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Watts AG, Kanoski SE, Sanchez-Watts G, Langhans W. The physiological control of eating: signals, neurons, and networks. Physiol Rev 2022; 102:689-813. [PMID: 34486393 PMCID: PMC8759974 DOI: 10.1152/physrev.00028.2020] [Citation(s) in RCA: 53] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 08/30/2021] [Indexed: 02/07/2023] Open
Abstract
During the past 30 yr, investigating the physiology of eating behaviors has generated a truly vast literature. This is fueled in part by a dramatic increase in obesity and its comorbidities that has coincided with an ever increasing sophistication of genetically based manipulations. These techniques have produced results with a remarkable degree of cell specificity, particularly at the cell signaling level, and have played a lead role in advancing the field. However, putting these findings into a brain-wide context that connects physiological signals and neurons to behavior and somatic physiology requires a thorough consideration of neuronal connections: a field that has also seen an extraordinary technological revolution. Our goal is to present a comprehensive and balanced assessment of how physiological signals associated with energy homeostasis interact at many brain levels to control eating behaviors. A major theme is that these signals engage sets of interacting neural networks throughout the brain that are defined by specific neural connections. We begin by discussing some fundamental concepts, including ones that still engender vigorous debate, that provide the necessary frameworks for understanding how the brain controls meal initiation and termination. These include key word definitions, ATP availability as the pivotal regulated variable in energy homeostasis, neuropeptide signaling, homeostatic and hedonic eating, and meal structure. Within this context, we discuss network models of how key regions in the endbrain (or telencephalon), hypothalamus, hindbrain, medulla, vagus nerve, and spinal cord work together with the gastrointestinal tract to enable the complex motor events that permit animals to eat in diverse situations.
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Affiliation(s)
- Alan G Watts
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Scott E Kanoski
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Graciela Sanchez-Watts
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Wolfgang Langhans
- Physiology and Behavior Laboratory, Eidgenössische Technische Hochschule-Zürich, Schwerzenbach, Switzerland
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Ujvári B, Pytel B, Márton Z, Bognár M, Kovács LÁ, Farkas J, Gaszner T, Berta G, Kecskés A, Kormos V, Farkas B, Füredi N, Gaszner B. Neurodegeneration in the centrally-projecting Edinger-Westphal nucleus contributes to the non-motor symptoms of Parkinson's disease in the rat. J Neuroinflammation 2022; 19:31. [PMID: 35109869 PMCID: PMC8809039 DOI: 10.1186/s12974-022-02399-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Accepted: 01/24/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The neuropathological background of major depression and anxiety as non-motor symptoms of Parkinson's disease is much less understood than classical motor symptoms. Although, neurodegeneration of the Edinger-Westphal nucleus in human Parkinson's disease is a known phenomenon, its possible significance in mood status has never been elucidated. In this work we aimed at investigating whether neuron loss and alpha-synuclein accumulation in the urocortin 1 containing (UCN1) cells of the centrally-projecting Edinger-Westphal (EWcp) nucleus is associated with anxiety and depression-like state in the rat. METHODS Systemic chronic rotenone administration as well as targeted leptin-saporin-induced lesions of EWcp/UCN1 neurons were conducted. Rotarod, open field and sucrose preference tests were performed to assess motor performance and mood status. Multiple immunofluorescence combined with RNAscope were used to reveal the functional-morphological changes. Two-sample Student's t test, Spearman's rank correlation analysis and Mann-Whitney U tests were used for statistics. RESULTS In the rotenone model, besides motor deficit, an anxious and depression-like phenotype was detected. Well-comparable neuron loss, cytoplasmic alpha-synuclein accumulation as well as astro- and microglial activation were observed both in the substantia nigra pars compacta and EWcp. Occasionally, UCN1-immunoreactive neuronal debris was observed in phagocytotic microglia. UCN1 peptide content of viable EWcp cells correlated with dopaminergic substantia nigra cell count. Importantly, other mood status-related dopaminergic (ventral tegmental area), serotonergic (dorsal and median raphe) and noradrenergic (locus ceruleus and A5 area) brainstem centers did not show remarkable morphological changes. Targeted partial selective EWcp/UCN1 neuron ablation induced similar mood status without motor symptoms. CONCLUSIONS Our findings collectively suggest that neurodegeneration of urocortinergic EWcp contributes to the mood-related non-motor symptoms in toxic models of Parkinson's disease in the rat.
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Affiliation(s)
- Balázs Ujvári
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary.,Centre for Neuroscience, University of Pécs, 7624, Pecs, Hungary
| | - Bence Pytel
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary
| | - Zsombor Márton
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary
| | - Máté Bognár
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary
| | - László Ákos Kovács
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary.,Centre for Neuroscience, University of Pécs, 7624, Pecs, Hungary
| | - József Farkas
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary.,Centre for Neuroscience, University of Pécs, 7624, Pecs, Hungary
| | - Tamás Gaszner
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary.,Centre for Neuroscience, University of Pécs, 7624, Pecs, Hungary
| | - Gergely Berta
- Department of Medical Biology, Medical School, University of Pécs, 7624, Pecs, Hungary
| | - Angéla Kecskés
- Department of Pharmacology and Pharmacotherapy, Medical School & Szentágothai Research Centre, Molecular Pharmacology Research Group, University of Pécs, 7624, Pecs, Hungary
| | - Viktória Kormos
- Department of Pharmacology and Pharmacotherapy, Medical School & Szentágothai Research Centre, Molecular Pharmacology Research Group, University of Pécs, 7624, Pecs, Hungary
| | - Boglárka Farkas
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary
| | - Nóra Füredi
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary.,Centre for Neuroscience, University of Pécs, 7624, Pecs, Hungary
| | - Balázs Gaszner
- Department of Anatomy, Research Group for Mood Disorders, Medical School, University of Pécs, Szigeti út 12., 7624, Pecs, Hungary. .,Centre for Neuroscience, University of Pécs, 7624, Pecs, Hungary.
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Sanna F, Bratzu J, Angioni L, Pina Sorighe M, Cocco C, Argiolas A, Melis MR. Oxytocin-conjugated saporin injected into the substantia nigra of male rats alters the activity of the nigrostriatal dopaminergic system: A behavioral and neurochemical study. Brain Res 2021; 1773:147705. [PMID: 34744015 DOI: 10.1016/j.brainres.2021.147705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/19/2021] [Accepted: 10/25/2021] [Indexed: 10/20/2022]
Abstract
Saporin conjugated to oxytocin (OXY-SAP) destroys neurons expressing oxytocinergic receptors. When injected unilaterally in the substantia nigra of male rats, OXY-SAP causes a dose-dependent decrease up to 55 % in nigral Tyrosine Hydroxylase (TH)-immunoreactivity compared to control mock peptide BLANK-SAP- and PBS-treated rats or the contralateral substantia nigra. TH decrease was parallel to a dopamine content decrease in the ipsilateral striatum compared to BLANK-SAP- or PBS-treated rats or the contralateral striatum. OXY-SAP-treated rats showed a small but significant increase of locomotor activity 28 days after intranigral injection in the Open field test compared to BLANK-SAP- or PBS-treated rats, in line with an inhibitory role of nigral oxytocin on locomotor activity. OXY-SAP-, but not BLANK-SAP- or PBS-treated rats, also showed marked dose-dependent rotational turning ipsilateral to the injected substantia nigra when challenged with d-amphetamine, but not with apomorphine. Under isoflurane anesthesia OXY-SAP-treated rats showed levels of extracellular dopamine in the dialysate from the ipsilateral striatum only half those of BLANK-SAP- or PBS-treated rats or the contralateral striatum. When treated with d-amphetamine, OXY-SAP_60/120 rats showed increased extracellular dopamine levels in the dialysate from the ipsilateral striatum two third/one third only of those found in BLANK-SAP- or PBS-treated rats or the contralateral striatum, respectively. These results show that OXY-SAP destroys nigrostriatal dopaminergic neurons expressing oxytocin receptors leading to a reduced striatal dopamine function.
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Affiliation(s)
- Fabrizio Sanna
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy.
| | - Jessica Bratzu
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy.
| | - Laura Angioni
- Department of Biomedical Sciences, Neuro-Endocrine-Fluorescence (NEF) Laboratory, University of Cagliari, Italy.
| | - Maria Pina Sorighe
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy.
| | - Cristina Cocco
- Department of Biomedical Sciences, Neuro-Endocrine-Fluorescence (NEF) Laboratory, University of Cagliari, Italy.
| | - Antonio Argiolas
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy; Centre of Excellence for the Neurobiology of Addictions, University of Cagliari, Cagliari, Italy; Institute of Neuroscience, National Research Council, Cagliari Section, University of Cagliari, Cagliari, Italy.
| | - Maria Rosaria Melis
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy; Centre of Excellence for the Neurobiology of Addictions, University of Cagliari, Cagliari, Italy.
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Harris RBS. Phosphorylation of STAT3 in hypothalamic nuclei is stimulated by lower doses of leptin than are needed to inhibit food intake. Am J Physiol Endocrinol Metab 2021; 321:E190-E201. [PMID: 34121448 PMCID: PMC8321824 DOI: 10.1152/ajpendo.00143.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/03/2021] [Accepted: 06/07/2021] [Indexed: 01/08/2023]
Abstract
This experiment investigated which hypothalamic nuclei were activated by a dose of leptin that inhibited food intake. Foodnot intake, energy expenditure, respiratory exchange ratio (RER), and intrascapular brown adipose tissue (IBAT) temperature were measured in male and female Sprague Dawley rats for 36 h following an intraperitoneal injection of 0, 50, 200, 500, or 1,000 µg leptin/kg with each rat tested with each dose of leptin in random order. In both males and females, RER and 12-h food intake were inhibited only by 1,000 µg leptin/kg, but there was no effect on energy expenditure or IBAT temperature. At the end of the experiment, phosphorylated signal transducer and activator of transcription 3 (pSTAT3) immunoreactivity was measured 1 h after injection of 0, 50, 500, or 1,000 µg leptin/kg. In male rats, the lowest dose of leptin produced a maximal activation of STAT3 in the Arc and nucleus of the solitary tract (NTS). There was no response in the dorsomedial hypothalamus, but there was a progressive increase in ventromedial nucleus of the hypothalamus (VMH) pSTAT3 with increasing doses of leptin. In female rats, there was no significant change in Arc and pSTAT3 NTS activation was maximal with 500 mg leptin/kg, but only the highest dose of leptin increased VMH pSTAT3. These results suggest that the VMH plays an important role in the energetic response to elevations of circulating leptin but do not exclude the possibility that multiple nuclei provide the appropriate integrated response to hyperleptinemia.NEW & NOTEWORTHY The results of this experiment show that doses of leptin too small to inhibit food intake produce a maximal response to leptin in the arcuate nucleus. By contrast the VMH shows a robust response that correlates with inhibition of food intake. This suggests that the VMH plays an important role in the energetic response to hyperleptinemia.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia
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Leptin Sensitizes NTS Neurons to Vagal Input by Increasing Postsynaptic NMDA Receptor Currents. J Neurosci 2020; 40:7054-7064. [PMID: 32817248 DOI: 10.1523/jneurosci.1865-19.2020] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/05/2019] [Accepted: 07/27/2020] [Indexed: 11/21/2022] Open
Abstract
Leptin signaling within the nucleus of the solitary tract (NTS) contributes to the control of food intake, and injections of leptin into the NTS reduce meal size and increase the efficacy of vagus-mediated satiation signals. Leptin receptors (LepRs) are expressed by vagal afferents as well as by a population of NTS neurons. However, the electrophysiological properties of LepR-expressing NTS neurons have not been well characterized, and it is unclear how leptin might act on these neurons to reduce food intake. To address this question, we recorded from LepR-expressing neurons in horizontal brain slices containing the NTS from male and female LepR-Cre X Rosa-tdTomato mice. We found that the vast majority of NTS LepR neurons received monosynaptic innervation from vagal afferent fibers and LepR neurons exhibited large synaptic NMDA receptor (NMDAR)-mediated currents compared with non-LepR neurons. During high-frequency stimulation of vagal afferents, leptin increased the size of NMDAR-mediated currents, but not AMPAR-mediated currents. Leptin also increased the size of evoked EPSPs and the ability of low-intensity solitary tract stimulation to evoke action potentials in LepR neurons. These effects of leptin were blocked by bath applying a competitive NMDAR antagonist (DCPP-ene) or by an NMDAR channel blocker applied through the recording pipette (MK-801). Last, feeding studies using male rats demonstrate that intra-NTS injections of DCPP-ene attenuate reduction of overnight food intake following intra-NTS leptin injection. Our results suggest that leptin acts in the NTS to reduce food intake by increasing NMDAR-mediated currents, thus enhancing NTS sensitivity to vagal inputs.SIGNIFICANCE STATEMENT Leptin is a hormone that critically impacts food intake and energy homeostasis. The nucleus of the solitary tract (NTS) is activated by vagal afferents from the gastrointestinal tract, which promotes termination of a meal. Injection of leptin into the NTS inhibits food intake, while knockdown of leptin receptors (LepRs) in NTS neurons increases food intake. However, little was known about how leptin acts in the NTS neurons to inhibit food intake. We found that leptin increases the sensitivity of LepR-expressing neurons to vagal inputs by increasing NMDA receptor-mediated synaptic currents and that NTS NMDAR activation contributes to leptin-induced reduction of food intake. These findings suggest a novel mechanism by which leptin, acting in the NTS, could potentiate gastrointestinal satiation signals.
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