1
|
Ali AB, Islam A, Constanti A. The fate of interneurons, GABA A receptor sub-types and perineuronal nets in Alzheimer's disease. Brain Pathol 2022; 33:e13129. [PMID: 36409151 PMCID: PMC9836378 DOI: 10.1111/bpa.13129] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 10/12/2022] [Indexed: 11/23/2022] Open
Abstract
Alzheimer's disease (AD) is the most common neurological disease, which is associated with gradual memory loss and correlated with synaptic hyperactivity and abnormal oscillatory rhythmic brain activity that precedes phenotypic alterations and is partly responsible for the spread of the disease pathology. Synaptic hyperactivity is thought to be because of alteration in the homeostasis of phasic and tonic synaptic inhibition, which is orchestrated by the GABAA inhibitory system, encompassing subclasses of interneurons and GABAA receptors, which play a vital role in cognitive functions, including learning and memory. Furthermore, the extracellular matrix, the perineuronal nets (PNNs) which often go unnoticed in considerations of AD pathology, encapsulate the inhibitory cells and neurites in critical brain regions and have recently come under the light for their crucial role in synaptic stabilisation and excitatory-inhibitory balance and when disrupted, serve as a potential trigger for AD-associated synaptic imbalance. Therefore, in this review, we summarise the current understanding of the selective vulnerability of distinct interneuron subtypes, their synaptic and extrasynaptic GABAA R subtypes as well as the changes in PNNs in AD, detailing their contribution to the mechanisms of disease development. We aim to highlight how seemingly unique malfunction in each component of the interneuronal GABA inhibitory system can be tied together to result in critical circuit dysfunction, leading to the irreversible symptomatic damage observed in AD.
Collapse
|
2
|
Hammoud H, Netsyk O, Tafreshiha AS, Korol SV, Jin Z, Li J, Birnir B. Insulin differentially modulates GABA signalling in hippocampal neurons and, in an age-dependent manner, normalizes GABA-activated currents in the tg-APPSwe mouse model of Alzheimer's disease. Acta Physiol (Oxf) 2021; 232:e13623. [PMID: 33559388 DOI: 10.1111/apha.13623] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/29/2021] [Accepted: 02/03/2021] [Indexed: 02/06/2023]
Abstract
AIM We examined if tonic γ-aminobutyric acid (GABA)-activated currents in primary hippocampal neurons were modulated by insulin in wild-type and tg-APPSwe mice, an Alzheimer's disease (AD) model. METHODS GABA-activated currents were recorded in dentate gyrus (DG) granule cells and CA3 pyramidal neurons in hippocampal brain slices, from 8 to 10 weeks old (young) wild-type mice and in dorsal DG granule cells in adult, 5-6 and 10-12 (aged) months old wild-type and tg-APPSwe mice, in the absence or presence of insulin, by whole-cell patch-clamp electrophysiology. RESULTS In young mice, insulin (1 nmol/L) enhanced the total spontaneous inhibitory postsynaptic current (sIPSCT ) density in both dorsal and ventral DG granule cells. The extrasynaptic current density was only increased by insulin in dorsal CA3 pyramidal neurons. In absence of action potentials, insulin enhanced DG granule cells and dorsal CA3 pyramidal neurons miniature IPSC (mIPSC) frequency, consistent with insulin regulation of presynaptic GABA release. sIPSCT densities in DG granule cells were similar in wild-type and tg-APPSwe mice at 5-6 months but significantly decreased in aged tg-APPSwe mice where insulin normalized currents to wild-type levels. The extrasynaptic current density was increased in tg-APPSwe mice relative to wild-type littermates but, only in aged tg-APPSwe mice did insulin decrease and normalize the current. CONCLUSION Insulin effects on GABA signalling in hippocampal neurons are selective while multifaceted and context-based. Not only is the response to insulin related to cell-type, hippocampal axis-location, age of animals and disease but also to the subtype of neuronal inhibition involved, synaptic or extrasynaptic GABAA receptors-activated currents.
Collapse
Affiliation(s)
- Hayma Hammoud
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | - Olga Netsyk
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | | | - Sergiy V. Korol
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | - Zhe Jin
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | - Jin‐Ping Li
- Department of Medical Biochemistry and Microbiology Uppsala University Uppsala Sweden
| | - Bryndis Birnir
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| |
Collapse
|
3
|
Impaired Expression of GABA Signaling Components in the Alzheimer's Disease Middle Temporal Gyrus. Int J Mol Sci 2020; 21:ijms21228704. [PMID: 33218044 PMCID: PMC7698927 DOI: 10.3390/ijms21228704] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/13/2020] [Accepted: 11/16/2020] [Indexed: 12/26/2022] Open
Abstract
γ-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter, playing a central role in the regulation of cortical excitability and the maintenance of the excitatory/inhibitory (E/I) balance. Several lines of evidence point to a remodeling of the cerebral GABAergic system in Alzheimer’s disease (AD), with past studies demonstrating alterations in GABA receptor and transporter expression, GABA synthesizing enzyme activity and focal GABA concentrations in post-mortem tissue. AD is a chronic neurodegenerative disorder with a poorly understood etiology and the temporal cortex is one of the earliest regions in the brain to be affected by AD neurodegeneration. Utilizing NanoString nCounter analysis, we demonstrate here the transcriptional downregulation of several GABA signaling components in the post-mortem human middle temporal gyrus (MTG) in AD, including the GABAA receptor α1, α2, α3, α5, β1, β2, β3, δ, γ2, γ3, and θ subunits and the GABAB receptor 2 (GABABR2) subunit. In addition to this, we note the transcriptional upregulation of the betaine-GABA transporter (BGT1) and GABA transporter 2 (GAT2), and the downregulation of the 67 kDa isoform of glutamate decarboxylase (GAD67), the primary GABA synthesizing enzyme. The functional consequences of these changes require further investigation, but such alterations may underlie disruptions to the E/I balance that are believed to contribute to cognitive decline in AD.
Collapse
|
4
|
Vico Varela E, Etter G, Williams S. Excitatory-inhibitory imbalance in Alzheimer's disease and therapeutic significance. Neurobiol Dis 2019; 127:605-615. [DOI: 10.1016/j.nbd.2019.04.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 04/08/2019] [Accepted: 04/12/2019] [Indexed: 11/29/2022] Open
|
5
|
Kwakowsky A, Calvo-Flores Guzmán B, Pandya M, Turner C, Waldvogel HJ, Faull RL. GABA A receptor subunit expression changes in the human Alzheimer's disease hippocampus, subiculum, entorhinal cortex and superior temporal gyrus. J Neurochem 2019; 145:374-392. [PMID: 29485232 DOI: 10.1111/jnc.14325] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 01/17/2018] [Accepted: 02/12/2018] [Indexed: 12/14/2022]
Abstract
Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. GABA type A receptors (GABAA Rs) are severely affected in Alzheimer's disease (AD). However, the distribution and subunit composition of GABAA Rs in the AD brain are not well understood. This is the first comprehensive study to show brain region- and cell layer-specific alterations in the expression of the GABAA R subunits α1-3, α5, β1-3 and γ2 in the human AD hippocampus, entorhinal cortex and superior temporal gyrus. In late-stage AD tissue samples using immunohistochemistry we found significant alteration of all investigated GABAA Rs subunits except for α3 and β1 that were well preserved. The most prominent changes include an increase in GABAA R α1 expression associated with AD in all layers of the CA3 region, in the stratum (str.) granulare and hilus of the dentate gyrus. We found a significant increase in GABAA R α2 expression in the str. oriens of the CA1-3, str. radiatum of the CA2,3 and decrease in the str. pyramidale of the CA1 region in AD cases. In AD there was a significant increase in GABAA R α5 subunit expression in str. pyramidale, str. oriens of the CA1 region and decrease in the superior temporal gyrus. We also found a significant decrease in the GABAA R β3 subunit immunoreactivity in the str. oriens of the CA2, str. granulare and str. moleculare of the dentate gyrus. In conclusion, these findings indicate that the expression of the GABAA R subunits shows brain region- and layer-specific alterations in AD, and these changes could significantly influence and alter GABAA R function in the disease. Cover Image for this issue: doi: 10.1111/jnc.14179.
Collapse
Affiliation(s)
- Andrea Kwakowsky
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Beatriz Calvo-Flores Guzmán
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Madhavi Pandya
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Clinton Turner
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.,Department of Anatomical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Henry J Waldvogel
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Richard L Faull
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| |
Collapse
|
6
|
Unsupervised excitation: GABAergic dysfunctions in Alzheimer’s disease. Brain Res 2019; 1707:216-226. [DOI: 10.1016/j.brainres.2018.11.042] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 10/31/2018] [Accepted: 11/27/2018] [Indexed: 12/22/2022]
|
7
|
Stefanits H, Milenkovic I, Mahr N, Pataraia E, Hainfellner JA, Kovacs GG, Sieghart W, Yilmazer-Hanke D, Czech T. GABAAreceptor subunits in the human amygdala and hippocampus: Immunohistochemical distribution of 7 subunits. J Comp Neurol 2017; 526:324-348. [DOI: 10.1002/cne.24337] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 09/12/2017] [Accepted: 09/19/2017] [Indexed: 12/18/2022]
Affiliation(s)
- Harald Stefanits
- Department of Neurosurgery; Medical University of Vienna; Vienna Austria
- Institute of Neurology, Medical University of Vienna; Vienna Austria
| | - Ivan Milenkovic
- Department of Clinical Neurology; Medical University of Vienna; Vienna Austria
| | - Nina Mahr
- Department of Neurosurgery; Medical University of Vienna; Vienna Austria
| | - Ekaterina Pataraia
- Department of Clinical Neurology; Medical University of Vienna; Vienna Austria
| | | | - Gabor G. Kovacs
- Institute of Neurology, Medical University of Vienna; Vienna Austria
| | - Werner Sieghart
- Center for Brain Research, Department of Molecular Neurosciences; Medical University of Vienna; Vienna Austria
| | - Deniz Yilmazer-Hanke
- Clinical Neuroanatomy, Neurology Department, Medical Faculty; Ulm University; Ulm Germany
| | - Thomas Czech
- Department of Neurosurgery; Medical University of Vienna; Vienna Austria
| |
Collapse
|
8
|
Towards a Better Understanding of GABAergic Remodeling in Alzheimer's Disease. Int J Mol Sci 2017; 18:ijms18081813. [PMID: 28825683 PMCID: PMC5578199 DOI: 10.3390/ijms18081813] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/16/2017] [Accepted: 08/17/2017] [Indexed: 12/18/2022] Open
Abstract
γ-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the vertebrate brain. In the past, there has been a major research drive focused on the dysfunction of the glutamatergic and cholinergic neurotransmitter systems in Alzheimer’s disease (AD). However, there is now growing evidence in support of a GABAergic contribution to the pathogenesis of this neurodegenerative disease. Previous studies paint a complex, convoluted and often inconsistent picture of AD-associated GABAergic remodeling. Given the importance of the GABAergic system in neuronal function and homeostasis, in the maintenance of the excitatory/inhibitory balance, and in the processes of learning and memory, such changes in GABAergic function could be an important factor in both early and later stages of AD pathogenesis. Given the limited scope of currently available therapies in modifying the course of the disease, a better understanding of GABAergic remodeling in AD could open up innovative and novel therapeutic opportunities.
Collapse
|
9
|
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease, characterized by the loss of memory, multiple cognitive impairments and changes in the personality and behavior. Several decades of intense research have revealed that multiple cellular changes are involved in disease process, including synaptic damage, mitochondrial abnormalities and inflammatory responses, in addition to formation and accumulation of amyloid-β (Aβ) and phosphorylated tau. Although tremendous progress has been made in understanding the impact of neurotransmitters in the progression and pathogenesis of AD, we still do not have a drug molecule associated with neurotransmitter(s) that can delay disease process in elderly individuals and/or restore cognitive functions in AD patients. The purpose of our article is to assess the latest developments in neurotransmitters research using cell and mouse models of AD. We also updated the current status of clinical trials using neurotransmitters' agonists/antagonists in AD.
Collapse
Affiliation(s)
- Ramesh Kandimalla
- Garrison Institute on Aging Department, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Pharmacology & Neuroscience Department, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - P. Hemachandra Reddy
- Garrison Institute on Aging Department, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Pharmacology & Neuroscience Department, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Cell Biology & Biochemistry Department, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Neurology Department, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Garrison Institute on Aging, South West Campus, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| |
Collapse
|
10
|
Defrancesco M, Marksteiner J, Fleischhacker WW, Blasko I. Use of Benzodiazepines in Alzheimer's Disease: A Systematic Review of Literature. Int J Neuropsychopharmacol 2015; 18:pyv055. [PMID: 25991652 PMCID: PMC4648159 DOI: 10.1093/ijnp/pyv055] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/12/2015] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Benzodiazepines are frequently prescribed in patients with Alzheimer's disease. Unfortunately, studies evaluating their benefits and risks in these patients are limited. METHODS Clinical trials focusing on the effect of benzodiazepines on cognitive functions, disease progression, behavioral symptoms, sleep disturbances, and the general frequency of benzodiazepine use were included in this review. Published articles from January 1983 to January 2015 were identified using specific search terms in MEDLINE and PubMed Library according to the recommendations of The Strengthening the Reporting of Observational Studies in Epidemiology initiative. RESULTS Of the 657 articles found, 18 articles met predefined selection criteria and were included in this review (8 on frequency, 5 on cognitive functions, 5 on behavioral and sleep disturbances). The frequency of benzodiazepine use ranged from 8.5% to 20%. Five studies reported accelerated cognitive deterioration in association with benzodiazepine use. Two studies reported clinical efficacy for lorazepam and alprazolam to reduce agitation in Alzheimer's disease patients. No evidence was found for an improvement of sleep quality using benzodiazepines. CONCLUSION This systematic review shows a relatively high prevalence of benzodiazepine use but limited evidence for clinical efficacy in Alzheimer's disease patients. However, there is a paucity of methodologically high quality controlled clinical trials. Our results underscore a need for randomized controlled trials in this area.
Collapse
Affiliation(s)
- Michaela Defrancesco
- Memory Clinic (Dr Defrancesco), and Division of General and Social Psychiatry (Drs Fleischhacker and Blasko), Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Psychotherapy A, Landeskrankenhaus Hall, Hall, Austria (Dr Marksteiner); Division of Biological Psychiatry, Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Innsbruck, Austria (Dr Fleischhacker)
| | - Josef Marksteiner
- Memory Clinic (Dr Defrancesco), and Division of General and Social Psychiatry (Drs Fleischhacker and Blasko), Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Psychotherapy A, Landeskrankenhaus Hall, Hall, Austria (Dr Marksteiner); Division of Biological Psychiatry, Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Innsbruck, Austria (Dr Fleischhacker)
| | - W Wolfgang Fleischhacker
- Memory Clinic (Dr Defrancesco), and Division of General and Social Psychiatry (Drs Fleischhacker and Blasko), Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Psychotherapy A, Landeskrankenhaus Hall, Hall, Austria (Dr Marksteiner); Division of Biological Psychiatry, Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Innsbruck, Austria (Dr Fleischhacker)
| | - Imrich Blasko
- Memory Clinic (Dr Defrancesco), and Division of General and Social Psychiatry (Drs Fleischhacker and Blasko), Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Psychotherapy A, Landeskrankenhaus Hall, Hall, Austria (Dr Marksteiner); Division of Biological Psychiatry, Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Innsbruck, Austria (Dr Fleischhacker)
| |
Collapse
|
11
|
Nava-Mesa MO, Jiménez-Díaz L, Yajeya J, Navarro-Lopez JD. GABAergic neurotransmission and new strategies of neuromodulation to compensate synaptic dysfunction in early stages of Alzheimer's disease. Front Cell Neurosci 2014; 8:167. [PMID: 24987334 PMCID: PMC4070063 DOI: 10.3389/fncel.2014.00167] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 06/02/2014] [Indexed: 01/06/2023] Open
Abstract
Alzheimer’s disease (AD) is a progressive neurodegenerative disease characterized by cognitive decline, brain atrophy due to neuronal and synapse loss, and formation of two pathological lesions: extracellular amyloid plaques, composed largely of amyloid-beta peptide (Aβ), and neurofibrillary tangles formed by intracellular aggregates of hyperphosphorylated tau protein. Lesions mainly accumulate in brain regions that modulate cognitive functions such as the hippocampus, septum or amygdala. These brain structures have dense reciprocal glutamatergic, cholinergic, and GABAergic connections and their relationships directly affect learning and memory processes, so they have been proposed as highly susceptible regions to suffer damage by Aβ during AD course. Last findings support the emerging concept that soluble Aβ peptides, inducing an initial stage of synaptic dysfunction which probably starts 20–30 years before the clinical onset of AD, can perturb the excitatory–inhibitory balance of neural circuitries. In turn, neurotransmission imbalance will result in altered network activity that might be responsible of cognitive deficits in AD. Therefore, Aβ interactions on neurotransmission systems in memory-related brain regions such as amygdaloid complex, medial septum or hippocampus are critical in cognitive functions and appear as a pivotal target for drug design to improve learning and dysfunctions that manifest with age. Since treatments based on glutamatergic and cholinergic pharmacology in AD have shown limited success, therapies combining modulators of different neurotransmission systems including recent findings regarding the GABAergic system, emerge as a more useful tool for the treatment, and overall prevention, of this dementia. In this review, focused on inhibitory systems, we will analyze pharmacological strategies to compensate neurotransmission imbalance that might be considered as potential therapeutic interventions in AD.
Collapse
Affiliation(s)
| | - Lydia Jiménez-Díaz
- Neurophysiology and Behavior Lab, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha Ciudad Real, Spain
| | - Javier Yajeya
- Department of Physiology and Pharmacology, University of Salamanca Salamanca, Spain
| | - Juan D Navarro-Lopez
- Neurophysiology and Behavior Lab, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha Ciudad Real, Spain
| |
Collapse
|
12
|
Dihydromyricetin Ameliorates Behavioral Deficits and Reverses Neuropathology of Transgenic Mouse Models of Alzheimer’s Disease. Neurochem Res 2014; 39:1171-81. [DOI: 10.1007/s11064-014-1304-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 04/01/2014] [Accepted: 04/03/2014] [Indexed: 11/27/2022]
|
13
|
Mizukami K, Abrahamson EE, Mi Z, Ishikawa M, Watanabe K, Kinoshita S, Asada T, Ikonomovic MD. Immunohistochemical analysis of ubiquilin-1 in the human hippocampus: association with neurofibrillary tangle pathology. Neuropathology 2013; 34:11-8. [PMID: 23869942 DOI: 10.1111/neup.12055] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 06/23/2013] [Accepted: 06/24/2013] [Indexed: 12/28/2022]
Abstract
This post mortem immunohistochemical study examined the localization and distribution of ubiquilin-1 (UBL), a shuttle protein which interacts with ubiquitin and the proteasome, in the hippocampus from Alzheimer's disease (AD) dementia cases, and age-matched cases without dementia. In Braak stages 0-I-II cases, UBL immunoreactivity was detected in a dense fiber network in the neuropil, and in the cell cytoplasm and nucleoplasm of neurons in Cornu Ammonis (CA) fields and dentate gyrus granular neurons. In Braak stages III-IV and V-VI cases, UBL immunoreactivity was reduced in the neuropil and in the cytoplasm of the majority of CA1 neurons; some CA1 pyramidal neurons and the majority of CA2/3 pyramidal, CA4 multipolar, and dentate granular neurons had markedly increased UBL immunoreactivity in the nucleoplasm. Dual immunofluorescence analysis of UBL and antibody clone AT8 revealed co-localization most frequently in CA1 pyramidal neurons in Braak stage III-IV and V-VI cases. Further processing using the pan-amyloid marker X-34 revealed prominent UBL/X-34 dual labeling of extracellular NFT confined to the CA1/subiculum in Braak stage V-VI cases. Our results demonstrate that in AD hippocampus, early NFT changes are associated with neuronal up-regulation of UBL in nucleoplasm, or its translocation from the cytoplasm to the nucleus. The perseverance of UBL changes in CA2/3, CA4 and dentate gyrus, generally considered as more resistant to NFT pathology, but not in the CA1, may mark a compensatory, potentially protective response to increased tau phosphorylation in hippocampal neurons; the failure of such a response may contribute to neuronal degeneration in end-stage AD.
Collapse
Affiliation(s)
- Katsuyoshi Mizukami
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tokyo, Japan
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Lemoine D, Jiang R, Taly A, Chataigneau T, Specht A, Grutter T. Ligand-gated ion channels: new insights into neurological disorders and ligand recognition. Chem Rev 2012; 112:6285-318. [PMID: 22988962 DOI: 10.1021/cr3000829] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Damien Lemoine
- Laboratoire de Biophysicochimie des Récepteurs Canaux, UMR 7199 CNRS, Conception et Application de Molécules Bioactives, Faculté de Pharmacie, Université de Strasbourg , 67400 Illkirch, France
| | | | | | | | | | | |
Collapse
|
15
|
Tan S, Rudd JA, Yew DT. Gene expression changes in GABA(A) receptors and cognition following chronic ketamine administration in mice. PLoS One 2011; 6:e21328. [PMID: 21712993 PMCID: PMC3119682 DOI: 10.1371/journal.pone.0021328] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 05/26/2011] [Indexed: 01/09/2023] Open
Abstract
Ketamine is a well-known anesthetic agent and a drug of abuse. Despite its widespread use and abuse, little is known about its long-term effects on the central nervous system. The present study was designed to evaluate the effect of long-term (1- and 3-month) ketamine administration on learning and memory and associated gene expression levels in the brain. The Morris water maze was used to assess spatial memory and gene expression changes were assayed using Affymetrix Genechips; a focus on the expression of GABA(A) receptors that mediate a tonic inhibition in the brain, was confirmed by quantitative real-time PCR and western blot. Compared with saline controls, there was a decline in learning and memory performance in the ketamine-treated mice. Genechip results showed that 110 genes were up-regulated and 136 genes were down-regulated. An ontology analysis revealed the most significant effects of ketamine were on GABA(A) receptors. In particular, there was a significant up-regulation of both mRNA and protein levels of the alpha 5 subunit (Gabra5) of the GABA(A) receptors in the prefrontal cortex. In conclusion, chronic exposure to ketamine impairs working memory in mice, which may be explained at least partly by up-regulation of Gabra5 subunits in the prefrontal cortex.
Collapse
Affiliation(s)
- Sijie Tan
- Brain Research Center, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong S.A.R., China
| | - John A. Rudd
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong S.A.R., China
| | - David T. Yew
- Brain Research Center, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong S.A.R., China
- * E-mail:
| |
Collapse
|
16
|
Rissman RA, Mobley WC. Implications for treatment: GABAA receptors in aging, Down syndrome and Alzheimer's disease. J Neurochem 2011; 117:613-22. [PMID: 21388375 DOI: 10.1111/j.1471-4159.2011.07237.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In addition to progressive dementia, Alzheimer's disease (AD) is characterized by increased incidence of seizure activity. Although originally discounted as a secondary process occurring as a result of neurodegeneration, more recent data suggest that alterations in excitatory-inhibitory (E/I) balance occur in AD and may be a primary mechanism contributing AD cognitive decline. In this study, we discuss relevant research and reports on the GABA(A) receptor in developmental disorders, such as Down syndrome, in healthy aging, and highlight documented aberrations in the GABAergic system in AD. Stressing the importance of understanding the subunit composition of individual GABA(A) receptors, investigations demonstrate alterations of particular GABA(A) receptor subunits in AD, but overall sparing of the GABAergic system. In this study, we review experimental data on the GABAergic system in the pathobiology of AD and discuss relevant therapeutic implications. When developing AD therapeutics that modulate GABA it is important to consider how E/I balance impacts AD pathogenesis and the relationship between seizure activity and cognitive decline.
Collapse
Affiliation(s)
- Robert A Rissman
- Department of Neurosciences, University of California, San Diego, La Jolla, California 92093-0624, USA.
| | | |
Collapse
|
17
|
Mizukami K, Ishikawa M, Akatsu H, Abrahamson EE, Ikonomovic MD, Asada T. An immunohistochemical study of the serotonin 1A receptor in the hippocampus of subjects with Alzheimer's disease. Neuropathology 2011; 31:503-9. [PMID: 21269332 DOI: 10.1111/j.1440-1789.2010.01193.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Alzheimer's disease (AD) is associated with neuronal degeneration, synaptic loss and deficits in multiple neurotransmitter systems. Alterations in the serotonin 1A (5-HT1A) receptor can contribute to impaired cognitive function in AD, and both in vitro binding and Positron emission tomography (PET) imaging studies have demonstrated that 5-HT1A receptors in the hippocampus/medial temporal cortex are affected early in AD. This neuropathological study examined the localization and immunoreaction intensity of 5-HT1A receptor protein in AD hippocampus with the goal to determine whether neuronal receptor levels are influenced by the severity of NFT severity defined by Braaks' pathological staging and to provide immunohistochemical confirmation of the binding assays and PET imaging studies. Subjects included AD patients and non-AD controls (NC) stratified into three Braaks' stages (Braak 0-II, NC; Braak III/IV and V/VI, AD). In the Braak 0-II group, 5-HT1A-immunoreactivity (ir) was prominent in the neuropil of the CA1 and subiculum, moderate in the dentate gyrus molecular layer (DGml), and low in the CA3 and CA4. No changes in 5-HT1A-ir were observed in the hippocampus of AD subjects in the Braak III/IV group. Hippocampal 5-HT1A-ir intensity was markedly decreased in the CA1 region in 6/11 (54.5%) subjects in the Braak V/VI group. Across all three groups combined, there was a statistically significant association between reduced 5HT1A-ir and neuronal loss in the CA1, but not in the CA3. The present data demonstrate that hippocampal 5-HT1A receptors are mainly preserved until the end-stage of NFT progression in AD. Thus, the utility of PET imaging using a 5-HT1A-specific radiolabeled probe as a marker of hippocampal neuronal loss may be limited to the CA1 field in advanced stage AD cases.
Collapse
Affiliation(s)
- Katsuyoshi Mizukami
- Department of Psychiatry, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
| | | | | | | | | | | |
Collapse
|
18
|
Iwakiri M, Mizukami K, Ikonomovic MD, Ishikawa M, Abrahamson EE, DeKosky ST, Asada T. An immunohistochemical study of GABA A receptor gamma subunits in Alzheimer's disease hippocampus: relationship to neurofibrillary tangle progression. Neuropathology 2008; 29:263-9. [PMID: 19019179 DOI: 10.1111/j.1440-1789.2008.00978.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Immunohistochemical characterization of the distribution of GABA(A) receptor subunits gamma1/3 and 2 in the hippocampus relative to neurofibrillary tangle (NFT) pathology staging was performed in cognitively normal subjects (Braak stage I/II, n = 4) and two groups of Alzheimer's disease (AD) patients (Braak stage III/IV, n = 4; Braak stage V/VI, n = 8). In both Braak groups of AD patients, neuronal gamma1/3 and gamma2 immunoreactivity was preserved in all hippocampal subfields. However, compared to normal controls neuronal gamma1/3 immunoreactivity was more intense in several end-stage AD subjects. Despite increased NFT pathology in the Braak V/VI AD group, GABA(A)gamma1/3 and gamma2 immunoreactivity did not co-localize with markers of NFT. These results suggest that upregulating or preserving GABA(A)gamma1/3 and gamma2 receptors may protect neurons against neurofibrillary pathology in AD.
Collapse
Affiliation(s)
- Masahiko Iwakiri
- Department of Psychiatry, Ishizaki Hosipital, Ibaraki-machi, Japan
| | | | | | | | | | | | | |
Collapse
|
19
|
Abstract
In this article we present a comprehensive review of relevant research and reports on the GABA(A) receptor in the aged and Alzheimer's disease (AD) brain. In comparison to glutamatergic and cholinergic systems, the GABAergic system is relatively spared in AD, but the precise mechanisms underlying differential vulnerability are not well understood. Using several methods, investigations demonstrate that despite resistance of the GABAergic system to neurodegeneration, particular subunits of the GABA(A) receptor are altered with age and AD, which can induce compensatory increases in GABA(A) receptor subunits within surrounding cells. We conclude that although aging- and disease-related changes in GABA(A) receptor subunits may be modest, the mechanisms that compensate for these changes may alter the pharmacokinetic and physiological properties of the receptor. It is therefore crucial to understand the subunit composition of individual GABA(A) receptors in the diseased brain when developing therapeutics that act at these receptors.
Collapse
Affiliation(s)
- Robert A Rissman
- Laboratory of Neuronal Structure and Function, The Salk Institute for Biological Studies, La Jolla, California, USA.
| | | | | |
Collapse
|
20
|
Ryzhikov S, Bahr BA. Gephyrin alterations due to protein accumulation stress are reduced by the lysosomal modulator Z-Phe-Ala-diazomethylketone. J Mol Neurosci 2007; 34:131-9. [PMID: 18204977 DOI: 10.1007/s12031-007-9009-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2007] [Accepted: 08/22/2007] [Indexed: 11/25/2022]
Abstract
Inhibitory neurotransmission is important for brain function and requires specific transmitter receptors that are organized in synaptic domains. Gephyrin is a cytoskeletal organization protein that binds tubulin and plays an important role in clustering and organizing select inhibitory neurotransmitter receptors. Here, we tested if gephyrin is altered by protein accumulation stress that is common in age-related neurodegenerative disorders. For this, we used the hippocampal slice model that has been shown to exhibit chloroquine (CQN)-induced protein accumulation, microtubule destabilization, transport failure, and declines in excitatory neurotransmitter receptors and their responses. In addition to the decreases in excitatory receptor subunits and other glutamatergic markers, we found that gephyrin isoforms were reduced across the CQN treatment period. Associated with this decline in gephyrin levels was the production of three gephyrin breakdown products (GBDPs) of 30, 38, and 48 kDa. The induced effects on gephyrin were tested for evidence of recovery through enhancement of lysosomal function that is known to promote protein clearance and microtubule integrity. Using the lysosomal modulator Z-Phe-Ala-diazomethylketone (PADK), gephyrin levels were completely restored in correspondence with the recovery of excitatory glutamatergic components. In addition, GBDPs were significantly reduced after the 2-day PADK treatment, to levels that were at or below those measured in control cultures. These findings suggest that receptor-clustering mechanisms for inhibitory synapses are compromised during protein accumulation events. They also indicate that a lysosomal enhancement strategy can protect gephyrin integrity, which may be vital for the balance between inhibitory and excitatory signaling during age-related diseases.
Collapse
Affiliation(s)
- Sophia Ryzhikov
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, USA
| | | |
Collapse
|
21
|
Abstract
As part of the hippocampus, the dentate gyrus is considered to play a crucial role in associative memory. The reviewed data suggest that the dentate gyrus withstands the formation of plaques, tangles and neuronal death until late stages of Alzheimer's disease (AD). However, changes related to a disconnecting process, and more subtle intrinsic alterations, may contribute to disturbances in memory and learning observed in early stages of AD.
Collapse
Affiliation(s)
- Thomas G Ohm
- Institute of Integrative Neuroanatomy, Department of Clinical Cell and Neurobiology, Charité CCM, 10098 Berlin, Germany.
| |
Collapse
|
22
|
Rissman RA, Nocera R, Fuller LM, Kordower JH, Armstrong DM. Age-related alterations in GABAA receptor subunits in the nonhuman primate hippocampus. Brain Res 2006; 1073-1074:120-30. [PMID: 16430870 DOI: 10.1016/j.brainres.2005.12.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Revised: 11/23/2005] [Accepted: 12/05/2005] [Indexed: 10/25/2022]
Abstract
Pharmacological studies have documented that altered drug responses, particularly to benzodiazepines, are common in elderly populations. While numerous factors may contribute to changes in drug response, age-related alterations in the molecular composition of GABA(A) receptors may be a key factor in regulating these responses. We employed quantitative densitometry to examine the cytological features and density of highly prevalent hippocampal GABA(A) receptor subunits (alpha1 and beta2/3) in young and aged rhesus monkeys. alpha1 and beta2/3 subunit immunostaining was differentially distributed throughout the hippocampus. In addition, beta2/3 immunolabeling in aged monkeys was characterized by marked intersubject variability in labeling intensity, with dramatic reductions present in 3 of 5 samples. alpha1 immunolabeling in aged monkeys was significantly reduced in the CA2 and CA3 subregions, and in hilus/polymorphic layer of the dentate gyrus. Collectively, our findings demonstrate that not only are GABA(A) receptor subunits differentially distributed throughout the hippocampus, but they are also differentially altered with increased age--changes that may have an important impact on the binding properties of GABA(A) receptor pharmacological agents.
Collapse
Affiliation(s)
- Robert A Rissman
- Department of Neurobiology and Anatomy, Graduate Program in Neuroscience, MCP Hahnemann University School of Medicine, Philadelphia, PA 19102-1192, USA.
| | | | | | | | | |
Collapse
|
23
|
Iwakiri M, Mizukami K, Ikonomovic MD, Ishikawa M, Hidaka S, Abrahamson EE, DeKosky ST, Asada T. Changes in hippocampal GABABR1 subunit expression in Alzheimer's patients: association with Braak staging. Acta Neuropathol 2005; 109:467-74. [PMID: 15759131 DOI: 10.1007/s00401-005-0985-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Revised: 12/30/2004] [Accepted: 01/03/2005] [Indexed: 11/27/2022]
Abstract
Alterations in the gamma-aminobutyric acid (GABA) neurotransmitter and receptor systems may contribute to vulnerability of hippocampal pyramidal neurons in Alzheimer's disease (AD). The present study examined the immunohistochemical localization and distribution of GABA(B) receptor R1 protein (GBR1) in the hippocampus of 16 aged subjects with a range of neurofibrillary tangle (NFT) pathology as defined by Braak staging (I-VI). GBR1 immunoreactivity (IR) was localized to the soma and processes of hippocampal pyramidal cells and some non-pyramidal interneurons. In control subjects (Braak I/II), the intensity of neuronal GBR1 immunostaining differed among hippocampal fields, being most prominent in the CA4 and CA3/2 fields, moderate in the CA1 field, and very light in the dentate gyrus. AD cases with moderate NFT pathology (Braak III/IV) were characterized by increased GBR1-IR, particularly in the CA4 and CA3/2 fields. In the CA1 field of the majority of AD cases, the numbers of GBR1-IR neurons were significantly reduced, despite the presence of Nissl-labeled neurons in this region. These data indicate that GBR1 expression changes with the progression of NFT in AD hippocampus. At the onset of hippocampal pathology, increased or stable expression of GBR1 could contribute to neuronal resistance to the disease process. Advanced hippocampal pathology appears to be associated with decreased neuronal GBR1 staining in the CA1 region, which precedes neuronal cell death. Thus, changes in hippocampal GBR1 may reflect alterations in the balance between excitatory and inhibitory neurotransmitter systems, which likely contributes to dysfunction of hippocampal circuitry in AD.
Collapse
Affiliation(s)
- Masahiko Iwakiri
- Department of Psychiatry, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennodai, 305-8575, Tsukuba city, Ibaraki, Japan
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Ishikawa M, Mizukami K, Iwakiri M, Kamma H, Ikonomovic MD, Dekosky ST, Asada T. Immunohistochemical study of hnRNP B1 in the postmortem temporal cortices of patients with Alzheimer's disease. Neurosci Res 2004; 50:481-4. [PMID: 15567486 DOI: 10.1016/j.neures.2004.08.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2004] [Accepted: 08/27/2004] [Indexed: 10/26/2022]
Abstract
In order to examine the post-transcriptional regulations in Alzheimer's disease, we employed immunohistochemical techniques and examined the expression of heterogeneous nuclear ribonucleoprotein (hnRNP) B1 in the inferior temporal cortex of subjects with Alzheimer's disease. In the mild cases, intense B1 immunoreactivity was observed in neurons of layer V, and less intense immunoreactivity was observed in layers II and III. The overall distributions and intensities of B1 immunoreactivity were undistinguishable among mild, moderate, and severe cases. Double-immunolabeling with MC1 and B1 demonstrated that B1 immunoreactivity was preserved in the majority of neurofibrillary tangle (NFT)-bearing neurons. Our study suggests that hnRNP B1-associated post-transcriptional regulations are preserved in the inferior temporal cortex of Alzheimer's disease.
Collapse
Affiliation(s)
- Masanori Ishikawa
- Department of Psychiatry, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba city, Ibaraki 305-8575, Japan
| | | | | | | | | | | | | |
Collapse
|
25
|
Ishikawa M, Mizukami K, Iwakiri M, Hidaka S, Asada T. Immunohistochemical and immunoblot study of GABA(A) alpha1 and beta2/3 subunits in the prefrontal cortex of subjects with schizophrenia and bipolar disorder. Neurosci Res 2004; 50:77-84. [PMID: 15288501 DOI: 10.1016/j.neures.2004.06.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2004] [Accepted: 06/09/2004] [Indexed: 10/26/2022]
Abstract
A number of investigations have provided a growing body of evidence of the involvement of the gamma-aminobutyric acid (GABA) transmitter system in the pathophysiology of schizophrenia and bipolar disorder. In this study, immunohistochemical and immunoblot techniques were employed in order to examine alterations of the GABA(A) receptor alpha1 and beta2/3 subunits in the prefrontal cortex from postmortem subjects with schizophrenia and bipolar disorder. alpha1 immunoreactivity was observed in the neuropil of the prefrontal cortex and in the neuronal soma in specimens from both groups, as well as from normal controls. alpha1 immunolabeling in the neuronal soma from the schizophrenic group was more intense than that of the other two groups. The distribution of beta2/3 immunoreactivity was similar to that of alpha1. beta2/3 immunolabeling in the neuronal soma from the schizophrenia and bipolar disorder groups was more intense than that of the normal controls. The densitometry measurements, as well as the immunoblot analysis for alpha1 and beta2/3 were highly consistent with the alpha1 and beta2/3 immunohistochemistry results. The present study suggests that the expression of these two GABA(A) receptor subunits was altered in subjects with schizophrenia and bipolar disorder, but that the patterns of change differed between those with these two disorders.
Collapse
Affiliation(s)
- Masanori Ishikawa
- Department of Psychiatry, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba City, Ibaraki 305-8575, Japan
| | | | | | | | | |
Collapse
|
26
|
Steiger JL, Russek SJ. GABAA receptors: building the bridge between subunit mRNAs, their promoters, and cognate transcription factors. Pharmacol Ther 2004; 101:259-81. [PMID: 15031002 DOI: 10.1016/j.pharmthera.2003.12.002] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The type A gamma-aminobutyric acid (GABA(A)) receptors mediate the majority of fast inhibitory neurotransmission in the CNS, and alterations in GABA(A) receptor function is believed to be involved in the pathology of several neurological and psychiatric illnesses, such as epilepsy, anxiety, Alzheimer's disease, and schizophrenia. GABA(A) receptors can be assembled from eight distinct subunit families defined by sequence similarity: alpha(1-6), beta(1-3), gamma(1-3), delta, pi, theta, and rho(1-3). The regulation of GABA(A) receptor function in the brain is a highly compensating system, influencing both the number and the composition of receptors at the cell surface. While transcriptional and translational points of control operate in parallel, it is becoming increasingly evident that many functional changes in GABA(A) receptors reflect the differential gene regulation of its subunits. The fact that certain GABA(A) receptor subunit genes are transcribed in distinct cell types during specific periods of development strongly suggests that genetic control plays a major role in the choice of subunit variants available for receptor assembly. This review focuses on the physiological conditions that alter subunit mRNA levels, the promoters that may control such levels, and the use of a conceptual framework created by bioinformatics to study coordinate and independent GABA(A) receptor subunit gene regulation. As this exciting field moves closer to identifying the language hidden inside the chromatin of GABA(A) receptor subunit gene clusters, future experiments will be aimed at testing models generated by computational analysis with biologically relevant in vivo and in vitro assays. It is hoped that through this functional genomic approach there will be the identification of new targets for therapeutic intervention.
Collapse
Affiliation(s)
- Janine L Steiger
- Laboratory of Molecular Neurobiology, Department of Pharmacology, Boston University School of Medicine, Boston, MA 02118, USA
| | | |
Collapse
|
27
|
Armstrong DM, Sheffield R, Mishizen-Eberz AJ, Carter TL, Rissman RA, Mizukami K, Ikonomovic MD. Plasticity of glutamate and GABAA receptors in the hippocampus of patients with Alzheimer's disease. Cell Mol Neurobiol 2004; 23:491-505. [PMID: 14514010 DOI: 10.1023/a:1025063811290] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AIM In Alzheimer's disease (AD) it is well known that specific regions of the brain are particularly vulnerable to the pathologic insults of the disease. In particular, the hippocampus is affected very early in the disease and by end stage AD is ravaged by neurofibrillary tangles and senile plaques (i.e., the pathologic hallmarks of AD). Throughout the past several years our laboratory has sought to determine the molecular mechanisms underlying the selective vulnerability of neurons in AD. METHODS To this end, we employed immunohistochemical, biochemical, and in situ hybrization methods to examine glutamate and gamma-aminobutyric acid (GABAA) receptor subtypes in the hippocampus of patients displaying the full spectrum of AD pathology. RESULTS Despite the fact that the hippocampus is characterized by a marked loss of neurons in the late stages of the disease, our data demonstrate a rather remarkable preservation among some glutamate and GABAA receptor subtypes. CONCLUSIONS Collectively, our data support the view that the relatively constant levels of selected receptor subtypes represent a compensatory up-regulation of these receptors subunits in surviving neurons. The demonstration that glutamate and GABA receptor subunits are comparably unaffected implies that even in the terminal stages of the discase the brain is "attempting" to maintain a balance in excitatory and inhibitory tone. Our data also support the concept that receptor subunits are differentially affected in AD with some subunits displaying no change while others display alterations in protein and mRNA levels within selected regions of the hippocampus. Although many of these changes are modest, they do suggest that the subunit composition of these receptors may be altered and hence affect the pharmacokinetic and physiological properties of the receptor. The latter findings stress the importance of understanding the subunit composition of individual glutamate/GABA receptors in the diseased brain prior to the development of drugs targeted towards those receptors.
Collapse
Affiliation(s)
- David M Armstrong
- Laboratory of Neuronal Vulnerability and Aging, The Lankenau Institute for Medical Research, Jefferson Health System, Wynnewood, Pennsylvania, USA.
| | | | | | | | | | | | | |
Collapse
|
28
|
Miledi R, Dueñas Z, Martinez-Torres A, Kawas CH, Eusebi F. Microtransplantation of functional receptors and channels from the Alzheimer's brain to frog oocytes. Proc Natl Acad Sci U S A 2004; 101:1760-3. [PMID: 14749517 PMCID: PMC341849 DOI: 10.1073/pnas.0308224100] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
About a decade ago, cell membranes from the electric organ of Torpedo and from the rat brain were transplanted to frog oocytes, which thus acquired functional Torpedo and rat neurotransmitter receptors. Nevertheless, the great potential that this method has for studying human diseases has remained virtually untapped. Here, we show that cell membranes from the postmortem brains of humans that suffered Alzheimer's disease can be microtransplanted to the plasma membrane of Xenopus oocytes. We show also that these postmortem membranes carry neurotransmitter receptors and voltage-operated channels that are still functional, even after they have been kept frozen for many years. This method provides a new and powerful approach to study directly the functional characteristics and structure of receptors, channels, and other membrane proteins of the Alzheimer's brain. This knowledge may help in understanding the basis of Alzheimer's disease and also help in developing new treatments.
Collapse
Affiliation(s)
- R Miledi
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-4550, USA.
| | | | | | | | | |
Collapse
|
29
|
Rissman RA, Mishizen-Eberz AJ, Carter TL, Wolfe BB, De Blas AL, Miralles CP, Ikonomovic MD, Armstrong DM. Biochemical analysis of GABA(A) receptor subunits alpha 1, alpha 5, beta 1, beta 2 in the hippocampus of patients with Alzheimer's disease neuropathology. Neuroscience 2003; 120:695-704. [PMID: 12895510 DOI: 10.1016/s0306-4522(03)00030-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Alzheimer's disease (AD) is characterized by selective vulnerability of specific neuronal populations within particular brain regions. For example, hippocampal glutamatergic cell populations within the CA1/subicular pyramidal cell fields have been found to be particularly vulnerable early in AD progression. In contrast, hippocampal GABA-ergic neurons and receptors appear resistant to neurodegeneration. Despite relative sparing of GABA(A) receptors in AD, it is possible that the specific subunit composition of these receptors may undergo alterations with disease progression. In order to address this issue, we employed quantitative Western blot analysis to examine protein levels of GABA(A) receptor subunits alpha 1, alpha 5, beta 1, beta 2 in the hippocampus of subjects displaying increasing severity of AD neuropathology. Subjects were categorized into three groups based upon Braak staging pathologic criteria: pathologically mild (stages I/II, n=9); moderate (stages III/IV, n=8); and severe (stages V/VI, n=7). Across all subject groups, levels of subunit protein were heterogeneously distributed throughout the five hippocampal subregions analyzed (subiculum, CA1-3, dentate gyrus). Statistical analyses revealed differential preservation of GABA(A) receptor subunits in AD. In particular, alpha 1, beta 1, and beta 2 displayed little difference in protein levels among pathologically mild, moderate, and severe subject groups. In contrast, although relatively modest, protein levels of the alpha 5 subunit were significantly reduced between subjects with severe neuropathology compared with pathologically mild subjects (13.5% reduction). Collectively, our data provide evidence for heterogeneous distribution and relative sparing of GABA(A) receptor subunits in the hippocampus of AD patients.
Collapse
Affiliation(s)
- R A Rissman
- Laboratory of Neuronal Vulnerability and Aging, The Lankenau Institute for Medical Research, Jefferson Health System, Wynnewood, PA 19096, USA.
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Pirker S, Schwarzer C, Czech T, Baumgartner C, Pockberger H, Maier H, Hauer B, Sieghart W, Furtinger S, Sperk G. Increased expression of GABA(A) receptor beta-subunits in the hippocampus of patients with temporal lobe epilepsy. J Neuropathol Exp Neurol 2003; 62:820-34. [PMID: 14503638 DOI: 10.1093/jnen/62.8.820] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It has been postulated that dysfunction of the GABA-ergic transmission is causatively related to the development of epilepsy. Animal models of temporal lobe epilepsy (TLE) revealed considerable changes in the expression of GABA(A) receptor subunits in the hippocampus. Using immunocytochemistry, we investigated the expression of GABA(A) receptor subunits alpha1, alpha3, beta1-3, and gamma2 in hippocampal specimens obtained at surgery from TLE patients with and without hippocampal sclerosis and in autopsy controls. Consistent with the severe neurodegeneration in the CA1 sector, significant decreases in alpha1-, alpha3-, beta3-, and gamma2-subunit immunoreactivity (IR) were detected in sclerotic but not in nonsclerosic specimens. In contrast, pronounced increases in IR of all 3 beta-subunits were observed in most sectors of the hippocampal formation both in sclerotic and nonsclerotic specimens, being especially pronounced in the dentate molecular layer and in the subiculum where subunit alpha3- and gamma2-IR were also elevated. Using in situ hybridization for subunits beta2 and beta3, increased expression of the respective mRNAs was detected in dentate granule cells of patients with and without hippocampal sclerosis. Beta-subunits are important constituents of the GABA(A) receptor and contribute to the binding site of GABA. Our data indicate pronounced adaptive changes in the expression of these GABA(A) receptor subunits related to seizure activity and indicate altered assembly of GABA(A) receptors in TLE.
Collapse
Affiliation(s)
- Susanne Pirker
- Department of Pharmacology, University of Innsbruck, Innsbruck, Austria
| | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
DeLorey TM, Lin RC, McBrady B, He X, Cook JM, Lameh J, Loew GH. Influence of benzodiazepine binding site ligands on fear-conditioned contextual memory. Eur J Pharmacol 2001; 426:45-54. [PMID: 11525770 DOI: 10.1016/s0014-2999(01)01199-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Eight compounds that bind to the benzodiazepine binding site on the gamma-amino butyric acid(A) (GABA(A)) receptor were assessed for their influence on contextual memory, an aspect of memory affected in various cognitive disorders including Alzheimer's disease. Using a Pavlovian fear-conditioning paradigm, each ligand was evaluated in C57Bl/6 mice in regards to its direct affect on contextual memory and whether the ligand could attenuate scopolamine-induced contextual memory impairment. Of the eight ligands tested, one impaired contextual memory (agonist), six attenuated scopolamine-induced contextual memory impairment (inverse agonists), and one antagonized the ability of an inverse agonist to attenuate scopolamine-induced contextual memory impairment. Hence, further demonstrating the bi-directional influence benzodiazepine binding site ligands are able to exert on memory modulation. This study serves as an initial starting point in the development of pharmacological tools to be used in deciphering how GABA(A) receptors influence contextual memory.
Collapse
Affiliation(s)
- T M DeLorey
- Molecular Research Institute, 2495 Old Middlefield Way, Mountain View, CA 94043, USA.
| | | | | | | | | | | | | |
Collapse
|
32
|
Howell O, Atack JR, Dewar D, McKernan RM, Sur C. Density and pharmacology of alpha5 subunit-containing GABA(A) receptors are preserved in hippocampus of Alzheimer's disease patients. Neuroscience 2000; 98:669-75. [PMID: 10891610 DOI: 10.1016/s0306-4522(00)00163-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The anatomical localization and pharmacology of alpha5 subunit-containing GABA type-A receptors in the human hippocampal formation of Alzheimer's disease patients were studied with an alpha5 receptor selective ligand, [3H]L-655,708 and compared to age-matched human controls. Autoradiographic analyses revealed a heterogeneous distribution of [3H]L-655,708 binding sites in CA1-CA3 areas with high levels in stratum oriens, stratum pyramidale and stratum radiatum contrasting with low levels in stratum lacunosum. The highest quantity of alpha5 receptors was found in the molecular layer of the dentate gyrus. This pattern of expression was identical in both hippocampus from control and Alzheimer's disease subjects. Quantitative studies demonstrated that the number of [3H]L-655,708 binding sites is well preserved in Alzheimer's disease with only a moderate reduction (25-30%) in the CA1 subfield and entorhinal cortex. Furthermore, saturation and competition experiments with [3H]L-655,708 and representative benzodiazepine site ligands revealed that alpha5 receptors in Alzheimer's hippocampus have an alpha5beta2/3gamma2 pharmacology and structure as in control human brain.Overall, the data reported here provide evidence for a specific expression and relative sparing of alpha5 subunit-containing gamma-aminobutyric acid type-A receptors in the hippocampus of Alzheimer's patients.
Collapse
Affiliation(s)
- O Howell
- Department of Biochemistry, Merck Sharp and Dohme Research Laboratories, Terlings Park, Eastwick Road, Essex CM20 2QR, Harlow, UK
| | | | | | | | | |
Collapse
|
33
|
Abstract
Temporal lobe epilepsy (TLE) is associated with impaired inhibitory neurotransmission. Studies in animal models suggest that GABA(A) receptor dysfunction contributes to epileptogenesis. To understand the mechanisms underlying TLE in humans, it is fundamental to determine whether and how GABA(A) receptor subtypes are altered. Furthermore, identifying novel receptor targets is a prerequisite for developing selective antiepileptic drugs. We have therefore analyzed subunit composition and distribution of the three major GABA(A) receptor subtypes immunohistochemically with subunit-specific antibodies (alpha1, alpha2, alpha3, beta2,3, and gamma2) in surgical specimens from TLE patients with hippocampal sclerosis (n = 16). Profound alterations in GABA(A) receptor subtype expression were observed when compared with control hippocampi (n = 10). Although decreased GABA(A) receptor subunit staining, reflecting cell loss, was observed in CA1, CA3, and hilus, the distinct neuron-specific expression pattern of the alpha-subunit variants observed in controls was markedly changed in surviving neurons. In granule cells, prominent upregulation mainly of the alpha2-subunit was seen on somata and apical dendrites with reduced labeling on basal dendrites. In CA2, differential rearrangement of all three alpha-subunits occurred. Moreover, there was layer-specific loss of alpha1-subunit-immunoreactive interneurons in hippocampus proper, whereas surviving interneurons exhibited extensive changes in dendritic morphology. Throughout, expression patterns of beta2,3- and gamma2-subunits largely followed those of alpha-subunit variants. These results demonstrate unique subtype-specific expression of GABA(A) receptors in human hippocampus. The significant reorganization of distinct receptor subtypes in surviving hippocampal neurons of TLE patients with hippocampal sclerosis underlines the potential for synaptic plasticity in the human GABA system.
Collapse
|
34
|
Mizukami K, Ikonomovic MD, Grayson DR, Sheffield R, Armstrong DM. Immunohistochemical study of GABAA receptor alpha1 subunit in the hippocampal formation of aged brains with Alzheimer-related neuropathologic changes. Brain Res 1998; 799:148-55. [PMID: 9666109 DOI: 10.1016/s0006-8993(98)00437-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Immunocytochemical techniques were employed to examine the distribution of the gamma-aminobutyric acid (GABA)A receptor alpha1 subunit within the hippocampus of 19 elderly subjects with Alzheimer-related neuropathologic changes. In mild cases (i.e., Braak stages I and II), the most intense neuropil immunolabeling was observed in the molecular layer of the dentate gyrus, the stratum pyramidale of the CA1 subregion and subiculum, while the weakest labeling was observed in the CA3 subfield. In CA4 region, the proximal dendrites and cell bodies of mossy cells were intensely alpha1 positive. Throughout the hippocampus, we observed a number of alpha1 labeled interneurons. These cells consisted of both large and small multipolar cells as well as small bipolar neurons. In moderate cases (i.e., Braak stages III and IV), the pattern and intensity of alpha1 immunolabeling appeared indistinguishable from mild cases. In severe cases (i.e., Braak stages V and VI), we observed a marked decrease in neuropil immunolabeling within the CA2, CA1 subregions and prosubiculum, while the labeling of the molecular layer of the dentate gyrus, subiculum proper and presubiculum was indistinguishable from mild and moderate cases. These data together with our previous immunocytochemical study in which we demonstrated a marked preservation of the GABAA receptor subunit beta2/3 suggest that responses of selected GABAA receptor subunits to AD pathology are variable with the alpha1 subunit displaying a high degree of vulnerability.
Collapse
Affiliation(s)
- K Mizukami
- Neuroscience Research Center, MCP Hahnemann School of Medicine, Allegheny-Campus, 320 East North Avenue, Pittsburgh, PA 15212, USA
| | | | | | | | | |
Collapse
|
35
|
Mizukami K, Grayson DR, Ikonomovic MD, Sheffield R, Armstrong DM. GABAA receptor beta 2 and beta 3 subunits mRNA in the hippocampal formation of aged human brain with Alzheimer-related neuropathology. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1998; 56:268-72. [PMID: 9602147 DOI: 10.1016/s0169-328x(97)00347-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Our work on the role of glutamate in Alzheimer's disease (AD)-related neuronal vulnerability and death provided significant insight into the potential contribution of the gamma-aminobutyric acid (GABA) neurotransmitter system as it participates in countering the neurotoxic effects of excessive glutamate receptor stimulation. Our previous studies demonstrate that beta2/3 GABAA receptor subunit immunoreactivity is relatively well preserved in hippocampi with AD pathology. To further elucidate the molecular basis for this observation, we employed in situ hybridization histochemistry to examine the levels of beta2 and beta3 receptor subunit mRNAs in the hippocampus of 19 elderly subjects presenting with a broad range of pathologic severity (i.e., Braak stage I-VI). Semi-quantitative analysis with film autoradiograms revealed that beta2 mRNA signal was highest in the granule cell layer, CA2 and CA1 subfields, while beta3 mRNA hybridization was highest in the granule cell layer, followed by CA2>/=CA3>/=CA1 regions. No significant difference in beta2 mRNA expression was detected among the pathologically mild, moderate or severe groups. In contrast, levels of beta3 mRNA in the pathologically severe group was significantly decreased compared to the mild group within all subregions examined except CA4. Our data suggest that alterations in the expression of GABAA receptor subunits in the AD hippocampus differ between specific receptor subunits with the amount of beta2 mRNA being relatively well-preserved, while beta3 mRNA levels were decreased.
Collapse
Affiliation(s)
- K Mizukami
- Neuroscience Research Center, MCP-Hahnemann School of Medicine, Allegheny-Campus, 320 East North Avenue, Pittsburgh, PA 15212, USA
| | | | | | | | | |
Collapse
|