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Huang YT, Chen YW, Lin TY, Chen JC. Suppression of presynaptic corticostriatal glutamate activity attenuates L-dopa-induced dyskinesia in 6-OHDA-lesioned Parkinson's disease mice. Neurobiol Dis 2024; 193:106452. [PMID: 38401650 DOI: 10.1016/j.nbd.2024.106452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 02/21/2024] [Accepted: 02/21/2024] [Indexed: 02/26/2024] Open
Abstract
A common adverse effect of Parkinson's disease (PD) treatment is L-dopa-induced dyskinesia (LID). This condition results from both dopamine (DA)-dependent and DA-independent mechanisms, as glutamate inputs from corticostriatal projection neurons impact DA-responsive medium spiny neurons in the striatum to cause the dyskinetic behaviors. In this study, we explored whether suppression of presynaptic corticostriatal glutamate inputs might affect the behavioral and biochemical outcomes associated with LID. We first established an animal model in which 6-hydroxydopamine (6-OHDA)-lesioned mice were treated daily with L-dopa (10 mg/kg, i.p.) for 2 weeks; these mice developed stereotypical abnormal involuntary movements (AIMs). When the mice were pretreated with the NMDA antagonist, amantadine, we observed suppression of AIMs and reductions of phosphorylated ERK1/2 and NR2B in the striatum. We then took an optogenetic approach to manipulate glutamatergic activity. Slc17a6 (vGluT2)-Cre mice were injected with pAAV5-Ef1a-DIO-eNpHR3.0-mCherry and received optic fiber implants in either the M1 motor cortex or dorsolateral striatum. Optogenetic inactivation at either optic fiber implant location could successfully reduce the intensity of AIMs after 6-OHDA lesioning and L-dopa treatment. Both optical manipulation strategies also suppressed phospho-ERK1/2 and phospho-NR2B signals in the striatum. Finally, we performed intrastriatal injections of LDN 212320 in the dyskenesic mice to enhance expression of glutamate uptake transporter GLT-1. Sixteen hours after the LDN 212320 treatment, L-dopa-induced AIMs were reduced along with the levels of striatal phospho-ERK1/2 and phospho-NR2B. Together, our results affirm a critical role of corticostriatal glutamate neurons in LID and strongly suggest that diminishing synaptic glutamate, either by suppression of neuronal activity or by upregulation of GLT-1, could be an effective approach for managing LID.
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Affiliation(s)
- Yu-Ting Huang
- Graduate Institute of Biomedical Sciences, School of Medicine, Chang-Gung University, Taoyuan, Taiwan
| | - Ya-Wen Chen
- Graduate Institute of Biomedical Sciences, School of Medicine, Chang-Gung University, Taoyuan, Taiwan
| | - Tze-Yen Lin
- Department and Graduate Institute of Physiology, National Taiwan University, College of Medicine, Taipei, Taiwan
| | - Jin-Chung Chen
- Graduate Institute of Biomedical Sciences, School of Medicine, Chang-Gung University, Taoyuan, Taiwan; Department of Physiology and Pharmacology, Healthy Ageing Research Center, Chang-Gung University, Taiwan; Neuroscience Research Center and Department of Psychiatry, Chang-Gung Memorial Hospitall, Linkou, Taiwan.
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Reeves KC, Kube MJ, Grecco GG, Fritz BM, Muñoz B, Yin F, Gao Y, Haggerty DL, Hoffman HJ, Atwood BK. Mu opioid receptors on vGluT2-expressing glutamatergic neurons modulate opioid reward. Addict Biol 2021; 26:e12942. [PMID: 32686251 PMCID: PMC7854952 DOI: 10.1111/adb.12942] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 12/27/2022]
Abstract
The role of Mu opioid receptor (MOR)‐mediated regulation of GABA transmission in opioid reward is well established. Much less is known about MOR‐mediated regulation of glutamate transmission in the brain and how this relates to drug reward. We previously found that MORs inhibit glutamate transmission at synapses that express the Type 2 vesicular glutamate transporter (vGluT2). We created a transgenic mouse that lacks MORs in vGluT2‐expressing neurons (MORflox‐vGluT2cre) to demonstrate that MORs on the vGluT2 neurons themselves mediate this synaptic inhibition. We then explored the role of MORs in vGluT2‐expressing neurons in opioid‐related behaviors. In tests of conditioned place preference, MORflox‐vGluT2cre mice did not acquire place preference for a low dose of the opioid, oxycodone, but displayed conditioned place aversion at a higher dose, whereas control mice displayed preference for both doses. In an oral consumption assessment, these mice consumed less oxycodone and had reduced preference for oxycodone compared with controls. MORflox‐vGluT2cre mice also failed to show oxycodone‐induced locomotor stimulation. These mice displayed baseline withdrawal‐like responses following the development of oxycodone dependence that were not seen in littermate controls. In addition, withdrawal‐like responses in these mice did not increase following treatment with the opioid antagonist, naloxone. However, other MOR‐mediated behaviors were unaffected, including oxycodone‐induced analgesia. These data reveal that MOR‐mediated regulation of glutamate transmission is a critical component of opioid reward.
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Affiliation(s)
- Kaitlin C. Reeves
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
| | - Megan J. Kube
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
| | - Gregory G. Grecco
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
- Medical Scientist Training Program Indiana University School of Medicine Indianapolis Indiana USA
| | - Brandon M. Fritz
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
| | - Braulio Muñoz
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
| | - Fuqin Yin
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
| | - Yong Gao
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
| | - David L. Haggerty
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
| | - Hunter J. Hoffman
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
| | - Brady K. Atwood
- Department of Pharmacology and Toxicology Indiana University School of Medicine Indianapolis Indiana USA
- Stark Neurosciences Research Institute Indiana University School of Medicine Indianapolis Indiana USA
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Yamaguchi T, Ozawa H, Yamaguchi S, Hamaguchi S, Ueda S. Calbindin-Positive Neurons Co-express Functional Markers in a Location-Dependent Manner Within the A11 Region of the Rat Brain. Neurochem Res 2021; 46:853-865. [PMID: 33439431 DOI: 10.1007/s11064-020-03217-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 12/16/2020] [Accepted: 12/24/2020] [Indexed: 11/24/2022]
Abstract
The A11 region plays a role in numerous physiological functions, including pain and locomotor activity, and consists of a variety of neurons including GABAergic, calbindin positive (Calb+), and dopaminergic (DA) neurons. However, the neurochemical nature of Calb+ neurons and their regulatory role in the A11 region remain largely unknown. In this study, we examined the kind of functional markers co-expressed in the Calb+ neurons using sections from 8-week-old rats. To examine a marker related to classical neurotransmitters, we performed in situ hybridization for vesicular glutamate transporter 2 (vGluT2) or glutamate decarboxylase (GAD) 65 and 67, in conjunction with Calb immunohistochemistry. We found cellular co-expression of Calb with vGluT2 or GAD65/67 throughout the A11 region. Nearly all Calb+/GAD65/67+ neurons were found in the rostral-middle aspect of the A11 region. In contrast, Calb+/vGluT2+ neurons were found predominantly in the middle-caudal aspect of the A11 region. For receptors and neuropeptides, we performed immunohistochemistry for androgen receptor (AR), estrogen receptors (ERα and ERβ), and calcitonin gene-related peptide (CGRP). We found that Calb+ neurons co-expressed AR in the rostral aspect of the A11 region in both male and female rats. However, we rarely find cellular co-expression of Calb with ERα or ERβ in this region. For CGRP, we found both Calb+ neurons with or without CGRP expression. These results demonstrate that Calb+ neurons co-express many functional markers. Calb+ neurons have a distinct distribution pattern and may play a variety of regulatory roles, depending on their location within the A11 region.
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Affiliation(s)
- Tsuyoshi Yamaguchi
- Department of Histology and Neurobiology, Dokkyo Medical University, School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan.
| | - Hidechika Ozawa
- Department of Histology and Neurobiology, Dokkyo Medical University, School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan
- Department of Anesthesia and Pain Medicine, Dokkyo Medical University, School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan
| | - Shigeki Yamaguchi
- Department of Anesthesia and Pain Medicine, Dokkyo Medical University, School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan
| | - Shinsuke Hamaguchi
- Department of Anesthesia and Pain Medicine, Dokkyo Medical University, School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan
| | - Shuichi Ueda
- Department of Histology and Neurobiology, Dokkyo Medical University, School of Medicine, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan
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Villalba RM, Pare JF, Lee S, Lee S, Smith Y. Thalamic degeneration in MPTP-treated Parkinsonian monkeys: impact upon glutamatergic innervation of striatal cholinergic interneurons. Brain Struct Funct 2019; 224:3321-3338. [PMID: 31679085 PMCID: PMC6878768 DOI: 10.1007/s00429-019-01967-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/04/2019] [Indexed: 12/13/2022]
Abstract
In both Parkinson's disease (PD) patients and MPTP-treated non-human primates, there is a profound neuronal degeneration of the intralaminar centromedian/parafascicular (CM/Pf) thalamic complex. Although this thalamic pathology has long been established in PD (and other neurodegenerative disorders), the impact of CM/Pf cell loss on the integrity of the thalamo-striatal glutamatergic system and its regulatory functions upon striatal neurons remain unknown. In the striatum, cholinergic interneurons (ChIs) are important constituents of the striatal microcircuitry and represent one of the main targets of CM/Pf-striatal projections. Using light and electron microscopy approaches, we have analyzed the potential impact of CM/Pf neuronal loss on the anatomy of the synaptic connections between thalamic terminals (vGluT2-positive) and ChIs neurons in the striatum of parkinsonian monkeys treated chronically with MPTP. The following conclusions can be drawn from our observations: (1) as reported in PD patients, and in our previous monkey study, CM/Pf neurons undergo profound degeneration in monkeys chronically treated with low doses of MPTP. (2) In the caudate (head and body) nucleus of parkinsonian monkeys, there is an increased density of ChIs. (3) Despite the robust loss of CM/Pf neurons, no significant change was found in the density of thalamostriatal (vGluT2-positive) terminals, and in the prevalence of vGluT2-positive terminals in contact with ChIs in parkinsonian monkeys. These findings provide new information about the state of thalamic innervation of the striatum in parkinsonian monkeys with CM/Pf degeneration, and bring up an additional level of intricacy to the consequences of thalamic pathology upon the functional microcircuitry of the thalamostriatal system in parkinsonism. Future studies are needed to assess the importance of CM/Pf neuronal loss, and its potential consequences on the neuroplastic changes induced in the synaptic organization of the thalamostriatal system, in the development of early cognitive impairments in PD.
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Affiliation(s)
- Rosa M Villalba
- Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA, 303, USA.
- UDALL Center for Excellence for Parkinson's Disease, Emory University, Atlanta, GA, USA.
| | - Jean-Francois Pare
- Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA, 303, USA
- UDALL Center for Excellence for Parkinson's Disease, Emory University, Atlanta, GA, USA
| | - Solah Lee
- Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA, 303, USA
- UDALL Center for Excellence for Parkinson's Disease, Emory University, Atlanta, GA, USA
| | - Sol Lee
- Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA, 303, USA
- UDALL Center for Excellence for Parkinson's Disease, Emory University, Atlanta, GA, USA
| | - Yoland Smith
- Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA, 303, USA
- Department of Neurology, School of Medicine, Emory University, Atlanta, GA, USA
- UDALL Center for Excellence for Parkinson's Disease, Emory University, Atlanta, GA, USA
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Swaminathan M, Hill-Yardin EL, Bornstein JC, Foong JPP. Endogenous Glutamate Excites Myenteric Calbindin Neurons by Activating Group I Metabotropic Glutamate Receptors in the Mouse Colon. Front Neurosci 2019; 13:426. [PMID: 31118881 PMCID: PMC6504831 DOI: 10.3389/fnins.2019.00426] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 04/15/2019] [Indexed: 12/20/2022] Open
Abstract
Glutamate is a classic excitatory neurotransmitter in the central nervous system (CNS), but despite several studies reporting the expression of glutamate together with its various receptors and transporters within the enteric nervous system (ENS), its role in the gut remains elusive. In this study, we characterized the expression of the vesicular glutamate transporter, vGluT2, and examined the function of glutamate in the myenteric plexus of the distal colon by employing calcium (Ca2+)-imaging on Wnt1-Cre; R26R-GCaMP3 mice which express a genetically encoded fluorescent Ca2+ indicator in all enteric neurons and glia. Most vGluT2 labeled varicosities contained the synaptic vesicle release protein, synaptophysin, but not vesicular acetylcholine transporter, vAChT, which labels vesicles containing acetylcholine, the primary excitatory neurotransmitter in the ENS. The somata of all calbindin (calb) immunoreactive neurons examined received close contacts from vGluT2 varicosities, which were more numerous than those contacting nitrergic neurons. Exogenous application of L-glutamic acid (L-Glu) and N-methyl-D-aspartate (NMDA) transiently increased the intracellular Ca2+ concentration [Ca2+]i in about 25% of myenteric neurons. Most L-Glu responsive neurons were calb immunoreactive. Blockade of NMDA receptors with APV significantly reduced the number of neurons responsive to L-Glu and NMDA, thus showing functional expression of NMDA receptors on enteric neurons. However, APV resistant responses to L-Glu and NMDA suggest that other glutamate receptors were present. APV did not affect [Ca2+]i transients evoked by electrical stimulation of interganglionic nerve fiber tracts, which suggests that NMDA receptors are not involved in synaptic transmission. The group I metabotropic glutamate receptor (mGluR) antagonist, PHCCC, significantly reduced the amplitude of [Ca2+]i transients evoked by a 20 pulse (20 Hz) train of electrical stimuli in L-Glu responsive neurons. This stimulus is known to induce slow synaptic depolarizations. Further, some neurons that had PHCCC sensitive [Ca2+]i transients were calb immunoreactive and received vGluT2 varicosities. Overall, we conclude that electrically evoked release of endogenous glutamate mediates slow synaptic transmission via activation of group I mGluRs expressed by myenteric neurons, particularly those immunoreactive for calb.
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Affiliation(s)
- Mathusi Swaminathan
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Elisa L Hill-Yardin
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia.,School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC, Australia
| | - Joel C Bornstein
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Jaime P P Foong
- Department of Physiology, The University of Melbourne, Parkville, VIC, Australia
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Qiu J, Rivera HM, Bosch MA, Padilla SL, Stincic TL, Palmiter RD, Kelly MJ, Rønnekleiv OK. Estrogenic-dependent glutamatergic neurotransmission from kisspeptin neurons governs feeding circuits in females. eLife 2018; 7:e35656. [PMID: 30079889 PMCID: PMC6103748 DOI: 10.7554/elife.35656] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 07/24/2018] [Indexed: 11/13/2022] Open
Abstract
The neuropeptides tachykinin2 (Tac2) and kisspeptin (Kiss1) in hypothalamic arcuate nucleus Kiss1 (Kiss1ARH) neurons are essential for pulsatile release of GnRH and reproduction. Since 17β-estradiol (E2) decreases Kiss1 and Tac2 mRNA expression in Kiss1ARH neurons, the role of Kiss1ARH neurons during E2-driven anorexigenic states and their coordination of POMC and NPY/AgRP feeding circuits have been largely ignored. Presently, we show that E2 augmented the excitability of Kiss1ARH neurons by amplifying Cacna1g, Hcn1 and Hcn2 mRNA expression and T-type calcium and h-currents. E2 increased Slc17a6 mRNA expression and glutamatergic synaptic input to arcuate neurons, which excited POMC and inhibited NPY/AgRP neurons via metabotropic receptors. Deleting Slc17a6 in Kiss1 neurons eliminated glutamate release and led to conditioned place preference for sucrose in E2-treated KO female mice. Therefore, the E2-driven increase in Kiss1 neuronal excitability and glutamate neurotransmission may play a key role in governing the motivational drive for palatable food in females.
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Affiliation(s)
- Jian Qiu
- Department of Physiology and PharmacologyOregon Health and Science UniversityPortlandUnited States
| | - Heidi M Rivera
- Department of Physiology and PharmacologyOregon Health and Science UniversityPortlandUnited States
| | - Martha A Bosch
- Department of Physiology and PharmacologyOregon Health and Science UniversityPortlandUnited States
| | - Stephanie L Padilla
- Department of BiochemistryHoward Hughes Medical Institute, University of WashingtonSeattleUnited States
| | - Todd L Stincic
- Department of Physiology and PharmacologyOregon Health and Science UniversityPortlandUnited States
| | - Richard D Palmiter
- Department of BiochemistryHoward Hughes Medical Institute, University of WashingtonSeattleUnited States
| | - Martin J Kelly
- Department of Physiology and PharmacologyOregon Health and Science UniversityPortlandUnited States
- Division of NeuroscienceOregon National Primate Research Center, Oregon Health and Science UniversityBeavertonUnited States
| | - Oline K Rønnekleiv
- Department of Physiology and PharmacologyOregon Health and Science UniversityPortlandUnited States
- Division of NeuroscienceOregon National Primate Research Center, Oregon Health and Science UniversityBeavertonUnited States
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Antal M, Beneduce BM, Regehr WG. The substantia nigra conveys target-dependent excitatory and inhibitory outputs from the basal ganglia to the thalamus. J Neurosci 2014; 34:8032-42. [PMID: 24899724 DOI: 10.1523/JNEUROSCI.0236-14.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The basal ganglia (BG), which influence cortical activity via the thalamus, play a major role in motor activity, learning and memory, sensory processing, and many aspects of behavior. The substantia nigra (SN) consists of GABAergic neurons of the pars reticulata that inhibit thalamic neurons and provide the primary output of the BG, and dopaminergic neurons of the pars compacta that modulate thalamic excitability. Little is known about the functional properties of the SN→thalamus synapses, and anatomical characterization has been controversial. Here we use a combination of anatomical, electrophysiological, genetic, and optogenetic approaches to re-examine these synaptic connections in mice. We find that neurons in the SN inhibit neurons in the ventroposterolateral nucleus of the thalamus via GABAergic synapses, excite neurons in the thalamic nucleus reticularis, and both excite and inhibit neurons within the posterior nucleus group. Glutamatergic SN neurons express the vesicular glutamate receptor transporter vGluT2 and receive inhibitory synapses from striatal neurons, and many also express tyrosine hydroxylase, a marker of dopaminergic neurons. Thus, in addition to providing inhibitory outputs, which is consistent with the canonical circuit, the SN provides glutamatergic outputs that differentially target thalamic nuclei. This suggests that an increase in the activity of glutamatergic neurons in the SN allows the BG to directly excite neurons in specific thalamic nuclei. Elucidating an excitatory connection between the BG and the thalamus provides new insights into how the BG regulate thalamic activity, and has important implications for understanding BG function in health and disease.
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Villalba RM, Smith Y. Differential striatal spine pathology in Parkinson's disease and cocaine addiction: a key role of dopamine? Neuroscience 2013; 251:2-20. [PMID: 23867772 DOI: 10.1016/j.neuroscience.2013.07.011] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 07/03/2013] [Indexed: 01/19/2023]
Abstract
In the striatum, the dendritic tree of the two main populations of projection neurons, called "medium spiny neurons (MSNs)", are covered with spines that receive glutamatergic inputs from the cerebral cortex and thalamus. In Parkinson's disease (PD), striatal MSNs undergo an important loss of dendritic spines, whereas aberrant overgrowth of striatal spines occurs following chronic cocaine exposure. This review examines the possibility that opposite dopamine dysregulation is one of the key factors that underlies these structural changes. In PD, nigrostriatal dopamine degeneration results in a significant loss of dendritic spines in the dorsal striatum, while rodents chronically exposed to cocaine and other psychostimulants, display an increase in the density of "thin and immature" spines in the nucleus accumbens (NAc). In rodent models of PD, there is evidence that D2 dopamine receptor-containing MSNs are preferentially affected, while D1-positive cells are the main targets of increased spine density in models of addiction. However, such specificity remains to be established in primates. Although the link between the extent of striatal spine changes and the behavioral deficits associated with these disorders remains controversial, there is unequivocal evidence that glutamatergic synaptic transmission is significantly altered in both diseased conditions. Recent studies have suggested that opposite calcium-mediated regulation of the transcription factor myocyte enhancer factor 2 (MEF2) function induces these structural defects. In conclusion, there is strong evidence that dopamine is a major, but not the sole, regulator of striatal spine pathology in PD and addiction to psychostimulants. Further studies of the role of glutamate and other genes associated with spine plasticity in mediating these effects are warranted.
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Affiliation(s)
- R M Villalba
- Yerkes National Primate Research Center, Emory University, 954, Gatewood Road NE, Atlanta, GA 30329, USA; UDALL Center of Excellence for Parkinson's Disease, Emory University, 954, Gatewood Road NE, Atlanta, GA 30329, USA.
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