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Wei R, Li D, Jia S, Chen Y, Wang J. MC4R in Central and Peripheral Systems. Adv Biol (Weinh) 2023; 7:e2300035. [PMID: 37043700 DOI: 10.1002/adbi.202300035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 02/25/2023] [Indexed: 04/14/2023]
Abstract
Obesity has emerged as a critical and urgent health burden during the current global pandemic. Among multiple genetic causes, melanocortin receptor-4 (MC4R), involved in food intake and energy metabolism regulation through various signaling pathways, has been reported to be the lead genetic factor in severe and early onset obesity and hyperphagia disorders. Most previous studies have illustrated the roles of MC4R signaling in energy intake versus expenditure in the central system, while some evidence indicates that MC4R is also expressed in peripheral systems, such as the gut and endocrine organs. However, its physiopathological function remains poorly defined. This review aims to depict the central and peripheral roles of MC4R in energy metabolism and endocrine hormone homeostasis, the diversity of phenotypes, biased downstream signaling caused by distinct MC4R mutations, and current drug development targeting the receptor.
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Affiliation(s)
- Ran Wei
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
- Department of Endocrinology, Shanghai Fifth People's Hospital, Fudan University, Shanghai, 200240, China
| | - Danjie Li
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
| | - Sheng Jia
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
| | - Yuhong Chen
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
| | - Jiqiu Wang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Shanghai, 200025, China
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Anhê GF, Bordin S. The adaptation of maternal energy metabolism to lactation and its underlying mechanisms. Mol Cell Endocrinol 2022; 553:111697. [PMID: 35690287 DOI: 10.1016/j.mce.2022.111697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 04/15/2022] [Accepted: 06/01/2022] [Indexed: 11/29/2022]
Abstract
Maternal energy metabolism undergoes a singular adaptation during lactation that allows for the caloric enrichment of milk. Changes in the mammary gland, changes in the white adipose tissue, brown adipose tissue, liver, skeletal muscles and endocrine pancreas are pivotal for this adaptation. The present review details the landmark studies describing the enzymatic modulation and the endocrine signals behind these metabolic changes. We will also update this perspective with data from recent studies showing transcriptional and post-transcriptional mechanisms that mediate the adaptation of the maternal metabolism to lactation. The present text will also bring experimental and observational data that describe the long-term consequences that short periods of lactation impose to maternal metabolism.
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Affiliation(s)
- Gabriel Forato Anhê
- Department of Translational Medicine, School of Medical Sciences, State University of Campinas, Campinas, Brazil.
| | - Silvana Bordin
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
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Misch M, Puthanveetil P. The Head-to-Toe Hormone: Leptin as an Extensive Modulator of Physiologic Systems. Int J Mol Sci 2022; 23:ijms23105439. [PMID: 35628271 PMCID: PMC9141226 DOI: 10.3390/ijms23105439] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/30/2022] [Accepted: 05/10/2022] [Indexed: 12/12/2022] Open
Abstract
Leptin is a well-known hunger-sensing peptide hormone. The role of leptin in weight gain and metabolic homeostasis has been explored for the past two decades. In this review, we have tried to shed light upon the impact of leptin signaling on health and diseases. At low or moderate levels, this peptide hormone supports physiological roles, but at chronically higher doses exhibits detrimental effects on various systems. The untoward effects we observe with chronically higher levels of leptin are due to their receptor-mediated effect or due to leptin resistance and are not well studied. This review will help us in understanding the non-anorexic roles of leptin, including their contribution to the metabolism of various systems and inflammation. We will be able to get an alternative perspective regarding the physiological and pathological roles of this mysterious peptide hormone.
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Affiliation(s)
- Monica Misch
- Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, IL 60515, USA;
| | - Prasanth Puthanveetil
- Department of Pharmacology, College of Graduate Studies, Midwestern University, Downers Grove, IL 60515, USA
- Correspondence: ; Tel.: +1-630-960-3935
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Rønnekleiv OK, Qiu J, Kelly MJ. Hypothalamic Kisspeptin Neurons and the Control of Homeostasis. Endocrinology 2022; 163:bqab253. [PMID: 34953135 PMCID: PMC8758343 DOI: 10.1210/endocr/bqab253] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Indexed: 12/27/2022]
Abstract
Hypothalamic kisspeptin (Kiss1) neurons provide indispensable excitatory transmission to gonadotropin-releasing hormone (GnRH) neurons for the coordinated release of gonadotropins, estrous cyclicity, and ovulation. But maintaining reproductive functions is metabolically demanding so there must be a coordination with multiple homeostatic functions, and it is apparent that Kiss1 neurons play that role. There are 2 distinct populations of hypothalamic Kiss1 neurons, namely arcuate nucleus (Kiss1ARH) neurons and anteroventral periventricular and periventricular nucleus (Kiss1AVPV/PeN) neurons in rodents, both of which excite GnRH neurons via kisspeptin release but are differentially regulated by ovarian steroids. Estradiol (E2) increases the expression of kisspeptin in Kiss1AVPV/PeN neurons but decreases its expression in Kiss1ARH neurons. Also, Kiss1ARH neurons coexpress glutamate and Kiss1AVPV/PeN neurons coexpress gamma aminobutyric acid (GABA), both of which are upregulated by E2 in females. Also, Kiss1ARH neurons express critical metabolic hormone receptors, and these neurons are excited by insulin and leptin during the fed state. Moreover, Kiss1ARH neurons project to and excite the anorexigenic proopiomelanocortin neurons but inhibit the orexigenic neuropeptide Y/Agouti-related peptide neurons, highlighting their role in regulating feeding behavior. Kiss1ARH and Kiss1AVPV/PeN neurons also project to the preautonomic paraventricular nucleus (satiety) neurons and the dorsomedial nucleus (energy expenditure) neurons to differentially regulate their function via glutamate and GABA release, respectively. Therefore, this review will address not only how Kiss1 neurons govern GnRH release, but how they control other homeostatic functions through their peptidergic, glutamatergic and GABAergic synaptic connections, providing further evidence that Kiss1 neurons are the key neurons coordinating energy states with reproduction.
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Affiliation(s)
- Oline K Rønnekleiv
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
| | - Jian Qiu
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Martin J Kelly
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
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Arcuate and Preoptic Kisspeptin Neurons Exhibit Differential Projections to Hypothalamic Nuclei and Exert Opposite Postsynaptic Effects on Hypothalamic Paraventricular and Dorsomedial Nuclei in the Female Mouse. eNeuro 2021; 8:ENEURO.0093-21.2021. [PMID: 34281980 PMCID: PMC8354717 DOI: 10.1523/eneuro.0093-21.2021] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/21/2021] [Accepted: 07/11/2021] [Indexed: 01/24/2023] Open
Abstract
Kisspeptin (Kiss1) neurons provide indispensable excitatory input to gonadotropin-releasing hormone (GnRH) neurons, which is important for the coordinated release of gonadotropins, estrous cyclicity and ovulation. However, Kiss1 neurons also send projections to many other brain regions within and outside the hypothalamus. Two different populations of Kiss1 neurons, one in the arcuate nucleus (Kiss1ARH) and another in the anteroventral periventricular nucleus (AVPV) and periventricular nucleus (PeN; Kiss1AVPV/PeN) of the hypothalamus are differentially regulated by ovarian steroids, and are believed to form direct contacts with GnRH neurons as well as other neurons. To investigate the projection fields from Kiss1AVPV/PeN and Kiss1ARH neurons in female mice, we used anterograde projection analysis, and channelrhodopsin-assisted circuit mapping (CRACM) to explore their functional input to select target neurons within the paraventricular (PVH) and dorsomedial (DMH) hypothalamus, key preautonomic nuclei. Cre-dependent viral (AAV1-DIO-ChR2 mCherry) vectors were injected into the brain to label the two Kiss1 neuronal populations. Immunocytochemistry (ICC) for mCherry and neuropeptides combined with confocal microscopy was used to determine the projection-fields of both Kiss1 neuronal groups. Whole-cell electrophysiology and optogenetics were used to elucidate the functional input to the PVH and DMH. Our analysis revealed many common but also several clearly separate projection fields between the two different populations of Kiss1 neurons. In addition, optogenetic stimulation of Kiss1 projections to PVH prodynorphin, Vglut2 and DMH CART-expressing neurons, revealed excitatory glutamatergic input from Kiss1ARH neurons and inhibitory GABAergic input from Kiss1AVPV/PeN neurons. Therefore, these steroid-sensitive Kiss1 neuronal groups can differentially control the excitability of target neurons to coordinate autonomic functions with reproduction.
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Trotta M, Bello EP, Alsina R, Tavella MB, Ferrán JL, Rubinstein M, Bumaschny VF. Hypothalamic Pomc expression restricted to GABAergic neurons suppresses Npy overexpression and restores food intake in obese mice. Mol Metab 2020; 37:100985. [PMID: 32311511 PMCID: PMC7292867 DOI: 10.1016/j.molmet.2020.100985] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 03/17/2020] [Accepted: 03/23/2020] [Indexed: 12/28/2022] Open
Abstract
Objective Hypothalamic arcuate proopiomelanocortin (Arc-POMC) neurons are involved in different physiological processes such as the regulation of energy balance, glucose homeostasis, and stress-induced analgesia. Since these neurons heterogeneously express different biological markers and project to many hypothalamic and extrahypothalamic areas, it is proposed that Arc-POMC neurons could be classified into different subpopulations having diverse physiological roles. The aim of the present study was to characterize the contribution of the subpopulation of Arc-POMC neurons cosecreting gamma-aminobutyric acid (GABA) neurotransmitter in the control of energy balance. Methods Arc-Pomc expression restricted to GABAergic-POMC neurons was achieved by crossing a reversible Pomc-deficient mouse line (arcPomc−) with a tamoxifen-inducible Gad2-CreER transgenic line. Pomc expression was rescued in the compound arcPomc−/−:Gad2-CreER female and male mice by tamoxifen treatment at postnatal days 25 (P25) or 60 (P60), and body weight, daily food intake, fasting glycemia, and fasting-induced hyperphagia were measured. POMC recovery was quantified by immunohistochemistry and semiquantitative RT-PCR. Neuropeptide Y (NPY) and GABAergic neurons were identified by in situ hybridization. Arc-POMC neurons projecting to the dorsomedial hypothalamic nucleus (DMH) were studied by stereotactic intracerebral injection of fluorescent retrobeads into the DMH. Results Tamoxifen treatment of arcPomc−/−:Gad2-CreER mice at P60 resulted in Pomc expression in ∼23–25% of Arc-POMC neurons and ∼15–23% of Pomc mRNA levels, compared to Gad2-CreER control mice. Pomc rescue in GABAergic-POMC neurons at P60 normalized food intake, glycemia, and fasting-induced hyperphagia, while significantly reducing body weight. Energy balance was also improved in arcPomc−/−:Gad2-CreER mice treated with tamoxifen at P25. Distribution analysis of rescued POMC immunoreactive fibers revealed that the DMH is a major target site of GABAergic-POMC neurons. Further, the expression of the orexigenic neuropeptide Y (NPY) in the DMH was increased in arcPomc−/− obese mice but was completely restored after Pomc rescue in arcPomc−/−:Gad2-CreER mice. Finally, we found that ∼75% of Arc-POMC neurons projecting to the DMH are GABAergic. Conclusions In the present study, we show that the expression of Pomc in the subpopulation of Arc-GABAergic-POMC neurons is sufficient to maintain normal food intake. In addition, we found that DMH-NPY expression is negatively correlated with Pomc expression in GABAergic-POMC neurons, suggesting that food intake may be regulated by an Arc-GABAergic-POMC → DMH-NPY pathway. The subpopulation of arcuate GABAergic-POMC neurons is sufficient to maintain normal food intake. Overweight induced by Pomc deficiency is reduced by arcuate Pomc expression restricted to GABAergic-POMC neurons. DMH-Npy overexpression in POMC-deficient mice is restored by Pomc rescue restricted to GABAergic-POMC neurons. Arcuate POMC neurons projecting to the DMH are mainly GABAergic.
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Affiliation(s)
- Milagros Trotta
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO HOUSSAY), Facultad de Medicina, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina.
| | - Estefanía Pilar Bello
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO HOUSSAY), Facultad de Medicina, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina.
| | - Ramiro Alsina
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO HOUSSAY), Facultad de Medicina, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina.
| | - María Belén Tavella
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, 1428, Ciudad Autónoma de Buenos Aires, Argentina.
| | - José Luis Ferrán
- Department of Human Anatomy, School of Medicine, University of Murcia and IMIB-Arrixaca Institute, Carretera Buenavista s/n, 30120, El Palmar, Murcia, Spain.
| | - Marcelo Rubinstein
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, 1428, Ciudad Autónoma de Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Ciudad Autónoma de Buenos Aires, Argentina.
| | - Viviana Florencia Bumaschny
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO HOUSSAY), Facultad de Medicina, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina; Departamento de Ciencias Fisiológicas, Facultad de Medicina. Universidad de Buenos Aires, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina.
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Switching off the furnace: brown adipose tissue and lactation. Mol Aspects Med 2019; 68:18-41. [DOI: 10.1016/j.mam.2019.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/12/2019] [Indexed: 12/31/2022]
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Quitete FT, de Moura EG, Atella GC, Lisboa PC, de Oliveira E. Differential effects in male adult rats of lifelong coconut oil exposure versus during early-life only. J Funct Foods 2019. [DOI: 10.1016/j.jff.2019.02.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Baldini G, Phelan KD. The melanocortin pathway and control of appetite-progress and therapeutic implications. J Endocrinol 2019; 241:R1-R33. [PMID: 30812013 PMCID: PMC6500576 DOI: 10.1530/joe-18-0596] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 01/22/2019] [Indexed: 12/19/2022]
Abstract
The initial discovery that ob/ob mice become obese because of a recessive mutation of the leptin gene has been crucial to discover the melanocortin pathway to control appetite. In the melanocortin pathway, the fed state is signaled by abundance of circulating hormones such as leptin and insulin, which bind to receptors expressed at the surface of pro-opiomelanocortin (POMC) neurons to promote processing of POMC to the mature hormone α-melanocyte-stimulating hormone (α-MSH). The α-MSH released by POMC neurons then signals to decrease energy intake by binding to melanocortin-4 receptor (MC4R) expressed by MC4R neurons to the paraventricular nucleus (PVN). Conversely, in the 'starved state' activity of agouti-related neuropeptide (AgRP) and of neuropeptide Y (NPY)-expressing neurons is increased by decreased levels of circulating leptin and insulin and by the orexigenic hormone ghrelin to promote food intake. This initial understanding of the melanocortin pathway has recently been implemented by the description of the complex neuronal circuit that controls the activity of POMC, AgRP/NPY and MC4R neurons and downstream signaling by these neurons. This review summarizes the progress done on the melanocortin pathway and describes how obesity alters this pathway to disrupt energy homeostasis. We also describe progress on how leptin and insulin receptors signal in POMC neurons, how MC4R signals and how altered expression and traffic of MC4R change the acute signaling and desensitization properties of the receptor. We also describe how the discovery of the melanocortin pathway has led to the use of melanocortin agonists to treat obesity derived from genetic disorders.
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Affiliation(s)
- Giulia Baldini
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Kevin D. Phelan
- Department of Neurobiology & Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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van den Pol AN, Acuna C, Davis JN, Huang H, Zhang X. Defining the caudal hypothalamic arcuate nucleus with a focus on anorexic excitatory neurons. J Physiol 2019; 597:1605-1625. [PMID: 30618146 PMCID: PMC6418765 DOI: 10.1113/jp277152] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/03/2019] [Indexed: 01/11/2023] Open
Abstract
KEY POINTS Excitatory glutamate neurons are sparse in the rostral hypothalamic arcuate nucleus (ARC), the subregion that has received the most attention in the past. In striking contrast, excitatory neurons are far more common (by a factor of 10) in the caudal ARC, an area which has received relatively little attention. These glutamate cells may play a negative role in energy balance and food intake. They can show an increase in phosphorylated Stat-3 in the presence of leptin, are electrically excited by the anorectic neuromodulator cholecystokinin, and inhibited by orexigenic neuromodulators neuropeptide Y, met-enkephalin, dynorphin and the catecholamine dopamine. The neurons project local axonal connections that excite other ARC neurons including proopiomelanocortin neurons that can play an important role in obesity. These data are consistent with models suggesting that the ARC glutamatergic neurons may play both a rapid and a slower role in acting as anorectic neurons in CNS control of food intake and energy homeostasis. ABSTRACT Here we interrogate a unique class of excitatory neurons in the hypothalamic arcuate nucleus (ARC) that utilizes glutamate as a fast neurotransmitter using mice expressing GFP under control of the vesicular glutamate transporter 2 (vGluT2) promoter. These neurons show a unique distribution, synaptic characterization, cellular physiology and response to neuropeptides involved in energy homeostasis. Although apparently not previously appreciated, the caudal ARC showed a far greater density of vGluT2 cells than the rostral ARC, as seen in transgenic vGluT2-GFP mice and mRNA analysis. After food deprivation, leptin induced an increase in phosphorylated Stat-3 in vGluT2-positive neurons, indicating a response to hormonal cues of energy state. Based on whole-cell recording electrophysiology in brain slices, vGluT2 neurons were spontaneously active with a spike frequency around 2 Hz. vGluT2 cells were responsive to a number of neuropeptides related to energy homeostasis; they were excited by the anorectic peptide cholecystokinin, but inhibited by orexigenic neuropeptide Y, dynorphin and met-enkephalin, consistent with an anorexic role in energy homeostasis. Dopamine, associated with the hedonic aspect of enhancing food intake, inhibited vGluT2 neurons. Optogenetic excitation of vGluT2 cells evoked EPSCs in neighbouring neurons, indicating local synaptic excitation of other ARC neurons. Microdrop excitation of ARC glutamate cells in brain slices rapidly increased excitatory synaptic activity in anorexigenic proopiomelanocortin neurons. Together these data support the perspective that vGluT2 cells may be more prevalent in the ARC than previously appreciated, and play predominantly an anorectic role in energy metabolism.
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Affiliation(s)
| | - Claudio Acuna
- Department of NeurosurgeryYale University School of MedicineNew HavenCT06520USA
| | - John N. Davis
- Department of NeurosurgeryYale University School of MedicineNew HavenCT06520USA
| | - Hao Huang
- Department of NeurosurgeryYale University School of MedicineNew HavenCT06520USA
| | - Xiaobing Zhang
- Department of NeurosurgeryYale University School of MedicineNew HavenCT06520USA
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Morrison SF. Efferent neural pathways for the control of brown adipose tissue thermogenesis and shivering. HANDBOOK OF CLINICAL NEUROLOGY 2018; 156:281-303. [PMID: 30454595 DOI: 10.1016/b978-0-444-63912-7.00017-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The fundamental central neural circuits for thermoregulation orchestrate behavioral and autonomic repertoires that maintain body core temperature during thermal challenges that arise from either the ambient or the internal environment. This review summarizes our understanding of the neural pathways within the fundamental thermoregulatory reflex circuitry that comprise the efferent (i.e., beyond thermosensory) control of brown adipose tissue (BAT) and shivering thermogenesis: the motor neuron systems consisting of the BAT sympathetic preganglionic neurons and BAT sympathetic ganglion cells, and the alpha- and gamma-motoneurons; the premotor neurons in the region of the rostral raphe pallidus, and the thermogenesis-promoting neurons in the dorsomedial hypothalamus/dorsal hypothalamic area. Also included are inputs to, and neurochemical modulators of, these efferent neuronal populations that could influence their activity during thermoregulatory responses. Signals of metabolic status can be particularly significant for the energy-hungry thermoeffectors for heat production.
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Affiliation(s)
- Shaun F Morrison
- Department of Neurological Surgery, Oregon Health and Science University, Portland, OR, United States.
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Bal NC, Singh S, Reis FCG, Maurya SK, Pani S, Rowland LA, Periasamy M. Both brown adipose tissue and skeletal muscle thermogenesis processes are activated during mild to severe cold adaptation in mice. J Biol Chem 2017; 292:16616-16625. [PMID: 28794154 DOI: 10.1074/jbc.m117.790451] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 07/24/2017] [Indexed: 11/06/2022] Open
Abstract
Thermogenesis is an important homeostatic mechanism essential for survival and normal physiological functions in mammals. Both brown adipose tissue (BAT) (i.e. uncoupling protein 1 (UCP1)-based) and skeletal muscle (i.e. sarcolipin (SLN)-based) thermogenesis processes play important roles in temperature homeostasis, but their relative contributions differ from small to large mammals. In this study, we investigated the functional interplay between skeletal muscle- and BAT-based thermogenesis under mild versus severe cold adaptation by employing UCP1-/- and SLN-/- mice. Interestingly, adaptation of SLN-/- mice to mild cold conditions (16 °C) significantly increased UCP1 expression, suggesting increased reliance on BAT-based thermogenesis. This was also evident from structural alterations in BAT morphology, including mitochondrial architecture, increased expression of electron transport chain proteins, and depletion of fat droplets. Similarly, UCP1-/- mice adapted to mild cold up-regulated muscle-based thermogenesis, indicated by increases in muscle succinate dehydrogenase activity, SLN expression, mitochondrial content, and neovascularization, compared with WT mice. These results further confirm that SLN-based thermogenesis is a key player in muscle non-shivering thermogenesis (NST) and can compensate for loss of BAT activity. We also present evidence that the increased reliance on BAT-based NST depends on increased autonomic input, as indicated by abundant levels of tyrosine hydroxylase and neuropeptide Y. Our findings demonstrate that both BAT and muscle-based NST are equally recruited during mild and severe cold adaptation and that loss of heat production from one thermogenic pathway leads to increased recruitment of the other, indicating a functional interplay between these two thermogenic processes.
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Affiliation(s)
- Naresh C Bal
- From the School of Biotechnology, KIIT University, Bhubaneswar, Odisha 751024, India, .,the Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, Ohio 43210, and.,the Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827
| | - Sushant Singh
- the Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, Ohio 43210, and.,the Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827
| | - Felipe C G Reis
- the Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827
| | - Santosh K Maurya
- the Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, Ohio 43210, and.,the Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827
| | - Sunil Pani
- From the School of Biotechnology, KIIT University, Bhubaneswar, Odisha 751024, India
| | - Leslie A Rowland
- the Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, Ohio 43210, and
| | - Muthu Periasamy
- the Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, Ohio 43210, and .,the Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827
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Otgon-Uul Z, Suyama S, Onodera H, Yada T. Optogenetic activation of leptin- and glucose-regulated GABAergic neurons in dorsomedial hypothalamus promotes food intake via inhibitory synaptic transmission to paraventricular nucleus of hypothalamus. Mol Metab 2016; 5:709-715. [PMID: 27656408 PMCID: PMC5021668 DOI: 10.1016/j.molmet.2016.06.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 06/15/2016] [Accepted: 06/16/2016] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE The dorsomedial hypothalamus (DMH) has been considered an orexigenic nucleus, since the DMH lesion reduced food intake and body weight and induced resistance to diet-induced obesity. The DMH expresses feeding regulatory neuropeptides and receptors including neuropeptide Y (NPY), cocaine- and amphetamine-regulated transcript (CART), cholecystokinin (CCK), leptin receptor, and melanocortin 3/4 receptors. However, the principal neurons generating the orexigenic function in the DMH remain to be defined. This study aimed to clarify the role of the DMH GABAergic neurons in feeding regulation by using optogenetics and electrophysiological techniques. METHODS We generated the mice expressing ChRFR-C167A, a bistable chimeric channelrhodopsin, selectively in GABAergic neurons of DMH via locally injected adeno-associated virus 2. Food intake after optogenetic activation of DMH GABAergic neurons was measured. Electrophysiological properties of DMH GABAergic neurons were measured using slice patch clamp. RESULTS Optogenetic activation of DMH GABAergic neurons promoted food intake. Leptin hyperpolarized and lowering glucose depolarized half of DMH GABAergic neurons, suggesting their orexigenic property. Optical activation of axonal terminals of DMH GABAergic neurons at the paraventricular nucleus of hypothalamus (PVN), where anorexigenic neurons are localized, increased inhibitory postsynaptic currents on PVN neurons and promoted food intake. CONCLUSION DMH GABAergic neurons are regulated by metabolic signals leptin and glucose and, once activated, promote food intake via inhibitory synaptic transmission to PVN.
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Affiliation(s)
- Zesemdorj Otgon-Uul
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, 3311-1 Yakushiji, Shimotsuke, Tochigi, 320-0498, Japan
| | - Shigetomo Suyama
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, 3311-1 Yakushiji, Shimotsuke, Tochigi, 320-0498, Japan
| | - Hiroshi Onodera
- Photon Science Center of the University of Tokyo, Department of Electrical Engineering of the University of Tokyo, Tokyo, Japan
| | - Toshihiko Yada
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, 3311-1 Yakushiji, Shimotsuke, Tochigi, 320-0498, Japan.
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14
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Alvarez-Crespo M, Csikasz RI, Martínez-Sánchez N, Diéguez C, Cannon B, Nedergaard J, López M. Essential role of UCP1 modulating the central effects of thyroid hormones on energy balance. Mol Metab 2016; 5:271-282. [PMID: 27069867 PMCID: PMC4812006 DOI: 10.1016/j.molmet.2016.01.008] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/18/2016] [Accepted: 01/22/2016] [Indexed: 01/05/2023] Open
Abstract
Objective Classically, metabolic effects of thyroid hormones (THs) have been considered to be peripherally mediated, i.e. different tissues in the body respond directly to thyroid hormones with an increased metabolism. An alternative view is that the metabolic effects are centrally regulated. We have examined here the degree to which prolonged, centrally infused triiodothyronine (T3) could in itself induce total body metabolic effects and the degree to which brown adipose tissue (BAT) thermogenesis was essential for such effects, by examining uncoupling protein 1 (UCP1) KO mice. Methods Wildtype and UPC1 KO mice were centrally-treated with T3 by using minipumps. Metabolic measurements were analyzed by indirect calorimetry and expression analysis by RT-PCR or western blot. BAT morphology and histology were studied by immunohistochemistry. Results We found that central T3-treatment led to reduced levels of hypothalamic AMP-activated protein kinase (AMPK) and elevated body temperature (0.7 °C). UCP1 was essential for the T3-induced increased rate of energy expenditure, which was only observable at thermoneutrality and notably only during the active phase, for the increased body weight loss, for the increased hypothalamic levels of neuropeptide Y (NPY) and agouti-related peptide (AgRP) and for the increased food intake induced by central T3-treatment. Prolonged central T3-treatment also led to recruitment of BAT and britening/beiging (“browning”) of inguinal white adipose tissue (iWAT). Conclusions We conclude that UCP1 is essential for mediation of the central effects of thyroid hormones on energy balance, and we suggest that similar UCP1-dependent effects may underlie central energy balance effects of other agents. Central thyroid hormone (TH) increases brown adipose tissue (BAT) thermogenesis. Central TH increases oxygen consumption and energy expenditure. Central TH increases food intake. Central TH promotes britening/beiging of white adipose tissue (WAT). All these metabolic effects of central TH are lost in UCP1 knockout mice.
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Affiliation(s)
- Mayte Alvarez-Crespo
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain
| | - Robert I Csikasz
- The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Noelia Martínez-Sánchez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain
| | - Carlos Diéguez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain
| | - Barbara Cannon
- The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Jan Nedergaard
- The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91, Stockholm, Sweden.
| | - Miguel López
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain.
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15
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Zhang JY, Zhao XY, Wen J, Tan S, Zhao ZJ. Plasticity in gastrointestinal morphology and enzyme activity in lactating striped hamsters (Cricetulus barabensis). J Exp Biol 2016; 219:1327-36. [DOI: 10.1242/jeb.138396] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 02/19/2016] [Indexed: 11/20/2022]
Abstract
In small mammals marked phenotypic plasticity of digestive physiology has been shown to make it easier to cope with the energetically stressful periods, such as lactation. It has been proposed that the capacity of the gut to digest and absorb food is not the factor limiting to sustained energy intake (SusEI) during peak lactation. In this study, plasticity in energy intake and gastrointestinal morphology was examined in striped hamsters at different stages of reproduction and raising litters of different sizes. Mechanisms associated with digestive enzymes and neuroendocrine hormones underpinning the plasticity were also examined. The females significantly increased energy intake, digestibility, masses of digestive tracts and activity of stomach pepsin and maltase, sucrase and aminopeptidase of small intestine in peak lactation compared to the non-productive and post-lactating periods. Further, the females raising large litters significantly increased energy intake, digestibility, gastrointestinal mass and activity of digestive enzymes, and weaned heavier offspring compared with those nursing small and medium litters, indicating that the significant plasticity of digestive physiology increased reproductive performance. The agouti-related protein (AgRP) mRNA expression in the hypothalamus was up-regulated significantly in the females raising large litters relative to those raising small litters. Serum leptin levels, hypothalamus neuropeptide Y (NPY), or anorexigenic neuropeptides (pro-opiomelanocortin / cocaine- and amphetamine-regulated transcript, POMC / CART) mRNA expression did not differ among the females raising small, medium and large litters, indicating that leptin levels in lactation might only reflect a state of energy balance rather than being the prime driver of hyperphagia. Some hypothalamic neuropeptides, such as NPY, POMC and CART, would be involved in the limits to the SusEI during lactation.
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Affiliation(s)
- Ji-Ying Zhang
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Xiao-Ya Zhao
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Jing Wen
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Song Tan
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Zhi-Jun Zhao
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
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16
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Lactation and appetite-regulating hormones: increased maternal plasma peptide YY concentrations 3-6 months postpartum. Br J Nutr 2015; 114:1203-8. [PMID: 26299586 DOI: 10.1017/s0007114515002536] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Breast-feeding is associated with maternal hormonal and metabolic changes ensuring adequate milk production. In this study, we investigate the impact of breast-feeding on the profile of changes in maternal appetite-regulating hormones 3-6 months postpartum. Study participants were age- and BMI-matched lactating mothers (n 10), non-lactating mothers (n 9) and women without any history of pregnancy or breast-feeding in the previous 12 months (control group, n 10). During study sessions, young mothers breast-fed or bottle-fed their babies, and maternal blood samples were collected at five time points during 90 min: before, during and after feeding the babies. Outcome parameters were plasma concentrations of ghrelin, peptide YY (PYY), leptin, adiponectin, prolactin, cortisol, insulin, glucose and lipid values. At baseline, circulating PYY concentrations were significantly increased in lactating mothers (100·3 (se 6·7) pg/ml) v. non-lactating mothers (73·6 (se 4·9) pg/ml, P=0·008) and v. the control group (70·2 (se 9) pg/ml, P=0·021). We found no differences in ghrelin, leptin and adiponectin values. Baseline prolactin concentrations were over 4-fold higher in lactating mothers (P<0·001). Lactating women had reduced TAG levels and LDL-cholesterol:HDL-cholesterol ratio, but increased waist circumference, when compared with non-lactating women. Breast-feeding sessions further elevated circulating prolactin (P<0·001), but induced no acute effects on appetite-regulating hormones. In summary, one single breast-feeding session did not acutely modulate circulating appetite-regulating hormones, but increased baseline PYY concentrations are associated with prolonged lactation. PYY might play a role in the coordination of energy balance during lactation, increasing fat mobilisation from maternal depots and ensuring adequate milk production for the demands of the growing infant.
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17
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Luchtman DW, Chee MJS, Doslikova B, Marks DL, Baracos VE, Colmers WF. Defense of Elevated Body Weight Setpoint in Diet-Induced Obese Rats on Low Energy Diet Is Mediated by Loss of Melanocortin Sensitivity in the Paraventricular Hypothalamic Nucleus. PLoS One 2015; 10:e0139462. [PMID: 26444289 PMCID: PMC4596859 DOI: 10.1371/journal.pone.0139462] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 09/12/2015] [Indexed: 01/15/2023] Open
Abstract
Some animals and humans fed a high-energy diet (HED) are diet-resistant (DR), remaining as lean as individuals who were naïve to HED. Other individuals become obese during HED exposure and subsequently defend the obese weight (Diet-Induced Obesity- Defenders, DIO-D) even when subsequently maintained on a low-energy diet. We hypothesized that the body weight setpoint of the DIO-D phenotype resides in the hypothalamic paraventricular nucleus (PVN), where anorexigenic melanocortins, including melanotan II (MTII), increase presynaptic GABA release, and the orexigenic neuropeptide Y (NPY) inhibits it. After prolonged return to low-energy diet, GABA inputs to PVN neurons from DIO-D rats exhibited highly attenuated responses to MTII compared with those from DR and HED-naïve rats. In DIO-D rats, melanocortin-4 receptor expression was significantly reduced in dorsomedial hypothalamus, a major source of GABA input to PVN. Unlike melanocortin responses, NPY actions in PVN of DIO-D rats were unchanged, but were reduced in neurons of the ventromedial hypothalamic nucleus; in PVN of DR rats, NPY responses were paradoxically increased. MTII-sensitivity was restored in DIO-D rats by several weeks’ refeeding with HED. The loss of melanocortin sensitivity restricted to PVN of DIO-D animals, and its restoration upon prolonged refeeding with HED suggest that their melanocortin systems retain the ability to up- and downregulate around their elevated body weight setpoint in response to longer-term changes in dietary energy density. These properties are consistent with a mechanism of body weight setpoint.
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Affiliation(s)
- Dirk W. Luchtman
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Melissa J. S. Chee
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Barbora Doslikova
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Daniel L. Marks
- Papé Family Pediatric Research Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd. Portland, Oregon, United States of America
| | - Vickie E. Baracos
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - William F. Colmers
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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18
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Abstract
Thermogenesis, the production of heat energy, in brown adipose tissue is a significant component of the homeostatic repertoire to maintain body temperature during the challenge of low environmental temperature in many species from mouse to man and plays a key role in elevating body temperature during the febrile response to infection. The sympathetic neural outflow determining brown adipose tissue (BAT) thermogenesis is regulated by neural networks in the CNS which increase BAT sympathetic nerve activity in response to cutaneous and deep body thermoreceptor signals. Many behavioral states, including wakefulness, immunologic responses, and stress, are characterized by elevations in core body temperature to which central command-driven BAT activation makes a significant contribution. Since energy consumption during BAT thermogenesis involves oxidation of lipid and glucose fuel molecules, the CNS network driving cold-defensive and behavioral state-related BAT activation is strongly influenced by signals reflecting the short- and long-term availability of the fuel molecules essential for BAT metabolism and, in turn, the regulation of BAT thermogenesis in response to metabolic signals can contribute to energy balance, regulation of body adipose stores and glucose utilization. This review summarizes our understanding of the functional organization and neurochemical influences within the CNS networks that modulate the level of BAT sympathetic nerve activity to produce the thermoregulatory and metabolic alterations in BAT thermogenesis and BAT energy expenditure that contribute to overall energy homeostasis and the autonomic support of behavior.
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Affiliation(s)
- Shaun F Morrison
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon
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19
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Monge-Roffarello B, Labbe SM, Roy MC, Lemay ML, Coneggo E, Samson P, Lanfray D, Richard D. The PVH as a site of CB1-mediated stimulation of thermogenesis by MC4R agonism in male rats. Endocrinology 2014; 155:3448-58. [PMID: 24949658 DOI: 10.1210/en.2013-2092] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The present study was designed to investigate the involvement of the cannabinoid receptor 1 (CB1) in the stimulating effects of the melanocortin-4 receptor (MC4R) agonism on whole-body and brown adipose tissue (BAT) thermogenesis. In a first series of experiments, whole-body and BAT thermogenesis were investigated in rats infused in the third ventricle of the brain with the MC4R agonist melanotan II (MTII) and the CB1 agonist δ9-tetrahydrocannabinol (δ(9)-THC) or the CB1 antagonist AM251. Whole-body thermogenesis was measured by indirect calorimetry and BAT thermogenesis assessed from interscapular BAT (iBAT) temperature. δ(9)-THC blunted the effects of MTII on energy expenditure and iBAT temperature, whereas AM251 tended to potentiate the MTII effects. δ(9)-THC also blocked the stimulating effect of MTII on (14)C-bromopalmitate and (3)H-deoxyglucose uptakes in iBAT. Additionally, δ(9)-THC attenuated the stimulating effect of MTII on the expression of peroxisome proliferator-activated receptor-γ coactivator 1-α (Pgc1α), type II iodothyronine deiodinase (Dio2), carnitine palmitoyltransferase 1B (Cpt1b), and uncoupling protein 1 (Ucp1). In a second series of experiments, we addressed the involvement of the paraventricular hypothalamic nucleus (PVH) in the CB1-mediated effects of MTII on iBAT thermogenesis, which were assessed following the infusion of MTII in the PVH and δ(9)-THC or AM251 in the fourth ventricle of the brain. We demonstrated the ability of δ(9)-THC to blunt MTII-induced iBAT temperature elevation. δ(9)-THC also blocked the PVH effect of MTII on (14)C-bromopalmitate uptake as well as on Pgc1α and Dio2 expression in iBAT. Altogether the results of this study demonstrate the involvement of the PVH in the CB1-mediated stimulating effects of the MC4R agonist MTII on whole-body and BAT thermogenesis.
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MESH Headings
- Adipose Tissue, Brown/metabolism
- Animals
- Male
- Paraventricular Hypothalamic Nucleus/metabolism
- Peptides, Cyclic/metabolism
- Piperidines
- Pyrazoles
- Rats
- Rats, Wistar
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Melanocortin, Type 4/agonists
- Receptor, Melanocortin, Type 4/metabolism
- Thermogenesis
- alpha-MSH/analogs & derivatives
- alpha-MSH/metabolism
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Affiliation(s)
- Boris Monge-Roffarello
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada G1V 4G5
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20
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Monge-Roffarello B, Labbe SM, Lenglos C, Caron A, Lanfray D, Samson P, Richard D. The medial preoptic nucleus as a site of the thermogenic and metabolic actions of melanotan II in male rats. Am J Physiol Regul Integr Comp Physiol 2014; 307:R158-66. [DOI: 10.1152/ajpregu.00059.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The present study was designed to investigate the role of the medial preoptic nucleus (MPO) as a site of the thermogenic and metabolic effects of the α-melanocyte-stimulating hormone analog melanotan II (MTII). We also assessed the involvement of the dorsomedial hypothalamic nucleus (DMH) by investigating the effects of the MPO infusion of MTII in rats with DMH lesions produced by kainic acid. Infusion of MTII in the MPO led to increases in interscapular brown adipose tissue (iBAT) temperature and iBAT uptake of 14C-bromopalmitate. Both increases were blocked by DMH lesions. iBAT temperature increase (area under curve) and 14C-bromopalmitate uptake emerged as two correlated variables ( r = 0.63, P < 0.001). DMH lesions also blocked MTII-induced expression of mRNAs coding for proteins involved in 1) thermogenesis [type II iodothyronine deiodinase ( Dio2) and peroxisome proliferator-activated receptor gamma coactivator 1-α ( Pgc1α)], 2) lipolysis [hormone-sensitive lipase ( Hsl)], and 3) lipogenesis [diacylglycerol-O-acyltransferase 2 ( Dgat2), fatty acid synthase ( Fas)], in iBAT of rats killed 1 h after MPO infusion of MTII. MTII also stimulated expression of genes in iWAT but only in rats with DMH lesions. These genes included glucose transporter member 4 ( Glut4), glycerol-3-phosphate acyltransferase 3 ( Gpat3), Dgat1, Dgat2, triglyceride lipase ( Atgl), Hsl, and carnitine palmitoyltransferase 1β ( Cpt1β). Altogether, the present results reveal the MPO as a site of the thermogenic and metabolic actions of MTII. They also contribute to establish the MPO-DMH duet as a significant target for melanocortins to modulate energy homeostasis.
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Affiliation(s)
- Boris Monge-Roffarello
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Sebastien M. Labbe
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Christophe Lenglos
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Alexandre Caron
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Damien Lanfray
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Pierre Samson
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
| | - Denis Richard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada
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Abstract
During critical periods of development early in life, excessive or scarce nutritional environments can disrupt the development of central feeding and metabolic neural circuitry, leading to obesity and metabolic disorders in adulthood. A better understanding of the genetic networks that control the development of feeding and metabolic neural circuits, along with knowledge of how and where dietary signals disrupt this process, can serve as the basis for future therapies aimed at reversing the public health crisis that is now building as a result of the global obesity epidemic. This review of animal and human studies highlights recent insights into the molecular mechanisms that regulate the development of central feeding circuitries, the mechanisms by which gestational and early postnatal nutritional status affects this process, and approaches aimed at counteracting the deleterious effects of early over- and underfeeding.
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Affiliation(s)
- Daniel A Lee
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
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22
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Lee SJ, Kirigiti M, Lindsley SR, Loche A, Madden CJ, Morrison SF, Smith MS, Grove KL. Efferent projections of neuropeptide Y-expressing neurons of the dorsomedial hypothalamus in chronic hyperphagic models. J Comp Neurol 2013; 521:1891-914. [PMID: 23172177 DOI: 10.1002/cne.23265] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 08/15/2012] [Accepted: 11/06/2012] [Indexed: 12/31/2022]
Abstract
The dorsomedial hypothalamus (DMH) has long been implicated in feeding behavior and thermogenesis. The DMH contains orexigenic neuropeptide Y (NPY) neurons, but the role of these neurons in the control of energy homeostasis is not well understood. NPY expression in the DMH is low under normal conditions in adult rodents but is significantly increased during chronic hyperphagic conditions such as lactation and diet-induced obesity (DIO). To understand better the role of DMH-NPY neurons, we characterized the efferent projections of DMH-NPY neurons using the anterograde tracer biotinylated dextran amine (BDA) in lactating rats and DIO mice. In both models, BDA- and NPY-colabeled fibers were limited mainly to the hypothalamus, including the paraventricular nucleus of the hypothalamus (PVH), lateral hypothalamus/perifornical area (LH/PFA), and anteroventral periventricular nucleus (AVPV). Specifically in lactating rats, BDA-and NPY-colabeled axonal swellings were in close apposition to cocaine- and amphetamine-regulated transcript (CART)-expressing neurons in the PVH and AVPV. Although the DMH neurons project to the rostral raphe pallidus (rRPa), these projections did not contain NPY immunoreactivity in either the lactating rat or the DIO mouse. Instead, the majority of BDA-labeled fibers in the rRPa were orexin positive. Furthermore, DMH-NPY projections were not observed within the nucleus of the solitary tract (NTS), another brainstem site critical for the regulation of sympathetic outflow. The present data suggest that NPY expression in the DMH during chronic hyperphagic conditions plays important roles in feeding behavior and thermogenesis by modulating neuronal functions within the hypothalamus, but not in the brainstem.
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Affiliation(s)
- Shin J Lee
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon 97006, USA
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23
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Asarian L, Geary N. Sex differences in the physiology of eating. Am J Physiol Regul Integr Comp Physiol 2013; 305:R1215-67. [PMID: 23904103 DOI: 10.1152/ajpregu.00446.2012] [Citation(s) in RCA: 350] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hypothalamic-pituitary-gonadal (HPG) axis function fundamentally affects the physiology of eating. We review sex differences in the physiological and pathophysiological controls of amounts eaten in rats, mice, monkeys, and humans. These controls result from interactions among genetic effects, organizational effects of reproductive hormones (i.e., permanent early developmental effects), and activational effects of these hormones (i.e., effects dependent on hormone levels). Male-female sex differences in the physiology of eating involve both organizational and activational effects of androgens and estrogens. An activational effect of estrogens decreases eating 1) during the periovulatory period of the ovarian cycle in rats, mice, monkeys, and women and 2) tonically between puberty and reproductive senescence or ovariectomy in rats and monkeys, sometimes in mice, and possibly in women. Estrogens acting on estrogen receptor-α (ERα) in the caudal medial nucleus of the solitary tract appear to mediate these effects in rats. Androgens, prolactin, and other reproductive hormones also affect eating in rats. Sex differences in eating are mediated by alterations in orosensory capacity and hedonics, gastric mechanoreception, ghrelin, CCK, glucagon-like peptide-1 (GLP-1), glucagon, insulin, amylin, apolipoprotein A-IV, fatty-acid oxidation, and leptin. The control of eating by central neurochemical signaling via serotonin, MSH, neuropeptide Y, Agouti-related peptide (AgRP), melanin-concentrating hormone, and dopamine is modulated by HPG function. Finally, sex differences in the physiology of eating may contribute to human obesity, anorexia nervosa, and binge eating. The variety and physiological importance of what has been learned so far warrant intensifying basic, translational, and clinical research on sex differences in eating.
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Affiliation(s)
- Lori Asarian
- Institute of Veterinary Physiology and Center for Integrated Human Physiology, University of Zurich, Zurich, Switzerland; and
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24
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Boonanuntanasarn S, Jangprai A, Yoshizaki G. Characterization of neuropeptide Y in snakeskin gourami and the change in its expression due to feeding status and melanocortin 4 receptor expression. Gen Comp Endocrinol 2012; 179:184-95. [PMID: 22898434 DOI: 10.1016/j.ygcen.2012.07.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/22/2012] [Accepted: 07/26/2012] [Indexed: 11/17/2022]
Abstract
In this study, we characterized the neuropeptide Y (NPY) mRNA in snakeskin gourami (Trichogaster pectoralis) (TpNPY). TpNPY displayed characteristics typical of previously reported NPYs, and it exhibited a high degree of homology with the NPY proteins of other vertebrates. A phylogenetic analysis demonstrated that TpNPY was closely related to the NPYs found in the acanthomorpha and salmoniformes fish species. TpNPY was found to be ubiquitously expressed in all brain regions when assessed by real-time RT-PCR and in situ hybridization. In addition, a graded expression level of TpNPY was observed in peripheral tissues; for example, a moderate level of TpNPY was found in the gills, liver, kidney, stomach, intestine, spleen and gonads, while a low level of TpNPY was found in the muscle. The change in expression of TpNPY with respect to daily feeding habits was investigated in distinct brain regions, including the telencephalon, mesencephalon, metencephalon, and diencephalon. Fluctuations in the expression level of TpNPY were observed for a 24h post-prandial period. Except for the telencephalon, a reduction in TpNPY expression was found after a meal, while a peak level of TpNPY was observed 1h before the scheduled breakfast. Furthermore, there was a positive correlation between TpNPY and TpMC4R in the telencephalon and diencephalon throughout the circadian feeding cycle, which suggests that there is a connection between the function of NPY and the melanocortin system for the regulation of daily feeding. Fish brains were incubated with an MC4R antagonist (i.e., HS024), and the expression of TpNPY and TpMC4R was measured. Interestingly, there was a significant relationship between the expression of TpNPY and TpMC4R under the effects of HS024, which demonstrates that there are interactions between MC4R and NPY, particularly in a hyperphagic state.
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Affiliation(s)
- Surintorn Boonanuntanasarn
- School of Animal Production Technology, Institute of Agricultural Technology, Suranaree University of Technology, 111 University Avenue, Muang, Nakhon Ratchasima 30000, Thailand.
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Speakman JR, Król E. Limits to sustained energy intake. XIII. Recent progress and future perspectives. J Exp Biol 2011; 214:230-41. [DOI: 10.1242/jeb.048603] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Summary
Several theories have been proposed to explain limits on the maximum rate at which animals can ingest and expend energy. These limits are likely to be intrinsic to the animal, and potentially include the capacity of the alimentary tract to assimilate energy – the ‘central limitation’ hypothesis. Experimental evidence from lactating mice exposed to different ambient temperatures allows us to reject this and similar ideas. Two alternative ideas have been proposed. The ‘peripheral limitation’ hypothesis suggests that the maximal sustained energy intake reflects the summed demands of individual tissues, which have their own intrinsic limitations on capacity. In contrast, the ‘heat dissipation limit’ (HDL) theory suggests that animals are constrained by the maximal capacity to dissipate body heat. Abundant evidence in domesticated livestock supports the HDL theory, but data from smaller mammals are less conclusive. Here, we develop a novel framework showing how the HDL and peripheral limitations are likely to be important in all animals, but to different extents. The HDL theory makes a number of predictions – in particular that there is no fixed limit on sustained energy expenditure as a multiple of basal metabolic rate, but rather that the maximum sustained scope is positively correlated with the capacity to dissipate heat.
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Affiliation(s)
- John R. Speakman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK
| | - Elżbieta Król
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK
- Mammal Research Institute PAS, 17-230 Białowieża, Poland
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Cui JG, Tang GB, Wang DH, Speakman JR. Effects of leptin infusion during peak lactation on food intake, body composition, litter growth, and maternal neuroendocrine status in female Brandt's voles (Lasiopodomys brandtii). Am J Physiol Regul Integr Comp Physiol 2010; 300:R447-59. [PMID: 21123757 DOI: 10.1152/ajpregu.00121.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
During lactation, female small mammals frequently reduce their fat reserves to very low levels. The function of this reduction is unclear, as calculations suggest that the contribution of the withdrawn energy from fat to the total energy balance of lactation is trivial. An alternative hypothesis is that reducing fat leads to a reduction in circulating adipokines, such as leptin, that play a role in stimulating the hyperphagia of lactation. We investigated the role of circulating leptin in lactation by repleting leptin levels using miniosmotic pumps during the last 7 days of lactation in Brandt's voles (Lasiopodomys brandtii), a model small wild mammal we have extensively studied in the context of lactation energy demands. Repletion of leptin resulted in a dose-dependent reduction of body mass and food intake in lactating voles. Comparisons to nonreproducing individuals suggests that the reduced leptin in lactation, due to reduced fat stores, may account for ∼16% of the lactational hyperphagia. Reduced leptin in lactation may, in part, cause lactational hyperphagia via stimulatory effects on hypothalamic orexigenic neuropeptides (neuropeptide Y and agouti-related peptide) and inhibition of the anorexigenic neuropeptide (proopiomelanocortin). These effects were reversed by the experimental repletion of leptin. There was no significant effect of leptin treatment on daily energy expenditure, milk production or pup growth, but leptin repletion did result in a reversal of the suppression of uncoupling protein-1 levels in brown adipose tissue, indicating an additional role for reducing body fat and leptin during peak lacation.
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Affiliation(s)
- Jian-Guo Cui
- Institute of Zoology, Chinese Academy of Sciences, Benchen Xilu, Chaoyang, Beijing 100101, China
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The neuroendocrine basis of lactation-induced suppression of GnRH: role of kisspeptin and leptin. Brain Res 2010; 1364:139-52. [PMID: 20727862 DOI: 10.1016/j.brainres.2010.08.038] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 08/11/2010] [Accepted: 08/12/2010] [Indexed: 11/22/2022]
Abstract
Lactation is an important physiological model of the integration of energy balance and reproduction, as it involves activation of potent appetitive neuropeptide systems coupled to a profound inhibition of pulsatile GnRH/LH secretion. There are multiple systems that contribute to the chronic hyperphagia of lactation: 1) suppression of the metabolic hormones, leptin and insulin, 2) activation of hypothalamic orexigenic neuropeptide systems NPY, AGRP, orexin (OX) and melanin concentrating hormone (MCH), 3) special induction of NPY expression in the dorsomedial hypothalamus, and 4) suppression of anorexigenic systems POMC and CART. These changes ensure adequate energy intake to meet the metabolic needs of milk production. There is significant overlap in all of the systems that regulate food intake with the regulation of GnRH, suggesting there could be several redundant factors acting to suppress GnRH/LH during lactation. In addition to an overall increase in inhibitory tone acting directly on GnRH cell bodies that is brought about by increases in orexigenic systems, there are also effects at the ARH to disrupt Kiss1/neurokinin B/dynorphin neuronal function through inhibition of Kiss1 and NKB. These changes could lead to an increase in inhibitory auto-regulation of the Kiss1 neurons and a possible disruption of pulsatile GnRH release. While the low levels of leptin and insulin contribute to the changes in ARH appetitive systems, they do not appear to contribute to the suppression of ARH Kiss1 or NKB. The inhibition of Kiss1 may be the key factor in the suppression of GnRH during lactation, although the mechanisms responsible for its inhibition are unknown.
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Gallagher SK, Witkovsky P, Roux MJ, Low MJ, Otero-Corchon V, Hentges ST, Vigh J. beta-Endorphin expression in the mouse retina. J Comp Neurol 2010; 518:3130-48. [PMID: 20533364 PMCID: PMC3095846 DOI: 10.1002/cne.22387] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Evidence showing expression of endogenous opioids in the mammalian retina is sparse. In the present study we examined a transgenic mouse line expressing an obligate dimerized form of Discosoma red fluorescent protein (DsRed) under the control of the pro-opiomelanocortin promoter and distal upstream regulatory elements to assess whether pro-opiomelanocortin peptide (POMC), and its opioid cleavage product, beta-endorphin, are expressed in the mouse retina. Using double label immunohistochemistry we found that DsRed fluorescence was restricted to a subset of GAD-67-positive cholinergic amacrine cells of both orthotopic and displaced subtypes. About 50% of cholinergic amacrine cells colocalized DsRed and a large fraction of DsRed-expressing amacrine cells was positive for beta-endorphin immunostaining, whereas beta-endorphin-immunoreactive neurons were absent in retinas of POMC null mice. Our findings contribute to a growing body of evidence demonstrating that opioid peptides are an integral component of vertebrate retinas, including those of mammals.
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Affiliation(s)
- Shannon K. Gallagher
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Paul Witkovsky
- Department of Ophthalmology, New York University School of Medicine, New York, NY 10016, USA
| | - Michel J. Roux
- Department of Neurobiology and Genetics, IGBMC, CNRS UMR 7104, Inserm U 964, Université de Strasbourg, F-67404 Illkirch, France
| | - Malcolm J. Low
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Veronica Otero-Corchon
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Shane T. Hentges
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Jozsef Vigh
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
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Draper S, Kirigiti M, Glavas M, Grayson B, Chong CNA, Jiang B, Smith MS, Zeltser LM, Grove KL. Differential gene expression between neuropeptide Y expressing neurons of the dorsomedial nucleus of the hypothalamus and the arcuate nucleus: microarray analysis study. Brain Res 2010; 1350:139-50. [PMID: 20380814 DOI: 10.1016/j.brainres.2010.03.082] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/21/2010] [Accepted: 03/24/2010] [Indexed: 12/29/2022]
Abstract
The Dorsomedial Nucleus of the Hypothalamus (DMH) is known to play important roles in ingestive behavior and body weight homeostasis. The DMH contains neurons expressing Neuropeptide Y (NPY) during specific physiological conditions of hyperphagia and obesity, however, the role of DMH-NPY neurons has yet to be characterized. In contrast to the DMH-NPY neurons, NPY expressing neurons have been best characterized in the Arcuate Nucleus of the Hypothalamus (ARH). The purpose of this study is to characterize the chemical phenotype of DMH-NPY neurons by comparing the gene expression profiles of NPY neurons in the DMH and ARH isolated from postnatal NPY-hrGFP mice by microarray analysis. Twenty genes were differentially expressed in the DMH-NPY neurons compared to the ARH. Among them, there were several transcriptional factors that play important roles in the regulation of energy balance. DMH-NPY neurons expressed Glutamic Acid Decarboxylase (GAD) 65 and 67, suggesting that they may be GABAergic, similar to ARH-NPY neurons. While ARH-NPY neurons expressed leptin receptor (ObRb) and displayed the activation of STAT3 in response to leptin administration, DMH-NPY neurons showed neither. These findings strongly suggest that DMH-NPY neurons could play a distinct role in the control of energy homeostasis and are differentially regulated from ARH-NPY neurons through afferent inputs and transcriptional regulators.
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Affiliation(s)
- Shin Draper
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006-3499, USA
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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]
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Xu J, Kirigiti MA, Grove KL, Smith MS. Regulation of food intake and gonadotropin-releasing hormone/luteinizing hormone during lactation: role of insulin and leptin. Endocrinology 2009; 150:4231-40. [PMID: 19470705 PMCID: PMC2736090 DOI: 10.1210/en.2009-0190] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Negative energy balance during lactation is reflected by low levels of insulin and leptin and is associated with chronic hyperphagia and suppressed GnRH/LH activity. We studied whether restoration of insulin and/or leptin to physiological levels would reverse the lactation-associated hyperphagia, changes in hypothalamic neuropeptide expression [increased neuropeptide Y (NPY) and agouti-related protein (AGRP) and decreased proopiomelanocortin (POMC), kisspeptin (Kiss1), and neurokinin B (NKB)] and suppression of LH. Ovariectomized lactating rats (eight pups) were treated for 48 h with sc minipumps containing saline, human insulin, or rat leptin. The arcuate nucleus (ARH) was analyzed for NPY, AGRP, POMC, Kiss1, and NKB mRNA expression; the dorsal medial hypothalamus (DMH) was analyzed for NPY mRNA. Insulin replacement reversed the increase in ARH NPY/AGRP mRNAs, partially recovered POMC, but had no effect on recovering Kiss1/NKB. Leptin replacement only affected POMC, which was fully recovered. Insulin/leptin dual replacement had similar effects as insulin replacement alone but with a slight increase in Kiss1/NKB. The lactation-induced increase in DMH NPY was unchanged after treatments. Restoration of insulin and/or leptin had no effect on food intake, body weight, serum glucose or serum LH. These results suggest that the negative energy balance of lactation is not required for the hyperphagic drive, although it is involved in the orexigenic changes in the ARH. The chronic hyperphagia of lactation is most likely sustained by the induction of NPY in the DMH. The negative energy balance also does not appear to be a necessary prerequisite for the suppression of GnRH/LH activity.
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Affiliation(s)
- Jing Xu
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon 97006, USA
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32
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Role of dorsomedial hypothalamic neuropeptide Y in modulating food intake and energy balance. J Neurosci 2009; 29:179-90. [PMID: 19129396 DOI: 10.1523/jneurosci.4379-08.2009] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Previous studies have suggested that neuropeptide Y (NPY) in the dorsomedial hypothalamus (DMH) serves as an important signaling peptide in the regulation of energy balance. To elucidate such actions, we used the adenoassociated virus (AAV) system to alter Npy gene expression in the DMH and examined the effects of these alterations on food intake and energy balance as well as explored its downstream signaling pathway. We found that AAV-mediated overexpression of NPY in the DMH of lean rats increased food intake and body weight, and exacerbated high-fat diet-induced obesity. Knockdown of NPY expression in the DMH via AAV-mediated RNA interference ameliorated the hyperphagia, obesity, and diabetes of Otsuka Long-Evans Tokushima Fatty (OLETF) rats. NPY knockdown in the DMH produced a nocturnal and meal size-specific feeding effect. Moreover, we found that knockdown of DMH NPY expression in intact rats reduced NPY content in the nucleus of the solitary tract (NTS) and the dorsal motor nucleus of the vagus and affected within-meal satiation. DMH NPY knockdown increased the feeding inhibitory and NTS c-Fos responses to peripheral administration of cholecystokinin. Together, these results indicate that DMH NPY plays an important role in modulating food intake and energy balance and its dysregulation causes disordered energy balance leading to obesity.
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Xu J, Kirigiti MA, Cowley MA, Grove KL, Smith MS. Suppression of basal spontaneous gonadotropin-releasing hormone neuronal activity during lactation: role of inhibitory effects of neuropeptide Y. Endocrinology 2009; 150:333-40. [PMID: 18719019 PMCID: PMC2630892 DOI: 10.1210/en.2008-0962] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Increased neuropeptide Y (NPY) activity drives the chronic hyperphagia of lactation and may contribute to the suppression of GnRH activity. The majority of GnRH neurons are contacted by NPY fibers, and GnRH cells express NPY Y5 receptor (Y5R). Therefore, NPY provides a neurocircuitry for information about food intake/energy balance to be directly transmitted to GnRH neurons. To investigate the effects of lactation on GnRH neuronal activity, hypothalamic slices were prepared from green fluorescent protein-GnRH transgenic rats. Extracellular loose-patch recordings determined basal GnRH neuronal activity from slices of ovariectomized control and lactating rats. Compared with controls, hypothalamic slices from lactating rats had double the number of quiescent GnRH neurons (14.51 +/- 2.86 vs. 7.04 +/- 2.84%) and significantly lower firing rates of active GnRH neurons (0.25 +/- 0.02 vs. 0.37 +/- 0.03 Hz). To study the NPY-postsynaptic Y5R system, whole-cell current-clamp recordings were performed in hypothalamic slices from control rats to examine NPY/Y5R antagonist effects on GnRH neuronal resting membrane potential. Under tetrodotoxin treatment, NPY hyperpolarized GnRH neurons from -56.7 +/- 1.94 to -62.1 +/- 1.83 mV; NPY's effects were blocked by Y5R antagonist. To determine whether increased endogenous NPY tone contributes to GnRH neuronal suppression during lactation, hypothalamic slices were treated with Y5R antagonist. A significantly greater percentage of GnRH cells were activated in slices from lactating rats (52%) compared with controls (28%). These results suggest that: 1) basal GnRH neuronal activity is suppressed during lactation; 2) NPY can hyperpolarize GnRH neurons via postsynaptic Y5R; and 3) increased inhibitory NPY tone during lactation is a component of the mechanisms responsible for suppression of GnRH neuronal activity.
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Affiliation(s)
- Jing Xu
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, 505 Northwest 185th Avenue, Beaverton, Oregon 97006, USA
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Fyffe SL, Neul JL, Samaco RC, Chao HT, Ben-Shachar S, Moretti P, McGill BE, Goulding EH, Sullivan E, Tecott LH, Zoghbi HY. Deletion of Mecp2 in Sim1-expressing neurons reveals a critical role for MeCP2 in feeding behavior, aggression, and the response to stress. Neuron 2008; 59:947-58. [PMID: 18817733 PMCID: PMC2597031 DOI: 10.1016/j.neuron.2008.07.030] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 06/05/2008] [Accepted: 07/21/2008] [Indexed: 11/17/2022]
Abstract
Rett Syndrome (RTT) is an autism spectrum disorder caused by mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MeCP2). In order to map the neuroanatomic origins of the complex neuropsychiatric behaviors observed in patients with RTT and to uncover endogenous functions of MeCP2 in the hypothalamus, we removed Mecp2 from Sim1-expressing neurons in the hypothalamus using Cre-loxP technology. Loss of MeCP2 in Sim1-expressing neurons resulted in mice that recapitulated the abnormal physiological stress response that is seen upon MeCP2 dysfunction in the entire brain. Surprisingly, we also uncovered a role for MeCP2 in the regulation of social and feeding behaviors since the Mecp2 conditional knockout (CKO) mice were aggressive, hyperphagic, and obese. This study demonstrates that deleting Mecp2 in a defined brain region is an excellent approach to map the neuronal origins of complex behaviors and provides new insight about the function of MeCP2 in specific neurons.
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Affiliation(s)
- Sharyl L Fyffe
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Abstract
The prevalence of obesity is steadily rising and has huge health and financial implications for society. Weight gain is due to an imbalance between dietary intake and energy expenditure and research has focused on trying to understand the complex pathways involved in controlling these aspects. This review highlights the key areas of research in the hypothalamic control of appetite. The hypothalamus consists of several nuclei that integrate peripheral signals, such as adiposity and caloric intake, to regulate important pathways within the CNS controlling food intake. The best characterized pathways are the orexigenic neuropeptide Y/Agouti-related protein and the anorexigenic pro-opiomelanocortin/cocaine- and amphetamine-related transcript neurons in the arcuate nucleus of the hypothalamus. These project from the arcuate nucleus to other key hypothalamic nuclei, such as the paraventricular, dorsomedial, ventromedial and lateral hypothalamic nuclei. There are also projections to and from the brainstem, cortical areas and reward pathways, all of which influence food intake. The challenge at present is to understand the complexity of these pathways and try to find ways of modulating them in order to find potential therapeutic targets.
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Affiliation(s)
- Katherine A Simpson
- a Department of Investigative Medicine, Imperial College, London W12 ONN, UK
| | - Niamh M Martin
- a Department of Investigative Medicine, Imperial College, London W12 ONN, UK
| | - Steve R Bloom
- b Department of Investigative Medicine, Imperial College, London W12 ONN, UK.
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Abstract
Feeding behavior is tightly regulated by peptidergic transmission within the hypothalamus. Neuropeptide Y (NPY) is one of the most potent known stimulators of food intake and has robust effects on the hypothalamic feeding neuronal networks. A vast body of literature has documented the substantial effects of NPY on feeding behavior. However, the cellular mechanisms underlying the actions of NPY have only recently begun to be explored. The NPYergic signal, including its expression in hypothalamic neurons, its release into the synaptic space, and its direct or indirect receptor-mediated actions, is highly responsive to decreases in the metabolic state. The orexigenic NPY signal can suppress the anorexigenic drive to restore energy balance homeostasis when energy levels are low, such as after food deprivation. The NPY signal interacts with glucose- and fat-sensitive signals arriving in the hypothalamus and effects changes in anorexigenic pathways, such as those mediated by the melanocortins. Recent applications of electrophysiological methods to examine the neuronal activity and pathways engaged by NPY-mediated signaling have advanced our understanding of this orexigenic system. Furthermore, crucial roles for NPY pathways in the development of hypothalamic feeding circuitry have been identified by these means. Orexigenic NPY signaling is critical during development and its absence is lethal in adults, thus reflecting the essential role of NPY for the regulation of energy homeostasis.
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Affiliation(s)
- Melissa J S Chee
- Centre for Neuroscience and Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada
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Zagoory-Sharon O, Schroeder M, Levine A, Moran TH, Weller A. Adaptation to lactation in OLETF rats lacking CCK-1 receptors: body weight, fat tissues, leptin and oxytocin. Int J Obes (Lond) 2008; 32:1211-21. [PMID: 18461073 DOI: 10.1038/ijo.2008.58] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To understand the adaptation to lactation of obese rats, by studying the interplay among the gut hormone cholecystokinin (CCK), the adiposity hormone leptin and the affiliation hormone oxytocin in modulating body mass and fat storage. DESIGN Strain differences were examined between Otsuka Long Evans Tokushima Fatty (OLETF) rats lacking expression of functional CCK-1 receptors and Long Evans Tokushima Otsuka (LETO) controls, tested as nulliparous dams, at the 7 and 15th lactation day, at weaning (lactation day 22) or 8 weeks postweaning. MEASUREMENTS We measured body mass, fat pads (brown, retroperitoneal and inguinal) and inguinal adipocytes. Plasma levels of leptin and oxytocin were determined. RESULTS Fat depots of LETO female rats were larger during lactation compared to the levels found in postweaning and nulliparous female rats. LETO female rats gained weight and accumulated fat during pregnancy and lactation, returning to their normal fat levels postweaning. In contrast, OLETF female rats presented lower body weight and fat depots during the lactation period than nulliparous dams, and regained the weight and fat postweaning. Plasma leptin and oxytocin were highly correlated and followed the same pattern. OLETF leptin levels were highly correlated with fat depot and inguinal cell surface. No significant correlation was found for LETO parameters. CONCLUSIONS Pregnancy and lactation are energy-consuming events, which naturally induce female rats to increase food intake and accumulate fat. When challenged by the demands of rapidly growing preobese OLETF pups, OLETF dams' fat stores are reduced to lean, LETO levels. During lactation, sensitivity of the oxytocinergic neurons descending from the paraventricular nuclei to the nucleus of the solitary tract to CCK is reduced. We theorized that this pathway is not available to OLETF female rats that lack functional CCK-1 receptors to mediate the signal. The current study contributes to the understanding of the female body's adaptation to lactation.
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Affiliation(s)
- O Zagoory-Sharon
- Department of Psychology, The Leslie and Susan Gonda Goldschmied Multidisciplinary Brain Research Center, Bar Ilan University, Ramat Gan, Israel.
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Abstract
Hypothalamic neurons that express agouti-related protein (AgRP) and neuropeptide Y (NPY) are thought to be important for regulation of feeding, especially under conditions of negative energy balance. The expression of NPY and AgRP increases during lactation and may promote the hyperphagia that ensues. We explored the role of AgRP neurons in reproduction and lactation, using a mouse model in which AgRP-expressing neurons were selectively ablated by the action of diphtheria toxin. We show that ablation of AgRP neurons in neonatal mice does not interfere with pregnancy, parturition, or lactation, suggesting that early ablation allows compensatory mechanisms to become established. However, ablation of AgRP neurons after lactation commences results in rapid starvation, indicating that both basal feeding and lactation-induced hyperphagia become dependent on AgRP neurons in adulthood. We also show that constitutive inactivation of Npy and Agrp genes does not prevent pregnancy or lactation, nor does it protect lactating dams from diphtheria toxin-induced starvation.
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Affiliation(s)
- Colin T Phillips
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
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39
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Geary N. Curt Richter and the female rat. Appetite 2007; 49:376-87. [PMID: 17544544 DOI: 10.1016/j.appet.2007.01.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 01/06/2007] [Accepted: 01/20/2007] [Indexed: 02/04/2023]
Abstract
Richter fully appreciated the fundamental biological importance of sex differences, in particular the challenges of female reproductive function to the two classes of behavior that most engaged him, endogenous rhythms and "self-regulatory" behaviors. Indeed, his contributions in these areas justify honoring him as one of the founders of behavioral neuroendocrinology. During the 1920s Richter, together with Wang, Kinder and other students, performed elegant phenomenological and mechanistic studies of sex differences in rats' spontaneous locomotor activity, nest building, and food intake. All of these behaviors display rhythms entrained to the ovarian cycle in female rats, and Richter's analyses of them formed the bases of many current areas of behavioral neuroscience. Slightly later, Richter made fundamentally important discoveries related to nutrient self-selection in pregnant and lactating rats, including changes in micronutrient and macronutrient selection. These data played a major role in the development of his concept of behavioral regulation of homeostasis. Unfortunately, some of these discoveries are rarely recalled. This is both historically regrettable and potentially an impediment to contemporary research progress.
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Affiliation(s)
- Nori Geary
- Institute of Animal Physiology, ETH Zürich, CH-8603, Schwerzenbach, Switzerland.
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Abstract
The nutritional needs of developing young place a large energetic demand on lactating females. In this paper some of the mechanisms through which lactating rats meet these demands are described. Emphasis is placed on the mechanisms that drive increased food intake in suckled rats that are independent of milk delivery and negative energy balance. Evidence is presented to suggest that prolactin (PRL), released from the pituitary in response to suckling stimulation, acts centrally to stimulate food intake during lactation. Brain areas in which PRL may act to stimulate food intake as well as its interactions with other hormones and neuropeptides involved in energy balance are discussed.
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Affiliation(s)
- Barbara Woodside
- Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Quebec, Canada.
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41
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Glavas MM, Joachim SE, Draper SJ, Smith MS, Grove KL. Melanocortinergic activation by melanotan II inhibits feeding and increases uncoupling protein 1 messenger ribonucleic acid in the developing rat. Endocrinology 2007; 148:3279-87. [PMID: 17412803 DOI: 10.1210/en.2007-0184] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The hypothalamic neurocircuitry that regulates energy homeostasis in adult rats is not fully developed until the third postnatal week. In particular, fibers from the hypothalamic arcuate nucleus, including both neuropeptide Y (NPY) and alpha-MSH fibers, do not begin to innervate downstream hypothalamic targets until the second postnatal week. However, alpha-MSH fibers from the brainstem and melanocortin receptors are present in the hypothalamus at birth. The present study investigated the melanocortin system in the early postnatal period by examining effects of the melanocortin receptor agonist melanotan II (MTII) on body weight, energy expenditure, and hypothalamic NPY expression. Rat pups were injected ip with MTII (3 mg/kg body weight) or saline on postnatal day (P) 5 to P6, P10-P11, or P15-P16 at 1700 and 0900 h and then killed at 1300 h. Stomach weight and brown adipose tissue uncoupling protein 1 mRNA were determined. In addition, we assessed central c-Fos activation 90 min after MTII administration and hypothalamic NPY mRNA after twice daily MTII administration from P5-P10 or P10-P15. MTII induced hypothalamic c-Fos activation as well as attenuating body weight gain in rat pups. Stomach weight was significantly decreased and uncoupling protein 1 mRNA was increased at all ages, indicating decreased food intake and increased energy expenditure, respectively. However, MTII had no effect on NPY mRNA levels in any hypothalamic region. These findings demonstrate that MTII can inhibit food intake and stimulate energy expenditure before the full development of hypothalamic feeding neurocircuitry. These effects do not appear to be mediated by changes in NPY expression.
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Affiliation(s)
- Maria M Glavas
- Oregon National Primate Research Center, Department of Physiology and Pharmacology, Oregon Health and Science University, 505 NW 185th Avenue, Beaverton, Oregon 97006, USA
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42
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Singh M, Kesterson RA, Jacobs MM, Joers JM, Gore JC, Emeson RB. Hyperphagia-mediated obesity in transgenic mice misexpressing the RNA-editing enzyme ADAR2. J Biol Chem 2007; 282:22448-59. [PMID: 17567573 DOI: 10.1074/jbc.m700265200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
ADAR2 is a double-stranded RNA-specific adenosine deaminase involved in the editing of mammalian RNAs by the site-specific conversion of adenosine to inosine. To examine the physiologic consequences resulting from ADAR2 misexpression, we have generated mutant mice expressing either wild-type or deaminase-deficient ADAR2 transgenes under the control of the human cytomegalovirus promoter. Transgenic mice expressing either wild-type or inactive ADAR2 isoforms demonstrated adult onset obesity characterized by hyperglycemia, hyperleptinemia, and increased adiposity. Paired feeding analysis revealed that mutant mice on caloric restriction had a growth rate and body composition indistinguishable from wild-type littermates, indicating that the observed obesity predominantly results from hyperphagia rather than a metabolic derangement. The observation that expression of catalytically inactive ADAR2 also is capable of producing an obese phenotype in mutant animals suggests that ADAR2 may possess additional biological activities beyond those required for the site-selective deamination of adenosine or may interfere with the actions of other double-stranded RNA-specific binding proteins in the cell.
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Affiliation(s)
- Minati Singh
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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43
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Singru PS, Fekete C, Lechan RM. Neuroanatomical evidence for participation of the hypothalamic dorsomedial nucleus (DMN) in regulation of the hypothalamic paraventricular nucleus (PVN) by alpha-melanocyte stimulating hormone. Brain Res 2005; 1064:42-51. [PMID: 16336950 DOI: 10.1016/j.brainres.2005.09.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Revised: 09/19/2005] [Accepted: 09/25/2005] [Indexed: 11/27/2022]
Abstract
To test the hypothesis that neurons in the hypothalamic paraventricular nucleus (PVN) may be under both direct and indirect regulation by alpha melanocyte-stimulating hormone (alpha-MSH)-synthesizing neurons of the arcuate nucleus, we determined whether the retrogradely transported marker substance, cholera toxin beta-subunit (CtB), when injected into the PVN, labels distinct populations of neurons in the hypothalamic dorsomedial nucleus (DMN) that are innervated by axon terminals containing alpha-MSH. Following iontophoresis of CtB into the PVN, retrogradely labeled neurons were identified in the DMN primarily on the same side as the injection, although a few neurons were also identified in the opposite side of the DMN. The greatest percentage of retrogradely labeled DMN neurons were located in the medial portion of the ventral subdivision of the DMN (DMNv), accounting for approximately 64.8 +/- 1.1% of all CtB-labeled cells in the DMN. The second largest population, comprising 25.9 +/- 1.6% of the total number of CtB cells in the DMN, was diffusely distributed in the dorsal subdivision of the DMN (DMNd). Only 9.4 +/- 0.3% of the CtB-labeled cells were located in the compact zone of the DMN (DMNc). In double-labeling immunofluorescent preparations, 61.1 +/- 1.0% of the CtB cells in the DMNv, 38.6 +/- 0.9% of the CtB cells in the DMNd, and 13.1 +/- 1.3% of the CtB cells in the DMNc were contacted by axon terminals containing alpha-MSH. These data establish that neurons in discrete regions in the DMN may be influenced by the melanocortin signaling system and thereby, could serve as important relay sites to the PVN.
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Affiliation(s)
- Praful S Singru
- Tupper Research Institute and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, Tufts-New England Medical Center, Boston, MA 02111, USA
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44
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Kim HJ, Lee JH, Choi SH, Lee YS, Jahng JW. Fasting-induced increases of arcuate NPY mRNA and plasma corticosterone are blunted in the rat experienced neonatal maternal separation. Neuropeptides 2005; 39:587-94. [PMID: 16266747 DOI: 10.1016/j.npep.2005.09.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Accepted: 09/09/2005] [Indexed: 11/17/2022]
Abstract
This study was conducted to examine the effects of neonatal maternal separation on the hypothalamic expression of feeding peptides in later life. Pups in maternal separation (MS) groups were separated from their dam for 3 h daily from postnatal day (PND) 1-14, while pups in non-handled (NH) groups were left undisturbed. Rats were sacrificed on PND 60 to examine the gene expression of neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) in the hypothalamic arcuate nucleus by mRNA in situ hybridization. Half of the rats from each group were food-deprived for 48 h before sacrifice. POMC mRNA expression increased in the free fed MS group compared with the free fed NH group. Food deprivation significantly decreased the arcuate POMC mRNA level in both groups. Body weight gain, basal levels of plasma corticosterone, leptin, and arcuate NPY mRNA were not modulated by experience of neonatal maternal separation. However, fasting-induced increases of plasma corticosterone and arcuate NPY expression were blunted in MS rats. These results suggest that neonatal maternal separation may increase the basal expression level of arcuate POMC mRNA, while inhibit the fasting-induced expression of arcuate NPY mRNA, later in life. Lastly, the altered expression of arcuate NPY mRNA, but not of arcuate POMC mRNA, appeared to be related with altered activity of the hypothalamic-pituitary-adrenal gland axis in offspring by neonatal maternal separation.
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Affiliation(s)
- H J Kim
- Department of Pharmacology, BK21 Project for Medical Science, Yonsei University College of Medicine, Shin Chon Dong, Seo Dae Moon Ku, Seoul, Republic of Korea
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45
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Abstract
Our knowledge of the physiological systems controlling energy homeostasis has increased dramatically over the last decade. The roles of peripheral signals from adipose tissue, pancreas, and the gastrointestinal tract reflecting short- and long-term nutritional status are now being described. Such signals influence central circuits in the hypothalamus, brain stem, and limbic system to modulate neuropeptide release and hence food intake and energy expenditure. This review discusses the peripheral hormones and central neuronal pathways that contribute to control of appetite.
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Affiliation(s)
- Sarah Stanley
- Endocrine Unit, Imperial College Faculty of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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46
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Fan W, Voss-Andreae A, Cao WH, Morrison SF. Regulation of thermogenesis by the central melanocortin system. Peptides 2005; 26:1800-13. [PMID: 15979759 DOI: 10.1016/j.peptides.2004.11.033] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Accepted: 11/05/2004] [Indexed: 12/21/2022]
Abstract
Adaptive thermogenesis represents one of the important homeostatic mechanisms by which the body maintains appropriate levels of stored energy and its core temperature. Dysregulation of adaptive thermogenesis promotes obesity. The central melanocortin system, in particular the melanocortin 4 receptor (MC4R) signaling pathway, influences the regulation of every aspect of energy balance, including thermogenesis, and plays a critical role in energy homeostasis in both rodent and man. This review will outline our current understanding of adaptive thermogenesis, focusing on the role of the central melanocortin pathway in the regulation of thermogenesis.
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Affiliation(s)
- Wei Fan
- Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Mail Code L474, Portland, OR 97239-3098, USA.
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47
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Speakman JR, Król E. Limits to sustained energy intake IX: a review of hypotheses. J Comp Physiol B 2005; 175:375-94. [PMID: 16047178 DOI: 10.1007/s00360-005-0013-3] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Revised: 03/08/2005] [Accepted: 05/03/2005] [Indexed: 02/01/2023]
Abstract
Several lines of evidence indicate that animals in the wild may be limited in their maximal rates of energy intake by their intrinsic physiology rather than food availability. Understanding the limits to sustained energy intake is important because this defines an envelope within which animals must trade-off competing activities. In the first part of this review, we consider the initial ideas that propelled this area and experimental evidence connected with them. An early conceptual advance in this field was the idea that energy intake could be centrally limited by aspects of the digestive process, or peripherally limited at the sites of energy utilisation. A model system that has been widely employed to explore these ideas is lactation in small rodents. Initial studies in the late 1980s indicated that energy intake might be centrally limited, but work by Hammond and colleagues in the 1990s suggested that it was more likely that the limits were imposed by capacity of the mammary glands, and other works tended to support this view. This consensus, however, was undermined by studies that showed milk production was higher in mice at low temperatures, suggesting that the capacity of the mammary gland is not a limiting factor. In the second part of the review we consider some additional hypotheses that might explain these conflicting data. These include the heat dissipation limits hypothesis, the seasonal investment hypothesis and the saturated neural control hypothesis. Current evidence with respect to these hypotheses is also reviewed. The limited evidence presently available does not unambiguously support any one of them.
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Affiliation(s)
- John R Speakman
- Aberdeen Centre for Energy Regulation and Obesity, School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK.
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48
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Kas MJH, Tiesjema B, van Dijk G, Garner KM, Barsh GS, ter Brake O, Verhaagen J, Adan RAH. Induction of brain-region-specific forms of obesity by agouti. J Neurosci 2005; 24:10176-81. [PMID: 15537888 PMCID: PMC6730190 DOI: 10.1523/jneurosci.3442-04.2004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Disruption of melanocortin (MC) signaling, such as by ectopic Agouti overexpression, leads to an obesity syndrome with hyperphagia, obesity, and accelerated body weight gain during high-fat diet. To investigate where in the brain disruption of MC signaling results in obesity, long-term Agouti expression was induced after local injections of recombinant adeno-associated viral particles in selected brain nuclei of adult rats. Agouti expression in the paraventricular nucleus, a hypothalamic region with a high density of MC receptors, induced acute onset hyperphagia and rapid weight gain that persisted for at least 6 weeks. In contrast, obesity and hyperphagia developed with a 3 week delay when Agouti was expressed in the dorsal medial hypothalamus. Agouti expression in the lateral hypothalamus (LH) did not affect food intake and body weight during regular diet, despite the presence of MC receptors in this region. However, during exposure to a high-fat diet, animals with Agouti expression in the LH exhibited a marked increase in body weight. Here we show that the LH is important for the protection against diet-induced obesity by controlling caloric intake during consumption of a high-fat diet. Together, this study provides evidence that different aspects of the Agouti-induced obesity syndrome, such as hyperphagia and diet responsiveness, are mediated by distinct brain regions and opens challenging opportunities for further understanding of pathophysiological processes in the development of the obesity syndrome.
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Affiliation(s)
- Martien J H Kas
- Rudolf Magnus Institute of Neuroscience, Department of Pharmacology and Anatomy, University Medical Centre Utrecht, 3584 CG Utrecht, The Netherlands
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49
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Williamson-Hughes PS, Grove KL, Smith MS. Melanin concentrating hormone (MCH): A novel neural pathway for regulation of GnRH neurons. Brain Res 2005; 1041:117-24. [PMID: 15829220 DOI: 10.1016/j.brainres.2004.11.066] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Revised: 11/01/2004] [Accepted: 11/06/2004] [Indexed: 11/23/2022]
Abstract
The link between the state of energy balance and reproductive function is well known. Thus, signals denoting negative energy balance and the accompanying hyperphagic drive are likely to be factors in the suppression of gonadotropin releasing hormone (GnRH) activity. We have previously found that appetite-regulating systems, such as neuropeptide Y (NPY) in the arcuate nucleus (ARH) and orexin in the lateral hypothalamic area (LHA), send fiber projections that come in close apposition with GnRH neurons. Furthermore, the appropriate receptors, NPY Y5 and OR-1, respectively, are coexpressed on GnRH neurons, providing neuroanatomical evidence for a direct link between the NPY and orexin systems and GnRH neurons. Therefore, these orexigenic neuropeptide systems are potential candidates that convey information about energy balance to GnRH neurons. The current studies focused on melanin concentrating hormone (MCH), another orexigenic neuropeptide system located in the LHA that is sensitive to energy balance. The results showed that MCH fiber projections came in close apposition with approximately 85-90% of GnRH cell bodies throughout the preoptic area and anterior hypothalamic area in the rat. In addition, the MCH receptor (MCHR1) was coexpressed on about 50-55% of GnRH neurons. These findings present evidence for a possible direct neuroanatomical pathway by which MCH may play a role in the regulation of GnRH neuronal function. Thus, MCH is another potential signal that may serve to integrate energy balance and reproductive function.
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Affiliation(s)
- Patricia S Williamson-Hughes
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
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50
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Vaughan CH, Moore MC, Haskell-Luevano C, Rowland NE. Meal patterns and foraging in melanocortin receptor knockout mice. Physiol Behav 2004; 84:129-33. [PMID: 15642615 DOI: 10.1016/j.physbeh.2004.10.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2004] [Revised: 09/03/2004] [Accepted: 10/21/2004] [Indexed: 10/26/2022]
Abstract
We report the meal patterns of mice with the deletion of either the melanocortin type 3 or 4 receptors (MC3RKO or MC4RKO) compared with that of the wild type (WT) under conditions of varying foraging costs. Mice lived in two-lever operant chambers; the completion of a designated number of responses (termed procurement fixed ratio or PFR) on the "foraging" lever activated the other lever. On this second lever, the completion of a designated number of responses (termed consumatory fixed ratio or CFR) caused the delivery of a 20-mg food pellet. Animals could complete as many CFRs as they wished to constitute a meal, but whenever 10 min elapsed without pressing on this second lever, the meal was terminated and pressing on the "foraging" lever was again required to initiate a new meal. At lower PFRs, mice of all three genotypes took 5-7 well-defined meals per day of approximately 35 pellets/meal. At the highest PFR, mice of all three groups took about half this number of meals, with some increase in meal size, and total intake was slightly reduced. MC4RKO mice were obese compared with WT or MC3RKO but failed to eat more food in the operant chambers and, as a consequence, lost weight, regardless of PFR. Thus, changes in meal-taking strategies as a function of imposed foraging cost are not critically dependent on either MC3 or MC4 receptors, but these conditions did not allow us to study meal patterns in MC4RKO mice that are hyperphagic.
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MESH Headings
- Analysis of Variance
- Animals
- Behavior, Animal
- Conditioning, Operant/physiology
- Feeding Behavior/physiology
- Male
- Mice
- Mice, Knockout/physiology
- Receptor, Melanocortin, Type 3/deficiency
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 4/deficiency
- Receptor, Melanocortin, Type 4/genetics
- Reinforcement Schedule
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Affiliation(s)
- C H Vaughan
- Department of Psychology, University of Florida, Gainesville, Fl 32611-2250, USA
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