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Li R, Wang Y, Yang Y, Wu Z, Wang L, Tang G, Yang J, Liu J. The α1 and γ2 subunit-containing GABA A receptor-mediated inhibitory transmission in the anteroventral bed nucleus of stria terminalis is involved in the regulation of anxiety in rats with substantia nigra lesions. Neuropharmacology 2023:109645. [PMID: 37392819 DOI: 10.1016/j.neuropharm.2023.109645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/08/2023] [Accepted: 06/22/2023] [Indexed: 07/03/2023]
Abstract
The anteroventral bed nucleus of the stria terminalis (avBNST) is widely acknowledged as a key brain structure that regulates negative emotional states, such as anxiety. At present, it is still unclear whether GABAA receptor-mediated inhibitory transmission in the avBNST is involved in Parkinson's disease (PD)-related anxiety. In this study, unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra pars compacta (SNc) in rats induced anxiety-like behaviors, increased GABA synthesis and release, and upregulated expression of GABAA receptor subunits in the avBNST, as well as decreased level of dopamine (DA) in the basolateral amygdala (BLA). In both sham and 6-OHDA rats, intra-avBNST injection of GABAA receptor agonist muscimol induced the following changes: (i) anxiolytic-like responses, (ii) inhibition of the firing activity of GABAergic neurons in the avBNST, (iii) excitation of dopaminergic neurons in the ventral tegmental area (VTA) and serotonergic neurons in the dorsal raphe nucleus (DRN), and (iv) increase of DA and 5-HT release in the BLA, whereas antagonist bicuculline induced the opposite effects. Collectively, these findings suggest that degeneration of the nigrostriatal pathway enhances GABAA receptor-mediated inhibitory transmission in the avBNST, which is involved in PD-related anxiety. Further, activation and blockade of avBNST GABAA receptors affect the firing activity of VTA dopaminergic and DRN serotonergic neurons, and then change release of BLA DA and 5-HT, thereby regulating anxiety-like behaviors.
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Affiliation(s)
- Ruotong Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Yong Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Yaxin Yang
- Department of Rehabilitation Medicine, The Second Affiliated Hospital, Xi'an Jiaotong University, Xi'an, 710004, China
| | - Zhongheng Wu
- Department of Rehabilitation Medicine, The Second Affiliated Hospital, Xi'an Jiaotong University, Xi'an, 710004, China
| | - Ling Wang
- Department of Rehabilitation Medicine, The Second Affiliated Hospital, Xi'an Jiaotong University, Xi'an, 710004, China
| | - Guoyi Tang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Jie Yang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Jian Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China.
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Wang Y, Gu L, Yang HM, Zhang H. Cystic fibrosis transmembrane conductance regulator-associated ligand protects dopaminergic neurons by differentially regulating metabotropic glutamate receptor 5 in the progression of neurotoxin 6-hydroxydopamine-induced Parkinson's disease model. Neurotoxicology 2021; 84:14-29. [PMID: 33571554 DOI: 10.1016/j.neuro.2021.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 12/21/2020] [Accepted: 02/04/2021] [Indexed: 10/22/2022]
Abstract
Due to limitations in early diagnosis and treatments of Parkinson's disease (PD), it is necessary to explore the neuropathological changes that occur early in PD progression and to design neuroprotective therapies to prevent or delay the ongoing degeneration process. Metabotropic glutamate receptor 5 (mGlu5) has shown both diagnostic and therapeutic potential in preclinical studies on PD. Clinical trials using mGlu5 negative allosteric modulators to treat PD have, however, raised limitations about the neuroprotective role of mGlu5. It is likely that mGlu5 has different regulatory roles in different stages of PD. Here, we investigated a protective role of cystic fibrosis transmembrane conductance regulator-associated ligand (CAL) in the progression of PD by differential regulation of mGlu5 expression and activity to protect against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity. Following treatment with 6-OHDA, mGlu5 and CAL expressions were elevated in the early stage and reduced in the late stage, both in vitro and in vivo. Activation of mGlu5 in the early stage by (RS)-2-chloro-5-hydroxyphenylglycine, or blocking mGlu5 in the late stage by 2-methyl-6-(phenylethynyl) pyridine, increased cell survival and inhibited apoptosis, but these effects were significantly weakened by knockdown of CAL. CAL alleviated 6-OHDA-induced neurotoxicity by regulating mGlu5-mediated signaling pathways, thereby maintaining the physiological function of mGlu5 in different disease stages. In PD rat model, CAL deficiency aggravated 6-OHDA toxicity on dopaminergic neurons and increased motor dysfunction because of lack of regulation of mGlu5 activity. These data reveal a potential mechanism by which CAL specifically regulates the opposite activity of mGlu5 in progression of PD to protect against neurotoxicity, suggesting that CAL is a favorable endogenous target for the treatment of PD.
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Affiliation(s)
- Yuan Wang
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing Institute for Brain Disorders, Capital Medical University, No. 10 Xitoutiao, You An Men, Beijing, 100069, China
| | - Li Gu
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing Institute for Brain Disorders, Capital Medical University, No. 10 Xitoutiao, You An Men, Beijing, 100069, China
| | - Hui Min Yang
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing Institute for Brain Disorders, Capital Medical University, No. 10 Xitoutiao, You An Men, Beijing, 100069, China
| | - Hong Zhang
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing Institute for Brain Disorders, Capital Medical University, No. 10 Xitoutiao, You An Men, Beijing, 100069, China.
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Luo WY, Xing SQ, Zhu P, Zhang CG, Yang HM, Van Halm-Lutterodt N, Gu L, Zhang H. PDZ Scaffold Protein CAL Couples with Metabotropic Glutamate Receptor 5 to Protect Against Cell Apoptosis and Is a Potential Target in the Treatment of Parkinson's Disease. Neurotherapeutics 2019; 16:761-783. [PMID: 31073978 PMCID: PMC6694344 DOI: 10.1007/s13311-019-00730-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Targeting mGluR5 has been an attractive strategy to modulate glutamate excitotoxicity for neuroprotection. Although human clinical trials using mGluR5 negative allosteric modulators (NAMs) have included some disappointments, recent investigations have added several more attractive small molecules to this field, providing a promise that the identification of more additional strategies to modulate mGluR5 activity might be potentially beneficial for the advancement of PD treatment. Here, we determined the role of the interacting partner CAL (cystic fibrosis transmembrane conductance regulator-associated ligand) in mGluR5-mediated protection in vitro and in vivo. In astroglial C6 cells, CAL deficiency blocked (S)-3, 5-dihydroxyphenylglycine (DHPG)-elicited p-AKT and p-ERK1/2, subsequently prevented group I mGluRs-mediated anti-apoptotic protection, which was blocked by receptor antagonist 1-aminoindan-1, 5-dicarboxylic acid (AIDA), and PI3K or MEK inhibitor LY294002 or U0126. In rotenone-treated MN9D cells, both CAL and mGluR5 expressions were decreased in a time- and dose-dependent manner, and the correlation between these 2 proteins was confirmed by lentivirus-delivered CAL overexpression and knockdown. Moreover, CAL coupled with mGluR5 upregulated mGluR5 protein expression by inhibition of ubiquitin-proteasome-dependent degradation to suppress mGluR5-mediated p-JNK and to protect against cell apoptosis. Additionally, CAL also inhibited rotenone-induced glutamate release to modulate mGluR5 activity. Furthermore, in the rotenone-induced rat model of PD, AAV-delivered CAL overexpression attenuated behavioral deficits and dopaminergic neuronal death, while CAL deficiency aggravated rotenone toxicity. On the other hand, the protective effect of the mGluR5 antagonist MPEP was weakened by knocking down CAL. In vivo experiments also confirmed that CAL inhibited ubiquitination-proteasome-dependent degradation to modulate mGluR5 expression and JNK phosphorylation. Our findings show that CAL protects against cell apoptosis via modulating mGluR5 activity, and may be a new molecular target for an effective therapeutic strategy for PD.
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Affiliation(s)
- Wen Yuan Luo
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Institute for Brain Disorders and Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Su Qian Xing
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Institute for Brain Disorders and Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Ping Zhu
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Institute for Brain Disorders and Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Chen Guang Zhang
- Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, 100069, China
| | - Hui Min Yang
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Institute for Brain Disorders and Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Nicholas Van Halm-Lutterodt
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100069, China
- Department of Orthopaedics and Neurosurgery, Keck Medical Center, University of Southern California, Los Angeles, CA, 90033, USA
| | - Li Gu
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Institute for Brain Disorders and Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China.
| | - Hong Zhang
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Institute for Brain Disorders and Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China.
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Aono H, Choudhury ME, Higaki H, Miyanishi K, Kigami Y, Fujita K, Akiyama JI, Takahashi H, Yano H, Kubo M, Nishikawa N, Nomoto M, Tanaka J. Microglia may compensate for dopaminergic neuron loss in experimental Parkinsonism through selective elimination of glutamatergic synapses from the subthalamic nucleus. Glia 2017; 65:1833-1847. [PMID: 28836295 DOI: 10.1002/glia.23199] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 06/19/2017] [Accepted: 07/23/2017] [Indexed: 12/20/2022]
Abstract
Parkinson's disease (PD) symptoms do not become apparent until most dopaminergic neurons in the substantia nigra pars compacta (SNc) degenerate, suggesting that compensatory mechanisms play a role. Here, we investigated the compensatory involvement of activated microglia in the SN pars reticulata (SNr) and the globus pallidus (GP) in a 6-hydroxydopamine-induced rat hemiparkinsonism model. Activated microglia accumulated more markedly in the SNr than in the SNc in the model. The cells had enlarged somata and expressed phagocytic markers CD68 and NG2 proteoglycan in a limited region of the SNr, where synapsin I- and postsynaptic density 95-immunoreactivities were reduced. The activated microglia engulfed pre- and post-synaptic elements, including NMDA receptors into their phagosomes. Cells in the SNr and GP engulfed red fluorescent DiI that was injected into the subthalamic nucleus (STN) as an anterograde tracer. Rat primary microglia increased their phagocytic activities in response to glutamate, with increased expression of mRNA encoding phagocytosis-related factors. The synthetic glucocorticoid dexamethasone overcame the stimulating effect of glutamate. Subcutaneous single administration of dexamethasone to the PD model rats suppressed microglial activation in the SNr, resulting in aggravated motor dysfunctions, while expression of mRNA encoding glutamatergic, but not GABAergic, synaptic elements increased. These findings suggest that microglia in the SNr and GP become activated and selectively eliminate glutamatergic synapses from the STN in response to increased glutamatergic activity. Thus, microglia may be involved in a negative feedback loop in the indirect pathway of the basal ganglia to compensate for the loss of dopaminergic neurons in PD brains.
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Affiliation(s)
- Hitomi Aono
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | | | - Hiromi Higaki
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Kazuya Miyanishi
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Yuka Kigami
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Kohdai Fujita
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Jun-Ichi Akiyama
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Hisaaki Takahashi
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan.,Division of Pathophysiology, Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Ishikawa, Japan
| | - Hajime Yano
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Madoka Kubo
- Department of Therapeutic Medicine, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Noriko Nishikawa
- Department of Therapeutic Medicine, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Masahiro Nomoto
- Department of Therapeutic Medicine, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Junya Tanaka
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
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Wang T, Zhang L, Zhang QJ, Wang Y, Du CX, Sun YN, Zhang J, Lv SX, Chen L, Liu J. Involvement of lateral habenula α1 subunit-containing GABA A receptor-mediated inhibitory transmission in the regulation of depression-related behaviors in experimental Parkinson's disease. Neuropharmacology 2017; 116:399-411. [PMID: 28109827 DOI: 10.1016/j.neuropharm.2017.01.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 10/27/2016] [Accepted: 01/17/2017] [Indexed: 02/06/2023]
Abstract
The lateral habenula (LHb) plays an important role in the regulation of depression. At present, it is not clear whether GABAA receptor-mediated inhibitory transmission in the LHb is involved in Parkinson's disease (PD)-associated depression. In this study, unilateral 6-hydroxydopamine lesions of the substantia nigra in rats induced depressive-like behaviors and led to hyperactivity of LHb neurons compared to sham-operated rats, which attribute to depletion of dopamine, and decreased synthesis and release of GABA and increased release of glutamate in the LHb. Intra-LHb injection of GABAA receptor agonist muscimol produced antidepressant-like effects, while the injection of GABAA receptor antagonist picrotoxin induced or increased the expression of depressive-like behaviors in sham-operated and the lesioned rats. However, the doses producing these behavioral effects in the lesioned rats were lower than those in sham-operated rats. Intra-LHb injection of muscimol decreased the firing rate of LHb neurons and increased the medial prefrontal cortex serotonin (5-HT) release; conversely, picrotoxin increased the firing rate of the neurons and decreased 5-HT release in two groups of rats. Compared to sham-operated rats, the duration of muscimol and picrotoxin action on the firing rate of the neurons and 5-HT release was prolonged in the lesioned rats. These changes in the lesioned rats were associated with up-regulation of the expression of α1 subunit-containing GABAA receptors and reduction of GABA release in the LHb. Collectively, our findings suggest that degeneration of the nigrostriatal pathway impairs GABAA receptor-mediated inhibitory transmission in the LHb, and the transmission is important for regulating PD-associated depression.
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Affiliation(s)
- Tao Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Li Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education of China, Xi'an 710061, China
| | - Qiao-Jun Zhang
- Department of Rehabilitation Medicine, The Second Hospital, Xi'an Jiaotong University, Xi'an 710004, China
| | - Yong Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education of China, Xi'an 710061, China
| | - Cheng-Xue Du
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Yi-Na Sun
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Jin Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Shu-Xuan Lv
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China
| | - Li Chen
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education of China, Xi'an 710061, China
| | - Jian Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education of China, Xi'an 710061, China.
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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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Waldvogel H, Faull R. The Diversity of GABAA Receptor Subunit Distribution in the Normal and Huntington's Disease Human Brain1. DIVERSITY AND FUNCTIONS OF GABA RECEPTORS: A TRIBUTE TO HANNS MÖHLER, PART B 2015; 73:223-64. [DOI: 10.1016/bs.apha.2014.11.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Proliferation of external globus pallidus-subthalamic nucleus synapses following degeneration of midbrain dopamine neurons. J Neurosci 2013; 32:13718-28. [PMID: 23035084 DOI: 10.1523/jneurosci.5750-11.2012] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The symptoms of Parkinson's disease (PD) are related to changes in the frequency and pattern of activity in the reciprocally connected GABAergic external globus pallidus (GPe) and glutamatergic subthalamic nucleus (STN). In idiopathic and experimental PD, the GPe and STN exhibit hypoactivity and hyperactivity, respectively, and abnormal synchronous rhythmic burst firing. Following lesion of midbrain dopamine neurons, abnormal STN activity emerges slowly and intensifies gradually until it stabilizes after 2-3 weeks. Alterations in cellular/network properties may therefore underlie the expression of abnormal firing. Because the GPe powerfully regulates the frequency, pattern, and synchronization of STN activity, electrophysiological, molecular, and anatomical measures of GPe-STN transmission were compared in the STN of control and 6-hydroxydopamine-lesioned rats and mice. Following dopamine depletion: (1) the frequency (but not the amplitude) of mIPSCs increased by ∼70%; (2) the amplitude of evoked IPSCs and isoguvacine-evoked current increased by ∼60% and ∼70%, respectively; (3) mRNA encoding α1, β2, and γ2 GABA(A) receptor subunits increased by 15-30%; (4) the density of postsynaptic gephyrin and γ2 subunit coimmunoreactive structures increased by ∼40%, whereas the density of vesicular GABA transporter and bassoon coimmunoreactive axon terminals was unchanged; and (5) the number of ultrastructurally defined synapses per GPe-STN axon terminal doubled with no alteration in terminal/synapse size or target preference. Thus, loss of dopamine leads, through an increase in the number of synaptic connections per GPe-STN axon terminal, to substantial strengthening of the GPe-STN pathway. This adaptation may oppose hyperactivity but could also contribute to abnormal firing patterns in the parkinsonian STN.
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Abstract
The transplantation of dopaminergic cells for the treatment of symptoms of Parkinson’s disease has several hurdles to overcome before it can be considered a successful therapeutic approach. One issue is the development of abnormal involuntary movements in the absence of L-3,4-dihydroxyphenylalanine following the transplantation of fetal ventral mesencephalon identified in three different clinical trials. Hypotheses as to the cause of these movements include: the composition of the graft, size of the graft, L-3,4-dihydroxyphenylalanine exposure and L-3,4-dihydroxyphenylalanine-induced dyskinesia prior to transplantation and inflammatory responses in and around the graft. We evaluate the clinical evidence supporting these hypotheses and the preclinical models upon which experiments are being based to resolve them.
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Affiliation(s)
- E L Lane
- Brain Repair Group, School of Bioscience, Cardiff University, Cardiff CF10 3AX, Wales, UK.
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11
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Xue Y, Han XH, Chen L. Effects of Pharmacological Block of GABA(A) Receptors on Pallidal Neurons in Normal and Parkinsonian State. Front Cell Neurosci 2010; 4:2. [PMID: 20204138 PMCID: PMC2831626 DOI: 10.3389/neuro.03.002.2010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Accepted: 01/26/2010] [Indexed: 11/19/2022] Open
Abstract
The globus pallidus plays a central integrative role in the basal ganglia circuitry. Morphological studies have revealed a high level of GABA and GABAA receptors in the globus pallidus. To further investigate the effects of endogenous GABAA neurotransmission in the globus pallidus of normal and parkinsonian rats, in vivo extracellular recording and behavioral tests were performed in the present studies. In normal rats, micro-pressure ejection of GABAA receptor antagonist gabazine (0.1 mM) increased the spontaneous firing rate of pallidal neurons by 28.3%. Furthermore, in 6-hydroxydopamine parkinsonian rats, gabazine increased the firing rate by 46.0% on the lesioned side, which was significantly greater than that on the unlesioned side (21.5%, P < 0.05), as well as that in normal rats (P < 0.05). In the behaving rats, unilateral microinjection of gabazine (0.1 mM) evoked consistent contralateral rotation in normal rats, and significantly potentiated the number of apomorphine-induced contralateral rotations in parkinsonian rats. The present electrophysiological and behavioral findings may provide a rational for further investigations into the potential of pallidal endogenous GABAA neurotransmission in the treatment of Parkinson's disease.
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Affiliation(s)
- Yan Xue
- Department of Physiology, Qingdao University Qingdao, China
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12
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Galvan A, Wichmann T. GABAergic circuits in the basal ganglia and movement disorders. PROGRESS IN BRAIN RESEARCH 2007; 160:287-312. [PMID: 17499121 DOI: 10.1016/s0079-6123(06)60017-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
GABA is the major inhibitory neurotransmitter in the basal ganglia, and GABAergic pathways dominate information processing in most areas of these structures. It is therefore not surprising that abnormalities of GABAergic transmission are key elements in pathophysiologic models of movement disorders involving the basal ganglia. These include hypokinetic diseases such as Parkinson's disease, and hyperkinetic diseases, such as Huntington's disease or hemiballism. In this chapter, we will briefly review the major anatomic features of the GABAergic pathways in the basal ganglia, and then describe in greater detail the changes of GABAergic transmission, which are known to occur in movement disorders.
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Affiliation(s)
- Adriana Galvan
- Department of Neurology, School of Medicine and Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA.
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McOmish CE, Hannan AJ. Enviromimetics: exploring gene environment interactions to identify therapeutic targets for brain disorders. Expert Opin Ther Targets 2007; 11:899-913. [PMID: 17614759 DOI: 10.1517/14728222.11.7.899] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
There is a growing awareness of the central role played by environmental factors in many of the most debilitating neural disorders. Epidemiological studies have suggested a complex balance between genetic and environmental factors in the pathogenesis of neurological and psychiatric conditions. The use of accurate animal models, combined with experimental manipulations such as environmental enrichment, has shown that increased sensory, cognitive and motor stimulation has beneficial effects in a range of CNS disorders, including Huntington's, Alzheimer's, Parkinson's and other neurodegenerative diseases. Various studies have identified molecular, structural and functional correlates of this experience-dependent plasticity. The authors propose that the molecular systems which mediate the therapeutic effects of environmental enrichment may provide novel targets for pharmacotherapies. More specifically, they elaborate a theoretical framework for the development of 'enviromimetics', therapeutics that mimic or enhance the beneficial effects of environmental stimulation, targeted towards a wide range of nervous system disorders.
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Affiliation(s)
- Caitlin E McOmish
- Howard Florey Institute, University of Melbourne, VIC 3010, Australia
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Fragioudaki K, Kouvelas ED, Cristiani R, Giompres P, Bagnoli P, Mitsacos A. Expression of amino acid receptors and neural peptides in the weaver mouse brain. Brain Res 2007; 1140:132-52. [PMID: 16626633 DOI: 10.1016/j.brainres.2006.03.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 03/01/2006] [Accepted: 03/07/2006] [Indexed: 12/29/2022]
Abstract
In the present study, we conducted: (i) in situ hybridization in order to investigate the expression of kainate and GABA(A) receptor subunits and the pre-proenkephalin and prodynorphin peptides in the brain of weaver mouse (a genetic model of dopamine deficiency) and (ii) immunocytochemistry in order to study the somatostatin-positive cells in weaver striatum. Our results indicated: (i) increases in mRNA levels of KA2 and GluR6 kainate receptor subunits, of alpha(4) and beta(3) GABA(A) receptor subunits and of pre-proenkephalin and prodynorphin in 6-month-old weaver striatum; (ii) a decrease in alpha(1) and beta(2) GABA(A) subunit mRNAs in 6-month-old weaver globus pallidus; (iii) increases in KA2, alpha(4) and beta(3) and decreases in alpha(2) and beta(2) mRNAs in the 6-month-old weaver somatosensory cortex; and (iv) an increase in somatostatin-immunopositive cells in 3-month-old weaver striatum. We suggest that: (i) in striatum, the alterations are induced by the induction of the transcription factor DeltafosB (for GluR6, pre-proenkephalin and prodynorphin mRNAs) and the suppression of transcription factors like NGF-IB (nerve growth factor inducible B; for the KA2 mRNA), in response to dopamine depletion; (ii) in striatum and cortex, the alterations in the expression of the GABA(A) subunits indicate an increase of extrasynaptic versus a decrease of synaptic GABA(A) receptors; and (iii) in globus pallidus, the increased striatopallidal GABAergic transmission leads to a decrease in the number of GABA(A) receptors. Our results further clarify the regulatory role of dopamine in the expression of amino acid receptors and striatal neuropeptides.
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Affiliation(s)
- Kleopatra Fragioudaki
- Department of Physiology, Faculty of Medicine, University of Patras, 26504 Patras, Greece
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Ismayilova N, Verkhratsky A, Dascombe MJ. Changes in mGlu5 receptor expression in the basal ganglia of reserpinised rats. Eur J Pharmacol 2006; 545:134-41. [PMID: 16890937 DOI: 10.1016/j.ejphar.2006.06.076] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Revised: 06/26/2006] [Accepted: 06/28/2006] [Indexed: 11/19/2022]
Abstract
Dopamine depletion in Parkinson's disease results in a series of pathophysiological changes in the basal ganglia circuitry. Increased release of glutamate plays an important role in this motor disorder, therefore, agents interacting with glutamatergic transmission may have therapeutic potential. In this study we investigated changes in both mRNA expression and the number of binding sites of the mGlu5 receptor in a reserpinised rat model of Parkinson's disease. The in situ hybridisation demonstrated that acute reserpine treatment caused a significant decrease in the expression of mGlu5 receptor mRNA in the rostral and caudal parts of the rat striatum. At the same time, tritium-labelled 2-ethyl-6-(phenylethynyl)-pyridine ([(3)H]MPEP) ligand binding experiments detected a significant increase in the total number of mGlu5 receptors in the same region of the motor loop. These apparently contradictory data can be explained by mGlu5 receptor turnover being down-regulated in reserpinised rats, due possibly to an imbalance in the rates of synthesis/insertion and internalisation/degradation of the receptor. These findings suggest that changes such as these affecting mGlu5 receptors may be involved in the pathophysiological consequences of dopamine depletion in the brain.
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Affiliation(s)
- Naila Ismayilova
- The University of Manchester, Faculty of Life Sciences, 1.124 Stopford Building, Oxford Road, Manchester M13 9PT, UK
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Shen KZ, Johnson SW. Dopamine depletion alters responses to glutamate and GABA in the rat subthalamic nucleus. Neuroreport 2005; 16:171-4. [PMID: 15671871 DOI: 10.1097/00001756-200502080-00021] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We used whole-cell recordings to compare currents evoked by glutamate and GABA receptor agonists in subthalamic nucleus neurons located ipsilateral and contralateral to unilateral 6-hydroxydopamine (6-OHDA) injections into the substantia nigra zona compacta. The ratio of currents evoked by AMPA (0.6 microM) and NMDA (20 microM) was significantly greater in neurons recorded ipsilateral to 6-OHDA lesions compared with the ratio of currents recorded in control (contralateral) neurons. Both the GABA(A) agonist isoguvacine (20 microM) and the GABA(B) agonist baclofen (10 microM) evoked significantly greater outward currents in subthalamic nucleus neurons ipsilateral to the lesion compared to contralateral neurons. We conclude that chronic dopamine depletion up-regulates expression of GABA receptors and shifts the functional expression of ionotropic glutamate receptor subtype from NMDA to AMPA receptors in subthalamic nucleus.
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Affiliation(s)
- Ke-Zhong Shen
- 1Department of Neurology, Oregon Health and Science University, Portland, OR 97239, USA
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17
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Funchal C, Dall Bello Pessutto F, de Almeida LMV, de Lima Pelaez P, Loureiro SO, Vivian L, Wajner M, Pessoa-Pureur R. Alpha-keto-beta-methylvaleric acid increases the in vitro phosphorylation of intermediate filaments in cerebral cortex of young rats through the gabaergic system. J Neurol Sci 2004; 217:17-24. [PMID: 14675604 DOI: 10.1016/j.jns.2003.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In this study we investigated the effects of alpha-ketoisovaleric (KIV) and alpha-keto-beta-methylvaleric acids (KMV), metabolites accumulating in the inherited neurometabolic disorder maple syrup urine disease (MSUD), on the in vitro incorporation of 32P into intermediate filament (IF) proteins from cerebral cortex of young rats during development (9-21 days of age) We observed that KMV significantly increased the in vitro incorporation of 32P into the IF proteins studied in cortical slices of 12-day-old rats through the PKA and PKCaMII, with no alteration at the other ages. In contrast, KIV was ineffective in altering the phosphorylating system associated with IF proteins at all ages examined. A similar effect on IF phosphorylation was achieved by incubating cortical slices with gamma-aminobutiric acid (GABA). Furthermore, by using specific GABA antagonists, we verified that KMV induced a stimulatory effect on IF phosphorylation of tissue slices from 12-day-old rats mediated by GABA(A) and GABA(B) receptors. In conclusion, our results indicate the involvement of the GABAergic system in the alterations of IF phosphorylation caused by KMV, one of the branched-chain keto acids accumulating in MSUD.
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Affiliation(s)
- Cláudia Funchal
- Universidade Federal do Rio Grande do Sul, Instituto de Ciências Básicas da Saúde, Departamento de Bioquímica, Rua Ramiro Barcelos 2600 anexo, 90035-003 Porto Alegre, RS, Brazil
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Marino MJ, Awad-Granko H, Ciombor KJ, Conn PJ. Haloperidol-induced alteration in the physiological actions of group I mGlus in the subthalamic nucleus and the substantia nigra pars reticulata. Neuropharmacology 2002; 43:147-59. [PMID: 12213269 DOI: 10.1016/s0028-3908(02)00097-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Excitatory glutamatergic inputs to the subthalamic nucleus (STN), and subthalamic afferents to the substantia nigra pars reticulata (SNr) are believed to play a key role in the pathophysiology of Parkinson's disease (PD). Previously, we have shown that activation of the group I mGlus in the STN and SNr induces a direct depolarization of the neurons in these nuclei. Surprisingly, although both group I mGlus were present in the STN and SNr, mGlu5 alone mediated the DHPG-induced depolarization of the STN, and mGlu1 alone mediated the DHPG-induced depolarization of the SNr. We now report that both mGlu1 and mGlu5 are coexpressed in the same cells in both of these brain regions, and that both receptors play a role in mediating the DHPG-induced increase in intracellular calcium. Furthermore, we demonstrate that the induction of an acute PD-like state using a 16 h haloperidol treatment produces an alteration in the coupling of the group I receptors, such that post-haloperidol, DHPG-induced depolarizations are mediated by both mGlu1 and mGlu5 in the STN and SNr. Therefore, the pharmacology of the group I mGlu-mediated depolarization depends on the state of the system, and alterations in receptor coupling may be evident in pathological states such as PD.
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Affiliation(s)
- M J Marino
- Department of Neuroscience, Merck Research Laboratories, West Point, PA 19486, USA.
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Selective blockade of mGlu5 metabotropic glutamate receptors is protective against methamphetamine neurotoxicity. J Neurosci 2002. [PMID: 11896153 DOI: 10.1523/jneurosci.22-06-02135.2002] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Methamphetamine (MA), a widely used drug of abuse, produces oxidative damage of nigrostriatal dopaminergic terminals. We examined the effect of subtype-selective ligands of metabotropic glutamate (mGlu) receptors on MA neurotoxicity in mice. MA (5 mg/kg, i.p.; injected three times, every 2 hr) induced, 5 d later, a substantial degeneration of striatal dopaminergic terminals associated with reactive gliosis. MA toxicity was primarily attenuated by the coinjection of the noncompetitive mGlu5 receptor antagonists 2-methyl-6-(phenylethynyl)pyridine and (E)-2-methyl-6-styrylpyridine both at 10 mg/kg, i.p.). In contrast, the mGlu1 receptor antagonist 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (10 mg/kg, i.p.), and the mGlu2/3 receptor agonist (-)-2-oxa-4-aminocyclo[3.1.0]hexane-4,6-dicarboxylic acid (1 mg/kg, i.p.), failed to affect MA toxicity. mGlu5 receptor antagonists reduced the production of reactive oxygen species but did not reduce the acute stimulation of dopamine release induced by MA both in striatal synaptosomes and in the striatum of freely moving mice. We conclude that endogenous activation of mGlu5 receptors enables the development of MA neurotoxicity and that mGlu5 receptor antagonists are neuroprotective without interfering with the primary mechanism of action of MA.
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