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Ablation of p75 NTR signaling strengthens gamma-theta rhythm interaction and counteracts Aβ-induced degradation of neuronal dynamics in mouse hippocampus in vitro. Transl Psychiatry 2021; 11:212. [PMID: 33837176 PMCID: PMC8035168 DOI: 10.1038/s41398-021-01332-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/09/2021] [Accepted: 03/26/2021] [Indexed: 11/09/2022] Open
Abstract
Gamma and theta brain rhythms play important roles in cognition and their interaction can affect gamma oscillation features. Hippocampal theta oscillations depend on cholinergic and GABAergic input from the medial septum-diagonal band of Broca. These projecting neurons undergo degeneration during aging and maintain high levels of neurotrophin receptor p75 (p75NTR). p75NTR mediates both apoptosis and survival and its expression is increased in Alzheimer's disease (AD) patients. Here, we investigate the importance of p75NTR for the cholinergic input to the hippocampus. Performing extracellular recordings in brain slices from p75NTR knockout mice (p75-/-) in presence of the muscarinic agonist carbachol, we find that gamma oscillation power and rhythmicity are increased compared to wild-type (WT) mice. Furthermore, gamma activity is more phase-locked to the underlying theta rhythm, which renders a stronger coupling of both rhythms. On the cellular level, we find that fast-spiking interneurons (FSNs) fire more synchronized to a preferred gamma phase in p75-/- mice. The excitatory input onto FSN is more rhythmic displaying a higher similarity with the concomitant gamma rhythm. Notably, the ablation of p75NTR counteracts the Aβ-induced degradation of gamma oscillations and its nesting within the underlying theta rhythm. Our results show that the lack of p75NTR signaling could promote stronger cholinergic modulation of the hippocampal gamma rhythm, suggesting an involvement of p75NTR in the downregulation of cognition-relevant hippocampal network dynamics in pathologies. Moreover, functional data provided here suggest p75NTR as a suitable target in the search for efficacious treatments to counteract the loss of cognitive function observed in amyloid-driven pathologies such as AD.
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Modulation of the p75 neurotrophin receptor suppresses age-related basal forebrain cholinergic neuron degeneration. Sci Rep 2019; 9:5273. [PMID: 30918278 PMCID: PMC6437186 DOI: 10.1038/s41598-019-41654-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 02/08/2019] [Indexed: 11/19/2022] Open
Abstract
Age-related degeneration of basal forebrain cholinergic neurons (BFCNs) is linked to cognitive impairment. The p75 neurotrophin receptor (p75NTR) has been proposed to mediate neuronal degeneration in aging. Therefore, we tested the hypothesis that modifying p75NTR function would prevent or reverse aging-related neuronal degeneration using LM11A-31, a small molecule p75NTR modulator that downregulates degenerative and upregulates trophic receptor-associated signaling. Morphological analysis in mice showed loss of BFCN area detectable by 18 months of age. Oral administration of LM11A-31 from age 15 to 18 months resulted in a dose-related preservation of BFCN area and one month of treatment from 17 to 18 months also preserved cell area. To evaluate reversal of established neuronal atrophy, animals were treated from 21 to 25 months of age. Treatment was associated with an increase of cell size to a mean area larger than that observed at 18 months, accompanied by increases in mean MS/VDB neurite length, as well as increased cholinergic fiber density and synaptophysin pre-synaptic marker levels in the hippocampus. These findings support the idea that modulation of p75NTR activity can prevent and potentially reverse age-associated BFCN degeneration. Moreover, this may be achieved therapeutically with orally bioavailable agents such as LM11A-31.
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Boskovic Z, Meier S, Wang Y, Milne M, Onraet T, Tedoldi A, Coulson E. Regulation of cholinergic basal forebrain development, connectivity, and function by neurotrophin receptors. Neuronal Signal 2019; 3:NS20180066. [PMID: 32269831 PMCID: PMC7104233 DOI: 10.1042/ns20180066] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/15/2019] [Accepted: 01/15/2019] [Indexed: 12/11/2022] Open
Abstract
Cholinergic basal forebrain (cBF) neurons are defined by their expression of the p75 neurotrophin receptor (p75NTR) and tropomyosin-related kinase (Trk) neurotrophin receptors in addition to cholinergic markers. It is known that the neurotrophins, particularly nerve growth factor (NGF), mediate cholinergic neuronal development and maintenance. However, the role of neurotrophin signalling in regulating adult cBF function is less clear, although in dementia, trophic signalling is reduced and p75NTR mediates neurodegeneration of cBF neurons. Here we review the current understanding of how cBF neurons are regulated by neurotrophins which activate p75NTR and TrkA, B or C to influence the critical role that these neurons play in normal cortical function, particularly higher order cognition. Specifically, we describe the current evidence that neurotrophins regulate the development of basal forebrain neurons and their role in maintaining and modifying mature basal forebrain synaptic and cortical microcircuit connectivity. Understanding the role neurotrophin signalling plays in regulating the precision of cholinergic connectivity will contribute to the understanding of normal cognitive processes and will likely provide additional ideas for designing improved therapies for the treatment of neurological disease in which cholinergic dysfunction has been demonstrated.
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Affiliation(s)
- Zoran Boskovic
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Sonja Meier
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Yunpeng Wang
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
- College of Forensic Science, Xi’an Jiaotong University, Shaanxi, China
| | - Michael R. Milne
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Tessa Onraet
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Angelo Tedoldi
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Elizabeth J. Coulson
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
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Bobkova N, Vorobyov V, Medvinskaya N, Nesterova I, Tatarnikova O, Nekrasov P, Samokhin A, Deev A, Sengpiel F, Koroev D, Volpina O. Immunization Against Specific Fragments of Neurotrophin p75 Receptor Protects Forebrain Cholinergic Neurons in the Olfactory Bulbectomized Mice. J Alzheimers Dis 2018; 53:289-301. [PMID: 27163825 PMCID: PMC4942728 DOI: 10.3233/jad-160146] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Alzheimer’s disease (AD) is characterized by progressive cognitive impairment associated with marked cholinergic neuron loss and amyloid-β (Aβ) peptide accumulation in the brain. The cytotoxicity in AD is mediated, at least in part, by Aβ binding with the extracellular domain of the p75 neurotrophin receptor (p75NTR), localized predominantly in the membranes of acetylcholine-producing neurons in the basal forebrain. Hypothesizing that an open unstructured loop of p75NTR might be the effective site for Aβ binding, we have immunized both olfactory bulbectomized (OBX) and sham-operated (SO) mice (n = 82 and 49, respectively) with synthetic peptides, structurally similar to different parts of the loops, aiming to block them by specific antibodies. OBX-mice have been shown in previous studies, and confirmed in the present one, to be characterized by typical behavioral, morphological, and biochemical AD hallmarks, including cholinergic deficits in forebrain neurons. Immunization of OBX- or SO-mice with KLH conjugated fragments of p75NTR induced high titers of specific serum antibodies for each of nine chosen fragments. However, maximal protective effects on spatial memory, evaluated in a Morris water maze, and on activity of choline acetyltransferase in forebrain neurons, detected by immunoreactivity to specific antibodies, were revealed only for peptides with amino acid residue sequences of 155–164 and 167–176. We conclude that the approach based on immunological blockade of specific p75NTR sites, linked with the cytotoxicity, is a useful and effective tool for study of AD-associated mechanisms and for development of highly selective therapy of cholinergic malfunctioning in AD patients.
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Affiliation(s)
- Natalia Bobkova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Vasily Vorobyov
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Natalia Medvinskaya
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Inna Nesterova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Olga Tatarnikova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Pavel Nekrasov
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Alexander Samokhin
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Alexander Deev
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Frank Sengpiel
- School of Biosciences and Neuroscience & Mental Health Research Institute, Cardiff University, Museum Avenue, Cardiff, UK
| | - Dmitry Koroev
- Shemyakin's-Ovchinnikov's Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Olga Volpina
- Shemyakin's-Ovchinnikov's Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
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Puschban Z, Sah A, Grutsch I, Singewald N, Dechant G. Reduced Anxiety-Like Behavior and Altered Hippocampal Morphology in Female p75NTR(exon IV-/-) Mice. Front Behav Neurosci 2016; 10:103. [PMID: 27313517 PMCID: PMC4887477 DOI: 10.3389/fnbeh.2016.00103] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 05/13/2016] [Indexed: 02/05/2023] Open
Abstract
The presence of the p75 neurotrophin receptor (p75NTR) in adult basal forebrain cholinergic neurons, precursor cells in the subventricular cell layer and the subgranular cell layer of the hippocampus has been linked to alterations in learning as well as anxiety- and depression- related behaviors. In contrast to previous studies performed in a p75NTRexon III−/− model still expressing the short isoform of the p75NTR, we focused on locomotor and anxiety–associated behavior in p75NTRexon IV−/− mice lacking both p75NTR isoforms. Comparing p75NTRexon IV−/− and wildtype mice for both male and female animals showed an anxiolytic-like behavior as evidenced by increased central activities in the open field paradigm and flex field activity system as well as higher numbers of open arm entries in the elevated plus maze test in female p75NTR knockout mice. Morphometrical analyses of dorsal and ventral hippocampus revealed a reduction of width of the dentate gyrus and the granular cell layer in the dorsal but not ventral hippocampus in male and female p75NTRexon IV−/− mice. We conclude that germ-line deletion of p75NTR seems to differentially affect morphometry of dorsal and ventral dentate gyrus and that p75NTR may play a role in anxiety-like behavior, specifically in female mice.
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Affiliation(s)
- Zoe Puschban
- Department of Neuroscience, Innsbruck Medical University Innsbruck, Austria
| | - Anupam Sah
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences (CMBI), Leopold-Franzens University of Innsbruck Innsbruck, Austria
| | - Isabella Grutsch
- Department of Neuroscience, Innsbruck Medical University Innsbruck, Austria
| | - Nicolas Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences (CMBI), Leopold-Franzens University of Innsbruck Innsbruck, Austria
| | - Georg Dechant
- Department of Neuroscience, Innsbruck Medical University Innsbruck, Austria
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Barrett GL, Naim T, Trieu J, Huang M. In vivo knockdown of basal forebrain p75 neurotrophin receptor stimulates choline acetyltransferase activity in the mature hippocampus. J Neurosci Res 2016; 94:389-400. [DOI: 10.1002/jnr.23717] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Revised: 12/15/2015] [Accepted: 01/11/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Graham L. Barrett
- Department of Physiology; University of Melbourne; Melbourne Victoria Australia
| | - Timur Naim
- Department of Physiology; University of Melbourne; Melbourne Victoria Australia
| | - Jennifer Trieu
- Department of Physiology; University of Melbourne; Melbourne Victoria Australia
| | - Mengjie Huang
- Department of Physiology; University of Melbourne; Melbourne Victoria Australia
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Poser R, Dokter M, von Bohlen Und Halbach V, Berger SM, Busch R, Baldus M, Unsicker K, von Bohlen Und Halbach O. Impact of a deletion of the full-length and short isoform of p75NTR on cholinergic innervation and the population of postmitotic doublecortin positive cells in the dentate gyrus. Front Neuroanat 2015; 9:63. [PMID: 26074780 PMCID: PMC4444824 DOI: 10.3389/fnana.2015.00063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 05/06/2015] [Indexed: 12/19/2022] Open
Abstract
Analyses of mice carrying a deletion of the pan-neurotrophin receptor p75NTR have allowed identifying p75NTR as an important structural regulator of the hippocampus. Most of the previous analyses were done using p75NTR (ExIII) knockout mice which still express the short isoform of p75NTR. To scrutinize the role of p75NTR in the hippocampus, we analyzed adult and aged p75NTR (ExIV) knockout mice, in which both, the short and the full-length isoform are deleted. Deletion of these isoforms induced morphological alterations in the adult dentate gyrus (DG), leading to an increase in the thickness of the molecular and granular layer. Based on these observations, we next determined the morphological substrates that might contribute to this phenotype. The cholinergic innervation of the molecular and granular layer of the DG was found to be significantly increased in the knockout mice. Furthermore, adult neurogenesis in the DG was found to be significantly altered with increased numbers of doublecortin (DCX) positive cells and reduced numbers of apoptotic cells in p75NTR (ExIV) knockout mice. However, cell proliferation as measured by phosphohiston H3 (PH3) positive cell numbers was not affected. These morphological alterations (number of DCX-positive cells and increased cholinergic fiber densities) as well as reduced cell death in the DG are likely to contribute to the observed thickening of the granular layer in p75NTR (ExIV) knockout mice. In addition, Sholl-analysis of DCX-positive neurons revealed a higher dendritic complexity and could thus be a possible morphological correlate for the increased thickness of the molecular layer in p75NTR deficient animals. Our data clearly demonstrate that deletion of both, the short and the full-length isoform of p75NTR affects DG morphology, due to alterations of the cholinergic system and an imbalance between neurogenesis and programmed cell death within the subgranular zone.
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Affiliation(s)
- Robert Poser
- Institute of Anatomy and Cell Biology, Universitätsmedizin Greifswald Greifswald, Germany
| | - Martin Dokter
- Institute of Anatomy and Cell Biology, Universitätsmedizin Greifswald Greifswald, Germany
| | | | - Stefan M Berger
- Department of Molecular Biology, Central Institute of Mental Health and Medical Faculty Mannheim, Heidelberg University Mannheim, Germany
| | - Ruben Busch
- Institute of Anatomy and Cell Biology, Universitätsmedizin Greifswald Greifswald, Germany
| | - Marian Baldus
- Institute of Anatomy and Cell Biology, Universitätsmedizin Greifswald Greifswald, Germany
| | - Klaus Unsicker
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, University of Freiburg Freiburg, Germany
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8
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Murphy M, Wilson YM, Vargas E, Munro KM, Smith B, Huang A, Li QX, Xiao J, Masters CL, Reid CA, Barrett GL. Reduction of p75 neurotrophin receptor ameliorates the cognitive deficits in a model of Alzheimer's disease. Neurobiol Aging 2015; 36:740-52. [PMID: 25443284 DOI: 10.1016/j.neurobiolaging.2014.09.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 08/28/2014] [Accepted: 09/18/2014] [Indexed: 12/29/2022]
Abstract
Alzheimer's disease (AD) is an extremely prevalent cause of dementia. It is characterized by progressive memory loss, confusion, and other behavioral and physiological problems. The amyloid-β (Aβ) protein is thought to be involved in the pathogenesis of AD, and there is evidence that Aβ may act through the p75 neurotrophin receptor (p75) to mediate its pathogenic effects. This raises the possibility that reducing levels of p75 could be a treatment for AD by preventing the effects of Aβ. In this study, we have crossed the transgenic AD model mice, Tg2576, with p75(-/-) mice to generate Tg2576/p75(+/-) mice with reduced levels of p75. These mice are rescued from the deficits in learning and memory and hippocampal function which were found in the Tg2576 mice. These findings suggest that reduction of p75 can ameliorate some of the primary symptoms of AD.
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Affiliation(s)
- Mark Murphy
- Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia.
| | - Yvette M Wilson
- Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia
| | - Ernesto Vargas
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Kathryn M Munro
- Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia
| | - Belinda Smith
- Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Amy Huang
- Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Qiao-Xin Li
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Junhua Xiao
- Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia
| | - Colin L Masters
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher A Reid
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Graham L Barrett
- Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia
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Grabenstatter HL, Carlsen J, Raol YH, Yang T, Hund D, Cruz Del Angel Y, White AM, Gonzalez MI, Longo FM, Russek SJ, Brooks-Kayal AR. Acute administration of the small-molecule p75(NTR) ligand does not prevent hippocampal neuron loss or development of spontaneous seizures after pilocarpine-induced status epilepticus. J Neurosci Res 2014; 92:1307-18. [PMID: 24801281 DOI: 10.1002/jnr.23402] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/24/2014] [Accepted: 03/31/2014] [Indexed: 02/02/2023]
Abstract
Neurotrophins, such as brain-derived neurotrophic factor (BDNF), are initially expressed in a precursor form (e.g., pro-BDNF) and cleaved to form mature BDNF (mBDNF). After pilocarpine-induced status epilepticus (SE), increases in neurotrophins regulate a wide variety of cell-signaling pathways, including prosurvival and cell-death machinery in a receptor-specific manner. Pro-BDNF preferentially binds to the p75 neurotrophin receptor (p75(NTR) ), whereas mBDNF is the major ligand of the tropomyosin-related kinase receptor. To elucidate a potential role for p75(NTR) in acute stages of epileptogenesis, rats were injected prior to and at onset of SE with LM11A-31, a small-molecule ligand that binds to p75(NTR) to promote survival signaling and inhibit neuronal cell death. Modulation of early p75(NTR) signaling and its effects on electrographic SE, SE-induced neurodegeneration, and subsequent spontaneous seizures were examined after LM11A-31 administration. Despite an established neuroprotective effect of LM11A-31 in several animal models of neurodegenerative disorders (e.g., Alzheimer's disease, traumatic brain injury, and spinal cord injury), high-dose LM11A-31 administration prior to and at onset of SE did not reduce the intensity of electrographic SE, prevent SE-induced neuronal cell injury, or inhibit the progression of epileptogenesis. Further studies are required to understand the role of p75(NTR) activation during epileptogenesis and in seizure-induced cell injury in the hippocampus, among other potential cellular pathologies contributing to the onset of spontaneous seizures. Additional studies utilizing more prolonged treatment with LM11A-31 are required to reach a definite conclusion on its potential neuroprotective role in epilepsy.
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Affiliation(s)
- H L Grabenstatter
- Department of Pediatrics, Division of Neurology, and Translational Epilepsy Research Program, University of Colorado School of Medicine, Aurora, Colorado
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10
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Abstract
Cholinergic neurotransmission has been shown to play an important role in modulating attentional processing of visual stimuli. However, it is not yet clear whether the neurochemical acetylcholine (ACh) is necessary exclusively for visual attention, or if it also contributes to attentional functions through some modality-independent (supramodal) mechanism. To answer this question, we examined the effects of reduced cortical cholinergic afferentation on both a traditional visual and a novel olfactory five-choice serial reaction time task (5-CSRTT), the benchmark rodent test of sustained attention in rats. Following the successful acquisition of both modalities of the task, the rats underwent either a cholinergic immunotoxic- or sham-lesion surgery of the nucleus basalis magnocellularis (NBM), the basal forebrain nuclei that provide the majority of neocortical ACh. Reduced cholinergic afferentation to the neocortex was induced by bilaterally infusing the cholinergic immunotoxin 192 IgG-saporin into the NBM. After surgery, ACh-NBM-lesioned rats performed comparably to sham-lesioned rats under the conditions of low attentional demand, but displayed behavioral decrements relative to the sham-lesioned rats when the attentional demands of the task were increased. Moreover, this decrement in attentional functioning correlated significantly with the number of choline acetyltransferase-immunoreactive cells in the NBM. Importantly, the nature of this behavioral decrement was identical in the visual and olfactory 5-CSRTTs. Together, these data suggest the presence of a supramodal attentional modulatory cortical network whose activity is dependent on cholinergic innervation from the NBM.
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Dokter M, Busch R, Poser R, Vogt MA, von Bohlen Und Halbach V, Gass P, Unsicker K, von Bohlen Und Halbach O. Implications of p75NTR for dentate gyrus morphology and hippocampus-related behavior revisited. Brain Struct Funct 2014; 220:1449-62. [PMID: 24599786 DOI: 10.1007/s00429-014-0737-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 02/14/2014] [Indexed: 12/26/2022]
Abstract
The pan-neurotrophin receptor p75NTR is expressed in the adult brain in a discrete pattern. Although numerous studies have addressed its implications for hippocampal functions, the generated sets of data are surprisingly conflicting. We have therefore set out to re-investigate the impact of a deletion of the full-length p75NTR receptor on several parameters of the dentate gyrus (DG), including neurogenesis and hippocampus-related behavior by using p75NTR(ExIII) knockout mice. Moreover, we investigated further parameters of the DG (cholinergic innervation, dendritic spines). In addition, we analyzed on the morphological level the impact of aging by comparing adult and aged p75NTR(ExIII) mice and their age-matched littermates. Adult (4-6 months old), but not aged (20 months old), p75NTR(ExIII) knockout mice display an enhanced volume of the DG. However, adult neurogenesis within the adult DG was unaffected in both adult and aged p75NTR(ExIII) knockout mice. We could further demonstrate that the change in the volume of the DG was accompanied by an increased cholinergic innervation and increased spine densities of granule cells in adult, but not aged p75NTR deficient mice. These morphological changes in the adult p75NTR deficient mice were accompanied by specific alterations in their behavior, including altered behavior in the Morris water maze test, indicating impairments in spatial memory retention.
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Affiliation(s)
- M Dokter
- Institute of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Friedrich Loeffler Str. 23c, 17487, Greifswald, Germany
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12
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Analysis of morphological changes as a key method in studying psychiatric animal models. Cell Tissue Res 2013; 354:41-50. [PMID: 23334194 PMCID: PMC3785701 DOI: 10.1007/s00441-012-1547-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 12/05/2012] [Indexed: 12/26/2022]
Abstract
A major interest in the analysis of animal models of psychiatric diseases is their underlying cellular pathology and to gain information regarding whether pharmacological treatments, genetic differences or an altered environment exert an impact upon the brain morphology or on the morphology or activity of single neurones. In this review, several key methods will be introduced that allow the analysis of morphological changes that are frequently observed in psychiatric animal models. An overview of the techniques that enable dendritic arborisation, alterations in dendritic spines and changes in fibre densities to be analysed are described. Moreover, methods for the analysis of adult neurogenesis and neurodegeneration and for the analysis of neuronal activity in fixed brain tissue are described. An important step during the analysis of morphological changes is the estimation of the number of stained cells. Since conventional cell counting methods have several limitations, two different approaches that permit an estimate of the number of stained cells within three-dimensional tissue are also discussed.
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Green SH, Bailey E, Wang Q, Davis RL. The Trk A, B, C's of Neurotrophins in the Cochlea. Anat Rec (Hoboken) 2012; 295:1877-95. [DOI: 10.1002/ar.22587] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 12/20/2022]
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