cancer cachexia. J Gerontol A Biol Sci Med Sci 2002; 57:M511-8. [PMID: 12145364 DOI: 10.1093/gerona/57.8.m511] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Loss of appetite, or anorexia, has profound implications for older persons, altering social interactions, reducing quality of life, and leading to weight loss with grave health consequences. Two conditions associated with anorexia considered in this article are the multidetermined anorexia of aging and the wasting syndrome termed cachexia induced by cancer. Nutritional interventions may have some benefit in the former, but are of limited value in the latter. Emerging studies at the molecular level relating to appetite regulation and energy balance may offer new approaches to arrest progressive weight loss in the anorexia of aging and cancer cachexia.
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Affiliation(s)
- David Hamerman
- Resnick Gerontology Center, Department of Medicine, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York 10467, USA.
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Beretta E, Dube MG, Kalra PS, Kalra SP. Long-term suppression of weight gain, adiposity, and serum insulin by central leptin gene therapy in prepubertal rats: effects on serum ghrelin and appetite-regulating genes. Pediatr Res 2002; 52:189-98. [PMID: 12149495 DOI: 10.1203/00006450-200208000-00010] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Intracerebroventricular administration of recombinant adeno-associated virus (rAAV) encoding the rat leptin gene (rAAV-lep) to 24-d-old female and male rats suppressed postpubertal weight gain for extended periods by decreasing food consumption and adiposity, as reflected by lowered serum leptin, insulin, and FFA. Serum ghrelin levels were increased in young but not older rats. Central rAAV-lep therapy also increased energy expenditure through nonshivering thermogenesis in younger rats as shown by expression of uncoupling protein mRNA in brown adipose tissue. The sustained decrease in appetite seemingly resulted from attenuation of appetite-stimulating neuropeptide Y and enhancement of appetite-inhibiting melanocortin signalings in the hypothalamus. Neither the onset of pubertal sexual maturation nor reproductive cyclicity in adult female rats was affected by the sustained reduction in energy consumption and weight gain. These findings demonstrate that central leptin gene therapy in prepubertal rats is a novel therapy to control postpubertal weight gain, adiposity, and hyperinsulinemia for extended periods.
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Affiliation(s)
- Elena Beretta
- Department of Neuroscience, University of Florida McKnight Brain Institute, Gainesville 32610-0244, USA
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Beretta E, Dhillon H, Kalra PS, Kalra SP. Central LIF gene therapy suppresses food intake, body weight, serum leptin and insulin for extended periods. Peptides 2002; 23:975-84. [PMID: 12084530 DOI: 10.1016/s0196-9781(02)00021-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Leukemia inhibitory factor (LIF) overexpression, induced by the intracerebroventricular (i.c.v.) injection of an recombinant adeno-associated viral vector encoding LIF (rAAV-LIF), resulted in a dose-dependent reduction in body weight (BW) gain, food intake (FI) and adiposity, evidenced by suppression of serum leptin and free fatty acids for an extended period in outbred adult female rats. A dose-dependent reduction in serum insulin levels and unchanged serum glucose, energy expenditure through thermogenesis as indicated by uncoupling protein-1 (UCP-1) mRNA expression in brown adipose tissue (BAT), and metabolism as indicated by serum T3 and T4, accompanied the blockade of weight gain. Thus, central rAAV-LIF therapy is a viable strategy to voluntarily reduce appetite and circumvent leptin resistance, a primary factor underlying age-dependent weight gain and obesity in rodents and humans.
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Affiliation(s)
- Elena Beretta
- Department of Neuroscience, College of Medicine, University of Florida McKnight Brain Institute, Gainesville, FL 32610-0244, USA
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Abstract
Over the past several years, the pharmacologic treatment of obesity has undergone changes in safety, efficacy, and therapeutic targeting. The prevalence of cardiac valvulopathy associated with treatment with phentermine, fenfluramine, and dexfenfluramine is now becoming clarified with the publication of longer-term studies. Phenylpropanolamine, a well-known over-the-counter appetite suppressant, was recently removed from the market in the United States because of an increased risk of hemorrhagic stroke in women. In contrast, two currently approved medications, sibutramine and orlistat, have been shown to be safe and moderately effective for weight loss with documented beneficial effects on cardiovascular risk factors. Three other drugs, bupropion, topiramate, and ciliary neurotrophic factor, are undergoing clinical trials for obesity based on empirical observations. Most promising are the advances in genetics and molecular biology that are beginning to elucidate new targets for controlling appetite and energy utilization. These therapeutic agents will likely herald a second generation of anti-obesity medications over the next decade.
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Affiliation(s)
- Robert F Kushner
- Division of General Internal Medicine, Northwestern University Medical School, Chicago, Illinois 60611, USA.
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Shimokawa T, Kumar MV, Lane MD. Effect of a fatty acid synthase inhibitor on food intake and expression of hypothalamic neuropeptides. Proc Natl Acad Sci U S A 2002; 99:66-71. [PMID: 11756683 PMCID: PMC117515 DOI: 10.1073/pnas.012606199] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The fatty acid synthase inhibitor, C75, acts centrally to reduce food intake and body weight in mice. Here we report the effects of C75 on the expression of key orexigenic [neuropeptide Y (NPY), agouti-related protein (AgRP), and melanin-concentrating hormone] and anorexigenic [pro-opiomelanocortin (POMC) and cocaine-amphetamine-related transcript (CART)] neuropeptide messages in the hypothalami of lean and obese (ob/ob) mice. In lean mice, C75 rapidly and almost completely blocked food intake and prevented fasting-induced up-regulation of hypothalamic AgRP and NPY mRNAs, as well as down-regulation of CART and POMC mRNAs. Thus, in lean mice C75 seems to interrupt the fasting-induced signals that activate expression of NPY and AgRP and suppression of POMC and CART. In obese mice, C75 rapidly suppressed food intake, reduced body weight, and normalized obesity-associated hyperglycemia and hyperinsulinemia. Like its effect in lean mice, C75 prevented the fasting-induced increase of hypothalamic NPY and AgRP mRNAs in obese mice, but had no effect on the expression of POMC and CART mRNAs. The suppressive effect of C75 on food intake in lean mice seems to be mediated both by NPY/AgRP and POMC/CART neurons, whereas in obese mice the effect seems to be mediated primarily by NPY/AgRP neurons. In both lean and obese mice, C75 markedly increased expression of melanin-concentrating hormone and its receptor in the hypothalamus.
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Affiliation(s)
- Teruhiko Shimokawa
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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42
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Horvath TL, Diano S, Sotonyi P, Heiman M, Tschöp M. Minireview: ghrelin and the regulation of energy balance--a hypothalamic perspective. Endocrinology 2001; 142:4163-9. [PMID: 11564668 DOI: 10.1210/endo.142.10.8490] [Citation(s) in RCA: 310] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The recently discovered hormone, ghrelin, has been recognized as an important regulator of GH secretion and energy homeostasis. Orexigenic and adipogenic ghrelin is produced by the stomach, intestine, placenta, pituitary, and possibly in the hypothalamus. The concentration of circulating ghrelin, principally derived from the stomach, is influenced by acute and chronic changes in nutritional state. To date, most studies focused on the role of ghrelin in GH secretion or its function in complementing leptin action to prevent energy deficits. The potential significance of ghrelin in the etiology of obesity and cachexia as well as in the regulation of growth processes is the subject of ongoing discussions. A large quantity of information based on clinical trials and experimental studies with ghrelin and previously available synthetic ghrelin receptor agonists (GH secretagogues) must now be integrated with a rapidly increasing amount of data on the central regulation of metabolism and appetite. In this overview, we summarize recent findings and strategies on the integration of ghrelin into neuroendocrine networks that regulate energy homeostasis.
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Affiliation(s)
- T L Horvath
- Reproductive Neuroscience Unit, Department of Obstetrics and Gynecology, Yale Medical School, New Haven, Connecticut 06520, USA.
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Dhillon H, Kalra SP, Kalra PS. Dose-dependent effects of central leptin gene therapy on genes that regulate body weight and appetite in the hypothalamus. Mol Ther 2001; 4:139-45. [PMID: 11482985 DOI: 10.1006/mthe.2001.0427] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We have examined the dose-dependent effects and central action of intraventricular administration of a recombinant adeno-associated virus encoding rat leptin (rAAV-leptin) in suppressing body weight (BW) gain in adult female rats. A low dose of rAAV-leptin (5x10(10) particles) suppressed weight gain (15%) without changing daily food intake (FI), but a twofold higher dose decreased BW by 30% along with a reduction in daily FI. Reduced BW was due to a loss in body adiposity because serum leptin was reduced. Serum insulin levels were decreased (96%) by only the high dose along with a slight reduction in glucose. Uncoupling protein-1 (UCP-1) mRNA expression in brown adipose tissue (BAT), reflecting energy expenditure through thermogenesis, was upregulated to the same magnitude by the two rAAV-leptin doses. We analyzed by in situ hybridization the expression in the hypothalamus of genes encoding the appetite-regulating neuropeptides. Only the high dose decreased expression of neuropeptide Y (NPY), the orexigenic peptide, and increased proopiomelanocortin (POMC), precursor of the an orexigenic peptide, alpha-MSH. Our studies show for the first time that increased availability of leptin within the hypothalamus through central leptin gene therapy dose-dependently decreases weight gain, adiposity, and serum insulin by increasing energy expenditure and decreasing FI. The decrease in FI occurs only when NPY is reduced and alpha-MSH is increased in the hypothalamus by the high dose of rAAV-leptin. Delivery of the leptin gene centrally through rAAV vectors is a viable therapeutic modality for long-term control of weight and metabolic hormones.
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Affiliation(s)
- H Dhillon
- Department of Physiology, University of Florida McKnight Brain Institute, College of Medicine, Gainesville, Florida 32610, USA
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44
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Abstract
The field of neuroimaging has made great progress in the mapping of human brain function. In this article, we present a functional magnetic resonance imaging (fMRI) study on the hypothalamic regulation of satiety and its relationship with obesity. The fMRI techniques have been proven invaluable for analyzing changes in brain activity that are associated with most sensorimotor and cognitive functions. However, few studies have been successful in the delineation of the interaction between the central nervous system and the endocrine system, due to the lack of suitable mapping methods which can pinpoint the onset of changes in neuronal activity (e.g., those following eating or drug intake). We have recently introduced a new fMRI method known as temporal clustering analysis (TCA) for dynamically tracking the time course of brain activation. Along with simultaneous blood sampling for the circulating hormone levels, the fMRI techniques with TCA may provide an integrated view of the nervous and endocrine systems in vivo, and thus greatly enhance our understanding of the complex interplay between neural events and hormonal signals.
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Affiliation(s)
- G A James
- Department of Psychiatry and Neuroscience, McKnight Brain Institute, University of Florida, Gainesville 32610, USA
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