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Gos A, Steiner J, Trübner K, Ungewickell J, Mawrin C, Karnecki K, Kaliszan M, Gos T. Inverse pattern of GABAergic system impairment in the external versus internal globus pallidus in male heroin addicts. Eur Arch Psychiatry Clin Neurosci 2024; 274:445-452. [PMID: 37507486 PMCID: PMC10914887 DOI: 10.1007/s00406-023-01656-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023]
Abstract
Opioid addiction is a global problem that has been exacerbated in the USA and Europe by the COVID-19 pandemic. The globus pallidus (GP) plays a prominent neurobiological role in the regulation of behaviour as an output station of the striato-pallidal system. GABAergic large projection neurons are the main neuronal type in the external (EGP) and internal (IGP) parts of the GP, where addiction-specific molecular and functional abnormalities occur. In these neurons, glutamate decarboxylase (GAD) with isoforms GAD 65 and 67 is a key enzyme in GABA synthesis, and experimental studies suggest GAD dysregulation in the GP of heroin addicts. Our study, which was performed on paraffin-embedded brains from the Magdeburg Brain Bank, aimed to investigate abnormalities in the GABAergic function of large GP neurons by densitometric evaluation of their GAD 65/67-immunostained thick dendrites. The study revealed a bilaterally decreased fibres density in the EGP paralleled by the increase in the IGP in 11 male heroin addicts versus 11 healthy controls (significant U-test P values). The analysis of confounding variables found no interference of age, brain volume, and duration of formalin fixation with the results. Our findings suggest a dysregulation of GABAergic activity in the GP of heroin addicts, which is consistent with experimental data from animal models and plays potentially a role in the disturbed function of basal ganglia circuit in opioid addiction.
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Affiliation(s)
- Anna Gos
- Department of Psychiatry, Otto Von Guericke University, Magdeburg, Germany
| | - Johann Steiner
- Department of Psychiatry, Otto Von Guericke University, Magdeburg, Germany
| | - Kurt Trübner
- Institute of Legal Medicine, University of Duisburg-Essen, Essen, Germany
| | - Jonas Ungewickell
- Department of Psychiatry, Otto Von Guericke University, Magdeburg, Germany
| | - Christian Mawrin
- Department of Neuropathology, Otto Von Guericke University, Magdeburg, Germany
| | - Karol Karnecki
- Department of Forensic Medicine, Medical University of Gdańsk, Ul. Dębowa 23, 80-204, Gdańsk, Poland
| | - Michał Kaliszan
- Department of Forensic Medicine, Medical University of Gdańsk, Ul. Dębowa 23, 80-204, Gdańsk, Poland
| | - Tomasz Gos
- Department of Psychiatry, Otto Von Guericke University, Magdeburg, Germany.
- Department of Forensic Medicine, Medical University of Gdańsk, Ul. Dębowa 23, 80-204, Gdańsk, Poland.
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2
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Henderson TT, Taylor JL, Thorstensen JR, Tucker MG, Kavanagh JJ. Enhanced availability of serotonin limits muscle activation during high-intensity, but not low-intensity, fatiguing contractions. J Neurophysiol 2022; 128:751-762. [PMID: 36001790 DOI: 10.1152/jn.00182.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Serotonin (5-HT) modulates motoneuron excitability during muscle contractions, where the release of 5-HT in the central nervous system (CNS) is linked to the intensity of physical activity. Although there is evidence that enhanced availability of 5-HT can exacerbate fatigue, these effects on the development of fatigue during different contraction intensities are largely unknown. The purpose of this study was to investigate how enhanced 5-HT availability affects voluntary muscle activation and corticospinal excitability during fatigue-inducing contractions. Two experiments were performed. In the first experiment (n = 11), twelve isometric elbow flexions at 20% maximal voluntary contractions (MVC) were performed for 2-min each with 40-s rest periods. In the second experiment (n = 14), twelve maximal isometric elbow flexions were held for 10-s each with 40-s rest periods. In both experiments, the selective serotonin reuptake inhibitor (20 mg paroxetine), or a placebo, was administered in a two-way crossover-design. Muscle responses to transcranial magnetic stimulation (TMS) of the motor cortex (both experiments 1 and 2), as well as motor point stimulation of the elbow flexors (experiment 2) were assessed. Paroxetine reduced both motor cortical (p = 0.018) and motor point voluntary activation (p = 0.036) during the maximal contraction protocol. Paroxetine also reduced exercise-induced lengthening of the TMS silent period during the submaximal (p = 0.037) and maximal (p = 0.002) contraction protocols. Activation of inhibitory 5-HT1A receptors on motoneurons likely exacerbated exercise-induced reductions in voluntarily drive to the elbow flexors. However, 5-HT modulation of motor activity also appeared at the supraspinal level.
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Affiliation(s)
- Tyler T Henderson
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Janet L Taylor
- School of Medical and Health Sciences, Edith Cowan University, Perth, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Jacob R Thorstensen
- Child Health Research Centre, The University of Queensland, Brisbane, Australia
| | - Murray G Tucker
- Barwon Health, University Hospital Geelong, Geelong, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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3
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Qi W, Fu H, Luo X, Ren Y, Liu X, Dai H, Zheng Q, Liang F. Electroacupuncture at PC6 (Neiguan) Attenuates Angina Pectoris in Rats with Myocardial Ischemia-Reperfusion Injury Through Regulating the Alternative Splicing of the Major Inhibitory Neurotransmitter Receptor GABRG2. J Cardiovasc Transl Res 2022; 15:1176-1191. [PMID: 35377129 DOI: 10.1007/s12265-022-10245-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 03/25/2022] [Indexed: 11/27/2022]
Abstract
Angina pectoris is the most common manifestation of coronary heart disease, causing suffering in patients. Electroacupuncture at PC6 can effectively alleviate angina by regulating the expression of genes, whether the alternative splicing (AS) of genes is affected by acupuncture is still unknown. We established a rat model of myocardial ischemia-reperfusion by coronary artery ligation and confirmed electroacupuncture alleviated the abnormal discharge caused by angina pectoris measured in EMG electromyograms. Analysis of the GSE61840 dataset established that AS events were altered after I/R and regulated by electroacupuncture. I/R decreased the expression of splicing factor Nova1 while electroacupuncture rescued it. Further experiments in dorsal root ganglion cells showed Nova1 regulated the AS of the GABRG2, specifically on its exon 9 where an important phosphorylation site is present. In vivo, results also showed that electroacupuncture can restore AS of GABRG2. Our results proved that electroacupuncture alleviates angina results by regulating alternative splicing.
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Affiliation(s)
- Wenchuan Qi
- Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, Sichuan, China
| | - Hongjuan Fu
- Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, Sichuan, China
| | - Xinye Luo
- Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, Sichuan, China
| | - Yanrong Ren
- Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, Sichuan, China.,Shanxi University of Traditional Chinese Medicine, Jinzhong, 030002, Shanxi, China
| | - Xueying Liu
- Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, Sichuan, China.,Shanxi University of Traditional Chinese Medicine, Jinzhong, 030002, Shanxi, China
| | - Hongyuan Dai
- College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China
| | - Qianhua Zheng
- Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, Sichuan, China
| | - Fanrong Liang
- Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, Sichuan, China.
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4
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Park TIH, Waldvogel HJ, Montgomery JM, Mee EW, Bergin PS, Faull RLM, Dragunow M, Curtis MA. Identifying Neural Progenitor Cells in the Adult Human Brain. Methods Mol Biol 2022; 2389:125-154. [PMID: 34558008 DOI: 10.1007/978-1-0716-1783-0_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The discovery, in 1998, that the adult human brain contains at least two populations of progenitor cells and that progenitor cells are upregulated in response to a range of degenerative brain diseases has raised hopes for their use in replacing dying brain cells. Since these early findings, the race has been on to understand the biology of progenitor cells in the human brain, and they have now been isolated and studied in many major neurodegenerative diseases. Before these cells can be exploited for cell replacement purposes, it is important to understand how to (1) locate them, (2) label them, (3) determine what receptors they express, (4) isolate them, and (5) examine their electrophysiological properties when differentiated. In this chapter we have described the methods we use for studying progenitor cells in the adult human brain and in particular the tissue processing, immunohistochemistry, autoradiography, progenitor cell culture, and electrophysiology on brain cells. The Neurological Foundation of New Zealand Human Brain Bank has been receiving human tissue for approximately 25 years during which time we have developed a number of unique ways to examine and isolate progenitor cells from resected surgical specimens as well as from postmortem brain tissue. There are ethical and technical considerations that are unique to working with human brain tissue, and these, as well as the processing of this tissue and the culturing of it for the purpose of studying progenitor cells, are the topic of this chapter.
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Affiliation(s)
- Thomas I H Park
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Henry J Waldvogel
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.,Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Johanna M Montgomery
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.,Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Edward W Mee
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.,Department of Neurosurgery, Auckland City Hospital, Auckland, New Zealand
| | - Peter S Bergin
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.,Department of Neurology, Auckland City Hospital, Auckland, New Zealand
| | - Richard L M Faull
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.,Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Mike Dragunow
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Maurice A Curtis
- Centre for Brain Research, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand. .,Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.
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Purves-Tyson TD, Brown AM, Weissleder C, Rothmond DA, Shannon Weickert C. Reductions in midbrain GABAergic and dopamine neuron markers are linked in schizophrenia. Mol Brain 2021; 14:96. [PMID: 34174930 PMCID: PMC8235806 DOI: 10.1186/s13041-021-00805-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 06/07/2021] [Indexed: 01/16/2023] Open
Abstract
Reductions in the GABAergic neurotransmitter system exist across multiple brain regions in schizophrenia and encompass both pre- and postsynaptic components. While reduced midbrain GABAergic inhibitory neurotransmission may contribute to the hyperdopaminergia thought to underpin psychosis in schizophrenia, molecular changes consistent with this have not been reported. We hypothesised that reduced GABA-related molecular markers would be found in the midbrain of people with schizophrenia and that these would correlate with dopaminergic molecular changes. We hypothesised that downregulation of inhibitory neuron markers would be exacerbated in schizophrenia cases with high levels of neuroinflammation. Eight GABAergic-related transcripts were measured with quantitative PCR, and glutamate decarboxylase (GAD) 65/67 and GABAA alpha 3 (α3) (GABRA3) protein were measured with immunoblotting, in post-mortem midbrain (28/28 and 28/26 control/schizophrenia cases for mRNA and protein, respectively), and analysed by both diagnosis and inflammatory subgroups (as previously defined by higher levels of four pro-inflammatory cytokine transcripts). We found reductions (21 – 44%) in mRNA encoding both presynaptic and postsynaptic proteins, vesicular GABA transporter (VGAT), GAD1, and parvalbumin (PV) mRNAs and four alpha subunits (α1, α2, α3, α5) of the GABAA receptor in people with schizophrenia compared to controls (p < 0.05). Gene expression of somatostatin (SST) was unchanged (p = 0.485). We confirmed the reduction in GAD at the protein level (34%, p < 0.05). When stratifying by inflammation, only GABRA3 mRNA exhibited more pronounced changes in high compared to low inflammatory subgroups in schizophrenia. GABRA3 protein was expressed by 98% of tyrosine hydroxylase-positive neurons and was 23% lower in schizophrenia, though this did not reach statistical significance (p > 0.05). Expression of transcripts for GABAA receptor alpha subunits 2 and 3 (GABRA2, GABRA3) were positively correlated with tyrosine hydroxylase (TH) and dopamine transporter (DAT) transcripts in schizophrenia cases (GABRA2; r > 0.630, GABRA3; r > 0.762, all p < 0.001) but not controls (GABRA2; r < − 0.200, GABRA3; r < 0.310, all p > 0.05). Taken together, our results support a profound disruption to inhibitory neurotransmission in the substantia nigra regardless of inflammatory status, which provides a potential mechanism for disinhibition of nigrostriatal dopamine neurotransmission.
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Affiliation(s)
- Tertia D Purves-Tyson
- Schizophrenia Research Laboratory, Neuroscience Research Australia, 139 Barker Street, Margarete Ainsworth Building, Level 5, Randwick, NSW, 2031, Australia. .,School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - Amelia M Brown
- Schizophrenia Research Laboratory, Neuroscience Research Australia, 139 Barker Street, Margarete Ainsworth Building, Level 5, Randwick, NSW, 2031, Australia
| | - Christin Weissleder
- Schizophrenia Research Laboratory, Neuroscience Research Australia, 139 Barker Street, Margarete Ainsworth Building, Level 5, Randwick, NSW, 2031, Australia
| | - Debora A Rothmond
- Schizophrenia Research Laboratory, Neuroscience Research Australia, 139 Barker Street, Margarete Ainsworth Building, Level 5, Randwick, NSW, 2031, Australia
| | - Cynthia Shannon Weickert
- Schizophrenia Research Laboratory, Neuroscience Research Australia, 139 Barker Street, Margarete Ainsworth Building, Level 5, Randwick, NSW, 2031, Australia. .,School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, NSW, 2052, Australia. .,Department of Neuroscience & Physiology, Upstate Medical University, Syracuse, NY, 13210, USA.
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6
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Lee TJ, Zanello AF, Morrison TR, Ricci LA, Melloni RH. Valproate selectively suppresses adolescent anabolic/androgenic steroid-induced aggressive behavior: implications for a role of hypothalamic γ-aminobutyric acid neural signaling. Behav Pharmacol 2021; 32:295-307. [PMID: 33595952 DOI: 10.1097/fbp.0000000000000616] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Pubertal male Syrian hamsters (Mesocricetus auratus) treated with anabolic/androgenic steroids (AASs) during adolescence (P27-P56) display a highly intense aggressive phenotype that shares many behavioral similarities with pathological aggression in youth. Anticonvulsant drugs like valproate that enhance the activity of the γ-aminobutyric acid (GABA) neural system in the brain have recently gained acceptance as a primary treatment for pathological aggression. This study examined whether valproate would selectively suppress adolescent AAS-induced aggressive behavior and whether GABA neural signaling through GABAA subtype receptors in the latero-anterior hypothalamus (LAH; an area of convergence for developmental and neuroplastic changes that underlie aggression in hamsters) modulate the aggression-suppressing effect of this anticonvulsant medication. Valproate (1.0-10.0 mg/kg, intraperitoneal) selectively suppressed the aggressive phenotype in a dose-dependent fashion, with the effective anti-aggressive effects beginning at 5 mg/kg, intraperitoneally. Microinfusion of the GABAA receptor antagonist bicuculline (7.0-700 ng) into the LAH reversed valproate's suppression of AAS-induced aggression in a dose-dependent fashion. At the 70 ng dose of bicuculline, animals expressed the highly aggressive baseline phenotype normally observed in AAS-treated animals. These studies provide preclinical evidence that the anticonvulsant valproate selectively suppresses adolescent, AAS-induced aggression and that this suppression is modulated, in part, by GABA neural signaling within the LAH.
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Affiliation(s)
- Terrence J Lee
- Program in Behavioral Neuroscience, Department of Psychology, Northeastern University, Boston, Massachusetts, USA
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7
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Zeugin D, Ionta S. Anatomo-Functional Origins of the Cortical Silent Period: Spotlight on the Basal Ganglia. Brain Sci 2021; 11:705. [PMID: 34071742 PMCID: PMC8227635 DOI: 10.3390/brainsci11060705] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/17/2021] [Accepted: 05/25/2021] [Indexed: 02/06/2023] Open
Abstract
The so-called cortical silent period (CSP) refers to the temporary interruption of electromyographic signal from a muscle following a motor-evoked potential (MEP) triggered by transcranial magnetic stimulation (TMS) over the primary motor cortex (M1). The neurophysiological origins of the CSP are debated. Previous evidence suggests that both spinal and cortical mechanisms may account for the duration of the CSP. However, contextual factors such as cortical fatigue, experimental procedures, attentional load, as well as neuropathology can also influence the CSP duration. The present paper summarizes the most relevant evidence on the mechanisms underlying the duration of the CSP, with a particular focus on the central role of the basal ganglia in the "direct" (excitatory), "indirect" (inhibitory), and "hyperdirect" cortico-subcortical pathways to manage cortical motor inhibition. We propose new methods of interpretation of the CSP related, at least partially, to the inhibitory hyperdirect and indirect pathways in the basal ganglia. This view may help to explain the respective shortening and lengthening of the CSP in various neurological disorders. Shedding light on the complexity of the CSP's origins, the present review aims at constituting a reference for future work in fundamental research, technological development, and clinical settings.
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Affiliation(s)
| | - Silvio Ionta
- Sensory-Motor Laboratory (SeMoLa), Jules-Gonin Eye Hospital/Fondation Asile des Aveugles, Department of Ophthalmology, University of Lausanne, 1002 Lausanne, Switzerland
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8
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Ferdinand JM, Peters KZ, Yavas E, Young AMJ. Modulation of stimulated dopamine release in rat nucleus accumbens shell by GABA in vitro: Effect of sub-chronic phencyclidine pretreatment. J Neurosci Res 2021; 99:1885-1901. [PMID: 33848365 DOI: 10.1002/jnr.24843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 02/25/2021] [Accepted: 03/21/2021] [Indexed: 01/24/2023]
Abstract
Dopamine signaling in nucleus accumbens (NAc) is modulated by γ-aminobutyric acid (GABA), acting through GABA-A and GABA-B receptors: dysregulation of GABAergic control of dopamine function may be important in behavioral deficits in schizophrenia. We investigated the effect of GABA-A (muscimol) and GABA-B (baclofen) receptor agonists on electrically stimulated dopamine release. Furthermore, we explored whether drug-induced changes were disrupted by pretreatment with phencyclidine, which provides a well-validated model of schizophrenia. Using brain slices from female rats, fast-scan cyclic voltammetry was used to measure electrically stimulated dopamine release in NAc shell. Both muscimol and baclofen caused concentration-dependent attenuation of evoked dopamine release: neither effect was changed by dihydro-β-erythroidine, a nicotinic acetylcholine receptor antagonist, or the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), precluding indirect mechanisms using these transmitter systems in the GABAergic actions. In slices taken from rats pretreated with phencyclidine, the attenuation of evoked dopamine release by baclofen was abolished, but the attenuation by muscimol was unaffected. Since phencyclidine pretreatment was followed by drug-free washout period of at least a week, the drug was not present during recording. Therefore, disruption of GABA-B modulation of dopamine is due to long-term functional changes resulting from the treatment, rather than transient changes due to the drug's presence at test. This enduring dysregulation of GABA-B modulation of accumbal dopamine release provides a plausible mechanism through which GABA dysfunction influences accumbal dopamine leading to behavioral changes seen in schizophrenia and may provide a route for novel therapeutic strategies to treat the condition.
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Affiliation(s)
| | - Kate Z Peters
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, LE1 9HN, UK
| | - Ersin Yavas
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, LE1 9HN, UK
| | - Andrew M J Young
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, LE1 9HN, UK
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9
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Subcortical atrophy correlates with the perturbational complexity index in patients with disorders of consciousness. Brain Stimul 2020; 13:1426-1435. [PMID: 32717393 DOI: 10.1016/j.brs.2020.07.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 05/26/2020] [Accepted: 07/21/2020] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The complexity of neurophysiological brain responses to direct cortical stimulation, referred to as the perturbational complexity index (PCI), has been shown able to discriminate between consciousness and unconsciousness in patients surviving severe brain injury as well as several other conditions (e.g., wake, dreamless sleep, sleep and ketamine dreaming, anesthesia). OBJECTIVE This study asks whether, in patients with a disorder of consciousness (DOC), the complexity of the neurophysiological response to cortical stimulation is preferentially associated with atrophy within specific brain structures. METHODS We perform a retrospective analysis of 40 DOC patients and correlate their maximal PCI to MR-based measurements of cortical thinning and subcortical atrophy. RESULTS PCI was systematically and inversely associated with the degree of local atrophy within the globus pallidus, a region previously linked to electrocortical and behavioral arousal. Conversely, we fail to detect any association between variance in cortical ribbon thickness and PCI. CONCLUSION These findings corroborate the previously reported association between pallidal atrophy and low behavioral arousal and suggest that this region's role in maintaining the overall balance of excitation and inhibition may critically affect the emergence of complex cortical interactions in chronic disorders of consciousness. This finding thus also suggests a target for potential neuromodulatory intervention in DOC patients.
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10
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GABA B receptors: modulation of thalamocortical dynamics and synaptic plasticity. Neuroscience 2020; 456:131-142. [PMID: 32194227 DOI: 10.1016/j.neuroscience.2020.03.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 01/03/2023]
Abstract
GABAB-receptors (GABAB-Rs) are metabotropic, G protein-coupled receptors for the neurotransmitter GABA. Their activation induces slow inhibitory control of the neuronal excitability mediated by pre- and postsynaptic inhibition. Presynaptically GABAB-Rs reduce GABA and glutamate release inhibiting presynaptic Ca2+ channels in both inhibitory and excitatory synapses while postsynaptic GABAB-Rs induce robust slow hyperpolarization by the activation of K+ channels. GABAB-Rs are activated by non-synaptic or volume transmission, which requires high levels of GABA release, either by the simultaneous discharge of GABAergic interneurons or very intense discharges in the thalamus or by means of the activation of a neurogliaform interneurons in the cortex. The main receptor subunits GABAB1a, GABAB1b and GABAB2 are strongly expressed in neurons and glial cells throughout the central nervous system and GABAB-R activation is related to many neuronal processes such as the modulation of rhythmic activity in several brain regions. In the thalamus, GABAB-Rs modulate the generation of the main thalamic rhythm, spindle waves. In the cerebral cortex, GABAB-Rs also modulate the most prominent emergent oscillatory activity-slow oscillations-as well as faster oscillations like gamma frequency. Further, recent studies evaluating the complexity expressed by the cortical network, a parameter associated with consciousness levels, have found that GABAB-Rs enhance this complexity, while their blockade decreases it. This review summarizes the current results on how the activation of GABAB-Rs affects the interchange of information between brain areas by controlling rhythmicity as well as synaptic plasticity.
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11
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Murray SJ, Black BL, Reid SJ, Rudiger SR, Simon Bawden C, Snell RG, Waldvogel HJ, Faull RL. Chemical neuroanatomy of the substantia nigra in the ovine brain. J Chem Neuroanat 2019; 97:43-56. [DOI: 10.1016/j.jchemneu.2019.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 01/17/2019] [Accepted: 01/18/2019] [Indexed: 01/20/2023]
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12
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Inhibition of Nigrostriatal Dopamine Release by Striatal GABA A and GABA B Receptors. J Neurosci 2018; 39:1058-1065. [PMID: 30541909 PMCID: PMC6363932 DOI: 10.1523/jneurosci.2028-18.2018] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 11/07/2018] [Accepted: 11/15/2018] [Indexed: 01/22/2023] Open
Abstract
Nigrostriatal dopamine (DA) is critical to action selection and learning. Axonal DA release is locally influenced by striatal neurotransmitters. Striatal neurons are principally GABAergic projection neurons and interneurons, and a small minority of other neurons are cholinergic interneurons (ChIs). ChIs strongly gate striatal DA release via nicotinic receptors (nAChRs) identified on DA axons. Striatal GABA is thought to modulate DA, but GABA receptors have not been documented conclusively on DA axons. However, ChIs express GABA receptors and are therefore candidates for potential mediators of GABA regulation of DA. We addressed whether striatal GABA and its receptors can modulate DA release directly, independently from ChI regulation, by detecting DA in striatal slices from male mice using fast-scan cyclic voltammetry in the absence of nAChR activation. DA release evoked by single electrical pulses in the presence of the nAChR antagonist dihydro-β-erythroidine was reduced by GABA or agonists of GABAA or GABAB receptors, with effects prevented by selective GABA receptor antagonists. GABA agonists slightly modified the frequency sensitivity of DA release during short stimulus trains. GABA agonists also suppressed DA release evoked by optogenetic stimulation of DA axons. Furthermore, antagonists of GABAA and GABAB receptors together, or GABAB receptors alone, significantly enhanced DA release evoked by either optogenetic or electrical stimuli. These results indicate that striatal GABA can inhibit DA release through GABAA and GABAB receptors and that these actions are not mediated by cholinergic circuits. Furthermore, these data reveal that there is a tonic inhibition of DA release by striatal GABA operating through predominantly GABAB receptors.SIGNIFICANCE STATEMENT The principal inhibitory transmitter in the mammalian striatum, GABA, is thought to modulate striatal dopamine (DA) release, but definitive evidence for GABA receptors on DA axons is lacking. Striatal cholinergic interneurons regulate DA release via axonal nicotinic receptors (nAChRs) and also express GABA receptors, but they have not been eliminated as potentially critical mediators of DA regulation by GABA. Here, we found that GABAA and GABAB receptors inhibit DA release without requiring cholinergic interneurons. Furthermore, ambient levels of GABA inhibited DA release predominantly through GABAB receptors. These findings provide further support for direct inhibition of DA release by GABA receptors and reveal that striatal GABA operates a tonic inhibition on DA output that could critically influence striatal output.
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13
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Dieriks BV, Dean JM, Aronica E, Waldvogel HJ, Faull RLM, Curtis MA. Differential Fatty Acid-Binding Protein Expression in Persistent Radial Glia in the Human and Sheep Subventricular Zone. Dev Neurosci 2018; 40:145-161. [PMID: 29680832 DOI: 10.1159/000487633] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 01/18/2018] [Indexed: 01/19/2023] Open
Abstract
Fatty acid-binding proteins (FABPs) are a family of transport proteins that facilitate intracellular transport of fatty acids. Despite abundant expression in the brain, the role that FABPs play in the process of cell proliferation and migration in the subventricular zone (SVZ) remains unclear. Our results provide a detailed characterisation of FABP3, 5, and 7 expression in adult and fetal human and sheep SVZ. High FABP5 expression was specifically observed in the adult human SVZ and co-labelled with polysialylated neural cell adhesion molecule (PSA-NCAM), glial fibrillary acidic protein (GFAP), GFAPδ, and proliferating cell nuclear antigen (PCNA), indicating a role for FABP5 throughout the full maturation process of astrocytes and neuroblasts. Some FABP5+ cells had a radial glial-like appearance and co-labelled with the radial glia markers vimentin (40E-C) and GFAP. In the fetal human brain, FABP5 was expressed by radial glia cells throughout the ventricular zone. In contrast, radial glia-like cells in sheep highly expressed FABP3. Taken together, these differences highlight the species-specific expression profile of FABPs in the SVZ. In this study, we demonstrate the distribution of FABP in the adult human SVZ and fetal ventricular zone and reveal its expression on persistent radial glia that may be involved in adult neurogenesis.
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Affiliation(s)
- Birger Victor Dieriks
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, Amsterdam, the Netherlands
| | - Henry J Waldvogel
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
| | - Richard L M Faull
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
| | - Maurice A Curtis
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
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14
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Wu XH, Song JJ, Faull RLM, Waldvogel HJ. GABAAand GABABreceptor subunit localization on neurochemically identified neurons of the human subthalamic nucleus. J Comp Neurol 2017; 526:803-823. [DOI: 10.1002/cne.24368] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 11/12/2017] [Accepted: 11/14/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Xi Hua Wu
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences; The University of Auckland; Auckland New Zealand
| | - Jennifer Junru Song
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences; The University of Auckland; Auckland New Zealand
| | - Richard Lewis Maxwell Faull
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences; The University of Auckland; Auckland New Zealand
| | - Henry John Waldvogel
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences; The University of Auckland; Auckland New Zealand
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15
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GABA A receptor subunit deregulation in the hippocampus of human foetuses with Down syndrome. Brain Struct Funct 2017; 223:1501-1518. [PMID: 29168008 PMCID: PMC5869939 DOI: 10.1007/s00429-017-1563-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 11/05/2017] [Indexed: 11/01/2022]
Abstract
The function, regulation and cellular distribution of GABAA receptor subunits have been extensively documented in the adult rodent brain and are linked to numerous neurological disorders. However, there is a surprising lack of knowledge on the cellular (sub-) distribution of GABAA receptor subunits and of their expressional regulation in developing healthy and diseased foetal human brains. To propose a role for GABAA receptor subunits in neurodevelopmental disorders, we studied the developing hippocampus of normal and Down syndrome foetuses. Among the α1-3 and γ2 subunits probed, we find significantly altered expression profiles of the α1, α3 and γ2 subunits in developing Down syndrome hippocampi, with the α3 subunit being most affected. α3 subunits were selectively down-regulated in all hippocampal subfields and developmental periods tested in Down syndrome foetuses, presenting a developmental mismatch by their adult-like distribution in early foetal development. We hypothesized that increased levels of the amyloid precursor protein (APP), and particularly its neurotoxic β-amyloid (1-42) fragment, could disrupt α3 gene expression, likely by facilitating premature neuronal differentiation. Indeed, we find increased APP content in the hippocampi of the Down foetuses. In a corresponding cellular model, soluble β-amyloid (1-42) administered to cultured SH-SY5Y neuroblastoma cells, augmented by retinoic acid-induced differentiation towards a neuronal phenotype, displayed a reduction in α3 subunit levels. In sum, this study charts a comprehensive regional and subcellular map of key GABAA receptor subunits in identified neuronal populations in the hippocampus of healthy and Down syndrome foetuses and associates increased β-amyloid load with discordant down-regulation of α3 subunits.
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16
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Stefanits H, Milenkovic I, Mahr N, Pataraia E, Hainfellner JA, Kovacs GG, Sieghart W, Yilmazer-Hanke D, Czech T. GABAAreceptor subunits in the human amygdala and hippocampus: Immunohistochemical distribution of 7 subunits. J Comp Neurol 2017; 526:324-348. [DOI: 10.1002/cne.24337] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 09/12/2017] [Accepted: 09/19/2017] [Indexed: 12/18/2022]
Affiliation(s)
- Harald Stefanits
- Department of Neurosurgery; Medical University of Vienna; Vienna Austria
- Institute of Neurology, Medical University of Vienna; Vienna Austria
| | - Ivan Milenkovic
- Department of Clinical Neurology; Medical University of Vienna; Vienna Austria
| | - Nina Mahr
- Department of Neurosurgery; Medical University of Vienna; Vienna Austria
| | - Ekaterina Pataraia
- Department of Clinical Neurology; Medical University of Vienna; Vienna Austria
| | | | - Gabor G. Kovacs
- Institute of Neurology, Medical University of Vienna; Vienna Austria
| | - Werner Sieghart
- Center for Brain Research, Department of Molecular Neurosciences; Medical University of Vienna; Vienna Austria
| | - Deniz Yilmazer-Hanke
- Clinical Neuroanatomy, Neurology Department, Medical Faculty; Ulm University; Ulm Germany
| | - Thomas Czech
- Department of Neurosurgery; Medical University of Vienna; Vienna Austria
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17
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Hegeman DJ, Hong ES, Hernández VM, Chan CS. The external globus pallidus: progress and perspectives. Eur J Neurosci 2016; 43:1239-65. [PMID: 26841063 PMCID: PMC4874844 DOI: 10.1111/ejn.13196] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 01/20/2016] [Accepted: 01/27/2016] [Indexed: 12/12/2022]
Abstract
The external globus pallidus (GPe) of the basal ganglia is in a unique and powerful position to influence processing of motor information by virtue of its widespread projections to all basal ganglia nuclei. Despite the clinical importance of the GPe in common motor disorders such as Parkinson's disease, there is only limited information about its cellular composition and organizational principles. In this review, recent advances in the understanding of the diversity in the molecular profile, anatomy, physiology and corresponding behaviour during movement of GPe neurons are described. Importantly, this study attempts to build consensus and highlight commonalities of the cellular classification based on existing but contentious literature. Additionally, an analysis of the literature concerning the intricate reciprocal loops formed between the GPe and major synaptic partners, including both the striatum and the subthalamic nucleus, is provided. In conclusion, the GPe has emerged as a crucial node in the basal ganglia macrocircuit. While subtleties in the cellular makeup and synaptic connection of the GPe create new challenges, modern research tools have shown promise in untangling such complexity, and will provide better understanding of the roles of the GPe in encoding movements and their associated pathologies.
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Affiliation(s)
- Daniel J Hegeman
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Ellie S Hong
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Vivian M Hernández
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - C Savio Chan
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
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18
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Eid L, Parent M. Chemical anatomy of pallidal afferents in primates. Brain Struct Funct 2016; 221:4291-4317. [PMID: 27028222 DOI: 10.1007/s00429-016-1216-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/15/2016] [Indexed: 12/24/2022]
Abstract
Neurons of the globus pallidus receive massive inputs from the striatum and the subthalamic nucleus, but their activity, as well as those of their striatal and subthalamic inputs, are modulated by brainstem afferents. These include serotonin (5-HT) projections from the dorsal raphe nucleus, cholinergic (ACh) inputs from the pedunculopontine tegmental nucleus, and dopamine (DA) afferents from the substantia nigra pars compacta. This review summarizes our recent findings on the distribution, quantitative and ultrastructural aspects of pallidal 5-HT, ACh and DA innervations. These results have led to the elaboration of a new model of the pallidal neuron based on a precise knowledge of the hierarchy and chemical features of the various synaptic inputs. The dense 5-HT, ACh and DA innervations disclosed in the associative and limbic pallidal territories suggest that these brainstem inputs contribute principally to the planification of motor behaviors and the regulation of attention and mood. Although 5-HT, ACh and DA inputs were found to modulate pallidal neurons and their afferents mainly through asynaptic (volume) transmission, genuine synaptic contacts occur between these chemospecific axon varicosities and pallidal dendrites, revealing that these brainstem projections have a direct access to pallidal neurons, in addition to their indirect input through the striatum and subthalamic nucleus. Altogether, these findings reveal that the brainstem 5-HT, ACh and DA pallidal afferents act in concert with the more robust GABAergic inhibitory striatopallidal and glutamatergic excitatory subthalamopallidal inputs. We hypothesize that a fragile equilibrium between forebrain and brainstem pallidal afferents plays a key role in the functional organization of the primate basal ganglia, in both health and disease.
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Affiliation(s)
- Lara Eid
- Department of Psychiatry and Neuroscience, Faculty of Medicine, Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Université Laval, F-6530-1, 2601, de la Canardière, Quebec, QC, G1J 2G3, Canada
| | - Martin Parent
- Department of Psychiatry and Neuroscience, Faculty of Medicine, Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Université Laval, F-6530-1, 2601, de la Canardière, Quebec, QC, G1J 2G3, Canada.
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19
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Stojanovic T, Capo I, Aronica E, Adle-Biassette H, Höger H, Sieghart W, Kovacs GG, Milenkovic I. The α1, α2, α3, and γ2 subunits of GABAA receptors show characteristic spatial and temporal expression patterns in rhombencephalic structures during normal human brain development. J Comp Neurol 2015; 524:1805-24. [PMID: 26518133 DOI: 10.1002/cne.23923] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Revised: 10/24/2015] [Accepted: 10/28/2015] [Indexed: 01/13/2023]
Abstract
γ-Aminobutyric acid (GABA) is the most abundant inhibitory neurotransmitter in adult mammalian brain, mediating its actions chiefly via a pentameric chloride ion channel, the GABAA receptor. Nineteen different subunits (α1-6, β1-3, γ1-3, δ, ε, π, θ, ρ1-3) can give rise to multiple receptor subtypes that are the site of action of many clinically important drugs. In the developing brain, however, GABAA receptors mediate excitatory actions due to an increased chloride concentration within neurons and seem to control cell proliferation, migration, differentiation, synapse maturation, and cell death. Little is known about the distribution of single subunits in the human brain. Here we describe developmental changes in the immunohistochemical distribution of four subunits (α1, α2, α3, and γ2) in the human rhombencephalon. The γ2 was the most abundant subunit in all rhombencephalic structures during development and in adults, whereas α subunits showed a structure- and age-characteristic distribution. The α1 was expressed prenatally in the molecular and Purkinje cell layer, but only postnatally in the granule cell layer and the dentate nucleus. Expression was completely absent in the inferior olivary nucleus. The α2 gradually increased during development, showing some layer specificity in the cerebellar cortex. The α3-immunoreactivity in the cerebellar cortex was relatively weak, but it was abundantly observed in different cell populations in the subcortical cerebellar structures. Structure- and age-characteristic colocalization between subunits during development suggests differences in GABAA receptor composition. Interestingly, subunit expression in several instances differed between human and rodent brain, underlining the importance of immunohistochemical studies in humans.
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Affiliation(s)
- Tamara Stojanovic
- Institute of Neurology, Neurodegeneration Research Group, Medical University of Vienna, Vienna, Austria
| | - Ivan Capo
- Department of Histology and Embryology, Medical Faculty, Vojvodina, Serbia
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, The Netherlands; SEIN - Stichting Epilepsie Instellingen Nederland, Heemstede, The Netherlands; Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, The Netherlands
| | - Homa Adle-Biassette
- Inserm U1141, Paris, France; Univ. Paris Diderot, Sorbonne Paris Cité, UMRS 676, Paris, France, Department of Pathology, Lariboisière Hospital, APHP, Paris, France
| | - Harald Höger
- Division of Laboratory Animal Science and Genetics, Medical University of Vienna, Vienna, Austria
| | - Werner Sieghart
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Gabor G Kovacs
- Institute of Neurology, Neurodegeneration Research Group, Medical University of Vienna, Vienna, Austria
| | - Ivan Milenkovic
- Institute of Neurology, Neurodegeneration Research Group, Medical University of Vienna, Vienna, Austria.,Department of Neurology, Medical University of Vienna, Vienna, Austria
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20
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Gonzales KK, Smith Y. Cholinergic interneurons in the dorsal and ventral striatum: anatomical and functional considerations in normal and diseased conditions. Ann N Y Acad Sci 2015; 1349:1-45. [PMID: 25876458 DOI: 10.1111/nyas.12762] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Striatal cholinergic interneurons (ChIs) are central for the processing and reinforcement of reward-related behaviors that are negatively affected in states of altered dopamine transmission, such as in Parkinson's disease or drug addiction. Nevertheless, the development of therapeutic interventions directed at ChIs has been hampered by our limited knowledge of the diverse anatomical and functional characteristics of these neurons in the dorsal and ventral striatum, combined with the lack of pharmacological tools to modulate specific cholinergic receptor subtypes. This review highlights some of the key morphological, synaptic, and functional differences between ChIs of different striatal regions and across species. It also provides an overview of our current knowledge of the cellular localization and function of cholinergic receptor subtypes. The future use of high-resolution anatomical and functional tools to study the synaptic microcircuitry of brain networks, along with the development of specific cholinergic receptor drugs, should help further elucidate the role of striatal ChIs and permit efficient targeting of cholinergic systems in various brain disorders, including Parkinson's disease and addiction.
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Affiliation(s)
- Kalynda K Gonzales
- Yerkes National Primate Research Center, Department of Neurology and Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia.,Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York
| | - Yoland Smith
- Yerkes National Primate Research Center, Department of Neurology and Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia
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21
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Milenkovic I, Vasiljevic M, Maurer D, Höger H, Klausberger T, Sieghart W. The parvalbumin-positive interneurons in the mouse dentate gyrus express GABAA receptor subunits α1, β2, and δ along their extrasynaptic cell membrane. Neuroscience 2013; 254:80-96. [PMID: 24055402 DOI: 10.1016/j.neuroscience.2013.09.019] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 08/27/2013] [Accepted: 09/09/2013] [Indexed: 11/17/2022]
Abstract
Neuronal circuitries in the hippocampus are involved in navigation and memory and are controlled by major networks of GABAergic interneurons. Parvalbumin (PV)-expressing interneurons in the dentate gyrus (DG) are identified as fast-spiking cells, playing a crucial role in network oscillation and synchrony. The inhibitory modulation of these interneurons is thought to be mediated mainly through GABAA receptors, the major inhibitory neurotransmitter receptors in the brain. Here we show that all PV-positive interneurons in the granular/subgranular layer (GL/SGL) of the mouse DG express high levels of the GABAA receptor δ subunit. PV-containing interneurons in the hilus and the molecular layer, however, express the δ subunit to a lower extent. Only 8% of the somatostatin-containing interneurons express the δ subunit, whereas calbindin- or calretinin-containing interneurons in the DG seem not to express the GABAA receptor δ subunit at all. Hence, these cells receive a GABAergic control different from that of PV-containing interneurons in the GL/SGL. Experiments investigating a possible co-expression of GABAA receptor α1, α2, α3, α4, α5, β1, β2, β3, or γ2 subunits with PV and δ subunits indicated that α1 and β2 subunits are co-expressed with δ subunits along the extrasynaptic membranes of PV-interneurons. These results suggest a robust tonic GABAergic control of PV-containing interneurons in the GL/SGL of the DG via δ subunit-containing receptors. Our data are important for better understanding of the neuronal circuitries in the DG and the role of specific cell types under pathological conditions.
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Affiliation(s)
- I Milenkovic
- Center for Brain Research, Department of Biochemistry and Molecular Biology of the Nervous System, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria; Institute of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, 1097 Vienna, Austria.
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22
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Gonzales KK, Pare JF, Wichmann T, Smith Y. GABAergic inputs from direct and indirect striatal projection neurons onto cholinergic interneurons in the primate putamen. J Comp Neurol 2013; 521:2502-22. [PMID: 23296794 PMCID: PMC3983787 DOI: 10.1002/cne.23295] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 11/14/2012] [Accepted: 12/27/2012] [Indexed: 01/30/2023]
Abstract
Striatal cholinergic interneurons (ChIs) are involved in reward-dependent learning and the regulation of attention. The activity of these neurons is modulated by intrinsic and extrinsic γ-aminobutyric acid (GABA)ergic and glutamatergic afferents, but the source and relative prevalence of these diverse regulatory inputs remain to be characterized. To address this issue, we performed a quantitative ultrastructural analysis of the GABAergic and glutamatergic innervation of ChIs in the postcommissural putamen of rhesus monkeys. Postembedding immunogold localization of GABA combined with peroxidase immunostaining for choline acetyltransferase showed that 60% of all synaptic inputs to ChIs originate from GABAergic terminals, whereas 21% are from putatively glutamatergic terminals that establish asymmetric synapses, and 19% from other (non-GABAergic) sources of symmetric synapses. Double pre-embedding immunoelectron microscopy using substance P and Met-/Leu-enkephalin antibodies to label GABAergic terminals from collaterals of "direct" and "indirect" striatal projection neurons, respectively, revealed that 47% of the indirect pathway terminals and 36% of the direct pathway terminals target ChIs. Together, substance P- and enkephalin-positive terminals represent 24% of all synapses onto ChIs in the monkey putamen. These findings show that ChIs receive prominent GABAergic inputs from multiple origins, including a significant contingent from axon collaterals of direct and indirect pathway projection neurons.
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Affiliation(s)
- Kalynda Kari Gonzales
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia 30329
| | - Jean-Francois Pare
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia 30329
| | - Thomas Wichmann
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329
- Department of Neurology, Emory University, Atlanta, Georgia 30329
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia 30329
| | - Yoland Smith
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329
- Department of Neurology, Emory University, Atlanta, Georgia 30329
- Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia 30329
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23
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Dieriks BV, Waldvogel HJ, Monzo HJ, Faull RLM, Curtis MA. GABA(A) receptor characterization and subunit localization in the human sub-ventricular zone. J Chem Neuroanat 2013; 52:58-68. [PMID: 23770130 DOI: 10.1016/j.jchemneu.2013.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 05/29/2013] [Accepted: 06/01/2013] [Indexed: 11/19/2022]
Abstract
It is now well established that the human brain continuously produces new stem cells until well into old age. One of these stem-cell rich areas in the human brain is the sub-ventricular zone (SVZ). The human SVZ is organized in four distinctive layers containing type A, B and C cells. To date, no studies have investigated the distribution of inhibitory neurotransmitters such as γ-aminobutyric acid (GABA) and their respective receptors on the different cell types in the human SVZ. GABA(A) receptors (GABA(A)R) are ubiquitously expressed, inhibitory heteropentameric chloride ion channels comprised of a variety of subunits that are targeted by many prescribed drugs. In this study we present detailed immunohistochemical data on the regional and cellular localization of α₁, α₂, α3, β₂,₃ and γ₂ subunits of GABA(A)R in the human SVZ. The results from our double and triple labeling studies demonstrate that the cell types and subunit composition throughout the SVZ is heterogeneous; the thickness of the SVZ and GABA(A)R α₂ and γ₂ expression is increased especially in the vicinity of large SVZ blood vessels. GABA(A)R γ₂ is the most specific to the SVZ and present on various cells that express, either glial fibrillary acidic protein (GFAPδ) or polysialic acid-neural cell adhesion molecule (PSA-NCAM) separately, or together in a respective ratio of 7:6:2. Proliferating (type C) cells in the SVZ express GAD65/67, GFAPδ and GABA(A)R β₂,₃ receptor subunits. Within the SVZ the majority of cells have an unexpected nuclear GABA(A)R β₂,₃ expression that is inversely proportional to that of PCNA (proliferating cell nuclear antigen marker), which is a very different pattern of expression compared with underlying caudate nucleus cells. Taken together our results provide a detailed description of the chemo-architecture of the adult human SVZ demonstrating the importance of GABA and GABA(A) receptors on the various cell types in the SVZ.
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Affiliation(s)
- Birger V Dieriks
- Department of Anatomy with Radiology and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag 92019, Auckland, New Zealand
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24
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Abstract
The discovery, in 1998, that the adult human brain contains at least two populations of progenitor cells and that progenitor cells are upregulated in response to a range of degenerative brain diseases has raised hopes for their use in replacing dying brain cells. Since these early findings the race has been on to understand the biology of progenitor cells in the human brain and they have now been isolated and studied in many major neurodegenerative diseases. Before these cells can be exploited for cell replacement purposes it is important to understand how to: (1) find them, (2) label them, (3) determine what receptors they express, (4) isolate them, and (5) examine their electrophysiological properties when differentiated. In this chapter we have described the methods we use for studying progenitor cells in the adult human brain and in particular the tissue processing, immunohistochemistry, autoradiography, progenitor cell culture, and electrophysiology on brain cells. The Neurological Foundation of New Zealand Human Brain Bank has been receiving human tissue for approximately 20 years during which time we have developed a number of unique ways to examine and isolate progenitor cells from resected surgical specimens as well as from postmortem brain tissue. There are ethical and technical considerations that are unique to working with human brain tissue and these, as well as the processing of this tissue and the culturing of it for the purpose of studying progenitor cells, are the topic of this chapter.
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25
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Rohof WO, Aronica E, Beaumont H, Troost D, Boeckxstaens GE. Localization of mGluR5, GABAB, GABAA, and cannabinoid receptors on the vago-vagal reflex pathway responsible for transient lower esophageal sphincter relaxation in humans: an immunohistochemical study. Neurogastroenterol Motil 2012; 24:383-e173. [PMID: 22256945 DOI: 10.1111/j.1365-2982.2011.01868.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND Transient lower esophageal sphincter relaxations (TLESRs) are the predominant mechanisms underlying gastro-esophageal reflux. TLESRs are mediated by a vago-vagal reflex, which can be blocked by interaction with metabotropic Glutamate Receptor 5 (mGluR5), γ-aminobutyric acid type B (GABA(B)), γ-aminobutyric acid type A (GABA(A)), and cannabinoid (CB) receptors. However, the distribution of these receptors in the neural pathway underlying the triggering of TLESRs has not been evaluated in humans. METHODS Using immunohistochemistry, we investigated the distribution of mGluR5, GABA(A), GABA(B), CB1, and CB2 receptors in the human nodose ganglion, the brain stem, and the myenteric plexus of the esophagus. KEY RESULTS MGluR5, GABA(B), CB1, and CB2 receptors are abundantly expressed in neurons of the myenteric plexus of the LES, nodose ganglion cell bodies and nerve fibers, the dorsal motor nucleus, and nucleus of the solitary tract in the brain stem. GABA(A) receptors are expressed in the same regions except in the nodose ganglion and myenteric plexus of the LES. CONCLUSIONS & INFERENCES Human mGluR5, GABA(A,B), and CB(1,2) receptors are abundantly expressed along the vago-vagal neural pathway and involved in the triggering of TLESRs. These findings are not only in line with the central side effects observed during treatment with reflux inhibitors such as GABA(B) receptor agonists and mGluR5 antagonists, but also suggest that peripherally acting compounds may be effective.
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Affiliation(s)
- W O Rohof
- Department of Gastroenterology, Academic Medical Center, Amsterdam, The Netherlands
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26
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Díaz E, Bravo D, Rojas X, Concha ML. Morphologic and immunohistochemical organization of the human habenular complex. J Comp Neurol 2012; 519:3727-47. [PMID: 21674490 DOI: 10.1002/cne.22687] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The habenular complex (HbCpx) is a phylogenetically conserved brain structure located in the epithalamus of vertebrates. Despite its fundamental role in decision-making processes and the proposed link between habenular dysfunction and neuropsychiatric conditions, little is known about the structural and functional organization of the HbCpx in humans. The goal of this study was thus to provide a first systematic morphologic and immunohistochemical analysis of the human HbCpx to begin dissecting its nuclear and subnuclear organization. Our results confirmed that the human HbCpx is subdivided into medial (MHb) and lateral (LHb) nuclei, each showing a large degree of intranuclear morphologic heterogeneity. Analysis of serially stained sections using a combination of morphologic and immunohistochemical criteria allowed the distinction of five subnuclei in both the MHb and LHb. Overall, the observed subnuclear organization of the MHb in humans resembles the organization of subnuclei in the MHb of rats. The shape, relative size, and intranuclear organization of the LHb, however, show significant differences. The contribution of the LHb to the entire HbCpx is about five times larger in humans than in rats. Noteworthy, a dorsal domain of the LHb that contains afferent myelinated fibers from the stria medullaris and shows GABA-(B) -R(1) immunoreactive cells, appears substantially enlarged in humans when compared to rats. This feature seems to account for a large part of the relative growth in size of the LHb in humans and opens the intriguing possibility of an increased influence of limbic and striatal afferents into the LHb of humans.
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Affiliation(s)
- Eugenia Díaz
- Laboratory of Experimental Ontogeny (LEO), Anatomy and Developmental Biology Program, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
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Lin LH, Nitschke Dragon D, Talman WT. Collateral damage and compensatory changes after injection of a toxin targeting neurons with the neurokinin-1 receptor in the nucleus tractus solitarii of rat. J Chem Neuroanat 2012; 43:141-8. [PMID: 22414622 DOI: 10.1016/j.jchemneu.2012.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 02/23/2012] [Accepted: 02/24/2012] [Indexed: 02/02/2023]
Abstract
Injection into the nucleus tractus solitarii (NTS) of toxins that target substance P (SP) receptors ablates neurons that express neurokinin-1 (NK1) receptors, attenuates baroreflexes, and results in increased lability of arterial pressure. We and others have shown that the toxin leads to loss of neurons containing SP receptors and loss of GABAergic neurons in the NTS; but given that neither type neuron is thought to be integral to baroreflex transmission in NTS, mechanisms responsible for the cardiovascular changes remained unclear. Because NK1 receptors colocalize with N-methyl-d-aspartate (NMDA) receptors and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in NTS and because glutamate transmission may be integral to baroreflex transmission in the NTS we hypothesized that the toxic lesions may interrupt mechanisms for glutamate transmission. Interruption of those mechanisms could be responsible for the cardiovascular effects. We tested the hypothesis by performing fluorescent immunohistochemistry, confocal microscopy and image analysis after injecting stabilized SP-SAP (SSP-SAP) unilaterally into the NTS. We assessed changes in immunoreactivity (IR) of NMDA receptor subunit 1 (NMDAR1), AMPA receptor subunit 2 (GluR2), and 3 types of vesicular glutamate transporters (VGluT) as well as IR of gamma-aminobutyric acid receptors type b (GABAb), neuronal nitric oxide synthase (nNOS), tyrosine hydroxylase (TH), and protein gene product 9.5 (PGP 9.5), a neuronal marker, in the NTS. When compared to that of the same section of the un-injected NTS, IR decreased significantly in the injected side for NMDAR1 (p<0.01), GluR2 (p<0.01), VGluT3 (p<0.01), GABAb (p<0.001), and PGP9.5 (p<0.001). In contrast, IR for VGluT1 (p<0.001), VGluT2 (p<0.001), nNOS (p<0.001), and TH (p<0.001) increased significantly. We conclude that pathologic effects following ablation of neurons with NK1 receptors in NTS may result from interruption of neurotransmission through other neurochemical systems associated with NK1 receptors-containing neurons.
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Affiliation(s)
- Li-Hsien Lin
- Department of Neurology, University of Iowa, Iowa City, IA 52242, USA
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Bernácer J, Prensa L, Giménez-Amaya JM. Distribution of GABAergic interneurons and dopaminergic cells in the functional territories of the human striatum. PLoS One 2012; 7:e30504. [PMID: 22272358 PMCID: PMC3260284 DOI: 10.1371/journal.pone.0030504] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 12/16/2011] [Indexed: 11/30/2022] Open
Abstract
Background The afferent projections of the striatum (caudate nucleus and putamen) are segregated in three territories: associative, sensorimotor and limbic. Striatal interneurons are in part responsible for the integration of these different types of information. Among them, GABAergic interneurons are the most abundant, and can be sorted in three populations according to their content in the calcium binding proteins calretinin (CR), parvalbumin (PV) and calbindin (CB). Conversely, striatal dopaminergic cells (whose role as interneurons is still unclear) are scarce. This study aims to analyze the interneuron distribution in the striatal functional territories, as well as their organization regarding to the striosomal compartment. Methodology/Principal Findings We used immunohistochemical methods to visualize CR, PV, CB and tyrosine hydroxylase (TH) positive striatal neurons. The interneuronal distribution was assessed by stereological methods applied to every striatal functional territory. Considering the four cell groups altogether, their density was higher in the associative (2120±91 cells/mm3) than in the sensorimotor (959±47 cells/mm3) or limbic (633±119 cells/mm3) territories. CB- and TH-immunoreactive(-ir) cells were distributed rather homogeneously in the three striatal territories. However, the density of CR and PV interneurons were more abundant in the associative and sensorimotor striatum, respectively. Regarding to their compartmental organization, CR-ir interneurons were frequently found in the border between compartments in the associative and sensorimotor territories, and CB-ir interneurons abounded at the striosome/matrix border in the sensorimotor domain. Conclusions/Significance The present study demonstrates that the architecture of the human striatum in terms of its interneuron composition varies in its three functional territories. Furthermore, our data highlight the importance of CR-ir striatal interneurons in the integration of associative information, and the selective role of PV-ir interneurons in the motor territory. On the other hand, the low density of dopaminergic cells casts doubts about their role in the normal human striatum.
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Affiliation(s)
- Javier Bernácer
- Laboratorio de Neuromorfología Funcional, Clínica Universitaria de Navarra, Pamplona, Spain.
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Shrivastava AN, Triller A, Sieghart W. GABA(A) Receptors: Post-Synaptic Co-Localization and Cross-Talk with Other Receptors. Front Cell Neurosci 2011; 5:7. [PMID: 21734865 PMCID: PMC3123775 DOI: 10.3389/fncel.2011.00007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 06/06/2011] [Indexed: 11/14/2022] Open
Abstract
γ-Aminobutyric acid type A receptors (GABAARs) are the major inhibitory neurotransmitter receptors in the central nervous system, and importantly contribute to the functional regulation of the nervous system. Several studies in the last few decades have convincingly shown that GABA can be co-localized with other neurotransmitters in the same synapse, and can be co-released with these neurotransmitters either from the same vesicles or from different vesicle pools. The co-released transmitters may act on post-synaptically co-localized receptors resulting in a simultaneous activation of both receptors. Most of the studies investigating such co-activation observed a reduced efficacy of GABA for activating GABAARs and thus, a reduced inhibition of the post-synaptic neuron. Similarly, in several cases activation of GABAARs has been reported to suppress the response of the associated receptors. Such a receptor cross-talk is either mediated via a direct coupling between the two receptors or via the activation of intracellular signaling pathways and is used for fine tuning of inhibition in the nervous system. Recently, it was demonstrated that a direct interaction of different receptors might already occur in intracellular compartments and might also be used to specifically target the receptors to the cell membrane. In this article, we provide an overview on such cross-talks between GABAARs and several other neurotransmitter receptors and briefly discuss their possible physiological and clinical importance.
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Affiliation(s)
- Amulya Nidhi Shrivastava
- Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University of Vienna Vienna, Austria
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Rekik L, Daguin-Nerrière V, Petit JY, Brachet P. γ-Aminobutyric acid type B receptor changes in the rat striatum and substantia nigra following intrastriatal quinolinic acid lesions. J Neurosci Res 2011; 89:524-35. [PMID: 21290407 DOI: 10.1002/jnr.22574] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 10/25/2010] [Accepted: 11/05/2010] [Indexed: 12/16/2023]
Abstract
Changes in the regional distribution of the metabotropic GABA type B receptors (GABA(B)) were investigated in a rat model of Huntington's disease. Animals received a unilateral intrastriatal injection of quinolinic acid (QA), and GABA(B) immunoreactivity was monitored 3, 11, and 21 days postinjection in the striatum and substantia nigra (SN). Two antibodies, recognizing either the GABA(B1) or the GABA(B2) receptor subtypes, were used. QA injection rapidly induced a protracted increase in GABA(B1) or GABA(B2) immunoreactivity in the lesioned striatum, despite the neuronal loss. In the SN, a continuous increase in GABA(B1) and GABA(B2) immunoreactivity was observed at all time points in the ipsilateral pars reticulata (SNr), whereas the pars compacta (SNc) was unaffected by this phenomenon. This increase was supported by a densitometric analysis. At day 21 postlesion induction, intensely labeled stellate cells and processes were found in the ipsilateral SNr, in addition to immunoreactive neurons. Double labeling of GABA(B1) and glial fibrillary acidic protein (GFAP) showed that the stellate cells were reactive astrocytes. Hence, part of the sustained increase in GABA(B) immunoreactivity that takes place in the SNr and possibly the striatum may be ascribed to reactive astrocytes. It is suggested that GABA(B) receptors are up-regulated in these reactive astrocytes and that agonists might influence the extent of this astroglial reaction.
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Affiliation(s)
- Letaïef Rekik
- Laboratory of Pharmacology, Faculty of Pharmacy, University of Monastir, Monastir, Tunisia.
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Ghose S, Winter MK, McCarson KE, Tamminga CA, Enna SJ. The GABAβ receptor as a target for antidepressant drug action. Br J Pharmacol 2011; 162:1-17. [PMID: 20735410 PMCID: PMC3012402 DOI: 10.1111/j.1476-5381.2010.01004.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 08/06/2010] [Accepted: 08/11/2010] [Indexed: 11/29/2022] Open
Abstract
Preclinical and clinical data suggest that a modification in GABA(B) receptor expression and function may contribute to the symptoms of major depression and the response to antidepressants. This includes laboratory animal experiments demonstrating that antidepressants modify brain GABA(B) receptor expression and function and that GABA(B) receptor antagonists display antidepressant potential in animal models of this condition. Clinical and post-mortem studies reveal changes in GABAergic transmission associated with depression as well as depression-related changes in GABA(B) subunit expression that are localized to the cortical depression network. Detailed in this review are the preclinical and clinical data implicating a role for the GABA(B) receptor system in mediating symptoms of this disorder and its possible involvement in the response to antidepressants. Particular emphasis is placed on clinical and post-mortem studies, including previously unpublished work demonstrating regionally-selective modifications in GABA(B) receptor subunit expression in brain samples obtained from depressed subjects. Together with the earlier preclinical studies, these new data point to a role for the GABA(B) system in major depression and support the antidepressant potential of GABA(B) receptor antagonists.
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Affiliation(s)
- Subroto Ghose
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
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Mathew J, Soman S, Sadanandan J, Paulose CS. Decreased GABA receptor in the striatum and spatial recognition memory deficit in epileptic rats: effect of Bacopa monnieri and bacoside-A. JOURNAL OF ETHNOPHARMACOLOGY 2010; 130:255-261. [PMID: 20451596 DOI: 10.1016/j.jep.2010.04.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 04/10/2010] [Accepted: 04/28/2010] [Indexed: 05/29/2023]
Abstract
AIM OF THE STUDY Gamma-aminobutyric acid A receptors are the principal mediators of synaptic inhibition in striatal neurons and play an important role in preventing the spreading of seizures through the striatum. In the present study, effect of Bacopa monnieri (L.) Pennel and its active component bacoside-A on spatial recognition memory deficit and alterations of GABA receptor in the striatum of epileptic rats were investigated. MATERIALS AND METHODS Total GABA and GABA(A) receptor numbers in the control and epileptic rats were evaluated using [(3)H]GABA and [(3)H]bicuculline binding. GABA(Aalpha1,) GABA(Aalpha5,) GABA(Agamma3) and GABA(Adelta) gene expressions were studied. Behavioral performance was assed using Y-maze. RESULTS Scatchard analysis of [(3)H]GABA and [(3)H]bicuculline in the striatum of epileptic rats showed significant decrease in B(max) compared to control. Real-Time PCR amplification of GABA(A) receptor subunits such as GABA(Aalpha1,) GABA(Aalpha5) and GABA(Adelta), were down regulated (p<0.001) in the striatum of epileptic rats compared to control. Epileptic rats have deficit in Y-maze performance. Bacopa monnieri and bacoside-A treatment reversed these changes to near control. CONCLUSION Our results suggest that decreased GABA receptors in the striatum have an important role in epilepsy associated motor learning deficits and Bacopa monnieri and bacoside-A has a beneficial effect in the management of epilepsy.
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Affiliation(s)
- Jobin Mathew
- Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, Kerala, India
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Morawski M, Brückner G, Jäger C, Seeger G, Arendt T. Neurons associated with aggrecan-based perineuronal nets are protected against tau pathology in subcortical regions in Alzheimer's disease. Neuroscience 2010; 169:1347-63. [PMID: 20497908 DOI: 10.1016/j.neuroscience.2010.05.022] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 04/14/2010] [Accepted: 05/11/2010] [Indexed: 10/19/2022]
Abstract
The biological basis for the selective vulnerability of neurons in Alzheimer's disease (AD) is elusive. Aggrecan-based perineuronal nets (PNs) of the extracellular matrix have been considered to contribute to neuroprotection in the cerebral cortex. In the present study, we investigated the organization of the aggrecan-based extracellular matrix in subcortical regions known to be preferentially affected by tau pathology in AD. Immunocytochemistry of aggrecan core protein was combined with detection of neurofibrillary degeneration. The results show that many regions affected by tau pathology in AD, such as the basal nucleus of Meynert, the dorsal thalamus, hypothalamic nuclei, raphe nuclei, and the locus coeruleus were devoid of a characteristic aggrecan-based extracellular matrix. Regions composed of nuclei with clearly different intensity of tau pathology, such as the amygdala, the thalamus and the oculomotor complex, showed largely complementary distribution patterns of neurofibrillary tangles and PNs. Quantification in the rostral interstitial nucleus of the longitudinal fascicle potentially affected by tau pathology in AD revealed that tau pathology was not accompanied by loss of aggrecan-based PNs. Neuro-fibrillary tangles in net-associated neurons extremely rarely occurred in the pontine reticular formation. We conclude that the low vulnerability of neurons ensheathed by PNs previously described for cortical areas in AD represents a more general phenomenon that also applies to subcortical regions. The aggrecan-based extracellular matrix of PNs may thus, be involved in neuroprotection.
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Affiliation(s)
- M Morawski
- Department of Molecular and Cellular Mechanisms of Neurodegeneration, Medical Faculty, Paul Flechsig Institute for Brain Research, University of Leipzig, Jahnallee 59, D-04109 Leipzig, Germany.
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Waldvogel HJ, Baer K, Eady E, Allen KL, Gilbert RT, Mohler H, Rees MI, Nicholson LFB, Faull RLM. Differential localization of gamma-aminobutyric acid type A and glycine receptor subunits and gephyrin in the human pons, medulla oblongata and uppermost cervical segment of the spinal cord: an immunohistochemical study. J Comp Neurol 2010; 518:305-28. [PMID: 19950251 DOI: 10.1002/cne.22212] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Gephyrin is a multifunctional protein responsible for the clustering of glycine receptors (GlyR) and gamma-aminobutyric acid type A receptors (GABA(A)R). GlyR and GABA(A)R are heteropentameric chloride ion channels that facilitate fast-response, inhibitory neurotransmission in the mammalian brain and spinal cord. We investigated the immunohistochemical distribution of gephyrin and the major GABA(A)R and GlyR subunits in the human light microscopically in the rostral and caudal one-thirds of the pons, in the middle and caudal one-thirds of the medulla oblongata, and in the first cervical segment of the spinal cord. The results demonstrate a widespread pattern of immunoreactivity for GlyR and GABA(A)R subunits throughout these regions, including the spinal trigeminal nucleus, abducens nucleus, facial nucleus, pontine reticular formation, dorsal motor nucleus of the vagus nerve, hypoglossal nucleus, lateral cuneate nucleus, and nucleus of the solitary tract. The GABA(A)R alpha(1) and GlyR alpha(1) and beta subunits show high levels of immunoreactivity in these nuclei. The GABA(A)R subunits alpha(2), alpha(3), beta(2,3), and gamma(2) present weaker levels of immunoreactivity. Exceptions are intense levels of GABA(A)R alpha(2) subunit immunoreactivity in the inferior olivary complex and high levels of GABA(A)R alpha(3) subunit immunoreactivity in the locus coeruleus and raphe nuclei. Gephyrin immunoreactivity is highest in the first segment of the cervical spinal cord and hypoglossal nucleus. Our results suggest that a variety of different inhibitory receptor subtypes is responsible for inhibitory functions in the human brainstem and cervical spinal cord and that gephyrin functions as a clustering molecule for major subtypes of these inhibitory neurotransmitter receptors.
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Affiliation(s)
- H J Waldvogel
- Department of Anatomy with Radiology, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand.
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Baer K, Waldvogel HJ, Faull RLM, Rees MI. Localization of glycine receptors in the human forebrain, brainstem, and cervical spinal cord: an immunohistochemical review. Front Mol Neurosci 2009; 2:25. [PMID: 19915682 PMCID: PMC2776491 DOI: 10.3389/neuro.02.025.2009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 10/15/2009] [Indexed: 11/26/2022] Open
Abstract
Inhibitory neurotransmitter receptors for glycine (GlyR) are heteropentameric chloride ion channels that are comprised of four functional subunits, alpha1–3 and beta and that facilitate fast-response, inhibitory neurotransmission in the mammalian brain and spinal cord. We have investigated the distribution of GlyRs in the human forebrain, brainstem, and cervical spinal cord using immunohistochemistry at light and confocal laser scanning microscopy levels. This review will summarize the present knowledge on the GlyR distribution in the human brain using our established immunohistochemical techniques. The results of our immunohistochemical labeling studies demonstrated GlyR immunoreactivity (IR) throughout the human basal ganglia, substantia nigra, various pontine regions, rostral medulla oblongata and the cervical spinal cord present an intense and abundant punctate IR along the membranes of the neuronal soma and dendrites. This work is part of a systematic study of inhibitory neurotransmitter receptor distribution in the human CNS, and provides a basis for additional detailed physiological and pharmacological studies on the inter-relationship of GlyR, GABAAR and gephyrin in the human brain. This basic mapping exercise, we believe, will provide important baselines for the testing of future pharmacotherapies and drug regimes that modulate neuroinhibitory systems. These findings provide new information for understanding the complexity of glycinergic functions in the human brain, which will translate into the contribution of inhibitory mechanisms in paroxysmal disorders and neurodegenerative diseases such as Epilepsy, Huntington's and Parkinson's Disease and Motor Neuron Disease.
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Affiliation(s)
- Kristin Baer
- Molecular Neuroscience, Institute of Life Science, School of Medicine, Swansea University Swansea, UK
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Allen K, Waldvogel H, Glass M, Faull R. Cannabinoid (CB1), GABAA and GABAB receptor subunit changes in the globus pallidus in Huntington's disease. J Chem Neuroanat 2009; 37:266-81. [DOI: 10.1016/j.jchemneu.2009.02.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 02/05/2009] [Accepted: 02/05/2009] [Indexed: 10/21/2022]
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Connelly WM, Shenton FC, Lethbridge N, Leurs R, Waldvogel HJ, Faull RLM, Lees G, Chazot PL. The histamine H4 receptor is functionally expressed on neurons in the mammalian CNS. Br J Pharmacol 2009; 157:55-63. [PMID: 19413571 DOI: 10.1111/j.1476-5381.2009.00227.x] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE The histamine H4 receptor is the most recently identified of the G protein-coupled histamine receptor family and binds several neuroactive drugs, including amitriptyline and clozapine. So far, H4 receptors have been found only on haematopoietic cells, highlighting its importance in inflammatory conditions. Here we investigated the possibility that H4 receptors may be expressed in both the human and mouse CNS. METHODS Immunological and pharmacological studies were performed using a novel anti-H4 receptor antibody in both human and mouse brains, and electrophysiological techniques in the mouse brain respectively. Pharmacological tools, selective for the H4 receptor and patch clamp electrophysiology, were utilized to confirm functional properties of the H4 receptor in layer IV of the mouse somatosensory cortex. RESULTS Histamine H4 receptors were prominently expressed in distinct deep laminae, particularly layer VI, in the human cortex, and mouse thalamus, hippocampal CA4 stratum lucidum and layer IV of the cerebral cortex. In layer IV of the mouse somatosensory cortex, the H4 receptor agonist 4-methyl histamine (20 micromol x L(-1)) directly hyperpolarized neurons, an effect that was blocked by the selective H4 receptor antagonist JNJ 10191584, and promoted outwardly rectifying currents in these cells. Monosynaptic thalamocortical CNQX-sensitive excitatory postsynaptic potentials were not altered by 4-methyl histamine (20 micromol x L(-1)) suggesting that H4 receptors did not act as hetero-receptors on thalamocortical glutamatergic terminals. CONCLUSIONS AND IMPLICATIONS This is the first demonstration that histamine H4 receptors are functionally expressed on neurons, which has major implications for the therapeutic potential of these receptors in neurology and psychiatry.
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Affiliation(s)
- W M Connelly
- Department of Pharmacology & Toxicology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Chung SH, Kim CT, Hawkes R. Compartmentation of GABA B receptor2 expression in the mouse cerebellar cortex. THE CEREBELLUM 2009; 7:295-303. [PMID: 18418671 DOI: 10.1007/s12311-008-0030-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite the apparent uniformity in cellular composition of the adult mammalian cerebellar cortex, it is actually highly compartmentalized into transverse zones, and within each zone the cortex is further subdivided into a reproducible array of parasagittal stripes. The most extensively studied compartmentation antigen is zebrin II/aldolase c, which is expressed by a subset of Purkinje cells forming parasagittal stripes. Gamma-aminobutyric acid B receptors (GABABRs) are G-protein-coupled receptors that mediate a slow, prolonged form of inhibition in many brain areas. This study examines the localization of GABABR2 in the mouse cerebellum by using whole mount and section immunohistochemistry. The data reveal that GABABR2 immunoreactivity is expressed strongly in the dendrites of a subset of Purkinje cells that form a reproducible array of transverse zones and parasagittal stripes. By using double immunostaining, the striped pattern of GABABR2 expression was shown to be identical to that revealed by anti-zebrin II and complementary to that of phospholipase Cbeta4. This finding supports previous functional studies showing that inhibitory neurotransmission is highly patterned in the cerebellar cortex.
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Affiliation(s)
- Seung-Hyuk Chung
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, and Genes and Development Research Group, Faculty of Medicine, University of Calgary, Alberta, Canada
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The localization of inhibitory neurotransmitter receptors on dopaminergic neurons of the human substantia nigra. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2009:59-70. [PMID: 20411768 DOI: 10.1007/978-3-211-92660-4_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The substantia nigra pars compacta (SNc) is comprised mainly of dopaminergic pigmented neurons arranged in groups, with a small population of nonpigmented neurons scattered among these groups. These different types of neurons possess GABAA, GABAB, and glycine receptors. The SNc-pigmented dopaminergic neurons have postsynaptic GABAA receptors (GABAAR) with a subunit configuration containing alpha3 and gamma2 subunits, with a small population of pigmented neurons containing alpha1 beta2,3 gamma2 subunits. GABAB receptors comprised of R1 and R2 subunits and glycine receptors are also localized on pigmented neurons. In contrast, nonpigmented (mainly parvalbumin positive neurons) located in the SNc are morphologically and neurochemically similar to substantia nigra pars reticulata (SNr) neurons by showing immunoreactivity for parvalbumin and GABAARs containing immunoreactivity for alpha1, alpha3, beta2,3, and gamma2 subunits as well as GABAB R1 and R2 subunits and glycine receptors. Thus, these two neuronal types of the SNc, either pigmented dopaminergic neurons or nonpigmented parvalbumin positive neurons, have similar GABAB and glycine receptor combinations, but differ mainly in the subunit composition of the GABAARs located on their membranes. The different types of GABAARs suggest that GABAergic inputs to these neuronal types operate through GABAARs with different pharmacological and physiological profiles, whereas GABABR and glycine receptors of these cell types are likely to have similar properties.
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Mizuta K, Osawa Y, Mizuta F, Xu D, Emala CW. Functional expression of GABAB receptors in airway epithelium. Am J Respir Cell Mol Biol 2008; 39:296-304. [PMID: 18403780 DOI: 10.1165/rcmb.2007-0414oc] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system and exerts its actions via both ionotropic (GABA(A)) and metabotropic (GABA(B)) receptors. The GABA(B) receptor is a dimer composed of R1 and R2 components and classically couples to the heterotrimeric G(i) protein. In addition to their location on neurons, GABA and functional GABA(B) receptors have been detected in peripheral tissue such as airway smooth muscle. We questioned whether airway epithelium expresses receptors that could respond to GABA. We detected the mRNA encoding multiple-splice variants of the GABA(B)R1 and GABA(B)R2 in total RNA isolated from native human and guinea pig airway epithelium and human airway epithelial cell lines (BEAS-2B and H441). Immunoblots identified the GABA(B)R1 and GABA(B)R2 proteins in both guinea pig airway epithelium and BEAS-2B cells. The expression of GABA(B)R1 protein was immunohistochemically localized to basal mucin-secreting and ciliated columnar epithelial cells in guinea pig trachea. Baclofen inhibited adenylyl cyclase activity, induced ERK phosphorylation and cross-regulated phospholipase C, leading to increased inositol phosphates in BEAS-2B cells in a pertussis toxin-sensitive manner, implicating G(i) protein coupling. Thus, these receptors couple to G(i) and cross-regulate the phospholipase C/inositol phosphate pathway. The second messengers of these pathways, cyclic AMP and calcium, play pivotal roles in airway epithelial cell primary functions of mucus clearance. Furthermore, the enzyme that synthesizes GABA, glutamic acid decarboxylase (GAD65/67), was also localized to airway epithelium. GABA may modulate an uncharacterized signaling cascade via GABA(B) receptors coupled to G(i) protein in airway epithelium.
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Affiliation(s)
- Kentaro Mizuta
- Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
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Waldvogel HJ, Bullock JY, Synek BJ, Curtis MA, van Roon-Mom WMC, Faull RLM. The collection and processing of human brain tissue for research. Cell Tissue Bank 2008; 9:169-79. [PMID: 18357514 DOI: 10.1007/s10561-008-9068-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Accepted: 02/26/2008] [Indexed: 01/18/2023]
Abstract
To further understand the neuroanatomy, neurochemistry and neuropathology of the normal and diseased human brain, it is essential to have access to human brain tissue where the biological and chemical nature of the tissue is optimally preserved. We have established a human brain bank where brain tissue is optimally processed and stored in order to provide a resource to facilitate neuroscience research of the human brain in health and disease. A donor programme has been established in consultation with the community to provide for the post-mortem donation of brain tissue to the brain bank. We are using this resource of human brain tissue to further investigate the basis of normal neuronal functioning in the human brain as well as the mechanisms of neuronal dysfunction and degeneration in neurodegenerative diseases. We have established a protocol for the preservation of post-mortem adult human brain tissue firstly by snap-freezing unfixed brain tissue and secondly by chemical fixation and then storage of this tissue at -80 degrees C in a human brain bank. Several research techniques such as receptor autoradiography, DNA and RNA analysis, are carried out on the unfixed tissue and immunohistochemical and histological analysis is carried out on the fixed human tissue. Comparison of tissue from normal control cases and from cases with neurodegenerative disorders is carried out in order to document the changes that occur in the brain in these disorders and to further investigate the underlying pathogenesis of these devastating neurological diseases.
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Affiliation(s)
- H J Waldvogel
- Department of Anatomy with Radiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
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Chung SH, Marzban H, Croci L, Consalez GG, Hawkes R. Purkinje cell subtype specification in the cerebellar cortex: early B-cell factor 2 acts to repress the zebrin II-positive Purkinje cell phenotype. Neuroscience 2008; 153:721-32. [PMID: 18403128 DOI: 10.1016/j.neuroscience.2008.01.090] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 01/23/2008] [Accepted: 01/30/2008] [Indexed: 11/16/2022]
Abstract
The mammalian cerebellar cortex is highly compartmentalized. First, it is subdivided into four transverse expression domains: the anterior zone (AZ), the central zone (CZ), the posterior zone (PZ), and the nodular zone (NZ). Within each zone, the cortex is further subdivided into a symmetrical array of parasagittal stripes. The most extensively studied compartmentation antigen is zebrin II/aldolase c, which is expressed by a subset of Purkinje cells forming parasagittal stripes. Stripe phenotypes are specified early in cerebellar development, in part through the action of early B-cell factor 2 (Ebf2), a member of the atypical helix-loop-helix transcription factor family Collier/Olf1/EBF. In the murine cerebellum, Ebf2 expression is restricted to the zebrin II-immunonegative (zebrin II-) Purkinje cell population. We have identified multiple cerebellar defects in the Ebf2 null mouse involving a combination of selective Purkinje cell death and ectopic expression of multiple genes normally restricted to the zebrin II- subset. The nature of the cerebellar defect in the Ebf2 null is different in each transverse zone. In contrast to the ectopic expression of genes characteristic of the zebrin II+ Purkinje cell phenotype, phospholipase Cbeta4 expression, restricted to zebrin II- Purkinje cells in control mice, is well maintained, and the normal number of stripes is present. Taken together, these data suggest that Ebf2 regulates the expression of genes associated with the zebrin II+ Purkinje cell phenotype and that the zebrin II- Purkinje cell subtype is specified independently.
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Affiliation(s)
- S-H Chung
- Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
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Darbin O, Wichmann T. Effects of Striatal GABAA-Receptor Blockade on Striatal and Cortical Activity in Monkeys. J Neurophysiol 2008; 99:1294-305. [DOI: 10.1152/jn.01191.2007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To elucidate the role of ambient striatal γ-aminobutyric acid (GABA) in the regulation of neuronal activity in the basal ganglia–thalamocortical circuits, we studied the effects of blocking striatal GABAA receptors on the electrical activities of single striatal neurons, on local field potentials (LFPs) in the striatum, and on motor cortical electroencephalograms (EEGs) in two monkeys. Striatal LFPs were recorded with a device that allowed us to simultaneously record field potentials and apply drugs by reverse microdialysis at the same site. Administration of the GABAA-receptor antagonist gabazine (SR95531, 10 and 500 μM) induced large-amplitude LFP fluctuations at the infusion site, occurring every 2–5 s for about 2 h after the start of the 20-min drug administration. These events were prevented by cotreatment with a GABAA-receptor agonist (muscimol, 100 μM) or a combination of ionotropic glutamate receptor antagonists (CNQX and MK-801, each given at 100 μM). Gabazine (10 μM) also increased the firing of single neurons recorded close to the injection site, but in most cases there was no correlation between single-neuron activity and the concomitantly recorded LFP signals from the same striatal region. In contrast, intrastriatal application of gabazine increased the correlation between striatal LFPs and EEG, and resulted in the appearance of recurrent EEG events that were temporally related to the striatal LFP events. These data provide evidence that a GABAergic “tone” in the monkey striatum controls the spontaneous activity of striatal neurons, as well as the level of striatal and cortical synchrony.
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Brückner G, Morawski M, Arendt T. Aggrecan-based extracellular matrix is an integral part of the human basal ganglia circuit. Neuroscience 2008; 151:489-504. [DOI: 10.1016/j.neuroscience.2007.10.033] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 10/26/2007] [Accepted: 11/02/2007] [Indexed: 11/28/2022]
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Bernácer J, Prensa L, Giménez-Amaya JM. Cholinergic interneurons are differentially distributed in the human striatum. PLoS One 2007; 2:e1174. [PMID: 18080007 PMCID: PMC2137841 DOI: 10.1371/journal.pone.0001174] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 10/24/2007] [Indexed: 11/18/2022] Open
Abstract
Background The striatum (caudate nucleus, CN, and putamen, Put) is a group of subcortical nuclei involved in planning and executing voluntary movements as well as in cognitive processes. Its neuronal composition includes projection neurons, which connect the striatum with other structures, and interneurons, whose main roles are maintaining the striatal organization and the regulation of the projection neurons. The unique electrophysiological and functional properties of the cholinergic interneurons give them a crucial modulating function on the overall striatal response. Methodology/Principle Findings This study was carried out using stereological methods to examine the volume and density (cells/mm3) of these interneurons, as visualized by choline acetyltransferase (ChAT) immunoreactivity, in the following territories of the CN and Put of nine normal human brains: 1) precommissural head; 2) postcommissural head; 3) body; 4) gyrus and 5) tail of the CN; 6) precommissural and 7) postcommissural Put. The distribution of ChAT interneurons was analyzed with respect to the topographical, functional and chemical territories of the dorsal striatum. The CN was more densely populated by cholinergic neurons than the Put, and their density increased along the anteroposterior axis of the striatum with the CN body having the highest neuronal density. The associative territory of the dorsal striatum was by far the most densely populated. The striosomes of the CN precommissural head and the postcommissural Put contained the greatest number of ChAT-ir interneurons. The intrastriosomal ChAT-ir neurons were abundant on the periphery of the striosomes throughout the striatum. Conclusions/Significance All these data reveal that cholinergic interneurons are differentially distributed in the distinct topographical and functional territories of the human dorsal striatum, as well as in its chemical compartments. This heterogeneity may indicate that the posterior aspects of the CN require a special integration of information by interneurons. Interestingly, these striatal regions have been very much left out in functional studies.
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Affiliation(s)
- Javier Bernácer
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - Lucía Prensa
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - José Manuel Giménez-Amaya
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- * To whom correspondence should be addressed. E-mail:
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Alam MS, Huang J, Ozoe F, Matsumura F, Ozoe Y. Synthesis, 3D-QSAR, and docking studies of 1-phenyl-1H-1,2,3-triazoles as selective antagonists for β3 over α1β2γ2 GABA receptors. Bioorg Med Chem 2007; 15:5090-104. [PMID: 17544280 DOI: 10.1016/j.bmc.2007.05.039] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2007] [Revised: 05/13/2007] [Accepted: 05/15/2007] [Indexed: 11/21/2022]
Abstract
A series of 16 1-phenyl-1H-1,2,3-triazoles with substituents at both the 4- and 5-positions of the triazole ring were synthesized, and a total of 49 compounds, including previously reported 4- or 5-monosubstituted analogues, were examined for their ability to inhibit the specific binding of [(3)H]4'-ethynyl-4-n-propylbicycloorthobenzoate (EBOB), a non-competitive antagonist, to human homo-oligomeric beta3 and hetero-oligomeric alpha1beta2gamma2 gamma-aminobutyric acid (GABA) receptors. Among all tested compounds, the 4-n-propyl-5-chloromethyl analogue of 1-(2,6-dichloro-4-trifluoromethylphenyl)-1H-1,2,3-triazole showed the highest level of affinity for both beta3 and alpha1beta2gamma2 receptors, with K(i) values of 659pM and 266nM, respectively. Most of the tested compounds showed selectivity for beta3 over alpha1beta2gamma2 receptors. Among all 1-phenyl-1H-1,2,3-triazoles, the 4-n-propyl-5-ethyl analogue exhibited the highest (>1133-fold) selectivity, followed by the 4-n-propyl-5-methyl analogue of 1-(2,6-dibromo-4-trifluoromethylphenyl)-1H-1,2,3-triazole with a >671-fold selectivity. The 2,6-dichloro plus 4-trifluoromethyl substitution pattern on the benzene ring was found to be important for the high affinity for both beta3 and alpha1beta2gamma2 receptors. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) provided similar contour maps, revealing that an electronegative substituent at the 4-position of the benzene ring, a compact, hydrophobic substituent at the 4-position of the triazole ring, and a small, electronegative substituent at the 5-position of the triazole ring play significant roles for the high potency in beta3 receptors. Molecular docking studies suggested that the putative binding sites for 1-phenyl-1H-1,2,3-triazole antagonists are located in the channel-lining 2'-6' region of the second transmembrane segment of beta3 and alpha1beta2gamma2 receptors. A difference in the hydrophobic environment at the 2' position might underlie the selectivity of 1-phenyl-1H-1,2,3-triazoles for beta3 over alpha1beta2gamma2 receptors. The compounds that had high affinity for beta3 receptors with homology to insect GABA receptors showed insecticidal activity against houseflies with LD(50) values in the pmol/fly range. The information obtained in the present study should prove helpful for the discovery of selective insect control chemicals.
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Affiliation(s)
- Mohammad Sayed Alam
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane, Japan
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Higashi S, Biskup S, West AB, Trinkaus D, Dawson VL, Faull RLM, Waldvogel HJ, Arai H, Dawson TM, Moore DJ, Emson PC. Localization of Parkinson’s disease-associated LRRK2 in normal and pathological human brain. Brain Res 2007; 1155:208-19. [PMID: 17512502 DOI: 10.1016/j.brainres.2007.04.034] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 04/04/2007] [Accepted: 04/07/2007] [Indexed: 01/26/2023]
Abstract
Mutations in the LRRK2 gene cause autosomal dominant, late-onset parkinsonism, which presents with pleomorphic pathology including alpha-synucleopathy. To promote our understanding of the biological role of LRRK2 in the brain we examined the distribution of LRRK2 mRNA and protein in postmortem human brain tissue from normal and neuropathological subjects. In situ hybridization and immunohistochemical analysis demonstrate the expression and localization of LRRK2 to various neuronal populations in brain regions implicated in Parkinson's disease (PD) including the cerebral cortex, caudate-putamen and substantia nigra pars compacta. Immunofluorescent double labeling studies additionally reveal the prominent localization of LRRK2 to cholinergic-, calretinin- and GABA(B) receptor 1-positive, dopamine-innervated, neuronal subtypes in the caudate-putamen. The distribution of LRRK2 in brain tissue from sporadic PD and dementia with Lewy bodies (DLB) subjects was also examined. In PD brains, LRRK2 immunoreactivity localized to nigral neuronal processes is dramatically reduced which reflects the disease-associated loss of dopaminergic neurons in this region. However, surviving nigral neurons occasionally exhibit LRRK2 immunostaining of the halo structure of Lewy bodies. Moreover, LRRK2 immunoreactivity is not associated with Lewy neurites or with cortical Lewy bodies in sporadic PD and DLB brains. These observations indicate that LRRK2 is not a primary component of Lewy bodies and does not co-localize with mature fibrillar alpha-synuclein to a significant extent. The localization of LRRK2 to key neuronal populations throughout the nigrostriatal dopaminergic pathway is consistent with the involvement of LRRK2 in the molecular pathogenesis of familial and sporadic parkinsonism.
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Affiliation(s)
- Shinji Higashi
- Laboratory of Molecular Neuroscience, The Babraham Institute, Babraham, Cambridge, UK
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Abstract
The external segment of the pallidum (GP(e)) is a relatively large nucleus located caudomedial to the neostriatum (Str). The GP(e) receives major inputs from two major basal ganglia input nuclei, the Str and the subthalamic nucleus (STN), and sends its output to many basal ganglia nuclei including the STN, the Str, the internal pallidal segment (GP(i)), and the substantia nigra (SN). Thus, the GPe can be placed at the center of the basal ganglia connection diagram (Fig. 1(A)). From the viewpoint that emphasizes the direct and indirect pathways of the basal ganglia, the GP(e) is a component of the indirect pathway that relays Str inputs to the STN. The indirect pathway can be traced in Fig. 1(A), although it comprises only a part of multiple indirect pathways. This chapter begins with a brief description of the anatomical organization of the GP(e) followed by physiological and pharmacological characterizations of GABAergic responses in the GP(e).
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Affiliation(s)
- Hitoshi Kita
- Department of Anatomy and Neurobiology, The University of Tennessee Memphis, 855 Monroe Avenue, Memphis, TN 38163, USA.
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Abstract
The majority of neurons in the basal ganglia utilize GABA as their principal neurotransmitter and, as a consequence, most basal ganglia neurons receive extensive GABAergic inputs derived from multiple sources. In order to understand the diverse roles of GABA in the basal ganglia it is necessary to define the precise localization of GABA receptors in relation to known neuron subtypes and known afferents. In this chapter, we summarize data on the ultrastructural localization of ionotropic GABA(A) receptors and metabotropic GABA(B) receptors in the basal ganglia. In each of the regions of the basal ganglia that have been studied, GABA(A) receptor subunits are located primarily at symmetrical synapses formed by GABAergic boutons, where they display a several-hundred-fold enrichment over extrasynaptic sites. In contrast, GABA(B) receptors are widely distributed at synaptic and extrasynaptic sites on both presynaptic and postsynaptic membranes. Presynaptic GABA(B) receptors are localized on striatopallidal, striatonigral and pallidonigral afferent terminals, as well as glutamatergic terminals derived from the cortex, thalamus and subthalamic nucleus. It is concluded that fast GABA transmission mediated by GABA(A) receptors in the basal ganglia occurs primarily at synapses whereas GABA transmission mediated by GABA(B) receptors is more complex, involving receptors located at presynaptic, postsynaptic and extrasynaptic sites.
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Affiliation(s)
- Justin Boyes
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
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Waldvogel H, Baer K, Gai WP, Gilbert R, Rees M, Mohler H, Faull R. Differential localization of GABAA receptor subunits within the substantia nigra of the human brain: An immunohistochemical study. J Comp Neurol 2007; 506:912-29. [DOI: 10.1002/cne.21573] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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