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Ethiraj J, Palpagama TH, Turner C, van der Werf B, Waldvogel HJ, Faull RLM, Kwakowsky A. The effect of age and sex on the expression of GABA signaling components in the human hippocampus and entorhinal cortex. Sci Rep 2021; 11:21470. [PMID: 34728681 PMCID: PMC8563768 DOI: 10.1038/s41598-021-00792-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 10/14/2021] [Indexed: 12/02/2022] Open
Abstract
Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the nervous system. The GABA signaling system in the brain is comprised of GABA synthesizing enzymes, transporters, GABAA and GABAB receptors (GABAAR and GABABR). Alterations in the expression of these signaling components have been observed in several brain regions throughout aging and between sexes in various animal models. The hippocampus is the memory centre of the brain and is impaired in several age-related disorders. It is composed of two main regions: the Cornu Ammonis (CA1-4) and the Dentate Gyrus (DG), which are interconnected with the Entorhinal Cortex (ECx). The age- and sex-specific changes of GABA signaling components in these regions of the human brain have not been examined. This study is the first to determine the effect of age and sex on the expression of GABA signaling components-GABAAR α1,2,3,5, β1-3, γ2, GABABR R1 and R2 subunits and the GABA synthesizing enzymes GAD 65/67-in the ECx, and the CA1 and DG regions of the human hippocampus using Western blotting. No significant differences were found in GABAAR α1,2,3,5, β1-3, γ2, GABABR R1 and R2 subunit and GAD65/76 expression levels in the ECx, CA1 and DG regions between the younger and older age groups for both sexes. However, we observed a significant negative correlation between age and GABAAR α1subunit level in the CA1 region for females; significant negative correlation between age and GABAAR β1, β3 and γ2 subunit expression in the DG region for males. In females a significant positive correlation was found between age and GABAAR γ2 subunit expression in the ECx and GABABR R2 subunit expression in the CA1 region. The results indicate that age and sex do not affect the expression of GAD 65/67. In conclusion, our results show age- and sex-related GABAA/BR subunit alterations in the ECx and hippocampus that might significantly influence GABAergic neurotransmission and underlie disease susceptibility and progression.
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Affiliation(s)
- Jayarjun Ethiraj
- grid.9654.e0000 0004 0372 3343Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Thulani Hansika Palpagama
- grid.9654.e0000 0004 0372 3343Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Clinton Turner
- grid.9654.e0000 0004 0372 3343Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, School of Medical Sciences, University of Auckland, Auckland, New Zealand ,grid.414055.10000 0000 9027 2851Department of Anatomical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Bert van der Werf
- grid.9654.e0000 0004 0372 3343Department of Epidemiology and Biostatistics, Faculty of Medical and Health Sciences, School of Population Health, University of Auckland, Auckland, New Zealand
| | - Henry John Waldvogel
- grid.9654.e0000 0004 0372 3343Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Richard Lewis Maxwell Faull
- grid.9654.e0000 0004 0372 3343Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Andrea Kwakowsky
- grid.9654.e0000 0004 0372 3343Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, School of Medical Sciences, University of Auckland, Auckland, New Zealand
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Hashimoto T, Kiyoshi T, Kohayakawa H, Iwamura Y, Yoshida N. Pharmacological properties of AC-3933, a novel benzodiazepine receptor partial inverse agonist. Neuroscience 2014; 256:352-9. [DOI: 10.1016/j.neuroscience.2013.10.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Chang Q, Savage LM, Gold PE. Microdialysis measures of functional increases in ACh release in the hippocampus with and without inclusion of acetylcholinesterase inhibitors in the perfusate. J Neurochem 2006; 97:697-706. [PMID: 16579834 DOI: 10.1111/j.1471-4159.2006.03765.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Because brain extracellular acetylcholine (ACh) levels are near detection limits in microdialysis samples, an acetylcholinesterase (AChE) inhibitor such as neostigmine is often added to microdialysis perfusates to increase ACh levels in the dialysate, a practice that raises concerns that the inhibitor might alter the results. Two experiments compared functional differences in ACh release with and without neostigmine. In the first experiment, 30-60% increases in extracellular ACh concentrations in the hippocampus were evident during food-rewarded T-maze training with 20-500 nm neostigmine in the perfusate but no increases were seen without neostigmine. In the second experiment, 78% increases in ACh release in the hippocampus were seen after injections of the GABA(A) receptor antagonist, bicuculline, into medial septum only if neostigmine (50 nm) was included in the perfusate. These findings suggest that, in the hippocampus, endogenous brain AChEs are very efficient at removing extracellular ACh, obscuring differences in ACh release in these experiments. Therefore, inclusion of AChE inhibitors in the microdialysis perfusate may be necessary under some conditions for observations of functional changes in release of ACh in the hippocampus.
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Affiliation(s)
- Qing Chang
- Department of Psychology and the Neuroscience Program, University of Illinois at Urbana-Champaign, Champaign, Illinois 61820, USA
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Padlubnaya D, Galizio M, Pitts RC, Keith JR. Chlordiazepoxide interactions with scopolamine and dizocilpine: novel cooperative and antagonistic effects on spatial learning. Behav Neurosci 2006; 119:1331-8. [PMID: 16300439 DOI: 10.1037/0735-7044.119.5.1331] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The authors investigated the effects on spatial behavior of coadministrations of a benzodiazepine, chlordiazepoxide (CDP), with a noncompetitive N-methyl-d-aspartate receptor antagonist (NMDAR), dizocilpine (DZP), and a muscarinic cholinergic receptor antagonist, scopolamine (SCP). Rats solved the Morris swim task in 2 settings; 1 in which a hidden escape platform was always in the same location (performance) and a 2nd in which the platform had been moved to a different location (acquisition) for repeated daily sessions. CDP (3.0 mg/kg) administered alone did not disrupt escape latencies or swim path accuracies. SCP and DZP each impaired acquisition and performance in a dose-dependent manner. CDP coadministered with 0.3 mg/kg SCP impaired escape only in the acquisition setting and when coadministered with 1.0 mg/kg SCP selectively exacerbated the escape impairment in the acquisition setting. CDP ameliorated deleterious effects of DZP in both settings.
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Affiliation(s)
- Diana Padlubnaya
- Department of Psychology, University of North Carolina at Wilmington, 610 South College Rd, NC 28403-5612, USA
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Korpi ER, Sinkkonen ST. GABA(A) receptor subtypes as targets for neuropsychiatric drug development. Pharmacol Ther 2005; 109:12-32. [PMID: 15996746 DOI: 10.1016/j.pharmthera.2005.05.009] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Accepted: 05/26/2005] [Indexed: 12/30/2022]
Abstract
The main inhibitory neurotransmitter system in the brain, the gamma-aminobutyric acid (GABA) system, is the target for many clinically used drugs to treat, for example, anxiety disorders and epilepsy and to induce sedation and anesthesia. These drugs facilitate the function of pentameric A-type GABA (GABA(A)) receptors that are extremely widespread in the brain and composed from the repertoire of 19 subunit variants. Modern genetic studies have found associations of various subunit gene polymorphisms with neuropsychiatric disorders, including alcoholism, schizophrenia, anxiety, and bipolar affective disorder, but these studies are still at their early phase because they still have failed to lead to validated drug development targets. Recent neurobiological studies on new animal models and receptor subunit mutations have revealed novel aspects of the GABA(A) receptors, which might allow selective targeting of the drug action in receptor subtype-selective fashion, either on the synaptic or extrasynaptic receptor populations. More precisely, the greatest advances have occurred in the clarification of the molecular and behavioral mechanisms of action of the GABA(A) receptor agonists already in the clinical use, such as benzodiazepines and anesthetics, rather than in the introduction of novel compounds to clinical practice. It is likely that these new developments will help to overcome the present problems of the chronic treatment with nonselective GABA(A) agonists, that is, the development of tolerance and dependence, and to focus the drug action on the neurobiologically and neuropathologically relevant substrates.
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Affiliation(s)
- Esa R Korpi
- Institute of Biomedicine, Pharmacology, Biomedicum Helsinki, P.O. Box 63 (Haartmaninkatu 8), FI-00014 University of Helsinki, Finland.
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Beracochea D, Celerier A, Pierard C. BetaCCM but not physostigmine enhancement of memory retrieval depends on emotional processes in mice. Psychopharmacology (Berl) 2004; 176:66-73. [PMID: 15064917 DOI: 10.1007/s00213-004-1854-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2003] [Accepted: 02/19/2004] [Indexed: 10/26/2022]
Abstract
RATIONALE The effects of methyl beta-carboline-3-carboxylate (betaCCM, an inverse agonists of GABA/benzodiazepine receptors) or physostigmine (a cholinesterase inhibitor) on retrieval processes and relationships with anxiety have been only marginally studied. OBJECTIVE This study investigates in mice the effects of acute betaCCM or physostigmine injections on retrieval of previously acquired discriminations involving distinct contextual cues (serial contextual discrimination; SCD) in a four-hole-board. Animals submitted to SCD were also evaluated for emotional reactivity in an elevated-plus maze. METHODS Mice were injected before the learning session began with a saline solution. Twenty-four hours later, mice were replaced on the context of the initial acquisition and a single dose of saline or betaCCM (0.5 or 1.5 mg/kg) or physostigmine (0.05 and 1.0 mg/kg) was injected 20 min before testing. RESULTS The highest dose of either betaCCM or physostigmine improved performance of the first discrimination in the SCD task. The higher dose of betaCCM produced anxiety-like reactivity in the plus maze, and scores of "anxiety" were significantly correlated with memory scores; in contrast, memory performance of physostigmine-treated subjects were totally independent of emotional reactivity. CONCLUSION These results show that, as opposed to physostigmine, betaCCM acts on retrieval processes specifically through its emotional component.
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Affiliation(s)
- Daniel Beracochea
- Laboratoire de Neurosciences Cognitives, UMR CNRS 5106, Batiment Biologie Animale, Université de Bordeaux 1, Avenue des Facultés, 33405 Talence, France.
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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.
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Affiliation(s)
- T M DeLorey
- Molecular Research Institute, 2495 Old Middlefield Way, Mountain View, CA 94043, USA.
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D'Hooge R, De Deyn PP. Applications of the Morris water maze in the study of learning and memory. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2001; 36:60-90. [PMID: 11516773 DOI: 10.1016/s0165-0173(01)00067-4] [Citation(s) in RCA: 1386] [Impact Index Per Article: 60.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Morris water maze (MWM) was described 20 years ago as a device to investigate spatial learning and memory in laboratory rats. In the meanwhile, it has become one of the most frequently used laboratory tools in behavioral neuroscience. Many methodological variations of the MWM task have been and are being used by research groups in many different applications. However, researchers have become increasingly aware that MWM performance is influenced by factors such as apparatus or training procedure as well as by the characteristics of the experimental animals (sex, species/strain, age, nutritional state, exposure to stress or infection). Lesions in distinct brain regions like hippocampus, striatum, basal forebrain, cerebellum and cerebral cortex were shown to impair MWM performance, but disconnecting rather than destroying brain regions relevant for spatial learning may impair MWM performance as well. Spatial learning in general and MWM performance in particular appear to depend upon the coordinated action of different brain regions and neurotransmitter systems constituting a functionally integrated neural network. Finally, the MWM task has often been used in the validation of rodent models for neurocognitive disorders and the evaluation of possible neurocognitive treatments. Through its many applications, MWM testing gained a position at the very core of contemporary neuroscience research.
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Affiliation(s)
- R D'Hooge
- Laboratory of Neurochemistry and Behavior, Born-Bunge Foundation, and Department of Neurology/Memory Clinic, Middelheim Hospital, University of Antwerp, Universiteitsplein 1, B-2610, Antwerp, Belgium.
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Emre M, Qizilbash N. Experimental approaches and drugs in development for the treatment of dementia. Expert Opin Investig Drugs 2001; 10:607-17. [PMID: 11281812 DOI: 10.1517/13543784.10.4.607] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Treatment of dementia can be divided as symptomatic treatment of cognitive or non-cognitive symptoms and the treatment of underlying pathology. In the last decade the thrust of symptomatic treatment of Alzheimer's disease (AD) has been enhancement of cholinergic transmission. Besides the acetycholinesterase inhibitors (AChE-I) currently in use, cholinergic agonists and enhancers are in development. Other therapeutic approaches directed towards neurotransmitter substitution or modulation include serotoninergic, noradrenergic substances, neuropeptides and those acting via excitatory amino acid receptors, such as ampakines or NMDA antagonists. Introduction of atypical neuroleptics represents the most recent development in the treatment of behavioural symptoms. Efforts to treat the underlying pathology are based on modulation of APP processing in order to decrease the accumulation of beta-amyloid, those to decrease tau hyperphosphorylation, use of nerve growth factors and those based on Apo-E modulation. Potential use of oestrogens and NSAIDs are also under investigation. Recently, vaccination with amyloid-beta peptide has been reported to be effective in an animal model of AD, this putative vaccine is now in clinical trials. Likewise, recent studies suggest that some statins may have a prophylactic effect.
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Affiliation(s)
- M Emre
- Istanbul Medical School, Department of Neirology, Capa/Istanbul, Turkey.
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Day JC, Kornecook TJ, Quirion R. Application of in vivo microdialysis to the study of cholinergic systems. Methods 2001; 23:21-39. [PMID: 11162147 DOI: 10.1006/meth.2000.1103] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The application of in vivo microdialysis to the study of acetylcholine (ACh) release has contributed greatly to our understanding of cholinergic brain systems. This article reviews standard experimental procedures for dialysis probe selection and implantation, perfusion parameters, neurochemical detection, and data analysis as they relate to microdialysis assessments of cholinergic function. Particular attention is focused on the unique methodological considerations that arise when in vivo microdialysis is dedicated expressly to the recovery and measurement of ACh as opposed to other neurotransmitters. Limitations of the microdialysis technique are discussed, as well as methodological adaptations that may prove useful in overcoming these limitations. This is followed by an overview of recent studies in which the application of in vivo microdialysis has been used to characterize the basic pharmacology and physiology of cholinergic neurons. Finally, the usefulness of the microdialysis approach for testing hypotheses regarding the cholinergic systems' involvement in cognitive processes is examined. It can be concluded that, in addition to being a versatile and practical method for studying the neurochemistry of cholinergic brain systems, in vivo microdialysis represents a valuable tool in our efforts to better comprehend ACh's underlying role in a variety of behavioral processes.
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Affiliation(s)
- J C Day
- Douglas Hospital Research Centre & Department of Psychiatry, McGill University, Verdun, Quebec, H4H 1R3, Canada
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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.
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Affiliation(s)
- O Howell
- Department of Biochemistry, Merck Sharp and Dohme Research Laboratories, Terlings Park, Eastwick Road, Essex CM20 2QR, Harlow, UK
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