101
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Affiliation(s)
- Young-Hwan Jo
- Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park avenue, Bronx, NY 10461, USA
| | - Christoph Buettner
- Departments of Medicine and Neuroscience, and Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029-6574, USA
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102
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Leshan RL, Pfaff DW. The hypothalamic ventral premammillary nucleus: A key site in leptin's regulation of reproduction. J Chem Neuroanat 2014; 61-62:239-47. [PMID: 25172030 DOI: 10.1016/j.jchemneu.2014.08.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 08/18/2014] [Accepted: 08/20/2014] [Indexed: 11/24/2022]
Abstract
Reproduction is an energy-expensive process that relies on indicators of energy availability to adjust its proper functioning. The adipokine leptin provides one such metabolic signal, with leptin receptor-expressing neurons at sites widespread within the CNS, including regions associated with the neuroendocrine reproductive axis. One substantial population lies within the hypothalamic ventral premammillary nucleus (PMv), a region itself linked to reproductive control, which may provide a strategic site for the integration of energy availability, sensory and gonadal cues. Here we review our current understanding of leptin and PMv regulation of reproduction, including emerging details about intracellular mechanisms of leptin action at this site.
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Affiliation(s)
- Rebecca L Leshan
- Laboratory of Neurobiology and Behavior, Rockefeller University, Box 275, 1230 York Avenue, New York, NY 10065, United States
| | - Donald W Pfaff
- Laboratory of Neurobiology and Behavior, Rockefeller University, Box 275, 1230 York Avenue, New York, NY 10065, United States.
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103
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Yeoh JW, James MH, Graham BA, Dayas CV. Electrophysiological characteristics of paraventricular thalamic (PVT) neurons in response to cocaine and cocaine- and amphetamine-regulated transcript (CART). Front Behav Neurosci 2014; 8:280. [PMID: 25309361 PMCID: PMC4162416 DOI: 10.3389/fnbeh.2014.00280] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 07/30/2014] [Indexed: 01/01/2023] Open
Abstract
Recent work has established that the paraventricular thalamus (PVT) is a central node in the brain reward-seeking pathway. This role is mediated in part through projections from hypothalamic peptide transmitter systems such as cocaine- and amphetamine-regulated transcript (CART). Consistent with this proposition, we previously found that inactivation of the PVT or infusions of CART into the PVT suppressed drug-seeking behavior in an animal model of contingent cocaine self-administration. Despite this work, few studies have assessed how the basic physiological properties of PVT neurons are influenced by exposure to drugs such as cocaine. Further, our previous work did not assess how infusions of CART, which we found to decrease cocaine-seeking, altered the activity of PVT neurons. In the current study we address these issues by recording from anterior PVT (aPVT) neurons in acutely prepared brain slices from cocaine-treated (15 mg/ml, n = 8) and saline-treated (control) animals (n = 8). The excitability of aPVT neurons was assessed by injecting a series of depolarizing and hyperpolarizing current steps and characterizing the resulting action potential (AP) discharge properties. This analysis indicated that the majority of aPVT neurons exhibit tonic firing (TF), and initial bursting (IB) consistent with previous studies. However, we also identified PVT neurons that exhibited delayed firing (DF), single spiking (SS) and reluctant firing (RF) patterns. Interestingly, cocaine exposure significantly increased the proportion of aPVT neurons that exhibited TF. We then investigated the effects of CART on excitatory synaptic inputs to aPVT neurons. Application of CART significantly suppressed excitatory synaptic drive to PVT neurons in both cocaine-treated and control recordings. This finding is consistent with our previous behavioral data, which showed that CART signaling in the PVT negatively regulates drug-seeking behavior. Together, these studies suggest that cocaine exposure shifts aPVT neurons to a more excitable state (TF). We propose that the capacity of CART to reduce excitatory drive to this population balances the enhanced aPVT excitability to restore the net output of this region in the reward-seeking pathway. This is in line with previous anatomical evidence that the PVT can integrate reward-relevant information and provides a putative mechanism through which drugs of abuse can dysregulate this system in addiction.
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Affiliation(s)
- Jiann Wei Yeoh
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy, and The Centre for Translational Neuroscience and Mental Health Research, University of Newcastle and the Hunter Medical Research Institute Newcastle, NSW, Australia
| | - Morgan H James
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy, and The Centre for Translational Neuroscience and Mental Health Research, University of Newcastle and the Hunter Medical Research Institute Newcastle, NSW, Australia
| | - Brett A Graham
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy, and The Centre for Translational Neuroscience and Mental Health Research, University of Newcastle and the Hunter Medical Research Institute Newcastle, NSW, Australia
| | - Christopher V Dayas
- Neurobiology of Addiction Laboratory, School of Biomedical Sciences and Pharmacy, and The Centre for Translational Neuroscience and Mental Health Research, University of Newcastle and the Hunter Medical Research Institute Newcastle, NSW, Australia
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104
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Neurochemical pathways that converge on thalamic trigeminovascular neurons: potential substrate for modulation of migraine by sleep, food intake, stress and anxiety. PLoS One 2014; 9:e103929. [PMID: 25090640 PMCID: PMC4121288 DOI: 10.1371/journal.pone.0103929] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 07/08/2014] [Indexed: 12/24/2022] Open
Abstract
Dynamic thalamic regulation of sensory signals allows the cortex to adjust better to rapidly changing behavioral, physiological and environmental demands. To fulfill this role, thalamic neurons must themselves be subjected to constantly changing modulatory inputs that originate in multiple neurochemical pathways involved in autonomic, affective and cognitive functions. Our overall goal is to define an anatomical framework for conceptualizing how a ‘decision’ is made on whether a trigeminovascular thalamic neuron fires, for how long, and at what frequency. To begin answering this question, we determine which neuropeptides/neurotransmitters are in a position to modulate thalamic trigeminovascular neurons. Using a combination of in-vivo single-unit recording, juxtacellular labeling with tetramethylrhodamine dextran (TMR) and in-vitro immunohistochemistry, we found that thalamic trigeminovascular neurons were surrounded by high density of axons containing biomarkers of glutamate, GABA, dopamine and serotonin; moderate density of axons containing noradrenaline and histamine; low density of axons containing orexin and melanin concentrating hormone (MCH); but not axons containing CGRP, serotonin 1D receptor, oxytocin or vasopressin. In the context of migraine, the findings suggest that the transmission of headache-related nociceptive signals from the thalamus to the cortex may be modulated by opposing forces (i.e., facilitatory, inhibitory) that are governed by continuous adjustments needed to keep physiological, behavioral, cognitive and emotional homeostasis.
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105
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Skrapits K, Borsay BÁ, Herczeg L, Ciofi P, Bloom SR, Ghatei MA, Dhillo WS, Liposits Z, Hrabovszky E. Colocalization of cocaine- and amphetamine-regulated transcript with kisspeptin and neurokinin B in the human infundibular region. PLoS One 2014; 9:e103977. [PMID: 25084101 PMCID: PMC4118993 DOI: 10.1371/journal.pone.0103977] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 07/08/2014] [Indexed: 01/08/2023] Open
Abstract
Kisspeptin (KP)- and neurokinin B (NKB)- synthesizing neurons of the hypothalamic arcuate nucleus play a pivotal role in the regulation of pulsatile gonadotropin-releasing hormone (GnRH) secretion. Unlike in rodents and sheep, the homologous KP and NKB neurons in the human infundibular region rarely express dynorphin- but often exhibit Substance P (SP) immunoreactivity, indicating remarkable species differences in the neurochemical phenotype of these neurons. In search for additional neuropeptides in human KP and NKB neurons, we carried out immunofluorescent studies on hypothalamic sections obtained from five postmenopausal women. Colocalization experiments provided evidence for the presence of cocaine- and amphetamine-regulated transcript (CART) in 47.9±6.6% of KP-immunoreactive (IR) and 30.0±4.9% of NKB-IR perikarya and in 17.0±2.3% of KP-IR and 6.2±2.0% of NKB-IR axon varicosities. All three neuropeptides were present in 33.3±4.9% of KP-IR and 28.2±4.6% of NKB-IR somata, respectively, whereas triple-labeling showed lower incidences in KP-IR (14.3±1.8%) and NKB-IR (5.9±2.0%) axon varicosities. CART-IR KP and NKB neurons established contacts with other peptidergic cells, including GnRH-IR neurons and also sent projections to the infundibular stalk. KP and NKB fibers with CART often contained SP as well, while being distinct from CART fibers co-containing the orexigenic peptide agouti-related protein. Presence of CART in human, but not rodent, KP and NKB neurons represents a new example of species differences in the neuropeptide repertoire of mediobasal hypothalamic KP and NKB neurons. Target cells, receptor sites and physiological significance of CART in the efferent communication of KP and NKB neurons in primates require clarification.
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Affiliation(s)
- Katalin Skrapits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Beáta Á. Borsay
- Department of Forensic Medicine, Faculty of Medicine of the University of Debrecen, Debrecen, Hungary
| | - László Herczeg
- Department of Forensic Medicine, Faculty of Medicine of the University of Debrecen, Debrecen, Hungary
| | | | - Stephen R. Bloom
- Department of Investigative Medicine, Hammersmith Hospital, Imperial College London, London, United Kingdom
| | - Mohammad A. Ghatei
- Department of Investigative Medicine, Hammersmith Hospital, Imperial College London, London, United Kingdom
| | - Waljit S. Dhillo
- Department of Investigative Medicine, Hammersmith Hospital, Imperial College London, London, United Kingdom
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Department of Neuroscience, Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
| | - Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- * E-mail:
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106
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The neuroanatomical function of leptin in the hypothalamus. J Chem Neuroanat 2014; 61-62:207-20. [PMID: 25007719 DOI: 10.1016/j.jchemneu.2014.05.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Revised: 05/09/2014] [Accepted: 05/28/2014] [Indexed: 02/07/2023]
Abstract
The anorexigenic hormone leptin plays an important role in the control of food intake and feeding-related behavior, for an important part through its action in the hypothalamus. The adipose-derived hormone modulates a complex network of several intercommunicating orexigenic and anorexigenic neuropeptides in the hypothalamus to reduce food intake and increase energy expenditure. In this review we present an updated overview of the functional role of leptin in respect to feeding and feeding-related behavior per distinct hypothalamic nuclei. In addition to the arcuate nucleus, which is a major leptin sensitive hub, leptin-responsive neurons in other hypothalamic nuclei, including the, dorsomedial-, ventromedial- and paraventricular nucleus and the lateral hypothalamic area, are direct targets of leptin. However, leptin also modulates hypothalamic neurons in an indirect manner, such as via the melanocortin system. The dissection of the complexity of leptin's action on the networks involved in energy balance is subject of recent and future studies. A full understanding of the role of hypothalamic leptin in the regulation of energy balance requires cell-specific manipulation using of conditional deletion and expression of leptin receptors. In addition, optogenetic and pharmacogenetic tools in combination with other pharmacological (such as the recent discovery of a leptin receptor antagonist) and neuronal tracing techniques to map the circuit, will be helpful to understand the role of leptin receptor expressing neurons. Better understanding of these circuits and the involvement of leptin could provide potential sites for therapeutic interventions in obesity and metabolic diseases characterized by dysregulation of energy balance.
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107
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Horjales-Araujo E, Hellysaz A, Broberger C. Lateral hypothalamic thyrotropin-releasing hormone neurons: distribution and relationship to histochemically defined cell populations in the rat. Neuroscience 2014; 277:87-102. [PMID: 24993479 DOI: 10.1016/j.neuroscience.2014.06.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 06/13/2014] [Accepted: 06/20/2014] [Indexed: 12/30/2022]
Abstract
The lateral hypothalamic area (LHA) constitutes a large component of the hypothalamus, and has been implicated in several aspects of motivated behavior. The LHA is of particular relevance to behavioral state control and the maintenance of arousal. Due to the cellular heterogeneity of this region, however, only some subpopulations of LHA cells have been properly anatomically characterized. Here, we have focused on cells expressing thyrotropin-releasing hormone (TRH), a peptide found in the LHA that has been implicated as a promoter of arousal. Immunofluorescence and in situ hybridization were used to map the LHA TRH population in the rat, and cells were observed to form a large ventral cluster that extended throughout almost the entire rostro-caudal axis of the hypothalamus. Almost no examples of coexistence were seen when sections were double-stained for TRH and markers of other LHA populations, including the peptides hypocretin/orexin, melanin-concentrating hormone and neurotensin. In the juxtaparaventricular area, however, a discrete group of TRH-immunoreactive cells were also stained with antisera against enkephalin and urocortin 3. Innervation from the metabolically sensitive hypothalamic arcuate nucleus was investigated by double-staining for peptide markers of the two centrally projecting groups of arcuate neurons, agouti gene-related peptide and α-melanocyte-stimulating hormone, respectively; both populations of terminals were observed forming close appositions on TRH cells in the LHA. The present study indicates that TRH-expressing cells form a unique population in the LHA that may serve as a link between metabolic signals and the generation of arousal.
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Affiliation(s)
- E Horjales-Araujo
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - A Hellysaz
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - C Broberger
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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108
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Akieda-Asai S, Poleni PE, Date Y. Coinjection of CCK and leptin reduces food intake via increased CART/TRH and reduced AMPK phosphorylation in the hypothalamus. Am J Physiol Endocrinol Metab 2014; 306:E1284-91. [PMID: 24735891 DOI: 10.1152/ajpendo.00664.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
CCK and leptin are anorectic hormones produced in the small intestine and white adipose tissue, respectively. Investigating how these hormones act together as an integrated anorectic signal is important for elucidating the mechanisms by which energy balance is maintained. We found here that coadministration of subthreshold CCK and leptin, which individually have no effect on feeding, dramatically reduced food intake in rats. Phosphorylation of AMP-activated protein kinase (AMPK) in the hypothalamus significantly decreased after coinjection of CCK and leptin. In addition, coadministration of these hormones significantly increased mRNA levels of anorectic cocaine- and amphetamine-regulated transcript (CART) and thyrotropin-releasing hormone (TRH) in the hypothalamus. The interactive effect of CCK and leptin on food intake was abolished by intracerebroventricular preadministration of the AMPK activator AICAR or anti-CART/anti-TRH antibodies. These findings indicate that coinjection of CCK and leptin reduces food intake via reduced AMPK phosphorylation and increased CART/TRH in the hypothalamus. Furthermore, by using midbrain-transected rats, we investigated the role of the neural pathway from the hindbrain to the hypothalamus in the interaction of CCK and leptin to reduce food intake. Food intake reduction induced by coinjection of CCK and leptin was blocked in midbrain-transected rats. Therefore, the neural pathway from hindbrain to hypothalamus plays an important role in transmitting the anorectic signals provided by coinjection of CCK and leptin. Our findings give further insight into the mechanisms of feeding and energy balance.
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Affiliation(s)
- Sayaka Akieda-Asai
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Paul-Emile Poleni
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Yukari Date
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
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109
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Subhedar NK, Nakhate KT, Upadhya MA, Kokare DM. CART in the brain of vertebrates: circuits, functions and evolution. Peptides 2014; 54:108-30. [PMID: 24468550 DOI: 10.1016/j.peptides.2014.01.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/10/2014] [Accepted: 01/10/2014] [Indexed: 12/12/2022]
Abstract
Cocaine- and amphetamine-regulated transcript peptide (CART) with its wide distribution in the brain of mammals has been the focus of considerable research in recent years. Last two decades have witnessed a steady rise in the information on the genes that encode this neuropeptide and regulation of its transcription and translation. CART is highly enriched in the hypothalamic nuclei and its relevance to energy homeostasis and neuroendocrine control has been understood in great details. However, the occurrence of this peptide in a range of diverse circuitries for sensory, motor, vegetative, limbic and higher cortical areas has been confounding. Evidence that CART peptide may have role in addiction, pain, reward, learning and memory, cognition, sleep, reproduction and development, modulation of behavior and regulation of autonomic nervous system are accumulating, but an integration has been missing. A steady stream of papers has been pointing at the therapeutic potentials of CART. The current review is an attempt at piecing together the fragments of available information, and seeks meaning out of the CART elements in their anatomical niche. We try to put together the CART containing neuronal circuitries that have been conclusively demonstrated as well as those which have been proposed, but need confirmation. With a view to finding out the evolutionary antecedents, we visit the CART systems in sub-mammalian vertebrates and seek the answer why the system is shaped the way it is. We enquire into the conservation of the CART system and appreciate its functional diversity across the phyla.
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Affiliation(s)
- Nishikant K Subhedar
- Indian Institute of Science Education and Research (IISER), Sai Trinity Building, Sutarwadi, Pashan, Pune 411 021, Maharashtra, India.
| | - Kartik T Nakhate
- Rungta College of Pharmaceutical Sciences and Research, Rungta Educational Campus, Kohka-Kurud Road, Bhilai 490 024, Chhattisgarh, India
| | - Manoj A Upadhya
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, Maharashtra, India
| | - Dadasaheb M Kokare
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, Maharashtra, India
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110
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Lee JS, Lee HS. Reciprocal connections between CART-immunoreactive, hypothalamic paraventricular neurons and serotonergic dorsal raphe cells in the rat: Light microscopic study. Brain Res 2014; 1560:46-59. [DOI: 10.1016/j.brainres.2014.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 02/13/2014] [Accepted: 03/07/2014] [Indexed: 10/25/2022]
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111
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Solomon A, De Fanti BA, Martínez JA. Peripheral Ghrelin participates in glucostatic feeding mechanisms and in the anorexigenic signalling mediated by CART and CRF neurons. Nutr Neurosci 2013; 8:287-95. [PMID: 16669599 DOI: 10.1080/10284150500502546] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Ghrelin is upregulated under negative energy balance conditions, including starvation and hypoglycemia, while it is downregulated under situations of positive energy balance, such as feeding, hyperglycemia and obesity. The aims of this study were to assess potential ghrelin interactions with glucose levels in appetite control and to identify potential mechanisms involving orexigenic and anorexigenic ghrelin mediated signals by using a specific anti-ghrelin antibody. Our results confirm that peripheral ghrelin is an important signal in meal initiation and food intake stimulation. C-fos positive neurons in the PVN increased after insulin or 2-deoxyglucose administration. Moreover, we also demonstrate that peripheral ghrelin blockade with a specific anti-ghrelin antibody reduces, in part, the orexigenic signal induced by insulin and 2-DG administration. Furthermore, when we blocked peripheral ghrelin, c-fos positive CRF neurons and CART expression increased in the PVN, both under hypoglycemia or cytoglycopenia conditions, suggesting a neuronal activation (anorexigenic signalling) in this hypothalamic region. In summary, our findings imply that peripheral ghrelin plays an important role in regulatory "glucostatic" feeding mechanisms due to its role as a "hunger" signal affecting the PVN area, which may contribute to energy homeostasis through both orexigenic/anorexigenic pathways.
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Affiliation(s)
- Andrew Solomon
- Department of Physiology and Nutrition, University of Navarra, 31008 Pamplona, Spain
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112
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Leptin stimulates neuropeptide Y and cocaine amphetamine-regulated transcript coexpressing neuronal activity in the dorsomedial hypothalamus in diet-induced obese mice. J Neurosci 2013; 33:15306-17. [PMID: 24048859 DOI: 10.1523/jneurosci.0837-13.2013] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Neuropeptide Y (NPY) neurons in both the arcuate nucleus of the hypothalamus (ARH) and the dorsomedial hypothalamus (DMH) have been implicated in food intake and obesity. However, while ARH NPY is highly expressed in the lean animal, DMH NPY mRNA expression is observed only after diet-induced obesity (DIO). Furthermore, while ARH NPY neurons are inhibited by leptin, the effect of this adipokine on DMH NPY neurons is unknown. In this study we show that in contrast to the consistent expression in the ARH, DMH NPY mRNA expression was undetectable until after 10 weeks in mice fed a high-fat diet, and peaked at 20 weeks. Surprisingly, electrophysiological experiments demonstrated that leptin directly depolarized and increased the firing rate of DMH NPY neurons in DIO mice. To further differentiate the regulation of DMH and ARH NPY populations, fasting decreased expression of DMH NPY expression, while it increased ARH NPY expression. However, treatment with a leptin receptor antagonist failed to alter DMH NPY expression, indicating that leptin may not be the critical factor regulating mRNA expression. Importantly, we also demonstrated that DMH NPY neurons coexpress cocaine amphetamine-regulated transcript (CART); however, CART mRNA expression in the DMH peaked earlier in the progression of DIO. This study demonstrates novel and important findings. First, NPY and CART are coexpressed in the same neurons within the DMH, and second, leptin stimulates DMH NPY neurons. These studies suggest that during the progression of DIO, there is an unknown signal that drives the expression of the orexigenic NPY signal within the DMH, and that the chronic hyperleptinemia increases the activity of these NPY/CART neurons.
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113
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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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114
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Jego S, Glasgow SD, Herrera CG, Ekstrand M, Reed SJ, Boyce R, Friedman J, Burdakov D, Adamantidis AR. Optogenetic identification of a rapid eye movement sleep modulatory circuit in the hypothalamus. Nat Neurosci 2013; 16:1637-43. [PMID: 24056699 PMCID: PMC4974078 DOI: 10.1038/nn.3522] [Citation(s) in RCA: 283] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 08/23/2013] [Indexed: 12/22/2022]
Abstract
Rapid-Eye Movement (REM) sleep correlates with neuronal activity in the brainstem, basal forebrain and lateral hypothalamus (LH). LH melanin-concentrating hormone (MCH)-expressing neurons are active during sleep, however, their action on REM sleep remains unclear. Using optogenetic tools in newly-generated Tg(Pmch-Cre) mice, we found that acute activation of MCH neurons (ChETA, SSFO) at the onset of REM sleep extended the duration of REM, but not non-REM sleep episode. In contrast, their acute silencing (eNpHR3.0, ArchT) reduced the frequency and amplitude of hippocampal theta rhythm, without affecting REM sleep duration. In vitro activation of MCH neuron terminals induced GABAA-mediated inhibitory post-synaptic currents (IPSCs) in wake-promoting histaminergic neurons of the tuberomammillary nucleus (TMN), while in vivo activation of MCH neuron terminals in TMN or medial septum also prolonged REM sleep episodes. Collectively, these results suggest that activation of MCH neurons maintains REM sleep, possibly through inhibition of arousal circuits in the mammalian brain.
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Affiliation(s)
- Sonia Jego
- Douglas Institute, Department of Psychiatry, McGill University, Montreal, Canada
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115
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Abstract
Melanin concentrating hormone (MCH) is a cyclic neuropeptide present in the hypothalamus of all vertebrates. MCH is implicated in a number of behaviors but direct evidence is lacking. To selectively stimulate the MCH neurons the gene for the light-sensitive cation channel, channelrhodopsin-2, was inserted into the MCH neurons of wild-type mice. Three weeks later MCH neurons were stimulated for 1 min every 5 min for 24 h. A 10 Hz stimulation at the start of the night hastened sleep onset, reduced length of wake bouts by 50%, increased total time in non-REM and REM sleep at night, and increased sleep intensity during the day cycle. Sleep induction at a circadian time when all of the arousal neurons are active indicates that MCH stimulation can powerfully counteract the combined wake-promoting signal of the arousal neurons. This could be potentially useful in treatment of insomnia.
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116
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Gao S, Moran TH, Lopaschuk GD, Butler AA. Hypothalamic malonyl-CoA and the control of food intake. Physiol Behav 2013; 122:17-24. [PMID: 23988346 DOI: 10.1016/j.physbeh.2013.07.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 12/19/2022]
Abstract
Fatty acid metabolism is implicated in the hypothalamic control of food intake. In this regard, malonyl-CoA, an intermediate in fatty acid synthesis, is emerging as a key player. Malonyl-CoA in the hypothalamus has been proposed as an anorectic mediator in the central control of feeding. A large body of evidence demonstrates that modulating hypothalamic activities of malonyl-CoA metabolic enzymes impacts food intake. Malonyl-CoA action appears to play a significant role in the intracellular signaling pathways underlying leptin anorectic effect in the arcuate nucleus. Ghrelin's hypothalamic effect on feeding may also involve the change in malonyl-CoA metabolism. Hypothalamic malonyl-CoA levels are altered in response to fasting and refeeding, suggesting physiological relevance of the changes in malonyl-CoA level in the controls of feeding and energy balance. Malonyl-CoA inhibits the acyltransferase activity of carnitine palmitoyltransferase-1 (CPT-1), and CPT-1 was considered as a downstream effector in hypothalamic malonyl-CoA effect on feeding. However, recent evidence has not been entirely consistent with this notion. In the arcuate nucleus, the inhibition of CPT-1 acyltransferase activity does not play an important role in the feeding effect of either leptin or cerulenin (a fatty acid synthase inhibitor) that requires the increase in malonyl-CoA level. Alternatively, the brain isoform of CPT-1 (CPT-1c) may act as a downstream target in the malonyl-CoA signaling pathways. CPT-1c does not possess a typical acyltransferase activity, and the exact molecular function of this protein is currently unknown. Recent data indicate it is involved in ceramide metabolism. Of relevance, in the arcuate nucleus, CPT-1c may link malonyl-CoA to ceramide metabolism to affect food intake.
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Affiliation(s)
- Su Gao
- Department of Metabolism and Aging, Scripps Research Institute, Jupiter, FL 33458, USA.
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117
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True C, Verma S, Grove KL, Smith MS. Cocaine- and amphetamine-regulated transcript is a potent stimulator of GnRH and kisspeptin cells and may contribute to negative energy balance-induced reproductive inhibition in females. Endocrinology 2013; 154:2821-32. [PMID: 23736294 PMCID: PMC3713223 DOI: 10.1210/en.2013-1156] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cocaine- and amphetamine-regulated transcript (CART) is a hypothalamic neuropeptide implicated in both metabolic and reproductive regulation, raising the possibility that CART plays a role in reproductive inhibition during negative metabolic conditions. The current study characterized CART's regulatory influence on GnRH and kisspeptin (Kiss1) cells and determined the sensitivity of different CART populations to negative energy balance. CART fibers made close appositions to 60% of GnRH cells, with the majority of the fibers (>80%) originating from the arcuate nucleus (ARH) CART/pro-opiomelanocortin population. Electrophysiological recordings in GnRH-green fluorescent protein rats demonstrated that CART postsynaptically depolarizes GnRH cells. CART fibers from the ARH were also observed in close contact with Kiss1 cells in the ARH and anteroventral periventricular nucleus (AVPV). Recordings in Kiss1-GFP mice demonstrated CART also postsynaptically depolarizes ARH Kiss1 cells, suggesting CART may act directly and indirectly, via Kiss1 populations, to stimulate GnRH neurons. CART protein and mRNA levels were analyzed in 2 models of negative energy balance: caloric restriction (CR) and lactation. Both CART mRNA levels and the number of CART-immunoreactive cells were suppressed in the ARH during CR but not during lactation. AVPV CART mRNA was suppressed during CR, but not during lactation when there was a dramatic increase in CART-immunoreactive cells. These data suggest differing regulatory signals of CART between the models. In conclusion, both morphological and electrophysiological methods identify CART as a novel and potent stimulator of Kiss1 and GnRH neurons and suppression of CART expression during negative metabolic conditions could contribute to inhibition of the reproductive axis.
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Affiliation(s)
- Cadence True
- Divisions of Diabetes, Obesity, & Metabolism, and Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
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118
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Meister B, Perez-Manso M, Daraio T. Delta-like 1 homologue is a hypothalamus-enriched protein that is present in orexin-containing neurones of the lateral hypothalamic area. J Neuroendocrinol 2013; 25:617-25. [PMID: 23387476 DOI: 10.1111/jne.12029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 01/03/2013] [Accepted: 01/30/2013] [Indexed: 01/18/2023]
Abstract
Delta-like 1 homologue (DLK1), also known as preadipocyte factor-1, fetal antigen 1 or pG2, is a transmembrane protein belonging to the epidermal growth factor-like superfamily. The protein becomes soluble and biologically active after cleavage of the tumour necrosis factor-α-converting enzyme. DLK1 is involved in the differentiation of several cell types, including adipocytes. Lack of the dlk1 gene in mice results in adiposity and a polymorphism within the gene encoding DLK1 has been associated with obesity. The dlk1 gene is expressed in restricted areas of the central nervous system with an enrichment of cell bodies expressing DLK1 mRNA in the hypothalamus. Goat and rabbit antisera to DLK1 were used to study the cellular localisation and chemical identity of DLK1-immunoreactive neuronal cell bodies in rat hypothalamus. DLK1 immunoreactivity was demonstrated in the cell bodies of the suprachiasmatic, supraoptic, paraventricular, arcuate nuclei and in the lateral hypothalamus. At the subcellular level, DLK1 immunoreactivity was observed in the cell soma and dendrites, although not in axonal fibres or nerve terminals. Double-labelling of sections from the lateral hypothalamic/perifornical area of colchicine-treated rats (a treatment that increases the content of immunoreactive material in the cell soma) showed that DLK1 was present in the virually all orexin- and dynorphin-containing neurones. By contrast, DLK1 was not demonstrated in any melanin-concentrating hormone or cocaine- and amphetamine-regulated transcript-containing neurones of the lateral hypothalamic/perifornical area. The presence of DLK1 in a population of lateral hypothalamic neurones suggests a functional role for DLK1 in orexin/hypocretin/dynorphin neurones.
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Affiliation(s)
- B Meister
- Department of Neuroscience, Karolinska Institutet, Stockholm SE-171 77, Sweden.
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119
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Yoon YS, Lee JS, Lee HS. Retrograde study of CART- or NPY-neuronal projection from the hypothalamic arcuate nucleus to the dorsal raphe and/or the locus coeruleus in the rat. Brain Res 2013; 1519:40-52. [DOI: 10.1016/j.brainres.2013.04.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 04/08/2013] [Accepted: 04/19/2013] [Indexed: 11/16/2022]
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120
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Sohn JW. Ion channels in the central regulation of energy and glucose homeostasis. Front Neurosci 2013; 7:85. [PMID: 23734095 PMCID: PMC3661948 DOI: 10.3389/fnins.2013.00085] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Accepted: 05/08/2013] [Indexed: 11/23/2022] Open
Abstract
Ion channels are critical regulators of neuronal excitability and synaptic function in the brain. Recent evidence suggests that ion channels expressed by neurons within the brain are responsible for regulating energy and glucose homeostasis. In addition, the central effects of neurotransmitters and hormones are at least in part achieved by modifications of ion channel activity. This review focuses on ion channels and their neuronal functions followed by a discussion of the identified roles for specific ion channels in the central pathways regulating food intake, energy expenditure, and glucose balance.
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Affiliation(s)
- Jong-Woo Sohn
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center Dallas, TX, USA
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121
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Ablation of neurons expressing melanin-concentrating hormone (MCH) in adult mice improves glucose tolerance independent of MCH signaling. J Neurosci 2013; 33:2009-16. [PMID: 23365238 DOI: 10.1523/jneurosci.3921-12.2013] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Melanin-concentrating hormone (MCH)-expressing neurons have been ascribed many roles based on studies of MCH-deficient mice. However, MCH neurons express other neurotransmitters, including GABA, nesfatin, and cocaine-amphetamine-regulated transcript. The importance of these other signaling molecules made by MCH neurons remains incompletely characterized. To determine the roles of MCH neurons in vivo, we targeted expression of the human diphtheria toxin receptor (DTR) to the gene for MCH (Pmch). Within 2 weeks of diphtheria toxin injection, heterozygous Pmch(DTR/+) mice lost 98% of their MCH neurons. These mice became lean but ate normally and were hyperactive, especially during a fast. They also responded abnormally to psychostimulants. For these phenotypes, ablation of MCH neurons recapitulated knock-out of MCH, so MCH appears to be the critical neuromodulator released by these neurons. In contrast, MCH-neuron-ablated mice showed improved glucose tolerance when compared with MCH-deficient mutant mice and wild-type mice. We conclude that MCH neurons regulate glucose tolerance through signaling molecules other than MCH.
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122
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The vertebrate diencephalic MCH system: a versatile neuronal population in an evolving brain. Front Neuroendocrinol 2013; 34:65-87. [PMID: 23088995 DOI: 10.1016/j.yfrne.2012.10.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 10/05/2012] [Accepted: 10/10/2012] [Indexed: 11/22/2022]
Abstract
Neurons synthesizing melanin-concentrating hormone (MCH) are described in the posterior hypothalamus of all vertebrates investigated so far. However, their anatomy is very different according to species: they are small and periventricular in lampreys, cartilaginous fishes or anurans, large and neuroendocrine in bony fishes, or distributed over large regions of the lateral hypothalamus in many mammals. An analysis of their comparative anatomy alongside recent data about the development of the forebrain, suggests that although very different, MCH neurons of the caudal hypothalamus are homologous. We further hypothesize that their divergent anatomy is linked to divergence in the forebrain - in particular telencephalic evolution.
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123
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Yoon YS, Lee HS. Projection patterns of lateral hypothalamic, cocaine- and amphetamine-regulated transcript (CART) neurons to the dorsal raphe and/or the locus coeruleus in the rat. Brain Res 2013. [DOI: 10.1016/j.brainres.2012.11.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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124
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Romanova IV. Morphofunctional interaction of CART peptide and dopaminergic brain neurons. J EVOL BIOCHEM PHYS+ 2013. [DOI: 10.1134/s0022093013010143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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125
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Garfield AS, Patterson C, Skora S, Gribble FM, Reimann F, Evans ML, Myers MG, Heisler LK. Neurochemical characterization of body weight-regulating leptin receptor neurons in the nucleus of the solitary tract. Endocrinology 2012; 153:4600-7. [PMID: 22869346 PMCID: PMC3507354 DOI: 10.1210/en.2012-1282] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Accepted: 07/12/2012] [Indexed: 11/19/2022]
Abstract
The action of peripherally released leptin at long-form leptin receptors (LepRb) within the brain represents a fundamental axis in the regulation of energy homeostasis and body weight. Efforts to delineate the neuronal mediators of leptin action have recently focused on extrahypothalamic populations and have revealed that leptin action within the nucleus of the solitary tract (NTS) is critical for normal appetite and body weight regulation. To elucidate the neuronal circuits that mediate leptin action within the NTS, we employed multiple transgenic reporter lines to characterize the neurochemical identity of LepRb-expressing NTS neurons. LepRb expression was not detected in energy balance-associated NTS neurons that express cocaine- and amphetamine-regulated transcript, brain-derived neurotrophic factor, neuropeptide Y, nesfatin, catecholamines, γ-aminobutyric acid, prolactin-releasing peptide, or nitric oxide synthase. The population of LepRb-expressing NTS neurons was comprised of subpopulations marked by a proopiomelanocortin-enhanced green fluorescent protein (EGFP) transgene and distinct populations that express proglucagon and/or cholecystokinin. The significance of leptin action on these three populations of NTS neurons was assessed in leptin-deficient Ob/Ob mice, revealing increased NTS proglucagon and cholecystokinin, but not proopiomelanocortin, expression. These data provide new insight into the appetitive brainstem circuits engaged by leptin.
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Affiliation(s)
- Alastair S Garfield
- University of Cambridge, Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
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126
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Region- and sex-specific changes in CART mRNA in rat hypothalamic nuclei induced by forced swim stress. Brain Res 2012; 1479:62-71. [PMID: 22960117 DOI: 10.1016/j.brainres.2012.08.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 08/23/2012] [Accepted: 08/24/2012] [Indexed: 01/22/2023]
Abstract
Cocaine and amphetamine regulated transcript (CART) mRNA and peptides are highly expressed in the paraventricular (PVN), dorsomedial (DMH) and arcuate (ARC) nuclei of the hypothalamus. It has been suggested that these nuclei regulate the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system activity, and feeding behavior. Our previous studies showed that forced swim stress augmented CART peptide expression significantly in whole hypothalamus of male rats. In another study, forced swim stress increased the number of CART-immunoreactive cells in female PVN, whereas no effect was observed in male PVN or in the ARC nucleus of either sex. In the present study, we evaluated the effect of forced swim stress on CART mRNA expression in PVN, DMH and ARC nuclei in both male and female rats. Twelve male (stressed and controls, n=6 each) and 12 female (stressed and controls, n=6 each) Sprague-Dawley rats were used. Control animals were only handled, whereas forced swim stress procedure was applied to the stressed groups. Brains were dissected and brain sections containing PVN, DMH and ARC nuclei were prepared. CART mRNA levels were determined by in situ hybridization. In male rats, forced swim stress upregulated CART mRNA expression in DMH and downregulated it in the ARC. In female rats, forced swim stress increased CART mRNA expression in PVN and DMH, whereas a decrease was observed in the ARC nucleus. Our results show that forced swim stress elicits region- and sex-specific changes in CART mRNA expression in rat hypothalamus that may help in explaining some of the effects of stress.
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127
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Immunohistochemical evidence for synaptic release of GABA from melanin-concentrating hormone containing varicosities in the locus coeruleus. Neuroscience 2012; 223:269-76. [PMID: 22890079 DOI: 10.1016/j.neuroscience.2012.07.072] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 07/26/2012] [Accepted: 07/31/2012] [Indexed: 11/22/2022]
Abstract
Melanin-concentrating hormone (MCH) is synthesized by neurons located in the hypothalamus and projecting to widespread regions of the brain, including the locus coeruleus (LC), through which MCH could modulate sleep-wake states. Yet MCH does not appear to exert direct postsynaptic effects on target neurons, including the noradrenergic LC neurons. Previous studies using in situ hybridization showed that MCH neurons synthesize glutamic acid decarboxylase (GAD) and could thus utilize GABA as a neurotransmitter. To determine whether MCH varicosities can release GABA, we examined by fluorescent microscopy in the LC, whether their terminals also contain the vesicular transporter for GABA (VGAT). In dual-immunostained sections, we found that approximately 6% of MCH varicosities was immunopositive for VGAT and a similar proportion for synaptophysin, the presynaptic marker for small synaptic vesicles, whereas <1% was positive for the vesicular glutamate transporter (VGluT2). Moreover, of the MCH varicosities, ∼5% abutted puncta that were immunostained for gephyrin, the postsynaptic marker for GABAergic synapses. In triple-immunostained sections viewed with confocal laser scanning microscopy, we established that MCH varicosities that also contained VGAT or abutted upon gephyrin puncta contacted the tyrosine hydroxylase-immunostained neurons of the LC. Our results suggest that although MCH neurons can influence noradrenergic LC neurons through paracrine release and indirect effects of their peptide, they can also do so through synaptic release and direct postsynaptic effects of GABA and thus serve to inhibit the LC neurons during sleep, when they are silent, and the MCH neurons discharge.
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128
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Yeoh JW, James MH, Jobling P, Bains JS, Graham BA, Dayas CV. Cocaine potentiates excitatory drive in the perifornical/lateral hypothalamus. J Physiol 2012; 590:3677-89. [PMID: 22641785 DOI: 10.1113/jphysiol.2012.230268] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The hypothalamus is a critical controller of homeostatic responses and plays a fundamental role in reward-seeking behaviour. Recently, hypothalamic neurones in the perifornical/lateral hypothalamic area (PF/LHA) have also been implicated in drug-seeking behaviour through projections to extra-hypothalamic sites such as the ventral tegmental area. For example, a population of neurones that expresses the peptide orexin has been strongly implicated in addiction-relevant behaviours. To date, the effect of addictive drugs on synaptic properties in the hypothalamus remains largely unexplored. Previous studies focusing on the PF/LHA neurones, however, have shown that the orexin system exhibits significant plasticity in response to food or sleep restriction. This neuroadaptive ability suggests that PF/LHA neurones could be highly susceptible to modifications by drug exposure. Here, we sought to determine whether cocaine produces synaptic plasticity in PF/LHA neurones. Whole-cell patch-clamp techniques were used to examine the effects of experimenter-administered (passive) or self-administered (SA) cocaine on glutamatergic synaptic transmission in PF/LHA neurones. These experiments demonstrate that both passive and SA cocaine exposure increases miniature excitatory postsynaptic current (mEPSC) frequency in PF/LHA neurones. In addition, SA cocaine reduced the paired-pulse ratio but the AMPA/NMDA ratio of evoked excitatory inputs was unchanged, indicative of a presynaptic locus for synaptic plasticity. Dual-labelling for orexin and excitatory inputs using the vesicular glutamate transporter (VGLUT2), showed that passive cocaine exposure increased VGLUT2-positive appositions onto orexin neurones. Further, a population of recorded neurones that were filled with neurobiotin and immunolabelled for orexin confirmed that increased excitatory drive occurs in this PF/LHA population. Given the importance of the PF/LHA and the orexin system in modulating drug addiction, we suggest that these cocaine-induced excitatory synapse-remodelling events within the hypothalamus may contribute to persistence in drug-seeking behaviour and relapse.
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Affiliation(s)
- Jiann Wei Yeoh
- 1School of Biomedical Sciences and Pharmacy, and the Centre for Translational Neuroscience and Mental Health Research, University of Newcastle,Callaghan, NSW 2308, Australia
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129
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Thyrotropin-releasing hormone (TRH) inhibits melanin-concentrating hormone neurons: implications for TRH-mediated anorexic and arousal actions. J Neurosci 2012; 32:3032-43. [PMID: 22378876 DOI: 10.1523/jneurosci.5966-11.2012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Thyrotropin-releasing hormone (TRH) increases activity and decreases food intake, body weight, and sleep, in part through hypothalamic actions. The mechanism of this action is unknown. Melanin-concentrating hormone (MCH) and hypocretin/orexin neurons in the lateral hypothalamus (LH) together with neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons in the arcuate nucleus play central roles in energy homeostasis. Here, we provide electrophysiological evidence from GFP-reporter transgenic mouse brain slices that shows TRH modulates the activity of MCH neurons. Using whole-cell current-clamp recording, we unexpectedly found that TRH and its agonist, montrelin, dose-dependently inhibited MCH neurons. Consistent with previous reports, TRH excited hypocretin/orexin neurons. No effect was observed on arcuate nucleus POMC or NPY neurons. The TRH inhibition of MCH neurons was eliminated by bicuculline and tetrodotoxin, suggesting that the effect was mediated indirectly through synaptic mechanisms. TRH increased spontaneous IPSC frequency without affecting amplitude and had no effect on miniature IPSCs or EPSCs. Immunocytochemistry revealed little interaction between TRH axons and MCH neurons, but showed TRH axons terminating on or near GABA neurons. TRH inhibition of MCH neurons was attenuated by Na(+)-Ca(2+) exchanger (NCX) inhibitors, TRPC channel blockers and the phospholipase C inhibitor U-73122. TRH excited LH GABA neurons, and this was also reduced by NCX inhibitors. Finally, TRH attenuated the excitation of MCH neurons by hypocretin. Together, our data suggest that TRH inhibits MCH neurons by increasing synaptic inhibition from local GABA neurons. Inhibition of MCH neurons may contribute to the TRH-mediated reduction in food intake and sleep.
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130
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Schulz C, Paulus K, Jöhren O, Lehnert H. Intranasal leptin reduces appetite and induces weight loss in rats with diet-induced obesity (DIO). Endocrinology 2012; 153:143-53. [PMID: 22128019 DOI: 10.1210/en.2011-1586] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Resistance to brain-mediated effects of leptin is a characteristic feature of obesity, resulting from alterations in leptin receptor signaling in hypothalamic neurons and/or transport across the blood-brain-barrier. We have shown previously, that the latter can be circumvented by intranasal (i.n.) application of leptin in lean rats. This prompted us to test i.n. leptin in animals with diet-induced obesity (DIO) as a basis for future human administration. DIO was induced in male Wistar rats by feeding a cafeteria diet for 25 or 32 wk, respectively. Consecutively, these DIO animals (seven to eight per treatment) and standard diet rats (lean) (14-15 per treatment, matched for age and diet duration) were treated with 0.1, 0.2 mg/kg leptin, or control solution i.n. daily for 4 wk before onset of dark period. Energy intake and body weight were measured daily; blood glucose, serum insulin, and leptin were measured before and after treatment. Expression of hypothalamic neuropeptides was assessed by quantitative real-time PCR. We demonstrate, for the first time, that i.n. leptin reduces appetite and induces weight loss in DIO to the same extent as in lean rats. Our findings are supported accordingly by an altered expression pattern of anorexigenic and orexigenic neuropeptides in the hypothalamus, e.g. proopiomelanocortin, cocaine and amphetamine-related transcript, neuropeptide Y, agouti-related protein. It now appears clear that i.n. leptin is effectively acting in obese animals in the same fashion as in their lean counterparts. These findings now clearly warrant studies in humans and may open new perspectives in the treatment of obesity.
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Affiliation(s)
- Carla Schulz
- Department of Internal Medicine I, Luebeck University, Ratzeburger Allee 160, 23538 Luebeck, Germany.
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131
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Croizier S, Amiot C, Chen X, Presse F, Nahon JL, Wu JY, Fellmann D, Risold PY. Development of posterior hypothalamic neurons enlightens a switch in the prosencephalic basic plan. PLoS One 2011; 6:e28574. [PMID: 22194855 PMCID: PMC3241628 DOI: 10.1371/journal.pone.0028574] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 11/10/2011] [Indexed: 12/24/2022] Open
Abstract
In rats and mice, ascending and descending axons from neurons producing melanin-concentrating hormone (MCH) reach the cerebral cortex and spinal cord. However, these ascending and descending projections originate from distinct sub-populations expressing or not “Cocaine-and-Amphetamine-Regulated-Transcript” (CART) peptide. Using a BrdU approach, MCH cell bodies are among the very first generated in the hypothalamus, within a longitudinal cell cord made of earliest delaminating neuroblasts in the diencephalon and extending from the chiasmatic region to the ventral midbrain. This region also specifically expresses the regulatory genes Sonic hedgehog (Shh) and Nkx2.2. First MCH axons run through the tractus postopticus (tpoc) which gathers pioneer axons from the cell cord and courses parallel to the Shh/Nkx2.2 expression domain. Subsequently generated MCH neurons and ascending MCH axons differentiate while neurogenesis and mantle layer differentiation are generalized in the prosencephalon, including telencephalon. Ascending MCH axons follow dopaminergic axons of the mesotelencephalic tract, both being an initial component of the medial forebrain bundle (mfb). Netrin1 and Slit2 proteins that are involved in the establishment of the tpoc and mfb, respectively attract or repulse MCH axons. We conclude that first generated MCH neurons develop in a diencephalic segment of a longitudinal Shh/Nkx2.2 domain. This region can be seen as a prosencephalic segment of a medial neurogenic column extending from the chiasmatic region through the ventral neural tube. However, as the telencephalon expends, it exerts a trophic action and the mfb expands, inducing a switch in the longitudinal axial organization of the prosencephalon.
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Affiliation(s)
- Sophie Croizier
- EA3922, Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France
- IFR133, Université de Franche-Comté, Besançon, France
| | - Clotilde Amiot
- EA3922, Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France
- IFR133, Université de Franche-Comté, Besançon, France
| | - Xiaoping Chen
- Department of Neurology, School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Françoise Presse
- UMR 6097 CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Université Nice-Sophia Antipolis, Valbonne, France
| | - Jean-Louis Nahon
- UMR 6097 CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Université Nice-Sophia Antipolis, Valbonne, France
| | - Jane Y. Wu
- Department of Neurology, School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Dominique Fellmann
- EA3922, Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France
- IFR133, Université de Franche-Comté, Besançon, France
| | - Pierre-Yves Risold
- EA3922, Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France
- IFR133, Université de Franche-Comté, Besançon, France
- * E-mail:
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132
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The acute effects of leptin require PI3K signaling in the hypothalamic ventral premammillary nucleus. J Neurosci 2011; 31:13147-56. [PMID: 21917798 DOI: 10.1523/jneurosci.2602-11.2011] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Evidence suggests that the role played by the adipocyte-derived hormone leptin in female reproductive physiology is mediated in part by neurons located within the ventral premammillary nucleus (PMV). Leptin activates PMV neurons; however, the intracellular signaling pathway and channel(s) involved remain undefined. Notably, leptin's excitatory and inhibitory effects within hypothalamic and brainstem nuclei share the intracellular signaling cascade phosphoinositide 3 kinase (PI3K). Therefore, we assessed whether PI3K signaling is required for the acute effect of leptin to alter cellular activity of PMV neurons that express leptin receptors (LepR PMV neurons). Leptin caused a rapid depolarization in the majority of LepR PMV neurons in patch-clamp recordings of hypothalamic slices, while a subset of LepR PMV neurons were hyperpolarized in response to leptin. Data were obtained from both male and female mice and results demonstrate that the acute effect of leptin on LepR PMV neurons was identical for both sexes. Pharmacological inhibition of PI3K prevented the acute leptin-induced change in neuronal activity of LepR PMV neurons, indicating a PI3K-dependent mechanism of leptin action. Similarly, mice with genetically disrupted PI3K signaling in LepR PMV neurons failed to alter cellular activity in response to leptin. Moreover, the leptin-induced depolarization was dependent on a putative TRPC channel. In contrast, the leptin-induced-hyperpolarization required the activation of a putative Katp channel. Collectively, these results suggest that PI3K signaling in LepR PMV neurons is essential for leptin-induced alteration in cellular activity, and these data may suggest a cellular correlate in which leptin contributes to the initiation of reproductive development.
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133
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Comparative distribution of cocaine- and amphetamine-regulated transcript (CART) in the hypothalamus of the capuchin monkey (Cebus apella) and the common marmoset (Callithrix jacchus). Brain Res 2011; 1425:47-61. [DOI: 10.1016/j.brainres.2011.09.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 08/27/2011] [Accepted: 09/10/2011] [Indexed: 11/17/2022]
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134
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Job MO, McNamara IM, Kuhar MJ. CART Peptides Regulate Psychostimulants and May be Endogenous Antidepressants. Curr Neuropharmacol 2011; 9:12-6. [PMID: 21886553 PMCID: PMC3137165 DOI: 10.2174/157015911795017074] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 04/17/2010] [Accepted: 05/26/2010] [Indexed: 11/22/2022] Open
Abstract
CART peptides are endogenous neurotransmitters that are involved in a variety of physiologic functions. Injection of CART 55-102 into the nucleus accumbens produces no effect, but when co-administered with cocaine, it reduces the locomotor and rewarding properties of cocaine. In a human study, subjects carrying a missense mutation of the CART gene exhibited increased anxiety and depression. Also, several animal studies support the idea that CART is involved in anxiety and depression, and they also suggest several possible mechanisms by which this may occur. Thus, there is interesting evidence that CART peptides play a role in anxiety and depression, and that CART peptides may be endogenous antidepressants.
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Affiliation(s)
- M O Job
- Yerkes National Primate Research Center of Emory University, 954 Gatewood Rd NE, Atlanta GA 30329, USA
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135
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Rodrigues BC, Cavalcante JC, Elias CF. Expression of cocaine- and amphetamine-regulated transcript in the rat forebrain during postnatal development. Neuroscience 2011; 195:201-14. [PMID: 21903152 DOI: 10.1016/j.neuroscience.2011.08.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 08/11/2011] [Accepted: 08/17/2011] [Indexed: 12/19/2022]
Abstract
Cocaine- and amphetamine-regulated transcript (CART) is widespread in the rodent brain. CART has been implicated in many different functions including reward, feeding, stress responses, sensory processing, learning and memory formation. Recent studies have suggested that CART may also play a role in neural development. Therefore, in the present study we compared the distribution pattern and levels of CART mRNA expression in the forebrain of male and female rats at different stages of postnatal development: P06, P26 and P66. At 6 days of age (P06), male and female rats showed increased CART expression in the somatosensory and piriform cortices, indusium griseum, dentate gyrus, nucleus accumbens, and ventral premammillary nucleus. Interestingly, we found a striking expression of CART mRNA in the ventral posteromedial and ventral posterolateral thalamic nuclei. This thalamic expression was absent at P26 and P66. Contrastingly, at P06 CART mRNA expression was decreased in the arcuate nucleus. Comparing sexes, we found increased CART mRNA expression in the anteroventral periventricular nucleus of adult females. In other regions including the CA1, the lateral hypothalamic area and the dorsomedial nucleus of the hypothalamus, CART expression was not different comparing postnatal ages and sexes. Our findings indicate that CART gene expression is induced in a distinct temporal and spatial manner in forebrain sites of male and female rats. They also suggest that CART peptide participate in the development of neural pathways related to selective functions including sensory processing, reward and memory formation.
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Affiliation(s)
- B C Rodrigues
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo - USP, São Paulo, SP 05508-900, Brazil
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136
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Wernette CM, White BD, Zizza CA. Signaling proteins that influence energy intake may affect unintentional weight loss in elderly persons. ACTA ACUST UNITED AC 2011; 111:864-73. [PMID: 21616199 DOI: 10.1016/j.jada.2011.03.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 12/08/2010] [Indexed: 11/25/2022]
Abstract
After age 70 to 75 years, average body weight decreases both in ailing and healthy people because of a loss of appetite that results in reduced energy intake and the loss of body fat and lean muscle tissue. This so-called anorexia of aging predisposes elderly people to continued pathologic weight loss and malnutrition-major causes of morbidity and mortality. Health care professionals must understand the many factors involved in the anorexia of aging to help older adults prevent unintentional weight loss. Psychological, social, and cultural factors are important effectors; however, physiological factors are emphasized here because they are not thoroughly understood and they make it inherently difficult for most people to alter their body weight. Monoamines, steroid hormones (glucocorticoids and mineralocorticoids), endocannabinoids, and proteins all influence body weight. This review is an analysis of proteins from the brain, pancreas, adipose tissue, and gastrointestinal tract that are known to affect energy intake and energy balance, with an attempt to identify those factors that may change with aging. The articles included in this review were obtained by a PubMed database search using the keywords mouse OR rat OR human AND aged OR aging OR older OR elderly AND adult AND anorexia OR "unintentional weight loss," and each of the individual proteins discussed, as well as from the reference lists of those articles. The results reveal that some proteins may be important in the development of unintentional weight loss in elderly persons, whereas others may not have a significant role. However, many of the proteins that could conceivably have a role in unintentional weight loss have not yet been studied with that question in mind. Preventing unintentional weight loss in older adults is an important goal and further research on the role of proteins important for the maintenance of energy balance and the development of unintentional weight loss in elderly persons is warranted.
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Affiliation(s)
- Catherine M Wernette
- Department of Nutrition, Dietetics, and Hospitality Management, Auburn University, Auburn, AL, USA.
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137
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Baroncini M, Jissendi P, Balland E, Besson P, Pruvo JP, Francke JP, Dewailly D, Blond S, Prevot V. MRI atlas of the human hypothalamus. Neuroimage 2011; 59:168-80. [PMID: 21777680 DOI: 10.1016/j.neuroimage.2011.07.013] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Revised: 06/24/2011] [Accepted: 07/04/2011] [Indexed: 10/18/2022] Open
Abstract
Gaining new insights into the anatomy of the human hypothalamus is crucial for the development of new treatment strategies involving functional stereotactic neurosurgery. Here, using anatomical comparisons between histology and magnetic resonance images of the human hypothalamus in the coronal plane, we show that discrete gray and white hypothalamic structures are consistently identifiable by MRI. Macroscopic and microscopic images were used to precisely annotate the MRI sequences realized in the coronal plane in twenty healthy volunteers. MRI was performed on a 1.5 T scanner, using a protocol including T1-weighted 3D fast field echo, T1-weighted inversion-recovery, turbo spin echo and T2-weighted 2D fast field echo imaging. For each gray matter structure as well as for white matter bundles, the different MRI sequences were analyzed in comparison to each other. The anterior commissure and the fornix were often identifiable, while the mammillothalamic tract was more difficult to spot. Qualitative analyses showed that MRI could also highlight finer structures such as the paraventricular nucleus, the ventromedial nucleus of the hypothalamus and the infundibular (arcuate) nucleus, brain nuclei that play key roles in the regulation of food intake and energy homeostasis. The posterior hypothalamic area, a target for deep brain stimulation in the treatment of cluster headaches, was readily identified, as was the lateral hypothalamic area, which similar to the aforementioned hypothalamic nuclei, could be a putative target for deep brain stimulation in the treatment of obesity. Finally, each of the identified structures was mapped to Montreal Neurological Institute (MNI) space.
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Affiliation(s)
- Marc Baroncini
- Inserm, Jean-Pierre Aubert Research Center, U837, Development and Plasticity of the postnatal Brain, Univ Lille Nord de France, CHRU Lille, Department of Neurosurgery, Lille University Hospital, 59037 Lille cedex, France.
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138
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Burt J, Alberto CO, Parsons MP, Hirasawa M. Local network regulation of orexin neurons in the lateral hypothalamus. Am J Physiol Regul Integr Comp Physiol 2011; 301:R572-80. [PMID: 21697524 DOI: 10.1152/ajpregu.00674.2010] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Obesity and inadequate sleep are among the most common causes of health problems in modern society. Thus, the discovery that orexin (hypocretin) neurons play a pivotal role in sleep/wake regulation, energy balance, and consummatory behaviors has sparked immense interest in understanding the regulatory mechanisms of these neurons. The local network consisting of neurons and astrocytes within the lateral hypothalamus and perifornical area (LH/PFA), where orexin neurons reside, shapes the output of orexin neurons and the LH/PFA. Orexin neurons not only send projections to remote brain areas but also contribute to the local network where they release multiple neurotransmitters to modulate its activity. These neurotransmitters have opposing actions, whose balance is determined by the amount released and postsynaptic receptor desensitization. Modulation and negative feedback regulation of excitatory glutamatergic inputs as well as release of astrocyte-derived factors, such as lactate and ATP, can also affect the excitability of orexin neurons. Furthermore, distinct populations of LH/PFA neurons express neurotransmitters with known electrophysiological actions on orexin neurons, such as melanin-concentrating hormone, corticotropin-releasing factor, thyrotropin-releasing hormone, neurotensin, and GABA. These LH/PFA-specific mechanisms may be important for fine tuning the firing activity of orexin neurons to maintain optimal levels of prolonged output to sustain wakefulness and stimulate consummatory behaviors. Building on these exciting findings should shed further light onto the cellular mechanisms of energy balance and sleep-wake regulation.
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Affiliation(s)
- Julia Burt
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, Newfoundland, Canada
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139
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Bittencourt JC. Anatomical organization of the melanin-concentrating hormone peptide family in the mammalian brain. Gen Comp Endocrinol 2011; 172:185-97. [PMID: 21463631 DOI: 10.1016/j.ygcen.2011.03.028] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 03/23/2011] [Accepted: 03/28/2011] [Indexed: 11/24/2022]
Abstract
More than 20 years ago, melanin-concentrating hormone (MCH) and its peptide family members - neuropeptide EI (NEI) and neuropeptide GE (NGE) - were described in various species, including mammals (rodents, humans, and non-human primates). Since then, most studies have focused on the role of MCH as an orexigenic peptide, as well as on its participation in learning, spatial memory, neuroendocrine control, and sleep. It has been shown that MCH mRNA or the neuropeptide MCH are present in neurons of the prosencephalon, hypothalamus and brainstem. However, most of the neurons containing MCH/NEI are within the incerto-hypothalamic and lateral hypothalamic areas. In addition, the terminals of those neurons are distributed widely throughout the central nervous system. In this review, we will discuss the relationship between those territories and the roles played by MCH/NEI, as well as the importance of MCH receptor 1 in the respective terminal fields. Certain neurochemical features of MCH- and NEI-immunoreactive (MCH-ir and NEI-ir) neurons will also be discussed. The overarching theme is the anatomical organization of an inhibitory neuropeptide colocalized with an inhibitory neurotransmitter in integrative territories of the central nervous system, such as the IHy and LHA. Although these territories have connections to few brain regions, the regions to which they are connected are relevant, being responsible for the organization of motivated behaviors. All available information on this peptidergic system (anatomical, neurochemical, hodological, physiological, pharmacological and behavioral data) suggests that MCH is intimately involved in arousal and the initiation of motivated behaviors.
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Affiliation(s)
- Jackson C Bittencourt
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, SP, Brazil.
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140
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Alkemade A, Friesema ECH, Kalsbeek A, Swaab DF, Visser TJ, Fliers E. Expression of thyroid hormone transporters in the human hypothalamus. J Clin Endocrinol Metab 2011; 96:E967-71. [PMID: 21508134 DOI: 10.1210/jc.2010-2750] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Transport of thyroid hormone across the plasma membrane is required for proper thyroid hormone action and metabolism. Several specific thyroid hormone transporters have been identified capable of facilitating uptake and/or efflux of thyroid hormones. Monocarboxylate transporter (MCT)-8, MCT10, and organic anion transporting polypeptide 1C1 (OATP1C1) are the best-characterized specific thyroid hormone transporters to date. OBJECTIVE Our earlier studies in the human hypothalamus have shown that MCT8 is present in neurons of the hypothalamic paraventricular nucleus (PVN) and infundibular nucleus (IFN) and in tanycytes. We hypothesized that also MCT10 and OATP1C1 are present in specific areas of the human hypothalamus. DESIGN We studied postmortem brain samples of patients with known serum thyroid hormone levels using immunocytochemistry to investigate the distribution of MCT10 and OATP1C1 in the hypothalamus. RESULTS We found strong neuronal MCT10 immunocytochemical staining in a number of hypothalamic nuclei, including the PVN, IFN, and supraoptic nucleus. Intense staining was also observed in neurons of the lateral hypothalamus including the perifornical area. OATP1C1 immunoreactivity was present in glial cells throughout the hypothalamus. In addition, staining was present in capillary walls and in neurons of the PVN, IFN, and supraoptic nucleus. CONCLUSION The strong expression of MCT10 and OATP1C1 in the human hypothalamus indicates a possible role in the regulation of the hypothalamus-pituitary-thyroid axis.
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Affiliation(s)
- Anneke Alkemade
- Academic Medical Center, University of Amsterdam, Department of Endocrinology and Metabolism, G2-136, 1105AZ Amsterdam, The Netherlands.
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141
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Leinninger GM. Lateral thinking about leptin: a review of leptin action via the lateral hypothalamus. Physiol Behav 2011; 104:572-81. [PMID: 21550356 DOI: 10.1016/j.physbeh.2011.04.060] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Revised: 04/19/2011] [Accepted: 04/28/2011] [Indexed: 12/30/2022]
Abstract
The lateral hypothalamic area (LHA) was initially described as a "feeding center" but we are now beginning to understand that the LHA contributes to other aspects of physiology as well. Indeed, the best-characterized neuronal populations of the LHA (which contain melanin-concentrating hormone (MCH) or the hypocretins/orexins (OX)) are not strictly orexigenic, but also have roles in regulation of the autonomic and sympathetic nervous systems as well as in modulating motivated behavior. Leptin is an anorectic hormone that regulates energy homeostasis and the mesolimbic DA system (which transduces the wanting of food, drugs of abuse, and sex) in part, via actions at the LHA. At least three populations of LHA neurons are regulated by leptin: those containing MCH, OX or the long form of the leptin receptor, LepRb. The emerging picture of leptin interaction with these LHA populations suggests that the LHA is not merely regulating feeding, but is a crucial integrator of energy balance and motivated behavior.
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Affiliation(s)
- Gina M Leinninger
- Division of Metabolism, Endocrinology and Diabetes, Department of Medicine, University of Michigan Medical School, 100 Wall Street, Ann Arbor, MI 48105, USA
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142
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Hypothalamic cocaine- and amphetamine-regulated transcript and corticotrophin releasing factor neurons are stimulated by extracellular volume and osmotic changes. Neuroscience 2011; 186:57-64. [PMID: 21539900 DOI: 10.1016/j.neuroscience.2011.04.047] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 04/19/2011] [Accepted: 04/20/2011] [Indexed: 11/22/2022]
Abstract
Several studies suggest that hypothalamic cocaine- and amphetamine-regulated transcript (CART) may interact with the hypothalamic-pituitary-adrenal (HPA) axis in the control of neuroendocrine function and may also participate in cardiovascular regulation. Therefore, this study aimed to evaluate, in experimental models of isotonic (I-EVE) and hypertonic (H-EVE) extracellular volume expansion and water deprivation (WD), the activation of CART- and corticotrophin releasing factor (CRF)-immunoreactive neurons, as well as the relative expression of CART and CRF mRNAs in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. Both H-EVE (0.30M NaCl, 2mL/100g of body weight, in 1 minute) and 24 hours of WD significantly increased plasma sodium concentrations, producing, respectively, either an increase or a decrease in extracellular volume. I-EVE (0.15M NaCl, 2mL/100g of body weight, in 1 minute) evoked a significant increase in the circulating volume accompanied by unaltered plasma concentrations of sodium. CART-expressing neurons of both magnocellular and parvocellular hypothalamic divisions were activated to produce Fos in response to H-EVE but not in response to I-EVE. Furthermore, increased expression of CART mRNA was found in the PVN of H-EVE but not I-EVE rats. These data show for the first time that EVE not only activates hypothalamic CRF neurons but also increases CRF mRNA expression in the PVN. In contrast, WD increases the number of CART-immunoreactive neurons activated to produce Fos in the PVN and SON but does not change the number of neurons double labeled for Fos and CRF or expression of CRF mRNA in the PVN. These findings provided new insights into the participation of CART in diverse processes within the PVN and SON, including its possible involvement in activation of the HPA axis and cardiovascular regulation in response to changes in extracellular volume and osmolality.
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143
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Remmers F, Delemarre-van de Waal HA. Developmental programming of energy balance and its hypothalamic regulation. Endocr Rev 2011; 32:272-311. [PMID: 21051592 DOI: 10.1210/er.2009-0028] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Developmental programming is an important physiological process that allows different phenotypes to originate from a single genotype. Through plasticity in early life, the developing organism can adopt a phenotype (within the limits of its genetic background) that is best suited to its expected environment. In humans, together with the relative irreversibility of the phenomenon, the low predictive value of the fetal environment for later conditions in affluent countries makes it a potential contributor to the obesity epidemic of recent decades. Here, we review the current evidence for developmental programming of energy balance. For a proper understanding of the subject, knowledge about energy balance is indispensable. Therefore, we first present an overview of the major hypothalamic routes through which energy balance is regulated and their ontogeny. With this background, we then turn to the available evidence for programming of energy balance by the early nutritional environment, in both man and rodent models. A wealth of studies suggest that energy balance can indeed be permanently affected by the early-life environment. However, the direction of the effects of programming appears to vary considerably, both between and within different animal models. Because of these inconsistencies, a comprehensive picture is still elusive. More standardization between studies seems essential to reach veritable conclusions about the role of developmental programming in adult energy balance and obesity.
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Affiliation(s)
- Floor Remmers
- Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Germany.
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144
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Torterolo P, Lagos P, Monti JM. Melanin-concentrating hormone: a new sleep factor? Front Neurol 2011; 2:14. [PMID: 21516258 PMCID: PMC3080035 DOI: 10.3389/fneur.2011.00014] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 03/02/2011] [Indexed: 12/18/2022] Open
Abstract
Neurons containing the neuropeptide melanin-concentrating hormone (MCH) are mainly located in the lateral hypothalamus and the incerto-hypothalamic area, and have widespread projections throughout the brain. While the biological functions of this neuropeptide are exerted in humans through two metabotropic receptors, the MCHR1 and MCHR2, only the MCHR1 is present in rodents. Recently, it has been shown that the MCHergic system is involved in the control of sleep. We can summarize the experimental findings as follows: (1) The areas related to the control of sleep and wakefulness have a high density of MCHergic fibers and receptors. (2) MCHergic neurons are active during sleep, especially during rapid eye movement (REM) sleep. (3) MCH knockout mice have less REM sleep, notably under conditions of negative energy balance. Animals with genetically inactivated MCHR1 also exhibit altered vigilance state architecture and sleep homeostasis. (4) Systemically administered MCHR1 antagonists reduce sleep. (5) Intraventricular microinjection of MCH increases both slow wave sleep (SWS) and REM sleep; however, the increment in REM sleep is more pronounced. (6) Microinjection of MCH into the dorsal raphe nucleus increases REM sleep time. REM seep is inhibited by immunoneutralization of MCH within this nucleus. (7) Microinjection of MCH in the nucleus pontis oralis of the cat enhances REM sleep time and reduces REM sleep latency. All these data strongly suggest that MCH has a potent role in the promotion of sleep. Although both SWS and REM sleep are facilitated by MCH, REM sleep seems to be more sensitive to MCH modulation.
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Affiliation(s)
- Pablo Torterolo
- Department of Physiology, School of Medicine, University of the Republic Montevideo, Uruguay
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145
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Krolewski DM, Medina A, Kerman IA, Bernard R, Burke S, Thompson RC, Bunney WE, Schatzberg AF, Myers RM, Akil H, Jones EG, Watson SJ. Expression patterns of corticotropin-releasing factor, arginine vasopressin, histidine decarboxylase, melanin-concentrating hormone, and orexin genes in the human hypothalamus. J Comp Neurol 2011; 518:4591-611. [PMID: 20886624 DOI: 10.1002/cne.22480] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The hypothalamus regulates numerous autonomic responses and behaviors. The neuroactive substances corticotropin-releasing factor (CRF), arginine-vasopressin (AVP), histidine decarboxylase (HDC), melanin-concentrating hormone (MCH), and orexin/hypocretins (ORX) produced in the hypothalamus mediate a subset of these processes. Although the expression patterns of these genes have been well studied in rodents, less is known about them in humans. We combined classical histological techniques with in situ hybridization histochemistry to produce both 2D and 3D images and to visually align and quantify expression of the genes for these substances in nuclei of the human hypothalamus. The hypothalamus was arbitrarily divided into rostral, intermediate, and caudal regions. The rostral region, containing the paraventricular nucleus (PVN), was defined by discrete localization of CRF- and AVP-expressing neurons, whereas distinct relationships between HDC, MCH, and ORX mRNA-expressing neurons delineated specific levels within the intermediate and caudal regions. Quantitative mRNA signal intensity measurements revealed no significant differences in overall CRF or AVP expression at any rostrocaudal level of the PVN. HDC mRNA expression was highest at the level of the premammillary area, which included the dorsomedial and tuberomammillary nuclei as well as the dorsolateral hypothalamic area. In addition, the overall intensity of hybridization signal exhibited by both MCH and ORX mRNA-expressing neurons peaked in distinct intermediate and caudal hypothalamic regions. These results suggest that human hypothalamic neurons involved in the regulation of the HPA axis display distinct neurochemical patterns that may encompass multiple local nuclei.
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Affiliation(s)
- David M Krolewski
- Molecular & Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, Michigan 48109, USA
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146
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Saper CB, Fuller PM, Pedersen NP, Lu J, Scammell TE. Sleep state switching. Neuron 2011; 68:1023-42. [PMID: 21172606 DOI: 10.1016/j.neuron.2010.11.032] [Citation(s) in RCA: 818] [Impact Index Per Article: 62.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2010] [Indexed: 12/27/2022]
Abstract
We take for granted the ability to fall asleep or to snap out of sleep into wakefulness, but these changes in behavioral state require specific switching mechanisms in the brain that allow well-defined state transitions. In this review, we examine the basic circuitry underlying the regulation of sleep and wakefulness and discuss a theoretical framework wherein the interactions between reciprocal neuronal circuits enable relatively rapid and complete state transitions. We also review how homeostatic, circadian, and allostatic drives help regulate sleep state switching and discuss how breakdown of the switching mechanism may contribute to sleep disorders such as narcolepsy.
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Affiliation(s)
- Clifford B Saper
- Department of Neurology, Program in Neuroscience, and Division of Sleep Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA.
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147
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Serrano A, Pavón FJ, Tovar S, Casanueva F, Señarís R, Diéguez C, de Fonseca FR. Oleoylethanolamide: effects on hypothalamic transmitters and gut peptides regulating food intake. Neuropharmacology 2010; 60:593-601. [PMID: 21172362 DOI: 10.1016/j.neuropharm.2010.12.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 11/09/2010] [Accepted: 12/12/2010] [Indexed: 10/18/2022]
Abstract
Recently, it has been described the role of fatty acid ethanolamides in the control of feeding behavior. Oleoylethanolamide (OEA) is a member of this family of lipid mediators regulating feeding. OEA acts suppressing feeding behavior through, at least partially, a peripheral mechanism. However, the interaction between this acylethanolamide and other orexigenic or anorexigenic mediators is mostly not well characterized. The aim of this study was to evaluate whether anorectic actions of OEA were mediated through the modulation of central and peripheral signals involved in the regulation of feeding. Experiments were performed in male Wistar rats under free-feeding and fasting conditions. We measured hypothalamic neuropeptides and monoamines by in situ hybridization and HPLC respectively as well as plasmatic levels of relevant endocrine signals. OEA administration induced changes in hypothalamic monoaminergic activity and in the anorexigenic neuropeptide CART expressed in the paraventricular nucleus (PVN) but lacked effect on neuropeptides expression in nucleus arcuatus. In addition, OEA induced peripheral changes in gut peptides, with marked effects on PYY and Ghrelin. These results further suggest that anorexigenic properties of OEA are mediated by peripheral signals and by central alterations in neuropeptides expressed by feeding-involved hypothalamic structures receiving input from peripheral sensory systems, such as the PVN.
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Affiliation(s)
- Antonia Serrano
- Fundación IMABIS, Hospital Carlos Haya de Málaga, Málaga, Spain.
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148
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Changes in key hypothalamic neuropeptide populations in Huntington disease revealed by neuropathological analyses. Acta Neuropathol 2010; 120:777-88. [PMID: 20821223 DOI: 10.1007/s00401-010-0742-6] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 08/19/2010] [Accepted: 08/21/2010] [Indexed: 10/19/2022]
Abstract
Huntington disease (HD) is a fatal neurodegenerative disorder caused by expansion of a CAG repeat in the HD gene. Degeneration concentrating in the basal ganglia has been thought to account for the characteristic psychiatric symptoms, cognitive decline and motor dysfunction. However, the homeostatic control of emotions and metabolism are disturbed early in HD, and focused studies have identified a loss of orexin (hypocretin) neurons in the lateral hypothalamus in HD patients. There has been limited assessment of other hypothalamic cell populations that may be involved. In this study, we quantified the neuropeptide-expressing hypothalamic neurons known to regulate metabolism and emotion in patients with HD compared to healthy controls using unbiased stereological methods. We confirmed the loss of orexin-expressing neurons in HD and revealed substantial differences in the peptide expression of other neuronal populations in the same patients. Both oxytocin- and vasopressin-expressing neurons were decreased by 45 and 24%, respectively, while the number of cocaine- and amphetamine-regulated transcript (CART)-expressing neurons was increased by 30%. The increased expression of CART in the hypothalamus is consistent with a previous study showing increased CART levels in cerebrospinal fluid from HD patients. There was no difference in the numbers of neuropeptide Y-expressing neurons. These results show significant and specific alterations in the peptide expression of hypothalamic neurons known to regulate metabolism and emotion. They may be important in the development of psychiatric symptoms and metabolic disturbances in HD, and may provide potential targets for therapeutic interventions.
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Cravo RM, Margatho LO, Osborne-Lawrence S, Donato J, Atkin S, Bookout AL, Rovinsky S, Frazão R, Lee CE, Gautron L, Zigman JM, Elias CF. Characterization of Kiss1 neurons using transgenic mouse models. Neuroscience 2010; 173:37-56. [PMID: 21093546 DOI: 10.1016/j.neuroscience.2010.11.022] [Citation(s) in RCA: 243] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 11/09/2010] [Accepted: 11/11/2010] [Indexed: 10/18/2022]
Abstract
Humans and mice with loss-of-function mutations of the genes encoding kisspeptins (Kiss1) or kisspeptin receptor (Kiss1r) are infertile due to hypogonadotropic hypogonadism. Within the hypothalamus, Kiss1 mRNA is expressed in the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (Arc). In order to better study the different populations of kisspeptin cells we generated Kiss1-Cre transgenic mice. We obtained one line with Cre activity specifically within Kiss1 neurons (line J2-4), as assessed by generating mice with Cre-dependent expression of green fluorescent protein or β-galactosidase. Also, we demonstrated Kiss1 expression in the cerebral cortex and confirmed previous data showing Kiss1 mRNA in the medial nucleus of amygdala and anterodorsal preoptic nucleus. Kiss1 neurons were more concentrated towards the caudal levels of the Arc and higher leptin-responsivity was observed in the most caudal population of Arc Kiss1 neurons. No evidence for direct action of leptin in AVPV Kiss1 neurons was observed. Melanocortin fibers innervated subsets of Kiss1 neurons of the preoptic area and Arc, and both populations expressed melanocortin receptors type 4 (MC4R). Specifically in the preoptic area, 18-28% of Kiss1 neurons expressed MC4R. In the Arc, 90% of Kiss1 neurons were glutamatergic, 50% of which also were GABAergic. In the AVPV, 20% of Kiss1 neurons were glutamatergic whereas 75% were GABAergic. The differences observed between the Kiss1 neurons in the preoptic area and the Arc likely represent neuronal evidence for their differential roles in metabolism and reproduction.
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Affiliation(s)
- R M Cravo
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard Dallas, TX, USA
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150
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Janzsó G, Valcz G, Thuma A, Szoke B, Lendvai Z, Abrahám H, Kozicz T, Halasy K. Cocaine- and amphetamine-regulated transcript (CART) peptide-immunopositive neuronal elements in the lateral septum: rostrocaudal distribution in the male rat. Brain Res 2010; 1362:40-7. [PMID: 20883668 DOI: 10.1016/j.brainres.2010.09.079] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Revised: 09/07/2010] [Accepted: 09/22/2010] [Indexed: 11/26/2022]
Abstract
The morphological features and distribution of cocaine- and amphetamine-regulated transcript peptide immunoreactivity (CART-IR) were studied in the lateral septum (LS) of male rats using light and electron microscopic immunocytochemistry and computer-aided densitometry. CART-IR was detected along the rostrocaudal axis of the LS in varicose axonal fibers only, although immunoreactive cell bodies and dendrites were not detected. Pericellular basket-like arrangements around immunonegative cell bodies were present. From among the targets of such pericellular baskets, glutamic acid decarboxylase (GAD)-immunopositive and NPY-immunoreactive somata were identified. Thin varicose axons were present in each section, whereas thick varicose axons were restricted to the sections of rostral position only. CART-IR was observed in varicose fibers forming a dense subependymal plexus, from which solitary varicose fibers entered the ependymal layer. The fine structure of varicosities was similar to that of other neuropeptide-containing fibers. Small varicosities established asymmetrical synaptic contacts mainly with dendrites and dendritic spines, and larger varicosities established symmetrical synapses with somata and dendritic shafts. CART-to-CART connections were not revealed. The density curve of the CART-IR along the rostrocaudal axis of LS was found to be paraboloid. CART is known as one of the most anorexigenic peptides. These results serve as basis for further physiological studies concerning the biological significance of lateral septal CART peptide in the regulation of food intake.
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Affiliation(s)
- Gergely Janzsó
- Department of Anatomy and Histology, Faculty of Veterinary Sciences, Szent István University, Budapest, Hungary
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