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Liu C, Liu WH, Yang W, Chen L, Xue Y, Chen XY. GLP-1 modulated the firing activity of nigral dopaminergic neurons in both normal and parkinsonian mice. Neuropharmacology 2024; 252:109946. [PMID: 38599494 DOI: 10.1016/j.neuropharm.2024.109946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 03/27/2024] [Accepted: 04/07/2024] [Indexed: 04/12/2024]
Abstract
The spontaneous firing activity of nigral dopaminergic neurons is associated with some important roles including modulation of dopamine release, expression of tyrosine hydroxylase (TH), as well as neuronal survival. The decreased neuroactivity of nigral dopaminergic neurons has been revealed in Parkinson's disease. Central glucagon-like peptide-1 (GLP-1) functions as a neurotransmitter or neuromodulator to exert multiple brain functions. Although morphological studies revealed the expression of GLP-1 receptors (GLP-1Rs) in the substantia nigra pars compacta, the possible modulation of GLP-1 on spontaneous firing activity of nigral dopaminergic neurons is unknown. The present extracellular in vivo single unit recordings revealed that GLP-1R agonist exendin-4 significantly increased the spontaneous firing rate and decreased the firing regularity of partial nigral dopaminergic neurons of adult male C57BL/6 mice. Blockade of GLP-1Rs by exendin (9-39) decreased the firing rate of nigral dopaminergic neurons suggesting the involvement of endogenous GLP-1 in the modulation of firing activity. Furthermore, the PKA and the transient receptor potential canonical (TRPC) 4/5 channels are involved in activation of GLP-1Rs-induced excitatory effects of nigral dopaminergic neurons. Under parkinsonian state, both the exogenous and endogenous GLP-1 could still induce excitatory effects on the surviving nigral dopaminergic neurons. As the mild excitatory stimuli exert neuroprotective effects on nigral dopaminergic neurons, the present GLP-1-induced excitatory effects may partially contribute to its antiparkinsonian effects.
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Affiliation(s)
- Cui Liu
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China; Department of Histology and Embryology, School of Clinical and Basic Medical Sciences, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Wen-Hong Liu
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Wu Yang
- Department of International Medicine, Affiliated Hospital of Qingdao University, Qingdao, China
| | - Lei Chen
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Yan Xue
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Xin-Yi Chen
- Department of International Medicine, Affiliated Hospital of Qingdao University, Qingdao, China.
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Stutz B, Nasrallah C, Nigro M, Curry D, Liu ZW, Gao XB, Elsworth JD, Mintz L, Horvath TL. Dopamine neuronal protection in the mouse Substantia nigra by GHSR is independent of electric activity. Mol Metab 2019; 24:120-138. [PMID: 30833218 PMCID: PMC6531791 DOI: 10.1016/j.molmet.2019.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 02/15/2019] [Accepted: 02/16/2019] [Indexed: 12/25/2022] Open
Abstract
Objective Dopamine neurons in the Substantia nigra (SN) play crucial roles in control of voluntary movement. Extensive degeneration of this neuronal population is the cause of Parkinson's disease (PD). Many factors have been linked to SN DA neuronal survival, including neuronal pacemaker activity (responsible for maintaining basal firing and DA tone) and mitochondrial function. Dln-101, a naturally occurring splice variant of the human ghrelin gene, targets the ghrelin receptor (GHSR) present in the SN DA cells. Ghrelin activation of GHSR has been shown to protect SN DA neurons against 1-methyl-4-phenyl-1,2,5,6 tetrahydropyridine (MPTP) treatment. We decided to compare the actions of Dln-101 with ghrelin and identify the mechanisms associated with neuronal survival. Methods Histologial, biochemical, and behavioral parameters were used to evaluate neuroprotection. Inflammation and redox balance of SN DA cells were evaluated using histologial and real-time PCR analysis. Designer Receptors Exclusively Activated by Designer Drugs (DREADD) technology was used to modulate SN DA neuron electrical activity and associated survival. Mitochondrial dynamics in SN DA cells was evaluated using electron microscopy data. Results Here, we report that the human isoform displays an equivalent neuroprotective factor. However, while exogenous administration of mouse ghrelin electrically activates SN DA neurons increasing dopamine output, as well as locomotion, the human isoform significantly suppressed dopamine output, with an associated decrease in animal motor behavior. Investigating the mechanisms by which GHSR mediates neuroprotection, we found that dopamine cell-selective control of electrical activity is neither sufficient nor necessary to promote SN DA neuron survival, including that associated with GHSR activation. We found that Dln101 pre-treatment diminished MPTP-induced mitochondrial aberrations in SN DA neurons and that the effect of Dln101 to protect dopamine cells was dependent on mitofusin 2, a protein involved in the process of mitochondrial fusion and tethering of the mitochondria to the endoplasmic reticulum. Conclusions Taken together, these observations unmasked a complex role of GHSR in dopamine neuronal protection independent on electric activity of these cells and revealed a crucial role for mitochondrial dynamics in some aspects of this process. Dln101 is a human splice-variant of the ghrelin gene with different expression pattern. Ghrelin and Dln101 display equivalent levels of neuroprotection of SN DA cells. Modulation of electrical activity of SN DA cells is not relevant for neuroprotection. Mitochondrial fusion protein 2 (MFN 2) blocks DLN101-induced mitochondrial fusion in SN DA neurons and prevents DLN101-induced neuroprotection.
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Affiliation(s)
- Bernardo Stutz
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, USA.
| | - Carole Nasrallah
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, USA; Interdepartmental Neuroscience Program, USA
| | - Mariana Nigro
- Department of Obstetrics, Gynecology and Reproductive Sciences, USA
| | | | - Zhong-Wu Liu
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, USA
| | - Xiao-Bing Gao
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, USA
| | | | | | - Tamas L Horvath
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, USA; Interdepartmental Neuroscience Program, USA; Department of Obstetrics, Gynecology and Reproductive Sciences, USA; Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Anatomy and Histology, University of Veterinary Medicine, Budapest, 1078, Hungary.
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Yee AG, Lee SM, Hunter MR, Glass M, Freestone PS, Lipski J. Effects of the Parkinsonian toxin MPP+ on electrophysiological properties of nigral dopaminergic neurons. Neurotoxicology 2014; 45:1-11. [DOI: 10.1016/j.neuro.2014.08.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/22/2014] [Accepted: 08/25/2014] [Indexed: 10/24/2022]
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Daschil N, Humpel C. Nifedipine and nimodipine protect dopaminergic substantia nigra neurons against axotomy-induced cell death in rat vibrosections via modulating inflammatory responses. Brain Res 2014; 1581:1-11. [PMID: 25038562 DOI: 10.1016/j.brainres.2014.07.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 06/13/2014] [Accepted: 07/08/2014] [Indexed: 12/31/2022]
Abstract
Neurodegeneration of cholinergic and dopaminergic neurons is a major hallmark in Alzheimer's or Parkinson's disease, respectively. A dysregulation in calcium homeostasis may be part of this process and counteracting calcium influx may have neuroprotective properties in both diseases. Therefore, we investigated the putative neuroprotective or neurotoxic activity of L-type calcium channel (LTCC) inhibitors on cholinergic and dopaminergic neurons in a rat organotypic vibrosection model. Sagittal or coronal vibrosections (200 μm thick) of postnatal day 10 rats were cultured on 0.4 μm semipermeable membranes for 2 weeks with 10 ng/ml nerve growth factor (NGF) and/or glial-cell line derived neurotrophic factor (GDNF) to maintain survival of cholinergic or dopaminergic neurons, respectively. Thereafter, sections were incubated with 0.1, 1 or 10 μM isradipine, nicardipine or verapamil for 2 weeks to explore cytotoxicity. Alternatively, in order to explore neuroprotective activity, vibrosections were incubated without growth factors but with isradipine or verapamil or with nicardipine, nimodipine or nifedipine from the beginning for 4 weeks. Our data show that all LTCC inhibitors exhibited no neurotoxic effect on cholinergic and dopaminergic neurons. Further, LTCC inhibitors did not have any neuroprotective activity on cholinergic neurons. However, nimodipine and nifedipine significantly enhanced the survival of dopaminergic substantia nigra (SN) but not ventral tegmental area (VTA) neurons, while nicardipine, isradipine and verapamil had no effect. Nifedipine (and more potently GDNF) reduced inflammatory cytokines (macrophage inflammatory protein-2, tumor necrosis factor-α), but did not influence oxidative stress or caspase-3 activity and did not interfere with iron-mediated overload. Our data show that nifedipine and nimodipine are very potent to enhance the survival of axotomized SN neurons, possibly influencing inflammatory processes.
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Affiliation(s)
- Nina Daschil
- Laboratory of Psychiatry and Experimental Alzheimer׳s Research, Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Austria
| | - Christian Humpel
- Laboratory of Psychiatry and Experimental Alzheimer׳s Research, Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Austria.
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Michel PP, Toulorge D, Guerreiro S, Hirsch EC. Specific needs of dopamine neurons for stimulation in order to survive: implication for Parkinson disease. FASEB J 2013; 27:3414-23. [PMID: 23699175 DOI: 10.1096/fj.12-220418] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Parkinson disease (PD) is a degenerative brain disorder characterized by motor symptoms that are unequivocally associated with the loss of dopaminergic (DA) neurons in the substantia nigra (SN). Although our knowledge of the mechanisms that contribute to DA cell death in both hereditary and sporadic forms of the disease has advanced significantly, the nature of the pathogenic process remains poorly understood. In this review, we present evidence that neurodegeneration occurs when the electrical activity and excitability of these neurons is reduced. In particular, we will focus on the specific need these neurons may have for stimulation in order to survive and on the molecular and cellular mechanisms that may be compromised when this need is no longer met in PD.
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Affiliation(s)
- Patrick P Michel
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Unité Mixte de Recherche (UMR) S975, Paris, France.
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Kurauchi Y, Hisatsune A, Isohama Y, Sawa T, Akaike T, Katsuki H. Nitric oxide/soluble guanylyl cyclase signaling mediates depolarization-induced protection of rat mesencephalic dopaminergic neurons from MPP⁺ cytotoxicity. Neuroscience 2012; 231:206-15. [PMID: 23238575 DOI: 10.1016/j.neuroscience.2012.11.044] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 11/09/2012] [Accepted: 11/24/2012] [Indexed: 12/30/2022]
Abstract
Neuronal electrical activity has been known to affect the viability of neurons in the central nervous system. Here we show that long-lasting membrane depolarization induced by elevated extracellular K(+) recruits nitric oxide (NO)/soluble guanylyl cyclase/protein kinase G signaling pathway, induces 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP)-mediated protein S-guanylation, and confers dopaminergic neuroprotection. Treatment of primary mesencephalic cell cultures with 1-methyl-4-phenylpyridinium (MPP(+)) for 72 h decreased the number of dopaminergic neurons, whereas the cell loss was markedly inhibited by elevated extracellular concentration of K(+) (+40 mM). The neuroprotective effect of elevated extracellular K(+) was significantly attenuated by tetrodotoxin (a Na(+) channel blocker), amlodipine (a voltage-dependent Ca(2+) channel blocker), N(ω)-nitro-l-arginine methyl ester (l-NAME) (a nitric oxide synthase inhibitor), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (a soluble guanylyl cyclase inhibitor), and KT5823 or Rp-8-bromo-β-phenyl-1,N(2)-ethenoguanosine 3',5'-cyclic monophosphorothioate (Rp-8-Br-PET-cGMPS) (protein kinase G inhibitors). Elevated extracellular K(+) increased 8-nitro-cGMP production resulting in the induction of protein S-guanylation in cells in mesencephalic cultures including dopaminergic neurons. In addition, exogenous application of 8-nitro-cGMP protected dopaminergic neurons from MPP(+) cytotoxicity, which was prevented by zinc protoporphyrin IX, an inhibitor of heme oxygenase-1 (HO-1). Zinc protoporphyrin IX also inhibited the neuroprotective effect of elevated extracellular K(+). On the other hand, KT5823 or Rp-8-Br-PET-cGMPS did not inhibit the induction of HO-1 protein expression by 8-nitro-cGMP, although these protein kinase G inhibitors abrogated the neuroprotective effect of 8-nitro-cGMP. These results suggest that protein S-guanylation (leading to HO-1 induction) as well as canonical protein kinase G signaling pathway plays an important role in NO-mediated, activity-dependent dopaminergic neuroprotection.
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Affiliation(s)
- Y Kurauchi
- Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
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Toulorge D, Guerreiro S, Hild A, Maskos U, Hirsch EC, Michel PP. Neuroprotection of midbrain dopamine neurons by nicotine is gated by cytoplasmic Ca
2+. FASEB J 2011; 25:2563-73. [DOI: 10.1096/fj.11-182824] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Damien Toulorge
- Université Pierre et Marie Curie‐Paris 6Centre de Recherche de l'Institut du Cerveau et de la Moelle EpinièreUnité Mixte de Recherche‐S975ParisFrance
- Institut National de la Santé et de la Recherche Médicale U975ParisFrance
- Centre National de la Recherche ScientifiqueUnité Mixte de Recherche 7225ParisFrance
| | - Serge Guerreiro
- Université Pierre et Marie Curie‐Paris 6Centre de Recherche de l'Institut du Cerveau et de la Moelle EpinièreUnité Mixte de Recherche‐S975ParisFrance
- Institut National de la Santé et de la Recherche Médicale U975ParisFrance
- Centre National de la Recherche ScientifiqueUnité Mixte de Recherche 7225ParisFrance
| | - Audrey Hild
- Université Pierre et Marie Curie‐Paris 6Centre de Recherche de l'Institut du Cerveau et de la Moelle EpinièreUnité Mixte de Recherche‐S975ParisFrance
- Institut National de la Santé et de la Recherche Médicale U975ParisFrance
- Centre National de la Recherche ScientifiqueUnité Mixte de Recherche 7225ParisFrance
| | - Uwe Maskos
- Neurobiologie Integrative des Systèmes CholinergiquesInstitut PasteurParisFrance
| | - Etienne C. Hirsch
- Université Pierre et Marie Curie‐Paris 6Centre de Recherche de l'Institut du Cerveau et de la Moelle EpinièreUnité Mixte de Recherche‐S975ParisFrance
- Institut National de la Santé et de la Recherche Médicale U975ParisFrance
- Centre National de la Recherche ScientifiqueUnité Mixte de Recherche 7225ParisFrance
| | - Patrick P. Michel
- Université Pierre et Marie Curie‐Paris 6Centre de Recherche de l'Institut du Cerveau et de la Moelle EpinièreUnité Mixte de Recherche‐S975ParisFrance
- Institut National de la Santé et de la Recherche Médicale U975ParisFrance
- Centre National de la Recherche ScientifiqueUnité Mixte de Recherche 7225ParisFrance
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Michinaga S, Hisatsune A, Isohama Y, Katsuki H. Inhibition of neural activity depletes orexin from rat hypothalamic slice culture. J Neurosci Res 2010; 88:214-21. [PMID: 19610104 DOI: 10.1002/jnr.22183] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Orexins (hypocretins) are neuropeptides produced by a small population of hypothalamic neurons whose dysregulation may lead to narcolepsy, a neurological disorder characterized by disorganization of sleep and wakefulness. Excessive stimulation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors causes preferential loss of orexin neurons in the hypothalamus, whereas an adequate level of neuronal excitatory activities is generally known to be important for the maintenance of central neurons. By examining the effect of manipulation of neural activity, we found that 24-72 hr application of tetrodotoxin (TTX) caused a substantial decrease in the number of orexin-immunoreactive neurons, but not of melanin-concentrating hormone-immunoreactive neurons, in hypothalamic slice culture. Similar results were obtained when neural activity was arrested by added extracellular Mg(2+). Reduction of orexin expression by TTX and Mg(2+) was also observed at mRNA level. The decrease of orexin-immunoreactive neurons was attributable to depletion of orexin, because it was reversible after washout of TTX or elevated extracellular Mg(2+) and was not associated with induction of cell death. Blockers of voltage-dependent Ca(2+) channels as well as of NMDA receptors also induced a significant and selective decrease of orexin-immunoreactive neurons. Moreover, TTX-induced decrease of orexin immunoreactivity was largely abrogated by concurrent application of a moderate concentration of NMDA. These results suggest that Ca(2+) entry associated with nontoxic levels of spontaneous activity of glutamatergic inputs plays an important role in the maintenance of orexin neurons in a tissue culture model.
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Affiliation(s)
- Shotaro Michinaga
- Department of Chemico-Pharmacological Sciences, Kumamoto University, Kumamoto, Japan
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Nakatsu Y, Kotake Y, Takishita T, Ohta S. Long-term exposure to endogenous levels of tributyltin decreases GluR2 expression and increases neuronal vulnerability to glutamate. Toxicol Appl Pharmacol 2009; 240:292-8. [DOI: 10.1016/j.taap.2009.06.024] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Revised: 06/25/2009] [Accepted: 06/26/2009] [Indexed: 11/29/2022]
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Delivery of peptide and protein drugs over the blood-brain barrier. Prog Neurobiol 2009; 87:212-51. [PMID: 19395337 DOI: 10.1016/j.pneurobio.2008.12.002] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 11/11/2008] [Accepted: 12/17/2008] [Indexed: 12/12/2022]
Abstract
Peptide and protein (P/P) drugs have been identified as showing great promises for the treatment of various neurodegenerative diseases. A major challenge in this regard, however, is the delivery of P/P drugs over the blood-brain barrier (BBB). Intense research over the last 25 years has enabled a better understanding of the cellular and molecular transport mechanisms at the BBB, and several strategies for enhanced P/P drug delivery over the BBB have been developed and tested in preclinical and clinical-experimental research. Among them, technology-based approaches (comprising functionalized nanocarriers and liposomes) and pharmacological strategies (such as the use of carrier systems and chimeric peptide technology) appear to be the most promising ones. This review combines a comprehensive overview on the current understanding of the transport mechanisms at the BBB with promising selected strategies published so far that can be applied to facilitate enhanced P/P drug delivery over the BBB.
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Larsen TR, Rossen S, Gramsbergen JB. Dopamine release in organotypic cultures of foetal mouse mesencephalon: effects of depolarizing agents, pargyline, nomifensine, tetrodotoxin and calcium. Eur J Neurosci 2008; 28:569-76. [DOI: 10.1111/j.1460-9568.2008.06354.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Michel PP, Alvarez-Fischer D, Guerreiro S, Hild A, Hartmann A, Hirsch EC. Role of activity-dependent mechanisms in the control of dopaminergic neuron survival. J Neurochem 2007; 101:289-97. [PMID: 17402966 DOI: 10.1111/j.1471-4159.2006.04424.x] [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: 01/15/2023]
Abstract
Dopaminergic neurons that constitute the nigrostriatal pathway are characterized by singular electrical properties that allow them to discharge in vivo spontaneously in a spectrum of patterns ranging from pacemaker to random and bursting modes. These electrophysiological features allow dopaminergic neurons to optimize the release of dopamine in their terminal fields. However, there is emerging evidence indicating that electrical activity might also participate in the control of dopaminergic neuron survival, not only during development, but also in the adult brain, thus raising the possibility that alterations in ionic currents could contribute actively to the demise of these neurons in Parkinson disease. This review focuses on the mechanisms by which activity-dependent mechanisms might modulate dopaminergic cell survival.
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Salthun-Lassalle B, Traver S, Hirsch EC, Michel PP. Substance P, neurokinins A and B, and synthetic tachykinin peptides protect mesencephalic dopaminergic neurons in culture via an activity-dependent mechanism. Mol Pharmacol 2005; 68:1214-24. [PMID: 16077032 DOI: 10.1124/mol.105.015453] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We evaluated the neuroprotective potential of tachykinin peptides using a model system in which mesencephalic dopaminergic (DA) neurons die spontaneously and selectively as they mature. The three native tachykinins, substance P (SP), neurokinin (NK) A, and NKB afforded substantial protection against DA cell demise. The selective NK1 receptor antagonist [D-Pro9,[spiro-gamma-lactam] Leu10,Trp11]substance P (GR71251) was sufficient in itself to suppress the effect of SP, whereas a cotreatment with GR71251 and the NK3 receptor antagonist (R)-N-[alpha-(methoxycarbonyl)benzyl]-2-phenylquinoline-4-carboxamide (SB218795) was required to prevent the effects of both NKA and NKB. Consistent with these results, D-Ala-[L-Pro9,Me-Leu8]substance P(7-11) (GR73632), a selective agonist of NK1 receptors and [pro7]-NKB, a selective agonist of NK3 receptors, conferred protection to DA neurons, whereas (Lys3, Gly8-R-gamma-lactam-Leu9)neurokinin A(3-10) (GR64349), which activates specifically NK2 receptors, did not. DA neurons rescued by tachykinins accumulated [3H]DA efficiently, which suggests that they were also totally functional. Neuroprotection by tachykinins was highly selective for DA neurons, rapidly reversed upon treatment withdrawal, and reproduced by but independent of glial cell line-derived neurotrophic factor. Survival promotion by tachykinins was abolished by blocking voltage-gated Na+ channels with tetrodotoxin or N-type voltage-gated Ca2+ channels with omega-conotoxin-MVIIA, which indicates that an increase in neuronal excitability was crucially involved in this effect. Together, these data further support the notion that the survival of mesencephalic DA neurons during development depends largely on excitatory inputs, which may be provided in part by tachykinins.
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Katsuki H, Shibata H, Takenaka C, Kume T, Kaneko S, Akaike A. N-Methyl-D-aspartate receptors contribute to the maintenance of dopaminergic neurons in rat midbrain slice cultures. Neurosci Lett 2003; 341:123-6. [PMID: 12686381 DOI: 10.1016/s0304-3940(03)00176-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Excitatory neuronal activity produces beneficial influences on neuronal survival under several circumstances. We show that cultivation of rat midbrain slices in the presence of elevated extracellular Mg(2+) resulted in a marked decrease in the number of dopaminergic neurons. The effect was prominent when Mg(2+) was added to the medium during the first week of cultivation. Chronic treatment with antagonists of N-methyl-D-aspartate receptors such as 2-amino-5-phosphonovaleric acid, MK-801 and ifenprodil also resulted in a marked loss of dopaminergic neurons, whereas nicotinic receptor antagonists showed no effect. The effect of MK-801 was abolished by chronic depolarization by elevated extracellular K(+), or by application of forskolin or dibutyryl cyclic AMP. Thus, tonic activation of N-methyl-D-aspartate receptors driven by neuronal activity may play an important role in the maintenance of dopaminergic neurons.
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Affiliation(s)
- Hiroshi Katsuki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, 606-8501, Kyoto, Japan
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Chawla S, Vanhoutte P, Arnold FJL, Huang CLH, Bading H. Neuronal activity-dependent nucleocytoplasmic shuttling of HDAC4 and HDAC5. J Neurochem 2003; 85:151-9. [PMID: 12641737 DOI: 10.1046/j.1471-4159.2003.01648.x] [Citation(s) in RCA: 224] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The class II histone deacetylases, HDAC4 and HDAC5, directly bind to and repress myogenic transcription factors of the myocyte enhancer factor-2 (MEF-2) family thereby inhibiting skeletal myogenesis. During muscle differentiation, repression of gene transcription by MEF-2/HDAC complexes is relieved due to calcium/calmodulin-dependent (CaM) kinase-induced translocation of HDAC4 and HDAC5 to the cytoplasm. MEF-2 proteins and HDACs are also highly expressed in the nervous system and have been implicated in neuronal survival and differentiation. Here we investigated the possibility that the subcellular localization of HDACs, and thus their ability to repress target genes, is controlled by synaptic activity in neurones. We found that, in cultured hippocampal neurones, the localization of HDAC4 and HDAC5 is dynamic and signal-regulated. Spontaneous electrical activity was sufficient for nuclear export of HDAC4 but not of HDAC5. HDAC5 translocation to the cytoplasm was induced following stimulation of calcium flux through synaptic NMDA receptors or L-type calcium channels; glutamate bath application (stimulating synaptic and extrasynaptic NMDA receptors) antagonized nuclear export. Activity-induced nucleocytoplasmic shuttling of both HDACs was partially blocked by the CaM kinase inhibitor KN-62 with HDAC5 nuclear export being more sensitive to CaM kinase inhibition than that of HDAC4. Thus, the subcellular localization of HDACs in neurones is specified by neuronal activity; differences in the activation thresholds for HDAC4 and HDAC5 nuclear export provides a mechanism for input-specific gene expression.
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Affiliation(s)
- Sangeeta Chawla
- Department of Physiology, University of Cambridge, Cambridge, UK.
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Shirakawa H, Katsuki H, Kume T, Kaneko S, Ito J, Akaike A. Regulation of N-methyl-D-aspartate cytotoxicity by neuroactive steroids in rat cortical neurons. Eur J Pharmacol 2002; 454:165-75. [PMID: 12421643 DOI: 10.1016/s0014-2999(02)02493-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigated the effects of neuroactive steroids on N-methyl-D-aspartate (NMDA) cytotoxicity in cultured rat cortical neurons. 3alpha-hydroxy-5beta-pregnan-20-one sulfate (3alpha5betaS) attenuated, whereas pregnenolone sulfate and pregnenolone hemisuccinate exacerbated, NMDA neurotoxicity in cortical slice cultures. These actions of steroids were not affected by inhibition of protein synthesis, by blockade of GABA(A) receptors, or by blockade of sigma receptors. In addition, the actions of steroids were not affected by manipulation of cyclic AMP levels or protein kinase C activity. We found that 3alpha5betaS attenuated and pregnenolone hemisuccinate augmented NMDA-induced currents in cortical neurons, whereas pregnenolone sulfate exerted no significant effect. Fluorometric measurements revealed that 3alpha5betaS attenuated and pregnenolone hemisuccinate augmented glutamate-induced increase in intracellular Ca(2+). Pregnenolone sulfate slowed the decay of Ca(2+) increase induced by glutamate, without significant effect on the peak amplitude of Ca(2+) increase. These results indicate that neuroactive steroids affect NMDA cytotoxicity by modulation of Ca(2+) influx through NMDA receptor-associated channels.
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Affiliation(s)
- Hisashi Shirakawa
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
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Akaike A, Katsuki H, Kume T. [Role of nitric oxide in survival and death of neurons]. Nihon Yakurigaku Zasshi 2002; 119:15-20. [PMID: 11862752 DOI: 10.1254/fpj.119.15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The prominent pathological feature of the brain in Parkinson's disease is selective degeneration of dopaminergic neurons in the substantia nigra of the midbrain. Glutamate and nitric oxide (NO) are the major effectors of the radical stress that may induce selective loss of dopaminergic neurons. It has been postulated that neurotoxicity induced by glutamate and NO in dopaminergic neurons is regulated by certain endogenous factors. We have reported that estradiol protects dopaminergic neurons against NO-mediated glutamate neurotoxicity by reducing intracellular reactive oxygen species (ROS) levels. We further searched for a candidate for neuroprotective substances with unique structure. From the ether extract of fetal calf serum (FCS), we isolated a novel substance possessing protective activity against neurotoxicity induced by glutamate NO. The compound was a sulfur-containing diterpenoid and showed hydroxyl radical scavenging activity. We further analyzed the change of resistance to excitotoxicity in midbrain dopaminergic neurons in co-culture with the striatum by using a slice culture technique. The results suggested that the generation of NO is involved in NMDA cytotoxicity on dopaminergic neurons and that increased activity of SOD in co-culture renders dopaminergic neurons resistant to NMDA cytotoxicity by preventing peroxynitrite formation. Those findings suggest that regulation of intracellular ROS levels plays a critical role in protecting neurons against NO-mediated radical stress in neurodegenerative disorders.
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Affiliation(s)
- Akinori Akaike
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
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