101
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Imayoshi I, Hirano K, Kitano S, Miyachi H, Kageyama R. In vivo evaluation of ΦC31 recombinase activity in transgenic mice. Neurosci Res 2012; 73:106-14. [PMID: 22608021 DOI: 10.1016/j.neures.2012.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 02/17/2012] [Accepted: 02/20/2012] [Indexed: 11/16/2022]
Abstract
Genome engineering strategies employing site-specific recombinases (SSRs) such as Cre, Flp and PhiC31, have become powerful tools to analyze gene function and manipulate neural network in vertebrates. In the present study, we evaluated the ability of PhiC31 phage integrase to induce genomic recombination in transgenic mice. PhiC31 is the integrase encoded by the Streptomyces bacteriophage that promotes recombination between heterotypic attP and attB sites. We generated transgenic mice that express codon-optimized PhiC31 (PhiC31o) in neural stem/progenitor cells or tyrosine hydroxylase (TH) expressing catecholaminergic neurons. PhiC31 was functional in these cells and capable of excising a transcriptional stop cassette flanked by PhiC31-specific attP/B recognition sites. PhiC31-ER(T2), a fusion protein of PhiC31o (without the nuclear localization signal) and the mutated ligand-binding domain of the human estrogen receptor, was able to induce recombination in neural stem/progenitor cells in a tamoxifen-dependent manner, but the recombination rate was less efficient than for PhiC31. Thus, PhiC31 integrase is functional in transgenic mice and is suitable for mosaic recombination in restricted cell populations.
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Affiliation(s)
- Itaru Imayoshi
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan.
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102
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Srinivasan R, Richards CI, Xiao C, Rhee D, Pantoja R, Dougherty DA, Miwa JM, Lester HA. Pharmacological chaperoning of nicotinic acetylcholine receptors reduces the endoplasmic reticulum stress response. Mol Pharmacol 2012; 81:759-69. [PMID: 22379121 DOI: 10.1124/mol.112.077792] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We report the first observation that endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) can decrease when a central nervous system drug acts as an intracellular pharmacological chaperone for its classic receptor. Transient expression of α4β2 nicotinic receptors (nAChRs) in Neuro-2a cells induced the nuclear translocation of activating transcription factor 6 (ATF6), which is part of the UPR. Cells were exposed for 48 h to the full agonist nicotine, the partial agonist cytisine, or the competitive antagonist dihydro-β-erythroidine; we also tested mutant nAChRs that readily exit the ER. Each of these four manipulations increased Sec24D-enhanced green fluorescent protein fluorescence of condensed ER exit sites and attenuated translocation of ATF6-enhanced green fluorescent protein to the nucleus. However, we found no correlation among the manipulations regarding other tested parameters [i.e., changes in nAChR stoichiometry (α4(2)β2(3) versus α4(3)β2(2)), changes in ER and trans-Golgi structures, or the degree of nAChR up-regulation at the plasma membrane]. The four manipulations activated 0 to 0.4% of nAChRs, which shows that activation of the nAChR channel did not underlie the reduced ER stress. Nicotine also attenuated endogenously expressed ATF6 translocation and phosphorylation of eukaryotic initiation factor 2α in mouse cortical neurons transfected with α4β2 nAChRs. We conclude that, when nicotine accelerates ER export of α4β2 nAChRs, this suppresses ER stress and the UPR. Suppression of a sustained UPR may explain the apparent neuroprotective effect that causes the inverse correlation between a person's history of tobacco use and susceptibility to developing Parkinson's disease. This suggests a novel mechanism for neuroprotection by nicotine.
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Affiliation(s)
- Rahul Srinivasan
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
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103
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Protein kinase C activity alters the effect of μ-opioid receptors on inhibitory postsynaptic current in the striosomes. Neuroreport 2012; 23:184-8. [DOI: 10.1097/wnr.0b013e32834faab0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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104
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Autonomic Nervous System In Vitro: Studying Tonically Active Neurons Controlling Vagal Outflow in Rodent Brainstem Slices. ISOLATED CENTRAL NERVOUS SYSTEM CIRCUITS 2012. [DOI: 10.1007/978-1-62703-020-5_1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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105
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Masuda M, Miura M, Inoue R, Imanishi M, Saino-Saito S, Takada M, Kobayashi K, Aosaki T. Postnatal development of tyrosine hydroxylase mRNA-expressing neurons in mouse neostriatum. Eur J Neurosci 2011; 34:1355-67. [PMID: 22004548 DOI: 10.1111/j.1460-9568.2011.07873.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The striatum harbors a small number of tyrosine hydroxylase (TH) mRNA-containing GABAergic neurons that express TH immunoreactivity after dopamine depletion, some of which reportedly resembled striatal medium spiny projection neurons (MSNs). To clarify whether the TH mRNA-expressing neurons were a subset of MSNs, we characterized their postnatal development of electrophysiological and morphological properties using a transgenic mouse strain expressing enhanced green fluorescent protein (EGFP) under the control of the rat TH gene promoter. At postnatal day (P)1, EGFP-TH+ neurons were present as clusters in the striatum and, thereafter, gradually scattered ventromedially by P18 without regard to the striatal compartments. They were immunonegative for calbindin, but immunopositive for enkephalin (54.5%) and dynorphin (80.0%). Whole-cell patch-clamp recordings revealed at least two distinct neuronal types, termed EGFP-TH+ Type A and B. Whereas Type B neurons were aspiny and negative for the MSN marker dopamine- and cyclic AMP-regulated phosphoprotein of 32 kDa (DARPP-32), Type A neurons constituted 75% of the EGFP+ cells, had dendritic spines (24.6%), contained DARPP-32 (73.6%) and a proportion acquired TH immunoreactivity after injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and 3-nitropropionic acid. The membrane properties and N-methyl-d-aspartate : non-N-methyl-d-aspartate excitatory postsynaptic current ratio of Type A neurons were very similar to MSNs at P18. However, their resting membrane potentials and spike widths were statistically different from those of MSNs. In addition, the calbindin-like, DARPP-32-like and dynorphin B-like immunoreactivity of Type A neurons developed differently from that of MSNs in the matrix. Thus, Type A neurons closely resemble MSNs, but constitute a cell type distinct from classical MSNs.
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Affiliation(s)
- Masao Masuda
- Neuropathophysiology Research Group, Tokyo Metropolitan Institute of Gerontology, Itabashi, Tokyo, Japan
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106
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Sensory input regulates spatial and subtype-specific patterns of neuronal turnover in the adult olfactory bulb. J Neurosci 2011; 31:11587-96. [PMID: 21832189 DOI: 10.1523/jneurosci.0614-11.2011] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Throughout life, new neurons are added and old ones eliminated in the adult mouse olfactory bulb. Previous studies suggested that olfactory experience controls the process by which new neurons are integrated into mature circuits. Here we report novel olfactory-experience-dependent mechanisms of neuronal turnover. Using two-photon laser-scanning microscopy and sensory manipulations in adult live mice, we found that the neuronal turnover was dynamically controlled by olfactory input in a neuronal subtype-specific manner. Olfactory input enhanced this turnover, which was characterized by the reiterated use of the same positions in the glomeruli by new neurons. Our results suggest that olfactory-experience-dependent modification of neuronal turnover confers structural plasticity and stability on the olfactory bulb.
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107
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Gong R, Ding C, Hu J, Lu Y, Liu F, Mann E, Xu F, Cohen MB, Luo M. Role for the membrane receptor guanylyl cyclase-C in attention deficiency and hyperactive behavior. Science 2011; 333:1642-6. [PMID: 21835979 DOI: 10.1126/science.1207675] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Midbrain dopamine neurons regulate many important behavioral processes, and their dysfunctions are associated with several human neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD) and schizophrenia. Here, we report that these neurons in mice selectively express guanylyl cyclase-C (GC-C), a membrane receptor previously thought to be expressed mainly in the intestine. GC-C activation potentiates the excitatory responses mediated by glutamate and acetylcholine receptors via the activity of guanosine 3',5'-monophosphate-dependent protein kinase (PKG). Mice in which GC-C has been knocked out exhibit hyperactivity and attention deficits. Moreover, their behavioral phenotypes are reversed by ADHD therapeutics and a PKG activator. These results indicate important behavioral and physiological functions for the GC-C/PKG signaling pathway within the brain and suggest new therapeutic targets for neuropsychiatric disorders related to the malfunctions of midbrain dopamine neurons.
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Affiliation(s)
- Rong Gong
- Graduate Program in Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China
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108
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Lenartowski R, Goc A. Epigenetic, transcriptional and posttranscriptional regulation of the tyrosine hydroxylase gene. Int J Dev Neurosci 2011; 29:873-83. [PMID: 21803145 DOI: 10.1016/j.ijdevneu.2011.07.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2011] [Accepted: 07/14/2011] [Indexed: 01/12/2023] Open
Abstract
The activity of tyrosine hydroxylase (TH, EC 1.14.16.2) gene and protein determines the catecholamine level, which, in turn, is crucial for the organism homeostasis. The TH gene expression is regulated by near all possible regulatory mechanisms on epigenetic, transcriptional and posttranscriptional levels. Ongoing molecular characteristic of the TH gene reveals some of the cis and trans elements necessary for its proper expression but most of them especially these responsible for tissue specific expression remain still obscure. This review will focus on some aspects of TH regulation including spatial chromatin organization of the TH locus and TH gene, regulatory elements mediating basal, induced and cell-specific activity, transcriptional elongation, alternative TH RNA processing, and the regulation of TH RNA stability in the cell.
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Affiliation(s)
- Robert Lenartowski
- Nicolaus Copernicus University, Institute of General and Molecular Biology, Department of Genetics, Gagarina 9, 87-100 Toruń, Poland
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109
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Inputs underlying the ON-OFF light responses of type 2 wide-field amacrine cells in TH::GFP mice. J Neurosci 2011; 31:4780-91. [PMID: 21451016 DOI: 10.1523/jneurosci.6235-10.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In the mammalian retina, two types of catecholaminergic amacrine cells have been described. Although dopaminergic type 1 cells are well characterized, the physiology of type 2 cells is, so far, unknown. To target type 2 cells specifically, we used a transgenic mouse line that expresses green fluorescent protein under the control of the tyrosine hydroxylase promoter. Type 2 cells are GABAergic and have an extensive dendritic arbor, which stratifies in the middle of the inner plexiform layer. Our data suggest that type 2 cells comprise two subpopulations with identical physiological properties: one has its somata located in the inner nuclear layer and the other in the ganglion cell layer. Immunostaining with bipolar cell markers suggested that type 2 cells receive excitatory inputs from type 3 OFF and type 5 ON bipolar cells. Consistently, patch-clamp recordings showed that type 2 cells are ON-OFF amacrine cells. Blocking excitatory inputs revealed that different rod and cone pathways are active under scotopic and mesopic light conditions. Blockade of inhibitory inputs led to membrane potential oscillations in type 2 cells, suggesting that GABAergic and glycinergic amacrine cells strongly influence type 2 cell signaling. Among the glycinergic amacrine cells, we identified the VGluT3-immunoreactive amacrine cell as a likely candidate. Collectively, light responses of type 2 cells were remarkably uniform over a wide range of light intensities. These properties point toward a general function of type 2 cells that is maintained under scotopic and mesopic conditions.
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110
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Cucchiaroni ML, Freestone PS, Berretta N, Viscomi MT, Bisicchia E, Okano H, Molinari M, Bernardi G, Lipski J, Mercuri NB, Guatteo E. Properties of dopaminergic neurons in organotypic mesencephalic-striatal co-cultures - evidence for a facilitatory effect of dopamine on the glutamatergic input mediated by α-1 adrenergic receptors. Eur J Neurosci 2011; 33:1622-36. [DOI: 10.1111/j.1460-9568.2011.07659.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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111
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Thibault D, Albert PR, Pineyro G, Trudeau LÉ. Neurotensin triggers dopamine D2 receptor desensitization through a protein kinase C and beta-arrestin1-dependent mechanism. J Biol Chem 2011; 286:9174-84. [PMID: 21233215 PMCID: PMC3059057 DOI: 10.1074/jbc.m110.166454] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 01/12/2011] [Indexed: 11/06/2022] Open
Abstract
The peptide neurotensin (NT) is known to exert a potent excitatory effect on the dopaminergic system by inhibiting D2 dopamine (DA) receptor (D2R) function. This regulation is dependent on activation of PKC, a well known effector of the type 1 NT receptor (NTR1). Because PKC phosphorylation of the D2R has recently been shown to induce its internalization, we hypothesized that NT acts to reduce D2R function through heterologous desensitization of the D2R. In the present study, we first used HEK-293 cells to demonstrate that NT induces PKC-dependent D2R internalization. Furthermore, internalization displayed faster kinetics in cells expressing the D2R short isoform, known to act as an autoreceptor in DA neurons, than in cells expressing the long isoform, known to act as a postsynaptic D2R. In patch clamp experiments on cultured DA neurons, overexpression of a mutant D2S lacking three key PKC phosphorylation sites abrogated the ability of NT to reduce D2R-mediated cell firing inhibition. Short interfering RNA-mediated inhibition of β-arrestin1 and dynamin2, proteins important for receptor desensitization, reduced agonist-induced desensitization of D2R function, but only the inhibition of β-arrestin1 reduced the effect of NT on D2R function. Taken together, our data suggest that NT acutely regulates D2 autoreceptor function and DA neuron excitability through PKC-mediated phosphorylation of the D2R, leading to heterologous receptor desensitization.
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Affiliation(s)
- Dominic Thibault
- From the Department of Pharmacology
- Department of Physiology
- the Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Québec H3C 3J7, Canada
| | - Paul R. Albert
- the Ottawa Hospital Research Institute, University of Ottawa, Ottawa K1H 8M5, Canada
| | - Graciela Pineyro
- From the Department of Pharmacology
- Department of Psychiatry, Faculty of Medicine, and
- the Centre de Recherche du Centre Hospitalier Universitaire Sainte Justine, Université de Montréal, Quebec H3T 1C5, Canada, and
| | - Louis-Éric Trudeau
- From the Department of Pharmacology
- Department of Physiology
- Department of Psychiatry, Faculty of Medicine, and
- the Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, Québec H3C 3J7, Canada
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112
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Malmersjö S, Liste I, Dyachok O, Tengholm A, Arenas E, Uhlén P. Ca2+ and cAMP signaling in human embryonic stem cell-derived dopamine neurons. Stem Cells Dev 2011; 19:1355-64. [PMID: 20043754 DOI: 10.1089/scd.2009.0436] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Human embryonic stem (hES) cell differentiation into dopamine neurons is considered a promising strategy for cell replacement therapy in Parkinson's disease, yet the functional properties of hES cell-derived dopamine neurons remain poorly defined. The objective of this study was to characterize intracellular calcium (Ca(2+)) and sub-plasma membrane cyclic AMP-signaling properties in hES cell-derived dopamine neurons. We found that hES cell-derived dopamine neurons and neural progenitors raised Ca(2+) from intra- and extracellular compartments in response to depolarization, glutamate, ATP, and dopamine D(2) receptor activation, while undifferentiated hES cells only mobilized Ca(2+) from intracellular stores in response to ATP and D(2) receptor-induced activation. Interestingly, we also found that hES cell-derived dopamine neurons in addition to primary ventral midbrain dopamine neurons were more prone to release Ca(2+) from intracellular stores than non-dopamine neurons following treatment with the neuropeptide neurotensin. Furthermore, hES cell-derived dopamine neurons showed cAMP elevations in response to forskolin and 3-isobutyl-methylxanthine, similar to primary dopamine neurons. Taken together, these results unravel the temporal sequence by which hES cells acquire Ca(2+) and cAMP signaling competence during dopamine differentiation.
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Affiliation(s)
- Seth Malmersjö
- Department of Medical Biochemistry and Biophysics, Linnaeus Center in Developmental Biology for Regenerative Medicine, Karolinska Institutet, Stockholm, Sweden
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113
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Aumann TD, Egan K, Lim J, Boon WC, Bye CR, Chua HK, Baban N, Parish CL, Bobrovskaya L, Dickson P, Horne MK. Neuronal activity regulates expression of tyrosine hydroxylase in adult mouse substantia nigra pars compacta neurons. J Neurochem 2011; 116:646-58. [PMID: 21166807 DOI: 10.1111/j.1471-4159.2010.07151.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Striatal delivery of dopamine (DA) by midbrain substantia nigra pars compacta (SNc) neurons is vital for motor control and its depletion causes the motor symptoms of Parkinson's disease. While membrane potential changes or neuronal activity regulates tyrosine hydroxylase (TH, the rate limiting enzyme in catecholamine synthesis) expression in other catecholaminergic cells, it is not known whether the same occurs in adult SNc neurons. We administered drugs known to alter neuronal activity to mouse SNc DAergic neurons in various experimental preparations and measured changes in their TH expression. In cultured midbrain neurons, blockade of action potentials with 1 μM tetrodotoxin decreased TH expression beginning around 20 h later (as measured in real time by green fluorescent protein (GFP) expression driven off TH promoter activity). By contrast, partial blockade of small-conductance, Ca(2+) -activated potassium channels with 300 nM apamin increased TH mRNA and protein between 12 and 24 h later in slices of adult midbrain. Two-week infusions of 300 nM apamin directly to the adult mouse midbrain in vivo also increased TH expression in SNc neurons, measured immunohistochemically. Paradoxically, the number of TH immunoreactive (TH+) SNc neurons decreased in these animals. Similar in vivo infusions of drugs affecting other ion-channels and receptors (L-type voltage-activated Ca(2+) channels, GABA(A) receptors, high K(+) , DA receptors) also increased or decreased cellular TH immunoreactivity but decreased or increased, respectively, the number of TH+ cells in SNc. We conclude that in adult SNc neurons: (i) TH expression is activity-dependent and begins to change ∼20 h following sustained changes in neuronal activity; (ii) ion-channels and receptors mediating cell-autonomous activity or synaptic input are equally potent in altering TH expression; and (iii) activity-dependent changes in TH expression are balanced by opposing changes in the number of TH+ SNc cells.
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Affiliation(s)
- Tim D Aumann
- Florey Neuroscience Institutes, The University of Melbourne, Parkville, Victoria, Australia.
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114
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Kanbar R, Depuy SD, West GH, Stornetta RL, Guyenet PG. Regulation of visceral sympathetic tone by A5 noradrenergic neurons in rodents. J Physiol 2010; 589:903-17. [PMID: 21173073 DOI: 10.1113/jphysiol.2010.198374] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The ventrolateral pons contains the A5 group of noradrenergic neurons which regulate the circulation and probably breathing. The present experiments were designed to identify these neurons definitively in vivo, to examine their response to chemoreceptor stimuli (carotid body stimulation and changes in brain pH) and to determine their effects on sympathetic outflow. Bulbospinal A5 neurons, identified by juxtacellular labelling in anaesthetized rats, had a slow regular discharge, were vigorously activated by peripheral chemoreceptor stimulation with cyanide, but only mildly activated by hyperoxic hypercapnia (central chemoreceptor stimulation). The caudal end of the A5 region also contained neurons with properties reminiscent of retrotrapezoid neurons. These cells lacked a spinal axon and were characterized by a robust response to CO2. The pH sensitivity of A5 neurons, examined in brain slices from neonatal (postnatal days 6–10) tyrosine hydroxylase (TH)-GFP transgenic mice, was about 10 times smaller than that of similarly recorded retrotrapezoid neurons. Selective stimulation of the A5 neurons in rats using channelrhodopsin optogenetics (A5 TH neurons represented 66% of transfected cells) produced fivefold greater activation of the renal nerve than the lumbar sympathetic chain. In summary, adult A5 noradrenergic neurons are vigorously activated by carotid body stimulation. This effect presumably contributes to the increase in visceral sympathetic nerve activity elicited by acute hypoxia. A5 neurons respond weakly to hypercapnia in vivo or to changes in pH in slices suggesting that their ability to sense local variations in brain pH or Pco₂ is limited.
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Affiliation(s)
- Roy Kanbar
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
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115
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Jian K, Cifelli P, Pignatelli A, Frigato E, Belluzzi O. Metabotropic glutamate receptors 1 and 5 differentially regulate bulbar dopaminergic cell function. Brain Res 2010; 1354:47-63. [DOI: 10.1016/j.brainres.2010.07.104] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 07/28/2010] [Accepted: 07/30/2010] [Indexed: 02/04/2023]
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116
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Fasano C, Kortleven C, Trudeau LE. Chronic activation of the D2 autoreceptor inhibits both glutamate and dopamine synapse formation and alters the intrinsic properties of mesencephalic dopamine neurons in vitro. Eur J Neurosci 2010; 32:1433-41. [PMID: 20846243 DOI: 10.1111/j.1460-9568.2010.07397.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Dysfunctional dopamine (DA)-mediated signaling is implicated in several diseases including Parkinson's disease, schizophrenia and attention deficit and hyperactivity disorder. Chronic treatment with DA receptor agonists or antagonists is often used in pharmacotherapy, but the consequences of these treatments on DA neuron function are unclear. It was recently demonstrated that chronic D2 autoreceptor (D2R) activation in DA neurons decreases DA release and inhibits synapse formation. Given that DA neurons can establish synapses that release glutamate in addition to DA, we evaluated the synapse specificity of the functional and structural plasticity induced by chronic D2R activation. We show that chronic activation of the D2R with quinpirole in vitro caused a parallel decrease in the number of dopaminergic and glutamatergic axon terminals. The capacity of DA neurons to synthesize DA was not altered, as indicated by the lack of change in protein kinase A-mediated Ser(40) phosphorylation of tyrosine hydroxylase. However, the spontaneous firing rate of DA neurons was decreased and was associated with altered intrinsic properties as revealed by a prolonged latency to first spike after release from hyperpolarization. Moreover, D2R function was decreased after its chronic activation. Our results demonstrate that chronic activation of the D2R induces a complex neuronal reorganization involving the inhibition of both DA and glutamate synapse formation and an alteration in electrical activity, but not in DA synthesis. A better understanding of D2R-induced morphological and functional long-term plasticity may lead to improved pharmacotherapy of DA-related neurological and psychiatric disorders.
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Affiliation(s)
- C Fasano
- Department of Pharmacology, Groupe de Recherche sur le Système Nerveux Central, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
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117
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Contini M, Lin B, Kobayashi K, Okano H, Masland RH, Raviola E. Synaptic input of ON-bipolar cells onto the dopaminergic neurons of the mouse retina. J Comp Neurol 2010; 518:2035-50. [PMID: 20394057 DOI: 10.1002/cne.22320] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In the retina, dopamine fulfills a crucial role in neural adaptation to photopic illumination, but the pathway that carries cone signals to the dopaminergic amacrine (DA) cells was controversial. We identified the site of ON-cone bipolar input onto DA cells in transgenic mice in which both types of catecholaminergic amacrine (CA) cells were labeled with green fluorescent protein or human placental alkaline phosphatase (PLAP). In confocal Z series of retinal whole mounts stained with antibodies to tyrosine hydroxylase (TH), DA cells gave rise to varicose processes that descended obliquely through the scleral half of the inner plexiform layer (IPL) and formed a loose, tangential plexus in the middle of this layer. Comparison with the distribution of the dendrites of type 2 CA cells and examination of neurobiotin-injected DA cells proved that their vitreal processes were situated in stratum S3 of the IPL. Electron microscope demonstration of PLAP activity showed that bipolar cell endings in S3 established ribbon synapses onto a postsynaptic dyad in which one or both processes were labeled by a precipitate of lead phosphate and therefore belonged to DA cells. In places, the postsynaptic DA cell processes returned a reciprocal synapse onto the bipolar endings. Confocal images of sections stained with antibodies to TH, kinesin Kif3a, which labels synaptic ribbons, and glutamate or GABA(A) receptors, confirmed that ribbon-containing endings made glutamatergic synapses onto DA cells processes in S3 and received from them GABAergic synapses. The presynaptic ON-bipolar cells most likely belonged to the CB3 (type 5) variety.
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Affiliation(s)
- Massimo Contini
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
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118
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Zhang TA, Placzek AN, Dani JA. In vitro identification and electrophysiological characterization of dopamine neurons in the ventral tegmental area. Neuropharmacology 2010; 59:431-6. [PMID: 20600174 DOI: 10.1016/j.neuropharm.2010.06.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 06/08/2010] [Accepted: 06/10/2010] [Indexed: 01/21/2023]
Abstract
Dopamine (DA) neurons in the ventral tegmental area (VTA) have been implicated in brain mechanisms related to motivation, reward, and drug addiction. Successful identification of these neurons in vitro has historically depended upon the expression of a hyperpolarization-activated current (I(h)) and immunohistochemical demonstration of the presence of tyrosine hydroxylase (TH), the rate-limiting enzyme for DA synthesis. Recent findings suggest that electrophysiological criteria may be insufficient for distinguishing DA neurons from non-DA neurons in the VTA. In this study, we sought to determine factors that could potentially account for the apparent discrepancies in the literature regarding DA neuron identification in the rodent brain slice preparation. We found that confirmed DA neurons from the lateral VTA generally displayed a larger amplitude I(h) relative to DA neurons located in the medial VTA. Measurement of a large amplitude I(h) (>100 pA) consistently indicated a dopaminergic phenotype, but non-dopamine neurons also can have I(h) current. The data also showed that immunohistochemical TH labeling of DA neurons can render false negative results after relatively long duration (>15 min) whole-cell patch clamp recordings. We conclude that whole-cell patch clamp recording in combination with immunohistochemical detection of TH expression can guarantee positive but not negative DA identification in the VTA.
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Affiliation(s)
- Tao A Zhang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030-3498, USA
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119
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Akiba Y, Cave JW, Akiba N, Langley B, Ratan RR, Baker H. Histone deacetylase inhibitors de-repress tyrosine hydroxylase expression in the olfactory bulb and rostral migratory stream. Biochem Biophys Res Commun 2010; 393:673-7. [PMID: 20170631 DOI: 10.1016/j.bbrc.2010.02.054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 02/11/2010] [Indexed: 10/19/2022]
Abstract
Most olfactory bulb (OB) interneurons are derived from neural stem cells in the subventricular zone (SVZ) and migrate to the OB via the rostral migratory stream (RMS). Mature dopaminergic interneurons in the OB glomerular layer are readily identified by their synaptic activity-dependent expression of tyrosine hydroxylase (TH). Paradoxically, TH is not expressed in neural progenitors migrating in the RMS, even though ambient GABA and glutamate depolarize these progenitors. In forebrain slice cultures prepared from transgenic mice containing a GFP reporter gene under the control of the Th 9kb upstream regulatory region, treatment with histone deacetylase (HDAC) inhibitors (either sodium butyrate, Trichostatin A or Scriptaid) induced Th-GFP expression specifically in the RMS independently of depolarizing conditions in the culture media. Th-GFP expression in the glomerular layer was also increased in slices treated with Trichostatin A, but this increased expression was dependent on depolarizing concentrations of KCl in the culture media. Th-GFP expression was also induced in the RMS in vivo by intra-peritoneal injections with either sodium butyrate or valproic acid. Quantitative RT-PCR analysis of neurosphere cultures confirmed that HDAC inhibitors de-repressed Th expression in SVZ-derived neural progenitors. Together, these findings suggest that HDAC function is critical for regulating Th expression levels in both neural progenitors and mature OB dopaminergic neurons. However, the differential responses to the combinatorial exposure of HDAC inhibitors and depolarizing culture conditions indicate that Th expression in mature OB neurons and neural progenitors in the RMS are regulated by distinct HDAC-mediated mechanisms.
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Affiliation(s)
- Yosuke Akiba
- Burke Medical Research Institute, 785 Mamaroneck Ave, White Plains, NY 10605, USA
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120
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Pérez-Sánchez F, Milán M, Buendía P, Cano-Jaimez M, Ambrosio S, Rosenthal A, Fariñas I. Prosurvival effect of human wild-type alpha-synuclein on MPTP-induced toxicity to central but not peripheral catecholaminergic neurons isolated from transgenic mice. Neuroscience 2010; 167:261-76. [PMID: 20156526 DOI: 10.1016/j.neuroscience.2010.02.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 02/01/2010] [Accepted: 02/08/2010] [Indexed: 12/15/2022]
Abstract
In the present work we report the generation of a new line of alpha-synuclein (alpha-SYN) transgenic mice in which the human wild-type alpha-SYN cDNA is expressed under the control of a tyrosine hydroxylase (TH) promoter. We provide evidence that the ectopic protein is found in TH expressing neurons of both central and peripheral nervous systems. The transgene is expressed very early in development coinciding with the activity of the TH promoter and in the adult brain the human protein distributes normally to the nerve endings and cell bodies of dopaminergic nigral neurons without any evidence of abnormal aggregation. Our results indicate that expression of human wild-type alpha-SYN does not affect normal development or maintenance of TH immunoreactive nigral neurons, striatal dopamine content, or locomotor activity. Systemic administration of the parkinsonian neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induces a loss of TH immunoreactive nigral neurons and terminals and of dopamine levels to the same degree in both transgenic and non-transgenic adult mice. Intoxication also results in a similar loss of cardiac noradrenaline in both genotypes. Surprisingly, cultured transgenic ventral mesencephalic fetal dopaminergic neurons exhibit complete resistance to cell death induced by 1-methyl-4-phenylpyridinium ion (MPP(+)) intoxication, without changes in dopamine transporter (DAT) surface levels. Interestingly, this protection is not observed in other populations of catecholaminergic neurons such as peripheral sympathetic neurons, despite their high sensitivity to MPP(+)in vitro.
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Affiliation(s)
- F Pérez-Sánchez
- Departament de Biologia cellular and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Universitat de València, 46100 Burjassot, València, Spain.
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121
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Abstract
Within glomeruli, the initial sites of synaptic integration in the olfactory pathway, olfactory sensory axons terminate on dendrites of projection and juxtaglomerular (JG) neurons. JG cells form at least two major circuits: the classic intraglomerular circuit consisting of external tufted (ET) and periglomerular (PG) cells and an interglomerular circuit comprised of the long-range connections of short axon (SA) cells. We examined the projections and the synaptic inputs of identified JG cell chemotypes using mice expressing green fluorescent protein (GFP) driven by the promoter for glutamic acid decarboxylase (GAD) 65 kDa, 67 kDa, or tyrosine hydroxylase (TH). Virtually all (97%) TH+ cells are also GAD67+ and are thus DAergic-GABAergic neurons. Using a combination of retrograde tracing, whole-cell patch-clamp recording, and single-cell three-dimensional reconstruction, we show that different JG cell chemotypes contribute to distinct microcircuits within or between glomeruli. GAD65+ GABAergic PG cells ramify principally within one glomerulus and participate in uniglomerular circuits. DAergic-GABAergic cells have extensive interglomerular projections. DAergic-GABAergic SA cells comprise two subgroups. One subpopulation contacts 5-12 glomeruli and is referred to as "oligoglomerular." Approximately one-third of these oligoglomerular DAergic SA cells receive direct olfactory nerve (ON) synaptic input, and the remaining two-thirds receive input via a disynaptic ON-->ET-->SA circuit. The second population of DAergic-GABAergic SA cells also disynaptic ON input and connect tens to hundreds of glomeruli in an extensive "polyglomerular" network. Although DAergic JG cells have traditionally been considered PG cells, their interglomerular connections argue that they are more appropriately classified as SA cells.
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122
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Guyenet PG, Stornetta RL, Abbott SBG, Depuy SD, Fortuna MG, Kanbar R. Central CO2 chemoreception and integrated neural mechanisms of cardiovascular and respiratory control. J Appl Physiol (1985) 2010; 108:995-1002. [PMID: 20075262 DOI: 10.1152/japplphysiol.00712.2009] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In this review, we examine why blood pressure (BP) and sympathetic nerve activity (SNA) increase during a rise in central nervous system (CNS) P(CO(2)) (central chemoreceptor stimulation). CNS acidification modifies SNA by two classes of mechanisms. The first one depends on the activation of the central respiratory controller (CRG) and causes the much-emphasized respiratory modulation of the SNA. The CRG probably modulates SNA at several brain stem or spinal locations, but the most important site of interaction seems to be the caudal ventrolateral medulla (CVLM), where unidentified components of the CRG periodically gate the baroreflex. CNS P(CO(2)) also influences sympathetic tone in a CRG-independent manner, and we propose that this process operates differently according to the level of CNS P(CO(2)). In normocapnia and indeed even below the ventilatory recruitment threshold, CNS P(CO(2)) exerts a tonic concentration-dependent excitatory effect on SNA that is plausibly mediated by specialized brain stem chemoreceptors such as the retrotrapezoid nucleus. Abnormally high levels of P(CO(2)) cause an aversive interoceptive awareness in awake individuals and trigger arousal from sleep. These alerting responses presumably activate wake-promoting and/or stress-related pathways such as the orexinergic, noradrenergic, and serotonergic neurons. These neuronal groups, which may also be directly activated by brain acidification, have brainwide projections that contribute to the CO(2)-induced rise in breathing and SNA by facilitating neuronal activity at innumerable CNS locations. In the case of SNA, these sites include the nucleus of the solitary tract, the ventrolateral medulla, and the preganglionic neurons.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908-0735, USA.
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Lazarenko RM, Milner TA, Depuy SD, Stornetta RL, West GH, Kievits JA, Bayliss DA, Guyenet PG. Acid sensitivity and ultrastructure of the retrotrapezoid nucleus in Phox2b-EGFP transgenic mice. J Comp Neurol 2009; 517:69-86. [PMID: 19711410 DOI: 10.1002/cne.22136] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The retrotrapezoid nucleus (RTN) contains noncholinergic noncatecholaminergic glutamatergic neurons that express the transcription factor Phox2b (chemically coded or "cc" RTN neurons). These cells regulate breathing and may be central chemoreceptors. Here we explore their ultrastructure and their acid sensitivity by using two novel BAC eGFP-Phox2b transgenic mice (B/G, GENSAT JX99) in which, respectively, 36% and 100% of the cc RTN neurons express the transgene in complete or partial anatomical isolation from other populations of eGFP neurons. All but one of the eGFP-labeled RTN neurons recorded in these mice were acid activated in slices. These cells contained VGLUT2 mRNA, and 50% contained preprogalanin mRNA (determined by single-cell PCR in the B/G mouse). Two neuronal subgroups were revealed, which differed in discharge rate at pH 7.3 (type I approximately 2; type II approximately 4 Hz) and the degree of alkalization that silenced the cells (type I 7.4-7.6, type II 7.8-8.0). Medial to the RTN, C1 neurons recorded in a tyrosine hydroxylase-GFP mouse were pH insensitive between pH 6.9 and pH 7.5. Ultrastructural studies demonstrated that eGFP-labeled RTN neurons were surrounded by numerous capillaries and were often in direct contact with glial cells, pericytes, and the basement membrane of capillaries. Terminals contacting large proximal eGFP dendrites formed mainly symmetric, likely inhibitory, synapses. Terminals on more distal eGFP dendrites formed preferentially asymmetric, presumably excitatory, synapses. In sum, C1 cells are pH insensitive, whereas cc RTN neurons are uniformly acid sensitive. The RTN neurons receive inhibitory and excitatory synaptic inputs and may have unfettered biochemical interactions with glial cells and the local microvasculature.
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Affiliation(s)
- Roman M Lazarenko
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908-0735, USA
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124
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Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder caused by loss-of-function mutations in the Methyl-CpG-binding protein-2 (MECP2) gene and is characterized by derangements in cognition, behavior, motor control, respiration and autonomic homeostasis, as well as seizures. Deficits in norepinephrine (NE) are thought to contribute to RTT pathogenesis, but little is known about how MeCP2 regulates function of noradrenergic neurons. We therefore characterized morphological, electrical, and neurochemical properties of neurons in the locus ceruleus (LC), the major source of noradrenergic innervation to the central neuraxis, in Mecp2 mutant mice. We found that MeCP2 null LC neurons are electrically hyperexcitable, smaller in size, and express less of the NE-synthesizing enzyme tyrosine hydroxylase (TH) compared with wild-type neurons. Increased excitability of mutant neurons is associated with reductions in passive membrane conductance and the amplitude of the slow afterhyperpolarization. Studies in Mecp2 heterozygotes, which are mosaic for the null allele, demonstrated that electrical hyperexcitability and reduced neuronal size are cell-autonomous consequences of MeCP2 loss, whereas reduced TH expression appears to reflect both cell-autonomous and non-autonomous influences. Finally, we found reduced levels of TH and norepinephrine in cingulate cortex, a forebrain target of the LC. Thus, genetic loss of MeCP2 results in a somewhat paradoxical LC neuron phenotype, characterized by both electrical hyperexcitability and reduced indices of noradrenergic function. Given the importance of the LC in modulating activity in brainstem and forebrain networks, we hypothesize that dysregulation of LC function in the absence of MeCP2 plays a key role in the pathophysiology of RTT.
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125
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Akiba Y, Sasaki H, Huerta PT, Estevez AG, Baker H, Cave JW. gamma-Aminobutyric acid-mediated regulation of the activity-dependent olfactory bulb dopaminergic phenotype. J Neurosci Res 2009; 87:2211-21. [PMID: 19301430 DOI: 10.1002/jnr.22055] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
gamma-Aminobutyric acid (GABA) regulates the proliferation and migration of olfactory bulb (OB) interneuron progenitors derived from the subventricular zone (SVZ), but the role of GABA in the differentiation of these progenitors has been largely unexplored. This study examines the role of GABA in the differentiation of OB dopaminergic interneurons using neonatal forebrain organotypic slice cultures prepared from transgenic mice expressing green fluorescent protein (GFP) under the control of the tyrosine hydroxylase (Th) gene promoter (ThGFP). KCl-mediated depolarization of the slices induced ThGFP expression. The addition of GABA to the depolarized slices further increased GFP fluorescence by inducing ThGFP expression in an additional set of periglomerular cells. These findings show that GABA promoted differentiation of SVZ-derived OB dopaminergic interneurons and suggest that GABA indirectly regulated Th expression and OB dopaminergic neuron differentiation through an acceleration of the maturation rate for the dopaminergic progenitors. Additional studies revealed that the effect of GABA on ThGFP expression required activation of L- and P/Q-type Ca2+ channels as well as GABA(A) and GABA(B) receptors. These voltage-gated Ca2+ channels and GABA receptors have previously been shown to be required for the coexpressed GABAergic phenotype in the OB interneurons. Together, these findings suggest that Th expression and the differentiation of OB dopaminergic interneurons are coupled to the coexpressed GABAergic phenotype and demonstrate a novel role for GABA in neurogenesis.
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Affiliation(s)
- Yosuke Akiba
- Burke Medical Research Institute, White Plains, NY 10605. USA
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126
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Cooper MA, Kobayashi K, Zhou R. Ephrin-A5 regulates the formation of the ascending midbrain dopaminergic pathways. Dev Neurobiol 2009; 69:36-46. [PMID: 19003794 DOI: 10.1002/dneu.20685] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Dopaminergic neurons from the substantia nigra and the ventral tegmental area of the midbrain project to the caudate/putamen and nucleus accumbens, respectively, establishing the mesostriatal and the mesolimbic pathways. However, the mechanisms underlying the development of these pathways are not well understood. In the current study, the EphA5 receptor and its corresponding ligand, ephrin-A5, were shown to regulate dopaminergic axon outgrowth and influence the formation of the midbrain dopaminergic pathways. Using a strain of mutant mice in which the EphA5 cytoplasmic domain was replaced with beta-galactosidase, EphA5 protein expression was detected in both the ventral tegmental area and the substantia nigra of the midbrain. Ephrin-A5 was found in both the dorsolateral and the ventromedial regions of the striatum, suggesting a role in mediating dopaminergic axon-target interactions. In the presence of ephrin-A5, dopaminergic neurons extended longer neurites in in vitro coculture assays. Furthermore, in mice lacking ephrin-A5, retrograde tracing studies revealed that fewer neurons sent axons to the striatum. These observations indicate that the interactions between ephrin-A ligands and EphA receptors promote growth and targeting of the midbrain dopaminergic axons to the striatum.
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Affiliation(s)
- Margaret A Cooper
- Department of Chemical Biology, Ernest P. Mario School of Pharmacy, Rutgers University, Piscataway, New Jersey 08854, USA
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127
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Hao M, Anderson R, Kobayashi K, Whitington P, Young H. The migratory behavior of immature enteric neurons. Dev Neurobiol 2009; 69:22-35. [DOI: 10.1002/dneu.20683] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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128
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Saino-Saito S. Visualization of spatiotemporal differentiation of dopaminergic interneurons in adult mouse olfactory bulb using transgenic mice. Anat Sci Int 2008; 83:228-31. [DOI: 10.1111/j.1447-073x.2007.00209.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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129
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Pignatelli A, Ackman JB, Vigetti D, Beltrami AP, Zucchini S, Belluzzi O. A potential reservoir of immature dopaminergic replacement neurons in the adult mammalian olfactory bulb. Pflugers Arch 2008; 457:899-915. [PMID: 19011893 DOI: 10.1007/s00424-008-0535-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Accepted: 05/16/2008] [Indexed: 11/30/2022]
Abstract
A significant fraction of the interneurons added in adulthood to the glomerular layer (GL) of the olfactory bulb (OB) are dopaminergic (DA). In the OB, DA neurons are restricted to the GL, but using transgenic mice expressing eGFP under the tyrosine hydroxylase (TH) promoter, we also detected the presence of TH-GFP+ cells in the mitral and external plexiform layers. We hypothesized that these could be adult-generated neurons committed to become DA but not yet entirely differentiated. Accordingly, TH-GFP+ cells outside the GL exhibit functional properties (appearance of pacemaker currents, synaptic connection with the olfactory nerve, intracellular chloride concentration, and other) marking a gradient of maturity toward the dopaminergic phenotype along the mitral-glomerular axis. Finally, we propose that the establishment of a synaptic contact with the olfactory nerve is the key event allowing these cells to complete their differentiation toward the DA phenotype and to reach their final destination.
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Affiliation(s)
- Angela Pignatelli
- Sez. Fisiologia e Biofisica, Dipartimento di Biologia ed Evoluzione, Università degli Studi di Ferrara, Via Borsari 46, 44100, Ferrara, Italy
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130
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Fasano C, Poirier A, DesGroseillers L, Trudeau LE. Chronic activation of the D2 dopamine autoreceptor inhibits synaptogenesis in mesencephalic dopaminergic neuronsin vitro. Eur J Neurosci 2008; 28:1480-90. [DOI: 10.1111/j.1460-9568.2008.06450.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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131
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Descarries L, Bérubé-Carrière N, Riad M, Bo GD, Mendez JA, Trudeau LÉ. Glutamate in dopamine neurons: Synaptic versus diffuse transmission. ACTA ACUST UNITED AC 2008; 58:290-302. [DOI: 10.1016/j.brainresrev.2007.10.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Revised: 10/16/2007] [Accepted: 10/18/2007] [Indexed: 10/22/2022]
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132
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Developmental and target-dependent regulation of vesicular glutamate transporter expression by dopamine neurons. J Neurosci 2008; 28:6309-18. [PMID: 18562601 DOI: 10.1523/jneurosci.1331-08.2008] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mesencephalic dopamine (DA) neurons have been suggested to use glutamate as a cotransmitter. Here, we suggest a mechanism for this form of cotransmission by showing that a subset of DA neurons both in vitro and in vivo expresses vesicular glutamate transporter 2 (VGluT2). Expression of VGluT2 decreases with age. Moreover, when DA neurons are grown in isolation using a microculture system, there is a marked upregulation of VGluT2 expression. We provide evidence that expression of this transporter is normally repressed through a contact-dependent interaction with GABA and other DA neurons, thus providing a partial explanation for the highly restricted expression of VGluT2 in DA neurons in vivo. Our results demonstrate that the neurotransmitter phenotype of DA neurons is both developmentally and dynamically regulated. These findings may have implications for a better understanding of the fast synaptic action of DA neurons as well as basal ganglia circuitry.
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133
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Miura M, Masuda M, Aosaki T. Roles of micro-opioid receptors in GABAergic synaptic transmission in the striosome and matrix compartments of the striatum. Mol Neurobiol 2008; 37:104-15. [PMID: 18473190 DOI: 10.1007/s12035-008-8023-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 04/17/2008] [Indexed: 10/22/2022]
Abstract
The striatum is divided into two compartments, the striosomes and extrastriosomal matrix, which differ in several cytochemical markers, input-output connections, and time of neurogenesis. Since it is thought that limbic, reward-related information and executive aspects of behavioral information may be differentially processed in the striosomes and matrix, respectively, intercompartmental communication should be of critical importance to proper functioning of the basal ganglia-thalamocortical circuits. Cholinergic interneurons are in a suitable position for this communication since they are preferentially located in the striosome-matrix boundaries and are known to elicit a conditioned pause response during sensorimotor learning. Recently, micro-opioid receptor (MOR) activation was found to presynaptically suppress the amplitude of GABAergic inhibitory postsynaptic currents in striosomal cells but not in matrix cells. Disinhibition of cells in the striosomes is further enhanced by inactivation of the protein kinase C cascade. We discuss in this review the possibility that MOR activation in the striosomes affects the activity of cholinergic interneurons and thus leads to changes in synaptic efficacy in the striatum.
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Affiliation(s)
- Masami Miura
- Neural Circuits Dynamics Research Group, Tokyo Metropolitan Institute of Gerontology, 35-2, Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan
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134
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Pignatelli A, Belluzzi O. Cholinergic modulation of dopaminergic neurons in the mouse olfactory bulb. Chem Senses 2008; 33:331-8. [PMID: 18209017 DOI: 10.1093/chemse/bjm091] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Considerable evidence exists for an extrinsic cholinergic influence in the maturation and function of the main olfactory bulb. In this study, we addressed the muscarinic modulation of dopaminergic neurons in this structure. We used different patch-clamp techniques to characterize the diverse roles of muscarinic agonists on identified dopaminergic neurons in a transgenic animal model expressing a reporter protein (green fluorescent protein) under the tyrosine hydroxylase promoter. Bath application of acetylcholine (1 mM) in slices and in enzymatically dissociated cells reduced the spontaneous firing of dopaminergic neurons recorded in cell-attached mode. In whole-cell configuration no effect of the agonist was observed, unless using the perforated patch technique, thus suggesting the involvement of a diffusible second messenger. The effect was mediated by metabotropic receptors as it was blocked by atropine and mimicked by the m2 agonist oxotremorine (10 muM). The reduction of periglomerular cell firing by muscarinic activation results from a membrane-potential hyperpolarization caused by activation of a potassium conductance. This modulation of dopaminergic interneurons may be important in the processing of sensory information and may be relevant to understand the mechanisms underlying the olfactory dysfunctions occurring in neurodegenerative diseases affecting the dopaminergic and/or cholinergic systems.
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Affiliation(s)
- Angela Pignatelli
- Dipartimento di Biologia ed Evoluzione, Sez. Fisiologia e Biofisica, Via Borsari 46, 44100 Ferrara, Italy
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135
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Visceral afferents directly activate catecholamine neurons in the solitary tract nucleus. J Neurosci 2008; 27:13292-302. [PMID: 18045923 DOI: 10.1523/jneurosci.3502-07.2007] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Brainstem A2/C2 neurons are catecholamine (CA) neurons within the solitary tract nucleus (NTS) that influence many homeostatic functions, including cardiovascular reflexes, food intake, and stress. Because NTS is a major interface between sensory visceral afferents and the CNS, NTS CA neurons are ideally suited to coordinate complex responses by their projections to multiple brain regions. To test how NTS CA neurons process visceral afferent information carried by solitary tract (ST) afferents, we identified CA neurons using transgenic mice expressing TH-EGFP (enhanced green fluorescent protein under the control of the tyrosine hydroxylase promoter) and recorded synaptic responses to ST activation in horizontal slices. ST shocks evoked large-amplitude, short-latency, glutamatergic EPSCs (ST-EPSCs) in 90% of NTS CA neurons. Within neurons, ST-EPSCs had constant latency, rarely failed, and depressed substantially at high ST frequencies, indicating that NTS CA neurons receive direct monosynaptic connections from afferent terminals. NTS CA neurons received direct ST inputs from only one or two afferent fibers, with one-half also receiving smaller amplitude indirect inputs. Up to 90% of ST shocks evoked action potentials in NTS CA neurons. However, transmission of sensory afferent information through NTS CA neurons critically depended on the expression of an A-type potassium current (I(KA)), which when active attenuated ST-activated action potentials to a 37% success rate. The satiety peptide, cholecystokinin, presynaptically facilitated glutamate transmission in one-half of NTS CA neurons. Thus, NTS CA neurons are directly driven by visceral afferents with output being modulated by presynaptic peptide receptors and postsynaptic potassium channels.
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136
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Miura M, Saino-Saito S, Masuda M, Kobayashi K, Aosaki T. Compartment-specific modulation of GABAergic synaptic transmission by mu-opioid receptor in the mouse striatum with green fluorescent protein-expressing dopamine islands. J Neurosci 2007; 27:9721-8. [PMID: 17804632 PMCID: PMC6672981 DOI: 10.1523/jneurosci.2993-07.2007] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The striatum is a heterogeneous mosaic of two neurochemically, developmentally, and functionally distinct compartments: the mu-opioid receptor (MOR)-enriched striosomes and the matrix. Preferential activation of the striosomes and persistent suppression of the matrix have recently been suggested to represent neural correlates of motor stereotypy. However, little is known concerning the physiological properties of the striosomes. We made patch-clamp recordings from medium spiny neurons in identified MOR-immunoreactive "dopamine islands" as striosomes in a slice preparation taken from transgenic mice expressing green fluorescent protein in tyrosine hydroxylase mRNA-containing neurons. Striosomal neurons differed electrophysiologically from cells in the matrix in having significantly less hyperpolarized resting membrane potentials and larger input resistances, suggesting developmental differences between the two types of cells. Moreover, corticostriatal EPSCs were inhibited by MOR activation to similar extents in the two compartments, although inhibition of IPSCs was observed only in the striosomes. This MOR-induced inhibition of IPSCs was presynaptically mediated, because MOR agonist invariably decreased IPSC amplitudes when postsynaptic G-protein was inactivated, significantly increased the paired-pulse ratio of the IPSCs, and decreased the frequency but not the amplitude of miniature IPSCs. These effects of MOR were mediated principally by 4-aminopyridine-sensitive K+ conductance via a cAMP-dependent pathway, which was further augmented by previous blockade of the protein kinase C cascade. These findings suggest that MOR activation by endogenous and/or exogenous MOR-selective opioid substances differentially regulates the activities of the striosome and matrix compartments and thus plays an important role in motivated behavior and learning.
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Affiliation(s)
- Masami Miura
- Neural Circuits Dynamics Research Group, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo 173-0015, Japan
| | - Sachiko Saino-Saito
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata, Yamagata 990-9585, Japan, and
| | - Masao Masuda
- Neural Circuits Dynamics Research Group, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo 173-0015, Japan
| | - Kazuto Kobayashi
- Fukushima Medical University School of Medicine, Fukushima, Fukushima 960-1295, Japan
| | - Toshihiko Aosaki
- Neural Circuits Dynamics Research Group, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo 173-0015, Japan
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137
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Saino-Saito S, Cave JW, Akiba Y, Sasaki H, Goto K, Kobayashi K, Berlin R, Baker H. ER81 and CaMKIV identify anatomically and phenotypically defined subsets of mouse olfactory bulb interneurons. J Comp Neurol 2007; 502:485-96. [PMID: 17394138 DOI: 10.1002/cne.21293] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The mechanisms underlying dopamine (DA) phenotypic differentiation in the olfactory bulb (OB) have not yet been fully elucidated and are the subject of some controversy. OB DA interneurons destined for the glomerular layer were shown to originate in the subventricular zone (SVZ) and in the rostral migratory stream (RMS). The current study investigated whether calcium/calmodulin-dependent protein kinase IV (CaMKIV) either alone or together with the Ets transcription factor ER81 was necessary for phenotypic determination during migration of progenitors. In most brain areas, including the OB, CaMKIV and ER81 displayed a reciprocal distribution. In the SVZ, only ER81 could be demonstrated. In the RMS, a subpopulation of progenitors contained ER81, but few, if any, contained CaMKIV. In OB, CaMKIV expression, restricted to deep granule cells, showed limited overlap with ER81. ER81 expression was weak in deep granule cells. Strong labeling occurred in the mitral and glomerular layers, where ER81 colabeled dopaminergic periglomerular cells that expressed either tyrosine hydroxylase (TH) or green fluorescent protein, the latter reporter gene under control of 9-kb of 5' TH promoter. Odor deprivation resulted in a significant 5.2-fold decline in TH immunoreactivity, but ER81 exhibited a relatively small 1.7-fold decline in immunoreactivity. TH expression as well as brain and bulb size were unchanged in CaMKIV knockout mice. These data suggest that ER81 may be required but is not sufficient for DA neuron differentiation and that CaMKIV is not directly involved in TH gene regulation.
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Affiliation(s)
- Sachiko Saino-Saito
- Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata, Japan 990-9585
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138
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Teh CHL, Loh CC, Lam KKY, Loo JM, Yan T, Lim TM. Neuronal PAS domain protein 1 regulates tyrosine hydroxylase level in dopaminergic neurons. J Neurosci Res 2007; 85:1762-73. [PMID: 17457889 DOI: 10.1002/jnr.21312] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Catecholamines (dopamine, norepinephrine, and epinephrine) are all synthesized from a common pathway in which tyrosine hydroxylase (TH) is the rate-limiting enzyme. Dopamine is the main neurotransmitter present in dopaminergic neurons of the ventral midbrain, where dysfunction of these neurons can lead to Parkinson's disease and schizophrenia. Neuronal PAS domain protein 1 (NPAS1) was identified as one of the genes up-regulated during dopaminergic MN9D cell differentiation. We found that there was a corresponding decrease in TH level during MN9D differentiation. Overexpression and siRNA experiments revealed that NPAS1, in concert with ARNT, negatively regulates the expression of TH and that this regulation is mediated by a direct binding of NPAS1 on the TH promoter. Expression studies also confirmed a decrease in TH level in the ventral midbrain during mouse development, concomitant with an increase in NPAS1 level. These results suggest that NPAS1 plays a novel and important role in regulating TH level of dopaminergic neurons in the ventral midbrain during development.
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Affiliation(s)
- Christina H L Teh
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
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139
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Tu Y, Kroener S, Abernathy K, Lapish C, Seamans J, Chandler LJ, Woodward JJ. Ethanol inhibits persistent activity in prefrontal cortical neurons. J Neurosci 2007; 27:4765-75. [PMID: 17460089 PMCID: PMC3625968 DOI: 10.1523/jneurosci.5378-06.2007] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cognitive functions supported by neurons in the prefrontal cortex (PFC) are disrupted by acute and chronic exposure to alcohol, yet little is known about the mechanisms that underlie these effects. In the present study, in vivo and in vitro electrophysiology was used to determine the effects of ethanol on neuronal firing and network patterns of persistent activity in PFC neurons. In vivo, ethanol (0.375-3.5 g/kg) dose-dependently reduced spike activity in the PFC measured with multielectrode extracellular recording in the anesthetized rat. In an in vitro coculture system containing slices of PFC, hippocampus, and ventral tegmental area (VTA), ethanol (25-100 mM) decreased persistent activity of PFC neurons, but had little effect on firing evoked by direct current injection. Persistent activity was often enhanced after ethanol washout and this effect was maintained in cultures lacking the VTA. A low concentration of the NMDA antagonist APV (5 microM) mimicked the inhibition of ethanol of persistent activity with no change in activity after washout. Ethanol inhibition of spontaneous and VTA-evoked persistent activity was enhanced by the D1 dopamine receptor antagonist SCH23390 [R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride]. The results of this study show that ethanol inhibits persistent activity and spike firing of PFC neurons and that the degree of ethanol inhibition may be influenced by D1 receptor tone. Ethanol-induced alterations in the activity of deep-layer cortical neurons may underlie some of the behavioral effects associated with ethanol intake.
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Affiliation(s)
- Yali Tu
- Department of Neurosciences and Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Sven Kroener
- Department of Neurosciences and Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Kenneth Abernathy
- Department of Neurosciences and Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Christopher Lapish
- Department of Neurosciences and Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Jeremy Seamans
- Department of Neurosciences and Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina 29425
| | - L. Judson Chandler
- Department of Neurosciences and Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina 29425
| | - John J. Woodward
- Department of Neurosciences and Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina 29425
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140
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Hedlund E, Pruszak J, Ferree A, Viñuela A, Hong S, Isacson O, Kim KS. Selection of embryonic stem cell-derived enhanced green fluorescent protein-positive dopamine neurons using the tyrosine hydroxylase promoter is confounded by reporter gene expression in immature cell populations. Stem Cells 2007; 25:1126-35. [PMID: 17234989 PMCID: PMC2614084 DOI: 10.1634/stemcells.2006-0540] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Transplantation of mouse embryonic stem (mES) cells can restore function in Parkinson disease models, but can generate teratomas. Purification of dopamine neurons derived from embryonic stem cells by fluorescence-activated cell sorting (FACS) could provide a functional cell population for transplantation while eliminating the risk of teratoma formation. Here we used the tyrosine hydroxylase (TH) promoter to drive enhanced green fluorescent protein (eGFP) expression in mES cells. First, we evaluated 2.5-kilobase (kb) and 9-kb TH promoter fragments and showed that clones generated using the 9-kb fragment produced significantly more eGFP+/TH+ neurons. We selected the 9-kb TH clone with the highest eGFP/TH overlap for further differentiation, FACS, and transplantation experiments. Grafts contained large numbers of eGFP+ dopamine neurons of an appropriate phenotype. However, there were also numerous eGFP+ cells that did not express TH and did not have a neuronal morphology. In addition, we found cells in the grafts representing all three germ layers. Based on these findings, we examined the expression of stem cell markers in our eGFP+ population. We found that a majority of eGFP+ cells were stage-specific embryonic antigen-positive (SSEA-1+) and that the genetically engineered clones contained more SSEA-1+ cells after differentiation than the original D3 mES cells. By negative selection of SSEA-1, we could isolate a neuronal eGFP+ population of high purity. These results illustrate the complexity of using genetic selection to purify mES cell-derived dopamine neurons and provide a comprehensive analysis of cell selection strategies based on tyrosine hydroxylase expression. Disclosure of potential conflicts of interest is found at the end of this article.
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Affiliation(s)
- Eva Hedlund
- Udall Parkinson's Disease Research Center for Excellence, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
- Molecular Neurobiology Laboratories, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
- Neuroregeneration Laboratories, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
| | - Jan Pruszak
- Udall Parkinson's Disease Research Center for Excellence, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
- Neuroregeneration Laboratories, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
| | - Andrew Ferree
- Udall Parkinson's Disease Research Center for Excellence, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
- Neuroregeneration Laboratories, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
| | - Angel Viñuela
- Udall Parkinson's Disease Research Center for Excellence, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
- Neuroregeneration Laboratories, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
| | - Sunghoi Hong
- Udall Parkinson's Disease Research Center for Excellence, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
- Neuroregeneration Laboratories, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
| | - Ole Isacson
- Udall Parkinson's Disease Research Center for Excellence, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
- Neuroregeneration Laboratories, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
| | - Kwang-Soo Kim
- Udall Parkinson's Disease Research Center for Excellence, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
- Molecular Neurobiology Laboratories, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA
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141
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Paul G, Christophersen NS, Raymon H, Kiaer C, Smith R, Brundin P. Tyrosine hydroxylase expression is unstable in a human immortalized mesencephalic cell line--studies in vitro and after intracerebral grafting in vivo. Mol Cell Neurosci 2007; 34:390-9. [PMID: 17222562 DOI: 10.1016/j.mcn.2006.11.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Revised: 11/09/2006] [Accepted: 11/14/2006] [Indexed: 11/17/2022] Open
Abstract
We have studied the stability of the dopaminergic phenotype in a conditionally immortalized human mesencephalic cell line, MESC2.10. Even though MESC2.10 cells exhibit features of dopaminergic neurons in vitro, none of the cells expressed tyrosine hydroxylase (TH) after transplantation into a rat model of Parkinson's disease. We examined whether this is caused by cell death or loss of transmitter phenotype. Cells were cultured in differentiation medium, then harvested and replated into the same medium where they continued to express TH, whereas replated cells fed medium lacking differentiation factors (dibutyryl cAMP and glial cell line-derived neurotrophic factor) did not. Interestingly, cultures grown in the absence of differentiation factors could regain TH expression once exposed to differentiation medium. Our data suggest that TH expression in vitro is inducible in neurons derived from the MESC2.10 cell line and that the dopaminergic phenotype of these cells in vivo might be unstable.
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Affiliation(s)
- Gesine Paul
- Neuronal Survival Unit, Department of Experimental Medical Science, Wallenberg Neuroscience Center, 22184-Lund, Sweden.
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142
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Jomphe C, Lemelin PL, Okano H, Kobayashi K, Trudeau LE. Bidirectional regulation of dopamine D2 and neurotensin NTS1 receptors in dopamine neurons. Eur J Neurosci 2006; 24:2789-800. [PMID: 17116165 DOI: 10.1111/j.1460-9568.2006.05151.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Several lines of evidence suggest a close association between dopamine (DA) and neurotensin (NT) systems in the CNS. Indeed, in the rodent brain, abundant NT-containing fibres are found in DA-rich areas such as the ventral tegmental area and substantia nigra. Moreover, it has been shown in vivo that NT, acting through its high-affinity receptor (NTS1), reduces the physiological and behavioural effects of DA D2 receptor (D2R) activation, a critical autoreceptor feedback system regulating DA neurotransmission. However, the mechanism of this interaction is still elusive. The aim of our study was thus to reproduce in vitro the interaction between D2R and NTS1, and then to characterize the mechanisms implicated. We used a primary culture model of DA neurons prepared from transgenic mice expressing green fluorescent protein under the control of the tyrosine hydroxylase promoter. In these cultures, DA neurons endogenously express both D2R and NTS1. Using electrophysiological recordings, we show that activation of D2R directly inhibits the firing rate of DA neurons. In addition, we find that NT, acting through a NTS1-like receptor, is able to reduce D2R autoreceptor function independently of its ability to enhance DA neuron firing, and that this interaction occurs through a protein kinase C- and Ca(2+)-dependent mechanism. Furthermore, prior activation of D2R reduces the ability of NTS1 to induce intracellular Ca(2+) mobilization. Our findings provide evidence for bidirectional interaction between D2R and NTS1 in DA neurons, a regulatory mechanism that could play a key role in the control of the activity of these neurons.
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Affiliation(s)
- C Jomphe
- Department of Pharmacology, Faculty of Medicine, Groupe de Recherche sur le Système Nerveux Central, Centre de Recherche Fernand Seguin, Université de Montréal, Montréal, Québec, Canada
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143
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Nelson SB, Hempel C, Sugino K. Probing the transcriptome of neuronal cell types. Curr Opin Neurobiol 2006; 16:571-6. [PMID: 16962313 DOI: 10.1016/j.conb.2006.08.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Accepted: 08/25/2006] [Indexed: 01/19/2023]
Abstract
Distinct neuronal cell types acquire and maintain their identity by expressing different genes. Recently it has become feasible to measure this cell type specific expression by isolating and amplifying mRNA from small populations of fluorescently labeled neurons and probing this mRNA with microarrays. Prior to this, most neuronal gene expression studies used tissue homogenates or randomly selected single cells and were, therefore, not well suited to studying transcriptional differences between cell types. Microarray studies of purified cell types have enabled investigators to identify the transcriptional signatures of, for example, subtypes of pyramidal neurons and interneurons in the neocortex, modulatory dopaminergic and serotonergic neurons, and the striatal neurons that form the so-called 'direct' and 'indirect' pathways through the basal ganglia. These studies are opening up new approaches to understanding brain circuitry, plasticity and pathology and are refining the concept of the neuronal cell type.
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Affiliation(s)
- Sacha B Nelson
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, MS 008, 415 South Street, Waltham, Massachusetts 02454-9110, USA
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144
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Akiba Y, Sasaki H, Saino-Saito S, Baker H. Temporal and Spatial Disparity in cFOS Expression and Dopamine Phenotypic Differentiation in the Neonatal Mouse Olfactory Bulb. Neurochem Res 2006; 32:625-34. [PMID: 16944318 DOI: 10.1007/s11064-006-9134-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2006] [Indexed: 11/29/2022]
Abstract
The mammalian olfactory bulb (OB) is among the few regions in adult brain which generates interneurons. A subpopulation of these phenotypically diverse interneurons is dopaminergic (DA) periglomerular cells. Full phenotypic development as indicated by expression of tyrosine hydroxylase (TH), the first enzyme in DA biosynthesis, requires afferent activity or equivalent depolarizing conditions. To investigate the hypothesis that cFOS regulates TH expression, this study analyzed OB slice cultures obtained from neonatal transgenic mice expressing 9 kb of TH promoter directing expression of green fluorescent protein (TH/GFP). Cultures were depolarized with 50 mM potassium chloride (KCl), the calcium channel blocker, nifedipine (10 microM) with KCl, or an equimolar concentration of sodium chloride (NaCl). Depolarization increased cFOS expression 6-fold peaking at about 3 h. Staining decreased rapidly returning to control, NaCl, levels by 48 h post-stimulation when TH/GFP expression was highest. Nifedipine blocked the increase in TH and cFOS suggesting that similar signal transduction pathways mediate both responses.
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Affiliation(s)
- Yosuke Akiba
- Weill Medical College, Cornell University at the Burke Medical Research Institute, 785 Mamaroneck Avenue, White Plains, NY 10605, USA
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145
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KELLY BB, HEDLUND E, KIM C, ISHIGURO H, ISACSON O, CHIKARAISHI DM, KIM KS, FENG G. A tyrosine hydroxylase-yellow fluorescent protein knock-in reporter system labeling dopaminergic neurons reveals potential regulatory role for the first intron of the rodent tyrosine hydroxylase gene. Neuroscience 2006; 142:343-54. [PMID: 16876957 PMCID: PMC2610443 DOI: 10.1016/j.neuroscience.2006.06.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Revised: 06/14/2006] [Accepted: 06/16/2006] [Indexed: 11/20/2022]
Abstract
Degeneration of the dopaminergic neurons of the substantia nigra is a hallmark of Parkinson's disease. To facilitate the study of the differentiation and maintenance of this population of dopaminergic neurons both in vivo and in vitro, we generated a knock-in reporter line in which the yellow fluorescent protein (YFP) replaced the first exon and the first intron of the tyrosine hydroxylase (TH) gene in one allele by homologous recombination. Expression of YFP under the direct control of the entire endogenous 5' upstream region of the TH gene was predicted to closely match expression of TH from the wild type allele, thus marking functional dopaminergic neurons. We found that YFP was expressed in dopaminergic neurons differentiated in vitro from the knock-in mouse embryonic stem cell line and in dopaminergic brain regions in knock-in mice. Surprisingly, however, YFP expression did not overlap completely with TH expression, and the degree of overlap varied in different TH-expressing brain regions. Thus, the reporter gene did not identify functional TH-expressing cells with complete accuracy. A DNaseI hypersensitivity assay revealed a cluster of hypersensitivity sites in the first intron of the TH gene, which was deleted by insertion of the reporter gene, suggesting that this region may contain cis-acting regulatory sequences. Our results suggest that the first intron of the rodent TH gene may be important for accurate expression of TH.
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Affiliation(s)
- B. B. KELLY
- Department of Neurobiology, Box 3209, Duke University Medical Center, Durham, NC 27710, USA
| | - E. HEDLUND
- Udall Parkinson’s Disease Research Center of Excellence, McLean Hospital/Harvard Medical School, MA 02478, USA
- Molecular Neurobiology Laboratory, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA
- Neuroregeneration Laboratory, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA
| | - C. KIM
- Udall Parkinson’s Disease Research Center of Excellence, McLean Hospital/Harvard Medical School, MA 02478, USA
- Molecular Neurobiology Laboratory, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA
| | - H. ISHIGURO
- Carna Bioscience, KIBC 511, 5-5-2, Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Hyogo, Japan
| | - O. ISACSON
- Udall Parkinson’s Disease Research Center of Excellence, McLean Hospital/Harvard Medical School, MA 02478, USA
- Neuroregeneration Laboratory, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA
| | - D. M. CHIKARAISHI
- Department of Neurobiology, Box 3209, Duke University Medical Center, Durham, NC 27710, USA
| | - K.-S. KIM
- Udall Parkinson’s Disease Research Center of Excellence, McLean Hospital/Harvard Medical School, MA 02478, USA
- Molecular Neurobiology Laboratory, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA
| | - G. FENG
- Department of Neurobiology, Box 3209, Duke University Medical Center, Durham, NC 27710, USA
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
- Correspondence to: G. Feng, Department of Neurobiology, Box 3209, Duke University Medical Center, Durham, NC 27710, USA. Tel: +1-919-668-1657; fax: +1-919-668-1891. E-mail address: (G. Feng)
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146
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Arttamangkul S, Torrecilla M, Kobayashi K, Okano H, Williams JT. Separation of mu-opioid receptor desensitization and internalization: endogenous receptors in primary neuronal cultures. J Neurosci 2006; 26:4118-25. [PMID: 16611829 PMCID: PMC6673897 DOI: 10.1523/jneurosci.0303-06.2006] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A close relationship between desensitization and internalization of mu-opioid receptors (MORs) has been proposed based on differential actions of series of agonists. The role that these two processes have in the development of tolerance and dependence to opioids has been a controversial subject that has been studied in a variety of model systems. Here, we examine desensitization and internalization of endogenous MORs simultaneously in primary cultures of locus ceruleus neurons using fluorescently tagged peptide agonists. With the use of two fluorescent opioid peptides, dermorphin-Bodipy Texas Red and dermorphin-Alexa594 (Derm-A594), desensitization was measured electrophysiologically and trafficking was followed by the accumulation of intracellular fluorescent puncta. Blocking endocytosis with concanavalin A eliminated the accumulation of fluorescent puncta but desensitization induced by Derm-A594 was unaffected. Likewise, after treatment with concanavalin A, there was no change in either desensitization or recovery from desensitization induced by [Met]5enkephalin. The results demonstrate that desensitization and the recovery from desensitization are not dependent on receptor internalization and suggest that the activity of endogenous MORs in primary neurons can be modulated at the level of the plasma membrane.
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147
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Rawal N, Castelo-Branco G, Sousa KM, Kele J, Kobayashi K, Okano H, Arenas E. Dynamic temporal and cell type-specific expression of Wnt signaling components in the developing midbrain. Exp Cell Res 2006; 312:1626-36. [PMID: 16510140 DOI: 10.1016/j.yexcr.2006.01.032] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 01/23/2006] [Accepted: 01/27/2006] [Indexed: 01/09/2023]
Abstract
Wnt1 and -5a have been shown to modulate the proliferation and differentiation of midbrain dopaminergic (DA) neurons. However, it is not known whether other Wnts or which Frizzled (Fz) receptors are expressed in the developing midbrain. We found that 13 out of 19 Wnts, all 10 Fzs, and several intracellular Wnt signaling modulators, including Axin, FRAT, Naked, Par-1, and Ltap are developmentally regulated between embryonic days (E) 10.5 and 15.5. Next, we studied whether Fzs are differentially expressed in different cell types and examined neuronal-progenitor- or glial-enriched cultures and DA neurons isolated from TH-GFP reporter mice. We found that Fz8 is expressed at high levels in DA neurons at E11.5 and E13.5. Fz6 and -7 are the predominant transcripts in glial precursors, and Fz9, which is absent in DA neurons at E11.5, is the main receptor expressed in neuronal precursors. We therefore examined the function of Fz9 in DA cells and found that overexpression of Fz9 reduced Wnt5a- but not Wnt3a-induced hyperphosphorylation of Dishevelled. Thus, our results show that Fzs are developmentally regulated and differentially expressed in VM precursors, DA neurons, and glia. These findings suggest that Fz expression contributes to provide specificity to Wnt-mediated effects.
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Affiliation(s)
- Nina Rawal
- Laboratory of Molecular Neurobiology, Medical Biochemistry and Biophysics, Karolinska Institute, Scheeles väg 1, A1:2, 171 77 Stockholm, Sweden
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148
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Meuer K, Pitzer C, Teismann P, Krüger C, Göricke B, Laage R, Lingor P, Peters K, Schlachetzki JCM, Kobayashi K, Dietz GPH, Weber D, Ferger B, Schäbitz WR, Bach A, Schulz JB, Bähr M, Schneider A, Weishaupt JH. Granulocyte-colony stimulating factor is neuroprotective in a model of Parkinson's disease. J Neurochem 2006; 97:675-86. [PMID: 16573658 DOI: 10.1111/j.1471-4159.2006.03727.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have recently shown that the hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) is neuroprotective in rodent stroke models, and that this action appears to be mediated via a neuronal G-CSF receptor. Here, we report that the G-CSF receptor is expressed in rodent dopaminergic substantia nigra neurons, suggesting that G-CSF might be neuroprotective for dopaminergic neurons and a candidate molecule for the treatment of Parkinson's disease. Thus, we investigated protective effects of G-CSF in 1-methyl-4-phenylpyridinium (MPP+)-challenged PC12 cells and primary neuronal midbrain cultures, as well as in the mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson's disease. Substantial protection was found against MPP+-induced dopaminergic cell death in vitro. Moreover, subcutaneous application of G-CSF at a dose of 40 microg/Kg body weight daily over 13 days rescued dopaminergic substantia nigra neurons from MPTP-induced death in aged mice, as shown by quantification of tyrosine hydroxylase-positive substantia nigra cells. Using HPLC, a corresponding reduction in striatal dopamine depletion after MPTP application was observed in G-CSF-treated mice. Thus our data suggest that G-CSF is a novel therapeutic opportunity for the treatment of Parkinson's disease, because it is well-tolerated and already approved for the treatment of neutropenic conditions in humans.
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MESH Headings
- 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine
- 3,4-Dihydroxyphenylacetic Acid/metabolism
- Animals
- Blotting, Northern/methods
- Brain/cytology
- Brain/drug effects
- Brain/metabolism
- Cell Count/methods
- Cells, Cultured
- Chromatography, High Pressure Liquid/methods
- Disease Models, Animal
- Dopamine/metabolism
- Embryo, Mammalian
- Gene Expression/drug effects
- Gene Expression/physiology
- Granulocyte Colony-Stimulating Factor/therapeutic use
- Green Fluorescent Proteins
- Homovanillic Acid/metabolism
- Immunohistochemistry/methods
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Neurons/drug effects
- Neurons/metabolism
- Neuroprotective Agents/therapeutic use
- Parkinsonian Disorders/chemically induced
- Parkinsonian Disorders/prevention & control
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Receptors, Granulocyte Colony-Stimulating Factor/genetics
- Receptors, Granulocyte Colony-Stimulating Factor/metabolism
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Transfection/methods
- Tyrosine 3-Monooxygenase/metabolism
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Affiliation(s)
- Katrin Meuer
- Department of Neurology, University of Göttingen, Waldweg 33, 37073 Göttingen, Germany
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149
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Sasaki H, Berlin R, Baker H. Transient expression of tyrosine hydroxylase promoter/reporter gene constructs in the olfactory epithelium of transgenic mice. ACTA ACUST UNITED AC 2005; 33:681-92. [PMID: 16217623 DOI: 10.1007/s11068-005-3336-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2005] [Revised: 03/16/2005] [Accepted: 05/17/2005] [Indexed: 11/29/2022]
Abstract
Maturation and survival of olfactory receptor neurons (ORNs) are hypothesized to depend on trophic support from the olfactory bulb during both development and regeneration of the olfactory epithelium (OE). The current study characterized transgene expression in two independently derived transgenic mouse lines in which 9 kb of tyrosine hydroxylase (TH) promoter was utilized to drive either enhanced green fluorescent protein (TH/eGFP) or LacZ (TH/beta-gal) reporters. Transgene expression, found primarily on dorsal aspects of the OE, the dorsal septum and endoturbinate II, resembled the Zone one distribution of olfactory receptor genes. Labeled cells were ovoid to fusiform with dendrites that projected to the epithelial surface but only rarely exhibited discernable cilia. Axons were short and did not extend beyond the basal lamina. As only a subpopulation of the cells contained olfactory marker protein, indicative of ORN maturation, the transgene expressing cells were likely immature neuronal precursors. Demonstration of transgene expression without either TH mRNA or protein was consistent with low basal level transcriptional activity of endogenous TH that may reflect differences between TH and reporter protein stability. Molecules identifying specific olfactory-derived cell populations, PDE2 and LHRH, also did not co-localize with either reporter. A higher than predicted proportion of apoptotic neonatal transgene-expressing cells accounted for their apparent paucity in adult mice. These studies support the concept that transgene expressing cells exhibiting morphological and biochemical characteristics of presumptive ORNs are unable to mature and undergo apoptotic cell death possibly because they lack trophic support.
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Affiliation(s)
- Hayato Sasaki
- Weill Medical College, Cornell University, The Burke Medical Research Institute, White Plains, New York 10605, USA
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Baier PC, Schindehütte J, Thinyane K, Flügge G, Fuchs E, Mansouri A, Paulus W, Gruss P, Trenkwalder C. Behavioral changes in unilaterally 6-hydroxy-dopamine lesioned rats after transplantation of differentiated mouse embryonic stem cells without morphological integration. Stem Cells 2005; 22:396-404. [PMID: 15153616 DOI: 10.1634/stemcells.22-3-396] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Transplantation of fetal mesencephalic cells into the striatum has been performed in about 350 patients with Parkinson's disease and has been intensively studied in rat models of Parkinson's disease. Limited access to this material has shifted the focus toward embryonic stem (ES) cells. The grafting of undifferentiated ES cells to 6-hydroxy-dopamine (6-OHDA)-lesioned rats leads to behavioral improvements but may induce teratoma-like structures. This risk might be avoided by using more differentiated ES cells. In this study, we aimed to investigate differentiated mouse ES cells regarding their in vivo development and fate after transplantation in the striatum in the 6-OHDA rat model and the behavioral changes induced after transplantation. METHODS Mouse ES cells were differentiated on PA6 feeder cells for 14 days before grafting. Twenty to twenty-five percent of the neurons obtained were positive for tyrosine-hydroxylase (TH). PKH26-labeled cells were transplanted in the striata of unilaterally 6-OHDA-lesioned rats. RESULTS Direct PKH26 fluorescence visualization and TH staining proved the existence of cell deposits in the striata of all grafted animals, indicating cell survival for at least 5 weeks posttransplantation. There was no evidence of tumor formation. Immunocytochemical staining showed glial immunoreactivity surrounding the grafted cell deposits, probably inhibiting axonal outgrowth into the surrounding host tissue. There was a significant reduction in amphetamine-induced rotational behavior seen in grafted animals, which was not observed in sham-operated animals. CONCLUSIONS The findings of this study suggest that the amphetamine-induced rotational behavioral test without histological confirmation is not proof of morphological integration with axonal outgrowth within the first 4 weeks posttransplantation.
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Affiliation(s)
- Paul Christian Baier
- Department of Clinical Neurophysiology, Georg-August University Göttingen, Göttingen, Germany.
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