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Orser BA. Discovering the Intriguing Properties of Extrasynaptic γ-Aminobutyric Acid Type A Receptors. Anesthesiology 2024; 140:1192-1200. [PMID: 38624275 DOI: 10.1097/aln.0000000000004949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Tonic inhibition in mouse hippocampal CA1 pyramidal neurons is mediated by α5 subunit-containing γ-aminobutyric acid type A receptors. By Caraiscos VB, Elliott EM, You-Ten KE, Cheng VY, Belelli D, Newell JG, Jackson MF, Lambert JJ, Rosahl TW, Wafford KA, MacDonald JF, Orser BA. Proc Natl Acad Sci U S A 2004; 101:3662-7. Reprinted with permission. In this Classic Paper Revisited, the author recounts the scientific journey leading to a report published in the Proceedings of the National Academy of Sciences (PNAS) and shares several personal stories from her formative years and "research truths" that she has learned along the way. Briefly, the principal inhibitory neurotransmitter in the brain, γ-aminobutyric acid (GABA), was conventionally thought to regulate cognitive processes by activating synaptic GABA type A (GABAA) receptors and generating transient inhibitory synaptic currents. However, the author's laboratory team discovered a novel nonsynaptic form of tonic inhibition in hippocampal pyramidal neurons, mediated by extrasynaptic GABAA receptors that are pharmacologically distinct from synaptic GABAA receptors. This tonic current is highly sensitive to most general anesthetics, including sevoflurane and propofol, and likely contributes to the memory-blocking properties of these drugs. Before the publication in PNAS, the subunit composition of GABAA receptors that generate the tonic current was unknown. The team's research showed that GABAA receptors containing the α5 subunit (α5GABAARs) generated the tonic inhibitory current in hippocampal neurons. α5GABAARs are highly sensitive to GABA, desensitize slowly, and are thus well suited for detecting low, persistent, ambient concentrations of GABA in the extracellular space. Interest in α5GABAARs has surged since the PNAS report, driven by their pivotal roles in cognitive processes and their potential as therapeutic targets for treating various neurologic disorders.
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Affiliation(s)
- Beverley A Orser
- Department of Anesthesiology and Pain Medicine, and Department of Physiology, University of Toronto, Toronto, Canada
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Zheng Y, Shao S, Zhang Y, Yuan S, Xing Y, Wang J, Qi X, Cui K, Tong J, Liu F, Cui S, Wan Y, Yi M. HCN2 Channels in the Ventral Hippocampal CA1 Regulate Nociceptive Hypersensitivity in Mice. Int J Mol Sci 2023; 24:13823. [PMID: 37762124 PMCID: PMC10531460 DOI: 10.3390/ijms241813823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/02/2023] [Accepted: 08/08/2023] [Indexed: 09/29/2023] Open
Abstract
Chronic pain is a significant health problem worldwide. Recent evidence has suggested that the ventral hippocampus is dysfunctional in humans and rodents, with decreased neuronal excitability and connectivity with other brain regions, parallel pain chronicity, and persistent nociceptive hypersensitivity. But the molecular mechanisms underlying hippocampal modulation of pain remain poorly elucidated. In this study, we used ex vivo whole-cell patch-clamp recording, immunofluorescence staining, and behavioral tests to examine whether hyperpolarization-activated cyclic nucleotide-gated channels 2 (HCN2) in the ventral hippocampal CA1 (vCA1) were involved in regulating nociceptive perception and CFA-induced inflammatory pain in mice. Reduced sag potential and firing rate of action potentials were observed in vCA1 pyramidal neurons from CFA-injected mice. Moreover, the expression of HCN2, but not HCN1, in vCA1 decreased in mice injected with CFA. HCN2 knockdown in vCA1 pyramidal neurons induced thermal hypersensitivity, whereas overexpression of HCN2 alleviated thermal hyperalgesia induced by intraplantar injection of CFA in mice. Our findings suggest that HCN2 in the vCA1 plays an active role in pain modulation and could be a promising target for the treatment of chronic pain.
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Affiliation(s)
- Yawen Zheng
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - Shan Shao
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - Yu Zhang
- National Health Commission Key Laboratory of Human Disease Comparative Medicine, Beijing Engineering Research Center for Experimental Animal Models of Human Critical Diseases, Institute of Laboratory Animal Science, Chinese Academy of Medical Science (CAMS) & Peking Union Medical College (PUMC), Beijing 100101, China;
| | - Shulu Yuan
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - Yuanwei Xing
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - Jiaxin Wang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - Xuetao Qi
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - Kun Cui
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - Jifu Tong
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - Fengyu Liu
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - Shuang Cui
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
| | - You Wan
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
- Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing 100101, China
| | - Ming Yi
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China; (Y.Z.); (S.S.); (S.Y.); (Y.X.); (J.W.); (X.Q.); (K.C.); (J.T.); (F.L.); (S.C.); (Y.W.)
- Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing 100101, China
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Wyroślak M, Dobrzański G, Mozrzymas JW. Bidirectional plasticity of GABAergic tonic inhibition in hippocampal somatostatin- and parvalbumin-containing interneurons. Front Cell Neurosci 2023; 17:1193383. [PMID: 37448697 PMCID: PMC10336215 DOI: 10.3389/fncel.2023.1193383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 06/05/2023] [Indexed: 07/15/2023] Open
Abstract
GABAA receptors present in extrasynaptic areas mediate tonic inhibition in hippocampal neurons regulating the performance of neural networks. In this study, we investigated the effect of NMDA-induced plasticity on tonic inhibition in somatostatin- and parvalbumin-containing interneurons. Using pharmacological methods and transgenic mice (SST-Cre/PV-Cre x Ai14), we induced the plasticity of GABAergic transmission in somatostatin- and parvalbumin-containing interneurons by a brief (3 min) application of NMDA. In the whole-cell patch-clamp configuration, we measured tonic currents enhanced by specific agonists (etomidate or gaboxadol). Furthermore, in both the control and NMDA-treated groups, we examined to what extent these changes depend on the regulation of distinct subtypes of GABAA receptors. Tonic conductance in the somatostatin-containing (SST+) interneurons is enhanced after NMDA application, and the observed effect is associated with an increased content of α5-containing GABAARs. Both fast-spiking and non-fast-spiking parvalbumin-positive (PV+) cells showed a reduction of tonic inhibition after plasticity induction. This effect was accompanied in both PV+ interneuron types by a strongly reduced proportion of δ-subunit-containing GABAARs and a relatively small increase in currents mediated by α5-containing GABAARs. Both somatostatin- and parvalbumin-containing interneurons show cell type-dependent and opposite sign plasticity of tonic inhibition. The underlying mechanisms depend on the cell-specific balance of plastic changes in the contents of α5 and δ subunit-containing GABAARs.
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Affiliation(s)
- Marcin Wyroślak
- Department of Biophysics and Neuroscience, Wroclaw Medical University, Wrocław, Poland
| | | | - Jerzy W. Mozrzymas
- Department of Biophysics and Neuroscience, Wroclaw Medical University, Wrocław, Poland
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Rubinstein MR, Burgueño AL, Quiroga S, Wald MR, Genaro AM. Current Understanding of the Roles of Gut-Brain Axis in the Cognitive Deficits Caused by Perinatal Stress Exposure. Cells 2023; 12:1735. [PMID: 37443769 PMCID: PMC10340286 DOI: 10.3390/cells12131735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/15/2023] [Accepted: 06/19/2023] [Indexed: 07/15/2023] Open
Abstract
The term 'perinatal environment' refers to the period surrounding birth, which plays a crucial role in brain development. It has been suggested that dynamic communication between the neuro-immune system and gut microbiota is essential in maintaining adequate brain function. This interaction depends on the mother's status during pregnancy and/or the newborn environment. Here, we show experimental and clinical evidence that indicates that the perinatal period is a critical window in which stress-induced immune activation and altered microbiota compositions produce lasting behavioral consequences, although a clear causative relationship has not yet been established. In addition, we discuss potential early treatments for preventing the deleterious effect of perinatal stress exposure. In this sense, early environmental enrichment exposure (including exercise) and melatonin use in the perinatal period could be valuable in improving the negative consequences of early adversities. The evidence presented in this review encourages the realization of studies investigating the beneficial role of melatonin administration and environmental enrichment exposure in mitigating cognitive alteration in offspring under perinatal stress exposure. On the other hand, direct evidence of microbiota restoration as the main mechanism behind the beneficial effects of this treatment has not been fully demonstrated and should be explored in future studies.
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Affiliation(s)
- Mara Roxana Rubinstein
- Laboratorio de Psiconeuroendocrinoinmunologia, Instituto de Investigaciones Biomédicas, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)—Pontificia Universidad Católica Argentina, Buenos Aires C1107AFF, Argentina; (A.L.B.); (S.Q.); (M.R.W.)
| | | | | | | | - Ana María Genaro
- Laboratorio de Psiconeuroendocrinoinmunologia, Instituto de Investigaciones Biomédicas, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)—Pontificia Universidad Católica Argentina, Buenos Aires C1107AFF, Argentina; (A.L.B.); (S.Q.); (M.R.W.)
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Wyroślak M, Lebida K, Mozrzymas JW. Induction of Inhibitory Synaptic Plasticity Enhances Tonic Current by Increasing the Content of α5-Subunit Containing GABA A Receptors in Hippocampal Pyramidal Neurons. Neuroscience 2021; 467:39-46. [PMID: 34033868 DOI: 10.1016/j.neuroscience.2021.05.020] [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: 03/24/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 11/16/2022]
Abstract
It is known that besides synaptic inhibition, there is a persistent component of inhibitory drive mediated by tonic currents which is believed to mediate majority of the total inhibitory charge in hippocampal neurons. Tonic currents, depending on cell types, can be mediated by a variety of GABAA receptor (GABAAR) subtypes but in pyramidal neurons, α5-subunit containing receptors were found to be predominant. Importantly, α5-GABAARs were implicated in both inhibitory and excitatory synaptic plasticity as well as in a variety of cognitive tasks. In the present study, we asked whether the protocol that evokes NMDAR-dependent GABAergic inhibitory long-term potentiation (iLTP) also induces the plasticity of tonic inhibition in hippocampal pyramidal neurons. Our whole-cell patch-clamp recordings revealed that the induction of this type of iLTP is associated with a marked increase in tonic current. By using the specific inverse agonist of α5-containing GABAARs (L-655,709) we provide evidence that this plastic change in tonic current is correlated with an increased proportion of this type of GABAARs. On the contrary, the iLTP induction did not affect the tonic current potentiated by THIP, indicating that the pool of δ subunit-containing GABAARs receptors remains unaffected. We conclude that the α5-GABAARs-dependent plasticity of tonic inhibition is a novel dimension of the neuroplasticity of the inhibitory drive in the hippocampal principal neurons. Overall, α5-containing GABAARs emerge as key players in a variety of plasticity mechanisms operating over a large span of time and spatial scales.
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Affiliation(s)
- Marcin Wyroślak
- Department of Biophysics and Neuroscience, Wroclaw Medical University, 50-367 Wroclaw, Poland.
| | - Katarzyna Lebida
- Department of Biophysics and Neuroscience, Wroclaw Medical University, 50-367 Wroclaw, Poland
| | - Jerzy W Mozrzymas
- Department of Biophysics and Neuroscience, Wroclaw Medical University, 50-367 Wroclaw, Poland
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Effect of Allopregnanolone on Spatial Memory and Synaptic Proteins in Animal Model of Metabolic Syndrome. Brain Sci 2021; 11:brainsci11050644. [PMID: 34063474 PMCID: PMC8156862 DOI: 10.3390/brainsci11050644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/04/2021] [Accepted: 05/11/2021] [Indexed: 11/26/2022] Open
Abstract
Metabolic Syndrome (MetS) is considered a common disorder, especially with a sedentary lifestyle and unhealthy food consumption. Cognitive impairment is one of the MetS consequences that worsens the quality of life of the patients. The study aimed to assess the therapeutic effect of the neurosteroid Allopregnalonone on spatial memory and, therefore, the expression of two synaptic plasticity markers in the hippocampus. Thirty-two male rats were divided into four groups: control groups, MetS, and MetS + Allopregnalone. Spatial memory has been evaluated by the Y-maze task and blood pressure measured by the rat tail method. Biochemical evaluation of serum glucose, insulin, lipid profile, and hippocampal expression of Synaptophysin and Associated Protein 43 (GAP-43) were performed for assessing Allopregnanolone on serum and hippocampal markers. Allopregnanolone therapy improved working spatial memory, hypertension, and biochemical markers measured in the serum and hippocampus.
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Liao VWY, Chebib M, Ahring PK. Efficient expression of concatenated α1β2δ and α1β3δ GABA A receptors, their pharmacology and stoichiometry. Br J Pharmacol 2021; 178:1556-1573. [PMID: 33491192 DOI: 10.1111/bph.15380] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/28/2020] [Accepted: 01/11/2021] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE GABAA receptors containing δ-subunits are notorious for being difficult to study in vitro due to heterogeneity of expressed receptor populations and low GABA-evoked current amplitudes. Thus, there are some published misconceptions and contradictory conclusions made regarding the pharmacology and stoichiometry of δ-containing receptors. The aim of this study was to obtain robust homogenous expression of α1βδ receptors for in-depth investigation. EXPERIMENTAL APPROACH Novel δ-containing pentameric concatenated constructs were designed. The resulting α1β2δ and α1β3δ GABAA receptor concatemers were investigated by two-electrode voltage-clamp electrophysiology using Xenopus laevis oocytes. KEY RESULTS First, while homogenous α1βδ GABAA receptor pools could not be obtained by manipulating the ratio of injected cRNAs of free α1, β2/3, and δ subunits, concatenated pentameric α1β2δ and α1β3δ constructs resulted in robust expression levels of concatemers. Second, by using optimised constructs that give unidirectional assembly of concatemers, we found that the δ subunit cannot directly participate in GABA binding and receptor activation. Hence, functional δ-containing receptors are likely to all have a conventional 2α:2β:1δ stoichiometry arranged as βαβαδ when viewed counterclockwise from the extracellular side. Third, α1β2/3δ receptors were found to express efficiently in X. laevis oocytes but have a low estimated open probability of ~0.5% upon GABA activation. Because of this, these receptors are uniquely susceptible to positive allosteric modulation by, for example, neurosteroids. CONCLUSION AND IMPLICATIONS Our data answer important outstanding questions regarding the pharmacology and stoichiometry of α1δ-containing GABAA receptors and pave the way for future analysis and drug discovery efforts.
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Affiliation(s)
- Vivian Wan Yu Liao
- Brain and Mind Centre, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Mary Chebib
- Brain and Mind Centre, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Philip Kiaer Ahring
- Brain and Mind Centre, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
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Yang J, Yang Q. Identification of Core Genes and Screening of Potential Targets in Glioblastoma Multiforme by Integrated Bioinformatic Analysis. Front Oncol 2021; 10:615976. [PMID: 33718116 PMCID: PMC7943725 DOI: 10.3389/fonc.2020.615976] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 12/30/2020] [Indexed: 12/28/2022] Open
Abstract
Glioblastoma multiforme is the most common primary intracranial malignancy, but its etiology and pathogenesis are still unclear. With the deepening of human genome research, the research of glioma subtype screening based on core molecules has become more in-depth. In the present study, we screened out differentially expressed genes (DEGs) through reanalyzing the glioblastoma multiforme (GBM) datasets GSE90598 from the Gene Expression Omnibus (GEO), the GBM dataset TCGA-GBM and the low-grade glioma (LGG) dataset TCGA-LGG from the Cancer Genome Atlas (TCGA). A total of 150 intersecting DEGs were found, of which 48 were upregulated and 102 were downregulated. These DEGs from GSE90598 dataset were enriched using the overrepresentation method, and multiple enriched gene ontology (GO) function terms were significantly correlated with neural cell signal transduction. DEGs between GBM and LGG were analyzed by gene set enrichment analysis (GSEA), and the significantly enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways involved in synapse signaling and oxytocin signaling pathways. Then, a protein-protein interaction (PPI) network was constructed to assess the interaction of proteins encoded by the DEGs. MCODE identified 2 modules from the PPI network. The 11 genes with the highest degrees in module 1 were designated as core molecules, namely, GABRD, KCNC1, KCNA1, SYT1, CACNG3, OPALIN, CD163, HPCAL4, ANK3, KIF5A, and MS4A6A, which were mainly enriched in ionic signaling-related pathways. Survival analysis of the GSE83300 dataset verified the significant relationship between expression levels of the 11 core genes and survival. Finally, the core molecules of GBM and the DrugBank database were assessed by a hypergeometric test to identify 10 drugs included tetrachlorodecaoxide related to cancer and neuropsychiatric diseases. Further studies are required to explore these core genes for their potentiality in diagnosis, prognosis, and targeted therapy and explain the relationship among ionic signaling-related pathways, neuropsychiatric diseases and neurological tumors.
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Affiliation(s)
- Ji'an Yang
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Qian Yang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, China
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Enhanced expression of GABRD predicts poor prognosis in patients with colon adenocarcinoma. Transl Oncol 2020; 13:100861. [PMID: 32891902 PMCID: PMC7484591 DOI: 10.1016/j.tranon.2020.100861] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 08/05/2020] [Accepted: 08/07/2020] [Indexed: 12/24/2022] Open
Abstract
Neurotransmitters are reported to be involved in tumor initiation and progression. This study aimed to elucidate the prognostic value of γ-aminobutyric acid type A receptor δ subunit (GABRD) in colon adenocarcinoma (COAD) using the data from The Cancer Genome Atlas (TCGA) database. The GABRD mRNA expression levels in the COAD and normal tissues were compared using the Wilcoxon rank-sum test. The correlation between clinicopathologic characteristics and GABRD expression was analyzed by Wilcoxon rank-sum test or Kruskal-Wallis test and logistic regression. The prognostic value of GABRD mRNA expression in patients with COAD was determined using the Kaplan-Meier curve and Cox regression analysis. Finally, the molecular mechanisms of GABRD in COAD were predicted by gene set enrichment analysis (GSEA). The COAD tissues exhibited higher GABRD mRNA expression levels than the normal tissues. The logistic regression analysis revealed that GABRD mRNA expression was correlated with TNM stage, N stage, M stage, and microsatellite instability (MSI) status. The Kaplan-Meier survival curve and log-rank test revealed that patients with COAD exhibiting high GABRD mRNA expression were associated with poor overall survival (OS). The multivariate analysis indicated that increased GABRD mRNA expression was an independent prognostic factor and was correlated with a poor OS. The GSEA revealed that GABRD was involved in signaling pathways, including cell adhesion molecules, gap junction, melanogenesis, and mTOR signaling pathway, as well as the signaling pathways associated with basal cell carcinoma or bladder cancer development. In summary, enhanced GABRD mRNA expression may be a potential independent prognostic biomarker for COAD.
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Aghighi Bidgoli F, Salami M, Talaei SA. Environmental enrichment restores impaired spatial memory and synaptic plasticity in prenatally stress exposed rats: The role of GABAergic neurotransmission. Int J Dev Neurosci 2020; 80:573-585. [PMID: 32706909 DOI: 10.1002/jdn.10052] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 07/15/2020] [Accepted: 07/18/2020] [Indexed: 11/05/2022] Open
Abstract
Evidence shows that prenatal stress negatively affects cognitive functions and activity of neuronal circuits in postnatal age. Environmental enrichment counteracts deficits induced by early life stress. We examined if behavioural function and synaptic plasticity are sensitive to prenatal stress and, how much environmental enrichment and GABAergic system impact these phenomena. Animals were exposed to noise stress during the third trimester of foetal life. Groups of the stressed animals remained intact (S-SH) or received enrichment (S-EE) from postnatal day 22 for one month. Also, two groups received either saline (S-SH-S) or bicuculline (S-SH-B). One enriched group received muscimol (S-EE-M). The control groups were intact (C-SH), enriched (C-EE), or received bicuculline (C-SH-B) or saline (C-SH-S). We assessed learning and memory and, hippocampal long-term potentiation (LTP). Serum corticosterone levels were detected as a measure of stress condition. We found that stress reduced spatial performance and suppressed LTP in the S-SH animals. Postnatal enrichment restored both spatial learning and memory and synaptic plasticity in the S-EE rats. GABAergic antagonism strengthens maze performance and LTP induction in the S-SH-B group. However, muscimol prevented the positive effects of enrichment in the S-EE-M animals. Environmental enrichment and GABAergic modulation may improve disrupted spatial performance and synaptic plasticity.
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Affiliation(s)
- Fatemeh Aghighi Bidgoli
- Physiology Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran
| | - Mahmoud Salami
- Physiology Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran
| | - Sayyed Alireza Talaei
- Physiology Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran
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Cognitive impairments in adult mice with RIP140 overexpression in neural stem cells. Behav Brain Res 2020; 393:112777. [PMID: 32579978 DOI: 10.1016/j.bbr.2020.112777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 05/27/2020] [Accepted: 06/16/2020] [Indexed: 12/31/2022]
Abstract
Receptor-interacting protein 140 (RIP140) is a transcription co-regulator of several transcription factors and a signal transduction regulator. RIP140 was recently implicated in the regulation of cognitive functions. The gene that encodes RIP140 is located on chromosome 21. An increase in RIP140 expression was observed in the fetal cerebral cortex and hippocampus in Down syndrome patients who exhibited strong cognitive disabilities. We hypothesized that RIP140 overexpression affects cognitive function in adult neural development. The present study used a Cre-dependent adeno-associated virus to selectively overexpress RIP140 in neural stem cells using nestin-Cre mice. RIP140 overexpression efficiency was evaluated at the subgranular zone (SGZ) of the dorsal dentate gyrus (dDG) and the subventricular zone (SVZ) of the lateral ventricles (LVs). Mice with RIP140 overexpression in the SGZ exhibited deficits in cognitive function and spatial learning and memory, measured in the Morris water maze, object-place recognition test, and novel object recognition test. However, overexpression of RIP140 in SVZ only impaired performance in the Morris water maze and novel object recognition test but not in the object-place recognition test. Altogether, these results indicated defects in cognitive functions that were associated with RIP140 overexpression in neural stem cells and revealed a behavioral phenotype that may be used as a framework for further investigating the neuropathogenesis of Down syndrome.
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Neonatal Clonazepam Administration Induced Long-Lasting Changes in GABA A and GABA B Receptors. Int J Mol Sci 2020; 21:ijms21093184. [PMID: 32366006 PMCID: PMC7246485 DOI: 10.3390/ijms21093184] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/24/2020] [Accepted: 04/28/2020] [Indexed: 11/17/2022] Open
Abstract
Benzodiazepines (BZDs) are widely used in patients of all ages. Unlike adults, neonatal animals treated with BZDs exhibit a variety of behavioral deficits later in life; however, the mechanisms underlying these deficits are poorly understood. This study aims to examine whether administration of clonazepam (CZP; 1 mg/kg/day) in 7-11-day-old rats affects Gama aminobutyric acid (GABA)ergic receptors in both the short and long terms. Using RT-PCR and quantitative autoradiography, we examined the expression of the selected GABAA receptor subunits (α1, α2, α4, γ2, and δ) and the GABAB B2 subunit, and GABAA, benzodiazepine, and GABAB receptor binding 48 h, 1 week, and 2 months after treatment discontinuation. Within one week after CZP cessation, the expression of the α2 subunit was upregulated, whereas that of the δ subunit was downregulated in both the hippocampus and cortex. In the hippocampus, the α4 subunit was downregulated after the 2-month interval. Changes in receptor binding were highly dependent on the receptor type, the interval after treatment cessation, and the brain structure. GABAA receptor binding was increased in almost all of the brain structures after the 48-h interval. BZD-binding was decreased in many brain structures involved in the neuronal networks associated with emotional behavior, anxiety, and cognitive functions after the 2-month interval. Binding of the GABAB receptors changed depending on the interval and brain structure. Overall, the described changes may affect both synaptic development and functioning and may potentially cause behavioral impairment.
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Khodaei S, Avramescu S, Wang DS, Sheng H, Chan NK, Lecker I, Fernandez-Escobar A, Lei G, Dewar MB, Whissell PD, Baker AJ, Orser BA. Inhibiting α5 Subunit-Containing γ-Aminobutyric Acid Type A Receptors Attenuates Cognitive Deficits After Traumatic Brain Injury. Crit Care Med 2020; 48:533-544. [PMID: 32205600 DOI: 10.1097/ccm.0000000000004161] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVES Cognitive deficits after traumatic brain injury are a leading cause of disability worldwide, yet no effective pharmacologic treatments exist to improve cognition. Traumatic brain injury increases proinflammatory cytokines, which trigger excess function of α5 subunit-containing γ-aminobutyric acid type A receptors. In several models of brain injury, drugs that inhibit α5 subunit-containing γ-aminobutyric acid type A receptor function improve cognitive performance. Thus, we postulated that inhibiting α5 subunit-containing γ-aminobutyric acid type A receptors would improve cognitive performance after traumatic brain injury. In addition, because traumatic brain injury reduces long-term potentiation in the hippocampus, a cellular correlate of memory, we studied whether inhibition of α5 subunit-containing γ-aminobutyric acid type A receptors attenuated deficits in long-term potentiation after traumatic brain injury. DESIGN Experimental animal study. SETTING Research laboratory. SUBJECTS Adult male mice and hippocampal brain slices. INTERVENTIONS Anesthetized mice were subjected to traumatic brain injury with a closed-head, free-weight drop method. One week later, the mice were treated with L-655,708 (0.5 mg/kg), an inhibitor that is selective for α5 subunit-containing γ-aminobutyric acid type A receptors, 30 minutes before undergoing behavioral testing. Problem-solving abilities were assessed using the puzzle box assay, and memory performance was studied with novel object recognition and object place recognition assays. In addition, hippocampal slices were prepared 1 week after traumatic brain injury, and long-term potentiation was studied using field recordings in the cornu Ammonis 1 region of slices that were perfused with L-655,708 (100 nM). MEASUREMENTS AND MAIN RESULTS Traumatic brain injury increased the time required to solve difficult but not simple tasks in the puzzle box assay and impaired memory in the novel object recognition and object place recognition assays. L-655,708 improved both problem solving and memory in the traumatic brain injury mice. Traumatic brain injury reduced long-term potentiation in the hippocampal slices, and L-655,708 attenuated this reduction. CONCLUSIONS Pharmacologic inhibition of α5 subunit-containing γ-aminobutyric acid type A receptors attenuated cognitive deficits after traumatic brain injury and enhanced synaptic plasticity in hippocampal slices. Collectively, these results suggest that α5 subunit-containing γ-aminobutyric acid type A receptors are novel targets for pharmacologic treatment of traumatic brain injury-induced persistent cognitive deficits.
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Affiliation(s)
- Shahin Khodaei
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Sinziana Avramescu
- Department of Anesthesia, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Dian-Shi Wang
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Heping Sheng
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Nathan K Chan
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Irene Lecker
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | | | - Gang Lei
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Michael B Dewar
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Paul D Whissell
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Andrew J Baker
- Department of Anesthesia, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia, St. Michael's Hospital, Toronto, ON, Canada
| | - Beverley A Orser
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
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Jung HY, Kwon HJ, Kim W, Nam SM, Kim JW, Hahn KR, Yoo DY, Yoon YS, Choi SY, Kim DW, Hwang IK. Role of pyridoxine in GABA synthesis and degradation in the hippocampus. Tissue Cell 2019; 61:72-78. [PMID: 31759410 DOI: 10.1016/j.tice.2019.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 09/02/2019] [Accepted: 09/17/2019] [Indexed: 10/26/2022]
Abstract
Pyridoxal-5'-phosphate, the active form of vitamin B6, is associated with activities of several enzymes and the treatment of various neurological disorders. Here, we investigated the effects of pyridoxine on the immunoreactivity and protein levels of γ-aminobutyric acid (GABA)-synthesizing and degradation enzymes such as glutamic acid decarboxylase (GAD), GABA transaminase (GABA-T), and succinic semialdehyde dehydrogenase (SSADH), in the hippocampus of mice. The mice intraperitonially received physiological saline and 350 mg/kg pyridoxine, twice a day for 21 days, and were euthanized 2 h after the final dose. In the vehicle-treated group, we observed GAD67 immunoreactivity in the stratum pyramidale of the CA1 and CA3 region, Schaffer collateral, polymorphic layer, and outer granule cell layer of the dentate gyrus. Pyridoxine administration significantly increased GAD67 immunoreactivity, while significantly decreasing GABA-T immunoreactivity in pyridoxine-treated mouse hippocampi (CA1 region and dentate gyrus). In the stratum lacunosum-moleculare of CA1 region, GABA-T immunoreactivity was significantly increased in the pyridoxine-treated group compared to that in the vehicle-treated group, although GAD67 immunoreactivity was similarly observed in these groups. Alternatively, there were no significant differences in SSADH immunoreactivity in any regions of the hippocampus between the vehicle- and pyridoxine-treated groups. Western blot analysis showed significant increases in GAD67 and GABA-T protein levels in the pyridoxine-treated group compared with those in the vehicle-treated group. Therefore, pyridoxine administration facilitates GABA turnover in mouse hippocampus by modulating the GABA-synthesizing and degradation enzymes.
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Affiliation(s)
- Hyo Young Jung
- Department of Anatomy and Cell Biology, College of Veterinary Medicine, and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, South Korea
| | - Hyun Jung Kwon
- Department of Biochemistry and Molecular Biology, Research Institute of Oral Sciences, College of Dentistry, Gangneung-Wonju National University, Gangneung 25457, South Korea
| | - Woosuk Kim
- Department of Biomedical Sciences, and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon 24252, South Korea
| | - Sung Min Nam
- Department of Anatomy, College of Veterinary Medicine, Konkuk University, Seoul 05030, South Korea
| | - Jong Whi Kim
- Department of Anatomy and Cell Biology, College of Veterinary Medicine, and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, South Korea
| | - Kyu Ri Hahn
- Department of Anatomy and Cell Biology, College of Veterinary Medicine, and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, South Korea
| | - Dae Young Yoo
- Department of Anatomy, College of Medicine, Soonchunhyang University, Cheonan, Chungcheongnam 31151, South Korea
| | - Yeo Sung Yoon
- Department of Anatomy and Cell Biology, College of Veterinary Medicine, and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, South Korea
| | - Soo Young Choi
- Department of Biomedical Sciences, and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon 24252, South Korea
| | - Dae Won Kim
- Department of Biochemistry and Molecular Biology, Research Institute of Oral Sciences, College of Dentistry, Gangneung-Wonju National University, Gangneung 25457, South Korea.
| | - In Koo Hwang
- Department of Biomedical Sciences, and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon 24252, South Korea.
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Zhang H, Zhang L, Tang Y, Wang C, Chen Y, Shu J, Zhang K. Systemic screening identifies GABRD, a subunit gene of GABAA receptor as a prognostic marker in adult IDH wild-type diffuse low-grade glioma. Biomed Pharmacother 2019; 118:109215. [PMID: 31545245 DOI: 10.1016/j.biopha.2019.109215] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/04/2019] [Accepted: 07/08/2019] [Indexed: 12/22/2022] Open
Abstract
Currently, no reliable prognostic biomarkers have been identified for adult IDH wild-type (WT) diffuse low grade glioma (LGG). With data from The Cancer Genome Atlas (TCGA)-LGG, we examined the prognostic value of GABAA receptor subunits in adult IDH WT LGG. Using 2016 WHO CNS tumor classification, we re-classified the TCGA-LGG and identified 95 IDH WT patients. Among 16 GABAA receptor subunit genes with RNA-seq data, eight genes showed significantly different expression in IDH WT LGG compared with IDH mutant (MT) cases. Among these genes, only GABRD expression was related to overall survival (OS) status. Preserved GABRD expression was independently associated with longer OS (HR: 0.799, 95%CI: 0.691-0.925, p = 0.003) in IDH WT LGG. GABRD expression showed a moderately negative correlation with tumor infiltration macrophage (TIM) and CSF1 expression. The methylation status of 34 CpG sites across GABRD gene was checked and only cg13916816 showed a moderately negative correlation with GABRD expression. In conclusion, GABRD expression might serve as a potential independent prognostic marker in patients with IDH WT LGG. Meanwhile, its expression was negatively correlated with the extent of TIM, which might help to explain the favorable survival outcome. Cg13916816 might be a critical CpG site influencing GABRD expression in IDH WT LGG.
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Affiliation(s)
- Hongwei Zhang
- Department of Anesthesiology, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610041, China
| | - Lixia Zhang
- Department of Hepatobiliary and Pancreatic Surgery, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610041, China
| | - Yumin Tang
- Department of Anesthesiology, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610041, China
| | - Chaoji Wang
- Department of Anesthesiology, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610041, China
| | - Yiding Chen
- Department of Anesthesiology, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610041, China
| | - Jinjun Shu
- Department of Anesthesiology, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610041, China
| | - Kexian Zhang
- Department of Anesthesiology, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610041, China.
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Selective Activation of Cholecystokinin-Expressing GABA (CCK-GABA) Neurons Enhances Memory and Cognition. eNeuro 2019; 6:eN-NWR-0360-18. [PMID: 30834305 PMCID: PMC6397954 DOI: 10.1523/eneuro.0360-18.2019] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 01/04/2019] [Accepted: 01/23/2019] [Indexed: 12/15/2022] Open
Abstract
Cholecystokinin-expressing GABAergic (CCK-GABA) neurons are perisomatic inhibitory cells that have been argued to regulate emotion and sculpt the network oscillations associated with cognition. However, no study has selectively manipulated CCK-GABA neuron activity during behavior in freely-moving animals. To explore the behavioral effects of activating CCK-GABA neurons on emotion and cognition, we utilized a novel intersectional genetic mouse model coupled with a chemogenetic approach. Specifically, we generated triple transgenic CCK-Cre;Dlx5/6-Flpe;RC::FL-hM3Dq (CCK-GABA/hM3Dq) mice that expressed the synthetic excitatory hM3Dq receptor in CCK-GABA neurons. Results showed that clozapine-N-oxide (CNO)-mediated activation of CCK-GABA neurons did not alter open field (OF) or tail suspension (TS) performance and only slightly increased anxiety in the elevated plus maze (EPM). Although CNO treatment had only modestly affected emotional behavior, it significantly enhanced multiple cognitive and memory behaviors including social recognition, contextual fear conditioning, contextual discrimination, object recognition, and problem-solving in the puzzle box. Collectively, these findings suggest that systemic activation of CCK-GABA neurons minimally affects emotion but significantly enhances cognition and memory. Our results imply that CCK-GABA neurons are more functionally diverse than originally expected and could serve as a potential therapeutic target for the treatment of cognitive/memory disorders.
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Novais A, Silva A, Ferreira AC, Falcão AM, Sousa N, Palha JA, Marques F, Sousa JC. Adult Hippocampal Neurogenesis Modulation by the Membrane-Associated Progesterone Receptor Family Member Neudesin. Front Cell Neurosci 2018; 12:463. [PMID: 30534059 PMCID: PMC6275434 DOI: 10.3389/fncel.2018.00463] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 11/13/2018] [Indexed: 11/13/2022] Open
Abstract
Neudesin (Neuron-derived neurotrophic factor, NENF), a membrane-associated progesterone receptor family (MAPR) member, is a neuron secreted protein with neurotrophic properties during embryonic stages. However, its role in the adult brain is still poorly addressed. In this study we have used neudesin-null (Nenf−/−) mice and performed a characterization of the proliferation state of the adult neurogenic niches, the adult subventricular zone (SVZ) and the hippocampus subgranular zone (SGZ). Nenf−/− males did not presented any deficits in proliferation in the SVZ neither in vivo nor in vitro. On the other hand a decrease in cell proliferation in the SGZ was observed, as well as a decrease in the number of newborn neurons in the dentate gyrus (DG) that was accompanied by impaired context discrimination in a contextual fear conditioning (CFC) task. Since NENF neurotrophic action is suggested to occur via the formation of a progesterone stability complex for the activation of non-genomic cascade, we further evaluated progesterone metabolism in the absence of NENF. Interestingly, expression of progesterone catabolic rate-determining enzyme, 5-α-reductase was upregulated in the DG of Nenf−/−, together with a significant increase in the expression of the δGABAA receptor gene, involved in DG tonic inhibition. Taken together, these findings add in vivo evidence on the neurotrophic properties of NENF in the adult brain. Furthermore, the mechanism of action of NENF in this process might implicate neurosteroids modulation, at least in the DG.
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Affiliation(s)
- Ashley Novais
- Life and Health Sciences Research Institute (ICVS), Neuroscience Domain, School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Guimarães, Portugal
| | - Alberto Silva
- Life and Health Sciences Research Institute (ICVS), Neuroscience Domain, School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Guimarães, Portugal
| | - Ana Catarina Ferreira
- Life and Health Sciences Research Institute (ICVS), Neuroscience Domain, School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Guimarães, Portugal
| | - Ana Mendanha Falcão
- Life and Health Sciences Research Institute (ICVS), Neuroscience Domain, School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Guimarães, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), Neuroscience Domain, School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Guimarães, Portugal
| | - Joana Almeida Palha
- Life and Health Sciences Research Institute (ICVS), Neuroscience Domain, School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Guimarães, Portugal
| | - Fernanda Marques
- Life and Health Sciences Research Institute (ICVS), Neuroscience Domain, School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Guimarães, Portugal
| | - João Carlos Sousa
- Life and Health Sciences Research Institute (ICVS), Neuroscience Domain, School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Guimarães, Portugal
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18
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Siivonen MS, de Miguel E, Aaltio J, Manner AK, Vahermo M, Yli-Kauhaluoma J, Linden AM, Aitta-Aho T, Korpi ER. Conditioned Reward of Opioids, but not Psychostimulants, is Impaired in GABA-A Receptor δ Subunit Knockout Mice. Basic Clin Pharmacol Toxicol 2018; 123:558-566. [PMID: 29781560 DOI: 10.1111/bcpt.13043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/07/2018] [Indexed: 12/17/2022]
Abstract
Extrasynaptic δ subunit-containing γ-aminobutyric acid type A receptors (δ-GABAA Rs) are emerging as targets for a number of neuropsychopharmacological drugs, including the direct GABA site agonist gaboxadol and neuroactive steroids. Among other regions, these δ-GABAA Rs are functionally expressed in the ventral tegmental area (VTA), the cell body region of mesocorticolimbic dopamine (DA) system important for motivated behaviours, and in the target region, the nucleus accumbens. Gaboxadol and neurosteroids induce VTA DA neuron plasticity ex vivo, by inhibiting the VTA GABA neurons, and aversive place conditioning, which are absent in the δ-GABAA R knockout mice (δ-KO). It is not known whether δ-GABAA Rs are important for the effects of other drugs, such as opioids (that also inhibit GABA neurons) and stimulants (that primarily elevate monoamine levels). Here, we used δ-KO mice and conditioned place preference (CPP) test to study the rewarding effects of morphine (20 mg/kg), methamphetamine (1 mg/kg) and mephedrone (5 mg/kg). Morphine-induced nociception was also assessed using tail-flick and hot-plate tests. We found that the δ-KO mice failed to express morphine-induced CPP, but that they were more sensitive to morphine-induced analgesia in the tail-flick test. In contrast, stimulant-induced CPP in the δ-KO mice was similar to that in the wild-type controls. Thus, the conditioned rewarding effect by opioids, but not that of stimulants, was impaired in the absence of δ-GABAA Rs. Further studies are warranted to assess the potential of δ-GABAA R antagonists as possible targets for reducing morphine reward and potentiating morphine analgesia.
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Affiliation(s)
- Milo S Siivonen
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Elena de Miguel
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Juho Aaltio
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Aino K Manner
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Mikko Vahermo
- Drug Discovery Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Jari Yli-Kauhaluoma
- Drug Discovery Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Anni-Maija Linden
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Teemu Aitta-Aho
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Esa R Korpi
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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19
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An Emerging Circuit Pharmacology of GABA A Receptors. Trends Pharmacol Sci 2018; 39:710-732. [PMID: 29903580 DOI: 10.1016/j.tips.2018.04.003] [Citation(s) in RCA: 131] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/23/2018] [Accepted: 04/17/2018] [Indexed: 12/21/2022]
Abstract
In the past 20 years we have learned a great deal about GABAA receptor (GABAAR) subtypes, and which behaviors are regulated or which drug effects are mediated by each subtype. However, the question of where GABAARs involved in specific drug effects and behaviors are located in the brain remains largely unanswered. We review here recent studies taking a circuit pharmacology approach to investigate the functions of GABAAR subtypes in specific brain circuits controlling fear, anxiety, learning, memory, reward, addiction, and stress-related behaviors. The findings of these studies highlight the complexity of brain inhibitory systems and the importance of taking a subtype-, circuit-, and neuronal population-specific approach to develop future therapeutic strategies using cell type-specific drug delivery.
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Zheng X, Liang L, Hei C, Yang W, Zhang T, Wu K, Qin Y, Chang Q. Bilateral Olfactory Mucosa Damage Induces the Disappearance of Olfactory Glomerulus and Reduces the Expression of Extrasynaptic α5GABA ARs in the Hippocampus in Early Postnatal Sprague Dawley Rats. Neurotox Res 2018; 34:353-362. [PMID: 29667127 DOI: 10.1007/s12640-018-9893-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 03/07/2018] [Accepted: 03/20/2018] [Indexed: 10/17/2022]
Abstract
Chloroform-induced olfactory mucosal degeneration has been reported in adult rats following gavage. We used fixed-point chloroform infusions on different postnatal days (PNDs) to investigate the effects of early olfactory bilateral deprivation on the main olfactory bulbs in Sprague Dawley rats. The experimental groups included rats infused with chloroform (5 μl) or saline (sham, 5 μl) on PNDs 3 and 8, and rats not receiving infusions (control) (n = 6 in all groups). Rats receiving chloroform on PND 3 showed significant hypoevolutism when compared to those in other groups (P < 0.05). There was a complete disappearance and a significant reduction in the size of olfactory glomeruli in the PND 3 and 8 groups, respectively, when compared to the respective sham groups. Rats receiving chloroform on PND 3 had significant memory impairment (P < 0.01) and increased levels of learned helplessness (P < 0.05), as measured using the Morris water maze and tail suspension tests, respectively. GABAA receptor alpha5 subunit (α5GABAAR) expression in hippocampal neurons was significantly lower in rats receiving chloroform on PND 3 than in rats in other groups (P < 0.01), as measured using immunohistochemistry and polymerase chain reaction. There was thus a critical period for the preservation of regenerative ability in olfactory receptor neurons, during which damage and olfactory deprivation led to altered rhinencephalon structure and disappearance of olfactory glomeruli, which induced hypoevolutism. Olfactory deprivation after the critical period had no significant effect on olfactory receptor neuron regeneration, leading to reduced developmental and behavioral effects in Sprague Dawley rats.
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Affiliation(s)
- Xiaomin Zheng
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Key Laboratory of Reproduction and Genetic Heredity of Ningxia Hui Autonomous Region, The School of Basic Medicine, Department of Anatomy, Ningxia Medical University, Yinchuan, 750004, China.
| | - Liang Liang
- Hubei General Hospital, Wuhan, 430060, China
| | - Changchun Hei
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Key Laboratory of Reproduction and Genetic Heredity of Ningxia Hui Autonomous Region, The School of Basic Medicine, Department of Anatomy, Ningxia Medical University, Yinchuan, 750004, China
| | - Wenjuan Yang
- Tongxin County Hospital, Tongxin County, Ningxia Hui Autonomous Region, Yinchuan, 751300, China
| | - Tingyuan Zhang
- People' s Hospital of Heze City, Shandong, 274015, China
| | - Kai Wu
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Key Laboratory of Reproduction and Genetic Heredity of Ningxia Hui Autonomous Region, The School of Basic Medicine, Department of Anatomy, Ningxia Medical University, Yinchuan, 750004, China
| | - Yi Qin
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Key Laboratory of Reproduction and Genetic Heredity of Ningxia Hui Autonomous Region, The School of Basic Medicine, Department of Anatomy, Ningxia Medical University, Yinchuan, 750004, China
| | - Qing Chang
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Key Laboratory of Reproduction and Genetic Heredity of Ningxia Hui Autonomous Region, The School of Basic Medicine, Department of Anatomy, Ningxia Medical University, Yinchuan, 750004, China.
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Hippocampal GABA A antagonism reverses the novel object recognition deficit in sub-chronic phencyclidine-treated rats. Behav Brain Res 2017; 342:11-18. [PMID: 29289597 DOI: 10.1016/j.bbr.2017.12.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/20/2017] [Accepted: 12/26/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND Abnormalities in prefrontal cortical and hippocampal GABAergic function are postulated to be major causes of the cognitive impairment associated with schizophrenia (CIAS). There are conflicting views on whether diminished or enhanced GABAergic activity contributes to the deficit in short-term novel object recognition (NOR) in the sub-chronic phencyclidine (scPCP) rodent model of CIAS. This study assessed the role of GABAA signaling in the medial prefrontal cortex (mPFC) and ventral hippocampus (vHPC) in NOR in saline (scSAL)- and scPCP-treated rats. METHODS The effects of local administration of a GABAA agonist (muscimol) into the vHPC or mPFC and an antagonist (bicuculline) or a GABAA/benzodiazepine partial agonist (bretazenil) into the vHPC on NOR in scSAL and scPCP-treated rats were determined. RESULTS In scSAL-treated rats, injection of muscimol into the vHPC, but not mPFC, induced a deficit in NOR. The scPCP-induced NOR deficit was significantly reversed by intra-vHPC bicuculline, while intra-vHPC bretazenil produced a non-significant trend for reversal (p = .06). scPCP treatment increased mRNA expression of GABAA γ2 in PFC and GABAA α5 and GABAA β1 in the HPC. However, GABA concentration in the PFC or HPC was not altered. CONCLUSIONS These findings indicate that the scPCP-induced NOR deficit can be rescued by reducing GABAA receptor stimulation in vHPC, indicating that increased vHPC GABAA inhibition may contribute to the scPCP-induced NOR deficit in rats. These results also indicate that excessive GABAA receptor signalling in the vHPC has a deleterious effect on NOR in normal rats.
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Liang L, Zhou H, Zhang S, Yuan J, Wu H. Effects of gut microbiota disturbance induced in early life on the expression of extrasynaptic GABA-A receptor α5 and δ subunits in the hippocampus of adult rats. Brain Res Bull 2017; 135:113-119. [DOI: 10.1016/j.brainresbull.2017.09.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 09/21/2017] [Accepted: 09/26/2017] [Indexed: 12/26/2022]
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Neural mechanisms underlying GABAergic regulation of adult hippocampal neurogenesis. Cell Tissue Res 2017; 371:33-46. [PMID: 28948349 DOI: 10.1007/s00441-017-2668-y] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 07/01/2017] [Indexed: 12/25/2022]
Abstract
Within the dentate gyrus of the adult hippocampus is the subgranular zone, which contains a neurogenic niche for radial-glia like cells, the most primitive neural stem cells in the adult brain. The quiescence of neural stem cells is maintained by tonic gamma-aminobutyric acid (GABA) released from local interneurons. Once these cells differentiate into neural progenitor cells, GABA continues to regulate their development into mature granule cells, the principal cell type of the dentate gyrus. Here, we review the role of GABA circuits, signaling, and receptors in regulating development of adult-born cells, as well as the molecular players that modulate GABA signaling. Furthermore, we review recent findings linking dysregulation of adult hippocampal neurogenesis to the altered GABAergic circuitry and signaling under various pathological conditions.
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Decreased surface expression of the δ subunit of the GABA A receptor contributes to reduced tonic inhibition in dentate granule cells in a mouse model of fragile X syndrome. Exp Neurol 2017; 297:168-178. [PMID: 28822839 DOI: 10.1016/j.expneurol.2017.08.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 07/21/2017] [Accepted: 08/15/2017] [Indexed: 11/22/2022]
Abstract
While numerous changes in the GABA system have been identified in models of Fragile X Syndrome (FXS), alterations in subunits of the GABAA receptors (GABAARs) that mediate tonic inhibition are particularly intriguing. Considering the key role of tonic inhibition in controlling neuronal excitability, reduced tonic inhibition could contribute to FXS-associated disorders such as hyperactivity, hypersensitivity, and increased seizure susceptibility. The current study has focused on the expression and function of the δ subunit of the GABAAR, a major subunit involved in tonic inhibition, in granule cells of the dentate gyrus in the Fmr1 knockout (KO) mouse model of FXS. Electrophysiological studies of dentate granule cells revealed a marked, nearly four-fold, decrease in tonic inhibition in the Fmr1 KO mice, as well as reduced effects of two δ subunit-preferring pharmacological agents, THIP and DS2, supporting the suggestion that δ subunit-containing GABAARs are compromised in the Fmr1 KO mice. Immunohistochemistry demonstrated a small but statistically significant decrease in δ subunit labeling in the molecular layer of the dentate gyrus in Fmr1 KO mice compared to wildtype (WT) littermates. The discrepancy between the large deficits in GABA-mediated tonic inhibition in granule cells in the Fmr1 KO mice and only modest reductions in immunolabeling of the δ subunit led to studies of surface expression of the δ subunit. Cross-linking experiments followed by Western blot analysis demonstrated a small, non-significant decrease in total δ subunit protein in the hippocampus of Fmr1 KO mice, but a four-fold decrease in surface expression of the δ subunit in these mice. No significant changes were observed in total or surface expression of the α4 subunit protein, a major partner of the δ subunit in the forebrain. Postembedding immunogold labeling for the δ subunit demonstrated a large, three-fold, decrease in the number of symmetric synapses with immunolabeling at perisynaptic locations in Fmr1 KO mice. While α4 immunogold particles were also reduced at perisynaptic locations in the Fmr1 KO mice, the labeling was increased at synaptic sites. Together these findings suggest that, in the dentate gyrus, altered surface expression of the δ subunit, rather than a decrease in δ subunit expression alone, could be limiting δ subunit-mediated tonic inhibition in this model of FXS. Finding ways to increase surface expression of the δ subunit of the GABAAR could be a novel approach to treatment of hyperexcitability-related alterations in FXS.
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Adult Hippocampal Neurogenesis along the Dorsoventral Axis Contributes Differentially to Environmental Enrichment Combined with Voluntary Exercise in Alleviating Chronic Inflammatory Pain in Mice. J Neurosci 2017; 37:4145-4157. [PMID: 28292830 DOI: 10.1523/jneurosci.3333-16.2017] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 02/27/2017] [Accepted: 03/02/2017] [Indexed: 11/21/2022] Open
Abstract
Cognitive behavioral therapy, such as environmental enrichment combined with voluntary exercise (EE-VEx), is under active investigation as an adjunct to pharmaceutical treatment for chronic pain. However, the effectiveness and underlying mechanisms of EE-VEx remain unclear. In mice with intraplantar injection of complete Freund's adjuvant, our results revealed that EE-VEx alleviated perceptual, affective, and cognitive dimensions of chronic inflammatory pain. These effects of EE-VEx on chronic pain were contingent on the occurrence of adult neurogenesis in the dentate gyrus in a functionally dissociated manner along the dorsoventral axis: neurogenesis in the ventral dentate gyrus participated in alleviating perceptual and affective components of chronic pain by EE-VEx, whereas neurogenesis in the dorsal dentate gyrus was involved in EE-VEx's cognitive-enhancing effects. Chronic inflammatory pain was accompanied by decreased levels of brain-derived neurotrophic factor (BDNF) in the dentate gyrus, which were reversed by EE-VEx. Overexpression of BDNF in the dentate gyrus mimicked the effects of EE-VEx. Our results demonstrate distinct contribution of adult hippocampal neurogenesis along the dorsoventral axis to EE-VEx's beneficial effects on different dimensions of chronic pain.SIGNIFICANCE STATEMENT Environmental enrichment combined with voluntary exercise (EE-VEx) is under active investigation as an adjunct to pharmaceutical treatment for chronic pain, but its effectiveness and underlying mechanisms remain unclear. In a mouse model of inflammatory pain, the present study demonstrates that the beneficial effects of EE-VEx on chronic pain depend on adult neurogenesis with a dorsoventral dissociation along the hippocampal axis. Adult neurogenesis in the ventral dentate gyrus participates in alleviating perceptual and affective components of chronic pain by EE-VEx, whereas that in the dorsal pole is involved in EE-VEx's cognitive-enhancing effects in chronic pain.
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Locci A, Porcu P, Talani G, Santoru F, Berretti R, Giunti E, Licheri V, Sanna E, Concas A. Neonatal estradiol exposure to female rats changes GABA A receptor expression and function, and spatial learning during adulthood. Horm Behav 2017; 87:35-46. [PMID: 27769760 DOI: 10.1016/j.yhbeh.2016.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 10/04/2016] [Accepted: 10/14/2016] [Indexed: 12/27/2022]
Abstract
Exposure of female rats to estradiol during the perinatal period has profound effects on GABAergic neurotransmission that are crucial to establish sexually dimorphic brain characteristics. We previously showed that neonatal β-estradiol 3-benzoate (EB) treatment decreases brain concentrations of the neurosteroid allopregnanolone, a potent positive modulator of extrasynaptic GABAA receptors (GABAAR). We thus evaluated whether neonatal EB treatment affects GABAAR expression and function in the hippocampus of adult female rats. Neonatal EB administration increased the expression of extrasynaptic α4/δ subunit-containing GABAARs and the modulatory action of THIP on tonic currents mediated by these receptors. The same treatment decreased the expression of synaptic α1/α4/γ2 subunit-containing receptors, as well as phasic currents. These effects of neonatal EB treatment are not related to ambient allopregnanolone concentrations per se, given that vehicle-treated rats in diestrus, which have opposite neurosteroid levels than EB-treated rats, show similar changes in GABAARs. Rather, these changes may represent a compensatory mechanism to counteract the long-term reduction in allopregnanolone concentrations, induced by neonatal EB. Given that both α4/δ receptors and allopregnanolone are involved in memory consolidation, we evaluated whether neonatal EB treatment alters performance in the Morris water maze test during adulthood. Neonatal EB treatment decreased the latency and the cumulative search error to reach the platform, as well as thigmotaxis, suggesting improved learning, and also enhanced memory performance during the probe trial. These enduring changes in GABAAR plasticity may be relevant for the regulation of neuronal excitability in the hippocampus and for the etiology of psychiatric disorders that originate in development and show sex differences.
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Affiliation(s)
- Andrea Locci
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Patrizia Porcu
- Neuroscience Institute, National Research Council of Italy (CNR), Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Giuseppe Talani
- Neuroscience Institute, National Research Council of Italy (CNR), Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Francesca Santoru
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Roberta Berretti
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Elisa Giunti
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Valentina Licheri
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Enrico Sanna
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy; Neuroscience Institute, National Research Council of Italy (CNR), Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Alessandra Concas
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy; Neuroscience Institute, National Research Council of Italy (CNR), Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy.
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Whissell PD, Avramescu S, Wang DS, Orser BA. δGABAA Receptors Are Necessary for Synaptic Plasticity in the Hippocampus. Anesth Analg 2016; 123:1247-1252. [DOI: 10.1213/ane.0000000000001373] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Ng T, Hor CHH, Chew B, Zhao J, Zhong Z, Ryu JR, Goh ELK. Neuropilin 2 Signaling Is Involved in Cell Positioning of Adult-born Neurons through Glycogen Synthase Kinase-3β (GSK3β). J Biol Chem 2016; 291:25088-25095. [PMID: 27687730 DOI: 10.1074/jbc.m116.755215] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 09/27/2016] [Indexed: 11/06/2022] Open
Abstract
Proper positioning of neurons is fundamental for brain functions. However, little is known on how adult-born neurons generated in the hilar side of hippocampal dentate gyrus migrate into the granular cell layer. Because class 3 Semaphorins (Sema3) are involved in dendritic growth of these newborn neurons, we examined whether they are essential for cell positioning. We disrupted Sema3 signaling by silencing neuropilin 1 (NRP1) or 2 (NRP2), the main receptors for Sema3A and Sema3F, in neural progenitors of adult mouse dentate gyrus. Silencing of NRP2, but not NRP1, affected cell positioning of adult newborn neurons. Glycogen synthase kinase-3β (GSK3β) knockdown phenocopied this NRP2 silencing-mediated cell positioning defect, but did not affect dendritic growth. Furthermore, GSK3β is activated upon stimulation with Sema3F, and GSK3β overexpression rescued the cell positioning phenotypes seen in NRP2-deficient neurons. These results point to a new role for NRP2 in the positioning of neurons during adult hippocampal neurogenesis, acting via the GSK3β signaling pathway.
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Affiliation(s)
- Teclise Ng
- From the Programme in Neuroscience and Behavioral Disorder and
| | - Catherine H H Hor
- Neuroscience Academic Clinical Programme, Duke-NUS Medical School, Singapore 169857, Singapore.,the Department of Research, National Neuroscience Institute, Singapore 308433, Singapore
| | - Benjamin Chew
- From the Programme in Neuroscience and Behavioral Disorder and
| | - Jing Zhao
- GlaxoSmithKline (China) R&D Co., Ltd., Shanghai 201203, China
| | - Zhong Zhong
- GlaxoSmithKline (China) R&D Co., Ltd., Shanghai 201203, China
| | - Jae Ryun Ryu
- From the Programme in Neuroscience and Behavioral Disorder and
| | - Eyleen L K Goh
- From the Programme in Neuroscience and Behavioral Disorder and .,Neuroscience Academic Clinical Programme, Duke-NUS Medical School, Singapore 169857, Singapore.,the Department of Research, National Neuroscience Institute, Singapore 308433, Singapore.,the Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore, and.,the KK Research Center, KK Women's and Children's Hospital, Singapore 229899, Singapore
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29
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Lee V, MacKenzie G, Hooper A, Maguire J. Reduced tonic inhibition in the dentate gyrus contributes to chronic stress-induced impairments in learning and memory. Hippocampus 2016; 26:1276-1290. [PMID: 27163381 DOI: 10.1002/hipo.22604] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 04/30/2016] [Accepted: 05/06/2016] [Indexed: 11/11/2022]
Abstract
It is well established that stress impacts the underlying processes of learning and memory. The effects of stress on memory are thought to involve, at least in part, effects on the hippocampus, which is particularly vulnerable to stress. Chronic stress induces hippocampal alterations, including but not limited to dendritic atrophy and decreased neurogenesis, which are thought to contribute to chronic stress-induced hippocampal dysfunction and deficits in learning and memory. Changes in synaptic transmission, including changes in GABAergic inhibition, have been documented following chronic stress. Recently, our laboratory demonstrated shifts in EGABA in CA1 pyramidal neurons following chronic stress, compromising GABAergic transmission and increasing excitability of these neurons. Interestingly, here we demonstrate that these alterations are unique to CA1 pyramidal neurons, since we do not observe shifts in EGABA following chronic stress in dentate gyrus granule cells. Following chronic stress, there is a decrease in the expression of the GABAA receptor (GABAA R) δ subunit and tonic GABAergic inhibition in dentate gyrus granule cells, whereas there is an increase in the phasic component of GABAergic inhibition, evident by an increase in the peak amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). Given the numerous changes observed in the hippocampus following stress, it is difficult to pinpoint the pertinent contributing pathophysiological factors. Here we directly assess the impact of a reduction in tonic GABAergic inhibition of dentate gyrus granule cells on learning and memory using a mouse model with a decrease in GABAA R δ subunit expression specifically in dentate gyrus granule cells (Gabrd/Pomc mice). Reduced GABAA R δ subunit expression and function in dentate gyrus granule cells is sufficient to induce deficits in learning and memory. Collectively, these findings suggest that the reduction in GABAA R δ subunit-mediated tonic inhibition in dentate gyrus granule cells contributes, at least in part, to deficits in learning and memory associated with chronic stress. These findings have significant implications regarding the pathophysiological mechanisms underlying impairments in learning and memory associated with stress and suggest a role for GABAA R δ subunit containing receptors in dentate gyrus granule cells. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Vallent Lee
- Medical Scientist Training Program and Graduate Program in Neuroscience, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA, United States
| | - Georgina MacKenzie
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Andrew Hooper
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
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30
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Abrous DN, Wojtowicz JM. Interaction between Neurogenesis and Hippocampal Memory System: New Vistas. Cold Spring Harb Perspect Biol 2015; 7:7/6/a018952. [PMID: 26032718 DOI: 10.1101/cshperspect.a018952] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
During the last decade, the questions on the functionality of adult neurogenesis have changed their emphasis from if to how the adult-born neurons participate in a variety of memory processes. The emerging answers are complex because we are overwhelmed by a variety of behavioral tasks that apparently require new neurons to be performed optimally. With few exceptions, the hippocampal memory system seems to use the newly generated neurons for multiple roles. Adult neurogenesis has given the dentate gyrus new capabilities not previously thought possible within the scope of traditional synaptic plasticity. Looking at these new developments from the perspective of past discoveries, the science of adult neurogenesis has emerged from its initial phase of being, first, a surprising oddity and, later, exciting possibility, to the present state of being an integral part of mainstream neuroscience. The answers to many remaining questions regarding adult neurogenesis will come along only with our growing understanding of the functionality of the brain as a whole. This, in turn, will require integration of multiple levels of organization from molecules and cells to circuits and systems, ultimately resulting in comprehension of behavioral outcomes.
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Affiliation(s)
- Djoher Nora Abrous
- Inserm U862, Bordeaux-F33077, France Université de Bordeaux, Bordeaux-F33077, France
| | - Jan Martin Wojtowicz
- Department of Physiology, University of Toronto, Medical Sciences Building, Toronto, Ontario M5S 1A8, Canada
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31
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Subramaniyan S, Hajali V, Scherf T, Sase SJ, Sialana FJ, Gröger M, Bennett KL, Pollak A, Li L, Korz V, Lubec G. Hippocampal receptor complexes paralleling LTP reinforcement in the spatial memory holeboard test in the rat. Behav Brain Res 2015; 283:162-74. [PMID: 25639541 DOI: 10.1016/j.bbr.2015.01.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 01/18/2015] [Accepted: 01/21/2015] [Indexed: 12/28/2022]
Abstract
The current study was designed to examine learning-induced transformation of early-LTP into late-LTP. Recording electrodes were implanted into the dentate gyrus of the hippocampus in male rats and early-LTP was induced by weak tetanic stimulation of the medial perforant path. Dorsal right hippocampi were removed, membrane proteins were extracted, separated by blue-native gel electrophoresis with subsequent immunoblotting using brain receptor antibodies. Spatial training resulted into reinforcement of LTP and the reinforced LTP was persistent for 6h. Receptor complex levels containing GluN1 and GluN2A of NMDARs, GluA1 and GluA2 of AMPARs, nAchα7R and the D(1A) dopamine receptor were significantly-elevated in rat hippocampi of animals underwent spatial learning, whilst levels of GluA3 and 5-HT1A receptor containing complexes were significantly reduced. Evidence for complex formation between GluN1 and D(1A) dopamine receptor was provided by antibody shift assay, co-immunoprecipitation and mass spectrometric analysis. Thus our results propose that behavioural stimuli like spatial learning reinforce early LTP into late LTP and this reinforced LTP is accompanied by changes in certain receptor levels in the membrane fraction of the rat hippocampus.
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Affiliation(s)
| | - Vahid Hajali
- Institute of Biology, Otto von Guericke University Magdeburg, 39120 Magdeburg, Germany
| | - Thomas Scherf
- Institute of Biology, Otto von Guericke University Magdeburg, 39120 Magdeburg, Germany
| | - Sunetra Jitkar Sase
- Department of Paediatrics, Medizinische Universität Wien, Währinger Gürtel 18A, 1090 Wien
| | - Fernando J Sialana
- Department of Paediatrics, Medizinische Universität Wien, Währinger Gürtel 18A, 1090 Wien
| | - Marion Gröger
- Core facilities, Core Facility Imaging, Medizinische Universität Wien, Anna Spiegel Forschungsgebäude, 1090 Vienna, Austria
| | - Keiryn L Bennett
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT25.3 and 1090 Vienna, Austria
| | - Arnold Pollak
- Department of Paediatrics, Medizinische Universität Wien, Währinger Gürtel 18A, 1090 Wien
| | - Lin Li
- Department of Paediatrics, Medizinische Universität Wien, Währinger Gürtel 18A, 1090 Wien
| | - Volker Korz
- Institute of Biology, Otto von Guericke University Magdeburg, 39120 Magdeburg, Germany.
| | - Gert Lubec
- Department of Paediatrics, Medizinische Universität Wien, Währinger Gürtel 18A, 1090 Wien.
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Fritschy JM. Significance of GABAA Receptor Heterogeneity. DIVERSITY AND FUNCTIONS OF GABA RECEPTORS: A TRIBUTE TO HANNS MÖHLER, PART B 2015; 73:13-39. [DOI: 10.1016/bs.apha.2014.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Sabaliauskas N, Shen H, Molla J, Gong QH, Kuver A, Aoki C, Smith SS. Neurosteroid effects at α4βδ GABAA receptors alter spatial learning and synaptic plasticity in CA1 hippocampus across the estrous cycle of the mouse. Brain Res 2014; 1621:170-86. [PMID: 25542386 DOI: 10.1016/j.brainres.2014.12.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 12/08/2014] [Accepted: 12/10/2014] [Indexed: 11/26/2022]
Abstract
Fluctuations in circulating levels of ovarian hormones have been shown to regulate cognition (Sherwin and Grigorova, 2011. Fertil. Steril. 96, 399-403; Shumaker et al., 2004. JAMA. 291, 2947-2958), but increases in estradiol on the day of proestrus yield diverse outcomes: In vivo induction of long-term potentiation (LTP), a model of learning, is reduced in the morning, but optimal in the afternoon (Warren et al., 1995. Brain Res. 703, 26-30). The mechanism underlying this discrepancy is not known. Here, we show that impairments in both CA1 hippocampal LTP and spatial learning observed on the morning of proestrus are due to increased dendritic expression of α4βδ GABAA receptors (GABARs) on CA1 pyramidal cells, as assessed by electron microscopic (EM) techniques, compared with estrus and diestrus. LTP induction and spatial learning were robust, however, when assessed on the morning of proestrus in α4-/- mice, implicating these receptors in mediating impaired plasticity. Although α4βδ expression remained elevated on the afternoon of proestrus, increases in 3α-OH-THP (3α-OH-5α-pregnan-20-one) decreased inhibition by reducing outward current through α4βδ GABARs (Shen et al., 2007. Nat. Neurosci. 10, 469-477), in contrast to the usual effect of this steroid to enhance inhibition. Proestrous levels of 3α-OH-THP reversed the deficits in LTP and spatial learning, an effect prevented by the inactive metabolite 3β-OH-THP (10 mg/kg, i.p.), which antagonizes actions of 3α-OH-THP. In contrast, administration of 3α-OH-THP (10 mg/kg, i.p.) on the morning of proestrus improved spatial learning scores 150-300%. These findings suggest that cyclic fluctuations in ovarian steroids can induce changes in cognition via α4βδ GABARs that are dependent upon 3α-OH-THP. This article is part of a Special Issue entitled SI: Brain and Memory.
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Affiliation(s)
- Nicole Sabaliauskas
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, 450 Clarkson Ave., Brooklyn, NY 11203, USA; Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA
| | - Hui Shen
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, 450 Clarkson Ave., Brooklyn, NY 11203, USA; School of Biomedical Engineering, Tianjin Medical University, No. 22 Qixiangtai Road, Heping District, Tianjin 300070, China
| | - Jonela Molla
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, 450 Clarkson Ave., Brooklyn, NY 11203, USA
| | - Qi Hua Gong
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, 450 Clarkson Ave., Brooklyn, NY 11203, USA
| | - Aarti Kuver
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, 450 Clarkson Ave., Brooklyn, NY 11203, USA
| | - Chiye Aoki
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA
| | - Sheryl S Smith
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, 450 Clarkson Ave., Brooklyn, NY 11203, USA; The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, USA.
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Altered expression of δGABAA receptors in health and disease. Neuropharmacology 2014; 88:24-35. [PMID: 25128850 DOI: 10.1016/j.neuropharm.2014.08.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 07/28/2014] [Accepted: 08/03/2014] [Indexed: 01/08/2023]
Abstract
γ-Aminobutyric acid type A receptors that contain the δ subunit (δGABAA receptors) are expressed in multiple types of neurons throughout the central nervous system, where they generate a tonic conductance that shapes neuronal excitability and synaptic plasticity. These receptors regulate a variety of important behavioral functions, including memory, nociception and anxiety, and may also modulate neurogenesis. Given their functional significance, δGABAA receptors are considered to be novel therapeutic targets for the treatment of memory dysfunction, pain, insomnia and mood disorders. These receptors are highly responsive to sedative-hypnotic drugs, general anesthetics and neuroactive steroids. A further remarkable feature of δGABAA receptors is that their expression levels are highly dynamic and fluctuate substantially during development and in response to physiological changes including stress and the reproductive cycle. Furthermore, the expression of these receptors varies in pathological conditions such as alcoholism, fragile X syndrome, epilepsy, depression, schizophrenia, mood disorders and traumatic brain injury. Such fluctuations in receptor expression have significant consequences for behavior and may alter responsiveness to therapeutic drugs. This review considers the alterations in the expression of δGABAA receptors associated with various states of health and disease and the implications of these changes.
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Merkley CM, Jian C, Mosa A, Tan YF, Wojtowicz JM. Homeostatic regulation of adult hippocampal neurogenesis in aging rats: long-term effects of early exercise. Front Neurosci 2014; 8:174. [PMID: 25071426 PMCID: PMC4077125 DOI: 10.3389/fnins.2014.00174] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/05/2014] [Indexed: 01/05/2023] Open
Abstract
Adult neurogenesis is highly responsive to environmental and physiological factors. The majority of studies to date have examined short-term consequences of enhancing or blocking neurogenesis but long-term changes remain less well understood. Current evidence for age-related declines in neurogenesis warrant further investigation into these long-term changes. In this report we address the hypothesis that early life experience, such as a period of voluntary running in juvenile rats, can alter properties of adult neurogenesis for the remainder of the animal's life. The results indicate that the number of proliferating and differentiating neuronal precursors is not altered in runners beyond the initial weeks post-running, suggesting homeostatic regulation of these processes. However, the rate of neuronal maturation and survival during a 4 week period after cell division was enhanced up to 11 months of age (the end of the study period). This study is the first to show that a transient period of physical activity at a young age promotes changes in neurogenesis that persist over the long-term, which is important for our understanding of the modulation of neurogenesis by exercise with age. Functional integration of adult-born neurons within the hippocampus that resist homeostatic regulation with aging, rather than the absolute number of adult-born neurons, may be an essential feature of adult neurogenesis that promotes the maintenance of neural plasticity in old age.
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Affiliation(s)
- Christina M Merkley
- Department of Physiology, Faculty of Medicine, University of Toronto Toronto, ON, Canada
| | - Charles Jian
- Department of Physiology, Faculty of Medicine, University of Toronto Toronto, ON, Canada
| | - Adam Mosa
- Department of Physiology, Faculty of Medicine, University of Toronto Toronto, ON, Canada
| | - Yao-Fang Tan
- Department of Physiology, Faculty of Medicine, University of Toronto Toronto, ON, Canada
| | - J Martin Wojtowicz
- Department of Physiology, Faculty of Medicine, University of Toronto Toronto, ON, Canada
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Dihydromyricetin prevents fetal alcohol exposure-induced behavioral and physiological deficits: the roles of GABAA receptors in adolescence. Neurochem Res 2014; 39:1147-61. [PMID: 24676702 DOI: 10.1007/s11064-014-1291-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/18/2014] [Accepted: 03/20/2014] [Indexed: 10/25/2022]
Abstract
Fetal alcohol exposure (FAE) can lead to a variety of behavioral and physiological disturbances later in life. Understanding how alcohol (ethanol, EtOH) affects fetal brain development is essential to guide the development of better therapeutics for FAE. One of EtOH's many pharmacological targets is the γ-aminobutyric acid type A receptor (GABAAR), which plays a prominent role in early brain development. Acute EtOH potentiates inhibitory currents carried by certain GABAAR subtypes, whereas chronic EtOH leads to persistent alterations in GABAAR subunit composition, localization and function. We recently introduced a flavonoid compound, dihydromyricetin (DHM), which selectively antagonizes EtOH's intoxicating effects in vivo and in vitro at enhancing GABAAR function as a candidate for alcohol abuse pharmacotherapy. Here, we studied the effect of FAE on physiology, behavior and GABAAR function of early adolescent rats and tested the utility of DHM as a preventative treatment for FAE-induced disturbances. Gavage administration of EtOH (1.5, 2.5, or 5.0 g/kg) to rat dams on day 5, 8, 10, 12, and 15 of pregnancy dose-dependently reduced female/male offspring ratios (largely through decreased numbers of female offspring) and offspring body weights. FAE (2.5 g/kg) rats tested on postnatal days (P) 25-32 also exhibited increased anxiety and reduced pentylenetetrazol (PTZ)-induced seizure threshold. Patch-clamp recordings from dentate gyrus granule cells (DGCs) in hippocampal slices from FAE (2.5 g/kg) rats at P25-35 revealed reduced sensitivity of GABAergic miniature inhibitory postsynaptic currents (mIPSCs) and tonic current (Itonic) to potentiation by zolpidem (0.3 μM). Interestingly, potentiation of mIPSCs by gaboxadol increased, while potentiation of Itonic decreased in DGCs from FAE rats. Co-administration of EtOH (1.5 or 2.5 g/kg) with DHM (1.0 mg/kg) in pregnant dams prevented all of the behavioral, physiological, and pharmacological alterations observed in FAE offspring. DHM administration alone in pregnant rats had no adverse effect on litter size, progeny weight, anxiety level, PTZ seizure threshold, or DGC GABAAR function. Our results indicate that FAE induces long-lasting alterations in physiology, behavior, and hippocampal GABAAR function and that these deficits are prevented by DHM co-treatment of EtOH-exposed dams. The absence of adverse side effects and the ability of DHM to prevent FAE consequences suggest that DHM is an attractive candidate for development as a treatment for prevention of fetal alcohol spectrum disorders.
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Fritschy JM, Panzanelli P. GABAAreceptors and plasticity of inhibitory neurotransmission in the central nervous system. Eur J Neurosci 2014; 39:1845-65. [DOI: 10.1111/ejn.12534] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 01/29/2014] [Accepted: 01/29/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology; University of Zurich; Winterthurerstrasse 190 8057 Zurich Switzerland
- Neuroscience Center Zurich; University of Zurich and ETH; Zurich Switzerland
| | - Patrizia Panzanelli
- Department of Neuroscience Rita Levi Montalcini; University of Turin; Turin Italy
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Whissell PD, Eng D, Lecker I, Martin LJ, Wang DS, Orser BA. Acutely increasing δGABA(A) receptor activity impairs memory and inhibits synaptic plasticity in the hippocampus. Front Neural Circuits 2013; 7:146. [PMID: 24062648 PMCID: PMC3775149 DOI: 10.3389/fncir.2013.00146] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/29/2013] [Indexed: 12/03/2022] Open
Abstract
Extrasynaptic γ-aminobutyric acid type A (GABAA) receptors that contain the δ subunit (δGABAA receptors) are expressed in several brain regions including the dentate gyrus (DG) and CA1 subfields of the hippocampus. Drugs that increase δGABAA receptor activity have been proposed as treatments for a variety of disorders including insomnia, epilepsy and chronic pain. Also, long-term pretreatment with the δGABAA receptor–preferring agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) enhances discrimination memory and increases neurogenesis in the DG. Despite the potential therapeutic benefits of such treatments, the effects of acutely increasing δGABAA receptor activity on memory behaviors remain unknown. Here, we studied the effects of THIP (4 mg/kg, i.p.) on memory performance in wild-type (WT) and δGABAA receptor null mutant (Gabrd−/−) mice. Additionally, the effects of THIP on long-term potentiation (LTP), a molecular correlate of memory, were studied within the DG and CA1 subfields of the hippocampus using electrophysiological recordings of field potentials in hippocampal slices. The results showed that THIP impaired performance in the Morris water maze, contextual fear conditioning and object recognition tasks in WT mice but not Gabrd−/− mice. Furthermore, THIP inhibited LTP in hippocampal slices from WT but not Gabrd−/− mice, an effect that was blocked by GABAA receptor antagonist bicuculline. Thus, acutely increasing δGABAA receptor activity impairs memory behaviors and inhibits synaptic plasticity. These results have important implications for the development of therapies aimed at increasing δGABAA receptor activity.
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Affiliation(s)
- Paul D Whissell
- Institute of Medical Science, University of Toronto Toronto, ON, Canada
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Smith SS. α4βδ GABAA receptors and tonic inhibitory current during adolescence: effects on mood and synaptic plasticity. Front Neural Circuits 2013; 7:135. [PMID: 24027497 PMCID: PMC3759753 DOI: 10.3389/fncir.2013.00135] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 07/28/2013] [Indexed: 11/13/2022] Open
Abstract
The onset of puberty is associated with alterations in mood as well as changes in cognitive function, which can be more pronounced in females. Puberty onset in female mice is associated with increased expression of α4βδ γ-amino-butyric acid-A (GABAA) receptors (GABARs) in CA1 hippocampus. These receptors, which normally have low expression in this central nervous system (CNS) site, emerge along the apical dendrites as well as on the dendritic spines of pyramidal neurons, adjacent to excitatory synapses where they underlie a tonic inhibition that shunts excitatory current and impairs activation of N-methyl-D-aspartate (NMDA) receptors, the trigger for synaptic plasticity. As would be expected, α4βδ expression at puberty also prevents long-term potentiation (LTP), an in vitro model of learning which is a function of network activity, induced by theta burst stimulation of the Schaffer collaterals to the CA1 hippocampus. The expression of these receptors also impairs spatial learning in a hippocampal-dependent task. These impairments are not seen in δ knock-out (-/-) mice, implicating α4βδ GABARs. α4βδ GABARs are also a sensitive target for steroids such as THP ([allo]pregnanolone or 3α-OH-5α[β]-pregnan-20-one), which are dependent upon the polarity of GABAergic current. It is well-known that THP can increase depolarizing current gated by α4βδ GABARs, but more recent data suggest that THP can reduce hyperpolarizing current by accelerating receptor desensitization. At puberty, THP reduces the hyperpolarizing GABAergic current, which removes the shunting inhibition that impairs synaptic plasticity and learning at this time. However, THP, a stress steroid, also increases anxiety, via its action at α4βδ GABARs because it is not seen in δ(-/-) mice. These findings will be discussed as well as their relevance to changes in mood and cognition at puberty, which can be a critical period for certain types of learning and when anxiety disorders and mood swings can emerge.
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Affiliation(s)
- Sheryl S Smith
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center Brooklyn, NY 11203, USA.
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