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Zahola P, Hanics J, Pintér A, Máté Z, Gáspárdy A, Hevesi Z, Echevarria D, Adori C, Barde S, Törőcsik B, Erdélyi F, Szabó G, Wagner L, Kovacs GG, Hökfelt T, Harkany T, Alpár A. Secretagogin expression in the vertebrate brainstem with focus on the noradrenergic system and implications for Alzheimer's disease. Brain Struct Funct 2019; 224:2061-2078. [PMID: 31144035 PMCID: PMC6591208 DOI: 10.1007/s00429-019-01886-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 05/03/2019] [Indexed: 12/04/2022]
Abstract
Calcium-binding proteins are widely used to distinguish neuronal subsets in the brain. This study focuses on secretagogin, an EF-hand calcium sensor, to identify distinct neuronal populations in the brainstem of several vertebrate species. By using neural tube whole mounts of mouse embryos, we show that secretagogin is already expressed during the early ontogeny of brainstem noradrenaline cells. In adults, secretagogin-expressing neurons typically populate relay centres of special senses and vegetative regulatory centres of the medulla oblongata, pons and midbrain. Notably, secretagogin expression overlapped with the brainstem column of noradrenergic cell bodies, including the locus coeruleus (A6) and the A1, A5 and A7 fields. Secretagogin expression in avian, mouse, rat and human samples showed quasi-equivalent patterns, suggesting conservation throughout vertebrate phylogeny. We found reduced secretagogin expression in locus coeruleus from subjects with Alzheimer’s disease, and this reduction paralleled the loss of tyrosine hydroxylase, the enzyme rate limiting noradrenaline synthesis. Residual secretagogin immunoreactivity was confined to small submembrane domains associated with initial aberrant tau phosphorylation. In conclusion, we provide evidence that secretagogin is a useful marker to distinguish neuronal subsets in the brainstem, conserved throughout several species, and its altered expression may reflect cellular dysfunction of locus coeruleus neurons in Alzheimer’s disease.
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Affiliation(s)
- Péter Zahola
- SE NAP B Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, Budapest, Hungary.,Department of Anatomy, Semmelweis University, Budapest, Hungary
| | - János Hanics
- SE NAP B Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, Budapest, Hungary.,Department of Anatomy, Semmelweis University, Budapest, Hungary
| | - Anna Pintér
- Department of Anatomy, Semmelweis University, Budapest, Hungary
| | - Zoltán Máté
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Anna Gáspárdy
- Department of Anatomy, Semmelweis University, Budapest, Hungary
| | - Zsófia Hevesi
- SE NAP B Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, Budapest, Hungary.,Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, 1090, Vienna, Austria
| | - Diego Echevarria
- Institute of Neuroscience, University of Miguel Hernandez de Elche, Alicante, Spain
| | - Csaba Adori
- Department of Neuroscience, Karolinska Institutet, Biomedicum 7D, SE-17165, Stockholm, Sweden
| | - Swapnali Barde
- Department of Neuroscience, Karolinska Institutet, Biomedicum 7D, SE-17165, Stockholm, Sweden
| | - Beáta Törőcsik
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary
| | - Ferenc Erdélyi
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gábor Szabó
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Ludwig Wagner
- Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Gabor G Kovacs
- Institute of Neurology, Medical University of Vienna, Vienna, Austria
| | - Tomas Hökfelt
- Department of Neuroscience, Karolinska Institutet, Biomedicum 7D, SE-17165, Stockholm, Sweden
| | - Tibor Harkany
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, 1090, Vienna, Austria.,Department of Neuroscience, Karolinska Institutet, Biomedicum 7D, SE-17165, Stockholm, Sweden
| | - Alán Alpár
- SE NAP B Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, Budapest, Hungary. .,Department of Anatomy, Semmelweis University, Budapest, Hungary.
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Alpár A, Zahola P, Hanics J, Hevesi Z, Korchynska S, Benevento M, Pifl C, Zachar G, Perugini J, Severi I, Leitgeb P, Bakker J, Miklosi AG, Tretiakov E, Keimpema E, Arque G, Tasan RO, Sperk G, Malenczyk K, Máté Z, Erdélyi F, Szabó G, Lubec G, Palkovits M, Giordano A, Hökfelt TG, Romanov RA, Horvath TL, Harkany T. Hypothalamic CNTF volume transmission shapes cortical noradrenergic excitability upon acute stress. EMBO J 2018; 37:e100087. [PMID: 30209240 PMCID: PMC6213283 DOI: 10.15252/embj.2018100087] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/10/2018] [Accepted: 08/13/2018] [Indexed: 02/06/2023] Open
Abstract
Stress-induced cortical alertness is maintained by a heightened excitability of noradrenergic neurons innervating, notably, the prefrontal cortex. However, neither the signaling axis linking hypothalamic activation to delayed and lasting noradrenergic excitability nor the molecular cascade gating noradrenaline synthesis is defined. Here, we show that hypothalamic corticotropin-releasing hormone-releasing neurons innervate ependymal cells of the 3rd ventricle to induce ciliary neurotrophic factor (CNTF) release for transport through the brain's aqueductal system. CNTF binding to its cognate receptors on norepinephrinergic neurons in the locus coeruleus then initiates sequential phosphorylation of extracellular signal-regulated kinase 1 and tyrosine hydroxylase with the Ca2+-sensor secretagogin ensuring activity dependence in both rodent and human brains. Both CNTF and secretagogin ablation occlude stress-induced cortical norepinephrine synthesis, ensuing neuronal excitation and behavioral stereotypes. Cumulatively, we identify a multimodal pathway that is rate-limited by CNTF volume transmission and poised to directly convert hypothalamic activation into long-lasting cortical excitability following acute stress.
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Affiliation(s)
- Alán Alpár
- SE NAP Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, Budapest, Hungary
- Department of Anatomy, Histology, and Embryology, Semmelweis University, Budapest, Hungary
| | - Péter Zahola
- SE NAP Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, Budapest, Hungary
- Department of Anatomy, Histology, and Embryology, Semmelweis University, Budapest, Hungary
| | - János Hanics
- SE NAP Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, Budapest, Hungary
- Department of Anatomy, Histology, and Embryology, Semmelweis University, Budapest, Hungary
| | - Zsófia Hevesi
- SE NAP Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, Budapest, Hungary
| | - Solomiia Korchynska
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Marco Benevento
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Christian Pifl
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Gergely Zachar
- Department of Anatomy, Histology, and Embryology, Semmelweis University, Budapest, Hungary
| | - Jessica Perugini
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | - Ilenia Severi
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | - Patrick Leitgeb
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Joanne Bakker
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Andras G Miklosi
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | | | - Erik Keimpema
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Gloria Arque
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Ramon O Tasan
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Günther Sperk
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Katarzyna Malenczyk
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Zoltán Máté
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Ferenc Erdélyi
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gábor Szabó
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gert Lubec
- Paracelsus Medical University, Salzburg, Austria
| | - Miklós Palkovits
- Department of Anatomy, Histology, and Embryology, Semmelweis University, Budapest, Hungary
- Human Brain Tissue Bank and Laboratory, Semmelweis University, Budapest, Hungary
| | - Antonio Giordano
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | - Tomas Gm Hökfelt
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Roman A Romanov
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
- Immanuel Kant Baltic Federal University, Kaliningrad, Russia
| | - Tamas L Horvath
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Departments of Comparative Medicine and Neuroscience, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
- Department of Anatomy and Histology, University of Veterinary Medicine, Budapest, Hungary
| | - Tibor Harkany
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
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Abstract
The small GTPase Ras is a universal eukaryotic cytoplasmic membrane-anchored protein, which regulates diverse downstream signal transduction pathways that play an important role in the proper functioning of neurons. Ras activity is a central regulator of structural and functional synaptic plasticity in the adult nervous system, where it channels neuronal responses to various extracellular cues allowing the organism to adapt to complex environmental stimuli. The suprachiasmatic nucleus (SCN) is the principle pacemaker of the circadian clock, and the circadian and photic regulation of Ras activity in the SCN is an important modulator of the clockwork. We have generated transgenic mouse expressing constitutively active V12-H-Ras selectively in neurons via a synapsin I promoter (synRas mice), which serves as a suitable model to study the role of neuronal Ras signaling. Modulation of Ras activity affects ERK1,2/CREB signaling and glycogen synthase kinase-3 beta expression in the SCN, which in turn modify the photoentrainment of the clock and the fine tuning the circadian period length. The main focus of this review is to offer an overview of the function of Ras signaling in the circadian rhythm and its potential role in learning and memory consolidation.
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Affiliation(s)
- Tsvetan Serchov
- Department of Psychiatry and Psychotherapy, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Rolf Heumann
- Biochemistry II, Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
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The small G protein H-Ras in the mesolimbic system is a molecular gateway to alcohol-seeking and excessive drinking behaviors. J Neurosci 2013; 32:15849-58. [PMID: 23136424 DOI: 10.1523/jneurosci.2846-12.2012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Uncontrolled consumption of alcohol is a hallmark of alcohol abuse disorders; however, the central molecular mechanisms underlying excessive alcohol consumption are still unclear. Here, we report that the GTP binding protein, H-Ras in the nucleus accumbens (NAc) plays a key role in neuroadaptations that underlie excessive alcohol-drinking behaviors. Specifically, acute (15 min) systemic administration of alcohol (2.5 g/kg) leads to the activation of H-Ras in the NAc of mice, which is observed even 24 h later. Similarly, rat operant self-administration of alcohol (20%) also results in the activation of H-Ras in the NAc. Using the same procedures, we provide evidence suggesting that the exchange factor GRF1 is upstream of H-Ras activation by alcohol. Importantly, we show that infection of mice NAc with lentivirus expressing a short hairpin RNA that targets the H-Ras gene produces a significant reduction of voluntary consumption of 20% alcohol. In contrast, knockdown of H-Ras in the NAc of mice did not alter water, quinine, and saccharin intake. Furthermore, using two-bottle choice and operant self-administration procedures, we show that inhibiting H-Ras activity by intra-NAc infusion of the farnesyltransferase inhibitor, FTI-276, produced a robust decrease of rats' alcohol drinking; however, sucrose consumption was unaltered. Finally, intra-NAc infusion of FTI-276 also resulted in an attenuation of seeking for alcohol. Together, these results position H-Ras as a central molecular mediator of alcohol's actions within the mesolimbic system and put forward the potential value of the enzyme as a novel target to treat alcohol use disorders.
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Antonucci F, Alpár A, Kacza J, Caleo M, Verderio C, Giani A, Martens H, Chaudhry FA, Allegra M, Grosche J, Michalski D, Erck C, Hoffmann A, Harkany T, Matteoli M, Härtig W. Cracking down on inhibition: selective removal of GABAergic interneurons from hippocampal networks. J Neurosci 2012; 32:1989-2001. [PMID: 22323713 PMCID: PMC3742881 DOI: 10.1523/jneurosci.2720-11.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 12/07/2011] [Accepted: 12/14/2011] [Indexed: 12/12/2022] Open
Abstract
Inhibitory (GABAergic) interneurons entrain assemblies of excitatory principal neurons to orchestrate information processing in the hippocampus. Disrupting the dynamic recruitment as well as the temporally precise activity of interneurons in hippocampal circuitries can manifest in epileptiform seizures, and impact specific behavioral traits. Despite the importance of GABAergic interneurons during information encoding in the brain, experimental tools to selectively manipulate GABAergic neurotransmission are limited. Here, we report the selective elimination of GABAergic interneurons by a ribosome inactivation approach through delivery of saporin-conjugated anti-vesicular GABA transporter antibodies (SAVAs) in vitro as well as in the mouse and rat hippocampus in vivo. We demonstrate the selective loss of GABAergic--but not glutamatergic--synapses, reduced GABA release, and a shift in excitation/inhibition balance in mixed cultures of hippocampal neurons exposed to SAVAs. We also show the focal and indiscriminate loss of calbindin(+), calretinin(+), parvalbumin/system A transporter 1(+), somatostatin(+), vesicular glutamate transporter 3 (VGLUT3)/cholecystokinin/CB(1) cannabinoid receptor(+) and neuropeptide Y(+) local-circuit interneurons upon SAVA microlesions to the CA1 subfield of the rodent hippocampus, with interneuron debris phagocytosed by infiltrating microglia. SAVA microlesions did not affect VGLUT1(+) excitatory afferents. Yet SAVA-induced rearrangement of the hippocampal circuitry triggered network hyperexcitability associated with the progressive loss of CA1 pyramidal cells and the dispersion of dentate granule cells. Overall, our data identify SAVAs as an effective tool to eliminate GABAergic neurons from neuronal circuits underpinning high-order behaviors and cognition, and whose manipulation can recapitulate pathogenic cascades of epilepsy and other neuropsychiatric illnesses.
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Affiliation(s)
- Flavia Antonucci
- Department of Medical Pharmacology, CNR Institute of Neuroscience, Università di Milano and
- Fondazione Filarete, I-20129 Milan, Italy
| | - Alán Alpár
- Division of Molecular Neurobiology, Department of Medical Biochemistry & Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Johannes Kacza
- Institute of Veterinary Anatomy, University of Leipzig, D-04103 Leipzig, Germany
| | - Matteo Caleo
- CNR Institute of Neuroscience, I-51600 Pisa, Italy
| | - Claudia Verderio
- Department of Medical Pharmacology, CNR Institute of Neuroscience, Università di Milano and
| | - Alice Giani
- Department of Medical Pharmacology, CNR Institute of Neuroscience, Università di Milano and
| | | | - Farrukh A. Chaudhry
- The Biotechnology Centre of Oslo & Centre for Molecular Biology and Neuroscience, University of Oslo, N-0317 Oslo, Norway
| | | | - Jens Grosche
- Paul Flechsig Institute for Brain Research, University of Leipzig, D-04109 Leipzig, Germany
| | - Dominik Michalski
- Department of Neurology, University of Leipzig, D-04103 Leipzig, Germany
| | | | - Anke Hoffmann
- Institute of Veterinary Anatomy, University of Leipzig, D-04103 Leipzig, Germany
| | - Tibor Harkany
- Division of Molecular Neurobiology, Department of Medical Biochemistry & Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden
- European Neuroscience Institute, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom, and
| | - Michela Matteoli
- Department of Medical Pharmacology, CNR Institute of Neuroscience, Università di Milano and
- Instituto Clinico Humanitas, IRCCS, Rozzano, I-20089 Milan, Italy
| | - Wolfgang Härtig
- Paul Flechsig Institute for Brain Research, University of Leipzig, D-04109 Leipzig, Germany
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Localization of pre- and postsynaptic cholinergic markers in rodent forebrain: a brief history and comparison of rat and mouse. Behav Brain Res 2010; 221:356-66. [PMID: 21129407 DOI: 10.1016/j.bbr.2010.11.051] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 11/23/2010] [Indexed: 11/23/2022]
Abstract
Rat and mouse models are widely used for studies in cognition and pathophysiology, among others. Here, we sought to determine to what extent these two model species differ for cholinergic and cholinoceptive features. For this purpose, we focused on cholinergic innervation patterns based on choline acetyltransferase (ChAT) immunostaining, and the expression of muscarinic acetylcholine receptors (mAChRs) detected immunocytochemically. In this brief review we first place cholinergic and cholinoceptive markers in a historic perspective, and then provide an overview of recent publications on cholinergic studies and techniques to provide a literature survey of current research. Next, we compare mouse (C57Bl/J6) and rat (Wistar) cholinergic and cholinoceptive systems simultaneously stained, respectively, for ChAT (analyzed qualitatively) and mAChRs (analyzed qualitatively and quantitatively). In general, the topographic cholinergic innervation patterns of both rodent species are highly comparable, with only considerable (but region specific) differences in number of detectable cholinergic interneurons, which are more numerous in rat. In contrast, immunolabeling for mAChRs, detected by the monoclonal antibody M35, differs markedly in the forebrain between the two species. In mouse brain, basal levels of activated and/or internalized mAChRs (as a consequence of cholinergic neurotransmission) are significantly higher. This suggests a higher cholinergic tone in mouse than rat, and hence the animal model of choice may have consequences for cholinergic drug testing experiments.
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Ye X, Carew TJ. Small G protein signaling in neuronal plasticity and memory formation: the specific role of ras family proteins. Neuron 2010; 68:340-61. [PMID: 21040840 PMCID: PMC3008420 DOI: 10.1016/j.neuron.2010.09.013] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2010] [Indexed: 01/04/2023]
Abstract
Small G proteins are an extensive family of proteins that bind and hydrolyze GTP. They are ubiquitous inside cells, regulating a wide range of cellular processes. Recently, many studies have examined the role of small G proteins, particularly the Ras family of G proteins, in memory formation. Once thought to be primarily involved in the transduction of a variety of extracellular signals during development, it is now clear that Ras family proteins also play critical roles in molecular processing underlying neuronal and behavioral plasticity. We here review a number of recent studies that explore how the signaling of Ras family proteins contributes to memory formation. Understanding these signaling processes is of fundamental importance both from a basic scientific perspective, with the goal of providing mechanistic insights into a critical aspect of cognitive behavior, and from a clinical perspective, with the goal of providing effective therapies for a range of disorders involving cognitive impairments.
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Affiliation(s)
- Xiaojing Ye
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA 92697, USA
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Alpár A, Naumann N, Arendt T, Gärtner U. Constitutively enhanced p21Ras activity amplifies dendritic remodeling of hippocampal neurons during physical activity. Int J Dev Neurosci 2009; 27:407-11. [DOI: 10.1016/j.ijdevneu.2009.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 02/24/2009] [Accepted: 03/04/2009] [Indexed: 10/21/2022] Open
Affiliation(s)
- Alán Alpár
- Department of Anatomy, Histology and EmbryologySemmelweis University Medical SchoolTűzoltó u. 58H‐1450BudapestHungary
| | - Nicole Naumann
- Department of Molecular and Cellular Mechanisms of NeurodegenerationPaul Flechsig Institute for Brain Research, Universität LeipzigD‐04109LeipzigGermany
| | - Thomas Arendt
- Department of Molecular and Cellular Mechanisms of NeurodegenerationPaul Flechsig Institute for Brain Research, Universität LeipzigD‐04109LeipzigGermany
| | - Ulrich Gärtner
- Department of Molecular and Cellular Mechanisms of NeurodegenerationPaul Flechsig Institute for Brain Research, Universität LeipzigD‐04109LeipzigGermany
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Alpr A, Naumann N, Hrtig W, Arendt T, Grtner U. Enhanced Ras activity preserves dendritic size and extension as well as synaptic contacts of neurons after functional deprivation in synRas mice. Eur J Neurosci 2008; 27:3083-94. [DOI: 10.1111/j.1460-9568.2008.06313.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Alpár A, Ueberham U, Seeger G, Arendt T, Gärtner U. Effects of wild-type and mutant human amyloid precursor protein on cortical afferent network. Neuroreport 2007; 18:1247-50. [PMID: 17632276 DOI: 10.1097/wnr.0b013e3282202829] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Alzheimer's disease is characterized by severe neuronal disintegration supposed to be partly associated with amyloid pathology. Recently, we described morphological alterations of pyramidal cell structure in transgenic mice expressing wild-type or mutant human amyloid precursor protein (hAPP) (strains B6-Py8.9 and Tg2576), which are unrelated to direct plaque-associated changes. In this study, we focused on the pattern of cortical afferent connections in these transgenic mice. The quantity of cholinergic afferents is increased in both transgenic lines. Glutamatergic intra- and interhemispheric afferents are augmented in B6-Py8.9 mice but decreased in Tg2576 mice. Furthermore, perisomatic inhibition of pyramidal neurons was found to be reduced in Tg2576 mice. Findings suggest different effects of wild-type and mutant hAPP on neuronal connectivity.
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Affiliation(s)
- Alán Alpár
- Department of Anatomy, Histology and Embryology, Semmelweis University Medical School, Budapest, Hungary.
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Gärtner U, Alpár A, Seeger G, Heumann R, Arendt T. Enhanced Ras activity in pyramidal neurons induces cellular hypertrophy and changes in afferent and intrinsic connectivity in synRas mice. Int J Dev Neurosci 2004; 22:165-73. [PMID: 15140470 DOI: 10.1016/j.ijdevneu.2004.02.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Accepted: 02/04/2004] [Indexed: 01/19/2023] Open
Abstract
Neurotrophic actions are critically controlled and transmitted to cellular responses by the small G protein Ras which is therefore essential for normal functioning and plasticity of the nervous system. The present study summarises findings of recent studies on morphological changes in the neocortex of synRas mice expressing Val12-Ha-Ras in vivo under the control of the rat synapsin I promoter. In the here reported model (introduced by Heumann et al. [J. Cell Biol. 151 (2000) 1537]), transgenic Val12-Ha-Ras expression is confined to the pyramidal cell population and starts postnatally at a time, when neurons are postmitotic and their developmental maturation has been basically completed. Expression of Val12-Ha-Ras results in a significant enlargement of pyramidal neurons. Size, complexity and spine density of dendritic trees are increased, which leads, finally, to cortical expansion. However, the main morphological design principles of 'transgenic' pyramidal cells remain preserved. In addition to somato-dendritic changes, expression of Val12-Ha-Ras in pyramidal cells induces augmented axon calibres and upregulates the establishment of efferent boutons. Despite the enlargement of cortical size, the overall density of terminals representing intra- or interhemispheric, specific and non-specific afferents is unchanged or even higher in transgenic mice suggesting a significant increase in the total afferent input to the neocortex. Although interneurons do not express the transgene and are therefore excluded from direct, intrinsic Val12-Ha-Ras effects, they respond with morphological adaptations to structural changes. Thus, dendritic arbours of interneurons are extended to follow the cortical expansion and basket cells establish a denser inhibitory innervation of 'transgenic' pyramidal cells perikarya. It is concluded that expression of Val12-Ha-Ras in pyramidal neurons results in remodelling of neocortical structuring which strongly implicates a crucial involvement of Ras in cortical plasticity.
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Affiliation(s)
- Ulrich Gärtner
- Department of Neuroanatomy, Paul Flechsig Institute for Brain Research, University of Leipzig, Jahnallee 59, D-04109 Leipzig, Germany.
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