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Cabral A, Fernandez G, Tolosa MJ, Rey Moggia Á, Calfa G, De Francesco PN, Perello M. Fasting induces remodeling of the orexigenic projections from the arcuate nucleus to the hypothalamic paraventricular nucleus, in a growth hormone secretagogue receptor-dependent manner. Mol Metab 2019; 32:69-84. [PMID: 32029231 PMCID: PMC7005150 DOI: 10.1016/j.molmet.2019.11.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/14/2019] [Accepted: 11/20/2019] [Indexed: 02/06/2023] Open
Abstract
Objective Arcuate nucleus (ARC) neurons producing Agouti-related peptide (AgRP) and neuropeptide Y (NPY; ARCAgRP/NPY neurons) are activated under energy-deficit states. ARCAgRP/NPY neurons innervate the hypothalamic paraventricular nucleus (PVH), and ARC→PVH projections are recognized as key regulators of food intake. Plasma ghrelin levels increase under energy-deficit states and activate ARCAgRP/NPY neurons by acting on the growth hormone secretagogue receptor (GHSR). Here, we hypothesized that activation of ARCAgRP/NPY neurons in fasted mice would promote morphological remodeling of the ARCAgRP/NPY→PVH projections in a GHSR-dependent manner. Methods We performed 1) fluorescent immunohistochemistry, 2) imaging of green fluorescent protein (GFP) signal in NPY-GFP mice, and 3) DiI axonal labeling in brains of ad libitum fed or fasted mice with pharmacological or genetic blockage of the GHSR signaling and then estimated the density and strength of ARCAgRP/NPY→PVH fibers by assessing the mean fluorescence intensity, the absolute area with fluorescent signal, and the intensity of the fluorescent signal in the fluorescent area of the PVH. Results We found that 1) the density and strength of ARCAgRP/NPY fibers increase in the PVH of fasted mice, 2) the morphological remodeling of the ARCAgRP/NPY→PVH projections correlates with the activation of PVH neurons, and 3) PVH neurons are not activated in ARC-ablated mice. We also found that fasting-induced remodeling of ARCAgRP/NPY→PVH fibers and PVH activation are impaired in mice with pharmacological or genetic blockage of GHSR signaling. Conclusion This evidence shows that the connectivity between hypothalamic circuits controlling food intake can be remodeled in the adult brain, depending on the energy balance conditions, and that GHSR activity is a key regulator of this phenomenon. The density and strength of ARCAgRP/NPY→PVH fibers increase in fasted mice. Remodeling of ARCAgRP/NPY→PVH projections correlates with the activation of PVH neurons. GHSR signaling is required for fasting-induced ARCAgRP/NPY→PVH projection remodeling.
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Affiliation(s)
- Agustina Cabral
- Laboratorio de Neurofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional La Plata y Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC-PBA), La Plata, Buenos Aires, Argentina
| | - Gimena Fernandez
- Laboratorio de Neurofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional La Plata y Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC-PBA), La Plata, Buenos Aires, Argentina
| | - María J Tolosa
- Laboratorio de Neurofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional La Plata y Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC-PBA), La Plata, Buenos Aires, Argentina
| | - Ángeles Rey Moggia
- Laboratorio de Neurofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional La Plata y Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC-PBA), La Plata, Buenos Aires, Argentina
| | - Gastón Calfa
- Instituto de Farmacología Experimental de Córdoba (IFEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Pablo N De Francesco
- Laboratorio de Neurofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional La Plata y Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC-PBA), La Plata, Buenos Aires, Argentina
| | - Mario Perello
- Laboratorio de Neurofisiología, Instituto Multidisciplinario de Biología Celular (IMBICE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional La Plata y Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC-PBA), La Plata, Buenos Aires, Argentina.
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McFadden JW, Aja S, Li Q, Bandaru VVR, Kim EK, Haughey NJ, Kuhajda FP, Ronnett GV. Increasing fatty acid oxidation remodels the hypothalamic neurometabolome to mitigate stress and inflammation. PLoS One 2014; 9:e115642. [PMID: 25541737 PMCID: PMC4277346 DOI: 10.1371/journal.pone.0115642] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 11/25/2014] [Indexed: 11/18/2022] Open
Abstract
Modification of hypothalamic fatty acid (FA) metabolism can improve energy homeostasis and prevent hyperphagia and excessive weight gain in diet-induced obesity (DIO) from a diet high in saturated fatty acids. We have shown previously that C75, a stimulator of carnitine palmitoyl transferase-1 (CPT-1) and fatty acid oxidation (FAOx), exerts at least some of its hypophagic effects via neuronal mechanisms in the hypothalamus. In the present work, we characterized the effects of C75 and another anorexigenic compound, the glycerol-3-phosphate acyltransferase (GPAT) inhibitor FSG67, on FA metabolism, metabolomics profiles, and metabolic stress responses in cultured hypothalamic neurons and hypothalamic neuronal cell lines during lipid excess with palmitate. Both compounds enhanced palmitate oxidation, increased ATP, and inactivated AMP-activated protein kinase (AMPK) in hypothalamic neurons in vitro. Lipidomics and untargeted metabolomics revealed that enhanced catabolism of FA decreased palmitate availability and prevented the production of fatty acylglycerols, ceramides, and cholesterol esters, lipids that are associated with lipotoxicity-provoked metabolic stress. This improved metabolic signature was accompanied by increased levels of reactive oxygen species (ROS), and yet favorable changes in oxidative stress, overt ER stress, and inflammation. We propose that enhancing FAOx in hypothalamic neurons exposed to excess lipids promotes metabolic remodeling that reduces local inflammatory and cell stress responses. This shift would restore mitochondrial function such that increased FAOx can produce hypothalamic neuronal ATP and lead to decreased food intake and body weight to improve systemic metabolism.
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Affiliation(s)
- Joseph W. McFadden
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Susan Aja
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
| | - Qun Li
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Veera V. R. Bandaru
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Eun-Kyoung Kim
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Norman J. Haughey
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Francis P. Kuhajda
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Gabriele V. Ronnett
- Center for Metabolism and Obesity Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
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The central administration of C75, a fatty acid synthase inhibitor, activates sympathetic outflow and thermogenesis in interscapular brown adipose tissue. Pflugers Arch 2013; 465:1687-99. [PMID: 23827961 DOI: 10.1007/s00424-013-1301-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 05/13/2013] [Accepted: 05/15/2013] [Indexed: 12/20/2022]
Abstract
The present work investigated the participation of interscapular brown adipose tissue (IBAT), which is an important site for thermogenesis, in the anti-obesity effects of C75, a synthetic inhibitor of fatty acid synthase (FAS). We report that a single intracerebroventricular (i.c.v.) injection of C75 induced hypophagia and weight loss in fasted male Wistar rats. Furthermore, C75 induced a rapid increase in core body temperature and an increase in heat dissipation. In parallel, C75 stimulated IBAT thermogenesis, which was evidenced by a marked increase in the IBAT temperature that preceded the rise in the core body temperature and an increase in the mRNA levels of uncoupling protein-1. As with C75, an i.c.v. injection of cerulenin, a natural FAS inhibitor, increased the core body and IBAT temperatures. The sympathetic IBAT denervation attenuated all of the thermoregulatory effects of FAS inhibitors as well as the C75 effect on weight loss and hypophagia. C75 induced the expression of Fos in the paraventricular nucleus, preoptic area, dorsomedial nucleus, ventromedial nucleus, and raphé pallidus, all of which support a central role of FAS in regulating IBAT thermogenesis. These data indicate a role for IBAT in the increase in body temperature and hypophagia that is induced by FAS inhibitors and suggest new mechanisms explaining the weight loss induced by these compounds.
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The receptive function of hypothalamic and brainstem centres to hormonal and nutrient signals affecting energy balance. Proc Nutr Soc 2012; 71:463-77. [PMID: 22931748 DOI: 10.1017/s0029665112000778] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The hypothalamic arcuate nucleus (ARC) and the area postrema (AP) represent targets for hormonal and metabolic signals involved in energy homoeostasis, e.g. glucose, amylin, insulin, leptin, peptide YY (PYY), glucagon-like peptide 1 (GLP-1) and ghrelin. Orexigenic neuropeptide Y expressing ARC neurons are activated by food deprivation and inhibited by feeding in a nutrient-dependent manner. PYY and leptin also reverse or prevent fasting-induced activation of the ARC. Interestingly, hypothalamic responses to fasting are blunted in different models of obesity (e.g. diet-induced obesity (DIO) or late-onset obesity). The AP also responds to feeding-related signals. The pancreatic hormone amylin acts via the AP to control energy intake. Amylin-sensitive AP neurons are also glucose-responsive. Furthermore, diet-derived protein attenuates amylin responsiveness suggesting a modulation of AP sensitivity by macronutrient supply. This review gives an overview of the receptive function of the ARC and the AP to hormonal and nutritional stimuli involved in the control of energy balance and the possible implications in the context of obesity. Collectively, there is consistency between the neurophysiological actions of these stimuli and their effects on energy homoeostasis under experimental conditions. However, surprisingly little progress has been made in the development of effective pharmacological approaches against obesity. A promising way to improve effectiveness involves combination treatments (e.g. amylin/leptin agonists). Hormonal alterations (e.g. GLP-1 and PYY) are also considered to mediate body weight loss observed in obese patients receiving bariatric surgery. The effects of hormonal and nutritional signals and their interactions might hold the potential to develop poly-mechanistic therapeutic strategies against obesity.
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Lee DA, Bedont JL, Pak T, Wang H, Song J, Miranda-Angulo A, Takiar V, Charubhumi V, Balordi F, Takebayashi H, Aja S, Ford E, Fishell G, Blackshaw S. Tanycytes of the hypothalamic median eminence form a diet-responsive neurogenic niche. Nat Neurosci 2012; 15:700-2. [PMID: 22446882 PMCID: PMC3380241 DOI: 10.1038/nn.3079] [Citation(s) in RCA: 351] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 03/01/2012] [Indexed: 01/02/2023]
Abstract
Adult hypothalamic neurogenesis has been recently reported, but the cell of origin and function of these newborn neurons are unknown. We utilize genetic fate mapping to show that median eminence tanycytes generate newborn neurons; blocking this neurogenesis alters weight and metabolic activity in adult mice. These findings describe a previously unreported neurogenic niche within the mammalian hypothalamus with important implications for metabolism.
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Affiliation(s)
- Daniel A Lee
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Hankir MK, Parkinson JRC, Minnion JS, Addison ML, Bloom SR, Bell JD. Peptide YY 3-36 and pancreatic polypeptide differentially regulate hypothalamic neuronal activity in mice in vivo as measured by manganese-enhanced magnetic resonance imaging. J Neuroendocrinol 2011; 23:371-80. [PMID: 21251093 DOI: 10.1111/j.1365-2826.2011.02111.x] [Citation(s) in RCA: 21] [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: 01/01/2023]
Abstract
Peptide YY (PYY) and pancreatic polypeptide (PP) are two appetite suppressing hormones, released post-prandially from the ileum and pancreas, respectively. PYY(3-36) , the major circulating form of the peptide, is considered to reduce food intake in humans and rodents via high affinity binding to the auto-inhibitory neuropeptide Y receptor Y2R, whereas PP is considered to act through the Y4R. Current evidence indicates the anorexigenic effects of both peptides occur via signalling in the brainstem and arcuate nucleus (ARC) of the hypothalamus. Manganese-enhanced magnetic resonance imaging (MEMRI) has previously been used to track hypothalamic neuronal activity in vivo in response to both nutritional interventions and gut hormone treatment. In the present study, we used MEMRI to demonstrate that s.c. administration of PP results in a significant reduction in signal intensity (SI) in the ARC, ventromedial hypothalamus and paraventricular nucleus of fasted mice. Subcutaneous delivery of PYY(3-36) resulted in a nonsignificant trend towards decreased SI in the hypothalamus of fasted mice. We found no SI change in the area postrema of the brainstem after s.c. injection of either peptide. These differences in hypothalamic SI profile between PP and PYY(3-36) occurred despite both peptides producing a comparable reduction in food intake. These results suggest that separate central pathways control the anorexigenic response for PP and PYY(3-36) , possibly via a differential effect of Y4 receptor versus Y2 receptor signalling. In addition, we performed a series of MEMRI scans at 0-2, 2-4 and 4-6 h post-injection of PYY(3-36) and a potent analogue of the peptide; PYY(3-36) (LT). We recorded a significant reduction in the ARC SI 2-4 h after PYY(3-36) (LT) injection compared to both saline and PYY(3-36) in fasted mice. The physiological differences between PYY(3-36) and its analogue were also observed in the long-term effects on food intake, with PYY(3-36) (LT) producing a more sustained anorexigenic effect. These data suggest that MEMRI can be used to investigate the long-term effects of gut peptide delivery on activity within the hypothalamus and brainstem.
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Affiliation(s)
- M K Hankir
- Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
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Blouet C, Schwartz GJ. Hypothalamic nutrient sensing in the control of energy homeostasis. Behav Brain Res 2009; 209:1-12. [PMID: 20035790 DOI: 10.1016/j.bbr.2009.12.024] [Citation(s) in RCA: 196] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Accepted: 12/16/2009] [Indexed: 12/15/2022]
Abstract
The hypothalamus is a center of convergence and integration of multiple nutrient-related signals. It can sense changes in circulating adiposity hormones, gastric hormones and nutrients, and receives neuroanatomical projections from other nutrient sensors, mainly within the brainstem. The hypothalamus also integrates these signals with various cognitive forebrain-descending information and reward/motivation-related signals coming from the midbrain-dopamine system, to coordinate neuroendocrine, behavioral and metabolic effectors of energy balance. Some of the key nutrient-sensing hypothalamic neurons have been identified in the arcuate, the ventro-medial and the lateral nuclei of the hypothalamus, and the molecular mechanisms underlying intracellular integration of nutrient-related signals in these neurons are currently under intensive investigation. However, little is known about the neural pathways downstream from hypothalamic nutrient sensors, and how they drive effectors of energy homeostasis under physiological conditions. This manuscript will review recent progress from molecular, genetic and neurophysiological studies that identify and characterize the critical intracellular signalling pathways and neurocircuits involved in determining hypothalamic nutrient detection, and link these circuits to behavioral and metabolic effectors of energy balance. We will provide a critical analysis of current data to identify ongoing challenges for future research in this field.
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Affiliation(s)
- Clémence Blouet
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
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Differential patterns of neuronal activation in the brainstem and hypothalamus following peripheral injection of GLP-1, oxyntomodulin and lithium chloride in mice detected by manganese-enhanced magnetic resonance imaging (MEMRI). Neuroimage 2008; 44:1022-31. [PMID: 18983926 DOI: 10.1016/j.neuroimage.2008.09.047] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 09/02/2008] [Accepted: 09/23/2008] [Indexed: 01/01/2023] Open
Abstract
We have used manganese-enhanced magnetic resonance imaging (MEMRI) to show distinct patterns of neuronal activation within the hypothalamus and brainstem of fasted mice in response to peripheral injection of the anorexigenic agents glucagon-like peptide-1 (GLP-1), oxyntomodulin (OXM) and lithium chloride. Administration of both GLP-1 and OXM resulted in a significant increase in signal intensity (SI) in the area postrema of fasted mice, reflecting an increase in neuronal activity within the brainstem. In the hypothalamus, GLP-1 administration induced a significant reduction in SI in the paraventricular nucleus and an increase in the ventromedial hypothalamic nucleus whereas OXM reduced SI in the arcuate and supraoptic nuclei of the hypothalamus. These data indicate that whilst these related peptides both induce a similar effect on neuronal activity in the brainstem they generate distinct patterns of activation within the hypothalamus. Furthermore, the hypothalamic pattern of signal intensity generated by GLP-1 closely matches that generated by peripheral injection of LiCl, suggesting the anorexigenic effects of GLP-1 may be in part transmitted via nausea circuits. This work provides a framework by which the temporal effects of appetite modulating agents can be recorded simultaneously within hypothalamic and brainstem feeding centres.
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Mansouri A, Aja S, Moran TH, Ronnett G, Kuhajda FP, Arnold M, Geary N, Langhans W, Leonhardt M. Intraperitoneal injections of low doses of C75 elicit a behaviorally specific and vagal afferent-independent inhibition of eating in rats. Am J Physiol Regul Integr Comp Physiol 2008; 295:R799-805. [PMID: 18667714 DOI: 10.1152/ajpregu.90381.2008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Central and intraperitoneal C75, an inhibitor of fatty acid synthase and stimulator of carnitine palmitoyl-transferase-1, inhibits eating in mice and rats. Mechanisms involved in feeding inhibition after central C75 have been identified, but little is yet known about how systemic C75 might inhibit eating. One issue is whether intraperitoneal C75 reduces food intake in rats by influencing normal physiological controls of food intake or acts nonselectively, for example by eliciting illness or aversion. Another issue relates to whether intraperitoneal C75 acts centrally or, similar to some other peripheral metabolic controls of eating, activates abdominal vagal afferents to inhibit eating. To further address these questions, we investigated the effects of intraperitoneal C75 on spontaneous meal patterns and the formation of conditioned taste aversion (CTA). We also tested whether the eating inhibitory effect of intraperitoneal C75 is vagally mediated by testing rats after either total subdiaphragmatic vagotomy (TVX) or selective subdiaphragmatic vagal deafferentations (SDA). Intraperitoneal injection of 3.2 and 7.5 mg/kg of C75 significantly reduced food intake 3, 12, and 24 h after injection by reducing the number of meals without affecting meal size, whereas 15 mg/kg of C75 reduced both meal number and meal size. The two smaller doses of C75 failed to induce a CTA, but 15 mg/kg C75 did. The eating inhibitory effect of C75 was not diminished in either TVX or SDA rats. We conclude that intraperitoneal injections of low doses of C75 inhibit eating in a behaviorally specific manner and that this effect does not require abdominal vagal afferents.
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Affiliation(s)
- Abdelhak Mansouri
- Physiology and Behaviour Group, Institute of Animal Sciences, ETH Zurich, Schwerzenbach, Switzerland
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Becskei C, Riediger T, Hernádfalvy N, Arsenijevic D, Lutz TA, Langhans W. Inhibitory effects of lipopolysaccharide on hypothalamic nuclei implicated in the control of food intake. Brain Behav Immun 2008; 22:56-64. [PMID: 17624718 DOI: 10.1016/j.bbi.2007.06.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 06/01/2007] [Accepted: 06/02/2007] [Indexed: 10/23/2022] Open
Abstract
The arcuate nucleus (Arc) and the lateral hypothalamic area (LHA), two key hypothalamic nuclei regulating feeding behavior, express c-Fos, a marker of neuronal activation in fasted animals. This is reversed by refeeding. In the present study we tested whether an anorectic dose of lipopolysaccharide (LPS), the cell wall component of Gram-negative bacteria, also inhibits fasting-induced c-Fos expression in these hypothalamic nuclei. This would suggest that they are involved in anorexia during bacterial infections as well. We also studied whether LPS modulates the activity of orexin-A positive (OX+) LHA neurons. Food deprived BALB/c mice were injected with LPS or saline and were sacrificed 4 or 6h later. Four hours after injection, LPS reduced the number of c-Fos positive cells in the Arc and in the LHA, but had no effect on c-Fos in OX+ neurons. Six hours after injection, LPS reduced c-Fos expression in the LHA, both in the OX- and OX+ neurons, but not in the Arc. These results show that LPS modulates neuronal activity in the Arc and LHA similar to feeding-related stimuli, suggesting that the observed effects might contribute to the anorectic effect of LPS. Thus, physiological satiety signals released during refeeding and anorexia during bacterial infection seem to engage similar neuronal substrates.
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Affiliation(s)
- Csilla Becskei
- Institute of Veterinary Physiology and Zurich Centre of Human Integrative Physiology, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
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Aja S, Bi S, Knipp SB, McFadden JM, Ronnett GV, Kuhajda FP, Moran TH. Intracerebroventricular C75 decreases meal frequency and reduces AgRP gene expression in rats. Am J Physiol Regul Integr Comp Physiol 2006; 291:R148-54. [PMID: 16484442 DOI: 10.1152/ajpregu.00041.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
3-Carboxy-4-alkyl-2-methylenebutyrolactone (C75), an inhibitor of fatty acid synthase and stimulator of carnitine palmitoyltransferase-1, reduces food intake and body weight in rodents when given systemically or centrally. Intracellular molecular mechanisms involving changes in cellular energy status are proposed to initiate the feeding and body weight reductions. However, effectors that lie downstream of these initial steps are not yet fully identified. Present experiments characterize the time courses of hypophagia and weight loss after single injections of C75 into the lateral cerebroventicle in rats and go on to identify specific meal pattern changes and coinciding alterations in gene expression for feeding-related hypothalamic neuropeptides. C75 reduced chow intake and body weight dose dependently. Although the principal effects occurred on the first day, weight losses relative to vehicle control were maintained over multiple days. C75 did not affect generalized locomotor activity. C75 began to reduce feeding after a 6-h delay. The hypophagia was due primarily to decreased meal number during 6–12 h without a significant effect on meal size, suggesting that central C75 reduced the drive to initiate meals. C75 prevented the anticipated hypophagia-induced increases in mRNA for AgRP in the arcuate nucleus at 22 h and at 6 h when C75 begins to suppress feeding. Overall, the data suggest that gene expression changes leading to altered melanocortin signaling are important for the hypophagic response to intracerebroventricular C75.
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Affiliation(s)
- Susan Aja
- Department of Psychiatry and Behavioural Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Wang R, Cruciani-Guglielmacci C, Migrenne S, Magnan C, Cotero VE, Routh VH. Effects of Oleic Acid on Distinct Populations of Neurons in the Hypothalamic Arcuate Nucleus Are Dependent on Extracellular Glucose Levels. J Neurophysiol 2006; 95:1491-8. [PMID: 16306178 DOI: 10.1152/jn.00697.2005] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pharmacological manipulation of fatty acid metabolism in the hypothalamic arcuate nucleus (ARC) alters energy balance and glucose homeostasis. Thus, we tested the hypotheses that distinctive populations of ARC neurons are oleic acid (OA) sensors that exhibit a glucose dependency, independent of whether some of these OA sensors are also glucose-sensing neurons. We used patch-clamp recordings to investigate the effects of OA on ARC neurons in brain slices from 14- to 21-day-old Sprague–Dawley (SD) rats. Additionally, we recorded spontaneous discharge rate in ARC neurons in 8-wk-old fed and fasted SD rats in vivo. Patch-clamp studies showed that in 2.5 mM glucose 12 of 94 (13%) ARC neurons were excited by 2 μM OA (OA-excited or OAE neurons), whereas six of 94 (6%) were inhibited (OA-inhibited2.5or OAI2.5neurons). In contrast, in 0.1 mM glucose, OA inhibited six of 20 (30%) ARC neurons (OAI0.1neurons); none was excited. None of the OAI0.1neurons responded to OA in 2.5 mM glucose. Thus OAI2.5and OAI0.1neurons are distinct. Similarly, in seven of 20 fed rats (35%) the overall response was OAE-like, whereas in three of 20 (15%) it was OAI-like. In contrast, in fasted rats only OAI-like response were observed (three of 15; 20%). There was minimal overlap between OA-sensing neurons and glucose-sensing neurons. In conclusion, OA regulated three distinct subpopulations of ARC neurons in a glucose-dependent fashion. These data suggest that an interaction between glucose and fatty acids regulates OA sensing in ARC neurons.
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Affiliation(s)
- R Wang
- Department of Pharmacology and Physiology, New Jersey Medical School, 185 S. Orange Ave, PO Box 1709, Newark, NJ 07101-1709, USA
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Kuhajda FP, Landree LE, Ronnett GV. The connections between C75 and obesity drug-target pathways. Trends Pharmacol Sci 2005; 26:541-4. [PMID: 16169094 DOI: 10.1016/j.tips.2005.09.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 07/27/2005] [Accepted: 09/02/2005] [Indexed: 11/21/2022]
Abstract
Obesity and its attendant disorders, such as Type II diabetes, have reached epidemic proportions in the USA, and their prevalence is increasing globally. C75 is a small-molecule inhibitor of fatty acid synthase (FAS) and a stimulator of carnitine palmitoyl 1 activity, which causes profound weight loss in mice. Although C75 is not a compound that is destined for human drug development, it has provided two potential pathways to target in obesity therapy: fatty acid synthesis and fatty acid oxidation. In this article, we discuss the latest data challenging the relationship between fatty acid synthase inhibition and C75-induced anorexia.
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Affiliation(s)
- Francis P Kuhajda
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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14
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Abstract
Selective regions of the brain, including the hypothalamus, are capable of gathering information on the body's nutritional status in order to implement appropriate behavioral and metabolic responses to changes in fuel availability. This review focuses on direct metabolic signaling within the hypothalamus. There is growing evidence supporting the idea that fatty acid metabolism within discrete hypothalamic regions can function as a sensor for nutrient availability that can integrate multiple nutritional and hormonal signals.
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Affiliation(s)
- Tony K T Lam
- Department of Medicine and Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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15
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Rohrbach KW, Han S, Gan J, O'Tanyi EJ, Zhang H, Chi CL, Taub R, Largent BL, Cheng D. Disconnection between the early onset anorectic effects by C75 and hypothalamic fatty acid synthase inhibition in rodents. Eur J Pharmacol 2005; 511:31-41. [PMID: 15777777 DOI: 10.1016/j.ejphar.2005.01.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Accepted: 01/18/2005] [Indexed: 10/25/2022]
Abstract
In order to explore the relationship between the anorectic effect of 3-carboxy-4-octyl-2-methylenebutyrolactone (C75) and its pharmacokinetic properties, studies of in vivo and in vitro pharmacological characterization of C75 were performed in Fischer rats. In a quantitative measurement of food intake, we determined that appetite suppression by C75 takes place within 4 h. The C(max) for C75 of 2.6+/-1.5 microM was reached within 1-4 h after intraperitoneal administration at 30 mg/kg, a drug level that causes complete blockade of food intake. However, this concentration is substantially lower than the effective concentration used to inhibit rat fatty acid synthase enzyme activity in vitro (IC50: approximately 200 microM) and hypothalamic enzyme activity was found not to be inhibited by intraperitoneal administration of C75 at 30 mg/kg. Instead, a dramatic induction of c-Fos expression was found in area postrema. Collectively, these data indicate that the anorectic effect of C75 is independent of its inhibition of fatty acid synthase in the hypothalamus.
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Affiliation(s)
- Kenneth W Rohrbach
- Pharmaceutical Research Institute, Department of Metabolic Disease, Bristol-Myers Squibb Company, Princeton, NJ 08543, USA
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