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Boyle CA, Kola PK, Oraegbuna CS, Lei S. Leptin excites basolateral amygdala principal neurons and reduces food intake by LepRb-JAK2-PI3K-dependent depression of GIRK channels. J Cell Physiol 2024; 239:e31117. [PMID: 37683049 PMCID: PMC10920395 DOI: 10.1002/jcp.31117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/08/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023]
Abstract
Leptin is an adipocyte-derived hormone that modulates food intake, energy balance, neuroendocrine status, thermogenesis, and cognition. Whereas a high density of leptin receptors has been detected in the basolateral amygdala (BLA) neurons, the physiological functions of leptin in the BLA have not been determined yet. We found that application of leptin excited BLA principal neurons by activation of the long form leptin receptor, LepRb. The LepRb-elicited excitation of BLA neurons was mediated by depression of the G protein-activated inwardly rectifying potassium (GIRK) channels. Janus Kinase 2 (JAK2) and phosphoinositide 3-kinase (PI3K) were required for leptin-induced excitation of BLA neurons and depression of GIRK channels. Microinjection of leptin into the BLA reduced food intake via activation of LepRb, JAK2, and PI3K. Our results may provide a cellular and molecular mechanism to explain the physiological roles of leptin in vivo.
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Affiliation(s)
- Cody A. Boyle
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND58203, USA
| | - Phani K. Kola
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND58203, USA
| | - Chidiebele S. Oraegbuna
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND58203, USA
| | - Saobo Lei
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND58203, USA
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2
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Tucker JAL, Bornath DPD, McCarthy SF, Hazell TJ. Leptin and energy balance: exploring Leptin's role in the regulation of energy intake and energy expenditure. Nutr Neurosci 2024; 27:87-95. [PMID: 36583502 DOI: 10.1080/1028415x.2022.2161135] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Leptin is a tonic appetite-regulating hormone, which is integral for the long-term regulation of energy balance. The current evidence suggests that the typical orexigenic or anorexigenic response of many of these appetite-regulating hormones, most notably ghrelin and cholecystokinin (CCK), require leptin to function whereas glucagon-like peptide-1 (GLP-1) is required for leptin to function, and these responses are altered when leptin injection or gene therapy is administered in combination with these same hormones or respective agonists. The appetite-regulatory pathway is complex, thus peptide tyrosine tyrosine (PYY), brain-derived neurotrophic factor (BDNF), orexin-A (OXA), and amylin also maintain ties to leptin, however these are less well understood. While reviews to date have focused on the existing relationships between leptin and the various neuropeptide modulators of appetite within the central nervous system (CNS) or it's role in thermogenesis, no review paper has synthesised the information regarding the interactions between appetite-regulating hormones and how leptin as a chronic regulator of energy balance can influence the acute appetite-regulatory response. Current evidence suggests that potential relationships exist between leptin and the circulating peripheral appetite hormones ghrelin, GLP-1, CCK, OXA and amylin to exhibit either synergistic or opposing effects on appetite inhibition. Though more research is warranted, leptin appears to be integral in both energy intake and energy expenditure. More specifically, functional leptin receptors appear to play an essential role in these processes.
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Affiliation(s)
- Jessica A L Tucker
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, Canada
| | - Derek P D Bornath
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, Canada
| | - Seth F McCarthy
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, Canada
| | - Tom J Hazell
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, Canada
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3
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Jiao Y, Hao L, Xia P, Cheng Y, Song J, Chen X, Wang Z, Ma Z, Zheng S, Chen T, Zhang Y, Yu H. Identification of Potential miRNA-mRNA Regulatory Network Associated with Pig Growth Performance in the Pituitaries of Bama Minipigs and Landrace Pigs. Animals (Basel) 2022; 12:3058. [PMID: 36359184 PMCID: PMC9657654 DOI: 10.3390/ani12213058] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/02/2022] [Accepted: 11/03/2022] [Indexed: 08/27/2023] Open
Abstract
Pig growth performance is one of the criteria for judging pork production and is influenced by genotype and external environmental factors such as feeding conditions. The growth performance of miniature pigs, such as Bama minipigs, differs considerably from that of the larger body size pigs, such as Landrace pigs, and can be regarded as good models in pig growth studies. In this research, we identified differentially expressed genes in the pituitary gland of Bama minipigs and Landrace pigs. Through the pathway enrichment analysis, we screened the growth-related pathways and the genes enriched in the pathways and established the protein-protein interaction network. The RNAHybrid algorithm was used to predict the interaction between differentially expressed microRNAs and differentially expressed mRNAs. Four regulatory pathways (Y-82-ULK1/CDKN1A, miR-4334-5p-STAT3/PIK3R1/RPS6KA3/CAB39L, miR-4331-SCR/BCL2L1, and miR-133a-3p-BCL2L1) were identified via quantitative real-time PCR to detect the expression and correlation of candidate miRNAs and mRNAs. In conclusion, we revealed potential miRNA-mRNA regulatory networks associated with pig growth performance in the pituitary glands of Bama minipigs and Landrace pigs, which may help to elucidate the underlying molecular mechanisms of growth differences in pigs of different body sizes.
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Affiliation(s)
- Yingying Jiao
- College of Animal Science, Jilin University, Changchun 130061, China
| | - Linlin Hao
- College of Animal Science, Jilin University, Changchun 130061, China
| | - Peijun Xia
- College of Animal Science, Jilin University, Changchun 130061, China
| | - Yunyun Cheng
- Ministry of Health Key Laboratory of Radiobiology, College of Public Health, Jilin University, Changchun 130061, China
| | - Jie Song
- College of Animal Science, Jilin University, Changchun 130061, China
| | - Xi Chen
- College of Animal Science, Jilin University, Changchun 130061, China
| | - Zhaoguo Wang
- College of Animal Science, Jilin University, Changchun 130061, China
| | - Ze Ma
- College of Animal Science, Jilin University, Changchun 130061, China
| | - Shuo Zheng
- College of Animal Science, Jilin University, Changchun 130061, China
| | - Ting Chen
- Chinese National Engineering Research Center for Breeding Swine Industry, SCAU-Alltech Research Joint Alliance, Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Ying Zhang
- College of Animal Science, Jilin University, Changchun 130061, China
| | - Hao Yu
- College of Animal Science, Jilin University, Changchun 130061, China
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4
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Cawthon CR, de La Serre CB. The critical role of CCK in the regulation of food intake and diet-induced obesity. Peptides 2021; 138:170492. [PMID: 33422646 DOI: 10.1016/j.peptides.2020.170492] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 12/16/2020] [Accepted: 12/23/2020] [Indexed: 12/17/2022]
Abstract
In 1973, Gibbs, Young, and Smith showed that exogenous cholecystokinin (CCK) administration reduces food intake in rats. This initial report has led to thousands of studies investigating the physiological role of CCK in regulating feeding behavior. CCK is released from enteroendocrine I cells present along the gastrointestinal (GI) tract. CCK binding to its receptor CCK1R leads to vagal afferent activation providing post-ingestive feedback to the hindbrain. Vagal afferent neurons' (VAN) sensitivity to CCK is modulated by energy status while CCK signaling regulates gene expression of other feeding related signals and receptors expressed by VAN. In addition to its satiation effects, CCK acts all along the GI tract to optimize digestion and nutrient absorption. Diet-induced obesity (DIO) is characterized by reduced sensitivity to CCK and every part of the CCK system is negatively affected by chronic intake of energy-dense foods. EEC have recently been shown to adapt to diet, CCK1R is affected by dietary fats consumption, and the VAN phenotypic flexibility is lost in DIO. Altered endocannabinoid tone, changes in gut microbiota composition, and chronic inflammation are currently being explored as potential mechanisms for diet driven loss in CCK signaling. This review discusses our current understanding of how CCK controls food intake in conditions of leanness and how control is lost in chronic energy excess and obesity, potentially perpetuating excessive intake.
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Affiliation(s)
- Carolina R Cawthon
- Department of Foods and Nutrition, University of Georgia, Athens, GA, USA
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5
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Intracellular interplay between cholecystokinin and leptin signalling for satiety control in rats. Sci Rep 2020; 10:12000. [PMID: 32686770 PMCID: PMC7371863 DOI: 10.1038/s41598-020-69035-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 06/29/2020] [Indexed: 11/09/2022] Open
Abstract
Cholecystokinin (CCK) and leptin are satiety-controlling peptides, yet their interactive roles remain unclear. Here, we addressed this issue using in vitro and in vivo models. In rat C6 glioma cells, leptin pre-treatment enhanced Ca2+ mobilization by a CCK agonist (CCK-8s). This leptin action was reduced by Janus kinase inhibitor (AG490) or PI3-kinase inhibitor (LY294002). Meanwhile, leptin stimulation alone failed to mobilize Ca2+ even in cells overexpressing leptin receptors (C6-ObRb). Leptin increased nuclear immunoreactivity against phosphorylated STAT3 (pSTAT3) whereas CCK-8s reduced leptin-induced nuclear pSTAT3 accumulation in these cells. In the rat ventromedial hypothalamus (VMH), leptin-induced action potential firing was enhanced, whereas nuclear pSTAT3 was reduced by co-stimulation with CCK-8s. To further analyse in vivo signalling interplay, a CCK-1 antagonist (lorglumide) was intraperitoneally injected in rats following 1-h restricted feeding. Food access was increased 3-h after lorglumide injection. At this timepoint, nuclear pSTAT3 was increased whereas c-Fos was decreased in the VMH. Taken together, these results suggest that leptin and CCK receptors may both contribute to short-term satiety, and leptin could positively modulate CCK signalling. Notably, nuclear pSTAT3 levels in this experimental paradigm were negatively correlated with satiety levels, contrary to the generally described transcriptional regulation for long-term satiety via leptin receptors.
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6
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Idrizaj E, Garella R, Squecco R, Baccari MC. Adipocytes-released Peptides Involved in the Control of Gastrointestinal Motility. Curr Protein Pept Sci 2019; 20:614-629. [PMID: 30663565 DOI: 10.2174/1389203720666190121115356] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 01/07/2019] [Accepted: 01/09/2019] [Indexed: 12/18/2022]
Abstract
The present review focuses on adipocytes-released peptides known to be involved in the control of gastrointestinal motility, acting both centrally and peripherally. Thus, four peptides have been taken into account: leptin, adiponectin, nesfatin-1, and apelin. The discussion of the related physiological or pathophysiological roles, based on the most recent findings, is intended to underlie the close interactions among adipose tissue, central nervous system, and gastrointestinal tract. The better understanding of this complex network, as gastrointestinal motor responses represent peripheral signals involved in the regulation of food intake through the gut-brain axis, may also furnish a cue for the development of either novel therapeutic approaches in the treatment of obesity and eating disorders or potential diagnostic tools.
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Affiliation(s)
- Eglantina Idrizaj
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Florence, Italy
| | - Rachele Garella
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Florence, Italy
| | - Roberta Squecco
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Florence, Italy
| | - Maria Caterina Baccari
- Department of Experimental and Clinical Medicine, Section of Physiological Sciences, University of Florence, Florence, Italy
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7
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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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8
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Choi JS. Effects of Maternal and Post-Weaning High-Fat Diet on Leptin Resistance and Hypothalamic Appetite Genes in Sprague Dawley Rat Offspring. Clin Nutr Res 2018; 7:276-290. [PMID: 30406057 PMCID: PMC6209730 DOI: 10.7762/cnr.2018.7.4.276] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/11/2018] [Accepted: 09/16/2018] [Indexed: 01/13/2023] Open
Abstract
The defective satiation signaling may contribute to the etiology of obesity. We investigated how dietary modification during maternal (pregnancy and lactation) and post-weaning affects obesity, insulin resistance (IR) and hypothalamic appetite responses in offspring in adulthood. Pregnant female SD rats were randomly allocated to either maternal high-fat diet (43% energy from fat) or control diet (12% energy from fat) until the end of suckling. After weaning for additional 4 weeks, half of the offsprings were continuously fed the same diet as the dam (C-C and H-H groups); the remainder received the counterpart diet (C-H and H-C groups). The long-term high-fat diet during maternal and post-weaning period (H-H group) led to susceptibility to obesity and IR through the significant increases of hypothalamic orexigenic genes compared to the maternal and post-weaning control diet group (C-C group). In contrast, the hypothalamic expression levels of anorexigenic genes, apolipoprotein E, leptin receptor, and activated signal transducer and activator of transcription protein 3 were significantly lower in H-H group with elevations in circulating insulin and leptin and body fat mass. However, dietary changes after weaning (H-C and C-H groups) partially modified these conditions. These results suggest that maternal and post-weaning diet conditions can potentially disrupt hypothalamic neuronal signal irrelevantly, which is essential for leptin's regulation of energy homeostasis and induce the risk of offspring to future metabolic disorders.
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Affiliation(s)
- Joo Sun Choi
- Department of Home Economics, College of Education, Kyungnam University, Changwon 51767, Korea
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9
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Abstract
The regulation of energy and glucose balance contributes to whole-body metabolic homeostasis, and such metabolic regulation is disrupted in obesity and diabetes. Metabolic homeostasis is orchestrated partly in response to nutrient and vagal-dependent gut-initiated functions. Specifically, the sensory and motor fibres of the vagus nerve transmit intestinal signals to the central nervous system and exert biological and physiological responses. In the past decade, the understanding of the regulation of vagal afferent signals and of the associated metabolic effect on whole-body energy and glucose balance has progressed. This Review highlights the contributions made to the understanding of the vagal afferent system and examines the integrative role of the vagal afferent in gastrointestinal regulation of appetite and glucose homeostasis. Investigating the integrative and metabolic role of vagal afferent signalling represents a potential strategy to discover novel therapeutic targets to restore energy and glucose balance in diabetes and obesity.
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10
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Santiago GG, Siqueira F, Cardoso FF, Regitano LCA, Ventura R, Sollero BP, Souza MD, Mokry FB, Ferreira ABR, Torres RAA. Genomewide association study for production and meat quality traits in Canchim beef cattle. J Anim Sci 2018; 95:3381-3390. [PMID: 28805909 DOI: 10.2527/jas.2017.1570] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The commercial value of the bovine carcass is determined by a set of traits, such as weight, yield, back fat thickness, and marbling; therefore, the genetic improvement of growth, meat, and carcass quality traits is an important tool to add value to the supply chain. Genomewide association studies (GWAS) enable the identification of loci that control phenotypic expression of quantitative traits (QTL). Therefore, the objective of this work was to perform a GWAS to identify genomic regions and genes associated with growth, carcass traits, and meat quality in Canchim beef cattle. These traits were yearling weight (YW), rib eye area (REA), back fat thickness (BFT), and marbling (MARB). To increase sample size and marker density, genotype imputation was performed, and only markers imputed with greater than 95% accuracy were used. Genomewide association study was performed using a Bayesian approach, by the Bayes B statistical method, incorporating genotypes and phenotypes from 614 animals from both the Canchim breed and the MA genetic group (offspring of Charolais bulls and one-half Canchim + one-half Zebu cows). This investigation identified 1 and 4 genomic regions explaining 0.23 and 7.35% of the genetic variance for REA and YW, respectively. These regions harbor a total of 19 genes, 7 of which were classified for biological functions by functional analysis. Significant associations were not observed for BFT and MARB. The identification of QTL that had been previously described in the literature reinforces associations found in this study.
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11
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Mechanick JI, Zhao S, Garvey WT. Leptin, An Adipokine With Central Importance in the Global Obesity Problem. Glob Heart 2017; 13:113-127. [PMID: 29248361 DOI: 10.1016/j.gheart.2017.10.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 10/25/2017] [Indexed: 02/08/2023] Open
Abstract
Leptin has central importance in the global obesity and cardiovascular disease problem. Leptin is principally secreted by adipocytes and acts in the hypothalamus to suppress appetite and food intake, increase energy expenditure, and regulate body weight. Based on clinical translation of specific and networked actions, leptin affects the cardiovascular system and may be a marker and driver of cardiometabolic risk factors with interventions that are actionable by cardiologists. Leptin subnetwork analysis demonstrates a statistically significant role for ethnoculturally and socioeconomically appropriate lifestyle intervention in cardiovascular disease. Emergent mechanistic components and potential diagnostic or therapeutic targets include hexokinase 3, urocortins, clusterin, sialic acid-binding immunoglobulin-like lectin 6, C-reactive protein, platelet glycoprotein VI, albumin, pentraxin 3, ghrelin, obestatin prepropeptide, leptin receptor, neuropeptide Y, and corticotropin-releasing factor receptor 1. Emergent associated symptoms include weight change, eating disorders, vascular necrosis, chronic fatigue, and chest pain. Leptin-targeted therapies are reported for lipodystrophy and leptin deficiency, but they are investigational for leptin resistance, obesity, and other chronic diseases.
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Affiliation(s)
- Jeffrey I Mechanick
- Division of Cardiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Division of Endocrinology, Diabetes, and Bone Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Shan Zhao
- Basepaws Inc., Redondo Beach, CA, USA
| | - W Timothy Garvey
- Department of Nutritional Sciences and Diabetes Research Center, University of Alabama at Birmingham, Birmingham, AL, USA; Geriatric Research Education and Clinical Center, Birmingham Veterans Affairs Medical Center, Birmingham, AL, USA
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12
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Gutiérrez-Tenorio J, Marín-Royo G, Martínez-Martínez E, Martín R, Miana M, López-Andrés N, Jurado-López R, Gallardo I, Luaces M, San Román JA, González-Amor M, Salaices M, Nieto ML, Cachofeiro V. The role of oxidative stress in the crosstalk between leptin and mineralocorticoid receptor in the cardiac fibrosis associated with obesity. Sci Rep 2017; 7:16802. [PMID: 29196758 PMCID: PMC5711898 DOI: 10.1038/s41598-017-17103-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 11/22/2017] [Indexed: 12/27/2022] Open
Abstract
We have investigated whether mineralocorticoid receptor activation can participate in the profibrotic effects of leptin in cardiac myofibroblasts, as well as the potential mechanisms involved. The presence of eplerenone reduced the leptin-induced increase in protein levels of collagen I, transforming growth factor β, connective tissue growth factor and galectin-3 and the levels of both total and mitochondrial of superoxide anion (O2.−) in cardiac myofibroblasts. Likewise, the MEK/ERK inhibitor, PD98059, and the PI3/Akt inhibitor, LY294002, showed a similar pattern. Mitochondrial reactive oxygen species (ROS) scavenger (MitoTempo) attenuated the increase in body weight observed in rats fed a high fat diet (HFD). No differences were found in cardiac function or blood pressure among any group. However, the cardiac fibrosis and enhanced O2.-levels observed in HFD rats were attenuated by MitoTempo, which also prevented the increased circulating leptin and aldosterone levels in HFD fed animals. This study supports a role of mineralocorticoid receptor in the cardiac fibrosis induced by leptin in the context of obesity and highlights the role of the mitochondrial ROS in this process.
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Affiliation(s)
- Josué Gutiérrez-Tenorio
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense de Madrid and Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM), Madrid, Spain
| | - Gema Marín-Royo
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense de Madrid and Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM), Madrid, Spain
| | - Ernesto Martínez-Martínez
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense de Madrid and Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM), Madrid, Spain.,Cardiovascular Translational Research, Navarrabiomed (Miguel Servet Foundation), Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Rubén Martín
- Instituto de Biología y Genética Molecular, CSIC-Universidad de Valladolid, Valladolid, Spain
| | - María Miana
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense de Madrid and Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM), Madrid, Spain.,Facultad de Enfermería y Fisioterapia, Salus Infirmorum. Universidad Pontificia de Salamanca, Madrid, Spain
| | - Natalia López-Andrés
- Cardiovascular Translational Research, Navarrabiomed (Miguel Servet Foundation), Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Raquel Jurado-López
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense de Madrid and Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM), Madrid, Spain
| | - Isabel Gallardo
- Instituto de Biología y Genética Molecular, CSIC-Universidad de Valladolid, Valladolid, Spain
| | - María Luaces
- Servicio de Cardiología, Instituto Cardiovascular, Hospital Clínico San Carlos, Madrid, Spain
| | - José Alberto San Román
- Instituto de Ciencias del Corazón (ICICOR), Hospital Clínico Universitario de Valladolid, Valladolid, Spain.,Ciber de Enfermedades Cardiovasculares (CIBERCV). Instituto de Salud Carlos III, Madrid, Spain
| | - María González-Amor
- Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid and Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid, Spain
| | - Mercedes Salaices
- Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid and Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid, Spain.,Ciber de Enfermedades Cardiovasculares (CIBERCV). Instituto de Salud Carlos III, Madrid, Spain
| | - María Luisa Nieto
- Instituto de Biología y Genética Molecular, CSIC-Universidad de Valladolid, Valladolid, Spain.,Ciber de Enfermedades Cardiovasculares (CIBERCV). Instituto de Salud Carlos III, Madrid, Spain
| | - Victoria Cachofeiro
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense de Madrid and Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM), Madrid, Spain. .,Ciber de Enfermedades Cardiovasculares (CIBERCV). Instituto de Salud Carlos III, Madrid, Spain.
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13
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Karaseva TL, Likhota EB, Krivenko YR, Semibrat’ev SA, Pavlovskii VI. Synthesis of New 7-bromo-5-(2’-chlorophenyl)-3-arylamino-1,2-dihydro-3H-1,4-benzodiazepine Derivatives and Their Influence on Appetite in Rats. Pharm Chem J 2017. [DOI: 10.1007/s11094-017-1594-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Page AJ, Kentish SJ. Plasticity of gastrointestinal vagal afferent satiety signals. Neurogastroenterol Motil 2017; 29. [PMID: 27781333 DOI: 10.1111/nmo.12973] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 09/19/2016] [Indexed: 12/21/2022]
Abstract
The vagal link between the gastrointestinal tract and the central nervous system (CNS) has numerous vital functions for maintaining homeostasis. The regulation of energy balance is one which is attracting more and more attention due to the potential for exploiting peripheral hormonal targets as treatments for conditions such as obesity. While physiologically, this system is well tuned and demonstrated to be effective in the regulation of both local function and promoting/terminating food intake the neural connection represents a susceptible pathway for disruption in various disease states. Numerous studies have revealed that obesity in particularly is associated with an array of modifications in vagal afferent function from changes in expression of signaling molecules to altered activation mechanics. In general, these changes in vagal afferent function in obesity further promote food intake instead of the more desirable reduction in food intake. It is essential to gain a comprehensive understanding of the mechanisms responsible for these detrimental effects before we can establish more effective pharmacotherapies or lifestyle strategies for the treatment of obesity and the maintenance of weight loss.
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Affiliation(s)
- A J Page
- Centre for Nutrition and Gastrointestinal Disease, Discipline of Medicine, University of Adelaide, Adelaide, SA, Australia.,Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, SA, Australia.,Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, SA, Australia
| | - S J Kentish
- Centre for Nutrition and Gastrointestinal Disease, Discipline of Medicine, University of Adelaide, Adelaide, SA, Australia.,Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, SA, Australia.,School of Medicine, University of Queensland, St Lucia, QLD, Australia
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Grabauskas G, Owyang C. Plasticity of vagal afferent signaling in the gut. MEDICINA-LITHUANIA 2017; 53:73-84. [PMID: 28454890 PMCID: PMC6318799 DOI: 10.1016/j.medici.2017.03.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 03/21/2017] [Indexed: 12/13/2022]
Abstract
Vagal sensory neurons mediate the vago-vagal reflex which, in turn, regulates a wide array of gastrointestinal functions including esophageal motility, gastric accommodation and pancreatic enzyme secretion. These neurons also transmit sensory information from the gut to the central nervous system, which then mediates the sensations of nausea, fullness and satiety. Recent research indicates that vagal afferent neurons process non-uniform properties and a significant degree of plasticity. These properties are important to ensure that vagally regulated gastrointestinal functions respond rapidly and appropriately to various intrinsic and extrinsic factors. Similar plastic changes in the vagus also occur in pathophysiological conditions, such as obesity and diabetes, resulting in abnormal gastrointestinal functions. A clear understanding of the mechanisms which mediate these events may provide novel therapeutic targets for the treatment of gastrointestinal disorders due to vago-vagal pathway malfunctions.
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Affiliation(s)
- Gintautas Grabauskas
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48019, USA.
| | - Chung Owyang
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48019, USA
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16
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A dangerous liaison: Leptin and sPLA2-IIA join forces to induce proliferation and migration of astrocytoma cells. PLoS One 2017; 12:e0170675. [PMID: 28249041 PMCID: PMC5331986 DOI: 10.1371/journal.pone.0170675] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 01/09/2017] [Indexed: 11/19/2022] Open
Abstract
Glioblastoma, the most aggressive type of primary brain tumour, shows worse prognosis linked to diabetes or obesity persistence. These pathologies are chronic inflammatory conditions characterized by altered profiles of inflammatory mediators, including leptin and secreted phospholipase A2-IIA (sPLA2-IIA). Both proteins, in turn, display diverse pro-cancer properties in different cell types, including astrocytes. Herein, to understand the underlying relationship between obesity and brain tumors, we investigated the effect of leptin, alone or in combination with sPLA2-IIA on astrocytoma cell functions. sPLA2-IIA induced up-regulation of leptin receptors in 1321N1 human astrocytoma cells. Leptin, as well as sPLA2-IIA, increased growth and migration in these cells, through activation/phosphorylation of key proteins of survival cascades. Leptin, at concentrations with minimal or no activating effects on astrocytoma cells, enhanced growth and migration promoted by low doses of sPLA2-IIA. sPLA2-IIA alone induced a transient phosphorylation pattern in the Src/ERK/Akt/mTOR/p70S6K/rS6 pathway through EGFR transactivation, and co-addition of leptin resulted in a sustained phosphorylation of these signaling regulators. Mechanistically, EGFR transactivation and tyrosine- and serine/threonine-protein phosphatases revealed a key role in this leptin-sPLA2-IIA cross-talk. This cooperative partnership between both proteins was also found in primary astrocytes. These findings thus indicate that the adipokine leptin, by increasing the susceptibility of cells to inflammatory mediators, could contribute to worsen the prognosis of tumoral and neurodegenerative processes, being a potential mediator of some obesity-related medical complications.
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Grabauskas G, Wu X, Song I, Zhou SY, Lanigan T, Owyang C. Increased Activation of the TRESK K + Mediates Vago-Vagal Reflex Malfunction in Diabetic Rats. Gastroenterology 2016; 151:910-922.e7. [PMID: 27475306 PMCID: PMC5159314 DOI: 10.1053/j.gastro.2016.07.029] [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: 12/22/2015] [Revised: 06/29/2016] [Accepted: 07/07/2016] [Indexed: 12/28/2022]
Abstract
BACKGROUND & AIMS Patients with diabetes have defects in the vagal afferent pathway that result in abnormal gastrointestinal function. We investigated whether selective increased activation of the 2-pore domain potassium channel TRESK (2-pore-domain weak inward-rectifying potassium channel-related spinal cord potassium channel) contributes to nodose ganglia (NG) malfunction, disrupting gastrointestinal function in diabetic rats. METHODS We conducted whole-cell current-clamp and single-unit recordings in NG neurons from diabetes-prone BioBreeding/Worcester rats and streptozotocin-induced diabetic (STZ-D) rats and compared them with control rats. NG neurons in rats or cultured NG neurons were exposed to pharmacologic antagonists and/or transfected with short hairpin or small interfering RNAs that reduced expression of TRESK. We then made electrophysiologic recordings and studied gastrointestinal functions. RESULTS We observed reduced input resistance, hyperpolarized membrane potential, and increased current threshold to elicit action potentiation in NG neurons of STZ-D rats compared with controls. NG neuron excitability was similarly altered in diabetes-prone rats. In vivo single-unit NG neuronal discharges in response to 30 and 60 pmol cholecystokinin octapeptide were significantly lower in STZ-D rats compared with controls. Reducing expression of the TRESK K+ channel restored NG excitability in vitro and in vivo, as well as cholecystokinin 8-stimulated secretion of pancreatic enzymes and secretin-induced gastrointestinal motility, which are mediated by vago-vagal reflexes. These abnormalities resulted from increased intracellular Ca2+ in the NG, activating calcineurin, which, in turn, bound to an nuclear factor of activated T cell-like docking site on the TRESK protein, resulting in neuronal membrane hyperpolarization. CONCLUSIONS In 2 rate models of diabetes, we found that activation of the TRESK K+ channel reduced NG excitability and disrupted gastrointestinal functions.
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Affiliation(s)
- Gintautas Grabauskas
- Division of Gastroenterology, Department of Internal Medicine, Ann Arbor, Michigan
| | - Xiaoyin Wu
- Division of Gastroenterology, Department of Internal Medicine, Ann Arbor, Michigan
| | - Il Song
- Division of Gastroenterology, Department of Internal Medicine, Ann Arbor, Michigan
| | - Shi-Yi Zhou
- Division of Gastroenterology, Department of Internal Medicine, Ann Arbor, Michigan
| | - Thomas Lanigan
- Department of Internal Medicine, Center for Gene Therapy, Ann Arbor, Michigan
| | - Chung Owyang
- Division of Gastroenterology, Department of Internal Medicine, Ann Arbor, Michigan.
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18
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Interplay between gut microbiota, its metabolites and human metabolism: Dissecting cause from consequence. Trends Food Sci Technol 2016. [DOI: 10.1016/j.tifs.2016.08.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Miller LJ, Desai AJ. Metabolic Actions of the Type 1 Cholecystokinin Receptor: Its Potential as a Therapeutic Target. Trends Endocrinol Metab 2016; 27:609-619. [PMID: 27156041 PMCID: PMC4992613 DOI: 10.1016/j.tem.2016.04.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/31/2016] [Accepted: 04/05/2016] [Indexed: 12/13/2022]
Abstract
Cholecystokinin (CCK) regulates appetite and reduces food intake by activating the type 1 CCK receptor (CCK1R). Attempts to develop CCK1R agonists for obesity have yielded active agents that have not reached clinical practice. Here we discuss why, along with new strategies to target CCK1R more effectively. We examine signaling events and the possibility of developing agents that exhibit ligand-directed bias, to dissociate satiety activity from undesirable side effects. Potential allosteric sites of modulation are also discussed, along with desired properties of a positive allosteric modulator (PAM) without intrinsic agonist action as another strategy to treat obesity. These new types of CCK1R-active drugs could be useful as standalone agents or as part of a rational drug combination for management of obesity.
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Affiliation(s)
- Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA.
| | - Aditya J Desai
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA
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Grabauskas G, Wu X, Lu Y, Heldsinger A, Song I, Zhou SY, Owyang C. KATP channels in the nodose ganglia mediate the orexigenic actions of ghrelin. J Physiol 2015; 593:3973-89. [PMID: 26174421 PMCID: PMC4575581 DOI: 10.1113/jp270788] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/26/2015] [Indexed: 12/21/2022] Open
Abstract
Ghrelin, a hunger signalling peptide derived from the peripheral tissues, overcomes the satiety signals evoked by anorexigenic molecules, such as cholecystokinin (CCK) and leptin, to stimulate feeding. Using in vivo and in vitro electrophysiological techniques, we show that ghrelin hyperpolarizes neurons and inhibits currents evoked by leptin and CCK-8. Administering a KATP channel antagonist or silencing Kir6.2, a major subunit of the KATP channel, abolished ghrelin inhibition. The inhibitory actions of ghrelin were also abolished by treating the vagal ganglia neurons with pertussis toxin, as well as phosphatidylinositol 3-kinase (PI3K) or extracellular signal-regulated kinase 1 and 2 (Erk1/2) small interfering RNA. Feeding experiments showed that silencing Kir6.2 in the vagal ganglia abolished the orexigenic actions of ghrelin. These data indicate that ghrelin modulates vagal ganglia neuron excitability by activating KATP conductance via the growth hormone secretagogue receptor subtype 1a-Gαi -PI3K-Erk1/2-KATP pathway. This provides a mechanism to explain the actions of ghrelin with respect to overcoming anorexigenic signals that act via the vagal afferent pathways. Ghrelin is the only known hunger signal derived from the peripheral tissues. Ghrelin overcomes the satiety signals evoked by anorexigenic molecules, such as cholecystokinin (CCK) and leptin, to stimulate feeding. The mechanisms by which ghrelin reduces the sensory signals evoked by anorexigenic hormones, which act via the vagus nerve to stimulate feeding, are unknown. Patch clamp recordings of isolated rat vagal neurons show that ghrelin hyperpolarizes neurons by activating K(+) conductance. Administering a KATP channel antagonist or silencing Kir6.2, a major subunit of the KATP channel, abolished ghrelin inhibition in vitro and in vivo. Patch clamp studies show that ghrelin inhibits currents evoked by leptin and CCK-8, which operate through independent ionic channels. The inhibitory actions of ghrelin were abolished by treating the vagal ganglia neurons with pertussis toxin, as well as phosphatidylinositol 3-kinase (PI3K) or extracellular signal-regulated kinase 1 and 2 (Erk1/2) small interfering RNA. In vivo gene silencing of PI3K and Erk1/2 in the nodose ganglia prevented ghrelin inhibition of leptin- or CCK-8-evoked vagal firing. Feeding experiments showed that silencing Kir6.2 in the vagal ganglia abolished the orexigenic actions of ghrelin. These data indicate that ghrelin modulates vagal ganglia neuron excitability by activating KATP conductance via the growth hormone secretagogue receptor subtype 1a-Gαi -PI3K-Erk1/2-KATP pathway. The resulting hyperpolarization renders the neurons less responsive to signals evoked by anorexigenic hormones. This provides a mechanism to explain the actions of ghrelin with respect to overcoming anorexigenic signals that act via the vagal afferent pathways.
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Affiliation(s)
- Gintautas Grabauskas
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health SystemAnn Arbor, MI, USA
| | - Xiaoyin Wu
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health SystemAnn Arbor, MI, USA
| | - Yuanxu Lu
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health SystemAnn Arbor, MI, USA
| | - Andrea Heldsinger
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health SystemAnn Arbor, MI, USA
| | - Il Song
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health SystemAnn Arbor, MI, USA
| | - Shi-Yi Zhou
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health SystemAnn Arbor, MI, USA
| | - Chung Owyang
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health SystemAnn Arbor, MI, USA
- Corresponding author C. Owyang: 3912 Taubman Center, SPC 5362, 1500 East Medical Center Drive, University of Michigan Health System, Ann Arbor, MI 48109, USA.
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Fang H, Chen QP. Leptin and maintenance of gastrointestinal function. Shijie Huaren Xiaohua Zazhi 2015; 23:2920-2927. [DOI: 10.11569/wcjd.v23.i18.2920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Leptin is a protein hormone encoded by the obese (Ob) gene, exerting an important biological role in the life. Initially, leptin is believed to play a major role in regulating appetite control and energy metabolism, including adjusting the energy metabolism. However, recent data suggest that leptin also plays an important part in regulating the function of the gastrointestinal tract, immune and inflammation response, injury repair, and tumor angiogenesis. This article reviews the protective effects of leptin on the function of the gastrointestinal tract.
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Heldsinger A, Grabauskas G, Wu X, Zhou S, Lu Y, Song I, Owyang C. Ghrelin induces leptin resistance by activation of suppressor of cytokine signaling 3 expression in male rats: implications in satiety regulation. Endocrinology 2014; 155:3956-69. [PMID: 25060362 PMCID: PMC4164930 DOI: 10.1210/en.2013-2095] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The anorexigenic adipocyte-derived hormone leptin and the orexigenic hormone ghrelin act in opposition to regulate feeding behavior via the vagal afferent pathways. The mechanisms by which ghrelin exerts its inhibitory effects on leptin are unknown. We hypothesized that ghrelin activates the exchange protein activated by cAMP (Epac), inducing increased SOCS3 expression, which negatively affects leptin signal transduction and neuronal firing in nodose ganglia (NG) neurons. We showed that 91 ± 3% of leptin receptor (LRb) -bearing neurons contained ghrelin receptors (GHS-R1a) and that ghrelin significantly inhibited leptin-stimulated STAT3 phosphorylation in rat NG neurons. Studies of the signaling cascades used by ghrelin showed that ghrelin caused a significant increase in Epac and suppressor of cytokine signaling 3 (SOCS3) expression in cultured rat NG neurons. Transient transfection of cultured NG neurons to silence SOCS3 and Epac genes reversed the inhibitory effects of ghrelin on leptin-stimulated STAT3 phosphorylation. Patch-clamp studies and recordings of single neuronal discharges of vagal primary afferent neurons showed that ghrelin markedly inhibited leptin-stimulated neuronal firing, an action abolished by silencing SOCS3 expression in NG. Plasma ghrelin levels increased significantly during fasting. This was accompanied by enhanced SOCS3 expression in the NG and prevented by treatment with a ghrelin antagonist. Feeding studies showed that silencing SOCS3 expression in the NG reduced food intake evoked by endogenous leptin. We conclude that ghrelin exerts its inhibitory effects on leptin-stimulated neuronal firing by increasing SOCS3 expression. The SOCS3 signaling pathway plays a pivotal role in ghrelin's inhibitory effect on STAT3 phosphorylation, neuronal firing, and feeding behavior.
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Affiliation(s)
- Andrea Heldsinger
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48019
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A new IRAK-M-mediated mechanism implicated in the anti-inflammatory effect of nicotine via α7 nicotinic receptors in human macrophages. PLoS One 2014; 9:e108397. [PMID: 25259522 PMCID: PMC4178160 DOI: 10.1371/journal.pone.0108397] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 08/21/2014] [Indexed: 12/21/2022] Open
Abstract
Nicotine stimulation of α7 nicotinic acetylcholine receptor (α7 nAChR) powerfully inhibits pro-inflammatory cytokine production in lipopolysaccharide (LPS)-stimulated macrophages and in experimental models of endotoxemia. A signaling pathway downstream from the α7 nAChRs, which involves the collaboration of JAK2/STAT3 and NF-κB to interfere with signaling by Toll-like receptors (TLRs), has been implicated in this anti-inflammatory effect of nicotine. Here, we identifiy an alternative mechanism involving interleukin-1 receptor-associated kinase M (IRAK-M), a negative regulator of innate TLR-mediated immune responses. Our data show that nicotine up-regulates IRAK-M expression at the mRNA and protein level in human macrophages, and that this effect is secondary to α7 nAChR activation. By using selective inhibitors of different signaling molecules downstream from the receptor, we provide evidence that activation of STAT3, via either JAK2 and/or PI3K, through a single (JAK2/PI3K/STAT3) or two convergent cascades (JAK2/STAT3 and PI3K/STAT3), is necessary for nicotine-induced IRAK-M expression. Moreover, down-regulation of this expression by small interfering RNAs specific to the IRAK-M gene significantly reverses the anti-inflammatory effect of nicotine on LPS-induced TNF-α production. Interestingly, macrophages pre-exposed to nicotine exhibit higher IRAK-M levels and reduced TNF-α response to an additional LPS challenge, a behavior reminiscent of the ‘endotoxin tolerant’ phenotype identified in monocytes either pre-exposed to LPS or from immunocompromised septic patients. Since nicotine is a major component of tobacco smoke and increased IRAK-M expression has been considered one of the molecular determinants for the induction of the tolerant phenotype, our findings showing IRAK-M overexpression could partially explain the known influence of smoking on the onset and progression of inflammatory and infectious diseases.
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Leptin and aging: Review and questions with particular emphasis on its role in the central regulation of energy balance. J Chem Neuroanat 2014; 61-62:248-55. [PMID: 25218974 DOI: 10.1016/j.jchemneu.2014.08.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 08/07/2014] [Accepted: 08/13/2014] [Indexed: 01/12/2023]
Abstract
Leptin is produced mainly in the white adipose tissue and emerged as one of the key catabolic regulators of food intake and energy expenditure. During the course of aging characteristic alterations in body weight and body composition in humans and mammals, i.e. middle-aged obesity and aging anorexia and cachexia, suggest age-related regulatory changes in energy balance in the background. Aging has been associated with increased fat mass, central and peripheral leptin resistance as indicated by its failure to reduce food intake, to increase metabolic rate and thereby to induce weight loss. Leptin resistance is a common feature of aging and obesity (even in the young). The question arises whether aging or fat accumulation plays the primary role in the development of this resistance. The review focuses mainly on mechanisms and development of central leptin resistance. Age-related decline primarily affects the hypermetabolic component of central catabolic leptin actions, while the anorexigenic component is even growing stronger in the late phase of aging. Obesity enhances resistance to leptin at any age, particularly in old rats, calorie-restriction, on the other hand, increases responsiveness to leptin, especially in the oldest age-group. Thus, without obesity, leptin sensitivity appears not to decrease but to increase by old age. Interactions with other substances (e.g. insulin, cholecystokinin, endogenous cannabinoids) and life-style factors (e.g. exercise) in these age-related changes need to be investigated.
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Guan X. The CNS glucagon-like peptide-2 receptor in the control of energy balance and glucose homeostasis. Am J Physiol Regul Integr Comp Physiol 2014; 307:R585-96. [PMID: 24990862 DOI: 10.1152/ajpregu.00096.2014] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The gut-brain axis plays a key role in the control of energy balance and glucose homeostasis. In response to luminal stimulation of macronutrients and microbiota-derived metabolites (secondary bile acids and short chain fatty acids), glucagon-like peptides (GLP-1 and -2) are cosecreted from endocrine L cells in the gut and coreleased from preproglucagonergic neurons in the brain stem. Glucagon-like peptides are proposed as key mediators for bariatric surgery-improved glycemic control and energy balance. Little is known about the GLP-2 receptor (Glp2r)-mediated physiological roles in the control of food intake and glucose homeostasis, yet Glp1r has been studied extensively. This review will highlight the physiological relevance of the central nervous system (CNS) Glp2r in the control of energy balance and glucose homeostasis and focuses on cellular mechanisms underlying the CNS Glp2r-mediated neural circuitry and intracellular PI3K signaling pathway. New evidence (obtained from Glp2r tissue-specific KO mice) indicates that the Glp2r in POMC neurons is essential for suppressing feeding behavior, gastrointestinal motility, and hepatic glucose production. Mice with Glp2r deletion selectively in POMC neurons exhibit hyperphagic behavior, accelerated gastric emptying, glucose intolerance, and hepatic insulin resistance. GLP-2 differentially modulates postsynaptic membrane excitability of hypothalamic POMC neurons in Glp2r- and PI3K-dependent manners. GLP-2 activates the PI3K-Akt-FoxO1 signaling pathway in POMC neurons by Glp2r-p85α interaction. Intracerebroventricular GLP-2 augments glucose tolerance, suppresses glucose production, and enhances insulin sensitivity, which require PI3K (p110α) activation in POMC neurons. Thus, the CNS Glp2r plays a physiological role in the control of food intake and glucose homeostasis. This review will also discuss key questions for future studies.
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Affiliation(s)
- Xinfu Guan
- U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics; and Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, Texas
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Leptin modulates the intrinsic excitability of AgRP/NPY neurons in the arcuate nucleus of the hypothalamus. J Neurosci 2014; 34:5486-96. [PMID: 24741039 DOI: 10.1523/jneurosci.4861-12.2014] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The hypothalamic arcuate nucleus (ARH) is a brain region critical for regulation of food intake and a primary area for the action of leptin in the CNS. In lean mice, the adipokine leptin inhibits neuropeptide Y (NPY) and agouti-related peptide (AgRP) neuronal activity, resulting in decreased food intake. Here we show that diet-induced obesity in mice is associated with persistent activation of NPY neurons and a failure of leptin to reduce the firing rate or hyperpolarize the resting membrane potential. However, the molecular mechanism whereby diet uncouples leptin's effect on neuronal excitability remains to be fully elucidated. In NPY neurons from lean mice, the Kv channel blocker 4-aminopyridine inhibited leptin-induced changes in input resistance and spike rate. Consistent with this, we found that ARH NPY neurons have a large, leptin-sensitive delayed rectifier K(+) current and that leptin sensitivity of this current is blunted in neurons from diet-induced obese mice. This current is primarily carried by Kv2-containing channels, as the Kv2 channel inhibitor stromatoxin-1 significantly increased the spontaneous firing rate in NPY neurons from lean mice. In HEK cells, leptin induced a significant hyperpolarizing shift in the voltage dependence of Kv2.1 but had no effect on the function of the closely related channel Kv2.2 when these channels were coexpressed with the long isoform of the leptin receptor LepRb. Our results suggest that dynamic modulation of somatic Kv2.1 channels regulates the intrinsic excitability of NPY neurons to modulate the spontaneous activity and the integration of synaptic input onto these neurons in the ARH.
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Akieda-Asai S, Poleni PE, Date Y. Coinjection of CCK and leptin reduces food intake via increased CART/TRH and reduced AMPK phosphorylation in the hypothalamus. Am J Physiol Endocrinol Metab 2014; 306:E1284-91. [PMID: 24735891 DOI: 10.1152/ajpendo.00664.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
CCK and leptin are anorectic hormones produced in the small intestine and white adipose tissue, respectively. Investigating how these hormones act together as an integrated anorectic signal is important for elucidating the mechanisms by which energy balance is maintained. We found here that coadministration of subthreshold CCK and leptin, which individually have no effect on feeding, dramatically reduced food intake in rats. Phosphorylation of AMP-activated protein kinase (AMPK) in the hypothalamus significantly decreased after coinjection of CCK and leptin. In addition, coadministration of these hormones significantly increased mRNA levels of anorectic cocaine- and amphetamine-regulated transcript (CART) and thyrotropin-releasing hormone (TRH) in the hypothalamus. The interactive effect of CCK and leptin on food intake was abolished by intracerebroventricular preadministration of the AMPK activator AICAR or anti-CART/anti-TRH antibodies. These findings indicate that coinjection of CCK and leptin reduces food intake via reduced AMPK phosphorylation and increased CART/TRH in the hypothalamus. Furthermore, by using midbrain-transected rats, we investigated the role of the neural pathway from the hindbrain to the hypothalamus in the interaction of CCK and leptin to reduce food intake. Food intake reduction induced by coinjection of CCK and leptin was blocked in midbrain-transected rats. Therefore, the neural pathway from hindbrain to hypothalamus plays an important role in transmitting the anorectic signals provided by coinjection of CCK and leptin. Our findings give further insight into the mechanisms of feeding and energy balance.
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Affiliation(s)
- Sayaka Akieda-Asai
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Paul-Emile Poleni
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Yukari Date
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
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28
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Rasmussen BA, Breen DM, Duca FA, Côté CD, Zadeh-Tahmasebi M, Filippi BM, Lam TKT. Jejunal leptin-PI3K signaling lowers glucose production. Cell Metab 2014; 19:155-61. [PMID: 24361011 DOI: 10.1016/j.cmet.2013.11.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 10/08/2013] [Accepted: 11/11/2013] [Indexed: 10/25/2022]
Abstract
The fat-derived hormone leptin binds to its hypothalamic receptors to regulate glucose homeostasis. Leptin is also synthesized in the stomach and subsequently binds to its receptors expressed in the intestine, although the functional relevance of such activation remains largely unknown. We report here that intrajejunal leptin administration activates jejunal leptin receptors and signals through a phosphatidylinositol 3-kinase (PI3K)-dependent and signal transducer and activator of transcription 3 (STAT3)-independent signaling pathway to lower glucose production in healthy rodents. Jejunal leptin action is sufficient to lower glucose production in uncontrolled diabetic and high-fat-fed rodents and contributes to the early antidiabetic effect of duodenal-jejunal bypass surgery. These data unveil a glucoregulatory site of leptin action and suggest that enhancing leptin-PI3K signaling in the jejunum lowers plasma glucose concentrations in diabetes.
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Affiliation(s)
- Brittany A Rasmussen
- Toronto General Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Danna M Breen
- Toronto General Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Frank A Duca
- Toronto General Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Clémence D Côté
- Toronto General Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Melika Zadeh-Tahmasebi
- Toronto General Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Beatrice M Filippi
- Toronto General Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Tony K T Lam
- Toronto General Research Institute, University Health Network, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada.
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Irwin N, Frizelle P, O'Harte FPM, Flatt PR. (pGlu-Gln)-CCK-8[mPEG]: a novel, long-acting, mini-PEGylated cholecystokinin (CCK) agonist that improves metabolic status in dietary-induced diabetes. Biochim Biophys Acta Gen Subj 2013; 1830:4009-16. [PMID: 23583730 DOI: 10.1016/j.bbagen.2013.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 03/29/2013] [Accepted: 04/02/2013] [Indexed: 01/12/2023]
Abstract
BACKGROUND Cholecystokinin (CCK) is a gastrointestinal hormone that has been proposed as a potential therapeutic option for obesity-diabetes. As such, (pGlu-Gln)-CCK-8 is an N-terminally modified CCK-8 analogue with improved biological effectiveness over the native peptide. METHODS The current study has examined the in vitro stability, biological activity and in vivo therapeutic applicability of a novel second generation mini-PEGylated form of (pGlu-Gln)-CCK-8, (pGlu-Gln)-CCK-8[mPEG]. RESULTS (pGlu-Gln)-CCK-8[mPEG] was completely resistant to enzymatic degradation and in addition displayed similar insulinotropic (p<0.05 to p<0.001) and satiating effects (p<0.01 to p<0.001) as (pGlu-Gln)-CCK-8. This confirmed the capability of (pGlu-Gln)-CCK-8[mPEG] to bind to and activate the CCK receptor. Sub-chronic twice daily injection of (pGlu-Gln)-CCK-8[mPEG] in high fat fed mice for 35days significantly decreased body weight gain (p<0.05), food intake (p<0.01 to p<0.001) and triacylglycerol deposition in liver (p<0.001) and muscle (p<0.001). Furthermore, (pGlu-Gln)-CCK-8[mPEG] markedly improved intraperitoneal glucose tolerance (p<0.05) and insulin sensitivity (p<0.001). Despite this therapeutic profile, once daily injection of (pGlu-Gln)-CCK-8[mPEG] in high fat fed mice for 33days, at the same dose, was not associated with alterations in food intake and body weight. In addition, metabolic responses to exogenous glucose and insulin injection were similar to saline treated controls. CONCLUSION These studies emphasise the therapeutic potential of (pGlu-Gln)-CCK-8[mPEG] and similar molecules. GENERAL SIGNIFICANCE A more detailed analysis of the dose and administration schedule employed for (pGlu-Gln)-CCK-8[mPEG] could provide a novel and effective compound to treat obesity-diabetes.
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Affiliation(s)
- Nigel Irwin
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK.
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Irwin N, Montgomery IA, Moffett RC, Flatt PR. Chemical cholecystokinin receptor activation protects against obesity-diabetes in high fat fed mice and has sustainable beneficial effects in genetic ob/ob mice. Biochem Pharmacol 2013; 85:81-91. [DOI: 10.1016/j.bcp.2012.10.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 10/08/2012] [Accepted: 10/09/2012] [Indexed: 12/17/2022]
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The Role of Cholecystokinin Receptors in the Short-Term Control of Food Intake. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 114:277-316. [DOI: 10.1016/b978-0-12-386933-3.00008-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Heldsinger A, Lu Y, Zhou SY, Wu X, Grabauskas G, Song I, Owyang C. Cocaine- and amphetamine-regulated transcript is the neurotransmitter regulating the action of cholecystokinin and leptin on short-term satiety in rats. Am J Physiol Gastrointest Liver Physiol 2012; 303:G1042-51. [PMID: 22936273 PMCID: PMC3517666 DOI: 10.1152/ajpgi.00231.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Vagal CCK-A receptors (CCKARs) and leptin receptors (LRbs) interact synergistically to mediate short-term satiety. Cocaine- and amphetamine-regulated transcript (CART) peptide is expressed by vagal afferent neurons. We sought to demonstrate that this neurotransmitter regulates CCK and leptin actions on short-term satiety. We also examined the signal transduction pathways responsible for mediating the CART release from the nodose ganglia (NG). ELISA studies coupled with gene silencing of NG neurons by RNA interference elucidated intracellular signaling pathways responsible for CCK/leptin-stimulated CART release. Feeding studies followed by gene silencing of CART in NG established the role of CART in mediating short-term satiety. Immunohistochemistry was performed on rat NG neurons to confirm colocalization of CCKARs and LRbs; 63% of these neurons contained CART. Coadministration of CCK-8 and leptin caused a 2.2-fold increase in CART release that was inhibited by CCK-OPE, a low-affinity CCKAR antagonist. Transfection of cultured NG neurons with steroid receptor coactivator (SRC) or phosphatidylinositol 3-kinase (PI3K) small-interfering RNA (siRNA) or STAT3 lentiviral short hairpin RNA inhibited CCK/leptin-stimulated CART release. Silencing the expression of the EGR-1 gene inhibited the CCK/leptin-stimulated CART release but had no effect on CCK/leptin-stimulated neuronal firing. Electroporation of NG with CART siRNA inhibited CCK/leptin stimulated c-Fos expression in rat hypothalamus. Feeding studies following electroporation of the NG with CART or STAT3 siRNA abolished the effects of CCK/leptin on short-term satiety. We conclude that the synergistic interaction of low-affinity vagal CCKARs and LRbs mediates CART release from the NG, and CART is the principal neurotransmitter mediating short-term satiety. CART release from the NG involves interaction between CCK/SRC/PI3K cascades and leptin/JAK2/PI3K/STAT3 signaling pathways.
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Affiliation(s)
- Andrea Heldsinger
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Yuanxu Lu
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Shi-Yi Zhou
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Xiaoyin Wu
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Gintautas Grabauskas
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Il Song
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Chung Owyang
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
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Kinch DC, Peters JH, Simasko SM. Comparative pharmacology of cholecystokinin induced activation of cultured vagal afferent neurons from rats and mice. PLoS One 2012; 7:e34755. [PMID: 22514663 PMCID: PMC3326049 DOI: 10.1371/journal.pone.0034755] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 03/05/2012] [Indexed: 12/18/2022] Open
Abstract
Cholecystokinin (CCK) facilitates the process of satiation via activation of vagal afferent neurons innervating the upper gastrointestinal tract. Recent findings indicate CCK acts on these neurons via a ruthenium red (RuR) sensitive pathway that involves members of the vanilloid (V) subfamily of transient receptor potential (TRP) channels. To further test this mechanism, the mouse provides an ideal model in which genetic tools could be applied. However, whether CCK acts by similar mechanism(s) in mice has not been determined. In the present study we explored the actions of CCK on nodose neurons isolated from Sprague Dawley (SD) rat and two strains of mice; C57BL/6 and BalbC using fluorescence-based calcium imaging. With minor exceptions nodose neurons isolated from all species/strains behaved similarly. They all respond to brief depolarization with a large calcium transient. A significant subset of neurons responded to capsaicin (CAP), a TRPV1 agonist, although neurons from C57BL/6 were 10-fold more sensitive to CAP than SD rats or BalbC mice, and a significantly smaller fraction of neurons from BalbC mice responded to CAP. CCK-8 dose-dependently activated a subpopulation of neurons with similar dose dependency, percent responders, and overlap between CCK and CAP responsiveness. In all species/strains CCK-8 induced activation was significantly attenuated (but not completely blocked) by pretreatment with the TRPV channel blocker RuR. Surprisingly, the CCK analogue JMV-180, which is reported to have pure antagonistic properties in rat but mixed agonist/antagonist properties in mice, behaved as a pure antagonist to CCK in both rat and mouse neurons. The pure antagonistic action of JMV-180 in this in vitro preparation suggests that prior reported differential effects of JMV-180 on satiation in rats versus mouse must be mediated by a site other than vagal afferent activation.
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Affiliation(s)
- Dallas C. Kinch
- Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington, United States of America
| | - James H. Peters
- Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington, United States of America
| | - Steven M. Simasko
- Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington, United States of America
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Intermittent hypoxia and systemic leptin administration induces pSTAT3 and Fos/Fra-1 in the carotid body. Brain Res 2012; 1446:56-70. [DOI: 10.1016/j.brainres.2012.01.074] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 01/19/2012] [Accepted: 01/28/2012] [Indexed: 12/16/2022]
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Abstract
PURPOSE OF REVIEW Cholecystokinin (CCK) controls nutrient delivery to the small intestine by inhibiting food intake and gastric emptying. This review deals with recent work shedding new light on how and when. RECENT FINDINGS Intestinal I-cells release CCK in response to dietary lipid and protein through mechanisms involving the G-protein-coupled receptors GPR40 and calcium-sensing receptor. Vagal afferent neurons are a primary target of CCK and are now recognized as an important site of integration of peripheral signals regulating ingestion. In addition to regulating vagal afferent nerve discharge, CCK also controls the expression of receptors and peptide neurotransmitters by these neurons; these actions are potentiated by leptin and inhibited by ghrelin. The responses of vagal afferent neurons to CCK are attenuated in obesity. Studies of human central nervous system responses using functional magnetic resonance imaging indicate activation of brainstem, hypothalamus and motor cortex by ingested fatty acid that is inhibited by a CCK-1 receptor antagonist. CCK may also play a role in adaptive responses in pancreatic islets by maintaining β-cell mass and acting as an incretin in certain circumstances. SUMMARY CCK mediates inhibition of food intake in response to ingested lipid and protein; resistance to CCK occurs in obesity and may contribute to altered mechanisms regulating food intake.
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Affiliation(s)
- Graham J Dockray
- Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.
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Owyang C, Heldsinger A. Vagal control of satiety and hormonal regulation of appetite. J Neurogastroenterol Motil 2011; 17:338-48. [PMID: 22148102 PMCID: PMC3228973 DOI: 10.5056/jnm.2011.17.4.338] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 09/10/2011] [Accepted: 09/15/2011] [Indexed: 12/27/2022] Open
Abstract
The paradigm for the control of feeding behavior has changed significantly. In this review, we present evidence that the separation of function in which cholecystokinin (CCK) controls short-term food intake and leptin regulate long-term eating behavior and body weight become less clear. In addition to the hypothalamus, the vagus nerve is critically involved in the control of feeding by transmitting signals arising from the upper gut to the nucleus of the solitary tract. Among the peripheral mediators, CCK is the key peptide involved in generating the satiety signal via the vagus. Leptin receptors have also been identified in the vagus nerve. Studies in the rodents clearly indicate that leptin and CCK interact synergistically to induce short-term inhibition of food intake and long-term reduction of body weight. The synergistic interaction between vagal CCK-A receptor and leptin is mediated by the phosphorylation of signal transducer and activator of transcription3 (STAT3), which in turn, activates closure of K(+) channels, leading to membrane depolarization and neuronal firing. This involves the interaction between CCK/SRC/phosphoinositide 3-kinase cascades and leptin/Janus kinase-2/phosphoinositide 3-kinase/STAT3 signaling pathways. It is conceivable that malfunctioning of these signaling molecules may result in eating disorders.
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Affiliation(s)
- Chung Owyang
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA.
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