1
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Alcantara IC, Tapia APM, Aponte Y, Krashes MJ. Acts of appetite: neural circuits governing the appetitive, consummatory, and terminating phases of feeding. Nat Metab 2022; 4:836-847. [PMID: 35879462 PMCID: PMC10852214 DOI: 10.1038/s42255-022-00611-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 06/16/2022] [Indexed: 12/11/2022]
Abstract
The overconsumption of highly caloric and palatable foods has caused a surge in obesity rates in the past half century, thereby posing a healthcare challenge due to the array of comorbidities linked to heightened body fat accrual. Developing treatments to manage body weight requires a grasp of the neurobiological basis of appetite. In this Review, we discuss advances in neuroscience that have identified brain regions and neural circuits that coordinate distinct phases of eating: food procurement, food consumption, and meal termination. While pioneering work identified several hypothalamic nuclei to be involved in feeding, more recent studies have explored how neuronal populations beyond the hypothalamus, such as the mesolimbic pathway and nodes in the hindbrain, interconnect to modulate appetite. We also examine how long-term exposure to a calorically dense diet rewires feeding circuits and alters the response of motivational systems to food. Understanding how the nervous system regulates eating behaviour will bolster the development of medical strategies that will help individuals to maintain a healthy body weight.
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Affiliation(s)
- Ivan C Alcantara
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, MD, USA
- Department of Neuroscience, Brown University, Providence, RI, USA
| | | | - Yeka Aponte
- National Institute on Drug Abuse (NIDA), National Institutes of Health, Baltimore, MD, USA.
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Michael J Krashes
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, MD, USA.
- National Institute on Drug Abuse (NIDA), National Institutes of Health, Baltimore, MD, USA.
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2
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Urstadt KR, Berridge KC. Optogenetic mapping of feeding and self-stimulation within the lateral hypothalamus of the rat. PLoS One 2020; 15:e0224301. [PMID: 31986148 PMCID: PMC6984703 DOI: 10.1371/journal.pone.0224301] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/27/2019] [Indexed: 11/18/2022] Open
Abstract
The lateral hypothalamus (LH) includes several anatomical subregions involved in eating and reward motivation. This study explored localization of function across different LH subregions in controlling food intake stimulated by optogenetic channelrhodopsin excitation, and in supporting laser self-stimulation. We particularly compared the tuberal LH subregion, the posterior LH subregion, and the lateral preoptic area. Local diameters of tissue optogenetically stimulated within the LH were assessed by measuring laser-induced Fos plumes and Jun plumes via immunofluorescence surrounding optic fiber tips. Those plume diameters were used to map localization of function for behavioral effects elicited by LH optogenetic stimulation. Optogenetic stimulation of the tuberal subsection of the LH produced the most robust eating behavior and food intake initially, but produced only mild laser self-stimulation in the same rats. However, after repeated exposures to optogenetic stimulation, tuberal LH behavioral profiles shifted toward more self-stimulation and less food intake. By contrast, stimulation of the lateral preoptic area produced relatively little food intake or self-stimulation, either initially or after extended stimulation experience. Stimulation in the posterior LH subregion supported moderate self-stimulation, but not food intake, and at higher laser intensity shifted valence to evoke escape behaviors. We conclude that the tuberal LH subregion may best mediate stimulation-bound increases in food intake stimulated by optogenetic excitation. However, incentive motivational effects of tuberal LH stimulation may shift toward self-stimulation behavior after repeated stimulation. By contrast, the lateral preoptic area and posterior LH do not as readily elicit either eating behavior or laser self-stimulation, and may be more prone to higher-intensity aversive effects.
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Affiliation(s)
- Kevin R. Urstadt
- Psychology Dept., University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
| | - Kent C. Berridge
- Psychology Dept., University of Michigan, Ann Arbor, Michigan, United States of America
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3
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Kardos J, Dobolyi Á, Szabó Z, Simon Á, Lourmet G, Palkovits M, Héja L. Molecular Plasticity of the Nucleus Accumbens Revisited-Astrocytic Waves Shall Rise. Mol Neurobiol 2019; 56:7950-7965. [PMID: 31134458 PMCID: PMC6834761 DOI: 10.1007/s12035-019-1641-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 05/06/2019] [Indexed: 12/11/2022]
Abstract
Part of the ventral striatal division, the nucleus accumbens (NAc) drives the circuit activity of an entire macrosystem about reward like a "flagship," signaling and leading diverse conducts. Accordingly, NAc neurons feature complex inhibitory phenotypes that assemble to process circuit inputs and generate outputs by exploiting specific arrays of opposite and/or parallel neurotransmitters, neuromodulatory peptides. The resulting complex combinations enable versatile yet specific forms of accumbal circuit plasticity, including maladaptive behaviors. Although reward signaling and behavior are elaborately linked to neuronal circuit activities, it is plausible to propose whether these neuronal ensembles and synaptic islands can be directly controlled by astrocytes, a powerful modulator of neuronal activity. Pioneering studies showed that astrocytes in the NAc sense citrate cycle metabolites and/or ATP and may induce recurrent activation. We argue that the astrocytic calcium, GABA, and Glu signaling and altered sodium and chloride dynamics fundamentally shape metaplasticity by providing active regulatory roles in the synapse- and network-level flexibility of the NAc.
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Affiliation(s)
- Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary.
| | - Árpád Dobolyi
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Üllői út 26, Budapest, 1086, Hungary
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Eötvös Loránd University and the Hungarian Academy of Sciences, Pázmány Péter sétány 1C, Budapest, 1117, Hungary
| | - Zsolt Szabó
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Ágnes Simon
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Guillaume Lourmet
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Üllői út 26, Budapest, 1086, Hungary
| | - Miklós Palkovits
- Human Brain Tissue Bank, Semmelweis University, Tűzoltó utca 58, Budapest, H-1094, Hungary
| | - László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
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4
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Diehl MM, Bravo-Rivera C, Rodriguez-Romaguera J, Pagan-Rivera PA, Burgos-Robles A, Roman-Ortiz C, Quirk GJ. Active avoidance requires inhibitory signaling in the rodent prelimbic prefrontal cortex. eLife 2018; 7:34657. [PMID: 29851381 PMCID: PMC5980229 DOI: 10.7554/elife.34657] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 05/06/2018] [Indexed: 12/27/2022] Open
Abstract
Much is known about the neural circuits of conditioned fear and its relevance to understanding anxiety disorders, but less is known about other anxiety-related behaviors such as active avoidance. Using a tone-signaled, platform-mediated avoidance task, we observed that pharmacological inactivation of the prelimbic prefrontal cortex (PL) delayed avoidance. Surprisingly, optogenetic silencing of PL glutamatergic neurons did not delay avoidance. Consistent with this, inhibitory but not excitatory responses of rostral PL neurons were associated with avoidance training. To test the importance of these inhibitory responses, we optogenetically stimulated PL neurons to counteract the tone-elicited reduction in firing rate. Photoactivation of rostral (but not caudal) PL neurons at 4 Hz impaired avoidance. These findings suggest that inhibitory responses of rostral PL neurons signal the avoidability of a potential threat and underscore the importance of designing behavioral optogenetic studies based on neuronal firing responses.
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Affiliation(s)
- Maria M Diehl
- Department of Psychiatry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico.,Department of Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Christian Bravo-Rivera
- Department of Psychiatry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico.,Department of Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Jose Rodriguez-Romaguera
- Department of Psychiatry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico.,Department of Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Pablo A Pagan-Rivera
- Department of Psychiatry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico.,Department of Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Anthony Burgos-Robles
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Ciorana Roman-Ortiz
- Department of Psychiatry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico.,Department of Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Gregory J Quirk
- Department of Psychiatry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico.,Department of Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
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5
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Do-Monte FH, Minier-Toribio A, Quiñones-Laracuente K, Medina-Colón EM, Quirk GJ. Thalamic Regulation of Sucrose Seeking during Unexpected Reward Omission. Neuron 2017; 94:388-400.e4. [PMID: 28426970 DOI: 10.1016/j.neuron.2017.03.036] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 02/02/2017] [Accepted: 03/27/2017] [Indexed: 01/05/2023]
Abstract
The paraventricular nucleus of the thalamus (PVT) is thought to regulate behavioral responses under emotionally arousing conditions. Reward-associated cues activate PVT neurons; however, the specific PVT efferents regulating reward seeking remain elusive. Using a cued sucrose-seeking task, we manipulated PVT activity under two emotionally distinct conditions: (1) when reward was available during the cue as expected or (2) when reward was unexpectedly omitted during the cue. Pharmacological inactivation of the anterior PVT (aPVT), but not the posterior PVT, increased sucrose seeking only when reward was omitted. Consistent with this, photoactivation of aPVT neurons abolished sucrose seeking, and the firing of aPVT neurons differentiated reward availability. Photoinhibition of aPVT projections to the nucleus accumbens or to the amygdala increased or decreased, respectively, sucrose seeking only when reward was omitted. Our findings suggest that PVT bidirectionally modulates sucrose seeking under the negative (frustrative) conditions of reward omission.
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Affiliation(s)
- Fabricio H Do-Monte
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, PO Box 365067, San Juan 00936, Puerto Rico.
| | - Angélica Minier-Toribio
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, PO Box 365067, San Juan 00936, Puerto Rico
| | - Kelvin Quiñones-Laracuente
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, PO Box 365067, San Juan 00936, Puerto Rico
| | - Estefanía M Medina-Colón
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, PO Box 365067, San Juan 00936, Puerto Rico
| | - Gregory J Quirk
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, PO Box 365067, San Juan 00936, Puerto Rico
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6
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Calderón N, Betancourt L, Hernández L, Rada P. A ketogenic diet modifies glutamate, gamma-aminobutyric acid and agmatine levels in the hippocampus of rats: A microdialysis study. Neurosci Lett 2017; 642:158-162. [PMID: 28189745 DOI: 10.1016/j.neulet.2017.02.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 01/17/2017] [Accepted: 02/07/2017] [Indexed: 11/26/2022]
Abstract
The ketogenic diet (KD) is acknowledged as an unconventional option in the treatment of epilepsy. Several lines of investigation point to a possible role of glutamate and gamma-aminobutyric acid (GABA) as main contributors in this protective effect. Other biomolecules could also be involved in the beneficial consequence of the KD, for example, the diamine agmatine has been suggested to block imidazole and glutamate NMDA receptor and serves as an endogenous anticonvulsant in different animal models of epilepsy. In the present report, we have used microdialysis coupled to capillary electrophoresis to monitor microdialysate levels of GABA, glutamate and agmatine in the hippocampus of rats submitted to a KD for 15days compared to rats on a normal rat chow diet. A significant increase in GABA and agmatine levels while no change in glutamate levels was observed. These results support the notion that the KD modifies different transmitters favoring inhibitory over excitatory neurotransmitters.
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Affiliation(s)
- Naima Calderón
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, 5101-A, Venezuela
| | - Luis Betancourt
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, 5101-A, Venezuela
| | - Luis Hernández
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, 5101-A, Venezuela
| | - Pedro Rada
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, 5101-A, Venezuela.
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7
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Sánchez-Fuentes A, Marichal-Cancino BA, Méndez-Díaz M, Becerril-Meléndez AL, Ruiz-Contreras AE, Prospéro-Garcia O. mGluR1/5 activation in the lateral hypothalamus increases food intake via the endocannabinoid system. Neurosci Lett 2016; 631:104-108. [PMID: 27542344 DOI: 10.1016/j.neulet.2016.08.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/14/2016] [Accepted: 08/13/2016] [Indexed: 11/17/2022]
Abstract
Mounting evidence has shown that glutamatergic and endocannabinoid systems in the hypothalamus regulate mammalian food intake. Stimulation of hypothalamic mGluR1/5 and CB1 receptors induces hyperphagia suggesting a possible interaction between these systems to control food intake. In addition, synthesis of endocannabinoids has been reported after mGluR1/5 stimulation in the brain. The aim of this study was to examine the potential cannabinergic activity in the food intake induction by lateral hypothalamic stimulation of mGluR1/5. Wistar albino male rats received bilateral infusions in the lateral hypothalamus (LH) of: (i) vehicle; (ii) (RS)-2-Chloro-5-hidroxyphenylglycine (CHPG; mGluR1/5 agonist); (iii) 2-AG (CB1 endogenous agonist); (iv) AM251 (CB1 antagonist); (v) tetrahydrolipstatin (THL, 1.2μg; diacyl-glycerol lipase inhibitor); and (vi) combinations of CHPG + with the other aforementioned drugs. Food intake was evaluated the first two hours after drug administration. CHPG significantly increased food intake; whereas CHPG in combination with a dose of 2-AG (with no effects on food intake) greatly increased food ingestion compared to CHPG alone. The increase induced by CHPG in food intake was prevented with AM251 or THL. These results suggest that activation of mGluR1/5 in the lateral hypothalamus induces an orexigenic effect via activation of the endocannabinoid system.
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Affiliation(s)
- Asai Sánchez-Fuentes
- Grupo de Neurociencias, Laboratorio de Cannabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Bruno A Marichal-Cancino
- Grupo de Neurociencias, Laboratorio de Cannabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Mónica Méndez-Díaz
- Grupo de Neurociencias, Laboratorio de Cannabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Alline L Becerril-Meléndez
- Grupo de Neurociencias, Laboratorio de Cannabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Alejandra E Ruiz-Contreras
- Lab. Neurogenomica Cognitiva, Coord. Psicobiología y Neurociencias, Fac. Psicologia, Universidad Nacional Autónoma de México, México D.F., Mexico
| | - Oscar Prospéro-Garcia
- Grupo de Neurociencias, Laboratorio de Cannabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
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8
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Murakami G, Nakamura M, Takita M, Ishida Y, Ueki T, Nakahara D. Brain Rewarding Stimulation Reduces Extracellular Glutamate Through Glial Modulation in Medial Prefrontal Cortex of Rats. Neuropsychopharmacology 2015; 40:2686-95. [PMID: 25924203 PMCID: PMC4864644 DOI: 10.1038/npp.2015.115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 03/16/2015] [Accepted: 03/24/2015] [Indexed: 12/29/2022]
Abstract
Growing evidence implicates a critical involvement of prefrontal glial modulation of extracellular glutamate (GLU) in aversive behaviors. However, nothing is known about whether prefrontal glial cells modulate GLU levels in rewarding behaviors. To address this question, we measured GLU efflux in the medial prefrontal cortex (PFC) of rats associated with rewarding behaviors. We used intracranial self-stimulation (ICSS) of the medial forebrain bundle (MFB) as the rewarding behavior. GLU was indirectly measured using microdialysis combined with on-line fluorometric detection of NADH resulting from the reaction of GLU and NAD(+) catalyzed by GLU dehydrogenase with a time resolution of 1 min. ICSS caused a minute-by-minute change of extracellular GLU in the medial PFC, with a slight decrease during the stimulation, followed by an increase afterward. This bidirectional change was tetrodotoxin insensitive and abolished by the gliotoxin fluorocitrate. To confirm and extend the previous studies of aversion-induced increase of extracellular GLU in the medial PFC, we also measured prefrontal GLU efflux associated with an aversive stimulation, immobilization stress. The temporal change in extracellular GLU caused by this stress was markedly different from that observed during ICSS. A rapid increase in GLU was detected during the aversive stimulation, followed by a large increase afterward. This bimodal change was tetrodotoxin insensitive, similar to that detected for ICSS. These findings indicate a bidirectional regulation of extracellular GLU by prefrontal glial cells associated with rat ICSS behavior, and reveal that glial modulation of GLU neurochemistry in the medial PFC contributes to rewarding as well as aversive behaviors in rats.
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Affiliation(s)
- Gen Murakami
- Division of Psychology and Behavioral Neuroscience, Department of Integrated Human Sciences, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Masato Nakamura
- Division of Psychology and Behavioral Neuroscience, Department of Integrated Human Sciences, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Masatoshi Takita
- Cognition and Action Research Group, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Yasushi Ishida
- Department of Psychiatry, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Takatoshi Ueki
- Department of Anatomy and Cell Biology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
- Department of Biofunctional Imaging, Medical Photonics Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Daiichiro Nakahara
- Division of Psychology and Behavioral Neuroscience, Department of Integrated Human Sciences, Hamamatsu University School of Medicine, Hamamatsu, Japan
- Department of Biofunctional Imaging, Medical Photonics Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
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9
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Urstadt KR, Stanley BG. Direct hypothalamic and indirect trans-pallidal, trans-thalamic, or trans-septal control of accumbens signaling and their roles in food intake. Front Syst Neurosci 2015; 9:8. [PMID: 25741246 PMCID: PMC4327307 DOI: 10.3389/fnsys.2015.00008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 01/15/2015] [Indexed: 01/01/2023] Open
Abstract
Due in part to the increasing incidence of obesity in developed nations, recent research aims to elucidate neural circuits that motivate humans to overeat. Earlier research has described how the nucleus accumbens shell (AcbSh) motivates organisms to feed by activating neuronal populations in the lateral hypothalamus (LH). However, more recent research suggests that the LH may in turn communicate with the AcbSh, both directly and indirectly, to re-tune the motivation to consume foods with homeostatic and food-related sensory signals. Here, we discuss the functional and anatomical evidence for an LH to AcbSh connection and its role in eating behaviors. The LH appears to modulate Acb activity directly, using neurotransmitters such as hypocretin/orexin or melanin concentrating hormone (MCH). The LH also indirectly regulates AcbSh activity through certain subcortical "relay" regions, such as the lateral septum (LS), ventral pallidum (VP), and paraventricular thalamus, using a variety of neurotransmitters. This review aims to summarize studies on these topics and outline a model by which LH circuits processing energy balance can modulate AcbSh neural activity to regulate feeding behavior.
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Affiliation(s)
- Kevin R Urstadt
- Department of Psychology, University of Michigan Ann Arbor, MI, USA
| | - B Glenn Stanley
- Departments of Psychology and Cell Biology and Neuroscience, University of California - Riverside Riverside, CA, USA
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10
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Wakabayashi KT, Myal SE, Kiyatkin EA. Fluctuations in nucleus accumbens extracellular glutamate and glucose during motivated glucose-drinking behavior: dissecting the neurochemistry of reward. J Neurochem 2015; 132:327-41. [PMID: 25393775 DOI: 10.1111/jnc.12993] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/17/2014] [Accepted: 11/10/2014] [Indexed: 12/21/2022]
Abstract
While motivated behavior involves multiple neurochemical systems, few studies have focused on the role of glutamate, the brain's excitatory neurotransmitter, and glucose, the energetic substrate of neural activity in reward-related neural processes. Here, we used high-speed amperometry with enzyme-based substrate-sensitive and control, enzyme-free biosensors to examine second-scale fluctuations in the extracellular levels of these substances in the nucleus accumbens shell during glucose-drinking behavior in trained rats. Glutamate rose rapidly after the presentation of a glucose-containing cup and before the initiation of drinking (reward seeking), decreased more slowly to levels below baseline during consumption (sensory reward), and returned to baseline when the ingested glucose reached the brain (metabolic reward). When water was substituted for glucose, glutamate rapidly increased with cup presentation and in contrast to glucose drinking, increased above baseline after rats tasted the water and refused to drink further. Therefore, extracellular glutamate show distinct changes associated with key events of motivated drinking behavior and opposite dynamics during sensory and metabolic components of reward. In contrast to glutamate, glucose increased at each stimulus and behavioral event, showing a sustained elevation during the entire behavior and a robust post-ingestion rise that correlated with the gradual return of glutamate levels to their baseline. By comparing active drinking with passive intra-gastric glucose delivery, we revealed that fluctuations in extracellular glucose are highly dynamic, reflecting a balance between rapid delivery because of neural activity, intense metabolism, and the influence of ingested glucose reaching the brain.
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Affiliation(s)
- Ken T Wakabayashi
- In-Vivo Electrophysiology Unit, Behavioral Neuroscience Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, DHHS, Baltimore, Maryland, USA
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11
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Charles JR, Hernandez E, Winter A, Yang CR, Stanley BG. Site selective activation of lateral hypothalamic mGluR1 and R5 receptors elicits feeding in rats. Physiol Behav 2014; 139:261-6. [PMID: 25449406 DOI: 10.1016/j.physbeh.2014.10.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 10/17/2014] [Accepted: 10/20/2014] [Indexed: 12/26/2022]
Abstract
Recent findings from our lab indicate that metabotropic glutamate receptor (mGluR) activation elicits eating, and the goal of the current study was to specify whether the lateral hypothalamus (LH) is the actual brain site mediating this effect. To examine this issue we injected the selective mGluR group I agonist (S)-3,5-dihydroxyphenylglycine (DHPG) unilaterally into the LH and surrounding regions (n=5-8 subjects/brain site) of satiated adult male Sprague-Dawley rats and measured elicited feeding. We determined that 1.0 nmol elicited food intake only within the LH. Increasing the dose to 10 or 25 nmol produced a more sustained effect in the LH, and also elicited eating in several other brain sites. These results, demonstrating that the LH mediates the eating elicited by low doses of DHPG, suggest that the LH may contain mGluR whose activation can produce eating behavior.
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Affiliation(s)
- J R Charles
- Department of Cell Biology and Neuroscience, University of California, Riverside, 900 University Ave., Riverside, CA 92521, USA.
| | - E Hernandez
- Department of Cell Biology and Neuroscience, University of California, Riverside, 900 University Ave., Riverside, CA 92521, USA
| | - A Winter
- Department of Cell Biology and Neuroscience, University of California, Riverside, 900 University Ave., Riverside, CA 92521, USA
| | - C R Yang
- Eli Lilly & Co., Lilly Corporate Center, Indianapolis, IN 46285, USA
| | - B G Stanley
- Department of Cell Biology and Neuroscience, University of California, Riverside, 900 University Ave., Riverside, CA 92521, USA; Department of Psychology, University of California, Riverside, 900 University Ave., Riverside, CA 92521, USA
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12
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Activation of lateral hypothalamic mGlu1 and mGlu5 receptors elicits feeding in rats. Neuropharmacology 2013; 79:59-65. [PMID: 24219858 DOI: 10.1016/j.neuropharm.2013.10.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 10/21/2013] [Accepted: 10/29/2013] [Indexed: 11/20/2022]
Abstract
Metabotropic glutamate receptors (mGluRs) have been popular drug targets for a variety of central nervous system (CNS) disease models, ranging from seizures to schizophrenia. The current study aimed to determine whether mGluRs participate in lateral hypothalamic (LH) stimulation of feeding. To this end, we used satiated adult male Sprague-Dawley rats stereotaxically implanted with indwelling bilateral LH guide cannulas to determine if injection of (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD), a broad mGluR group I and II agonist, would elicit feeding. Administration of 100 nmol ACPD induced feeding with a short latency. Similarly, unilateral LH injection of the selective mGluR group I agonist (S)-3,5-dihydroxyphenylglycine (DHPG) elicited significant feeding beginning 60 min postinjection and continuing until 4 h postinjection. Administration of the mGluR5 agonist, (RS)-2-chloro-5-hydroxyphenylglycine (CHPG) produced a smaller delayed feeding response. These delayed but prolonged eating responses suggest that activation of LH mGluR1 and/or mGluR5 might be sufficient to elicit feeding. To determine which subtypes were involved, LH DHPG injections were preceded by LH injection of either the group I antagonist n-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC), the mGluR1 antagonist 6-amino-n-cyclohexyl-n,3-dimethylthiazolo[3,2-a]benzimi dazole-2-carboxamide hydrochloride (YM-298198) or the mGluR5 antagonist 3-((2-methyl-4-thiazolyl)ethynyl)pyridine (MTEP), and food intake was measured. PHCCC blocked DHPG-elicited feeding, and each of the other antagonists produced significant feeding suppression. These findings suggest roles for mGluR1 and/or mGluR5 in lateral hypothalamic circuits capable of stimulating feeding behavior.
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Guyenet SJ, Matsen ME, Morton GJ, Kaiyala KJ, Schwartz MW. Rapid glutamate release in the mediobasal hypothalamus accompanies feeding and is exaggerated by an obesogenic food. Mol Metab 2013; 2:116-22. [PMID: 24199157 DOI: 10.1016/j.molmet.2013.02.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 02/02/2013] [Accepted: 02/04/2013] [Indexed: 10/27/2022] Open
Abstract
The mediobasal hypothalamus (MBH) plays a central role in the regulation of food intake and energy balance. Although the excitatory neurotransmitter glutamate is implicated in energy balance regulation by the MBH, the hypothesis that feeding elicits local glutamate release remains untested. To test this hypothesis, we employed a glutamate biosensor that measures glutamate concentrations at 1-s intervals in conscious, freely behaving rats. Results indicate that feeding is associated with an increase of MBH glutamate concentration that occurs within 1-2 s of oral contact with a food pellet, and the glutamate response to a palatable high-fat pellet is greatly exaggerated relative to chow. In contrast, glutamate responses were not observed during water ingestion or other observed behaviors. These findings indicate that feeding is associated with rapid release of glutamate in the MBH, that this release is exaggerated with an obesogenic food, and that this response is likely stimulated by orosensory factors.
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Affiliation(s)
- Stephan J Guyenet
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, UW Medicine at South Lake Union, 850 Republican Street, Box 358055, Seattle, WA 98109, USA
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14
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Stratford TR, Wirtshafter D. Injections of muscimol into the paraventricular thalamic nucleus, but not mediodorsal thalamic nuclei, induce feeding in rats. Brain Res 2012; 1490:128-33. [PMID: 23111346 DOI: 10.1016/j.brainres.2012.10.043] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 10/18/2012] [Accepted: 10/20/2012] [Indexed: 12/31/2022]
Abstract
The paraventricular thalamic nucleus (PVT) is a component of the midline thalamic group that is interconnected with several brain regions known to play important roles in the control of food intake, including the lateral hypothalamus and nucleus accumbens shell, suggesting that the PVT itself may be involved in mediating feeding behavior. In the current study, we examined whether inhibition of cells in the PVT with the GABA(A) agonist muscimol could alter food intake in non-deprived rats. To control for possible spread of the drug, we also observed food intake after injections of muscimol into the overlying ventricle or laterally adjacent mediodorsal thalamic nuclei (MD). We found that muscimol injections into the central PVT dose-dependently increased food intake. In contrast, intra-MD injections of muscimol resulted in a potent dose-dependent suppression of food intake, while those into the overlying ventricle had no effect. These results support the proposal that the PVT is a component of the neural circuitry controlling feeding behavior.
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Affiliation(s)
- Thomas R Stratford
- Laboratory of Integrative Neuroscience and Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607-7137, USA.
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15
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Terán Y, Ponce O, Betancourt L, Hernández L, Rada P. Amino acid profile of plasma and cerebrospinal fluid in preeclampsia. Pregnancy Hypertens 2012; 2:416-22. [PMID: 26105613 DOI: 10.1016/j.preghy.2012.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 03/26/2012] [Accepted: 05/06/2012] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To determine patterns in amino acids (arginine, GABA, glutamate and glutamine) and the diamine (agmatine) in plasma and cerebrospinal fluid (CSF) of mild and severe preeclampsia compared to control patients, using capillary zone electrophoresis to generate methods for refining diagnosis and prognosis and shed light on the pathophysiological mechanisms of preeclampsia. STUDY DESIGN This is an observational case-control study in pregnant women that attended the emergency ward of the University Hospital, Mérida, Venezuela, during the period April, 2009-April 2010. MAIN OUTCOME MEASURES Molar concentration of amino acids and diamine in plasma and CSF in control, mild and severe preeclampsia patients. RESULTS An increase in glutamate plasma levels was observed in mild preeclampsia and even higher in severe patients, while a biphasic response occurred in the CSF samples with a significant increment in mild preeclampsia patients and a decrease in severe preeclampsia patients. GABA significantly decreased both in plasma and CSF in mild preeclampsia with a tendency to return to normal levels in severe preeclampsia patients. Arginine CSF and plasma levels decreased in mild preeclampsia patients and even more in severe preeclampsia while agmatine significantly increased in plasma levels with no changes in CSF. CONCLUSIONS The results are discussed in terms of molecules that could be used as biomarkers of the severity of the disease and the possible involvement of these substances in the pathophysiology of preeclampsia.
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Affiliation(s)
- Yurbi Terán
- Obstetrics and Gynecology Unit, University of Los Andes Hospital, Mérida, Venezuela
| | - Ormelys Ponce
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, Venezuela
| | - Luis Betancourt
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, Venezuela
| | - Luis Hernández
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, Venezuela
| | - Pedro Rada
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, Venezuela.
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16
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Betancourt L, Rada P, Paredes D, Hernández L. In vivo monitoring of cerebral agmatine by microdialysis and capillary electrophoresis. J Chromatogr B Analyt Technol Biomed Life Sci 2012; 880:58-65. [DOI: 10.1016/j.jchromb.2011.11.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 11/07/2011] [Accepted: 11/09/2011] [Indexed: 10/15/2022]
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17
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Rosa CB, Goularte JF, Trindade NA, De Oliveira AP, Rasia-Filho AA. Glutamate microinjected in the posterodorsal medial amygdala induces subtle increase in the consumption of a three-choice macronutrient self-selection diet in male rats. Anat Rec (Hoboken) 2011; 294:1226-32. [PMID: 21634022 DOI: 10.1002/ar.21419] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 02/25/2011] [Accepted: 03/26/2011] [Indexed: 02/04/2023]
Abstract
Previous studies have involved the "posterodorsal" amygdaloid area with the control of food intake and the development of obesity in rats. Within this wide region, the posterodorsal medial amygdala (MePD) has connections with specific hypothalamic nuclei that increase feeding behavior and modulate energy balance. Glutamate is the major brain excitatory neurotransmitter, remarkably enhances centrally mediated food consumption, and is abundantly found in the MePD. Here, it was studied the effects of saline (0.3 μL) and glutamate (45 nM or 45 mM/0.3 μL) directly microinjected in the MePD of adult male rats on the consumption of a three-choice (high-carbohydrate, high-protein, or high-lipid) macronutrient selective diet. The rat adaptation to the experimental procedures and its body weight gain were continuously evaluated. Control data for all groups and results following microinjections were obtained after a fasting protocol. Feeding behavior was evaluated during the subsequent 2-hr period of free access to the selective diets. Both doses of glutamate microinjected in the MePD did not lead to a higher percentage of animals consuming any of the different diets (P > 0.05), although glutamate 45 mM induced a higher consumption of the high-carbohydrate diet when compared with presurgery control values (P < 0.01). Interestingly, present data indicate that glutamate in the male MePD induces only a subtle modification in the feeding behavior and suggest that large electrolytic lesions of the "posterodorsal" amygdaloid region might have affected other regions to alter drastically meal size consumption in rats.
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Affiliation(s)
- Carolina Böettge Rosa
- Pathology Graduate Program/Basic Neuroscience, Federal University of Health Sciences of Porto Alegre, Brazil
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18
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Hernández L, Paredes D, Rada P. Feeding behavior as seen through the prism of brain microdialysis. Physiol Behav 2011; 104:47-56. [PMID: 21549733 DOI: 10.1016/j.physbeh.2011.04.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 04/22/2011] [Indexed: 11/28/2022]
Abstract
The knowledge of feeding behavior mechanisms gained through brain microdialysis is reviewed. Most of the chemical changes so far reported concern to the limbic system in rodents. A picture showing increases and decreases of extracellular neurotransmitters correlating to different aspects of feeding behavior is gradually emerging. Depending on the region, the same neurotransmitter may signal opposite aspects of feeding. Dopamine (DA) in the nucleus accumbens (NAC) correlates with food reward, stimulus saliency, and goal directed hyperlocomotion but in the ventromedial hypothalamus DA correlates with satiety and hypolocomotion. The findings accumulated in the last 25 years suggest that the control of a particular function relies on the interaction of several neurotransmitters rather than on a single neurotransmitter. The poor sensitivity of most analytical techniques hinders time and spatial resolution of microdialysis. Therefore, neurochemical correlates of short lasting behaviors are hard to figure out. As new and more sensitive analytical techniques are applied, new neurochemical correlates of feeding show up. Sometimes the proper analytical techniques are simply not available. As a consequence, critical signals such as neuropeptides are not yet completely placed in the puzzle. Despite such limitations, brain microdialysis has yielded a great deal of knowledge on the neurochemical basis of feeding.
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Affiliation(s)
- Luis Hernández
- Laboratory of Behavioral Physiology, School of Medicine, Universidad de los Andes, Mérida, Venezuela
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19
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Hettes SR, Gonzaga WJ, Heyming TW, Nguyen JK, Perez S, Stanley BG. Stimulation of lateral hypothalamic AMPA receptors may induce feeding in rats. Brain Res 2010; 1346:112-20. [PMID: 20580634 DOI: 10.1016/j.brainres.2010.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 04/27/2010] [Accepted: 05/03/2010] [Indexed: 11/18/2022]
Abstract
Glutamate or its ionotropic receptor (iGluR) agonists, N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxale propionate (AMPA), and kainate (KA) elicit feeding when microinjected into the lateral hypothalamus (LH) of satiated rats. In the present study we investigated the contributions of AMPA and KA receptors (AMPARs and KARs) to feeding initiation. Intense feeding was elicited by LH injection of RS-AMPA (1 and 10 nmol) but not by the isolated, inactive R-AMPA enantiomer (1 and 10 nmol). Further, LH pretreatment with either the non-selective AMPAR/KAR antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 4 nmol) or the selective AMPAR antagonist, GYKI 52466 (10 nmol), suppressed AMPA-elicited food intake and, when combined, blocked AMPA-elicited food intake. These findings suggest that LH AMPARs mediate AMPA injection-elicited feeding with a possible contribution by KARs. In contrast, CNQX or GYKI 52466 injected into the LH at the onset of the nocturnal period or into fasted rats did not suppress the feeding produced by either condition. RS-AMPA injected into the LH of fasted or nocturnal feeding subjects elicited eating in both conditions; however, the magnitude of the increase was greater in fasted rats. These data suggest that selective stimulation of AMPAR in the LH is sufficient to elicit feeding. In contrast, the results did not provide evidence that AMPAR stimulation is necessary for deprivation-induced or nocturnal eating; however, they did suggest that modulatory interactions may exist between these receptors and these forms of naturally occurring eating behavior.
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MESH Headings
- 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
- Animals
- Benzodiazepines/pharmacology
- Dose-Response Relationship, Drug
- Excitatory Amino Acid Agonists/pharmacology
- Excitatory Amino Acid Antagonists/pharmacology
- Feeding Behavior/drug effects
- Food Deprivation/physiology
- Hypothalamic Area, Lateral/anatomy & histology
- Hypothalamic Area, Lateral/drug effects
- Hypothalamic Area, Lateral/physiology
- Injections
- Male
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/agonists
- Receptors, AMPA/antagonists & inhibitors
- Receptors, Kainic Acid/agonists
- Stereoisomerism
- Stimulation, Chemical
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/chemistry
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology
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Affiliation(s)
- Stacey R Hettes
- Neuroscience Graduate Program, University of California-Riverside, Riverside, CA 92521, USA
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20
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Featherstone DE. Intercellular glutamate signaling in the nervous system and beyond. ACS Chem Neurosci 2010; 1:4-12. [PMID: 22778802 DOI: 10.1021/cn900006n] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 09/25/2009] [Indexed: 01/22/2023] Open
Abstract
Most intercellular glutamate signaling in the nervous system occurs at synapses. Some intercellular glutamate signaling occurs outside synapses, however, and even outside the nervous system where high ambient extracellular glutamate might be expected to preclude the effectiveness of glutamate as an intercellular signal. Here, I briefly review the types of intercellular glutamate signaling in the nervous system and beyond, with emphasis on the diversity of signaling mechanisms and fundamental unanswered questions.
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Affiliation(s)
- David E. Featherstone
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607
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21
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da Silva AA, de Azevedo Campanella LC, Ramos MC, Parreira C, Faria MS, Marino-Neto J, Paschoalini MA. Arcopallium, NMDA antagonists and ingestive behaviors in pigeons. Physiol Behav 2009; 98:594-601. [DOI: 10.1016/j.physbeh.2009.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 08/21/2009] [Accepted: 09/18/2009] [Indexed: 01/29/2023]
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22
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Crestani CC, Deolindo MV, Alves FHF, Resstel LBM, Correa FMA. Non-N-methyl-d-aspartate glutamate receptors in the lateral hypothalamus modulate cardiac baroreflex responses in conscious rats. Clin Exp Pharmacol Physiol 2009; 36:1079-85. [DOI: 10.1111/j.1440-1681.2009.05191.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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23
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Hirasawa M, Parsons MP, Alberto CO. Interaction between orexins and the mesolimbic system for overriding satiety. Rev Neurosci 2009; 18:383-93. [PMID: 19544624 DOI: 10.1515/revneuro.2007.18.5.383] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In North American society, it is all too common for the intake of calories to outweigh an individual's energy demands. Such over-consumption where high-energy foods are readily available undoubtedly contributes to the growing problem of obesity. Palatable food stimulates brain circuits similar to those that mediate behavioral responses to drugs of abuse, which may underlie the continuation of food intake long after energy requirements are met. Among the brain areas implicated in reward and food intake, the lateral hypothalamus (LH) has long been recognized as a common region involved in both. It has been suggested that orexin neurons that are expressed exclusively within and adjacent to the LH comprise a major cellular substrate for the functioning of the LH. Here, we review the idea that the orexin neuropeptides play a key role in the rewarding aspects of food intake through interactions with both peripheral and central signals reflecting current energy stores as well as the classic reward pathway--the mesolimbic dopamine system. Furthermore, a possible heterogeneity of orexin neurons is discussed. Uncovering orexin's role in food reinforcement may provide insight into hyperphagia and obesity. In addition, the idea that food intake and substance abuse involve similar brain circuitry suggests potential for a single treatment aiding both obesity and addiction.
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Affiliation(s)
- Michiru Hirasawa
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada.
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24
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Thongkhao-on K, Wirtshafter D, Shippy SA. Feeding specific glutamate surge in the rat lateral hypothalamus revealed by low-flow push-pull perfusion. Pharmacol Biochem Behav 2008; 89:591-7. [PMID: 18377969 PMCID: PMC4209903 DOI: 10.1016/j.pbb.2008.02.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 02/06/2008] [Accepted: 02/14/2008] [Indexed: 11/18/2022]
Abstract
Substantial evidence implicates the lateral hypothalamus (LH) in the control of ingestive behavior and previous studies have found that glutamate release within the LH increases during meals. It is not known, however, whether this effect is selective for feeding, or whether similar changes are also seen during drinking. In this work, we examined this question using low-flow push-pull perfusion which allows sampling from small tissue volumes. Presentation of highly palatable solid or liquid foods to food-deprived rats resulted in an immediate increase in glutamate output of more than 200% over baseline. The response was maximal immediately after food presentation. In contrast, significant changes in glutamate output were not seen when water was presented to water-deprived animals, despite the occurrence of vigorous drinking. These findings confirm reports of feeding related glutamate release in the LH and demonstrate that this effect is specific to feeding, rather than being a general concomitant of all ingestive behaviors. The push-pull technique described here may allow the relevant region of the LH to be identified with greater precision than other methods.
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Affiliation(s)
- Kongthong Thongkhao-on
- Department of Chemistry, University of Illinois at Chicago, M/C 111, Chicago, IL 60607, United States.
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25
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Doane DF, Lawson MA, Meade JR, Kotz CM, Beverly JL. Orexin-induced feeding requires NMDA receptor activation in the perifornical region of the lateral hypothalamus. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1022-6. [PMID: 17537834 DOI: 10.1152/ajpregu.00282.2007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Food intake is stimulated following administration of orexin-A into the perifornical region of the lateral hypothalamus (LH/PFA). Orexin neurons originating in the LH/PFA interact with a number of hypothalamic systems known to influence food intake, including glutamatergic neurons. Glutamatergic systems in the LH/PFA were demonstrated to initiate feeding through N-methyl-d-aspartic acid (NMDA) receptors. Male Sprague-Dawley rats fitted with brain guide cannulas to the LH/PFA were used in two experiments. In the first experiment, a combination microdialysis/microinjection probe was used to deliver artificial cerebrospinal fluid (aCSF) or 500 pmol of orexin-A into the LH/PFA. Orexin-A increased interstitial glutamate to 143 ± 12% of baseline ( P < 0.05), which remained elevated over the 120-min collection period. In the second experiment, the NMDA receptor antagonist d-2-amino-5-phosphonopentanoic acid (d-AP5; 10 nmol) was administered before orexin-A. The orexin-induced increase in food intake (from 1.1 ± 0.4 to 3.2 ± 0.5 g, P < 0.05) during the first hour was absent in rats receiving d-AP5 + orexin-A (1.2 ± 0.5 g). There was no effect of d-AP5 alone on food intake. These data support glutamatergic systems in the LH/PFA mediating the feeding response to orexin-A through NMDA receptors.
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Affiliation(s)
- Dolores F Doane
- University of Illinois at Urbana-Champaign, 1207 W. Gregory Drive, Urbana, IL 61801, USA
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26
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Da Silva AA, Campanella LCA, Ramos MC, Faria MS, Paschoalini MA, Marino-Neto J. Ingestive effects of NMDA and AMPA-kainate receptor antagonists microinjections into the lateral hypothalamus of the pigeon (Columba livia). Brain Res 2006; 1115:75-82. [PMID: 16919612 DOI: 10.1016/j.brainres.2006.07.073] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2006] [Revised: 07/20/2006] [Accepted: 07/24/2006] [Indexed: 11/28/2022]
Abstract
This study examined the ingestive and behavioral effects of NMDA- and AMPA/kainate glutamatergic receptor blockade in the lateral hypothalamic area (LHy) of free-feeding pigeons (Columba livia). Injections of MK-801 (NMDA receptor antagonist; 6 nmol) or CNQX (AMPA/kainate receptor antagonist; 25.8 nmol) into the LHy of free-feeding pigeons induced significant increases in food intake and in feeding duration, as well as reductions in the latency to start feeding. Duration, latency and volume of water intake, as well as duration of sleep-like behavior, alert immobility, locomotion and preening were not changed by these treatments in the LHy. These results indicate that glutamatergic inputs to cells containing NMDA and/or AMPA receptors located in the LHy could modify both the beginning of a feeding bout (or the end of a period of satiety) and its duration (satiation). Our data also suggest that these inhibitory glutamatergic influences on feeding behavior are tonically active in the LHy.
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MESH Headings
- 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
- Animals
- Appetite Regulation/drug effects
- Appetite Regulation/physiology
- Columbidae/anatomy & histology
- Columbidae/metabolism
- Dizocilpine Maleate/pharmacology
- Excitatory Amino Acid Antagonists/pharmacology
- Feeding Behavior/drug effects
- Feeding Behavior/physiology
- Glutamic Acid/metabolism
- Hypothalamic Area, Lateral/anatomy & histology
- Hypothalamic Area, Lateral/drug effects
- Hypothalamic Area, Lateral/metabolism
- Male
- Microinjections/methods
- Neural Inhibition/drug effects
- Neural Inhibition/physiology
- Neural Pathways/anatomy & histology
- Neural Pathways/drug effects
- Neural Pathways/metabolism
- Neurons/drug effects
- Neurons/metabolism
- Presynaptic Terminals/drug effects
- Presynaptic Terminals/metabolism
- Receptors, AMPA/antagonists & inhibitors
- Receptors, AMPA/metabolism
- Receptors, Glutamate/drug effects
- Receptors, Glutamate/metabolism
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/metabolism
- Satiety Response/drug effects
- Satiety Response/physiology
- Species Specificity
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- Amanda A Da Silva
- Department of Physiological Sciences, CCB, Federal University of Santa Catarina, 88040-900 Florianópolis SC, Brazil
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27
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Ramírez-Lugo L, Núñez-Jaramillo L, Bermúdez-Rattoni F. Taste Memory Formation: Role of Nucleus Accumbens. Chem Senses 2006; 32:93-7. [PMID: 16914504 DOI: 10.1093/chemse/bjl023] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
When a novel taste has been associated with postingestive malaise, animals recognize this taste as aversive. This associative learning is known as conditioned taste aversion. However, when an animal consumes a novel taste and no aversive consequences follow, it becomes recognized as a safe signal, leading to an increase in its consumption in subsequent presentations. In this review, we will discuss the results related to the taste memory formation focusing particularly on the nucleus accumbens (NAcc). The NAcc keeps projections with amygdala, insular cortex, parabrachial nucleus, and nucleus of the solitary tract areas important for taste memory formation. We will review the evidence relating to how the NAcc could be involved in taste memory formation, due to its role in the taste memory trace formation and its role in the association of the conditioned stimulus-unconditioned stimulus, and finally the retrieval of taste memory. In this context, we will review the participation of the cholinergic, dopaminergic, and glutamatergic systems in the NAcc during taste memory formation.
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Affiliation(s)
- Leticia Ramírez-Lugo
- Departamento de Neurociencias, Instituto de Fisiologia Celular, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-253, 04510 Mexico, DF, Mexico
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28
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Lee SW, Stanley BG. NMDA receptors mediate feeding elicited by neuropeptide Y in the lateral and perifornical hypothalamus. Brain Res 2005; 1063:1-8. [PMID: 16259968 DOI: 10.1016/j.brainres.2005.09.045] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Revised: 09/02/2005] [Accepted: 09/24/2005] [Indexed: 11/25/2022]
Abstract
Neuropeptide Y (NPY) and N-methyl-d-aspartate (NMDA) receptors in the lateral (LH) and perifornical hypothalamus (PFH) are believed to be involved in the stimulation of feeding behavior. To investigate the possibility that neurons with these receptors interact to stimulate eating, the NMDA receptor antagonists d-(-)-2-amino-5-phosphonopentanoic acid (D-AP5) or 7-chlorokynurenic acid (7-CK) were injected into the LH or PFH of satiated rats 5 min prior to NPY in the same site and subsequent food intake was measured 1, 2, and 4 h postinjection. The injection of NPY (78 pmol/0.3 microl aCSF) in the PFH produced an average food intake of 9.7 g in 4 h, compared to the intake of 1.3 g after the artificial cerebrospinal fluid (aCSF) vehicle. D-AP5 (1, 10, or 20 nmol/0.3 microl aCSF) pretreatment suppressed NPY-induced eating, with the 20 nmol dose of D-AP5 producing up to an 80% suppression of elicited food intake down to 1.9 g in 4 h. Similar effects were produced with the LH as the injection site. Illustrating the specificity of the NMDA receptor antagonist's suppression of NPY-elicited feeding, D-AP5 suppressed NMDA-elicited feeding but did not affect the eating response induced by kainic acid. Consistent with the effects of D-AP5, the NMDA receptor antagonist 7-CK (40 nmol/0.3 microl dimethyl sulfoxide, DMSO) suppressed feeding elicited by NPY in the LH by 78%. Collectively, the findings suggest that the feeding elicited by NPY is dependent upon the activation of the NMDA receptors in the LH and PFH.
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Affiliation(s)
- Star W Lee
- Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, CA 92521, USA
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29
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Khan AM, Cheung HH, Gillard ER, Palarca JA, Welsbie DS, Gurd JW, Stanley BG. Lateral hypothalamic signaling mechanisms underlying feeding stimulation: differential contributions of Src family tyrosine kinases to feeding triggered either by NMDA injection or by food deprivation. J Neurosci 2005; 24:10603-15. [PMID: 15564576 PMCID: PMC6730118 DOI: 10.1523/jneurosci.3390-04.2004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In rats, feeding can be triggered experimentally using many approaches. Included among these are (1) food deprivation and (2) acute microinjection of the neurotransmitter l-glutamate (Glu) or its receptor agonist NMDA into the lateral hypothalamic area (LHA). Under both paradigms, the NMDA receptor (NMDA-R) within the LHA appears critically involved in transferring signals encoded by Glu to stimulate feeding. However, the intracellular mechanisms underlying this signal transfer are unknown. Because protein-tyrosine kinases (PTKs) participate in NMDA-R signaling mechanisms, we determined PTK involvement in LHA mechanisms underlying both types of feeding stimulation through food intake and biochemical measurements. LHA injections of PTK inhibitors significantly suppressed feeding elicited by LHA NMDA injection (up to 69%) but only mildly suppressed deprivation feeding (24%), suggesting that PTKs may be less critical for signals underlying this feeding behavior. Conversely, food deprivation but not NMDA injection produced marked increases in apparent activity for Src PTKs and in the expression of Pyk2, an Src-activating PTK. When considered together, the behavioral and biochemical results demonstrate that, although it is easier to suppress NMDA-elicited feeding by PTK inhibitors, food deprivation readily drives PTK activity in vivo. The latter result may reflect greater PTK recruitment by neurotransmitter receptors, distinct from the NMDA-R, that are activated during deprivation-elicited but not NMDA-elicited feeding. These results also demonstrate how the use of only one feeding stimulation paradigm may fail to reveal the true contributions of signaling molecules to pathways underlying feeding behavior in vivo.
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Affiliation(s)
- Arshad M Khan
- Department of Cell Biology and Neuroscience, University of California, Riverside, California 92521, USA.
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30
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Saulskaya NB, Soloviova NA. Tetrodotoxin-dependent glutamate release in the rat nucleus accumbens during concurrent presentation of appetitive and conditioned aversive stimuli. J Neurosci Methods 2005; 140:15-21. [PMID: 15589329 DOI: 10.1016/j.jneumeth.2004.03.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2003] [Accepted: 03/08/2004] [Indexed: 11/22/2022]
Abstract
In vivo microdialysis combined with a high-performance liquid chromatography was used to monitor extracellular glutamate (GLU) levels in the nucleus accumbens (N.Acc) of Sprague-Dawley rats during their behavioral responses to the concurrent presentation of appetitive and conditioned aversive stimuli. The presentation of a highly palatable diet followed by a tone previously paired with footshock to rats trained to take a pellet of the diet under these experimental conditions resulted in a marked and short lasting increase in extracellular glutamate, whereas the tone alone had no effect. A similar increase of the glutamate release was observed during the presentation of a piece of rubber instead of the diet. In both cases, the increase in extracellular glutamate was completely prevented by intra-accumbal infusions through the dialysis probe of 1 microM tetrodotoxin (a voltage-dependent Na(+) channel blocker), whereas (S)-4-carboxyphenylglycine (a cystine/glutamate exchange blocker, 5 microM) had no effect. The data obtained suggest that behavioral responses to unpredicted change in motivational value of expected reward appear to be associated with an increase of the extracellular glutamate level in the nucleus accumbens, and impulse-dependent synaptic release, rather than non-vesicular glutamate release via cystine/glutamate exchange, is responsible for this phenomenon.
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Affiliation(s)
- Natalia B Saulskaya
- Laboratory of Higher Nervous Activity, I.P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Admiral Makarov Embankment, St. Petersburg 199034, Russia.
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31
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White BD, Du F, Higginbotham DA. Low dietary protein is associated with an increase in food intake and a decrease in the in vitro release of radiolabeled glutamate and GABA from the lateral hypothalamus. Nutr Neurosci 2004; 6:361-7. [PMID: 14744040 DOI: 10.1080/10284150310001640365] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Moderately low-protein diets lead to a rapid increase in food intake and body fat. The increase in feeding is associated with a decrease in the concentration of serum urea nitrogen, suggesting that the low-protein-induced increase in food intake may be related to the decreased metabolism of nitrogen from amino acids. We hypothesized that low dietary protein would be associated with a decrease in the synaptic release of two nitrogen-containing neurotransmitters, GABA and glutamate, whose nitrogen can be derived from amino acids. In this study, we examined the effects of a low-protein diet (10% casein) in Sprague-Dawley rats on the in vitro release of 3H-GABA and 14C-glutamate from the lateral and medial hypothalamus. The low-protein diet increased food intake by about 25% after one day. After four days, the in vitro release of radiolabeled GABA and glutamate was assessed. The calcium-dependent, potassium-stimulated release of radiolabeled GABA and glutamate from the lateral hypothalamus was decreased in rats fed the low-protein diet. The magnitude of neurotransmitter release from the lateral hypothalamus inversely correlated with food intake. No dietary differences in the release of neurotransmitters from the medial hypothalamus were observed. These results support the contention that alterations in nitrogen metabolism are associated with low-protein-induced feeding.
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Affiliation(s)
- B D White
- Department of Nutrition and Food Science, 328 Spidle Hall, Auburn University, AL 36849, USA.
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32
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Silva E, Hernandez L, Quiñonez B, Gonzalez LE, Colasante C. Selective amino acids changes in the medial and lateral preoptic area in the formalin test in rats. Neuroscience 2004; 124:395-404. [PMID: 14980389 DOI: 10.1016/s0306-4522(03)00437-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/30/2003] [Indexed: 11/22/2022]
Abstract
A combination of microdialysis in freely moving rats and capillary zone electrophoresis coupled to laser induced fluorescence detection was used to measure extracellular concentrations of amino acid neurotransmitters in different hypothalamic areas during noxious stimulation. Arginine, glutamate and aspartate were monitored every 30 s before and after a s.c. injection of formalin (5%, 50 microl) or saline (0.9%) in the right hind paw. In the medial and lateral preoptic area, calcium and nerve impulse dependent increases of arginine, glutamate and aspartate were observed during the first 2 min after formalin injection. However, amino acid changes were not detected in the lateral hypothalamus or in the ventromedial nucleus when compared with pre-injection levels or with the levels from animals injected with saline in the hind paw. Flinching behavior was also scored during the first 10 min following the formalin or saline injection. Flinching frequency was maximum at minute 2 after formalin injection, whereas saline injection did not elicited any flinching behavior. These results show that nociceptive stimulation induces rapid and differential amino acids changes in discrete areas of the hypothalamus that can be associated with pain-related behavior.
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Affiliation(s)
- E Silva
- Laboratory of Behavioral Physiology, School of Medicine, Universidad de Los Andes, Merida, Venezuela.
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33
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Hettes SR, Gonzaga J, Heyming TW, Perez S, Wolfsohn S, Stanley BG. Dual roles in feeding for AMPA/kainate receptors: receptor activation or inactivation within distinct hypothalamic regions elicits feeding behavior. Brain Res 2003; 992:167-78. [PMID: 14625056 DOI: 10.1016/j.brainres.2003.08.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have previously shown that hypothalamic injections of glutamate, or agonists of its ionotropic receptors (iGluRs), elicit intense feeding responses in satiated rats [Brain Res. 613 (1993) 88, Brain Res. 630 (1993) 41]. While attempting to clarify the role of the AMPA and kainate (KA) receptor subtypes in glutamatergic feeding systems, we discovered that lateral hypothalamic (LH) injection of high doses of the competitive AMPA/KA receptor antagonist, NBQX (10 and 30 nmol), elicited a pronounced feeding response. We questioned whether this effect was due to inactivation of AMPA or possibly KA receptors. To determine whether other AMPA/KA antagonists can also elicit feeding, we tested whether injection of CNQX, another AMPA/KA receptor antagonist, also stimulates eating and whether these feeding stimulatory effects were due to antagonists' actions in the LH or in other hypothalamic sites. Here we report that NBQX and CNQX elicit feeding in a dose dependent manner and are most effective when injected into the perifornical hypothalamus (PFH), or into the paraventricular nucleus (PVN) and, to a lesser extent, into the LH of satiated rats. In contrast, AMPA was most effective in stimulating feeding when injected into the LH, confirming previous reports. These data suggest that either activation or inactivation of AMPA/KA receptors in distinct but overlapping hypothalamic sites may be sufficient to induce feeding behavior, indicating a broadened role for glutamate in hypothalamic feeding mechanisms.
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MESH Headings
- 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
- Animals
- Dose-Response Relationship, Drug
- Feeding Behavior/drug effects
- Feeding Behavior/physiology
- Glutamic Acid/metabolism
- Hypothalamic Area, Lateral/cytology
- Hypothalamic Area, Lateral/drug effects
- Hypothalamic Area, Lateral/metabolism
- Hypothalamus/cytology
- Hypothalamus/drug effects
- Hypothalamus/metabolism
- Male
- Neural Pathways/cytology
- Neural Pathways/drug effects
- Neural Pathways/metabolism
- Paraventricular Hypothalamic Nucleus/cytology
- Paraventricular Hypothalamic Nucleus/drug effects
- Paraventricular Hypothalamic Nucleus/metabolism
- Quinoxalines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/agonists
- Receptors, AMPA/antagonists & inhibitors
- Receptors, AMPA/metabolism
- Receptors, Kainic Acid/agonists
- Receptors, Kainic Acid/antagonists & inhibitors
- Receptors, Kainic Acid/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology
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Affiliation(s)
- Stacey R Hettes
- Neuroscience Graduate Program, University of California-Riverside,Riverside, CA 92521, USA.
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34
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Rada P, Moreno SA, Tucci S, Gonzalez LE, Harrison T, Chau DT, Hoebel BG, Hernandez L. Glutamate release in the nucleus accumbens is involved in behavioral depression during the PORSOLT swim test. Neuroscience 2003; 119:557-65. [PMID: 12770568 DOI: 10.1016/s0306-4522(03)00162-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
An abnormality in glutamate function has been implicated in the neural substrate of depressive disorders. To investigate this in rats, the Porsolt swim test was used to assess the role of glutamate in the nucleus accumbens. Glutamate injected into the nucleus accumbens dose-dependently decreased swimming time on the test day (day 2), whereas N-methyl-D-aspartate antagonists dizocilpine and 2-amino-5-phosphonovalerate increased swimming, like an antidepressant. Dizocilpine injected before the conditioning trial (day 1) did not modify the swimming times during the first day but abolished behavioral depression on day 2. Microdialysis coupled to capillary-zone electrophoresis was then used to determine in vivo changes in glutamate release in 1-min samples during the swim test. On day 1, glutamate increased significantly and reached a maximum of 222% after 3 min of swimming. On day 2, baseline glutamate levels were back to normal, but when the animal was placed in the water, glutamate increased to 419% during the first minute, and the animals swam significantly less. For comparison, tail pinch on consecutive days was used as a nonspecific, repeated stressor while accumbens glutamate levels were measured. Tail pinch on the first day increased glutamate similar to the effect obtained during the first day of swimming; however, a second day of tail pinch decreased glutamate levels, instead of the potentiated response observed during the second day of swimming. These results show that accumbens glutamate plays a role in causing the behavioral aspects of depressed behavior as modeled in the swim test. The accumbens may be a potential site of action for drugs that alter behavioral depression.
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Affiliation(s)
- P Rada
- Laboratory of Behavioral Physiology, Universidad de los Andes, Mérida, Venezuela 5101-A
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35
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Mikhailova MO. Comparison of changes in glutamate levels in the nucleus accumbens of the rat brain during food consumption in conditions of blockade of dopamine D1 and D2 receptors. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2003; 33:431-4. [PMID: 12921172 DOI: 10.1023/a:1023450931164] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effects of blockade of D1 and D2 dopamine receptors in the nucleus accumbens on changes in glutamate levels in the intercellular space of this structure during food consumption were studied in Sprague-Dawley rats by intracerebral microdialysis combined with HPLC. These experiments showed that food consumption was accompanied by decreases in glutamate levels in the intercellular spaces of the nucleus accumbens. Blockade of D1 dopamine receptors with SCH-23390 (0.01 mM) produced no changes in the dynamics of glutamate release during food consumption. Food consumption in conditions of blockade of D2 dopamine receptors with raclopride (0.01 mM) induced increases in glutamate levels. These data suggest that glutamate levels during food consumption are controlled by the dopaminergic system of the nucleus accumbens, mediated by D2 but not D1 dopamine receptors.
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Affiliation(s)
- M O Mikhailova
- I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Makarov Bank, 199034 St. Petersburg, Russia
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36
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Extracellular glutamate decrease in accumbens following cued food delivery. Neuroreport 2003. [DOI: 10.1097/00001756-200305230-00017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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37
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Reynolds SM, Berridge KC. Glutamate motivational ensembles in nucleus accumbens: rostrocaudal shell gradients of fear and feeding. Eur J Neurosci 2003; 17:2187-200. [PMID: 12786986 DOI: 10.1046/j.1460-9568.2003.02642.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study demonstrates that microinjection of an AMPA/kainate glutamate antagonist elicits motivated fear and feeding behaviour mapped along rostrocaudal gradients of positive-to-negative valence in nucleus accumbens shell (similar to rostrocaudal shell gradients recently reported for GABA agonist microinjections). Rats received rostral or caudal microinjections of the glutamate AMPA/kainate receptor antagonist DNQX (0, 50, 450 or 850 ng in 0.5 micro L) or the NMDA receptor antagonist MK-801 (0, 0.5, 1 or 2 micro g in 0.5 micro L), into medial accumbens shell prior to behavioural tests for fear, feeding or conditioning of place preference or avoidance. Another group received rostral or caudal microinjections of DNQX in nucleus accumbens core. Rostral shell DNQX microinjections potently increased appetitive food intake and established only weak conditioned place avoidance. Caudal shell DNQX microinjections elicited defensive treading behaviour, caused rats to defensively bite the experimenter and emit fearful distress vocalizations when handled, and established strong conditioned place avoidance. By contrast, no rostrocaudal gradients of motivational bivalence were produced by microinjections of the glutamate AMPA/kainate receptor antagonist DNQX into the core, or by microinjections of the NMDA antagonist MK-801 into the shell. Our results indicate that appetitive and aversive motivation is carried in anatomically differentiated channels by mesocorticolimbic glutamate signals to microcircuits in the medial shell. Hyperpolarization of local shell ensembles by AMPA/kainate glutamate receptor blockade elicits fear and feeding behaviours mapped along distinct positive-to-negative rostrocaudal gradients.
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Affiliation(s)
- Sheila M Reynolds
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109-1109, USA.
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38
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Rada P, Mendialdua A, Hernandez L, Hoebel BG. Extracellular glutamate increases in the lateral hypothalamus during meal initiation, and GABA peaks during satiation: microdialysis measurements every 30 s. Behav Neurosci 2003; 117:222-7. [PMID: 12708518 DOI: 10.1037/0735-7044.117.2.222] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Glutamate injected into the lateral hypothalamus can initiate eating, and gamma-aminobutyric acid (GABA) can stop it. This leads to the hypothesis that glutamate inputs are active at the beginning of a meal, and GABA is released at the end. To test this theory, the authors used microdialysis to sample glutamate and GABA simultaneously before, during, and after a meal. Food-deprived rats ate a meal of chow. Glutamate increased during the first third of the meal, then decreased to below baseline while the rats were still eating. GABA also increased at the start of the meal but continued rising and peaked during the last third of the meal. Glutamate may drive a hypothalamic system for eating, and GABA may oppose it.
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Affiliation(s)
- Pedro Rada
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, Venezuela
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39
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Da Silva AA, Marino-Neto J, Paschoalini MA. Feeding induced by microinjections of NMDA and AMPA-kainate receptor antagonists into ventral striatal and ventral pallidal areas of the pigeon. Brain Res 2003; 966:76-83. [PMID: 12646310 DOI: 10.1016/s0006-8993(02)04196-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The participation of glutamatergic circuits of the ventral basal ganglia in feeding-related regulatory mechanisms has been extensively indicated in primate and rodent species. In avian species, it has been shown that ICV injections of MK-801 or of CNQX increase food intake and reduce the latency of feeding initiation in free-feeding pigeons. In the present study, the effects of local injections of MK-801 (6 nmol), CNQX (160 nmol) or vehicle (0.2 microl) into a number of ventral striatopallidal nuclei on feeding, drinking and non-ingestive (sleep, preening) spontaneous behaviors were investigated in free-feeding pigeons (Columba livia). Intense feeding responses associated with an increased duration of feeding behavior were consistently recorded after injections of MK-801 or CNQX into the medial two-thirds of the tuberculum olfactorium (TO), the ventral aspect of lobus parolfactorium (LPOv), or the ventral pallidum (VP). In contrast, the latency of feeding initiation was unaffected by these treatments. No changes in drinking, preening or sleep responses were observed after drug injections into the TO/LPOv/VP area. These data indicate that glutamate-mediated circuits in the TO/LPOv/VP area can play an inhibitory role in feeding behavior in this species, contributing to the conclusion of a feeding bout, thus delaying satiation processes, and that these effects may be mediated by AMPA and NMDA receptors. Additionally, our data support the notion that a region functionally and anatomically comparable to the mammalian accumbens shell may be present in the TO/LPOv/VP region of the pigeon, and that the existence of a glutamatergic circuit in the ventral striatum controlling feeding-related phenomena may represent a highly conserved attribute throughout the amniote's evolution.
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Affiliation(s)
- Amanda A Da Silva
- Department of Physiological Sciences, CCB, Federal University of Santa Catarina, 88049-900, Florianópolis SC, Brazil
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40
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Parrot S, Bert L, Renaud B, Denoroy L. Glutamate and aspartate do not exhibit the same changes in their extracellular concentrations in the rat striatum after N-methyl-D-aspartate local administration. J Neurosci Res 2003; 71:445-54. [PMID: 12526032 DOI: 10.1002/jnr.10489] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
To determine whether glutamate (Glu) and aspartate (Asp) undergo a similar regulation of their extracellular levels, Glu and Asp were simultaneously monitored in the striatum of anesthetized rats after local N-methyl-D-aspartate (NMDA) receptor stimulation, using 1-min in vivo microdialysis coupled to capillary electrophoresis with laser-induced fluorescence detection. Application of NMDA (10 min, 10(-3) M) through the dialysis probe induced 1) an increase (+50%) in Asp during the NMDA administration and 2) a surprising biphasic effect on Glu, with a rapid increase (+30%) and a return to baseline before the end of NMDA application, followed by a second increase (+40%) occurring after and linked to the end of NMDA administration. When studied in the presence of 10 microM tetrodotoxin (TTX) or 0.1 mM Ca(2+), the increase in Asp was partially TTX-dependent, and the early increase in Glu appeared to be partially TTX and Ca(2+) dependent, whereas the second increase in Glu was not. The second increase in Glu level was still present when NMDA antagonists (AP5 or MK-801) were administered at the end of NMDA application. Finally, only extracellular Asp was increased through application of lower NMDA concentrations (10(-4) M, 10(-5) M), whereas extracellular Glu was not affected. In conclusion, these results suggest a differential control of Glu and Asp extracellular levels in rat striatum by distinct mechanisms linked to NMDA receptors and involving neuronal or nonneuronal release.
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Affiliation(s)
- Sandrine Parrot
- Laboratoire de Neuropharmacologie et Neurochimie, INSERM U512, Faculté de Pharmacie, Université Claude Bernard, Lyon, France.
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41
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Saul'skaya NB, Mikhailova MO. The effects of motivational and emotional factors in glutamate release in the nucleus accumbens of the rat brain during food consumption. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2003; 33:151-6. [PMID: 12669786 DOI: 10.1023/a:1021769814069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Studies on male Sprague-Dawley rats using intracerebral dialysis and high-performance liquid chromatography with electrochemical detection showed that consumption of fold with an attractive taste was accompanied by decreases in glutamate levels in the intercelular space of the nucleus accumbens, whose depth and duration depended on food deprivation. It was only in deprived animals that food consumption in conditions of presentation of a conditioned sound signal previously combined with electrocutaneous stimulation of the paws led to increases in intercellular glutamate levels in this structure. Isolated presentation of the aversion-relevant conditioned stimulation did not elicit changes in intercellular glutamate levels. These data suggest cooperativity in the actions of motivational and emotional factors in controlling glutamate release into the intercellular space of the nucleus accumbens during food consumption.
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Affiliation(s)
- N B Saul'skaya
- I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Makarov Bank, 199034 St. Petersburg, Russia
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42
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Bert L, Parrot S, Robert F, Desvignes C, Denoroy L, Suaud-Chagny MF, Renaud B. In vivo temporal sequence of rat striatal glutamate, aspartate and dopamine efflux during apomorphine, nomifensine, NMDA and PDC in situ administration. Neuropharmacology 2002; 43:825-35. [PMID: 12384168 DOI: 10.1016/s0028-3908(02)00170-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In vivo microdialysis was used to investigate the interactions between dopamine (DA), glutamate (Glu) and aspartate (Asp) in anaesthetised-rat striatum. The combination of brain microdialysis and capillary electrophoresis with laser-induced fluorescence detection (CE-LIFD) allows the simultaneous monitoring of the efflux of these neurotransmitters up to every 10 s. DA and Glu reuptake inhibitors, nomifensine and L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC) and, dopaminergic and glutamatergic receptor agonists, apomorphine and NMDA respectively, were administered by reverse dialysis. Reverse dialysis of 20 micro M nomifensine induced a rapid and marked increase (+3200% at 5 min) in extracellular DA, while a decrease in Glu and Asp (-11 and -25%, respectively) was observed simultaneously. Reverse dialysis of 10 micro M apomorphine led to progressive changes: -63% decrease in DA and +25% Glu increase at 36 min. Reverse dialysis of 1 mM NMDA induced a simultaneous increase in DA, Glu and Asp which peaked at +2 min (+840%, +40% and +150%, respectively). Surprisingly, a second increase in Glu was observed 5 min after the end of NMDA perfusion. Reverse dialysis of PDC (1 mM and 10 mM) induced a rapid increase in Glu and Asp levels, while DA increased with a 26-s delay. These findings indicate that, in the striatum, endogenous DA and Glu may act in opposition to regulate each other's efflux. These results have been obtained due to unique features offered by microdialysis coupled with CE-LIFD.
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Affiliation(s)
- L Bert
- Laboratoire de Neuropharmacologie et Neurochimie, INSERM U512, Université Claude Bernard, Faculté de Pharmacie, 8 Avenue Rockefeller, 69373 08, Lyon Cedex, France.
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43
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Saulskaya NB, Mikhailova MO. Feeding-induced decrease in extracellular glutamate level in the rat nucleus accumbens: dependence on glutamate uptake. Neuroscience 2002; 112:791-801. [PMID: 12088739 DOI: 10.1016/s0306-4522(02)00126-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In vivo microdialysis combined with high-performance liquid chromatography and electrochemical detection was used to monitor extracellular glutamate levels in the medial nucleus accumbens of Sprague-Dawley rats during their feeding behaviour. Consumption of a palatable new diet or a diet to which rats were previously exposed caused a decrease in extracellular level of glutamate in the nucleus accumbens during and after feeding. The presentation of an inedible object (a piece of rubber) instead of the expected food caused a marked increase in extracellular glutamate levels. In contrast, if the piece of rubber was presented to rats that did not expect food delivery, the extracellular level of glutamate remained unchanged during the rubber presentation. The feeding-induced decrease in the extracellular glutamate level did not depend on food deprivation and was completely prevented by intraaccumbal infusions through the dialysis probe of 10 mM D,L-threo-beta-hydroxyaspartate (a glutamate uptake inhibitor). Intraaccumbal infusions of 10 microM S-(-)-raclopride L-tartrate (a D2/D3 dopamine receptor antagonist) or 1 microM tetrodotoxin (a voltage-dependent Na(+) channel blocker) also completely reversed the decrease in extracellular glutamate level in response to food intake. The D1/D5 dopamine receptor antagonist SCH-23390 (10 microM) administered into the nucleus accumbens had no significant effect on the feeding-induced decrease in extracellular glutamate level. From the data obtained we suggest that the decrease in the extracellular level of glutamate in the medial nucleus accumbens in response to feeding appears to arise from a temporal increase in glutamate uptake that is probably operated by dopamine inputs to the nucleus accumbens via D2/D3 receptors. Our findings also suggest that the dissociation between the expected biological value of a presented object and the reality might be an important determinant for regulation of glutamate release in this brain area during feeding behaviour.
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Affiliation(s)
- N B Saulskaya
- Laboratory of Higher Nervous Activity, I.P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Admiral Makarov Embankment, St. Petersburg 199034, Russia.
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Silva E, Quiñones B, Freund N, Gonzalez LE, Hernandez L. Extracellular glutamate, aspartate and arginine increase in the ventral posterolateral thalamic nucleus during nociceptive stimulation. Brain Res 2001; 923:45-9. [PMID: 11743971 DOI: 10.1016/s0006-8993(01)03195-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Although there is evidence that the thalamus plays a remarkable role in pain processing few in vivo studies on the thalamic neurochemical correlates of pain have been done. In the present experiments a combination of capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIF) and microdialysis in freely moving rats was used to measure extracellular arginine, glutamate and aspartate in the thalamus during the formalin test. Microdialysis probes were implanted in the left ventral posterolateral (VPL) nucleus of the thalamus in rats. Samples were collected every 30 s, derivatized with fluorescein isothyocyanate and injected into a CZE-LIF instrument. After nine baseline samples, a subcutaneous formalin (5%, 50 microl) injection in the right hind paw caused an increase of arginine, glutamate and aspartate that lasted for about 3 min. These increases were calcium and nerve impulse dependent. These results indicate that the release of arginine, glutamate and aspartate may mediate rapid pain neural transmission in the VPL nucleus of the thalamus.
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Affiliation(s)
- E Silva
- Behavioral and Physiology Laboratory, School of Medicine, Los Andes University (ULA), Merida 5101, Venezuela.
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Duva MA, Tomkins EM, Moranda LM, Kaplan R, Sukhaseum A, Jimenez A, Stanley BG. Reverse microdialysis of N-methyl-D-aspartic acid into the lateral hypothalamus of rats: effects on feeding and other behaviors. Brain Res 2001; 921:122-32. [PMID: 11720718 DOI: 10.1016/s0006-8993(01)03108-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effects of reverse microdialysis of N-methyl-D-aspartic acid (NMDA) into the lateral hypothalamus (LH) on feeding and other behaviors were examined. Consistent with similar studies utilizing central microinjections, NMDA reverse microdialysed into the rat LH rapidly elicited a strong concentration-dependent stimulation of feeding. The minimum perfusate concentration of NMDA needed to elicit feeding with reverse microdialysis was 660 microM, a concentration 1/50 of that needed with pressure injections. Further, eating responses could be consistently elicited in sequential tests separated by 2-4 h in the same subject, and the magnitude of the eating in the first and second tests was highly correlated (r=0.87). Behavioral analysis revealed that the main response to NMDA consisted of eating without the concomitant hyperactivity produced by central microinjections of this agonist. The other behaviors exhibited during NMDA administration were those that normally occur during spontaneous feeding in rats. Also, rats precisely compensated for the increased food intake elicited by NMDA by reducing spontaneous feeding during the subsequent nocturnal phase, so as to maintain normal daily intakes. In contrast, N-methyl-L-aspartate (NMLA) reverse microdialysed in to the LH (660 microM) did not elicit feeding nor affect any other behaviors we examined. These data support a role for LH glutamate and NMDA receptors in the control of feeding.
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Affiliation(s)
- M A Duva
- Department of Psychology, University of California-Riverside, Riverside, CA 92521, USA
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Echo JA, Lamonte N, Christian G, Znamensky V, Ackerman TF, Bodnar RJ. Excitatory amino acid receptor subtype agonists induce feeding in the nucleus accumbens shell in rats: opioid antagonist actions and interactions with mu-opioid agonists. Brain Res 2001; 921:86-97. [PMID: 11720714 DOI: 10.1016/s0006-8993(01)03094-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Administration of mu-opioid receptor subtype agonists into the nucleus accumbens shell elicits feeding which is dependent upon the normal function of mu-, delta- and kappa-opioid receptors, D(1) dopamine receptors and GABA(B) receptors in the nucleus accumbens shell for its full expression. Whereas the AMPA antagonist, DNQX administered into the nucleus accumbens shell elicits a transient, though intense feeding response, feeding is elicited by excitatory amino acid agonists administered into the lateral hypothalamus. The present study examined whether excitatory amino acid agonists elicited feeding following administration into the nucleus accumbens shell of rats, whether such feeding responses were altered by opioid antagonist pretreatment, and whether such feeding responses interacted with feeding elicited by mu-opioid agonists. Both AMPA (0.25-0.5 microg) and NMDA (1 microg) in the nucleus accumbens shell significantly and dose-dependently increased food intake over 4 h. Both feeding responses were blocked by naltrexone pretreatment in the nucleus accumbens shell. The mu-opioid agonist, [D-Ala(2),NMe-Phe(4),Gly-ol(5)]-enkephalin in the nucleus accumbens shell significantly increased food intake which was significantly enhanced by AMPA cotreatment. This enhanced feeding response was in turn blocked by pretreatment with either general or mu-selective opioid antagonists. In contrast, cotreatment of NMDA and the mu-opioid agonist in the nucleus accumbens shell elicited feeding which was significantly less than that elicited by either treatment alone. These data indicate the presence of important interactions between excitatory amino acid receptors and mu-opioid receptors in the nucleus accumbens shell in mediating feeding responses in nondeprived, ad libitum-fed rats.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Dose-Response Relationship, Drug
- Drug Interactions/physiology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Excitatory Amino Acid Agonists/pharmacology
- Feeding Behavior/drug effects
- Feeding Behavior/physiology
- Male
- N-Methylaspartate/pharmacology
- Naltrexone/pharmacology
- Narcotic Antagonists/pharmacology
- Neurons/drug effects
- Neurons/metabolism
- Nucleus Accumbens/drug effects
- Nucleus Accumbens/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/agonists
- Receptors, AMPA/metabolism
- Receptors, N-Methyl-D-Aspartate/agonists
- Receptors, N-Methyl-D-Aspartate/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology
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Affiliation(s)
- J A Echo
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Boulevard, Flushing, NY 11367, USA
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Páez X, Hernández L. Biomedical applications of capillary electrophoresis with laser-induced fluorescence detection. Biopharm Drug Dispos 2001; 22:273-89. [PMID: 11835251 DOI: 10.1002/bdd.277] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Capillary electrophoresis (CE) is a high-efficiency analytical technique that has had a great impact as a tool in biomedical research, clinical and forensic practice in the last ten years. Only in one of the applications, the DNA analysis, it has had an explosive exponential growth in the last few years. This impact is expressed in an enormous amount of CE articles and many reviews. The CE advantages with respect to other analytical techniques: the required very small sample volume, rapid analysis, great resolution power and low costs, have made this technique ideal for the analysis of a numerous endogenous and exogenous substances present in biological fluids. The different modes of CE have been coupled to different detection techniques such as UV-absorbance, electrochemical, mass spectrometry and laser-induced fluorescence detection (LIFD) to detect different nature and molecular size separated analytes. This review focuses mostly on the applications of CE-LIFD, to measure drugs and endogenous neuroactive substances such as amino acids and monoamines, especially in microdialysis samples from experimental animals and humans. CE-LIFD trends are discussed: automated faster analysis with capillary array systems, resolution power improvement, higher detection sensitivity, and CE systems miniaturization for extremely small sample volume, in order to make CE easier and affordable to the lab bench or the clinical bed.
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Affiliation(s)
- X Páez
- Laboratory of Behavioral Physiology, Universidad de los Andes, Mérida, Venezuela.
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Saul'skaya NB, Mikhailova MO, Gorbachevskaya AI. Dopamine-dependent inhibition of glycine release in the nucleus accumbens of the rat brain during food consumption. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2001; 31:317-21. [PMID: 11430577 DOI: 10.1023/a:1010342803617] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Studies of Sprague-Dawley rats using in vivo intracerebral dialysis and high-performance liquid chromatography with electrochemical detection were used to investigate glycine release into the intercellular space of the nucleus accumbens during food consumption. The results showed that food consumption led to decreases in glycine levels in the intercellular space of the nucleus accumbens. Administration of the sodium channel blocker tetrodotoxin (1 microM), but not the glutamate reuptake blocker D,L-threo-hydroxyaspartate (1 mM), prevented the food-related behavior-induced decrease in glycine levels in the nucleus accumbens. Eating of food after administration of the dopamine D2 receptor blocker raclopride (10 microM) into the nucleus accumbens was accompanied by an increase in the glycine level in the intercellular space of this structure. These data provide evidence for the neural regulation of glycine release in the nucleus accumbens during food-related behavior, mediated via dopamine D2 receptors.
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Affiliation(s)
- N B Saul'skaya
- I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg
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Choi YH, Fletcher PJ, Anderson GH. Extracellular amino acid profiles in the paraventricular nucleus of the rat hypothalamus are influenced by diet composition. Brain Res 2001; 892:320-8. [PMID: 11172779 DOI: 10.1016/s0006-8993(00)03267-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
One possible mechanism by which food consumption signals feeding centers is through the resulting changes in amino acid profiles in the brain. In this study we examined the effect of voluntary consumption of a 50% protein diet or a 0% protein (carbohydrate) diet on extracellular amino acid profiles in the hypothalamic paraventricular nucleus (PVN) of freely moving rats from 1800 to 2100 h. Dialysates were continuously collected via microdialysis probes inserted in the PVN at 1500 h. Extracellular concentrations of isoleucine, leucine, methionine, tyrosine and valine were elevated within the first or second 20 min following the start of the 50% protein diet (P<0.05). The ratio of tryptophan to the total branched-chain amino acids (BCAA) in extracellular fluid increased following consumption of the carbohydrate diet (P<0.05), but decreased after the protein diet. An elevated ratio of tyrosine to BCAA was observed at the end of the measurement following the protein-free meal. It is concluded that amino acid concentrations in extracellular fluid of the PVN change rapidly after food consumption and that the changes are influenced by dietary composition.
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Affiliation(s)
- Y H Choi
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON M5S 3E2, Canada
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