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Cover KK, Mathur BN. Axo-axonic synapses: Diversity in neural circuit function. J Comp Neurol 2021; 529:2391-2401. [PMID: 33314077 PMCID: PMC8053672 DOI: 10.1002/cne.25087] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/20/2022]
Abstract
The chemical synapse is the principal form of contact between neurons of the central nervous system. These synapses are typically configured as presynaptic axon terminations onto postsynaptic dendrites or somata, giving rise to axo-dendritic and axo-somatic synapses, respectively. Beyond these common synapse configurations are less-studied, non-canonical synapse types that are prevalent throughout the brain and significantly contribute to neural circuit function. Among these are the axo-axonic synapses, which consist of an axon terminating on another axon or axon terminal. Here, we review evidence for axo-axonic synapse contributions to neural signaling in the mammalian nervous system and survey functional neural circuit motifs enabled by these synapses. We also detail how recent advances in microscopy, transgenics, and biological sensors may be used to identify and functionally assay axo-axonic synapses.
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Affiliation(s)
- Kara K. Cover
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD USA 21201
| | - Brian N. Mathur
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD USA 21201
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2
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Li WG, Wu YJ, Gu X, Fan HR, Wang Q, Zhu JJ, Yi X, Wang Q, Jiang Q, Li Y, Yuan TF, Xu H, Lu J, Xu NJ, Zhu MX, Xu TL. Input associativity underlies fear memory renewal. Natl Sci Rev 2021; 8:nwab004. [PMID: 34691732 PMCID: PMC8433092 DOI: 10.1093/nsr/nwab004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 12/09/2020] [Accepted: 12/29/2020] [Indexed: 11/13/2022] Open
Abstract
Abstract
Synaptic associativity, a feature of Hebbian plasticity wherein coactivation of two inputs onto the same neuron produces synergistic actions on postsynaptic activity, is a primary cellular correlate of associative learning. However, whether and how synaptic associativity are implemented into context-dependent relapse of extinguished memory (i.e. fear renewal) is unknown. Here, using an auditory fear conditioning paradigm in mice, we show that fear renewal is determined by the associativity between convergent inputs from the auditory cortex (ACx) and ventral hippocampus (vHPC) onto the lateral amygdala (LA) that reactivate ensembles engaged during learning. Fear renewal enhances synaptic strengths of both ACx to LA and the previously unknown vHPC to LA monosynaptic inputs. While inactivating either of the afferents abolishes fear renewal, optogenetic activation of their input associativity in the LA recapitulates fear renewal. Thus, input associativity underlies fear memory renewal.
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Affiliation(s)
- Wei-Guang Li
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Yan-Jiao Wu
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Xue Gu
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Hui-Ran Fan
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Qi Wang
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Jia-Jie Zhu
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Xin Yi
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Qin Wang
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Qin Jiang
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Ying Li
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Ti-Fei Yuan
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 201108, China
| | - Han Xu
- Center for Neuroscience and Department of Neurology of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Jiangteng Lu
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Nan-Jie Xu
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
| | - Michael Xi Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Tian-Le Xu
- Center for Brain Science of Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 20025, China
- Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai 201210, China
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3
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Sun W, Yuill MB. Role of the GABA a and GABA b receptors of the central nucleus of the amygdala in compulsive cocaine-seeking behavior in male rats. Psychopharmacology (Berl) 2020; 237:3759-3771. [PMID: 32875348 PMCID: PMC7686280 DOI: 10.1007/s00213-020-05653-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 08/24/2020] [Indexed: 01/28/2023]
Abstract
RATIONALE Compulsive cocaine use, defined as the continued use despite the dire consequences, is a hallmark of cocaine addiction. Thus, understanding the brain mechanism regulating the compulsive cocaine-seeking and cocaine-taking behaviors is essential to understand cocaine addiction and the key to identification of the molecular targets for the development of medications against this condition. OBJECTIVE This study aimed to determine how the GABAa and GABAb receptors of the central nucleus of the amygdala (CeA) regulate the compulsive cocaine-seeking behavior. METHODS Male Wistar outbred rats were trained to self-administer intravenous cocaine (0.4 mg/kg/infusion) under a chained schedule. The compulsive cocaine-seeking behavior was measured as the cocaine-seeking behavior in the face of footshock punishment. The role of the GABA receptors of CeA in the regulation of such behavior was determined by measuring the dose-dependent effects of the GABAa agonist muscimol or the GABAb agonist baclofen bilaterally microinjected into the CeA on the punished cocaine-seeking behavior. RESULTS The cocaine-seeking behavior was inhibited by footshock punishment in an intensity-dependent manner. Both muscimol and baclofen dose-dependently increased the punished cocaine-seeking behavior. However, the potency of muscimol but not baclofen was negatively correlated with the effects of punishment. CONCLUSION These data indicate that the CeA GABAa receptors play a key role in the regulation of the compulsive cocaine-seeking behavior and suggest that an increase in the function of the GABAa receptors possibly induced by cocaine or genetic factors may be an important mechanism involved in the development of or vulnerability to the compulsive cocaine use and addiction.
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Affiliation(s)
- WenLin Sun
- Department of Pharmacology, University of Tennessee Health Science Center, 71 S. Manassas, Memphis, TN, 38103, USA.
| | - Matt B Yuill
- Department of Pharmacology, University of Tennessee Health Science Center, 71 S. Manassas, Memphis, TN, 38103, USA
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4
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Pan HQ, Zhang WH, Liao CZ, He Y, Xiao ZM, Qin X, Liu WZ, Wang N, Zou JX, Liu XX, Pan BX. Chronic Stress Oppositely Regulates Tonic Inhibition in Thy1-Expressing and Non-expressing Neurons in Amygdala. Front Neurosci 2020; 14:299. [PMID: 32362809 PMCID: PMC7180173 DOI: 10.3389/fnins.2020.00299] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 03/16/2020] [Indexed: 12/13/2022] Open
Abstract
Chronic or prolonged exposure to stress ranks among the most important socioenvironmental factors contributing to the development of neuropsychiatric diseases, a process generally associated with loss of inhibitory tone in amygdala. Recent studies have identified distinct neuronal circuits within the basolateral amygdala (BLA) engaged in different emotional processes. However, the potential circuit involved in stress-induced dysregulation of inhibitory tones in BLA remains elusive. Here, a transgenic mouse model expressing yellow fluorescent protein under control of the Thy1 promoter was used to differentiate subpopulations of projection neurons (PNs) within the BLA. We observed that the tonic inhibition in amygdala neurons expressing and not expressing Thy1 (Thy1+/-) was oppositely regulated by chronic social defeat stress (CSDS). In unstressed control mice, the tonic inhibitory currents were significantly stronger in Thy1- PNs than their Thy1+ counterparts. CSDS markedly reduced the currents in Thy1- projection neurons (PNs), but increased that in Thy1+ ones. By contrast, CSDS failed to affect both the phasic A-type γ-aminobutyric acid receptor (GABAAR) currents and GABABR currents in these two PN populations. Moreover, chronic corticosterone administration was sufficient to mimic the effect of CSDS on the tonic inhibition of Thy1+ and Thy1- PNs. As a consequence, the suppression of tonic GABAAR currents on the excitability of Thy1- PNs was weakened by CSDS, but enhanced in Thy1+ PNs. The differential regulation of chronic stress on the tonic inhibition in Thy1+ and Thy1- neurons may orchestrate cell-specific adaptation of amygdala neurons to chronic stress.
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Affiliation(s)
- Han-Qing Pan
- Department of Biological Science, School of Life Sciences, Nanchang University, Nanchang, China.,Laboratory of Fear and Anxiety Disorders, Institutes of Life Science, Nanchang University, Nanchang, China
| | - Wen-Hua Zhang
- Department of Biological Science, School of Life Sciences, Nanchang University, Nanchang, China.,Laboratory of Fear and Anxiety Disorders, Institutes of Life Science, Nanchang University, Nanchang, China
| | - Cai-Zhi Liao
- Department of Biological Science, School of Life Sciences, Nanchang University, Nanchang, China.,Laboratory of Fear and Anxiety Disorders, Institutes of Life Science, Nanchang University, Nanchang, China
| | - Ye He
- Center for Medical Experiments, Nanchang University, Nanchang, China
| | - Zhi-Ming Xiao
- Laboratory of Fear and Anxiety Disorders, Institutes of Life Science, Nanchang University, Nanchang, China
| | - Xia Qin
- Department of Biological Science, School of Life Sciences, Nanchang University, Nanchang, China.,Laboratory of Fear and Anxiety Disorders, Institutes of Life Science, Nanchang University, Nanchang, China
| | - Wei-Zhu Liu
- Department of Biological Science, School of Life Sciences, Nanchang University, Nanchang, China.,Laboratory of Fear and Anxiety Disorders, Institutes of Life Science, Nanchang University, Nanchang, China
| | - Na Wang
- Department of Physiology, Mudanjiang Medical University, Mudanjiang, China
| | - Jia-Xin Zou
- Department of Biological Science, School of Life Sciences, Nanchang University, Nanchang, China.,Laboratory of Fear and Anxiety Disorders, Institutes of Life Science, Nanchang University, Nanchang, China
| | - Xiao-Xuan Liu
- Department of Biological Science, School of Life Sciences, Nanchang University, Nanchang, China.,Laboratory of Fear and Anxiety Disorders, Institutes of Life Science, Nanchang University, Nanchang, China
| | - Bing-Xing Pan
- Department of Biological Science, School of Life Sciences, Nanchang University, Nanchang, China.,Laboratory of Fear and Anxiety Disorders, Institutes of Life Science, Nanchang University, Nanchang, China
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5
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Han RW, Liu ZP, Lin HR, Tian AW, Xiao YF, Wei J, Deng KY, Pan BX, Xin HB. Role of lateral amygdala calstabin2 in regulation of fear memory. Mol Brain 2020; 13:35. [PMID: 32151269 PMCID: PMC7063811 DOI: 10.1186/s13041-020-00576-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 03/02/2020] [Indexed: 01/28/2023] Open
Abstract
Calstabin2, also named FK506 binding protein 12.6 (FKBP12.6), is a subunit of ryanodine receptor subtype 2 (RyR2) macromolecular complex, an intracellular calcium channel. Studies from our and other's lab have shown that hippocampal calstabin2 regulates spatial memory. Calstabin2 and RyR2 are widely distributed in the brain, including the amygdala, a key brain area involved in the regulation of emotion including fear. Little is known about the role of calstabin2 in fear memory. Here, we found that genetic deletion of calstabin2 impaired long-term memory in cued fear conditioning test. Knockdown calstabin2 in the lateral amygdala (LA) by viral vector also impaired long-term cued fear memory expression. Furthermore, calstabin2 knockout reduced long-term potentiation (LTP) at both cortical and thalamic inputs to the LA. In conclusion, our present data indicate that calstabin2 in the LA plays a crucial role in the regulating of emotional memory.
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Affiliation(s)
- Ren-Wen Han
- The National Engineering Research Center for Bioengineering Drugs and the Technologies, Institute of Translational Medicine, Nanchang University, Nanchang, China. .,Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, China.
| | - Zhi-Peng Liu
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, China
| | - Hong-Ru Lin
- The National Engineering Research Center for Bioengineering Drugs and the Technologies, Institute of Translational Medicine, Nanchang University, Nanchang, China
| | - Ao-Wen Tian
- The National Engineering Research Center for Bioengineering Drugs and the Technologies, Institute of Translational Medicine, Nanchang University, Nanchang, China
| | - Yun-Fei Xiao
- The National Engineering Research Center for Bioengineering Drugs and the Technologies, Institute of Translational Medicine, Nanchang University, Nanchang, China
| | - Jie Wei
- Department of Physiology, Medical College of Nanchang University, Nanchang, China
| | - Ke-Yu Deng
- The National Engineering Research Center for Bioengineering Drugs and the Technologies, Institute of Translational Medicine, Nanchang University, Nanchang, China
| | - Bing-Xing Pan
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, China.
| | - Hong-Bo Xin
- The National Engineering Research Center for Bioengineering Drugs and the Technologies, Institute of Translational Medicine, Nanchang University, Nanchang, China. .,College of Life Sciences, Nanchang University, Nanchang, China.
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6
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Crane JW, Holmes NM, Fam J, Westbrook RF, Delaney AJ. Oxytocin increases inhibitory synaptic transmission and blocks development of long-term potentiation in the lateral amygdala. J Neurophysiol 2020; 123:587-599. [DOI: 10.1152/jn.00571.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Oxytocin (OT) is a neuroactive peptide that influences the processing of fearful stimuli in the amygdala. In the central nucleus of the amygdala, the activation of OT receptors alters neural activity and ultimately suppresses the behavioral response to a fear conditioned stimulus. Receptors for OT are also found in the lateral amygdala (LA), and infusion of OT into the basolateral amygdala complex affects the formation and consolidation of fear memories. Yet, how OT receptor activation alters neurons and neural networks in the LA is unknown. In this study we used whole cell electrophysiological recordings to determine how OT-receptor activation changes synaptic transmission and synaptic plasticity in the LA of Sprague-Dawley rats. Our results demonstrate that OT-receptor activation results in a 200% increase in spontaneous inhibitory transmission in the LA that leads to the activation of presynaptic GABAB receptors. The activation of these receptors inhibits excitatory transmission in the LA, blocking long-term potentiation of cortical inputs onto LA neurons. Hence, this study provides the first demonstration that OT influences synaptic transmission and plasticity in the LA, revealing a mechanism that could explain how OT regulates the formation and consolidation of conditioned fear memories in the amygdala. NEW & NOTEWORTHY This study investigates modulation of synaptic transmission by oxytocin (OT) in the lateral amygdala (LA). We demonstrate that OT induces transient increases in spontaneous GABAergic transmission by activating interneurons in the basolateral amygdala. The resultant increase in GABA release in the LA activates presynaptic GABAB receptors on both inhibitory and excitatory inputs onto LA neurons, reducing release probability at these synapses. We subsequently demonstrate that OT modulates synaptic plasticity at cortical inputs to the LA.
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Affiliation(s)
- J. W. Crane
- School of Biomedical Sciences, Charles Sturt University, Orange, New South Wales, Australia
- School of Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - N. M. Holmes
- School of Psychology, University of New South Wales, Sydney, New South Wales, Australia
| | - J. Fam
- School of Psychology, University of New South Wales, Sydney, New South Wales, Australia
| | - R. F. Westbrook
- School of Psychology, University of New South Wales, Sydney, New South Wales, Australia
| | - A. J. Delaney
- School of Biomedical Sciences, Charles Sturt University, Orange, New South Wales, Australia
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7
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Γ-Aminobutyric acid in adult brain: an update. Behav Brain Res 2019; 376:112224. [DOI: 10.1016/j.bbr.2019.112224] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 09/09/2019] [Accepted: 09/09/2019] [Indexed: 01/21/2023]
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8
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Meis S, Endres T, Munsch T, Lessmann V. Impact of Chronic BDNF Depletion on GABAergic Synaptic Transmission in the Lateral Amygdala. Int J Mol Sci 2019; 20:ijms20174310. [PMID: 31484392 PMCID: PMC6747405 DOI: 10.3390/ijms20174310] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/30/2019] [Accepted: 09/01/2019] [Indexed: 01/14/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) has previously been shown to play an important role in glutamatergic synaptic plasticity in the amygdala, correlating with cued fear learning. While glutamatergic neurotransmission is facilitated by BDNF signaling in the amygdala, its mechanism of action at inhibitory synapses in this nucleus is far less understood. We therefore analyzed the impact of chronic BDNF depletion on GABAA-mediated synaptic transmission in BDNF heterozygous knockout mice (BDNF+/−). Analysis of miniature and evoked inhibitory postsynaptic currents (IPSCs) in the lateral amygdala (LA) revealed neither pre- nor postsynaptic differences in BDNF+/− mice compared to wild-type littermates. In addition, long-term potentiation (LTP) of IPSCs was similar in both genotypes. In contrast, facilitation of spontaneous IPSCs (sIPSCs) by norepinephrine (NE) was significantly reduced in BDNF+/− mice. These results argue against a generally impaired efficacy and plasticity at GABAergic synapses due to a chronic BDNF deficit. Importantly, the increase in GABAergic tone mediated by NE is reduced in BDNF+/− mice. As release of NE is elevated during aversive behavioral states in the amygdala, effects of a chronic BDNF deficit on GABAergic inhibition may become evident in response to states of high arousal, leading to amygdala hyper-excitability and impaired amygdala function.
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Affiliation(s)
- Susanne Meis
- Institut für Physiologie, Otto-von-Guericke-Universität, D-39120 Magdeburg, Germany.
- Center for Behavioral Brain Sciences, D-39106 Magdeburg, Germany.
| | - Thomas Endres
- Institut für Physiologie, Otto-von-Guericke-Universität, D-39120 Magdeburg, Germany.
| | - Thomas Munsch
- Institut für Physiologie, Otto-von-Guericke-Universität, D-39120 Magdeburg, Germany.
- Center for Behavioral Brain Sciences, D-39106 Magdeburg, Germany.
| | - Volkmar Lessmann
- Institut für Physiologie, Otto-von-Guericke-Universität, D-39120 Magdeburg, Germany.
- Center for Behavioral Brain Sciences, D-39106 Magdeburg, Germany.
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9
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Meis S, Endres T, Munsch T, Lessmann V. The Relation Between Long-Term Synaptic Plasticity at Glutamatergic Synapses in the Amygdala and Fear Learning in Adult Heterozygous BDNF-Knockout Mice. Cereb Cortex 2019; 28:1195-1208. [PMID: 28184413 DOI: 10.1093/cercor/bhx032] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Indexed: 01/21/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) heterozygous knockout mice (BDNF+/- mice) show fear learning deficits from 3 months of age onwards. Here, we addressed the question how this learning deficit correlates with altered long-term potentiation (LTP) in the cortical synaptic input to the lateral amygdala (LA) and at downstream intra-amygdala synapses in BDNF+/- mice. Our results reveal that the fear learning deficit in BDNF+/- mice was not paralleled by a loss of LTP, neither at cortical inputs to the LA nor at downstream intra-amygdala glutamatergic synapses. As we did observe early fear memory (30 min after training) in BDNF+/- mice while long-term memory (24 h post-training) was absent, the stable LTP in cortico-LA and downstream synapses is in line with the intact acquisition of fear memories. Ex vivo recordings in acute slices of fear-conditioned wildtype (WT) mice revealed that fear learning induces long-lasting changes at cortico-LA synapses that occluded generation of LTP 4 and 24 h after training. Overall, our data show that the intact LTP in the tested amygdala circuits is consistent with intact acquisition of fear memories in both WT and BDNF+/- mice. In addition, the lack of learning-induced long-term changes at cortico-LA synapses in BDNF+/- mice parallels the observed deficit in fear memory consolidation.
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Affiliation(s)
- S Meis
- Institut für Physiologie, Otto-von-Guericke-Universität, D-39120 Magdeburg, Germany.,Center for Behavioral Brain Sciences, Universitätsplatz 2, D-39106 Magdeburg, Germany
| | - T Endres
- Institut für Physiologie, Otto-von-Guericke-Universität, D-39120 Magdeburg, Germany
| | - T Munsch
- Institut für Physiologie, Otto-von-Guericke-Universität, D-39120 Magdeburg, Germany.,Center for Behavioral Brain Sciences, Universitätsplatz 2, D-39106 Magdeburg, Germany
| | - V Lessmann
- Institut für Physiologie, Otto-von-Guericke-Universität, D-39120 Magdeburg, Germany.,Center for Behavioral Brain Sciences, Universitätsplatz 2, D-39106 Magdeburg, Germany
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10
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Cieślik P, Woźniak M, Tokarski K, Kusek M, Pilc A, Płoska A, Radulska A, Pelikant-Małecka I, Żołnowska B, Sławiński J, Kalinowski L, Wierońska JM. Simultaneous activation of muscarinic and GABA B receptors as a bidirectional target for novel antipsychotics. Behav Brain Res 2018; 359:671-685. [PMID: 30267715 DOI: 10.1016/j.bbr.2018.09.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 05/08/2018] [Accepted: 09/22/2018] [Indexed: 12/11/2022]
Abstract
Recent preclinical studies point to muscarinic and GABAB receptors as novel therapeutic targets for the treatment of schizophrenia. This study was aimed to assess the role of muscarinic and GABAB receptor interactions in animal models of schizophrenia, using positive allosteric modulators (PAMs) of GABAB receptor (GS39783), muscarinic M4 (VU0152100) and M5 (VU0238429) receptor, and partial allosteric agonist of M1 receptor (VU0357017). DOI-induced head twitches, social interaction and novel object recognition tests were used as the models of schizophrenia. Analyses of DOI-induced increases in sEPSCs (spontaneous excitatory postsynaptic currents) were performed as complementary experiments to the DOI-induced head twitch studies. Haloperidol-induced catalepsy and the rotarod test were used to examine the adverse effects of the drugs. All three activators of muscarinic receptors were active in DOI-induced head twitches. When administered together with GS39783 in subeffective doses, only the co-administration of VU0152100 and GS39783 was effective. The combination also reduced the frequency but not the amplitude of DOI-induced sEPSCs. Neither VU0357017 nor VU0238429 were active in social interaction test when given alone, and also the combination of VU0152100 and GS39783 failed to reverse MK-801-induced deficits observed in this test. All muscarinic activators when administered alone or in combination with GS39783 reversed the MK-801-induced disruption of memory in the novel object recognition test, and their actions were blocked by specific antagonists. None of the tested compounds or their combinations influenced the motor coordination of the animals. The compounds had no effect on haloperidol-induced catalepsy and did not induce catalepsy when administered alone. Pharmacokinetic analysis confirmed lack of possible drug-drug interactions after combined administration of GS39783 with VU0357017 or VU0152100; however, when the drug was co-administered with VU0238429 its ability to pass the blood-brain barrier slightly decreased, suggesting potential drug-drug interactions. Our data show that modulation of cholinergic and GABAergic systems can potentially be beneficial in the treatment of the positive and cognitive symptoms of schizophrenia without inducing the adverse effects typical for presently used antipsychotics.
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Affiliation(s)
- Paulina Cieślik
- Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, Poland
| | - Monika Woźniak
- Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, Poland
| | - Krzysztof Tokarski
- Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, Poland
| | - Magdalena Kusek
- Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, Poland
| | - Andrzej Pilc
- Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, Poland; Health Sciences Faculty, Institute of Public Health, Jagiellonian University Medical College, Kraków, Poland
| | - Agata Płoska
- Department of Medical Laboratory Diagnostics - Biobank, Medical University of Gdansk, Gdansk, Poland; Biobanking and Biomolecular Resources Research Infrastructure Poland (BBMRI.PL), Gdansk, Poland
| | - Adrianna Radulska
- Department of Medical Laboratory Diagnostics - Biobank, Medical University of Gdansk, Gdansk, Poland; Biobanking and Biomolecular Resources Research Infrastructure Poland (BBMRI.PL), Gdansk, Poland
| | - Iwona Pelikant-Małecka
- Department of Medical Laboratory Diagnostics - Biobank, Medical University of Gdansk, Gdansk, Poland; Biobanking and Biomolecular Resources Research Infrastructure Poland (BBMRI.PL), Gdansk, Poland
| | - Beata Żołnowska
- Department of Organic Chemistry, Medical University of Gdansk, Gdańsk, Poland
| | - Jarosław Sławiński
- Department of Organic Chemistry, Medical University of Gdansk, Gdańsk, Poland
| | - Leszek Kalinowski
- Department of Medical Laboratory Diagnostics - Biobank, Medical University of Gdansk, Gdansk, Poland; Biobanking and Biomolecular Resources Research Infrastructure Poland (BBMRI.PL), Gdansk, Poland
| | - Joanna M Wierońska
- Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, Poland.
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11
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Delaney AJ, Crane JW, Holmes NM, Fam J, Westbrook RF. Baclofen acts in the central amygdala to reduce synaptic transmission and impair context fear conditioning. Sci Rep 2018; 8:9908. [PMID: 29967489 PMCID: PMC6028433 DOI: 10.1038/s41598-018-28321-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 06/15/2018] [Indexed: 12/14/2022] Open
Abstract
The two main sub-divisions of the Central amygdala (CeA), the lateral-capsular (CeA-LC) and the medial (CeA-M), contain extensive networks of inhibitory interneurons. We have previously shown that activation of GABAB-receptors reduces excitatory transmission between axons of the pontine parabrachial nucleus and neurons of the CeA-LC by inhibiting glutamate release from presynaptic terminals13. Here we have characterised GABAB-receptor activation on other excitatory and inhibitory projections within the CeA. Using whole-cell, patch-clamp recordings, we found that the GABAB-receptor agonist baclofen significantly reduced excitatory and inhibitory transmission from all tested inputs into the CeA-LC and CeA-M. In all but one of the inputs, reductions in transmission were accompanied by an increase in paired pulse ratio, indicating that presynaptic GABAB-receptors acted to reduce the release probability of synaptic vesicles. To examine the impact of GABAB-receptors in the CeA on contextual fear-conditioning, we infused baclofen into the CeA immediately prior to training. Compared to vehicle-infused rats, baclofen-infused rats displayed significantly less freezing both during the final stages of the training period and at test 24 hours later. The results of this study demonstrate that, by suppressing excitatory and inhibitory transmission, activation of presynaptic GABAB-receptors in the CeA inhibits the development of context conditioned fear.
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Affiliation(s)
- A J Delaney
- School of Biomedical Sciences, Charles Sturt University, Orange, NSW, 2800, Australia.
| | - J W Crane
- School of Medicine, University of Tasmania, Hobart, TAS, 7000, Australia
| | - N M Holmes
- School of Psychology, University of New South Wales, Sydney, NSW, 2052, Australia
| | - J Fam
- School of Psychology, University of New South Wales, Sydney, NSW, 2052, Australia
| | - R F Westbrook
- School of Psychology, University of New South Wales, Sydney, NSW, 2052, Australia
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12
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Apland JP, Aroniadou-Anderjaska V, Figueiredo TH, Pidoplichko VI, Rossetti K, Braga MFM. Comparing the Antiseizure and Neuroprotective Efficacy of LY293558, Diazepam, Caramiphen, and LY293558-Caramiphen Combination against Soman in a Rat Model Relevant to the Pediatric Population. J Pharmacol Exp Ther 2018; 365:314-326. [PMID: 29467308 PMCID: PMC5878669 DOI: 10.1124/jpet.117.245969] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/08/2018] [Indexed: 12/13/2022] Open
Abstract
The currently Food and Drug Administration-approved anticonvulsant for the treatment of status epilepticus (SE) induced by nerve agents is the benzodiazepine diazepam; however, diazepam does not appear to offer neuroprotective benefits. This is of particular concern with respect to the protection of children because, in the developing brain, synaptic transmission mediated via GABAA receptors, the target of diazepam, is weak. In the present study, we exposed 21-day-old male rats to 1.2 × LD50 soman and compared the antiseizure, antilethality, and neuroprotective efficacy of diazepam (10 mg/kg), LY293558 (an AMPA/GluK1 receptor antagonist; 15 mg/kg), caramiphen (CRM, an antimuscarinic with NMDA receptor-antagonistic properties; 50 mg/kg), and LY293558 (15 mg/kg) + CRM (50 mg/kg), administered 1 hour after exposure. Diazepam, LY293558, and LY293558 + CRM, but not CRM alone, terminated SE; LY293558 + CRM treatment acted significantly faster and produced a survival rate greater than 85%. Thirty days after soman exposure, neurodegeneration in limbic regions was most severe in the CRM-treated group, minimal to severe-depending on the region-in the diazepam group, absent to moderate in the LY293558-treated group, and totally absent in the LY293558 + CRM group. Amygdala and hippocampal atrophy, a severe reduction in spontaneous inhibitory activity in the basolateral amygdala, and increased anxiety-like behavior in the open-field and acoustic startle response tests were present in the diazepam and CRM groups, whereas the LY293558 and LY293558 + CRM groups did not differ from controls. The combined administration of LY293558 and CRM, by blocking mainly AMPA, GluK1, and NMDA receptors, is a very effective anticonvulsant and neuroprotective therapy against soman in young rats.
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Affiliation(s)
- James P Apland
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Vassiliki Aroniadou-Anderjaska
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Taiza H Figueiredo
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Volodymyr I Pidoplichko
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Katia Rossetti
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Maria F M Braga
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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13
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Shen W, Nan C, Nelson PT, Ripps H, Slaughter MM. GABA B receptor attenuation of GABA A currents in neurons of the mammalian central nervous system. Physiol Rep 2017; 5:5/6/e13129. [PMID: 28348006 PMCID: PMC5371550 DOI: 10.14814/phy2.13129] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 11/18/2016] [Indexed: 11/24/2022] Open
Abstract
Ionotropic receptors are tightly regulated by second messenger systems and are often present along with their metabotropic counterparts on a neuron's plasma membrane. This leads to the hypothesis that the two receptor subtypes can interact, and indeed this has been observed in excitatory glutamate and inhibitory GABA receptors. In both systems the metabotropic pathway augments the ionotropic receptor response. However, we have found that the metabotropic GABAB receptor can suppress the ionotropic GABAA receptor current, in both the in vitro mouse retina and in human amygdala membrane fractions. Expression of amygdala membrane microdomains in Xenopus oocytes by microtransplantation produced functional ionotropic and metabotropic GABA receptors. Most GABAA receptors had properties of α‐subunit containing receptors, with ~5% having ρ‐subunit properties. Only GABAA receptors with α‐subunit‐like properties were regulated by GABAB receptors. In mouse retinal ganglion cells, where only α‐subunit‐containing GABAA receptors are expressed, GABAB receptors suppressed GABAA receptor currents. This suppression was blocked by GABAB receptor antagonists, G‐protein inhibitors, and GABAB receptor antibodies. Based on the kinetic differences between metabotropic and ionotropic receptors, their interaction would suppress repeated, rapid GABAergic inhibition.
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Affiliation(s)
- Wen Shen
- Department of Biomedical Science, Charles E. Schmidt College of Medicine Florida Atlantic University, Boca Raton, Florida
| | - Changlong Nan
- Department of Biomedical Science, Charles E. Schmidt College of Medicine Florida Atlantic University, Boca Raton, Florida
| | - Peter T Nelson
- Division of Neuropathology, Department of Pathology, University of Kentucky, Lexington, Kentucky.,Sanders-Brown Centre on Aging, University of Kentucky, Lexington, Kentucky
| | - Harris Ripps
- Department of Ophthalmology and Visual Sciences, University of Illinois College of Medicine, Chicago, Illinois.,Whitman Investigator, Marine Biological Laboratory, Woods Hole, Massachusetts
| | - Malcolm M Slaughter
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York
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14
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Elucidation of the neural circuits activated by a GABA B receptor positive modulator: Relevance to anxiety. Neuropharmacology 2017; 136:129-145. [PMID: 28734870 DOI: 10.1016/j.neuropharm.2017.07.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/17/2017] [Accepted: 07/18/2017] [Indexed: 01/09/2023]
Abstract
Although there is much evidence for a role of GABAB receptors in the pathophysiology of anxiety, the underlying neuronal mechanisms are largely unclear. The GABAB receptor allosteric positive modulator, GS39783, exerts anxiolytic effects without interfering with GABAB-mediated modulation of body temperature, cognitive performance and locomotor activity thus offering advantages over GABAB receptor agonists. However, the precise neural circuits underlying the anxiolytic effects of GS39783 are unknown. The aim of the present study was to identify brain structures and associated neuronal circuits that are modulated by GS39783 under either basal or mild stress conditions. To this end, the expression pattern of c-Fos, a marker of neuronal activation, was examined in mice acutely treated with GS39783 under basal conditions or following a mild anxiogenic challenge induced by exposure to the Open Arm (OA) of an Elevated Plus Maze. OA exposure enhanced c-Fos expression in vehicle-treated animals in several brain regions, including the medial prefrontal cortex, lateral septum, amygdala, hippocampus, paraventricular nucleus of the hypothalamus and the periaqueductal gray (PAG). Under basal conditions, GS39783 increased c-Fos in a restricted panel of areas notably amygdala nuclei, cortical areas and PAG subregions, while it inhibited c-Fos expression in the dorsal raphe nucleus (DRN). Under stress conditions, GS39783 reversed OA-induced c-Fos expression in the granular cell layer of the dentate gyrus, no longer increased c-Fos expression in the amygdala nor reduced c-Fos expression in the DRN. These specific patterns of neural activation by GS39783 might explain the neurobiological correlates implicated in GABAB-mediated anti-anxiety effects. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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15
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Zhang WH, Zhou J, Pan HQ, Wang XY, Liu WZ, Zhang JY, Yin XP, Pan BX. δ Subunit-containing GABA A receptor prevents overgeneralization of fear in adult mice. ACTA ACUST UNITED AC 2017; 24:381-384. [PMID: 28716958 PMCID: PMC5516689 DOI: 10.1101/lm.045856.117] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 05/08/2017] [Indexed: 11/25/2022]
Abstract
The role of δ subunit-containing GABAA receptor (GABAA(δ)R) in fear generalization is uncertain. Here, by using mice with or without genetic deletion of GABAA(δ)R and using protocols in which the conditioned tone stimuli were cross presented with different nonconditioned stimuli, we observed that when the two tone stimuli were largely similar, both genotypes froze similarly to either of them. However, when they differed markedly, the knockout mice froze much more than their wild-type littermates to the nonconditioned but not conditioned stimuli. Thus, GABAA(δ)R may prevent inappropriate fear generalization when the incoming stimuli differ clearly from the learned threat.
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Affiliation(s)
- Wen-Hua Zhang
- Department of Neurology, the 2nd Affiliated Hospital, Nanchang University, Nanchang, 330031, China.,Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, China
| | - Jin Zhou
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, China.,School of Life Science, Nanchang University, Nanchang, 330031, China
| | - Han-Qing Pan
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, China.,School of Life Science, Nanchang University, Nanchang, 330031, China
| | - Xiao-Yang Wang
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, China.,School of Life Science, Nanchang University, Nanchang, 330031, China
| | - Wei-Zhu Liu
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, China.,School of Life Science, Nanchang University, Nanchang, 330031, China
| | - Jun-Yu Zhang
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, China
| | - Xiao-Ping Yin
- Department of Neurology, the 2nd Affiliated Hospital, Nanchang University, Nanchang, 330031, China
| | - Bing-Xing Pan
- Department of Neurology, the 2nd Affiliated Hospital, Nanchang University, Nanchang, 330031, China.,Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, China.,School of Life Science, Nanchang University, Nanchang, 330031, China
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16
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Peng SC, Wu J, Zhang DY, Jiang CY, Xie CN, Liu T. Contribution of presynaptic HCN channels to excitatory inputs of spinal substantia gelatinosa neurons. Neuroscience 2017; 358:146-157. [PMID: 28673721 DOI: 10.1016/j.neuroscience.2017.06.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/19/2017] [Accepted: 06/23/2017] [Indexed: 01/09/2023]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are pathological pain-associated voltage-gated ion channels. They are widely expressed in central nervous system including spinal lamina II (also named the substantia gelatinosa, SG). Here, we examined the distribution of HCN channels in glutamatergic synaptic terminals as well as their role in the modulation of synaptic transmission in SG neurons from SD rats and glutamic acid decarboxylase-67 (GAD67)-GFP mice. We found that the expression of the HCN channel isoforms was varied in SG. The HCN4 isoform showed the highest level of co-localization with VGLUT2 (23±3%). In 53% (n=21/40 neurons) of the SG neurons examined in SD rats, application of HCN channel blocker, ZD7288 (10μM), decreased the frequency of spontaneous (s) and miniature (m) excitatory postsynaptic currents (EPSCs) by 37±4% and 33±4%, respectively. Consistently, forskolin (FSK) (an activator of adenylate cyclase) significantly increased the frequency of mEPSCs by 225±34%, which could be partially inhibited by ZD7288. Interestingly, the effects of ZD7288 and FSK on sEPSC frequency were replicated in non-GFP-expressing neurons, but not in GFP-expressing GABAergic SG neurons, in GAD67-GFP transgenic C57/BL6 mice. In summary, our results represent a previously unknown cellular mechanism by which presynaptic HCN channels, especially HCN4, regulate the glutamate release from presynaptic terminals that target excitatory, but not inhibitory SG interneurons.
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Affiliation(s)
- S-C Peng
- Department of Pediatrics, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, China
| | - J Wu
- Department of Pediatrics, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, China
| | - D-Y Zhang
- Department of Pain Clinic, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, China
| | - C-Y Jiang
- Jisheng Han Academician Workstation for Pain Medicine, Nanshan Hospital, Shenzhen 518052, China
| | - C-N Xie
- Department of Pediatrics, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, China
| | - T Liu
- Department of Pediatrics, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, China; Jisheng Han Academician Workstation for Pain Medicine, Nanshan Hospital, Shenzhen 518052, China; Jiangxi Key Laboratory of Molecular Diagnostics and Precision Medicine, Nanchang, Jiangxi 330006, China.
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17
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Packard AEB, Di S, Egan AE, Fourman SM, Tasker JG, Ulrich-Lai YM. Sucrose-induced plasticity in the basolateral amygdala in a 'comfort' feeding paradigm. Brain Struct Funct 2017; 222:4035-4050. [PMID: 28597100 DOI: 10.1007/s00429-017-1454-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 05/12/2017] [Indexed: 01/01/2023]
Abstract
A history of intermittent, limited sucrose intake (LSI) attenuates the hypothalamic-pituitary-adrenocortical (HPA) axis stress response, and neuronal activity in the basolateral amygdala (BLA) is necessary for this HPA-dampening. LSI increases the expression of plasticity-associated genes in the BLA; however, the nature of this plasticity is unknown. As BLA principal neuron activity normally promotes HPA responses, the present study tests the hypothesis that LSI decreases stress-excitatory BLA output by decreasing glutamatergic and/or increasing GABAergic inputs to BLA principal neurons. Male rats with unlimited access to chow and water were given additional access to 4 ml of sucrose (30%) or water twice daily for 14 days, and BLA structural and functional plasticity was assessed by quantitative dual immunolabeling and whole-cell recordings in brain slices. LSI increased vesicular glutamate transporter 1-positive (glutamatergic) appositions onto parvalbumin-positive inhibitory interneurons, and this was accompanied by increased expression of pCREB, a marker of neuronal activation that is mechanistically linked with plasticity, within parvalbumin interneurons. LSI also increased the paired-pulse facilitation of excitatory, but not inhibitory synaptic inputs to BLA principal neurons, without affecting postsynaptic excitatory or miniature excitatory and inhibitory postsynaptic currents, suggesting a targeted decrease in the probability of evoked synaptic excitation onto these neurons. Collectively, these results suggest that LSI decreases BLA principal neuron output by increasing the excitatory drive to parvalbumin inhibitory interneurons, and decreasing the probability of evoked presynaptic glutamate release onto principal neurons. Our data further imply that palatable food consumption blunts HPA stress responses by decreasing the excitation-inhibition balance and attenuating BLA output.
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Affiliation(s)
- Amy E B Packard
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Metabolic Diseases Institute, 2170 East Galbraith Road, ML0506, Cincinnati, OH, 45237, USA
| | - Shi Di
- Department of Cell and Molecular Biology, Tulane University, 2000 Percival Stern Hall, New Orleans, LA, 70118, USA
| | - Ann E Egan
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Metabolic Diseases Institute, 2170 East Galbraith Road, ML0506, Cincinnati, OH, 45237, USA
| | - Sarah M Fourman
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Metabolic Diseases Institute, 2170 East Galbraith Road, ML0506, Cincinnati, OH, 45237, USA
| | - Jeffrey G Tasker
- Department of Cell and Molecular Biology, Tulane University, 2000 Percival Stern Hall, New Orleans, LA, 70118, USA.,Tulane Brain Institute, Tulane University, Flower Hall, New Orleans, LA, 70118, USA
| | - Yvonne M Ulrich-Lai
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Metabolic Diseases Institute, 2170 East Galbraith Road, ML0506, Cincinnati, OH, 45237, USA.
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18
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Chang CH. Lateral Orbitofrontal Cortical Modulation on the Medial Prefrontal Cortex-Amygdala Pathway: Differential Regulation of Intra-Amygdala GABAA and GABAB Receptors. Int J Neuropsychopharmacol 2017; 20:602-610. [PMID: 28444246 PMCID: PMC5492808 DOI: 10.1093/ijnp/pyx027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 04/18/2017] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The basolateral complex of the amygdala receives inputs from neocortical areas, including the medial prefrontal cortex and lateral orbitofrontal cortex. Earlier studies have shown that lateral orbitofrontal cortex activation exerts an inhibitory gating on medial prefrontal cortex-amygdala information flow. Here we examined the individual role of GABAA and GABAB receptors in this process. METHODS In vivo extracellular single-unit recordings were done in anesthetized rats. We searched amygdala neurons that fire in response to medial prefrontal cortex activation, tested lateral orbitofrontal cortex gating at different delays (lateral orbitofrontal cortex-medial prefrontal cortex delays: 25, 50, 100, 250, 500, and 1000 milliseconds), and examined differential contribution of GABAA and GABAB receptors with iontophoresis. RESULTS Relative to baseline, lateral orbitofrontal cortex stimulation exerted an inhibitory modulatory gating on the medial prefrontal cortex-amygdala pathway and was effective up to a long delay of 500 ms (long-delay latencies at 100, 250, and 500 milliseconds). Moreover, blockade of intra-amygdala GABAA receptors with bicuculline abolished the lateral orbitofrontal cortex inhibitory gating at both short- (25 milliseconds) and long-delay (100 milliseconds) intervals, while blockade of GABAB receptors with saclofen reversed the inhibitory gating at long delay (100 milliseconds) only. Among the majority of the neurons examined (8 of 9), inactivation of either GABAA or GABAB receptors during baseline did not change evoked probability per se, suggesting that local feed-forward inhibitory mechanism is pathway specific. CONCLUSIONS Our results suggest that the effect of lateral orbitofrontal cortex inhibitory modulatory gating was effective up to 500 milliseconds and that intra-amygdala GABAA and GABAB receptors differentially modulate the short- and long-delay lateral orbitofrontal cortex inhibitory gating on the medial prefrontal cortex-amygdala pathway.
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Affiliation(s)
- Chun-hui Chang
- Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu, Taiwan
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19
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Bazelot M, Bocchio M, Kasugai Y, Fischer D, Dodson PD, Ferraguti F, Capogna M. Hippocampal Theta Input to the Amygdala Shapes Feedforward Inhibition to Gate Heterosynaptic Plasticity. Neuron 2015; 87:1290-1303. [PMID: 26402610 PMCID: PMC4590554 DOI: 10.1016/j.neuron.2015.08.024] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 07/02/2015] [Accepted: 08/07/2015] [Indexed: 12/29/2022]
Abstract
The dynamic interactions between hippocampus and amygdala are critical for emotional memory. Theta synchrony between these structures occurs during fear memory retrieval and may facilitate synaptic plasticity, but the cellular mechanisms are unknown. We report that interneurons of the mouse basal amygdala are activated during theta network activity or optogenetic stimulation of ventral CA1 pyramidal cell axons, whereas principal neurons are inhibited. Interneurons provide feedforward inhibition that transiently hyperpolarizes principal neurons. However, synaptic inhibition attenuates during theta frequency stimulation of ventral CA1 fibers, and this broadens excitatory postsynaptic potentials. These effects are mediated by GABAB receptors and change in the Cl− driving force. Pairing theta frequency stimulation of ventral CA1 fibers with coincident stimuli of the lateral amygdala induces long-term potentiation of lateral-basal amygdala excitatory synapses. Hence, feedforward inhibition, known to enforce temporal fidelity of excitatory inputs, dominates hippocampus-amygdala interactions to gate heterosynaptic plasticity. Video Abstract
Theta stimulation of CA1 ventral hippocampal fibers activates amygdala interneurons Interneurons induce feedforward inhibition that hyperpolarizes principal neurons Theta-evoked inhibition attenuates to broaden excitation on principal neurons Feedforward inhibition gates heterosynaptic plasticity via GABAB receptors
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Affiliation(s)
- Michaël Bazelot
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK
| | - Marco Bocchio
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK
| | - Yu Kasugai
- Department of Pharmacology, Innsbruck Medical University, Peter Mayr Straße 1a, 6020 Innsbruck, Austria
| | - David Fischer
- Department of Pharmacology, Innsbruck Medical University, Peter Mayr Straße 1a, 6020 Innsbruck, Austria
| | - Paul D Dodson
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK
| | - Francesco Ferraguti
- Department of Pharmacology, Innsbruck Medical University, Peter Mayr Straße 1a, 6020 Innsbruck, Austria
| | - Marco Capogna
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK.
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20
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Prager EM, Bergstrom HC, Wynn GH, Braga MFM. The basolateral amygdala γ-aminobutyric acidergic system in health and disease. J Neurosci Res 2015; 94:548-67. [PMID: 26586374 DOI: 10.1002/jnr.23690] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 10/01/2015] [Accepted: 10/18/2015] [Indexed: 01/13/2023]
Abstract
The brain comprises an excitatory/inhibitory neuronal network that maintains a finely tuned balance of activity critical for normal functioning. Excitatory activity in the basolateral amygdala (BLA), a brain region that plays a central role in emotion and motivational processing, is tightly regulated by a relatively small population of γ-aminobutyric acid (GABA) inhibitory neurons. Disruption in GABAergic inhibition in the BLA can occur when there is a loss of local GABAergic interneurons, an alteration in GABAA receptor activation, or a dysregulation of mechanisms that modulate BLA GABAergic inhibition. Disruptions in GABAergic control of the BLA emerge during development, in aging populations, or after trauma, ultimately resulting in hyperexcitability. BLA hyperexcitability manifests behaviorally as an increase in anxiety, emotional dysregulation, or development of seizure activity. This Review discusses the anatomy, development, and physiology of the GABAergic system in the BLA and circuits that modulate GABAergic inhibition, including the dopaminergic, serotonergic, noradrenergic, and cholinergic systems. We highlight how alterations in various neurotransmitter receptors, including the acid-sensing ion channel 1a, cannabinoid receptor 1, and glutamate receptor subtypes, expressed on BLA interneurons, modulate GABAergic transmission and how defects of these systems affect inhibitory tonus within the BLA. Finally, we discuss alterations in the BLA GABAergic system in neurodevelopmental (autism/fragile X syndrome) and neurodegenerative (Alzheimer's disease) diseases and after the development of epilepsy, anxiety, and traumatic brain injury. A more complete understanding of the intrinsic excitatory/inhibitory circuit balance of the amygdala and how imbalances in inhibitory control contribute to excessive BLA excitability will guide the development of novel therapeutic approaches in neuropsychiatric diseases.
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Affiliation(s)
- Eric M Prager
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services, University of the Health Sciences, Bethesda, Maryland
| | | | - Gary H Wynn
- Center for the Study of Traumatic Stress, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Maria F M Braga
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services, University of the Health Sciences, Bethesda, Maryland.,Center for the Study of Traumatic Stress, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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Bosch D, Ehrlich I. Postnatal maturation of GABAergic modulation of sensory inputs onto lateral amygdala principal neurons. J Physiol 2015; 593:4387-409. [PMID: 26227545 DOI: 10.1113/jp270645] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 07/28/2015] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Throughout life, fear learning is indispensable for survival and neural plasticity in the lateral amygdala underlies this learning and storage of fear memories. During development, properties of fear learning continue to change into adulthood, but currently little is known about changes in amygdala circuits that enable these behavioural transitions. In recordings from neurons in lateral amygdala brain slices from infant up to adult mice, we show that spontaneous and evoked excitatory and inhibitory synaptic transmissions mature into adolescence. At this time, increased inhibitory activity and signalling has the ability to restrict the function of excitation by presynaptic modulation, and may thus enable precise stimulus associations to limit fear generalization from adolescence onward. Our results provide a basis for addressing plasticity mechanisms that underlie altered fear behaviour in young animals. ABSTRACT Convergent evidence suggests that plasticity in the lateral amygdala (LA) participates in acquisition and storage of fear memory. Sensory inputs from thalamic and cortical areas activate principal neurons and local GABAergic interneurons, which provide feed-forward inhibition that tightly controls LA activity and plasticity via pre- and postsynaptic GABAA and GABAB receptors. GABAergic control is also critical during fear expression, generalization and extinction in adult animals. During rodent development, properties of fear and extinction learning continue to change into early adulthood. Currently, few studies have assessed physiological changes in amygdala circuits that may enable these behavioural transitions. To obtain first insights, we investigated changes in spontaneous and sensory input-evoked inhibition onto LA principal neurons and then focused on GABAB receptor-mediated modulation of excitatory sensory inputs in infant, juvenile, adolescent and young adult mice. We found that spontaneous and sensory-evoked inhibition increased during development. Physiological changes were accompanied by changes in dendritic morphology. While GABAB heteroreceptors were functionally expressed on sensory afferents already early in development, they could only be physiologically recruited by sensory-evoked GABA release to mediate heterosynaptic inhibition from adolescence onward. Furthermore, we found GABAB -mediated tonic inhibition of sensory inputs by ambient GABA that also emerged in adolescence. The observed increase in GABAergic drive may be a substrate for providing modulatory GABA. Our data suggest that GABAB -mediated tonic and evoked presynaptic inhibition can suppress sensory input-driven excitation in the LA to enable precise stimulus associations and limit generalization of conditioned fear from adolescence onward.
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Affiliation(s)
- Daniel Bosch
- Hertie Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller-Str. 25, 72076, Tuebingen, Germany.,Werner Reichardt Centre for Integrative Neuroscience, University of Tuebingen, Otfried-Mueller-Str. 25, 72076, Tuebingen, Germany
| | - Ingrid Ehrlich
- Hertie Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller-Str. 25, 72076, Tuebingen, Germany.,Werner Reichardt Centre for Integrative Neuroscience, University of Tuebingen, Otfried-Mueller-Str. 25, 72076, Tuebingen, Germany
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22
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Kasten CR, Boehm SL. Identifying the role of pre-and postsynaptic GABA(B) receptors in behavior. Neurosci Biobehav Rev 2015; 57:70-87. [PMID: 26283074 DOI: 10.1016/j.neubiorev.2015.08.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 06/18/2015] [Accepted: 08/09/2015] [Indexed: 12/15/2022]
Abstract
Although many reviews exist characterizing the molecular differences of GABAB receptor isoforms, there is no current review of the in vivo effects of these isoforms. The current review focuses on whether the GABAB1a and GABAB1b isoforms contribute differentially to behaviors in isoform knockout mice. The roles of these receptors have primarily been characterized in cognitive, anxiety, and depressive phenotypes. Currently, the field supports a role of GABAB1a in memory maintenance and protection against an anhedonic phenotype, whereas GABAB1b appears to be involved in memory formation and a susceptibility to developing an anhedonic phenotype. Although GABAB receptors have been strongly implicated in drug abuse phenotypes, no isoform-specific work has been done in this field. Future directions include developing site-specific isoform knockdown to identify the role of different brain regions in behavior, as well as identifying how these isoforms are involved in development of behavioral phenotypes.
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Affiliation(s)
- Chelsea R Kasten
- Department of Psychology, Indianapolis University Purdue University-Indianapolis, 402N Blackford St LD 124, Indianapolis, IN 46202, United States.
| | - Stephen L Boehm
- Department of Psychology, Indianapolis University Purdue University-Indianapolis, 402N Blackford St LD 124, Indianapolis, IN 46202, United States; Indiana Alcohol Research Center, 545 Barnhill Drive EH 317, Indianapolis, IN, United States.
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Asede D, Bosch D, Lüthi A, Ferraguti F, Ehrlich I. Sensory inputs to intercalated cells provide fear-learning modulated inhibition to the basolateral amygdala. Neuron 2015; 86:541-54. [PMID: 25843406 DOI: 10.1016/j.neuron.2015.03.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 01/07/2015] [Accepted: 02/25/2015] [Indexed: 12/16/2022]
Abstract
Increasing evidence suggests that parallel plastic processes in the amygdala involve inhibitory elements to control fear and extinction memory. GABAergic medial paracapsular intercalated cells (mpITCs) are thought to relay activity from basolateral nucleus (BLA) and prefrontal cortex to inhibit central amygdala output during suppression of fear. Recently, projection diversity and differential behavioral activation of mpITCs in distinct fear states suggest additional functions. Here, we show that mpITCs receive convergent sensory thalamic and cortical inputs that undergo fear learning-related changes and are dynamically modulated via presynaptic GABAB receptors recruited by GABA released from the mpITC network. Among mpITCs, we identify cells that inhibit but are also mutually activated by BLA principal neurons. Thus, mpITCs take part in fear learning-modulated feedforward and feedback inhibitory circuits to simultaneously control amygdala input and output nuclei. Our findings place mpITCs in a unique position to gate acquired amygdala-dependent behaviors via their direct sensory inputs.
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Affiliation(s)
- Douglas Asede
- Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Straße 25, 72076 Tübingen, Germany; Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, Otfried-Müller-Straße 25, 72076 Tübingen, Germany; Graduate School of Neural and Behavioral Sciences, International Max Planck Research School, University of Tübingen, Österbergstrasse 3, 72074 Tübingen, Germany
| | - Daniel Bosch
- Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Straße 25, 72076 Tübingen, Germany; Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, Otfried-Müller-Straße 25, 72076 Tübingen, Germany
| | - Andreas Lüthi
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Francesco Ferraguti
- Department of Pharmacology, Innsbruck Medical University, Peter Mayr Straße 1a, 6020 Innsbruck, Austria
| | - Ingrid Ehrlich
- Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Straße 25, 72076 Tübingen, Germany; Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, Otfried-Müller-Straße 25, 72076 Tübingen, Germany.
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Urban-Ciecko J, Fanselow EE, Barth AL. Neocortical somatostatin neurons reversibly silence excitatory transmission via GABAb receptors. Curr Biol 2015; 25:722-731. [PMID: 25728691 DOI: 10.1016/j.cub.2015.01.035] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/16/2014] [Accepted: 01/15/2015] [Indexed: 01/04/2023]
Abstract
BACKGROUND Understanding the dynamic range for excitatory transmission is a critical component of building a functional circuit diagram for the mammalian brain. Excitatory synaptic transmission is typically studied under optimized conditions, when background activity in the network is low. The range of synaptic function in the presence of inhibitory and excitatory activity within the neocortical circuit is unknown. RESULTS Paired-cell recordings from pyramidal neurons in acute brain slices of mouse somatosensory cortex show that excitatory synaptic transmission is markedly suppressed during spontaneous network activity: EPSP amplitudes are 2-fold smaller and failure rates are greater than 50%. This suppression is mediated by tonic activation of presynaptic GABAb receptors gated by the spontaneous activity of somatostatin-expressing (Sst) interneurons. Optogenetic suppression of Sst neuron firing was sufficient to enhance EPSP amplitude and reduce failure rates, effects that were fully reversible and occluded by GABAb antagonists. CONCLUSIONS These data indicate that Sst interneurons can rapidly and reversibly silence excitatory synaptic connections through the regulation of presynaptic release. This is an unanticipated role for Sst interneurons, which have been assigned a role only in fast GABAa-mediated inhibition. Because Sst interneuron activity has been shown to be regulated by sensory and motor input, these results suggest a mechanism by which functional connectivity and synaptic plasticity could be gated in a state-dependent manner.
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Affiliation(s)
- Joanna Urban-Ciecko
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | - Erika E Fanselow
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | - Alison L Barth
- Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
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Altered emotionality and neuronal excitability in mice lacking KCTD12, an auxiliary subunit of GABAB receptors associated with mood disorders. Transl Psychiatry 2015; 5:e510. [PMID: 25689571 PMCID: PMC4445757 DOI: 10.1038/tp.2015.8] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 12/02/2014] [Accepted: 12/19/2014] [Indexed: 12/26/2022] Open
Abstract
Gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the brain, is fundamental to brain function and implicated in the pathophysiology of several neuropsychiatric disorders. GABA activates G-protein-coupled GABAB receptors comprising principal GABAB1 and GABAB2 subunits as well as auxiliary KCTD8, 12, 12b and 16 subunits. The KCTD12 gene has been associated with bipolar disorder, major depressive disorder and schizophrenia. Here we compare Kctd12 null mutant (Kctd12(-/-)) and heterozygous (Kctd12(+/-)) with wild-type (WT) littermate mice to determine whether lack of or reduced KCTD12 expression leads to phenotypes that, extrapolating to human, could constitute endophenotypes for neuropsychiatric disorders with which KCTD12 is associated. Kctd12(-/-) mice exhibited increased fear learning but not increased memory of a discrete auditory-conditioned stimulus. Kctd12(+/-) mice showed increased activity during the inactive (light) phase of the circadian cycle relative to WT and Kctd12(-/-) mice. Electrophysiological recordings from hippocampal slices, a region of high Kctd12 expression, revealed an increased intrinsic excitability of pyramidal neurons in Kctd12(-/-) and Kctd12(+/-) mice. This is the first direct evidence for involvement of KCTD12 in determining phenotypes of emotionality, behavioral activity and neuronal excitability. This study provides empirical support for the polymorphism and expression evidence that KCTD12 confers risk for and is associated with neuropsychiatric disorders.
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Pathophysiological mechanisms underlying increased anxiety after soman exposure: reduced GABAergic inhibition in the basolateral amygdala. Neurotoxicology 2014; 44:335-43. [PMID: 25150775 DOI: 10.1016/j.neuro.2014.08.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/22/2014] [Accepted: 08/13/2014] [Indexed: 11/21/2022]
Abstract
The recent sarin attack in Syria killed 1429 people, including 426 children, and left countless more to deal with the health consequences of the exposure. Prior to the Syrian chemical assault, nerve agent attacks in Japan left many victims suffering from neuropsychiatric illnesses, particularly anxiety disorders, more than a decade later. Uncovering the neuro-pathophysiological mechanisms underlying the development of anxiety after nerve agent exposure is necessary for successful treatment. Anxiety is associated with hyperexcitability of the basolateral amygdala (BLA). The present study sought to determine the nature of the nerve agent-induced alterations in the BLA, which could explain the development of anxiety. Rats were exposed to soman, at a dose that induced prolonged status epilepticus. Twenty-four hours and 14-days after exposure, neurons from the BLA were recorded using whole-cell patch-clamp techniques. At both the 24h and 14-day post-exposure time-points, the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs) in the BLA were reduced, along with reduction in the frequency but not amplitude of miniature IPSCs. In addition, activation of α7-nicotinic acetylcholine receptors, a cholinergic receptor that participates in the regulation of BLA excitability and is involved in anxiety, increased spontaneous excitatory postsynaptic currents (sEPSCs) in both soman-exposed rats and controls, but was less effective in increasing sIPSCs in soman-exposed rats. Despite the loss of both interneurons and principal cells after soman-induced status epilepticus, the frequency of sEPSCs was increased in the soman-exposed rats. Impaired function and cholinergic modulation of GABAergic inhibition in the BLA may underlie anxiety disorders that develop after nerve agent exposure.
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Glutamic acid decarboxylase 65: a link between GABAergic synaptic plasticity in the lateral amygdala and conditioned fear generalization. Neuropsychopharmacology 2014; 39:2211-20. [PMID: 24663011 PMCID: PMC4104340 DOI: 10.1038/npp.2014.72] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 03/05/2014] [Accepted: 03/05/2014] [Indexed: 12/25/2022]
Abstract
An imbalance of the gamma-aminobutyric acid (GABA) system is considered a major neurobiological pathomechanism of anxiety, and the amygdala is a key brain region involved. Reduced GABA levels have been found in anxiety patients, and genetic variations of glutamic acid decarboxylase (GAD), the rate-limiting enzyme of GABA synthesis, have been associated with anxiety phenotypes in both humans and mice. These findings prompted us to hypothesize that a deficiency of GAD65, the GAD isoform controlling the availability of GABA as a transmitter, affects synaptic transmission and plasticity in the lateral amygdala (LA), and thereby interferes with fear responsiveness. Results indicate that genetically determined GAD65 deficiency in mice is associated with (1) increased synaptic length and release at GABAergic connections, (2) impaired efficacy of GABAergic synaptic transmission and plasticity, and (3) reduced spillover of GABA to presynaptic GABAB receptors, resulting in a loss of the associative nature of long-term synaptic plasticity at cortical inputs to LA principal neurons. (4) In addition, training with high shock intensities in wild-type mice mimicked the phenotype of GAD65 deficiency at both the behavioral and synaptic level, indicated by generalization of conditioned fear and a loss of the associative nature of synaptic plasticity in the LA. In conclusion, GAD65 is required for efficient GABAergic synaptic transmission and plasticity, and for maintaining extracellular GABA at a level needed for associative plasticity at cortical inputs in the LA, which, if disturbed, results in an impairment of the cue specificity of conditioned fear responses typifying anxiety disorders.
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28
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Liu ZP, Song C, Wang M, He Y, Xu XB, Pan HQ, Chen WB, Peng WJ, Pan BX. Chronic stress impairs GABAergic control of amygdala through suppressing the tonic GABAA receptor currents. Mol Brain 2014; 7:32. [PMID: 24758222 PMCID: PMC4012764 DOI: 10.1186/1756-6606-7-32] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 04/19/2014] [Indexed: 12/29/2022] Open
Abstract
Background Chronic stress is generally known to exacerbate the development of numerous neuropsychiatric diseases such as fear and anxiety disorders, which is at least partially due to the disinhibition of amygdala subsequent to the prolonged stress exposure. GABA receptor A (GABAAR) mediates the primary component of inhibition in brain and its activation produces two forms of inhibition: the phasic and tonic inhibition. While both of them are critically engaged in limiting the activity of amygdala, their roles in the amygdala disinhibition subsequent to chronic stress exposure are largely unknown. Results We investigated the possible alterations of phasic and tonic GABAAR currents and their roles in the amygdala disinhibition subsequent to chronic stress. We found that both chronic immobilization and unpredictable stress led to long lasting loss of tonic GABAAR currents in the projection neurons of lateral amygdala. By contrast, the phasic GABAAR currents, as measured by the spontaneous inhibitory postsynaptic currents, were virtually unaltered. The loss of tonic inhibition varied with the duration of daily stress and the total days of stress exposure. It was prevented by pretreatment with metyrapone to block corticosterone synthesis or RU 38486, a glucocorticoid receptor antagonist, suggesting the critical involvement of glucocorticoid receptor activation. Moreover, chronic treatment with corticosterone mimicked the effect of chronic stress and reduced the tonic inhibition in lateral amygdala of control mice. The loss of tonic inhibition resulted in the impaired GABAergic gating on neuronal excitability in amygdala, which was prevented by metyrapone pretreatment. Conclusions Our study suggests that enduring loss of tonic but not phasic GABAAR currents critically contributes to the prolonged amygdala disinhibition subsequent to chronic stress. We propose that the preferential loss of tonic inhibition may account for the development of stress-related neuropsychiatric diseases.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Bing-Xing Pan
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang 330031, China.
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Abstract
The discovery that even small changes in extracellular acidity can alter the excitability of neuronal networks via activation of acid-sensing ion channels (ASICs) could have therapeutic application in a host of neurological and psychiatric illnesses. Recent evidence suggests that activation of ASIC1a, a subtype of ASICs that is widely distributed in the brain, is necessary for the expression of fear and anxiety. Antagonists of ASIC1a, therefore, have been proposed as a potential treatment for anxiety. The basolateral amygdala (BLA) is central to fear generation, and anxiety disorders are characterized by BLA hyperexcitability. To better understand the role of ASIC1a in anxiety, we attempted to provide a direct assessment of whether ASIC1a activation increases BLA excitability. In rat BLA slices, activation of ASIC1a by low pH or ammonium elicited inward currents in both interneurons and principal neurons, and increased spontaneous IPSCs recorded from principal cells significantly more than spontaneous EPSCs. Epileptiform activity induced by high potassium and low magnesium was suppressed by ammonium. Antagonism of ASIC1a decreased spontaneous IPSCs more than EPSCs, and increased the excitability of the BLA network, as reflected by the pronounced increase of evoked field potentials, suggesting that ASIC1a channels are active in the basal state. In vivo activation or blockade of ASIC1a in the BLA suppressed or increased, respectively, anxiety-like behavior. Thus, in the rat BLA, ASIC1a has an inhibitory and anxiolytic function. The discovery of positive ASIC1a modulators may hold promise for the treatment of anxiety disorders.
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30
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Modulation of synaptic function through the α-neurexin-specific ligand neurexophilin-1. Proc Natl Acad Sci U S A 2014; 111:E1274-83. [PMID: 24639499 DOI: 10.1073/pnas.1312112111] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Neurotransmission at different synapses is highly variable, and cell-adhesion molecules like α-neurexins (α-Nrxn) and their extracellular binding partners determine synapse function. Although α-Nrxn affect transmission at excitatory and inhibitory synapses, the contribution of neurexophilin-1 (Nxph1), an α-Nrxn ligand with restricted expression in subpopulations of inhibitory neurons, is unclear. To reveal its role, we investigated mice that either lack or overexpress Nxph1. We found that genetic deletion of Nxph1 impaired GABAB receptor (GABA(B)R)-dependent short-term depression of inhibitory synapses in the nucleus reticularis thalami, a region where Nxph1 is normally expressed at high levels. To test the conclusion that Nxph1 supports presynaptic GABA(B)R, we expressed Nxph1 ectopically at excitatory terminals in the neocortex, which normally do not contain this molecule but can be modulated by GABA(B)R. We generated Nxph1-GFP transgenic mice under control of the Thy1.2 promoter and observed a reduced short-term facilitation at these excitatory synapses, representing an inverse phenotype to the knockout. Consistently, the diminished facilitation could be reversed by pharmacologically blocking GABA(B)R with CGP-55845. Moreover, a complete rescue was achieved by additional blocking of postsynaptic GABA(A)R with intracellular picrotoxin or gabazine, suggesting that Nxph1 is able to recruit or stabilize both presynaptic GABA(B)R and postsynaptic GABA(A)R. In support, immunoelectron microscopy validated the localization of ectopic Nxph1 at the synaptic cleft of excitatory synapses in transgenic mice and revealed an enrichment of GABA(A)R and GABA(B)R subunits compared with wild-type animals. Thus, our data propose that Nxph1 plays an instructive role in synaptic short-term plasticity and the configuration with GABA receptors.
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Gaier ED, Rodriguiz RM, Zhou J, Ralle M, Wetsel WC, Eipper BA, Mains RE. In vivo and in vitro analyses of amygdalar function reveal a role for copper. J Neurophysiol 2014; 111:1927-39. [PMID: 24554785 DOI: 10.1152/jn.00631.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mice with a single copy of the peptide amidating monooxygenase (Pam) gene (PAM(+/-)) are impaired in contextual and cued fear conditioning. These abnormalities coincide with deficient long-term potentiation (LTP) at excitatory thalamic afferent synapses onto pyramidal neurons in the lateral amygdala. Slice recordings from PAM(+/-) mice identified an increase in GABAergic tone (Gaier ED, Rodriguiz RM, Ma XM, Sivaramakrishnan S, Bousquet-Moore D, Wetsel WC, Eipper BA, Mains RE. J Neurosci 30: 13656-13669, 2010). Biochemical data indicate a tissue-specific deficit in Cu content in the amygdala; amygdalar expression of Atox-1 and Atp7a, essential for transport of Cu into the secretory pathway, is reduced in PAM(+/-) mice. When PAM(+/-) mice were fed a diet supplemented with Cu, the impairments in fear conditioning were reversed, and LTP was normalized in amygdala slice recordings. A role for endogenous Cu in amygdalar LTP was established by the inhibitory effect of a brief incubation of wild-type slices with bathocuproine disulfonate, a highly selective, cell-impermeant Cu chelator. Interestingly, bath-applied CuSO₄ had no effect on excitatory currents but reversibly potentiated the disynaptic inhibitory current. Bath-applied CuSO₄ was sufficient to potentiate wild-type amygdala afferent synapses. The ability of dietary Cu to affect signaling in pathways that govern fear-based behaviors supports an essential physiological role for Cu in amygdalar function at both the synaptic and behavioral levels. This work is relevant to neurological and psychiatric disorders in which disturbed Cu homeostasis could contribute to altered synaptic transmission, including Wilson's, Menkes, Alzheimer's, and prion-related diseases.
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Affiliation(s)
- E D Gaier
- Neuroscience Department, University of Connecticut Health Center, Farmington, Connecticut
| | - R M Rodriguiz
- Department of Psychiatry and Behavioral Sciences, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina
| | - J Zhou
- Department of Psychiatry and Behavioral Sciences, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina
| | - M Ralle
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon
| | - W C Wetsel
- Department of Psychiatry and Behavioral Sciences, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina; Department of Neurobiology, Duke University Medical Center, Durham, North Carolina; and Department of Cell Biology, Duke University Medical Center, Durham, North Carolina
| | - B A Eipper
- Neuroscience Department, University of Connecticut Health Center, Farmington, Connecticut
| | - R E Mains
- Neuroscience Department, University of Connecticut Health Center, Farmington, Connecticut;
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McCool BA, Christian DT, Fetzer JA, Chappell AM. Lateral/basolateral amygdala serotonin type-2 receptors modulate operant self-administration of a sweetened ethanol solution via inhibition of principal neuron activity. Front Integr Neurosci 2014; 8:5. [PMID: 24523680 PMCID: PMC3906593 DOI: 10.3389/fnint.2014.00005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/09/2014] [Indexed: 11/13/2022] Open
Abstract
The lateral/basolateral amygdala (BLA) forms an integral part of the neural circuitry controlling innate anxiety and learned fear. More recently, BLA dependent modulation of self-administration behaviors suggests a much broader role in the regulation of reward evaluation. To test this, we employed a self-administration paradigm that procedurally segregates “seeking” (exemplified as lever-press behaviors) from consumption (drinking) directed at a sweetened ethanol solution. Microinjection of the nonselective serotonin type-2 receptor agonist, alpha-methyl-5-hydroxytryptamine (α-m5HT) into the BLA reduced lever pressing behaviors in a dose-dependent fashion. This was associated with a significant reduction in the number of response-bouts expressed during non-reinforced sessions without altering the size of a bout or the rate of responding. Conversely, intra-BLA α-m5HT only modestly effected consumption-related behaviors; the highest dose reduced the total time spent consuming a sweetened ethanol solution but did not inhibit the total number of licks, number of lick bouts, or amount of solution consumed during a session. In vitro neurophysiological characterization of BLA synaptic responses showed that α-m5HT significantly reduced extracellular field potentials. This was blocked by the 5-HT2A/C antagonist ketanserin suggesting that 5-HT2-like receptors mediate the behavioral effect of α-m5HT. During whole-cell patch current-clamp recordings, we subsequently found that α-m5HT increased action potential threshold and hyperpolarized the resting membrane potential of BLA pyramidal neurons. Together, our findings show that the activation of BLA 5-HT2A/C receptors inhibits behaviors related to reward-seeking by suppressing BLA principal neuron activity. These data are consistent with the hypothesis that the BLA modulates reward-related behaviors and provides specific insight into BLA contributions during operant self-administration of a sweetened ethanol solution.
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Affiliation(s)
- Brian A McCool
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem NC, USA
| | - Daniel T Christian
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem NC, USA
| | - Jonathan A Fetzer
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem NC, USA
| | - Ann M Chappell
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem NC, USA
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Sears RM, Schiff HC, LeDoux JE. Molecular Mechanisms of Threat Learning in the Lateral Nucleus of the Amygdala. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 122:263-304. [DOI: 10.1016/b978-0-12-420170-5.00010-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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34
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Sweeney FF, O’Leary OF, Cryan JF. GABAB receptor ligands do not modify conditioned fear responses in BALB/c mice. Behav Brain Res 2013; 256:151-6. [DOI: 10.1016/j.bbr.2013.07.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 07/21/2013] [Indexed: 01/15/2023]
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35
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Song C, Xu XB, He Y, Liu ZP, Wang M, Zhang X, Li BM, Pan BX. Stuttering interneurons generate fast and robust inhibition onto projection neurons with low capacity of short term modulation in mouse lateral amygdala. PLoS One 2013; 8:e60154. [PMID: 23527307 PMCID: PMC3602081 DOI: 10.1371/journal.pone.0060154] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 02/21/2013] [Indexed: 11/18/2022] Open
Abstract
The stuttering interneurons (STi) represent one minor subset of interneuron population and exhibit characteristic stuttering firing upon depolarization current injection. While it has been long held that the GABAergic inhibitory transmission largely varies with the subtype identity of presynaptic interneurons, whether such a rule also applies to STi is largely unknown. Here, by paired recording of interneuron and their neighboring projection neuron in lateral amygdala, we found that relative to the fast spiking and late spiking interneurons, the STi-evoked unitary postsynaptic currents onto the projection neurons had markedly larger amplitude, shorter onset latency and faster rising and decay kinetics. The quantal content and the number of vesicles in the readily releasable pool were also larger in synapses made by STi versus other interneurons. Moreover, the short-term plasticity, as reflected by the paired pulse depression and depolarization-induced suppression of inhibition, was the least prominent in the output synapses of STi. Thus, the fast and robust inhibition together with its low capacity of short term modulation may suggest an important role for STi in preventing the overexcitation of the projection neurons and thus gating the information traffic in amygdala.
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Affiliation(s)
- Chen Song
- Laboratory of Fear and Anxiety Disorder, Institute of Life Science, Nanchang University, Nanchang, China
| | - Xiao-Bin Xu
- Laboratory of Fear and Anxiety Disorder, Institute of Life Science, Nanchang University, Nanchang, China
| | - Ye He
- Laboratory of Fear and Anxiety Disorder, Institute of Life Science, Nanchang University, Nanchang, China
- Department of Pharmacology, Nanchang University, Nanchang, China
| | - Zhi-Peng Liu
- Laboratory of Fear and Anxiety Disorder, Institute of Life Science, Nanchang University, Nanchang, China
| | - Min Wang
- Laboratory of Fear and Anxiety Disorder, Institute of Life Science, Nanchang University, Nanchang, China
| | - Xin Zhang
- Laboratory of Fear and Anxiety Disorder, Institute of Life Science, Nanchang University, Nanchang, China
| | - Bao-Ming Li
- Laboratory of Fear and Anxiety Disorder, Institute of Life Science, Nanchang University, Nanchang, China
| | - Bing-Xing Pan
- Laboratory of Fear and Anxiety Disorder, Institute of Life Science, Nanchang University, Nanchang, China
- * E-mail:
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Neurogliaform cells dynamically regulate somatosensory integration via synapse-specific modulation. Nat Neurosci 2012; 16:13-5. [PMID: 23222912 DOI: 10.1038/nn.3284] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 11/18/2012] [Indexed: 11/08/2022]
Abstract
Despite the prevailing idea that neurogliaform cells produce a spatially unrestricted widespread inhibition, we demonstrate here that their activity attenuates thalamic-evoked feed-forward inhibition in layer IV barrel cortex but has no effect on feed-forward excitation. The result of this circuit selectivity is a dynamic regulation in the temporal window for integration of excitatory thalamic input, thus revealing a new role for neurogliaform cells in shaping sensory processing.
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Heldt SA, Mou L, Ressler KJ. In vivo knockdown of GAD67 in the amygdala disrupts fear extinction and the anxiolytic-like effect of diazepam in mice. Transl Psychiatry 2012; 2:e181. [PMID: 23149445 PMCID: PMC3565763 DOI: 10.1038/tp.2012.101] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In mammals, γ-aminobutyric acid (GABA) transmission in the amygdala is particularly important for controlling levels of fear and anxiety. Most GABA synthesis in the brain is catalyzed in inhibitory neurons from L-glutamic acid by the enzyme glutamic acid decarboxylase 67 (GAD67). In the current study, we sought to examine the acquisition and extinction of conditioned fear in mice with knocked down expression of the GABA synthesizing enzyme GAD67 in the amygdala using a lentiviral-based (LV) RNA interference strategy to locally induce loss-of-function. In vitro experiments revealed that our LV-siRNA-GAD67 construct diminished the expression of GAD67 as determined with western blot and fluorescent immunocytochemical analyses. In vivo experiments, in which male C57BL/6J mice received bilateral amygdala microinjections, revealed that LV-siRNA-GAD67 injections produce significant inhibition of endogenous GAD67 when compared with control injections. In contrast, no significant changes in GAD65 expression were detected in the amygdala, validating the specificity of LV knockdown. Behavioral experiments showed that LV knockdown of GAD67 results in a deficit in the extinction, but not the acquisition or retention, of fear as measured by conditioned freezing. GAD67 knockdown did not affect baseline locomotion or basal measures of anxiety as measured in open field apparatus. However, diminished GAD67 in the amygdala blunted the anxiolytic-like effect of diazepam (1.5 mg kg(-1)) as measured in the elevated plus maze. Together, these studies suggest that of GABAergic transmission in amygdala mediates the inhibition of conditioned fear and the anxiolytic-like effect of diazepam in adult mice.
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Affiliation(s)
- S A Heldt
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN, USA.
| | - L Mou
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, GA, USA
| | - K J Ressler
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, GA, USA,Howard Hughes Medical Institute, Bethesda, MD, USA
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Bienvenu TCM, Busti D, Magill PJ, Ferraguti F, Capogna M. Cell-type-specific recruitment of amygdala interneurons to hippocampal theta rhythm and noxious stimuli in vivo. Neuron 2012; 74:1059-74. [PMID: 22726836 PMCID: PMC3391683 DOI: 10.1016/j.neuron.2012.04.022] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/27/2012] [Indexed: 11/25/2022]
Abstract
Neuronal synchrony in the basolateral amygdala (BLA) is critical for emotional behavior. Coordinated theta-frequency oscillations between the BLA and the hippocampus and precisely timed integration of salient sensory stimuli in the BLA are involved in fear conditioning. We characterized GABAergic interneuron types of the BLA and determined their contribution to shaping these network activities. Using in vivo recordings in rats combined with the anatomical identification of neurons, we found that the firing of BLA interneurons associated with network activities was cell type specific. The firing of calbindin-positive interneurons targeting dendrites was precisely theta-modulated, but other cell types were heterogeneously modulated, including parvalbumin-positive basket cells. Salient sensory stimuli selectively triggered axo-axonic cells firing and inhibited firing of a disctinct projecting interneuron type. Thus, GABA is released onto BLA principal neurons in a time-, domain-, and sensory-specific manner. These specific synaptic actions likely cooperate to promote amygdalo-hippocampal synchrony involved in emotional memory formation.
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Affiliation(s)
- Thomas C M Bienvenu
- Medical Research Council Anatomical Neuropharmacology Unit, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK.
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39
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Mańko M, Bienvenu TCM, Dalezios Y, Capogna M. Neurogliaform cells of amygdala: a source of slow phasic inhibition in the basolateral complex. J Physiol 2012; 590:5611-27. [PMID: 22930272 DOI: 10.1113/jphysiol.2012.236745] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Synaptic inhibition in the amygdala actively participates in processing emotional information. To improve the understanding of interneurons in amygdala networks it is necessary to characterize the GABAergic cell types, their connectivity and physiological roles. We used a mouse line expressing a green fluorescent protein (GFP) under the neuropeptide Y (NPY) promoter. Paired recordings between presynaptic NPY-GFP-expressing (+) cells and postsynaptic principal neurons (PNs) of the basolateral amygdala (BLA) were performed. The NPY-GFP+ neurons displayed small somata and short dendrites embedded in a cloud of highly arborized axon, suggesting a neurogliaform cell (NGFC) type. We discovered that a NPY-GFP+ cell evoked a GABA(A) receptor-mediated slow inhibitory postsynaptic current (IPSC) in a PN and an autaptic IPSC. The slow kinetics of these IPSCs was likely caused by the low concentration and spillover of extracellular GABA. We also report that NGFCs of the BLA fired action potentials phase-locked to hippocampal theta oscillations in anaesthetized rats. When this firing was re-played in NPY+-NGFCs in vitro, it evoked a transient depression of the IPSCs. Presynaptic GABA(B) receptors and functional depletion of synaptic vesicles determined this short-term plasticity. Synaptic contacts made by recorded NGFCs showed close appositions, and rarely identifiable classical synaptic structures. Thus, we report here a novel interneuron type of the amygdala that generates volume transmission of GABA. The peculiar functional mode of NGFCs makes them unique amongst all GABAergic cell types of the amygdala identified so far.
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Affiliation(s)
- Mirosława Mańko
- MRC Anatomical Neuropharmacology Unit, Mansfield Road, Oxford OX1 3TH, UK
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40
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Mori F, Kusayanagi H, Buttari F, Centini B, Monteleone F, Nicoletti CG, Bernardi G, Di Cantogno EV, Marciani MG, Centonze D. Early treatment with high-dose interferon beta-1a reverses cognitive and cortical plasticity deficits in multiple sclerosis. FUNCTIONAL NEUROLOGY 2012; 27:163-168. [PMID: 23402677 PMCID: PMC3812766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Acute inflammation is associated with cognitive deficits and alterations of cortical plasticity in multiple sclerosis (MS). We tested whether early treatment with high-dose interferon (IFN) beta-1a, known to reduce inflammatory activity, improves cortical function and cognitive deficits in MS. Eighty treatment-naïve relapsing-remitting MS (RRMS)patients received IFN beta-1a (44 mcg) subcutaneously three times per week. Cognitive performance and cortical plasticity were measured through the paced auditory serial addition test (PASAT) and intermittent theta burst stimulation (iTBS) before and up to two years af-ter IFN beta-1a initiation. Before treatment, patients with gadolinium-enhancing lesions (Gd+) on MRI performed worse on the PASAT,and showed lower iTBS-induced plasticity, compared with Gd- patients. Six months after treatment initiation both PASAT and iTBS-induced plasticity improved in Gd+ and remained stable in Gd- patients. These results suggest that cognitive and synaptic plasticity deficits may be rescued during high-doseIFN beta-1a treatment in newly-diagnosed RRMS patients with Gd+ lesions.
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Affiliation(s)
- Francesco Mori
- Correspondence to: Francesco Mori, UOSD CSM, Clinica Neurologica, Policlinico Tor Vergata, Viale Oxford 81, 00133 Rome, Italy, E-mail:
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41
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Gassmann M, Bettler B. Regulation of neuronal GABA(B) receptor functions by subunit composition. Nat Rev Neurosci 2012; 13:380-94. [PMID: 22595784 DOI: 10.1038/nrn3249] [Citation(s) in RCA: 248] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
GABA(B) receptors (GABA(B)Rs) are G protein-coupled receptors for GABA, the main inhibitory neurotransmitter in the CNS. In the past 5 years, notable advances have been made in our understanding of the molecular composition of these receptors. GABA(B)Rs are now known to comprise principal and auxiliary subunits that influence receptor properties in distinct ways. The principal subunits regulate the surface expression and the axonal versus dendritic distribution of these receptors, whereas the auxiliary subunits determine agonist potency and the kinetics of the receptor response. This Review summarizes current knowledge on how the subunit composition of GABA(B)Rs affects the distribution of these receptors, neuronal processes and higher brain functions.
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Affiliation(s)
- Martin Gassmann
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50-70, 4056 Basel, Switzerland.
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42
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Benke D, Zemoura K, Maier PJ. Modulation of cell surface GABA(B) receptors by desensitization, trafficking and regulated degradation. World J Biol Chem 2012; 3:61-72. [PMID: 22558486 PMCID: PMC3342575 DOI: 10.4331/wjbc.v3.i4.61] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Revised: 12/08/2011] [Accepted: 12/15/2011] [Indexed: 02/05/2023] Open
Abstract
Inhibitory neurotransmission ensures normal brain function by counteracting and integrating excitatory activity. γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the mammalian central nervous system, and mediates its effects via two classes of receptors: the GABA(A) and GABA(B) receptors. GABA(A) receptors are heteropentameric GABA-gated chloride channels and responsible for fast inhibitory neurotransmission. GABA(B) receptors are heterodimeric G protein coupled receptors (GPCR) that mediate slow and prolonged inhibitory transmission. The extent of inhibitory neurotransmission is determined by a variety of factors, such as the degree of transmitter release and changes in receptor activity by posttranslational modifications (e.g., phosphorylation), as well as by the number of receptors present in the plasma membrane available for signal transduction. The level of GABA(B) receptors at the cell surface critically depends on the residence time at the cell surface and finally the rates of endocytosis and degradation. In this review we focus primarily on recent advances in the understanding of trafficking mechanisms that determine the expression level of GABA(B) receptors in the plasma membrane, and thereby signaling strength.
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Affiliation(s)
- Dietmar Benke
- Dietmar Benke, Khaled Zemoura, Patrick J Maier, Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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43
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The GABA system in anxiety and depression and its therapeutic potential. Neuropharmacology 2012; 62:42-53. [DOI: 10.1016/j.neuropharm.2011.08.040] [Citation(s) in RCA: 348] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 08/23/2011] [Indexed: 01/01/2023]
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44
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Mori F, Rossi S, Sancesario G, Codecà C, Mataluni G, Monteleone F, Buttari F, Kusayanagi H, Castelli M, Motta C, Studer V, Bernardi G, Koch G, Bernardini S, Centonze D. Cognitive and cortical plasticity deficits correlate with altered amyloid-β CSF levels in multiple sclerosis. Neuropsychopharmacology 2011; 36:559-68. [PMID: 20944553 PMCID: PMC3055691 DOI: 10.1038/npp.2010.187] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Cognitive dysfunction is of frequent observation in multiple sclerosis (MS). It is associated with gray matter pathology, brain atrophy, and altered connectivity, and recent evidence showed that acute inflammation can exacerbate mental deficits independently of the primary functional system involved. In this study, we measured cerebrospinal fluid (CSF) levels of amyloid-β(1-42) and τ protein in MS and in clinically isolated syndrome patients, as both proteins have been associated with cognitive decline in Alzheimer's disease (AD). In AD, amyloid-β(1-42) accumulates in the brain as insoluble extracellular plaques, possibly explaining why soluble amyloid-β(1-42) is reduced in the CSF of these patients. In our sample of MS patients, amyloid-β(1-42) levels were significantly lower in patients cognitively impaired (CI) and were inversely correlated with the number of Gadolinium-enhancing (Gd+) lesions at the magnetic resonance imaging (MRI). Positive correlations between amyloid-β(1-42) levels and measures of attention and concentration were also found. Furthermore, abnormal neuroplasticity of the cerebral cortex, explored with θ burst stimulation (TBS), was observed in CI patients, and a positive correlation was found between amyloid-β(1-42) CSF contents and the magnitude of long-term potentiation-like effects induced by TBS. No correlation was conversely found between τ protein concentrations and MRI findings, cognitive parameters, and TBS effects in these patients. Together, our results indicate that in MS, central inflammation is able to alter amyloid-β metabolism by reducing its concentration in the CSF and leading to impairment of synaptic plasticity and cognitive function.
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Affiliation(s)
- Francesco Mori
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Silvia Rossi
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Giulia Sancesario
- Dipartimento di Medicina Interna, Università Tor Vergata, Rome, Italy,Dipartimento di Medicina di Laboratorio, UOC Biologia Molecolare Clinica, Policlinico Tor Vergata, Rome, Italy
| | - Claudia Codecà
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Giorgia Mataluni
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Fabrizia Monteleone
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Fabio Buttari
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Hajime Kusayanagi
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Maura Castelli
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Caterina Motta
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Valeria Studer
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Giorgio Bernardi
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Giacomo Koch
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy
| | - Sergio Bernardini
- Dipartimento di Medicina Interna, Università Tor Vergata, Rome, Italy,Dipartimento di Medicina di Laboratorio, UOC Biologia Molecolare Clinica, Policlinico Tor Vergata, Rome, Italy
| | - Diego Centonze
- Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, Rome, Italy,Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia, Rome, Italy,Dipartimento di Neuroscienze, Clinica Neurologica, Università Tor Vergata, via Montpellier 1, Rome 00133, Italy, Tel: +39 067 259 6010, Fax: +39 067 259 6006, E-mail:
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46
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Zschenderlein C, Gebhardt C, von Bohlen und Halbach O, Kulisch C, Albrecht D. Capsaicin-induced changes in LTP in the lateral amygdala are mediated by TRPV1. PLoS One 2011; 6:e16116. [PMID: 21249195 PMCID: PMC3020947 DOI: 10.1371/journal.pone.0016116] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 12/14/2010] [Indexed: 01/15/2023] Open
Abstract
The transient receptor potential vanilloid type 1 (TRPV1) channel is a well recognized polymodal signal detector that is activated by painful stimuli such as capsaicin. Here, we show that TRPV1 is expressed in the lateral nucleus of the amygdala (LA). Despite the fact that the central amygdala displays the highest neuronal density, the highest density of TRPV1 labeled neurons was found within the nuclei of the basolateral complex of the amygdala. Capsaicin specifically changed the magnitude of long-term potentiation (LTP) in the LA in brain slices of mice depending on the anesthetic (ether, isoflurane) used before euthanasia. After ether anesthesia, capsaicin had a suppressive effect on LA-LTP both in patch clamp and in extracellular recordings. The capsaicin-induced reduction of LTP was completely blocked by the nitric oxide synthase (NOS) inhibitor L-NAME and was absent in neuronal NOS as well as in TRPV1 deficient mice. The specific antagonist of cannabinoid receptor type 1 (CB1), AM 251, was also able to reduce the inhibitory effect of capsaicin on LA-LTP, suggesting that stimulation of TRPV1 provokes the generation of anandamide in the brain which seems to inhibit NO synthesis. After isoflurane anesthesia before euthanasia capsaicin caused a TRPV1-mediated increase in the magnitude of LA-LTP. Therefore, our results also indicate that the appropriate choice of the anesthetics used is an important consideration when brain plasticity and the action of endovanilloids will be evaluated. In summary, our results demonstrate that TRPV1 may be involved in the amygdala control of learning mechanisms.
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Affiliation(s)
- Carsten Zschenderlein
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, CVK, Berlin, Germany
| | - Christine Gebhardt
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, CVK, Berlin, Germany
| | | | - Christoph Kulisch
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, CVK, Berlin, Germany
| | - Doris Albrecht
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, CVK, Berlin, Germany
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47
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Popescu AT, Paré D. Synaptic interactions underlying synchronized inhibition in the basal amygdala: evidence for existence of two types of projection cells. J Neurophysiol 2010; 105:687-96. [PMID: 21084688 DOI: 10.1152/jn.00732.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The basal amygdala (BA) plays a key role in mediating the facilitating effects of emotions on memory. Recent findings indicate that this function depends on the ability of BA neurons to generate coherent oscillatory activity, facilitating synaptic plasticity in target neurons. However, the mechanisms allowing BA neurons to synchronize their activity remain poorly understood. Here, we aimed to shed light on this question, focusing on a slow periodic inhibitory oscillation previously observed in the BA in vitro. Paired patch recordings showed that these large inhibitory postsynaptic potentials (IPSPs) occur almost synchronously in BA projection neurons, that they were typically not preceded by excitatory postsynaptic potentials (EPSPs), and that they had little or no correlate in neighboring amygdala nuclei or cortical fields. The initial phase of the IPSPs was associated with an increase in membrane potential fluctuations at 50-100 Hz. In keeping with this, the IPSPs seen in projection cells were correlated with repetitive firing at 50-100 Hz in presumed interneurons and they could be abolished by picrotoxin. However, the IPSPs were also sensitive to 6-cyano-7-nitroquinoxaline-2,3-dione, implying that they arose from the interplay between glutamatergic and GABAergic BA neurons. In support of this idea, we identified a small subset of projection cells (15%), positively identified as such by retrograde labeling from BA projection sites, that began firing shortly before the IPSP onset and presumably drove interneuronal firing. These results add to a rapidly growing body of data indicating that the BA contains at least two distinct types of projection cells that vary in their relation with interneurons and extra-amygdala targets.
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Affiliation(s)
- Andrei T Popescu
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, Newark, New Jersey 07102, USA
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Haploinsufficiency in peptidylglycine alpha-amidating monooxygenase leads to altered synaptic transmission in the amygdala and impaired emotional responses. J Neurosci 2010; 30:13656-69. [PMID: 20943906 DOI: 10.1523/jneurosci.2200-10.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The mammalian amygdala expresses various neuropeptides whose signaling has been implicated in emotionality. Many neuropeptides require amidation for full activation by peptidylglycine α-amidating monooxygenase (PAM), a transmembrane vesicular cuproenzyme and regulator of the secretory pathway. Mice heterozygous for the Pam gene (PAM(+/-)) exhibit physiological and behavioral abnormalities related to specific peptidergic pathways. In the present study, we evaluated emotionality and examined molecular and cellular responses that characterize neurophysiological differences in the PAM(+/-) amygdala. PAM(+/-) mice presented with anxiety-like behaviors in the zero maze that were alleviated by diazepam. PAM(+/-) animals were deficient in short- and long-term contextual and cued fear conditioning and required higher shock intensities to establish fear-potentiated startle than their wild-type littermates. Immunohistochemical analysis of the amygdala revealed PAM expression in pyramidal neurons and local interneurons that synthesize GABA. We performed whole-cell recordings of pyramidal neurons in the PAM(+/-) amygdala to elucidate neurophysiological correlates of the fear behavioral phenotypes. Consistent with these observations, thalamic afferent synapses in the PAM(+/-) lateral nucleus were deficient in long-term potentiation. This deficit was apparent in the absence and presence of the GABA(A) receptor antagonist picrotoxin and was abolished when both GABA(A) and GABA(B) receptors were blocked. Both evoked and spontaneous excitatory signals were enhanced in the PAM(+/-) lateral nucleus. Phasic GABAergic signaling was also augmented in the PAM(+/-) amygdala, and this difference comprised activity-independent and -dependent components. These physiological findings represent perturbations in the PAM(+/-) amygdala that may underlie the aberrant emotional responses in the intact animal.
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Maier PJ, Marin I, Grampp T, Sommer A, Benke D. Sustained glutamate receptor activation down-regulates GABAB receptors by shifting the balance from recycling to lysosomal degradation. J Biol Chem 2010; 285:35606-14. [PMID: 20826795 DOI: 10.1074/jbc.m110.142406] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Metabotropic GABA(B) receptors are abundantly expressed at glutamatergic synapses where they control excitability of the synapse. Here, we tested the hypothesis that glutamatergic neurotransmission may regulate GABA(B) receptors. We found that application of glutamate to cultured cortical neurons led to rapid down-regulation of GABA(B) receptors via lysosomal degradation. This effect was mimicked by selective activation of AMPA receptors and further accelerated by coactivation of group I metabotropic glutamate receptors. Inhibition of NMDA receptors, blockade of L-type Ca(2+) channels, and removal of extracellular Ca(2+) prevented glutamate-induced down-regulation of GABA(B) receptors, indicating that Ca(2+) influx plays a critical role. We further established that glutamate-induced down-regulation depends on the internalization of GABA(B) receptors. Glutamate did not affect the rate of GABA(B) receptor endocytosis but led to reduced recycling of the receptors back to the plasma membrane. Blockade of lysosomal activity rescued receptor recycling, indicating that glutamate redirects GABA(B) receptors from the recycling to the degradation pathway. In conclusion, the data indicate that sustained activation of AMPA receptors down-regulates GABA(B) receptors by sorting endocytosed GABA(B) receptors preferentially to lysosomes for degradation on the expense of recycling. This mechanism may relieve glutamatergic synapses from GABA(B) receptor-mediated inhibition resulting in increased synaptic excitability.
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Affiliation(s)
- Patrick J Maier
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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50
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The mammalian interaural time difference detection circuit is differentially controlled by GABAB receptors during development. J Neurosci 2010; 30:9715-27. [PMID: 20660254 DOI: 10.1523/jneurosci.1552-10.2010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Throughout development GABA(B) receptors (GABA(B)Rs) are widely expressed in the mammalian brain. In mature auditory brainstem neurons, GABA(B)Rs are involved in the short-term regulation of the strength and dynamics of excitatory and inhibitory inputs, thus modulating sound analysis. During development, GABA(B)Rs also contribute to long-term changes in input strength. Using a combination of whole-cell patch-clamp recordings in acute brain slices and immunostainings in gerbils, we characterized developmental changes in GABA(B)R-mediated regulation of synaptic inputs to neurons in the medial superior olive (MSO), an auditory brainstem nucleus that analyzes interaural time differences (ITDs). Here, we show that, before hearing onset, GABA(B)R-mediated depression of transmitter release is much stronger for excitation than inhibition, whereas in mature animals GABA(B)Rs mainly control the inhibition. During the same developmental period, GABA(B)R immunoreactivity shifts from the dendritic to the somatic region of the MSO. Furthermore, only before hearing onset (postnatal day 12), stimulation of the fibers originating in the medial and the lateral nucleus of the trapezoid body (MNTB and LNTB) activates GABA(B)Rs on both the inhibitory and the excitatory inputs. After hearing onset, GAD65-positive endings devoid of glycine transporter reactivity suggest GABA release from sources other than the MNTB and LNTB. At this age, pharmacological increase of spontaneous synaptic release activates GABA(B)Rs only on the inhibitory inputs. This indicates not only a profound inhibitory effect of GABA(B)Rs on the major inputs to MSO neurons in neonatal animals but also a direct modulatory role of GABA(B)Rs for ITD analysis in the MSO of adult animals.
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