201
|
Schaller F, Watrin F, Sturny R, Massacrier A, Szepetowski P, Muscatelli F. A single postnatal injection of oxytocin rescues the lethal feeding behaviour in mouse newborns deficient for the imprinted Magel2 gene. Hum Mol Genet 2010; 19:4895-905. [DOI: 10.1093/hmg/ddq424] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Fabienne Schaller
- Institute of Biology of Development of Marseille Luminy, CNRS UMR 6126 and
- Mediterranean Institute of Neurobiology (INMED), INSERM U901, Parc Scientifique de Luminy, BP 13, 13273 Marseille Cedex 09, France and
- Université de la Méditerranée, UMR S901 Aix-Marseille 2, 13009Marseille, France
| | - Françoise Watrin
- Institute of Biology of Development of Marseille Luminy, CNRS UMR 6126 and
- Mediterranean Institute of Neurobiology (INMED), INSERM U901, Parc Scientifique de Luminy, BP 13, 13273 Marseille Cedex 09, France and
- Université de la Méditerranée, UMR S901 Aix-Marseille 2, 13009Marseille, France
| | - Rachel Sturny
- Institute of Biology of Development of Marseille Luminy, CNRS UMR 6126 and
- Université de la Méditerranée, UMR S901 Aix-Marseille 2, 13009Marseille, France
| | - Annick Massacrier
- Mediterranean Institute of Neurobiology (INMED), INSERM U901, Parc Scientifique de Luminy, BP 13, 13273 Marseille Cedex 09, France and
- Université de la Méditerranée, UMR S901 Aix-Marseille 2, 13009Marseille, France
| | - Pierre Szepetowski
- Mediterranean Institute of Neurobiology (INMED), INSERM U901, Parc Scientifique de Luminy, BP 13, 13273 Marseille Cedex 09, France and
- Université de la Méditerranée, UMR S901 Aix-Marseille 2, 13009Marseille, France
| | - Françoise Muscatelli
- Institute of Biology of Development of Marseille Luminy, CNRS UMR 6126 and
- Mediterranean Institute of Neurobiology (INMED), INSERM U901, Parc Scientifique de Luminy, BP 13, 13273 Marseille Cedex 09, France and
- Université de la Méditerranée, UMR S901 Aix-Marseille 2, 13009Marseille, France
| |
Collapse
|
202
|
Direct innervation and modulation of orexin neurons by lateral hypothalamic LepRb neurons. J Neurosci 2010; 30:11278-87. [PMID: 20739548 DOI: 10.1523/jneurosci.1340-10.2010] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Leptin, the adipose-derived hormonal signal of body energy stores, acts via the leptin receptor (LepRb) on neurons in multiple brain regions. We previously identified LepRb neurons in the lateral hypothalamic area (LHA), which are distinct from neighboring leptin-regulated melanin-concentrating hormone (MCH)- or orexin (OX)-expressing cells. Neither the direct synaptic targets of LHA LepRb neurons nor their potential role in the regulation of other LHA neurons has been determined, however. We thus generated several adenoviral and transgenic systems in which cre recombinase promotes the expression of the tracer, WGA (wheat germ agglutinin), and used these in combination with LepRb(cre) mice to determine the neuronal targets of LHA LepRb neurons. This analysis revealed that, although some LHA LepRb neurons project to dopamine neurons in the ventral tegmental area, LHA LepRb neurons also densely innervate the LHA where they directly synapse with OX, but not MCH, neurons. Indeed, few other LepRb neurons in the brain project to the OX-containing region of the mouse LHA, and direct leptin action via LHA LepRb neurons regulates gene expression in OX neurons. These findings thus reveal a major role for LHA leptin action in the modulation of OX neurons, suggesting the importance of LHA LepRb neurons in the regulation of OX signaling that is crucial to leptin action and metabolic control.
Collapse
|
203
|
Gray SL, Donald C, Jetha A, Covey SD, Kieffer TJ. Hyperinsulinemia precedes insulin resistance in mice lacking pancreatic beta-cell leptin signaling. Endocrinology 2010; 151:4178-86. [PMID: 20631001 DOI: 10.1210/en.2010-0102] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The adipocyte hormone leptin acts centrally and peripherally to regulate body weight and glucose homeostasis. The pancreatic beta-cell has been shown to be a key peripheral target of leptin, with leptin suppressing insulin synthesis and secretion from beta-cells both in vitro and in vivo. Mice with disrupted leptin signaling in beta-cells (lepr(flox/flox) RIPcre tg+ mice) display hyperinsulinemia, insulin resistance, glucose intolerance, obesity, and reduced fasting blood glucose. We hypothesized that hyperinsulinemia precedes the development of insulin resistance and increased adiposity in these mice with a defective adipoinsular axis. To determine the primary defect after impaired beta-cell leptin signaling, we treated lepr(flox/flox) RIPcre tg+ mice with the insulin sensitizer metformin or the insulin-lowering agent diazoxide with the rationale that pharmacological improvement of the primary defect would alleviate the secondary symptoms. We show that improving insulin sensitivity with metformin does not normalize hyperinsulinemia, whereas lowering insulin levels with diazoxide improves insulin sensitivity. Taken together, these results suggest that hyperinsulinemia precedes insulin resistance in beta-cell leptin receptor-deficient mice, with insulin resistance developing as a secondary consequence of excessive insulin secretion. Therefore, pancreatic beta-cell leptin receptor-deficient mice may represent a model of obesity-associated insulin resistance that is initiated by hyperinsulinemia.
Collapse
Affiliation(s)
- Sarah L Gray
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, 2350 Health Sciences Mall, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | | | | | | | | |
Collapse
|
204
|
Abstract
A novel mechanism explains how exercise exerts its beneficial effects on energy balance through an effect at the level of the hypothalamus.
Collapse
Affiliation(s)
- Pablo Blanco Martínez de Morentin
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Miguel López
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
- * E-mail:
| |
Collapse
|
205
|
Leinninger GM. Location, location, location: the CNS sites of leptin action dictate its regulation of homeostatic and hedonic pathways. Int J Obes (Lond) 2010; 33 Suppl 2:S14-7. [PMID: 19528973 DOI: 10.1038/ijo.2009.66] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The increasing incidence of obesity and obesity-linked disease presents a serious global health threat. To develop truly effective therapies to modulate food intake and promote weight loss, we must understand the physiological regulators that underlie these processes. One crucial mediator of food intake and energy homeostasis is the adipose-derived hormone, leptin, which acts through neurons expressing the long form of the leptin receptor (LepRb). Although most investigation of leptin action has centered on the large population of LepRb neurons in the arcuate nucleus (ARC), this nucleus does not mediate all aspects of leptin action. Indeed, several hypothalamic and extrahypothalamic loci contain substantial numbers of LepRb neurons, each of which presumably mediates distinct aspects of leptin action, and the collective output of these various LepRb populations produces the totality of leptin function. This review will examine known central nervous system loci that contain LepRb neurons and the potential roles for discrete populations of LepRb neurons in the control of homeostatic and hedonic pathways by leptin. Understanding the unique neuroanatomical and functional roles for each locus of leptin action will be important to identify how specific aspects of food intake contribute to obesity.
Collapse
Affiliation(s)
- G M Leinninger
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109-0678, USA.
| |
Collapse
|
206
|
Ramanjaneya M, Chen J, Brown JE, Tripathi G, Hallschmid M, Patel S, Kern W, Hillhouse EW, Lehnert H, Tan BK, Randeva HS. Identification of nesfatin-1 in human and murine adipose tissue: a novel depot-specific adipokine with increased levels in obesity. Endocrinology 2010; 151:3169-80. [PMID: 20427481 DOI: 10.1210/en.2009-1358] [Citation(s) in RCA: 230] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Nesfatin-1 is a recently identified anorexigenic peptide derived from its precursor protein, nonesterified fatty acid/nucleobindin 2 (NUCB2). Although the hypothalamus is pivotal for the maintenance of energy homeostasis, adipose tissue plays an important role in the integration of metabolic activity and energy balance by communicating with peripheral organs and the brain via adipokines. Currently no data exist on nesfatin-1 expression, regulation, and secretion in adipose tissue. We therefore investigated NUCB2/nesfatin-1 gene and protein expression in human and murine adipose tissue depots. Additionally, the effects of insulin, dexamethasone, and inflammatory cytokines and the impact of food deprivation and obesity on nesfatin-1 expression were studied by quantitative RT-PCR and Western blotting. We present data showing NUCB2 mRNA (P < 0.001), nesfatin-1 intracellular protein (P < 0.001), and secretion (P < 0.01) were significantly higher in sc adipose tissue compared with other depots. Also, nesfatin-1 protein expression was significantly increased in high-fat-fed mice (P < 0.01) and reduced under food deprivation (P < 0.01) compared with controls. Stimulation of sc adipose tissue explants with inflammatory cytokines (TNFalpha and IL-6), insulin, and dexamethasone resulted in a marked increase in intracellular nesfatin-1 levels. Furthermore, we present evidence that the secretion of nesfatin-1 into the culture media was dramatically increased during the differentiation of 3T3-L1 preadipocytes into adipocytes (P < 0.001) and after treatments with TNF-alpha, IL-6, insulin, and dexamethasone (P < 0.01). In addition, circulating nesfatin-1 levels were higher in high-fat-fed mice (P < 0.05) and showed positive correlation with body mass index in human. We report that nesfatin-1 is a novel depot specific adipokine preferentially produced by sc tissue, with obesity- and food deprivation-regulated expression.
Collapse
Affiliation(s)
- Manjunath Ramanjaneya
- Endocrinology and Metabolism Group, Clinical Sciences Research Institute, Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
207
|
Yao Y, Li XB, Zhao W, Zeng YY, Shen H, Xiang H, Xiao H. Anti-obesity effect of an isoflavone fatty acid ester on obese mice induced by high fat diet and its potential mechanism. Lipids Health Dis 2010; 9:49. [PMID: 20482839 PMCID: PMC2889992 DOI: 10.1186/1476-511x-9-49] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 05/19/2010] [Indexed: 12/26/2022] Open
Abstract
Background The novel compound 1a is one of the isoflavone fatty acid esters. In order to investigate the anti-obesity effect of compound 1a and its potential mechanism of influence in adipocyte differentiation, Obese male C57BL/6J mice induced by high-fat diet (HFD) and rat preadipocytes (3T3-L1 cell) were used. Methods After 4-week HFD induction, the obese model was made successfully. After treatment with compound 1a, mice plasma biochemistry parameters were analyzed. In addition, mice hepatic tissue slice was observed. In in vitro research, 3T3-L1 cell differentiation by Oil-Red-O staining and adipocyte apoptosis was detected by flow cytometry. Results The in vivo results implied that compound 1a significantly decreased the body weight, white adipose tissue weight of obesity mice(p < 0.05), reduced leptin and TG in plasma(p < 0.05), elevated HDL-C in serum(p < 0.05). The in vitro results suggested that compound 1a could significantly suppress the adipocyte viability and lipid accumulation in the differentiation of preadipocyte, and induce apoptosis in both preadipocytes and mature adipocytes(p < 0.05). Conclusion Compound 1a regulates serum lipid profiles, decreases adipose tissue mass and body weight gain by inducing adipocyte apoptosis in high fat diet induced mice. Thus, it may be used to treat obese patients with hypercholesterolemia and hypertriglyceridemia.
Collapse
Affiliation(s)
- Yao Yao
- Nanjing Brain Hospital affiliated to Nanjing Medical University, Nanjing 210029, PR China
| | | | | | | | | | | | | |
Collapse
|
208
|
Mullier A, Bouret SG, Prevot V, Dehouck B. Differential distribution of tight junction proteins suggests a role for tanycytes in blood-hypothalamus barrier regulation in the adult mouse brain. J Comp Neurol 2010; 518:943-62. [PMID: 20127760 DOI: 10.1002/cne.22273] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The median eminence is one of the seven so-called circumventricular organs. It is located in the basal hypothalamus, ventral to the third ventricle and adjacent to the arcuate nucleus. This structure characteristically contains a rich capillary plexus and features a fenestrated endothelium, making it a direct target of blood-borne molecules. The median eminence also contains highly specialized ependymal cells called tanycytes, which line the floor of the third ventricle. It has been hypothesized that one of the functions of these cells is to create a barrier that prevents substances in the portal capillary spaces from entering the brain. In this paper, we utilize immunohistochemistry to study the expression of tight junction proteins in the cells that compose the median eminence in adult mice. Our results indicate that tanycytes of the median eminence express occludin, ZO-1, and claudin 1 and 5, but not claudin 3. Remarkably, these molecules are organized as a continuous belt around the cell bodies of the tanycytes that line the ventral part of the third ventricle. In contrast, the tanycytes at the periphery of the arcuate nucleus do not express claudin 1 and instead exhibit a disorganized expression pattern of occludin, ZO-1, and claudin 5. Consistent with these observations, permeability studies using peripheral or central injections of Evans blue dye show that only the tanycytes of the median eminence are joined at their apices by functional tight junctions, whereas tanycytes located at the level of the arcuate nucleus form a permeable layer. In conclusion, this study reveals a unique expression pattern of tight junction proteins in hypothalamic tanycytes, which yields new insights into their barrier properties.
Collapse
Affiliation(s)
- Amandine Mullier
- Jean-Pierre Aubert Research Center, Development and Plasticity of the Postnatal Brain, Inserm U837, 59045 Lille Cedex, France
| | | | | | | |
Collapse
|
209
|
Ventral tegmental area leptin receptor neurons specifically project to and regulate cocaine- and amphetamine-regulated transcript neurons of the extended central amygdala. J Neurosci 2010; 30:5713-23. [PMID: 20410123 DOI: 10.1523/jneurosci.1001-10.2010] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Leptin acts via its receptor (LepRb) to regulate neural circuits in concert with body energy stores. In addition to acting on a number of hypothalamic structures, leptin modulates the mesolimbic dopamine (DA) system. To determine the sites at which LepRb neurons might directly influence the mesolimbic DA system, we examined the distribution of LepRb neurons and their projections within mesolimbic brain regions. Although the ventral tegmental area (VTA) contains DA LepRb neurons, LepRb neurons are absent from the amygdala and striatum. Also, LepRb-EGFPf mice (which label projections from LepRb neurons throughout the brain) reveal that few LepRb neurons project to the nucleus accumbens (NAc). In contrast, the central amygdala (CeA) and its rostral extension receive copious projections from LepRb neurons. Indeed, LepRb-specific anterograde tracing demonstrates (and retrograde tracing confirms) that VTA LepRb neurons project to the extended CeA (extCeA) but not the NAc. Consistently, leptin promotes cAMP response element-binding protein phosphorylation in the extCeA, but not NAc, of leptin-deficient animals. Furthermore, transgenic mice expressing the trans-synaptic tracer wheat germ agglutinin in LepRb neurons reveal the innervation of CeA cocaine- and amphetamine-regulated transcript (CART) neurons by LepRb neurons, and leptin suppresses the increased CeA CART expression of leptin-deficient animals. Thus, LepRb VTA neurons represent a subclass of VTA DA neurons that specifically innervates and controls the extCeA; we hypothesize that these neurons primarily modulate CeA-directed behaviors.
Collapse
|
210
|
Robertson S, Ishida-Takahashi R, Tawara I, Hu J, Patterson CM, Jones JC, Kulkarni RN, Myers MG. Insufficiency of Janus kinase 2-autonomous leptin receptor signals for most physiologic leptin actions. Diabetes 2010; 59:782-90. [PMID: 20068132 PMCID: PMC2844825 DOI: 10.2337/db09-1556] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE Leptin acts via its receptor (LepRb) to signal the status of body energy stores. Leptin binding to LepRb initiates signaling by activating the associated Janus kinase 2 (Jak2) tyrosine kinase, which promotes the phosphorylation of tyrosine residues on the intracellular tail of LepRb. Two previously examined LepRb phosphorylation sites mediate several, but not all, aspects of leptin action, leading us to hypothesize that Jak2 signaling might contribute to leptin action independently of LepRb phosphorylation sites. We therefore determined the potential role in leptin action for signals that are activated by Jak2 independently of LepRb phosphorylation (Jak2-autonomous signals). RESEARCH DESIGN AND METHODS We inserted sequences encoding a truncated LepRb mutant (LepRb(Delta65c), which activates Jak2 normally, but is devoid of other LepRb intracellular sequences) into the mouse Lepr locus. We examined the leptin-regulated physiology of the resulting Delta/Delta mice relative to LepRb-deficient db/db animals. RESULTS The Delta/Delta animals were similar to db/db animals in terms of energy homeostasis, neuroendocrine and immune function, and regulation of the hypothalamic arcuate nucleus, but demonstrated modest improvements in glucose homeostasis. CONCLUSIONS The ability of Jak2-autonomous LepRb signals to modulate glucose homeostasis in Delta/Delta animals suggests a role for these signals in leptin action. Because Jak2-autonomous LepRb signals fail to mediate most leptin action, however, signals from other LepRb intracellular sequences predominate.
Collapse
Affiliation(s)
- Scott Robertson
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | | | - Isao Tawara
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Jiang Hu
- Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
| | | | - Justin C. Jones
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Rohit N. Kulkarni
- Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
| | - Martin G. Myers
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
- Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts
- Corresponding author: Martin G. Myers Jr.,
| |
Collapse
|
211
|
Massolt ET, van Haard PM, Rehfeld JF, Posthuma EF, van der Veer E, Schweitzer DH. Appetite suppression through smelling of dark chocolate correlates with changes in ghrelin in young women. ACTA ACUST UNITED AC 2010; 161:81-6. [DOI: 10.1016/j.regpep.2010.01.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Revised: 12/06/2009] [Accepted: 01/18/2010] [Indexed: 11/26/2022]
|
212
|
Dallman MF. Stress-induced obesity and the emotional nervous system. Trends Endocrinol Metab 2010; 21:159-65. [PMID: 19926299 PMCID: PMC2831158 DOI: 10.1016/j.tem.2009.10.004] [Citation(s) in RCA: 495] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 10/21/2009] [Accepted: 10/28/2009] [Indexed: 11/27/2022]
Abstract
Stress and emotional brain networks foster eating behaviors that can lead to obesity. The neural networks underlying the complex interactions among stressors, body, brain and food intake are now better understood. Stressors, by activating a neural stress-response network, bias cognition toward increased emotional activity and degraded executive function. This causes formed habits to be used rather than a cognitive appraisal of responses. Stress also induces secretion of glucocorticoids, which increases motivation for food, and insulin, which promotes food intake and obesity. Pleasurable feeding then reduces activity in the stress-response network, reinforcing the feeding habit. These effects of stressors emphasize the importance of teaching mental reappraisal techniques to restore responses from habitual to thoughtful, thus battling stress-induced obesity.
Collapse
Affiliation(s)
- Mary F Dallman
- Department of Physiology, University of California San Francisco, San Francisco, CA 94143, USA
| |
Collapse
|
213
|
Scarpace PJ, Matheny M, Zhang Y. Wheel running eliminates high-fat preference and enhances leptin signaling in the ventral tegmental area. Physiol Behav 2010; 100:173-9. [PMID: 20193697 DOI: 10.1016/j.physbeh.2010.02.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 02/18/2010] [Accepted: 02/19/2010] [Indexed: 01/21/2023]
Abstract
Voluntary wheel running (WR) is a form of physical activity in rodents that influences ingestive behavior. This study examined the effects of WR on dietary preference and the potential role of leptin in mediating these effects. In a two-diet choice paradigm in which both palatable high-fat (HF) food and standard laboratory chow were provided ad libitum, rats displayed a strong preference for the former and chose to eat almost exclusively the HF diet over chow in sedentary conditions. With free access to running wheels, however, rats exhibited no preference for the HF food and consumed equal gram amounts of both chow and HF diets. The total daily caloric consumption during WR in the dietary choice protocol was equivalent to the amount of calories consumed daily by WR rats with only chow or only HF diet available, yet significantly less than sedentary chow caloric consumption. Two days after initiating WR, leptin signal transduction was examined in multiple selected brain sites following leptin injection into the third cerebral ventricle. The maximal leptin-stimulated STAT3 phosphorylation was enhanced only in the ventral tegmental area (VTA), but not in the arcuate nucleus, lateral hypothalamus, dorsal medial or ventral medial hypothalamus, or substantia nigra. In conclusion, wheel running appears to act either as an independent reinforcing factor or as a more favored activity to substitute for the consumption of a palatable HF diet, thus eliminating the preference for the HF food. Moreover, WR enhances leptin signaling specifically in the VTA, suggestive of a WR-evoked mechanism of heightened leptin function in the VTA to curb the drive to consume palatable HF foods.
Collapse
Affiliation(s)
- P J Scarpace
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL 32610, United States.
| | | | | |
Collapse
|
214
|
Bouret SG. Role of early hormonal and nutritional experiences in shaping feeding behavior and hypothalamic development. J Nutr 2010; 140:653-7. [PMID: 20107150 DOI: 10.3945/jn.109.112433] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Obesity in adults and children is increasingly becoming a major health problem worldwide. However, the precise biological mechanisms governing this disease have not been fully elucidated. Obesity involves the complex interaction of a wide range of environmental and genetic factors. Additionally, there is now a growing body of evidence suggesting that alterations in metabolic environment during important periods of organ development can predispose individuals to later development of obesity and diabetes. Maternal obesity or malnutrition during pregnancy increases the risk for metabolic disorders (including obesity) in the offspring. Similarly, early postnatal overnutrition also predisposes offspring to adult obesity. The hypothalamus appears to play an essential role in controlling appetite. It undergoes a tremendous growth beginning early in gestation and continuing during the postnatal period. These developmental windows represent periods of sensitivity for hypothalamic development during which alterations in the nutritional and/or hormonal environment may perturb hypothalamic development and subsequent function.
Collapse
Affiliation(s)
- Sebastien G Bouret
- The Saban Research Institute, Neuroscience Program, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA 90027, USA.
| |
Collapse
|
215
|
Affiliation(s)
- Iain J Clarke
- Department of Physiology, Monash University, Clayton, Victoria 3800, Australia.
| |
Collapse
|
216
|
Caron E, Sachot C, Prevot V, Bouret SG. Distribution of leptin-sensitive cells in the postnatal and adult mouse brain. J Comp Neurol 2010; 518:459-76. [DOI: 10.1002/cne.22219] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
217
|
Ramadori G, Coppari R. Pharmacological manipulations of CNS sirtuins: potential effects on metabolic homeostasis. Pharmacol Res 2010; 62:48-54. [PMID: 20138996 DOI: 10.1016/j.phrs.2010.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 01/29/2010] [Accepted: 02/01/2010] [Indexed: 11/30/2022]
Abstract
Sirtuins are deacetylases and/or mono-ADP-ribosyltransferases found in organisms ranging from bacteria to humans. These enzymes use oxidized nicotinamide adenine dinucleotide (NAD(+)) and a long array of different proteins (e.g.: histones, transcription factors, cofactors, members of the electron transport chain, etc.) as substrates. Sirtuins-mediated reactions yield deacetylated proteins, nicotinamide (NAM) and 2'-O-acetyl-ADP-ribose (O-AADPr) or mono-ADP-ribosylated proteins and NAM. As these post-translational modifications change the activity of their targets and sirtuins depend on NAD(+) to function, these enzymes are thought to link metabolic statuses with cellular gene expression, activity and fate; as such sirtuins are thought to be bona fide metabolic-sensor proteins. Due to their diverse targets, sirtuins affect metabolism, senescence, longevity, circadian rhythms and many other biological and physiological programs. In this review we focus on their known roles on metabolic homeostasis with particular emphasis on their functions in neurons within the central nervous system (CNS). We also touch upon the possible metabolic outcomes of pharmacological manipulations of CNS sirtuins.
Collapse
Affiliation(s)
- Giorgio Ramadori
- Department of Internal Medicine (Division of Hypothalamic Research), The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd-Room Y6-220C, Dallas, TX 75390-9077, USA
| | | |
Collapse
|
218
|
Schulz C, Paulus K, Lobmann R, Dallman M, Lehnert H. Endogenous ACTH, not only alpha-melanocyte-stimulating hormone, reduces food intake mediated by hypothalamic mechanisms. Am J Physiol Endocrinol Metab 2010; 298:E237-44. [PMID: 19920221 DOI: 10.1152/ajpendo.00408.2009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
ACTH and alpha-melanocyte-stimulating hormone (alpha-MSH) are both consecutively processed from proopiomelanocortin (POMC), which is synthesized in hypothalamic arcuate neurons innervating the paraventricular nuclei (PVN). POMC secretion/synthesis is regulated by energy availability. ACTH and alpha-MSH bind with equal affinity to melanocortin-4 receptors and elicit similar effects on signal transduction in-vitro. Endogenous alpha-MSH thus far is believed to be the major physiological agonist and to act in an anorexigenic manner. Until now, it was fully unknown whether endogenous ACTH is also involved in the regulation of appetite and food intake. In this study in rats, we now show that icv ACTH as well as alpha-MSH possess anorexigenic effects in the PVN or areas in close proximity in vivo and that the effect of ACTH is direct and not mediated via alpha-MSH. We investigated the roles of endogenous ACTH and alpha-MSH by PVN application of the respective antibodies under different physiological conditions. In satiated rats with high levels of ACTH and alpha-MSH in the PVN, antibody administration increased food intake and body weight gain; hungry animals were unaffected. Finally, repeated injections of ACTH antibodies into PVN resulted in persistently increased food intake during the light period. These data now provide robust evidence that endogenous ACTH without further processing acts in the PVN or areas in close proximity to reduce food intake under conditions of feeding-induced satiety.
Collapse
Affiliation(s)
- Carla Schulz
- Department of Internal Medicine I, Luebeck University, Germany.
| | | | | | | | | |
Collapse
|
219
|
Grayson BE, Kievit P, Smith MS, Grove KL. Critical determinants of hypothalamic appetitive neuropeptide development and expression: species considerations. Front Neuroendocrinol 2010; 31:16-31. [PMID: 19822169 PMCID: PMC2813940 DOI: 10.1016/j.yfrne.2009.10.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 10/05/2009] [Indexed: 01/21/2023]
Abstract
Over the last decade there has been a striking increase in the early onset of metabolic disease, including obesity and diabetes. The regulation of energy homeostasis is complex and involves the intricate integration of peripheral and central systems, including the hypothalamus. This review provides an overview of the development of brain circuitry involved in the regulation of energy homeostasis as well as recent findings related to the impact of both prenatal and postnatal maternal environment on the development of these circuits. There is surprising evidence that both overnutrition and undernutrition impact the development of these circuits in a similar manner as well as having similar consequences of increased obesity and diabetes later in life. There is also a special focus on relevant species differences in the development of hypothalamic circuits. A deeper understanding of the mechanisms involved in the development of brain circuitry is needed to fully understand how the nutritional and/or maternal environments impact the functional circuitry as well as the behavior and physiological outcomes.
Collapse
Affiliation(s)
- B E Grayson
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Portland, OR 97239, USA
| | | | | | | |
Collapse
|
220
|
Rondini TA, Donato J, Rodrigues BDC, Bittencourt JC, Elias CF. Chemical identity and connections of medial preoptic area neurons expressing melanin-concentrating hormone during lactation. J Chem Neuroanat 2010; 39:51-62. [DOI: 10.1016/j.jchemneu.2009.10.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 10/21/2009] [Accepted: 10/30/2009] [Indexed: 11/25/2022]
|
221
|
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.
Collapse
Affiliation(s)
- Clémence Blouet
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
| | | |
Collapse
|
222
|
Toda C, Shiuchi T, Lee S, Yamato-Esaki M, Fujino Y, Suzuki A, Okamoto S, Minokoshi Y. Distinct effects of leptin and a melanocortin receptor agonist injected into medial hypothalamic nuclei on glucose uptake in peripheral tissues. Diabetes 2009; 58:2757-65. [PMID: 19752162 PMCID: PMC2780865 DOI: 10.2337/db09-0638] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE The medial hypothalamus mediates leptin-induced glucose uptake in peripheral tissues, and brain melanocortin receptors (MCRs) mediate certain central effects of leptin. However, the contributions of the leptin receptor and MCRs in individual medial hypothalamic nuclei to regulation of peripheral glucose uptake have remained unclear. We examined the effects of an injection of leptin and the MCR agonist MT-II into medial hypothalamic nuclei on glucose uptake in peripheral tissues. RESEARCH DESIGN AND METHODS Leptin or MT-II was injected into the ventromedial (VMH), dorsomedial (DMH), arcuate nucleus (ARC), or paraventricular (PVH) hypothalamus or the lateral ventricle (intracerebroventricularly) in freely moving mice. The MCR antagonist SHU9119 was injected intracerebroventricularly. Glucose uptake was measured by the 2-[(3)H]deoxy-d-glucose method. RESULTS Leptin injection into the VMH increased glucose uptake in skeletal muscle, brown adipose tissue (BAT), and heart, whereas that into the ARC increased glucose uptake in BAT, and that into the DMH or PVH had no effect. SHU9119 abolished these effects of leptin injected into the VMH. Injection of MT-II either into the VMH or intracerebroventricularly increased glucose uptake in skeletal muscle, BAT, and heart, whereas that into the PVH increased glucose uptake in BAT, and that into the DMH or ARC had no effect. CONCLUSIONS The VMH mediates leptin- and MT-II-induced glucose uptake in skeletal muscle, BAT, and heart. These effects of leptin are dependent on MCR activation. The leptin receptor in the ARC and MCR in the PVH regulate glucose uptake in BAT. Medial hypothalamic nuclei thus play distinct roles in leptin- and MT-II-induced glucose uptake in peripheral tissues.
Collapse
Affiliation(s)
- Chitoku Toda
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Tetsuya Shiuchi
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Suni Lee
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Maya Yamato-Esaki
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Yusuke Fujino
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Internal Medicine 1, Faculty of Medicine, Oita University, Hasama, Oita, Japan
| | - Atsushi Suzuki
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Shiki Okamoto
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Yasuhiko Minokoshi
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Corresponding author: Yasuhiko Minokoshi,
| |
Collapse
|
223
|
Stengel A, Goebel M, Wang L, Rivier J, Kobelt P, Mönnikes H, Lambrecht NWG, Taché Y. Central nesfatin-1 reduces dark-phase food intake and gastric emptying in rats: differential role of corticotropin-releasing factor2 receptor. Endocrinology 2009; 150:4911-9. [PMID: 19797401 PMCID: PMC2775975 DOI: 10.1210/en.2009-0578] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Nesfatin-1, derived from nucleobindin2, is expressed in the hypothalamus and reported in one study to reduce food intake (FI) in rats. To characterize the central anorexigenic action of nesfatin-1 and whether gastric emptying (GE) is altered, we injected nesfatin-1 into the lateral brain ventricle (intracerebroventricular, icv) or fourth ventricle (4v) in chronically cannulated rats or into the cisterna magna (intracisternal, ic) under short anesthesia and compared with ip injection. Nesfatin-1 (0.05 microg/rat, icv) decreased 2-3 h and 3-6 h dark-phase FI by 87 and 45%, respectively, whereas ip administration (2 microg/rat) had no effect. The corticotropin-releasing factor (CRF)(1)/CRF(2) antagonist astressin-B or the CRF(2) antagonist astressin(2)-B abolished icv nesfatin-1's anorexigenic action, whereas an astressin(2)-B analog, devoid of CRF-receptor binding affinity, did not. Nesfatin-1 icv induced a dose-dependent reduction of GE by 26 and 43% that was not modified by icv astressin(2)-B. Nesfatin-1 into the 4v (0.05 microg/rat) or ic (0.5 microg/rat) decreased cumulative dark-phase FI by 29 and 60% at 1 h and by 41 and 37% between 3 and 5 h, respectively. This effect was neither altered by ic astressin(2)-B nor associated with changes in GE. Cholecystokinin (ip) induced Fos expression in 43% of nesfatin-1 neurons in the paraventricular hypothalamic nucleus and 24% of those in the nucleus tractus solitarius. These data indicate that nesfatin-1 acts centrally to reduce dark phase FI through CRF(2)-receptor-dependent pathways after forebrain injection and CRF(2)-receptor-independent pathways after hindbrain injection. Activation of nesfatin-1 neurons by cholecystokinin at sites regulating food intake may suggest a role in gut peptide satiation effect.
Collapse
Affiliation(s)
- Andreas Stengel
- Center for Neurovisceral Sciences and Women's Health CURE, Building 115, Room 117, Veterans Administration Greater Los Angeles Healthcare System, 11301 Wilshire Boulevard, Los Angeles, California 90073, USA
| | | | | | | | | | | | | | | |
Collapse
|
224
|
Abstract
Named originally for their effects on peripheral end organs, the melanocortin system controls a diverse set of physiological processes through a series of five G-protein-coupled receptors and several sets of small peptide ligands. The central melanocortin system plays an essential role in homeostatic regulation of body weight, in which two alternative ligands, alpha-melanocyte-stimulating hormone and agouti-related protein, stimulate and inhibit receptor signaling in several key brain regions that ultimately affect food intake and energy expenditure. Much of what we know about the relationship between central melanocortin signaling and body weight regulation stems from genetic studies. Comparative genomic studies indicate that melanocortin receptors used for controlling pigmentation and body weight regulation existed more than 500 million years ago in primitive vertebrates, but that fine-grained control of melanocortin receptors through neuropeptides and endogenous antagonists developed more recently. Recent studies based on dog coat-color genetics revealed a new class of melanocortin ligands, the beta-defensins, which reveal the potential for cross talk between the melanocortin and the immune systems.
Collapse
|
225
|
Villanueva EC, Myers MG. Leptin receptor signaling and the regulation of mammalian physiology. Int J Obes (Lond) 2009; 32 Suppl 7:S8-12. [PMID: 19136996 DOI: 10.1038/ijo.2008.232] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The adipocyte-derived hormone, leptin, signals the status of body energy stores to the central nervous system to regulate appetite and energy expenditure. A specific long-form leptin receptor (LepRb), a type I cytokine receptor, mediates leptin action on LepRb-expressing neurons in the brain. Leptin binding to LepRb activates the associated Janus kinase-2 (Jak2) tyrosine kinase to promote the phosphorylation of Jak2 and three residues on LepRb; each of these sites mediates a distinct aspect of downstream LepRb signaling, with differing physiologic functions. Tyr(1138) --> STAT3 signaling suppresses feeding, but is not required for a number of other leptin actions. Tyr(985) binds SH2-containing tyrosine phosphatase-2 and suppressor of cytokine signaling-3 and primarily mediates the attenuation of LepRb signaling in vivo. The role for Tyr(1077), the major regulator of signal transducer and activator of transcription-5 (STAT5) during leptin signaling, in the physiologic response to leptin remains unclear, although the obese phenotype of animals deleted for STAT5 in the brain suggests the potential importance of this signaling pathway. Leptin also modulates a number of other signaling pathways in the brain, including PI 3-kinase, mammalian target of rapamycin and AMP-dependent protein kinase; the pathways by which leptin controls these signals remain unclear, however, and may involve some indirect mechanisms. Important issues regarding leptin action and LepRb signaling in the future include not only the more thorough analysis of intracellular signaling pathways, but the neural substrate by which leptin acts, as most major populations of LepRb neurons remain poorly studied.
Collapse
Affiliation(s)
- E C Villanueva
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | | |
Collapse
|
226
|
Villanueva EC, Münzberg H, Cota D, Leshan RL, Kopp K, Ishida-Takahashi R, Jones JC, Fingar DC, Seeley RJ, Myers MG. Complex regulation of mammalian target of rapamycin complex 1 in the basomedial hypothalamus by leptin and nutritional status. Endocrinology 2009; 150:4541-51. [PMID: 19628573 PMCID: PMC2754689 DOI: 10.1210/en.2009-0642] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The medial basal hypothalamus, including the arcuate nucleus (ARC) and the ventromedial hypothalamic nucleus (VMH), integrates signals of energy status to modulate metabolism and energy balance. Leptin and feeding regulate the mammalian target of rapamycin complex 1 (mTORC1) in the hypothalamus, and hypothalamic mTORC1 contributes to the control of feeding and energy balance. To determine the mechanisms by which leptin modulates mTORC1 in specific hypothalamic neurons, we immunohistochemically assessed the mTORC1-dependent phosphorylation of ribosomal protein S6 (pS6). In addition to confirming the modulation of ARC mTORC1 activity by acute leptin treatment, this analysis revealed the robust activation of mTORC1-dependent ARC pS6 in response to fasting and leptin deficiency in leptin receptor-expressing Agouti-related protein neurons. In contrast, fasting and leptin deficiency suppress VMH mTORC1 signaling. The appropriate regulation of ARC mTORC1 by mutant leptin receptor isoforms correlated with their ability to suppress the activity of Agouti-related protein neurons, suggesting the potential stimulation of mTORC1 by the neuronal activity. Indeed, fasting- and leptin deficiency-induced pS6-immunoreactivity (IR) extensively colocalized with c-Fos-IR in ARC and VMH neurons. Furthermore, ghrelin, which activates orexigenic ARC neurons, increased ARC mTORC1 activity and induced colocalized pS6- and c-Fos-IR. Thus, neuronal activity promotes mTORC1/pS6 in response to signals of energy deficit. In contrast, insulin, which activates mTORC1 via the phosphatidylinositol 3-kinase pathway, increased ARC and VMH pS6-IR in the absence of neuronal activation. The regulation of mTORC1 in the basomedial hypothalamus thus varies by cell and stimulus type, as opposed to responding in a uniform manner to nutritional and hormonal perturbations.
Collapse
Affiliation(s)
- Eneida C Villanueva
- Division of Metabolism, Department of Medicine, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
227
|
Lew PS, Wong D, Yamaguchi T, Leckstrom A, Schwartz J, Dodd JG, Mizuno TM. Tail suspension increases energy expenditure independently of the melanocortin system in miceThis article is one of a selection of papers published in a special issue celebrating the 125th anniversary of the Faculty of Medicine at the University of Manitoba. Can J Physiol Pharmacol 2009; 87:839-49. [DOI: 10.1139/y09-074] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Space travelers experience anorexia and body weight loss in a microgravity environment, and microgravity-like situations cause changes in hypothalamic activity. Hypothalamic melanocortins play a critical role in the regulation of metabolism. Therefore, we hypothesized that microgravity affects metabolism through alterations in specific hypothalamic signaling pathways, including melanocortin signaling. To address this hypothesis, the microgravity-like situation was produced by an antiorthostatic tail suspension in wild-type and agouti mice, and the effect of tail suspension on energy expenditure and hypothalamic gene expression was examined. Energy expenditure was measured using indirect calorimetry before and during the tail suspension protocol. Hypothalamic tissues were collected for gene expression analysis at the end of the 3 h tail suspension period. Tail suspension significantly increased oxygen consumption, carbon dioxide production, and heat production in wild-type mice. Tail suspension-induced increases in energy expenditure were not attenuated in agouti mice. Although tail suspension did not alter hypothalamic proopiomelanocortin (POMC) and agouti-related protein (AGRP) mRNA levels, it significantly increased hypothalamic interleukin 6 (Il-6) mRNA levels. These data are consistent with the hypothesis that microgravity increases energy expenditure and suggest that these effects are mediated through hypothalamic signaling pathways that are independent of melanocortins, but possibly used by Il-6.
Collapse
Affiliation(s)
- Pei San Lew
- Department of Physiology, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada
| | - Davie Wong
- Department of Physiology, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada
| | - Takafumi Yamaguchi
- Department of Physiology, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada
| | - Arnold Leckstrom
- Department of Physiology, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada
| | - Jacquie Schwartz
- Department of Physiology, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada
| | - Janice G. Dodd
- Department of Physiology, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada
| | - Tooru M. Mizuno
- Department of Physiology, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada
| |
Collapse
|
228
|
A serotonin-dependent mechanism explains the leptin regulation of bone mass, appetite, and energy expenditure. Cell 2009; 138:976-89. [PMID: 19737523 DOI: 10.1016/j.cell.2009.06.051] [Citation(s) in RCA: 462] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 05/26/2009] [Accepted: 06/05/2009] [Indexed: 12/13/2022]
Abstract
Leptin inhibition of bone mass accrual requires the integrity of specific hypothalamic neurons but not expression of its receptor on these neurons. The same is true for its regulation of appetite and energy expenditure. This suggests that leptin acts elsewhere in the brain to achieve these three functions. We show here that brainstem-derived serotonin (BDS) favors bone mass accrual following its binding to Htr2c receptors on ventromedial hypothalamic neurons and appetite via Htr1a and 2b receptors on arcuate neurons. Leptin inhibits these functions and increases energy expenditure because it reduces serotonin synthesis and firing of serotonergic neurons. Accordingly, while abrogating BDS synthesis corrects the bone, appetite and energy expenditure phenotypes caused by leptin deficiency, inactivation of the leptin receptor in serotonergic neurons recapitulates them fully. This study modifies the map of leptin signaling in the brain and identifies a molecular basis for the common regulation of bone and energy metabolisms. For a video summary of this article, see the PaperFlick file with the Supplemental Data available online.
Collapse
|
229
|
Leinninger GM, Jo YH, Leshan RL, Louis GW, Yang H, Barrera JG, Wilson H, Opland DM, Faouzi MA, Gong Y, Jones JC, Rhodes CJ, Chua S, Diano S, Horvath TL, Seeley RJ, Becker JB, Münzberg H, Myers MG. Leptin acts via leptin receptor-expressing lateral hypothalamic neurons to modulate the mesolimbic dopamine system and suppress feeding. Cell Metab 2009; 10:89-98. [PMID: 19656487 PMCID: PMC2723060 DOI: 10.1016/j.cmet.2009.06.011] [Citation(s) in RCA: 289] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Revised: 05/27/2009] [Accepted: 06/25/2009] [Indexed: 12/24/2022]
Abstract
The lateral hypothalamic area (LHA) acts in concert with the ventral tegmental area (VTA) and other components of the mesolimbic dopamine (DA) system to control motivation, including the incentive to feed. The anorexigenic hormone leptin modulates the mesolimbic DA system, although the mechanisms underlying this control have remained incompletely understood. We show that leptin directly regulates a population of leptin receptor (LepRb)-expressing inhibitory neurons in the LHA and that leptin action via these LHA LepRb neurons decreases feeding and body weight. Furthermore, these LHA LepRb neurons innervate the VTA, and leptin action on these neurons restores VTA expression of the rate-limiting enzyme in DA production along with mesolimbic DA content in leptin-deficient animals. Thus, these findings reveal that LHA LepRb neurons link anorexic leptin action to the mesolimbic DA system.
Collapse
Affiliation(s)
- Gina M Leinninger
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
230
|
Kampe J, Tschöp M, Hollis J, Oldfield BJ. An anatomic basis for the communication of hypothalamic, cortical and mesolimbic circuitry in the regulation of energy balance. Eur J Neurosci 2009; 30:415-30. [DOI: 10.1111/j.1460-9568.2009.06818.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
231
|
Ren X, Zhou L, Terwilliger R, Newton SS, de Araujo IE. Sweet taste signaling functions as a hypothalamic glucose sensor. Front Integr Neurosci 2009; 3:12. [PMID: 19587847 PMCID: PMC2706652 DOI: 10.3389/neuro.07.012.2009] [Citation(s) in RCA: 183] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Accepted: 05/29/2009] [Indexed: 12/04/2022] Open
Abstract
Brain glucosensing is essential for normal body glucose homeostasis and neuronal function. However, the exact signaling mechanisms involved in the neuronal sensing of extracellular glucose levels remain poorly understood. Of particular interest is the identification of candidate membrane molecular sensors that would allow neurons to change firing rates independently of intracellular glucose metabolism. Here we describe for the first time the expression of the taste receptor genes Tas1r1, Tas1r2 and Tas1r3, and their associated G-protein genes, in the mammalian brain. Neuronal expression of taste genes was detected in different nutrient-sensing forebrain regions, including the paraventricular and arcuate nuclei of the hypothalamus, the CA fields and dentate gyrus of the hippocampus, the habenula, and cortex. Expression was also observed in the intra-ventricular epithelial cells of the choroid plexus. These same regions were found to express the corresponding gene products that form the heterodimeric T1R2/T1R3 and T1R1/T1R3 sweet and l-amino acid taste G-protein coupled receptors, respectively, along with the taste G-protein α-gustducin. Moreover, in vivo studies in mice demonstrated that the hypothalamic expression of taste-related genes is regulated by the nutritional state of the animal, with food deprivation significantly increasing expression levels of Tas1r1 and Tas1r2 in hypothalamus, but not in cortex. Furthermore, exposing mouse hypothalamic cells to a low-glucose medium, while maintaining normal l-amino acid concentrations, specifically resulted in higher expression levels of the sweet-associated gene Tas1r2. This latter effect was reversed by adding the non-metabolizable artificial sweetener sucralose to the low-glucose medium, indicating that taste-like signaling in hypothalamic neurons does not require intracellular glucose oxidation. Taken together, our findings suggest that the heterodimeric G-protein coupled sweet receptor T1R2/T1R3 is a candidate membrane-bound brain glucosensor.
Collapse
Affiliation(s)
- Xueying Ren
- The John B Pierce Laboratory New Haven, CT, USA
| | | | | | | | | |
Collapse
|
232
|
Woods SC. The control of food intake: behavioral versus molecular perspectives. Cell Metab 2009; 9:489-98. [PMID: 19490904 PMCID: PMC3090647 DOI: 10.1016/j.cmet.2009.04.007] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 04/15/2009] [Accepted: 04/24/2009] [Indexed: 01/16/2023]
Abstract
To meet the continuous demand for energy, organisms use diverse signals to match food intake with energy needs. This paper reviews the effect of satiation signals and adiposity signals on food intake, including how they interact in the brain and how their influence changes with experience. Whereas meal initiation is influenced by external environmental factors, meal size is influenced by an array of signals that can be partitioned according to their reliability in indicating caloric content of food. It is argued that the malleability of satiation signals renders them poor candidates as pharmacological targets to control body weight.
Collapse
Affiliation(s)
- Stephen C Woods
- Department of Psychiatry, University of Cincinnati, Cincinnati, OH 45237, USA.
| |
Collapse
|
233
|
The ventral premammillary nucleus links fasting-induced changes in leptin levels and coordinated luteinizing hormone secretion. J Neurosci 2009; 29:5240-50. [PMID: 19386920 DOI: 10.1523/jneurosci.0405-09.2009] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Physiological conditions of low leptin levels like those observed during negative energy balance are usually characterized by the suppression of luteinizing hormone (LH) secretion and fertility. Leptin administration restores LH levels and reproductive function. Leptin action on LH secretion is thought to be mediated by the brain. However, the neuronal population that mediates this effect is still undefined. The hypothalamic ventral premammillary nucleus (PMV) neurons express a dense concentration of leptin receptors and project to brain areas related to reproductive control. Therefore, we hypothesized that the PMV is well located to mediate leptin action on LH secretion. To test our hypothesis, we performed bilateral excitotoxic lesions of the PMV in adult female rats. PMV-lesioned animals displayed a clear disruption of the estrous cycle, remaining in anestrus for 15-20 d. After apparent recovery of cyclicity, animals perfused in the afternoon of proestrus showed decreased Fos immunoreactivity in the anteroventral periventricular nucleus and in gonadotropin releasing hormone neurons. PMV-lesioned animals also displayed decreased estrogen and LH secretion on proestrus. Lesions caused no changes in mean food intake and body weight up to 7 weeks after surgery. We further tested the ability of leptin to induce LH secretion in PMV-lesioned fasted animals. We found that complete lesions of the PMV precluded leptin stimulation of LH secretion on fasting. Our findings demonstrate that the PMV is a key site linking changing levels of leptin and coordinated control of reproduction.
Collapse
|
234
|
de Vries GJ, Södersten P. Sex differences in the brain: the relation between structure and function. Horm Behav 2009; 55:589-96. [PMID: 19446075 PMCID: PMC3932614 DOI: 10.1016/j.yhbeh.2009.03.012] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 03/10/2009] [Accepted: 03/12/2009] [Indexed: 11/24/2022]
Abstract
In the fifty years since the organizational hypothesis was proposed, many sex differences have been found in behavior as well as structure of the brain that depend on the organizational effects of gonadal hormones early in development. Remarkably, in most cases we do not understand how the two are related. This paper makes the case that overstating the magnitude or constancy of sex differences in behavior and too narrowly interpreting the functional consequences of structural differences are significant roadblocks in resolving this issue.
Collapse
Affiliation(s)
- Geert J de Vries
- Department of Psychology and Center for Neuroendocrine Studies, Tobin Hall, University of Massachusetts, Amherst, MA 01003 9333, USA.
| | | |
Collapse
|
235
|
Direct innervation of GnRH neurons by metabolic- and sexual odorant-sensing leptin receptor neurons in the hypothalamic ventral premammillary nucleus. J Neurosci 2009; 29:3138-47. [PMID: 19279251 DOI: 10.1523/jneurosci.0155-09.2009] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Leptin acts via its receptor (LepRb) on specific CNS neurons to signal the adequacy of long-term energy stores, thereby permitting the expenditure of resources on energy-intensive processes such as reproduction. The ventral premammillary nucleus of the hypothalamus (PMv), which has been implicated in the stimulation of gonadotropin release by olfactory cues, contains numerous LepRb neurons, suggesting a potential role for LepRb PMv neurons in transmitting both metabolic and odorant signals to the neuroendocrine reproductive system. Indeed, Fos immunoreactivity and electrophysiologic recordings revealed the direct activation of LepRb PMv neurons by leptin, and exposure to odors from mice of the opposite sex promoted Fos immunoreactivity (Fos-IR) in many LepRb PMv neurons. To determine the regions innervated by the LepRb PMv neurons, we used two novel cre-activated tract-tracing systems in Lepr(cre) animals; data from these systems and from standard tracing techniques revealed that LepRb PMv neurons project to a subset of the regions, including the preoptic area, that are innervated by the PMv as a whole. Furthermore, the retrograde accumulation in LepRb PMv neurons of a trans-synaptic tracer from GnRH neurons revealed the direct innervation of GnRH neurons by many LepRb PMv neurons. Thus, LepRb PMv neurons sense metabolic and sexual odorant cues and project to the rostral hypothalamus to directly innervate GnRH neurons. These results are consistent with a role for LepRb PMv neurons in regulating the reproductive axis in response to metabolic and odorant stimuli.
Collapse
|
236
|
The neuropeptides CCK and NPY and the changing view of cell-to-cell communication in the taste bud. Physiol Behav 2009; 97:581-91. [PMID: 19332083 DOI: 10.1016/j.physbeh.2009.02.043] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Accepted: 02/16/2009] [Indexed: 11/24/2022]
Abstract
The evolving view of the taste bud increasingly suggests that it operates as a complex signal processing unit. A number of neurotransmitters and neuropeptides and their corresponding receptors are now known to be expressed in subsets of taste receptor cells in the mammalian bud. These expression patterns set up hard-wired cell-to-cell communication pathways whose exact physiological roles still remain obscure. As occurs in other cellular systems, it is likely that neuropeptides are co-expressed with neurotransmitters and function as neuromodulators. Several neuropeptides have been identified in taste receptor cells including cholecystokinin (CCK), neuropeptide Y (NPY), vasoactive intestinal peptide (VIP), and glucagon-like peptide 1 (GLP-1). Of these, CCK and NPY are the best studied. These two peptides are co-expressed in the same presynaptic cells; however, their postsynaptic actions are both divergent and antagonistic. CCK and its receptor, the CCK-1 subtype, are expressed in the same subset of taste receptor cells and the autocrine activation of these cells produces a number of excitatory physiological actions. Further, most of these cells are responsive to bitter stimuli. On the other hand, NPY and its receptor, the NPY-1 subtype, are expressed in different cells. NPY, acting in a paracrine fashion on NPY-1 receptors, results in inhibitory actions on the cell. Preliminary evidence suggests the NPY-1 receptor expressing cell co-expresses T1R3, a member of the T1R family of G-protein coupled receptors thought to be important in detection of sweet and umami stimuli. Thus the neuropeptide expressing cells co-express CCK, NPY, and CCK-1 receptor. Neuropeptides released from these cells during bitter stimulation may work in concert to both modulate the excitation of bitter-sensitive taste receptor cells while concurrently inhibiting sweet-sensitive cells. This modulatory process is similar to the phenomenon of lateral inhibition that occurs in other sensory systems.
Collapse
|
237
|
Gerin I, Louis GW, Zhang X, Prestwich TC, Kumar TR, Myers MG, Macdougald OA, Nothnick WB. Hyperphagia and obesity in female mice lacking tissue inhibitor of metalloproteinase-1. Endocrinology 2009; 150:1697-704. [PMID: 19036876 PMCID: PMC2659269 DOI: 10.1210/en.2008-1409] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Certain matrix metalloproteinases and their regulators, the tissue inhibitors of metalloproteinases (TIMPs), are involved in development and remodeling of adipose tissue. In studying Timp1(<tm1Pds>) mice, which have a null mutation in Timp1 (Timp1(-/-)), we observed that females exhibit increased body weight by 3 months of age due to increased total body lipid and adipose tissue. Whereas Timp1(-/-) mice have increased size and number of adipocytes, they also display increased food intake despite hyperleptinemia, suggesting that alterations in hypothalamic leptin action or responsiveness may underlie their weight gain. Indeed, leptin promotes the expression of Timp1 mRNA in the hypothalamus, and leptin signaling via signal transducer and activator of transcription-3 mediates the expression of hypothalamic Timp1. Furthermore, Timp1(-/-) mice demonstrate increased food intake and altered expression of certain hypothalamic neuropeptide genes prior to elevated weight gain. Thus, whereas previous data suggested roles for matrix metalloproteinases and TIMPs in the regulation of adipose tissue, these data reveal that Timp1 mRNA is induced by leptin in the hypothalamus and that expression and action of Timp1 contributes to the regulation of feeding and energy balance.
Collapse
Affiliation(s)
- Isabelle Gerin
- Department of Molecular and Integrative Physiology, Ann Arbor, Michigan 48109-0622, USA
| | | | | | | | | | | | | | | |
Collapse
|
238
|
Williams KW, Scott MM, Elmquist JK. From observation to experimentation: leptin action in the mediobasal hypothalamus. Am J Clin Nutr 2009; 89:985S-990S. [PMID: 19176744 PMCID: PMC2667659 DOI: 10.3945/ajcn.2008.26788d] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The burgeoning obesity epidemic has fueled the drive to describe, mechanistically, metabolic homeostasis. From the early theories implicating glucose as a principal modulator grew an understanding of a complex array of metabolic signals, sensed by peripheral organs along with specific locations within the central nervous system (CNS). The discovery that leptin, an adipose-derived hormone, acts within the mediobasal hypothalamus to control food intake and energy expenditure ushered in a decade of research that went on to describe not only the specific nuclei and cell type, such as proopiomelanocortin neurons of the arcuate nucleus, that respond to leptin but also the signaling cascades that mediated its effects. This review thus highlights the sites and mechanisms of action of leptin, both in the hypothalamus and in extrahypothalamic sites within the CNS, and shows our current knowledge and direction of future research aimed at understanding the multifunctional role of leptin in maintaining metabolic homeostasis.
Collapse
Affiliation(s)
- Kevin W Williams
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 85390-905, USA
| | | | | |
Collapse
|
239
|
Minor RK, Chang JW, de Cabo R. Hungry for life: How the arcuate nucleus and neuropeptide Y may play a critical role in mediating the benefits of calorie restriction. Mol Cell Endocrinol 2009; 299:79-88. [PMID: 19041366 PMCID: PMC2668104 DOI: 10.1016/j.mce.2008.10.044] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Accepted: 10/14/2008] [Indexed: 11/27/2022]
Abstract
Laboratory studies consistently demonstrate extended lifespan in animals on calorie restriction (CR), where total caloric intake is reduced by 10-40% but adequate nutrition is otherwise maintained. CR has been further shown to delay the onset and severity of chronic diseases associated with aging such as cancer, and to extend the functional health span of important faculties like cognition. Less understood are the underlying mechanisms through which CR might act to induce such alterations. One theory postulates that CR's beneficial effects are intimately tied to the neuroendocrine response to low energy availability, of which the arcuate nucleus in the hypothalamus plays a pivotal role. Neuropeptide Y (NPY), a neurotransmitter in the front line of the arcuate response to low energy availability, is the primary hunger signal affected by CR and therefore may be a critical mechanism for lifespan extension.
Collapse
Affiliation(s)
- Robin K. Minor
- Laboratory of Experimental Gerontology, Intramural Research Program, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
| | - Joy W. Chang
- Laboratory of Experimental Gerontology, Intramural Research Program, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
| | - Rafael de Cabo
- Laboratory of Experimental Gerontology, Intramural Research Program, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
| |
Collapse
|
240
|
Myers MG, Münzberg H, Leinninger GM, Leshan RL. The geometry of leptin action in the brain: more complicated than a simple ARC. Cell Metab 2009; 9:117-23. [PMID: 19187770 PMCID: PMC2648854 DOI: 10.1016/j.cmet.2008.12.001] [Citation(s) in RCA: 219] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 11/10/2008] [Accepted: 12/04/2008] [Indexed: 01/07/2023]
Abstract
Leptin signals the repletion of fat stores, acting in the CNS to permit energy utilization by a host of autonomic and neuroendocrine processes and to decrease feeding. While much recent research has focused on the leptin-regulated circuitry of the hypothalamic arcuate nucleus (ARC), the majority of brain leptin receptor (LepRb)-expressing neurons lie outside the ARC in other CNS regions known to modulate energy balance. Each set of LepRb neurons throughout the brain presumably mediates unique aspects of leptin action, and understanding the function for LepRb-expressing neurons throughout the brain represents a crucial next step in the study of energy homeostasis.
Collapse
Affiliation(s)
- Martin G Myers
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA.
| | | | | | | |
Collapse
|
241
|
Richard D, Guesdon B, Timofeeva E. The brain endocannabinoid system in the regulation of energy balance. Best Pract Res Clin Endocrinol Metab 2009; 23:17-32. [PMID: 19285258 DOI: 10.1016/j.beem.2008.10.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The role played by the endocannabinoid system in the regulation of energy balance is currently generating a great amount of interest among several groups of investigators. This interest in large part comes from the urgent need to develop anti-obesity and anti-cachexia drugs around target systems (such as the endocannabinoid system), which appears to be genuinely involved in energy balance regulation. When activated, the endocannabinoid system favors energy deposition through increasing energy intake and reducing energy expenditure. This system is activated in obesity and following food deprivation, which further supports its authentic function in energy balance regulation. The cannabinoid receptor type 1 (CB1), one of the two identified cannabinoid receptors, is expressed in energy-balance brain structures that are also able to readily produce or inactivate N-arachidonoyl ethanolamine (anandamide) and 2-arachidonoylglycerol (2AG), the most abundantly formed and released endocannabinoids. The brain action of endocannabinoid system on energy balance seems crucial and needs to be delineated in the context of the homeostatic and hedonic controls of food intake and energy expenditure. These controls require the coordinated interaction of the hypothalamus, brainstem and limbic system and it appears imperative to unravel those interplays. It is also critical to investigate the metabolic endocannabinoid system while considering the panoply of functions that the endocannabinoid system fulfills in the brain and other tissues. This article aims at reviewing the potential mechanisms whereby the brain endocannabinoid system influences the regulation energy balance.
Collapse
Affiliation(s)
- Denis Richard
- Laval Hospital Research Center, Québec, Canada, G1V 4G5.
| | | | | |
Collapse
|
242
|
Abstract
The rising rate of obesity in Western countries has led to intensified efforts to understand the molecular mechanisms underlying the central control of appetite and feeding behavior. This report highlights studies published from 2006 to 2008 revealing novel centrally acting anorexigenic hormones, the continued unraveling of complex hypothalamic intracellular signaling pathways that regulate feeding, and insights into leptin resistance.
Collapse
Affiliation(s)
- Kristin A Anderson
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine Durham, NC 27710 USA.
| | | |
Collapse
|
243
|
Stengel A, Goebel M, Yakubov I, Wang L, Witcher D, Coskun T, Taché Y, Sachs G, Lambrecht NWG. Identification and characterization of nesfatin-1 immunoreactivity in endocrine cell types of the rat gastric oxyntic mucosa. Endocrinology 2009; 150:232-8. [PMID: 18818289 PMCID: PMC2630900 DOI: 10.1210/en.2008-0747] [Citation(s) in RCA: 249] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hypothalamic nesfatin-1, derived from the nucleobindin2 (NUCB2) precursor, inhibits nocturnal food intake and body weight gain in rats. Nesfatin-1 is able to cross the blood-brain barrier, suggesting a peripheral source of nesfatin-1. Many centrally acting food intake regulatory neuropeptides are also produced in the periphery, especially in the gastrointestinal tract. Therefore, we investigated the gene expression of NUCB2 and distribution of nesfatin-1-immunoreactive cells in the stomach. Microarray mRNA expression profiles in purified small endocrine cells of the gastric mucosa substantiated by quantitative RT-PCR showed significantly higher NUCB2 mRNA expression compared with brain and heart. Western blot confirmed the expression of NUCB2 protein and its transport into a secretory soluble fraction of gastric mucosal endocrine cell homogenates. Immunohistochemical colabeling for nesfatin-1 and ghrelin, histidine decarboxylase, or somatostatin revealed two subtypes of nesfatin-1-positive endocrine cells. Cells in the midportion of the glands coexpressed nesfatin-1 and ghrelin, whereas few cells in the glandular base coexpressed nesfatin-1 and somatostatin or histidine decarboxylase. High-resolution three-dimensional volume imaging revealed two separate populations of intracytoplasmic vesicles in these cells, one containing nesfatin-1 and the other ghrelin immunoreactivity. Microarray rat genome expression data of NUCB2 in small gastric endocrine cells confirmed by quantitative RT-PCR showed significant down-regulation of NUCB2 after 24 h fasting. In summary, NUCB2 mRNA expression as well as protein content is present in a specific subset of gastric endocrine cells, most of which coexpress ghrelin. NUCB2 gene expression is significantly regulated by nutritional status, suggesting a regulatory role of peripheral nesfatin-1 in energy homeostasis.
Collapse
Affiliation(s)
- Andreas Stengel
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division, Department of Medicine, University of California, Los Angeles, California, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
244
|
Impaired anorectic effect of leptin in neurotensin receptor 1-deficient mice. Behav Brain Res 2008; 194:66-71. [DOI: 10.1016/j.bbr.2008.06.024] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2008] [Revised: 06/17/2008] [Accepted: 06/20/2008] [Indexed: 11/21/2022]
|
245
|
Woods SC, D'Alessio DA. Central control of body weight and appetite. J Clin Endocrinol Metab 2008; 93:S37-50. [PMID: 18987269 PMCID: PMC2585760 DOI: 10.1210/jc.2008-1630] [Citation(s) in RCA: 302] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Accepted: 09/08/2008] [Indexed: 12/14/2022]
Abstract
CONTEXT Energy balance is critical for survival and health, and control of food intake is an integral part of this process. This report reviews hormonal signals that influence food intake and their clinical applications. EVIDENCE ACQUISITION A relatively novel insight is that satiation signals that control meal size and adiposity signals that signify the amount of body fat are distinct and interact in the hypothalamus and elsewhere to control energy homeostasis. This review focuses upon recent literature addressing the integration of satiation and adiposity signals and therapeutic implications for treatment of obesity. EVIDENCE SYNTHESIS During meals, signals such as cholecystokinin arise primarily from the GI tract to cause satiation and meal termination; signals secreted in proportion to body fat such as insulin and leptin interact with satiation signals and provide effective regulation by dictating meal size to amounts that are appropriate for body fatness, or stored energy. Although satiation and adiposity signals are myriad and redundant and reduce food intake, there are few known orexigenic signals; thus, initiation of meals is not subject to the degree of homeostatic regulation that cessation of eating is. There are now drugs available that act through receptors for satiation factors and which cause weight loss, demonstrating that this system is amenable to manipulation for therapeutic goals. CONCLUSIONS Although progress on effective medical therapies for obesity has been relatively slow in coming, advances in understanding the central regulation of food intake may ultimately be turned into useful treatment options.
Collapse
Affiliation(s)
- Stephen C Woods
- Department of Psychiatry, University of Cincinnati, Cincinnati, OH 45237, USA.
| | | |
Collapse
|
246
|
Park SM, Gaykema RPA, Goehler LE. How does immune challenge inhibit ingestion of palatable food? Evidence that systemic lipopolysaccharide treatment modulates key nodal points of feeding neurocircuitry. Brain Behav Immun 2008; 22:1160-72. [PMID: 18562160 PMCID: PMC2784149 DOI: 10.1016/j.bbi.2008.05.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 05/02/2008] [Accepted: 05/02/2008] [Indexed: 12/27/2022] Open
Abstract
Immune challenge induces behavioral changes including reduced ingestion of palatable food. Multiple pathways likely contribute to this effect, including viscerosensory pathways controlling hypothalamic feeding circuits or by influence on "reward" circuitry previously established to control ingestive behavior. To investigate whether the effects of immune challenge may influence this network, we compared brain activation patterns in animals trained to drink a palatable sweetened milk solution and treated systemically with either the immune stimulant lipopolysaccharide (LPS) or saline. Brain sections were processed for localization of the activation marker c-Fos in neurons of regions implicated in regulation of feeding behavior. Sweetened milk ingestion was associated with increased numbers of c-Fos positive neurons in the caudal core and shell of the nucleus accumbens (NAc), the paraventricular thalamus (PVT), central nucleus of the amygdala (CEA), the basal lateral amygdala (BLA), in orexin-A containing neurons of the lateral hypothalamus (LH), and in cocaine and amphetamine regulated transcript (CART) neurons of the arcuate hypothalamus. In LPS-treated animals sweetened milk consumption was significantly reduced, as was c-Fos induction in the hypothalamic orexin-A and CART neurons, and in the BLA. In addition, induction of c-Fos in the rostral regions of the NAc, the PVT, and CEA was increased following LPS treatment, compared to controls. The findings from this study point to a network of brain regions (LH, PVT, NAc, and BLA) previously implicated in the modulation of feeding behavior, reward, and arousal that may also contribute to neural substrates involved in the reorganization of behavioral priorities that occurs during sickness.
Collapse
|
247
|
Woods SC, Seeley RJ, Cota D. Regulation of food intake through hypothalamic signaling networks involving mTOR. Annu Rev Nutr 2008; 28:295-311. [PMID: 18429698 DOI: 10.1146/annurev.nutr.28.061807.155505] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To maintain normal activity, single cells must assure that their energy needs and utilization are continuously matched. Likewise, multicellular organisms must constantly coordinate energy intake and expenditure to maintain energy homeostasis. The brain, and the hypothalamus in particular, plays a critical role in integrating and coordinating several types of signals, including hormones and nutrients, to guarantee such homeostasis. Like single cells, the hypothalamus also profits from intracellular pathways known to work as fuel sensors to maintain energy balance. One such pathway is the mammalian target of rapamycin (mTOR). mTOR integrates different sensory inputs to regulate protein synthesis rates in individual cells, and it has recently been implicated in the central nervous system to regulate food intake and body weight as well. This review provides an overview of the role of hypothalamic intracellular fuel sensors in the overall control of energy balance and discusses the potential contribution of these fuel-sensing mechanisms to the metabolic dysregulation associated with obesity.
Collapse
Affiliation(s)
- Stephen C Woods
- Department of Psychiatry, Genome Research Institute, University of Cincinnati, Cincinnati, Ohio 45237, USA.
| | | | | |
Collapse
|
248
|
Södersten P, Nergårdh R, Bergh C, Zandian M, Scheurink A. Behavioral neuroendocrinology and treatment of anorexia nervosa. Front Neuroendocrinol 2008; 29:445-62. [PMID: 18602416 DOI: 10.1016/j.yfrne.2008.06.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 05/29/2008] [Accepted: 06/06/2008] [Indexed: 12/20/2022]
Abstract
Outcome in anorexia nervosa remains poor and a new way of looking at this condition is therefore needed. To this aim, we review the effects of food restriction and starvation in humans. It is suggested that body weight remains stable and relatively low when the access to food requires a considerable amount of physical activity. In this condition, the human homeostatic phenotype, body fat content is also low and as a consequence, the synthesis and release of brain neurotransmitters are modified. As an example, the role of neuropeptide Y is analyzed in rat models of this state. It is suggested that the normal behavioral role of neuropeptide Y is to facilitate the search for food and switch attention from sexual stimuli to food. Descriptive neuroendocrine studies on patients with anorexia nervosa have not contributed to the management of the patients and the few studies in which hormones have been administered have, at best, reversed an endocrine consequence secondary to starvation. In a modified framework for understanding the etiology and treatment of anorexia nervosa it is suggested that the condition emerges because neural mechanisms of reward and attention are engaged. The neural neuropeptide Y receptor system may be involved in the maintenance of the behavior of eating disorder patients because the localization of these receptors overlaps with the neural systems engaged in cue-conditioned eating in limbic and cortical areas. The eating behavior of patients with anorexia nervosa, and other eating disorders as well, is viewed as a cause of the psychological changes of the patients. Patients are trained to re-learn normal eating habits using external support and as they do, their symptoms, including the psychological symptoms, dissolve.
Collapse
Affiliation(s)
- P Södersten
- Karolinska Institutet, Section of Applied Neuroendocrinology, Mandometer Clinic, AB Mando Novum, S-141 57 Huddinge, Sweden.
| | | | | | | | | |
Collapse
|
249
|
Robertson SA, Leinninger GM, Myers MG. Molecular and neural mediators of leptin action. Physiol Behav 2008; 94:637-42. [PMID: 18501391 PMCID: PMC2516921 DOI: 10.1016/j.physbeh.2008.04.005] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Accepted: 04/02/2008] [Indexed: 01/17/2023]
Abstract
The adipose tissue-derived hormone, leptin, acts via its receptor (LepRb) in the brain to regulate energy balance and neuroendocrine function. Parsing the biology of leptin requires understanding LepRb signaling and the roles for specific signaling pathways in neural and physiological leptin action. Since the leptin acts via a broadly distributed network of LepRb-expressing neurons, understanding the function of each of these LepRb neural populations will also be crucial. Here, we review the status of knowledge regarding the molecular mediators of leptin action and the neural substrate via which leptin acts to regulate physiologic processes.
Collapse
Affiliation(s)
- Scott A. Robertson
- Division of Metabolism, Endocrinology and Diabetes, Department of Medicine and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Gina M. Leinninger
- Division of Metabolism, Endocrinology and Diabetes, Department of Medicine and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Martin G. Myers
- Division of Metabolism, Endocrinology and Diabetes, Department of Medicine and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| |
Collapse
|
250
|
Coyle CA, Strand SC, Good DJ. Reduced activity without hyperphagia contributes to obesity in Tubby mutant mice. Physiol Behav 2008; 95:168-75. [PMID: 18619628 DOI: 10.1016/j.physbeh.2008.05.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 05/22/2008] [Accepted: 05/23/2008] [Indexed: 10/22/2022]
Abstract
The Tub gene was originally identified as a spontaneous mutation in C57Bl/6J mice, and associated with adult-onset obesity (Tub MUT mice). Although the original Tub MUT mouse was identified over 15 years ago, there have been few reports on the animal's food intake, body fat percentage or energy expenditure. In this study, we report food intake, body weight from 5-20 weeks, body fat, body temperature and three different measures of physical activity behavior. Tub MUT mice display reduced food intake, uncharacteristic of many obese mouse models, and reduced voluntary wheel running with normal home cage ambulatory behavior. We conclude that motivation for food and exercise is an underlying defect in TUB MUT mice.
Collapse
Affiliation(s)
- Christopher A Coyle
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, United States
| | | | | |
Collapse
|