1
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Heuer SE, Bloss EB, Howell GR. Strategies to dissect microglia-synaptic interactions during aging and in Alzheimer's disease. Neuropharmacology 2024; 254:109987. [PMID: 38705570 DOI: 10.1016/j.neuropharm.2024.109987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/29/2024] [Accepted: 05/02/2024] [Indexed: 05/07/2024]
Abstract
Age is the largest risk factor for developing Alzheimer's disease (AD), a neurodegenerative disorder that causes a progressive and severe dementia. The underlying cause of cognitive deficits seen in AD is thought to be the disconnection of neural circuits that control memory and executive functions. Insight into the mechanisms by which AD diverges from normal aging will require identifying precisely which cellular events are driven by aging and which are impacted by AD-related pathologies. Since microglia, the brain-resident macrophages, are known to have critical roles in the formation and maintenance of neural circuits through synaptic pruning, they are well-positioned to modulate synaptic connectivity in circuits sensitive to aging or AD. In this review, we provide an overview of the current state of the field and on emerging technologies being employed to elucidate microglia-synaptic interactions in aging and AD. We also discuss the importance of leveraging genetic diversity to study how these interactions are shaped across more realistic contexts. We propose that these approaches will be essential to define specific aging- and disease-relevant trajectories for more personalized therapeutics aimed at reducing the effects of age or AD pathologies on the brain. This article is part of the Special Issue on "Microglia".
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Affiliation(s)
- Sarah E Heuer
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Erik B Bloss
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA; Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, 04469, USA.
| | - Gareth R Howell
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA; Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, 04469, USA.
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2
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Griffin H, Hanson J, Phelan KD, Baldini G. MC4R Localizes at Excitatory Postsynaptic and Peri-Postsynaptic Sites of Hypothalamic Neurons in Primary Culture. Cells 2024; 13:1235. [PMID: 39120267 PMCID: PMC11311852 DOI: 10.3390/cells13151235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 07/13/2024] [Accepted: 07/18/2024] [Indexed: 08/10/2024] Open
Abstract
The melanocortin-4 receptor (MC4R) is a G protein-coupled receptor (GPCR) that is expressed in several brain locations encompassing the hypothalamus and the brainstem, where the receptor controls several body functions, including metabolism. In a well-defined pathway to decrease appetite, hypothalamic proopiomelanocortin (POMC) neurons localized in the arcuate nucleus (Arc) project to MC4R neurons in the paraventricular nuclei (PVN) to release the natural MC4R agonist α-melanocyte-stimulating hormone (α-MSH). Arc neurons also project excitatory glutamatergic fibers to the MC4R neurons in the PVN for a fast synaptic transmission to regulate a satiety pathway potentiated by α-MSH. By using super-resolution microscopy, we found that in hypothalamic neurons in a primary culture, postsynaptic density protein 95 (PSD95) colocalizes with GluN1, a subunit of the ionotropic N-methyl-D-aspartate receptor (NMDAR). Thus, hypothalamic neurons form excitatory postsynaptic specializations. To study the MC4R distribution at these sites, tagged HA-MC4R under the synapsin promoter was expressed in neurons by adeno-associated virus (AAV) gene transduction. HA-MC4R immunofluorescence peaked at the center and in proximity to the PSD95- and NMDAR-expressing sites. These data provide morphological evidence that MC4R localizes together with glutamate receptors at postsynaptic and peri-postsynaptic sites.
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Affiliation(s)
- Haven Griffin
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (H.G.); (J.H.)
| | - Jude Hanson
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (H.G.); (J.H.)
| | - Kevin D. Phelan
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA;
| | - Giulia Baldini
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (H.G.); (J.H.)
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3
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Dodt S, Widdershooven NV, Dreisow ML, Weiher L, Steuernagel L, Wunderlich FT, Brüning JC, Fenselau H. NPY-mediated synaptic plasticity in the extended amygdala prioritizes feeding during starvation. Nat Commun 2024; 15:5439. [PMID: 38937485 PMCID: PMC11211344 DOI: 10.1038/s41467-024-49766-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 06/18/2024] [Indexed: 06/29/2024] Open
Abstract
Efficient control of feeding behavior requires the coordinated adjustment of complex motivational and affective neurocircuits. Neuropeptides from energy-sensing hypothalamic neurons are potent feeding modulators, but how these endogenous signals shape relevant circuits remains unclear. Here, we examine how the orexigenic neuropeptide Y (NPY) adapts GABAergic inputs to the bed nucleus of the stria terminalis (BNST). We find that fasting increases synaptic connectivity between agouti-related peptide (AgRP)-expressing 'hunger' and BNST neurons, a circuit that promotes feeding. In contrast, GABAergic input from the central amygdala (CeA), an extended amygdala circuit that decreases feeding, is reduced. Activating NPY-expressing AgRP neurons evokes these synaptic adaptations, which are absent in NPY-deficient mice. Moreover, fasting diminishes the ability of CeA projections in the BNST to suppress food intake, and NPY-deficient mice fail to decrease anxiety in order to promote feeding. Thus, AgRP neurons drive input-specific synaptic plasticity, enabling a selective shift in hunger and anxiety signaling during starvation through NPY.
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Affiliation(s)
- Stephan Dodt
- Synaptic Transmission in Energy Homeostasis Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
| | - Noah V Widdershooven
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
| | - Marie-Luise Dreisow
- Synaptic Transmission in Energy Homeostasis Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Center for Endocrinology, Diabetes and Preventive Medicine (CEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
| | - Lisa Weiher
- Synaptic Transmission in Energy Homeostasis Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
| | - Lukas Steuernagel
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
| | - F Thomas Wunderlich
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany
- Center for Endocrinology, Diabetes and Preventive Medicine (CEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Straße 26, Cologne, 50931, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Straße 21, 50931, Cologne, Germany
| | - Jens C Brüning
- Department of Neuronal Control of Metabolism, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany.
- Center for Endocrinology, Diabetes and Preventive Medicine (CEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany.
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Straße 26, Cologne, 50931, Germany.
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Straße 21, 50931, Cologne, Germany.
| | - Henning Fenselau
- Synaptic Transmission in Energy Homeostasis Group, Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Cologne, Germany.
- Center for Endocrinology, Diabetes and Preventive Medicine (CEDP), University Hospital Cologne, Kerpener Strasse 26, 50924, Cologne, Germany.
- Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Straße 26, Cologne, 50931, Germany.
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4
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Sayar-Atasoy N, Yavuz Y, Laule C, Dong C, Kim H, Rysted J, Flippo K, Davis D, Aklan I, Yilmaz B, Tian L, Atasoy D. Opioidergic signaling contributes to food-mediated suppression of AgRP neurons. Cell Rep 2024; 43:113630. [PMID: 38165803 PMCID: PMC10865729 DOI: 10.1016/j.celrep.2023.113630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/22/2023] [Accepted: 12/13/2023] [Indexed: 01/04/2024] Open
Abstract
Opioids are generally known to promote hedonic food consumption. Although much of the existing evidence is primarily based on studies of the mesolimbic pathway, endogenous opioids and their receptors are widely expressed in hypothalamic appetite circuits as well; however, their role in homeostatic feeding remains unclear. Using a fluorescent opioid sensor, deltaLight, here we report that mediobasal hypothalamic opioid levels increase by feeding, which directly and indirectly inhibits agouti-related protein (AgRP)-expressing neurons through the μ-opioid receptor (MOR). AgRP-specific MOR expression increases by energy surfeit and contributes to opioid-induced suppression of appetite. Conversely, its antagonists diminish suppression of AgRP neuron activity by food and satiety hormones. Mice with AgRP neuron-specific ablation of MOR expression have increased fat preference without increased motivation. These results suggest that post-ingestion release of endogenous opioids contributes to AgRP neuron inhibition to shape food choice through MOR signaling.
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Affiliation(s)
- Nilufer Sayar-Atasoy
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Yavuz Yavuz
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Physiology, School of Medicine, Yeditepe University, Istanbul 34755, Turkey
| | - Connor Laule
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Chunyang Dong
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Hyojin Kim
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Jacob Rysted
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Kyle Flippo
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Debbie Davis
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Iltan Aklan
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Bayram Yilmaz
- Department of Physiology, School of Medicine, Yeditepe University, Istanbul 34755, Turkey
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Deniz Atasoy
- Department of Neuroscience and Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Fraternal Order of Eagles Diabetes Research Center (FOEDRC), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
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5
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Sayar-Atasoy N, Laule C, Aklan I, Kim H, Yavuz Y, Ates T, Coban I, Koksalar-Alkan F, Rysted J, Davis D, Singh U, Alp MI, Yilmaz B, Cui H, Atasoy D. Adrenergic modulation of melanocortin pathway by hunger signals. Nat Commun 2023; 14:6602. [PMID: 37857606 PMCID: PMC10587058 DOI: 10.1038/s41467-023-42362-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 10/09/2023] [Indexed: 10/21/2023] Open
Abstract
Norepinephrine (NE) is a well-known appetite regulator, and the nor/adrenergic system is targeted by several anti-obesity drugs. To better understand the circuitry underlying adrenergic appetite control, here we investigated the paraventricular hypothalamic nucleus (PVN), a key brain region that integrates energy signals and receives dense nor/adrenergic input, using a mouse model. We found that PVN NE level increases with signals of energy deficit and decreases with food access. This pattern is recapitulated by the innervating catecholaminergic axon terminals originating from NTSTH-neurons. Optogenetic activation of rostral-NTSTH → PVN projection elicited strong motivation to eat comparable to overnight fasting whereas its inhibition attenuated both fasting-induced & hypoglycemic feeding. We found that NTSTH-axons functionally targeted PVNMC4R-neurons by predominantly inhibiting them, in part, through α1-AR mediated potentiation of GABA release from ARCAgRP presynaptic terminals. Furthermore, glucoprivation suppressed PVNMC4R activity, which was required for hypoglycemic feeding response. These results define an ascending nor/adrenergic circuit, NTSTH → PVNMC4R, that conveys peripheral hunger signals to melanocortin pathway.
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Affiliation(s)
- Nilufer Sayar-Atasoy
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Connor Laule
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Iltan Aklan
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Hyojin Kim
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Yavuz Yavuz
- Department of Physiology, School of Medicine, Yeditepe University, Istanbul, Turkey
| | - Tayfun Ates
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Ilknur Coban
- Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | | | - Jacob Rysted
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Debbie Davis
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Uday Singh
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Muhammed Ikbal Alp
- Department of Physiology, School of Medicine, Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, Istanbul, Turkey
| | - Bayram Yilmaz
- Department of Physiology, School of Medicine, Yeditepe University, Istanbul, Turkey
| | - Huxing Cui
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Deniz Atasoy
- Department of Pharmacology, Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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6
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Kim EM, Quinn JG, Reid RE, O'Hare E. Evidence for a feeding related association between melanocortin in the NTS and Neuropeptide-Y in the PVN. Appetite 2023; 188:106618. [PMID: 37257508 DOI: 10.1016/j.appet.2023.106618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/26/2023] [Accepted: 05/27/2023] [Indexed: 06/02/2023]
Abstract
Melanocortin and neuropeptide-Y (NPY) are both involved in feeding and energy regulation, and they have opposite effects in the paraventricular nucleus of the hypothalamus (PVN). The present study examined an interaction between melanocortin in the nucleus of the solitary tract (NTS) and NPY in the PVN. Male Sprague-Dawley rats were implanted with cannulae in the injection sites of interest. In Experiment 1, subjects received either the melanocortin 3/4-receptor (MC3/4) antagonist SHU9119 (0, 10, 50 and 100 pmol/0.5 μl) or the MC3/4 agonist MTII (0, 10, 50, 100 and 200 pmol/0.5 μl) into the NTS. Food intake was measured at 1, 2, 4, 6 and 24-h post-injection. Administration of SHU9119 into the NTS significantly and dose-dependently increased food intake at 1, 2, 4, 6 and 6-24-h, and administration of MTII into the NTS significantly and dose-dependently decreased 24-h free feeding. In Experiment 2, subjects received the MC3/4 agonist MTII (0, 10, 50, 100 and 200 pmol/0.5 μl) into the NTS just prior to NPY (0 and 1μg/0.5 μl) in the PVN. PVN injection of NPY stimulated feeding, and administration of MTII (50, 100 and 200 pmol) into the NTS significantly and dose-dependently decreased NPY-induced feeding at 2, 4, 6 and 6-24-h. These data suggest that there could be a neuronal association between melanocortin in the NTS and NPY in the PVN, and that the melanocortin system in the NTS has an antagonistic effect on NPY-induced feeding in the PVN.
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Affiliation(s)
- E-M Kim
- School of Psychology, Ulster University, Cromore Road, Coleraine, Northern Ireland, UK.
| | - J G Quinn
- School of Medicine, Queen's University Belfast, Northern Ireland, UK
| | - R E Reid
- School of Psychology, Dublin Business School, Ireland
| | - E O'Hare
- School of Psychology, Queen's University Belfast, Northern Ireland, UK
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7
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Douglass AM, Resch JM, Madara JC, Kucukdereli H, Yizhar O, Grama A, Yamagata M, Yang Z, Lowell BB. Neural basis for fasting activation of the hypothalamic-pituitary-adrenal axis. Nature 2023; 620:154-162. [PMID: 37495689 PMCID: PMC11168300 DOI: 10.1038/s41586-023-06358-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 06/21/2023] [Indexed: 07/28/2023]
Abstract
Fasting initiates a multitude of adaptations to allow survival. Activation of the hypothalamic-pituitary-adrenal (HPA) axis and subsequent release of glucocorticoid hormones is a key response that mobilizes fuel stores to meet energy demands1-5. Despite the importance of the HPA axis response, the neural mechanisms that drive its activation during energy deficit are unknown. Here, we show that fasting-activated hypothalamic agouti-related peptide (AgRP)-expressing neurons trigger and are essential for fasting-induced HPA axis activation. AgRP neurons do so through projections to the paraventricular hypothalamus (PVH), where, in a mechanism not previously described for AgRP neurons, they presynaptically inhibit the terminals of tonically active GABAergic afferents from the bed nucleus of the stria terminalis (BNST) that otherwise restrain activity of corticotrophin-releasing hormone (CRH)-expressing neurons. This disinhibition of PVHCrh neurons requires γ-aminobutyric acid (GABA)/GABA-B receptor signalling and potently activates the HPA axis. Notably, stimulation of the HPA axis by AgRP neurons is independent of their induction of hunger, showing that these canonical 'hunger neurons' drive many distinctly different adaptations to the fasted state. Together, our findings identify the neural basis for fasting-induced HPA axis activation and uncover a unique means by which AgRP neurons activate downstream neurons: through presynaptic inhibition of GABAergic afferents. Given the potency of this disinhibition of tonically active BNST afferents, other activators of the HPA axis, such as psychological stress, may also work by reducing BNST inhibitory tone onto PVHCrh neurons.
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Affiliation(s)
- Amelia M Douglass
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Jon M Resch
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
- Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Joseph C Madara
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Hakan Kucukdereli
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Ofer Yizhar
- Departments of Brain Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
| | - Abhinav Grama
- Center for Brain Science, Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Masahito Yamagata
- Center for Brain Science, Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Zongfang Yang
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
- Program in Neuroscience, Harvard Medical School, Boston, MA, USA.
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8
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Zhang SX, Kim A, Madara JC, Zhu PK, Christenson LF, Lutas A, Kalugin PN, Jin Y, Pal A, Tian L, Lowell BB, Andermann ML. Competition between stochastic neuropeptide signals calibrates the rate of satiation. RESEARCH SQUARE 2023:rs.3.rs-3185572. [PMID: 37546985 PMCID: PMC10402269 DOI: 10.21203/rs.3.rs-3185572/v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
We investigated how transmission of hunger- and satiety-promoting neuropeptides, NPY and αMSH, is integrated at the level of intracellular signaling to control feeding. Receptors for these peptides use the second messenger cAMP. How cAMP integrates opposing peptide signals to regulate energy balance, and the in vivo spatiotemporal dynamics of endogenous peptidergic signaling, remain largely unknown. We show that AgRP axon stimulation in the paraventricular hypothalamus evokes probabilistic NPY release that triggers stochastic cAMP decrements in downstream MC4R-expressing neurons (PVHMC4R). Meanwhile, POMC axon stimulation triggers stochastic, αMSH-dependent cAMP increments. Release of either peptide impacts a ~100 μm diameter region, and when these peptide signals overlap, they compete to control cAMP. The competition is reflected by hunger-state-dependent differences in the amplitude and persistence of cAMP transients: hunger peptides are more efficacious in the fasted state, satiety peptides in the fed state. Feeding resolves the competition by simultaneously elevating αMSH release and suppressing NPY release, thereby sustaining elevated cAMP in PVHMC4R neurons. In turn, cAMP potentiates feeding-related excitatory inputs and promotes satiation across minutes. Our findings highlight how biochemical integration of opposing, quantal peptide signals during energy intake orchestrates a gradual transition between stable states of hunger and satiety.
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Affiliation(s)
- Stephen X Zhang
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
- Co-corresponding authors
| | - Angela Kim
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Joseph C Madara
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Paula K Zhu
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Lauren F Christenson
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Andrew Lutas
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
- Present address: Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Peter N Kalugin
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
- Program in Neuroscience, Harvard University, Cambridge, MA 02138, USA
| | - Yihan Jin
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Sacramento, CA 95817, USA
| | - Akash Pal
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Sacramento, CA 95817, USA
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Sacramento, CA 95817, USA
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Mark L Andermann
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
- Program in Neuroscience, Harvard University, Cambridge, MA 02138, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
- Co-corresponding authors
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9
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Zhang SX, Kim A, Madara JC, Zhu PK, Christenson LF, Lutas A, Kalugin PN, Jin Y, Pal A, Tian L, Lowell BB, Andermann ML. Competition between stochastic neuropeptide signals calibrates the rate of satiation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.11.548551. [PMID: 37503012 PMCID: PMC10369917 DOI: 10.1101/2023.07.11.548551] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
We investigated how transmission of hunger- and satiety-promoting neuropeptides, NPY and αMSH, is integrated at the level of intracellular signaling to control feeding. Receptors for these peptides use the second messenger cAMP, but the messenger's spatiotemporal dynamics and role in energy balance are controversial. We show that AgRP axon stimulation in the paraventricular hypothalamus evokes probabilistic and spatially restricted NPY release that triggers stochastic cAMP decrements in downstream MC4R-expressing neurons (PVH MC4R ). Meanwhile, POMC axon stimulation triggers stochastic, αMSH-dependent cAMP increments. NPY and αMSH competitively control cAMP, as reflected by hunger-state-dependent differences in the amplitude and persistence of cAMP transients evoked by each peptide. During feeding bouts, elevated αMSH release and suppressed NPY release cooperatively sustain elevated cAMP in PVH MC4R neurons, thereby potentiating feeding-related excitatory inputs and promoting satiation across minutes. Our findings highlight how state-dependent integration of opposing, quantal peptidergic events by a common biochemical target calibrates energy intake.
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10
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A multifunctional peroxidase-based reaction for imaging, sensing and networking of spatial biology. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119428. [PMID: 36610614 DOI: 10.1016/j.bbamcr.2022.119428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 12/22/2022] [Accepted: 12/29/2022] [Indexed: 01/06/2023]
Abstract
Peroxidase is a heme-containing enzyme that reduces hydrogen peroxide to water by extracting electron(s) from aromatic compounds via a sequential turnover reaction. This reaction can generate various aromatic radicals in the form of short-lived "spray" molecules. These can be either covalently attached to proximal proteins or polymerized via radical-radical coupling. Recent studies have shown that these peroxidase-generated radicals can be utilized as effective tools for spatial research in biological systems, including imaging studies aimed at the spatial localization of proteins using electron microscopy, spatial proteome mapping, and spatial sensing of metabolites (e.g., heme and hydrogen peroxide). This review may facilitate the wider utilization of these peroxidase-based methods for spatial discovery in cellular biology.
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11
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Ayuso-Jimeno IP, Ronchi P, Wang T, Gallori CE, Gross CT. Identifying long-range synaptic inputs using genetically encoded labels and volume electron microscopy. Sci Rep 2022; 12:10213. [PMID: 35715545 PMCID: PMC9205864 DOI: 10.1038/s41598-022-14309-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 06/06/2022] [Indexed: 11/08/2022] Open
Abstract
Enzymes that facilitate the local deposition of electron dense reaction products have been widely used as labels in electron microscopy (EM) for the identification of synaptic contacts in neural tissue. Peroxidases, in particular, can efficiently metabolize 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) to produce precipitates with high contrast under EM following heavy metal staining, and can be genetically encoded to facilitate the labeling of specific cell-types or organelles. Nevertheless, the peroxidase/DAB method has so far not been reported to work in a multiplexed manner in combination with 3D volume EM techniques (e.g. Serial blockface electron microscopy, SBEM; Focused ion beam electron microscopy, FIBSEM) that are favored for the large-scale ultrastructural assessment of synaptic architecture However, a recently described peroxidase with enhanced enzymatic activity (dAPEX2) can efficienty deposit EM-visible DAB products in thick tissue without detergent treatment opening the possibility for the multiplex labeling of genetically defined cell-types in combination with volume EM methods. Here we demonstrate that multiplexed dAPEX2/DAB tagging is compatible with both FIBSEM and SBEM volume EM approaches and use them to map long-range genetically identified synaptic inputs from the anterior cingulate cortex to the periaqueductal gray in the mouse brain.
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Affiliation(s)
- Irene P Ayuso-Jimeno
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Via Ramarini 32, 00015, Monterotondo, RM, Italy
| | - Paolo Ronchi
- Electron Microscopy Core Facility (EMCF), European Molecular Biology Laboratory (EMBL), 69117, Meyerhofstr, Germany
| | - Tianzi Wang
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Via Ramarini 32, 00015, Monterotondo, RM, Italy
| | - Catherine E Gallori
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Via Ramarini 32, 00015, Monterotondo, RM, Italy
| | - Cornelius T Gross
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Via Ramarini 32, 00015, Monterotondo, RM, Italy.
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12
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Bosch C, Ackels T, Pacureanu A, Zhang Y, Peddie CJ, Berning M, Rzepka N, Zdora MC, Whiteley I, Storm M, Bonnin A, Rau C, Margrie T, Collinson L, Schaefer AT. Functional and multiscale 3D structural investigation of brain tissue through correlative in vivo physiology, synchrotron microtomography and volume electron microscopy. Nat Commun 2022; 13:2923. [PMID: 35614048 PMCID: PMC9132960 DOI: 10.1038/s41467-022-30199-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 04/19/2022] [Indexed: 12/16/2022] Open
Abstract
Understanding the function of biological tissues requires a coordinated study of physiology and structure, exploring volumes that contain complete functional units at a detail that resolves the relevant features. Here, we introduce an approach to address this challenge: Mouse brain tissue sections containing a region where function was recorded using in vivo 2-photon calcium imaging were stained, dehydrated, resin-embedded and imaged with synchrotron X-ray computed tomography with propagation-based phase contrast (SXRT). SXRT provided context at subcellular detail, and could be followed by targeted acquisition of multiple volumes using serial block-face electron microscopy (SBEM). In the olfactory bulb, combining SXRT and SBEM enabled disambiguation of in vivo-assigned regions of interest. In the hippocampus, we found that superficial pyramidal neurons in CA1a displayed a larger density of spine apparati than deeper ones. Altogether, this approach can enable a functional and structural investigation of subcellular features in the context of cells and tissues.
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Affiliation(s)
- Carles Bosch
- Sensory Circuits and Neurotechnology Lab., The Francis Crick Institute, London, UK.
| | - Tobias Ackels
- Sensory Circuits and Neurotechnology Lab., The Francis Crick Institute, London, UK
- Department of Neuroscience, Physiology and Pharmacology, University College, London, UK
| | - Alexandra Pacureanu
- Sensory Circuits and Neurotechnology Lab., The Francis Crick Institute, London, UK
- Department of Neuroscience, Physiology and Pharmacology, University College, London, UK
- ESRF, The European Synchrotron, Grenoble, France
| | - Yuxin Zhang
- Sensory Circuits and Neurotechnology Lab., The Francis Crick Institute, London, UK
- Department of Neuroscience, Physiology and Pharmacology, University College, London, UK
| | | | - Manuel Berning
- Department of Connectomics, Max Planck Institute for Brain Research, Frankfurt am Main, Germany
- Scalable minds GmbH, Potsdam, Germany
| | | | - Marie-Christine Zdora
- Department of Physics and Astronomy, University College London, London, UK
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
- School of Physics and Astronomy, University of Southampton, Highfield Campus, Southampton, UK
| | - Isabell Whiteley
- Sensory Circuits and Neurotechnology Lab., The Francis Crick Institute, London, UK
- Department of Neuroscience, Physiology and Pharmacology, University College, London, UK
| | - Malte Storm
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
- Institute of Materials Physics, Helmholtz-Zentrum Hereon, Geesthacht, Germany
| | - Anne Bonnin
- Paul Scherrer Institut, Villigen, Switzerland
| | - Christoph Rau
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Troy Margrie
- Sainsbury Wellcome Centre, University College London, London, UK
| | - Lucy Collinson
- Electron Microscopy STP, The Francis Crick Institute, London, UK
| | - Andreas T Schaefer
- Sensory Circuits and Neurotechnology Lab., The Francis Crick Institute, London, UK.
- Department of Neuroscience, Physiology and Pharmacology, University College, London, UK.
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13
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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: 59] [Impact Index Per Article: 29.5] [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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14
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Ammer G, Vieira RM, Fendl S, Borst A. Anatomical distribution and functional roles of electrical synapses in Drosophila. Curr Biol 2022; 32:2022-2036.e4. [DOI: 10.1016/j.cub.2022.03.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 02/16/2022] [Accepted: 03/14/2022] [Indexed: 10/18/2022]
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15
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Rah JC, Choi JH. Finding Needles in a Haystack with Light: Resolving the Microcircuitry of the Brain with Fluorescence Microscopy. Mol Cells 2022; 45:84-92. [PMID: 35236783 PMCID: PMC8907002 DOI: 10.14348/molcells.2022.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 12/20/2021] [Indexed: 11/30/2022] Open
Abstract
To understand the microcircuitry of the brain, the anatomical and functional connectivity among neurons must be resolved. One of the technical hurdles to achieving this goal is that the anatomical connections, or synapses, are often smaller than the diffraction limit of light and thus are difficult to resolve by conventional microscopy, while the microcircuitry of the brain is on the scale of 1 mm or larger. To date, the gold standard method for microcircuit reconstruction has been electron microscopy (EM). However, despite its rapid development, EM has clear shortcomings as a method for microcircuit reconstruction. The greatest weakness of this method is arguably its incompatibility with functional and molecular analysis. Fluorescence microscopy, on the other hand, is readily compatible with numerous physiological and molecular analyses. We believe that recent advances in various fluorescence microscopy techniques offer a new possibility for reliable synapse detection in large volumes of neural circuits. In this minireview, we summarize recent advances in fluorescence-based microcircuit reconstruction. In the same vein as these studies, we introduce our recent efforts to analyze the long-range connectivity among brain areas and the subcellular distribution of synapses of interest in relatively large volumes of cortical tissue with array tomography and superresolution microscopy.
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Affiliation(s)
- Jong-Cheol Rah
- Laboratory of Neurophysiology, Korea Brain Research Institute, Daegu 41062, Korea
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, Korea
| | - Joon Ho Choi
- Laboratory of Neurophysiology, Korea Brain Research Institute, Daegu 41062, Korea
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16
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Takemoto K. [Optical inactivation of molecular functions in vivo by chromophore-assisted light inactivation]. Nihon Yakurigaku Zasshi 2022; 157:238-243. [PMID: 35781452 DOI: 10.1254/fpj.22009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Many biological phenomena have spatio-temporal characteristics, such as the expression of molecular activity locally or at a limited time. Such phenomena have been observed in various organisms from slime mold to mammals, and are considered to be one of the basic patterns in biological reactions. Live imaging studies using the fluorescent protein GFP and fluorescence microscopy have become a standard technique in the life sciences to reveal the dynamics of these characteristic biological phenomena. On the other hand, the characteristic behaviors of molecules and cells captured by microscopy only correlate with life phenomena, and the causal relationship of whether they really matter is unknown. It is unclear whether they are really important or not. Therefore, to elucidate their physiological significance, it is important to introduce spatiotemporal manipulation techniques to manipulate molecules and cells locally and at arbitrary timing, and to perform causal analysis in vivo. The chromophore-assisted light inactivation (CALI) method, which uses light to inactivate molecular functions, is an optical technology that enables such spatiotemporal manipulation, and has recently been used in vivo in various model organisms, attracting widespread attention. In this section, we will review the principle of the CALI method, actual research examples, in particular, its in vivo application, and future prospects.
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Affiliation(s)
- Kiwamu Takemoto
- Department of Biochemistry, Mie University, Graduate School of Medicine
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17
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Kim GT, Bahn S, Kim N, Choi JH, Kim JS, Rah JC. Efficient and Accurate Synapse Detection With Selective Structured Illumination Microscopy on the Putative Regions of Interest of Ultrathin Serial Sections. Front Neuroanat 2021; 15:759816. [PMID: 34867216 PMCID: PMC8634652 DOI: 10.3389/fnana.2021.759816] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/08/2021] [Indexed: 11/13/2022] Open
Abstract
Critical determinants of synaptic functions include subcellular locations, input sources, and specific molecular characteristics. However, there is not yet a reliable and efficient method that can detect synapses. Electron microscopy is a gold-standard method to detect synapses due to its exceedingly high spatial resolution. However, it requires laborious and time-consuming sample preparation and lengthy imaging time with limited labeling methods. Recent advances in various fluorescence microscopy methods have highlighted fluorescence microscopy as a substitute for electron microscopy in reliable synapse detection in a large volume of neural circuits. In particular, array tomography has been verified as a useful tool for neural circuit reconstruction. To further improve array tomography, we developed a novel imaging method, called “structured illumination microscopy on the putative region of interest on ultrathin sections”, which enables efficient and accurate detection of synapses-of-interest. Briefly, based on low-magnification conventional fluorescence microscopy images, synapse candidacy was determined. Subsequently, the coordinates of the regions with candidate synapses were imaged using super-resolution structured illumination microscopy. Using this system, synapses from the high-order thalamic nucleus, the posterior medial nucleus in the barrel cortex were rapidly and accurately imaged.
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Affiliation(s)
- Gyeong Tae Kim
- Korea Brain Research Institute, Daegu, South Korea.,Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Sangkyu Bahn
- Korea Brain Research Institute, Daegu, South Korea
| | - Nari Kim
- Korea Brain Research Institute, Daegu, South Korea
| | - Joon Ho Choi
- Korea Brain Research Institute, Daegu, South Korea
| | - Jinseop S Kim
- Korea Brain Research Institute, Daegu, South Korea.,Department of Biological Sciences, Sungkyunkwan University, Suwon, South Korea
| | - Jong-Cheol Rah
- Korea Brain Research Institute, Daegu, South Korea.,Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
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18
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Steinkellner T, Madany M, Haberl MG, Zell V, Li C, Hu J, Mackey M, Ramachandra R, Adams S, Ellisman MH, Hnasko TS, Boassa D. Genetic Probe for Visualizing Glutamatergic Synapses and Vesicles by 3D Electron Microscopy. ACS Chem Neurosci 2021; 12:626-639. [PMID: 33522227 PMCID: PMC7899175 DOI: 10.1021/acschemneuro.0c00643] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/19/2021] [Indexed: 01/21/2023] Open
Abstract
Communication between neurons relies on the release of diverse neurotransmitters, which represent a key-defining feature of a neuron's chemical and functional identity. Neurotransmitters are packaged into vesicles by specific vesicular transporters. However, tools for labeling and imaging synapses and synaptic vesicles based on their neurochemical identity remain limited. We developed a genetically encoded probe to identify glutamatergic synaptic vesicles at the levels of both light and electron microscopy (EM) by fusing the mini singlet oxygen generator (miniSOG) probe to an intralumenal loop of the vesicular glutamate transporter-2. We then used a 3D imaging method, serial block-face scanning EM, combined with a deep learning approach for automatic segmentation of labeled synaptic vesicles to assess the subcellular distribution of transporter-defined vesicles at nanometer scale. These tools represent a new resource for accessing the subcellular structure and molecular machinery of neurotransmission and for transmitter-defined tracing of neuronal connectivity.
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Affiliation(s)
- Thomas Steinkellner
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Institute of Pharmacology, Center for Physiology and
Pharmacology, Medical University of Vienna, Vienna 1090,
Austria
| | - Matthew Madany
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Matthias G. Haberl
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
- Charité−Universitätsmedizin
Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität
zu Berlin, and Berlin Institute of Health, Neuroscience Research Center,
Berlin 10117, Germany
| | - Vivien Zell
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
| | - Carolina Li
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Junru Hu
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Mason Mackey
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Ranjan Ramachandra
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Stephen Adams
- Department of Pharmacology, University of
California, San Diego, La Jolla California 92093, United
States
| | - Mark H. Ellisman
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
| | - Thomas S. Hnasko
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Research Service, VA San Diego Healthcare
System, San Diego, California 92161, United
States
| | - Daniela Boassa
- Department of Neurosciences, University
of California, San Diego, La Jolla, California 92093, United
States
- Center for Research in Biological Systems, National
Center for Microscopy and Imaging Research, University of California, San
Diego, La Jolla, California 92093, United States
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19
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Minehart JA, Speer CM. A Picture Worth a Thousand Molecules-Integrative Technologies for Mapping Subcellular Molecular Organization and Plasticity in Developing Circuits. Front Synaptic Neurosci 2021; 12:615059. [PMID: 33469427 PMCID: PMC7813761 DOI: 10.3389/fnsyn.2020.615059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/07/2020] [Indexed: 12/23/2022] Open
Abstract
A key challenge in developmental neuroscience is identifying the local regulatory mechanisms that control neurite and synaptic refinement over large brain volumes. Innovative molecular techniques and high-resolution imaging tools are beginning to reshape our view of how local protein translation in subcellular compartments drives axonal, dendritic, and synaptic development and plasticity. Here we review recent progress in three areas of neurite and synaptic study in situ-compartment-specific transcriptomics/translatomics, targeted proteomics, and super-resolution imaging analysis of synaptic organization and development. We discuss synergies between sequencing and imaging techniques for the discovery and validation of local molecular signaling mechanisms regulating synaptic development, plasticity, and maintenance in circuits.
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Affiliation(s)
| | - Colenso M. Speer
- Department of Biology, University of Maryland, College Park, MD, United States
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20
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TAKEMOTO K. Optical manipulation of molecular function by chromophore-assisted light inactivation. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2021; 97:197-209. [PMID: 33840676 PMCID: PMC8062263 DOI: 10.2183/pjab.97.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
In addition to simple on/off switches for molecular activity, spatiotemporal dynamics are also thought to be important for the regulation of cellular function. However, their physiological significance and in vivo importance remain largely unknown. Fluorescence imaging technology is a powerful technique that can reveal the spatiotemporal dynamics of molecular activity. In addition, because imaging detects the correlations between molecular activity and biological phenomena, the technique of molecular manipulation is also important to analyze causal relationships. Recent advances in optical manipulation techniques that artificially perturb molecules and cells via light can address this issue to elucidate the causality between manipulated target and its physiological function. The use of light enables the manipulation of molecular activity in microspaces, such as organelles and nerve spines. In this review, we describe the chromophore-assisted light inactivation method, which is an optical manipulation technique that has been attracting attention in recent years.
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Affiliation(s)
- Kiwamu TAKEMOTO
- Department of Biochemistry, Mie University, Graduate School of Medicine, Tsu-City, Mie, Japan
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21
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Hypothalamic Pomc Neurons Innervate the Spinal Cord and Modulate the Excitability of Premotor Circuits. Curr Biol 2020; 30:4579-4593.e7. [PMID: 32976803 DOI: 10.1016/j.cub.2020.08.103] [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: 11/05/2019] [Revised: 07/30/2020] [Accepted: 08/27/2020] [Indexed: 12/20/2022]
Abstract
Locomotion requires energy, yet animals need to increase locomotion in order to find and consume food in energy-deprived states. While such energy homeostatic coordination suggests brain origin, whether the central melanocortin 4 receptor (Mc4r) system directly modulates locomotion through motor circuits is unknown. Here, we report that hypothalamic Pomc neurons in zebrafish and mice have long-range projections into spinal cord regions harboring Mc4r-expressing V2a interneurons, crucial components of the premotor networks. Furthermore, in zebrafish, Mc4r activation decreases the excitability of spinal V2a neurons as well as swimming and foraging, while systemic or V2a neuron-specific blockage of Mc4r promotes locomotion. In contrast, in mice, electrophysiological recordings revealed that two-thirds of V2a neurons in lamina X are excited by the Mc4r agonist α-MSH, and acute inhibition of Mc4r signaling reduces locomotor activity. In addition, we found other Mc4r neurons in spinal lamina X that are inhibited by α-MSH, which is in line with previous studies in rodents where Mc4r agonists reduced locomotor activity. Collectively, our studies identify spinal V2a interneurons as evolutionary conserved second-order neurons of the central Mc4r system, providing a direct anatomical and functional link between energy homeostasis and locomotor control systems. The net effects of this modulatory system on locomotor activity can vary between different vertebrate species and, possibly, even within one species. We discuss the biological sense of this phenomenon in light of the ambiguity of locomotion on energy balance and the different living conditions of the different species.
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22
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Pomrenze MB, Giovanetti SM, Maiya R, Gordon AG, Kreeger LJ, Messing RO. Dissecting the Roles of GABA and Neuropeptides from Rat Central Amygdala CRF Neurons in Anxiety and Fear Learning. Cell Rep 2020; 29:13-21.e4. [PMID: 31577943 PMCID: PMC6879108 DOI: 10.1016/j.celrep.2019.08.083] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 07/25/2019] [Accepted: 08/27/2019] [Indexed: 11/26/2022] Open
Abstract
Central amygdala (CeA) neurons that produce corticotropin-releasing factor (CRF) regulate anxiety and fear learning. These CeACRF neurons release GABA and several neuropeptides predicted to play important yet opposing roles in these behaviors. We dissected the relative roles of GABA, CRF, dynorphin, and neurotensin in CeACRF neurons in anxiety and fear learning by disrupting their expression using RNAi in male rats. GABA, but not CRF, dynorphin, or neurotensin, regulates baseline anxiety-like behavior. In contrast, chemogenetic stimulation of CeACRF neurons evokes anxiety-like behavior dependent on CRF and dynorphin, but not neurotensin. Finally, knockdown of CRF and dynorphin impairs fear learning, whereas knockdown of neurotensin enhances it. Our results demonstrate distinct behavioral roles for GABA, CRF, dynorphin, and neurotensin in a subpopulation of CeA neurons. These results highlight the importance of considering the repertoire of signaling molecules released from a given neuronal population when studying the circuit basis of behavior. Pomrenze et al. demonstrate that CRF neurons of the central amygdala differentially regulate fear and anxiety through the release of GABA and different neuropeptides.
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Affiliation(s)
- Matthew B Pomrenze
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712, USA; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, USA.
| | - Simone M Giovanetti
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712, USA; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, USA
| | - Rajani Maiya
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712, USA; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, USA
| | - Adam G Gordon
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712, USA; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, USA
| | - Lauren J Kreeger
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712, USA
| | - Robert O Messing
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712, USA; Department of Neurology, University of Texas at Austin, Austin, TX 78712, USA; Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, USA.
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23
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Dunigan AI, Swanson AM, Olson DP, Roseberry AG. Whole-brain efferent and afferent connectivity of mouse ventral tegmental area melanocortin-3 receptor neurons. J Comp Neurol 2020; 529:1157-1183. [PMID: 32856297 DOI: 10.1002/cne.25013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 07/10/2020] [Accepted: 08/14/2020] [Indexed: 12/27/2022]
Abstract
The mesolimbic dopamine (DA) system is involved in the regulation of multiple behaviors, including feeding, and evidence demonstrates that the melanocortin system can act on the mesolimbic DA system to control feeding and other behaviors. The melanocortin-3 receptor (MC3R) is an important component of the melanocortin system, but its overall role is poorly understood. Because MC3Rs are highly expressed in the ventral tegmental area (VTA) and are likely to be the key interaction point between the melanocortin and mesolimbic DA systems, we set out to identify both the efferent projection patterns of VTA MC3R neurons and the location of the neurons providing afferent input to them. VTA MC3R neurons were broadly connected to neurons across the brain but were strongly connected to a discrete set of brain regions involved in the regulation of feeding, reward, and aversion. Surprisingly, experiments using monosynaptic rabies virus showed that proopiomelanocortin (POMC) and agouti-related protein (AgRP) neurons in the arcuate nucleus made few direct synapses onto VTA MC3R neurons or any of the other major neuronal subtypes in the VTA, despite being extensively labeled by general retrograde tracers injected into the VTA. These results greatly contribute to our understanding of the anatomical interactions between the melanocortin and mesolimbic systems and provide a foundation for future studies of VTA MC3R neurons and the circuits containing them in the control of feeding and other behaviors.
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Affiliation(s)
- Anna I Dunigan
- Department of Biology, Georgia State University, Atlanta, Georgia, USA
| | - Andrew M Swanson
- Department of Biology, Georgia State University, Atlanta, Georgia, USA
| | - David P Olson
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Aaron G Roseberry
- Department of Biology, Georgia State University, Atlanta, Georgia, USA.,Neuroscience Institute, Georgia State University, Atlanta, Georgia, USA
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24
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Campos AMP, Teixeira PDS, Wasinski F, Klein MO, Bittencourt JC, Metzger M, Donato J. Differences between rats and mice in the leptin action on the paraventricular nucleus of the hypothalamus: Implications for the regulation of the hypothalamic-pituitary-thyroid axis. J Neuroendocrinol 2020; 32:e12895. [PMID: 32840013 DOI: 10.1111/jne.12895] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/03/2020] [Accepted: 07/20/2020] [Indexed: 12/23/2022]
Abstract
Previous studies indicate that leptin regulates the hypothalamic-pituitary-thyroid (HPT) axis via direct and indirect mechanisms. The indirect mechanism involves leptin action in pro-opiomelanocortin (POMC)- and agouti-related peptide (AgRP)-expressing neurones. These cells innervate the paraventricular nucleus of the hypothalamus (PVH) where they modulate hypophysiotrophic thyrotrophin-releasing hormone (TRH)-producing neurones. The direct mechanism involves the expression of leptin receptor (LepR) in a subpopulation of PVH TRH neurones. However, to our knowledge, the existence of LepR in PVH TRH neurones of mice has not been clearly confirmed. Therefore, we investigated possible species-specific differences between rats and mice with respect to the mechanisms recruited by leptin to regulate the HPT axis. We observed that an acute leptin injection induced phosphorylated signal transducer and activator of transcription 3 (pSTAT3), a marker of leptin-responsive cells, in 46.2 ± 8.0% of PVH proTRH immunoreactive neurones in rats. By contrast, an insignificant number of proTRH positive neurones in the mouse PVH co-expressed leptin-induced pSTAT3 or LepR. Similarly, central leptin injection increased the percentage of PVH proTRH neurones containing cAMP response element-binding protein phosphorylation in rats, but not in mice. We investigated the innervation of AgRP and POMC axons in the PVH and observed that rats exhibited a denser POMC innervation in the PVH compared to mice, whereas rats and mice showed similar density of AgRP axons in the PVH. In conclusion, rats and mice exhibit important species-specific differences in the direct and indirect mechanisms used by leptin to regulate the HPT axis.
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Affiliation(s)
- Ana M P Campos
- Departamento de Fisiologia e Biofísica, Universidade de Sao Paulo, Instituto de Ciencias Biomedicas, Sao Paulo, Brazil
| | - Pryscila D S Teixeira
- Departamento de Fisiologia e Biofísica, Universidade de Sao Paulo, Instituto de Ciencias Biomedicas, Sao Paulo, Brazil
| | - Frederick Wasinski
- Departamento de Fisiologia e Biofísica, Universidade de Sao Paulo, Instituto de Ciencias Biomedicas, Sao Paulo, Brazil
| | - Marianne O Klein
- Departamento de Anatomia, Universidade de Sao Paulo, Instituto de Ciencias Biomedicas, Sao Paulo, Brazil
| | - Jackson C Bittencourt
- Departamento de Anatomia, Universidade de Sao Paulo, Instituto de Ciencias Biomedicas, Sao Paulo, Brazil
| | - Martin Metzger
- Departamento de Fisiologia e Biofísica, Universidade de Sao Paulo, Instituto de Ciencias Biomedicas, Sao Paulo, Brazil
| | - Jose Donato
- Departamento de Fisiologia e Biofísica, Universidade de Sao Paulo, Instituto de Ciencias Biomedicas, Sao Paulo, Brazil
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25
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Calarco CA, Picciotto MR. Nicotinic Acetylcholine Receptor Signaling in the Hypothalamus: Mechanisms Related to Nicotine's Effects on Food Intake. Nicotine Tob Res 2020; 22:152-163. [PMID: 30690485 DOI: 10.1093/ntr/ntz010] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 01/17/2019] [Indexed: 12/12/2022]
Abstract
Despite health risks associated with smoking, up to 20% of the US population persist in this behavior; many smoke to control body weight or appetite, and fear of post-cessation weight gain can motivate continued smoking. Nicotine and tobacco use is associated with lower body weight, and cessation yields an average weight gain of about 4 kg, which is thought to reflect a return to the body weight of a typical nonsmoker. Nicotine replacement therapies can delay this weight gain but do not prevent it altogether, and the underlying mechanism for how nicotine is able to reduce weight is not fully understood. In rodent models, nicotine reduces weight gain, reduces food consumption, and alters energy expenditure, but these effects vary with duration and route of nicotine administration. Nicotine, acting through nicotinic acetylcholine receptors (nAChRs), increases the firing rate of both orexigenic agouti-related peptide and anorexigenic proopiomelanocortin neurons in the arcuate nucleus of the hypothalamus (ARC). Manipulation of nAChR subunit expression within the ARC can block the ability of nicotine and the nicotinic agonist cytisine from decreasing food intake; however, it is unknown exactly how this reduces food intake. This review summarizes the clinical and preclinical work on nicotine, food intake, and weight gain, then explores the feeding circuitry of the ARC and how it is regulated by nicotine. Finally, we propose a novel hypothesis for how nicotine acts on this hypothalamic circuit to reduce food intake. Implications: This review provides a comprehensive and updated summary of the clinical and preclinical work examining nicotine and food intake, as well as a summary of recent work examining feeding circuits of the hypothalamus. Synthesis of these two topics has led to new understanding of how nAChR signaling regulates food intake circuits in the hypothalamus.
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Affiliation(s)
- Cali A Calarco
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT.,Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT
| | - Marina R Picciotto
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT.,Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT
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26
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Kim KY, Rios LC, Le H, Perez AJ, Phan S, Bushong EA, Deerinck TJ, Liu YH, Ellisman MA, Lev-Ram V, Ju S, Panda SA, Yoon S, Hirayama M, Mure LS, Hatori M, Ellisman MH, Panda S. Synaptic Specializations of Melanopsin-Retinal Ganglion Cells in Multiple Brain Regions Revealed by Genetic Label for Light and Electron Microscopy. Cell Rep 2020; 29:628-644.e6. [PMID: 31618632 DOI: 10.1016/j.celrep.2019.09.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 07/01/2019] [Accepted: 09/04/2019] [Indexed: 11/17/2022] Open
Abstract
The form and synaptic fine structure of melanopsin-expressing retinal ganglion cells, also called intrinsically photosensitive retinal ganglion cells (ipRGCs), were determined using a new membrane-targeted version of a genetic probe for correlated light and electron microscopy (CLEM). ipRGCs project to multiple brain regions, and because the method labels the entire neuron, it was possible to analyze nerve terminals in multiple retinorecipient brain regions, including the suprachiasmatic nucleus (SCN), olivary pretectal nucleus (OPN), and subregions of the lateral geniculate. Although ipRGCs provide the only direct retinal input to the OPN and SCN, ipRGC terminal arbors and boutons were found to be remarkably different in each target region. A network of dendro-dendritic chemical synapses (DDCSs) was also revealed in the SCN, with ipRGC axon terminals preferentially synapsing on the DDCS-linked cells. The methods developed to enable this analysis should propel other CLEM studies of long-distance brain circuits at high resolution.
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Affiliation(s)
- Keun-Young Kim
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Luis C Rios
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Hiep Le
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Alex J Perez
- National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Sébastien Phan
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Eric A Bushong
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Thomas J Deerinck
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Yu Hsin Liu
- Salk Institute for Biological Studies, La Jolla, CA, USA; Medical Scientist Training Program, University of California at San Diego School of Medicine, La Jolla, CA, USA
| | - Maya A Ellisman
- Biological Sciences Graduate Training Program, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Varda Lev-Ram
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Suyeon Ju
- National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Sneha A Panda
- National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | - Sanghee Yoon
- National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA
| | | | - Ludovic S Mure
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Megumi Hatori
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Mark H Ellisman
- Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, CA, USA; National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, CA, USA; Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA.
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27
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Nyamugenda E, Griffin H, Russell S, Cooney KA, Kowalczyk NS, Islam I, Phelan KD, Baldini G. Selective Survival of Sim1/MC4R Neurons in Diet-Induced Obesity. iScience 2020; 23:101114. [PMID: 32438321 PMCID: PMC7240135 DOI: 10.1016/j.isci.2020.101114] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/19/2020] [Accepted: 04/27/2020] [Indexed: 12/12/2022] Open
Abstract
In the melanocortin pathway, melanocortin-4 receptor (MC4R) functions to control energy homeostasis. MC4R is expressed in a sub-population of Sim1 neurons (Sim1/MC4R neurons) and functions in hypothalamic paraventricular nuclei (PVN) to control food intake. Mapping sites of hypothalamic injury in obesity is essential to counteract the disease. In the PVN of male and female mice with diet-induced obesity (DIO) there is neuronal loss. However, the existing subpopulation of PVN Sim1/MC4R neurons is unchanged, but has a loss of mitochondria and MC4R protein. In mice of both sexes with DIO, dietary intervention to re-establish normal weight restores abundance of MC4R protein in Sim1/MC4R neurons and neurogenesis in the PVN. However, the number of non-Sim1/MC4R neurons in the PVN continues to remain decreased. Selective survival and recovery of Sim1/MC4R neurons after DIO suggests these neurons as preferential target to restore energy homeostasis and of therapy against obesity.
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Affiliation(s)
- Eugene Nyamugenda
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Haven Griffin
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Susan Russell
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Kimberly A Cooney
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Nicholas S Kowalczyk
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Ishrar Islam
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Kevin D Phelan
- Department of Neurobiology & Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Giulia Baldini
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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28
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Abstract
Food intake and energy homeostasis determine survival of the organism and species. Information on total energy levels and metabolic state are sensed in the periphery and transmitted to the brain, where it is integrated and triggers the animal to forage, prey, and consume food. Investigating circuitry and cellular mechanisms coordinating energy balance and feeding behaviors has drawn on many state-of-the-art techniques, including gene manipulation, optogenetics, virus tracing, and single-cell sequencing. These new findings provide novel insights into how the central nervous system regulates food intake, and shed the light on potential therapeutic interventions for eating-related disorders such as obesity and anorexia.
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29
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Cui Z, Smith AS. In vivo measurement of enhanced agouti-related peptide release in the paraventricular nucleus of the hypothalamus through G s activation of agouti-related peptide neurons. J Biol Methods 2019; 6:e116. [PMID: 31453263 PMCID: PMC6706141 DOI: 10.14440/jbm.2019.288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 04/23/2019] [Accepted: 05/16/2019] [Indexed: 12/25/2022] Open
Abstract
Agouti-related peptide (AgRP) neurons of the hypothalamus play a role in hunger-triggered food intake, stability of body weight, and long-term energy balance. A recent study showed that activation of the Gs-linked G protein-coupled receptors (GCPR) expressed by hypothalamic AgRP neurons promotes a sustained increase in food intake. Enhanced AgRP release has been the postulated underlying mechanism. Here, we confirmed that activation of Gs-coupled receptors expressed by AgRP neurons in the arcuate nucleus (ARC) of the hypothalamus, which is the primary brain region for the synthesis and release of AgRP, leads to increased release of AgRP in the paraventricular nucleus of the hypothalamus (PVN). We were unable to confirm changes in AgRP expression or intracellular content using traditional histological techniques. Thus, we developed an assay to measure AgRP in the extracellular fluid in the brain using large molecular weight cut-off microdialysis probes. Our technique enables assessment of brain AgRP pharmacokinetics under physiological conditions and in response to specific pharmacological interventions designed to modulate AgRP signaling.
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Affiliation(s)
- Zhenzhong Cui
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.,Mouse Metabolism Core Laboratory, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Adam S Smith
- Section on Neural Gene Expression, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA.,Department of Pharmacology & Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
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30
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Bloss EB, Hunt DL. Revealing the Synaptic Hodology of Mammalian Neural Circuits With Multiscale Neurocartography. Front Neuroinform 2019; 13:52. [PMID: 31427940 PMCID: PMC6690003 DOI: 10.3389/fninf.2019.00052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 07/02/2019] [Indexed: 11/20/2022] Open
Abstract
The functional features of neural circuits are determined by a combination of properties that range in scale from projections systems across the whole brain to molecular interactions at the synapse. The burgeoning field of neurocartography seeks to map these relevant features of brain structure—spanning a volume ∼20 orders of magnitude—to determine how neural circuits perform computations supporting cognitive function and complex behavior. Recent technological breakthroughs in tissue sample preparation, high-throughput electron microscopy imaging, and automated image analyses have produced the first visualizations of all synaptic connections between neurons of invertebrate model systems. However, the sheer size of the central nervous system in mammals implies that reconstruction of the first full brain maps at synaptic scale may not be feasible for decades. In this review, we outline existing and emerging technologies for neurocartography that complement electron microscopy-based strategies and are beginning to derive some basic organizing principles of circuit hodology at the mesoscale, microscale, and nanoscale. Specifically, we discuss how a host of light microscopy techniques including array tomography have been utilized to determine both long-range and subcellular organizing principles of synaptic connectivity. In addition, we discuss how new techniques, such as two-photon serial tomography of the entire mouse brain, have become attractive approaches to dissect the potential connectivity of defined cell types. Ultimately, principles derived from these techniques promise to facilitate a conceptual understanding of how connectomes, and neurocartography in general, can be effectively utilized toward reaching a mechanistic understanding of circuit function.
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Affiliation(s)
- Erik B Bloss
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, United States
| | - David L Hunt
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, United States
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31
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Relationship of α-MSH and AgRP axons to the perikarya of melanocortin-4 receptor neurons. Brain Res 2019; 1717:136-146. [DOI: 10.1016/j.brainres.2019.04.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 03/29/2019] [Accepted: 04/18/2019] [Indexed: 11/21/2022]
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32
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Baldini G, Phelan KD. The melanocortin pathway and control of appetite-progress and therapeutic implications. J Endocrinol 2019; 241:R1-R33. [PMID: 30812013 PMCID: PMC6500576 DOI: 10.1530/joe-18-0596] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 01/22/2019] [Indexed: 12/19/2022]
Abstract
The initial discovery that ob/ob mice become obese because of a recessive mutation of the leptin gene has been crucial to discover the melanocortin pathway to control appetite. In the melanocortin pathway, the fed state is signaled by abundance of circulating hormones such as leptin and insulin, which bind to receptors expressed at the surface of pro-opiomelanocortin (POMC) neurons to promote processing of POMC to the mature hormone α-melanocyte-stimulating hormone (α-MSH). The α-MSH released by POMC neurons then signals to decrease energy intake by binding to melanocortin-4 receptor (MC4R) expressed by MC4R neurons to the paraventricular nucleus (PVN). Conversely, in the 'starved state' activity of agouti-related neuropeptide (AgRP) and of neuropeptide Y (NPY)-expressing neurons is increased by decreased levels of circulating leptin and insulin and by the orexigenic hormone ghrelin to promote food intake. This initial understanding of the melanocortin pathway has recently been implemented by the description of the complex neuronal circuit that controls the activity of POMC, AgRP/NPY and MC4R neurons and downstream signaling by these neurons. This review summarizes the progress done on the melanocortin pathway and describes how obesity alters this pathway to disrupt energy homeostasis. We also describe progress on how leptin and insulin receptors signal in POMC neurons, how MC4R signals and how altered expression and traffic of MC4R change the acute signaling and desensitization properties of the receptor. We also describe how the discovery of the melanocortin pathway has led to the use of melanocortin agonists to treat obesity derived from genetic disorders.
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Affiliation(s)
- Giulia Baldini
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Kevin D. Phelan
- Department of Neurobiology & Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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33
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Zhang Q, Lee WCA, Paul DL, Ginty DD. Multiplexed peroxidase-based electron microscopy labeling enables simultaneous visualization of multiple cell types. Nat Neurosci 2019; 22:828-839. [PMID: 30886406 PMCID: PMC6555422 DOI: 10.1038/s41593-019-0358-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 02/07/2019] [Indexed: 01/06/2023]
Abstract
Electron microscopy (EM) is a powerful tool for circuit mapping, but identifying specific cell types in EM datasets remains a major challenge. Here we describe a technique enabling simultaneous visualization of multiple, genetically identified neuronal populations so that synaptic interactions between them can be unequivocally defined. We present 15 AAV constructs and six mouse reporter lines for multiplexed EM labeling in the mammalian nervous system. These reporters feature dAPEX2, which exhibits dramatically improved signal compared to previously described ascorbate peroxidases. By targeting this enhanced peroxidase to different subcellular compartments, multiple orthogonal reporters can be simultaneously visualized and distinguished under EM using a protocol compatible with existing EM pipelines. Proof-of-principle double and triple EM labeling experiments demonstrated synaptic connections between primary afferents, descending cortical inputs, and inhibitory interneurons in the spinal cord dorsal horn. Our multiplexed peroxidase-based EM labeling system should therefore greatly facilitate analysis of connectivity in the nervous system.
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Affiliation(s)
- Qiyu Zhang
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Wei-Chung A Lee
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
| | - David L Paul
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
| | - David D Ginty
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA. .,Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
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34
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Rossi MJ, Pekkurnaz G. Powerhouse of the mind: mitochondrial plasticity at the synapse. Curr Opin Neurobiol 2019; 57:149-155. [PMID: 30875521 DOI: 10.1016/j.conb.2019.02.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 02/05/2019] [Indexed: 12/16/2022]
Abstract
Neurons are highly polarized cells with extraordinary energy demands, which are mainly fulfilled by mitochondria. In response to altered neuronal energy state, mitochondria adapt to enable energy homeostasis and nervous system function. This adaptation, also called mitochondrial plasticity, can be observed as alterations in the form, function and position. The primary site of energy consumption in neurons is localized at the synapse, where mitochondria are critical for both pre- and postsynaptic functions. In this review, we will discuss molecular mechanisms regulating mitochondrial plasticity at the synapse and how they contribute to information processing within neurons.
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Affiliation(s)
- Meghan J Rossi
- Neurobiology Section, Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States
| | - Gulcin Pekkurnaz
- Neurobiology Section, Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States.
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35
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van den Pol AN, Acuna C, Davis JN, Huang H, Zhang X. Defining the caudal hypothalamic arcuate nucleus with a focus on anorexic excitatory neurons. J Physiol 2019; 597:1605-1625. [PMID: 30618146 PMCID: PMC6418765 DOI: 10.1113/jp277152] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/03/2019] [Indexed: 01/11/2023] Open
Abstract
KEY POINTS Excitatory glutamate neurons are sparse in the rostral hypothalamic arcuate nucleus (ARC), the subregion that has received the most attention in the past. In striking contrast, excitatory neurons are far more common (by a factor of 10) in the caudal ARC, an area which has received relatively little attention. These glutamate cells may play a negative role in energy balance and food intake. They can show an increase in phosphorylated Stat-3 in the presence of leptin, are electrically excited by the anorectic neuromodulator cholecystokinin, and inhibited by orexigenic neuromodulators neuropeptide Y, met-enkephalin, dynorphin and the catecholamine dopamine. The neurons project local axonal connections that excite other ARC neurons including proopiomelanocortin neurons that can play an important role in obesity. These data are consistent with models suggesting that the ARC glutamatergic neurons may play both a rapid and a slower role in acting as anorectic neurons in CNS control of food intake and energy homeostasis. ABSTRACT Here we interrogate a unique class of excitatory neurons in the hypothalamic arcuate nucleus (ARC) that utilizes glutamate as a fast neurotransmitter using mice expressing GFP under control of the vesicular glutamate transporter 2 (vGluT2) promoter. These neurons show a unique distribution, synaptic characterization, cellular physiology and response to neuropeptides involved in energy homeostasis. Although apparently not previously appreciated, the caudal ARC showed a far greater density of vGluT2 cells than the rostral ARC, as seen in transgenic vGluT2-GFP mice and mRNA analysis. After food deprivation, leptin induced an increase in phosphorylated Stat-3 in vGluT2-positive neurons, indicating a response to hormonal cues of energy state. Based on whole-cell recording electrophysiology in brain slices, vGluT2 neurons were spontaneously active with a spike frequency around 2 Hz. vGluT2 cells were responsive to a number of neuropeptides related to energy homeostasis; they were excited by the anorectic peptide cholecystokinin, but inhibited by orexigenic neuropeptide Y, dynorphin and met-enkephalin, consistent with an anorexic role in energy homeostasis. Dopamine, associated with the hedonic aspect of enhancing food intake, inhibited vGluT2 neurons. Optogenetic excitation of vGluT2 cells evoked EPSCs in neighbouring neurons, indicating local synaptic excitation of other ARC neurons. Microdrop excitation of ARC glutamate cells in brain slices rapidly increased excitatory synaptic activity in anorexigenic proopiomelanocortin neurons. Together these data support the perspective that vGluT2 cells may be more prevalent in the ARC than previously appreciated, and play predominantly an anorectic role in energy metabolism.
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Affiliation(s)
| | - Claudio Acuna
- Department of NeurosurgeryYale University School of MedicineNew HavenCT06520USA
| | - John N. Davis
- Department of NeurosurgeryYale University School of MedicineNew HavenCT06520USA
| | - Hao Huang
- Department of NeurosurgeryYale University School of MedicineNew HavenCT06520USA
| | - Xiaobing Zhang
- Department of NeurosurgeryYale University School of MedicineNew HavenCT06520USA
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36
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Idelevich A, Baron R. Brain to bone: What is the contribution of the brain to skeletal homeostasis? Bone 2018; 115:31-42. [PMID: 29777919 PMCID: PMC6110971 DOI: 10.1016/j.bone.2018.05.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 05/15/2018] [Accepted: 05/15/2018] [Indexed: 12/13/2022]
Abstract
The brain, which governs most, if not all, physiological functions in the body, from the complexities of cognition, learning and memory, to the regulation of basal body temperature, heart rate and breathing, has long been known to affect skeletal health. In particular, the hypothalamus - located at the base of the brain in close proximity to the medial eminence, where the blood-brain-barrier is not as tight as in other regions of the brain but rather "leaky", due to fenestrated capillaries - is exposed to a variety of circulating body cues, such as nutrients (glucose, fatty acids, amino acids), and hormones (insulin, glucagon, leptin, adiponectin) [1-3].Information collected from the body via these peripheral cues is integrated by hypothalamic sensing neurons and glial cells [4-7], which express receptors for these nutrients and hormones, transforming these cues into physiological outputs. Interestingly, many of the same molecules, including leptin, adiponectin and insulin, regulate both energy and skeletal homeostasis. Moreover, they act on a common set of hypothalamic nuclei and their residing neurons, activating endocrine and neuronal systems, which ultimately fine-tune the body to new physiological states. This review will focus exclusively on the brain-to-bone pathway, highlighting the most important anatomical sites within the brain, which are known to affect bone, but not covering the input pathways and molecules informing the brain of the energy and bone metabolic status, covered elsewhere [8-10]. The discussion in each section will present side by side the metabolic and bone-related functions of hypothalamic nuclei, in an attempt to answer some of the long-standing questions of whether energy is affected by bone remodeling and homeostasis and vice versa.
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Affiliation(s)
- Anna Idelevich
- Department of Medicine, Harvard Medical School and Endocrine Unit MGH, Division of Bone and Mineral Metabolism, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
| | - Roland Baron
- Department of Medicine, Harvard Medical School and Endocrine Unit MGH, Division of Bone and Mineral Metabolism, Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA.
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37
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Drawitsch F, Karimi A, Boergens KM, Helmstaedter M. FluoEM, virtual labeling of axons in three-dimensional electron microscopy data for long-range connectomics. eLife 2018; 7:38976. [PMID: 30106377 PMCID: PMC6158011 DOI: 10.7554/elife.38976] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 08/10/2018] [Indexed: 01/29/2023] Open
Abstract
The labeling and identification of long-range axonal inputs from multiple sources within densely reconstructed electron microscopy (EM) datasets from mammalian brains has been notoriously difficult because of the limited color label space of EM. Here, we report FluoEM for the identification of multi-color fluorescently labeled axons in dense EM data without the need for artificial fiducial marks or chemical label conversion. The approach is based on correlated tissue imaging and computational matching of neurite reconstructions, amounting to a virtual color labeling of axons in dense EM circuit data. We show that the identification of fluorescent light- microscopically (LM) imaged axons in 3D EM data from mouse cortex is faithfully possible as soon as the EM dataset is about 40-50 µm in extent, relying on the unique trajectories of axons in dense mammalian neuropil. The method is exemplified for the identification of long-distance axonal input into layer 1 of the mouse cerebral cortex.
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Affiliation(s)
- Florian Drawitsch
- Department of Connectomics, Max Planck Institute for Brain Research, Frankfurt, Germany.,Donders Institute, Faculty of Science, Radboud University, Nijmegen, Netherlands
| | - Ali Karimi
- Department of Connectomics, Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Kevin M Boergens
- Department of Connectomics, Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Moritz Helmstaedter
- Department of Connectomics, Max Planck Institute for Brain Research, Frankfurt, Germany.,Donders Institute, Faculty of Science, Radboud University, Nijmegen, Netherlands
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38
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Ghamari-Langroudi M, Cakir I, Lippert RN, Sweeney P, Litt MJ, Ellacott KLJ, Cone RD. Regulation of energy rheostasis by the melanocortin-3 receptor. SCIENCE ADVANCES 2018; 4:eaat0866. [PMID: 30140740 PMCID: PMC6105298 DOI: 10.1126/sciadv.aat0866] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 07/18/2018] [Indexed: 05/19/2023]
Abstract
Like most homeostatic systems, adiposity in mammals is defended between upper and lower boundary conditions. While leptin and melanocortin-4 receptor (MC4R) signaling are required for defending energy set point, mechanisms controlling upper and lower homeostatic boundaries are less well understood. In contrast to the MC4R, deletion of the MC3R does not produce measurable hyperphagia or hypometabolism under normal conditions. However, we demonstrate that MC3R is required bidirectionally for controlling responses to external homeostatic challenges, such as caloric restriction or calorie-rich diet. MC3R is also required for regulated excursion from set point, or rheostasis, during pregnancy. Further, we demonstrate a molecular mechanism: MC3R provides regulatory inputs to melanocortin signaling, acting presynaptically on agouti-related protein neurons to regulate γ-aminobutyric acid release onto anorexigenic MC4R neurons, exerting boundary control on the activity of MC4R neurons. Thus, the MC3R is a critical regulator of boundary controls on melanocortin signaling, providing rheostatic control on energy storage.
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Affiliation(s)
- Masoud Ghamari-Langroudi
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN 37232, USA
- Corresponding author. (M.G.-L.); (R.D.C.)
| | - Isin Cakir
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN 37232, USA
- Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109–2216, USA
| | - Rachel N. Lippert
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN 37232, USA
- Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931 Cologne, Germany
| | - Patrick Sweeney
- Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109–2216, USA
| | - Michael J. Litt
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN 37232, USA
| | - Kate L. J. Ellacott
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN 37232, USA
- University of Exeter Medical School, Exeter, UK
| | - Roger D. Cone
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN 37232, USA
- Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109–2216, USA
- Corresponding author. (M.G.-L.); (R.D.C.)
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39
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Cruz-Lopez D, Ramos D, Castilloveitia G, Schikorski T. Quintuple labeling in the electron microscope with genetically encoded enhanced horseradish peroxidase. PLoS One 2018; 13:e0200693. [PMID: 30011315 PMCID: PMC6047818 DOI: 10.1371/journal.pone.0200693] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 07/02/2018] [Indexed: 11/25/2022] Open
Abstract
Genetic encoded multilabeling is essential for modern cell biology. In fluorescence microscopy this need has been satisfied by the development of numerous color-variants of the green fluorescent protein. In electron microscopy, however, true genetic encoded multilabeling is currently not possible. Here, we introduce combinatorial cell organelle type-specific labeling as a strategy for multilabeling. First, we created a reliable and high sensitive label by evolving the catalytic activity of horseradish peroxidase (HRP). We then built fusion proteins that targeted our new enhanced HRP (eHRP) to three cell organelles whose labeling pattern did not overlap with each other. The labeling of the endoplasmic reticulum, synaptic vesicles and the plasma membrane consequently allowed for triple labeling in the EM. The combinatorial expression of the three organelle-specific constructs increased the number of clearly distinguishable labels to seven. This strategy of multilabeling for EM closes a significant gap in our tool set and has a broad application range in cell biology.
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Affiliation(s)
- Didiana Cruz-Lopez
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
| | - Dianne Ramos
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
| | - Gloria Castilloveitia
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
| | - Thomas Schikorski
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
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40
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Zhang Y, Yu J, Qiang L, Gu Z. Nanomedicine for obesity treatment. SCIENCE CHINA-LIFE SCIENCES 2018; 61:373-379. [PMID: 29623548 DOI: 10.1007/s11427-017-9257-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 11/20/2017] [Indexed: 01/07/2023]
Abstract
Obesity, as a chronic condition, has been a serious public health issue over the last decades both in the affluent Western world and developing countries. As reported, the risk of several serious diseases increases with weight gain, including type 2 diabetes, coronary heart disease, cancer, and respiratory diseases. In addition to lifestyle modifications, pharmacotherapy has become an important strategy to control weight gain. However, most of the anti-obesity drugs often show poor outcome for weight-loss and cause severe adverse effects. This review surveys recent advances in nanomedicine as an emerging strategy for obesity treatment with an emphasis on the enhanced therapeutic efficiency and minimized side effects. The insights for future development are also discussed.
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Affiliation(s)
- Yuqi Zhang
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Raleigh, NC, 27695, USA
- Center for Nanotechnology in Drug Delivery and Division of Molecular Pharmaceutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jicheng Yu
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Raleigh, NC, 27695, USA
- Center for Nanotechnology in Drug Delivery and Division of Molecular Pharmaceutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Li Qiang
- Department of Pathology and Cell Biology, Naomi Berrie Diabetes Center, Columbia University, New York, NY, 10032, USA.
| | - Zhen Gu
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Raleigh, NC, 27695, USA.
- Center for Nanotechnology in Drug Delivery and Division of Molecular Pharmaceutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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41
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Functional Interrogation of the AgRP Neural Circuits in Control of Appetite, Body Weight, and Behaviors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1090:1-16. [PMID: 30390282 DOI: 10.1007/978-981-13-1286-1_1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neurons expressing agouti-related protein (AgRP), the so-called hunger neurons, protect mammals from starvation by promoting food-seeking behaviors (Trends Neurosci 36:504-512, 2013). Now an increasing amount of evidence show that these hunger-sensing neurons not only motivate animals to forage and ingest food but also help conserve energy by inhibiting innate processes that demand large amounts of energy such as growth, reproduction, and stress response. It has further been perceived that AgRP neurons transmit signals with negative valence to reward and cognitive centers so as to engage the motivational behavior toward seeking and obtaining foods (Physiol Behav 190:34-42, 2017). Recent advancement in genome editing and neurotechniques unleashed an escalated research of uniquely defined neuronal populations and neural circuits underlying the behavioral regulation of body weight and food responses (Nat Biotechnol 32:347-355, 2014; Proc Natl Acad Sci 113, 2016). In this chapter we will review literatures describing the functional organization of the AgRP circuit and its correlative signaling components that influence ingestive, foraging, motivational, and cognitive responses, a framework that reshaped our thinking toward the new hope and challenges in treatment of obesity and eating disorders.
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42
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Devarakonda K, Stanley S. Investigating metabolic regulation using targeted neuromodulation. Ann N Y Acad Sci 2017; 1411:83-95. [PMID: 29106710 DOI: 10.1111/nyas.13468] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/11/2017] [Accepted: 08/18/2017] [Indexed: 01/13/2023]
Abstract
The central nervous system (CNS) plays a vital role in regulating energy balance and metabolism. Over the last 50 years, studies in animal models have allowed us to identify critical CNS regions involved in these processes and even crucial cell populations. Now, techniques for genetically and anatomically targeted manipulation of specific neural populations using light (optogenetic), ligands (chemogenetic), or magnetic fields (radiogenetic/magnetogenetic) allow detailed investigation of circuits involved in metabolic regulation. In this review, we provide a brief overview of recent studies using light- and magnetic field-regulated neural activity to investigate the neural circuits contributing to metabolic control.
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Affiliation(s)
- Kavya Devarakonda
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Sarah Stanley
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York.,Diabetes, Obesity and Metabolism Institute, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
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43
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Pipkin JE, Bushong EA, Ellisman MH, Kristan WB. Patterns and distribution of presynaptic and postsynaptic elements within serial electron microscopic reconstructions of neuronal arbors from the medicinal leech Hirudo verbana. J Comp Neurol 2017; 524:3677-3695. [PMID: 27636374 DOI: 10.1002/cne.24120] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 06/15/2016] [Accepted: 09/10/2016] [Indexed: 12/11/2022]
Abstract
Microscale connectomics involves the large-scale acquisition of high-resolution serial electron micrographs from which neuronal arbors can be reconstructed and synapses can be detected. In addition to connectivity information, these data sets are also rich with structural information, including vesicle types, number of postsynaptic partners at a given presynaptic site, and spatial distribution of synaptic inputs and outputs. This study uses serial block-face scanning electron microscopy (EM) to collect two volumes of serial EM data from ganglia of the medicinal leech. For the first volume, we sampled a small fraction of the neuropil belonging to an adult ganglion. From this data set we measured the proportion of arbors that contained vesicles and the types of vesicles contained and developed criteria to identify synapses and to measure the number of apparent postsynaptic partners in apposition to presynaptic boutons. For the second data set, we sampled an entire juvenile ganglion, which included the somata and arbors of all the neurons. We used this data set to placd our findings from mature tissue in the context of fully reconstructed arbors and to explore the spatial distribution of synaptic inputs and outputs on these arbors. We observed that some neurons segregated their arbors into input only and mixed input/output zones, that other neurons contained exclusively mixed input/output zones, and that still others contained only input zones. These results provide the groundwork for future behavioral studies. J. Comp. Neurol. 524:3677-3695, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Jason E Pipkin
- Neurosciences Graduate Program, University of California at San Diego, La Jolla, California, 92093. .,Neurobiology Section, Division of Biological Sciences, University of California at San Diego, La Jolla, California, 92093.
| | - Eric A Bushong
- National Center for Microscopy and Imaging Research, University of California at San Diego, La Jolla, California, 92093
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, University of California at San Diego, La Jolla, California, 92093.,Department of Neurosciences, University of California at San Diego School of Medicine, La Jolla, California, 92093
| | - William B Kristan
- Neurobiology Section, Division of Biological Sciences, University of California at San Diego, La Jolla, California, 92093
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44
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Andermann ML, Lowell BB. Toward a Wiring Diagram Understanding of Appetite Control. Neuron 2017; 95:757-778. [PMID: 28817798 DOI: 10.1016/j.neuron.2017.06.014] [Citation(s) in RCA: 329] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 06/02/2017] [Accepted: 06/07/2017] [Indexed: 01/26/2023]
Abstract
Prior mouse genetic research has set the stage for a deep understanding of appetite regulation. This goal is now being realized through the use of recent technological advances, such as the ability to map connectivity between neurons, manipulate neural activity in real time, and measure neural activity during behavior. Indeed, major progress has been made with regard to meal-related gut control of appetite, arcuate nucleus-based hypothalamic circuits linking energy state to the motivational drive, hunger, and, finally, limbic and cognitive processes that bring about hunger-mediated increases in reward value and perception of food. Unexpected findings are also being made; for example, the rapid regulation of homeostatic neurons by cues that predict future food consumption. The aim of this review is to cover the major underpinnings of appetite regulation, describe recent advances resulting from new technologies, and synthesize these findings into an updated view of appetite regulation.
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Affiliation(s)
- Mark L Andermann
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA.
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA.
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45
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Shigemoto R, Joesch M. The genetic encoded toolbox for electron microscopy and connectomics. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2017; 6. [DOI: 10.1002/wdev.288] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/02/2017] [Accepted: 07/05/2017] [Indexed: 11/08/2022]
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46
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Dodd GT, Andrews ZB, Simonds SE, Michael NJ, DeVeer M, Brüning JC, Spanswick D, Cowley MA, Tiganis T. A Hypothalamic Phosphatase Switch Coordinates Energy Expenditure with Feeding. Cell Metab 2017; 26:375-393.e7. [PMID: 28768176 DOI: 10.1016/j.cmet.2017.07.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 04/13/2017] [Accepted: 07/17/2017] [Indexed: 12/17/2022]
Abstract
Beige adipocytes can interconvert between white and brown-like states and switch between energy storage versus expenditure. Here we report that beige adipocyte plasticity is important for feeding-associated changes in energy expenditure and is coordinated by the hypothalamus and the phosphatase TCPTP. A fasting-induced and glucocorticoid-mediated induction of TCPTP, inhibited insulin signaling in AgRP/NPY neurons, repressed the browning of white fat and decreased energy expenditure. Conversely feeding reduced hypothalamic TCPTP, to increase AgRP/NPY neuronal insulin signaling, white adipose tissue browning and energy expenditure. The feeding-induced repression of hypothalamic TCPTP was defective in obesity. Mice lacking TCPTP in AgRP/NPY neurons were resistant to diet-induced obesity and had increased beige fat activity and energy expenditure. The deletion of hypothalamic TCPTP in obesity restored feeding-induced browning and increased energy expenditure to promote weight loss. Our studies define a hypothalamic switch that coordinates energy expenditure with feeding for the maintenance of energy balance.
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Affiliation(s)
- Garron T Dodd
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Victoria 3800, Australia; Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Zane B Andrews
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Victoria 3800, Australia; Department of Physiology, Monash University, Victoria 3800, Australia
| | - Stephanie E Simonds
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Victoria 3800, Australia; Department of Physiology, Monash University, Victoria 3800, Australia
| | - Natalie J Michael
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Victoria 3800, Australia; Department of Physiology, Monash University, Victoria 3800, Australia
| | - Michael DeVeer
- Monash Biomedical Imaging, Monash University, Victoria 3168, Australia
| | - Jens C Brüning
- Max Plank Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Gleueler Str. 50, 50931 Cologne, Germany; Center for Endocrinology, Diabetes, and Preventive Medicine (CEDP), University Hospital Cologne, Kerpener Str. 26, 50924 Cologne, Germany; Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany; National Center for Diabetes Research (DZD), Ingolstädter Land Str. 1, 85764 Neuherberg, Germany
| | - David Spanswick
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Victoria 3800, Australia; Department of Physiology, Monash University, Victoria 3800, Australia
| | - Michael A Cowley
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Victoria 3800, Australia; Department of Physiology, Monash University, Victoria 3800, Australia
| | - Tony Tiganis
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Victoria 3800, Australia; Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia.
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47
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Livneh Y, Ramesh RN, Burgess CR, Levandowski KM, Madara JC, Fenselau H, Goldey GJ, Diaz VE, Jikomes N, Resch JM, Lowell BB, Andermann ML. Homeostatic circuits selectively gate food cue responses in insular cortex. Nature 2017; 546:611-616. [PMID: 28614299 PMCID: PMC5577930 DOI: 10.1038/nature22375] [Citation(s) in RCA: 209] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 04/10/2017] [Indexed: 12/17/2022]
Abstract
Physiological needs bias perception and attention to relevant sensory cues. This process is 'hijacked' by drug addiction, causing cue-induced cravings and relapse. Similarly, its dysregulation contributes to failed diets, obesity, and eating disorders. Neuroimaging studies in humans have implicated insular cortex in these phenomena. However, it remains unclear how 'cognitive' cortical representations of motivationally relevant cues are biased by subcortical circuits that drive specific motivational states. Here we develop a microprism-based cellular imaging approach to monitor visual cue responses in the insular cortex of behaving mice across hunger states. Insular cortex neurons demonstrate food-cue-biased responses that are abolished during satiety. Unexpectedly, while multiple satiety-related visceral signals converge in insular cortex, chemogenetic activation of hypothalamic 'hunger neurons' (expressing agouti-related peptide (AgRP)) bypasses these signals to restore hunger-like response patterns in insular cortex. Circuit mapping and pathway-specific manipulations uncover a pathway from AgRP neurons to insular cortex via the paraventricular thalamus and basolateral amygdala. These results reveal a neural basis for state-specific biased processing of motivationally relevant cues.
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Affiliation(s)
- Yoav Livneh
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Rohan N Ramesh
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Christian R Burgess
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Kirsten M Levandowski
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Joseph C Madara
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Henning Fenselau
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Glenn J Goldey
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Veronica E Diaz
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Nick Jikomes
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Jon M Resch
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Mark L Andermann
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA
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48
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Burke LK, Darwish T, Cavanaugh AR, Virtue S, Roth E, Morro J, Liu SM, Xia J, Dalley JW, Burling K, Chua S, Vidal-Puig T, Schwartz GJ, Blouet C. mTORC1 in AGRP neurons integrates exteroceptive and interoceptive food-related cues in the modulation of adaptive energy expenditure in mice. eLife 2017; 6. [PMID: 28532548 PMCID: PMC5441868 DOI: 10.7554/elife.22848] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 04/18/2017] [Indexed: 01/19/2023] Open
Abstract
Energy dissipation through interscapular brown adipose tissue (iBAT) thermogenesis is an important contributor to adaptive energy expenditure. However, it remains unresolved how acute and chronic changes in energy availability are detected by the brain to adjust iBAT activity and maintain energy homeostasis. Here, we provide evidence that AGRP inhibitory tone to iBAT represents an energy-sparing circuit that integrates environmental food cues and internal signals of energy availability. We establish a role for the nutrient-sensing mTORC1 signaling pathway within AGRP neurons in the detection of environmental food cues and internal signals of energy availability, and in the bi-directional control of iBAT thermogenesis during nutrient deficiency and excess. Collectively, our findings provide insights into how mTORC1 signaling within AGRP neurons surveys energy availability to engage iBAT thermogenesis, and identify AGRP neurons as a neuronal substrate for the coordination of energy intake and adaptive expenditure under varying physiological and environmental contexts. DOI:http://dx.doi.org/10.7554/eLife.22848.001 Losing weight through dieting can be difficult. Weight loss strategies often prove ineffective because the body works like a thermostat and couples what we eat to the number of calories we burn. When we eat less, our bodies compensate and burn fewer calories, which makes losing weight harder. The brain is the master regulator of this caloric thermostat, but it is not clear how it adjusts our energy expenditure to account for how much we have eaten. A structure deep within the brain called the hypothalamus, which helps regulate appetite, is thought to be involved in the caloric thermostat. Activating a group of neurons within the hypothalamus called the agouti-related neuropeptide (AGRP) neurons causes animals to consume large quantities of food. By contrast, inhibiting AGRP neurons causes animals to stop eating almost entirely. Burke et al. studied AGRP neurons in mice. The experiments show that artificially activating the neurons in mice that don’t have access to food increases the animals’ activity levels but reduces the rate at which they burn calories, which helps the mice to maintain their existing weight. Allowing the mice to eat, or even just to see and smell food, switches off this effect and returns energy expenditure to normal. Finally, exposing mice to a high-fat diet for several days inhibits their AGRP neurons, and causes the animals to burn calories at a faster rate. By using up excess calories, this change also helps the animals maintain their existing body weight. The findings of Burke et al. show that AGRP neurons are a key component of the caloric thermostat. By adjusting the rate at which the body burns calories, AGRP neurons can compensate for any changes in food intake and so limit changes in body weight. This work opens up the possibility of developing therapies that disconnect energy expenditure from energy intake to help maintain long-term weight loss. DOI:http://dx.doi.org/10.7554/eLife.22848.002
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Affiliation(s)
- Luke K Burke
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Tamana Darwish
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Althea R Cavanaugh
- Departments of Medicine and Neuroscience, The Albert Einstein College of Medicine, New York, United States
| | - Sam Virtue
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Emma Roth
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Joanna Morro
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Shun-Mei Liu
- Departments of Medicine and Neuroscience, The Albert Einstein College of Medicine, New York, United States
| | - Jing Xia
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom
| | - Jeffrey W Dalley
- Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom.,Department of Psychiatry, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom
| | - Keith Burling
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Streamson Chua
- Departments of Medicine and Neuroscience, The Albert Einstein College of Medicine, New York, United States
| | - Toni Vidal-Puig
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Gary J Schwartz
- Departments of Medicine and Neuroscience, The Albert Einstein College of Medicine, New York, United States
| | - Clémence Blouet
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom.,WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
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49
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Ng J, Browning A, Lechner L, Terada M, Howard G, Jefferis GSXE. Genetically targeted 3D visualisation of Drosophila neurons under Electron Microscopy and X-Ray Microscopy using miniSOG. Sci Rep 2016; 6:38863. [PMID: 27958322 PMCID: PMC5153665 DOI: 10.1038/srep38863] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/11/2016] [Indexed: 11/23/2022] Open
Abstract
Large dimension, high-resolution imaging is important for neural circuit visualisation as neurons have both long- and short-range patterns: from axons and dendrites to the numerous synapses at terminal endings. Electron Microscopy (EM) is the favoured approach for synaptic resolution imaging but how such structures can be segmented from high-density images within large volume datasets remains challenging. Fluorescent probes are widely used to localise synapses, identify cell-types and in tracing studies. The equivalent EM approach would benefit visualising such labelled structures from within sub-cellular, cellular, tissue and neuroanatomical contexts. Here we developed genetically-encoded, electron-dense markers using miniSOG. We demonstrate their ability in 1) labelling cellular sub-compartments of genetically-targeted neurons, 2) generating contrast under different EM modalities, and 3) segmenting labelled structures from EM volumes using computer-assisted strategies. We also tested non-destructive X-ray imaging on whole Drosophila brains to evaluate contrast staining. This enabled us to target specific regions for EM volume acquisition.
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Affiliation(s)
- Julian Ng
- Department of Zoology, Downing Street, Cambridge, CB2 3EJ, United Kingdom.,Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, CB2 0QH, United Kingdom
| | - Alyssa Browning
- Carl Zeiss X-ray Microscopy Inc., 4385 Hopyard Rd., Suite 100, Pleasanton, CA 94588, USA
| | - Lorenz Lechner
- Carl Zeiss X-ray Microscopy Inc., 4385 Hopyard Rd., Suite 100, Pleasanton, CA 94588, USA
| | - Masako Terada
- Carl Zeiss X-ray Microscopy Inc., 4385 Hopyard Rd., Suite 100, Pleasanton, CA 94588, USA
| | - Gillian Howard
- Cell Biology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, CB2 0QH, United Kingdom
| | - Gregory S X E Jefferis
- Department of Zoology, Downing Street, Cambridge, CB2 3EJ, United Kingdom.,Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, CB2 0QH, United Kingdom
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50
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A rapidly acting glutamatergic ARC→PVH satiety circuit postsynaptically regulated by α-MSH. Nat Neurosci 2016; 20:42-51. [PMID: 27869800 PMCID: PMC5191921 DOI: 10.1038/nn.4442] [Citation(s) in RCA: 159] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 10/20/2016] [Indexed: 12/12/2022]
Abstract
Arcuate nucleus (ARC) neurons sense the fed/fasted state and regulate hunger. Agouti-related protein (ARCAgRP) neurons are stimulated by fasting, and once activated, they rapidly (within minutes) drive hunger. Pro-opiomelanocortin (ARCPOMC) neurons are viewed as the counterpoint to ARCAgRP neurons. They are regulated in an opposite fashion and decrease hunger. However, unlike ARCAgRP neurons, ARCPOMC neurons are extremely slow in affecting hunger (many hours). Thus, a temporally analogous, rapid ARC satiety pathway does not exist or is presently unidentified. Here, we show that glutamate-releasing ARC neurons expressing oxytocin receptor, unlike ARCPOMC neurons, rapidly cause satiety when chemo- or optogenetically manipulated. These glutamatergic ARC projections synaptically converge with GABAergic ARCAgRP projections on melanocortin-4 receptor (MC4R)-expressing satiety neurons in the paraventricular hypothalamus (PVHMC4R neurons). Importantly, transmission across the ARCGlutamatergic→PVHMC4R synapse is potentiated by the ARCPOMC neuron-derived MC4R agonist, α-MSH. This excitatory ARC→PVH satiety circuit, and its modulation by α-MSH, provides new insight into regulation of hunger/satiety.
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