Sodium Phenylbutyrate Controls Neuroinflammatory and Antioxidant Activities and Protects Dopaminergic Neurons in Mouse Models of Parkinson’s Disease

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Jana, Arundhati; Liu, Xiaojuan; Brahmachari, Saurav; Gendelman, Howard E.; Pahan, Kalipada

2012-01-01

Neuroinflammation and oxidative stress underlie the pathogenesis of various neurodegenerative disorders. Here we demonstrate that sodium phenylbutyrate (NaPB), an FDA-approved therapy for reducing plasma ammonia and glutamine in urea cycle disorders, can suppress both proinflammatory molecules and reactive oxygen species (ROS) in activated glial cells. Interestingly, NaPB also decreased the level of cholesterol but involved only intermediates, not the end product of cholesterol biosynthesis pathway for these functions. While inhibitors of both geranylgeranyl transferase (GGTI) and farnesyl transferase (FTI) inhibited the activation of NF-κB, inhibitor of GGTI, but not FTI, suppressed the production of ROS. Accordingly, a dominant-negative mutant of p21rac, but not p21ras, attenuated the production of ROS from activated microglia. Inhibition of both p21ras and p21rac activation by NaPB in microglial cells suggests that NaPB exerts anti-inflammatory and antioxidative effects via inhibition of these small G proteins. Consistently, we found activation of both p21ras and p21rac in vivo in the substantia nigra of acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson’s disease. Oral administration of NaPB reduced nigral activation of p21ras and p21rac, protected nigral reduced glutathione, attenuated nigral activation of NF-κB, inhibited nigral expression of proinflammatory molecules, and suppressed nigral activation of glial cells. These findings paralleled dopaminergic neuronal protection, normalized striatal neurotransmitters, and improved motor functions in MPTP-intoxicated mice. Consistently, FTI and GGTI also protected nigrostriata in MPTP-intoxicated mice. Furthermore, NaPB also halted the disease progression in a chronic MPTP mouse model. These results identify novel mode of action of NaPB and suggest that NaPB may be of therapeutic benefit for neurodegenerative disorders. PMID:22723850

Attenuation of 6-hydroxydopamine-induced dopaminergic nigrostriatal lesions in superoxide dismutase transgenic mice

International Nuclear Information System (INIS)

Cadet, J.L.; Hirata, H.; Asanuma, M.

1998-01-01

6-Hydroxydopamine is a neurotoxin that produces degeneration of the nigrostriatal dopaminergic pathway in rodents. Its toxicity is thought to involve the generation of superoxide anion secondary to its autoxidation. To examine the effects of the overexpression of Cu,Zn-superoxide dismutase activity on 6-hydroxydopamine-induced dopaminergic neuronal damage, we have measured the effects of 6-hydroxydopamine on striatal and nigral dopamine transporters and nigral tyrosine hydroxylase-immunoreactive neurons in Cu,Zn-superoxide dismutase transgenic mice. Intracerebroventricular injection of 6-hydroxydopamine (50 μg) in non-transgenic mice produced reductions in the size of striatal area and an enlargement of the cerebral ventricle on both sides of the brains of mice killed two weeks after the injection. In addition, 6-hydroxydopamine caused marked decreases in striatal and nigral [ 125 I]RTI-121-labelled dopamine transporters not only on the injected side but also on the non-injected side of non-transgenic mice; this was associated with decreased cell number and size of tyrosine hydroxylase-immunoreactive dopamine neurons in the substantia nigra pars compacta on both sides in these mice. In contrast, superoxide dismutase transgenic mice were protected against these neurotoxic effects of 6-hydroxydopamine, with the homozygous transgenic mice showing almost complete protection.These results provide further support for a role of superoxide anion in the toxic effects of 6-hydroxydopamine. They also provide further evidence that reactive oxygen species may be the main determining factors in the neurodegenerative effects of catecholamines. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Physiological characterisation of human iPS-derived dopaminergic neurons.

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Elizabeth M Hartfield

Full Text Available Human induced pluripotent stem cells (hiPSCs offer the potential to study otherwise inaccessible cell types. Critical to this is the directed differentiation of hiPSCs into functional cell lineages. This is of particular relevance to research into neurological disease, such as Parkinson's disease (PD, in which midbrain dopaminergic neurons degenerate during disease progression but are unobtainable until post-mortem. Here we report a detailed study into the physiological maturation over time of human dopaminergic neurons in vitro. We first generated and differentiated hiPSC lines into midbrain dopaminergic neurons and performed a comprehensive characterisation to confirm dopaminergic functionality by demonstrating dopamine synthesis, release, and re-uptake. The neuronal cultures include cells positive for both tyrosine hydroxylase (TH and G protein-activated inward rectifier potassium channel 2 (Kir3.2, henceforth referred to as GIRK2, representative of the A9 population of substantia nigra pars compacta (SNc neurons vulnerable in PD. We observed for the first time the maturation of the slow autonomous pace-making (<10 Hz and spontaneous synaptic activity typical of mature SNc dopaminergic neurons using a combination of calcium imaging and electrophysiology. hiPSC-derived neurons exhibited inositol tri-phosphate (IP3 receptor-dependent release of intracellular calcium from the endoplasmic reticulum in neuronal processes as calcium waves propagating from apical and distal dendrites, and in the soma. Finally, neurons were susceptible to the dopamine neuron-specific toxin 1-methyl-4-phenylpyridinium (MPP+ which reduced mitochondrial membrane potential and altered mitochondrial morphology. Mature hiPSC-derived dopaminergic neurons provide a neurophysiologically-defined model of previously inaccessible vulnerable SNc dopaminergic neurons to bridge the gap between clinical PD and animal models.

Tetrahydrobiopterin precursor sepiapterin provides protection against neurotoxicity of 1-methyl-4-phenylpyridinium in nigral slice cultures

DEFF Research Database (Denmark)

Madsen, Jakob Torp; Jansen, Pernille; Hesslinger, Christian

2003-01-01

Complex-I inhibition and oxidative processes have been implicated in the loss of nigral dopamine neurones in Parkinson's disease and the toxicity of MPTP and its metabolite MPP+. Tetrahydrobiopterin, an essential cofactor for tyrosine hydroxylase, may act as an antioxidant in dopaminergic neurones...... and protects against the toxic consequences of glutathione depletion. Here we studied the effects of manipulating tetrahydrobiopterin levels on MPP+ toxicity in organotypic, rat ventral mesencephalic slice cultures. In cultures exposed to 30 micro m MPP+ for 2 days, followed by 8 days 'recovery' in control...... medium, we measured dopamine and its metabolites in the tissue and culture medium by HPLC, lactate dehydrogenase release to the culture medium, cellular uptake of propidium iodide and counted the tyrosine hydroxylase-immunoreactive neurones. Inhibition of tetrahydrobiopterin synthesis by 2,4-diamino-6...

Role of Inflammation in MPTP-Induced Dopaminergic Neuronal Death

Science.gov (United States)

2008-12-01

of MPTP to MPP+ and MPP+ entry into dopaminergic neurons are key to the neurotoxic effects of MPTP and interference in any of these processes...presented at the Society for Neuroscience Meetings in 2006 Figure 1. Tempol Structure 29 Figure 2. Tempol protects dopaminergic neurons...in PD. Dopaminergic neurons in the SNpc were protected to a significant degree against the damaging effects of MPTP by M40401 whereas its isoforms

Epigallocatechin gallate protects dopaminergic neurons against 1-methyl-4- phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity by inhibiting microglial cell activation.

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Li, Rui; Peng, Ning; Du, Fang; Li, Xu-ping; Le, Wei-dong

2006-04-01

To observe whether the dopaminergic neuroprotective effect of (-)-epigallocatechin gallate (EGCG) is associated with its inhibition of microglial cell activation in vivo. The effects of EGCG at different doses on dopaminergic neuronal survival were tested in a methyl-4-phenyl-pyridinium (MPP+)-induced dopaminergic neuronal injury model in the primary mesencephalic cell cultures. With unbiased stereological method, tyrosine hydroxylase-immunoreactive (TH-ir) cells were counted in the A8, A9 and A10 regions of the substantia nigra (SN) in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated C57BL/6 mice. The effect of EGCG on microglial activation in the SN was also investigated. Pretreatment with EGCG (1 to 100 micromol/L) significantly attenuated MPP+-induced TH-ir cell loss by 22.2% to 80.5% in the mesencephalic cell cultures. In MPTP-treated C57BL/6 mice, EGCG at a low concentration (1 mg/kg) provided significant protection against MPTP-induced TH-ir cell loss by 50.9% in the whole nigral area and by 71.7% in the A9 region. EGCG at 5 mg/kg showed more prominent protective effect than at 1 or 10 mg/kg. EGCG pretreatment significantly inhibited microglial activation and CD11b expression induced by MPTP. EGCG exerts potent dopaminergic neuroprotective activity by means of microglial inhibition, which shed light on the potential use of EGCG in treatment of Parkinson's disease.

Identification of the endogenous key substrates of the human organic cation transporter OCT2 and their implication in function of dopaminergic neurons.

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Dirk Taubert

Full Text Available BACKGROUND: The etiology of neurodegenerative disorders, such as the accelerated loss of dopaminergic neurons in Parkinson's disease, is unclear. Current hypotheses suggest an abnormal function of the neuronal sodium-dependent dopamine transporter DAT to contribute to cell death in the dopaminergic system, but it has not been investigated whether sodium-independent amine transporters are implicated in the pathogenesis of Parkinson's disease. METHODOLOGY/PRINCIPAL FINDINGS: By the use of a novel tandem-mass spectrometry-based substrate search technique, we have shown that the dopaminergic neuromodulators histidyl-proline diketopiperazine (cyclo(his-pro and salsolinol were the endogenous key substrates of the sodium-independent organic cation transporter OCT2. Quantitative real-time mRNA expression analysis revealed that OCT2 in contrast to its related transporters was preferentially expressed in the dopaminergic regions of the substantia nigra where it colocalized with DAT and tyrosine hydroxylase. By assessing cell viability with the MTT reduction assay, we found that salsolinol exhibited a selective toxicity toward OCT2-expressing cells that was prevented by cyclo(his-pro. A frequent genetic variant of OCT2 with the amino acid substitution R400C reduced the transport efficiency for the cytoprotective cyclo(his-pro and thereby increased the susceptibility to salsolinol-induced cell death. CONCLUSIONS/SIGNIFICANCE: Our findings indicate that the OCT2-regulated interplay between cyclo(his-pro and salsolinol is crucial for nigral cell integrity and that a shift in transport efficiency may impact the risk of Parkinson's disease.

Dose-dependent striatal changes in dopaminergic terminals and alpha-synuclein reactivity in a porcine model of progressive Parkinson’s disease

DEFF Research Database (Denmark)

Nielsen, Mette Slot; Glud, Andreas Nørgaard; Møller, Arne

2011-01-01

to discover effective compounds halting PD progression have so far failed in clinical trials, perhaps because current animal models do not imitate the neuropathological progression of PD well enough. We recently established a progressive large animal PD model in Göttingen minipigs based on chronic infusion......Parkinson disease (PD) is a common neurodegenerative disorder, resulting from a progressive dopaminergic neuron loss in the substantia nigra (SN). Alpha-synuclein positive neuronal inclusion bodies and progressive loss of dopaminergic striatal terminals is also well described in PD. Attempts...... the SN were paraffin embedded and immunohistochemically stained for tyrosine hydroxylase (TH) and alpha-synuclein. Stereological examination of the SN showed progressive nigral neuron loss with increased MPTP dosages. Occasional neuronal staining confined to the cytoplasm and cell membrane was observed...

Dopaminergic neurons encode a distributed, asymmetric representation of temperature in Drosophila.

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Tomchik, Seth M

2013-01-30

Dopaminergic circuits modulate a wide variety of innate and learned behaviors in animals, including olfactory associative learning, arousal, and temperature-preference behavior. It is not known whether distinct or overlapping sets of dopaminergic neurons modulate these behaviors. Here, I have functionally characterized the dopaminergic circuits innervating the Drosophila mushroom body with in vivo calcium imaging and conditional silencing of genetically defined subsets of neurons. Distinct subsets of PPL1 dopaminergic neurons innervating the vertical lobes of the mushroom body responded to decreases in temperature, but not increases, with rapidly adapting bursts of activity. PAM neurons innervating the horizontal lobes did not respond to temperature shifts. Ablation of the antennae and maxillary palps reduced, but did not eliminate, the responses. Genetic silencing of dopaminergic neurons innervating the vertical mushroom body lobes substantially reduced behavioral cold avoidance, but silencing smaller subsets of these neurons had no effect. These data demonstrate that overlapping dopaminergic circuits encode a broadly distributed, asymmetric representation of temperature that overlays regions implicated previously in learning, memory, and forgetting. Thus, diverse behaviors engage overlapping sets of dopaminergic neurons that encode multimodal stimuli and innervate a single anatomical target, the mushroom body.

p73 gene in dopaminergic neurons is highly susceptible to manganese neurotoxicity.

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Kim, Dong-Suk; Jin, Huajun; Anantharam, Vellareddy; Gordon, Richard; Kanthasamy, Arthi; Kanthasamy, Anumantha G

2017-03-01

Chronic exposure to elevated levels of manganese (Mn) has been linked to a Parkinsonian-like movement disorder, resulting from dysfunction of the extrapyramidal motor system within the basal ganglia. However, the exact cellular and molecular mechanisms of Mn-induced neurotoxicity remain elusive. In this study, we treated C57BL/6J mice with 30mg/kg Mn via oral gavage for 30 days. Interestingly, in nigral tissues of Mn-exposed mice, we found a significant downregulation of the truncated isoform of p73 protein at the N-terminus (ΔNp73). To further determine the functional role of Mn-induced p73 downregulation in Mn neurotoxicity, we examined the interrelationship between the effect of Mn on p73 gene expression and apoptotic cell death in an N27 dopaminergic neuronal model. Consistent with our animal study, 300μM Mn treatment significantly suppressed p73 mRNA expression in N27 dopaminergic cells. We further determined that protein levels of the ΔNp73 isoform was also reduced in Mn-treated N27 cells and primary striatal cultures. Furthermore, overexpression of ΔNp73 conferred modest cellular protection against Mn-induced neurotoxicity. Taken together, our results demonstrate that Mn exposure downregulates p73 gene expression resulting in enhanced susceptibility to apoptotic cell death. Thus, further characterization of the cellular mechanism underlying p73 gene downregulation will improve our understanding of the molecular underpinnings of Mn neurotoxicity. Copyright © 2016 Elsevier B.V. All rights reserved.

Sweet taste and nutrient value subdivide rewarding dopaminergic neurons in Drosophila.

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Huetteroth, Wolf; Perisse, Emmanuel; Lin, Suewei; Klappenbach, Martín; Burke, Christopher; Waddell, Scott

2015-03-16

Dopaminergic neurons provide reward learning signals in mammals and insects [1-4]. Recent work in Drosophila has demonstrated that water-reinforcing dopaminergic neurons are different to those for nutritious sugars [5]. Here, we tested whether the sweet taste and nutrient properties of sugar reinforcement further subdivide the fly reward system. We found that dopaminergic neurons expressing the OAMB octopamine receptor [6] specifically convey the short-term reinforcing effects of sweet taste [4]. These dopaminergic neurons project to the β'2 and γ4 regions of the mushroom body lobes. In contrast, nutrient-dependent long-term memory requires different dopaminergic neurons that project to the γ5b regions, and it can be artificially reinforced by those projecting to the β lobe and adjacent α1 region. Surprisingly, whereas artificial implantation and expression of short-term memory occur in satiated flies, formation and expression of artificial long-term memory require flies to be hungry. These studies suggest that short-term and long-term sugar memories have different physiological constraints. They also demonstrate further functional heterogeneity within the rewarding dopaminergic neuron population. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Sweet Taste and Nutrient Value Subdivide Rewarding Dopaminergic Neurons in Drosophila

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Huetteroth, Wolf; Perisse, Emmanuel; Lin, Suewei; Klappenbach, Mart?n; Burke, Christopher; Waddell, Scott

2015-01-01

Dopaminergic neurons provide reward learning signals in mammals and insects. Recent work in Drosophila has demonstrated that water-reinforcing dopaminergic neurons are different to those for nutritious sugars. Here, we tested whether the sweet taste and nutrient properties of sugar reinforcement further subdivide the fly reward system. We found that dopaminergic neurons expressing the OAMB octopamine receptor specifically convey the short-term reinforcing effects of sweet taste. These dopamin...

Human neuromelanin: an endogenous microglial activator for dopaminergic neuron death

OpenAIRE

Zhang, Wei; Zecca, Luigi; Wilson, Belinda; Ren, RW; Wang, Yong-jun; Wang, Xiao-min; Hong, Jau-Shyong

2013-01-01

Substantial evidence indicates that neuroinflammation caused by over-activation of microglial in the substantia nigra is critical in the pathogenesis of dopaminergic neurodegeneration in Parkinson’s disease (PD). Increasing data demonstrates that environmental factors such as rotenone, paraquat play pivotal roles in the death of dopaminergic neurons. Here, potential role and mechanism of neuromelanin (NM), a major endogenous component in dopaminergic neurons of the substantia nigra, on microg...

Examination of the presynaptic dopaminergic system using positron emission tomography in a family with autosomal dominant parkinsonism and dementia due to pallido-ponto-nigral degeneration (PPNO)

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Cordes, M. [Neurodegenerative Disorders Centre, Univ. of British Columbia, Vancouver, BC (Canada)]|[Strahlenklinik und Poliklinik, Universitaetsklinikum Rudolf Virchow, Freie Univ. Berlin (Germany); Wszolek, Z.K. [Neurodegenerative Disorders Centre, Univ. of British Columbia, Vancouver, BC (Canada)]|[Section of Neurology, Univ. of Nebraska Medical Center, Omaha, NE (United States); Pfeiffer, R.F. [Section of Neurology, Univ. of Nebraska Medical Center, Omaha, NE (United States); Calne, D.B. [Neurodegenerative Disorders Centre, Univ. of British Columbia, Vancouver, BC (Canada)

1993-12-31

We report positron emission tomography (PET) examinations of presynaptic nigrostriatal dopaminergic function in a large family with an autosomal dominant neuro-degenerative disorder characterized pathologically by pallido-ponto-nigral degeneration, and clinically by parkinsonism, dystonia, paresis of conjugate gaze, apraxia of eyelid opening and closing, pyramidal tract dysfunction, and urinary incontinence. Dopaminergic function was studied and quantified with [{sup 18}F]-L-6-fluorodopa (6 FD) and PET in five affected patients, 13 individuals at-risk, and 15 similarly aged controls. The rate constant K{sub i} (mL/striatum/min) for 6 FD was decreased in all patients. None of the individuals at risk had reduced 6 FD uptake. In fact, three of them had increased values. Repeat scans have revealed a fall in 6 FD uptake in two out of the three with initially high constants. This may reflect a preclinical stage of involvement, but longer observation is necessary. (orig.) [Deutsch] Wir berichten ueber Untersuchungen der praesynaptischen dopaminergen Funktion mit der Positronenemissionstomographie bei einer grossen Familie mit autosomal-dominant vererbtem Parkinsonismus und Demenz. Die Erkrankung ist pathologisch-anatomisch gekennzeichnet durch eine pallido-ponto-nigrale Degeneration. Klinisch bestehen ein Parkinsonismus, Dystonien, eine Apraxie der Augenoeffnung und -schliessung, pyramidale Dysfunktionen und eine Harninkontinenz. Die praesynaptische dopaminerge Funktion wurde untersucht und quantifiziert mittels [{sup 18}F]-L-6-Fluorodopa (6FD) PET bei fuenf erkrankten Patienten, 13 Risikopatienten und 15 Kontrollpersonen vergleichbaren Alters. Die Transportkonstante K{sub i} (ml/Striatum/min) fuer die striatale Aufnahme des Radiotracers war bei allen erkrankten Patienten erniedrigt. Von den 13 Risikopatienten hatte keiner eine reduzierte Aufnahme von 6FD. Drei Risikopatienten zeigten sogar Werte fuer K{sub i}, die oberhalb des Referenzbereiches der Kontrollpersonen lagen

Chronic Hypergravity Induces Changes in the Dopaminergic Neuronal System in Drosophila Melanogaster

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Pelos, Andrew; Hosamani, Ravikumar; Bhattacharya, Sharmila

2017-01-01

Upon atmospheric exitre-entry and during training, astronauts are subjected to temporary periods of hypergravity, which has been implicated in the activation of oxidative stress pathways contributing to mitochondrial dysfunction and neuronal degeneration. The pathogenesis of Parkinsons disease and other neurodegenerative disorders is associated with oxidative damage to neurons involved in dopamine systems of the brain. Our study aims to examine the effects of a hypergravitational developmental environment on the degeneration of dopaminergic systems in Drosophila melanogaster. Male and female flies (Gal4-UAS transgenic line) were hatched and raised to adulthood in centrifugal hypergravity (97rpm, 3g). The nuclear expression of the reporter, Green Fluorescent Protein (GFP) is driven by the dopaminergic enzyme tyrosine hydroxylase (TH) promoter, allowing for the targeted visualization of dopamine producing neurons. After being raised to adulthood and kept in hypergravity until 18 days of age, flies were dissected and the expression of TH was measured by fluorescence confocal microscopy. TH expression in the fly brains was used to obtain counts of healthy dopaminergic neurons for flies raised in chronic hypergravity and control groups. Dopaminergic neuron expression data were compared with those of previous studies that limited hypergravity exposure to late life in order to determine the flies adaptability to the gravitational environment when raised from hatching through adulthood. Overall, we observed a significant effect of chronic hypergravity exposure contributing to deficits in dopaminergic neuron expression (p 0.003). Flies raised in 3g had on average lower dopaminergic neuron counts (mean 97.7) when compared with flies raised in 1g (mean 122.8). We suspect these lower levels of TH expression are a result of oxidative dopaminergic cell loss in flies raised in hypergravity. In future studies, we hope to further elucidate the mechanism by which hypergravity

Effects of Chronic Hypergravity on the Dopaminergic Neuronal System in Drosophila Melanogaster

Science.gov (United States)

Pelos, Andrew; Hosamani, Ravikumar; Bhattacharya, Sharmila

2017-01-01

Upon atmospheric exitre-entry and during training, astronauts are subjected to temporary periods of hypergravity, which has been implicated in the activation of oxidative stress pathways contributing to mitochondrial dysfunction and neuronal degeneration. The pathogenesis of Parkinsons disease and other neurodegenerative disorders is associated with oxidative damage to neurons involved in dopamine systems of the brain. Our study aims to examine the effects of a hypergravitational developmental environment on the degeneration of dopaminergic systems in Drosophila melanogaster. Male and female flies (Gal4-UAS transgenic line) were hatched and raised to adulthood in centrifugal hypergravity (97rpm, 3g). The nuclear expression of the reporter, Green Fluorescent Protein (GFP) is driven by the dopaminergic enzyme tyrosine hydroxylase (TH) promoter, allowing for the targeted visualization of dopamine producing neurons. After being raised to adulthood and kept in hypergravity until 18 days of age, flies were dissected and the expression of TH was measured by fluorescence confocal microscopy. TH expression in the fly brains was used to obtain counts of healthy dopaminergic neurons for flies raised in chronic hypergravity and control groups. Dopaminergic neuron expression data were compared with those of previous studies that limited hypergravity exposure to late life in order to determine the flies adaptability to the gravitational environment when raised from hatching through adulthood. Overall, we observed a significant effect of chronic hypergravity exposure contributing to deficits in dopaminergic neuron expression (p 0.003). Flies raised in 3g had on average lower dopaminergic neuron counts (mean 97.7) when compared with flies raised in 1g (mean 122.8). We suspect these lower levels of TH expression are a result of oxidative dopaminergic cell loss in flies raised in hypergravity. In future studies, we hope to further elucidate the mechanism by which hypergravity

Do Substantia Nigra Dopaminergic Neurons Differentiate Between Reward and Punishment?

Institute of Scientific and Technical Information of China (English)

Michael J. Frank; D. James Surmeier

2009-01-01

The activity of dopaminergic neurons are thought to be increased by stimuli that predict reward and decreased by stimuli that predict aversive outcomes. Recent work by Matsumoto and Hikosaka challenges this model by asserting that stimuli associated with either rewarding or aversive outcomes increase the activity of dopaminergic neurons in the substantia nigra pars compacta.

Representation of spontaneous movement by dopaminergic neurons is cell-type selective and disrupted in parkinsonism

DEFF Research Database (Denmark)

Dodson, Paul D.; Dreyer, Jakob K.; Jennings, Katie Ann

2016-01-01

receptor expressed by striatal neurons. Importantly, in aged mice harboring a genetic burden relevant for human Parkinson's disease, the precise movement-related firing of SNc dopaminergic neurons and the resultant striatal dopamine signaling were lost. These data show that distinct dopaminergic cell types......Midbrain dopaminergic neurons are essential for appropriate voluntary movement, as epitomized by the cardinal motor impairments arising in Parkinson's disease. Understanding the basis of such motor control requires understanding how the firing of different types of dopaminergic neuron relates...... of these dopaminergic neurons can manifest as rapid and robust fluctuations in striatal dopamine concentration and receptor activity. The exact nature of the movement-related signaling in the striatum depended on the type of dopaminergic neuron providing inputs, the striatal region innervated, and the type of dopamine...

Protection but maintained dysfunction of nigral dopaminergic nerve cell bodies and striatal dopaminergic terminals in MPTP-lesioned mice after acute treatment with the mGluR5 antagonist MPEP.

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Aguirre, Jose A; Kehr, Jan; Yoshitake, Takashi; Liu, Fang-Ling; Rivera, Alicia; Fernandez-Espinola, Sergio; Andbjer, Beth; Leo, Giuseppina; Medhurst, Andrew D; Agnati, Luigi F; Fuxe, Kjell

2005-02-08

The mGluR5 antagonist MPEP was used to study the role of mGluR5 in MPTP-induced injury of the nigrostriatal DA neurons. The findings indicate that acute blockade of mGluR5 may result in neuroprotective actions against MPTP neurotoxicity on nigral DA cell bodies and striatal DA terminals using stereological analysis of TH immunoreactivity and microdensitometry. Biochemical analysis showed no restoration of DA levels and metabolism indicating a maintained reduction of DA transmission.

miR-34b/c Regulates Wnt1 and Enhances Mesencephalic Dopaminergic Neuron Differentiation

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Roberto De Gregorio

2018-04-01

Full Text Available Summary: The differentiation of dopaminergic neurons requires concerted action of morphogens and transcription factors acting in a precise and well-defined time window. Very little is known about the potential role of microRNA in these events. By performing a microRNA-mRNA paired microarray screening, we identified miR-34b/c among the most upregulated microRNAs during dopaminergic differentiation. Interestingly, miR-34b/c modulates Wnt1 expression, promotes cell cycle exit, and induces dopaminergic differentiation. When combined with transcription factors ASCL1 and NURR1, miR-34b/c doubled the yield of transdifferentiated fibroblasts into dopaminergic neurons. Induced dopaminergic (iDA cells synthesize dopamine and show spontaneous electrical activity, reversibly blocked by tetrodotoxin, consistent with the electrophysiological properties featured by brain dopaminergic neurons. Our findings point to a role for miR-34b/c in neuronal commitment and highlight the potential of exploiting its synergy with key transcription factors in enhancing in vitro generation of dopaminergic neurons. : In this article, Bellenchi and colleagues show that the microRNA miR-34b/c is expressed in FACS-purified Pitx3-GFP+ neurons and promotes dopaminergic differentiation by negative modulating Wnt1 and the downstream WNT signaling pathway. Induced dopaminergic cells, expressing miR-34b/c, synthesize dopamine and show the electrophysiological properties featured by brain dopaminergic neurons. Keywords: microRNA, dopamine, mESC, miR34b/c, epiSC, transdifferentiation, Wnt1, Wnt pathway, reprogramming

CALBINDIN CONTENT AND DIFFERENTIAL VULNERABILITY OF MIDBRAIN EFFERENT DOPAMINERGIC NEURONS IN MACAQUES

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Iria G Dopeso-Reyes

2014-12-01

Full Text Available Calbindin (CB is a calcium binding protein reported to protect dopaminergic neurons from degeneration. Although a direct link between CB content and differential vulnerability of dopaminergic neurons has long been accepted, factors other than CB have also been suggested, particularly those related to the dopamine transporter. Indeed, several studies have reported that CB levels are not causally related to the differential vulnerability of dopaminergic neurons against neurotoxins. Here we have used dual stains for tyrosine hydroxylase (TH and CB in 3 control and 3 MPTP-treated monkeys to visualize dopaminergic neurons in the ventral tegmental area (VTA and in the dorsal and ventral tiers of the substantia nigra pars compacta (SNcd and SNcv co-expressing TH and CB. In control animals, the highest percentages of co-localization were found in VTA (58.2%, followed by neurons located in the SNcd (34.7%. As expected, SNcv neurons lacked CB expression. In MPTP-treated animals, the percentage of CB-ir/TH-ir neurons in the VTA was similar to control monkeys (62.1%, whereas most of the few surviving neurons in the SNcd were CB-ir/TH-ir (88.6%. Next, we have elucidated the presence of CB within identified nigrostriatal and nigroextrastriatal midbrain dopaminergic projection neurons. For this purpose, two control monkeys received one injection of Fluoro-Gold into the caudate nucleus and one injection of cholera toxin (CTB into the postcommissural putamen, whereas two more monkeys were injected with CTB into the internal division of the globus pallidus. As expected, all the nigrocaudate- and nigroputamen-projecting neurons were TH-ir, although surprisingly, all of these nigrostriatal-projecting neurons were negative for CB. Furthermore, all the nigropallidal-projecting neurons co-expressed both TH and CB. In summary, although CB-ir dopaminergic neurons seem to be less prone to MPTP-induced degeneration, our data clearly demonstrated that these neurons are not

Examination of the presynaptic dopaminergic system using positron emission tomography in a family with autosomal dominant parkinsonism and dementia due to pallido-ponto-nigral degeneration (PPNO)

International Nuclear Information System (INIS)

Cordes, M.; Wszolek, Z.K.; Pfeiffer, R.F.; Calne, D.B.

1993-01-01

We report positron emission tomography (PET) examinations of presynaptic nigrostriatal dopaminergic function in a large family with an autosomal dominant neuro-degenerative disorder characterized pathologically by pallido-ponto-nigral degeneration, and clinically by parkinsonism, dystonia, paresis of conjugate gaze, apraxia of eyelid opening and closing, pyramidal tract dysfunction, and urinary incontinence. Dopaminergic function was studied and quantified with [ 18 F[-L-6-fluorodopa (6 FD) and PET in five affected patients, 13 individuals at-risk, and 15 similarly aged controls. The rate constant K i (mL/striatum/min) for 6 FD was decreased in all patients. None of the individuals at risk had reduced 6 FD uptake. In fact, three of them had increased values. Repeat scans have revealed a fall in 6 FD uptake in two out of the three with initially high constants. This may reflect a preclinical stage of involvement, but longer observation is necessary. (orig.) [de

Vulnerability to glutamate toxicity of dopaminergic neurons is dependent on endogenous dopamine and MAPK activation.

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Izumi, Yasuhiko; Yamamoto, Noriyuki; Matsuo, Takaaki; Wakita, Seiko; Takeuchi, Hiroki; Kume, Toshiaki; Katsuki, Hiroshi; Sawada, Hideyuki; Akaike, Akinori

2009-07-01

Dopaminergic neurons are more vulnerable than other types of neurons in cases of Parkinson disease and ischemic brain disease. An increasing amount of evidence suggests that endogenous dopamine plays a role in the vulnerability of dopaminergic neurons. Although glutamate toxicity contributes to the pathogenesis of these disorders, the sensitivity of dopaminergic neurons to glutamate toxicity has not been clarified. In this study, we demonstrated that dopaminergic neurons were preferentially affected by glutamate toxicity in rat mesencephalic cultures. Glutamate toxicity in dopaminergic neurons was blocked by inhibiting extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase, and p38 MAPK. Furthermore, depletion of dopamine by alpha-methyl-dl-p-tyrosine methyl ester (alpha-MT), an inhibitor of tyrosine hydroxylase (TH), protected dopaminergic neurons from the neurotoxicity. Exposure to glutamate facilitated phosphoryration of TH at Ser31 by ERK, which contributes to the increased TH activity. Inhibition of ERK had no additive effect on the protection offered by alpha-MT, whereas alpha-MT and c-jun N-terminal kinase or p38 MAPK inhibitors had additive effects and yielded full protection. These data suggest that endogenous dopamine is responsible for the vulnerability to glutamate toxicity of dopaminergic neurons and one of the mechanisms may be an enhancement of dopamine synthesis mediated by ERK.

High dendritic expression of Ih in the proximity of the axon origin controls the integrative properties of nigral dopamine neurons.

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Engel, Dominique; Seutin, Vincent

2015-11-15

The hyperpolarization-activated cation current Ih is expressed in dopamine neurons of the substantia nigra, but the subcellular distribution of the current and its role in synaptic integration remain unknown. We used cell-attached patch recordings to determine the localization profile of Ih along the somatodendritic axis of nigral dopamine neurons in slices from young rats. Ih density is higher in axon-bearing dendrites, in a membrane area close to the axon origin, than in the soma and axon-lacking dendrites. Dual current-clamp recordings revealed a similar contribution of Ih to the waveform of single excitatory postsynaptic potentials throughout the somatodendritic domain. The Ih blocker ZD 7288 increased the temporal summation in all dendrites with a comparable effect in axon- and non-axon dendrites. The strategic position of Ih in the proximity of the axon may influence importantly transitions between pacemaker and bursting activities and consequently the downstream release of dopamine. Dendrites of most neurons express voltage-gated ion channels in their membrane. In combination with passive properties, active currents confer to dendrites a high computational potential. The hyperpolarization-activated cation current Ih present in the dendrites of some pyramidal neurons affects their membrane and integration properties, synaptic plasticity and higher functions such as memory. A gradient of increasing h-channel density towards distal dendrites has been found to be responsible for the location independence of excitatory postsynaptic potential (EPSP) waveform and temporal summation in cortical and hippocampal pyramidal cells. However, reports on other cell types revealed that smoother gradients or even linear distributions of Ih can achieve homogeneous temporal summation. Although the existence of a robust, slowly activating Ih current has been repeatedly demonstrated in nigral dopamine neurons, its subcellular distribution and precise role in synaptic integration

Role of Nitric Oxide in MPTP-Induced Dopaminergic Neuron Degeneration

National Research Council Canada - National Science Library

Przedborski, Serge

2002-01-01

...) induced dopaminergic (DA) neuron death in this mouse model of Parkinson's Disease (PD). Our previous work demonstrated that the superoxide radical is involved in the MPTP neurotoxic process in SNpc DA neurons...

Effects of Forskolin on Trefoil factor 1 expression in cultured ventral mesencephalic dopaminergic neurons

DEFF Research Database (Denmark)

Jensen, Pia; Ducray, A D; Widmer, H R

2015-01-01

shown that TFF1 is expressed in developing and adult rat ventral mesencephalic tyrosine hydroxylase-immunoreactive (TH-ir) dopaminergic neurons. Here, we investigated the expression of TFF1 in rat ventral mesencephalic dopaminergic neurons (embryonic day 14) grown in culture for 5, 7 or 10days......, suggesting that Forskolin induced TFF1 expression through diverse signaling pathways. In conclusion, distinct populations of cultured dopaminergic neurons express TFF1, and their numbers can be increased by factors known to influence survival and differentiation of dopaminergic cells....... to neuronal cells, and the percentage of TH/TFF1 co-expressing cells was increased to the same extent in GDNF and Forskolin-treated cultures (4-fold) as compared to controls. Interestingly, the combination of GDNF and Forskolin resulted in a significantly increased co-expression (8-fold) of TH/TFF1, which...

Presence of proNGF-Sortilin Signaling Complex in Nigral Dopamine Neurons and Its Variation in Relation to Aging, Lactacystin and 6-OHDA Insults

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Ken Kam-Lin Yung

2013-07-01

Full Text Available Growing evidence has shown that proNGF-p75NTR-sortilin signaling might be a crucial factor in neurodegeneration, but it remains unclear if it may function in nigral neurons under aging and disease. The purpose of this study is to examine and quantify proNGF and sortilin expression in the substantia nigra and dynamic changes of aging in lactacystin and 6-hydroxydopamine (6-OHDA rat models of Parkinson’s disease using immunofluorescence, electronic microscopy, western blot and FLIVO staining methods. The expression of proNGF and sortilin was abundantly and selectively identified in tyrosine hydroxylase (TH-containing dopamine neurons in the substantia nigra. These proNGF/TH, sortilin/TH-positive neurons were densely distributed in the ventral tier, while they were less distributed in the dorsal tier, where calbindin-D28K-containing neurons were numerously located. A correlated decrease of proNGF, sortilin and TH was also detected during animal aging process. While increase of proNGF, sortilin and cleaved (active caspase-3 expression was found in the lactacystin model, dynamic proNGF and sortilin changes along with dopamine neuronal loss were demonstrated in the substantia nigra of both the lactacystin and 6-OHDA models. This study has thus revealed the presence of the proNGF-sortilin signaling complex in nigral dopamine neurons and its response to aging, lactacystin and 6-OHDA insults, suggesting that it might contribute to neuronal apoptosis or neurodegeneration during pathogenesis and disease progression of Parkinson’s disease; the underlying mechanism and key signaling pathways involved warrant further investigation.

Functional properties and synaptic integration of genetically labelled dopaminergic neurons in intrastriatal grafts

DEFF Research Database (Denmark)

Sørensen, Andreas Toft; Thompson, Lachlan; Kirik, Deniz

2005-01-01

in the dopamine-depleted striatum than of those in the intact striatum. Our findings define specific electrophysiological characteristics of transplanted fetal dopaminergic neurons, and we provide the first direct evidence of functional synaptic integration of these neurons into host neural circuitries......., the electrophysiological properties grafted cells need to have in order to induce substantial functional recovery are poorly defined. It has not been possible to prospectively identify and record from dopaminergic neurons in fetal transplants. Here we used transgenic mice expressing green fluorescent protein under control...... of the rat tyrosine hydroxylase promoter for whole-cell patch-clamp recordings of endogenous and grafted dopaminergic neurons. We transplanted ventral mesencephalic tissue from E12.5 transgenic mice into striatum of neonatal rats with or without lesions of the nigrostriatal dopamine system. The transplanted...

Regulation of differentiation flux by Notch signalling influences the number of dopaminergic neurons in the adult brain

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Niurka Trujillo-Paredes

2016-03-01

Full Text Available Notch signalling is a well-established pathway that regulates neurogenesis. However, little is known about the role of Notch signalling in specific neuronal differentiation. Using Dll1 null mice, we found that Notch signalling has no function in the specification of mesencephalic dopaminergic neural precursor cells (NPCs, but plays an important role in regulating their expansion and differentiation into neurons. Premature neuronal differentiation was observed in mesencephalons of Dll1-deficient mice or after treatment with a Notch signalling inhibitor. Coupling between neurogenesis and dopaminergic differentiation was indicated from the coincident emergence of neuronal and dopaminergic markers. Early in differentiation, decreasing Notch signalling caused a reduction in NPCs and an increase in dopaminergic neurons in association with dynamic changes in the proportion of sequentially-linked dopaminergic NPCs (Msx1/2+, Ngn2+, Nurr1+. These effects in differentiation caused a significant reduction in the number of dopaminergic neurons produced. Accordingly, Dll1 haploinsufficient adult mice, in comparison with their wild-type littermates, have a consistent reduction in neuronal density that was particularly evident in the substantia nigra pars compacta. Our results are in agreement with a mathematical model based on a Dll1-mediated regulatory feedback loop between early progenitors and their dividing precursors that controls the emergence and number of dopaminergic neurons.

Protection of dopaminergic neurons by 5-lipoxygenase inhibitor.

Science.gov (United States)

Kang, Kai-Hsiang; Liou, Horng-Hui; Hour, Mann-Jen; Liou, Houng-Chi; Fu, Wen-Mei

2013-10-01

Neuroinflammation and oxidative stress are important factors that induce neurodegeneration in age-related neurological disorders. 5-Lipoxygenase (5-LOX) is the enzyme responsible for catalysing the synthesis of leukotriene or 5-HETE from arachidonic acid. 5-LOX is expressed in the central nervous system and may cause neurodegenerative disease. In this study, we investigated the effect of the pharmacological inhibition of 5-lipoxygenase on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)/MPP(+)-induced dopaminergic neuronal death in midbrain neuron-glia co-cultures and in mice. It was found that 5-LOX was over-expressed in astrocytes after the injection of MPTP into C57BL6 mice. MK-886, a specific inhibitor of 5-LOX activating protein (FLAP), significantly increased [(3)H]-dopamine uptake, a functional indicator of the integrity of dopaminergic neurons, in midbrain cultures or the SH-SY5Y human dopaminergic cell line following MPP(+) treatment. In addition, LTB₄, one of 5-LOX's downstream products, was increased in the striatum and substantia nigra following MPTP injection in mice. LTB₄ but not LTD₄ and 5-HETE enhanced MPP(+)-induced neurotoxicity in primary midbrain cultures. MK-886 administration increased the number of tyrosine hydroxylase-positive neurons in the substantia nigra and the dopamine content in the striatum in MPTP-induced parkinsonian mice. Furthermore, the MPTP-induced upregulation of LTB₄ in the striatum and substantia nigra was antagonised by MK-886. These results suggest that 5-LOX inhibitors may be developed as novel neuroprotective agents and LTB₄ may play an important pathological role in Parkinson's disease. Copyright © 2013 Elsevier Ltd. All rights reserved.

Variability in the clinical expression of Parkinson's disease

NARCIS (Netherlands)

Wolters, E.C.

2008-01-01

Parkinsonism is a clinical syndrome characterized by bradykinesia, hypo-/akinesia, muscular rigidity, and resting tremor, mainly caused by Parkinson's disease (PD). Symptoms of PD are due to a progressive loss of nigral neurons causing striatal dopaminergic denervation. However, nigral degeneration

Complementary neural correlates of motivation in dopaminergic and noradrenergic neurons of monkeys.

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Sebastien eBouret

2012-07-01

Full Text Available Rewards have many influences on learning, decision-making and performance. All seem to rely on complementary actions of two closely related catecholaminergic neuromodulators, dopamine and noradrenaline. We compared single unit activity of dopaminergic neurons of the substantia nigra pars compacta and noradrenergic neurons of the locus coeruleus in monkeys performing a reward schedule task. Their motivation, indexed using operant performance, increased as they progressed through schedules ending in reward delivery. The responses of dopaminergic and noradrenergic neurons around the time of major task events, visual cues predicting trial outcome and operant action to complete a trial, were similar, in that they occurred at the same time. They were also similar in that they both responded most strongly to the first cues in schedules, which are the most informative cues. The neuronal responses around the time of the monkeys’ actions were different, in that the response intensity profiles changed in opposite directions. Dopaminergic responses were stronger around predictably rewarded correct actions whereas noradrenergic responses were greater around predictably unrewarded correct actions. The complementary response profiles related to the monkeys operant actions suggest that dopamine neurons might relate to the value of the current action whereas the noradrenergic neurons relate to the psychological cost of that action.

Bursting as a source of non-linear determinism in the firing patterns of nigral dopamine neurons.

Science.gov (United States)

Jeong, Jaeseung; Shi, Wei-Xing; Hoffman, Ralph; Oh, Jihoon; Gore, John C; Bunney, Benjamin S; Peterson, Bradley S

2012-11-01

Nigral dopamine (DA) neurons in vivo exhibit complex firing patterns consisting of tonic single-spikes and phasic bursts that encode information for certain types of reward-related learning and behavior. Non-linear dynamical analysis has previously demonstrated the presence of a non-linear deterministic structure in complex firing patterns of DA neurons, yet the origin of this non-linear determinism remains unknown. In this study, we hypothesized that bursting activity is the primary source of non-linear determinism in the firing patterns of DA neurons. To test this hypothesis, we investigated the dimension complexity of inter-spike interval data recorded in vivo from bursting and non-bursting DA neurons in the chloral hydrate-anesthetized rat substantia nigra. We found that bursting DA neurons exhibited non-linear determinism in their firing patterns, whereas non-bursting DA neurons showed truly stochastic firing patterns. Determinism was also detected in the isolated burst and inter-burst interval data extracted from firing patterns of bursting neurons. Moreover, less bursting DA neurons in halothane-anesthetized rats exhibited higher dimensional spiking dynamics than do more bursting DA neurons in chloral hydrate-anesthetized rats. These results strongly indicate that bursting activity is the main source of low-dimensional, non-linear determinism in the firing patterns of DA neurons. This finding furthermore suggests that bursts are the likely carriers of meaningful information in the firing activities of DA neurons. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Transcranial magnetic stimulation promotes the proliferation of dopaminergic neuronal cells in vitro

Science.gov (United States)

Zhong, Xiaojing; Luo, Jie; Rastogi, Priyam; Kanthasamy, Anumantha G.; Jiles, David C.; Fellow, IEEE

2018-05-01

Transcranial magnetic stimulation (TMS) is a safe and non-invasive treatment for neurological disorders. TMS has been approved as a treatment for major depressive disorders by the US Food and Drug Administration (FDA) in 2008. Due to the phenomenon of electromagnetic induction, a time-varying magnetic field induces an electric field in the conductive tissues in the brain, TMS has the ability to activate neurons in vivo. However, the effects of the magnetic fields on neurons in cell culture have not been investigated adequately. The magnetic fields affect the neurons when the potential across the neuronal membrane exceeds the threshold which in turn causes an action potential. Based on these theories, we investigated the effects of the magnetic fields generated by a monophasic stimulator with a 70 mm double coil on rat dopaminergic neuronal cell lines (N27). The directions of the magnetic fields in each coil of the double coil oppose each other. The effects of changing the direction of the magnetic field on N27 neurons was also investigated. The results of the experiments showed that both of the fields perpendicular to the coil surface promoted the proliferation of N27 dopaminergic neurons. In order to investigate the gene expression and protein expression affected by TMS, quantitative Polymerase Chain Reaction (qPCR) was used. Here we report changes in glial cell line-derived neurotrophic factor (GDNF) in dopaminergic neuronal cells (N27) after TMS treatment.

Transcranial magnetic stimulation promotes the proliferation of dopaminergic neuronal cells in vitro

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Xiaojing Zhong

2018-05-01

Full Text Available Transcranial magnetic stimulation (TMS is a safe and non-invasive treatment for neurological disorders. TMS has been approved as a treatment for major depressive disorders by the US Food and Drug Administration (FDA in 2008. Due to the phenomenon of electromagnetic induction, a time-varying magnetic field induces an electric field in the conductive tissues in the brain, TMS has the ability to activate neurons in vivo. However, the effects of the magnetic fields on neurons in cell culture have not been investigated adequately. The magnetic fields affect the neurons when the potential across the neuronal membrane exceeds the threshold which in turn causes an action potential. Based on these theories, we investigated the effects of the magnetic fields generated by a monophasic stimulator with a 70 mm double coil on rat dopaminergic neuronal cell lines (N27. The directions of the magnetic fields in each coil of the double coil oppose each other. The effects of changing the direction of the magnetic field on N27 neurons was also investigated. The results of the experiments showed that both of the fields perpendicular to the coil surface promoted the proliferation of N27 dopaminergic neurons. In order to investigate the gene expression and protein expression affected by TMS, quantitative Polymerase Chain Reaction (qPCR was used. Here we report changes in glial cell line-derived neurotrophic factor (GDNF in dopaminergic neuronal cells (N27 after TMS treatment.

Simultaneous activation of mitophagy and autophagy by staurosporine protects against dopaminergic neuronal cell death.

Science.gov (United States)

Ha, Ji-Young; Kim, Ji-Soo; Kim, Seo-Eun; Son, Jin H

2014-02-21

Abnormal autophagy is frequently observed during dopaminergic neurodegeneration in Parkinson's disease (PD). However, it is not yet firmly established whether active autophagy is beneficial or pathogenic with respect to dopaminergic cell loss. Staurosporine, a common inducer of apoptosis, is often used in mechanistic studies of dopaminergic cell death. Here we report that staurosporine activates both autophagy and mitophagy simultaneously during dopaminergic neuronal cell death, and evaluate the physiological significance of these processes during cell death. First, staurosporine treatment resulted in induction of autophagy in more than 75% of apoptotic cells. Pharmacological inhibition of autophagy by bafilomycin A1 decreased significantly cell viability. In addition, staurosporine treatment resulted in activation of the PINK1-Parkin mitophagy pathway, of which deficit underlies some familial cases of PD, in the dopaminergic neuronal cell line, SN4741. The genetic blockade of this pathway by PINK1 null mutation also dramatically increased staurosporine-induced cell death. Taken together, our data suggest that staurosporine induces both mitophagy and autophagy, and that these pathways exert a significant neuroprotective effect, rather than a contribution to autophagic cell death. This model system may therefore be useful for elucidating the mechanisms underlying crosstalk between autophagy, mitophagy, and cell death in dopaminergic neurons. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

25-Hydroxyvitamin D depletion does not exacerbate MPTP-induced dopamine neuron damage in mice.

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E Danielle Dean

Full Text Available Recent clinical evidence supports a link between 25-hydroxyvitamin D insufficiency (serum 25-hydroxyvitamin D [25(OHD] levels <30 ng/mL and Parkinson's disease. To investigate the effect of 25(OHD depletion on neuronal susceptibility to toxic insult, we induced a state of 25(OHD deficiency in mice and then challenged them with the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP. We found there was no significant difference between control and 25(OHD-deficient animals in striatal dopamine levels or dopamine transporter and tyrosine hydroxylase expression after lesioning with MPTP. Additionally, we found no difference in tyrosine hydroxylase expression in the substantia nigra pars compacta. Our data suggest that reducing 25(OHD serum levels in mice has no effect on the vulnerability of nigral dopaminergic neurons in vivo in this model system of parkinsonism.

ELECTROPHYSIOLOGICAL CHARACTERIZATION OF DOPAMINERGIC AND NONDOPAMINERGIC NEURONS IN ORGANOTYPIC SLICE CULTURES OF THE RAT VENTRAL MESENCEPHALON

DEFF Research Database (Denmark)

STEENSEN, BH; NEDERGAARD, S; OSTERGAARD, K

1995-01-01

-old organotypic slice cultures of the ventral mesencephalon prepared from newborn rats. Dopaminergic neurones were distinguished from non-dopaminergic neurones by staining with the autofluorescent serotonin analogue 5,7-dihydroxytryptamine and briefly viewing the preparation with short exposures to ultraviolet...... 81 M Omega), were silent or fired spontaneously at a low frequency (0-9 Hz), and no spontaneous GABA(A)-ergic inhibitory postsynaptic potentials or inward rectification were present. In contrast, non-dopaminergic neurones had fast action potentials (0.6-3.2 ms), low input resistance (mean 32 M Omega...

Bimolecular Fluorescence Complementation of Alpha-synuclein Demonstrates its Oligomerization with Dopaminergic Phenotype in Mice

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Waijiao Cai

2018-03-01

Full Text Available Alpha-synuclein (αSyn is encoded by the first causal gene identified in Parkinson's disease (PD and is the main component of Lewy bodies, a pathological hallmark of PD. aSyn-based animal models have contributed to our understanding of PD pathophysiology and to the development of therapeutics. Overexpression of human wildtype αSyn by viral vectors in rodents recapitulates the loss of dopaminergic neurons from the substantia nigra, another defining pathological feature of the disease. The development of a rat model exhibiting bimolecular fluorescence complementation (BiFC of αSyn by recombinant adeno-associated virus facilitates detection of the toxic αSyn oligomers species. We report here neurochemical, neuropathological and behavioral characterization of BiFC of αSyn in mice. Overexpression and oligomerization of αSyn through BiFC is detected by conjugated fluorescence. Reduced striatal dopamine and loss of nigral dopaminergic neurons are accompanied neuroinflammation and abnormal motor activities. Our mouse model may provide a valuable tool to study the role of αSyn in PD and to explore therapeutic approaches. Keywords: Parkinson's disease, Alpha-synuclein, Mouse model, Oligomers, Neuroinflammation

Mitogen-activated protein kinase phosphatase (MKP)-1 as a neuroprotective agent: promotion of the morphological development of midbrain dopaminergic neurons.

Science.gov (United States)

Collins, Louise M; O'Keeffe, Gerard W; Long-Smith, Caitriona M; Wyatt, Sean L; Sullivan, Aideen M; Toulouse, André; Nolan, Yvonne M

2013-06-01

A greater understanding of the mechanisms that promote the survival and growth of dopaminergic neurons is essential for the advancement of cell replacement therapies for Parkinson's disease (PD). Evidence supports a role for the mitogen-activated protein kinase p38 in the demise of dopaminergic neurons, while mitogen-activated protein kinase phosphatase-1 (MKP-1), which negatively regulates p38 activity, has not yet been investigated in this context. Here, we show that MKP-1 is expressed in dopaminergic neurons cultured from E14 rat ventral mesencephalon (VM). When dopaminergic neurons were transfected to overexpress MKP-1, they displayed a more complex morphology than their control counterparts in vitro. Specifically, MKP-1-transfection induced significant increases in neurite length and branching with a maximum increase observed in primary branches. We demonstrate that inhibition of dopaminergic neurite growth induced by treatment of rat VM neurons with the dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA) in vitro is mediated by p38 and is concomitant with a significant and selective decrease in MKP-1 expression in these neurons. We further show that overexpression of MKP-1 in dopaminergic neurons contributes to neuroprotection against the effects of 6-OHDA. Collectively, we report that MKP-1 can promote the growth and elaboration of dopaminergic neuronal processes and can help protect them from the neurotoxic effects of 6-OHDA. Thus, we propose that strategies aimed at augmenting MKP-1 expression or activity may be beneficial in protecting dopaminergic neurons and may provide potential therapeutic approaches for PD.

Differentiation and Characterization of Dopaminergic Neurons From Baboon Induced Pluripotent Stem Cells.

Science.gov (United States)

Grow, Douglas A; Simmons, DeNard V; Gomez, Jorge A; Wanat, Matthew J; McCarrey, John R; Paladini, Carlos A; Navara, Christopher S

2016-09-01

: The progressive death of dopamine producing neurons in the substantia nigra pars compacta is the principal cause of symptoms of Parkinson's disease (PD). Stem cells have potential therapeutic use in replacing these cells and restoring function. To facilitate development of this approach, we sought to establish a preclinical model based on a large nonhuman primate for testing the efficacy and safety of stem cell-based transplantation. To this end, we differentiated baboon fibroblast-derived induced pluripotent stem cells (biPSCs) into dopaminergic neurons with the application of specific morphogens and growth factors. We confirmed that biPSC-derived dopaminergic neurons resemble those found in the human midbrain based on cell type-specific expression of dopamine markers TH and GIRK2. Using the reverse transcriptase quantitative polymerase chain reaction, we also showed that biPSC-derived dopaminergic neurons express PAX6, FOXA2, LMX1A, NURR1, and TH genes characteristic of this cell type in vivo. We used perforated patch-clamp electrophysiology to demonstrate that biPSC-derived dopaminergic neurons fired spontaneous rhythmic action potentials and high-frequency action potentials with spike frequency adaption upon injection of depolarizing current. Finally, we showed that biPSC-derived neurons released catecholamines in response to electrical stimulation. These results demonstrate the utility of the baboon model for testing and optimizing the efficacy and safety of stem cell-based therapeutic approaches for the treatment of PD. Functional dopamine neurons were produced from baboon induced pluripotent stem cells, and their properties were compared to baboon midbrain cells in vivo. The baboon has advantages as a clinically relevant model in which to optimize the efficacy and safety of stem cell-based therapies for neurodegenerative diseases, such as Parkinson's disease. Baboons possess crucial neuroanatomical and immunological similarities to humans, and baboon

Neuroprotective effects of edaravone-administration on 6-OHDA-treated dopaminergic neurons

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Wang Feifei

2008-08-01

Full Text Available Abstract Background Parkinson's disease (PD is a neurological disorder characterized by the degeneration of nigrostriatal dopaminergic systems. Free radicals induced by oxidative stress are involved in the mechanisms of cell death in PD. This study clarifies the neuroprotective effects of edaravone (MCI-186, 3-methyl-1-phenyl-2-pyrazolin-5-one, which has already been used for the treatment of cerebral ischemia in Japan, on TH-positive dopaminergic neurons using PD model both in vitro and in vivo. 6-hydroxydopamine (6-OHDA, a neurotoxin for dopaminergic neurons, was added to cultured dopaminergic neurons derived from murine embryonal ventral mesencephalon with subsequet administration of edaravone or saline. The number of surviving TH-positive neurons and the degree of cell damage induced by free radicals were analyzed. In parallel, edaravone or saline was intravenously administered for PD model of rats receiving intrastriatal 6-OHDA lesion with subsequent behavioral and histological analyses. Results In vitro study showed that edaravone significantly ameliorated the survival of TH-positive neurons in a dose-responsive manner. The number of apoptotic cells and HEt-positive cells significantly decreased, thus indicating that the neuroprotective effects of edaravone might be mediated by anti-apoptotic effects through the suppression of free radicals by edaravone. In vivo study demonstrated that edaravone-administration at 30 minutes after 6-OHDA lesion reduced the number of amphetamine-induced rotations significantly than edaravone-administration at 24 hours. Tyrosine hydroxylase (TH staining of the striatum and substantia nigra pars compacta revealed that edaravone might exert neuroprotective effects on nigrostriatal dopaminergic systems. The neuroprotective effects were prominent when edaravone was administered early and in high concentration. TUNEL, HEt and Iba-1 staining in vivo might demonstrate the involvement of anti-apoptotic, anti

Effects of zoxazolamine and related centrally acting muscle relaxants on nigrostriatal dopaminergic neurons.

Science.gov (United States)

Matthews, R T; McMillen, B A; Speciale, S G; Jarrah, H; Shore, P A; Sanghera, M K; Shepard, P D; German, D C

1984-05-01

The effects of zoxazolamine (ZOX) and related centrally acting muscle relaxants on striatal dopamine (DA) metabolism and turnover, and substantia nigra zona compacta DA neuronal impulse flow were studied in rats. ZOX, chlorzoxazone and mephenesin, but not meprobamate, chloral hydrate, diazepam, pentobarbital, ethanol or dantrolene, decreased striatal DA metabolism without affecting striatal DA concentrations. More specifically, ZOX, as a representative muscle relaxant, was shown to decrease striatal DA turnover without directly affecting DA synthesis, catabolism, reuptake, or release. ZOX decreased nigral DA neuronal firing rates and dramatically decreased firing rate variability (normally many of the cells fire with bursting firing patterns but after ZOX the cells often fired with a very regular pacemaker-like firing pattern). ZOX and related centrally acting muscle relaxants appear to decrease striatal DA turnover by decreasing both neuronal firing rate and firing rate variability. The possible relationships between DA neuronal activity and muscle tone are discussed.

Novelty-Sensitive Dopaminergic Neurons in the Human Substantia Nigra Predict Success of Declarative Memory Formation.

Science.gov (United States)

Kamiński, Jan; Mamelak, Adam N; Birch, Kurtis; Mosher, Clayton P; Tagliati, Michele; Rutishauser, Ueli

2018-04-12

The encoding of information into long-term declarative memory is facilitated by dopamine. This process depends on hippocampal novelty signals, but it remains unknown how midbrain dopaminergic neurons are modulated by declarative-memory-based information. We recorded individual substantia nigra (SN) neurons and cortical field potentials in human patients performing a recognition memory task. We found that 25% of SN neurons were modulated by stimulus novelty. Extracellular waveform shape and anatomical location indicated that these memory-selective neurons were putatively dopaminergic. The responses of memory-selective neurons appeared 527 ms after stimulus onset, changed after a single trial, and were indicative of recognition accuracy. SN neurons phase locked to frontal cortical theta-frequency oscillations, and the extent of this coordination predicted successful memory formation. These data reveal that dopaminergic neurons in the human SN are modulated by memory signals and demonstrate a progression of information flow in the hippocampal-basal ganglia-frontal cortex loop for memory encoding. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

PINK1 Primes Parkin-Mediated Ubiquitination of PARIS in Dopaminergic Neuronal Survival

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Yunjong Lee

2017-01-01

Full Text Available Mutations in PTEN-induced putative kinase 1 (PINK1 and parkin cause autosomal-recessive Parkinson’s disease through a common pathway involving mitochondrial quality control. Parkin inactivation leads to accumulation of the parkin interacting substrate (PARIS, ZNF746 that plays an important role in dopamine cell loss through repression of proliferator-activated receptor gamma coactivator-1-alpha (PGC-1α promoter activity. Here, we show that PARIS links PINK1 and parkin in a common pathway that regulates dopaminergic neuron survival. PINK1 interacts with and phosphorylates serines 322 and 613 of PARIS to control its ubiquitination and clearance by parkin. PINK1 phosphorylation of PARIS alleviates PARIS toxicity, as well as repression of PGC-1α promoter activity. Conditional knockdown of PINK1 in adult mouse brains leads to a progressive loss of dopaminergic neurons in the substantia nigra that is dependent on PARIS. Altogether, these results uncover a function of PINK1 to direct parkin-PARIS-regulated PGC-1α expression and dopaminergic neuronal survival.

Effects of combined BDNF and GDNF treatment on cultured dopaminergic midbrain neurons

DEFF Research Database (Denmark)

Sautter, J; Meyer, Morten; Spenger, C

1998-01-01

Neural transplantation is an experimental therapy for Parkinson's disease. Pretreatment of fetal donor tissue with neurotrophic factors may improve survival of grafted dopaminergic neurons. Free-floating roller tube cultures of fetal rat ventral mesencephalon were treated with brain-derived neuro......Neural transplantation is an experimental therapy for Parkinson's disease. Pretreatment of fetal donor tissue with neurotrophic factors may improve survival of grafted dopaminergic neurons. Free-floating roller tube cultures of fetal rat ventral mesencephalon were treated with brain......-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), or a combination of both. Dopamine content of the culture medium, the number of tyrosine hydroxylase-immunoreactive neurons, and culture volumes were moderately increased in the BDNF- and GDNF-treated cultures but significantly...... increased by 6.8-, 3.2- and 2.4-fold, respectively after treatment with the combination of both factors. We conclude that pretreatment of dopaminergic tissue in culture with a combination of BDNF and GDNF may be an effective means to improve the quality of tissue prior to grafting....

Dopaminergic Neurons Controlling Anterior Pituitary Functions: Anatomy and Ontogenesis in Zebrafish.

Science.gov (United States)

Fontaine, Romain; Affaticati, Pierre; Bureau, Charlotte; Colin, Ingrid; Demarque, Michaël; Dufour, Sylvie; Vernier, Philippe; Yamamoto, Kei; Pasqualini, Catherine

2015-08-01

Dopaminergic (DA) neurons located in the preoptico-hypothalamic region of the brain exert a major neuroendocrine control on reproduction, growth, and homeostasis by regulating the secretion of anterior pituitary (or adenohypophysis) hormones. Here, using a retrograde tract tracing experiment, we identified the neurons playing this role in the zebrafish. The DA cells projecting directly to the anterior pituitary are localized in the most anteroventral part of the preoptic area, and we named them preoptico-hypophyseal DA (POHDA) neurons. During development, these neurons do not appear before 72 hours postfertilization (hpf) and are the last dopaminergic cell group to differentiate. We found that the number of neurons in this cell population continues to increase throughout life proportionally to the growth of the fish. 5-Bromo-2'-deoxyuridine incorporation analysis suggested that this increase is due to continuous neurogenesis and not due to a phenotypic change in already-existing neurons. Finally, expression profiles of several genes (foxg1a, dlx2a, and nr4a2a/b) were different in the POHDA compared with the adjacent suprachiasmatic DA neurons, suggesting that POHDA neurons develop as a distinct DA cell population in the preoptic area. This study offers some insights into the regional identity of the preoptic area and provides the first bases for future functional genetic studies on the development of DA neurons controlling anterior pituitary functions.

Electrophysiological and pharmacological evidence for the existence of distinct subpopulations of nigrostriatal dopaminergic neuron in the rat.

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Shepard, P D; German, D C

1988-11-01

The electrophysiological and pharmacological properties of dopaminergic neurons were systematically examined throughout the anterior-posterior extent of the substantia nigra zona compacta in the rat. Cells were characterized in terms of their (1) firing pattern, (2) firing rate, (3) antidromic response properties, and (4) inhibition in firing rate following dopaminergic agonist administration. These properties were then related to the cell's position within one of four anterior-posterior segments of the nucleus. There were three types of neuronal discharge pattern encountered; irregular, burst and regular. Cells which exhibited different firing patterns exhibited different firing rates and anatomical locations within the substantia nigra zona compacta. All neurons were antidromically activated from the striatum, however, the burst- and regular-firing cells exhibited significantly faster estimated conduction velocities than irregular-firing cells. The irregular-firing cells were most sensitive to dopaminergic autoreceptor agonists whereas the burst-firing cells were most sensitive to an indirect-acting dopaminergic agonist. These experiments provide both electrophysiological and pharmacological evidence to indicate that nigrostriatal dopaminergic neurons are composed of distinct subpopulations which are characterized by their firing pattern.

Linkage of cDNA expression profiles of mesencephalic dopaminergic neurons to a genome-wide in situ hybridization database

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Simon Horst H

2009-01-01

Full Text Available Abstract Midbrain dopaminergic neurons are involved in control of emotion, motivation and motor behavior. The loss of one of the subpopulations, substantia nigra pars compacta, is the pathological hallmark of one of the most prominent neurological disorders, Parkinson's disease. Several groups have looked at the molecular identity of midbrain dopaminergic neurons and have suggested the gene expression profile of these neurons. Here, after determining the efficiency of each screen, we provide a linked database of the genes, expressed in this neuronal population, by combining and comparing the results of six previous studies and verification of expression of each gene in dopaminergic neurons, using the collection of in situ hybridization in the Allen Brain Atlas.

Mesenchymal Stem Cells as a Source of Dopaminergic Neurons: A Potential Cell Based Therapy for Parkinson's Disease.

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Venkatesh, Katari; Sen, Dwaipayan

2017-01-01

Cell repair/replacing strategies for neurodegenerative diseases such as Parkinson's disease depend on well-characterized dopaminergic neuronal candidates that are healthy and show promising effect on the rejuvenation of degenerated area of the brain. Therefore, it is imperative to develop innovative therapeutic strategies that replace damaged neurons with new/functional dopaminergic neurons. Although several research groups have reported the generation of neural precursors/neurons from human/ mouse embryonic stem cells and mesenchymal stem cells, the latter is considered to be an attractive therapeutic candidate because of its high capacity for self-renewable, no adverse effect to allogeneic versus autologous transplants, high ethical acceptance and no teratoma formation. Therefore, mesenchymal stem cells can be considered as an ideal source for replacing lost cells in degenerative diseases like Parkinson's. Hence, the use of these cells in the differentiation of dopaminergic neurons becomes significant and thrives as a therapeutic approach to treat Parkinson's disease. Here we highlight the basic biology of mesenchymal stem cells, their differentiation potential into dopaminergic neurons and potential use in the clinics. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Parkin Mutations Reduce the Complexity of Neuronal Processes in iPSC-derived Human Neurons

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Ren, Yong; Jiang, Houbo; Hu, Zhixing; Fan, Kevin; Wang, Jun; Janoschka, Stephen; Wang, Xiaomin; Ge, Shaoyu; Feng, Jian

2015-01-01

Parkinson’s disease (PD) is characterized by the degeneration of nigral dopaminergic (DA) neurons and non-DA neurons in many parts of the brain. Mutations of parkin, an E3 ubiquitin ligase that strongly binds to microtubules, are the most frequent cause of recessively inherited Parkinson’s disease. The lack of robust PD phenotype in parkin knockout mice suggests a unique vulnerability of human neurons to parkin mutations. Here, we show that the complexity of neuronal processes as measured by total neurite length, number of terminals, number of branch points and Sholl analysis, was greatly reduced in induced pluripotent stem cell (iPSC)-derived TH+ or TH− neurons from PD patients with parkin mutations. Consistent with these, microtubule stability was significantly decreased by parkin mutations in iPSC-derived neurons. Overexpression of parkin, but not its PD-linked mutant nor GFP, restored the complexity of neuronal processes and the stability of microtubules. Consistent with these, the microtubule-depolymerizing agent colchicine mimicked the effect of parkin mutations by decreasing neurite length and complexity in control neurons while the microtubule-stabilizing drug taxol mimicked the effect of parkin overexpression by enhancing the morphology of parkin-deficient neurons. The results suggest that parkin maintains the morphological complexity of human neurons by stabilizing microtubules. PMID:25332110

A Tyrosine-Hydroxylase Characterization of Dopaminergic Neurons in the Honey Bee Brain

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Stevanus R. Tedjakumala

2017-07-01

Full Text Available Dopamine (DA plays a fundamental role in insect behavior as it acts both as a general modulator of behavior and as a value system in associative learning where it mediates the reinforcing properties of unconditioned stimuli (US. Here we aimed at characterizing the dopaminergic neurons in the central nervous system of the honey bee, an insect that serves as an established model for the study of learning and memory. We used tyrosine hydroxylase (TH immunoreactivity (ir to ensure that the neurons detected synthesize DA endogenously. We found three main dopaminergic clusters, C1–C3, which had been previously described; the C1 cluster is located in a small region adjacent to the esophagus (ES and the antennal lobe (AL; the C2 cluster is situated above the C1 cluster, between the AL and the vertical lobe (VL of the mushroom body (MB; the C3 cluster is located below the calyces (CA of the MB. In addition, we found a novel dopaminergic cluster, C4, located above the dorsomedial border of the lobula, which innervates the visual neuropils of the bee brain. Additional smaller processes and clusters were found and are described. The profuse dopaminergic innervation of the entire bee brain and the specific connectivity of DA neurons, with visual, olfactory and gustatory circuits, provide a foundation for a deeper understanding of how these sensory modules are modulated by DA, and the DA-dependent value-based associations that occur during associative learning.

Tp53 gene mediates distinct dopaminergic neuronal damage in different dopaminergic neurotoxicant models

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Tao Lu

2017-01-01

Full Text Available Tp53, a stress response gene, is involved in diverse cell death pathways and its activation is implicated in the pathogenesis of Parkinson's disease. However, whether the neuronal Tp53 protein plays a direct role in regulating dopaminergic (DA neuronal cell death or neuronal terminal damage in different neurotoxicant models is unknown. In our recent studies, in contrast to the global inhibition of Tp53 function by pharmacological inhibitors and in traditional Tp53 knock-out mice, we examined the effects of DA-specific Tp53 gene deletion after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and methamphetamine exposure. Our data suggests that the Tp53 gene might be involved in both neuronal apoptosis and neuronal terminal damage caused by different neurotoxicants. Additional results from other studies also suggest that as a master regulator of many pathways that regulate apoptosis and synaptic terminal damage, it is possible that Tp53 may function as a signaling hub to integrate different signaling pathways to mediate distinctive target pathways. Tp53 protein as a signaling hub might be able to evaluate the microenvironment of neurons, assess the forms and severities of injury incurred, and determine whether apoptotic cell death or neuronal terminal degeneration occurs. Identification of the precise mechanisms activated in distinct neuronal damage caused by different forms and severities of injuries might allow for development of specific Tp53 inhibitors or ways to modulate distinct downstream target pathways involved.

The Transcription Factor Orthodenticle Homeobox 2 Influences Axonal Projections and Vulnerability of Midbrain Dopaminergic Neurons

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Chung, Chee Yeun; Licznerski, Pawel; Alavian, Kambiz N.; Simeone, Antonio; Lin, Zhicheng; Martin, Eden; Vance, Jeffery; Isacson, Ole

2010-01-01

Two adjacent groups of midbrain dopaminergic neurons, A9 (substantia nigra pars compacta) and A10 (ventral tegmental area), have distinct projections and exhibit differential vulnerability in Parkinson's disease. Little is known about transcription factors that influence midbrain dopaminergic subgroup phenotypes or their potential role in disease.…

Parkin protects dopaminergic neurons from excessive Wnt/β-catenin signaling

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Rawal, Nina; Corti, Olga; Sacchetti, Paola; Ardilla-Osorio, Hector; Sehat, Bita; Brice, Alexis; Arenas, Ernest

2009-01-01

Parkinson's disease (PD) is caused by degeneration of the dopaminergic (DA) neurons of the substantia nigra but the molecular mechanisms underlying the degenerative process remain elusive. Several reports suggest that cell cycle deregulation in post-mitotic neurons could lead to neuronal cell death. We now show that Parkin, an E3 ubiquitin ligase linked to familial PD, regulates β-catenin protein levels in vivo. Stabilization of β-catenin in differentiated primary ventral midbrain neurons results in increased levels of cyclin E and proliferation, followed by increased levels of cleaved PARP and loss of DA neurons. Wnt3a signaling also causes death of post-mitotic DA neurons in parkin null animals, suggesting that both increased stabilization and decreased degradation of β-catenin results in DA cell death. These findings demonstrate a novel regulation of Wnt signaling by Parkin and suggest that Parkin protects DA neurons against excessive Wnt signaling and β-catenin-induced cell death.

Parkin protects dopaminergic neurons from excessive Wnt/{beta}-catenin signaling

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Rawal, Nina [Laboratory of Molecular Neurobiology, MBB, DBRM, Karolinska Institute, S-17177 Stockholm (Sweden); Corti, Olga [Universite Pierre et Marie Curie-Paris 6, CRICM UMR-S975, Inserm, U975 (France); CNRS, UMR 7225, Paris (France); Sacchetti, Paola [Laboratory of Molecular Neurobiology, MBB, DBRM, Karolinska Institute, S-17177 Stockholm (Sweden); Ardilla-Osorio, Hector [Universite Pierre et Marie Curie-Paris 6, CRICM UMR-S975, Inserm, U975 (France); CNRS, UMR 7225, Paris (France); Sehat, Bita [Cancer Center Karolinska, Karolinska Institute, S-17177 Stockholm (Sweden); Brice, Alexis [Universite Pierre et Marie Curie-Paris 6, CRICM UMR-S975, Inserm, U975 (France); CNRS, UMR 7225, Paris (France); Department of Genetics and Cytogenetics, AP-HP, Groupe Hospitalier Pitie-Salpetriere, Paris (France); Arenas, Ernest, E-mail: Ernest.Arenas@ki.se [Laboratory of Molecular Neurobiology, MBB, DBRM, Karolinska Institute, S-17177 Stockholm (Sweden)

2009-10-23

Parkinson's disease (PD) is caused by degeneration of the dopaminergic (DA) neurons of the substantia nigra but the molecular mechanisms underlying the degenerative process remain elusive. Several reports suggest that cell cycle deregulation in post-mitotic neurons could lead to neuronal cell death. We now show that Parkin, an E3 ubiquitin ligase linked to familial PD, regulates {beta}-catenin protein levels in vivo. Stabilization of {beta}-catenin in differentiated primary ventral midbrain neurons results in increased levels of cyclin E and proliferation, followed by increased levels of cleaved PARP and loss of DA neurons. Wnt3a signaling also causes death of post-mitotic DA neurons in parkin null animals, suggesting that both increased stabilization and decreased degradation of {beta}-catenin results in DA cell death. These findings demonstrate a novel regulation of Wnt signaling by Parkin and suggest that Parkin protects DA neurons against excessive Wnt signaling and {beta}-catenin-induced cell death.

Roles of octopaminergic and dopaminergic neurons in appetitive and aversive memory recall in an insect.

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Mizunami, Makoto; Unoki, Sae; Mori, Yasuhiro; Hirashima, Daisuke; Hatano, Ai; Matsumoto, Yukihisa

2009-08-04

In insect classical conditioning, octopamine (the invertebrate counterpart of noradrenaline) or dopamine has been suggested to mediate reinforcing properties of appetitive or aversive unconditioned stimulus, respectively. However, the roles of octopaminergic and dopaminergic neurons in memory recall have remained unclear. We studied the roles of octopaminergic and dopaminergic neurons in appetitive and aversive memory recall in olfactory and visual conditioning in crickets. We found that pharmacological blockade of octopamine and dopamine receptors impaired aversive memory recall and appetitive memory recall, respectively, thereby suggesting that activation of octopaminergic and dopaminergic neurons and the resulting release of octopamine and dopamine are needed for appetitive and aversive memory recall, respectively. On the basis of this finding, we propose a new model in which it is assumed that two types of synaptic connections are formed by conditioning and are activated during memory recall, one type being connections from neurons representing conditioned stimulus to neurons inducing conditioned response and the other being connections from neurons representing conditioned stimulus to octopaminergic or dopaminergic neurons representing appetitive or aversive unconditioned stimulus, respectively. The former is called 'stimulus-response connection' and the latter is called 'stimulus-stimulus connection' by theorists studying classical conditioning in higher vertebrates. Our model predicts that pharmacological blockade of octopamine or dopamine receptors during the first stage of second-order conditioning does not impair second-order conditioning, because it impairs the formation of the stimulus-response connection but not the stimulus-stimulus connection. The results of our study with a cross-modal second-order conditioning were in full accordance with this prediction. We suggest that insect classical conditioning involves the formation of two kinds of memory

Neuron-derived IgG protects dopaminergic neurons from insult by 6-OHDA and activates microglia through the FcγR I and TLR4 pathways.

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Zhang, Jie; Niu, Na; Wang, Mingyu; McNutt, Michael A; Zhang, Donghong; Zhang, Baogang; Lu, Shijun; Liu, Yuqing; Liu, Zhihui

2013-08-01

Oxidative and immune attacks from the environment or microglia have been implicated in the loss of dopaminergic neurons of Parkinson's disease. The role of IgG which is an important immunologic molecule in the process of Parkinson's disease has been unclear. Evidence suggests that IgG can be produced by neurons in addition to its traditionally recognized source B lymphocytes, but its function in neurons is poorly understood. In this study, extensive expression of neuron-derived IgG was demonstrated in dopaminergic neurons of human and rat mesencephalon. With an in vitro Parkinson's disease model, we found that neuron-derived IgG can improve the survival and reduce apoptosis of dopaminergic neurons induced by 6-hydroxydopamine toxicity, and also depress the release of NO from microglia triggered by 6-hydroxydopamine. Expression of TNF-α and IL-10 in microglia was elevated to protective levels by neuron-derived IgG at a physiologic level via the FcγR I and TLR4 pathways and microglial activation could be attenuated by IgG blocking. All these data suggested that neuron-derived IgG may exert a self-protective function by activating microglia properly, and IgG may be involved in maintaining immunity homeostasis in the central nervous system and serve as an active factor under pathological conditions such as Parkinson's disease. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Delta-like 1 participates in the specification of ventral midbrain progenitor derived dopaminergic neurons

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Bauer, Matthias; Szulc, Jolanta; Meyer, Morten

2008-01-01

function of Dlk1 in VM neuron development, we investigated the effect of soluble Dlk1 protein as well as the intrinsic Dlk1 function in the course of VM progenitor expansion and dopaminergic (DA) neuron differentiation in vitro. Dlk1 treatment during expansion increased DA progenitor proliferation...

Oleuropein Prevents Neuronal Death, Mitigates Mitochondrial Superoxide Production and Modulates Autophagy in a Dopaminergic Cellular Model

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Imène Achour

2016-08-01

Full Text Available Parkinson’s disease (PD is a progressive neurodegenerative disorder, primarily affecting dopaminergic neurons in the substantia nigra. There is currently no cure for PD and present medications aim to alleviate clinical symptoms, thus prevention remains the ideal strategy to reduce the prevalence of this disease. The goal of this study was to investigate whether oleuropein (OLE, the major phenolic compound in olive derivatives, may prevent neuronal degeneration in a cellular dopaminergic model of PD, differentiated PC12 cells exposed to the potent parkinsonian toxin 6-hydroxydopamine (6-OHDA. We also investigated OLE’s ability to mitigate mitochondrial oxidative stress and modulate the autophagic flux. Our results obtained by measuring cytotoxicity and apoptotic events demonstrate that OLE significantly decreases neuronal death. OLE could also reduce mitochondrial production of reactive oxygen species resulting from blocking superoxide dismutase activity. Moreover, quantification of autophagic and acidic vesicles in the cytoplasm alongside expression of specific autophagic markers uncovered a regulatory role for OLE against autophagic flux impairment induced by bafilomycin A1. Altogether, our results define OLE as a neuroprotective, anti-oxidative and autophagy-regulating molecule, in a neuronal dopaminergic cellular model.

The cellular and Genomic response of rat dopaminergic neurons (N27) to coated nanosilver

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This study examined if nanosilver (nanoAg) of different sizes and coatings were differentially toxic to oxidative stress-sensitive neurons. N27 rat dopaminergic neurons were exposed (0.5-5ppm) to a set of nanoAg of different sizes (10nm, 75nm) and coatings (PVP, citrate) and thei...

The role of alpha-synuclein in melanin synthesis in melanoma and dopaminergic neuronal cells.

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Tianhong Pan

Full Text Available The relatively high co-occurrence of Parkinson's disease (PD and melanoma has been established by a large number of epidemiological studies. However, a clear biological explanation for this finding is still lacking. Ultra-violet radiation (UVR-induced skin melanin synthesis is a defense mechanism against UVR-induced damage relevant to the initiation of melanoma, whereas, increased neuromelanin (NM, the melanin synthesized in dopaminergic neurons, may enhance the susceptibility to oxidative stress-induced neuronal injury relevant to PD. SNCA is a PD-causing gene coding for alpha-Synuclein (α-Syn that expresses not only in brain, but also in skin as well as in tumors, such as melanoma. The findings that α-Syn can interact with tyrosinase (TYR and inhibit tyrosine hydroxylase (TH, both of which are enzymes involved in the biosynthesis of melanin and dopamine (DA, led us to propose that α-Syn may participate in the regulation of melanin synthesis. In this study, by applying ultraviolet B (UVB light, a physiologically relevant stimulus of melanogenesis, we detected melanin synthesis in A375 and SK-MEL-28 melanoma cells and in SH-SY5Y and PC12 dopaminergic neuronal cells and determined effects of α-Syn on melanin synthesis. Our results showed that UVB light exposure increased melanin synthesis in all 4 cell lines. However, we found that α-Syn expression reduced UVB light-induced increase of melanin synthesis and that melanin content was lower when melanoma cells were expressed with α-Syn, indicating that α-Syn may have inhibitory effects on melanin synthesis in melanoma cells. Different from melanoma cells, the melanin content was higher in α-Syn-over-expressed dopaminergic neuronal SH-SY5Y and PC12 cells, cellular models of PD, than that in non-α-Syn-expressed control cells. We concluded that α-Syn could be one of the points responsible for the positive association between PD and melanoma via its differential roles in melanin synthesis in

Alkaloids from piper longum protect dopaminergic neurons against inflammation-mediated damage induced by intranigral injection of lipopolysaccharide.

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He, Huan; Guo, Wei-Wei; Xu, Rong-Rong; Chen, Xiao-Qing; Zhang, Nan; Wu, Xia; Wang, Xiao-Min

2016-10-24

Alkaloids from Piper longum (PLA), extracted from P. longum, have potent anti-inflammatory effects. The aim of this study was to investigate whether PLA could protect dopaminergic neurons against inflammation-mediated damage by inhibiting microglial activation using a lipopolysaccharide (LPS)-induced dopaminergic neuronal damage rat model. The animal behaviors of rotational behavior, rotarod test and open-field test were investigated. The survival ratio of dopaminergic neurons and microglial activation were examined. The dopamine (DA) and its metabolite were detected by high performance liquid chromatography (HPLC). The effects of PLA on the expression of interleukin (IL)-6, interleukin (IL)-1β and tumor necrosis factor (TNF)-α were detected by enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) and nitric oxide (NO) were also estimated. We showed that the survival ratio of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the substantia nigra pars compacta (SNpc) and DA content in the striatum were reduced after a single intranigral dose of LPS (10 μg) treatment. The survival rate of TH-ir neurons in the SNpc and DA levels in the striatum were significantly improved after treatment with PLA for 6 weeks. The over-activated microglial cells were suppressed by PLA treatment. We also observed that the levels of inflammatory cytokines, including TNF-α, IL-6 and IL-1β were decreased and the excessive production of ROS and NO were abolished after PLA treatment. Therefore, the behavioral dysfunctions induced by LPS were improved after PLA treatment. This study suggests that PLA plays a significant role in protecting dopaminergic neurons against inflammatory reaction induced damage.

3-hydroxymorphinan is neurotrophic to dopaminergic neurons and is also neuroprotective against LPS-induced neurotoxicity.

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Zhang, Wei; Qin, Liya; Wang, Tongguang; Wei, Sung-Jen; Gao, Hui-ming; Liu, Jie; Wilson, Belinda; Liu, Bin; Zhang, Wanqin; Kim, Hyoung-Chun; Hong, Jau-Shyong

2005-03-01

The purpose of this study was to develop a novel therapy for Parkinson's disease (PD). We recently reported that dextromethorphan (DM), an active ingredient in a variety of widely used anticough remedies, protected dopaminergic neurons in rat primary mesencephalic neuron-glia cultures against lipopolysaccharide (LPS)-mediated degeneration and provided potent protection for dopaminergic neurons in a MPTP mouse model. The underlying mechanism for the protective effect of DM was attributed to its anti-inflammatory activity through inhibition of microglia activation. In an effort to develop more potent compounds for the treatment of PD, we have screened a series of analogs of DM, and 3-hydroxymorphinan (3-HM) emerged as a promising candidate for this purpose. Our study using primary mesencephalic neuron-glia cultures showed that 3-HM provided more potent neuroprotection against LPS-induced dopaminergic neurotoxicity than its parent compound. The higher potency of 3-HM was attributed to its neurotrophic effect in addition to the anti-inflammatory effect shared by both DM and 3-HM. First, we showed that 3-HM exerted potent neuroprotective and neurotrophic effects on dopaminergic neurons in rat primary mesencephalic neuron-glia cultures treated with LPS. The neurotrophic effect of 3-HM was glia-dependent since 3-HM failed to show any protective effect in the neuron-enriched cultures. We subsequently demonstrated that it was the astroglia, not the microglia, that contributed to the neurotrophic effect of 3-HM. This conclusion was based on the reconstitution studies, in which we added different percentages of microglia (10-20%) or astroglia (40-50%) back to the neuron-enriched cultures and found that 3-HM was neurotrophic after the addition of astroglia, but not microglia. Furthermore, 3-HM-treated astroglia-derived conditioned media exerted a significant neurotrophic effect on dopaminergic neurons. It appeared likely that 3-HM caused the release of neurotrophic factor

Effect of inhibition of fatty acid amide hydrolase on MPTP-induced dopaminergic neuronal damage.

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Viveros-Paredes, J M; Gonzalez-Castañeda, R E; Escalante-Castañeda, A; Tejeda-Martínez, A R; Castañeda-Achutiguí, F; Flores-Soto, M E

2017-01-16

Parkinson's disease (PD) is a neurodegenerative disorder characterised by balance problems, muscle rigidity, and slow movement due to low dopamine levels and loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The endocannabinoid system is known to modulate the nigrostriatal pathway through endogenous ligands such as anandamide (AEA), which is hydrolysed by fatty acid amide hydrolase (FAAH). The purpose of this study was to increase AEA levels using FAAH inhibitor URB597 to evaluate the modulatory effect of AEA on dopaminergic neuronal death induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Our study included 4 experimental groups (n = 6 mice per group): a control group receiving no treatment, a group receiving URB597 (0.2mg/kg) every 3 days for 30 days, a group treated with MPTP (30mg/kg) for 5 days, and a group receiving URB597 and subsequently MPTP injections. Three days after the last dose, we conducted a series of behavioural tests (beam test, pole test, and stride length test) to compare motor coordination between groups. We subsequently analysed immunoreactivity of dopaminergic cells and microglia in the SNpc and striatum. Mice treated with URB597 plus MPTP were found to perform better on behavioural tests than mice receiving MPTP only. According to the immunohistochemistry study, mice receiving MPTP showed fewer dopaminergic cells and fibres in the SNpc and striatum. Animals treated with URB597 plus MPTP displayed increased tyrosine hydroxylase immunoreactivity compared to those treated with MPTP only. Regarding microglial immunoreactivity, the group receiving MPTP showed higher Iba1 immunoreactivity in the striatum and SNpc than did the group treated with URB597 plus MPTP. Our results show that URB597 exerts a protective effect since it inhibits dopaminergic neuronal death, decreases microglial immunoreactivity, and improves MPTP-induced motor alterations. Copyright © 2016 Sociedad Española de Neurología. Publicado

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) Is Selectively Toxic to Primary Dopaminergic Neurons In Vitro

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Griggs, Amy M.; Agim, Zeynep S.; Mishra, Vartika R.; Tambe, Mitali A.; Director-Myska, Alison E.; Turteltaub, Kenneth W.; McCabe, George P.; Rochet, Jean-Christophe; Cannon, Jason R.

2014-01-01

Parkinson's disease (PD) is the second most common neurodegenerative disease. Much data has linked the etiology of PD to a variety of environmental factors. The majority of cases are thought to arise from a combination of genetic susceptibility and environmental factors. Chronic exposures to dietary factors, including meat, have been identified as potential risk factors. Although heterocyclic amines that are produced during high-temperature meat cooking are known to be carcinogenic, their effect on the nervous system has yet to be studied in depth. In this study, we investigated neurotoxic effects of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a highly abundant heterocyclic amine in cooked meat, in vitro. We tested toxicity of PhIP and the two major phase I metabolites, N-OH-PhIP and 4′-OH-PhIP, using primary mesencephalic cultures from rat embryos. This culture system contains both dopaminergic and nondopaminergic neurons, which allows specificity of neurotoxicity to be readily examined. We find that exposure to PhIP or N-OH-PhIP is selectively toxic to dopaminergic neurons in primary cultures, resulting in a decreased percentage of dopaminergic neurons. Neurite length is decreased in surviving dopaminergic neurons. Exposure to 4′-OH-PhIP did not produce significant neurotoxicity. PhIP treatment also increased formation of oxidative damage markers, 4-hydroxy-2-nonenal (HNE) and 3-nitrotyrosine in dopaminergic neurons. Pretreatment with N-acetylcysteine was protective. Finally, treatment with blueberry extract, a dietary factor with known antioxidant and other protective mechanisms, prevented PhIP-induced toxicity. Collectively, our study suggests, for the first time, that PhIP is selectively toxic to dopaminergic neurons likely through inducing oxidative stress. PMID:24718704

Dopaminergic-like neurons derived from oral mucosa stem cells by developmental cues improve symptoms in the hemi-parkinsonian rat model.

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Javier Ganz

Full Text Available Achieving safe and readily accessible sources for cell replacement therapy in Parkinson's disease (PD is still a challenging unresolved issue. Recently, a primitive neural crest stem cell population (hOMSC was isolated from the adult human oral mucosa and characterized in vitro and in vivo. In this study we assessed hOMSC ability to differentiate into dopamine-secreting cells with a neuronal-dopaminergic phenotype in vitro in response to dopaminergic developmental cues and tested their therapeutic potential in the hemi-Parkinsonian rat model. We found that hOMSC express constitutively a repertoire of neuronal and dopaminergic markers and pivotal transcription factors. Soluble developmental factors induced a reproducible neuronal-like morphology in the majority of hOMSC, downregulated stem cells markers, upregulated the expression of the neuronal and dopaminergic markers that resulted in dopamine release capabilities. Transplantation of these dopaminergic-induced hOMSC into the striatum of hemi-Parkinsonian rats improved their behavioral deficits as determined by amphetamine-induced rotational behavior, motor asymmetry and motor coordination tests. Human TH expressing cells and increased levels of dopamine in the transplanted hemispheres were observed 10 weeks after transplantation. These results demonstrate for the first time that soluble factors involved in the development of DA neurons, induced a DA phenotype in hOMSC in vitro that significantly improved the motor function of hemiparkinsonian rats. Based on their neural-related origin, their niche accessibility by minimal-invasive procedures and their propensity for DA differentiation, hOMSC emerge as an attractive tool for autologous cell replacement therapy in PD.

Towards a Non-Human Primate Model of Alpha-Synucleinopathy for Development of Therapeutics for Parkinson's Disease: Optimization of AAV1/2 Delivery Parameters to Drive Sustained Expression of Alpha Synuclein and Dopaminergic Degeneration in Macaque.

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James B Koprich

Full Text Available Recent failures in clinical trials for disease modification in Parkinson's disease have highlighted the need for a non-human primate model of the synucleinopathy underpinning dopaminergic neuron degeneration. The present study was defined to begin the development of such a model in cynomolgus macaque. We have validated surgical and vector parameters to define a means to provide a robust over-expression of alpha-synuclein which is associated with Lewy-like pathology and robust degeneration of the nigrostriatal pathway. Thus, an AAV1/2 vector incorporating strong transcription and transduction regulatory elements was used to deliver the gene for the human A53T mutation of alpha-synuclein. When injected into 4 sites within each substantia nigra (7 μl per site, 1.7 x 1012 gp/ml, this vector provided expression lasting at least 4 months, and a 50% loss of nigral dopaminergic neurons and a 60% reduction in striatal dopamine. Further studies will be required to develop this methodology into a validated model of value as a drug development platform.

Lesion of the locus coeruleus aggravates dopaminergic neuron degeneration by modulating microglial function in mouse models of Parkinson׳s disease.

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Yao, Ning; Wu, Yanhong; Zhou, Yan; Ju, Lili; Liu, Yujun; Ju, Rongkai; Duan, Deyi; Xu, Qunyuan

2015-11-02

The degeneration of noradrenergic neurons in the locus coeruleus (LC) commonly occurs in patients with Parkinson's disease (PD), which is characterized by a selective injury of dopaminergic neurons in the substantia nigra (SN). The pathological impact of the LC on the SN in the disease is unknown. In the present study, we used a noradrenergic toxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4), to deplete noradrenaline (NA) derived from the LC to explore its influence on degeneration or injury of dopaminergic neurons in the SN in mouse model produced by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or lipopolysaccharide (LPS). Our results demonstrated that lesion of the LC could change microglial function in the brain, which led to enhanced or prolonged expression of pro-inflammatory cytokines, diminished neurotrophic factors, and weakened ability of anti-oxidation in the SN. The in vitro experiments further confirmed that NA could reduce the inflammatory reaction of microglia. The selective injury of dopaminergic neurons by inflammation, however, was due to the inflammation in different brain regions rather than the depletion of NA. Our results indicate that the lesion in the LC is an important factor in promoting dopaminergic neuron degeneration by impacting the function of microglia in the midbrain. Copyright © 2015 Elsevier B.V. All rights reserved.

Subthalamic nucleus electrical stimulation modulates calcium activity of nigral astrocytes.

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Elodie Barat

Full Text Available The substantia nigra pars reticulata (SNr is a major output nucleus of the basal ganglia, delivering inhibitory efferents to the relay nuclei of the thalamus. Pathological hyperactivity of SNr neurons is known to be responsible for some motor disorders e.g. in Parkinson's disease. One way to restore this pathological activity is to electrically stimulate one of the SNr input, the excitatory subthalamic nucleus (STN, which has emerged as an effective treatment for parkinsonian patients. The neuronal network and signal processing of the basal ganglia are well known but, paradoxically, the role of astrocytes in the regulation of SNr activity has never been studied.In this work, we developed a rat brain slice model to study the influence of spontaneous and induced excitability of afferent nuclei on SNr astrocytes calcium activity. Astrocytes represent the main cellular population in the SNr and display spontaneous calcium activities in basal conditions. Half of this activity is autonomous (i.e. independent of synaptic activity while the other half is dependent on spontaneous glutamate and GABA release, probably controlled by the pace-maker activity of the pallido-nigral and subthalamo-nigral loops. Modification of the activity of the loops by STN electrical stimulation disrupted this astrocytic calcium excitability through an increase of glutamate and GABA releases. Astrocytic AMPA, mGlu and GABA(A receptors were involved in this effect.Astrocytes are now viewed as active components of neural networks but their role depends on the brain structure concerned. In the SNr, evoked activity prevails and autonomous calcium activity is lower than in the cortex or hippocampus. Our data therefore reflect a specific role of SNr astrocytes in sensing the STN-GPe-SNr loops activity and suggest that SNr astrocytes could potentially feedback on SNr neuronal activity. These findings have major implications given the position of SNr in the basal ganglia network.

Subthalamic nucleus electrical stimulation modulates calcium activity of nigral astrocytes.

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Barat, Elodie; Boisseau, Sylvie; Bouyssières, Céline; Appaix, Florence; Savasta, Marc; Albrieux, Mireille

2012-01-01

The substantia nigra pars reticulata (SNr) is a major output nucleus of the basal ganglia, delivering inhibitory efferents to the relay nuclei of the thalamus. Pathological hyperactivity of SNr neurons is known to be responsible for some motor disorders e.g. in Parkinson's disease. One way to restore this pathological activity is to electrically stimulate one of the SNr input, the excitatory subthalamic nucleus (STN), which has emerged as an effective treatment for parkinsonian patients. The neuronal network and signal processing of the basal ganglia are well known but, paradoxically, the role of astrocytes in the regulation of SNr activity has never been studied. In this work, we developed a rat brain slice model to study the influence of spontaneous and induced excitability of afferent nuclei on SNr astrocytes calcium activity. Astrocytes represent the main cellular population in the SNr and display spontaneous calcium activities in basal conditions. Half of this activity is autonomous (i.e. independent of synaptic activity) while the other half is dependent on spontaneous glutamate and GABA release, probably controlled by the pace-maker activity of the pallido-nigral and subthalamo-nigral loops. Modification of the activity of the loops by STN electrical stimulation disrupted this astrocytic calcium excitability through an increase of glutamate and GABA releases. Astrocytic AMPA, mGlu and GABA(A) receptors were involved in this effect. Astrocytes are now viewed as active components of neural networks but their role depends on the brain structure concerned. In the SNr, evoked activity prevails and autonomous calcium activity is lower than in the cortex or hippocampus. Our data therefore reflect a specific role of SNr astrocytes in sensing the STN-GPe-SNr loops activity and suggest that SNr astrocytes could potentially feedback on SNr neuronal activity. These findings have major implications given the position of SNr in the basal ganglia network.

Neuroprotective effects of phytochemicals on dopaminergic neuron cultures.

Science.gov (United States)

Sandoval-Avila, S; Diaz, N F; Gómez-Pinedo, U; Canales-Aguirre, A A; Gutiérrez-Mercado, Y K; Padilla-Camberos, E; Marquez-Aguirre, A L; Díaz-Martínez, N E

2016-06-21

Parkinson's disease is a progressive neurodegenerative disorder characterised by a loss of dopaminergic neurons in the substantia nigra pars compacta, which results in a significant decrease in dopamine levels and consequent functional motor impairment. Although its aetiology is not fully understood, several pathogenic mechanisms, including oxidative stress, have been proposed. Current therapeutic approaches are based on dopamine replacement drugs; these agents, however, are not able to stop or even slow disease progression. Novel therapeutic approaches aimed at acting on the pathways leading to neuronal dysfunction and death are under investigation. In recent years, such natural molecules as polyphenols, alkaloids, and saponins have been shown to have a neuroprotective effect due to their antioxidant and anti-inflammatory properties. The aim of our review is to analyse the most relevant studies worldwide addressing the benefits of some phytochemicals used in in vitro models of Parkinson's disease. Copyright © 2016 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.

Nogo-receptor 1 antagonization in combination with neurotrophin-4/5 is not superior to single factor treatment in promoting survival and morphological complexity of cultured dopaminergic neurons.

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Seiler, Stefanie; Di Santo, Stefano; Sahli, Sebastian; Andereggen, Lukas; Widmer, Hans Rudolf

2017-08-01

Cell transplantation using ventral mesencephalic tissue is an experimental approach to treat Parkinson's disease. This approach is limited by poor survival of the transplants and the high number of dopaminergic neurons needed for grafting. Increasing the yield of dopaminergic neurons in donor tissue is of great importance. We have previously shown that antagonization of the Nogo-receptor 1 by NEP1-40 promoted survival of cultured dopaminergic neurons and exposure to neurotrophin-4/5 increased dopaminergic cell densities in organotypic midbrain cultures. We investigated whether a combination of both treatments offers a novel tool to further improve dopaminergic neuron survival. Rat embryonic ventral mesencephalic neurons grown as organotypic free-floating roller tube or primary dissociated cultures were exposed to neurotrophin-4/5 and NEP1-40. The combined and single factor treatment resulted in significantly higher numbers of tyrosine hydroxylase positive neurons compared to controls. Significantly stronger tyrosine hydroxylase signal intensity was detected by Western blotting in the combination-treated cultures compared to controls but not compared to single factor treatments. Neurotrophin-4/5 and the combined treatment showed significantly higher signals for the neuronal marker microtubule-associated protein 2 in Western blots compared to control while no effects were observed for the astroglial marker glial fibrillary acidic protein between groups, suggesting that neurotrophin-4/5 targets mainly neuronal cells. Finally, NEP1-40 and the combined treatment significantly augmented tyrosine hydroxylase positive neurite length. Summarizing, our findings substantiate that antagonization of the Nogo-receptor 1 promotes dopaminergic neurons but does not further increase the yield of dopaminergic neurons and their morphological complexity when combined with neurotrophin-4/5 hinting to the idea that these treatments might exert their effects by activating common

The rise and fall of mesodiencephalic dopaminergic neurons : Molecular programming by transcription factors Engrailed 1, Pitx3, and Nkx2.9 during the development of mesodiencephalic neurons

NARCIS (Netherlands)

Kouwenhoven, W.M.

2016-01-01

The mid- and hindbrain harbor two essential monoaminergic neuronal populations: the mesodiencephalic dopaminergic (mdDA) neurons in the midbrain and the serotonergic (5HT) neurons in the hindbrain. Both systems innervate multiple regions in the forebrain and are involved in the guidance of our mood,

Docosahexaenoic acid prevents paraquat-induced reactive oxygen species production in dopaminergic neurons via enhancement of glutathione homeostasis

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Lee, Hyoung Jun; Han, Jeongsu; Jang, Yunseon; Kim, Soo Jeong; Park, Ji Hoon; Seo, Kang Sik [Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon (Korea, Republic of); Jeong, Soyeon; Shin, Soyeon; Lim, Kyu [Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon (Korea, Republic of); Infection Signaling Network Research Center, Chungnam National University, Daejeon (Korea, Republic of); Heo, Jun Young, E-mail: junyoung3@gmail.com [Brainscience Institute, Chungnam National University, Daejeon (Korea, Republic of); Kweon, Gi Ryang, E-mail: mitochondria@cnu.ac.kr [Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon (Korea, Republic of); Infection Signaling Network Research Center, Chungnam National University, Daejeon (Korea, Republic of)

2015-01-30

Highlights: • DHA prevents PQ-induced dopaminergic neuronal loss via decreasing of excessive ROS. • DHA increases GR and GCLm derivate GSH pool by enhancement of Nrf2 expression. • Protective mechanism is removal of PQ-induced ROS via DHA-dependent GSH pool. • DHA may be a good preventive strategy for Parkinson’s disease (PD) therapy. - Abstract: Omega-3 polyunsaturated fatty acid levels are reduced in the substantia nigra area in Parkinson’s disease patients and animal models, implicating docosahexaenoic acid (DHA) as a potential treatment for preventing Parkinson’s disease and suggesting the need for investigations into how DHA might protect against neurotoxin-induced dopaminergic neuron loss. The herbicide paraquat (PQ) induces dopaminergic neuron loss through the excessive production of reactive oxygen species (ROS). We found that treatment of dopaminergic SN4741 cells with PQ reduced cell viability in a dose-dependent manner, but pretreatment with DHA ameliorated the toxic effect of PQ. To determine the toxic mechanism of PQ, we measured intracellular ROS content in different organelles with specific dyes. As expected, all types of ROS were increased by PQ treatment, but DHA pretreatment selectively decreased cytosolic hydrogen peroxide content. Furthermore, DHA treatment-induced increases in glutathione reductase and glutamate cysteine ligase modifier subunit (GCLm) mRNA expression were positively correlated with glutathione (GSH) content. Consistent with this increase in GCLm mRNA levels, Western blot analysis revealed that DHA pretreatment increased nuclear factor-erythroid 2 related factor 2 (Nrf2) protein levels. These findings indicate that DHA prevents PQ-induced neuronal cell loss by enhancing Nrf2-regulated GSH homeostasis.

Docosahexaenoic acid prevents paraquat-induced reactive oxygen species production in dopaminergic neurons via enhancement of glutathione homeostasis

International Nuclear Information System (INIS)

Lee, Hyoung Jun; Han, Jeongsu; Jang, Yunseon; Kim, Soo Jeong; Park, Ji Hoon; Seo, Kang Sik; Jeong, Soyeon; Shin, Soyeon; Lim, Kyu; Heo, Jun Young; Kweon, Gi Ryang

2015-01-01

Highlights: • DHA prevents PQ-induced dopaminergic neuronal loss via decreasing of excessive ROS. • DHA increases GR and GCLm derivate GSH pool by enhancement of Nrf2 expression. • Protective mechanism is removal of PQ-induced ROS via DHA-dependent GSH pool. • DHA may be a good preventive strategy for Parkinson’s disease (PD) therapy. - Abstract: Omega-3 polyunsaturated fatty acid levels are reduced in the substantia nigra area in Parkinson’s disease patients and animal models, implicating docosahexaenoic acid (DHA) as a potential treatment for preventing Parkinson’s disease and suggesting the need for investigations into how DHA might protect against neurotoxin-induced dopaminergic neuron loss. The herbicide paraquat (PQ) induces dopaminergic neuron loss through the excessive production of reactive oxygen species (ROS). We found that treatment of dopaminergic SN4741 cells with PQ reduced cell viability in a dose-dependent manner, but pretreatment with DHA ameliorated the toxic effect of PQ. To determine the toxic mechanism of PQ, we measured intracellular ROS content in different organelles with specific dyes. As expected, all types of ROS were increased by PQ treatment, but DHA pretreatment selectively decreased cytosolic hydrogen peroxide content. Furthermore, DHA treatment-induced increases in glutathione reductase and glutamate cysteine ligase modifier subunit (GCLm) mRNA expression were positively correlated with glutathione (GSH) content. Consistent with this increase in GCLm mRNA levels, Western blot analysis revealed that DHA pretreatment increased nuclear factor-erythroid 2 related factor 2 (Nrf2) protein levels. These findings indicate that DHA prevents PQ-induced neuronal cell loss by enhancing Nrf2-regulated GSH homeostasis

Structural plasticity in mesencephalic dopaminergic neurons produced by drugs of abuse: critical role of BDNF and dopamine.

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Ginetta eCollo

2014-11-01

Full Text Available Mesencephalic dopaminergic neurons were suggested to be a critical physiopathology substrate for addiction disorders. Among neuroadaptive processes to addictive drugs, structural plasticity has attracted attention. While structural plasticity occurs at both pre- and post-synaptic levels in the mesolimbic dopaminergic system, the present review focuses only on dopaminergic neurons. Exposures to addictive drugs determine two opposite structural responses, hypothrophic plasticity produced by opioids and cannabinoids (in particular during the early withdrawal phase and hypertrophic plasticity, mostly driven by psychostimulants and nicotine. In vitro and in vivo studies indentified BDNF and extracellular dopamine as two critical factors in determining structural plasticity, the two molecules sharing similar intracellular pathways involved in cell soma and dendrite growth, the MEK-ERK1/2 and the PI3K-Akt-mTOR, via preferential activation of TrkB and dopamine D3 receptors, respectively. At present information regarding specific structural changes associated to the various stages of the addiction cycle is incomplete. Encouraging neuroimaging data in humans indirectly support the preclinical evidence of hypotrophic and hypertrophic effects, suggesting a possible differential engagement of dopamine neurons in parallel and partially converging circuits controlling motivation, stress and emotions.

Efferent connections and nigral afferents of the nucleus accumbens septi in the rat

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Nauta, W J.H.; Smith, G P; Faull, R L.M.; Domesick, V B [Massachusetts Inst. of Tech., Cambridge (USA). Dept. of Psychology

1978-01-01

The results of this study by the methods of autoradiographic fiber-tracing and retrograde cell-labelling confirm earlier reports of accumbens projections to the globus pallidus and to dorsal strata of the medial half of the substantia nigra. Also in accord with previous autoradiographic evidence, sparser projections could be traced to a variety of subcortical structures implicated in the circuitry of the limbic system: bed nucleus of the stria terminalis, septum, preoptic region, hypothalamus, ventral tegmental area, nuclei paratenialis and mediodorsalis thalami, and lateral habenular nucleus. Contrary to earlier reports, striatopallidal fibers from the accumbens were found to be distributed largely to the subcommissural part of the external pallidal segment and to avoid almost entirely the internal pallidal segment. Mesencephalic projections from the accumbens largely coincide with those from the preoptic region and hypothalamus; like the latter they prominantly involve the region of the out-lying nigral cell groups A10 and A8 and extend caudally beyond the nigral complex to the cuneiform and parabrachial regions of the tegmentum as well as to caudoventral parts of the central grey substance. Horseradish peroxidase injected into the nucleus accumbens labels numerous neurons in the region of cell group A10 and in the supralemniscal 'retrorubral nucleus', but only sporadic cells in the pars compacta of the substantia nigra proper. It thus appears that the accumbens projects to a region of the nigral complex considerably larger than that from which it receives nigrostriatal fibers, and hence, that the nigro-striato-nigral circuit associated with the accumbens is not organized in a mode of simple point-for-point reciprocity. The problem of delimiting the accumbens from the rest of the striatum is examined by comparing cases of tracer injection into various discrete loci within the ventral zone of the striatum.

Interaction of Synuclein and Inflammation in Dopaminergic Neurodegeneration

Science.gov (United States)

2014-06-01

induces degeneration of dopaminergic neurons: implications for progression of Parkinson’s disease. Neurotox Res. 19: 63-72, (2011). Kalia, L. V., S...1998). Zhang J, Niu N, Wang M, McNutt MA, Zhang D, Zhang B, Lu S, Liu Y, Liu Z. Neuron-derived IgG protects dopaminergic neurons from insult by 6...AD_________________ Award Number: W81XWH-08-1-0465 TITLE: Interaction of Synuclein and Inflammation in Dopaminergic

Imaging of dopaminergic system in movement disorders

International Nuclear Information System (INIS)

Kim, Yu Kyeong; Kim, Sang Eun

2007-01-01

Parkinson's disease is a common neurodegenerative disorder that is mainly caused by dopaminergic neuron loss in the substantia nigra. Several radiopharmaceutics have been developed to evaluated the integrity of dopaminergic neuronal system. In vivo PET and SPECT imaging of presynaptic dopamine imaging are already applied to Parkinson's disease and other parkinsonism, and can demonstrate the dopaminergic dysfunction. This review summarized the use of the presynaptic dopaminergic imaging in PD as biomarkers in evaluation of disease progression as well as in diagnosis of PD

Direct lineage reprogramming of mouse fibroblasts to functional midbrain dopaminergic neuronal progenitors

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Han-Seop Kim

2014-01-01

Full Text Available The direct lineage reprogramming of somatic cells to other lineages by defined factors has led to innovative cell-fate-change approaches for providing patient-specific cells. Recent reports have demonstrated that four pluripotency factors (Oct4, Sox2, Klf4, and c-Myc are sufficient to directly reprogram fibroblasts to other specific cells, including induced neural stem cells (iNSCs. Here, we show that mouse fibroblasts can be directly reprogrammed into midbrain dopaminergic neuronal progenitors (DPs by temporal expression of the pluripotency factors and environment containing sonic hedgehog and fibroblast growth factor 8. Within thirteen days, self-renewing and functional induced DPs (iDPs were generated. Interestingly, the inhibition of both Jak and Gsk3β notably enhanced the iDP reprogramming efficiency. We confirmed the functionality of the iDPs by showing that the dopaminergic neurons generated from iDPs express midbrain markers, release dopamine, and show typical electrophysiological profiles. Our results demonstrate that the pluripotency factors-mediated direct reprogramming is an invaluable strategy for supplying functional and proliferating iDPs and may be useful for other neural progenitors required for disease modeling and cell therapies for neurodegenerative disorders.

Spread of neuronal degeneration in a dopaminergic, Lrrk-G2019S model of Parkinson disease

Science.gov (United States)

Hindle, Samantha J.; Elliott, Christopher J.H.

2013-01-01

Flies expressing the most common Parkinson disease (PD)-related mutation, LRRK2-G2019S, in their dopaminergic neurons show loss of visual function and degeneration of the retina, including mitochondrial abnormalities, apoptosis and autophagy. Since the photoreceptors that degenerate are not dopaminergic, this demonstrates nonautonomous degeneration, and a spread of pathology. This provides a model consistent with Braak’s hypothesis on progressive PD. The loss of visual function is specific for the G2019S mutation, implying the cause is its increased kinase activity, and is enhanced by increased neuronal activity. These data suggest novel explanations for the variability in animal models of PD. The specificity of visual loss to G2019S, coupled with the differences in neural firing rate, provide an explanation for the variability between people with PD in visual tests. PMID:23529190

MiR-34b/c Regulates Wnt1 and Enhances Mesencephalic Dopaminergic Neuron Differentiation

NARCIS (Netherlands)

De Gregorio, Roberto; Pulcrano, Salvatore; De Sanctis, Claudia; Volpicelli, Floriana; Guatteo, Ezia; von Oerthel, Lars; Latagliata, Emanuele Claudio; Esposito, Roberta; Piscitelli, Rosa Maria; Perrone-Capano, Carla; Costa, Valerio; Greco, Dario; Puglisi-Allegra, Stefano; Smidt, Marten P.; di Porzio, Umberto; Caiazzo, Massimiliano; Mercuri, Nicola Biagio; Li, Meng; Bellenchi, Gian Carlo

2018-01-01

The differentiation of dopaminergic neurons requires concerted action of morphogens and transcription factors acting in a precise and well-defined time window. Very little is known about the potential role of microRNA in these events. By performing a microRNA-mRNA paired microarray screening, we

Vanillin Protects Dopaminergic Neurons against Inflammation-Mediated Cell Death by Inhibiting ERK1/2, P38 and the NF-κB Signaling Pathway.

Science.gov (United States)

Yan, Xuan; Liu, Dian-Feng; Zhang, Xiang-Yang; Liu, Dong; Xu, Shi-Yao; Chen, Guang-Xin; Huang, Bing-Xu; Ren, Wen-Zhi; Wang, Wei; Fu, Shou-Peng; Liu, Ju-Xiong

2017-02-12

Neuroinflammation plays a very important role in the pathogenesis of Parkinson's disease (PD). After activation, microglia produce pro-inflammatory mediators that damage surrounding neurons. Consequently, the inhibition of microglial activation might represent a new therapeutic approach of PD. Vanillin has been shown to protect dopaminergic neurons, but the mechanism is still unclear. Herein, we further study the underlying mechanisms in lipopolysaccharide (LPS)-induced PD models. In vivo, we firstly established rat models of PD by unilateral injection of LPS into substantia nigra (SN), and then examined the role of vanillin in motor dysfunction, microglial activation and degeneration of dopaminergic neurons. In vitro, murine microglial BV-2 cells were treated with vanillin prior to the incubation of LPS, and then the inflammatory responses and the related signaling pathways were analyzed. The in vivo results showed that vanillin markedly improved the motor dysfunction, suppressed degeneration of dopaminergic neurons and inhibited microglial over-activation induced by LPS intranigral injection. The in vitro studies demonstrated that vanillin reduces LPS-induced expression of inducible nitric oxide (iNOS), cyclooxygenase-2 (COX-2), IL-1β, and IL-6 through regulating ERK1/2, p38 and NF-κB signaling. Collectively, these data indicated that vanillin has a role in protecting dopaminergic neurons via inhibiting inflammatory activation.

Dopaminergic neuronal loss, reduced neurite complexity and autophagic abnormalities in transgenic mice expressing G2019S mutant LRRK2.

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David Ramonet

2011-04-01

Full Text Available Mutations in the leucine-rich repeat kinase 2 (LRRK2 gene cause late-onset, autosomal dominant familial Parkinson's disease (PD and also contribute to idiopathic PD. LRRK2 mutations represent the most common cause of PD with clinical and neurochemical features that are largely indistinguishable from idiopathic disease. Currently, transgenic mice expressing wild-type or disease-causing mutants of LRRK2 have failed to produce overt neurodegeneration, although abnormalities in nigrostriatal dopaminergic neurotransmission have been observed. Here, we describe the development and characterization of transgenic mice expressing human LRRK2 bearing the familial PD mutations, R1441C and G2019S. Our study demonstrates that expression of G2019S mutant LRRK2 induces the degeneration of nigrostriatal pathway dopaminergic neurons in an age-dependent manner. In addition, we observe autophagic and mitochondrial abnormalities in the brains of aged G2019S LRRK2 mice and markedly reduced neurite complexity of cultured dopaminergic neurons. These new LRRK2 transgenic mice will provide important tools for understanding the mechanism(s through which familial mutations precipitate neuronal degeneration and PD.

Differentiation of Human Dental Pulp Stem Cells into Dopaminergic Neuron-like Cells in Vitro.

Science.gov (United States)

Chun, So Young; Soker, Shay; Jang, Yu-Jin; Kwon, Tae Gyun; Yoo, Eun Sang

2016-02-01

We investigated the potential of human dental pulp stem cells (hDPSCs) to differentiate into dopaminergic neurons in vitro as an autologous stem cell source for Parkinson's disease treatment. The hDPSCs were expanded in knockout-embryonic stem cell (KO-ES) medium containing leukemia inhibitory factor (LIF) on gelatin-coated plates for 3-4 days. Then, the medium was replaced with KO-ES medium without LIF to allow the formation of the neurosphere for 4 days. The neurosphere was transferred into ITS medium, containing ITS (human insulin-transferrin-sodium) and fibronectin, to select for Nestin-positive cells for 6-8 days. The cells were then cultured in N-2 medium containing basic fibroblast growth factor (FGF), FGF-8b, sonic hedgehog-N, and ascorbic acid on poly-l-ornithine/fibronectin-coated plates to expand the Nestin-positive cells for up to 2 weeks. Finally, the cells were transferred into N-2/ascorbic acid medium to allow for their differentiation into dopaminergic neurons for 10-15 days. The differentiation stages were confirmed by morphological, immunocytochemical, flow cytometric, real-time PCR, and ELISA analyses. The expressions of mesenchymal stem cell markers were observed at the early stages. The expressions of early neuronal markers were maintained throughout the differentiation stages. The mature neural markers showed increased expression from stage 3 onwards. The percentage of cells positive for tyrosine hydroxylase was 14.49%, and the amount was 0.526 ± 0.033 ng/mL at the last stage. hDPSCs can differentiate into dopaminergic neural cells under experimental cell differentiation conditions, showing potential as an autologous cell source for the treatment of Parkinson's disease.

[Effects of perinatal exposure to bisphenol A inducing dopaminergic neuronal cell to apoptosis happening in midbrain of male rat offspring].

Science.gov (United States)

Lin, Yong; Zhang, Hao; Wang, Wen-dong; Wu, De-sheng; Jiang, Song-hui; Qu, Wei-dong

2006-07-01

To investigate the mechanism and effect of rat perinatal exposure to bisphenol A (BPA) resulting in midbrain dopaminergic neuronal cell apoptosis and tyrosine hydroxylase expression of male offspring. Rat dams were randomLy divided into 4 groups on gestational day(GD) 10 and given orally the bisphenol A doses as 0, 0.5, 5, 50 mg/kg x d from GD10 to weaning. The brains of male offspring were obtained for detecting, with immunohistochemistry protocol, the Caspase-3, Bcl-2 and tyrosine hydroxylase expression in the midbrain on postnatal day 21 or 30 respectively, and the midbrain apoptotic neuronal cell were detected by TUNEL on PND21. The expression of Caspase-3 in the midbrain of rat male offspring were increased but bcl-2 were decreased on PND21 and 30, respectively. On PND21, apoptotic neuronal cell were found in the midbrain of high and medium doses groups. TH protein expression was decreased. Perinatal exposure to bisphenol A can induce the apoptosis of midbrain dopaminergic neuron in the male rat offspring even after weaning, and concomitantly decrease the midbrain TH immunoreactivity, this may cause the abnormal function of dopaminergic pathway of rat male offspring.

Wnt/beta-catenin signaling blockade promotes neuronal induction and dopaminergic differentiation in embryonic stem cells

Czech Academy of Sciences Publication Activity Database

Čajánek, L.; Ribeiro, D.; Liste, I.; Parish, C.L.; Bryja, Vítězslav; Arenas, E.

2009-01-01

Roč. 27, č. 12 (2009), s. 2917-2927 ISSN 1066-5099 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : embryonic stem cells * Wnt pathway * dopaminergic neurons Subject RIV: BO - Biophysics Impact factor: 7.747, year: 2009

The dopaminergic system in the aging brain of Drosophila

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Katherine E White

2010-12-01

Full Text Available Drosophila models of Parkinson’s disease are characterised by two principal phenotypes: the specific loss of dopaminergic neurons in the aging brain and defects in motor behavior. However, an age-related analysis of these baseline parameters in wildtype Drosophila is lacking. Here we analysed the dopaminergic system and motor behavior in aging Drosophila. Dopaminergic neurons in the adult brain can be grouped into bilateral symmetric clusters, each comprising a stereotypical number of cells. Analysis of TH>mCD8::GFP and cell type-specific MARCM clones revealed that dopaminergic neurons show cluster-specific, stereotypical projection patterns with terminal arborization in target regions that represent distinct functional areas of the adult brain. Target areas include the mushroom bodies, involved in memory formation and motivation, and the central complex, involved in the control of motor behavior, indicating that similar to the mammalian brain, dopaminergic neurons in the fly brain are involved in the regulation of specific behaviors. Behavioral analysis revealed that Drosophila show an age-related decline in startle-induced locomotion and negative geotaxis. Motion tracking however, revealed that walking activity and exploration behavior, but not centrophobism increase at late stages of life. Analysis of TH>Dcr2, mCD8::GFP revealed a specific effect of Dcr2 expression on walking activity but not on exploratory or centrophobic behavior, indicating that the siRNA pathway may modulate distinct dopaminergic behaviors in Drosophila. Moreover, dopaminergic neurons were maintained between early- and late life, as quantified by TH>mCD8::GFP and anti-TH labelling, indicating that adult onset, age-related degeneration of dopaminergic neurons does not occur in the aging brain of Drosophila. Taken together, our data establish baseline parameters in Drosophila for the study of Parkinson’s disease as well as other disorders affecting dopaminergic neurons

Alpha-synuclein cell-to-cell transfer and seeding in grafted dopaminergic neurons in vivo.

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Elodie Angot

Full Text Available Several people with Parkinson's disease have been treated with intrastriatal grafts of fetal dopaminergic neurons. Following autopsy, 10-22 years after surgery, some of the grafted neurons contained Lewy bodies similar to those observed in the host brain. Numerous studies have attempted to explain these findings in cell and animal models. In cell culture, α-synuclein has been found to transfer from one cell to another, via mechanisms that include exosomal transport and endocytosis, and in certain cases seed aggregation in the recipient cell. In animal models, transfer of α-synuclein from host brain cells to grafted neurons has been shown, but the reported frequency of the event has been relatively low and little is known about the underlying mechanisms as well as the fate of the transferred α-synuclein. We now demonstrate frequent transfer of α-synuclein from a rat brain engineered to overexpress human α-synuclein to grafted dopaminergic neurons. Further, we show that this model can be used to explore mechanisms underlying cell-to-cell transfer of α-synuclein. Thus, we present evidence both for the involvement of endocytosis in α-synuclein uptake in vivo, and for seeding of aggregation of endogenous α-synuclein in the recipient neuron by the transferred α-synuclein. Finally, we show that, at least in a subset of the studied cells, the transmitted α-synuclein is sensitive to proteinase K. Our new model system could be used to test compounds that inhibit cell-to-cell transfer of α-synuclein and therefore might retard progression of Parkinson neuropathology.

Zebrafish chemical screening reveals the impairment of dopaminergic neuronal survival by cardiac glycosides.

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Yaping Sun

Full Text Available Parkinson's disease is a neurodegenerative disorder characterized by the prominent degeneration of dopaminergic (DA neurons among other cell types. Here we report a first chemical screen of over 5,000 compounds in zebrafish, aimed at identifying small molecule modulators of DA neuron development or survival. We find that Neriifolin, a member of the cardiac glycoside family of compounds, impairs survival but not differentiation of both zebrafish and mammalian DA neurons. Cardiac glycosides are inhibitors of Na(+/K(+ ATPase activity and widely used for treating heart disorders. Our data suggest that Neriifolin impairs DA neuronal survival by targeting the neuronal enriched Na(+/K(+ ATPase α3 subunit (ATP1A3. Modulation of ionic homeostasis, knockdown of p53, or treatment with antioxidants protects DA neurons from Neriifolin-induced death. These results reveal a previously unknown effect of cardiac glycosides on DA neuronal survival and suggest that it is mediated through ATP1A3 inhibition, oxidative stress, and p53. They also elucidate potential approaches for counteracting the neurotoxicity of this valuable class of medications.

Dopamine receptor D3 expressed on CD4+ T cells favors neurodegeneration of dopaminergic neurons during Parkinson's disease.

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González, Hugo; Contreras, Francisco; Prado, Carolina; Elgueta, Daniela; Franz, Dafne; Bernales, Sebastián; Pacheco, Rodrigo

2013-05-15

Emerging evidence has demonstrated that CD4(+) T cells infiltrate into the substantia nigra (SN) in Parkinson's disease (PD) patients and in animal models of PD. SN-infiltrated CD4(+) T cells bearing inflammatory phenotypes promote microglial activation and strongly contribute to neurodegeneration of dopaminergic neurons. Importantly, altered expression of dopamine receptor D3 (D3R) in PBLs from PD patients has been correlated with disease severity. Moreover, pharmacological evidence has suggested that D3R is involved in IFN-γ production by human CD4(+) T cells. In this study, we examined the role of D3R expressed on CD4(+) T cells in neurodegeneration of dopaminergic neurons in the SN using a mouse model of PD. Our results show that D3R-deficient mice are strongly protected against loss of dopaminergic neurons and microglial activation during 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD. Notably, D3R-deficient mice become susceptible to MPTP-induced neurodegeneration and microglial activation upon transfer of wild-type (WT) CD4(+) T cells. Furthermore, RAG1 knockout mice, which are devoid of T cells and are resistant to MPTP-induced neurodegeneration, become susceptible to MPTP-induced loss of dopaminergic neurons when reconstituted with WT CD4(+) T cells but not when transferred with D3R-deficient CD4(+) T cells. In agreement, experiments analyzing activation and differentiation of CD4(+) T cells revealed that D3R favors both T cell activation and acquisition of the Th1 inflammatory phenotype. These findings indicate that D3R expressed on CD4(+) T cells plays a fundamental role in the physiopathology of MPTP-induced PD in a mouse model.

Vanillin Protects Dopaminergic Neurons against Inflammation-Mediated Cell Death by Inhibiting ERK1/2, P38 and the NF-κB Signaling Pathway

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Xuan Yan

2017-02-01

Full Text Available Neuroinflammation plays a very important role in the pathogenesis of Parkinson’s disease (PD. After activation, microglia produce pro-inflammatory mediators that damage surrounding neurons. Consequently, the inhibition of microglial activation might represent a new therapeutic approach of PD. Vanillin has been shown to protect dopaminergic neurons, but the mechanism is still unclear. Herein, we further study the underlying mechanisms in lipopolysaccharide (LPS-induced PD models. In vivo, we firstly established rat models of PD by unilateral injection of LPS into substantia nigra (SN, and then examined the role of vanillin in motor dysfunction, microglial activation and degeneration of dopaminergic neurons. In vitro, murine microglial BV-2 cells were treated with vanillin prior to the incubation of LPS, and then the inflammatory responses and the related signaling pathways were analyzed. The in vivo results showed that vanillin markedly improved the motor dysfunction, suppressed degeneration of dopaminergic neurons and inhibited microglial over-activation induced by LPS intranigral injection. The in vitro studies demonstrated that vanillin reduces LPS-induced expression of inducible nitric oxide (iNOS, cyclooxygenase-2 (COX-2, IL-1β, and IL-6 through regulating ERK1/2, p38 and NF-κB signaling. Collectively, these data indicated that vanillin has a role in protecting dopaminergic neurons via inhibiting inflammatory activation.

Efficient induction of dopaminergic neuron differentiation from induced pluripotent stem cells reveals impaired mitophagy in PARK2 neurons.

Science.gov (United States)

Suzuki, Sadafumi; Akamatsu, Wado; Kisa, Fumihiko; Sone, Takefumi; Ishikawa, Kei-Ichi; Kuzumaki, Naoko; Katayama, Hiroyuki; Miyawaki, Atsushi; Hattori, Nobutaka; Okano, Hideyuki

2017-01-29

Patient-specific induced pluripotent stem cells (iPSCs) show promise for use as tools for in vitro modeling of Parkinson's disease. We sought to improve the efficiency of dopaminergic (DA) neuron induction from iPSCs by the using surface markers expressed in DA progenitors to increase the significance of the phenotypic analysis. By sorting for a CD184 high /CD44 - fraction during neural differentiation, we obtained a population of cells that were enriched in DA neuron precursor cells and achieved higher differentiation efficiencies than those obtained through the same protocol without sorting. This high efficiency method of DA neuronal induction enabled reliable detection of reactive oxygen species (ROS) accumulation and vulnerable phenotypes in PARK2 iPSCs-derived DA neurons. We additionally established a quantitative system using the mt-mKeima reporter system to monitor mitophagy in which mitochondria fuse with lysosomes and, by combining this system with the method of DA neuronal induction described above, determined that mitophagy is impaired in PARK2 neurons. These findings suggest that the efficiency of DA neuron induction is important for the precise detection of cellular phenotypes in modeling Parkinson's disease. Copyright © 2016. Published by Elsevier Inc.

Amentoflavone protects dopaminergic neurons in MPTP-induced Parkinson's disease model mice through PI3K/Akt and ERK signaling pathways

International Nuclear Information System (INIS)

Cao, Qin; Qin, Liyue; Huang, Fei; Wang, Xiaoshuang; Yang, Liu; Shi, Hailian; Wu, Hui; Zhang, Beibei; Chen, Ziyu; Wu, Xiaojun

2017-01-01

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in substantia nigra pars compacta (SNpc). Mitochondrial dysfunction and cell apoptosis are suggested to be actively involved in the pathogenesis of PD. In the present study, the neuroprotective effect of amentoflavone (AF), a naturally occurring biflavonoid from Selaginella tamariscina, was examined in PD models both in vitro and in vivo. On SH-SY5Y cells, AF treatment dose-dependently reduced 1-methyl-4-phenylpyridinium (MPP + )-induced nuclear condensation and loss of cell viability without obvious cytotoxicity. It inhibited the activation of caspase-3 and p21 but increased the Bcl-2/Bax ratio. Further study disclosed that AF enhanced the phosphorylation of PI3K, Akt and ERK1/2 down-regulated by MPP + in SH-SY5Y cells, the effect of which could be blocked by LY294002, the inhibitor of PI3K. Consistently, AF alleviated the behavioral deterioration in pole and traction tests and rescued the loss of dopaminergic neurons in SNpc and fibers in striatum in methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced mice. It also could enhance the activation of PI3K and Akt as well as Bcl-2/Bax ratio in SN. Moreover, AF alleviated gliosis as well as the gene expression levels of IL-1β and iNOS in SN. Collectively, these results suggested that AF protected dopaminergic neurons against MPTP/MPP + -induced neurotoxicity, which might be mediated through activation of PI3K/Akt and ERK signaling pathways in dopaminergic neurons and attenuation of neuroinflammation. - Highlights: • AF protected dopaminergic neurons against MPTP/MPP + -induced neurotoxicity. • AF modulated PI3K/Akt and ERK signaling pathways. • AF could alleviate neuroinflammation in SN.

Amentoflavone protects dopaminergic neurons in MPTP-induced Parkinson's disease model mice through PI3K/Akt and ERK signaling pathways

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Cao, Qin; Qin, Liyue; Huang, Fei, E-mail: Fei_H@hotmail.com; Wang, Xiaoshuang; Yang, Liu; Shi, Hailian; Wu, Hui; Zhang, Beibei; Chen, Ziyu; Wu, Xiaojun, E-mail: xiaojunwu320@126.com

2017-03-15

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in substantia nigra pars compacta (SNpc). Mitochondrial dysfunction and cell apoptosis are suggested to be actively involved in the pathogenesis of PD. In the present study, the neuroprotective effect of amentoflavone (AF), a naturally occurring biflavonoid from Selaginella tamariscina, was examined in PD models both in vitro and in vivo. On SH-SY5Y cells, AF treatment dose-dependently reduced 1-methyl-4-phenylpyridinium (MPP{sup +})-induced nuclear condensation and loss of cell viability without obvious cytotoxicity. It inhibited the activation of caspase-3 and p21 but increased the Bcl-2/Bax ratio. Further study disclosed that AF enhanced the phosphorylation of PI3K, Akt and ERK1/2 down-regulated by MPP{sup +} in SH-SY5Y cells, the effect of which could be blocked by LY294002, the inhibitor of PI3K. Consistently, AF alleviated the behavioral deterioration in pole and traction tests and rescued the loss of dopaminergic neurons in SNpc and fibers in striatum in methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced mice. It also could enhance the activation of PI3K and Akt as well as Bcl-2/Bax ratio in SN. Moreover, AF alleviated gliosis as well as the gene expression levels of IL-1β and iNOS in SN. Collectively, these results suggested that AF protected dopaminergic neurons against MPTP/MPP{sup +}-induced neurotoxicity, which might be mediated through activation of PI3K/Akt and ERK signaling pathways in dopaminergic neurons and attenuation of neuroinflammation. - Highlights: • AF protected dopaminergic neurons against MPTP/MPP{sup +}-induced neurotoxicity. • AF modulated PI3K/Akt and ERK signaling pathways. • AF could alleviate neuroinflammation in SN.

Asymmetric cell division and Notch signaling specify dopaminergic neurons in Drosophila.

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Murni Tio

Full Text Available In Drosophila, dopaminergic (DA neurons can be found from mid embryonic stages of development till adulthood. Despite their functional involvement in learning and memory, not much is known about the developmental as well as molecular mechanisms involved in the events of DA neuronal specification, differentiation and maturation. In this report we demonstrate that most larval DA neurons are generated during embryonic development. Furthermore, we show that loss of function (l-o-f mutations of genes of the apical complex proteins in the asymmetric cell division (ACD machinery, such as inscuteable and bazooka result in supernumerary DA neurons, whereas l-o-f mutations of genes of the basal complex proteins such as numb result in loss or reduction of DA neurons. In addition, when Notch signaling is reduced or abolished, additional DA neurons are formed and conversely, when Notch signaling is activated, less DA neurons are generated. Our data demonstrate that both ACD and Notch signaling are crucial mechanisms for DA neuronal specification. We propose a model in which ACD results in differential Notch activation in direct siblings and in this context Notch acts as a repressor for DA neuronal specification in the sibling that receives active Notch signaling. Our study provides the first link of ACD and Notch signaling in the specification of a neurotransmitter phenotype in Drosophila. Given the high degree of conservation between Drosophila and vertebrate systems, this study could be of significance to mechanisms of DA neuronal differentiation not limited to flies.

Detection of tyrosine hydroxylase in dopaminergic neuron cell using gold nanoparticles-based barcode DNA.

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An, Jeung Hee; Oh, Byung-Keun; Choi, Jeong Woo

2013-04-01

Tyrosine hydroxylase, the rate-limiting enzyme of catecholamine biosysthesis, is predominantly expressed in several cell groups within the brain, including the dopaminergic neurons of the substantia nigra and ventral tegmental area. We evaluated the efficacy of this protein-detection method in detecting tyrosine hydroxylase in normal and oxidative stress damaged dopaminergic cells. In this study, a coupling of DNA barcode and bead-based immnunoassay for detecting tyrosine hydroxylaser with PCR-like sensitivity is reported. The method relies on magnetic nanoparticles with antibodies and nanoparticles that are encoded with DNA and antibodies that can sandwich the target protein captured by the nanoparticle-bound antibodies. The aggregate sandwich structures are magnetically separated from solution, and treated to remove the conjugated barcode DNA. The DNA barcodes were identified by PCR analysis. The concentration of tyrosine hydroxylase in dopaminergic cell can be easily and rapidly detected using bio-barcode assay. The bio-barcode assay is a rapid and high-throughput screening tool to detect of neurotransmitter such as dopamine.

A New Glucocerebrosidase Chaperone Reduces α-Synuclein and Glycolipid Levels in iPSC-Derived Dopaminergic Neurons from Patients with Gaucher Disease and Parkinsonism.

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Aflaki, Elma; Borger, Daniel K; Moaven, Nima; Stubblefield, Barbara K; Rogers, Steven A; Patnaik, Samarjit; Schoenen, Frank J; Westbroek, Wendy; Zheng, Wei; Sullivan, Patricia; Fujiwara, Hideji; Sidhu, Rohini; Khaliq, Zayd M; Lopez, Grisel J; Goldstein, David S; Ory, Daniel S; Marugan, Juan; Sidransky, Ellen

2016-07-13

Among the known genetic risk factors for Parkinson disease, mutations in GBA1, the gene responsible for the lysosomal disorder Gaucher disease, are the most common. This genetic link has directed attention to the role of the lysosome in the pathogenesis of parkinsonism. To study how glucocerebrosidase impacts parkinsonism and to evaluate new therapeutics, we generated induced human pluripotent stem cells from four patients with Type 1 (non-neuronopathic) Gaucher disease, two with and two without parkinsonism, and one patient with Type 2 (acute neuronopathic) Gaucher disease, and differentiated them into macrophages and dopaminergic neurons. These cells exhibited decreased glucocerebrosidase activity and stored the glycolipid substrates glucosylceramide and glucosylsphingosine, demonstrating their similarity to patients with Gaucher disease. Dopaminergic neurons from patients with Type 2 and Type 1 Gaucher disease with parkinsonism had reduced dopamine storage and dopamine transporter reuptake. Levels of α-synuclein, a protein present as aggregates in Parkinson disease and related synucleinopathies, were selectively elevated in neurons from the patients with parkinsonism or Type 2 Gaucher disease. The cells were then treated with NCGC607, a small-molecule noninhibitory chaperone of glucocerebrosidase identified by high-throughput screening and medicinal chemistry structure optimization. This compound successfully chaperoned the mutant enzyme, restored glucocerebrosidase activity and protein levels, and reduced glycolipid storage in both iPSC-derived macrophages and dopaminergic neurons, indicating its potential for treating neuronopathic Gaucher disease. In addition, NCGC607 reduced α-synuclein levels in dopaminergic neurons from the patients with parkinsonism, suggesting that noninhibitory small-molecule chaperones of glucocerebrosidase may prove useful for the treatment of Parkinson disease. Because GBA1 mutations are the most common genetic risk factor for

Activation of the HMGB1-RAGE axis upregulates TH expression in dopaminergic neurons via JNK phosphorylation.

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Kim, Soo Jeong; Ryu, Min Jeong; Han, Jeongsu; Jang, Yunseon; Kim, Jungim; Lee, Min Joung; Ryu, Ilhwan; Ju, Xianshu; Oh, Eungseok; Chung, Woosuk; Kweon, Gi Ryang; Heo, Jun Young

2017-11-04

The derangement of tyrosine hydroxylase (TH) activity reduces dopamine synthesis and is implicated in the pathogenesis of Parkinson's disease. However, the extracellular modulator and intracellular regulatory mechanisms of TH have yet to be identified. Recently, high-mobility group box 1 (HMGB1) was reported to be actively secreted from glial cells and is regarded as a mediator of dopaminergic neuronal loss. However, the mechanism for how HMGB1 affects TH expression, particularly through the receptor for advanced glycation endproducts (RAGE), has not yet been investigated. We found that recombinant HMGB1 (rHMGB1) upregulates TH mRNA expression via simultaneous activation of JNK phosphorylation, and this induction of TH expression is blocked by inhibitors of RAGE and JNK. To investigate how TH expression levels change through the HMGB1-RAGE axis as a result of MPP + toxicity, we co-treated SN4741 dopaminergic cells with MPP + and rHMGB1. rHMGB1 blocked the reduction of TH mRNA following MPP + treatment without altering cell survival rates. Our results suggest that HMGB1 upregulates TH expression to maintain dopaminergic neuronal function via activating RAGE, which is dependent on JNK phosphorylation. Copyright © 2017 Elsevier Inc. All rights reserved.

Exosomes from dental pulp stem cells rescue human dopaminergic neurons from 6-hydroxy-dopamine-induced apoptosis.

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Jarmalavičiūtė, Akvilė; Tunaitis, Virginijus; Pivoraitė, Ugnė; Venalis, Algirdas; Pivoriūnas, Augustas

2015-07-01

Stem cells derived from the dental pulp of human exfoliated deciduous teeth (SHEDs) have unique neurogenic properties that could be potentially exploited for therapeutic use. The importance of paracrine SHED signaling for neuro-regeneration has been recognized, but the exact mechanisms behind these effects are presently unknown. In the present study, we investigated the neuro-protective potential of exosomes and micro-vesicles derived from SHEDs on human dopaminergic neurons during oxidative stress-induced by 6-hydroxy-dopamine (6-OHDA). ReNcell VM human neural stem cells were differentiated into dopaminergic neurons and treated with 100 μmol/L of 6-OHDA alone or in combination with exosomes or micro-vesicles purified by ultracentrifugation from SHEDs cultivated in serum-free medium under two conditions: in standard two-dimensional culture flasks or on laminin-coated micro-carriers in a bioreactor. Real-time monitoring of apoptosis was performed with the use of time-lapse confocal microscopy and the CellEvent Caspase-3/7 green detection reagent. Exosomes but not micro-vesicles derived from SHEDs grown on the laminin-coated three-dimensional alginate micro-carriers suppressed 6-OHDA-induced apoptosis in dopaminergic neurons by approximately 80% throughout the culture period. Strikingly, no such effects were observed for the exosomes derived from SHEDs grown under standard culture conditions. Our results suggest that exosomes derived from SHEDs are considered as new potential therapeutic tool in the treatment of Parkinson's disease. Copyright © 2015 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Gamma neurons mediate dopaminergic input during aversive olfactory memory formation in Drosophila.

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Qin, Hongtao; Cressy, Michael; Li, Wanhe; Coravos, Jonathan S; Izzi, Stephanie A; Dubnau, Joshua

2012-04-10

Mushroom body (MB)-dependent olfactory learning in Drosophila provides a powerful model to investigate memory mechanisms. MBs integrate olfactory conditioned stimulus (CS) inputs with neuromodulatory reinforcement (unconditioned stimuli, US), which for aversive learning is thought to rely on dopaminergic (DA) signaling to DopR, a D1-like dopamine receptor expressed in MBs. A wealth of evidence suggests the conclusion that parallel and independent signaling occurs downstream of DopR within two MB neuron cell types, with each supporting half of memory performance. For instance, expression of the Rutabaga (Rut) adenylyl cyclase in γ neurons is sufficient to restore normal learning to rut mutants, whereas expression of Neurofibromatosis 1 (NF1) in α/β neurons is sufficient to rescue NF1 mutants. DopR mutations are the only case where memory performance is fully eliminated, consistent with the hypothesis that DopR receives the US inputs for both γ and α/β lobe traces. We demonstrate, however, that DopR expression in γ neurons is sufficient to fully support short- and long-term memory. We argue that DA-mediated CS-US association is formed in γ neurons followed by communication between γ and α/β neurons to drive consolidation. Copyright © 2012 Elsevier Ltd. All rights reserved.

γ neurons mediate dopaminergic input during aversive olfactory memory formation in Drosophila

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Qin, H.; Cressy, M.; Li, W.; Coravos, J.; Izzi, S.; Dubnau, J.

2012-01-01

SUMMARY Mushroom body (MB) dependent olfactory learning in Drosophila provides a powerful model to investigate memory mechanisms. MBs integrate olfactory conditioned stimuli (CS) inputs with neuromodulatory reinforcement (unconditioned stimuli, US) [1, 2], which for aversive learning is thought to rely on dopaminergic (DA) signaling [3–6] to DopR, a D1-like dopamine receptor expressed in MB [7, 8]. A wealth of evidence suggests the conclusion that parallel and independent signaling occurs downstream of DopR within two MB neuron cell types, with each supporting half of memory performance. For instance, expression of the rutabaga adenylyl cyclase (rut) in γ neurons is sufficient to restore normal learning to rut mutants [9] whereas expression of Neurofibromatosis I (NFI) in α/β neurons is sufficient to rescue NF1 mutants [10, 11]. DopR mutations are the only case where memory performance is fully eliminated [7], consistent with the hypothesis that DopR receives the US inputs for both γ and α/β lobe traces. We demonstrate, however, that DopR expression in γ neurons is sufficient to fully support short (STM) and long-term memory (LTM). We argue that DA-mediated CS-US association is formed in γ neurons followed by communication between γ and α/β neurons to drive consolidation. PMID:22425153

Protection against methamphetamine-induced neurotoxicity to neostriatal dopaminergic neurons by adenosine receptor activation.

Science.gov (United States)

Delle Donne, K T; Sonsalla, P K

1994-12-01

Methamphetamine (METH)-induced neurotoxicity to nigrostriatal dopaminergic neurons in experimental animals appears to have a glutamatergic component because blockade of N-methyl-D-aspartate receptors prevents the neuropathologic consequences. Because adenosine affords neuroprotection against various forms of glutamate-mediated neuronal damage, the present studies were performed to investigate whether adenosine plays a protective role in METH-induced toxicity. METH-induced decrements in neostriatal dopamine content and tyrosine hydroxylase activity in mice were potentiated by concurrent treatment with caffeine, a nonselective adenosine antagonist that blocks both A1 and A2 adenosine receptors. In contrast, chronic treatment of mice with caffeine through their drinking water for 4 weeks, which increased the number of adenosine A1 receptors in the neostriatum and frontal cortex, followed by drug washout, prevented the neurochemical changes produced by the treatment of mice with METH treatment. In contrast, this treatment did not prevent 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine-induced dopaminergic neurotoxicity. Furthermore, concurrent administration of cyclopentyladenosine, an adenosine A1 receptor agonist, attenuated the METH-induced neurochemical changes. This protection by cyclopentyladenosine was blocked by cyclopentyltheophylline, an A1 receptor antagonist. These results indicate that activation of A1 receptors can protect against METH-induced neurotoxicity in mice.

Neuroprotective effects of a brain permeant 6-aminoquinoxaline derivative in cell culture conditions that model the loss of dopaminergic neurons in Parkinson disease.

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Le Douaron, Gael; Schmidt, Fanny; Amar, Majid; Kadar, Hanane; Debortoli, Lucila; Latini, Alexandra; Séon-Méniel, Blandine; Ferrié, Laurent; Michel, Patrick Pierre; Touboul, David; Brunelle, Alain; Raisman-Vozari, Rita; Figadère, Bruno

2015-01-07

Parkinson disease is a neurodegenerative disorder of aging, characterized by disabling motor symptoms resulting from the loss of midbrain dopaminergic neurons and the decrease of dopamine in the striatum. Current therapies are directed at treating the symptoms but there is presently no cure for the disease. In order to discover neuroprotective compounds with a therapeutical potential, our research team has established original and highly regioselective methods for the synthesis of 2,3-disubstituted 6-aminoquinoxalines. To evaluate the neuroprotective activity of these molecules, we used midbrain cultures and various experimental conditions that promote dopaminergic cell loss. Among a series of 11 molecules, only compound MPAQ (2-methyl-3-phenyl-6-aminoquinoxaline) afforded substantial protection in a paradigm where dopaminergic neurons die spontaneously and progressively as they mature. Prediction of blood-brain barrier permeation by Quantitative Structure-Activity Relationship studies (QSARs) suggested that MPAQ was able to reach the brain parenchyma with sufficient efficacy. HPLC-MS/MS quantification in brain homogenates and MALDI-TOF mass spectrometry imaging on brain tissue sections performed in MPAQ-treated mice allowed us to confirm this prediction and to demonstrate, by MALDI-TOF mass spectrometry imaging, that MPAQ was localized in areas containing vulnerable neurons and/or their terminals. Of interest, MPAQ also rescued dopaminergic neurons, which (i) acquired dependency on the trophic peptide GDNF for their survival or (ii) underwent oxidative stress-mediated insults mediated by catalytically active iron. In summary, MPAQ possesses an interesting pharmacological profile as it penetrates the brain parenchyma and counteracts mechanisms possibly contributive to dopaminergic cell death in Parkinson disease. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Mesenchymal stem cell transplantation attenuates blood brain barrier damage and neuroinflammation and protects dopaminergic neurons against MPTP toxicity in the substantia nigra in a model of Parkinson's disease.

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Chao, Yin Xia; He, Bei Ping; Tay, Samuel Sam Wah

2009-11-30

Immunomodulatory effects of transplanted mesenchymal stem cells (MSCs) in the treatment of Parkinson's disease were studied in the MPTP-induced mouse model. MPTP treatment induced a significant loss of dopaminergic neurons, decreased expressions of claudin 1, claudin 5 and occludin in the substantia nigra compacta (SNc), and functional damage of the blood brain barrier (BBB). Our study further discovered that infiltration of MBLs into the brain to bind with microglia was detected in the SNc of MPTP-treated mice, suggesting that the BBB compromise and MBL infiltration might be involved in the pathogenesis of MPTP-induced PD. In addition, MPTP treatment also increased the expression of mannose-binding lectins (MBLs) in the liver tissue. Intravenous transplantation of MSCs into MPTP-treated mice led to recovery of BBB integrity, suppression of MBL infiltration at SNc and MBL expression in the liver, suppression of microglial activation and prevention of dopaminergic neuron death. No transplanted MSCs were observed to differentiate into dopaminergic neurons, while the MSCs migrated into the SNc and released TGF-beta1 there. Therefore, intravenous transplantation of MSCs which protect dopaminergic neurons from MPTP toxicity may be engaged in anyone or a combination of these mechanisms: repair of the BBB, reduction of MBL in the brain, inhibition of microglial cytotoxicity, and direct protection of dopaminergic neurons.

TGF-β Signaling in Dopaminergic Neurons Regulates Dendritic Growth, Excitatory-Inhibitory Synaptic Balance, and Reversal Learning

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Sarah X. Luo

2016-12-01

Full Text Available Neural circuits involving midbrain dopaminergic (DA neurons regulate reward and goal-directed behaviors. Although local GABAergic input is known to modulate DA circuits, the mechanism that controls excitatory/inhibitory synaptic balance in DA neurons remains unclear. Here, we show that DA neurons use autocrine transforming growth factor β (TGF-β signaling to promote the growth of axons and dendrites. Surprisingly, removing TGF-β type II receptor in DA neurons also disrupts the balance in TGF-β1 expression in DA neurons and neighboring GABAergic neurons, which increases inhibitory input, reduces excitatory synaptic input, and alters phasic firing patterns in DA neurons. Mice lacking TGF-β signaling in DA neurons are hyperactive and exhibit inflexibility in relinquishing learned behaviors and re-establishing new stimulus-reward associations. These results support a role for TGF-β in regulating the delicate balance of excitatory/inhibitory synaptic input in local microcircuits involving DA and GABAergic neurons and its potential contributions to neuropsychiatric disorders.

Constitutively internalized dopamine transporter is targeted to late endosomes and lysosomal degradation in heterologous cell lines and dopaminergic neurons

DEFF Research Database (Denmark)

Eriksen, Jacob; Madsen, Kenneth; Vægter, Christian Bjerggaard

and amphetamine, a substrate of the DAT. In antibody feeding experiments we observed that Tac-DAT was constitutively internalized faster than Tac alone and using an ELISA based assay we could quantify time-dependent intracellular accumulation of the transporter. Incubation with inhibitors of lysosomal degradation...... (leupeptin, chloroquine, or ammonium chloride) increased the amount of transporter accumulated intracellularly over time, suggesting that constitutively endocytosed transporter was targeted to lysosomal degradation. This was further supported by expression of Tac-DAT in the immortalized dopaminergic cell...... dopaminergic neurons and visualized the DAT directly in the neurons using the fluorescent cocaine analog JHC 1-064. These data showed pronounced colocalization upon constitutive internalization with Lysotracker, a late endosomal/lysosomal marker; however only little co-lolization was observed with Alexa488...

Endogenous Opioid-Induced Neuroplasticity of Dopaminergic Neurons in the Ventral Tegmental Area Influences Natural and Opiate Reward

NARCIS (Netherlands)

Pitchers, Kyle K.; Coppens, Caroline M.; Beloate, Lauren N.; Fuller, Jonathan; Van, Sandy; Frohmader, Karla S.; Laviolette, Steven R.; Lehman, Michael N.; Coolen, Lique M.

2014-01-01

Natural reward and drugs of abuse converge on the mesolimbic pathway and activate common mechanism of neural plasticity in the nucleus accumbens. Chronic exposure to opiates induces plasticity in dopaminergic neurons of the ventral tegmental area (VTA), which regulates morphine reward tolerance.

Investigation of the therapeutic potential of N-acetyl cysteine and the tools used to define nigrostriatal degeneration in vivo

Energy Technology Data Exchange (ETDEWEB)

Nouraei, Negin; Zarger, Lauren; Weilnau, Justin N.; Han, Jimin; Mason, Daniel M.; Leak, Rehana K., E-mail: leakr@duq.edu

2016-04-01

The glutathione precursor N-acetyl-L-cysteine (NAC) is currently being tested on Parkinson's patients for its neuroprotective properties. Our studies have shown that NAC can elicit protection in glutathione-independent manners in vitro. Thus, the goal of the present study was to establish an animal model of NAC-mediated protection in which to dissect the underlying mechanism. Mice were infused intrastriatally with the oxidative neurotoxicant 6-hydroxydopamine (6-OHDA; 4 μg) and administered NAC intraperitoneally (100 mg/kg). NAC-treated animals exhibited higher levels of the dopaminergic terminal marker tyrosine hydroxylase (TH) in the striatum 10d after 6-OHDA. As TH expression is subject to stress-induced modulation, we infused the tracer FluoroGold into the striatum to retrogradely label nigrostriatal projection neurons. As expected, nigral FluoroGold staining and cell counts of FluoroGold{sup +} profiles were both more sensitive measures of nigrostriatal degeneration than measurements relying on TH alone. However, NAC failed to protect dopaminergic neurons 3 weeks following 6-OHDA, an effect verified by four measures: striatal TH levels, nigral TH levels, nigral TH{sup +} cell counts, and nigral FluoroGold levels. Some degree of mild toxicity of FluoroGold and NAC was evident, suggesting that caution must be exercised when relying on FluoroGold as a neuron-counting tool and when designing experiments with long-term delivery of NAC—such as clinical trials on patients with chronic disorders. Finally, the strengths and limitations of the tools used to define nigrostriatal degeneration are discussed. - Highlights: • N-acetyl cysteine (NAC) was injected into animals infused with the toxicant 6-OHDA. • Retrograde tracing with FluoroGold was used to define nigrostriatal cell loss. • Infrared Odyssey imaging and cell counts were used to screen for nigral cell loss. • NAC protected transiently against 6-OHDA but this effect waned over time. • Mildly

Molecular marker differences relate to developmental position and subsets of mesodiencephalic dopaminergic neurons.

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Simone M Smits

Full Text Available The development of mesodiencephalic dopaminergic (mdDA neurons located in the substantia nigra compacta (SNc and ventral tegmental area (VTA follow a number of stages marked by distinct events. After preparation of the region by signals that provide induction and patterning, several transcription factors have been identified, which are involved in specifying the neuronal fate of these cells. The specific vulnerability of SNc neurons is thought to root in these specific developmental programs. The present study examines the positions of young postmitotic mdDA neurons to relate developmental position to mdDA subset specific markers. MdDA neurons were mapped relative to the neuromeric domains (prosomeres 1-3 (P1-3, midbrain, and hindbrain as well as the longitudinal subdivisions (floor plate, basal plate, alar plate, as proposed by the prosomeric model. We found that postmitotic mdDA neurons are located mainly in the floorplate domain and very few in slightly more lateral domains. Moreover, mdDA neurons are present along a large proportion of the anterior/posterior axis extending from the midbrain to P3 in the diencephalon. The specific positions relate to some extent to the presence of specific subset markers as Ahd2. In the adult stage more of such subsets specific expressed genes are present and may represent a molecular map defining molecularly distinct groups of mdDA neurons.

FoxO1 in dopaminergic neurons regulates energy homeostasis and targets tyrosine hydroxylase

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Doan, Khanh V.; Kinyua, Ann W.; Yang, Dong Joo; Ko, Chang Mann; Moh, Sang Hyun; Shong, Ko Eun; Kim, Hail; Park, Sang-Kyu; Kim, Dong-Hoon; Kim, Inki; Paik, Ji-Hye; DePinho, Ronald A.; Yoon, Seul Gi; Kim, Il Yong; Seong, Je Kyung; Choi, Yun-Hee; Kim, Ki Woo

2016-01-01

Dopaminergic (DA) neurons are involved in the integration of neuronal and hormonal signals to regulate food consumption and energy balance. Forkhead transcriptional factor O1 (FoxO1) in the hypothalamus plays a crucial role in mediation of leptin and insulin function. However, the homoeostatic role of FoxO1 in DA system has not been investigated. Here we report that FoxO1 is highly expressed in DA neurons and mice lacking FoxO1 specifically in the DA neurons (FoxO1 KODAT) show markedly increased energy expenditure and interscapular brown adipose tissue (iBAT) thermogenesis accompanied by reduced fat mass and improved glucose/insulin homoeostasis. Moreover, FoxO1 KODAT mice exhibit an increased sucrose preference in concomitance with higher dopamine and norepinephrine levels. Finally, we found that FoxO1 directly targets and negatively regulates tyrosine hydroxylase (TH) expression, the rate-limiting enzyme of the catecholamine synthesis, delineating a mechanism for the KO phenotypes. Collectively, these results suggest that FoxO1 in DA neurons is an important transcriptional factor that directs the coordinated control of energy balance, thermogenesis and glucose homoeostasis. PMID:27681312

IGF-1 Protects Dopamine Neurons Against Oxidative Stress: Association with Changes in Phosphokinases

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El Ayadi, Amina; Zigmond, Michael J.; Smith, Amanda D.

2016-01-01

Insulin-like growth factor-1 (IGF-1) is an endogenous peptide transported across the blood brain barrier that is protective in several brain injury models, including an acute animal model of Parkinson’s disease (PD). Motor deficits in PD are due largely to the progressive loss of nigrostriatal dopaminergic neurons. Thus, we examined the neuroprotective potential of IGF-1 in a progressive model of dopamine deficiency in which 6-hydroxydopamine (6-OHDA) is infused into the striatum. Rats received intrastriatal IGF-1 (5 or 50 μg) 6 hrs prior to infusion of 4 μg 6-OHDA into the same site and were sacrificed 1 or 4 wks later. Both concentrations of IGF-1 protected tyrosine hydroxylase (TH) immunoreactive terminals in striatum at 4 wks but not at 1 wk, indicating that IGF-induced restoration of the dopaminergic phenotype occurred over several weeks. TH-immunoreactive cell loss was only attenuated with 50 μg IGF-1. We then examined the effect of striatal IGF-1 on the Ras/ERK1/2 and PI3K/Akt pathways to ascertain if their activation correlated with IGF-1-induced protection. Striatal and nigral levels of phospho-ERK1/2 (pERK1/2) were maximal 6 hrs after IGF-1 infusion and, with the exception of an increase in nigral pERK2 at 48 hrs, returned to basal levels by 7 days. Phospho-Akt (Ser473) was elevated 6–24 hrs post-IGF-1 infusion in both striatum and substantia nigra concomitant with inhibition of pro-death GSK-3β, a downstream target of Akt. These results suggest that IGF-1 can protect the nigrostriatal pathway in a progressive PD model and that this protection is preceded by activation of key pro-survival signaling cascades PMID:26894890

Glial cell line-derived neurotrophic factor up-regulates GTP-cyclohydrolase I activity and tetrahydrobiopterin levels in primary dopaminergic neurones

DEFF Research Database (Denmark)

Bauer, M; Suppmann, S; Meyer, M

2002-01-01

in tetrahydrobiopterin levels whereas tyrosine 3-monooxygenase activity was not altered. Actinomycin D, asan inhibitor of de novo biosynthesis, abolished any GDNF-mediated up-regulation of GTPCH I activity. However, GTPCH I mRNA levels in primary dopaminergic neurones were not altered by GDNF treatment, suggesting...... by triggering activation of GTP-cyclohydrolase I (GTPCH I), a key enzyme in catecholamine biosynthesis. GDNF stimulation of primary dopaminergic neurones expressing both tyrosine 3-monooxygenase and GTPCH I resulted in a dose-dependent doubling of GTPCH I activity, and a concomitant increase...... that the mode of action for that up-regulation is not directly connected to the regulation of GTPCH I transcription. We conclude that GDNF, in addition to its action in structural differentiation, also promotes differentiation regarding expression and enzymatic activity of a crucial component...

Gastrodin Protects Apoptotic Dopaminergic Neurons in a Toxin-Induced Parkinson’s Disease Model

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Hemant Kumar

2013-01-01

Full Text Available Gastrodia elata (GE Blume is one of the most important traditional plants in Oriental countries and has been used for centuries to improve various conditions. The phenolic glucoside gastrodin is an active constituent of GE. The aim of this study was to investigate the neuroprotective role of gastrodin in 1-methyl-4-phenylpyridinium (MPP+/1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine- (MPTP induced human dopaminergic SH-SY5Y cells and mouse model of Parkinson’s disease (PD, respectively. Gastrodin significantly and dose dependently protected dopaminergic neurons against neurotoxicity through regulating free radicals, Bax/Bcl-2 mRNA, caspase-3, and cleaved poly(ADP-ribose polymerase (PARP in SH-SY5Y cells stressed with MPP+. Gastrodin also showed neuroprotective effects in the subchronic MPTP mouse PD model by ameliorating bradykinesia and motor impairment in the pole and rotarod tests, respectively. Consistent with this finding, gastrodin prevented dopamine depletion and reduced reactive astrogliosis caused by MPTP as assessed by immunohistochemistry and immunoblotting in the substantiae nigrae and striatata of mice. Moreover, gastrodin was also effective in preventing neuronal apoptosis by attenuating antioxidant and antiapoptotic activities in these brain areas. These results strongly suggest that gastrodin has protective effects in experimental PD models and that it may be developed as a clinical candidate to ameliorate PD symptoms.

Methamphetamine-induced dopaminergic toxicity prevented owing to the neuroprotective effects of salicylic acid.

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Thrash-Williams, Bessy; Karuppagounder, Senthilkumar S; Bhattacharya, Dwipayan; Ahuja, Manuj; Suppiramaniam, Vishnu; Dhanasekaran, Muralikrishnan

2016-06-01

Methamphetamine (Schedule-II drug, U.S. Drug Enforcement Administration) is one of the most abused illicit drug following cocaine, marijuana, and heroin in the USA. There are numerous health impairments and substantial economic burden caused by methamphetamine abuse. Salicylic acid, potent anti-inflammatory drug and a known neuroprotectant has shown to protect against toxicity-induced by other dopaminergic neurotoxins. Hence, in this study we investigated the neuroprotective effects of salicylic acid against methamphetamine-induced toxicity in mice. The current study investigated the effects of sodium salicylate and/or methamphetamine on oxidative stress, monoamine oxidase, mitochondrial complex I & IV activities using spectrophotometric and fluorimetric methods. Behavioral analysis evaluated the effect on movement disorders-induced by methamphetamine. Monoaminergic neurotransmitter levels were evaluated using high pressure liquid chromatography-electrochemical detection. Methamphetamine caused significant generation of reactive oxygen species and decreased complex-I activity leading to dopamine depletion. Striatal dopamine depletion led to significant behavioral changes associated with movement disorders. Sodium salicylate (50 & 100mg/kg) significantly scavenged reactive oxygen species, blocked mitochondrial dysfunction and exhibited neuroprotection against methamphetamine-induced neurotoxicity. In addition, sodium salicylate significantly blocked methamphetamine-induced behavioral changes related to movement abnormalities. One of the leading causative theories in nigral degeneration associated with movement disorders such as Parkinson's disease is exposure to stimulants, drugs of abuse, insecticide and pesticides. These neurotoxic substances can induce dopaminergic neuronal insult by oxidative stress, apoptosis, mitochondrial dysfunction and inflammation. Salicylic acid due to its antioxidant and anti-inflammatory effects could provide neuroprotection against the

Correlation of dopaminergic terminal dysfunction and microstructural abnormalities of the basal ganglia and the olfactory tract in Parkinson's disease.

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Scherfler, Christoph; Esterhammer, Regina; Nocker, Michael; Mahlknecht, Philipp; Stockner, Heike; Warwitz, Boris; Spielberger, Sabine; Pinter, Bernadette; Donnemiller, Eveline; Decristoforo, Clemens; Virgolini, Irene; Schocke, Michael; Poewe, Werner; Seppi, Klaus

2013-10-01

Signal abnormalities of the substantia nigra and the olfactory tract detected either by diffusion tensor imaging, including measurements of mean diffusivity, a parameter of brain tissue integrity, and fractional anisotropy, a parameter of neuronal fibre integrity, or transcranial sonography, were recently reported in the early stages of Parkinson's disease. In this study, changes in the nigral and olfactory diffusion tensor signal, as well as nigral echogenicity, were correlated with clinical scales of motor disability, odour function and putaminal dopamine storage capacity measured with 6-[(18)F] fluorolevodopa positron emission tomography in early and advanced stages of Parkinson's disease. Diffusion tensor imaging, transcranial sonography and positron emission tomography were performed on 16 patients with Parkinson's disease (mean disease duration 3.7 ± 3.7 years, Hoehn and Yahr stage 1 to 4) and 14 age-matched healthy control subjects. Odour function was measured by the standardized Sniffin' Sticks Test. Mean putaminal 6-[(18)F] fluorolevodopa influx constant, mean nigral echogenicity, mean diffusivity and fractional anisotropy values of the substantia nigra and the olfactory tract were identified by region of interest analysis. When compared with the healthy control group, the Parkinson's disease group showed significant signal changes in the caudate and putamen by 6-[(18)F] fluorolevodopa positron emission tomography, in the substantia nigra by transcranial sonography, mean diffusivity and fractional anisotropy (P < 0.001, P < 0.01, P < 0.05, respectively) and in the olfactory tract by mean diffusivity (P < 0.05). Regional mean diffusivity values of the substantia nigra and the olfactory tract correlated significantly with putaminal 6-[(18)F] fluorolevodopa uptake (r = -0.52, P < 0.05 and r = -0.71, P < 0.01). Significant correlations were also found between nigral mean diffusivity values and the Unified Parkinson's Disease Rating Scale motor score (r = -0

Curcumin inhibition of JNKs prevents dopaminergic neuronal loss in a mouse model of Parkinson’s disease through suppressing mitochondria dysfunction

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Pan Jing

2012-08-01

Full Text Available Abstract Curcumin,a natural polyphenol obtained from turmeric,has been implicated to be neuroprotective in a variety of neurodegenerative disorders although the mechanism remains poorly understood. The results of our recent experiments indicated that curcumin could protect dopaminergic neurons from apoptosis in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP mouse model of Parkinson’s disease (PD. The death of dopaminergic neurons and the loss of dopaminergic axon in the striatum were significantly suppressed by curcumin in MPTP mouse model. Further studies showed that curcumin inhibited JNKs hyperphosphorylation induced by MPTP treatment. JNKs phosphorylation can cause translocation of Bax to mitochondria and the release of cytochrome c which both ultimately contribute to mitochondria-mediated apoptosis. These pro-apoptosis effect can be diminished by curcumin. Our experiments demonstrated that curcumin can prevent nigrostriatal degeneration by inhibiting the dysfunction of mitochondrial through suppressing hyperphosphorylation of JNKs induced by MPTP. Our results suggested that JNKs/mitochondria pathway may be a novel target in the treatment of PD patients.

GABAB-receptor activation alters the firing pattern of dopamine neurons in the rat substantia nigra.

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Engberg, G; Kling-Petersen, T; Nissbrandt, H

1993-11-01

Previous electrophysiological experiments have emphasized the importance of the firing pattern for the functioning of midbrain dopamine (DA) neurons. In this regard, excitatory amino acid receptors appear to constitute an important modulatory control mechanism. In the present study, extracellular recording techniques were used to investigate the significance of GABAB-receptor activation for the firing properties of DA neurons in the substantia nigra (SN) in the rat. Intravenous administration of the GABAB-receptor agonist baclofen (1-16 mg/kg) was associated with a dose-dependent regularization of the firing pattern, concomitant with a reduction in burst firing. At higher doses (16-32 mg/kg), the firing rate of the DA neurons was dose-dependently decreased. Also, microiontophoretic application of baclofen regularized the firing pattern of nigral DA neurons, including a reduction of burst firing. Both the regularization of the firing pattern and inhibition of firing rate produced by systemic baclofen administration was antagonized by the GABAB-receptor antagonist CGP 35348 (200 mg/kg, i.v.). The GABAA-receptor agonist muscimol produced effects on the firing properties of DA neurons that were opposite to those observed following baclofen, i.e., an increase in firing rate accompanied by a decreased regularity. The NMDA receptor antagonist MK 801 (0.4-3.2 mg/kg, i.v.) produced a moderate, dose-dependent increase in the firing rate of the nigral DA neurons as well as a slightly regularized firing pattern. Pretreatment with MK 801 (3.2 mg/kg, i.v., 3-10 min) did neither promote nor prevent the regularization of the firing pattern or inhibition of firing rate on the nigral DA neurons produced by baclofen. The present results clearly show that GABAB-receptors can alter the firing pattern of nigral DA neurons, hereby counterbalancing the previously described ability of glutamate to induce burst firing activity on these neurons.

Managing Parkinson's disease with continuous dopaminergic stimulation

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Wolters, Erik; Lees, Andrew J.; Volkmann, Jens; van Laar, Teus; Hovestadt, Ad

The pathophysiology of Parkinson's disease is marked by the loss of dopaminergic neurons, which leads to striatal dopaminergic deficiency. This causes resting tremor, hypokinesia, rigidity, bradykinesia, and loss of postural reflexes. Most current treatments for Parkinson's disease aim to restore

A novel dopamine transporter transgenic mouse line for identification and purification of midbrain dopaminergic neurons reveals midbrain heterogeneity

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Christiansen, Mia Apuschkin; Stilling, Sara; Rahbek-Clemmensen, Troels

2015-01-01

Midbrain dopaminergic (DAergic) neurons are a heterogeneous cell group, composed of functionally distinct cell populations projecting to the basal ganglia, prefrontal cortex and limbic system. Despite their functional significance, the midbrain population of DAergic neurons is sparse, constituting...... of the dopamine transporter (DAT) promoter was characterized. Confocal microscopy analysis of brain sections showed strong eGFP signal reporter in midbrain regions and striatal terminals that co-localized with the DAergic markers DAT and tyrosine hydroxylase (TH). Thorough quantification of co...

Topography and collateralization of dopaminergic projections to primary motor cortex in rats.

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Hosp, Jonas A; Nolan, Helen E; Luft, Andreas R

2015-05-01

Dopaminergic signaling within the primary motor cortex (M1) is necessary for successful motor skill learning. Dopaminergic neurons projecting to M1 are located in the ventral tegmental area (VTA, nucleus A10) of the midbrain. It is unknown which behavioral correlates are encoded by these neurons. The objective here is to investigate whether VTA-M1 fibers are collaterals of projections to prefrontal cortex (PFC) or nucleus accumbens (NAc) or if they form a distinct pathway. In rats, multiple-site retrograde fluorescent tracers were injected into M1, PFC and the core region of the NAc and VTA sections investigated for concomitant labeling of different tracers. Dopaminergic neurons projecting to M1, PFC and NAc were found in nucleus A10 and to a lesser degree in the medial nucleus A9. Neurons show high target specificity, minimal collateral branching to other than their target area and hardly cross the midline. Whereas PFC- and NAc-projecting neurons are indistinguishably intermingled within the ventral portion of dopaminergic nuclei in middle and caudal midbrain, M1-projecting neurons are only located within the dorsal part of the rostral midbrain. Within M1, the forelimb representation receives sevenfold more dopaminergic projections than the hindlimb representation. This strong rostro-caudal gradient as well as the topographical preference to dorsal structures suggest that projections to M1 emerged late in the development of the dopaminergic systems in and form a functionally distinct system.

Dopamine induces soluble α-synuclein oligomers and nigrostriatal degeneration.

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Mor, Danielle E; Tsika, Elpida; Mazzulli, Joseph R; Gould, Neal S; Kim, Hanna; Daniels, Malcolm J; Doshi, Shachee; Gupta, Preetika; Grossman, Jennifer L; Tan, Victor X; Kalb, Robert G; Caldwell, Kim A; Caldwell, Guy A; Wolfe, John H; Ischiropoulos, Harry

2017-11-01

Parkinson's disease (PD) is defined by the loss of dopaminergic neurons in the substantia nigra and the formation of Lewy body inclusions containing aggregated α-synuclein. Efforts to explain dopamine neuron vulnerability are hindered by the lack of dopaminergic cell death in α-synuclein transgenic mice. To address this, we manipulated both dopamine levels and α-synuclein expression. Nigrally targeted expression of mutant tyrosine hydroxylase with enhanced catalytic activity increased dopamine levels without damaging neurons in non-transgenic mice. In contrast, raising dopamine levels in mice expressing human A53T mutant α-synuclein induced progressive nigrostriatal degeneration and reduced locomotion. Dopamine elevation in A53T mice increased levels of potentially toxic α-synuclein oligomers, resulting in conformationally and functionally modified species. Moreover, in genetically tractable Caenorhabditis elegans models, expression of α-synuclein mutated at the site of interaction with dopamine prevented dopamine-induced toxicity. These data suggest that a unique mechanism links two cardinal features of PD: dopaminergic cell death and α-synuclein aggregation.

Transient activation of dopaminergic neurons during development modulates visual responsiveness, locomotion and brain activity in a dopamine ontogeny model of schizophrenia.

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Calcagno, B; Eyles, D; van Alphen, B; van Swinderen, B

2013-01-08

It has been observed that certain developmental environmental risk factors for schizophrenia when modeled in rodents alter the trajectory of dopaminergic development, leading to persistent behavioural changes in adults. This has recently been articulated as the "dopamine ontogeny hypothesis of schizophrenia". To test one aspect of this hypothesis, namely that transient dopaminergic effects during development modulate attention-like behavior and arousal in adults, we turned to a small-brain model, Drosophila melanogaster. By applying genetic tools allowing transient activation or silencing of dopaminergic neurons in the fly brain, we investigated whether a critical window exists during development when altered dopamine (DA) activity levels could lead to impairments in arousal states in adult animals. We found that increased activity in dopaminergic neurons in later stages of development significantly increased visual responsiveness and locomotion, especially in adult males. This misallocation of visual salience and hyperactivity mimicked the effect of acute methamphetamine feeding to adult flies, suggesting up-regulated DA signaling could result from developmental manipulations. Finally, brain recordings revealed significantly reduced gamma-band activity in adult animals exposed to the transient developmental insult. Together, these data support the idea that transient alterations in DA signaling during development can permanently alter behavior in adults, and that a reductionist model such as Drosophila can be used to investigate potential mechanisms underlying complex cognitive disorders such as schizophrenia.

A subpopulation of dopaminergic neurons co-expresses serotonin in ventral mesencephalic cultures but not after intrastriatal transplantation in a rat model of Parkinsons disease

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Di Santo, Stefano; Seiler, Stefanie; Ducray, Angélique

2017-01-01

Cell replacement therapy is a promising avenue into the investigation and treatment of Parkinson’s disease (PD) and in some cases significant long-term motor improvements have been demonstrated. The main source of donor tissue is the human fetal ventral mesencephalon (VM), which consists...... 30% of the dopaminergic neurons in the donor tissue co-expressed serotonin, no co-localization could be detected in grafts one month after intrastriatal transplantation into hemi-parkinsonian rats. In conclusion, a significant and susceptible sub-population of dopaminergic neurons in fetal VM tissues...... both fetal rat and human dissociated, organotypic and neurosphere VM cultures as well as an animal model of PD were investigated. In dissociated rat VM cultures approximately 30% of the TH positive neurons co-expressed serotonin, while no co-localization with GABA was observed. Interestingly, co...

The I2020T Leucine-rich repeat kinase 2 transgenic mouse exhibits impaired locomotive ability accompanied by dopaminergic neuron abnormalities

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Maekawa Tatsunori

2012-04-01

Full Text Available Abstract Background Leucine-rich repeat kinase 2 (LRRK2 is the gene responsible for autosomal-dominant Parkinson’s disease (PD, PARK8, but the mechanism by which LRRK2 mutations cause neuronal dysfunction remains unknown. In the present study, we investigated for the first time a transgenic (TG mouse strain expressing human LRRK2 with an I2020T mutation in the kinase domain, which had been detected in the patients of the original PARK8 family. Results The TG mouse expressed I2020T LRRK2 in dopaminergic (DA neurons of the substantia nigra, ventral tegmental area, and olfactory bulb. In both the beam test and rotarod test, the TG mice exhibited impaired locomotive ability in comparison with their non-transgenic (NTG littermates. Although there was no obvious loss of DA neurons in either the substantia nigra or striatum, the TG brain showed several neurological abnormalities such as a reduced striatal dopamine content, fragmentation of the Golgi apparatus in DA neurons, and an increased degree of microtubule polymerization. Furthermore, the tyrosine hydroxylase-positive primary neurons derived from the TG mouse showed an increased frequency of apoptosis and had neurites with fewer branches and decreased outgrowth in comparison with those derived from the NTG controls. Conclusions The I2020T LRRK2 TG mouse exhibited impaired locomotive ability accompanied by several dopaminergic neuron abnormalities. The TG mouse should provide valuable clues to the etiology of PD caused by the LRRK2 mutation.

Application of the Physical Disector Principle for Quantification of Dopaminergic Neuronal Loss in a Rat 6-Hydroxydopamine Nigral Lesion Model of Parkinson's Disease

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Katrine Fabricius

2017-12-01

Full Text Available Stereological analysis is the optimal tool for quantitative assessment of brain morphological and cellular changes induced by neurotoxic lesions or treatment interventions. Stereological methods based on random sampling techniques yield unbiased estimates of particle counts within a defined volume, thereby providing a true quantitative estimate of the target cell population. Neurodegenerative diseases involve loss of specific neuron types, such as the midbrain tyrosine hydroxylase-positive dopamine neurons in Parkinson's disease and in animal models of nigrostriatal degeneration. Therefore, we applied an established automated physical disector principle in a fractionator design for efficient stereological quantitative analysis of tyrosine hydroxylase (TH-positive dopamine neurons in the substantia nigra pars compacta of hemiparkinsonian rats with unilateral 6-hydroxydopamine (6-OHDA lesions. We obtained reliable estimates of dopamine neuron numbers, and established the relationship between behavioral asymmetry and dopamine neuron loss on the lesioned side. In conclusion, the automated physical disector principle provided a useful and efficient tool for unbiased estimation of TH-positive neurons in rat midbrain, and should prove valuable for investigating neuroprotective strategies in 6-OHDA model of parkinsonism, while generalizing to other immunohistochemically-defined cell populations.

Progranulin gene delivery protects dopaminergic neurons in a mouse model of Parkinson's disease.

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Jackalina M Van Kampen

Full Text Available Parkinson's disease (PD is a progressive neurodegenerative disorder characterized by tremor, rigidity and akinesia/bradykinesia resulting from the progressive loss of nigrostriatal dopaminergic neurons. To date, only symptomatic treatment is available for PD patients, with no effective means of slowing or stopping the progression of the disease. Progranulin (PGRN is a 593 amino acid multifunction protein that is widely distributed throughout the CNS, localized primarily in neurons and microglia. PGRN has been demonstrated to be a potent regulator of neuroinflammation and also acts as an autocrine neurotrophic factor, important for long-term neuronal survival. Thus, enhancing PGRN expression may strengthen the cells resistance to disease. In the present study, we have used the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP model of PD to investigate the possible use of PGRN gene delivery as a therapy for the prevention or treatment of PD. Viral vector delivery of the PGRN gene was an effective means of elevating PGRN expression in nigrostriatal neurons. When PGRN expression was elevated in the SNC, nigrostriatal neurons were protected from MPTP toxicity in mice, along with a preservation of striatal dopamine content and turnover. Further, protection of nigrostriatal neurons by PGRN gene therapy was accompanied by reductions in markers of MPTP-induced inflammation and apoptosis as well as a complete preservation of locomotor function. We conclude that PGRN gene therapy may have beneficial effects in the treatment of PD.

TFEB-mediated autophagy rescues midbrain dopamine neurons from α-synuclein toxicity

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Decressac, Mickael; Mattsson, Bengt; Weikop, Pia

2013-01-01

that the PD-like neurodegenerative changes induced by excess cellular levels of α-synuclein in nigral dopamine neurons are closely linked to a progressive decline in markers of lysosome function, accompanied by cytoplasmic retention of transcription factor EB (TFEB), a major transcriptional regulator...... in both A9 and A10 dopamine neurons. Delayed activation of TFEB function through inhibition of mammalian target of rapamycin blocked α-synuclein induced neurodegeneration and further disease progression. The results provide a mechanistic link between α-synuclein toxicity and impaired TFEB function......The aggregation of α-synuclein plays a major role in Parkinson disease (PD) pathogenesis. Recent evidence suggests that defects in the autophagy-mediated clearance of α-synuclein contribute to the progressive loss of nigral dopamine neurons. Using an in vivo model of α-synuclein toxicity, we show...

Redundant dopaminergic activity may enable compensatory axonal sprouting in Parkinson disease.

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Arkadir, David; Bergman, Hagai; Fahn, Stanley

2014-03-25

Neurodegenerative diseases become clinically apparent only after a substantial population of neurons is lost. This raises the possibility of compensatory mechanisms in the early phase of these diseases. The importance of understanding these mechanisms cannot be underestimated because it may guide future disease-modifying strategies. Because the anatomy and physiology of the nigrostriatal dopaminergic pathways have been well described, the study of Parkinson disease can offer insight into these early compensatory mechanisms. Collateral axonal sprouting of dopaminergic terminals into the denervated striatum is the most studied compensatory mechanism in animal (almost exclusively rodent) models of Parkinson disease and is correlated with behavioral recovery after partial lesions. This sprouting, however, does not respect the normal anatomy of the original nigrostriatal pathways and leads to aberrant neuronal networks. We suggest here that the unique physiologic property of the dopaminergic innervation of the striatum, namely redundancy of information encoding, is crucial to the efficacy of compensatory axonal sprouting in the presence of aberrant anatomical connections. Redundant information encoding results from the similarity of representation of salient and rewarding events by many dopaminergic neurons, from the wide axonal field of a single dopaminergic neuron in the striatum, and from the nonspecific spatial effect of dopamine on striatal neurons (volume conductance). Finally, we discuss the relevance of these findings in animal models to human patients with Parkinson disease.

Anti-Inflammatory Modulation of Microglia via CD163-Targeted Glucocorticoids Protects Dopaminergic Neurons in the 6-OHDA Parkinson's Disease Model

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Tentillier, Noemie; Etzerodt, Anders; Olesen, Mads N

2016-01-01

intravenous CD163-targeted liposomes with Dexa for 3 weeks exhibited better motor performance than the control groups and had minimal glucocorticoid-driven side effects. Furthermore, these animals showed better survival of dopaminergic neurons in substantia nigra and an increased number of microglia...

Electrophysiological effects of trace amines on mesencephalic dopaminergic neurons

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Ada eLedonne

2011-07-01

Full Text Available Trace amines (TAs are a class of endogenous compounds strictly related to classic monoamine neurotransmitters with regard to their structure, metabolism and tissue distribution. Although the presence of TAs in mammalian brain has been recognized for decades, until recently they were considered to be by-products of amino acid metabolism or as ‘false’ neurotransmitters. The discovery in 2001 of a new family of G protein-coupled receptors (GPCRs, namely trace amines receptors, has re-ignited interest in TAs. In particular, two members of the family, trace amine receptor 1 (TA1 and trace amine receptor 2 (TA2, were shown to be highly sensitive to these endogenous compounds. Experimental evidence suggests that TAs modulate the activity of catecholaminergic neurons and that TA dysregulation may contribute to neuropsychiatric disorders, including schizophrenia, attention deficit hyperactivity disorder, depression and Parkinson’s disease, all of which are characterised by altered monoaminergic networks. Here we review recent data concerning the electrophysiological effects of TAs on the activity of mesencephalic dopaminergic neurons. In the context of recent data obtained with TA1 receptor knockout mice, we also discuss the mechanisms by which the activation of these receptors modulates the activity of these neurons. Three important new aspects of TAs action have recently emerged: (a inhibition of firing due to increased release of dopamine; (b reduction of D2 and GABAB receptor-mediated inhibitory responses (excitatory effects due to dysinhibition; and (c a direct TA1 receptor-mediated activation of GIRK channels which produce cell membrane hyperpolarization. While the first two effects have been well documented in our laboratory, the direct activation of GIRK channels by TA1 receptors has been reported by others, but has not been seen in our laboratory (Geracitano et al., 2004. Further research is needed to address this point, and to further

INCREASE IN DOPAMINE RELEASE FROM THE NUCLEUS-ACCUMBENS IN RESPONSE TO FEEDING - A MODEL TO STUDY INTERACTIONS BETWEEN DRUGS AND NATURALLY ACTIVATED DOPAMINERGIC-NEURONS IN THE RAT-BRAIN

NARCIS (Netherlands)

WESTERINK, BHC; TEISMAN, A; DEVRIES, JB

The aim of the present study was to investigate the interactions between the in vivo release of dopamine and certain drugs, during conditions of increased dopaminergic activity. Dopaminergic neurons in the nucleus accumbens were activated by feeding hungry rats. 48-96 h after implantation of a

Transduced PEP-1-PON1 proteins regulate microglial activation and dopaminergic neuronal death in a Parkinson's disease model.

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Kim, Mi Jin; Park, Meeyoung; Kim, Dae Won; Shin, Min Jea; Son, Ora; Jo, Hyo Sang; Yeo, Hyeon Ji; Cho, Su Bin; Park, Jung Hwan; Lee, Chi Hern; Kim, Duk-Soo; Kwon, Oh-Shin; Kim, Joon; Han, Kyu Hyung; Park, Jinseu; Eum, Won Sik; Choi, Soo Young

2015-09-01

Parkinson's disease (PD) is an oxidative stress-mediated neurodegenerative disorder caused by selective dopaminergic neuronal death in the midbrain substantia nigra. Paraoxonase 1 (PON1) is a potent inhibitor of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) against oxidation by destroying biologically active phospholipids with potential protective effects against oxidative stress-induced inflammatory disorders. In a previous study, we constructed protein transduction domain (PTD) fusion PEP-1-PON1 protein to transduce PON1 into cells and tissue. In this study, we examined the role of transduced PEP-1-PON1 protein in repressing oxidative stress-mediated inflammatory response in microglial BV2 cells after exposure to lipopolysaccharide (LPS). Moreover, we identified the functions of transduced PEP-1-PON1 proteins which include, mitigating mitochondrial damage, decreasing reactive oxidative species (ROS) production, matrix metalloproteinase-9 (MMP-9) expression and protecting against 1-methyl-4-phenylpyridinium (MPP(+))-induced neurotoxicity in SH-SY5Y cells. Furthermore, transduced PEP-1-PON1 protein reduced MMP-9 expression and protected against dopaminergic neuronal cell death in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice model. Taken together, these results suggest a promising therapeutic application of PEP-1-PON1 proteins against PD and other inflammation and oxidative stress-related neuronal diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Proneural transcription factor Atoh1 drives highly efficient differentiation of human pluripotent stem cells into dopaminergic neurons.

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Sagal, Jonathan; Zhan, Xiping; Xu, Jinchong; Tilghman, Jessica; Karuppagounder, Senthilkumar S; Chen, Li; Dawson, Valina L; Dawson, Ted M; Laterra, John; Ying, Mingyao

2014-08-01

Human pluripotent stem cells (PSCs) are a promising cell resource for various applications in regenerative medicine. Highly efficient approaches that differentiate human PSCs into functional lineage-specific neurons are critical for modeling neurological disorders and testing potential therapies. Proneural transcription factors are crucial drivers of neuron development and hold promise for driving highly efficient neuronal conversion in PSCs. Here, we study the functions of proneural transcription factor Atoh1 in the neuronal differentiation of PSCs. We show that Atoh1 is induced during the neuronal conversion of PSCs and that ectopic Atoh1 expression is sufficient to drive PSCs into neurons with high efficiency. Atoh1 induction, in combination with cell extrinsic factors, differentiates PSCs into functional dopaminergic (DA) neurons with >80% purity. Atoh1-induced DA neurons recapitulate key biochemical and electrophysiological features of midbrain DA neurons, the degeneration of which is responsible for clinical symptoms in Parkinson's disease (PD). Atoh1-induced DA neurons provide a reliable disease model for studying PD pathogenesis, such as neurotoxin-induced neurodegeneration in PD. Overall, our results determine the role of Atoh1 in regulating neuronal differentiation and neuron subtype specification of human PSCs. Our Atoh1-mediated differentiation approach will enable large-scale applications of PD patient-derived midbrain DA neurons in mechanistic studies and drug screening for both familial and sporadic PD. ©AlphaMed Press.

Olfactory impairment in the rotenone model of Parkinson's disease is associated with bulbar dopaminergic D2 activity after REM sleep deprivation

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Laís Soares Rodrigues

2014-12-01

Full Text Available Olfactory and rapid eye movement (REM sleep deficits are commonly found in untreated subjects with a recent diagnosis of Parkinson's disease (PD. Besides different studies reported declines in olfactory performances during a short period of sleep deprivation. Mechanisms underlying these clinical manifestations are poorly understood although the impairment in the dopamine (DA neurotransmission in the olfactory bulb and in the nigrostriatal pathway may have important roles in olfactory as well as in REM sleep disturbances. Therefore, we have led to the hypothesis that a modulation of the dopaminergic D2 receptors in the olfactory bulb could provide a more comprehensive understanding of the olfactory deficits in PD and after a short period of REM sleep deprivation (REMSD. We decided to investigate the olfactory, neurochemical and histological alterations generated by the administration of piribedil (a selective D2 agonist or raclopride (a selective D2 antagonist, within the glomerular layer of the olfactory bulb, in rats submitted to intranigral rotenone and REMSD. Our findings provided a remarkable evidence of the occurrence of a negative correlation (r = - 0.52, P = 0.04 between the number of periglomerular TH-ir neurons and the bulbar levels of DA in the rotenone, but not sham groups. A significant positive correlation (r = 0.34, P = 0.03 was observed between nigral DA and olfactory discrimination index (DI, for the sham groups, indicating that increased DA levels in the substantia nigra pars compacta (SNpc are associated to enhanced olfactory discrimination performance. Also, increased levels in bulbar and striatal DA induced by piribedil in the rotenone control and rotenone REMSD groups were consistent with reduced amounts of DI. The present evidence reinforce that DA produced by periglomerular neurons, and particularly the bulbar dopaminergic D2 receptors, are essential participants in the olfactory discrimination processes, as well as SNpc

Ropinirole and Pramipexole Promote Structural Plasticity in Human iPSC-Derived Dopaminergic Neurons via BDNF and mTOR Signaling

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Ginetta Collo

2018-01-01

Full Text Available The antiparkinsonian ropinirole and pramipexole are D3 receptor- (D3R- preferring dopaminergic (DA agonists used as adjunctive therapeutics for the treatment resistant depression (TRD. While the exact antidepressant mechanism of action remains uncertain, a role for D3R in the restoration of impaired neuroplasticity occurring in TRD has been proposed. Since D3R agonists are highly expressed on DA neurons in humans, we studied the effect of ropinirole and pramipexole on structural plasticity using a translational model of human-inducible pluripotent stem cells (hiPSCs. Two hiPSC clones from healthy donors were differentiated into midbrain DA neurons. Ropinirole and pramipexole produced dose-dependent increases of dendritic arborization and soma size after 3 days of culture, effects antagonized by the selective D3R antagonists SB277011-A and S33084 and by the mTOR pathway kinase inhibitors LY294002 and rapamycin. All treatments were also effective in attenuating the D3R-dependent increase of p70S6-kinase phosphorylation. Immunoneutralisation of BDNF, inhibition of TrkB receptors, and blockade of MEK-ERK signaling likewise prevented ropinirole-induced structural plasticity, suggesting a critical interaction between BDNF and D3R signaling pathways. The highly similar profiles of data acquired with DA neurons derived from two hiPSC clones underpin their reliability for characterization of pharmacological agents acting via dopaminergic mechanisms.

Interaction of NMDA receptor and pacemaking mechanisms in the midbrain dopaminergic neuron.

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Joon Ha

Full Text Available Dopamine neurotransmission has been found to play a role in addictive behavior and is altered in psychiatric disorders. Dopaminergic (DA neurons display two functionally distinct modes of electrophysiological activity: low- and high-frequency firing. A puzzling feature of the DA neuron is the following combination of its responses: N-methyl-D-aspartate receptor (NMDAR activation evokes high-frequency firing, whereas other tonic excitatory stimuli (α-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate receptor (AMPAR activation or applied depolarization block firing instead. We suggest a new computational model that reproduces this combination of responses and explains recent experimental data. Namely, somatic NMDAR stimulation evokes high-frequency firing and is more effective than distal dendritic stimulation. We further reduce the model to a single compartment and analyze the mechanism of the distinct high-frequency response to NMDAR activation vs. other stimuli. Standard nullcline analysis shows that the mechanism is based on a decrease in the amplitude of calcium oscillations. The analysis confirms that the nonlinear voltage dependence provided by the magnesium block of the NMDAR determine its capacity to elevate the firing frequency. We further predict that the moderate slope of the voltage dependence plays the central role in the frequency elevation. Additionally, we suggest a repolarizing current that sustains calcium-independent firing or firing in the absence of calcium-dependent repolarizing currents. We predict that the ether-a-go-go current (ERG, which has been observed in the DA neuron, is the best fit for this critical role. We show that a calcium-dependent and a calcium-independent oscillatory mechanisms form a structure of interlocked negative feedback loops in the DA neuron. The structure connects research of DA neuron firing with circadian biology and determines common minimal models for investigation of robustness of oscillations

Single-Cell RNA-Seq of Mouse Dopaminergic Neurons Informs Candidate Gene Selection for Sporadic Parkinson Disease.

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Hook, Paul W; McClymont, Sarah A; Cannon, Gabrielle H; Law, William D; Morton, A Jennifer; Goff, Loyal A; McCallion, Andrew S

2018-03-01

Genetic variation modulating risk of sporadic Parkinson disease (PD) has been primarily explored through genome-wide association studies (GWASs). However, like many other common genetic diseases, the impacted genes remain largely unknown. Here, we used single-cell RNA-seq to characterize dopaminergic (DA) neuron populations in the mouse brain at embryonic and early postnatal time points. These data facilitated unbiased identification of DA neuron subpopulations through their unique transcriptional profiles, including a postnatal neuroblast population and substantia nigra (SN) DA neurons. We use these population-specific data to develop a scoring system to prioritize candidate genes in all 49 GWAS intervals implicated in PD risk, including genes with known PD associations and many with extensive supporting literature. As proof of principle, we confirm that the nigrostriatal pathway is compromised in Cplx1-null mice. Ultimately, this systematic approach establishes biologically pertinent candidates and testable hypotheses for sporadic PD, informing a new era of PD genetic research. Copyright © 2018 American Society of Human Genetics. All rights reserved.

Dopaminergic Neuron-Specific Deletion of p53 Gene Attenuates Methamphetamine Neurotoxicity.

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Lu, Tao; Kim, Paul P; Greig, Nigel H; Luo, Yu

2017-08-01

p53 plays an essential role in the regulation of cell death in dopaminergic (DA) neurons and its activation has been implicated in the neurotoxic effects of methamphetamine (MA). However, how p53 mediates MA neurotoxicity remains largely unknown. In this study, we examined the effect of DA-specific p53 gene deletion in DAT-p53KO mice. Whereas in vivo MA binge exposure reduced locomotor activity in wild-type (WT) mice, this was significantly attenuated in DAT-p53KO mice and associated with significant differences in the levels of the p53 target genes BAX and p21 between WT and DAT-p53KO. Notably, DA-specific deletion of p53 provided protection of substantia nigra pars reticulata (SNpr) tyrosine hydroxylase (TH) positive fibers following binge MA, with DAT-p53KO mice having less decline of TH protein levels in striatum versus WT mice. Whereas DAT-p53KO mice demonstrated a consistently higher density of TH fibers in striatum compared to WT mice at 10 days after MA exposure, DA neuron counts within the substantia nigra pars compacta (SNpc) were similar. Finally, supportive of these results, administration of a p53-specific inhibitor (PFT-α) provided a similarly protective effect on MA binge-induced behavioral deficits. Neither DA specific p53 deletion nor p53 pharmacological inhibition affected hyperthermia induced by MA binge. These findings demonstrate a specific contribution of p53 activation in behavioral deficits and DA neuronal terminal loss by MA binge exposure.

Glia Maturation Factor Dependent Inhibition of Mitochondrial PGC-1α Triggers Oxidative Stress-Mediated Apoptosis in N27 Rat Dopaminergic Neuronal Cells.

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Selvakumar, Govindhasamy Pushpavathi; Iyer, Shankar S; Kempuraj, Duraisamy; Raju, Murugesan; Thangavel, Ramasamy; Saeed, Daniyal; Ahmed, Mohammad Ejaz; Zahoor, Harris; Raikwar, Sudhanshu P; Zaheer, Smita; Zaheer, Asgar

2018-01-30

Parkinson's disease (PD) is a progressive neurodegenerative disease affecting over five million individuals worldwide. The exact molecular events underlying PD pathogenesis are still not clearly known. Glia maturation factor (GMF), a neuroinflammatory protein in the brain plays an important role in the pathogenesis of PD. Mitochondrial dysfunctions and oxidative stress trigger apoptosis leading to dopaminergic neuronal degeneration in PD. Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α or PPARGC-α) acts as a transcriptional co-regulator of mitochondrial biogenesis and energy metabolism by controlling oxidative phosphorylation, antioxidant activity, and autophagy. In this study, we found that incubation of immortalized rat dopaminergic (N27) neurons with GMF influences the expression of peroxisome PGC-1α and increases oxidative stress, mitochondrial dysfunction, and apoptotic cell death. We show that incubation with GMF reduces the expression of PGC-1α with concomitant decreases in the mitochondrial complexes. Besides, there is increased oxidative stress and depolarization of mitochondrial membrane potential (MMP) in these cells. Further, GMF reduces tyrosine hydroxylase (TH) expression and shifts Bax/Bcl-2 expression resulting in release of cytochrome-c and increased activations of effector caspase expressions. Transmission electron microscopy analyses revealed alteration in the mitochondrial architecture. Our results show that GMF acts as an important upstream regulator of PGC-1α in promoting dopaminergic neuronal death through its effect on oxidative stress-mediated apoptosis. Our current data suggest that GMF is a critical risk factor for PD and suggest that it could be explored as a potential therapeutic target to inhibit PD progression.

Mesencephalic dopaminergic neurons express a repertoire of olfactory receptors and respond to odorant-like molecules.

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Grison, Alice; Zucchelli, Silvia; Urzì, Alice; Zamparo, Ilaria; Lazarevic, Dejan; Pascarella, Giovanni; Roncaglia, Paola; Giorgetti, Alejandro; Garcia-Esparcia, Paula; Vlachouli, Christina; Simone, Roberto; Persichetti, Francesca; Forrest, Alistair R R; Hayashizaki, Yoshihide; Carloni, Paolo; Ferrer, Isidro; Lodovichi, Claudia; Plessy, Charles; Carninci, Piero; Gustincich, Stefano

2014-08-27

The mesencephalic dopaminergic (mDA) cell system is composed of two major groups of projecting cells in the Substantia Nigra (SN) (A9 neurons) and the Ventral Tegmental Area (VTA) (A10 cells). Selective degeneration of A9 neurons occurs in Parkinson's disease (PD) while abnormal function of A10 cells has been linked to schizophrenia, attention deficit and addiction. The molecular basis that underlies selective vulnerability of A9 and A10 neurons is presently unknown. By taking advantage of transgenic labeling, laser capture microdissection coupled to nano Cap-Analysis of Gene Expression (nanoCAGE) technology on isolated A9 and A10 cells, we found that a subset of Olfactory Receptors (OR)s is expressed in mDA neurons. Gene expression analysis was integrated with the FANTOM5 Helicos CAGE sequencing datasets, showing the presence of these ORs in selected tissues and brain areas outside of the olfactory epithelium. OR expression in the mesencephalon was validated by RT-PCR and in situ hybridization. By screening 16 potential ligands on 5 mDA ORs recombinantly expressed in an heterologous in vitro system, we identified carvone enantiomers as agonists at Olfr287 and able to evoke an intracellular Ca2+ increase in solitary mDA neurons. ORs were found expressed in human SN and down-regulated in PD post mortem brains. Our study indicates that mDA neurons express ORs and respond to odor-like molecules providing new opportunities for pharmacological intervention in disease.

Resistance of neuronal nitric oxide synthase-deficient mice to methamphetamine-induced dopaminergic neurotoxicity.

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Itzhak, Y; Gandia, C; Huang, P L; Ali, S F

1998-03-01

Methamphetamine (METH) is a powerful psychostimulant that produces dopaminergic neurotoxicity manifested by a decrease in the levels of dopamine, tyrosine hydroxylase activity and dopamine transporter (DAT) binding sites in the nigrostriatal system. We have recently reported that blockade of the neuronal nitric oxide synthase (nNOS) isoform by 7-nitroindazole provides protection against METH-induced neurotoxicity in Swiss Webster mice. The present study was undertaken to investigate the effect of a neurotoxic dose of METH on mutant mice lacking the nNOS gene [nNOS(-/-)] and wild-type controls. In addition, we sought to investigate the behavioral outcome of exposure to a neurotoxic dose of METH. Homozygote nNOS(-/-), heterozygote nNOS(+/-) and wild-type animals were administered either saline or METH (5 mg/kg x 3). Dopamine, DOPAC and HVA levels, as well as DAT binding site levels, were determined in striatal tissue derived 72 h after the last METH injection. This regimen of METH given to nNOS(-/-) mice affected neither the tissue content of dopamine and its metabolites nor the number of DAT binding sites. Although a moderate reduction in the levels of dopamine (35%) and DAT binding sites (32%) occurred in striatum of heterozygote nNOS(+/-) mice, a more profound depletion of the dopaminergic markers (up to 68%) was observed in the wild-type animals. METH-induced hyperthermia was observed in all animal strains examined except the nNOS(-/-) mice. Investigation of the animals' spontaneous locomotor activity before and after administration of the neurotoxic dose of METH (5 mg/kg x 3) revealed no differences. A low dose of METH (1.0 mg/kg) administered to naive animals (nNOS(-/-) and wild-type) resulted in a similar intensity of locomotor stimulation. However, 68 to 72 h after exposure to the high-dose METH regimen, a marked sensitized responses to a challenge METH injection was observed in the wild-type mice but not in the nNOS(-/-) mice. Taken together, these results

sigma receptor ligands attenuate N-methyl-D-aspartate cytotoxicity in dopaminergic neurons of mesencephalic slice cultures.

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Shimazu, S; Katsuki, H; Takenaka, C; Tomita, M; Kume, T; Kaneko, S; Akaike, A

2000-01-28

We investigated the potential neuroprotective effects of several sigma receptor ligands in organotypic midbrain slice cultures as an excitotoxicity model system. When challenged with 100-microM N-methyl-D-aspartate (NMDA) for 24 h, dopaminergic neurons in midbrain slice cultures degenerated, and this was prevented by (5R, 10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,b]-cyclohepten-5, 10-imine (MK-801; 1-10 microM). Concomitant application of ifenprodil (1-10 microM) or haloperidol (1-10 microM), both of which are high-affinity sigma receptor ligands, significantly attenuated the neurotoxicity of 100 microM NMDA. The sigma(1) receptor-selective ligand (+)-N-allylnormetazocine ((+)-SKF 10047; 1-10 microM) was also effective in attenuating the toxicity of NMDA. The effect of R(-)-N-(3-phenyl-1-propyl)-1-phenyl-2-aminopropane hydrochloride ((-)-PPAP), a sigma receptor ligand with negligible affinity for the phencyclidine site of NMDA receptors, was also examined. (-)-PPAP (3-100 microM) caused a concentration-dependent reduction of NMDA cytotoxicity, with significant protection at concentrations of 30 and 100 microM. In contrast, (+)-SKF 10047 (10 microM) and (-)-PPAP (100 microM) showed no protective effects against cell death induced by the Ca(2+) ionophore ionomycin (1-3 microM). These results indicate that sigma receptor ligands attenuate the cytotoxic effects of NMDA on midbrain dopaminergic neurons, possibly via inhibition of NMDA receptor functions.

Effects of Feeder Cells on Dopaminergic Differentiation of Human Embryonic Stem Cells

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Zhenqiang Zhao

2016-12-01

Full Text Available Mouse embryonic fibroblasts (MEFs and human foreskin fibroblasts (HFFs are used for the culture of human embryonic stem cells (hESCs. MEFs and HFFs differed in their capacity to support the proliferation and pluripotency of hESCs and could affect cardiac differentiation potential of hESCs. The aim of this study was to evaluate the effect of MEFs and HFFs feeders on dopaminergic differentiation of hESCs lines. To minimize the impact of culture condition variation, two hESCs lines were cultured on mixed feeder cells (MFCs, MEFs: HFFs =1:1 and HFFs feeder respectively, and then were differentiated into DA neurons under the identical protocol. Dopaminergic differentiation was evaluated by immunocytochemistry, quantitative fluorescent real-time PCR (qRT-PCR, transmission and scanning electron microscopy, and patch clamp. Our results demonstrated that these hESCs-derived neurons were genuine and functional DA neurons. However, compared to hESCs line on MFCs feeder, hESCs line on HFFs feeder had a higher proportion of TH positive cells and expressed higher levels of FOXA2, PITX3, NURR1 and TH genes. In addition, the values of threshold intensity and threshold membrane potential of DA neurons from hESCs line on HFFs feeder were lower than those of DA neurons from hESCs line on the MFCs feeder. In conclusion, HFFs feeder not only facilitated the differentiation of hESCs cells into dopaminergic neurons, but also induced hESCs-derived DA neurons to express higher electrophysiological excitability. Therefore, feeder cells could affect not only dopaminergic differentiation potential of different hESCs lines, but also electrophysiological properties of hESCs-derived DA neurons.

Progressive neurodegenerative and behavioural changes induced by AAV-mediated overexpression of α-synuclein in midbrain dopamine neurons

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Decressac, M; Mattsson, Bente; Lundblad, M

2012-01-01

-synuclein, we have now been able to achieve increased levels of α-synuclein in the transduced midbrain dopamine neurons sufficient to induce profound deficits in motor function, accompanied by reduced expression of proteins involved in dopamine neurotransmission and a time-dependent loss of nigral dopamine......Parkinson's disease (PD) is characterised by the progressive loss of nigral dopamine neurons and the presence of synucleinopathy. Overexpression of α-synuclein in vivo using viral vectors has opened interesting possibilities to model PD-like pathology in rodents. However, the attempts made so far...... have failed to show a consistent behavioural phenotype and pronounced dopamine neurodegeneration. Using a more efficient adeno-associated viral (AAV) vector construct, which includes a WPRE enhancer element and uses the neuron-specific synapsin-1 promoter to drive the expression of human wild-type α...

Curcumin ameliorates dopaminergic neuronal oxidative damage via activation of the Akt/Nrf2 pathway.

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Cui, Qunli; Li, Xin; Zhu, Hongcan

2016-02-01

Parkinson's disease (PD) is an age-related complex neurodegenerative disease that affects ≤ 80% of dopaminergic neurons in the substantia nigra pars compacta (SNpc). It has previously been suggested that mitochondrial dysfunction, oxidative stress and oxidative damage underlie the pathogenesis of PD. Curcumin, which is a major active polyphenol component extracted from the rhizomes of Curcuma longa (Zingiberaceae), has been reported to exert neuroprotective effects on an experimental model of PD. The present study conducted a series of in vivo experiments, in order to investigate the effects of curcumin on behavioral deficits, oxidative damage and related mechanisms. The results demonstrated that curcumin was able to significantly alleviate motor dysfunction and increase suppressed tyrosine hydroxylase (TH) activity in the SNpc of rotenone (ROT)-injured rats. Biochemical measurements indicated that rats pretreated with curcumin exhibited increased glutathione (GSH) levels, and reduced reactive oxygen species activity and malondialdehyde content. Mechanistic studies demonstrated that curcumin significantly restored the expression levels of heme oxygenase-1 and quinone oxidoreductase 1, thus ameliorating ROT-induced damage in vivo, via the phosphorylation of Akt and nuclear factor erythroid 2-related factor 2 (Nrf2). Further studies indicated that the Akt/Nrf2 signaling pathway was associated with the protective role of curcumin in ROT-treated rats. Inhibiting the Akt/Nrf2 pathway using a lentiviral vector containing Nrf2-specific short hairpin RNA, or the phosphoinositide 3-kinase inhibitor LY294002, markedly reduced the expression levels of TH and GSH, ultimately attenuating the neuroprotective effects of curcumin against oxidative damage. These results indicated that curcumin was able to significantly ameliorate ROT-induced dopaminergic neuronal oxidative damage in the SNpc of rats via activation of the Akt/Nrf2 signaling pathway.

Unaltered lactate and glucose transporter levels in the MPTP mouse model of Parkinson's disease

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Puchades, Maja; Sogn, Carl Johan; Maehlen, Jan

2013-01-01

BACKGROUND: Metabolic impairment contributes to development of Parkinson's disease (PD). Mitochondrial dysfunction is involved in degeneration of nigral dopamine neurons. Also, in PD there are alterations in glucose metabolism in nigro-striatal pathways, and increased cerebral lactate levels have...... of MCT1, MCT2 and GLUT1 is not changed following dopaminergic neurodegeneration. This is in contrast to findings in other neurodegenerative disease, such as mesial temporal lobe epilepsy, where there are large alterations in MCT levels....

Development of striatal patch/matrix organization in organotypic co-cultures of perinatal striatum, cortex and substantia nigra.

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Snyder-Keller, A; Costantini, L C; Graber, D J

2001-01-01

Organotypic cultures of fetal or early postnatal striatum were used to assess striatal patch formation and maintenance in the presence or absence of dopaminergic and glutamatergic influences. Vibratome-cut slices of the striatum prepared from embryonic day 19 to postnatal day 4 rat pups were maintained in static culture on clear membrane inserts in Dulbecco's modified Eagle's medium/F12 (1:1) with 20% horse serum. Some were co-cultured with embryonic day 12-16 ventral mesencephalon and/or embryonic day 19 to postnatal day 4 cortex, which produced a dense dopaminergic innervation and a modest cortical innervation. Donors of striatal and cortical tissue were previously injected with bromo-deoxyuridine (BrdU) on embryonic days 13 and 14 in order to label striatal neurons destined to populate the patch compartment of the striatum. Patches of BrdU-immunoreactive cells were maintained in organotypic cultures of late prenatal (embryonic days 20-22) or early postnatal striatum in the absence of nigral dopaminergic or cortical glutamatergic influences. In slices taken from embryonic day 19 fetuses prior to the time of in vivo patch formation, patches were observed to form after 10 days in vitro, in 39% of nigral-striatal co-cultures compared to 6% of striatal slices cultured alone or in the presence of cortex only. Patches of dopaminergic fibers, revealed by tyrosine hydroxylase immunoreactivity, were observed in the majority of nigral-striatal co-cultures. Immunostaining for the AMPA-type glutamate receptor GluR1 revealed a dense patch distribution in nearly all cultures, which developed in embryonic day 19 cultures after at least six days in vitro. These findings indicate that striatal patch/matrix organization is maintained in organotypic culture, and can be induced to form in vitro in striatal slices removed from fetuses prior to the time of in vivo patch formation. Furthermore, dopaminergic innervation from co-cultured pieces of ventral mesencephalon enhances patch

Dickkopf 3 Promotes the Differentiation of a Rostrolateral Midbrain Dopaminergic Neuronal Subset In Vivo and from Pluripotent Stem Cells In Vitro in the Mouse.

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Fukusumi, Yoshiyasu; Meier, Florian; Götz, Sebastian; Matheus, Friederike; Irmler, Martin; Beckervordersandforth, Ruth; Faus-Kessler, Theresa; Minina, Eleonora; Rauser, Benedict; Zhang, Jingzhong; Arenas, Ernest; Andersson, Elisabet; Niehrs, Christof; Beckers, Johannes; Simeone, Antonio; Wurst, Wolfgang; Prakash, Nilima

2015-09-30

Wingless-related MMTV integration site 1 (WNT1)/β-catenin signaling plays a crucial role in the generation of mesodiencephalic dopaminergic (mdDA) neurons, including the substantia nigra pars compacta (SNc) subpopulation that preferentially degenerates in Parkinson's disease (PD). However, the precise functions of WNT1/β-catenin signaling in this context remain unknown. Stem cell-based regenerative (transplantation) therapies for PD have not been implemented widely in the clinical context, among other reasons because of the heterogeneity and incomplete differentiation of the transplanted cells. This might result in tumor formation and poor integration of the transplanted cells into the dopaminergic circuitry of the brain. Dickkopf 3 (DKK3) is a secreted glycoprotein implicated in the modulation of WNT/β-catenin signaling. Using mutant mice, primary ventral midbrain cells, and pluripotent stem cells, we show that DKK3 is necessary and sufficient for the correct differentiation of a rostrolateral mdDA neuron subset. Dkk3 transcription in the murine ventral midbrain coincides with the onset of mdDA neurogenesis and is required for the activation and/or maintenance of LMX1A (LIM homeobox transcription factor 1α) and PITX3 (paired-like homeodomain transcription factor 3) expression in the corresponding mdDA precursor subset, without affecting the proliferation or specification of their progenitors. Notably, the treatment of differentiating pluripotent stem cells with recombinant DKK3 and WNT1 proteins also increases the proportion of mdDA neurons with molecular SNc DA cell characteristics in these cultures. The specific effects of DKK3 on the differentiation of rostrolateral mdDA neurons in the murine ventral midbrain, together with its known prosurvival and anti-tumorigenic properties, make it a good candidate for the improvement of regenerative and neuroprotective strategies in the treatment of PD. Significance statement: We show here that Dickkopf 3 (DKK3), a

Effect of superficial radial nerve stimulation on the activity of nigro-striatal dopaminergic neurons in the cat: role of cutaneous sensory input

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Nieoullon, A.; Dusticier, N.

1982-01-01

The release of 3 H-dopamine (DA) continuously synthesized from 3 H-thyrosine was measured in the caudate nucleus (CN) and in the substantia nigra (SN) in both sides of the brain during electrical stimulation of the superficial radial nerve in cats lightly anaesthetized with halothane. Use of appropriate electrophysiologically controlled stimulation led to selective activation of low threshold afferent fibers whereas high stimulation activated all cutaneous afferents. Results showed that low threshold fiber activation induced a decreased dopaminergic activity in CN contralateral to nerve stimulation and a concomitant increase in dopaminergic activity on the ipsilateral side. Stimulation of group I and threshold stimulation of group II afferent fibers induced changes in the release of 3 H-DA mainly on the contralateral CN and SN and in the ipsilateral CN. High stimulation was followed by a general increase of the neurotransmitter release in the four structures. This shows that the nigro-striatal dopaminergic neurons are mainly-if not exclusively-controlled by cutaneous sensory inputs. This control, non-specific when high threshold cutaneous fibers are also activated. Such activations could contribute to restablish sufficient release of DA when the dopaminergic function is impaired as in Parkinson's disease. (Author)

Effect of superficial radial nerve stimulation on the activity of nigro-striatal dopaminergic neurons in the cat: role of cutaneous sensory input

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Nieoullon, A; Dusticier, N [Centre National de la Recherche Scientifique, 13 - Marseille (France). Inst. de Neurophysiologie et Psychophysiologie

1982-01-01

The release of /sup 3/H-dopamine (DA) continuously synthesized from /sup 3/H-thyrosine was measured in the caudate nucleus (CN) and in the substantia nigra (SN) in both sides of the brain during electrical stimulation of the superficial radial nerve in cats lightly anaesthetized with halothane. Use of appropriate electrophysiologically controlled stimulation led to selective activation of low threshold afferent fibers whereas high stimulation activated all cutaneous afferents. Results showed that low threshold fiber activation induced a decreased dopaminergic activity in CN contralateral to nerve stimulation and a concomitant increase in dopaminergic activity on the ipsilateral side. Stimulation of group I and threshold stimulation of group II afferent fibers induced changes in the release of /sup 3/H-DA mainly on the contralateral CN and SN and in the ipsilateral CN. High stimulation was followed by a general increase of the neurotransmitter release in the four structures. This shows that the nigro-striatal dopaminergic neurons are mainly-if not exclusively-controlled by cutaneous sensory inputs. This control, non-specific when high threshold cutaneous fibers are also activated. Such activations could contribute to reestablish sufficient release of DA when the dopaminergic function is impaired as in Parkinson's disease.

Electrophysiological localization of distinct calcium potentials at selective somatodendritic sites in the substantia nigra

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Hounsgaard, J; Nedergaard, S; Greenfield, S A

1992-01-01

of differential polarization through applied electric fields, the cell body and dendrites have been activated in effective isolation during intracellular recordings from pars compacta neurons in the substantia nigra in vitro. In one class of neurons, which discharge in a "phasic" fashion and are located......The dendrites of dopaminergic neurons in the substantia nigra play a pivotal role in the neurochemical homeostasis of the nucleus. It is conceivable therefore that the cell body and dendrites of these nigral neurons possess distinct and independent electro-responsive features. By means......, a high-threshold calcium spike is located principally in the cell body. The differential localization of these calcium conductances in sub-populations of neurons is likely to determine the functions for the calcium responses in each type of neuron, and moreover highlight the dendrites as dynamic...

Neurotoxicity of cerebro-spinal fluid from patients with Parkinson's disease on mesencephalic primary cultures as an in vitro model of dopaminergic neurons.

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Kong, Ping; Zhang, Ben-Shu; Lei, Ping; Kong, Xiao-Dong; Zhang, Shi-Shuang; Li, Dai; Zhang, Yun

2015-08-01

Parkinson's disease is a degenerative disorder of the central nervous system. In spite of extensive research, neither the cause nor the mechanisms have been firmly established thus far. One assumption is that certain toxic substances may exist in the cerebro-spinal fluid (CSF) of Parkinson's disease patients. To confirm the neurotoxicity of CSF and study the potential correlation between neurotoxicity and the severity of Parkinson's disease, CSF was added to cultured cells. By observation of cell morphology, changes in the levels of lactate dehydrogenase, the ratio of tyrosine hydroxylase-positive cells, and the expression of tyrosine hydroxylase mRNA and protein, the differences between the two groups were shown. The created in vitro model of dopaminergic neurons using primary culture of mouse embryonic mesencephalic tissue is suitable for the study of neurotoxicity. The observations of the present study indicated that CSF from Parkinson's disease patients contains factors that can cause specific injury to cultured dopaminergic neurons. However, no obvious correlation was found between the neurotoxicity of CSF and the severity of Parkinson's disease.

Nanometer size diesel exhaust particles are selectively toxic to dopaminergic neurons: the role of microglia, phagocytosis, and NADPH oxidase.

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Block, M L; Wu, X; Pei, Z; Li, G; Wang, T; Qin, L; Wilson, B; Yang, J; Hong, J S; Veronesi, B

2004-10-01

The contributing role of environmental factors to the development of Parkinson's disease has become increasingly evident. We report that mesencephalic neuron-glia cultures treated with diesel exhaust particles (DEP; 0.22 microM) (5-50 microg/ml) resulted in a dose-dependent decrease in dopaminergic (DA) neurons, as determined by DA-uptake assay and tyrosine-hydroxylase immunocytochemistry (ICC). The selective toxicity of DEP for DA neurons was demonstrated by the lack of DEP effect on both GABA uptake and Neu-N immunoreactive cell number. The critical role of microglia was demonstrated by the failure of neuron-enriched cultures to exhibit DEP-induced DA neurotoxicity, where DEP-induced DA neuron death was reinstated with the addition of microglia to neuron-enriched cultures. OX-42 ICC staining of DEP treated neuron-glia cultures revealed changes in microglia morphology indicative of activation. Intracellular reactive oxygen species and superoxide were produced from enriched-microglia cultures in response to DEP. Neuron-glia cultures from NADPH oxidase deficient (PHOX-/-) mice were insensitive to DEP neurotoxicity when compared with control mice (PHOX+/+). Cytochalasin D inhibited DEP-induced superoxide production in enriched-microglia cultures, implying that DEP must be phagocytized by microglia to produce superoxide. Together, these in vitro data indicate that DEP selectively damages DA neurons through the phagocytic activation of microglial NADPH oxidase and consequent oxidative insult.

Reduced Number of Pigmented Neurons in the Substantia Nigra of Dystonia Patients? Findings from Extensive Neuropathologic, Immunohistochemistry, and Quantitative Analyses

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Diego Iacono

2015-05-01

Full Text Available Background: Dystonias (Dys represent the third most common movement disorder after essential tremor (ET and Parkinson's disease (PD. While some pathogenetic mechanisms and genetic causes of Dys have been identified, little is known about their neuropathologic features. Previous neuropathologic studies have reported generically defined neuronal loss in various cerebral regions of Dys brains, mostly in the basal ganglia (BG, and specifically in the substantia nigra (SN. Enlarged pigmented neurons in the SN of Dys patients with and without specific genetic mutations (e.g., GAG deletions in DYT1 dystonia have also been described. Whether or not Dys brains are associated with decreased numbers or other morphometric changes of specific neuronal types is unknown and has never been addressed with quantitative methodologies. Methods: Quantitative immunohistochemistry protocols were used to estimate neuronal counts and volumes of nigral pigmented neurons in 13 SN of Dys patients and 13 SN of age‐matched control subjects (C. Results: We observed a significant reduction (∼20% of pigmented neurons in the SN of Dys compared to C (p<0.01. Neither significant volumetric changes nor evident neurodegenerative signs were observed in the remaining pool of nigral pigmented neurons in Dys brains. These novel quantitative findings were confirmed after exclusion of possible co‐occurring SN pathologies including Lewy pathology, tau‐neurofibrillary tangles, β‐amyloid deposits, ubiquitin (ubiq, and phosphorylated‐TAR DNA‐binding protein 43 (pTDP43‐positive inclusions. Discussion: A reduced number of nigral pigmented neurons in the absence of evident neurodegenerative signs in Dys brains could indicate previously unconsidered pathogenetic mechanisms of Dys such as neurodevelopmental defects in the SN.

Renin angiotensin system and gender differences in dopaminergic degeneration

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Rodriguez-Perez Ana I

2011-08-01

Full Text Available Abstract Background There are sex differences in dopaminergic degeneration. Men are approximately two times as likely as premenopausal women of the same age to develop Parkinson's disease (PD. It has been shown that the local renin angiotensin system (RAS plays a prominent role in sex differences in the development of chronic renal and cardiovascular diseases, and there is a local RAS in the substantia nigra and dopaminergic cell loss is enhanced by angiotensin via type 1 (AT1 receptors. Results In the present study, we observed that intrastriatal injection of 6-hydroxydopamine induced a marked loss of dopaminergic neurons in the substantia nigra of male rats, which was significantly higher than the loss induced in ovariectomized female rats given estrogen implants (i.e. rats with estrogen. However, the loss of dopaminergic neurons was significantly lower in male rats treated with the AT1 antagonist candesartan, and similar to that observed in female rats with estrogen. The involvement of the RAS in gender differences in dopaminergic degeneration was confirmed with AT1a-null mice lesioned with the dopaminergic neurotoxin MPTP. Significantly higher expression of AT1 receptors, angiotensin converting enzyme activity, and NADPH-oxidase complex activity, and much lower levels of AT2 receptors were observed in male rats than in female rats with estrogen. Conclusions The results suggest that brain RAS plays a major role in the increased risk of developing PD in men, and that manipulation of brain RAS may be an efficient approach for neuroprotective treatment of PD in men, without the feminizing effects of estrogen.

Cholinergic and dopaminergic neuronal differentiation of human adipose tissue derived mesenchymal stem cells.

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Marei, Hany El Sayed; El-Gamal, Aya; Althani, Asma; Afifi, Nahla; Abd-Elmaksoud, Ahmed; Farag, Amany; Cenciarelli, Carlo; Thomas, Caceci; Anwarul, Hasan

2018-02-01

Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into various cell types such as cartilage, bone, and fat cells. Recent studies have shown that induction of MSCs in vitro by growth factors including epidermal growth factor (EGF) and fibroblast growth factor (FGF2) causes them to differentiate into neural like cells. These cultures also express ChAT, a cholinergic marker; and TH, a dopaminergic marker for neural cells. To establish a protocol with maximum differentiation potential, we examined MSCs under three experimental culture conditions using neural induction media containing FGF2, EGF, BMP-9, retinoic acid, and heparin. Adipose-derived MSCs were extracted and expanded in vitro for 3 passages after reaching >80% confluency, for a total duration of 9 days. Cells were then characterized by flow cytometry for CD markers as CD44 positive and CD45 negative. MSCs were then treated with neural induction media and were characterized by morphological changes and Q-PCR. Differentiated MSCs expressed markers for immature and mature neurons; β Tubulin III (TUBB3) and MAP2, respectively, showing the neural potential of these cells to differentiate into functional neurons. Improved protocols for MSCs induction will facilitate and ensure the reproducibility and standard production of MSCs for therapeutic applications in neurodegenerative diseases. © 2017 Wiley Periodicals, Inc.

Histamine induces microglia activation and dopaminergic neuronal toxicity via H1 receptor activation.

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Rocha, Sandra M; Saraiva, Tatiana; Cristóvão, Ana C; Ferreira, Raquel; Santos, Tiago; Esteves, Marta; Saraiva, Cláudia; Je, Goun; Cortes, Luísa; Valero, Jorge; Alves, Gilberto; Klibanov, Alexander; Kim, Yoon-Seong; Bernardino, Liliana

2016-06-04

Histamine is an amine widely known as a peripheral inflammatory mediator and as a neurotransmitter in the central nervous system. Recently, it has been suggested that histamine acts as an innate modulator of microglial activity. Herein, we aimed to disclose the role of histamine in microglial phagocytic activity and reactive oxygen species (ROS) production and to explore the consequences of histamine-induced neuroinflammation in dopaminergic (DA) neuronal survival. The effect of histamine on phagocytosis was assessed both in vitro by using a murine N9 microglial cell line and primary microglial cell cultures and in vivo. Cells were exposed to IgG-opsonized latex beads or phosphatidylserine (PS) liposomes to evaluate Fcγ or PS receptor-mediated microglial phagocytosis, respectively. ROS production and protein levels of NADPH oxidases and Rac1 were assessed as a measure of oxidative stress. DA neuronal survival was evaluated in vivo by counting the number of tyrosine hydroxylase-positive neurons in the substantia nigra (SN) of mice. We found that histamine triggers microglial phagocytosis via histamine receptor 1 (H1R) activation and ROS production via H1R and H4R activation. By using apocynin, a broad NADPH oxidase (Nox) inhibitor, and Nox1 knockout mice, we found that the Nox1 signaling pathway is involved in both phagocytosis and ROS production induced by histamine in vitro. Interestingly, both apocynin and annexin V (used as inhibitor of PS-induced phagocytosis) fully abolished the DA neurotoxicity induced by the injection of histamine in the SN of adult mice in vivo. Blockade of H1R protected against histamine-induced Nox1 expression and death of DA neurons in vivo. Overall, our results highlight the relevance of histamine in the modulation of microglial activity that ultimately may interfere with neuronal survival in the context of Parkinson's disease (PD) and, eventually, other neurodegenerative diseases which are accompanied by microglia

An imperfect dopaminergic error signal can drive temporal-difference learning.

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Wiebke Potjans

2011-05-01

Full Text Available An open problem in the field of computational neuroscience is how to link synaptic plasticity to system-level learning. A promising framework in this context is temporal-difference (TD learning. Experimental evidence that supports the hypothesis that the mammalian brain performs temporal-difference learning includes the resemblance of the phasic activity of the midbrain dopaminergic neurons to the TD error and the discovery that cortico-striatal synaptic plasticity is modulated by dopamine. However, as the phasic dopaminergic signal does not reproduce all the properties of the theoretical TD error, it is unclear whether it is capable of driving behavior adaptation in complex tasks. Here, we present a spiking temporal-difference learning model based on the actor-critic architecture. The model dynamically generates a dopaminergic signal with realistic firing rates and exploits this signal to modulate the plasticity of synapses as a third factor. The predictions of our proposed plasticity dynamics are in good agreement with experimental results with respect to dopamine, pre- and post-synaptic activity. An analytical mapping from the parameters of our proposed plasticity dynamics to those of the classical discrete-time TD algorithm reveals that the biological constraints of the dopaminergic signal entail a modified TD algorithm with self-adapting learning parameters and an adapting offset. We show that the neuronal network is able to learn a task with sparse positive rewards as fast as the corresponding classical discrete-time TD algorithm. However, the performance of the neuronal network is impaired with respect to the traditional algorithm on a task with both positive and negative rewards and breaks down entirely on a task with purely negative rewards. Our model demonstrates that the asymmetry of a realistic dopaminergic signal enables TD learning when learning is driven by positive rewards but not when driven by negative rewards.

Minocycline Rescues from Zinc-Induced Nigrostriatal Dopaminergic Neurodegeneration: Biochemical and Molecular Interventions.

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Kumar, Vinod; Singh, Brajesh Kumar; Chauhan, Amit Kumar; Singh, Deepali; Patel, Devendra Kumar; Singh, Chetna

2016-07-01

Accumulation of zinc (Zn) in dopaminergic neurons is implicated in Parkinson's disease (PD), and microglial activation plays a critical role in toxin-induced Parkinsonism. Oxidative stress is accused in Zn-induced dopaminergic neurodegeneration; however, its connection with microglial activation is still not known. This study was undertaken to elucidate the role and underlying mechanism of microglial activation in Zn-induced nigrostriatal dopaminergic neurodegeneration. Male Wistar rats were treated intraperitoneally with/without zinc sulphate (20 mg/kg) in the presence/absence of minocycline (30 mg/kg), a microglial activation inhibitor, for 2-12 weeks. While neurobehavioral and biochemical indexes of PD and number of dopaminergic neurons were reduced, the number of microglial cells was increased in the substantia nigra of the Zn-exposed animals. Similarly, Zn elevated lipid peroxidation (LPO) and activities of superoxide dismutase (SOD) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase; however, catalase activity was reduced. Besides, Zn increased an association of NADPH oxidase subunit p67(phox) with membrane, cytochrome c release from the mitochondria and cleavage of pro-caspase 3. Zn attenuated the expression of tyrosine hydroxylase (TH) and vesicular monoamine transporter-2 (VMAT-2) while augmented the expression of dopamine transporter (DAT) and heme oxygenase-1 (HO-1). Minocycline alleviated Zn-induced behavioural impairments, loss of TH-positive neurons, activated microglial cells and biochemical indexes and modulated the expression of studied genes/proteins towards normalcy. The results demonstrate that minocycline reduces the number of activated microglial cells and oxidative stress, which rescue from Zn-induced changes in the expression of monoamine transporter and nigrostriatal dopaminergic neurodegeneration.

Novel Pattern of Iron Deposition in the Fascicula Nigrale in Patients with Parkinson's Disease: A Pilot Study

International Nuclear Information System (INIS)

Peckham, Miriam E.; Dashtipour, Khashayar; Holshouser, Barbara A.; Kani, Camellia; Boscanin, Alex; Kani, Kayvan; Harder, Sheri L.

2016-01-01

Background and Purpose. To determine whether the pattern of iron deposition in the fascicula nigrale in patients with Parkinson's disease would be different from age-matched controls by utilizing quantitative susceptibility mapping to measure susceptibility change. Methods. MRIs of the brain were obtained from 34 subjects, 18 with Parkinson's disease and 16 age- and gender-matched controls. Regions of interest were drawn around the fascicula nigrale and substantia nigra using SWI mapping software by blinded investigators. Statistical analyses were performed to determine susceptibility patterns of both of these regions. Results. Measurements showed significantly increased susceptibility in the substantia nigra in Parkinson's patients and an increased rostral-caudal deposition of iron in the fascicula nigrale in all subjects. This trend was exaggerated with significant correlation noted with increasing age in the Parkinson group. Conclusion. The pattern of an exaggerated iron deposition gradient of the fascicula nigrale in the Parkinson group could represent underlying tract dysfunction. Significant correlation of increasing iron deposition with increasing age may be a cumulative effect, possibly related to disease duration

Electroacupuncture Promotes Recovery of Motor Function and Reduces Dopaminergic Neuron Degeneration in Rodent Models of Parkinson's Disease.

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Lin, Jaung-Geng; Chen, Chao-Jung; Yang, Han-Bin; Chen, Yi-Hung; Hung, Shih-Ya

2017-08-24

Parkinson's disease (PD) is a common neurodegenerative disease. The pathological hallmark of PD is a progressive loss of dopaminergic neurons in the substantia nigra (SN) pars compacta in the brain, ultimately resulting in severe striatal dopamine deficiency and the development of primary motor symptoms (e.g., resting tremor, bradykinesia) in PD. Acupuncture has long been used in traditional Chinese medicine to treat PD for the control of tremor and pain. Accumulating evidence has shown that using electroacupuncture (EA) as a complementary therapy ameliorates motor symptoms of PD. However, the most appropriate timing for EA intervention and its effect on dopamine neuronal protection remain unclear. Thus, this study used the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mouse model (systemic-lesioned by intraperitoneal injection) and the 1-methyl-4-phenylpyridinium (MPP⁺)-lesioned rat model (unilateral-lesioned by intra-SN infusion) of PD, to explore the therapeutic effects and mechanisms of EA at the GB34 (Yanglingquan) and LR3 (Taichong) acupoints. We found that EA increased the latency to fall from the accelerating rotarod and improved striatal dopamine levels in the MPTP studies. In the MPP⁺ studies, EA inhibited apomorphine induced rotational behavior and locomotor activity, and demonstrated neuroprotective effects via the activation of survival pathways of Akt and brain-derived neurotrophic factor (BDNF) in the SN region. In conclusion, we observed that EA treatment reduces motor symptoms of PD and dopaminergic neurodegeneration in rodent models, whether EA is given as a pretreatment or after the initiation of disease symptoms. The results indicate that EA treatment may be an effective therapy for patients with PD.

Contribution of synchronized GABAergic neurons to dopaminergic neuron firing and bursting.

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Morozova, Ekaterina O; Myroshnychenko, Maxym; Zakharov, Denis; di Volo, Matteo; Gutkin, Boris; Lapish, Christopher C; Kuznetsov, Alexey

2016-10-01

In the ventral tegmental area (VTA), interactions between dopamine (DA) and γ-aminobutyric acid (GABA) neurons are critical for regulating DA neuron activity and thus DA efflux. To provide a mechanistic explanation of how GABA neurons influence DA neuron firing, we developed a circuit model of the VTA. The model is based on feed-forward inhibition and recreates canonical features of the VTA neurons. Simulations revealed that γ-aminobutyric acid (GABA) receptor (GABAR) stimulation can differentially influence the firing pattern of the DA neuron, depending on the level of synchronization among GABA neurons. Asynchronous activity of GABA neurons provides a constant level of inhibition to the DA neuron and, when removed, produces a classical disinhibition burst. In contrast, when GABA neurons are synchronized by common synaptic input, their influence evokes additional spikes in the DA neuron, resulting in increased measures of firing and bursting. Distinct from previous mechanisms, the increases were not based on lowered firing rate of the GABA neurons or weaker hyperpolarization by the GABAR synaptic current. This phenomenon was induced by GABA-mediated hyperpolarization of the DA neuron that leads to decreases in intracellular calcium (Ca 2+ ) concentration, thus reducing the Ca 2+ -dependent potassium (K + ) current. In this way, the GABA-mediated hyperpolarization replaces Ca 2+ -dependent K + current; however, this inhibition is pulsatile, which allows the DA neuron to fire during the rhythmic pauses in inhibition. Our results emphasize the importance of inhibition in the VTA, which has been discussed in many studies, and suggest a novel mechanism whereby computations can occur locally. Copyright © 2016 the American Physiological Society.

Chronic organic manganese administration in the rat does not damage dopaminergic nigrostriatal neurons.

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Yong, V W; Perry, T L; Godolphin, W J; Jones, K A; Clavier, R M; Ito, M; Foulks, J G

1986-01-01

In an attempt to produce an animal model of Parkinson's disease, we injected rats repeatedly with high doses of methylcyclopentadienyl manganese tricarbonyl (MMT), a compound which has been reported to lower striatal dopamine content in mice. Chronic MMT administration for up to 5 months, even though it produced a substantial elevation in brain manganese content during the period of exposure, did not destroy dopaminergic nigrostriatal neurons. This was assessed by measurements of tyrosine hydroxylase activity and contents of dopamine and its metabolites in the striatum, and by histological examination of the substantia nigra. Our results differ from those of others who administered manganese chloride in drinking water to rats. This discrepancy is unlikely to be a consequence of differences in duration of exposure or route of administration. It could be due to our having used an organic rather than an inorganic manganese compound, or to a species difference in vulnerability to organic manganese between rats and mice.

Analysis of mice with targeted deletion of AQP9 gene provides conclusive evidence for expression of AQP9 in neurons

DEFF Research Database (Denmark)

Mylonakou, Maria N; Petersen, Petur H; Rinvik, Eric

2009-01-01

and in situ hybridization analyses with AQP9 knockout controls show that subpopulations of nigral neurons express AQP9 both at the mRNA and at the protein levels and that populations of cortical cells (including hilar neurons in the hippocampus) contain AQP9 mRNA but no detectable AQP9 immunosignal...

Genetic reduction of mitochondrial complex I function does not lead to loss of dopamine neurons in vivo.

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Kim, Hyung-Wook; Choi, Won-Seok; Sorscher, Noah; Park, Hyung Joon; Tronche, François; Palmiter, Richard D; Xia, Zhengui

2015-09-01

Inhibition of mitochondrial complex I activity is hypothesized to be one of the major mechanisms responsible for dopaminergic neuron death in Parkinson's disease. However, loss of complex I activity by systemic deletion of the Ndufs4 gene, one of the subunits comprising complex I, does not cause dopaminergic neuron death in culture. Here, we generated mice with conditional Ndufs4 knockout in dopaminergic neurons (Ndufs4 conditional knockout mice [cKO]) to examine the effect of complex I inhibition on dopaminergic neuron function and survival during aging and on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment in vivo. Ndufs4 cKO mice did not show enhanced dopaminergic neuron loss in the substantia nigra pars compacta or dopamine-dependent motor deficits over the 24-month life span. These mice were just as susceptible to MPTP as control mice. However, compared with control mice, Ndufs4 cKO mice exhibited an age-dependent reduction of dopamine in the striatum and increased α-synuclein phosphorylation in dopaminergic neurons of the substantia nigra pars compacta. We also used an inducible Ndufs4 knockout mouse strain (Ndufs4 inducible knockout) in which Ndufs4 is conditionally deleted in all cells in adult to examine the effect of adult onset, complex I inhibition on MPTP sensitivity of dopaminergic neurons. The Ndufs4 inducible knockout mice exhibited similar sensitivity to MPTP as control littermates. These data suggest that mitochondrial complex I inhibition in dopaminergic neurons does contribute to dopamine loss and the development of α-synuclein pathology. However, it is not sufficient to cause cell-autonomous dopaminergic neuron death during the normal life span of mice. Furthermore, mitochondrial complex I inhibition does not underlie MPTP toxicity in vivo in either cell autonomous or nonautonomous manner. These results provide strong evidence that inhibition of mitochondrial complex I activity is not sufficient to cause dopaminergic neuron

Glucocorticoids have state-dependent stimulant effects on the mesencephalic dopaminergic transmission.

OpenAIRE

Piazza, P V; Rougé-Pont, F; Deroche, V; Maccari, S; Simon, H; Le Moal, M

1996-01-01

An increase in the activity of mesencephalic dopaminergic neurons has been implicated in the appearance of pathological behaviors such as psychosis and drug abuse. Several observations suggest that glucocorticoids might contribute to such an increase in dopaminergic activity. The present experiments therefore analyzed the effects of corticosterone, the major glucocorticoid in the rat, both on dopamine release in the nucleus accumbens of freely moving animals by means of microdialysis, and on ...

SH-SY5Y human neuroblastoma cell line: in vitro cell model of dopaminergic neurons in Parkinson's disease.

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Xie, Hong-rong; Hu, Lin-sen; Li, Guo-yi

2010-04-20

To evaluate the human neuroblastoma SH-SY5Y cell line as an in vitro model of dopaminergic (DAergic) neurons for Parkinson's disease (PD) research and to determine the effect of differentiation on this cell model. The data of this review were selected from the original reports and reviews related to SH-SY5Y cells published in Chinese and foreign journals (Pubmed 1973 to 2009). After searching the literature, 60 articles were selected to address this review. The SH-SY5Y cell line has become a popular cell model for PD research because this cell line posses many characteristics of DAergic neurons. For example, these cells express tyrosine hydroxylase and dopamine-beta-hydroxylase, as well as the dopamine transporter. Moreover, this cell line can be differentiated into a functionally mature neuronal phenotype in the presence of various agents. Upon differentiation, SH-SY5Y cells stop proliferating and a constant cell number is subsequently maintained. However, different differentiating agents induce different neuronal phenotypes and biochemical changes. For example, retinoic acid induces differentiation toward a cholinergic neuronal phenotype and increases the susceptibility of SH-SY5Y cells to neurotoxins and neuroprotective agents, whereas treatment with retinoic acid followed by phorbol ester 12-O-tetradecanoylphorbol-13-acetate results in a DAergic neuronal phenotype and decreases the susceptibility of cells to neurotoxins and neuroprotective agents. Some differentiating agents also alter kinetics of 1-methyl-4-phenyl-pyridinium (MPP(+)) uptake, making SH-SY5Y cells more similar to primary mesencephalic neurons. Differentiated and undifferentiated SH-SY5Y cells have been widely used as a cell model of DAergic neurons for PD research. Some differentiating agents afford SH-SY5Y cells with more potential for studying neurotoxicity and neuroprotection and are thus more relevant to experimental PD research.

Tiam1 Regulates the Wnt/Dvl/Rac1 Signaling Pathway and the Differentiation of Midbrain Dopaminergic Neurons

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Čajánek, Lukáš; Ganji, Ranjani Sri; Henriques-Oliveira, Catarina; Theofilopoulos, Spyridon; Koník, Peter

2013-01-01

Understanding the mechanisms that drive the differentiation of dopaminergic (DA) neurons is crucial for successful development of novel therapies for Parkinson's disease, in which DA neurons progressively degenerate. However, the mechanisms underlying the differentiation-promoting effects of Wnt5a on DA precursors are poorly understood. Here, we present the molecular and functional characterization of a signaling pathway downstream of Wnt5a, the Wnt/Dvl/Rac1 pathway. First, we characterize the interaction between Rac1 and Dvl and identify the N-terminal part of Dvl3 as necessary for Rac1 binding. Next, we show that Tiam1, a Rac1 guanosine exchange factor (GEF), is expressed in the ventral midbrain, interacts with Dvl, facilitates Dvl-Rac1 interaction, and is required for Dvl- or Wnt5a-induced activation of Rac1. Moreover, we show that Wnt5a promotes whereas casein kinase 1 (CK1), a negative regulator of the Wnt/Dvl/Rac1 pathway, abolishes the interactions between Dvl and Tiam1. Finally, using ventral midbrain neurosphere cultures, we demonstrate that the generation of DA neurons in culture is impaired after Tiam1 knockdown, indicating that Tiam1 is required for midbrain DA differentiation. In summary, our data identify Tiam1 as a novel regulator of DA neuron development and as a Dvl-associated and Rac1-specific GEF acting in the Wnt/Dvl/Rac1 pathway. PMID:23109420

Improved cell therapy protocols for Parkinson's disease based on differentiation efficiency and safety of hESC-, hiPSC-, and non-human primate iPSC-derived dopaminergic neurons

DEFF Research Database (Denmark)

Sundberg, Maria; Bogetofte, Helle; Lawson, Tristan

2013-01-01

of safety and efficacy of stem cell-derived DA neurons. The aim of this study was to improve the safety of human- and non-human primate iPSC (PiPSC)-derived DA neurons. According to our results, NCAM(+) /CD29(low) sorting enriched VM DA neurons from pluripotent stem cell-derived neural cell populations......The main motor symptoms of Parkinson's disease are due to the loss of dopaminergic (DA) neurons in the ventral midbrain (VM). For the future treatment of Parkinson's disease with cell transplantation it is important to develop efficient differentiation methods for production of human iPSCs and h......ESCs-derived midbrain-type DA neurons. Here we describe an efficient differentiation and sorting strategy for DA neurons from both human ES/iPS cells and non-human primate iPSCs. The use of non-human primate iPSCs for neuronal differentiation and autologous transplantation is important for preclinical evaluation...

Activation of NF-κB is involved in 6-hydroxydopamine-but not MPP+-induced dopaminergic neuronal cell death: its potential role as a survival determinant

International Nuclear Information System (INIS)

Park, Seong H.; Choi, Won-Seok; Yoon, So-Young; Ahn, Young Soo; Oh, Young J.

2004-01-01

The nuclear factor-kappaB (NF-κB) family plays an important role in the control of the apoptotic response. Its activation has been demonstrated in both neurons and glial cells in many neurological disorders. In the present study, we specifically examined whether and to what extent NF-κB activation is involved in culture models of Parkinson's disease following exposure of MN9D dopaminergic neuronal cells to 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenyl-4-phenylpyridinium ion (MPP + ). Both analysis by immunocytochemistry and of immunoblots revealed that NF-κB-p65 was translocated into the nuclei following 6-OHDA but not MPP + -treatment. A time-dependent activation of NF-κB induced by 6-OHDA but not MPP + was also demonstrated by an electrophoretic mobility shift assay. A competition assay indicated that not only NF-κB-p65 but also -p50 is involved in 6-OHDA-induced NF-κB activity. Co-treatment with an antioxidant, N-acetyl-L-cysteine, blocked 6-OHDA-induced activation of NF-κB signaling. In the presence of an NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC), 6-OHDA-induced cell death was accelerated while PDTC did not affect MPP + -induced cell death. Our data may point to a drug-specific activation of NF-κB as a survival determinant for dopaminergic neurons

Diffusion tensor imaging of nigral degeneration in Parkinson's disease: A region-of-interest and voxel-based study at 3 T and systematic review with meta-analysis☆

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Schwarz, Stefan T.; Abaei, Maryam; Gontu, Vamsi; Morgan, Paul S.; Bajaj, Nin; Auer, Dorothee P.

2013-01-01

There is increasing interest in developing a reliable, affordable and accessible disease biomarker of Parkinson's disease (PD) to facilitate disease modifying PD-trials. Imaging biomarkers using magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) can describe parameters such as fractional anisotropy (FA), mean diffusivity (MD) or apparent diffusion coefficient (ADC). These parameters, when measured in the substantia nigra (SN), have not only shown promising but also varying and controversial results. To clarify the potential diagnostic value of nigral DTI in PD and its dependency on selection of region-of-interest, we undertook a high resolution DTI study at 3 T. 59 subjects (32 PD patients, 27 age and sex matched healthy controls) were analysed using manual outlining of SN and substructures, and voxel-based analysis (VBA). We also performed a systematic literature review and meta-analysis to estimate the effect size (DES) of disease related nigral DTI changes. We found a regional increase in nigral mean diffusivity in PD (mean ± SD, PD 0.80 ± 0.10 vs. controls 0.73 ± 0.06 · 10− 3 mm2/s, p = 0.002), but no difference using a voxel based approach. No significant disease effect was seen using meta-analysis of nigral MD changes (10 studies, DES = + 0.26, p = 0.17, I2 = 30%). None of the nigral regional or voxel based analyses of this study showed altered fractional anisotropy. Meta-analysis of 11 studies on nigral FA changes revealed a significant PD induced FA decrease. There was, however, a very large variation in results (I2 = 86%) comparing all studies. After exclusion of five studies with unusual high values of nigral FA in the control group, an acceptable heterogeneity was reached, but there was non-significant disease effect (DES = − 0.5, p = 0.22, I2 = 28%). The small PD related nigral MD changes in conjunction with the negative findings on VBA and meta-analysis limit the usefulness of nigral MD measures as

Pro-survival role for Parkinson's associated gene DJ-1 revealed in trophically impaired dopaminergic neurons.

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Liviu Aron

2010-04-01

Full Text Available The mechanisms underlying the selective death of substantia nigra (SN neurons in Parkinson disease (PD remain elusive. While inactivation of DJ-1, an oxidative stress suppressor, causes PD, animal models lacking DJ-1 show no overt dopaminergic (DA neuron degeneration in the SN. Here, we show that aging mice lacking DJ-1 and the GDNF-receptor Ret in the DA system display an accelerated loss of SN cell bodies, but not axons, compared to mice that only lack Ret signaling. The survival requirement for DJ-1 is specific for the GIRK2-positive subpopulation in the SN which projects exclusively to the striatum and is more vulnerable in PD. Using Drosophila genetics, we show that constitutively active Ret and associated Ras/ERK, but not PI3K/Akt, signaling components interact genetically with DJ-1. Double loss-of-function experiments indicate that DJ-1 interacts with ERK signaling to control eye and wing development. Our study uncovers a conserved interaction between DJ-1 and Ret-mediated signaling and a novel cell survival role for DJ-1 in the mouse. A better understanding of the molecular connections between trophic signaling, cellular stress and aging could uncover new targets for drug development in PD.

Intracellular Methamphetamine Prevents the Dopamine-induced Enhancement of Neuronal Firing*

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Saha, Kaustuv; Sambo, Danielle; Richardson, Ben D.; Lin, Landon M.; Butler, Brittany; Villarroel, Laura; Khoshbouei, Habibeh

2014-01-01

The dysregulation of the dopaminergic system is implicated in multiple neurological and neuropsychiatric disorders such as Parkinson disease and drug addiction. The primary target of psychostimulants such as amphetamine and methamphetamine is the dopamine transporter (DAT), the major regulator of extracellular dopamine levels in the brain. However, the behavioral and neurophysiological correlates of methamphetamine and amphetamine administration are unique from one another, thereby suggesting these two compounds impact dopaminergic neurotransmission differentially. We further examined the unique mechanisms by which amphetamine and methamphetamine regulate DAT function and dopamine neurotransmission; in the present study we examined the impact of extracellular and intracellular amphetamine and methamphetamine on the spontaneous firing of cultured midbrain dopaminergic neurons and isolated DAT-mediated current. In dopaminergic neurons the spontaneous firing rate was enhanced by extracellular application of amphetamine > dopamine > methamphetamine and was DAT-dependent. Amphetamine > methamphetamine similarly enhanced DAT-mediated inward current, which was sensitive to isosmotic substitution of Na+ or Cl− ion. Although isosmotic substitution of extracellular Na+ ions blocked amphetamine and methamphetamine-induced DAT-mediated inward current similarly, the removal of extracellular Cl− ions preferentially blocked amphetamine-induced inward current. The intracellular application of methamphetamine, but not amphetamine, prevented the dopamine-induced increase in the spontaneous firing of dopaminergic neurons and the corresponding DAT-mediated inward current. The results reveal a new mechanism for methamphetamine-induced dysregulation of dopaminergic neurons. PMID:24962577

Dopaminergic expression of the Parkinsonian gene LRRK2-G2019S leads to non-autonomous visual neurodegeneration, accelerated by increased neural demands for energy

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Hindle, Samantha; Afsari, Farinaz; Stark, Meg; Middleton, C. Adam; Evans, Gareth J.O.; Sweeney, Sean T.; Elliott, Christopher J.H.

2013-01-01

Parkinson's disease (PD) is associated with loss of dopaminergic signalling, and affects not just movement, but also vision. As both mammalian and fly visual systems contain dopaminergic neurons, we investigated the effect of LRRK2 mutations (the most common cause of inherited PD) on Drosophila electroretinograms (ERGs). We reveal progressive loss of photoreceptor function in flies expressing LRRK2-G2019S in dopaminergic neurons. The photoreceptors showed elevated autophagy, apoptosis and mitochondrial disorganization. Head sections confirmed extensive neurodegeneration throughout the visual system, including regions not directly innervated by dopaminergic neurons. Other PD-related mutations did not affect photoreceptor function, and no loss of vision was seen with kinase-dead transgenics. Manipulations of the level of Drosophila dLRRK suggest G2019S is acting as a gain-of-function, rather than dominant negative mutation. Increasing activity of the visual system, or of just the dopaminergic neurons, accelerated the G2019S-induced deterioration of vision. The fly visual system provides an excellent, tractable model of a non-autonomous deficit reminiscent of that seen in PD, and suggests that increased energy demand may contribute to the mechanism by which LRRK2-G2019S causes neurodegeneration. PMID:23396536

Role for excitatory amino acids in methamphetamine-induced nigrostriatal dopaminergic toxicity.

Science.gov (United States)

Sonsalla, P K; Nicklas, W J; Heikkila, R E

1989-01-20

The systemic administration of either methamphetamine or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to experimental animals produces degenerative changes in nigrostriatal dopaminergic neurons or their axon terminals. This study was conducted to determine if excitatory amino acids, which appear to be involved in various neurodegenerative disorders, might also contribute to the dopaminergic neurotoxicity produced in mice by either methamphetamine or MPTP. MK-801, phencyclidine, and ketamine, noncompetitive antagonists of one subtype of excitatory amino acid receptor, the N-methyl-D-aspartate receptor, provided substantial protection against neurotoxicity produced by methamphetamine but not that produced by MPTP. These findings indicate that excitatory amino acids play an important role in the nigrostriatal dopaminergic damage induced by methamphetamine.

Control of sleep by dopaminergic inputs to the Drosophila mushroom body

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Divya eSitaraman

2015-11-01

Full Text Available The Drosophila mushroom body (MB is an associative learning network that is important for the control of sleep. We have recently identified particular intrinsic MB Kenyon cell (KC classes that regulate sleep through synaptic activation of particular MB output neurons (MBONs whose axons convey sleep control signals out of the MB to downstream target regions. Specifically, we found that sleep-promoting KCs increase sleep by preferentially activating cholinergic sleep-promoting MBONs, while wake-promoting KCs decrease sleep by preferentially activating glutamatergic wake-promoting MBONs. Here we use a combination of genetic and physiological approaches to identify wake-promoting dopaminergic neurons (DANs that innervate the MB, and show that they activate wake-promoting MBONs. These studies reveal a dopaminergic sleep control mechanism that likely operates by modulation of KC-MBON microcircuits.

N-Acetyl Cysteine Protects against Methamphetamine-Induced Dopaminergic Neurodegeneration via Modulation of Redox Status and Autophagy in Dopaminergic Cells

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Prashanth Chandramani Shivalingappa

2012-01-01

Full Text Available Methamphetamine- (MA- induced neurotoxicity is associated with mitochondrial dysfunction and enhanced oxidative stress. Our previous study demonstrated that MA induces autophagy in a dopaminergic neuronal cell model (N27 cells. The cellular mechanisms underlying MA-induced autophagy and apoptosis remain poorly characterized. In the present study we sought to investigate the importance of GSH redox status in MA-induced neurotoxicity using a thiol antioxidant, N-acetylcysteine (NAC. Morphological and biochemical analysis revealed that MA-induced autophagy in N27 dopaminergic cells was associated with pronounced depletion of GSH levels. Moreover, pretreatment with NAC reduced MA-induced GSH depletion and autophagy, while depletion of GSH using L-buthionine sulfoximine (L-BSO enhanced autophagy. Furthermore, treatment with NAC significantly attenuated MA-induced apoptotic cell death as well as oxidative stress markers, namely, 3-nitrotyrosine (3-NT and 4-hydroxynonenal (4-HNE. Together, these results suggest that NAC exhibits significant protective effects against MA-induced dopaminergic cell death, presumably via modulation of the GSH level and autophagy. Collectively, our data provide mechanistic insights into the role of cellular GSH redox status in MA-induced autophagy and apoptotic cell death, and additional studies are needed to determine the therapeutic effectiveness of cellular redox modifiers in attenuating dopaminergic neurodegeneration in vivo.

Overexpression of miR-185 inhibits autophagy and apoptosis of dopaminergic neurons by regulating the AMPK/mTOR signaling pathway in Parkinson's disease

OpenAIRE

Wen, Zhi; Zhang, Jie; Tang, Peng; Tu, Ning; Wang, Ke; Wu, Guangyao

2017-01-01

Parkinson's disease (PD) is an age-associated neurodegenerative disorder characterized by the death of dopaminergic neurons in the substantia nigra pars compacta. Activation of 5′-adenosine monophosphate-activated protein kinase (AMPK) has been suggested to be associated with PD pathogenesis. The aim of the present study was to investigate the effects of the aberrant expression of microRNA-185 (miR-185) in PD. A 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced in vitro model of PD ...

Effects of manganese on tyrosine hydroxylase (TH) activity and TH-phosphorylation in a dopaminergic neural cell line

International Nuclear Information System (INIS)

Zhang Danhui; Kanthasamy, Arthi; Anantharam, Vellareddy; Kanthasamy, Anumantha

2011-01-01

Manganese (Mn) exposure causes manganism, a neurological disorder similar to Parkinson's disease. However, the cellular mechanism by which Mn impairs the dopaminergic neurotransmitter system remains unclear. We previously demonstrated that caspase-3-dependent proteolytic activation of protein kinase C delta (PKCδ) plays a key role in Mn-induced apoptotic cell death in dopaminergic neurons. Recently, we showed that PKCδ negatively regulates tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine synthesis, by enhancing protein phosphatase-2A activity in dopaminergic neurons. Here, we report that Mn exposure can affect the enzymatic activity of TH, the rate-limiting enzyme in dopamine synthesis, by activating PKCδ-PP2A signaling pathway in a dopaminergic cell model. Low dose Mn (3-10 μM) exposure to differentiated mesencephalic dopaminergic neuronal cells for 3 h induced a significant increase in TH activity and phosphorylation of TH-Ser40. The PKCδ specific inhibitor rottlerin did not prevent Mn-induced TH activity or TH-Ser40 phosphorylation. On the contrary, chronic exposure to 0.1-1 μM Mn for 24 h induced a dose-dependent decrease in TH activity. Interestingly, chronic Mn treatment significantly increased PKCδ kinase activity and protein phosphatase 2A (PP2A) enzyme activity. Treatment with the PKCδ inhibitor rottlerin almost completely prevented chronic Mn-induced reduction in TH activity, as well as increased PP2A activity. Neither acute nor chronic Mn exposures induced any cytotoxic cell death or altered TH protein levels. Collectively, these results demonstrate that low dose Mn exposure impairs TH activity in dopaminergic cells through activation of PKCδ and PP2A activity.

Th17 Cells Induce Dopaminergic Neuronal Death via LFA-1/ICAM-1 Interaction in a Mouse Model of Parkinson's Disease.

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Liu, Zhan; Huang, Yan; Cao, Bei-Bei; Qiu, Yi-Hua; Peng, Yu-Ping

2017-12-01

T helper (Th)17 cells, a subset of CD4 + T lymphocytes, have strong pro-inflammatory property and appear to be essential in the pathogenesis of many inflammatory diseases. However, the involvement of Th17 cells in Parkinson's disease (PD) that is characterized by a progressive degeneration of dopaminergic (DAergic) neurons in the nigrostriatal system is unclear. Here, we aimed to demonstrate that Th17 cells infiltrate into the brain parenchyma and induce neuroinflammation and DAergic neuronal death in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)- or 1-methyl-4-phenylpyridinium (MPP + )-induced PD models. Blood-brain barrier (BBB) disruption in the substantia nigra (SN) was assessed by the signal of FITC-labeled albumin that was injected into blood circulation via the ascending aorta. Live cell imaging system was used to observe a direct contact of Th17 cells with neurons by staining these cells using the two adhesion molecules, leukocyte function-associated antigen (LFA)-1 and intercellular adhesion molecule (ICAM)-1, respectively. Th17 cells invaded into the SN where BBB was disrupted in MPTP-induced PD mice. Th17 cells exacerbated DAergic neuronal loss and pro-inflammatory/neurotrophic factor disorders in MPP + -treated ventral mesencephalic (VM) cell cultures. A direct contact of LFA-1-stained Th17 cells with ICAM-1-stained VM neurons was dynamically captured. Either blocking LFA-1 in Th17 cells or blocking ICAM-1 in VM neurons with neutralizing antibodies abolished Th17-induced DAergic neuronal death. These results establish that Th17 cells infiltrate into the brain parenchyma of PD mice through lesioned BBB and exert neurotoxic property by promoting glial activation and importantly by a direct damage to neurons depending on LFA-1/ICAM-1 interaction.

Autologous transplants of Adipose-Derived Adult Stromal (ADAS) cells afford dopaminergic neuroprotection in a model of Parkinson's disease.

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McCoy, Melissa K; Martinez, Terina N; Ruhn, Kelly A; Wrage, Philip C; Keefer, Edward W; Botterman, Barry R; Tansey, Keith E; Tansey, Malú G

2008-03-01

Adult adipose contains stromal progenitor cells with neurogenic potential. However, the stability of neuronal phenotypes adopted by Adipose-Derived Adult Stromal (ADAS) cells and whether terminal neuronal differentiation is required for their consideration as alternatives in cell replacement strategies to treat neurological disorders is largely unknown. We investigated whether in vitro neural induction of ADAS cells determined their ability to neuroprotect or restore function in a lesioned dopaminergic pathway. In vitro-expanded naïve or differentiated ADAS cells were autologously transplanted into substantia nigra 1 week after an intrastriatal 6-hydroxydopamine injection. Neurochemical and behavioral measures demonstrated neuroprotective effects of both ADAS grafts against 6-hydroxydopamine-induced dopaminergic neuron death, suggesting that pre-transplantation differentiation of the cells does not determine their ability to survive or neuroprotect in vivo. Therefore, we investigated whether equivalent protection by naïve and neurally-induced ADAS grafts resulted from robust in situ differentiation of both graft types into dopaminergic fates. Immunohistological analyses revealed that ADAS cells did not adopt dopaminergic cell fates in situ, consistent with the limited ability of these cells to undergo terminal differentiation into electrically active neurons in vitro. Moreover, re-exposure of neurally-differentiated ADAS cells to serum-containing medium in vitro confirmed ADAS cell phenotypic instability (plasticity). Lastly, given that gene expression analyses of in vitro-expanded ADAS cells revealed that both naïve and differentiated ADAS cells express potent dopaminergic survival factors, ADAS transplants may have exerted neuroprotective effects by production of trophic factors at the lesion site. ADAS cells may be ideal for ex vivo gene transfer therapies in Parkinson's disease treatment.

Preserved dopaminergic homeostasis and dopamine-related behaviour in hemizygous TH-Cre mice.

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Runegaard, Annika H; Jensen, Kathrine L; Fitzpatrick, Ciarán M; Dencker, Ditte; Weikop, Pia; Gether, Ulrik; Rickhag, Mattias

2017-01-01

Cre-driver mouse lines have been extensively used as genetic tools to target and manipulate genetically defined neuronal populations by expression of Cre recombinase under selected gene promoters. This approach has greatly advanced neuroscience but interpretations are hampered by the fact that most Cre-driver lines have not been thoroughly characterized. Thus, a phenotypic characterization is of major importance to reveal potential aberrant phenotypes prior to implementation and usage to selectively inactivate or induce transgene expression. Here, we present a biochemical and behavioural assessment of the dopaminergic system in hemizygous tyrosine hydroxylase (TH)-Cre mice in comparison to wild-type (WT) controls. Our data show that TH-Cre mice display preserved dopaminergic homeostasis with unaltered levels of TH and dopamine as well as unaffected dopamine turnover in striatum. TH-Cre mice also show preserved dopamine transporter expression and function supporting sustained dopaminergic transmission. In addition, TH-Cre mice demonstrate normal responses in basic behavioural paradigms related to dopaminergic signalling including locomotor activity, reward preference and anxiolytic behaviour. Our results suggest that TH-Cre mice represent a valid tool to study the dopamine system, though careful characterization must always be performed to prevent false interpretations following Cre-dependent transgene expression and manipulation of selected neuronal pathways. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Expansion and characterization of ventral mesencephalic precursor cells: effect of mitogens and investigation of FA1 as a potential dopaminergic marker

DEFF Research Database (Denmark)

Jensen, Pia; Bauer, Matthias; Jensen, Charlotte H

2007-01-01

factor 8 (FGF8) for expansion of such dopaminergic precursor cells, and fetal antigen-1 (FA1), a secreted neuronal protein of unknown function, as a non-invasive dopaminergic marker. Tissue from embryonic day (ED) 12 rat ventral mesencephalon was dissociated mechanically and cultured for 4 days...... to controls. After differentiation, biochemical analyses showed significantly more dopamine and FA1 in conditioned medium from both FGF2 and FGF8 expanded cultures than in controls. Correspondingly, numbers of tyrosine hydroxylase (TH)- and FA1-immunoreactive cells had increased 16-fold (P ... for these cells. Furthermore, FA1 was identified as a potential supplementary non-invasive marker of cultured dopaminergic neurons....

Increased dopaminergic signaling impairs aversive olfactory memory retention in Drosophila.

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Zhang, Shixing; Yin, Yan; Lu, Huimin; Guo, Aike

2008-05-23

Dopamine is necessary for the aversive olfactory associative memory formation in Drosophila, but its effect on other stages of memory is not known. Herein, we studied the effect of enhanced dopaminergic signaling on aversive olfactory memory retention in flies. We used l-3,4-dihydroxyphenylalanine (l-DOPA) to elevate dopamine levels: l-DOPA-treated flies exhibited a normal learning performance, but a decrease in 1-h memory. Dopamine transporter (DAT) mutant flies or flies treated with the DAT inhibitor desipramine exhibited poor memory retention. Flies subjected to heat stress after training exhibited a decrease in memory. Memory was restored by blocking dopaminergic neuronal output during heat stress, suggesting that dopamine is involved in heat stress-induced memory impairment in flies. Taken together, our findings suggest that increased dopaminergic signaling impairs aversive olfactory memory retention in flies.

The transfection of BDNF to dopamine neurons potentiates the effect of dopamine D3 receptor agonist recovering the striatal innervation, dendritic spines and motor behavior in an aged rat model of Parkinson's disease.

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Luis F Razgado-Hernandez

Full Text Available The progressive degeneration of the dopamine neurons of the pars compacta of substantia nigra and the consequent loss of the dopamine innervation of the striatum leads to the impairment of motor behavior in Parkinson's disease. Accordingly, an efficient therapy of the disease should protect and regenerate the dopamine neurons of the substantia nigra and the dopamine innervation of the striatum. Nigral neurons express Brain Derived Neurotropic Factor (BDNF and dopamine D3 receptors, both of which protect the dopamine neurons. The chronic activation of dopamine D3 receptors by their agonists, in addition, restores, in part, the dopamine innervation of the striatum. Here we explored whether the over-expression of BDNF by dopamine neurons potentiates the effect of the activation of D3 receptors restoring nigrostriatal innervation. Twelve-month old Wistar rats were unilaterally injected with 6-hydroxydopamine into the striatum. Five months later, rats were treated with the D3 agonist 7-hydroxy-N,N-di-n-propy1-2-aminotetralin (7-OH-DPAT administered i.p. during 4½ months via osmotic pumps and the BDNF gene transfection into nigral cells using the neurotensin-polyplex nanovector (a non-viral transfection that selectively transfect the dopamine neurons via the high-affinity neurotensin receptor expressed by these neurons. Two months after the withdrawal of 7-OH-DPAT when rats were aged (24 months old, immunohistochemistry assays were made. The over-expression of BDNF in rats receiving the D3 agonist normalized gait and motor coordination; in addition, it eliminated the muscle rigidity produced by the loss of dopamine. The recovery of motor behavior was associated with the recovery of the nigral neurons, the dopamine innervation of the striatum and of the number of dendritic spines of the striatal neurons. Thus, the over-expression of BDNF in dopamine neurons associated with the chronic activation of the D3 receptors appears to be a promising strategy

WldS but not Nmnat1 protects dopaminergic neurites from MPP+ neurotoxicity.

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Antenor-Dorsey, Jo Ann V; O'Malley, Karen L

2012-02-08

The WldS mouse mutant ("Wallerian degeneration-slow") delays axonal degeneration in a variety of disorders including in vivo models of Parkinson's disease. The mechanisms underlying WldS -mediated axonal protection are unclear, although many studies have attributed WldS neuroprotection to the NAD+-synthesizing Nmnat1 portion of the fusion protein. Here, we used dissociated dopaminergic cultures to test the hypothesis that catalytically active Nmnat1 protects dopaminergic neurons from toxin-mediated axonal injury. Using mutant mice and lentiviral transduction of dopaminergic neurons, the present findings demonstrate that WldS but not Nmnat1, Nmnat3, or cytoplasmically-targeted Nmnat1 protects dopamine axons from the parkinsonian mimetic N-methyl-4-phenylpyridinium (MPP+). Moreover, NAD+ synthesis is not required since enzymatically-inactive WldS still protects. In addition, NAD+ by itself is axonally protective and together with WldS is additive in the MPP+ model. Our data suggest that NAD+ and WldS act through separate and possibly parallel mechanisms to protect dopamine axons. As MPP+ is thought to impair mitochondrial function, these results suggest that WldS might be involved in preserving mitochondrial health or maintaining cellular metabolism.

WldS but not Nmnat1 protects dopaminergic neurites from MPP+ neurotoxicity

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Antenor-Dorsey Jo Ann V

2012-02-01

Full Text Available Abstract Background The WldS mouse mutant ("Wallerian degeneration-slow" delays axonal degeneration in a variety of disorders including in vivo models of Parkinson's disease. The mechanisms underlying WldS -mediated axonal protection are unclear, although many studies have attributed WldS neuroprotection to the NAD+-synthesizing Nmnat1 portion of the fusion protein. Here, we used dissociated dopaminergic cultures to test the hypothesis that catalytically active Nmnat1 protects dopaminergic neurons from toxin-mediated axonal injury. Results Using mutant mice and lentiviral transduction of dopaminergic neurons, the present findings demonstrate that WldS but not Nmnat1, Nmnat3, or cytoplasmically-targeted Nmnat1 protects dopamine axons from the parkinsonian mimetic N-methyl-4-phenylpyridinium (MPP+. Moreover, NAD+ synthesis is not required since enzymatically-inactive WldS still protects. In addition, NAD+ by itself is axonally protective and together with WldS is additive in the MPP+ model. Conclusions Our data suggest that NAD+ and WldS act through separate and possibly parallel mechanisms to protect dopamine axons. As MPP+ is thought to impair mitochondrial function, these results suggest that WldS might be involved in preserving mitochondrial health or maintaining cellular metabolism.

Protective effects of a polysaccharide from Spirulina platensis on dopaminergic neurons in an MPTP-induced Parkinson′s disease model in C57BL/6J mice

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Fang Zhang

2015-01-01

Full Text Available The present study aimed to determine whether a polysaccharide obtained from Spirulina platensis shows protective effects on dopaminergic neurons. A Parkinson′s disease model was established through the intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP in C57BL/6J mice. Prior to the MPTP injection, some mice were pretreated with intraperitoneal injections of a polysaccharide derived from Spirulina platensis once daily for 10 days. The results showed that the immunoreactive staining and mRNA expression of the dopamine transporter and tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, in the substantia nigra, were significantly increased in mice pretreated with 800 mg/kg of the polysaccharide compared with those in MPTP-treated mice. The activities of superoxide dismutase and glutathione peroxidase in the serum and midbrain were also increased significantly in mice injected with MPTP after pretreatment with the polysaccharide from Spirulina platensis. By contrast, the activity of monoamine oxidase B in serum and midbrain maintained unchanged. These experimental findings indicate that the polysaccharide obtained from Spirulina platensis plays a protective role against the MPTP-induced loss of dopaminergic neurons in C57BL/6J mice, and that the antioxidative properties of this polysaccharide likely underlie its neuroprotective effect.

Intratelencephalic corticostriatal neurons equally excite striatonigral and striatopallidal neurons and their discharge activity is selectively reduced in experimental parkinsonism

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Ballion, B. (B.); Mallet, N. (Nicolas); Bezard, E. (E.); Lanciego, J.L. (José Luis); Gonon, F. (Francois)

2008-01-01

Striatonigral and striatopallidal neurons form distinct populations of striatal projection neurons. Their discharge activity is imbalanced after dopaminergic degeneration in Parkinson's disease. Striatal projection neurons receive massive cortical excitatory inputs from bilateral intratelencephalic (IT) neurons projecting to both the ipsilateral and contralateral striatum and from collateral axons of ipsilateral neurons that send their main axon through the pyramidal tract (PT). Previous anat...

Intermittent, low dose carbon monoxide exposure enhances survival and dopaminergic differentiation of human neural stem cells

DEFF Research Database (Denmark)

Dreyer-Andersen, Nanna; Almeida, Ana Sofia; Jensen, Pia

2018-01-01

cells constitute an alternative source of cells for transplantation in Parkinson's disease, but efficient protocols for controlled dopaminergic differentiation need to be developed. Short-term, low-level carbon monoxide (CO) exposure has been shown to affect signaling in several tissues, resulting...... in both protection and generation of reactive oxygen species. The present study investigated the effect of CO produced by a novel CO-releasing molecule on dopaminergic differentiation of human neural stem cells. Short-term exposure to 25 ppm CO at days 0 and 4 significantly increased the relative content...... of β-tubulin III-immunoreactive immature neurons and tyrosine hydroxylase expressing catecholaminergic neurons, as assessed 6 days after differentiation. Also the number of microtubule associated protein 2-positive mature neurons had increased significantly. Moreover, the content of apoptotic cells...

Dopaminergic neurotoxicant 6-OHDA induces oxidative damage through proteolytic activation of PKCδ in cell culture and animal models of Parkinson's disease

International Nuclear Information System (INIS)

Latchoumycandane, Calivarathan; Anantharam, Vellareddy; Jin, Huajun; Kanthasamy, Anumantha; Kanthasamy, Arthi

2011-01-01

The neurotoxicant 6-hydroxydopamine (6-OHDA) is used to investigate the cellular and molecular mechanisms underlying selective degeneration of dopaminergic neurons in Parkinson's disease (PD). Oxidative stress and caspase activation contribute to the 6-OHDA-induced apoptotic cell death of dopaminergic neurons. In the present study, we sought to systematically characterize the key downstream signaling molecule involved in 6-OHDA-induced dopaminergic degeneration in cell culture and animal models of PD. Treatment of mesencephalic dopaminergic neuronal N27 cells with 6-OHDA (100 μM) for 24 h significantly reduced mitochondrial activity and increased cytosolic cytochrome c, followed by sequential activation of caspase-9 and caspase-3. Co-treatment with the free radical scavenger MnTBAP (10 μM) significantly attenuated 6-OHDA-induced caspase activities. Interestingly, 6-OHDA induced proteolytic cleavage and activation of protein kinase C delta (PKCδ) was completely suppressed by treatment with a caspase-3-specific inhibitor, Z-DEVD-FMK (50 μM). Furthermore, expression of caspase-3 cleavage site-resistant mutant PKCδ D327A and kinase dead PKCδ K376R or siRNA-mediated knockdown of PKCδ protected against 6-OHDA-induced neuronal cell death, suggesting that caspase-3-dependent PKCδ promotes oxidative stress-induced dopaminergic degeneration. Suppression of PKCδ expression by siRNA also effectively protected N27 cells from 6-OHDA-induced apoptotic cell death. PKCδ cleavage was also observed in the substantia nigra of 6-OHDA-injected C57 black mice but not in control animals. Viral-mediated delivery of PKCδ D327A protein protected against 6-OHDA-induced PKCδ activation in mouse substantia nigra. Collectively, these results strongly suggest that proteolytic activation of PKCδ is a key downstream event in dopaminergic degeneration, and these results may have important translational value for development of novel treatment strategies for PD.

The Hyperpolarization-Activated Current Determines Synaptic Excitability, Calcium Activity and Specific Viability of Substantia Nigra Dopaminergic Neurons

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Carmen Carbone

2017-06-01

Full Text Available Differential vulnerability between Substantia Nigra pars compacta (SNpc and Ventral Tegmental Area (VTA dopaminergic (DAergic neurons is a hallmark of Parkinson’s disease (PD. Understanding the molecular bases of this key histopathological aspect would foster the development of much-needed disease-modifying therapies. Non-heterogeneous DAergic degeneration is present in both toxin-based and genetic animal models, suggesting that cellular specificity, rather than causing factors, constitutes the background for differential vulnerability. In this regard, we previously demonstrated that MPP+, a neurotoxin able to cause selective nigrostriatal degeneration in animal rodents and primates, inhibits the Hyperpolarization-activated current (Ih in SNpc DAergic neurons and that pharmacological Ih antagonism causes potentiation of evoked Excitatory post-synaptic potentials (EPSPs. Of note, the magnitude of such potentiation is greater in the SNpc subfield, consistent with higher Ih density. In the present work, we show that Ih block-induced synaptic potentiation leads to the amplification of somatic calcium responses (SCRs in vitro. This effect is specific for the SNpc subfield and largely mediated by L-Type calcium channels, as indicated by sensitivity to the CaV 1 blocker isradipine. Furthermore, Ih is downregulated by low intracellular ATP and determines the efficacy of GABAergic inhibition in SNpc DAergic neurons. Finally, we show that stereotaxic administration of Ih blockers causes SNpc-specific neurodegeneration and hemiparkinsonian motor phenotype in rats. During PD progression, Ih downregulation may result from mitochondrial dysfunction and, in concert with PD-related disinhibition of excitatory inputs, determine a SNpc-specific disease pathway.

Intranasal insulin protects against substantia nigra dopaminergic neuronal loss and alleviates motor deficits induced by 6-OHDA in rats.

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Pang, Y; Lin, S; Wright, C; Shen, J; Carter, K; Bhatt, A; Fan, L-W

2016-03-24

Protection of substantia nigra (SN) dopaminergic (DA) neurons by neurotrophic factors (NTFs) is one of the promising strategies in Parkinson's disease (PD) therapy. A major clinical challenge for NTF-based therapy is that NTFs need to be delivered into the brain via invasive means, which often shows limited delivery efficiency. The nose to brain pathway is a non-invasive brain drug delivery approach developed in recent years. Of particular interest is the finding that intranasal insulin improves cognitive functions in Alzheimer's patients. In vitro, insulin has been shown to protect neurons against various insults. Therefore, the current study was designed to test whether intranasal insulin could afford neuroprotection in the 6-hydroxydopamine (6-OHDA)-based rat PD model. 6-OHDA was injected into the right side of striatum to induce a progressive DA neuronal lesion in the ipsilateral SN pars compact (SNc). Recombinant human insulin was applied intranasally to rats starting from 24h post lesion, once per day, for 2 weeks. A battery of motor behavioral tests was conducted on day 8 and 15. The number of DA neurons in the SNc was estimated by stereological counting. Our results showed that 6-OHDA injection led to significant motor deficits and 53% of DA neuron loss in the ipsilateral side of injection. Treatment with insulin significantly ameliorated 6-OHDA-induced motor impairments, as shown by improved locomotor activity, tapered/ledged beam-walking performance, vibrissa-elicited forelimb-placing, initial steps, as well as methamphetamine-induced rotational behavior. Consistent with behavioral improvements, insulin treatment provided a potent protection of DA neurons in the SNc against 6-OHDA neurotoxicity, as shown by a 74.8% increase in tyrosine hydroxylase (TH)-positive neurons compared to the vehicle group. Intranasal insulin treatment did not affect body weight and blood glucose levels. In conclusion, our study showed that intranasal insulin provided strong

Caspase-1 Deficiency Alleviates Dopaminergic Neuronal Death via Inhibiting Caspase-7/AIF Pathway in MPTP/p Mouse Model of Parkinson's Disease.

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Qiao, Chen; Zhang, Lin-Xia; Sun, Xi-Yang; Ding, Jian-Hua; Lu, Ming; Hu, Gang

2017-08-01

Caspase family has been recognized to be involved in dopaminergic (DA) neuronal death and to exert an unfavorable role in Parkinson's disease (PD) pathology. Our previous study has revealed that caspase-1, as an important component of NLRP3 inflammasome, induces microglia-mediated neuroinflammation in the pathogenesis of PD. However, the role of caspase-1 in DA neuronal degeneration in the onset of PD remains unclear. Here, we showed that caspase-1 knockout ameliorated DA neuronal loss and dyskinesia in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine/probenecid (MPTP/p)-induced PD model mice. We further found that caspase-1 knockout decreased MPTP/p-induced caspase-7 cleavage, subsequently inhibited nuclear translocation of poly (ADP-ribose) polymerase 1 (PARP1), and reduced the release of apoptosis-inducing factor (AIF). Consistently, we demonstrated that caspase-1 inhibitor suppressed caspase-7/PARP1/AIF-mediated apoptosis pathway by 1-methyl-4-phenylpyridinium ion (MPP + ) stimulation in SH-SY5Y cells. Caspase-7 overexpression reduced the protective effects of caspase-1 inhibitor on SH-SY5Y cell apoptosis. Collectively, our results have revealed that caspase-1 regulates DA neuronal death in the pathogenesis of PD in mice via caspase-7/PARP1/AIF pathway. These findings will shed new insight into the potential of caspase-1 as a target for PD therapy.

Squamosamide derivative FLZ protects dopaminergic neurons against inflammation-mediated neurodegeneration through the inhibition of NADPH oxidase activity

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Wilson Belinda

2008-05-01

Full Text Available Abstract Background Inflammation plays an important role in the pathogenesis of Parkinson's disease (PD through over-activation of microglia, which consequently causes the excessive production of proinflammatory and neurotoxic factors, and impacts surrounding neurons and eventually induces neurodegeneration. Hence, prevention of microglial over-activation has been shown to be a prime target for the development of therapeutic agents for inflammation-mediated neurodegenerative diseases. Methods For in vitro studies, mesencephalic neuron-glia cultures and reconstituted cultures were used to investigate the molecular mechanism by which FLZ, a squamosamide derivative, mediates anti-inflammatory and neuroprotective effects in both lipopolysaccharide-(LPS- and 1-methyl-4-phenylpyridinium-(MPP+-mediated models of PD. For in vivo studies, a 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine-(MPTP- induced PD mouse model was used. Results FLZ showed potent efficacy in protecting dopaminergic (DA neurons against LPS-induced neurotoxicity, as shown in rat and mouse primary mesencephalic neuronal-glial cultures by DA uptake and tyrosine hydroxylase (TH immunohistochemical results. The neuroprotective effect of FLZ was attributed to a reduction in LPS-induced microglial production of proinflammatory factors such as superoxide, tumor necrosis factor-α (TNF-α, nitric oxide (NO and prostaglandin E2 (PGE2. Mechanistic studies revealed that the anti-inflammatory properties of FLZ were mediated through inhibition of NADPH oxidase (PHOX, the key microglial superoxide-producing enzyme. A critical role for PHOX in FLZ-elicited neuroprotection was further supported by the findings that 1 FLZ's protective effect was reduced in cultures from PHOX-/- mice, and 2 FLZ inhibited LPS-induced translocation of the cytosolic subunit of p47PHOX to the membrane and thus inhibited the activation of PHOX. The neuroprotective effect of FLZ demonstrated in primary neuronal

Synthetic bovine proline-rich-polypeptides generate hydroxyl radicals and fail to protect dopaminergic neurons against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced dopaminergic neurotoxicity in mice.

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Knaryan, Varduhi H; Samantaray, Supriti; Varghese, Merina; Srinivasan, Ambika; Galoyan, Armen A; Mohanakumar, Kochupurackal P

2006-08-01

Proline-rich-polypeptides (PRPs) isolated from bovine hypothalamus have been shown to render protection against neuronal injury of the brain and spinal cord. We examined two PRPs containing 15 and 10 amino acid residues (PRP-1 and PRP-4 synthetic polypeptide) for their effect, if any, on dopaminergic neuronal damage caused by the parkinsonian neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Effects of these PRPs on hydroxyl radical ((*)OH) generation in a Fenton-like reaction as well as from isolated mitochondria were monitored, employing a sensitive salicylate hydroxylation procedure. Balb/c mice treated (i.p., twice, 16 h apart) with MPTP (30 mg/kg) or PRP-1 (1.6 mg/kg), but not PRP-4 (1.6 mg/kg) showed significant loss of striatal dopamine and norepinephrine as assayed by an HPLC-electrochemical procedure. Pretreatment with the PRPs, 30 min prior to the neurotoxin administration failed to attenuate MPTP-induced striatal dopamine or norepinephrine depletion, but significantly attenuated the MPTP-induced decrease in dopamine turnover. A significant increase in the generation of (*)OH by the PRPs in a Fenton-like reaction or from isolated mitochondria suggests their pro-oxidant action, and explains their failure to protect against MPTP-induced parkinsonism in mice.

Curcumin protects dopaminergic neurons against inflammation-mediated damage and improves motor dysfunction induced by single intranigral lipopolysaccharide injection.

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Sharma, Neha; Sharma, Sheetal; Nehru, Bimla

2017-06-01

Various studies have indicated a lower incidence and prevalence of neurological conditions in people consuming curcumin. The ability of curcumin to target multiple cascades, simultaneously, could be held responsible for its neuroprotective effects. The present study was designed to investigate the potential of curcumin in minimizing microglia-mediated damage in lipopolysaccharide (LPS) induced model of PD. Altered microglial functions and increased inflammatory profile of the CNS have severe behavioral consequences. In the current investigation, a single injection of LPS (5 ug/5 µl PBS) was injected into the substantia nigra (SN) of rats, and curcumin [40 mg/kg b.wt (i.p.)] was administered daily for a period of 21 days. LPS triggered an inflammatory response characterized by glial activation [Iba-1 and glial fibrillary acidic protein (GFAP)] and pro-inflammatory cytokine production (TNF-α and IL-1β) leading to extensive dopaminergic loss and behavioral abnormality in rats. The behavioral observations, biochemical markers, quantification of dopamine and its metabolites (DOPAC and HVA) using HPLC followed by IHC of tyrosine hydroxylase (TH) were evaluated after 21 days of LPS injection. Curcumin supplementation prevented dopaminergic degeneration in LPS-treated animals by normalizing the altered levels of biomarkers. Also, a significant improvement in TH levels as well as behavioral parameters (actophotometer, rotarod, beam walking and grid walking tests) were seen in LPS injected rats. Curcumin shielded the dopaminergic neurons against LPS-induced inflammatory response, which was associated with suppression of glial activation (microglia and astrocytes) and transcription factor NF-κB as depicted from RT-PCR and EMSA assay. Curcumin also suppressed microglial NADPH oxidase activation as observed from NADPH oxidase activity. The results suggested that one of the important mechanisms by which curcumin mediates its protective effects in the LPS-induced PD

Differential Regulation of Action Potential Shape and Burst-Frequency Firing by BK and Kv2 Channels in Substantia Nigra Dopaminergic Neurons.

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Kimm, Tilia; Khaliq, Zayd M; Bean, Bruce P

2015-12-16

Little is known about the voltage-dependent potassium currents underlying spike repolarization in midbrain dopaminergic neurons. Studying mouse substantia nigra pars compacta dopaminergic neurons both in brain slice and after acute dissociation, we found that BK calcium-activated potassium channels and Kv2 channels both make major contributions to the depolarization-activated potassium current. Inhibiting Kv2 or BK channels had very different effects on spike shape and evoked firing. Inhibiting Kv2 channels increased spike width and decreased the afterhyperpolarization, as expected for loss of an action potential-activated potassium conductance. BK inhibition also increased spike width but paradoxically increased the afterhyperpolarization. Kv2 channel inhibition steeply increased the slope of the frequency-current (f-I) relationship, whereas BK channel inhibition had little effect on the f-I slope or decreased it, sometimes resulting in slowed firing. Action potential clamp experiments showed that both BK and Kv2 current flow during spike repolarization but with very different kinetics, with Kv2 current activating later and deactivating more slowly. Further experiments revealed that inhibiting either BK or Kv2 alone leads to recruitment of additional current through the other channel type during the action potential as a consequence of changes in spike shape. Enhancement of slowly deactivating Kv2 current can account for the increased afterhyperpolarization produced by BK inhibition and likely underlies the very different effects on the f-I relationship. The cross-regulation of BK and Kv2 activation illustrates that the functional role of a channel cannot be defined in isolation but depends critically on the context of the other conductances in the cell. This work shows that BK calcium-activated potassium channels and Kv2 voltage-activated potassium channels both regulate action potentials in dopamine neurons of the substantia nigra pars compacta. Although both

Metformin, besides exhibiting strong in vivo anti-inflammatory properties, increases mptp-induced damage to the nigrostriatal dopaminergic system

International Nuclear Information System (INIS)

Ismaiel, Afrah A.K.; Espinosa-Oliva, Ana M.; Santiago, Martiniano; García-Quintanilla, Albert; Oliva-Martín, María J.; Herrera, Antonio J.; Venero, José L.; Pablos, Rocío M. de

2016-01-01

Metformin is a widely used oral antidiabetic drug with known anti-inflammatory properties due to its action on AMPK protein. This drug has shown a protective effect on various tissues, including cortical neurons. The aim of this study was to determine the effect of metformin on the dopaminergic neurons of the substantia nigra of mice using the animal model of Parkinson's disease based on the injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, an inhibitor of the mitochondrial complex I. In vivo and in vitro experiments were used to study the activation of microglia and the damage of the dopaminergic neurons. Our results show that metformin reduced microglial activation measured both at cellular and molecular levels. Rather than protecting, metformin exacerbated dopaminergic damage in response to MPTP. Our data suggest that, contrary to other brain structures, metformin treatment could be deleterious for the dopaminergic system. Hence, metformin treatment may be considered as a risk factor for the development of Parkinson's disease. - Highlights: • Metformin treatment decreases microglial activation in the MPTP model of Parkinson's disease. • Metformin treatment increases the neurodegeneration in the MPTP model of Parkinson's disease, both in vivo and vitro. • Metformin treatment could be a risk factor for the development of Parkinson's disease.

Metformin, besides exhibiting strong in vivo anti-inflammatory properties, increases mptp-induced damage to the nigrostriatal dopaminergic system

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Ismaiel, Afrah A.K.; Espinosa-Oliva, Ana M.; Santiago, Martiniano; García-Quintanilla, Albert; Oliva-Martín, María J.; Herrera, Antonio J.; Venero, José L.; Pablos, Rocío M. de, E-mail: depablos@us.es

2016-05-01

Metformin is a widely used oral antidiabetic drug with known anti-inflammatory properties due to its action on AMPK protein. This drug has shown a protective effect on various tissues, including cortical neurons. The aim of this study was to determine the effect of metformin on the dopaminergic neurons of the substantia nigra of mice using the animal model of Parkinson's disease based on the injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, an inhibitor of the mitochondrial complex I. In vivo and in vitro experiments were used to study the activation of microglia and the damage of the dopaminergic neurons. Our results show that metformin reduced microglial activation measured both at cellular and molecular levels. Rather than protecting, metformin exacerbated dopaminergic damage in response to MPTP. Our data suggest that, contrary to other brain structures, metformin treatment could be deleterious for the dopaminergic system. Hence, metformin treatment may be considered as a risk factor for the development of Parkinson's disease. - Highlights: • Metformin treatment decreases microglial activation in the MPTP model of Parkinson's disease. • Metformin treatment increases the neurodegeneration in the MPTP model of Parkinson's disease, both in vivo and vitro. • Metformin treatment could be a risk factor for the development of Parkinson's disease.

nNOS inhibitors attenuate methamphetamine-induced dopaminergic neurotoxicity but not hyperthermia in mice.

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Itzhak, Y; Martin, J L; Ail, S F

2000-09-11

Methamphetamine (METH)-induced dopaminergic neurotoxicity is associated with hyperthermia. We investigated the effect of several neuronal nitric oxide synthase (nNOS) inhibitors on METH-induced hyperthermia and striatal dopaminergic neurotoxicity. Administration of METH (5 mg/kg; q. 3 h x 3) to Swiss Webster mice produced marked hyperthermia and 50-60% depletion of striatal dopaminergic markers 72 h after METH administration. Pretreatment with the nNOS inhibitors S-methylthiocitrulline (SMTC; 10 mg/kg) or 3-bromo-7-nitroindazole (3-Br-7-NI; 20 mg/kg) before each METH injection did not affect the persistent hyperthermia produced by METH, but afforded protection against the depletion of dopaminergic markers. A low dose (25 mg/kg) of the nNOS inhibitor 7-nitroindazole (7-NI) did not affect METH-induced hyperthermia, but a high dose (50 mg/kg) produced significant hypothermia. These findings indicate that low dose of selective nNOS inhibitors protect against METH-induced neurotoxicity with no effect on body temperature and support the hypothesis that nitric oxide (NO) and peroxynitrite have a major role in METH-induced dopaminergic neurotoxicity.

Dopamine synapse is a neuroligin-2–mediated contact between dopaminergic presynaptic and GABAergic postsynaptic structures

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Uchigashima, Motokazu; Ohtsuka, Toshihisa; Kobayashi, Kazuto; Watanabe, Masahiko

2016-01-01

Midbrain dopamine neurons project densely to the striatum and form so-called dopamine synapses on medium spiny neurons (MSNs), principal neurons in the striatum. Because dopamine receptors are widely expressed away from dopamine synapses, it remains unclear how dopamine synapses are involved in dopaminergic transmission. Here we demonstrate that dopamine synapses are contacts formed between dopaminergic presynaptic and GABAergic postsynaptic structures. The presynaptic structure expressed tyrosine hydroxylase, vesicular monoamine transporter-2, and plasmalemmal dopamine transporter, which are essential for dopamine synthesis, vesicular filling, and recycling, but was below the detection threshold for molecules involving GABA synthesis and vesicular filling or for GABA itself. In contrast, the postsynaptic structure of dopamine synapses expressed GABAergic molecules, including postsynaptic adhesion molecule neuroligin-2, postsynaptic scaffolding molecule gephyrin, and GABAA receptor α1, without any specific clustering of dopamine receptors. Of these, neuroligin-2 promoted presynaptic differentiation in axons of midbrain dopamine neurons and striatal GABAergic neurons in culture. After neuroligin-2 knockdown in the striatum, a significant decrease of dopamine synapses coupled with a reciprocal increase of GABAergic synapses was observed on MSN dendrites. This finding suggests that neuroligin-2 controls striatal synapse formation by giving competitive advantage to heterologous dopamine synapses over conventional GABAergic synapses. Considering that MSN dendrites are preferential targets of dopamine synapses and express high levels of dopamine receptors, dopamine synapse formation may serve to increase the specificity and potency of dopaminergic modulation of striatal outputs by anchoring dopamine release sites to dopamine-sensing targets. PMID:27035941

A Wnt1 regulated Frizzled-1/β-Catenin signaling pathway as a candidate regulatory circuit controlling mesencephalic dopaminergic neuron-astrocyte crosstalk: Therapeutical relevance for neuron survival and neuroprotection

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Pluchino Stefano

2011-07-01

Full Text Available Abstract Background Dopamine-synthesizing (dopaminergic, DA neurons in the ventral midbrain (VM constitute a pivotal neuronal population controlling motor behaviors, cognitive and affective brain functions, which generation critically relies on the activation of Wingless-type MMTV integration site (Wnt/β-catenin pathway in their progenitors. In Parkinson's disease, DA cell bodies within the substantia nigra pars compacta (SNpc progressively degenerate, with causes and mechanisms poorly understood. Emerging evidence suggests that Wnt signaling via Frizzled (Fzd receptors may play a role in different degenerative states, but little is known about Wnt signaling in the adult midbrain. Using in vitro and in vivo model systems of DA degeneration, along with functional studies in both intact and SN lesioned mice, we herein highlight an intrinsic Wnt1/Fzd-1/β-catenin tone critically contributing to the survival and protection of adult midbrain DA neurons. Results In vitro experiments identifie Fzd-1 receptor expression at a mRNA and protein levels in dopamine transporter (DAT expressing neurons, and demonstrate the ability of exogenous Wnt1 to exert robust neuroprotective effects against Caspase-3 activation, the loss of tyrosine hydroxylase-positive (TH+ neurons and [3H] dopamine uptake induced by different DA-specific insults, including serum and growth factor deprivation, 6-hydroxydopamine and MPTP/MPP+. Co-culture of DA neurons with midbrain astrocytes phenocopies Wnt1 neuroprotective effects, whereas RNA interference-mediated knockdown of Wnt1 in midbrain astrocytes markedly reduces astrocyte-induced TH+ neuroprotection. Likewise, silencing β-catenin mRNA or knocking down Fzd-1 receptor expression in mesencephalic neurons counteract astrocyte-induced TH+ neuroprotection. In vivo experiments document Fzd-1 co-localization with TH+ neurons within the intact SNpc and blockade of Fzd/β-catenin signaling by unilateral infusion of a Fzd

Unveiling the Dual Role of the Dopaminergic System on Locomotion and the Innate Value for an Aversive Olfactory Stimulus in Drosophila.

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Fuenzalida-Uribe, Nicolás; Campusano, Jorge M

2018-02-10

The communication between sensory systems and the specific brain centers that process this information is crucial to develop adequate behavioral responses. Modulatory systems, including dopaminergic circuits, regulate this communication to finely tune the behavioral response associated to any given stimulus. For instance, the Mushroom Body (MB), an insect brain integration center that receives and processes several sensory stimuli and organizes the execution of motor programs, communicates with MB output neurons (MBONs) to develop behavioral responses associated to olfactory stimuli. This communication is modulated by dopaminergic neural systems. Here we show that silencing dopaminergic neurons increases the aversive response observed in adult flies exposed to Benzaldehyde (Bz) or octanol. We studied the contribution of two dopaminergic clusters that innervate different zones of MB, Protocerebral anterior medial (PAM) and Protocerebral posterior lateral 1 (PPL1), on the innate value to the aversive stimulus and the associated locomotor behavior. In order to do this, we manipulated the synaptic transmission of these neural clusters through the expression of Tetanus toxin, Kir2.1 and Transient receptor potential cation channel A1 (TrpA1) channels. Our results show that neurons in PPL1 and PAM differentially modulate the innate value to Bz in adult flies. On the other hand, blocking neurotransmission or genetic silencing of PAM neurons results in decreased locomotor behavior in flies, an effect not observed when silencing PPL1. Our results suggest that as in mammals, specific dopaminergic pathways differentially modulate locomotor behavior and the innate value for an odorant, a limbic-like response in Drosophila. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Synergistic Effects of Aerobic Exercise after Bone Marrow Stem Cell Transplantation on Recovery of Dopaminergic Neurons and Angiogenesis Markers of Parkinsonian Rats

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Seyed Abdollah Hashemvarzi

2016-03-01

Full Text Available Abstract: Parkinson is a progressive neurodegenerative disease in central nervous system. Non-pharmacologic treatment methods such as stem cell transplantation and exercise have been considered as a treatment. The purpose of this study was to evaluate the synergistic effects of aerobic exercise after bone marrow stem cells transplantation on recovery of dopaminergic neurons and promotion of angiogenesis markers in the striatum of parkinsonian rats. 42 rats were divided into six groups: Normal (N, Sham (S, Parkinson’s (P, Stem cells transplanted Parkinson’s (SP, Exercised Parkinson’s (EP and Stem cells transplanted+Exercised Parkinson’s (SEP. To create a model of Parkinson's, the striatum was destroyed by injection of 6-hydroxy-dopamine into the striatum through stereotaxic apparatus. Stem cells were derived from the bone marrow of femur and tibia of male rats aged 6-8 weeks. After cultivation, approximately 5×105 cells were injected into the striatum of rats through the channel. Aerobic exercise was included 8 weeks of running on treadmill with a speed of 15 meters per minute. At the end of the study, all subjects were decapitated and striatum tissues were separately isolated for measurement of vascular endothelial growth factor (VEGF, dopamine (DA and tyrosine hydroxylase (TH levels. VEGF, DA and TH levels in the striatum of parkinsonian rats significantly increased in treatment groups (SP, EP and SEP, especially in SEP group compared to P group after treatment (P<0.05. The BMSCs transplantation in combination with exercise would have synergistic effects leading to functional recovery, dopaminergic neurons recovery and promotion of angiogenesis marker in the striatum of parkinsonian rats. Keywords: Stem cells, Aerobic exercise, Neurotrophic factors, Parkinson

CRISPR/Cas9 and piggyBac-mediated footprint-free LRRK2-G2019S knock-in reveals neuronal complexity phenotypes and α-Synuclein modulation in dopaminergic neurons.

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Qing, Xiaobing; Walter, Jonas; Jarazo, Javier; Arias-Fuenzalida, Jonathan; Hillje, Anna-Lena; Schwamborn, Jens C

2017-10-01

The p.G2019S mutation of the leucine-rich repeat kinase 2 (LRRK2) has been identified as the most prevalent genetic cause of familial and sporadic Parkinson's disease (PD). The Cre-LoxP recombination system has been used to correct the LRRK2-G2019S mutation in patient derived human induced pluripotent stem cells (hiPSCs) in order to generate isogenic controls. However, the remaining LoxP site can influence gene expression. In this study, we report the generation of a footprint-free LRRK2-G2019S isogenic hiPS cell line edited with the CRISPR/Cas9 and piggyBac technologies. We observed that the percentage of Tyrosine Hydroxylase (TH) positive neurons with a total neurite length of >2000μm was significantly reduced in LRRK2-G2019S dopaminergic (DA) neurons. The average branch number in LRRK2-G2019S DA neurons was also decreased. In addition, we have shown that in vitro TH positive neurons with a total neurite length of >2000μm were positive for Serine 129 phosphorylated (S129P) alpha-Synuclein (αS) and we hypothesize that S129P-αS plays a role in the maintenance or formation of long neurites. In summary, our footprint-free LRRK2-G2019S isogenic cell lines allow standardized, genetic background independent, in vitro PD modeling and provide new insights into the role of LRRK2-G2019S and S129P-αS in the pathogenesis of PD. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Altered dopaminergic regulation of the dorsal striatum is able to induce tic-like movements in juvenile rats

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Rizzo, Francesca; Boeckers, Tobias; Schulze, Ulrike

2018-01-01

Motor tics are sudden, repetitive, involuntary movements representing the hallmark behaviors of the neurodevelopmental disease Tourette’s syndrome (TS). The primary cause of TS remains unclear. The initial observation that dopaminergic antagonists alleviate tics led to the development of a dopaminergic theory of TS etiology which is supported by post mortem and in vivo studies indicating that non-physiological activation of the striatum could generate tics. The striatum controls movement execution through the balanced activity of dopamine receptor D1 and D2-expressing medium spiny neurons of the direct and indirect pathway, respectively. Different neurotransmitters can activate or repress striatal activity and among them, dopamine plays a major role. In this study we introduced a chronic dopaminergic alteration in juvenile rats, in order to modify the delicate balance between direct and indirect pathway. This manipulation was done in the dorsal striatum, that had been associated with tic-like movements generation in animal models. The results were movements resembling tics, which were categorized and scored according to a newly developed rating scale and were reduced by clonidine and riluzole treatment. Finally, post mortem analyses revealed altered RNA expression of dopaminergic receptors D1 and D2, suggesting an imbalanced dopaminergic regulation of medium spiny neuron activity as being causally related to the observed phenotype. PMID:29698507

GSTpi expression in MPTP-induced dopaminergic neurodegeneration of C57BL/6 mouse midbrain and striatum.

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Castro-Caldas, Margarida; Neves Carvalho, Andreia; Peixeiro, Isabel; Rodrigues, Elsa; Lechner, Maria Celeste; Gama, Maria João

2009-06-01

MPTP-induced dopaminergic neurotoxicity involves major biochemical processes such as oxidative stress and impaired energy metabolism, leading to a significant reduction in the number of nigrostriatal dopaminergic neurons. Glutathione S-transferase pi (GSTpi) is a phase II detoxifying enzyme that provides protection of cells from injury by toxic chemicals and products of oxidative stress. In humans, polymorphisms of GSTP1 affect substrate selectivity and stability increasing the susceptibility to parkinsonism-inducing effects of environmental toxins. Given the ability of MPTP to increase the levels of reactive oxygen species and the link between altered redox potential and the expression and activity of GSTpi, we investigated the effect of MPTP on GSTpi cellular concentration in an in vivo model of Parkinson's disease. The present study demonstrates that GSTpi is actively expressed in both substantia nigra pars compacta and striatum of C57BL/6 mice brain, mostly in oligodendrocytes and astrocytes. After systemic administration of MPTP, GSTpi expression is significantly increased in glial cells in the vicinity of dopaminergic neurons cell bodies and fibers. The results suggest that GSTpi expression may be part of the mechanism underlying the ability of glial cells to elicit protection against the mechanisms involved in MPTP-induced neuronal death.

Ascending Midbrain Dopaminergic Axons Require Descending GAD65 Axon Fascicles for Normal Pathfinding

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Claudia Marcela Garcia-Peña

2014-06-01

Full Text Available The Nigrostriatal pathway (NSP is formed by dopaminergic axons that project from the ventral midbrain to the dorsolateral striatum as part of the medial forebrain bundle. Previous studies have implicated chemotropic proteins in the formation of the NSP during development but little is known of the role of substrate-anchored signals in this process. We observed in mouse and rat embryos that midbrain dopaminergic axons ascend in close apposition to descending GAD65-positive axon bundles throughout their trajectory to the striatum. To test whether such interaction is important for dopaminergic axon pathfinding, we analyzed transgenic mouse embryos in which the GAD65 axon bundle was reduced by the conditional expression of the diphtheria toxin. In these embryos we observed dopaminergic misprojection into the hypothalamic region and abnormal projection in the striatum. In addition, analysis of Robo1/2 and Slit1/2 knockout embryos revealed that the previously described dopaminergic misprojection in these embryos is accompanied by severe alterations in the GAD65 axon scaffold. Additional studies with cultured dopaminergic neurons and whole embryos suggest that NCAM and Robo proteins are involved in the interaction of GAD65 and dopaminergic axons. These results indicate that the fasciculation between descending GAD65 axon bundles and ascending dopaminergic axons is required for the stereotypical NSP formation during brain development and that known guidance cues may determine this projection indirectly by instructing the pathfinding of the axons that are part of the GAD65 axon scaffold.

Zic-Proteins Are Repressors of Dopaminergic Forebrain Fate in Mice and C. elegans.

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Tiveron, Marie-Catherine; Beclin, Christophe; Murgan, Sabrina; Wild, Stefan; Angelova, Alexandra; Marc, Julie; Coré, Nathalie; de Chevigny, Antoine; Herrera, Eloisa; Bosio, Andreas; Bertrand, Vincent; Cremer, Harold

2017-11-01

In the postnatal forebrain regionalized neural stem cells along the ventricular walls produce olfactory bulb (OB) interneurons with varying neurotransmitter phenotypes and positions. To understand the molecular basis of this region-specific variability we analyzed gene expression in the postnatal dorsal and lateral lineages in mice of both sexes from stem cells to neurons. We show that both lineages maintain transcription factor signatures of their embryonic site of origin, the pallium and subpallium. However, additional factors, including Zic1 and Zic2, are postnatally expressed in the dorsal stem cell compartment and maintained in the lineage that generates calretinin-positive GABAergic neurons for the OB. Functionally, we show that Zic1 and Zic2 induce the generation of calretinin-positive neurons while suppressing dopaminergic fate in the postnatal dorsal lineage. We investigated the evolutionary conservation of the dopaminergic repressor function of Zic proteins and show that it is already present in C. elegans SIGNIFICANCE STATEMENT The vertebrate brain generates thousands of different neuron types. In this work we investigate the molecular mechanisms underlying this variability. Using a genomics approach we identify the transcription factor signatures of defined neural stem cells and neuron populations. Based thereon we show that two related transcription factors, Zic1 and Zic2, are essential to control the balance between two defined neuron types in the postnatal brain. We show that this mechanism is conserved in evolutionary very distant species. Copyright © 2017 the authors 0270-6474/17/3710611-13$15.00/0.

Dietary plant lectins appear to be transported from the gut to gain access to and alter dopaminergic neurons of Caenorhabditis elegans, a potential etiology of Parkinson’s disease

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Jolene eZheng

2016-03-01

Full Text Available Lectins from dietary plants have been shown to enhance drug absorption in the gastrointestinal tract of rats, be transported trans-synaptically as shown by tracing of axonal and dendritic paths, and enhance gene delivery. Other carbohydrate-binding protein toxins are known to traverse the gut intact in dogs. Post-feeding rhodamine- or TRITC-tagged dietary lectins, the lectins were tracked from gut to dopaminergic neurons (DAergic-N in transgenic Caenorhabditis elegans (C. elegans (egIs1[Pdat-1::GFP] where the mutant has the Green Fluorescent Protein (GFP gene fused to a dopamine transport protein gene labeling dopaminergic neurons, The lectins were supplemented along with the food organism Escherichia coli (OP50. Among nine tested rhodamine/TRITC-tagged lectins, four, including Phaseolus vulgaris erythroagglutinin (PHA-E, Bandeiraea simplicifolia (BS-I, Dolichos biflorus agglutinin (DBA, and Arachis hypogaea (PNA, appeared to be transported from gut to the GFP-DAergic-N. Griffonia Simplicifolia (GSL-I and PHA-E, reduced the number of GFP-DAergic-N suggesting a toxic activity. PHA-E, BS-I, Pisum Sativum (PSA, and Triticum vulgaris agglutinin (Succinylated reduced fluorescent intensity of GFP-DAergic-N. PHA-E, PSA, Concanavalin A, and Triticum vulgaris agglutinin decreased the size of GFP-DAergic-N, while BS-I increased neuron size. These observations suggest that dietary plant lectins are transported to and affect DAergic-N in C. elegans, which support Braak and Hawkes’ hypothesis, suggesting one alternate potential dietary etiology of Parkinson’s disease (PD. A recent Danish study showed that vagotomy resulted in 40% lower incidence of PD over 20 years. Differences in inherited sugar structures of gut and neuronal cell surfaces may make some individuals more susceptible in this conceptual disease etiology model.

Lipopolysaccharide-induced dopaminergic cell death in rat midbrain slice cultures: role of inducible nitric oxide synthase and protection by indomethacin.

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Shibata, Haruki; Katsuki, Hiroshi; Nishiwaki, Mayumi; Kume, Toshiaki; Kaneko, Shuji; Akaike, Akinori

2003-09-01

Glial cell activation associated with inflammatory reaction may contribute to pathogenic processes of neurodegenerative disorders, through production of several cytotoxic molecules. We investigated the consequences of glial activation by interferon-gamma (IFN-gamma)/lipopolysaccharide (LPS) in rat midbrain slice cultures. Application of IFN-gamma followed by LPS caused dopaminergic cell death and accompanying increases in nitrite production and lactate dehydrogenase release. Aminoguanidine, an inhibitor of inducible nitric oxide synthase (iNOS), or SB203580, an inhibitor of p38 mitogen-activated protein kinase, prevented dopaminergic cell loss as well as nitrite production. SB203580 also suppressed expression of iNOS and cyclooxygenase-2 (COX-2) induced by IFN-gamma/LPS. A COX inhibitor indomethacin protected dopaminergic neurons from IFN-gamma/LPS-induced injury, whereas selective COX-2 inhibitors such as NS-398 and nimesulide did not. Notably, indomethacin was able to attenuate neurotoxicity of a nitric oxide (NO) donor. Neutralizing antibodies against tumour necrosis factor-alpha and interleukin-1beta did not inhibit dopaminergic cell death caused by IFN-gamma/LPS, although combined application of these antibodies blocked lactate dehydrogenase release and decrease in the number of non-dopaminergic neurons. These results indicate that iNOS-derived NO plays a crucial role in IFN-gamma/LPS-induced dopaminergic cell death, and that indomethacin exerts protective effect by mechanisms probably related to NO neurotoxicity rather than through COX inhibition.

Hypoxic Culture Promotes Dopaminergic-Neuronal Differentiation of Nasal Olfactory Mucosa Mesenchymal Stem Cells via Upregulation of Hypoxia-Inducible Factor-1α.

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Zhuo, Yi; Wang, Lei; Ge, Lite; Li, Xuan; Duan, Da; Teng, Xiaohua; Jiang, Miao; Liu, Kai; Yuan, Ting; Wu, Pei; Wang, Hao; Deng, Yujia; Xie, Huali; Chen, Ping; Xia, Ying; Lu, Ming

2017-08-01

Olfactory mucosa mesenchymal stem cells (OM-MSCs) display significant clonogenic activity and may be easily propagated for Parkinson's disease therapies. Methods of inducing OM-MSCs to differentiate into dopaminergic (DAergic) neurons using olfactory ensheathing cells (OECs) are thus an attractive topic of research. We designed a hypoxic induction protocol to generate DAergic neurons from OM-MSCs using a physiological oxygen (O 2 ) level of 3% and OEC-conditioned medium (OCM; HI group). The normal induction (NI) group was cultured in O 2 at ambient air level (21%). The role of hypoxia-inducible factor-1α (HIF-1α) in the differentiation of OM-MSCs under hypoxia was investigated by treating cells with an HIF-1α inhibitor before induction (HIR group). The proportions of β-tubulin- and tyrosine hydroxylase (TH)-positive cells were significantly increased in the HI group compared with the NI and HIR groups, as shown by immunocytochemistry and Western blotting. Furthermore, the level of dopamine was significantly increased in the HI group. A slow outward potassium current was recorded in differentiated cells after 21 d of induction using whole-cell voltage-clamp tests. A hypoxic environment thus promotes OM-MSCs to differentiate into DAergic neurons by increasing the expression of HIF-1α and by activating downstream target gene TH. This study indicated that OCM under hypoxic conditions could significantly upregulate key transcriptional factors involved in the development of DAergic neurons from OM-MSCs, mediated by HIF-1α. Hypoxia promotes DAergic neuronal differentiation of OM-MSCs, and HIF-1α may play an important role in hypoxia-inducible pathways during DAergic lineage specification and differentiation in vitro.

Rat brain sagittal organotypic slice cultures as an ex vivo dopamine cell loss system.

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McCaughey-Chapman, Amy; Connor, Bronwen

2017-02-01

Organotypic brain slice cultures are a useful tool to study neurological function as they provide a more complex, 3-dimensional system than standard 2-dimensional in vitro cell cultures. Building on a previously developed mouse brain slice culture protocol, we have developed a rat sagittal brain slice culture system as an ex vivo model of dopamine cell loss. We show that rat brain organotypic slice cultures remain viable for up to 6 weeks in culture. Using Fluoro-Gold axonal tracing, we demonstrate that the slice 3-dimensional cytoarchitecture is maintained over a 4 week culturing period, with particular focus on the nigrostriatal pathway. Treatment of the cultures with 6-hydroxydopamine and desipramine induces a progressive loss of Fluoro-Gold-positive nigral cells with a sustained loss of tyrosine hydroxylase-positive nigral cells. This recapitulates the pattern of dopaminergic degeneration observed in the rat partial 6-hydroxydopamine lesion model and, most importantly, the progressive pathology of Parkinson's disease. Our slice culture platform provides an advance over other systems, as we demonstrate for the first time 3-dimensional cytoarchitecture maintenance of rat nigrostriatal sagittal slices for up to 6 weeks. Our ex vivo organotypic slice culture system provides a long term cellular platform to model Parkinson's disease, allowing for the elucidation of mechanisms involved in dopaminergic neuron degeneration and the capability to study cellular integration and plasticity ex vivo. Copyright © 2017 Elsevier B.V. All rights reserved.

6-OHDA induced calcium influx through N-type calcium channel alters membrane properties via PKA pathway in substantia nigra pars compacta dopaminergic neurons.

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Qu, Liang; Wang, Yuan; Zhang, Hai-Tao; Li, Nan; Wang, Qiang; Yang, Qian; Gao, Guo-Dong; Wang, Xue-Lian

2014-07-11

Voltage gated calcium channels (VGCC) are sensitive to oxidative stress, and their activation or inactivation can impact cell death. Although these channels have been extensively studied in expression systems, their role in the brain, particularly in the substantia nigra pars compacta (SNc), remain controversial. In this study, we assessed 6-hydroxydopamine (6-OHDA) induced transformation of firing pattern and functional changes of calcium channels in SNc dopaminergic neurons. Application of 6-OHDA (0.5-2mM) evoked a dose-dependent, desensitizing inward current and intracellular free calcium concentration ([Ca(2+)]i) rise. In voltage clamp, ω-conotoxin-sensitive Ca(2+) current modulation mediated by 6-OHDA reflected an altered sensitivity. Furthermore, we found that 6-OHDA modulated Ca(2+) currents through PKA pathway. These results provided evidence for the potential role of VGCCs and PKA involved in oxidative stress in degeneration of SNc neurons in Parkinson's disease (PD). Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Solvents and Parkinson disease: A systematic review of toxicological and epidemiological evidence

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Lock, Edward A., E-mail: e.lock@ljmu.ac.uk [Liverpool John Moores University, School of Pharmacy and Biomolecular Sciences, Byrom Street, Liverpool (United Kingdom); Zhang, Jing [University of Washington, Department of Pathology, School of Medicine, Seattle, WA (United States); Checkoway, Harvey [University of Washington, Department of Environmental and Occupational Health Sciences, Seattle, WA (United States)

2013-02-01

Parkinson disease (PD) is a debilitating neurodegenerative motor disorder, with its motor symptoms largely attributable to loss of dopaminergic neurons in the substantia nigra. The causes of PD remain poorly understood, although environmental toxicants may play etiologic roles. Solvents are widespread neurotoxicants present in the workplace and ambient environment. Case reports of parkinsonism, including PD, have been associated with exposures to various solvents, most notably trichloroethylene (TCE). Animal toxicology studies have been conducted on various organic solvents, with some, including TCE, demonstrating potential for inducing nigral system damage. However, a confirmed animal model of solvent-induced PD has not been developed. Numerous epidemiologic studies have investigated potential links between solvents and PD, yielding mostly null or weak associations. An exception is a recent study of twins indicating possible etiologic relations with TCE and other chlorinated solvents, although findings were based on small numbers, and dose–response gradients were not observed. At present, there is no consistent evidence from either the toxicological or epidemiologic perspective that any specific solvent or class of solvents is a cause of PD. Future toxicological research that addresses mechanisms of nigral damage from TCE and its metabolites, with exposure routes and doses relevant to human exposures, is recommended. Improvements in epidemiologic research, especially with regard to quantitative characterization of long-term exposures to specific solvents, are needed to advance scientific knowledge on this topic. -- Highlights: ► The potential for organic solvents to cause Parkinson's disease has been reviewed. ► Twins study suggests etiologic relations with chlorinated solvents and Parkinson's. ► Animal studies with TCE showed potential to cause damage to dopaminergic neurons. ► Need to determine if effects in animals are relevant to human

Solvents and Parkinson disease: A systematic review of toxicological and epidemiological evidence

International Nuclear Information System (INIS)

Lock, Edward A.; Zhang, Jing; Checkoway, Harvey

2013-01-01

Parkinson disease (PD) is a debilitating neurodegenerative motor disorder, with its motor symptoms largely attributable to loss of dopaminergic neurons in the substantia nigra. The causes of PD remain poorly understood, although environmental toxicants may play etiologic roles. Solvents are widespread neurotoxicants present in the workplace and ambient environment. Case reports of parkinsonism, including PD, have been associated with exposures to various solvents, most notably trichloroethylene (TCE). Animal toxicology studies have been conducted on various organic solvents, with some, including TCE, demonstrating potential for inducing nigral system damage. However, a confirmed animal model of solvent-induced PD has not been developed. Numerous epidemiologic studies have investigated potential links between solvents and PD, yielding mostly null or weak associations. An exception is a recent study of twins indicating possible etiologic relations with TCE and other chlorinated solvents, although findings were based on small numbers, and dose–response gradients were not observed. At present, there is no consistent evidence from either the toxicological or epidemiologic perspective that any specific solvent or class of solvents is a cause of PD. Future toxicological research that addresses mechanisms of nigral damage from TCE and its metabolites, with exposure routes and doses relevant to human exposures, is recommended. Improvements in epidemiologic research, especially with regard to quantitative characterization of long-term exposures to specific solvents, are needed to advance scientific knowledge on this topic. -- Highlights: ► The potential for organic solvents to cause Parkinson's disease has been reviewed. ► Twins study suggests etiologic relations with chlorinated solvents and Parkinson's. ► Animal studies with TCE showed potential to cause damage to dopaminergic neurons. ► Need to determine if effects in animals are relevant to human exposure

Drosophila divalent metal ion transporter Malvolio is required in dopaminergic neurons for feeding decisions.

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Søvik, E; LaMora, A; Seehra, G; Barron, A B; Duncan, J G; Ben-Shahar, Y

2017-06-01

Members of the natural resistance-associated macrophage protein (NRAMP) family are evolutionarily conserved metal ion transporters that play an essential role in regulating intracellular divalent cation homeostasis in both prokaryotes and eukaryotes. Malvolio (Mvl), the sole NRAMP family member in insects, plays a role in food choice behaviors in Drosophila and other species. However, the specific physiological and cellular processes that require the action of Mvl for appropriate feeding decisions remain elusive. Here, we show that normal food choice requires Mvl function specifically in the dopaminergic system, and can be rescued by supplementing food with manganese. Collectively, our data indicate that the action of the Mvl transporter affects food choice behavior via the regulation of dopaminergic innervation of the mushroom bodies, a principle brain region associated with decision-making in insects. Our studies suggest that the homeostatic regulation of the intraneuronal levels of divalent cations plays an important role in the development and function of the dopaminergic system and associated behaviors. © 2017 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

Effects of SR141716A on Cognitive and Depression-Related Behavior in an Animal Model of Premotor Parkinson's Disease

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M. T. Tadaiesky

2010-01-01

Full Text Available A previous study from our laboratory revealed that moderate nigral dopaminergic degeneration caused emotional and cognitive deficits in rats, paralleling early signs of Parkinson's disease. Recent evidence suggests that the blockade of cannabinoid CB1 receptors might be beneficial to alleviate motor inhibition typical of Parkinson's disease. Here, we investigated whether antagonism of CB1 receptors would improve emotional and cognitive deficits in a rat model of premotor Parkinson's disease. Depression-like behavior and cognition were assessed with the forced swim test and the social recognition test, respectively. Confirming our previous study, rats injected with 6-hydroxydopamine in striatum presented emotional and cognitive alterations which were improved by acute injection of SR141716A. HPLC analysis of monoamine levels demonstrated alterations in the striatum and prefrontal cortex after SR141716A injection. These findings suggest a role for CB1 receptors in the early symptoms caused by degeneration of dopaminergic neurons in the striatum, as observed in Parkinson's disease.

Galanin-like peptide stimulates feeding and sexual behavior via dopaminergic fibers within the medial preoptic area of adult male rats.

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Taylor, A; Madison, F N; Fraley, G S

2009-03-01

Galanin-like peptide (GALP) is located in the arcuate nucleus (Arc) of the hypothalamus and is known to regulate both food intake and sexual behaviors in adult male rats. We have previously demonstrated that ICV GALP administration elicits a significant fos response within the medial preoptic area (mPOA). GALP is known to stimulate both food intake and male-typical sex behavior, presumably by direct actions within the mPOA. Recent data from our and other labs have led us to suspect that GALP effects on sex behaviors are due to activation of incertohypothalamic dopaminergic neurons that terminate within the mPOA. To test the hypothesis that GALP activates mPOA dopaminergic systems, we utilized an immunolesion technique to eliminate dopaminergic fiber input to the mPOA via a dopamine transporter-specific toxin (DATSAP, n=8) and compared to control injections (SAP, n=8). All animals were sexually experienced adult male Long-Evans rats. DATSAP-treated male rats showed a significant (psexual behaviors compared to SAP controls. We found that elimination of dopaminergic fibers within the mPOA significantly (psexual behavior under normal mating paradigms. Injections of GALP (5.0 nmol) significantly increased (psexual behaviors in male rats by stimulating dopaminergic neurons that terminate within the mPOA.

Systemic administration of valproic acid and zonisamide promotes the survival and differentiation of induced pluripotent stem cell–derived dopaminergic neurons

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Tatsuya eYoshikawa

2013-02-01

Full Text Available Cell replacement therapy using embryonic stem cells (ESCs and induced pluripotent stem cells (iPSCs is a promising strategy for the treatment of neurologic diseases such as Parkinson’s disease (PD. However, a limiting factor for effective cell transplantation is the low survival rate of grafted cells, especially neurons. In this study, we modified the host environment and investigated whether the simultaneous administration of soluble factors can improve the survival and differentiation of murine iPSC-derived dopaminergic (DA neurons in host brains. With the goal of applying this technology in clinical settings in the near future, we selected drugs that were already approved for clinical use. The drugs included two commonly used anticonvulsants, valproic acid (VPA and zonisamide (ZNS, and estradiol (E2, also known as biologically active estrogen. Following neural induction of murine iPSCs, we collected neural progenitor cells by sorting PSA-NCAM+ cells, then treated the PSA-NCAM+ cells with drugs for four days. An immunofluorescence study revealed that 0.01 mM and 0.1 mM of VPA and 10 nM of E2 increased the percentage of tyrosine hydroxylase+ (TH: a DA neuron marker cells in vitro. Furthermore, 0.1 mM of VPA increased the percentage of TH+ cells that simultaneously express the midbrain markers FOXA2 and NURR1. Next, in order to determine the effects of the drugs in vivo, the iPSC-derived NPCs were transplanted into the striata of intact SD rats. The animals received intraperitoneal injections of one of the drugs for four weeks, then were subjected to an immunofluorescence study. VPA administration (150 mg/kg/daily increased the number of NeuN+ postmitotic neurons and TH+ DA neurons in the grafts. Furthermore, VPA (150 mg/kg/daily and ZNS (30 mg/kg/daily increased the number of TH+FOXA2+ midbrain DA neurons. These results suggest that the systemic administration of VPA and ZNS may improve the efficiency of cell replacement therapy using i

Imaging of the dopaminergic neurotransmission system using single-photon emission tomography and positron emission tomography in patients with parkinsonism

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Booij, J.; Tissingh, G.; Winogrodzka, A.; Royen, E.A. van

1999-01-01

Parkinsonism is a feature of a number of neurodegenerative diseases, including Parkinson's disease, multiple system atrophy and progressive supranuclear palsy. The results of post-mortem studies point to dysfunction of the dopaminergic neurotransmitter system in patients with parkinsonism. Nowadays, by using single-photon emission tomography (SPET) and positron emission tomography (PET) it is possible to visualise both the nigrostriatal dopaminergic neurons and the striatal dopamine D 2 receptors in vivo. Consequently, SPET and PET imaging of elements of the dopaminergic system can play an important role in the diagnosis of several parkinsonian syndromes. This review concentrates on findings of SPET and PET studies of the dopaminergic neurotransmitter system in various parkinsonian syndromes. (orig.)

Investigations into potential extrasynaptic communication between the dopaminergic and nitrergic systems

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Miso eMitkovski

2012-09-01

Full Text Available Nitric oxide is unconstrained by cell membranes and can therefore act along a broad distance as a volume transmitter. Spillover of nitric oxide between neurons may have a major impact on central nervous system diseases and particularly on neurodegeneration. There is evidence whereby communication between nitrergic and dopaminergic systems plays an essential role in the control of the nigrostriatal pathway. However, there is sparse information for either the coexistence or overlap of nitric oxide and dopaminergic structures. The present study used double-labeling immunofluorescent microscopy to investigate the degree of cellular co-localization between nitric oxide synthase and tyrosine hydroxylase, enzymes responsible for the synthesis of nitric oxide and dopamine, respectively, was examined in neurons of the nigrostriatal pathway regions in the rat brain. After perfusional fixation, the brains were cut and double immunostained. A proximity analysis of tyrosine hydroxylase and nitric oxide synthase structures was made using confocal laser scanning microscopy, in nigrostriatal regions of the rat brain. We used image acquired at the optical limit and generated binary masks at 2µm-wide margin from the respective maximum projections. Co-localization between the two antigens was infrequent (<10% in most areas examined. However, tyrosine hydroxylase labeling was particularly concentrated close to nitric oxide synthase dendrites/axons and the cell bodies. These results further substantiate an extrasynaptic substrate for interaction between nitrergic and dopaminergic systems, thereby modulating sensitivity to neural inputs and its gene expression.

Klotho Protects Dopaminergic Neuron Oxidant-Induced Degeneration by Modulating ASK1 and p38 MAPK Signaling Pathways.

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Reynolds K Brobey

Full Text Available Klotho transgenic mice exhibit resistance to oxidative stress as measured by their urinal levels of 8-hydroxy-2-deoxyguanosine, albeit this anti-oxidant defense mechanism has not been locally investigated in the brain. Here, we tested the hypothesis that the reactive oxygen species (ROS-sensitive apoptosis signal-regulating kinase 1 (ASK1/p38 MAPK pathway regulates stress levels in the brain of these mice and showed that: 1 the ratio of free ASK1 to thioredoxin (Trx-bound ASK1 is relatively lower in the transgenic brain whereas the reverse is true for the Klotho knockout mice; 2 the reduced p38 activation level in the transgene corresponds to higher level of ASK1-bound Trx, while the KO mice showed elevated p38 activation and lower level of-bound Trx; and 3 that 14-3-3ζ is hyper phosphorylated (Ser-58 in the transgene which correlated with increased monomer forms. In addition, we evaluated the in vivo robustness of the protection by challenging the brains of Klotho transgenic mice with a neurotoxin, MPTP and analyzed for residual neuron numbers and integrity in the substantia nigra pars compacta. Our results show that Klotho overexpression significantly protects dopaminergic neurons against oxidative damage, partly by modulating p38 MAPK activation level. Our data highlight the importance of ASK1/p38 MAPK pathway in the brain and identify Klotho as a possible anti-oxidant effector.

A Human Neural Crest Stem Cell-Derived Dopaminergic Neuronal Model Recapitulates Biochemical Abnormalities in GBA1 Mutation Carriers

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Shi-Yu Yang

2017-03-01

Full Text Available Numerically the most important risk factor for the development of Parkinson's disease (PD is the presence of mutations in the glucocerebrosidase GBA1 gene. In vitro and in vivo studies show that GBA1 mutations reduce glucocerebrosidase (GCase activity and are associated with increased α-synuclein levels, reflecting similar changes seen in idiopathic PD brain. We have developed a neural crest stem cell-derived dopaminergic neuronal model that recapitulates biochemical abnormalities in GBA1 mutation-associated PD. Cells showed reduced GCase protein and activity, impaired macroautophagy, and increased α-synuclein levels. Advantages of this approach include easy access to stem cells, no requirement to reprogram, and retention of the intact host genome. Treatment with a GCase chaperone increased GCase protein levels and activity, rescued the autophagic defects, and decreased α-synuclein levels. These results provide the basis for further investigation of GCase chaperones or similar drugs to slow the progression of PD.

IAP-Based Cell Sorting Results in Homogeneous Transplantable Dopaminergic Precursor Cells Derived from Human Pluripotent Stem Cells

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Daniela Lehnen

2017-10-01

Full Text Available Human pluripotent stem cell (hPSC-derived mesencephalic dopaminergic (mesDA neurons can relieve motor deficits in animal models of Parkinson's disease (PD. Clinical translation of differentiation protocols requires standardization of production procedures, and surface-marker-based cell sorting is considered instrumental for reproducible generation of defined cell products. Here, we demonstrate that integrin-associated protein (IAP is a cell surface marker suitable for enrichment of hPSC-derived mesDA progenitor cells. Immunomagnetically sorted IAP+ mesDA progenitors showed increased expression of ventral midbrain floor plate markers, lacked expression of pluripotency markers, and differentiated into mature dopaminergic (DA neurons in vitro. Intrastriatal transplantation of IAP+ cells sorted at day 16 of differentiation in a rat model of PD resulted in functional recovery. Grafts from sorted IAP+ mesDA progenitors were more homogeneous in size and DA neuron density. Thus, we suggest IAP-based sorting for reproducible prospective enrichment of mesDA progenitor cells in clinical cell replacement strategies.

A discrete dopaminergic projection from the incertohypothalamic A13 cell group to the dorsolateral periaqueductal gray in rat

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Fany eMessanvi

2013-12-01

Full Text Available Several findings have indicated an involvement of dopamine in panic and defensive behaviors. The dorsolateral column of the periaqueductal gray (dlPAG is crucially involved in the expression of panic attacks in humans and defensive behaviors, also referred to as panic-like behaviors, in animals. Although the dlPAG is known to receive a specific innervation of dopaminergic fibers and abundantly expresses dopamine receptors, the origin of this dopaminergic input is largely unknown. This study aimed at mapping the dopaminergic projections to the dlPAG in order to provide further insight into the panic-like related behavior circuitry of the dlPAG. For this purpose, the retrograde tracer cholera toxin subunit b (CTb was injected into the dlPAG of male Wistar rats and double immunofluorescence for CTb and tyrosine hydroxylase (TH, the rate-limiting enzyme in the synthesis of dopamine, was performed. Neurons labeled for both CTb and TH were counted in different dopaminergic cell groups. The findings indicate that the dopaminergic nerve terminals present in the dlPAG originate from multiple dopamine-containing cell groups in the hypothalamus and mesencephalon. Interestingly, the A13 cell group is the main source of dopaminergic afferents to the dlPAG and contains at least 45% of the total number of CTb/TH-positive neurons. Anterograde tracing with biotinylated dextran amine (BDA combined with double immunofluorescence for BDA and TH confirmed the projections from the A13 cell group to the dlPAG. The remainder of the dopamine-positive terminals present in the dlPAG was found to originate from the extended A10 cell group and the A11 group. The A13 cell group is known to send dopaminergic efferents to several other brain regions implicated in defensive behavior, including the central amygdala and ventromedial hypothalamus. Therefore, although direct behavioral evidence is lacking, our finding that the A13 cell group is also the main source of dopaminergic

The anorexic agents, sibutramine and fenfluramine, depress GABAB-induced inhibitory postsynaptic potentials in rat mesencephalic dopaminergic cells

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Ledonne, Ada; Sebastianelli, Luca; Federici, Mauro; Bernardi, Giorgio; Mercuri, Nicola Biagio

2009-01-01

Background and purpose Nutrition is the result of a complex interaction among environmental, homeostatic and reward-related processes. Accumulating evidence supports key roles for the dopaminergic neurons of the ventral midbrain in regulating feeding behaviour. For this reason, in the present study, we have investigated the electrophysiological effects of two centrally acting anorexic agents, fenfluramine and sibutramine, on these cells. Experimental approach Rat midbrain slices were used to make intracellular recordings from dopaminergic neurons of the substantia nigra and the ventral tegmental area. Gamma-aminobutyric acid (GABA)-mediated synaptic transmission was assessed from the inhibitory postsynaptic potentials (IPSPs) mediated by GABAA and GABAB receptors. Key results Fenfluramine and sibutramine reduced, concentration-dependently, the GABAB IPSPs, without affecting the GABAA-mediated potentials. This effect is presynaptic, as postsynaptic membrane responses induced by application of a GABAB receptor agonist, baclofen, were not affected by the two drugs. Furthermore, the selective 5-hydroxytriptamine 1B (5-HT1B) receptor antagonist, SB216641, blocked the reduction of GABAB IPSPs caused by fenfluramine and sibutramine, indicating that the receptor mediating this effect is 5-HT1B. Conclusions and implications Two anorexic agents, fenfluramine and sibutramine, induced the activation of 5-HT1B receptors located on presynaptic GABAergic terminals, thus reducing the release of GABA. This action can alter the strength of synaptic afferents that modify the activity of dopaminergic neurons, inducing neuronal excitation. Our results reveal an additional mechanism of action for fenfluramine and sibutramine that might contribute to reducing food intake, by influencing the pleasurable and motor aspects of feeding behaviour. PMID:19298257

HIV-1 TAT protein enhances sensitization to methamphetamine by affecting dopaminergic function.

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Kesby, James P; Najera, Julia A; Romoli, Benedetto; Fang, Yiding; Basova, Liana; Birmingham, Amanda; Marcondes, Maria Cecilia G; Dulcis, Davide; Semenova, Svetlana

2017-10-01

Methamphetamine abuse is common among humans with immunodeficiency virus (HIV). The HIV-1 regulatory protein TAT induces dysfunction of mesolimbic dopaminergic systems which may result in impaired reward processes and contribute to methamphetamine abuse. These studies investigated the impact of TAT expression on methamphetamine-induced locomotor sensitization, underlying changes in dopamine function and adenosine receptors in mesolimbic brain areas and neuroinflammation (microgliosis). Transgenic mice with doxycycline-induced TAT protein expression in the brain were tested for locomotor activity in response to repeated methamphetamine injections and methamphetamine challenge after a 7-day abstinence period. Dopamine function in the nucleus accumbens (Acb) was determined using high performance liquid chromatography. Expression of dopamine and/or adenosine A receptors (ADORA) in the Acb and caudate putamen (CPu) was assessed using RT-PCR and immunohistochemistry analyses. Microarrays with pathway analyses assessed dopamine and adenosine signaling in the CPu. Activity-dependent neurotransmitter switching of a reserve pool of non-dopaminergic neurons to a dopaminergic phenotype in the ventral tegmental area (VTA) was determined by immunohistochemistry and quantified with stereology. TAT expression enhanced methamphetamine-induced sensitization. TAT expression alone decreased striatal dopamine (D1, D2, D4, D5) and ADORA1A receptor expression, while increasing ADORA2A receptors expression. Moreover, TAT expression combined with methamphetamine exposure was associated with increased adenosine A receptors (ADORA1A) expression and increased recruitment of dopamine neurons in the VTA. TAT expression and methamphetamine exposure induced microglia activation with the largest effect after combined exposure. Our findings suggest that dopamine-adenosine receptor interactions and reserve pool neuronal recruitment may represent potential targets to develop new treatments for

Neuroprotective Effects of Erucin against 6-Hydroxydopamine-Induced Oxidative Damage in a Dopaminergic-like Neuroblastoma Cell Line

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Giorgio Cantelli-Forti

2012-08-01

Full Text Available Oxidative stress (OS contributes to the cascade leading to the dysfunction or death of dopaminergic neurons during Parkinson’s disease (PD. A strategy to prevent the OS of dopaminergic neurons may be the use of phytochemicals as inducers of endogenous antioxidants and phase 2 enzymes. In this study, we demonstrated that treatment of the dopaminergic-like neuroblastoma SH-SY5Y cell line with isothiocyanate erucin (ER, a compound of cruciferous vegetables, resulted in significant increases of both total glutathione (GSH levels and total antioxidant capacity at the cytosolic level. The increase of GSH levels was associated with an increase in the resistance of SH-SY5Y cells to neuronal death, in terms of apoptosis, induced by 6-hydroxydopamine (6-OHDA. The pretreatment of SH-SY5Y cells with ER was also shown to prevent the redox status impairment, in terms of intracellular ROS and O₂^•− formation, and loss of mitochondrial membrane potential, early events that are initiators of the apoptotic process, induced by 6-OHDA. Last, the antiapoptotic and antioxidant effects of ER were abolished by buthionine sulfoximine, supporting the main role of GSH in the neuroprotective effects recorded by ER. These results suggest that ER may prevent the oxidative damage induced by 6-OHDA.

Dopaminergic neurotoxicant 6-OHDA induces oxidative damage through proteolytic activation of PKC{delta} in cell culture and animal models of Parkinson's disease

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Latchoumycandane, Calivarathan; Anantharam, Vellareddy; Jin, Huajun; Kanthasamy, Anumantha; Kanthasamy, Arthi, E-mail: arthik@iastate.edu

2011-11-15

The neurotoxicant 6-hydroxydopamine (6-OHDA) is used to investigate the cellular and molecular mechanisms underlying selective degeneration of dopaminergic neurons in Parkinson's disease (PD). Oxidative stress and caspase activation contribute to the 6-OHDA-induced apoptotic cell death of dopaminergic neurons. In the present study, we sought to systematically characterize the key downstream signaling molecule involved in 6-OHDA-induced dopaminergic degeneration in cell culture and animal models of PD. Treatment of mesencephalic dopaminergic neuronal N27 cells with 6-OHDA (100 {mu}M) for 24 h significantly reduced mitochondrial activity and increased cytosolic cytochrome c, followed by sequential activation of caspase-9 and caspase-3. Co-treatment with the free radical scavenger MnTBAP (10 {mu}M) significantly attenuated 6-OHDA-induced caspase activities. Interestingly, 6-OHDA induced proteolytic cleavage and activation of protein kinase C delta (PKC{delta}) was completely suppressed by treatment with a caspase-3-specific inhibitor, Z-DEVD-FMK (50 {mu}M). Furthermore, expression of caspase-3 cleavage site-resistant mutant PKC{delta}{sup D327A} and kinase dead PKC{delta}{sup K376R} or siRNA-mediated knockdown of PKC{delta} protected against 6-OHDA-induced neuronal cell death, suggesting that caspase-3-dependent PKC{delta} promotes oxidative stress-induced dopaminergic degeneration. Suppression of PKC{delta} expression by siRNA also effectively protected N27 cells from 6-OHDA-induced apoptotic cell death. PKC{delta} cleavage was also observed in the substantia nigra of 6-OHDA-injected C57 black mice but not in control animals. Viral-mediated delivery of PKC{delta}{sup D327A} protein protected against 6-OHDA-induced PKC{delta} activation in mouse substantia nigra. Collectively, these results strongly suggest that proteolytic activation of PKC{delta} is a key downstream event in dopaminergic degeneration, and these results may have important translational value for

Polylysine-modified polyethylenimine (PEI-PLL) mediated VEGF gene delivery protects dopaminergic neurons in cell culture and in rat models of Parkinson's Disease (PD).

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Sheikh, Muhammad Abid; Malik, Yousra Saeed; Xing, Zhenkai; Guo, Zhaopei; Tian, Huayu; Zhu, Xiaojuan; Chen, Xuesi

2017-05-01

Parkinson's Disease (PD) is a chronic neurodegenerative disorder characterized by motor deficits which result from the progressive loss of dopaminergic neurons. Gene therapy using growth factors such as VEGF seems to be a viable approach for potential therapeutic treatment of PD. In this study, we utilized a novel non-viral gene carrier designated as PEI-PLL synthesized by our laboratory to deliver VEGF gene to study its effect by using both cell culture as well as animal models of PD. For cell culture experiments, we utilized 6-hydroxydopamine (6-OHDA) mediated cell death model of MN9D cells following transfection with either a control plasmid or VEGF expressing plasmid. As compared to control transfected cells, PEI-PLL mediated VEGF gene delivery to MN9D cells resulted in increased cell viability, increase in the number of Tyrosine hydroxylase (TH) positive cells and decreased apoptosis following 6-OHDA insult. Next, we studied the therapeutic potential of PEI-PLL mediated VEGF gene delivery in SNPc by using unilateral 6-OHDA Medial forebrain bundle (MFB) lesion model of PD in rats. VEGF administration prevented the loss of motor functions induced by 6-OHDA as determined by behavior analysis. Similarly, VEGF inhibited the 6-OHDA mediated loss of DA neurons in Substantia Nigra Pars Compacta (SNPc) as well as DA nerve fibers in striatum as determined by TH immunostaining. In addition, PEI-PLL mediated VEGF gene delivery also prevented apoptosis and microglial activation in PD rat models. Together, these results clearly demonstrated the beneficial effects of PEI-PLL mediated VEGF gene delivery on dopaminergic system in both cell culture and animal models of PD. In this report, we exploited the potential of PEI-PLL to deliver VEGF gene for the potential therapeutic treatment of PD by using both cell culture and animal models of PD. To the best of our knowledge, this is the first report describing the use of novel polymeric gene carriers for the delivery of VEGF gene

Intermittent, low dose carbon monoxide exposure enhances survival and dopaminergic differentiation of human neural stem cells

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Dreyer-Andersen, Nanna; Almeida, Ana Sofia; Jensen, Pia

2018-01-01

Exploratory studies using human fetal tissue have suggested that intrastriatal transplantation of dopaminergic neurons may become a future treatment for patients with Parkinson's disease. However, the use of human fetal tissue is compromised by ethical, regulatory and practical concerns. Human stem...... cells constitute an alternative source of cells for transplantation in Parkinson's disease, but efficient protocols for controlled dopaminergic differentiation need to be developed. Short-term, low-level carbon monoxide (CO) exposure has been shown to affect signaling in several tissues, resulting...... in Parkinson's disease....

Cholesterol contributes to dopamine-neuronal loss in MPTP mouse model of Parkinson's disease: Involvement of mitochondrial dysfunctions and oxidative stress.

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Rajib Paul

Full Text Available Hypercholesterolemia is a known contributor to the pathogenesis of Alzheimer's disease while its role in the occurrence of Parkinson's disease (PD is only conjecture and far from conclusive. Altered antioxidant homeostasis and mitochondrial functions are the key mechanisms in loss of dopaminergic neurons in the substantia nigra (SN region of the midbrain in PD. Hypercholesterolemia is reported to cause oxidative stress and mitochondrial dysfunctions in the cortex and hippocampus regions of the brain in rodents. However, the impact of hypercholesterolemia on the midbrain dopaminergic neurons in animal models of PD remains elusive. We tested the hypothesis that hypercholesterolemia in MPTP model of PD would potentiate dopaminergic neuron loss in SN by disrupting mitochondrial functions and antioxidant homeostasis. It is evident from the present study that hypercholesterolemia in naïve animals caused dopamine neuronal loss in SN with subsequent reduction in striatal dopamine levels producing motor impairment. Moreover, in the MPTP model of PD, hypercholesterolemia exacerbated MPTP-induced reduction of striatal dopamine as well as dopaminergic neurons in SN with motor behavioral depreciation. Activity of mitochondrial complexes, mainly complex-I and III, was impaired severely in the nigrostriatal pathway of hypercholesterolemic animals treated with MPTP. Hypercholesterolemia caused oxidative stress in the nigrostriatal pathway with increased generation of hydroxyl radicals and enhanced activity of antioxidant enzymes, which were further aggravated in the hypercholesterolemic mice with Parkinsonism. In conclusion, our findings provide evidence of increased vulnerability of the midbrain dopaminergic neurons in PD with hypercholesterolemia.

Cholesterol contributes to dopamine-neuronal loss in MPTP mouse model of Parkinson's disease: Involvement of mitochondrial dysfunctions and oxidative stress.

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Paul, Rajib; Choudhury, Amarendranath; Kumar, Sanjeev; Giri, Anirudha; Sandhir, Rajat; Borah, Anupom

2017-01-01

Hypercholesterolemia is a known contributor to the pathogenesis of Alzheimer's disease while its role in the occurrence of Parkinson's disease (PD) is only conjecture and far from conclusive. Altered antioxidant homeostasis and mitochondrial functions are the key mechanisms in loss of dopaminergic neurons in the substantia nigra (SN) region of the midbrain in PD. Hypercholesterolemia is reported to cause oxidative stress and mitochondrial dysfunctions in the cortex and hippocampus regions of the brain in rodents. However, the impact of hypercholesterolemia on the midbrain dopaminergic neurons in animal models of PD remains elusive. We tested the hypothesis that hypercholesterolemia in MPTP model of PD would potentiate dopaminergic neuron loss in SN by disrupting mitochondrial functions and antioxidant homeostasis. It is evident from the present study that hypercholesterolemia in naïve animals caused dopamine neuronal loss in SN with subsequent reduction in striatal dopamine levels producing motor impairment. Moreover, in the MPTP model of PD, hypercholesterolemia exacerbated MPTP-induced reduction of striatal dopamine as well as dopaminergic neurons in SN with motor behavioral depreciation. Activity of mitochondrial complexes, mainly complex-I and III, was impaired severely in the nigrostriatal pathway of hypercholesterolemic animals treated with MPTP. Hypercholesterolemia caused oxidative stress in the nigrostriatal pathway with increased generation of hydroxyl radicals and enhanced activity of antioxidant enzymes, which were further aggravated in the hypercholesterolemic mice with Parkinsonism. In conclusion, our findings provide evidence of increased vulnerability of the midbrain dopaminergic neurons in PD with hypercholesterolemia.

Estimation of in vitro activity of tuberoinfundibular dopaminergic neurons by measurement of DOPA synthesis in the median eminence of hypothalamic slices.

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Arita, J; Kimura, F

1984-12-01

A new method for estimation of in vitro neurosecretory activity of tuberoinfundibular dopaminergic (TIDA) neurons was developed by measuring the rate of synthesis of dihydroxyphenylalanine (DOPA) in the median eminence of hypothalamic slices. Sagittal hypothalamic slices of ovariectomized rats were incubated in a medium containing 3-hydroxybenzylhydrazine (NSD 1015), an inhibitor of DOPA decarboxylase. DOPA accumulated in the median eminence following incubation with NSD 1015 was determined by high-performance liquid chromatography with electro-chemical detection. The amount of DOPA accumulated in vitro in the median eminence was maximal in a medium containing 10 mM NSD 1015 and linear up to 120 min at 37 degrees C. Increasing the concentration of tyrosine in medium stimulated the synthesis of DOPA in the median eminence. The synthesis of DOPA was blocked by 1 mM alpha-methyltyrosine, an inhibitor of tyrosine hydroxylase. The rate of in vitro synthesis of DOPA in the median eminence was 33% of that of in vivo synthesis. Incubation in a medium containing 50 mM K+ to depolarize neurons caused a 2.4-fold increase in DOPA synthesis in the median eminence. The high K+-induced increase in DOPA synthesis was blocked by omission of Ca2+ and addition of 1 mM EGTA into the medium, suggesting Ca2+ dependency of depolarization-activated DOPA synthesis. These results indicate that this in vitro assay is a useful means to study the regulatory mechanisms of TIDA neurons.

Neuroprotective Effect and Mechanism of Thiazolidinedione on Dopaminergic Neurons In Vivo and In Vitro in Parkinson’s Disease

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Yanqin Wang

2017-01-01

Full Text Available The aim of the present study was to gain insight into the neuroprotection effects and mechanism of thiazolidinedione pioglitazone in both in vitro and in vivo MPP+/MPTP induced PD models. In vivo experimental results showed that oral treatment of pioglitazone resulted in significant improvements in behavior symptoms damaged by MPTP and increase in the survival of TH positive neurons in the pioglitazone intervention groups. In addition, oral treatment of pioglitazone increased the expression of peroxisome proliferator-activated receptor-γ coactivator of 1α (PGC-1α and increased the number of mitochondria, along with an observed improvement in mitochondrial ultrastructure. From in vitro studies, 2,4-thiazolidinedione resulted in increased levels of molecules regulated function of mitochondria, including PGC-1α, nuclear respiratory factor 1 (NRF1, NRF2, and mitochondria fusion 2 (Mfn2, and inhibited mitochondria fission 1 (Fis1. We show that protein levels of Bcl-2 and ERK were reduced in the MPP+-treated group compared with the control group. This effect was observed to be reversed upon treatment with 2,4-thiazolidinedione, as Bcl-2 and ERK expression levels were increased. We also observed that levels of the apoptotic protein Bax showed opposite changes compared to Bcl-2 and ERK levels. The results from this study confirm that pioglitazone/2,4-thiazolidinedione is able to activate PGC-1α and prevent damage of dopaminergic neurons and restore mitochondria ultrastructure through the regulation of mitochondria function.

Characterization of the human oncogene SCL/TAL1 interrupting locus (Stil) mediated Sonic hedgehog (Shh) signaling transduction in proliferating mammalian dopaminergic neurons

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Sun, Lei [Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Department of Physiology, Nankai University School of Medicine, Tianjin 300071 (China); Carr, Aprell L. [Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN 46556 (United States); Li, Ping; Lee, Jessica; McGregor, Mary [Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Li, Lei, E-mail: Li.78@nd.edu [Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556 (United States); Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN 46556 (United States)

2014-07-11

Highlights: • Stil is a human oncogene that is conserved in vertebrate species. • Stil functions in the Shh pathway in mammalian cells. • The expression of Stil is required for mammalian dopaminergic cell proliferation. - Abstract: The human oncogene SCL/TAL1 interrupting locus (Stil) is highly conserved in all vertebrate species. In humans, the expression of Stil is involved in cancer cell survival, apoptosis and proliferation. In this research, we investigated the roles of Stil expression in cell proliferation of mammalian dopaminergic (DA) PC12 cells. Stil functions through the Sonic hedgehog (Shh) signal transduction pathway. Co-immunoprecipitation tests revealed that STIL interacts with Shh downstream components, which include SUFU and GLI1. By examining the expression of Stil, Gli1, CyclinD2 (cell-cycle marker) and PCNA (proliferating cell nuclear antigen), we found that up-regulation of Stil expression (transfection with overexpression plasmids) increased Shh signaling transduction and PC12 cell proliferation, whereas down-regulation of Stil expression (by shRNA) inhibited Shh signaling transduction, and thereby decreased PC12 cell proliferation. Transient transfection of PC12 cells with Stil knockdown or overexpression plasmids did not affect PC12 cell neural differentiation, further indicating the specific roles of Stil in cell proliferation. The results from this research suggest that Stil may serve as a bio-marker for neurological diseases involved in DA neurons, such as Parkinson’s disease.

Competing dopamine neurons drive oviposition choice for ethanol in Drosophila.

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Azanchi, Reza; Kaun, Karla R; Heberlein, Ulrike

2013-12-24

The neural circuits that mediate behavioral choice evaluate and integrate information from the environment with internal demands and then initiate a behavioral response. Even circuits that support simple decisions remain poorly understood. In Drosophila melanogaster, oviposition on a substrate containing ethanol enhances fitness; however, little is known about the neural mechanisms mediating this important choice behavior. Here, we characterize the neural modulation of this simple choice and show that distinct subsets of dopaminergic neurons compete to either enhance or inhibit egg-laying preference for ethanol-containing food. Moreover, activity in α'β' neurons of the mushroom body and a subset of ellipsoid body ring neurons (R2) is required for this choice. We propose a model where competing dopaminergic systems modulate oviposition preference to adjust to changes in natural oviposition substrates.

Elicitation of dopaminergic features of Parkinson's disease in C. elegans by monocrotophos, an organophosphorous insecticide.

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Ali, Shaheen Jafri; Rajini, Padmanabhan Sharda

2012-12-01

Positive correlations have been suggested between usage of pesticides and the incidence of Parkinson's disease (PD) through epidemiological as well as few experimental evidences. Organophosphorus insecticides (OPI), which are extensively used in agricultural and household insect control, have been the subject of increasing concern in the past decades due to their neurotoxic potential. However, very few studies have demonstrated the potentials of OPI to induce features of PD in model organisms. In the present study, Caenorhabditis elegans was selected as the model organism to evaluate the potential of monocrotophos (MCP), an OPI, to elicit dopaminergic features of Parkinson's disease in terms of dopamine content, basic movement and integrity of dopaminergic neurons along with its effect on acetylcholinesterase (AChE) activity and life span. All the responses elicited by MCP were compared with that elicited by 1-methyl-4-phenyl- 1, 2, 3, 6-tetrahydropyridine (MPTP) in both N2 and BZ555 worms. N2 worms were exposed to varying concentrations of MCP (50, 100 and 200 μM) or MPTP (200, 300 and 400 μM) for 48 hours and locomotory rate, as measured by the number of body bends made in 20 seconds, was enumerated. Worms subjected to the same dose paradigms were also analyzed for the dopamine content by HPLC. The results indicated a significant reduction in the dopamine levels in the worms that were treated with MCP/MPTP and this correlated with the changes in locomotion compared to untreated worms. Worms treated with MCP also exhibited significant reduction in AChE activity. Both MPTP and MCP caused a marked reduction in life span in the worms. Transgenic worms (BZ555, which has GFP tagged to its 8 dopaminergic neurons) exposed to MCP and MPTP at the above concentrations showed a dose-dependent reduction in the number of green pixels in CEP and ADE neurons which also correlated with the neurodegeneration as visualized by decreased fluorescence in photomicrographs. Taken

IAP-Based Cell Sorting Results in Homogeneous Transplantable Dopaminergic Precursor Cells Derived from Human Pluripotent Stem Cells.

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Lehnen, Daniela; Barral, Serena; Cardoso, Tiago; Grealish, Shane; Heuer, Andreas; Smiyakin, Andrej; Kirkeby, Agnete; Kollet, Jutta; Cremer, Harold; Parmar, Malin; Bosio, Andreas; Knöbel, Sebastian

2017-10-10

Human pluripotent stem cell (hPSC)-derived mesencephalic dopaminergic (mesDA) neurons can relieve motor deficits in animal models of Parkinson's disease (PD). Clinical translation of differentiation protocols requires standardization of production procedures, and surface-marker-based cell sorting is considered instrumental for reproducible generation of defined cell products. Here, we demonstrate that integrin-associated protein (IAP) is a cell surface marker suitable for enrichment of hPSC-derived mesDA progenitor cells. Immunomagnetically sorted IAP + mesDA progenitors showed increased expression of ventral midbrain floor plate markers, lacked expression of pluripotency markers, and differentiated into mature dopaminergic (DA) neurons in vitro. Intrastriatal transplantation of IAP + cells sorted at day 16 of differentiation in a rat model of PD resulted in functional recovery. Grafts from sorted IAP + mesDA progenitors were more homogeneous in size and DA neuron density. Thus, we suggest IAP-based sorting for reproducible prospective enrichment of mesDA progenitor cells in clinical cell replacement strategies. Copyright © 2017 Miltenyi Biotec GmbH. Published by Elsevier Inc. All rights reserved.

α-Synuclein overexpression increases dopamine toxicity in BE(2-M17 cells

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Miller David W

2010-03-01

Full Text Available Abstract Background Oxidative stress has been proposed to be involved in the pathogenesis of Parkinson's disease (PD. A plausible source of oxidative stress in nigral dopaminergic neurons is the redox reactions that specifically involve dopamine and produce various toxic molecules, i.e., free radicals and quinone species. α-Synuclein, a protein found in Lewy bodies characteristic of PD, is also thought to be involved in the pathogenesis of PD and point mutations and multiplications in the gene coding for α-synuclein have been found in familial forms of PD. Results We used dopaminergic human neuroblastoma BE(2-M17 cell lines stably transfected with WT or A30P mutant α-synuclein to characterize the effect of α-synuclein on dopamine toxicity. Cellular toxicity was analyzed by lactate dehydrogenase assay and by fluorescence-activated cell sorter analysis. Increased expression of either wild-type or mutant α-synuclein enhances the cellular toxicity induced by the accumulation of intracellular dopamine or DOPA. Conclusions Our results suggest that an interplay between dopamine and α-synuclein can cause cell death in a neuron-like background. The data presented here are compatible with several models of cytotoxicity, including the formation of α-synuclein oligomers and impairment of the lysosomal degradation.

Dopaminergic agonists for hepatic encephalopathy

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Als-Nielsen, B; Gluud, L L; Gluud, C

2004-01-01

Hepatic encephalopathy may be associated with an impairment of the dopaminergic neurotransmission. Dopaminergic agonists may therefore have a beneficial effect on patients with hepatic encephalopathy.......Hepatic encephalopathy may be associated with an impairment of the dopaminergic neurotransmission. Dopaminergic agonists may therefore have a beneficial effect on patients with hepatic encephalopathy....

Evidence and possible mechanism for the permanent decline in tuberoinfundibular dopaminergic neuronal activity after chronic estradiol administration in Fischer 233 rats

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Gottschall, P.E.

1986-01-01

The objective of these studies was to determine if the decline in tuberoinfundibular dopaminergic (TIDA) neuronal function observed during chronic estradiol-17-β (E 2 ) administration persisted after E 2 was removed. Ovariectomized (OVX) Fischer 344 rats were implanted with an E 2 -containing Silastic capsule for 4 weeks. Anterior pituitary (AP) weight and serum prolactin was greatly increased at the end of the E 2 treatment, that persisted 4 and 26 weeks after E 2 was withdrawn. Ag the end of E 2 treatment and 4 weeks after E 2 was withdrawn, TIDA function, as evaluated by electrical stimulation of median eminence tissue in vitro after allowing for uptake of 3 H-DA, was decreased compared to OVX controls. In an attempt to elucidate the mechanism by which E 2 results in a permanent decline in TIDA function, F344 rats were given daily bromocryptine injections in addition to a 30-day E 2 treatment. TIDA neuronal release was reduced in both E 2 and E 2 and bromocryptine treated groups. However, by 30 days after discontinuing treatment only rats given E 2 alone showed a persistent decline in TIDA function. Since permanent damage to hypothalamic neurons by an enlarged AP was speculated to be the result of E 2 treatment, neurons which regulate other AP hormones may also be damaged. To evaluate this possibility, pulsatile release of prolactin, growth hormone (GH) and luteinizing hormone (LH) was evaluated in OVX control rats, chronically E 2 -treated rats, and rats 120 days after chronic E 2 treatment. Only the frequency of prolactin pulses, but not the frequency of GH and LH pulses, was reduced in rats 120 days after E 2 treatment. This suggests selectivity in the hypothalamic damage produced by the enlarged AP

Nrf2 deficiency potentiates methamphetamine-induced dopaminergic axonal damage and gliosis in the striatum.

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Granado, Noelia; Lastres-Becker, Isabel; Ares-Santos, Sara; Oliva, Idaira; Martin, Eduardo; Cuadrado, Antonio; Moratalla, Rosario

2011-12-01

Oxidative stress that correlates with damage to nigrostriatal dopaminergic neurons and reactive gliosis in the basal ganglia is a hallmark of methamphetamine (METH) toxicity. In this study, we analyzed the protective role of the transcription factor Nrf2 (nuclear factor-erythroid 2-related factor 2), a master regulator of redox homeostasis, in METH-induced neurotoxicity. We found that Nrf2 deficiency exacerbated METH-induced damage to dopamine neurons, shown by an increase in loss of tyrosine hydroxylase (TH)- and dopamine transporter (DAT)-containing fibers in striatum. Consistent with these effects, Nrf2 deficiency potentiated glial activation, indicated by increased striatal expression of markers for microglia (Mac-1 and Iba-1) and astroglia (GFAP) one day after METH administration. At the same time, Nrf2 inactivation dramatically potentiated the increase in TNFα mRNA and IL-15 protein expression in GFAP+ cells in the striatum. In sharp contrast to the potentiation of striatal damage, Nrf2 deficiency did not affect METH-induced dopaminergic neuron death or expression of glial markers or proinflammatory molecules in the substantia nigra. This study uncovers a new role for Nrf2 in protection against METH-induced inflammatory and oxidative stress and striatal degeneration. Copyright © 2011 Wiley‐Liss, Inc.

Long-Term Health of Dopaminergic Neuron Transplants in Parkinson's Disease Patients

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Penelope J. Hallett

2014-06-01

Full Text Available To determine the long-term health and function of transplanted dopamine neurons in Parkinson’s disease (PD patients, the expression of dopamine transporters (DATs and mitochondrial morphology were examined in human fetal midbrain cellular transplants. DAT was robustly expressed in transplanted dopamine neuron terminals in the reinnervated host putamen and caudate for at least 14 years after transplantation. The transplanted dopamine neurons showed a healthy and nonatrophied morphology at all time points. Labeling of the mitochondrial outer membrane protein Tom20 and α-synuclein showed a typical cellular pathology in the patients’ own substantia nigra, which was not observed in transplanted dopamine neurons. These results show that the vast majority of transplanted neurons remain healthy for the long term in PD patients, consistent with clinical findings that fetal dopamine neuron transplants maintain function for up to 15–18 years in patients. These findings are critically important for the rational development of stem-cell-based dopamine neuronal replacement therapies for PD.

Oxidative stress induces nuclear translocation of C-terminus of α-synuclein in dopaminergic cells

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Xu Shengli; Zhou Ming; Yu Shun; Cai Yanning; Zhang Alex; Ueda, Kenji; Chan Piu

2006-01-01

Growing evidence suggests that oxidative stress is involved in the neuronal degeneration and can promote the aggregation of α-synuclein. However, the role of α-synuclein under physiological and pathological conditions remains poorly understood. In the present study, we examined the possible interaction between the α-synuclein and oxidative stress. In a dopaminergic cell line MES23.5, we have found that the 200 μM H 2 O 2 treatment induced the translocation of α-synuclein from cytoplasm to nuclei at 30 min post-treatment. The immunoactivity of α-synuclein became highly intensive in the nuclei after 2 h treatment. The protein translocated to nucleus was a 10 kDa fragment of C-terminus region of α-synuclein, while full-length α-synuclein remained in cytoplasm. Thioflavine-S staining suggested that the C-terminal fragment in the nuclei has no β-sheet structures. Our present results indicated that 200 μM H 2 O 2 treatment induces the intranuclear accumulation of the C-terminal fragment of α-synuclein in dopaminergic neurons, whose role remains to be investigated

From the Cover: Harmane-Induced Selective Dopaminergic Neurotoxicity in Caenorhabditis elegans.

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Sammi, Shreesh Raj; Agim, Zeynep Sena; Cannon, Jason R

2018-02-01

Parkinson's disease (PD) is a debilitating neurodegenerative disease. Although numerous exposures have been linked to PD etiology, causative factors for most cases remain largely unknown. Emerging data on the neurotoxicity of heterocyclic amines suggest that this class of compounds should be examined for relevance to PD. Here, using Caenorhabditis elegans as a model system, we tested whether harmane exposure produced selective toxicity to dopamine neurons that is potentially relevant to PD. Harmane is a known tremorigenic β-carboline (a type of heterocyclic amine) found in cooked meat, roasted coffee beans, and tobacco. Thus, this compound represents a potentially important exposure. In the nematode model, we observed dopaminergic neurons to be selectively vulnerable, showing significant loss in terms of structure and function at lower doses than other neuronal populations. In examining mechanisms of toxicity, we observed significant harmane-induced decreases in mitochondrial viability and increased reactive oxygen species levels. Blocking transport through the dopamine transporter (DAT) was not neuroprotective, suggesting that harmane is unlikely to enter the cell through DAT. However, a mitochondrial complex I activator did partially ameliorate neurodegeneration. Further, mitochondrial complex I activator treatment reduced harmane-induced dopamine depletion, measured by the 1-nonanol assay. In summary, we have shown that harmane exposure in C. elegans produces selective dopaminergic neurotoxicity that may bear relevance to PD, and that neurotoxicity may be mediated through mitochondrial mechanisms. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Clinical Investigation of the Dopaminergic System with PET and FLUORINE-18-FLUORO-L-DOPA.

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Oakes, Terrence Rayford

1995-01-01

Positron Emission Tomography (PET) is a tool that provides quantitative physiological information. It is valuable both in a clinical environment, where information is sought for an individual, and in a research environment, to answer more fundamental questions about physiology and disease states. PET is particularly attractive compared to other nuclear medicine imaging techniques in cases where the anatomical regions of interest are small or when true metabolic rate constants are required. One example with both of these requirements is the investigation of Parkinson's Disease, which is characterized as a presynaptic motor function deficit affecting the striatum. As dopaminergic neurons die, the ability of the striatum to affect motor function decreases. The extent of functional neuronal damage in the small sub-structures may be ascertained by measuring the ability of the caudate and putamen to trap and store dopamine, a neurotransmitter. PET is able to utilize a tracer of dopamine activity, ^ {18}F- scL-DOPA, to quantitate the viability of the striatum. This thesis work deals with implementing and optimizing the many different elements that compose a PET study of the dopaminergic system, including: radioisotope production; conversion of aqueous ^{18}F ^-into [^ {18}F]-F2; synthesis of ^{18}F- scL -DOPA; details of the PET scan itself; measurements to estimate the radiation dosimetry; accurate measurement of a plasma input function; and the quantitation of dopaminergic activity in normal human subjects as well as in Parkinson's Disease patients.

Dysfunction of serotoninergic and dopaminergic neuronal systems in the antidepressant-resistant impairment of social behaviors induced by social defeat stress exposure as juveniles.

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Hasegawa, Sho; Miyake, Yuriko; Yoshimi, Akira; Mouri, Akihiro; Hida, Hirotake; Yamada, Kiyofumi; Ozaki, Norio; Nabeshima, Toshitaka; Noda, Yukihiro

2018-03-29

Extensive studies have been performed on the role of monoaminergic neuronal systems in rodents exposed to social defeat stress as adults. In the present study, we investigated the role of monoaminergic neuronal systems in the impairment of social behaviors induced by social defeat stress exposure as juveniles. Juvenile, male C57BL/6J mice were exposed to social defeat stress for 10 consecutive days. From 1 day after the last stress exposure, desipramine, sertraline, and aripiprazole, were administered for 15 days. Social behaviors were assessed at 1 and 15 days after the last stress exposure. Monoamine turnover was determined in specific regions of the brain in the mice exposed to the stress. Stress exposure as juveniles induced the impairment of social behaviors in adolescent mice. In mice that showed the impairment of social behaviors, turnover of the serotonin and dopamine, but not noradrenaline was decreased in specific brain regions. Acute and repeated administration of desipramine, sertraline, and aripiprazole failed to attenuate the impairment of social behaviors, whereas repeated administration of a combination of sertraline and aripiprazole showed additive attenuating effects. These findings suggest that social defeat stress exposure as juveniles induces the treatment-resistant impairment of social behaviors in adolescents through dysfunction in the serotoninergic and dopaminergic neuronal systems. The combination of sertraline and aripiprazole may be used as a new treatment strategy for treatment-resistant stress-related psychiatric disorders in adolescents with adverse juvenile experiences.

Targeting PERK signaling with the small molecule GSK2606414 prevents neurodegeneration in a model of Parkinson's disease.

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Mercado, Gabriela; Castillo, Valentina; Soto, Paulina; López, Nélida; Axten, Jeffrey M; Sardi, Sergio P; Hoozemans, Jeroen J M; Hetz, Claudio

2018-04-01

Parkinson's disease (PD) is the second most common neurodegenerative disorder, leading to the progressive decline of motor control due to the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Accumulating evidence suggest that altered proteostasis is a salient feature of PD, highlighting perturbations to the endoplasmic reticulum (ER), the main compartment involved in protein folding and secretion. PERK is a central ER stress sensor that enforces adaptive programs to recover homeostasis through a block of protein translation and the induction of the transcription factor ATF4. In addition, chronic PERK signaling results in apoptosis induction and neuronal dysfunction due to the repression in the translation of synaptic proteins. Here we confirmed the activation of PERK signaling in postmortem brain tissue derived from PD patients and three different rodent models of the disease. Pharmacological targeting of PERK by the oral administration of GSK2606414 demonstrated efficient inhibition of the pathway in the SNpc after experimental ER stress stimulation. GSK2606414 protected nigral-dopaminergic neurons against a PD-inducing neurotoxin, improving motor performance. The neuroprotective effects of PERK inhibition were accompanied by an increase in dopamine levels and the expression of synaptic proteins. However, GSK2606414 treated animals developed secondary effects possibly related to pancreatic toxicity. This study suggests that strategies to attenuate ER stress levels may be effective to reduce neurodegeneration in PD. Copyright © 2018 Elsevier Inc. All rights reserved.

High resolution quantitative element mapping of neuromelanin-containing neurons

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Reinert, Tilo [Nukleare Festkoerperphysik, Universitaet Leipzig, Linnestrasse 5, 04103 Leipzig (Germany)]. E-mail: reinert@physik.uni-leipzig.de; Fiedler, Anja [Nukleare Festkoerperphysik, Universitaet Leipzig, Linnestrasse 5, 04103 Leipzig (Germany); Paul-Flechsig-Institut fuer Hirnforschung, Universitaet Leipzig, Jahnallee 59, 04109 Leipzig (Germany); Morawski, Markus [Paul-Flechsig-Institut fuer Hirnforschung, Universitaet Leipzig, Jahnallee 59, 04109 Leipzig (Germany); Arendt, Thomas [Paul-Flechsig-Institut fuer Hirnforschung, Universitaet Leipzig, Jahnallee 59, 04109 Leipzig (Germany)

2007-07-15

Neuromelanin is a dark coloured intracellular pigment that appears in a specific population of neurons (dopaminergic and noradrenergic) predominantly in the substantia nigra and in the locus coeruleus. In recent years, there is increasing interest in the role of neuromelanin because of a hypothesised link between this pigment and the cell death of neuromelanin-containing neurons in Parkinson's disease (PD). Therefore, the role of neuromelanin in the pathology of PD is an actual focus in neuroscience. We have investigated the elemental contents and distributions of sulphur, calcium, iron, nickel and copper of neuromelanin in dopaminergic neurons for a Parkinson case and a control case (in situ, 6 {mu}m brain sections). There was no difference in the iron concentration between the two cases. However, the calcium concentration was 3-fold higher in the Parkinson case, whereas the copper and nickel concentrations decreased. An ultrastructural investigation of the concentrations of calcium and iron within the neuromelanin suggests that these two elements are not necessarily co-localized.

Expectancy-related changes in firing of dopamine neurons depend on orbitofrontal cortex.

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Takahashi, Yuji K; Roesch, Matthew R; Wilson, Robert C; Toreson, Kathy; O'Donnell, Patricio; Niv, Yael; Schoenbaum, Geoffrey

2011-10-30

The orbitofrontal cortex has been hypothesized to carry information regarding the value of expected rewards. Such information is essential for associative learning, which relies on comparisons between expected and obtained reward for generating instructive error signals. These error signals are thought to be conveyed by dopamine neurons. To test whether orbitofrontal cortex contributes to these error signals, we recorded from dopamine neurons in orbitofrontal-lesioned rats performing a reward learning task. Lesions caused marked changes in dopaminergic error signaling. However, the effect of lesions was not consistent with a simple loss of information regarding expected value. Instead, without orbitofrontal input, dopaminergic error signals failed to reflect internal information about the impending response that distinguished externally similar states leading to differently valued future rewards. These results are consistent with current conceptualizations of orbitofrontal cortex as supporting model-based behavior and suggest an unexpected role for this information in dopaminergic error signaling.

Morphine regulates Argonaute 2 and TH expression and activity but not miR-133b in midbrain dopaminergic neurons.

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García-Pérez, Daniel; López-Bellido, Roger; Hidalgo, Juana M; Rodríguez, Raquel E; Laorden, Maria Luisa; Núñez, Cristina; Milanés, Maria Victoria

2015-01-01

Epigenetic changes such as microRNAs (miRs)/Ago2-induced gene silencing represent complex molecular signature that regulate cellular plasticity. Recent studies showed involvement of miRs and Ago2 in drug addiction. In this study, we show that changes in gene expression induced by morphine and morphine withdrawal occur with concomitant epigenetic modifications in the mesolimbic dopaminergic (DA) pathway [ventral tegmental area (VTA)/nucleus accumbens (NAc) shell], which is critically involved in drug-induced dependence. We found that acute or chronic morphine administration as well as morphine withdrawal did not modify miR-133b messenger RNA (mRNA) expression in the VTA, whereas Ago2 protein levels were decreased and increased in morphine-dependent rats and after morphine withdrawal, respectively. These changes were paralleled with enhanced and decreased NAc tyrosine hydroxylase (TH) protein (an early DA marker) in morphine-dependent rats and after withdrawal, respectively. We also observed changes in TH mRNA expression in the VTA that could be related to Ago2-induced translational repression of TH mRNA during morphine withdrawal. However, the VTA number of TH-positive neurons suffered no alterations after the different treatment. Acute morphine administration produced a marked increase in TH activity and DA turnover in the NAc (shell). In contrast, precipitated morphine withdrawal decreased TH activation and did not change DA turnover. These findings provide new information into the possible correlation between Ago2/miRs complex regulation and DA neurons plasticity during opiate addiction. © 2013 Society for the Study of Addiction.

Pacemaker rate and depolarization block in nigral dopamine neurons: a somatic sodium channel balancing act

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Tucker, Kristal R.; Huertas, Marco A.; Horn, John P.; Canavier, Carmen C.; Levitan, Edwin S.

2012-01-01

Midbrain dopamine (DA) neurons are slow intrinsic pacemakers that undergo depolarization (DP) block upon moderate stimulation. Understanding DP block is important because it has been correlated with the clinical efficacy of chronic antipsychotic drug treatment. Here we describe how voltage-gated sodium (NaV) channels regulate DP block and pacemaker activity in DA neurons of the substantia nigra using rat brain slices. The distribution, density and gating of NaV currents were manipulated by blocking native channels with tetrodotoxin and by creating virtual channels and anti-channels with dynamic clamp. Although action potentials initiate in the axon initial segment (AIS) and NaV channels are distributed in multiple dendrites, selective reduction of NaV channel activity in the soma was sufficient to decrease pacemaker frequency and increase susceptibility to DP block. Conversely, increasing somatic NaV current density raised pacemaker frequency and lowered susceptibility to DP block. Finally, when NaV currents were restricted to the soma, pacemaker activity occurred at abnormally high rates due to excessive local subthreshold NaV current. Together with computational simulations, these data show that both the slow pacemaker rate and the sensitivity to DP block that characterizes DA neurons result from the low density of somatic NaV channels. More generally, we conclude that the somatodendritic distribution of NaV channels is a major determinant of repetitive spiking frequency. PMID:23077037

Reduced striatal dopamine DA D2 receptor function in dominant-negative GSK-3 transgenic mice.

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Gomez-Sintes, Raquel; Bortolozzi, Analia; Artigas, Francesc; Lucas, José J

2014-09-01

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase with constitutive activity involved in cellular architecture, gene expression, cell proliferation, fate decision and apoptosis, among others. GSK-3 expression is particularly high in brain where it may be involved in neurological and psychiatric disorders such as Alzheimer׳s disease, bipolar disorder and major depression. A link with schizophrenia is suggested by the antipsychotic drug-induced GSK-3 regulation and by the involvement of the Akt/GSK-3 pathway in dopaminergic neurotransmission. Taking advantage of the previous development of dominant negative GSK-3 transgenic mice (Tg) showing a selective reduction of GSK-3 activity in forebrain neurons but not in dopaminergic neurons, we explored the relationship between GSK-3 and dopaminergic neurotransmission in vivo. In microdialysis experiments, local quinpirole (DA D2-R agonist) in dorsal striatum reduced dopamine (DA) release significantly less in Tg mice than in wild-type (WT) mice. However, local SKF-81297 (selective DA D1-R agonist) in dorsal striatum reduced DA release equally in both control and Tg mice indicating a comparable function of DA D1-R in the direct striato-nigral pathway. Likewise, systemic quinpirole administration - acting preferentially on presynaptic DA D2- autoreceptors to modulate DA release-reduced striatal DA release similarly in both control and Tg mice. Quinpirole reduced locomotor activity and induced c-fos expression in globus pallidus (both striatal DA D2-R-mediated effects) significantly more in WT than in Tg mice. Taking together, the present results show that dominant negative GSK-3 transgenic mice show reduced DA D2-R-mediated function in striatum and further support a link between dopaminergic neurotransmission and GSK-3 activity. Copyright © 2014 Elsevier B.V. and ECNP. All rights reserved.

Neurotrophic effects of growth/differentiation factor 5 in a neuronal cell line.

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Toulouse, André; Collins, Grace C; Sullivan, Aideen M

2012-04-01

The neurotrophin growth/differentiation factor 5 (GDF5) is studied as a potential therapeutic agent for Parkinson's disease as it is believed to play a role in the development and maintenance of the nigrostriatal system. Progress in understanding the effects of GDF5 on dopaminergic neurones has been hindered by the use of mixed cell populations derived from primary cultures or in vivo experiments, making it difficult to differentiate between direct and indirect effects of GDF5 treatment on neurones. In an attempt to establish an useful model to study the direct neuronal influence of GDF5, we have characterised the effects of GDF5 on a human neuronal cell line, SH-SY5Y. Our results show that GDF5 has the capability to promote neuronal but not dopaminergic differentiation. We also show that it promotes neuronal survival in vitro following a 6-hydroxydopamine insult. Our results show that application of GDF5 to SH-SY5Y cultures induces the SMAD pathway which could potentially be implicated in the intracellular transmission of GDF5's neurotrophic effects. Overall, our study shows that the SH-SY5Y neuroblastoma cell line provides an excellent neuronal model to study the neurotrophic effects of GDF5.

Zebrafish GDNF and its co-receptor GFRα1 activate the human RET receptor and promote the survival of dopaminergic neurons in vitro.

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Tuulia Saarenpää

Full Text Available Glial cell line-derived neurotrophic factor (GDNF is a ligand that activates, through co-receptor GDNF family receptor alpha-1 (GFRα1 and receptor tyrosine kinase "RET", several signaling pathways crucial in the development and sustainment of multiple neuronal populations. We decided to study whether non-mammalian orthologs of these three proteins have conserved their function: can they activate the human counterparts? Using the baculovirus expression system, we expressed and purified Danio rerio RET, and its binding partners GFRα1 and GDNF, and Drosophila melanogaster RET and two isoforms of co-receptor GDNF receptor-like. Our results report high-level insect cell expression of post-translationally modified and dimerized zebrafish RET and its binding partners. We also found that zebrafish GFRα1 and GDNF are comparably active as mammalian cell-produced ones. We also report the first measurements of the affinity of the complex to RET in solution: at least for zebrafish, the Kd for GFRα1-GDNF binding RET is 5.9 μM. Surprisingly, we also found that zebrafish GDNF as well as zebrafish GFRα1 robustly activated human RET signaling and promoted the survival of cultured mouse dopaminergic neurons with comparable efficiency to mammalian GDNF, unlike E. coli-produced human proteins. These results contradict previous studies suggesting that mammalian GFRα1 and GDNF cannot bind and activate non-mammalian RET and vice versa.

The role of metallothionein II in neuronal differentiation and survival

DEFF Research Database (Denmark)

Køhler, Lene B; Berezin, Vladimir; Bock, Elisabeth

2003-01-01

-I+II can affect neurons directly. It is likely that MT isoforms could be beneficial also during neurodegenerative disorders. In this study, we have examined if MT-II affects survival and neurite extension of dopaminergic and hippocampal neurons. We show for the first time that MT-II treatment can....... Accordingly, treatment with MT-II may be of therapeutic value in neurodegenerative disorders....

Adult rat bone marrow stromal cells express genes associated with dopamine neurons

International Nuclear Information System (INIS)

Kramer, Brian C.; Woodbury, Dale; Black, Ira B.

2006-01-01

An intensive search is underway to identify candidates to replace the cells that degenerate in Parkinson's disease (PD). To date, no suitable substitute has been found. We have recently found that adult rat bone marrow stromal cells (MSCs) can be induced to assume a neuronal phenotype in vitro. These findings may have particular relevance to the treatment of PD. We now report that adult MSCs express multiple dopaminergic genes, suggesting that they are potential candidates for cell therapy. Using RT-PCR, we have examined families of genes that are associated with the development and/or survival of dopaminergic neurons. MSCs transcribe a variety of dopaminergic genes including patched and smoothened (components of the Shh receptor), Gli-1 (downstream mediator of Shh), and Otx-1, a gene associated with formation of the mesencephalon during development. Furthermore, Shh treatment elicits a 1.5-fold increase in DNA synthesis in cultured MSCs, suggesting the presence of a functional Shh receptor complex. We have also found that MSCs transcribe and translate Nurr-1, a nuclear receptor essential for the development of dopamine neurons. In addition, MSCs express a variety of growth factor receptors including the glycosyl-phosphatidylinositol-anchored ligand-binding subunit of the GDNF receptor, GFRα1, as well as fibroblast growth factor receptors one and four. The expression of genes that are associated with the development and survival of dopamine neurons suggests a potential role for these cells in the treatment of Parkinson's disease

Chronic stress triggers social aversion via glucocorticoid receptor in dopaminoceptive neurons.

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Barik, Jacques; Marti, Fabio; Morel, Carole; Fernandez, Sebastian P; Lanteri, Christophe; Godeheu, Gérard; Tassin, Jean-Pol; Mombereau, Cédric; Faure, Philippe; Tronche, François

2013-01-18

Repeated traumatic events induce long-lasting behavioral changes that are key to organism adaptation and that affect cognitive, emotional, and social behaviors. Rodents subjected to repeated instances of aggression develop enduring social aversion and increased anxiety. Such repeated aggressions trigger a stress response, resulting in glucocorticoid release and activation of the ascending dopamine (DA) system. We bred mice with selective inactivation of the gene encoding the glucocorticoid receptor (GR) along the DA pathway, and exposed them to repeated aggressions. GR in dopaminoceptive but not DA-releasing neurons specifically promoted social aversion as well as dopaminergic neurochemical and electrophysiological neuroadaptations. Anxiety and fear memories remained unaffected. Acute inhibition of the activity of DA-releasing neurons fully restored social interaction in socially defeated wild-type mice. Our data suggest a GR-dependent neuronal dichotomy for the regulation of emotional and social behaviors, and clearly implicate GR as a link between stress resiliency and dopaminergic tone.

Active and passive sexual roles that arise in Drosophila male-male courtship are modulated by dopamine levels in PPL2ab neurons

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Shiu-Ling Chen; Yu-Hui Chen; Chuan-Chan Wang; Yhu-Wei Yu; Yu-Chen Tsai; Hsiao-Wen Hsu; Chia-Lin Wu; Pei-Yu Wang; Lien-Cheng Chen; Tsuo-Hung Lan; Tsai-Feng Fu

2017-01-01

The neurology of male sexuality has been poorly studied owing to difficulties in studying brain circuitry in humans. Dopamine (DA) is essential for both physiological and behavioural responses, including the regulation of sexuality. Previous studies have revealed that alterations in DA synthesis in dopaminergic neurons can induce male-male courtship behaviour, while increasing DA levels in the protocerebral posteriolateral dopaminergic cluster neuron 2ab (PPL2ab) may enhance the intensity of ...

A well-refined in vitro model derived from human embryonic stem cell for screening phytochemicals with midbrain dopaminergic differentiation-boosting potential for improving Parkinson's disease.

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Hsieh, Wen-Ting; Chiang, Been-Huang

2014-07-09

Stimulation of endogenous neurogenesis is a potential approach to compensate for loss of dopaminergic neurons of substantia nigra compacta nigra (SNpc) in patients with Parkinson's disease (PD). This objective was to establish an in vitro model by differentiating pluripotent human embryonic stem cells (hESCs) into midbrain dopaminergic (mDA) neurons for screening phytochemicals with mDA neurogenesis-boosting potentials. Consequently, a five-stage differentiation process was developed. The derived cells expressed many mDA markers including tyrosine hydroxylase (TH), β-III tubulin, and dopamine transporter (DAT). The voltage-gated ion channels and dopamine release were also examined for verifying neuron function, and the dopamine receptor agonists bromocriptine and 7-hydroxy-2-(dipropylamino)tetralin (7-OH-DPAT) were used to validate our model. Then, several potential phytochemicals including green tea catechins and ginsenosides were tested using the model. Finally, ginsenoside Rb1 was identified as the most potent phytochemical which is capable of upregulating neurotrophin expression and inducing mDA differentiation.

Neuroprotective effect of curcumin-I in copper-induced dopaminergic neurotoxicity in rats: A possible link with Parkinson's disease.

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Abbaoui, Abdellatif; Chatoui, Hicham; El Hiba, Omar; Gamrani, Halima

2017-11-01

Numerous findings indicate an involvement of heavy metals in the neuropathology of several neurodegenerative disorders, especially Parkinson's disease (PD). Previous studies have demonstrated that Copper (Cu) exhibits a potent neurotoxic effect on dopaminergic neurons and triggers profound neurobehavioral alterations. Curcumin is a major component of Curcuma longa rhizomes and a powerful medicinal plant that exerts many pharmacological effects. However, the neuroprotective action of curcumin on Cu-induced dopaminergic neurotoxicity is yet to be investigated. The aim of the present study was to evaluate the impact of acute Cu-intoxication (10mg/kg B.W. i.p) for 3days on the dopaminergic system and locomotor performance as well as the possible therapeutic efficacy of curcumin I (30mg/kg B.W.). Intoxicated rats showed a significant loss of Tyrosine Hydroxylase (TH) expression within substantia nigra pars compacta (SNc), ventral tegmental area (VTA) and the striatal outputs. This was correlated with a clear decrease in locomotor performance. Critically, curcumin-I co-treatment reversed these changes and showed a noticeable protective effect; both TH expression and locomotor performance was reinstated in intoxicated rats. These results demonstrate altered dopaminergic innervations following Cu intoxication and a new therapeutic potential of curcumin against Cu-induced dopaminergic neurotransmission failure. Curcumin may therefore prevent heavy metal related Parkinsonism. Copyright © 2017 Elsevier B.V. All rights reserved.

Peripheral Inflammation Increases the Damage in Animal Models of Nigrostriatal Dopaminergic Neurodegeneration: Possible Implication in Parkinson's Disease Incidence

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A. Machado

2011-01-01

Full Text Available Inflammatory processes described in Parkinson’s disease (PD and its animal models appear to be important in the progression of the pathogenesis, or even a triggering factor. Here we review that peripheral inflammation enhances the degeneration of the nigrostriatal dopaminergic system induced by different insults; different peripheral inflammations have been used, such as IL-1β and the ulcerative colitis model, as well as insults to the dopaminergic system such as 6-hydroxydopamine or lipopolysaccharide. In all cases, an increased loss of dopaminergic neurons was described; inflammation in the substantia nigra increased, displaying a great activation of microglia along with an increase in the production of cytokines such as IL-1β and TNF-α. Increased permeability or disruption of the BBB, with overexpression of the ICAM-1 adhesion molecule and infiltration of circulating monocytes into the substantia nigra, is also involved, since the depletion of circulating monocytes prevents the effects of peripheral inflammation. Data are reviewed in relation to epidemiological studies of PD.

Caloric Restriction Protects against Lactacystin-Induced Degeneration of Dopamine Neurons Independent of the Ghrelin Receptor

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Jessica Coppens

2017-03-01

Full Text Available Parkinson’s disease (PD is a neurodegenerative disorder, characterized by a loss of dopamine (DA neurons in the substantia nigra pars compacta (SNc. Caloric restriction (CR has been shown to exert ghrelin-dependent neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP-based animal model for PD. We here investigated whether CR is neuroprotective in the lactacystin (LAC mouse model for PD, in which proteasome disruption leads to the destruction of the DA neurons of the SNc, and whether this effect is mediated via the ghrelin receptor. Adult male ghrelin receptor wildtype (WT and knockout (KO mice were maintained on an ad libitum (AL diet or on a 30% CR regimen. After 3 weeks, LAC was injected unilaterally into the SNc, and the degree of DA neuron degeneration was evaluated 1 week later. In AL mice, LAC injection significanty reduced the number of DA neurons and striatal DA concentrations. CR protected against DA neuron degeneration following LAC injection. However, no differences were observed between ghrelin receptor WT and KO mice. These results indicate that CR can protect the nigral DA neurons from toxicity related to proteasome disruption; however, the ghrelin receptor is not involved in this effect.

Sexually dimorphic activation of dopaminergic areas depends on affiliation during courtship and pair formation

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Mai eIwasaki

2014-06-01

Full Text Available For many species, dyadic interaction during courtship and pair bonding engage intense emotional states that control approach or avoidance behavior. Previous studies have shown that one component of a common social brain network (SBN, dopaminergic areas, are highly engaged during male songbird courtship of females. We tested whether the level of activity in dopaminergic systems of both females and males during courtship is related to their level of affiliation. In order to objectively quantify affiliative behaviors, we developed a system for tracking the position of both birds during free interaction sessions. During a third successive daily interaction session, there was a range of levels of affiliation among bird pairs, as quantified by several position and movement parameters. Because both positive and negative social interactions were present, we chose to characterize affiliation strength by pair valence. As a potential neural system involved in regulating pair valence, the level of activity of the dopaminergic group A11 (within the central gray was selectively reduced in females of positive valence pairs. Further, activation of non-dopaminergic neurons in VTA was negatively related to valence, with this relationship strongest in ventral VTA of females. Together, these results suggest that inhibition of fear or avoidance networks may be associated with development of close affiliation, and highlight the importance of negative as well as positive emotional states in the process of courtship, and in development of long-lasting social bonds.

Increased Fos expression among midbrain dopaminergic cell groups during birdsong tutoring.

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Nordeen, E J; Holtzman, D A; Nordeen, K W

2009-08-01

During avian vocal learning, birds memorize conspecific song patterns and then use auditory feedback to match their vocal output to this acquired template. Some models of song learning posit that during tutoring, conspecific visual, social and/or auditory cues activate neuromodulatory systems that encourage acquisition of the tutor's song and attach incentive value to that specific acoustic pattern. This hypothesis predicts that stimuli experienced during social tutoring activate cell populations capable of signaling reward. Using immunocytochemistry for the protein product of the immediate early gene c-Fos, we found that brief exposure of juvenile male zebra finches to a live familiar male tutor increased the density of Fos+ cells within two brain regions implicated in reward processing: the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). This activation of Fos appears to involve both dopaminergic and non-dopaminergic VTA/SNc neurons. Intriguingly, a familiar tutor was more effective than a novel tutor in stimulating Fos expression within these regions. In the periaqueductal gray, a dopamine-enriched cell population that has been implicated in emotional processing, Fos labeling also was increased after tutoring, with a familiar tutor again being more effective than a novel conspecific. As several neural regions implicated in song acquisition receive strong dopaminergic projections from these midbrain nuclei, their activation in conjunction with hearing the tutor's song could help to establish sensory representations that later guide motor sequence learning.

Effect of crowding, temperature and age on glia activation and dopaminergic neurotoxicity induced by MDMA in the mouse brain.

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Frau, Lucia; Simola, Nicola; Porceddu, Pier Francesca; Morelli, Micaela

2016-09-01

3,4-methylenedyoxymethamphetamine (MDMA or "ecstasy"), a recreational drug of abuse, can induce glia activation and dopaminergic neurotoxicity. Since MDMA is often consumed in crowded environments featuring high temperatures, we studied how these factors influenced glia activation and dopaminergic neurotoxicity induced by MDMA. C57BL/6J adolescent (4 weeks old) and adult (12 weeks old) mice received MDMA (4×20mg/kg) in different conditions: 1) while kept 1, 5, or 10×cage at room temperature (21°C); 2) while kept 5×cage at either room (21°C) or high (27°C) temperature. After the last MDMA administration, immunohistochemistry was performed in the caudate-putamen for CD11b and GFAP, to mark microglia and astroglia, and in the substantia nigra pars compacta for tyrosine hydroxylase, to mark dopaminergic neurons. MDMA induced glia activation and dopaminergic neurotoxicity, compared with vehicle administration. Crowding (5 or 10 mice×cage) amplified MDMA-induced glia activation (in adult and adolescent mice) and dopaminergic neurotoxicity (in adolescent mice). Conversely, exposure to a high environmental temperature (27°C) potentiated MDMA-induced glia activation in adult and adolescent mice kept 5×cage, but not dopaminergic neurotoxicity. Crowding and exposure to a high environmental temperature amplified MDMA-induced hyperthermia, and a positive correlation between body temperature and activation of either microglia or astroglia was found in adult and adolescent mice. These results provide further evidence that the administration setting influences the noxious effects of MDMA in the mouse brain. However, while crowding amplifies both glia activation and dopaminergic neurotoxicity, a high environmental temperature exacerbates glia activation only. Copyright © 2016 Elsevier B.V. All rights reserved.

Gender-specific role of mitochondria in the vulnerability of 6-hydroxydopamine-treated mesencephalic neurons.

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Misiak, Magdalena; Beyer, Cordian; Arnold, Susanne

2010-01-01

Many neurodegenerative diseases, such as Morbus Parkinson, exhibit a gender-dependency showing a higher incidence in men than women. Most of the neurodegenerative disorders involve either causally or consequently a dysfunction of mitochondria. Therefore, neuronal mitochondria may demonstrate a gender-specificity with respect to structural and functional characteristics of these organelles during toxic and degenerative processes. The application of 6-OHDA (6-hydroxydopamine) in vitro and in vivo represents a well-accepted experimental model of Parkinson's disease causing Parkinsonian symptoms. Besides the known effects of 6-OHDA on mitochondria and neuronal survivability, we aimed to demonstrate that the mitochondrial neurotoxin affects the morphology and survival of primary dopaminergic and non-dopaminergic neurons in the mesencephalon in a gender-specific manner by influencing the transcription of mitochondrial genes, ATP and reactive oxygen species production. Our data suggest that cell death in response to 6-OHDA is primarily caused due to increased oxidative stress which is more pronounced in male than in female mesencephalic neurons. Copyright © 2010 Elsevier B.V. All rights reserved.

Opioid receptors in midbrain dopaminergic regions of the rat. 1. Mu receptor autoradiography

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German, D.C.; Speciale, S.G.; Manaye, K.F.; Sadeq, M.

1993-01-01

Several lines of evidence indicate that an interaction exists between opioid peptides and midbrain dopaminergic neurons. The purpose of this study was to map and quantify the density of the mu opioid receptor subtype relative to the location of the dopaminergic (DA) neurons in the retrorubral field (nucleus A8), substantia nigra (nucleus A9), and ventral tegmental area and related nuclei (nucleus A10) in the rat. Sections through the rostral-caudal extent of the midbrain were stained with an antibody against tyrosine hydroxylase, as a DA cell marker, and comparable sections were processed for in vitro receptor autoradiography using the mu-selective ligand, 3 H-Tyr-D-Ala-N-MePhe-Gyl-ol enkephalin. In the nucleus A8 region, there were low levels of mu binding. In the rostral portion of nucleus A9, there was prominent mu binding both in the ventral pars compacta, which contains numerous DA neurons, and in regions that correspond to the location of the DA dendrites which project ventrally into the underlying substantia nigra pars reticulata. In the caudal portion of nucleus A9, mu binding was greatest in the substantia nigra pars reticulata, but also in the same region that contains DA neurons. In nucleus A10, mu receptor densities differed depending upon the nucleus A10 subdivision, and the rostral-caudal position in the nucleus. Low receptor densities were observed in rostral portions of the ventral tegmental area and interfascicular nucleus, and there was negligible binding in the parabrachial pigmented nucleus and paranigral nucleus at the level of the interpeduncular nucleus; all regions where there are high densities of DA somata. Mu binding was relatively high in the central linear nucleus, and in the dorsal and medial divisions of the medial terminal nucleus of the accessory optic system, which has been shown to contain DA dendrites. These data indicate that mu opioid receptors are located in certain regions occupied by all three midbrain DA nuclei, but in a

Dopaminergic control of motivation and reinforcement learning: a closed-circuit account for reward-oriented behavior.

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Morita, Kenji; Morishima, Mieko; Sakai, Katsuyuki; Kawaguchi, Yasuo

2013-05-15

Humans and animals take actions quickly when they expect that the actions lead to reward, reflecting their motivation. Injection of dopamine receptor antagonists into the striatum has been shown to slow such reward-seeking behavior, suggesting that dopamine is involved in the control of motivational processes. Meanwhile, neurophysiological studies have revealed that phasic response of dopamine neurons appears to represent reward prediction error, indicating that dopamine plays central roles in reinforcement learning. However, previous attempts to elucidate the mechanisms of these dopaminergic controls have not fully explained how the motivational and learning aspects are related and whether they can be understood by the way the activity of dopamine neurons itself is controlled by their upstream circuitries. To address this issue, we constructed a closed-circuit model of the corticobasal ganglia system based on recent findings regarding intracortical and corticostriatal circuit architectures. Simulations show that the model could reproduce the observed distinct motivational effects of D1- and D2-type dopamine receptor antagonists. Simultaneously, our model successfully explains the dopaminergic representation of reward prediction error as observed in behaving animals during learning tasks and could also explain distinct choice biases induced by optogenetic stimulation of the D1 and D2 receptor-expressing striatal neurons. These results indicate that the suggested roles of dopamine in motivational control and reinforcement learning can be understood in a unified manner through a notion that the indirect pathway of the basal ganglia represents the value of states/actions at a previous time point, an empirically driven key assumption of our model.

Intrinsic and integrative properties of substantia nigra pars reticulata neurons

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Zhou, Fu-Ming; Lee, Christian R.

2011-01-01

The GABA projection neurons of the substantia nigra pars reticulata (SNr) are output neurons for the basal ganglia and thus critical for movement control. Their most striking neurophysiological feature is sustained, spontaneous high frequency spike firing. A fundamental question is: what are the key ion channels supporting the remarkable firing capability in these neurons? Recent studies indicate that these neurons express tonically active TRPC3 channels that conduct a Na-dependent inward current even at hyperpolarized membrane potentials. When the membrane potential reaches −60 mV, a voltage-gated persistent sodium current (INaP) starts to activate, further depolarizing the membrane potential. At or slightly below −50 mV, the large transient voltage-activated sodium current (INaT) starts to activate and eventually triggers the rapid rising phase of action potentials. SNr GABA neurons have a higher density of (INaT), contributing to the faster rise and larger amplitude of action potentials, compared with the slow-spiking dopamine neurons. INaT also recovers from inactivation more quickly in SNr GABA neurons than in nigral dopamine neurons. In SNr GABA neurons, the rising phase of the action potential triggers the activation of high-threshold, inactivation-resistant Kv3-like channels that can rapidly repolarize the membrane. These intrinsic ion channels provide SNr GABA neurons with the ability to fire spontaneous and sustained high frequency spikes. Additionally, robust GABA inputs from direct pathway medium spiny neurons in the striatum and GABA neurons in the globus pallidus may inhibit and silence SNr GABA neurons, whereas glutamate synaptic input from the subthalamic nucleus may induce burst firing in SNr GABA neurons. Thus, afferent GABA and glutamate synaptic inputs sculpt the tonic high frequency firing of SNr GABA neurons and the consequent inhibition of their targets into an integrated motor control signal that is further fine-tuned by neuromodulators

Chronic levodopa administration followed by a washout period increased number and induced phenotypic changes in striatal dopaminergic cells in MPTP-monkeys.

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Carla DiCaudo

Full Text Available In addition to the medium spiny neurons the mammalian striatum contains a small population of GABAergic interneurons that are immunoreactive for tyrosine hydroxylase (TH, which dramatically increases after lesions to the nigrostriatal pathway and striatal delivery of neurotrophic factors. The regulatory effect of levodopa (L-Dopa on the number and phenotype of these cells is less well understood. Eleven macaques (Macaca fascicularis were included. Group I (n = 4 received 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP and L-Dopa; Group II (n = 4 was treated with MPTP plus vehicle and Group III (n = 3 consist of intact animals (control group. L-Dopa and vehicle were given for 1 year and animals sacrificed 6 months later. Immunohistochemistry against TH was used to identify striatal and nigral dopaminergic cells. Double and triple labeling immunofluorescence was performed to detect the neurochemical characteristics of the striatal TH-ir cells using antibodies against: TH, anti-glutamate decarboxylase (GAD(67 anti-calretinin (CR anti-dopa decarboxylase (DDC and anti-dopamine and cyclic AMP-regulated phosphoprotein (DARPP-32. The greatest density of TH-ir striatal cells was detected in the striatum of the L-Dopa treated monkeys and particularly in its associative territory. None of the striatal TH-ir cell expressed DARPP-32 indicating they are interneurons. The percentages of TH-ir cells that expressed GAD67 and DDC was approximately 50%. Interestingly, we found that in the L-Dopa group the number of TH/CR expressing cells was significantly reduced. We conclude that chronic L-Dopa administration produced a long-lasting increase in the number of TH-ir cells, even after a washout period of 6 months. L-Dopa also modified the phenotype of these cells with a significant reduction of the TH/CR phenotype in favor of an increased number of TH/GAD cells that do not express CR. We suggest that the increased number of striatal TH-ir cells might be involved

Protein Kinase Pathways That Regulate Neuronal Survival and Death

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2004-08-01

The neurotrophic effects of 2. Apostolides, C., E. Sanford, M. Hong, and 1. Mendez . 1998. Glial fibroblast growth factors on dopaminergic neurons in...Vaudry D, Falluel-Morel A, Leuillet S, Vaudry H, Gonzalez B) (2003) Reg- Martinez-Murillo R, Caro L, Nieto-Sampedro M (1993) Lesion-induced ulators

Noradrenaline and dopamine neurons in the reward/effort trade-off: a direct electrophysiological comparison in behaving monkeys.

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Varazzani, Chiara; San-Galli, Aurore; Gilardeau, Sophie; Bouret, Sebastien

2015-05-20

Motivation determines multiple aspects of behavior, including action selection and energization of behavior. Several components of the underlying neural systems have been examined closely, but the specific role of the different neuromodulatory systems in motivation remains unclear. Here, we compare directly the activity of dopaminergic neurons from the substantia nigra pars compacta and noradrenergic neurons from the locus coeruleus in monkeys performing a task manipulating the reward/effort trade-off. Consistent with previous reports, dopaminergic neurons encoded the expected reward, but we found that they also anticipated the upcoming effort cost in connection with its negative influence on action selection. Conversely, the firing of noradrenergic neurons increased with both pupil dilation and effort production in relation to the energization of behavior. Therefore, this work underlines the contribution of dopamine to effort-based decision making and uncovers a specific role of noradrenaline in energizing behavior to face challenges. Copyright © 2015 the authors 0270-6474/15/357866-12$15.00/0.

Involvment of cytosolic and mitochondrial GSK-3beta in mitochondrial dysfunction and neuronal cell death of MPTP/MPP-treated neurons.

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Agnès Petit-Paitel

Full Text Available Aberrant mitochondrial function appears to play a central role in dopaminergic neuronal loss in Parkinson's disease (PD. 1-methyl-4-phenylpyridinium iodide (MPP(+, the active metabolite of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, is a selective inhibitor of mitochondrial complex I and is widely used in rodent and cell models to elicit neurochemical alterations associated with PD. Recent findings suggest that Glycogen Synthase Kinase-3beta (GSK-3beta, a critical activator of neuronal apoptosis, is involved in the dopaminergic cell death. In this study, the role of GSK-3beta in modulating MPP(+-induced mitochondrial dysfunction and neuronal death was examined in vivo, and in two neuronal cell models namely primary cultured and immortalized neurons. In both cell models, MPTP/MPP(+ treatment caused cell death associated with time- and concentration-dependent activation of GSK-3beta, evidenced by the increased level of the active form of the kinase, i.e. GSK-3beta phosphorylated at tyrosine 216 residue. Using immunocytochemistry and subcellular fractionation techniques, we showed that GSK-3beta partially localized within mitochondria in both neuronal cell models. Moreover, MPP(+ treatment induced a significant decrease of the specific phospho-Tyr216-GSK-3beta labeling in mitochondria concomitantly with an increase into the cytosol. Using two distinct fluorescent probes, we showed that MPP(+ induced cell death through the depolarization of mitochondrial membrane potential. Inhibition of GSK-3beta activity using well-characterized inhibitors, LiCl and kenpaullone, and RNA interference, prevented MPP(+-induced cell death by blocking mitochondrial membrane potential changes and subsequent caspase-9 and -3 activation. These results indicate that GSK-3beta is a critical mediator of MPTP/MPP(+-induced neurotoxicity through its ability to regulate mitochondrial functions. Inhibition of GSK-3beta activity might provide protection against

Isolation of Human Induced Pluripotent Stem Cell-Derived Dopaminergic Progenitors by Cell Sorting for Successful Transplantation

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Daisuke Doi

2014-03-01

Full Text Available Human induced pluripotent stem cells (iPSCs can provide a promising source of midbrain dopaminergic (DA neurons for cell replacement therapy for Parkinson’s disease. However, iPSC-derived donor cells inevitably contain tumorigenic or inappropriate cells. Here, we show that human iPSC-derived DA progenitor cells can be efficiently isolated by cell sorting using a floor plate marker, CORIN. We induced DA neurons using scalable culture conditions on human laminin fragment, and the sorted CORIN+ cells expressed the midbrain DA progenitor markers, FOXA2 and LMX1A. When transplanted into 6-OHDA-lesioned rats, the CORIN+ cells survived and differentiated into midbrain DA neurons in vivo, resulting in significant improvement of the motor behavior, without tumor formation. In particular, the CORIN+ cells in a NURR1+ cell-dominant stage exhibited the best survival and function as DA neurons. Our method is a favorable strategy in terms of scalability, safety, and efficiency and may be advantageous for clinical application.

Enhanced proliferation and dopaminergic differentiation of ventral mesencephalic precursor cells by synergistic effect of FGF2 and reduced oxygen tension

DEFF Research Database (Denmark)

Jensen, Pia; Gramsbergen, Jan-Bert; Zimmer, Jens

2011-01-01

Effective numerical expansion of dopaminergic precursors might overcome the limited availability of transplantable cells in replacement strategies for Parkinson's disease. Here we investigated the effect of fibroblast growth factor-2 (FGF2) and FGF8 on expansion and dopaminergic differentiation o...... enzyme activity, which may explain the elevated dopamine levels. Our findings demonstrate that modulation of oxygen tension is a recognizable factor for in vitro expansion and dopaminergic differentiation of rat embryonic midbrain precursor cells....... of rat embryonic ventral mesencephalic neuroblasts cultured at high (20%) and low (3%) oxygen tension. More cells incorporated bromodeoxyuridine in cultures expanded at low as compared to high oxygen tension, and after 6 days of differentiation there were significantly more neuronal cells in low than......, switching FGF2-expanded cultures from low to high oxygen tension during the last two days of differentiation significantly enhanced dopamine release and intracellular dopamine levels as compared to all other treatment groups. In addition, the short-term exposure to high oxygen enhanced in situ assessed TH...

Αlpha-Synuclein as a Mediator in the Interplay between Aging and Parkinson’s Disease

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Wojciech Bobela

2015-10-01

Full Text Available Accumulation and misfolding of the alpha-synuclein protein are core mechanisms in the pathogenesis of Parkinson’s disease. While the normal function of alpha-synuclein is mainly related to the control of vesicular neurotransmission, its pathogenic effects are linked to various cellular functions, which include mitochondrial activity, as well as proteasome and autophagic degradation of proteins. Remarkably, these functions are also affected when the renewal of macromolecules and organelles becomes impaired during the normal aging process. As aging is considered a major risk factor for Parkinson’s disease, it is critical to explore its molecular and cellular implications in the context of the alpha-synuclein pathology. Here, we discuss similarities and differences between normal brain aging and Parkinson’s disease, with a particular emphasis on the nigral dopaminergic neurons, which appear to be selectively vulnerable to the combined effects of alpha-synuclein and aging.

Comparison of gene expression profile in embryonic mesencephalon and neuronal primary cultures.

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Dario Greco

Full Text Available In the mammalian central nervous system (CNS an important contingent of dopaminergic neurons are localized in the substantia nigra and in the ventral tegmental area of the ventral midbrain. They constitute an anatomically and functionally heterogeneous group of cells involved in a variety of regulatory mechanisms, from locomotion to emotional/motivational behavior. Midbrain dopaminergic neuron (mDA primary cultures represent a useful tool to study molecular mechanisms involved in their development and maintenance. Considerable information has been gathered on the mDA neurons development and maturation in vivo, as well as on the molecular features of mDA primary cultures. Here we investigated in detail the gene expression differences between the tissue of origin and ventral midbrain primary cultures enriched in mDA neurons, using microarray technique. We integrated the results based on different re-annotations of the microarray probes. By using knowledge-based gene network techniques and promoter sequence analysis, we also uncovered mechanisms that might regulate the expression of CNS genes involved in the definition of the identity of specific cell types in the ventral midbrain. We integrate bioinformatics and functional genomics, together with developmental neurobiology. Moreover, we propose guidelines for the computational analysis of microarray gene expression data. Our findings help to clarify some molecular aspects of the development and differentiation of DA neurons within the midbrain.

Modification of the striatal dopaminergic neuron system by carbon monoxide exposure in free-moving rats, as determined by in vivo brain microdialysis

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Hara, Shuichi; Kurosaki, Kunihiko; Kuriiwa, Fumi; Endo, Takahiko [Department of Forensic Medicine, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402 (Japan); Mukai, Toshiji [Department of Legal Medicine, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki, Kanagawa 216-0015 (Japan)

2002-10-01

Acute carbon monoxide (CO) intoxication in humans results in motor deficits, which resemble those in Parkinson's disease, suggesting possible disturbance of the central dopaminergic (DAergic) neuronal system by CO exposure. In the present study, therefore, we explored the effects of CO exposure on the DAergic neuronal system in the striatum of freely moving rats by means of in vivo brain microdialysis. Exposure of rats to CO (up to 0.3%) for 40 min caused an increase in extracellular dopamine (DA) levels and a decrease in extracellular levels of its major metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), in the striatum depending on the CO concentration. Reoxygenation following termination of the CO exposure resulted in a decline of DA to the control level and an overshoot in the recovery of DOPAC and HVA to levels higher than the control. A monoamine oxidase type A (MAO-A) inhibitor, clorgyline, significantly potentiated the CO-induced increase in DA and completely abolished the subsequent overshoot in the recovery of DOPAC and HVA. Tetrodotoxin, a Na{sup +} channel blocker, completely abolished both the CO-induced increase in DA and the overshoot of DOPAC and HVA. A DA uptake inhibitor, nomifensine, strongly potentiated the CO-induced increase in DA without affecting the subsequent overshoot of DOPAC and HVA. Clorgyline further potentiated the effect of nomifensine on the CO-induced increase in DA, although a slight overshoot of DOPAC and HVA appeared. These findings suggest that (1) CO exposure may stimulate Na{sup +}-dependent DA release in addition to suppressing DA metabolism, resulting in a marked increase in extracellular DA in rat striatum, and (2) CO withdrawal and subsequent reoxygenation may enhance the oxidative metabolism, preferentially mediated by MAO-A, of the increased extracellular DA. In the light of the neurotoxicity of DA per se and reactive substances, such as quinones and activated oxygen species

9-Cis retinoic acid protects against methamphetamine-induced neurotoxicity in nigrostriatal dopamine neurons.

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Reiner, David J; Yu, Seong-Jin; Shen, Hui; He, Yi; Bae, Eunkyung; Wang, Yun

2014-04-01

Methamphetamine (MA) is a drug of abuse as well as a dopaminergic neurotoxin. 9-Cis retinoic acid (9cRA), a biologically active derivative of vitamin A, has protective effects against damage caused by H(2)O(2) and oxygen-glucose deprivation in vitro as well as infarction and terminal deoxynucleotidyl transferase-mediated dNTP nick-end labeling (TUNEL) labeling in ischemic brain. The purpose of this study was to examine if there was a protective role for 9cRA against MA toxicity in nigrostriatal dopaminergic neurons. Primary dopaminergic neurons, prepared from rat embryonic ventral mesencephalic tissue, were treated with MA. High doses of MA decreased tyrosine hydroxylase (TH) immunoreactivity while increasing TUNEL labeling. These toxicities were significantly reduced by 9cRA. 9cRA also inhibited the export of Nur77 from nucleus to cytosol, a response that activates apoptosis. The interaction of 9cRA and MA in vivo was next examined in adult rats. 9cRA was delivered intracerebroventricularly; MA was given (5 mg/kg, 4×) one day later. Locomotor behavior was measured 2 days after surgery for a period of 48 h. High doses of MA significantly reduced locomotor activity and TH immunoreactivity in striatum. Administration of 9cRA antagonized these changes. Previous studies have shown that 9cRA can induce bone morphogenetic protein-7 (BMP7) expression and that administration of BMP7 attenuates MA toxicity. We demonstrated that MA treatment significantly reduced BMP7 mRNA expression in nigra. Noggin (a BMP antagonist) antagonized 9cRA-induced behavioral recovery and 9cRA-induced normalization of striatal TH levels. Our data suggest that 9cRA has a protective effect against MA-mediated neurodegeneration in dopaminergic neurons via upregulation of BMP.

Novel tactics for neuroprotection in Parkinson's disease: Role of antibiotics, polyphenols and neuropeptides.

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Reglodi, Dora; Renaud, Justine; Tamas, Andrea; Tizabi, Yousef; Socías, Sergio B; Del-Bel, Elaine; Raisman-Vozari, Rita

2017-08-01

Parkinson's disease is a progressive neurodegenerative disorder characterized by the degeneration of midbrain nigral dopaminergic neurons. Although its etiology remains unknown, the pathological role of several factors has been highlighted, namely oxidative stress, neuroinflammation, protein misfolding, and mitochondrial dysfunction, in addition to genetic predispositions. The current therapy is mainly symptomatic with l-DOPA aiming to replace dopamine. Novel therapeutic approaches are being investigated with the intention of influencing pathways leading to neuronal death and dysfunction. The present review summarizes three novel approaches, the use of which is promising in pre-clinical studies. Polyphenols have been shown to possess neuroprotective properties on account of their well-established antioxidative and anti-inflammatory actions but also due to their influence on protein misfolding and mitochondrial homeostasis. Within the amazing ancillary effects of antibiotics, their neuroprotective properties against neurodegenerative and neuroinflammatory processes are of great interest for the development of effective therapies against Parkinson's disease. Experimental evidence supports the potential of antibiotics as neuroprotective agents, being useful not only to prevent the formation of toxic α-synuclein oligomers but also to ameliorate mitochondrial dysfunction and neuroinflammation. Neuropeptides offer another approach with their diverse effects in the nervous system. Among them, pituitary adenylate cyclase-activating polypeptide, a member of the secretin/glucagon superfamily, has several advantageous effects in models of neurodegeneration, namely anti-apoptotic, anti-inflammatory and antioxidant actions, the combination of which offers a potent protective effect in dopaminergic neurons. Owing to their pleiotropic modes of action, these novel therapeutic candidates have potential in tackling the multidimensional features of Parkinson's disease. Copyright �

Evaluation of nigrostriatal damage and its change over weeks in a rat model of Parkinson's disease: small animal positron emission tomography studies with [11C]β-CFT

International Nuclear Information System (INIS)

Liu Limin; Wang Yong; Li Bo; Jia Jun; Sun Zuoli; Zhang Jinming; Tian Jiahe; Wang Xiaomin

2009-01-01

Introduction: The cardinal pathological feature of Parkinson's disease (PD) is progressive loss of dopaminergic neurons. Since dopamine transporter (DAT) is a protein located presynaptically on dopaminergic nerve terminals, radioligands that bind to these sites are promising radiopharmaceuticals for evaluation of the integrity of the dopamine system. This study using positron emission tomography (PET) tracers, [ 11 C]-2β-carbomethoxy-3β-(4-fluorophenyl)-tropane ([ 11 C]β-CFT, radioligand for DAT), was aimed at evaluating the degree of nigrostriatal damage and its change over weeks in a rat model of PD. Methods: The brains of these rats were unilaterally lesioned by mechanical transection of the nigrostriatal dopamine pathway at the medial forebrain bundle (MFB). Behavioral studies were carried out by apomorphine (APO) challenge prior to and 1, 2 and 4 weeks after MFB axotomy. Small animal PET scans were performed 2 days after the behavioral test. Immunohistochemistry was conducted 4 days after the last PET scan. Results: Compared with the contralateral intact side, a progressively decreased [ 11 C]β-CFT binding was observed on the lesioned side which correlated inversely with the APO-induced rotations. Postmortem immunohistochemical studies confirmed the loss of both striatal dopamine fibers and nigral neurons on the lesioned side. Conclusion: These findings not only demonstrate that the neuronal degeneration in this model is relatively slow, but also suggest [ 11 C]β-CFT is a sensitive marker to monitor the degree of nigrostriatal damage and its change over weeks. This marker can be used prospectively to study the progression of the disease, thereby making detection of early phases of PD possible.

Astroglia overexpressing heme oxygenase-1 predispose co-cultured PC12 cells to oxidative injury.

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Song, Linyang; Song, Wei; Schipper, Hyman M

2007-08-01

The mechanisms responsible for the progressive degeneration of dopaminergic neurons and pathologic iron deposition in the substantia nigra pars compacta of patients with Parkinson's disease (PD) remain unclear. Heme oxygenase-1 (HO-1), the rate-limiting enzyme in the oxidative degradation of heme to ferrous iron, carbon monoxide, and biliverdin, is upregulated in affected PD astroglia and may contribute to abnormal mitochondrial iron sequestration in these cells. To determine whether glial HO-1 hyper-expression is toxic to neuronal compartments, we co-cultured dopaminergic PC12 cells atop monolayers of human (h) HO-1 transfected, sham-transfected, or non-transfected primary rat astroglia. We observed that PC12 cells grown atop hHO-1 transfected astrocytes, but not the astroglia themselves, were significantly more susceptible to dopamine (1 microM) + H(2)O(2) (1 microM)-induced death (assessed by nuclear ethidium monoazide bromide staining and anti-tyrosine hydroxylase immunofluorescence microscopy) relative to control preparations. In the experimental group, PC12 cell death was attenuated significantly by the administration of the HO inhibitor, SnMP (1.5 microM), the antioxidant, ascorbate (200 microM), or the iron chelators, deferoxamine (400 microM), and phenanthroline (100 microM). Exposure to conditioned media derived from HO-1 transfected astrocytes also augmented PC12 cell killing in response to dopamine (1 microM) + H(2)O(2) (1 microM) relative to control media. In PD brain, overexpression of HO-1 in nigral astroglia and accompanying iron liberation may facilitate the bioactivation of dopamine to neurotoxic free radical intermediates and predispose nearby neuronal constituents to oxidative damage. (c) 2007 Wiley-Liss, Inc.

Imaging mass spectrometry reveals elevated nigral levels of dynorphin neuropeptides in L-DOPA-induced dyskinesia in rat model of Parkinson's disease.

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Anna Ljungdahl

Full Text Available L-DOPA-induced dyskinesia is a troublesome complication of L-DOPA pharmacotherapy of Parkinson's disease and has been associated with disturbed brain opioid transmission. However, so far the results of clinical and preclinical studies on the effects of opioids agonists and antagonists have been contradictory at best. Prodynorphin mRNA levels correlate well with the severity of dyskinesia in animal models of Parkinson's disease; however the identities of the actual neuroactive opioid effectors in their target basal ganglia output structures have not yet been determined. For the first time MALDI-TOF imaging mass spectrometry (IMS was used for unbiased assessment and topographical elucidation of prodynorphin-derived peptides in the substantia nigra of a unilateral rat model of Parkinson's disease and L-DOPA induced dyskinesia. Nigral levels of dynorphin B and alpha-neoendorphin strongly correlated with the severity of dyskinesia. Even if dynorphin peptide levels were elevated in both the medial and lateral part of the substantia nigra, MALDI IMS analysis revealed that the most prominent changes were localized to the lateral part of the substantia nigra. MALDI IMS is advantageous compared with traditional molecular methods, such as radioimmunoassay, in that neither the molecular identity analyzed, nor the specific localization needs to be predetermined. Indeed, MALDI IMS revealed that the bioconverted metabolite leu-enkephalin-arg also correlated positively with severity of dyskinesia. Multiplexing DynB and leu-enkephalin-arg ion images revealed small (0.25 by 0.5 mm nigral subregions with complementing ion intensities, indicating localized peptide release followed by bioconversion. The nigral dynorphins associated with L-DOPA-induced dyskinesia were not those with high affinity to kappa opioid receptors, but consisted of shorter peptides, mainly dynorphin B and alpha-neoendorphin that are known to bind and activate mu and delta opioid receptors

Time-scale invariance as an emergent property in a perceptron with realistic, noisy neurons.

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Buhusi, Catalin V; Oprisan, Sorinel A

2013-05-01

In most species, interval timing is time-scale invariant: errors in time estimation scale up linearly with the estimated duration. In mammals, time-scale invariance is ubiquitous over behavioral, lesion, and pharmacological manipulations. For example, dopaminergic drugs induce an immediate, whereas cholinergic drugs induce a gradual, scalar change in timing. Behavioral theories posit that time-scale invariance derives from particular computations, rules, or coding schemes. In contrast, we discuss a simple neural circuit, the perceptron, whose output neurons fire in a clockwise fashion based on the pattern of coincidental activation of its input neurons. We show numerically that time-scale invariance emerges spontaneously in a perceptron with realistic neurons, in the presence of noise. Under the assumption that dopaminergic drugs modulate the firing of input neurons, and that cholinergic drugs modulate the memory representation of the criterion time, we show that a perceptron with realistic neurons reproduces the pharmacological clock and memory patterns, and their time-scale invariance, in the presence of noise. These results suggest that rather than being a signature of higher order cognitive processes or specific computations related to timing, time-scale invariance may spontaneously emerge in a massively connected brain from the intrinsic noise of neurons and circuits, thus providing the simplest explanation for the ubiquity of scale invariance of interval timing. Copyright © 2013 Elsevier B.V. All rights reserved.

Serotonergic neurons signal reward and punishment on multiple timescales

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Cohen, Jeremiah Y; Amoroso, Mackenzie W; Uchida, Naoshige

2015-01-01

Serotonin's function in the brain is unclear. One challenge in testing the numerous hypotheses about serotonin's function has been observing the activity of identified serotonergic neurons in animals engaged in behavioral tasks. We recorded the activity of dorsal raphe neurons while mice experienced a task in which rewards and punishments varied across blocks of trials. We ‘tagged’ serotonergic neurons with the light-sensitive protein channelrhodopsin-2 and identified them based on their responses to light. We found three main features of serotonergic neuron activity: (1) a large fraction of serotonergic neurons modulated their tonic firing rates over the course of minutes during reward vs punishment blocks; (2) most were phasically excited by punishments; and (3) a subset was phasically excited by reward-predicting cues. By contrast, dopaminergic neurons did not show firing rate changes across blocks of trials. These results suggest that serotonergic neurons signal information about reward and punishment on multiple timescales. DOI: http://dx.doi.org/10.7554/eLife.06346.001 PMID:25714923

Meta-type analysis of dopaminergic effects on gene expression in the neuroendocrine brain of female goldfish

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Jason T Popesku

2012-11-01

Full Text Available Dopamine (DA is a major neurotransmitter important for neuroendocrine control and recent studies have described genomic signalling pathways activated and inhibited by DA agonists and antagonists in the goldfish brain. Here we perform a meta-type analysis using microarray datasets from experiments conducted with female goldfish to characterize the gene expression responses that underlie dopaminergic signalling. Sexually mature, pre-spawning (GSI 4.5 ± 1.3% or sexually regressing ( GSI 3 ± 0.4% female goldfish (15-40 g injected intraperitoneally with either SKF 38393, LY 171555, SCH 23390, sulpiride, or a combination of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and α-methyl-p-tyrosine. Microarray meta-type analysis identified 268 genes in the telencephalon and hypothalamus as having reciprocal (i.e. opposite between agonism and antagonism/depletion fold change responses, suggesting that these transcripts are likely targets for DA-mediated regulation. Noteworthy genes included ependymin, vimentin, and aromatase, genes that support the significance of DA in neuronal plasticity and tissue remodelling. Sub-network enrichment analysis (SNEA was used to identify common gene regulators and binding proteins associated with the differentially expressed genes mediated by DA. SNEA analysis identified gene expression targets that were related to three major categories that included cell signalling (STAT3, SP1, SMAD, Jun/Fos, immune response (IL6, IL1β, TNFs, cytokine, NF-κB, and cell proliferation and growth (IGF1, TGFβ1. These gene networks are also known to be associated with neurodegenerative disorders such as Parkinsons’ disease, well-known to be associated with loss of dopaminergic neurons. This study identifies genes and networks that underlie DA signalling in the vertebrate CNS and provides targets that may be key neuroendocrine regulators. The results provide a foundation for future work on dopaminergic regulation of gene expression in fish

Microglia Polarization, Gene-Environment Interactions and Wnt/β-Catenin Signaling: Emerging Roles of Glia-Neuron and Glia-Stem/Neuroprogenitor Crosstalk for Dopaminergic Neurorestoration in Aged Parkinsonian Brain

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Francesca L'Episcopo

2018-02-01

Full Text Available Neuroinflammatory processes are recognized key contributory factors in Parkinson's disease (PD physiopathology. While the causes responsible for the progressive loss of midbrain dopaminergic (mDA neuronal cell bodies in the subtantia nigra pars compacta are poorly understood, aging, genetics, environmental toxicity, and particularly inflammation, represent prominent etiological factors in PD development. Especially, reactive astrocytes, microglial cells, and infiltrating monocyte-derived macrophages play dual beneficial/harmful effects, via a panel of pro- or anti-inflammatory cytokines, chemokines, neurotrophic and neurogenic transcription factors. Notably, with age, microglia may adopt a potent neurotoxic, pro-inflammatory “primed” (M1 phenotype when challenged with inflammatory or neurotoxic stimuli that hamper brain's own restorative potential and inhibit endogenous neurorepair mechanisms. In the last decade we have provided evidence for a major role of microglial crosstalk with astrocytes, mDA neurons and neural stem progenitor cells (NSCs in the MPTP- (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine- mouse model of PD, and identified Wnt/β-catenin signaling, a pivotal morphogen for mDA neurodevelopment, neuroprotection, and neuroinflammatory modulation, as a critical actor in glia-neuron and glia-NSCs crosstalk. With age however, Wnt signaling and glia-NSC-neuron crosstalk become dysfunctional with harmful consequences for mDA neuron plasticity and repair. These findings are of importance given the deregulation of Wnt signaling in PD and the emerging link between most PD related genes, Wnt signaling and inflammation. Especially, in light of the expanding field of microRNAs and inflammatory PD-related genes as modulators of microglial-proinflammatory status, uncovering the complex molecular circuitry linking PD and neuroinflammation will permit the identification of new druggable targets for the cure of the disease. Here we summarize

Tracers tor the investigation of cerebral presynaptic dopaminergic function with positron emission tomography

International Nuclear Information System (INIS)

Firnau, G.; Chirakal, R.; Nahmias, C.; Garnett, E.S.

1991-01-01

Two pharmacologic concepts, open-quotes metabolic precursorsclose quotes and open-quotes enzyme inhibitorsclose quotes have been applied to the design of PET tracers for the metabolic aspects of the neurotransmitter dopamine. As the result, highly useful, positron-emitting radiotracers have been developed with which to visualize and measure the cerebral distribution and metabolism of dopaminergic neurons. Positron emitter-labeled DOPA, particularly 6-[ 18 F]fluoro-L-DOPA, is being used to obtain information about the neurochemical anatomy of the dopamine system, and potentially, the rate constant of dopamine biosynthesis. 6-[ 18 F]Fluoro-L- meta-tyrosine delineates the dopaminergic structures even better than 6-[ 18 F]fluoro-L-DOPA but cannot provide kinetic information about dopamine biosynthesis. The in vivo activity of the enzyme aromatic L-aminoacid decarboxylase and that of monoamine oxidase types A and B can be measured with a-fluoro-methyl-6-[ 18 F]fluoro-L-DOPA, [ 11 C]clorgyline and L-[ 11 C]deprenyl, respectively. Thus, neuropharmacologic investigations of human presynaptic dopamine pharmacology are now possible in vivo

The pedunculopontine nucleus and its relationship to the pathophysiology of Parkinson's disease

International Nuclear Information System (INIS)

Blanco Lezcano, Lisette; Lorigados Pedre, Lourdes; Serrano Sanchez, Teresa; Pavon Fuentes, Nancy; Gonzalez, Maria Elena; Francis Turner, Liliana

2012-01-01

Several decades of neuropathological and imagenologic investigations have provided sufficient evidences about alterations in cholinergic neurotransmission that go together with the dopaminergic dysfunction in Parkinson's Disease (PD). The laterodorsal segmental Pedunculopontine nucleus (PPN) represents one of the main sources of cholinergic projections into the brain and at the same time the origin of the only cholinergic projection that substantia nigra pars compacta (SNPC) receives. at present, the study of the PPN participation as part of the physiopathology of PD has two notions: the impact of the lack of pontine excitatory influence on SNPC, associated to the early degeneration of PPN as well as the low frequency stimulation in the PPN as a beneficial surgical treatment for the axial symptoms of pd. PPN has emerged as an essential structure in the comprehension of PD physiopathology, given by its relation with the basal ganglia nuclei, thalamus, motor cortex and the spinal cord. The degeneration of some of its neuronal populations in PD pre symptomatic steps, has suggested a cause and effect relation on this finding and the death of nigral dopaminergic cells. On the other hand, PPN stimulation has favorable results on postural and gait disorders, which present themselves in late PD stages and are refractory to other pharmacological and surgical treatments.

Pentazocine Protects SN4741 Cells Against MPP+-Induced Cell Damage via Up-Regulation of the Canonical Wnt/β-Catenin Signaling Pathway

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Jiancai Wang

2017-06-01

Full Text Available The Wnt/β-catenin signaling pathway has been linked to many neurodegenerative diseases including Parkinson’s disease (PD. A glycoprotein named Dickkopf-1 (Dkk1 can combine with the receptor complex on cell membrane to inhibit Wnt/β-catenin signaling. Opioids, a series of compounds including morphine, fentanyl and pentazocine, have been reported to contribute to the up-regulation of Wnt/β-catenin signaling. Naloxone is an antagonist that has been used as an antidote to opioids through mu-opioid receptor. 1-methyl-4-phenylpyridinium (MPP+, which serves as a selective toxin for dopaminergic neurons, has been used to create experimental models of PD. In our study, we examined the protective effects of pentazocine against MPP+-induced cell death in the nigral dopaminergic cell line, SN4741 and tried to elucidate the molecular mechanisms underlying such protective effects. The data showed that pretreatment with pentazocine significantly rescued the SN4741 cell against MPP+. Moreover, the MPP+-exposed SN4741 cells exhibited a down-regulation of β-catenin, which could be restored by treatment with pentazocine. However, Dkk1 but not naloxonewas associated with the abrogation of protective effect of pentazocine. These results suggest that pentazocine alleviates MPP+-induced SN4741 cells apoptosis via the up-regulation of canonical Wnt/β-catenin signaling.

Control of proliferation rate of N27 dopaminergic neurons using Transcranial Magnetic Stimulation orientation

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Meng, Yiwen; Hadimani, Ravi; Anantharam, Vellareddy; Kanthasamy, Anumantha; Jiles, David

2015-03-01

Transcranial magnetic stimulation (TMS) has been used to investigate possible treatments for a variety of neurological disorders. However, the effect that magnetic fields have on neurons has not been well documented in the literature. We have investigated the effect of different orientation of magnetic field generated by TMS coils with a monophasic stimulator on the proliferation rate of N27 neuronal cells cultured in flasks and multi-well plates. The proliferation rate of neurons would increase by exposed horizontally adherent N27 cells to a magnetic field pointing upward through the neuronal proliferation layer compared with the control group. On the other hand, proliferation rate would decrease in cells exposed to a magnetic field pointing downward through the neuronal growth layer compared with the control group. We confirmed results obtained from the Trypan-blue and automatic cell counting methods with those from the CyQuant and MTS cell viability assays. Our findings could have important implications for the preclinical development of TMS treatments of neurological disorders and represents a new method to control the proliferation rate of neuronal cells.

Alterations in Neuronal Activity in Basal Ganglia-Thalamocortical Circuits in the Parkinsonian State

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Adriana eGalvan

2015-02-01

Full Text Available In patients with Parkinson’s disease and in animal models of this disorder, neurons in the basal ganglia and related regions in thalamus and cortex show changes that can be recorded by using electrophysiologic single-cell recording techniques, including altered firing rates and patterns, pathologic oscillatory activity and increased inter-neuronal synchronization. In addition, changes in synaptic potentials or in the joint spiking activities of populations of neurons can be monitored as alterations in local field potentials, electroencephalograms or electrocorticograms. Most of the mentioned electrophysiologic changes are probably related to the degeneration of diencephalic dopaminergic neurons, leading to dopamine loss in the striatum and other basal ganglia nuclei, although degeneration of non-dopaminergic cell groups may also have a role. The altered electrical activity of the basal ganglia and associated nuclei may contribute to some of the motor signs of the disease. We here review the current knowledge of the electrophysiologic changes at the single cell level, the level of local populations of neural elements, and the level of the entire basal ganglia-thalamocortical network in parkinsonism, and discuss the possible use of this information to optimize treatment approaches to Parkinson’s disease, such as deep brain stimulation therapy.

Alterations in neuronal activity in basal ganglia-thalamocortical circuits in the parkinsonian state

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Galvan, Adriana; Devergnas, Annaelle; Wichmann, Thomas

2015-01-01

In patients with Parkinson’s disease and in animal models of this disorder, neurons in the basal ganglia and related regions in thalamus and cortex show changes that can be recorded by using electrophysiologic single-cell recording techniques, including altered firing rates and patterns, pathologic oscillatory activity and increased inter-neuronal synchronization. In addition, changes in synaptic potentials or in the joint spiking activities of populations of neurons can be monitored as alterations in local field potentials (LFPs), electroencephalograms (EEGs) or electrocorticograms (ECoGs). Most of the mentioned electrophysiologic changes are probably related to the degeneration of diencephalic dopaminergic neurons, leading to dopamine loss in the striatum and other basal ganglia nuclei, although degeneration of non-dopaminergic cell groups may also have a role. The altered electrical activity of the basal ganglia and associated nuclei may contribute to some of the motor signs of the disease. We here review the current knowledge of the electrophysiologic changes at the single cell level, the level of local populations of neural elements, and the level of the entire basal ganglia-thalamocortical network in parkinsonism, and discuss the possible use of this information to optimize treatment approaches to Parkinson’s disease, such as deep brain stimulation (DBS) therapy. PMID:25698937

Retrograde axoplasmic flow of serotonin in central mono-aminergic neurons

International Nuclear Information System (INIS)

Leger, Lucienne; Pujol, J.-F.; Bobillier, Pierre; Jouvet, Michel

1977-01-01

Following an injection of 3 H-5 HT in the neostriatum of the Rat, the tracer is transported by axoplasmic retrograde flow to the cell groups containing mono-aminergic neurons which are known or thought to have afferences to this structure: substantia nigra, dopaminergic group A8 and n. raphe dorsalis [fr

GDNF family ligands display distinct action profiles on cultured GABAergic and serotonergic neurons of rat ventral mesencephalon

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Ducray, Angélique; Krebs, Sandra H:; Schaller, Benoft

2006-01-01

Glial-cell-line-derived neurotrophic factor (GDNF), neurturin (NRTN), artemin (ARTN) and persephin (PSPN), known as the GDNF family ligands (GFLs), influence the development, survival and differentiation of cultured dopaminergic neurons from ventral mesencephalon (VM). Detailed knowledge about...... factors for VM GABAergic and serotonergic neurons, demonstrating characteristic individual action profiles emphasizing their important and distinct roles during brain development....

Super-resolution microscopy reveals functional organization of dopamine transporters into cholesterol and neuronal activity-dependent nanodomains

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Rahbek-Clemmensen, Troels; Lycas, Matthew D.; Erlendsson, Simon

2017-01-01

is dynamically sequestrated into cholesterol-dependent nanodomains in the plasma membrane of presynaptic varicosities and neuronal projections of dopaminergic neurons. Stochastic optical reconstruction microscopy reveals irregular dopamine transporter nanodomains (∼70 nm mean diameter) that were highly sensitive...... to cholesterol depletion. Live photoactivated localization microscopy shows a similar dopamine transporter membrane organization in live heterologous cells. In neurons, dual-color dSTORM shows that tyrosine hydroxylase and vesicular monoamine transporter-2 are distinctively localized adjacent to...

24-Epibrassinolide, a Phytosterol from the Brassinosteroid Family, Protects Dopaminergic Cells against MPP+-Induced Oxidative Stress and Apoptosis

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Julie Carange

2011-01-01

Full Text Available Oxidative stress and apoptosis are frequently cited to explain neuronal cell damage in various neurodegenerative disorders, such as Parkinson' s disease. Brassinosteroids (BRs are phytosterols recognized to promote stress tolerance of vegetables via modulation of the antioxidative enzyme cascade. However, their antioxidative effects on mammalian neuronal cells have never been examined so far. We analyzed the ability of 24-epibrassinolide (24-Epi, a natural BR, to protect neuronal PC12 cells from 1-methyl-4-phenylpyridinium- (MPP+- induced oxidative stress and consequent apoptosis in dopaminergic neurons. Our results demonstrate that 24-Epi reduces the levels of intracellular reactive oxygen species and modulates superoxide dismutase, catalase, and glutathione peroxidase activities. Finally, we determined that the antioxidative properties of 24-Epi lead to the inhibition of MPP+-induced apoptosis by reducing DNA fragmentation as well as the Bax/Bcl-2 protein ratio and cleaved caspase-3. This is the first time that the potent antioxidant and neuroprotective role of 24-Epi has been shown in a mammalian neuronal cell line.

The emerging role of norepinephrine in cognitive dysfunctions of Parkinson’s disease

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Elena eVazey

2012-07-01

Full Text Available Parkinson’s disease (PD is the second most common neurodegenerative disorder, affecting 1% of the population over age 60. In those patients cognitive dysfunction is a persistent issue that impairs quality of life and productivity. Neuropathological studies demonstrate significant damage in brain regions outside the nigral dopamine (DA system, including early degeneration of locus coeruleus norepinephrine (LC-NE neurons, yet discussion of PD and treatment focus has remained dopaminergic-based. Motor symptoms benefit from DA replacement for many years, but other symptoms including several cognitive deficits continue unabated. Recent interest in non-DA substrates of PD highlights early involvement of LC-NE neurons and provides evidence for a prodromal phase, with cognitive disturbance, even in sporadic PD. We outline insights from basic research in LC-NE function to clinical and pathological evidence highlighting a role for NE in PD cognitive dysfunction. We propose that loss of LC-NE regulation, particularly in higher cortical regions, critically underlies certain cognitive dysfunctions in early PD. As a major unmet need for patients, research and use of NE drugs in PD may provide significant benefits for cognitive processing.

Icariin Reduces Dopaminergic Neuronal Loss and Microglia-Mediated Inflammation in Vivo and in Vitro

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Guo-Qing Wang

2018-01-01

Full Text Available Parkinson’s disease (PD is one of the most common neurodegenerative diseases characterized with a gradual loss of midbrain substantia nigra (SN dopamine (DA neurons. An excessive evidence demonstrated that microglia-mediated inflammation might be involved in the pathogenesis of PD. Thus, inhibition of neuroinflammation might possess a promising potential for PD treatment. Icariin (ICA, a single active component extracted from the Herba Epimedii, presents amounts of pharmacological properties, such as anti-inflammation, anti-oxidant, and anti-aging. Recent studies show ICA produced neuroprotection against brain dysfunction. However, the mechanisms underlying ICA-exerted neuroprotection are fully illuminated. In the present study, two different neurotoxins of 6-hydroxydopamine (6-OHDA and lipopolysaccharide (LPS-induced rat midbrain DA neuronal damage were applied to investigate the neuroprotective effects of ICA. In addition, primary rat midbrain neuron-glia co-cultures were performed to explore the mechanisms underlying ICA-mediated DA neuroprotection. In vitro data showed that ICA protected DA neurons from LPS/6-OHDA-induced DA neuronal damage and inhibited microglia activation and pro-inflammatory factors production via the suppression of nuclear factor-κB (NF-κB pathway activation. In animal results, ICA significantly reduced microglia activation and significantly attenuated LPS/6-OHDA-induced DA neuronal loss and subsequent animal behavior changes. Together, ICA could protect DA neurons against LPS- and 6-OHDA-induced neurotoxicity both in vivo and in vitro. These actions might be closely associated with the inhibition of microglia-mediated neuroinflammation.

1,2,3,4-Tetrahydroisoquinoline protects terminals of dopaminergic neurons in the striatum against the malonate-induced neurotoxicity.

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Lorenc-Koci, Elzbieta; Gołembiowska, Krystyna; Wardas, Jadwiga

2005-07-27

Malonate, a reversible inhibitor of the mitochondrial enzyme succinate dehydrogenase, is frequently used as a model neurotoxin to produce lesion of the nigrostriatal dopaminergic system in animals due to particular sensitivity of dopamine neurons to mild energy impairment. This model of neurotoxicity was applied in our study to explore neuroprotective potential of 1,2,3,4-tetrahydroisoquinoline (TIQ), an endo- and exogenous substance whose function in the mammalian brain, despite extensive studies, has not been elucidated so far. Injection of malonate at a dose of 3 mumol unilaterally into the rat left medial forebrain bundle resulted in the 54% decrease in dopamine (DA) concentration in the ipsilateral striatum and, depending on the examined striatum regions, caused 24-44% reduction in [3H]GBR12,935 binding to the dopamine transporter (DAT). TIQ (50 mg/kg i.p.) administered 4 h before malonate infusion and next once daily for successive 7 days prevented both these effects of malonate. Such TIQ treatment restored DA content and DAT binding almost to the control level. The results of the present study indicate that TIQ may act as a neuroprotective agent in the rat brain. An inhibition of the enzymatic activities of monoamine oxidase and gamma-glutamyl transpeptidase as well as an increase in the striatal levels of glutathione and nitric oxide found after TIQ administration and reported in our earlier studies are considered to be potential factors that may be involved in the TIQ-mediated protection of dopamine terminals from malonate toxicity.

Glucose Metabolism and AMPK Signaling Regulate Dopaminergic Cell Death Induced by Gene (α-Synuclein)-Environment (Paraquat) Interactions.

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Anandhan, Annadurai; Lei, Shulei; Levytskyy, Roman; Pappa, Aglaia; Panayiotidis, Mihalis I; Cerny, Ronald L; Khalimonchuk, Oleh; Powers, Robert; Franco, Rodrigo

2017-07-01

While environmental exposures are not the single cause of Parkinson's disease (PD), their interaction with genetic alterations is thought to contribute to neuronal dopaminergic degeneration. However, the mechanisms involved in dopaminergic cell death induced by gene-environment interactions remain unclear. In this work, we have revealed for the first time the role of central carbon metabolism and metabolic dysfunction in dopaminergic cell death induced by the paraquat (PQ)-α-synuclein interaction. The toxicity of PQ in dopaminergic N27 cells was significantly reduced by glucose deprivation, inhibition of hexokinase with 2-deoxy-D-glucose (2-DG), or equimolar substitution of glucose with galactose, which evidenced the contribution of glucose metabolism to PQ-induced cell death. PQ also stimulated an increase in glucose uptake, and in the levels of glucose transporter type 4 (GLUT4) and Na + -glucose transporters isoform 1 (SGLT1) proteins, but only inhibition of GLUT-like transport with STF-31 or ascorbic acid reduced PQ-induced cell death. Importantly, while autophagy protein 5 (ATG5)/unc-51 like autophagy activating kinase 1 (ULK1)-dependent autophagy protected against PQ toxicity, the inhibitory effect of glucose deprivation on cell death progression was largely independent of autophagy or mammalian target of rapamycin (mTOR) signaling. PQ selectively induced metabolomic alterations and adenosine monophosphate-activated protein kinase (AMPK) activation in the midbrain and striatum of mice chronically treated with PQ. Inhibition of AMPK signaling led to metabolic dysfunction and an enhanced sensitivity of dopaminergic cells to PQ. In addition, activation of AMPK by PQ was prevented by inhibition of the inducible nitric oxide syntase (iNOS) with 1400W, but PQ had no effect on iNOS levels. Overexpression of wild type or A53T mutant α-synuclein stimulated glucose accumulation and PQ toxicity, and this toxic synergism was reduced by inhibition of glucose metabolism

Impaired dopaminergic neurotransmission in patients with traumatic brain injury: a SPECT study using 123I-beta-CIT and 123I-IBZM.

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Donnemiller, E; Brenneis, C; Wissel, J; Scherfler, C; Poewe, W; Riccabona, G; Wenning, G K

2000-09-01

Structural imaging suggests that traumatic brain injury (TBI) may be associated with disruption of neuronal networks, including the nigrostriatal dopaminergic pathway. However, to date deficits in pre- and/or postsynaptic dopaminergic neurotransmission have not been demonstrated in TBI using functional imaging. We therefore assessed dopaminergic function in ten TBI patients using [123I]2-beta-carbomethoxy-3-beta-(4-iodophenyl)tropane (beta-CIT) and [123I]iodobenzamide (IBZM) single-photon emission tomography (SPET). Average Glasgow Coma Scale score (+/-SD) at the time of head trauma was 5.8+/-4.2. SPET was performed on average 141 days (SD +/-92) after TBI. The SPET images were compared with structural images using cranial computerised tomography (CCT) and magnetic resonance imaging (MRI). SPET was performed with an ADAC Vertex dual-head camera. The activity ratios of striatal to cerebellar uptake were used as a semiquantitative parameter of striatal dopamine transporter (DAT) and D2 receptor (D2R) binding. Compared with age-matched controls, patients with TBI had significantly lower striatal/cerebellar beta-CIT and IBZM binding ratios (PTBI despite relative structural preservation of the striatum. Further investigations of possible clinical correlates and efficacy of dopaminergic therapy in patients with TBI seem justified.

Molecular Aspects of Dopaminergic Neurodegeneration: Gene-Environment Interaction in Parkin Dysfunction

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Syed Z. Imam

2011-12-01

Full Text Available Parkinson’s disease (PD is a common neurodegenerative movement disorder that is characterized pathologically by a progressive loss of midbrain dopaminergic neurons and by protein inclusions, designated Lewy bodies and Lewy neurites. PD is one of the most common neurodegenerative diseases, affecting almost 1% of the population over 60 years old. Although the symptoms and neuropathology of PD have been well characterized, the underlying mechanisms and causes of the disease are still not clear. Genetic mutations can provide important clues to disease mechanism, but most PD cases are sporadic rather than familial; environmental factors have long been suspected to contribute to the disease. Although more than 90% of PD cases occur sporadically and are thought to be due, in part, to oxidative stress and mitochondrial dysfunction, the study of genetic mutations has provided great insight into the molecular mechanisms of PD. Furthermore, rotenone, a widely used pesticide, and paraquat and maneb cause a syndrome in rats and mice that mimics, both behaviorally and neurologically, the symptoms of PD. In the current review, we will discuss various aspects of gene-environment interaction that lead to progressive dopaminergic neurodegenration, mainly focusing on our current finding based on stress-mediated parkin dysfunction.

Dopaminergic Dysregulation, Artistic Expressiveness, and Parkinson's Disease

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López-Pousa, S.; Lombardía-Fernández, C.; Olmo, J. Garre; Monserrat-Vila, S.; Vilalta-Franch, J.; Calvó-Perxas, L.

2012-01-01

Background The most frequent behavioral manifestations in Parkinson's disease (PD) are attributed to the dopaminergic dysregulation syndrome (DDS), which is considered to be secondary to the iatrogenic effects of the drugs that replace dopamine. Over the past few years some cases of patients improving their creative abilities after starting treatment with dopaminergic pharmaceuticals have been reported. These effects have not been clearly associated to DDS, but a relationship has been pointed out. Methods Case study of a patient with PD. The evolution of her paintings along medication changes and disease advance has been analyzed. Results The patient showed a compulsive increase of pictorial production after the diagnosis of PD was made. She made her best paintings when treated with cabergolide, and while painting, she reported a feeling of well-being, with loss of awareness of the disease and reduction of physical limitations. Conclusions Dopaminergic antagonists (DA) trigger a dopaminergic dysfunction that alters artistic creativity in patients having a predisposition for it. The development of these skills might be due to the dopaminergic overstimulation due to the therapy with DA, which causes a neurophysiological alteration that globally determines DDS. PMID:23185168

A comparison of experience-dependent locomotory behaviors and biogenic amine neurons in nematode relatives of Caenorhabditis elegans

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Sternberg Paul W

2010-02-01

Full Text Available Abstract Background Survival of an animal depends on its ability to match its responses to environmental conditions. To generate an optimal behavioral output, the nervous system must process sensory information and generate a directed motor output in response to stimuli. The nervous system should also store information about experiences to use in the future. The diverse group of free-living nematodes provides an excellent system to study macro- and microevolution of molecular, morphological and behavioral character states associated with such nervous system function. We asked whether an adaptive behavior would vary among bacterivorous nematodes and whether differences in the neurotransmitter systems known to regulate the behavior in one species would reflect differences seen in the adaptive behavior among those species. Caenorhabditis elegans worms slow in the presence of food; this 'basal' slowing is triggered by dopaminergic mechanosensory neurons that detect bacteria. Starved worms slow more dramatically; this 'enhanced' slowing is regulated by serotonin. Results We examined seven nematode species with known phylogenetic relationship to C. elegans for locomotory behaviors modulated by food (E. coli, and by the worm's recent history of feeding (being well-fed or starved. We found that locomotory behavior in some species was modulated by food and recent feeding experience in a manner similar to C. elegans, but not all the species tested exhibited these food-modulated behaviors. We also found that some worms had different responses to bacteria other than E. coli. Using histochemical and immunological staining, we found that dopaminergic neurons were very similar among all species. For instance, we saw likely homologs of four bilateral pairs of dopaminergic cephalic and deirid neurons known from C. elegans in all seven species examined. In contrast, there was greater variation in the patterns of serotonergic neurons. The presence of presumptive

Age-Dependence and Aging-Dependence: Neuronal Loss and Lifespan in a C. elegans Model of Parkinson's Disease.

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Apfeld, Javier; Fontana, Walter

2017-12-23

It is often assumed, but not established, that the major neurodegenerative diseases, such as Parkinson's disease, are not just age-dependent (their incidence changes with time) but actually aging-dependent (their incidence is coupled to the process that determines lifespan). To determine a dependence on the aging process requires the joint probability distribution of disease onset and lifespan. For human Parkinson's disease, such a joint distribution is not available, because the disease cuts lifespan short. To acquire a joint distribution, we resorted to an established C. elegans model of Parkinson's disease in which the loss of dopaminergic neurons is not fatal. We find that lifespan is not correlated with the loss of individual neurons. Therefore, neuronal loss is age-dependent and aging-independent. We also find that a lifespan-extending intervention into insulin/IGF1 signaling accelerates the loss of specific dopaminergic neurons, while leaving death and neuronal loss times uncorrelated. This suggests that distinct and compartmentalized instances of the same genetically encoded insulin/IGF1 signaling machinery act independently to control neurodegeneration and lifespan in C. elegans . Although the human context might well be different, our study calls attention to the need to maintain a rigorous distinction between age-dependence and aging-dependence.

DNA damage preceding dopamine neuron degeneration in A53T human α-synuclein transgenic mice

International Nuclear Information System (INIS)

Wang, Degui; Yu, Tianyu; Liu, Yongqiang; Yan, Jun; Guo, Yingli; Jing, Yuhong; Yang, Xuguang; Song, Yanfeng; Tian, Yingxia

2016-01-01

Defective DNA repair has been linked with age-associated neurodegenerative disorders. Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by genetic and environmental factors. Whether damages to nuclear DNA contribute to neurodegeneration of PD still remain obscure. in this study we aim to explore whether nuclear DNA damage induce dopamine neuron degeneration in A53T human α-Synuclein over expressed mouse model. We investigated the effects of X-ray irradiation on A53T-α-Syn MEFs and A53T-α-Syn transgene mice. Our results indicate that A53T-α-Syn MEFs show a prolonged DNA damage repair process and senescense phenotype. DNA damage preceded onset of motor phenotype in A53T-α-Syn transgenic mice and decrease the number of nigrostriatal dopaminergic neurons. Neurons of A53T-α-Syn transgenic mice are more fragile to DNA damages. - Highlights: • This study explore contribution of DNA damage to neurodegeneration in Parkinson's disease mice. • A53T-α-Syn MEF cells show a prolonged DNA damage repair process and senescense phenotype. • DNA damage preceded onset of motor phenotype in A53T-α-Syn transgenic mice. • DNA damage decrease the number of nigrostriatal dopaminergic neurons. • Neurons of A53T-α-Syn transgenic mice are more fragile to DNA damages.

Molecular mechanisms underlying protective effects of quercetin against mitochondrial dysfunction and progressive dopaminergic neurodegeneration in cell culture and MitoPark transgenic mouse models of Parkinson's Disease.

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Ay, Muhammet; Luo, Jie; Langley, Monica; Jin, Huajun; Anantharam, Vellareddy; Kanthasamy, Arthi; Kanthasamy, Anumantha G

2017-06-01

Quercetin, one of the major flavonoids in plants, has been recently reported to have neuroprotective effects against neurodegenerative processes. However, since the molecular signaling mechanisms governing these effects are not well clarified, we evaluated quercetin's effect on the neuroprotective signaling events in dopaminergic neuronal models and further tested its efficacy in the MitoPark transgenic mouse model of Parkinson's disease (PD). Western blot analysis revealed that quercetin significantly induced the activation of two major cell survival kinases, protein kinase D1 (PKD1) and Akt in MN9D dopaminergic neuronal cells. Furthermore, pharmacological inhibition or siRNA knockdown of PKD1 blocked the activation of Akt, suggesting that PKD1 acts as an upstream regulator of Akt in quercetin-mediated neuroprotective signaling. Quercetin also enhanced cAMP response-element binding protein phosphorylation and expression of the cAMP response-element binding protein target gene brain-derived neurotrophic factor. Results from qRT-PCR, Western blot analysis, mtDNA content analysis, and MitoTracker assay experiments revealed that quercetin augmented mitochondrial biogenesis. Quercetin also increased mitochondrial bioenergetics capacity and protected MN9D cells against 6-hydroxydopamine-induced neurotoxicity. To further evaluate the neuroprotective efficacy of quercetin against the mitochondrial dysfunction underlying PD, we used the progressive dopaminergic neurodegenerative MitoPark transgenic mouse model of PD. Oral administration of quercetin significantly reversed behavioral deficits, striatal dopamine depletion, and TH neuronal cell loss in MitoPark mice. Together, our findings demonstrate that quercetin activates the PKD1-Akt cell survival signaling axis and suggest that further exploration of quercetin as a promising neuroprotective agent for treating PD may offer clinical benefits. © 2017 International Society for Neurochemistry.

Odorants could elicit repair processes in melanized neuronal and skin cells

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Barbara Pavan

2017-01-01

Full Text Available The expression of ectopic olfactory receptors (ORs in melanized cells, such as the human brain nigrostriatal dopaminergic neurons and skin melanocytes, is here pointed out. ORs are recognized to regulate skin melanogenesis, whereas OR expression in the dopaminergic neurons, characterized by accumulation of pigment neuromelanin, is downregulated in Parkinson's disease. Furthermore, the correlation between the pigmentation process and the dopamine pathway through α-synuclein expression is also highlighted. Purposely, these ORs are suggested as therapeutic target for neurodegenerative diseases related to the pigmentation disorders. Based on this evidence, a possible way of turning odorants into drugs, acting on three specific olfactory receptors, OR51E2, OR2AT4 and VN1R1, is thus introduced. Various odorous molecules are shown to interact with these ORs and their therapeutic potential against melanogenic and neurodegenerative dysfunctions, including melanoma and Parkinson's disease, is suggested. Finally, a direct functional link between olfactory and endocrine systems in human brain through VN1R1 is proposed, helping to counteract female susceptibility to Parkinson's disease in quiescent life.

Lack of Neuronal IFN-β-IFNAR Causes Lewy Body- and Parkinson's Disease-like Dementia

DEFF Research Database (Denmark)

Ejlerskov, Patrick; Hultberg, Jeanette Göransdotter; Wang, JunYang

2015-01-01

-causing mutant proteins. Mice lacking Ifnb function exhibited motor and cognitive learning impairments with accompanying α-synuclein-containing Lewy bodies in the brain, as well as a reduction in dopaminergic neurons and defective dopamine signaling in the nigrostriatal region. Lack of IFN-β signaling caused...

Overexpression of DJ-1/PARK7, the Parkinson's disease-related protein, improves mitochondrial function via Akt phosphorylation on threonine 308 in dopaminergic neuron-like cells.

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Zhang, Yi; Gong, Xiao-Gang; Wang, Zhen-Zhen; Sun, Hong-Mei; Guo, Zhen-Yu; Hu, Jing-Hong; Ma, Ling; Li, Ping; Chen, Nai-Hong

2016-05-01

DJ-1/PARK7, the Parkinson's disease-related protein, plays an important role in mitochondrial function. However, the mechanisms by which DJ-1 affects mitochondrial function are not fully understood. Akt is a promoter of neuron survival and is partly involved in the neurodegenerative process. This research aimed at investigating a possible relationship between DJ-1 and Akt signalling in regulating mitochondrial function in the dopaminergic neuron-like cells SH-SY5Y and PC-12. Overexpression of DJ-1 was firstly validated at both the transcriptional and translational levels after transit transfection with plasmid pcDNA3-Flag-DJ-1. Confocal fluorescence microscopy demonstrated that overexpression of DJ-1 increased the mitochondrial mass, but did not disrupt the mitochondrial morphology. In addition, mitochondrial complex I activity was raised in DJ-1-overexpressing cells, and this rise occurred with an increase in cellular adenosine 5'-triphosphate content. Moreover, immunoblotting demonstrated that the levels of phosphoinositide 3-kinase and the total Akt were not altered in DJ-1-overexpressing cells, and nor was the Akt phosphorylation on serine 473 changed. By contrast, Akt phosphorylation on threonine 308 was significantly augmented by overexpression of DJ-1, and the expression of glycogen synthase kinase-3beta, a downstream effector of Akt, was suppressed. In summary, these results suggest that overexpression of DJ-1 improves the mitochondrial function, at least in part, through a mechanism involving Akt phosphorylation on threonine 308. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Regulatory Mechanisms Involved in the Expression of Brain-Derived Neurotrophic Factor and Glial Cell Line-Derived Neurotrophic Factor

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1996-03-01

neurotoxic dopamine analog that is taken up by nigral dopaminergic cells where it is metabolized to highly reactive oxygen free radicals that cause ...brain regions is elevated after other types of brain insults, including ischemia and hypoglycemia (see Lindvall et al. 1994 for review). Lindvall et a1...with kainic acid were also reported. These investigators also reported significant increases in BDNF mRNA levels in cultures of neonatal astrocytes

Neuronal Subtype Generation During Postnatal Olfactory Bulb Neurogenesis.

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Angelova, Alexandra; Tiveron, Marie-Catherine; Cremer, Harold; Beclin, Christophe

2018-01-01

In the perinatal and adult forebrain, regionalized neural stem cells lining the ventricular walls produce different types of olfactory bulb interneurons. Although these postnatal stem cells are lineage related to their embryonic counterparts that produce, for example, cortical, septal, and striatal neurons, their output at the level of neuronal phenotype changes dramatically. Tiveron et al. investigated the molecular determinants underlying stem cell regionalization and the gene expression changes inducing the shift from embryonic to adult neuron production. High-resolution gene expression analyses of different lineages revealed that the zinc finger proteins, Zic1 and Zic2, are postnatally induced in the dorsal olfactory bulb neuron lineage. Functional studies demonstrated that these factors confer a GABAergic and calretinin-positive phenotype to neural stem cells while repressing dopaminergic fate. Based on these findings, we discuss the molecular mechanisms that allow acquisition of new traits during the transition from embryonic to adult neurogenesis. We focus on the involvement of epigenetic marks and emphasize why the identification of master transcription factors, that instruct the fate of postnatally generated neurons, can help in deciphering the mechanisms driving fate transition from embryonic to adult neuron production.

Neuronal Subtype Generation During Postnatal Olfactory Bulb Neurogenesis

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Alexandra Angelova

2018-02-01

Full Text Available In the perinatal and adult forebrain, regionalized neural stem cells lining the ventricular walls produce different types of olfactory bulb interneurons. Although these postnatal stem cells are lineage related to their embryonic counterparts that produce, for example, cortical, septal, and striatal neurons, their output at the level of neuronal phenotype changes dramatically. Tiveron et al. investigated the molecular determinants underlying stem cell regionalization and the gene expression changes inducing the shift from embryonic to adult neuron production. High-resolution gene expression analyses of different lineages revealed that the zinc finger proteins, Zic1 and Zic2, are postnatally induced in the dorsal olfactory bulb neuron lineage. Functional studies demonstrated that these factors confer a GABAergic and calretinin-positive phenotype to neural stem cells while repressing dopaminergic fate. Based on these findings, we discuss the molecular mechanisms that allow acquisition of new traits during the transition from embryonic to adult neurogenesis. We focus on the involvement of epigenetic marks and emphasize why the identification of master transcription factors, that instruct the fate of postnatally generated neurons, can help in deciphering the mechanisms driving fate transition from embryonic to adult neuron production.

Striatal and Tegmental Neurons Code Critical Signals for Temporal-Difference Learning of State Value in Domestic Chicks

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Chentao Wen

2016-11-01

Full Text Available To ensure survival, animals must update the internal representations of their environment in a trial-and-error fashion. Psychological studies of associative learning and neurophysiological analyses of dopaminergic neurons have suggested that this updating process involves the temporal-difference (TD method in the basal ganglia network. However, the way in which the component variables of the TD method are implemented at the neuronal level is unclear. To investigate the underlying neural mechanisms, we trained domestic chicks to associate color cues with food rewards. We recorded neuronal activities from the medial striatum or tegmentum in a freely behaving condition and examined how reward omission changed neuronal firing. To compare neuronal activities with the signals assumed in the TD method, we simulated the behavioral task in the form of a finite sequence composed of discrete steps of time. The three signals assumed in the simulated task were the prediction signal, the target signal for updating, and the TD-error signal. In both the medial striatum and tegmentum, the majority of recorded neurons were categorized into three types according to their fitness for three models, though these neurons tended to form a continuum spectrum without distinct differences in the firing rate. Specifically, two types of striatal neurons successfully mimicked the target signal and the prediction signal. A linear summation of these two types of striatum neurons was a good fit for the activity of one type of tegmental neurons mimicking the TD-error signal. The present study thus demonstrates that the striatum and tegmentum can convey the signals critically required for the TD method. Based on the theoretical and neurophysiological studies, together with tract-tracing data, we propose a novel model to explain how the convergence of signals represented in the striatum could lead to the computation of TD error in tegmental dopaminergic neurons.

Chemogenetic activation of dopamine neurons in the ventral tegmental area, but not substantia nigra, induces hyperactivity in rats

NARCIS (Netherlands)

Boekhoudt, Linde; Omrani, Azar; Luijendijk, Mieneke C M; Wolterink-Donselaar, Inge G; Wijbrans, Ellen C; van der Plasse, Geoffrey; Adan, Roger A H

2016-01-01

Hyperactivity is a core symptom in various psychiatric disorders, including attention-deficit/hyperactivity disorder, schizophrenia, bipolar disorders, and anorexia nervosa. Although hyperactivity has been linked to dopaminergic  signalling, the causal relationship between midbrain dopamine neuronal

Nigrostriatal proteasome inhibition impairs dopamine neurotransmission and motor function in minipigs.

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Lillethorup, Thea P; Glud, Andreas N; Alstrup, Aage K O; Mikkelsen, Trine W; Nielsen, Erik H; Zaer, Hamed; Doudet, Doris J; Brooks, David J; Sørensen, Jens Christian H; Orlowski, Dariusz; Landau, Anne M

2018-05-01

Parkinson's disease (PD) is characterized by degeneration of dopaminergic neurons in the substantia nigra leading to slowness and stiffness of limb movement with rest tremor. Using ubiquitin proteasome system inhibitors, rodent models have shown nigrostriatal degeneration and motor impairment. We translated this model to the Göttingen minipig by administering lactacystin into the medial forebrain bundle (MFB). Minipigs underwent positron emission tomography (PET) imaging with (+)-α-[ 11 C]dihydrotetrabenazine ([ 11 C]DTBZ), a marker of vesicular monoamine transporter 2 availability, at baseline and three weeks after the unilateral administration of 100 μg lactacystin into the MFB. Compared to their baseline values, minipigs injected with lactacystin showed on average a 36% decrease in ipsilateral striatal binding potential corresponding to impaired presynaptic dopamine terminals. Behaviourally, minipigs displayed asymmetrical motor disability with spontaneous rotations in one of the animals. Immunoreactivity for tyrosine hydroxylase (TH) and HLA-DR-positive microglia confirmed asymmetrical reduction in nigral TH-positive neurons with an inflammatory response in the lactacystin-injected minipigs. In conclusion, direct injection of lactacystin into the MFB of minipigs provides a model of PD with reduced dopamine neurotransmission, TH-positive neuron reduction, microglial activation and behavioural deficits. This large animal model could be useful in studies of symptomatic and neuroprotective therapies with translatability to human PD. Copyright © 2018 Elsevier Inc. All rights reserved.

Subthalamic nucleus high-frequency stimulation restores altered electrophysiological properties of cortical neurons in parkinsonian rat.

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Bertrand Degos

Full Text Available Electrophysiological recordings performed in parkinsonian patients and animal models have confirmed the occurrence of alterations in firing rate and pattern of basal ganglia neurons, but the outcome of these changes in thalamo-cortical networks remains unclear. Using rats rendered parkinsonian, we investigated, at a cellular level in vivo, the electrophysiological changes induced in the pyramidal cells of the motor cortex by the dopaminergic transmission interruption and further characterized the impact of high-frequency electrical stimulation of the subthalamic nucleus, a procedure alleviating parkinsonian symptoms. We provided evidence that a lesion restricted to the substantia nigra pars compacta resulted in a marked increase in the mean firing rate and bursting pattern of pyramidal neurons of the motor cortex. These alterations were underlain by changes of the electrical membranes properties of pyramidal cells including depolarized resting membrane potential and increased input resistance. The modifications induced by the dopaminergic loss were more pronounced in cortico-striatal than in cortico-subthalamic neurons. Furthermore, subthalamic nucleus high-frequency stimulation applied at parameters alleviating parkinsonian signs regularized the firing pattern of pyramidal cells and restored their electrical membrane properties.

Transplantation of neuronal-primed human bone marrow mesenchymal stem cells in hemiparkinsonian rodents.

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Melissa L M Khoo

Full Text Available Bone marrow-derived human mesenchymal stem cells (hMSCs have shown promise in in vitro neuronal differentiation and in cellular therapy for neurodegenerative disorders, including Parkinson' disease. However, the effects of intracerebral transplantation are not well defined, and studies do not agreed on the optimal neuronal differentiation method. Here, we investigated three growth factor-based neuronal differentiation procedures (using FGF-2/EGF/PDGF/SHH/FGF-8/GDNF, and found all to be capable of eliciting an immature neural phenotype, in terms of cell morphology and gene/protein expression. The neuronal-priming (FGF-2/EGF method induced neurosphere-like formation and the highest NES and NR4A2 expression by hMSCs. Transplantation of undifferentiated and neuronal-primed hMSCs into the striatum and substantia nigra of 6-OHDA-lesioned hemiparkinsonian rats revealed transient graft survival of 7 days, despite the reported immunosuppressive properties of MSCs and cyclosporine-immunosuppression of rats. Neither differentiation of hMSCs nor induction of host neurogenesis was observed at injection sites, and hMSCs continued producing mesodermal fibronectin. Strategies for improving engraftment and differentiation post-transplantation, such as prior in vitro neuronal-priming, nigral and striatal grafting, and co-transplantation of olfactory ensheathing cells that promote neural regeneration, were unable to provide advantages. Innate inflammatory responses (Iba-1-positive microglia/macrophage and GFAP-positive astrocyte activation and accumulation were detected around grafts within 7 days. Our findings indicate that growth factor-based methods allow hMSC differentiation toward immature neuronal-like cells, and contrary to previous reports, only transient survival and engraftment of hMSCs occurs following transplantation in immunosuppressed hemiparkinsonian rats. In addition, suppression of host innate inflammatory responses may be a key factor for

Dopamine D(3) receptors contribute to methamphetamine-induced alterations in dopaminergic neuronal function: role of hyperthermia.

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Baladi, Michelle G; Newman, Amy H; Nielsen, Shannon M; Hanson, Glen R; Fleckenstein, Annette E

2014-06-05

Methamphetamine administration causes long-term deficits to dopaminergic systems that, in humans, are thought to be associated with motor slowing and memory impairment. Methamphetamine interacts with the dopamine transporter (DAT) and increases extracellular concentrations of dopamine that, in turn, binds to a number of dopamine receptor subtypes. Although the relative contribution of each receptor subtype to the effects of methamphetamine is not fully known, non-selective dopamine D2/D3 receptor antagonists can attenuate methamphetamine-induced changes to dopamine systems. The present study extended these findings by testing the role of the dopamine D3 receptor subtype in mediating the long-term dopaminergic, and for comparison serotonergic, deficits caused by methamphetamine. Results indicate that the dopamine D3 receptor selective antagonist, PG01037, attenuated methamphetamine-induced decreases in striatal DAT, but not hippocampal serotonin (5HT) transporter (SERT), function, as assessed 7 days after treatment. However, PG01037 also attenuated methamphetamine-induced hyperthermia. When methamphetamine-induced hyperthermia was maintained by treating rats in a warm ambient environment, PG01037 failed to attenuate the effects of methamphetamine on DAT uptake. Furthermore, PG01037 did not attenuate methamphetamine-induced decreases in dopamine and 5HT content. Taken together, the present study demonstrates that dopamine D3 receptors mediate, in part, the long-term deficits in DAT function caused by methamphetamine, and that this effect likely involves an attenuation of methamphetamine-induced hyperthermia. Copyright © 2014 Elsevier B.V. All rights reserved.

Dopamine D3 receptors contribute to methamphetamine-induced alterations in dopaminergic neuronal function: Role of hyperthermia

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Baladi, Michelle G.; Newman, Amy H.; Nielsen, Shannon M.; Hanson, Glen R.; Fleckenstein, Annette E.

2014-01-01

Methamphetamine administration causes long-term deficits to dopaminergic systems that, in humans, are thought to be associated with motor slowing and memory impairment. Methamphetamine interacts with the dopamine transporter (DAT) and increases extracellular concentrations of dopamine that, in turn, binds to a number of dopamine receptor subtypes. Although the relative contribution of each receptor subtype to the effects of methamphetamine is not fully known, non-selective dopamine D2/D3 receptor antagonists can attenuate methamphetamine-induced changes to dopamine systems. The present study extended these findings by testing the role of the dopamine D3 receptor subtype in mediating the long-term dopaminergic, and for comparison serotonergic, deficits caused by methamphetamine. Results indicate that the dopamine D3 receptor selective antagonist, PG01037, attenuated methamphetamine-induced decreases in striatal DAT, but not hippocampal serotonin (5HT) transporter (SERT), function, as assessed 7 days after treatment. However, PG01037 also attenuated methamphetamine-induced hyperthermia. When methamphetamine-induced hyperthermia was maintained by treating rats in a warm ambient environment, PG01037 failed to attenuate the effects of methamphetamine on DAT uptake. Furthermore, PG01037 did not attenuate methamphetamine-induced decreases in dopamine and 5HT content. Taken together, the present study demonstrates that dopamine D3 receptors mediate, in part, the long-term deficits in DAT function caused by methamphetamine, and that this effect likely involves an attenuation of methamphetamine-induced hyperthermia. PMID:24685638

Ibuprofen or piroxicam protects nigral neurons and delays the development of l-dopa induced dyskinesia in rats with experimental Parkinsonism: Influence on angiogenesis.

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Teema, Asmaa M; Zaitone, Sawsan A; Moustafa, Yasser M

2016-08-01

Neuroinflammation and angiogenesis have been involved in the pathogenesis of Parkinson's disease (PD). This study investigated the effect of ibuprofen or piroxicam on the motor response to l-dopa and development of dyskinesia in Parkinsonian rats focusing on the anti-angiogenic role of the two non-steroidal anti-inflammatory drugs (NSAIDs). Rats were divided into nine groups as follows: Group I: the vehicle group, Group II: rotenone group, rats were injected with nine doses of rotenone (1 mg/kg/48 h), group III&IV: rats received rotenone + ibuprofen (10 or 30 mg/kg), Group V-VI: rats received rotenone + piroxicam (1 or 3 mg/kg), Group VII: rats received rotenone + l-dopa/carbidopa (100/10 mg/kg), Group VIII-IX: rats received rotenone + l-dopa/carbidopa + ibuprofen (30 mg/kg) or piroxicam (3 mg/kg). In general, drugs were administered daily for ten weeks. Rotenone-treated rats showed motor dysfunction, lower striatal dopamine, lower staining for nigral tyrosine hydroxylase but higher level of striatal cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) compared to vehicle-treated rats (P piroxicam in combination with l-dopa preserved the effect of l-dopa at the end of week 10, delayed the development of dyskinesia and decreased striatal COX-2 and VEGF levels. In conclusion, the current study suggests that ibuprofen and piroxicam are promising candidates for neuroprotection in PD and may have utility in conjunction with l-dopa in order to ensure the longevity of its action and to delay the development of dyskinesia. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dietary Plant Lectins Appear to Be Transported from the Gut to Gain Access to and Alter Dopaminergic Neurons of Caenorhabditis elegans, a Potential Etiology of Parkinson’s Disease

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Zheng, Jolene; Wang, Mingming; Wei, Wenqian; Keller, Jeffrey N.; Adhikari, Binita; King, Jason F.; King, Michael L.; Peng, Nan; Laine, Roger A.

2016-01-01

Lectins from dietary plants have been shown to enhance drug absorption in the gastrointestinal tract of rats, be transported trans-synaptically as shown by tracing of axonal and dendritic paths, and enhance gene delivery. Other carbohydrate-binding protein toxins are known to traverse the gut intact in dogs. Post-feeding rhodamine- or TRITC-tagged dietary lectins, the lectins were tracked from gut to dopaminergic neurons (DAergic-N) in transgenic Caenorhabditis elegans (C. elegans) [egIs1(Pdat-1:GFP)] where the mutant has the green fluorescent protein (GFP) gene fused to a dopamine transport protein gene labeling DAergic-N. The lectins were supplemented along with the food organism Escherichia coli (OP50). Among nine tested rhodamine/TRITC-tagged lectins, four, including Phaseolus vulgaris erythroagglutinin (PHA-E), Bandeiraea simplicifolia (BS-I), Dolichos biflorus agglutinin (DBA), and Arachis hypogaea agglutinin (PNA), appeared to be transported from gut to the GFP-DAergic-N. Griffonia Simplicifolia and PHA-E, reduced the number of GFP-DAergic-N, suggesting a toxic activity. PHA-E, BS-I, Pisum sativum (PSA), and Triticum vulgaris agglutinin (Succinylated) reduced fluorescent intensity of GFP-DAergic-N. PHA-E, PSA, Concanavalin A, and Triticum vulgaris agglutinin decreased the size of GFP-DAergic-N, while BS-I increased neuron size. These observations suggest that dietary plant lectins are transported to and affect DAergic-N in C. elegans, which support Braak and Hawkes’ hypothesis, suggesting one alternate potential dietary etiology of Parkinson’s disease (PD). A recent Danish study showed that vagotomy resulted in 40% lower incidence of PD over 20 years. Differences in inherited sugar structures of gut and neuronal cell surfaces may make some individuals more susceptible in this conceptual disease etiology model. PMID:27014695

Vagus nerve stimulation improves locomotion and neuronal populations in a model of Parkinson's disease.

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Farrand, Ariana Q; Helke, Kristi L; Gregory, Rebecca A; Gooz, Monika; Hinson, Vanessa K; Boger, Heather A

Parkinson's disease (PD) is a progressive, neurodegenerative disorder with no disease-modifying therapies, and symptomatic treatments are often limited by debilitating side effects. In PD, locus coeruleus noradrenergic (LC-NE) neurons degenerate prior to substantia nigra dopaminergic (SN-DA) neurons. Vagus nerve stimulation (VNS) activates LC neurons, and decreases pro-inflammatory markers, allowing improvement of LC targets, making it a potential PD therapeutic. To assess therapeutic potential of VNS in a PD model. To mimic the progression of PD degeneration, rats received a systemic injection of noradrenergic neurotoxin DSP-4, followed one week later by bilateral intrastriatal injection of dopaminergic neurotoxin 6-hydroxydopamine. At this time, a subset of rats also had vagus cuffs implanted. After eleven days, rats received a precise VNS regimen twice a day for ten days, and locomotion was measured during each afternoon session. Immediately following final stimulation, rats were euthanized, and left dorsal striatum, bilateral SN and LC were sectioned for immunohistochemical detection of monoaminergic neurons (tyrosine hydroxylase, TH), α-synuclein, astrocytes (GFAP) and microglia (Iba-1). VNS significantly increased locomotion of lesioned rats. VNS also resulted in increased expression of TH in striatum, SN, and LC; decreased SN α-synuclein expression; and decreased expression of glial markers in the SN and LC of lesioned rats. Additionally, saline-treated rats after VNS, had higher LC TH and lower SN Iba-1. Our findings of increased locomotion, beneficial effects on LC-NE and SN-DA neurons, decreased α-synuclein density in SN TH-positive neurons, and neuroinflammation suggest VNS has potential as a novel PD therapeutic. Copyright © 2017 Elsevier Inc. All rights reserved.

Resveratrol Produces Neurotrophic Effects on Cultured Dopaminergic Neurons through Prompting Astroglial BDNF and GDNF Release

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Feng Zhang

2012-01-01

Full Text Available Increasing evidence indicated astroglia-derived neurotrophic factors generation might hold a promising therapy for Parkinson’s disease (PD. Resveratrol, naturally present in red wine and grapes with potential benefit for health, is well known to possess a number of pharmacological activities. Besides the antineuroinflammatory properties, we hypothesized the neuroprotective potency of resveratrol is partially due to its additional neurotrophic effects. Here, primary rat midbrain neuron-glia cultures were applied to investigate the neurotrophic effects mediated by resveratrol on dopamine (DA neurons and further explore the role of neurotrophic factors in its actions. Results showed resveratrol produced neurotrophic effects on cultured DA neurons. Additionally, astroglia-derived neurotrophic factors release was responsible for resveratrol-mediated neurotrophic properties as evidenced by the following observations: (1 resveratrol failed to exert neurotrophic effects on DA neurons in the cultures without astroglia; (2 the astroglia-conditioned medium prepared from astroglia-enriched cultures treated with resveratrol produced neurotrophic effects in neuron-enriched cultures; (3 resveratrol increased neurotrophic factors release in the concentration- and time-dependent manners; (4 resveratrol-mediated neurotrophic effects were suppressed by blocking the action of the neurotrophic factors. Together, resveratrol could produce neurotrophic effects on DA neurons through prompting neurotrophic factors release, and these effects might open new alternative avenues for neurotrophic factor-based therapy targeting PD.

Combinatorial programming of human neuronal progenitors using magnetically-guided stoichiometric mRNA delivery.

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Azimi, Sayyed M; Sheridan, Steven D; Ghannad-Rezaie, Mostafa; Eimon, Peter M; Yanik, Mehmet Fatih

2018-05-01

Identification of optimal transcription-factor expression patterns to direct cellular differentiation along a desired pathway presents significant challenges. We demonstrate massively combinatorial screening of temporally-varying mRNA transcription factors to direct differentiation of neural progenitor cells using a dynamically-reconfigurable magnetically-guided spotting technology for localizing mRNA, enabling experiments on millimetre size spots. In addition, we present a time-interleaved delivery method that dramatically reduces fluctuations in the delivered transcription-factor copy-numbers per cell. We screened combinatorial and temporal delivery of a pool of midbrain-specific transcription factors to augment the generation of dopaminergic neurons. We show that the combinatorial delivery of LMX1A, FOXA2 and PITX3 is highly effective in generating dopaminergic neurons from midbrain progenitors. We show that LMX1A significantly increases TH -expression levels when delivered to neural progenitor cells either during proliferation or after induction of neural differentiation, while FOXA2 and PITX3 increase expression only when delivered prior to induction, demonstrating temporal dependence of factor addition. © 2018, Azimi et al.

Wnts enhance neurotrophin-induced neuronal differentiation in adult bone-marrow-derived mesenchymal stem cells via canonical and noncanonical signaling pathways.

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Hung-Li Tsai

Full Text Available Wnts were previously shown to regulate the neurogenesis of neural stem or progenitor cells. Here, we explored the underlying molecular mechanisms through which Wnt signaling regulates neurotrophins (NTs in the NT-induced neuronal differentiation of human mesenchymal stem cells (hMSCs. NTs can increase the expression of Wnt1 and Wnt7a in hMSCs. However, only Wnt7a enables the expression of synapsin-1, a synaptic marker in mature neurons, to be induced and triggers the formation of cholinergic and dopaminergic neurons. Human recombinant (hrWnt7a and general neuron makers were positively correlated in a dose- and time-dependent manner. In addition, the expression of synaptic markers and neurites was induced by Wnt7a and lithium, a glycogen synthase kinase-3β inhibitor, in the NT-induced hMSCs via the canonical/β-catenin pathway, but was inhibited by Wnt inhibitors and frizzled-5 (Frz5 blocking antibodies. In addition, hrWnt7a triggered the formation of cholinergic and dopaminergic neurons via the non-canonical/c-jun N-terminal kinase (JNK pathway, and the formation of these neurons was inhibited by a JNK inhibitor and Frz9 blocking antibodies. In conclusion, hrWnt7a enhances the synthesis of synapse and facilitates neuronal differentiation in hMSCS through various Frz receptors. These mechanisms may be employed widely in the transdifferentiation of other adult stem cells.

Enduring, Sexually Dimorphic Impact of In Utero Exposure to Elevated Levels of Glucocorticoids on Midbrain Dopaminergic Populations

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Glenda E. Gillies

2016-12-01

Full Text Available Glucocorticoid hormones (GCs released from the fetal/maternal glands during late gestation are required for normal development of mammalian organs and tissues. Accordingly, synthetic glucocorticoids have proven to be invaluable in perinatal medicine where they are widely used to accelerate fetal lung maturation when there is risk of pre-term birth and to promote infant survival. However, clinical and pre-clinical studies have demonstrated that inappropriate exposure of the developing brain to elevated levels of GCs, either as a result of clinical over-use or after stress-induced activation of the fetal/maternal adrenal cortex, is linked with significant effects on brain structure, neurological function and behaviour in later life. In order to understand the underlying neural processes, particular interest has focused on the midbrain dopaminergic systems, which are critical regulators of normal adaptive behaviours, cognitive and sensorimotor functions. Specifically, using a rodent model of GC exposure in late gestation (approximating human brain development at late second/early third trimester, we demonstrated enduring effects on the shape and volume of the ventral tegmental area (VTA and substantia nigra pars compacta (SNc (origins of the mesocorticolimbic and nigrostriatal dopaminergic pathways on the topographical organisation and size of the dopaminergic neuronal populations and astrocytes within these nuclei and on target innervation density and neurochemical markers of dopaminergic transmission (receptors, transporters, basal and amphetamine-stimulated dopamine release at striatal and prefrontal cortical sites that impact on the adult brain. The effects of antenatal GC treatment (AGT were both profound and sexually-dimorphic, not only in terms of quantitative change but also qualitatively, with several parameters affected in the opposite direction in males and females. Although such substantial neurobiological changes might presage marked

Neuroprotective Effects of Cuscutae Semen in a Mouse Model of Parkinson’s Disease

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Minsook Ye

2014-01-01

Full Text Available Parkinson’s disease (PD is a neurodegenerative movement disorder that is characterized by the progressive degeneration of the dopaminergic (DA pathway. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP causes damage to the DA neurons, and 1-4-methyl-4-phenylpyridinium (MPP+ causes cell death in differentiated PC12 cells that is similar to the degeneration that occurs in PD. Moreover, MPTP treatment increases the activity of the brain’s immune cells, reactive oxygen species- (ROS- generating processes, and glutathione peroxidase. We recently reported that Cuscutae Semen (CS, a widely used traditional herbal medicine, increases cell viability in a yeast model of PD. In the present study, we examined the inhibitory effect of CS on the neurotoxicity of MPTP in mice and on the MPP+-induced cell death in differentiated PC12 cells. The MPTP-induced loss of nigral DA neurons was partly inhibited by CS-mediated decreases in ROS generation. The activation of microglia was slightly inhibited by CS, although this effect did not reach statistical significance. Furthermore, CS may reduce the MPP+ toxicity in PC12 cells by suppressing glutathione peroxidase activation. These results suggest that CS may be beneficial for the treatment of neurodegenerative diseases such as PD.

VPS35 Deficiency or Mutation Causes Dopaminergic Neuronal Loss by Impairing Mitochondrial Fusion and Function

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Fu-Lei Tang

2015-09-01

Full Text Available Vacuolar protein sorting-35 (VPS35 is a retromer component for endosomal trafficking. Mutations of VPS35 have been linked to familial Parkinson’s disease (PD. Here, we show that specific deletion of the VPS35 gene in dopamine (DA neurons resulted in PD-like deficits, including loss of DA neurons and accumulation of α-synuclein. Intriguingly, mitochondria became fragmented and dysfunctional in VPS35-deficient DA neurons, phenotypes that could be restored by expressing VPS35 wild-type, but not PD-linked mutant. Concomitantly, VPS35 deficiency or mutation increased mitochondrial E3 ubiquitin ligase 1 (MUL1 and, thus, led to mitofusin 2 (MFN2 degradation and mitochondrial fragmentation. Suppression of MUL1 expression ameliorated MFN2 reduction and DA neuron loss but not α-synuclein accumulation. These results provide a cellular mechanism for VPS35 dysfunction in mitochondrial impairment and PD pathogenesis.

Inhibition of Cathepsins B Induces Neuroprotection Against Secondary Degeneration in Ipsilateral Substantia Nigra After Focal Cortical Infarction in Adult Male Rats

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Xialin Zuo

2018-05-01

Full Text Available Stroke is the leading cause of adult disability in the world. In general, recovery from stroke is incomplete. Accumulating evidences have shown that focal cerebral infarction leads to dynamic trans-neuronal degeneration in non-ischemic remote brain regions, with the disruption of connections to synapsed neurons sustaining ischemic insults. Previously, we had reported that the ipsilateral striatum, thalamus degenerated in succession after permanent distal branch of middle cerebral artery occlusion (dMCAO in Sprague-Dawley (SD rats and cathepsin (Cath B was activated before these relay degeneration. Here, we investigate the role of CathB in the secondary degeneration of ipsilateral substantia nigra (SN after focal cortical infarction. We further examined whether the inhibition of CathB with L-3-trans-(Propyl-carbamoyloxirane-2-carbonyl-L-isoleucyl-L-proline methyl ester (CA-074Me would attenuate secondary degeneration through enhancing the cortico-striatum-nigral connections and contribute to the neuroprotective effects. Our results demonstrated that secondary degeneration in the ipsilateral SN occurred and CathB was upregulated in the ipsilateral SN after focal cortical infarction. The inhibition of CathB with CA-074Me reduced the neuronal loss and gliosis in the ipsilateral SN. Using biotinylated dextran amine (BDA or pseudorabies virus (PRV 152 as anterograde or retrograde tracer to trace striatum-nigral and cortico-nigral projections pathway, CA-074Me can effectively enhance the cortico-striatum-nigral connections and exert neuroprotection against secondary degeneration in the ipsilateral SN after cortical ischemia. Our study suggests that the lysosomal protease CathB mediates the secondary damage in the ipsilateral SN after dMCAO, thus it can be a promising neuroprotective target for the rehabilitation of stroke patients.

BNN-20, a synthetic microneurotrophin, strongly protects dopaminergic neurons in the "weaver" mouse, a genetic model of dopamine-denervation, acting through the TrkB neurotrophin receptor.

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Botsakis, Konstantinos; Mourtzi, Theodora; Panagiotakopoulou, Vasiliki; Vreka, Malamati; Stathopoulos, Georgios T; Pediaditakis, Iosif; Charalampopoulos, Ioannis; Gravanis, Achilleas; Delis, Foteini; Antoniou, Katerina; Zisimopoulos, Dimitrios; Georgiou, Christos D; Panagopoulos, Nikolaos T; Matsokis, Nikolaos; Angelatou, Fevronia

2017-07-15

Neurotrophic factors are among the most promising treatments aiming at slowing or stopping and even reversing Parkinson's disease (PD). However, in most cases, they cannot readily cross the human blood-brain-barrier (BBB). Herein, we propose as a therapeutic for PD the small molecule 17-beta-spiro-[5-androsten-17,2'-oxiran]-3beta-ol (BNN-20), a synthetic analogue of DHEA, which crosses the BBB and is deprived of endocrine side-effects. Using the "weaver" mouse, a genetic model of PD, which exhibits progressive dopaminergic neurodegeneration in the Substantia Nigra (SN), we have shown that long-term administration (P1-P21) of BNN-20 almost fully protected the dopaminergic neurons and their terminals, via i) a strong anti-apoptotic effect, probably mediated through the Tropomyosin receptor kinase B (TrkB) neurotrophin receptor's PI3K-Akt-NF-κB signaling pathway, ii) by exerting an efficient antioxidant effect, iii) by inducing significant anti-inflammatory activity and iv) by restoring Brain-Derived Neurotrophic Factor (BDNF) levels. By intercrossing "weaver" with NGL mice (dual GFP/luciferase-NF-κΒ reporter mice, NF-κΒ.GFP.Luc), we obtained Weaver/NGL mice that express the NF-κB reporter in all somatic cells. Acute BNN-20 administration to Weaver/NGL mice induced a strong NF-κB-dependent transcriptional response in the brain as detected by bioluminescence imaging, which was abolished by co-administration of the TrkB inhibitor ANA-12. This indicates that BNN-20 exerts its beneficial action (at least in part) through the TrkB-PI3K-Akt-NF-κB signaling pathway. These results could be of clinical relevance, as they suggest BNN-20 as an important neuroprotective agent acting through the TrkB neurotrophin receptor pathway, mimicking the action of the endogenous neurotrophin BDNF. Thus BNN-20 could be proposed for treatment of PD. Copyright © 2017. Published by Elsevier Ltd.

Cell type-specific gene expression of midbrain dopaminergic neurons reveals molecules involved in their vulnerability and protection.

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Chung, Chee Yeun; Seo, Hyemyung; Sonntag, Kai Christian; Brooks, Andrew; Lin, Ling; Isacson, Ole

2005-07-01

Molecular differences between dopamine (DA) neurons may explain why the mesostriatal DA neurons in the A9 region preferentially degenerate in Parkinson's disease (PD) and toxic models, whereas the adjacent A10 region mesolimbic and mesocortical DA neurons are relatively spared. To characterize innate physiological differences between A9 and A10 DA neurons, we determined gene expression profiles in these neurons in the adult mouse by laser capture microdissection, microarray analysis and real-time PCR. We found 42 genes relatively elevated in A9 DA neurons, whereas 61 genes were elevated in A10 DA neurons [> 2-fold; false discovery rate (FDR) neurotoxic or protective biochemical pathways. Three A9-elevated molecules [G-protein coupled inwardly rectifying K channel 2 (GIRK2), adenine nucleotide translocator 2 (ANT-2) and the growth factor IGF-1] and three A10-elevated peptides (GRP, CGRP and PACAP) were further examined in both alpha-synuclein overexpressing PC12 (PC12-alphaSyn) cells and rat primary ventral mesencephalic (VM) cultures exposed to MPP+ neurotoxicity. GIRK2-positive DA neurons were more vulnerable to MPP+ toxicity and overexpression of GIRK2 increased the vulnerability of PC12-alphaSyn cells to the toxin. Blocking of ANT decreased vulnerability to MPP+ in both cell culture systems. Exposing cells to IGF-1, GRP and PACAP decreased vulnerability of both cell types to MPP+, whereas CGRP protected PC12-alphaSyn cells but not primary VM DA neurons. These results indicate that certain differentially expressed molecules in A9 and A10 DA neurons may play key roles in their relative vulnerability to toxins and PD.

Compensatory weight gain due to dopaminergic hypofunction: new evidence and own incidental observations

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Bohr Iwo

2008-12-01

Full Text Available Abstract There is increasing evidence for a role of dopamine in the development of obesity. More specifically, dopaminergic hypofunction might lead to (overcompensatory food intake. Overeating and resulting weight gain may be induced by genetic predisposition for lower dopaminergic activity, but might also be a behavioral mechanism of compensating for decreased dopamine signaling after dopaminergic overstimulation, for example after smoking cessation or overconsumption of high palatable food. This hypothesis is in line with our incidental finding of increased weight gain after discontinuation of pharmaceutical dopaminergic overstimulation in rats. These findings support the crucial role of dopaminergic signaling for eating behaviors and offer an explanation for weight-gain after cessation of activities associated with high dopaminergic signaling. They further support the possibility that dopaminergic medication could be used to moderate food intake.

Mesocortical dopaminergic function and human cognition

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Weinberger, D.R.; Berman, K.F.; Chase, T.N.

1988-01-01

In summary, we have reviewed rCBF data in humans that suggest that mesoprefrontal dopaminergic activity is involved in human cognition. In patients with Parkinson's disease and possibly in patients with schizophrenia, prefrontal physiological activation during a cognitive task that appears to depend on prefrontal neural systems correlates positively with cognitive performance on the task and with clinical signs of dopaminergic function. It may be possible in the future to examine prefrontal dopamine metabolism directly during prefrontal cognition using positron emission tomography and tracers such as F-18 DOPA. 21 references

Dopaminergic Polymorphisms, Academic Achievement, and Violent Delinquency.

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Yun, Ilhong; Lee, Julak; Kim, Seung-Gon

2015-12-01

Recent research in the field of educational psychology points to the salience of self-control in accounting for the variance in students' report card grades. At the same time, a novel empirical study from molecular genetics drawing on the National Longitudinal Study of Adolescent Health (Add Health) data has revealed that polymorphisms in three dopaminergic genes (dopamine transporter [DAT1], dopamine D2 receptor [DRD2], and dopamine D4 receptor [DRD4]) are also linked to adolescents' grade point averages (GPAs). Juxtaposing these two lines of research, the current study reanalyzed the Add Health genetic subsample to assess the relative effects of these dopaminergic genes and self-control on GPAs. The results showed that the effects of the latter were far stronger than those of the former. The interaction effects between the dopaminergic genes and a set of environmental factors on academic performance were also examined, producing findings that are aligned with the "social push hypothesis" in behavioral genetics. Finally, based on the criminological literature on the link between academic performance and delinquency, we tested whether dopaminergic effects on violent delinquency were mediated by GPAs. The results demonstrated that academic performance fully mediated the linkage between these genes and violent delinquency. © The Author(s) 2014.

Dopaminergic profile of new heterocyclic N-phenylpiperazine derivatives

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Neves G.

2003-01-01

Full Text Available Dopamine constitutes about 80% of the content of central catecholamines and has a crucial role in the etiology of several neuropsychiatric disorders, including Parkinson's disease, depression and schizophrenia. Several dopaminergic drugs are used to treat these pathologies, but many problems are attributed to these therapies. Within this context, the search for new more efficient dopaminergic agents with less adverse effects represents a vast research field. The aim of the present study was to report the structural design of two N-phenylpiperazine derivatives, compound 4: 1-[1-(4-chlorophenyl-1H-4-pyrazolylmethyl]-4-phenylhexahydropyrazine and compound 5: 1-[1-(4-chlorophenyl-1H-1,2,3-triazol-4-ylmethyl]-4-phenylhexahydropyrazine, planned to be dopamine ligands, and their dopaminergic action profile. The two compounds were assayed (dose range of 15-40 mg/kg in three experimental models: 1 blockade of amphetamine (30 mg/kg, ip-induced stereotypy in rats; 2 the catalepsy test in mice, and 3 apomorphine (1 mg/kg, ip-induced hypothermia in mice. Both derivatives induced cataleptic behavior (40 mg/kg, ip and a hypothermic response (30 mg/kg, ip which was not prevented by haloperidol (0.5 mg/kg, ip. Compound 5 (30 mg/kg, ip also presented a synergistic hypothermic effect with apomorphine (1 mg/kg, ip. Only compound 4 (30 mg/kg, ip significantly blocked the amphetamine-induced stereotypy in rats. The N-phenylpiperazine derivatives 4 and 5 seem to have a peculiar profile of action on dopaminergic functions. On the basis of the results of catalepsy and amphetamine-induced stereotypy, the compounds demonstrated an inhibitory effect on dopaminergic behaviors. However, their hypothermic effect is compatible with the stimulation of dopaminergic function which seems not to be mediated by D2/D3 receptors.

Dopaminergic Modulation of Medial Prefrontal Cortex Deactivation in Parkinson Depression

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Anders H. Andersen

2015-01-01

Full Text Available Parkinson’s disease (PD is associated with emotional abnormalities. Dopaminergic medications ameliorate Parkinsonian motor symptoms, but less is known regarding the impact of dopaminergic agents on affective processing, particularly in depressed PD (dPD patients. The aim of this study was to examine the effects of dopaminergic pharmacotherapy on brain activation to emotional stimuli in depressed versus nondepressed Parkinson disease (ndPD patients. Participants included 18 ndPD patients (11 men, 7 women and 10 dPD patients (7 men, 3 women. Patients viewed photographs of emotional faces during functional MRI. Scans were performed while the patient was taking anti-Parkinson medication and the day after medication had been temporarily discontinued. Results indicate that dopaminergic medications have opposite effects in the prefrontal cortex depending upon depression status. DPD patients show greater deactivation in the ventromedial prefrontal cortex (VMPFC on dopaminergic medications than off, while ndPD patients show greater deactivation in this region off drugs. The VMPFC is in the default-mode network (DMN. DMN activity is negatively correlated with activity in brain systems used for external visual attention. Thus dopaminergic medications may promote increased attention to external visual stimuli among dPD patients but impede normal suppression of DMN activity during external stimulation among ndPD patients.

Prevention of dopaminergic neurotoxicity by targeting nitric oxide and peroxynitrite: implications for the prevention of methamphetamine-induced neurotoxic damage.

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Imam, S Z; Islam, F; Itzhak, Y; Slikker, W; Ali, S F

2000-09-01

Methamphetamine (METH) is a neurotoxic psychostimulant that produces catecholaminergic brain damage by producing oxidative stress and free radical generation. The role of oxygen and nitrogen radicals is well documented as a cause of METH-induced neurotoxic damage. In this study, we have obtained evidence that METH-induced neurotoxicity is the resultant of interaction between oxygen and nitrogen radicals, and it is mediated by the production of peroxynitrite. We have also assessed the effects of inhibitors of neuronal nitric oxide synthase (nNOS) as well as scavenger of nitric oxide and a peroxynitrite decomposition catalyst. Significant protective effects were observed with the inhibitor of nNOS, 7-nitroindazole (7-NI), as well as by the selective peroxynitrite scavenger or decomposition catalyst, 5,10,15,20-tetrakis(2,4,6-trimethyl-3,5-sulfonatophenyl)porphyrinato iron III (FeTPPS). However, the use of a nitric oxide scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), did not provide any significant protection against METH-induced hyperthermia or peroxynitrite generation and the resulting dopaminergic neurotoxicity. In particular, treatment with FeTPPS completely prevented METH-induced hyperthermia, peroxynitrite production, and METH-induced dopaminergic depletion. Together, these data demonstrate that METH-induced dopaminergic neurotoxicity is mediated by the generation of peroxynitrite, which can be selectively protected by nNOS inhibitors or peroxynitrite scavenger or decomposition catalysts.

Midbrain dopamine neurons associated with reward processing innervate the neurogenic subventricular zone.

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Lennington, Jessica B; Pope, Sara; Goodheart, Anna E; Drozdowicz, Linda; Daniels, Stephen B; Salamone, John D; Conover, Joanne C

2011-09-14

Coordinated regulation of the adult neurogenic subventricular zone (SVZ) is accomplished by a myriad of intrinsic and extrinsic factors. The neurotransmitter dopamine is one regulatory molecule implicated in SVZ function. Nigrostriatal and ventral tegmental area (VTA) midbrain dopamine neurons innervate regions adjacent to the SVZ, and dopamine synapses are found on SVZ cells. Cell division within the SVZ is decreased in humans with Parkinson's disease and in animal models of Parkinson's disease following exposure to toxins that selectively remove nigrostriatal neurons, suggesting that dopamine is critical for SVZ function and nigrostriatal neurons are the main suppliers of SVZ dopamine. However, when we examined the aphakia mouse, which is deficient in nigrostriatal neurons, we found no detrimental effect to SVZ proliferation or organization. Instead, dopamine innervation of the SVZ tracked to neurons at the ventrolateral boundary of the VTA. This same dopaminergic neuron population also innervated the SVZ of control mice. Characterization of these neurons revealed expression of proteins indicative of VTA neurons. Furthermore, exposure to the neurotoxin MPTP depleted neurons in the ventrolateral VTA and resulted in decreased SVZ proliferation. Together, these results reveal that dopamine signaling in the SVZ originates from a population of midbrain neurons more typically associated with motivational and reward processing.

BC-Box Motif-Mediated Neuronal Differentiation of Somatic Stem Cells

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Hiroshi Kanno

2018-02-01

Full Text Available Von Hippel-Lindau tumor suppressor protein (pVHL functions to induce neuronal differentiation of neural stem/progenitor cells (NSCs and skin-derived precursors (SKPs. Here we identified a neuronal differentiation domain (NDD in pVHL. Neuronal differentiation of SKPs was induced by intracellular delivery of a peptide composed of the amino-acid sequences encoded by the NDD. Neuronal differentiation mediated by the NDD was caused by the binding between it and elongin C followed by Janus kinase-2 (JAK2 ubiquitination of JAK2 and inhibition of the JAK2/the signal transducer and activator of transcription-3(STAT3 pathway. The NDD in pVHL contained the BC-box motif ((A,P,S,TLXXX (A,C XXX(A,I,L,V corresponding to the binding site of elongin C. Therefore, we proposed that other BC-box proteins might also contain an NDD; and subsequently also identified in them an NDD containing the amino-acid sequence encoded by the BC-box motif in BC-box proteins. Furthermore, we showed that different NDD peptide-delivered cells differentiated into different kinds of neuron-like cells. That is, dopaminergic neuron-like cells, cholinergic neuron-like cells, GABAnergic neuron-like cells or rhodopsin-positive neuron-like cells were induced by different NDD peptides. These novel findings might contribute to the development of a new method for promoting neuronal differentiation and shed further light on the mechanism of neuronal differentiation of somatic stem cells.

Reward-modulated motor information in identified striatum neurons.

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Isomura, Yoshikazu; Takekawa, Takashi; Harukuni, Rie; Handa, Takashi; Aizawa, Hidenori; Takada, Masahiko; Fukai, Tomoki

2013-06-19

It is widely accepted that dorsal striatum neurons participate in either the direct pathway (expressing dopamine D1 receptors) or the indirect pathway (expressing D2 receptors), controlling voluntary movements in an antagonistically balancing manner. The D1- and D2-expressing neurons are activated and inactivated, respectively, by dopamine released from substantia nigra neurons encoding reward expectation. However, little is known about the functional representation of motor information and its reward modulation in individual striatal neurons constituting the two pathways. In this study, we juxtacellularly recorded the spike activity of single neurons in the dorsolateral striatum of rats performing voluntary forelimb movement in a reward-predictable condition. Some of these neurons were identified morphologically by a combination of juxtacellular visualization and in situ hybridization for D1 mRNA. We found that the striatal neurons exhibited distinct functional activations before and during the forelimb movement, regardless of the expression of D1 mRNA. They were often positively, but rarely negatively, modulated by expecting a reward for the correct motor response. The positive reward modulation was independent of behavioral differences in motor performance. In contrast, regular-spiking and fast-spiking neurons in any layers of the motor cortex displayed only minor and unbiased reward modulation of their functional activation in relation to the execution of forelimb movement. Our results suggest that the direct and indirect pathway neurons cooperatively rather than antagonistically contribute to spatiotemporal control of voluntary movements, and that motor information is subcortically integrated with reward information through dopaminergic and other signals in the skeletomotor loop of the basal ganglia.

Adrenal androgen secretion and dopaminergic activity in anorexia nervosa.

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Devesa, J; Pérez-Fernández, R; Bokser, L; Gaudiero, G J; Lima, L; Casanueva, F F

1988-01-01

The aim of the present study was to investigate if the postulated deficient adrenal androgen secretion in Anorexia Nervosa (AN), could be associated with a status of sustained dopaminergic hyperactivity. The adrenal responses to ACTH and PRL response to dopaminergic receptor blockade were studied in seven patients with Anorexia Nervosa and seven regularly menstruating women. AN patients showed lower baseline DHEA-sulphate (DHEA-S), androstenedione (Adione) and prolactin (PRL) levels than controls. The response to ACTH revealed evidences of significantly decreased 17-20 desmolase activity in AN, with apparent predominance of glucocorticoid over androgenic pathways relative to controls. Because dopaminergic receptor blockade with Domperidone (DOM) showed intense dopaminergic hyperactivity in AN, we postulate that the adrenal regression seen in the disease is the consequence of a reduced zona reticularis as a consequence of the lack of trophic support by PRL and/or intermediate lobe proopiomelanocortin (IL-POMC). This is consistent with our previous results in pre-adrenarchal dogs and rabbits.

Methamphetamine-induced neurotoxicity linked to UPS dysfunction and autophagy related changes that can be modulated by PKCδ in dopaminergic neuronal cells

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Lin, Mengshien; Shivalingappa, Prashanth Chandramani; Jin, Huajun; Ghosh, Anamitra; Anantharam, Vellareddy; Ali, Syed; Kanthasamy, Anumantha G.; Kanthasamy, Arthi

2012-01-01

A compromised protein degradation machinery has been implicated in methamphetamine (MA)-induced neurodegeneration. However, the signaling mechanisms that induce autophagy and UPS dysfunction are not well understood. The present study investigates the contributions of PKC delta (PKCδ) mediated signaling events in MA-induced autophagy, UPS dysfunction and cell death. Using an in vitro mesencephalic dopaminergic cell culture model, we demonstrate that MA-induced early induction of autophagy is associated with reduction in proteasomal function and concomitant dissipation of mitochondrial membrane potential (MMP), followed by significantly increased of PKCδ activation, caspase-3 activation, accumulation of ubiquitin positive aggregates and microtubule associated light chain-3 (LC3-II) levels. Interestingly, siRNA mediated knockdown of PKCδ or overexpression of cleavage resistant mutant of PKCδ dramatically reduced MA-induced autophagy, proteasomal function, and associated accumulation of ubiquitinated protein aggregates, which closely paralleled cell survival. Importantly, when autophagy was inhibited either pharmacologically (3-MA) or genetically (siRNA mediated silencing of LC3), the dopaminergic cells became sensitized to MA-induced apoptosis through caspase-3 activation. Conversely, overexpression of LC3 partially protected against MA-induced apoptotic cell death, suggesting a neuroprotective role for autophagy in MA-induced neurotoxicity. Notably, rat striatal tissue isolated from MA treated rats also exhibited elevated LC3-II, ubiquitinated protein levels, and PKCδ cleavage. Taken together, our data demonstrate that MA-induced autophagy serves as an adaptive strategy for inhibiting mitochondria mediated apoptotic cell death and degradation of aggregated proteins. Our results also suggest that the sustained activation of PKCδ leads to UPS dysfunction, resulting in the activation of caspase-3 mediated apoptotic cell death in the nigrostriatal dopaminergic

Development of clinical study and application on dopaminergic neurotransmitters and neuroreceptor imaging

International Nuclear Information System (INIS)

Wang Rongfu

2000-01-01

In recent years, the neurotransmitter mapping has been rapidly developed from a lot of fundamental researches to the studies of clinical applications. At present, the dopaminergic neurotransmitter and receptor imaging in the central neurotransmitter mapping study are the most active area including dopaminergic receptor, dopaminergic neurotransmitter and dopaminergic transporter imaging, etc,. The nuclear medicine functional imaging technique with positron emission tomography and single photon emission computed tomography possesses potential advantages in the diagnosis and distinguished diagnosis of neuropsychiatric disorders and movement disorders, and in the study of recognition function

Dopamine suppresses neuronal activity of Helisoma B5 neurons via a D2-like receptor, activating PLC and K channels.

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Zhong, L R; Artinian, L; Rehder, V

2013-01-03

Dopamine (DA) plays fundamental roles as a neurotransmitter and neuromodulator in the central nervous system. How DA modulates the electrical excitability of individual neurons to elicit various behaviors is of great interest in many systems. The buccal ganglion of the freshwater pond snail Helisoma trivolvis contains the neuronal circuitry for feeding and DA is known to modulate the feeding motor program in Helisoma. The buccal neuron B5 participates in the control of gut contractile activity and is surrounded by dopaminergic processes, which are expected to release DA. In order to study whether DA modulates the electrical activity of individual B5 neurons, we performed experiments on physically isolated B5 neurons in culture and on B5 neurons within the buccal ganglion in situ. We report that DA application elicited a strong hyperpolarization in both conditions and turned the electrical activity from a spontaneously firing state to an electrically silent state. Using the cell culture system, we demonstrated that the strong hyperpolarization was inhibited by the D2 receptor antagonist sulpiride and the phospholipase C (PLC) inhibitor U73122, indicating that DA affected the membrane potential of B5 neurons through the activation of a D2-like receptor and PLC. Further studies revealed that the DA-induced hyperpolarization was inhibited by the K channel blockers 4-aminopyridine and tetraethylammonium, suggesting that K channels might serve as the ultimate target of DA signaling. Through its modulatory effect on the electrical activity of B5 neurons, the release of DA in vivo may contribute to a neuronal output that results in a variable feeding motor program. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

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Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China); Wei, Ling [Beijing Center for Physical & Chemical Analysis, Beijing 100089 (China); Liu, Yutong [School of Life Science, Beijing Normal University, Beijing 100875 (China); Liao, Jieying [Department of Translational Medicine, Xiamen Institute of Rare Earth Materials, Chinese Academy of Sciences, Xiamen 361024 (China); Gao, Hui-Ming [Model Animal Research Center of Nanjing University, Nanjing 211800 (China); Zhou, Hui, E-mail: hardhui@gmail.com [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China)

2017-05-01

Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm{sup 2} induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm{sup 2}) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91{sup phox}, p47{sup phox} and p40{sup phox}); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47{sup phox} and p67{sup phox} translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to

Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

International Nuclear Information System (INIS)

Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin; Wei, Ling; Liu, Yutong; Liao, Jieying; Gao, Hui-Ming; Zhou, Hui

2017-01-01

Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm 2 induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm 2 ) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91 phox , p47 phox and p40 phox ); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47 phox and p67 phox translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to oxidative damage to DA neurons. Our

Proliferating cell nuclear antigen binds DNA polymerase-β and mediates 1-methyl-4-phenylpyridinium-induced neuronal death.

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Zhentao Zhang

Full Text Available The mechanisms leading to dopaminergic neuronal loss in the substantia nigra of patients with Parkinson disease (PD remain poorly understood. We recently reported that aberrant DNA replication mediated by DNA polymerase-β (DNA pol-β plays a causal role in the death of postmitotic neurons in an in vitro model of PD. In the present study, we show that both proliferating cell nuclear antigen (PCNA and DNA pol-β are required for MPP(+-induced neuronal death. PCNA binds to the catalytic domain of DNA pol-β in MPP(+-treated neurons and in post-mortem brain tissues of PD patients. The PCNA-DNA pol-β complex is loaded into DNA replication forks and mediates DNA replication in postmitotic neurons. The aberrant DNA replication mediated by the PCNA-DNA pol-β complex induces p53-dependent neuronal cell death. Our results indicate that the interaction of PCNA and DNA pol-β contributes to neuronal death in PD.

GDNF family ligands display distinct action profiles on cultured GABAergic and serotonergic neurons of rat ventral mesencephalon

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Ducray, Angélique; Krebs, Sandra H:; Schaller, Benoft

2006-01-01

the effects of GFLs on other neuronal populations in the VM is essential for their potential application as therapeutic molecules for Parkinson's disease. Hence, in a comparative study, we investigated the effects of GFLs on cell densities and morphological differentiation of gamma-aminobutyric acid......Glial-cell-line-derived neurotrophic factor (GDNF), neurturin (NRTN), artemin (ARTN) and persephin (PSPN), known as the GDNF family ligands (GFLs), influence the development, survival and differentiation of cultured dopaminergic neurons from ventral mesencephalon (VM). Detailed knowledge about......-immunoreactive (GABA-ir) and serotonin-ir (5-HT-ir) neurons in primary cultures of E14 rat VM. We observed that all GFLs [10 ng/ml] significantly increased GABA-ir cell densities (1.6-fold) as well as neurite length/neuron. However, only GDNF significantly increased the number of primary neurites/neuron, and none...

Shikonin protects dopaminergic cell line PC12 against 6-hydroxydopamine-mediated neurotoxicity via both glutathione-dependent and independent pathways and by inhibiting apoptosis.

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Esmaeilzadeh, Emran; Gardaneh, Mossa; Gharib, Ehsan; Sabouni, Farzaneh

2013-08-01

We have investigated the mechanism of shikonin function on protection of dopaminergic neurons against 6-OHDA-induced neurotoxicity. Treatment of rat pheochromocytoma cell line PC12 by serial dilutions of shikonin determined 10 μM of the compound as its optimum concentration for protection saving nearly 70 % of the cells against toxicity. Reverse transcription-PCR analysis of shikonin-treated cells showed threefold increase in mRNA levels of glutathione peroxidase-1 (GPX-1) as a representative component of the intracellular anti-oxidant defense system. To elucidate shikonin-GPX1 relationships and maximize protection, we transduced PC12 cells using recombinant lentivirus vectors that harbored GPX-1 coding sequence. This change upregulated GPX-1 expression, increased peroxidase activity and made neuronal cells resistant to 6-OHDA-mediated toxicity. More importantly, addition of shikonin to GPX1-overexpressing PC12 cells augmented GPX-1 protein content by eightfold leading to fivefold increase of enzymatic activity, 91 % cell survival against neurotoxicity and concomitant increases in intracellular glutathione (GSH) levels. Depletion of intracellular GSH rendered all cell groups highly susceptible to toxicity; however, shikonin was capable of partially saving them. Subsequently, GSH-independent superoxide dismutase mRNA was found upregulated by shikonin. As signs of apoptosis inhibition, the compound upregulated Bcl-2, downregulated Bax, and prevented cell nuclei from undergoing morphological changes typical of apoptosis. Also, a co-staining method demonstrated GPX-1 overexpression significantly increases the percent of live cells that is maximized by shikonin treatment. Our data indicate that shikonin as an antioxidant compound protects dopaminergic neurons against 6-OHDA toxicity and enhances their survival via both glutathione-dependent and direct anti-apoptotic pathways.

In vivo binding of tritiated dopaminergic ligands in mouse brain

International Nuclear Information System (INIS)

Baudry, Michel; Martres, M.-P.; Le Sellin, Michel; Schwartz, J.-C.; Guyon, Anne; Morgat, J.-L.

1977-01-01

The regional distribution of various dopaminergic radiolabelled ligands has been studied in the mouse brain after their intravenous injections. Among them, 3 H-pimozide and, to a lesser extent, 3 H-apomorphine are preferentially accumulated in the striatum, a region rich in dopaminergic receptors, as compared to cerebellum, a region believed not to contain dopaminergic receptors. For 3 H-pimozide, this preferential retention is due to a more rapid disappearance from the cerebellum than from the striatum. Moreover, prior administration of various neuroleptics which do not modify 3 H-pimozide levels recovered in the cerebellum, abolishes the differential retention of 3 H-pimozide in the striatum. These results indicate that the retention of 3 H-pimozide in the brain may be regarded as the sum of two components: a non-specific retention evaluated by 3 H-pimozide level in the cerebellum and the binding to dopaminergic receptors [fr

α-Synuclein-induced dopaminergic neurodegeneration in a rat model of Parkinson's disease occurs independent of ATP13A2 (PARK9).

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Daniel, Guillaume; Musso, Alessandra; Tsika, Elpida; Fiser, Aris; Glauser, Liliane; Pletnikova, Olga; Schneider, Bernard L; Moore, Darren J

2015-01-01

Mutations in the ATP13A2 (PARK9) gene cause early-onset, autosomal recessive Parkinson's disease (PD) and Kufor-Rakeb syndrome. ATP13A2 mRNA is spliced into three distinct isoforms encoding a P5-type ATPase involved in regulating heavy metal transport across vesicular membranes. Here, we demonstrate that three ATP13A2 mRNA isoforms are expressed in the normal human brain and are modestly increased in the cingulate cortex of PD cases. ATP13A2 can mediate protection toward a number of stressors in mammalian cells and can protect against α-synuclein-induced toxicity in cellular and invertebrate models of PD. Using a primary cortical neuronal model combined with lentiviral-mediated gene transfer, we demonstrate that human ATP13A2 isoforms 1 and 2 display selective neuroprotective effects toward toxicity induced by manganese and hydrogen peroxide exposure through an ATPase-independent mechanism. The familial PD mutations, F182L and G504R, abolish the neuroprotective effects of ATP13A2 consistent with a loss-of-function mechanism. We further demonstrate that the AAV-mediated overexpression of human ATP13A2 is not sufficient to attenuate dopaminergic neurodegeneration, neuropathology, and striatal dopamine and motoric deficits induced by human α-synuclein expression in a rat model of PD. Intriguingly, the delivery of an ATPase-deficient form of ATP13A2 (D513N) to the substantia nigra is sufficient to induce dopaminergic neuronal degeneration and motor deficits in rats, potentially suggesting a dominant-negative mechanism of action. Collectively, our data demonstrate a distinct lack of ATP13A2-mediated protection against α-synuclein-induced neurotoxicity in the rat nigrostriatal dopaminergic pathway, and limited neuroprotective capacity overall, and raise doubts about the potential of ATP13A2 as a therapeutic target for PD. Copyright © 2015 Elsevier Inc. All rights reserved.

Decay Accelerating Factor (CD55) Protects Neuronal Cells from Chemical Hypoxia-Induced Injury

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2010-04-09

Pavlakovic G, Isom GE: Dopaminergic neurotoxicity of cyanide: neurochemical, histological and behavioral characterization. Toxicol Appl Pharmacol...provided the original work is properly cited. ResearchDecay accelerating factor (CD55) protects neuronal cells from chemical hypoxia-induced injury...deposition of C3a/C5a and membrane attack complex (MAC or C5b-9) production. The present study investigates the ability of DAF to protect primary cultured

Iron Chelators and Antioxidants Regenerate Neuritic Tree and Nigrostriatal Fibers of MPP+/MPTP-Lesioned Dopaminergic Neurons.

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Pabla Aguirre

Full Text Available Neuronal death in Parkinson's disease (PD is often preceded by axodendritic tree retraction and loss of neuronal functionality. The presence of non-functional but live neurons opens therapeutic possibilities to recover functionality before clinical symptoms develop. Considering that iron accumulation and oxidative damage are conditions commonly found in PD, we tested the possible neuritogenic effects of iron chelators and antioxidant agents. We used three commercial chelators: DFO, deferiprone and 2.2'-dypyridyl, and three 8-hydroxyquinoline-based iron chelators: M30, 7MH and 7DH, and we evaluated their effects in vitro using a mesencephalic cell culture treated with the Parkinsonian toxin MPP+ and in vivo using the MPTP mouse model. All chelators tested promoted the emergence of new tyrosine hydroxylase (TH-positive processes, increased axodendritic tree length and protected cells against lipoperoxidation. Chelator treatment resulted in the generation of processes containing the presynaptic marker synaptophysin. The antioxidants N-acetylcysteine and dymetylthiourea also enhanced axodendritic tree recovery in vitro, an indication that reducing oxidative tone fosters neuritogenesis in MPP+-damaged neurons. Oral administration to mice of the M30 chelator for 14 days after MPTP treatment resulted in increased TH- and GIRK2-positive nigra cells and nigrostriatal fibers. Our results support a role for oral iron chelators as good candidates for the early treatment of PD, at stages of the disease where there is axodendritic tree retraction without neuronal death.

Functional architecture of reward learning in mushroom body extrinsic neurons of larval Drosophila.

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Saumweber, Timo; Rohwedder, Astrid; Schleyer, Michael; Eichler, Katharina; Chen, Yi-Chun; Aso, Yoshinori; Cardona, Albert; Eschbach, Claire; Kobler, Oliver; Voigt, Anne; Durairaja, Archana; Mancini, Nino; Zlatic, Marta; Truman, James W; Thum, Andreas S; Gerber, Bertram

2018-03-16

The brain adaptively integrates present sensory input, past experience, and options for future action. The insect mushroom body exemplifies how a central brain structure brings about such integration. Here we use a combination of systematic single-cell labeling, connectomics, transgenic silencing, and activation experiments to study the mushroom body at single-cell resolution, focusing on the behavioral architecture of its input and output neurons (MBINs and MBONs), and of the mushroom body intrinsic APL neuron. Our results reveal the identity and morphology of almost all of these 44 neurons in stage 3 Drosophila larvae. Upon an initial screen, functional analyses focusing on the mushroom body medial lobe uncover sparse and specific functions of its dopaminergic MBINs, its MBONs, and of the GABAergic APL neuron across three behavioral tasks, namely odor preference, taste preference, and associative learning between odor and taste. Our results thus provide a cellular-resolution study case of how brains organize behavior.

Alpha-synuclein suppression by targeted small interfering RNA in the primate substantia nigra.

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Alison L McCormack

Full Text Available The protein alpha-synuclein is involved in the pathogenesis of Parkinson's disease and other neurodegenerative disorders. Its toxic potential appears to be enhanced by increased protein expression, providing a compelling rationale for therapeutic strategies aimed at reducing neuronal alpha-synuclein burden. Here, feasibility and safety of alpha-synuclein suppression were evaluated by treating monkeys with small interfering RNA (siRNA directed against alpha-synuclein. The siRNA molecule was chemically modified to prevent degradation by exo- and endonucleases and directly infused into the left substantia nigra. Results compared levels of alpha-synuclein mRNA and protein in the infused (left vs. untreated (right hemisphere and revealed a significant 40-50% suppression of alpha-synuclein expression. These findings could not be attributable to non-specific effects of siRNA infusion since treatment of a separate set of animals with luciferase-targeting siRNA produced no changes in alpha-synuclein. Infusion with alpha-synuclein siRNA, while lowering alpha-synuclein expression, had no overt adverse consequences. In particular, it did not cause tissue inflammation and did not change (i the number and phenotype of nigral dopaminergic neurons, and (ii the concentrations of striatal dopamine and its metabolites. The data represent the first evidence of successful anti-alpha-synuclein intervention in the primate substantia nigra and support further development of RNA interference-based therapeutics.

Mechanisms for multiple activity modes of VTA dopamine neurons

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Andrew eOster

2015-07-01

Full Text Available Midbrain ventral segmental area (VTA dopaminergic neurons send numerous projections to cortical and sub-cortical areas, and diffusely release dopamine (DA to their targets. DA neurons display a range of activity modes that vary in frequency and degree of burst firing. Importantly, DA neuronal bursting is associated with a significantly greater degree of DA release than an equivalent tonic activity pattern. Here, we introduce a single compartmental, conductance-based computational model for DA cell activity that captures the behavior of DA neuronal dynamics and examine the multiple factors that underlie DA firing modes: the strength of the SK conductance, the amount of drive, and GABA inhibition. Our results suggest that neurons with low SK conductance fire in a fast firing mode, are correlated with burst firing, and require higher levels of applied current before undergoing depolarization block. We go on to consider the role of GABAergic inhibition on an ensemble of dynamical classes of DA neurons and find that strong GABA inhibition suppresses burst firing. Our studies suggest differences in the distribution of the SK conductance and GABA inhibition levels may indicate subclasses of DA neurons within the VTA. We further identify, that by considering alternate potassium dynamics, the dynamics display burst patterns that terminate via depolarization block, akin to those observed in vivo in VTA DA neurons and in substantia nigra pars compacta DA cell preparations under apamin application. In addition, we consider the generation of transient burst firing events that are NMDA-initiated or elicited by a sudden decrease of GABA inhibition, that is, disinhibition.

Calcium Homeostatasis and Mitochondrial Dysfunction in Dopaminergic Neurons of the Substantia Nigra

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2010-03-01

complex I of the electron transport chain (ETC) [18]; this deficit is specific to PD patients [19] and seems to reflect oxidative damage to complex I...to drive pacemaking, SNc DA neurons also engage ion channels that enable Ca2+ to enter the cyto- plasm [36–38], leading to elevated intracellular Ca2...shown schematically are elements of the tricarboxylic acid (TCA) cycle that produces reducing equivalents for the electron transport chain; complexes I

PKCδ-dependent p47phox activation mediates methamphetamine-induced dopaminergic neurotoxicity.

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Dang, Duy-Khanh; Shin, Eun-Joo; Kim, Dae-Joong; Tran, Hai-Quyen; Jeong, Ji Hoon; Jang, Choon-Gon; Ottersen, Ole Petter; Nah, Seung-Yeol; Hong, Jau-Shyong; Nabeshima, Toshitaka; Kim, Hyoung-Chun

2018-02-01

Protein kinase C (PKC) has been recognized to activate NADPH oxidase (PHOX). However, the interaction between PKC and PHOX in vivo remains elusive. Treatment with methamphetamine (MA) resulted in a selective increase in PKCδ expression out of PKC isoforms. PKCδ co-immunoprecipitated with p47phox, and facilitated phosphorylation and membrane translocation of p47phox. MA-induced increases in PHOX activity and reactive oxygen species were attenuated by knockout of p47phox or PKCδ. In addition, MA-induced impairments in the Nrf-2-related glutathione synthetic system were also mitigated by knockout of p47phox or PKCδ. Glutathione-immunoreactivity was co-localized in Iba-1-labeled microglial cells and in NeuN-labeled neurons, but not in GFAP-labeled astrocytes, reflecting the necessity for self-protection against oxidative stress by mainly microglia. Buthionine-sulfoximine, an inhibitor of glutathione biosynthesis, potentiated microglial activation and pro-apoptotic changes, leading to dopaminergic losses. These neurotoxic processes were attenuated by rottlerin, a pharmacological inhibitor of PKCδ, genetic inhibitions of PKCδ [i.e., PKCδ knockout mice (KO) and PKCδ antisense oligonucleotide (ASO)], or genetic inhibition of p47phox (i.e., p47phox KO or p47phox ASO). Rottlerin did not exhibit any additive effects against the protective activity offered by genetic inhibition of p47phox. Therefore, we suggest that PKCδ is a critical regulator for p47phox activation induced by MA, and that Nrf-2-dependent GSH induction via inhibition of PKCδ or p47phox, is important for dopaminergic protection against MA insult. Copyright © 2017 Elsevier Inc. All rights reserved.

Running wheel exercise enhances recovery from nigrostriatal dopamine injury without inducing neuroprotection.

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O'Dell, S J; Gross, N B; Fricks, A N; Casiano, B D; Nguyen, T B; Marshall, J F

2007-02-09

Forced use of the forelimb contralateral to a unilateral injection of the dopaminergic neurotoxin 6-hydroxydopamine can promote recovery of motor function in that limb and can significantly decrease damage to dopamine terminals. The present study was conducted to determine (1) whether a form of voluntary exercise, wheel running, would improve motor performance in rats with such lesions, and (2) whether any beneficial effects of wheel running are attributable to ameliorating the dopaminergic damage. In experiment 1, rats were allowed to run in exercise wheels or kept in home cages for 2 1/2 weeks, then given stereotaxic infusions of 6-hydroxydopamine into the left striatum. The rats were replaced into their original environments (wheels or home cages) for four additional weeks, and asymmetries in forelimb use were quantified at 3, 10, 17, and 24 days postoperatively. After killing, dopaminergic damage was assessed by both quantifying 3 beta-(4-iodophenyl)tropan-2 beta-carboxylic acid methyl ester ([(125)I]RTI-55) binding to striatal dopamine transporters and counting tyrosine hydroxylase-positive cells in the substantia nigra. Exercised 6-hydroxydopamine-infused rats showed improved motor outcomes relative to sedentary lesioned controls, effects that were most apparent at postoperative days 17 and 24. Despite this behavioral improvement, 6-hydroxydopamine-induced loss of striatal dopamine transporters and tyrosine hydroxylase-positive nigral cells in exercised and sedentary groups did not differ. Since prior studies suggested that forced limb use improves motor performance by sparing nigrostriatal dopaminergic neurons from 6-hydroxydopamine damage, experiment 2 used a combined regimen of forced plus voluntary wheel running. Again, we found that the motor performance of exercised rats improved more rapidly than that of sedentary controls, but that there were no differences between these groups in the damage produced by 6-hydroxydopamine. It appears that voluntary

A microRNA, mir133b, suppresses melanopsin expression mediated by failure dopaminergic amacrine cells in RCS rats.

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Li, Yaochen; Li, Chunshi; Chen, Zhongshan; He, Jianrong; Tao, Zui; Yin, Zheng Qin

2012-03-01

The photopigment melanopsin and melanopsin-containing RGCs (mRGCs or ipRGCs) represent a brand-new and exciting direction in the field of visual field. Although the melanopsin is much less sensitive to light and has far less spatial resolution, mRGCs have the unique ability to project to brain areas by the retinohypothalamic tract (RHT) and communicate directly with the brain. Unfortunately, melanopsin presents lower expression levels in many acute and chronic retinal diseases. The molecular mechanisms underlying melanopsin expression are not yet really understood. MicroRNAs play important roles in the control of development. Most importantly, the link of microRNA biology to a diverse set of cellular processes, ranging from proliferation, apoptosis and malignant transformation to neuronal development and fate specification is emerging. We employed Royal College of Surgeon (RCS) rats as animal model to investigate the underlying molecular mechanism regulating melanopsin expression using a panel of miRNA by quantitative real-time reverse transcription polymerase chain reaction. We identified a microRNA, mir133b, that is specifically expressed in retinal dopaminergic amacrine cells as well as markedly increased expression at early stage during retinal degeneration in RCS rats. The overexpression of mir133b downregulates the important transcription factor Pitx3 expression in dopaminergic amacrine cells in RCS rats retinas and makes amacrine cells stratification deficit in IPL. Furthermore, deficient dopaminergic amacrine cells presented decreased TH expression and dopamine production, which lead to a failure to direct mRGCs dendrite to stratify and enter INL and lead to the reduced correct connections between amacrine cells and mRGCs. Our study suggested that overexpression of mir133b and downregulated Pitx3 suppress maturation and function of dopaminergic amacrine cells, and overexpression of mir133b decreased TH and D2 receptor expression as well as dopamine

Understanding metal homeostasis in primary cultured neurons. Studies using single neuron subcellular and quantitative metallomics.

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Colvin, Robert A; Lai, Barry; Holmes, William R; Lee, Daewoo

2015-07-01

associated with ferritin cages or transferrin receptor endosomes. The iron content and its distribution in puncta were similar in all neuron types studied including primary dopaminergic neurons. In summary, quantitative measurements of steady state metal levels in single primary cultured neurons made possible by SRXRF analyses provide unique information on the relative levels of each metal in neuronal soma and processes, subcellular location of zinc loads, and have confirmed and extended the characterization of heretofore poorly understood cytoplasmic iron puncta.

Resveratrol Protects Dopamine Neurons Against Lipopolysaccharide-Induced Neurotoxicity through Its Anti-Inflammatory Actions

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Zhang, Feng; Shi, Jing-Shan; Zhou, Hui; Wilson, Belinda; Hong, Jau-Shyong

2010-01-01

Parkinson's disease (PD) is the second most common neurodegenerative disease characterized by a progressive loss of dopamine (DA) neurons in the substantia nigra. Accumulating evidence indicates that inhibition of microglia-mediated neuroinflammation may become a reliable protective strategy for PD. Resveratrol, a nonflavonoid polyphenol naturally found in red wine and grapes, has been known to possess antioxidant, anticancer, and anti-inflammatory properties. Although recent studies have shown that resveratrol provided neuroprotective effects against ischemia, seizure, and neurodegenerative disorders, the mechanisms underlying its beneficial effects on dopaminergic neurodegeneration are poorly defined. In this study, rat primary midbrain neuron-glia cultures were used to elucidate the molecular mechanisms underlying resveratrol-mediated neuroprotection. The results clearly demonstrated that resveratrol protected DA neurons against lipopolysaccharide (LPS)-induced neurotoxicity in concentration- and time-dependent manners through the inhibition of microglial activation and the subsequent reduction of proinflammatory factor release. Mechanistically, resveratrol-mediated neuroprotection was attributed to the inhibition of NADPH oxidase. This conclusion is supported by the following observations. First, resveratrol reduced NADPH oxidase-mediated generation of reactive oxygen species. Second, LPS-induced translocation of NADPH oxidase cytosolic subunit p47 to the cell membrane was significantly attenuated by resveratrol. Third and most importantly, resveratrol failed to exhibit neuroprotection in cultures from NADPH oxidase-deficient mice. Furthermore, this neuroprotection was also related to an attenuation of the activation of mitogen-activated protein kinases and nuclear factor-κB signaling pathways in microglia. These findings suggest that resveratrol exerts neuroprotection against LPS-induced dopaminergic neurodegeneration, and NADPH oxidase may be a major player

Methamphetamine- and 1-methyl-4-phenyl- 1,2,3, 6-tetrahydropyridine-induced dopaminergic neurotoxicity in inducible nitric oxide synthase-deficient mice.

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Itzhak, Y; Martin, J L; Ali, S F

1999-12-15

Previous studies have suggested a role for the retrograde messenger, nitric oxide (NO), in methamphetamine (METH)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)- induced dopaminergic neurotoxicity. Since evidence supported the involvement of the neuronal nitric oxide synthase (nNOS) isoform in the dopaminergic neurotoxicity, the present study was undertaken to investigate whether the inducible nitric oxide synthase (iNOS) isoform is also associated with METH- and MPTP-induced neurotoxicity. The administration of METH (5mg/kg x 3) to iNOS deficient mice [homozygote iNOS(-/-)] and wild type mice (C57BL/6) resulted in significantly smaller depletion of striatal dopaminergic markers in the iNOS(-/-) mice compared with the wild-type mice. METH-induced hyperthermia was also significantly lower in the iNOS(-/-) mice than in wild-type mice. In contrast to the outcome of METH administration, MPTP injections (20 mg/kg x 3) resulted in a similar decrease in striatal dopaminergic markers in iNOS(-/-) and wild-type mice. In the set of behavioral experiments, METH-induced locomotor sensitization was investigated. The acute administration of METH (1.0 mg/kg) resulted in the same intensity of locomotor activity in iNOS(-/-) and wild-type mice. Moreover, 68 to 72 h after the exposure to the high-dose METH regimen (5 mg/kg x 3), a marked sensitized response to a challenge injection of METH (1.0 mg/kg) was observed in both the iNOS(-/-) and wild-type mice. The finding that iNOS(-/-) mice were unprotected from MPTP-induced neurotoxicity suggests that the partial protection against METH-induced neurotoxicity observed was primarily associated with the diminished hyperthermic effect of METH seen in the iNOS(-/-) mice. Moreover, in contrast to nNOS deficiency, iNOS deficiency did not affect METH-induced behavioral sensitization. Copyright 1999 Wiley-Liss, Inc.

DIRECT VISUALIZATION OF THE DOPAMINE TRANSPORTER IN CULTURED NEWBORN RAT MIDBRAIN NEURONS USING THE FLUORESCENT COCAINE ANALOGUE JHC 1-64

DEFF Research Database (Denmark)

Rasmussen, Søren; Vægter, Christian Bjerggaard; Cha, J

In this study we have established methods for visualization and tracking of the dopamine transporter (DAT) in cultured dopaminergic neurons in real time using a fluorescent cocaine analogue JHC 1-64 and confocal fluorescence microscopy. The initial binding experiments in HEK 293 cells stably...... 1-64 was prevented by excess concentrations of dopamine, cocaine, mazindol, or RTI-55, whereas the norepinephrine and/or serotonin transporter specific inhibitors desmethylimipramine and citalopram did not affect fluorescent labeling of the neurons. This strongly supports that JHC 1-64 specifically...

Dopaminergic and clinical correlates of pathological gambling in Parkinson's disease

DEFF Research Database (Denmark)

Callesen, Mette Buhl; Hansen, K V; Gjedde, A

2013-01-01

Dopaminergic medication for motor symptoms in Parkinson's disease (PD) recently has been linked with impulse control disorders, including pathological gambling (PG), which affects up to 8% of patients. PG often is considered a behavioral addiction associated with disinhibition, risky decision-mak...... decision-making. Overall, the findings are consistent with the hypothesis of medication-related PG in PD and underscore the importance of taking clinical variables, such as age and personality, into account when patients with PD are medicated, to reduce the risk of PG.......Dopaminergic medication for motor symptoms in Parkinson's disease (PD) recently has been linked with impulse control disorders, including pathological gambling (PG), which affects up to 8% of patients. PG often is considered a behavioral addiction associated with disinhibition, risky decision-making......, and altered striatal dopaminergic neurotransmission. Using [(11)C]raclopride with positron emission tomography, we assessed dopaminergic neurotransmission during Iowa Gambling Task performance. Here we present data from a single patient with PD and concomitant PG. We noted a marked decrease in [(11)C...

A Knockin Reporter Allows Purification and Characterization of mDA Neurons from Heterogeneous Populations

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Ninuo Xia

2017-03-01

Full Text Available Generation of midbrain dopaminergic (mDA neurons from human pluripotent stem cells provides a platform for inquiry into basic and translational studies of Parkinson’s disease (PD. However, heterogeneity in differentiation in vitro makes it difficult to identify mDA neurons in culture or in vivo following transplantation. Here, we report the generation of a human embryonic stem cell (hESC line with a tyrosine hydroxylase (TH-RFP (red fluorescent protein reporter. We validated that RFP faithfully mimicked TH expression during differentiation. Use of this TH-RFP reporter cell line enabled purification of mDA-like neurons from heterogeneous cultures with subsequent characterization of neuron transcriptional and epigenetic programs (global binding profiles of H3K27ac, H3K4me1, and 5-hydroxymethylcytosine [5hmC] at four different stages of development. We anticipate that the tools and data described here will contribute to the development of mDA neurons for applications in disease modeling and/or drug screening and cell replacement therapies for PD.

A Knockin Reporter Allows Purification and Characterization of mDA Neurons from Heterogeneous Populations.

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Xia, Ninuo; Fang, Fang; Zhang, Pengbo; Cui, Jun; Tep-Cullison, Chhavy; Hamerley, Tim; Lee, Hyun Joo; Palmer, Theo; Bothner, Brian; Lee, Jin Hyung; Pera, Renee Reijo

2017-03-07

Generation of midbrain dopaminergic (mDA) neurons from human pluripotent stem cells provides a platform for inquiry into basic and translational studies of Parkinson's disease (PD). However, heterogeneity in differentiation in vitro makes it difficult to identify mDA neurons in culture or in vivo following transplantation. Here, we report the generation of a human embryonic stem cell (hESC) line with a tyrosine hydroxylase (TH)-RFP (red fluorescent protein) reporter. We validated that RFP faithfully mimicked TH expression during differentiation. Use of this TH-RFP reporter cell line enabled purification of mDA-like neurons from heterogeneous cultures with subsequent characterization of neuron transcriptional and epigenetic programs (global binding profiles of H3K27ac, H3K4me1, and 5-hydroxymethylcytosine [5hmC]) at four different stages of development. We anticipate that the tools and data described here will contribute to the development of mDA neurons for applications in disease modeling and/or drug screening and cell replacement therapies for PD. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Pharmacological imaging as a tool to visualise dopaminergic neurotoxicity.

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Schrantee, A; Reneman, L

2014-09-01

Dopamine abnormalities underlie a wide variety of psychopathologies, including ADHD and schizophrenia. A new imaging technique, pharmacological magnetic resonance imaging (phMRI), is a promising non-invasive technique to visualize the dopaminergic system in the brain. In this review we explore the clinical potential of phMRI in detecting dopamine dysfunction or neurotoxicity, assess its strengths and weaknesses and identify directions for future research. Preclinically, phMRI is able to detect severe dopaminergic abnormalities quite similar to conventional techniques such as PET and SPECT. phMRI benefits from its high spatial resolution and the possibility to visualize both local and downstream effects of dopaminergic neurotransmission. In addition, it allows for repeated measurements and assessments in vulnerable populations. The major challenge is the complex interpretation of phMRI results. Future studies in patients with dopaminergic abnormalities need to confirm the currently reviewed preclinical findings to validate the technique in a clinical setting. Eventually, based on the current review we expect that phMRI can be of use in a clinical setting involving vulnerable populations (such as children and adolescents) for diagnosis and monitoring treatment efficacy. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'. Copyright © 2013 Elsevier Ltd. All rights reserved.

Neurotoxicity of "ecstasy" and its metabolites in human dopaminergic differentiated SH-SY5Y cells.

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Ferreira, Patrícia Silva; Nogueira, Tiago Bernandes; Costa, Vera Marisa; Branco, Paula Sério; Ferreira, Luísa Maria; Fernandes, Eduarda; Bastos, Maria Lourdes; Meisel, Andreas; Carvalho, Félix; Capela, João Paulo

2013-02-04

"Ecstasy" (3,4-methylenedioxymethamphetamine or MDMA) is a widely abused recreational drug, reported to produce neurotoxic effects, both in laboratory animals and in humans. MDMA metabolites can be major contributors for MDMA neurotoxicity. This work studied the neurotoxicity of MDMA and its catechol metabolites, α-methyldopamine (α-MeDA) and N-methyl-α-methyldopamine (N-Me-α-MeDA) in human dopaminergic SH-SY5Y cells differentiated with retinoic acid and 12-O-tetradecanoyl-phorbol-13-acetate. Differentiation led to SH-SY5Y neurons with higher ability to accumulate dopamine and higher resistance towards dopamine neurotoxicity. MDMA catechol metabolites were neurotoxic to SH-SY5Y neurons, leading to caspase 3-independent cell death in a concentration- and time-dependent manner. MDMA did not show a concentration- and time-dependent death. Pre-treatment with the antioxidant and glutathione precursor, N-acetylcysteine (NAC), resulted in strong protection against the MDMA metabolites' neurotoxicity. Neither the superoxide radical scavenger, tiron, nor the inhibitor of the dopamine (DA) transporter, GBR 12909, prevented the metabolites' toxicity. Cells exposed to α-MeDA showed an increase in intracellular glutathione (GSH) levels, which, at the 48 h time-point, was not dependent in the activity increase of γ-glutamylcysteine synthetase (γ-GCS), revealing a possible transient effect. Importantly, pre-treatment with buthionine sulfoximine (BSO), an inhibitor of γ-GCS, prevented α-MeDA induced increase in GSH levels, but did not augment this metabolite cytotoxicity. Even so, BSO pre-treatment abolished NAC protective effects against α-MeDA neurotoxicity, which were, at least partially, due to GSH de novo synthesis. Inversely, pre-treatment of cells with BSO augmented N-Me-α-MeDA-induced neurotoxicity, but only slightly affected NAC neuroprotection. In conclusion, MDMA catechol metabolites promote differential toxic effects to differentiated dopaminergic human SH

Functional integration of grafted neural stem cell-derived dopaminergic neurons monitored by optogenetics in an in vitro Parkinson model.

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Jan Tønnesen

Full Text Available Intrastriatal grafts of stem cell-derived dopamine (DA neurons induce behavioral recovery in animal models of Parkinson's disease (PD, but how they functionally integrate in host neural circuitries is poorly understood. Here, Wnt5a-overexpressing neural stem cells derived from embryonic ventral mesencephalon of tyrosine hydroxylase-GFP transgenic mice were expanded as neurospheres and transplanted into organotypic cultures of wild type mouse striatum. Differentiated GFP-labeled DA neurons in the grafts exhibited mature neuronal properties, including spontaneous firing of action potentials, presence of post-synaptic currents, and functional expression of DA D₂ autoreceptors. These properties resembled those recorded from identical cells in acute slices of intrastriatal grafts in the 6-hydroxy-DA-induced mouse PD model and from DA neurons in intact substantia nigra. Optogenetic activation or inhibition of grafted cells and host neurons using channelrhodopsin-2 (ChR2 and halorhodopsin (NpHR, respectively, revealed complex, bi-directional synaptic interactions between grafted cells and host neurons and extensive synaptic connectivity within the graft. Our data demonstrate for the first time using optogenetics that ectopically grafted stem cell-derived DA neurons become functionally integrated in the DA-denervated striatum. Further optogenetic dissection of the synaptic wiring between grafted and host neurons will be crucial to clarify the cellular and synaptic mechanisms underlying behavioral recovery as well as adverse effects following stem cell-based DA cell replacement strategies in PD.

Interaction between the dopaminergic and opioidergic systems in dorsal hippocampus in modulation of formalin-induced orofacial pain in rats.

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Reisi, Zahra; Haghparast, Amir; Pahlevani, Pouyan; Shamsizadeh, Ali; Haghparast, Abbas

2014-09-01

The hippocampus is a region of the brain that serves several functions. The dopaminergic system acts through D1- and D2-like receptors to interfere in pain modulation and the opioid receptors play major roles in analgesic processes and there are obvious overlaps between these two systems. The present study investigated the interaction between the opioidergic and dopaminergic systems in the dorsal hippocampus (CA1) region for formalin-induced orofacial pain. Two guide cannulae were stereotaxically implanted in the CA1 region and morphine (0.5, 1, 2 and 4 μg/0.5 μl saline) and naloxone (0.3, 1 and 3 μg/0.5 μl saline) were used as the opioid receptor agonist and antagonist, respectively. SKF-38393 (1 μg/0.5 μl saline) was used as a D1-like receptor agonist, quinpirole (2 μg/0.5 μl saline) as a D2-like receptor agonist, SCH-23390 (0.5 μg/0.5 μl saline) as a D1-like receptor antagonist and sulpiride (3 μg/0.5 μl DMSO) as a D2-like receptor antagonist. To induce orofacial pain, 50 μl of 1% formalin was subcutaneously injected into the left side of the upper lip. Our results showed that different doses of morphine significantly reduced orofacial pain in both phases induced by formalin. Naloxone (1 and 3 μg) reversed morphine induced analgesia in CA1. SKF-38393 and quinpirole with naloxone (1 μg) significantly decreased formalin-induced orofacial pain in both phases. SCH-23390 had no effect on the antinociceptive response of morphine in both phases of orofacial pain. Sulpiride reversed the antinociceptive effects of morphine only in the first phase, but this result was not significant. Our findings suggest that there is cross-talk between the opioidergic and dopaminergic systems. Opioidergic neurons also exerted antinociceptive effects by modulation of the dopaminergic system in the CA1 region of the brain. Copyright © 2014 Elsevier Inc. All rights reserved.

Generation of Regionally Specified Neural Progenitors and Functional Neurons from Human Embryonic Stem Cells under Defined Conditions

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Agnete Kirkeby

2012-06-01

Full Text Available To model human neural-cell-fate specification and to provide cells for regenerative therapies, we have developed a method to generate human neural progenitors and neurons from human embryonic stem cells, which recapitulates human fetal brain development. Through the addition of a small molecule that activates canonical WNT signaling, we induced rapid and efficient dose-dependent specification of regionally defined neural progenitors ranging from telencephalic forebrain to posterior hindbrain fates. Ten days after initiation of differentiation, the progenitors could be transplanted to the adult rat striatum, where they formed neuron-rich and tumor-free grafts with maintained regional specification. Cells patterned toward a ventral midbrain (VM identity generated a high proportion of authentic dopaminergic neurons after transplantation. The dopamine neurons showed morphology, projection pattern, and protein expression identical to that of human fetal VM cells grafted in parallel. VM-patterned but not forebrain-patterned neurons released dopamine and reversed motor deficits in an animal model of Parkinson's disease.

Neurotrophic effects of growth/differentiation factor 5 in a neuronal cell line

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Toulouse, André; Collins, Grace C.; Sullivan, Aideen M.

2012-01-01

The neurotrophin growth/differentiation factor 5 (GDF5) is studied as a potential therapeutic agent for Parkinson's disease as it is believed to play a role in the development and maintenance of the nigrostriatal system. Progress in understanding the effects of GDF5 on dopaminergic neurones has been hindered by the use of mixed cell populations derived from primary cultures or in vivo experiments, making it difficult to differentiate between direct and indirect effects of GDF5 treatment on ne...

Structural imaging in the presymptomatic stage of genetically determined parkinsonism

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Reetz, Kathrin; Tadic, Vera; Kasten, Meike

2010-01-01

Several genes associated with monogenic forms of Parkinson's disease (PD) have been discovered, opening up new avenues for the investigation of presymptomatic stages of PD. Using voxel-based morphometry in 30 asymptomatic mutation carriers (MC) with mutations in four different genes for PD and 100....... The observed striatal GMV increase might be the common structural correlate of compensatory mechanisms due to the latent dopaminergic deficit, reflecting the different, but probably interrelated pathogenic pathways resulting in nigral cell death. Asymptomatic PINK1 and LRRK2 MC also revealed smaller GMV...

Dopaminergic modulation of the human reward system: a placebo-controlled dopamine depletion fMRI study

NARCIS (Netherlands)

da Silva Alves, Fabiana; Schmitz, Nicole; Figee, Martijn; Abeling, Nico; Hasler, Gregor; van der Meer, Johan; Nederveen, Aart; de Haan, Lieuwe; Linszen, Don; van Amelsvoort, Therese

2011-01-01

Reward related behaviour is linked to dopaminergic neurotransmission. Our aim was to gain insight into dopaminergic involvement in the human reward system. Combining functional magnetic resonance imaging with dopaminergic depletion by α-methylparatyrosine we measured dopamine-related brain activity

3-aminopyridazine derivatives with atypical antidepressant, serotonergic, and dopaminergic activities.

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Wermuth, C G; Schlewer, G; Bourguignon, J J; Maghioros, G; Bouchet, M J; Moire, C; Kan, J P; Worms, P; Biziere, K

1989-03-01

Minaprine [3-[(beta-morpholinoethyl)amino]-4-methyl-6-phenylpyridazine dihydrochloride] is active in most animal models of depression and exhibits in vivo a dual dopaminomimetic and serotoninomimetic activity profile. In an attempt to dissociate these two effects and to characterize the responsible structural requirements, a series of 47 diversely substituted analogues of minaprine were synthesized and tested for their potential antidepressant, serotonergic, and dopaminergic activities. The structure-activity relationships show that dopaminergic and serotonergic activities can be dissociated. Serotonergic activity appears to be correlated mainly with the substituent in the 4-position of the pyridazine ring whereas the dopaminergic activity appears to be dependent on the presence, or in the formation, of a para-hydroxylated aryl ring in the 6-position of the pyridazine ring.

Ketamine Causes Mitochondrial Dysfunction in Human Induced Pluripotent Stem Cell-Derived Neurons

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Ito, Hiroyuki; Uchida, Tokujiro; Makita, Koshi

2015-01-01

Purpose Ketamine toxicity has been demonstrated in nonhuman mammalian neurons. To study the toxic effect of ketamine on human neurons, an experimental model of cultured neurons from human induced pluripotent stem cells (iPSCs) was examined, and the mechanism of its toxicity was investigated. Methods Human iPSC-derived dopaminergic neurons were treated with 0, 20, 100 or 500 μM ketamine for 6 and 24 h. Ketamine toxicity was evaluated by quantification of caspase 3/7 activity, reactive oxygen species (ROS) production, mitochondrial membrane potential, ATP concentration, neurotransmitter reuptake activity and NADH/NAD+ ratio. Mitochondrial morphological change was analyzed by transmission electron microscopy and confocal microscopy. Results Twenty-four-hour exposure of iPSC-derived neurons to 500 μM ketamine resulted in a 40% increase in caspase 3/7 activity (P ketamine (100 μM) decreased the ATP level (22%, P ketamine concentration, which suggests that mitochondrial dysfunction preceded ROS generation and caspase activation. Conclusions We established an in vitro model for assessing the neurotoxicity of ketamine in iPSC-derived neurons. The present data indicate that the initial mitochondrial dysfunction and autophagy may be related to its inhibitory effect on the mitochondrial electron transport system, which underlies ketamine-induced neural toxicity. Higher ketamine concentration can induce ROS generation and apoptosis in human neurons. PMID:26020236

17β-estradiol and tamoxifen protect mice from manganese-induced dopaminergic neurotoxicity.

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Pajarillo, Edward; Johnson, James; Kim, Judong; Karki, Pratap; Son, Deok-Soo; Aschner, Michael; Lee, Eunsook

2018-03-01

Chronic exposure to manganese (Mn) causes neurotoxicity, referred to as manganism, with common clinical features of parkinsonism. 17β-estradiol (E2) and tamoxifen (TX), a selective estrogen receptor modulator (SERM), afford neuroprotection in several neurological disorders, including Parkinson's disease (PD). In the present study, we tested if E2 and TX attenuate Mn-induced neurotoxicity in mice, assessing motor deficit and dopaminergic neurodegeneration. We implanted E2 and TX pellets in the back of the neck of ovariectomized C57BL/6 mice two weeks prior to a single injection of Mn into the striatum. One week later, we assessed locomotor activity and molecular mechanisms by immunohistochemistry, real-time quantitative PCR, western blot and enzymatic biochemical analyses. The results showed that both E2 and TX attenuated Mn-induced motor deficits and reversed the Mn-induced loss of dopaminergic neurons in the substantia nigra. At the molecular level, E2 and TX reversed the Mn-induced decrease of (1) glutamate aspartate transporter (GLAST) and glutamate transporter 1 (GLT-1) mRNA and protein levels; (2) transforming growth factor-α (TGF-α) and estrogen receptor-α (ER-α) protein levels; and (3) catalase (CAT) activity and glutathione (GSH) levels, and Mn-increased (1) malondialdehyde (MDA) levels and (2) the Bax/Bcl-2 ratio. These results indicate that E2 and TX afford protection against Mn-induced neurotoxicity by reversing Mn-reduced GLT1/GLAST as well as Mn-induced oxidative stress. Our findings may offer estrogenic agents as potential candidates for the development of therapeutics to treat Mn-induced neurotoxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

Successful function of autologous iPSC-derived dopamine neurons following transplantation in a non-human primate model of Parkinson's disease

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Hallett, Penelope J; Deleidi, Michela; Astradsson, Arnar

2015-01-01

that unilateral engraftment of CM-iPSCs could provide a gradual onset of functional motor improvement contralateral to the side of dopamine neuron transplantation, and increased motor activity, without a need for immunosuppression. Postmortem analyses demonstrated robust survival of midbrain-like dopaminergic......Autologous transplantation of patient-specific induced pluripotent stem cell (iPSC)-derived neurons is a potential clinical approach for treatment of neurological disease. Preclinical demonstration of long-term efficacy, feasibility, and safety of iPSC-derived dopamine neurons in non-human primate...... models will be an important step in clinical development of cell therapy. Here, we analyzed cynomolgus monkey (CM) iPSC-derived midbrain dopamine neurons for up to 2 years following autologous transplantation in a Parkinson's disease (PD) model. In one animal, with the most successful protocol, we found...

Drosophila Clock Is Required in Brain Pacemaker Neurons to Prevent Premature Locomotor Aging Independently of Its Circadian Function.

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Alexandra Vaccaro

2017-01-01

Full Text Available Circadian clocks control many self-sustained rhythms in physiology and behavior with approximately 24-hour periodicity. In many organisms, oxidative stress and aging negatively impact the circadian system and sleep. Conversely, loss of the clock decreases resistance to oxidative stress, and may reduce lifespan and speed up brain aging and neurodegeneration. Here we examined the effects of clock disruptions on locomotor aging and longevity in Drosophila. We found that lifespan was similarly reduced in three arrhythmic mutants (ClkAR, cyc0 and tim0 and in wild-type flies under constant light, which stops the clock. In contrast, ClkAR mutants showed significantly faster age-related locomotor deficits (as monitored by startle-induced climbing than cyc0 and tim0, or than control flies under constant light. Reactive oxygen species accumulated more with age in ClkAR mutant brains, but this did not appear to contribute to the accelerated locomotor decline of the mutant. Clk, but not Cyc, inactivation by RNA interference in the pigment-dispersing factor (PDF-expressing central pacemaker neurons led to similar loss of climbing performance as ClkAR. Conversely, restoring Clk function in these cells was sufficient to rescue the ClkAR locomotor phenotype, independently of behavioral rhythmicity. Accelerated locomotor decline of the ClkAR mutant required expression of the PDF receptor and correlated to an apparent loss of dopaminergic neurons in the posterior protocerebral lateral 1 (PPL1 clusters. This neuronal loss was rescued when the ClkAR mutation was placed in an apoptosis-deficient background. Impairing dopamine synthesis in a single pair of PPL1 neurons that innervate the mushroom bodies accelerated locomotor decline in otherwise wild-type flies. Our results therefore reveal a novel circadian-independent requirement for Clk in brain circadian neurons to maintain a subset of dopaminergic cells and avoid premature locomotor aging in Drosophila.

D-deprenyl protects nigrostriatal neurons against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced dopaminergic neurotoxicity.

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Muralikrishnan, Dhanasekharan; Samantaray, Supriti; Mohanakumar, Kochupurackal P

2003-10-01

Selegiline (L-deprenyl) is believed to render protection against l-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-neurotoxicity to a significant extent via a free radical scavenging mechanism, which is independent of its ability to inhibit monoamine oxidase-B (MAO-B) in the brain. We investigated the hydroxyl radical (.OH) scavenging action and neuroprotective effect of D-deprenyl, its less active isomer, in MPTP-induced dopaminergic neurotoxicity in mice to test whether the chemical structure of the molecule or its biological effects contribute to this property. To achieve this goal we studied the effects of D-deprenyl on: (1).OH production in a Fenton reaction; (2) MPTP-induced.OH generation and dopamine (DA) depletion in vivo, employing a sensitive HPLC-electrochemical procedure; and (3) formation of MPP(+) in vivo in the striatum following systemic administration of MPTP, employing an HPLC-photodiode array detection system. D-deprenyl inhibited ferrous citrate-induced.OH in vitro (0.45 microM) and MPTP-induced.OH in vivo in substantia nigra (SN) and in the striatum (1.0 mg/kg, i.p.). D-deprenyl did not, but L-deprenyl (0.5 mg/kg dose) did significantly inhibit formation of MPP(+) in the striatum 90 min following systemic MPTP injection. It failed to affect MAO-B activity at 0.5 mg/kg in the striatum, but effectively blocked MPTP-induced striatal DA depletion. The potency of D-deprenyl to scavenge MPTP-induced.OH in vivo and to render protection against the dopaminergic neurotoxicity without affecting dopamine turnover, MAO-B activity, or formation of MPP(+) in the brain indicates a direct involvement of.OH in the neurotoxic action of MPTP and antioxidant effect in the neuroprotective action of deprenyl. Copyright 2003 Wiley-Liss, Inc.

Effects of dopaminergic and subthalamic stimulation on musical performance.

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van Vugt, Floris T; Schüpbach, Michael; Altenmüller, Eckart; Bardinet, Eric; Yelnik, Jérôme; Hälbig, Thomas D

2013-05-01

Although subthalamic-deep brain stimulation (STN-DBS) is an efficient treatment for Parkinson's disease (PD), its effects on fine motor functions are not clear. We present the case of a professional violinist with PD treated with STN-DBS. DBS improved musical articulation, intonation and emotional expression and worsened timing relative to a timekeeper (metronome). The same effects were found for dopaminergic treatment. These results suggest that STN-DBS, mimicking the effects of dopaminergic stimulation, improves fine-tuned motor behaviour whilst impairing timing precision.

Neuroprotective effect of the natural iron chelator, phytic acid in a cell culture model of Parkinson's disease

International Nuclear Information System (INIS)

Xu Qi; Kanthasamy, Anumantha G.; Reddy, Manju B.

2008-01-01

Disrupted iron metabolism and excess iron accumulation has been reported in the brains of Parkinson's disease (PD) patients. Because excessive iron can induce oxidative stress subsequently causing degradation of nigral dopaminergic neurons in PD, we determined the protective effect of a naturally occurring iron chelator, phytic acid (IP6), on 1-methyl-4-phenylpyridinium (MPP + )-induced cell death in immortalized rat mesencephalic/dopaminergic cells. Cell death was induced with MPP + in normal and iron-excess conditions and cytotoxicity was measured by thiazolyl blue tetrazolium bromide (MTT assay) and trypan blue staining. Apoptotic cell death was also measured with caspase-3 activity, DNA fragmentation, and Hoechst nuclear staining. Compared to MPP + treatment, IP6 (30 μmol/L) increased cell viability by 19% (P + treatment was decreased by 55% (P < 0.01) and 52% (P < 0.05), respectively with IP6. Cell survival was increased by 18% (P < 0.05) and 42% (P < 0.001) with 30 and 100 μmol/L of IP6, respectively in iron-excess conditions. A 40% and 52% (P < 0.001) protection was observed in caspase-3 activity with 30 and 100 μmol/L IP6, respectively in iron-excess condition. Similarly, a 45% reduction (P < 0.001) in DNA fragmentation was found with 100 μmol/L IP6. In addition, Hoechst nuclear staining results confirmed the protective effect of IP6 against apoptosis. Similar protection was also observed with the differentiated cells. Collectively, our results demonstrate a significant neuroprotective effect of phytate in a cell culture model of PD

Functional activity of substantia nigra grafts reinnervating the striatum: neurotransmitter metabolism and (14C)2-deoxy-D-glucose autoradiography. [Rats

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Schmidt, R H; Ingvar, M; Lindvall, O; Stenevi, U; Bjoerklund, A

1982-03-01

Dopaminergic innervation of the caudate nucleus in adult rats can be partially restored by the grafting of embryonic substantia nigra into the overlying parietal cortex with concomitant compensation of certain behavioral abnormalities. In this study the function of such grafts was investigated neurochemically by quantification of transmitter metabolism and glucose utilization in the reinnervated target. Rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal bundle received a single graft to the dorsal caudate-putamen and were screened for rotational behavior following 5 mg/kg methamphetamine. The grafts restored dopamine concentrations in the caudate-putamen from initially less than 0.5% to an average of 13.6% of normal in rats with behavioral compensation. The ratio of 3,4-dihydroxyphenylacetic acid to dopamine, which is a measure of the rate of transmitter turnover, were equivalent in transplanted and normal control rats. Moreover, measurements of DOPA accumulation for a 30-min period after DOPA decarboxylase inhibition indicated similar fractional dopamine turnover rates in normal and transplant-reinnervated tissues. Correlations between rotational behavior and dopamine concentrations showed that reinnervation to only 3% of normal was sufficient to counterbalance the motor asymmetry. Measurements of glucose utilization by (14C)deoxyglucose autoradiography indicated equivalent metabolic rates for the grafted tissue and the intact substantia nigra. Overall the results indicate that behaviorally functional neuronal grafts spontaneously metabolize dopamine and utilize glucose at rates characteristic of the intact nigrostriatal system. This provides further evidence that ectopic intracortical nigral transplants can reinstate dopaminergic neurotransmission in regions of the host brain initially denervated by the 6-hydroxydopamine lesion.

Influence of dopaminergically mediated reward on somatosensory decision-making.

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Burkhard Pleger

2009-07-01

Full Text Available Reward-related dopaminergic influences on learning and overt behaviour are well established, but any influence on sensory decision-making is largely unknown. We used functional magnetic resonance imaging (fMRI while participants judged electric somatosensory stimuli on one hand or other, before being rewarded for correct performance at trial end via a visual signal, at one of four anticipated financial levels. Prior to the procedure, participants received either placebo (saline, a dopamine agonist (levodopa, or an antagonist (haloperidol.higher anticipated reward improved tactile decisions. Visually signalled reward reactivated primary somatosensory cortex for the judged hand, more strongly for higher reward. After receiving a higher reward on one trial, somatosensory activations and decisions were enhanced on the next trial. These behavioural and neural effects were all enhanced by levodopa and attenuated by haloperidol, indicating dopaminergic dependency. Dopaminergic reward-related influences extend even to early somatosensory cortex and sensory decision-making.

Drugs of abuse specifically sensitize noradrenergic and serotonergic neurons via a non-dopaminergic mechanism.

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Lanteri, Christophe; Salomon, Lucas; Torrens, Yvette; Glowinski, Jacques; Tassin, Jean-Pol

2008-06-01

A challenge in drug dependence is to delineate long-term neurochemical modifications induced by drugs of abuse. Repeated d-amphetamine was recently shown to disrupt a mutual regulatory link between noradrenergic and serotonergic neurons, thus inducing long-term increased responses to d-amphetamine and para-chloroamphetamine, respectively. We show here that such a sensitization of noradrenergic and serotonergic neurons also occurs following repeated treatment with cocaine, morphine, or alcohol, three compounds belonging to main groups of addictive substances. In all cases, this sensitization is prevented by alpha 1b-adrenergic and 5-HT2A receptors blockade, indicating the critical role of these receptors on long-term effects of drugs of abuse. However, repeated treatments with two non-addictive antidepressants, venlafaxine, and clorimipramine, which nevertheless inhibit noradrenergic and serotonergic reuptake, do not induce noradrenergic and serotonergic neurons sensitization. Similarly, this sensitization does not occur following repeated treatments with a specific inhibitor of dopamine (DA) reuptake, GBR12783. Moreover, we show that the effects of SCH23390, a D1 receptor antagonist known to inhibit development of d-amphetamine behavioral sensitization, are due to its 5-HT2C receptor agonist property. SCH23390 blocks amphetamine-induced release of norepinephrine and RS102221, a 5-HT2C antagonist, can reverse this inhibition as well as inhibition of noradrenergic sensitization and development of behavioral sensitization induced by repeated d-amphetamine. We propose that noradrenergic/serotonergic uncoupling is a common neurochemical consequence of repeated consumption of drugs of abuse, unrelated with DA release. Our data also suggest that compounds able to restore the link between noradrenergic and serotonergic modulatory systems could represent important therapeutic targets for investigation.

The role of MAC1 in diesel exhaust particle-induced microglial activation and loss of dopaminergic neuron function.

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Levesque, Shannon; Taetzsch, Thomas; Lull, Melinda E; Johnson, Jo Anne; McGraw, Constance; Block, Michelle L

2013-06-01

Increasing reports support that air pollution causes neuroinflammation and is linked to central nervous system (CNS) disease/damage. Diesel exhaust particles (DEP) are a major component of urban air pollution, which has been linked to microglial activation and Parkinson's disease-like pathology. To begin to address how DEP may exert CNS effects, microglia and neuron-glia cultures were treated with either nanometer-sized DEP (neuron function was assessed. All three treatments showed enhanced ameboid microglia morphology, increased H2 O2 production, and decreased DA uptake. Mechanistic inquiry revealed that the scavenger receptor inhibitor fucoidan blocked DEP internalization in microglia, but failed to alter DEP-induced H2 O2 production in microglia. However, pre-treatment with the MAC1/CD11b inhibitor antibody blocked microglial H2 O2 production in response to DEP. MAC1(-/-) mesencephalic neuron-glia cultures were protected from DEP-induced loss of DA neuron function, as measured by DA uptake. These findings support that DEP may activate microglia through multiple mechanisms, where scavenger receptors regulate internalization of DEP and the MAC1 receptor is mandatory for both DEP-induced microglial H2 O2 production and loss of DA neuron function. © 2013 International Society for Neurochemistry.

Directed neuronal differentiation of human embryonic stem cells

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Noggle Scott A

2003-10-01

Full Text Available Abstract Background We have developed a culture system for the efficient and directed differentiation of human embryonic stem cells (HESCs to neural precursors and neurons. HESC were maintained by manual passaging and were differentiated to a morphologically distinct OCT-4+/SSEA-4- monolayer cell type prior to the derivation of embryoid bodies. Embryoid bodies were grown in suspension in serum free conditions, in the presence of 50% conditioned medium from the human hepatocarcinoma cell line HepG2 (MedII. Results A neural precursor population was observed within HESC derived serum free embryoid bodies cultured in MedII conditioned medium, around 7–10 days after derivation. The neural precursors were organized into rosettes comprised of a central cavity surrounded by ring of cells, 4 to 8 cells in width. The central cells within rosettes were proliferating, as indicated by the presence of condensed mitotic chromosomes and by phosphoHistone H3 immunostaining. When plated and maintained in adherent culture, the rosettes of neural precursors were surrounded by large interwoven networks of neurites. Immunostaining demonstrated the expression of nestin in rosettes and associated non-neuronal cell types, and a radial expression of Map-2 in rosettes. Differentiated neurons expressed the markers Map-2 and Neurofilament H, and a subpopulation of the neurons expressed tyrosine hydroxylase, a marker for dopaminergic neurons. Conclusion This novel directed differentiation approach led to the efficient derivation of neuronal cultures from HESCs, including the differentiation of tyrosine hydroxylase expressing neurons. HESC were morphologically differentiated to a monolayer OCT-4+ cell type, which was used to derive embryoid bodies directly into serum free conditions. Exposure to the MedII conditioned medium enhanced the derivation of neural precursors, the first example of the effect of this conditioned medium on HESC.

The role of phosphatidylinositol 3-kinase in neural cell adhesion molecule-mediated neuronal differentiation and survival

DEFF Research Database (Denmark)

Ditlevsen, Dorte K; Køhler, Lene B; Pedersen, Martin Volmer

2003-01-01

The neural cell adhesion molecule, NCAM, is known to stimulate neurite outgrowth from primary neurones and PC12 cells presumably through signalling pathways involving the fibroblast growth factor receptor (FGFR), protein kinase A (PKA), protein kinase C (PKC), the Ras-mitogen activated protein...... kinase (MAPK) pathway and an increase in intracellular Ca2+ levels. Stimulation of neurones with the synthetic NCAM-ligand, C3, induces neurite outgrowth through signalling pathways similar to the pathways activated through physiological, homophilic NCAM-stimulation. We present here data indicating...... that phosphatidylinositol 3-kinase (PI3K) is required for NCAM-mediated neurite outgrowth from PC12-E2 cells and from cerebellar and dopaminergic neurones in primary culture, and that the thr/ser kinase Akt/protein kinase B (PKB) is phosphorylated downstream of PI3K after stimulation with C3. Moreover, we present data...

Effects of dopaminergic treatment on functional cortico-cortical connectivity in Parkinson's disease

DEFF Research Database (Denmark)

Zittel, S; Heinbokel, C; van der Vegt, J P M

2015-01-01

under chronic dopaminergic stimulation, but not in de novo PD patients at low stimulus intensities at an ISI of 4 ms. First-time exposure to levodopa exerts different effects on cortico-cortical pathways than chronic dopaminergic stimulation in PD, suggesting a change in the responsiveness of cortico...

Wnt5a regulates midbrain dopaminergic axon growth and guidance.

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Brette D Blakely

2011-03-01

Full Text Available During development, precise temporal and spatial gradients are responsible for guiding axons to their appropriate targets. Within the developing ventral midbrain (VM the cues that guide dopaminergic (DA axons to their forebrain targets remain to be fully elucidated. Wnts are morphogens that have been identified as axon guidance molecules. Several Wnts are expressed in the VM where they regulate the birth of DA neurons. Here, we describe that a precise temporo-spatial expression of Wnt5a accompanies the development of nigrostriatal projections by VM DA neurons. In mice at E11.5, Wnt5a is expressed in the VM where it was found to promote DA neurite and axonal growth in VM primary cultures. By E14.5, when DA axons are approaching their striatal target, Wnt5a causes DA neurite retraction in primary cultures. Co-culture of VM explants with Wnt5a-overexpressing cell aggregates revealed that Wnt5a is capable of repelling DA neurites. Antagonism experiments revealed that the effects of Wnt5a are mediated by the Frizzled receptors and by the small GTPase, Rac1 (a component of the non-canonical Wnt planar cell polarity pathway. Moreover, the effects were specific as they could be blocked by Wnt5a antibody, sFRPs and RYK-Fc. The importance of Wnt5a in DA axon morphogenesis was further verified in Wnt5a-/- mice, where fasciculation of the medial forebrain bundle (MFB as well as the density of DA neurites in the MFB and striatal terminals were disrupted. Thus, our results identify a novel role of Wnt5a in DA axon growth and guidance.

Characterization of A11 neurons projecting to the spinal cord of mice.

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Kathrin Koblinger

Full Text Available The hypothalamic A11 region has been identified in several species including rats, mice, cats, monkeys, zebrafish, and humans as the primary source of descending dopamine (DA to the spinal cord. It has been implicated in the control of pain, modulation of the spinal locomotor network, restless leg syndrome, and cataplexy, yet the A11 cell group remains an understudied dopaminergic (DAergic nucleus within the brain. It is unclear whether A11 neurons in the mouse contain the full complement of enzymes consistent with traditional DA neuronal phenotypes. Given the abundance of mouse genetic models and tools available to interrogate specific neural circuits and behavior, it is critical first to fully understand the phenotype of A11 cells. We provide evidence that, in addition to tyrosine hydroxylase (TH that synthesizes L-DOPA, neurons within the A11 region of the mouse contain aromatic L-amino acid decarboxylase (AADC, the enzyme that converts L-DOPA to dopamine. Furthermore, we show that the A11 neurons contain vesicular monoamine transporter 2 (VMAT2, which is necessary for packaging DA into vesicles. On the contrary, A11 neurons in the mouse lack the dopamine transporter (DAT. In conclusion, our data suggest that A11 neurons are DAergic. The lack of DAT, and therefore the lack of a DA reuptake mechanism, points to a longer time of action compared to typical DA neurons.

Preserved dopaminergic homeostasis and dopamine-related behaviour in hemizygous TH-Cre mice

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Thomsen, Annika Højrup Runegaard; Jensen, Kathrine L; Fitzpatrick, Ciarán M

2017-01-01

assessment of the dopaminergic system in hemizygous tyrosine hydroxylase (TH)-Cre mice in comparison to wild-type (WT) controls. Our data show that TH-Cre mice display preserved dopaminergic homeostasis with unaltered levels of TH and dopamine as well as unaffected dopamine turnover in striatum. TH-Cre mice...

Neurotensin enhances glutamatergic EPSCs in VTA neurons by acting on different neurotensin receptors.

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Bose, Poulomee; Rompré, Pierre-Paul; Warren, Richard A

2015-11-01

Neurotensin (NT) is an endogenous neuropeptide that modulates dopamine and glutamate neurotransmission in several limbic regions innervated by neurons located in the ventral tegmental area (VTA). While several studies showed that NT exerted a direct modulation on VTA dopamine neurons less is known about its role in the modulation of glutamatergic neurotransmission in this region. The present study was aimed at characterising the effects of NT on glutamate-mediated responses in different populations of VTA neurons. Using whole cell patch clamp recording technique in horizontal rat brain slices, we measured the amplitude of glutamatergic excitatory post-synaptic currents (EPSCs) evoked by electrical stimulation of VTA afferents before and after application of different concentrations of NT1-13 or its C-terminal fragment, NT8-13. Neurons were classified as either Ih(+) or Ih(-) based on the presence or absence of a hyperpolarisation activated cationic current (Ih). We found that NT1-13 and NT8-13 produced comparable concentration dependent increase in the amplitude of EPSCs in both Ih(+) and Ih(-) neurons. In Ih(+) neurons, the enhancement effect of NT8-13 was blocked by both antagonists, while in Ih(-) neurons it was blocked by the NTS1/NTS2 antagonist, SR142948A, but not the preferred NTS1 antagonist, SR48692. In as much as Ih(-) neurons are non-dopaminergic neurons and Ih(+) neurons represent both dopamine and non-dopamine neurons, we can conclude that NT enhances glutamatergic mediated responses in dopamine, and in a subset of non-dopamine, neurons by acting respectively on NTS1 and an NT receptor other than NTS1. Copyright © 2015 Elsevier Inc. All rights reserved.

Dopamine-dependent neurodegeneration in Drosophila models of familial and sporadic Parkinson's disease.

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Bayersdorfer, Florian; Voigt, Aaron; Schneuwly, Stephan; Botella, José A

2010-10-01

Parkinson's disease has been found to be caused by both, genetic and environmental factors. Despite the diversity of causes involved, a convergent pathogenic mechanism might underlie the special vulnerability of dopaminergic neurons in different forms of Parkinsonism. In recent years, a number of reports have proposed dopamine as a common player responsible in the loss of dopaminergic neurons independent of its etiology. Using RNAi lines we were able to generate flies with drastically reduced dopamine levels in the dopaminergic neurons. Combining these flies with a chemically induced Parkinson model (rotenone) and a familial form of Parkinson (mutant alpha-synuclein) we were able to show a strong reduction of neurotoxicity and a protection of the dopaminergic neurons when cellular dopamine levels were reduced. These results show that dopamine homeostasis plays a central role for the susceptibility of dopaminergic neurons to environmental and genetic factors in in vivo models of Parkinson disease. (c) 2010 Elsevier Inc. All rights reserved.

Functional integration of grafted neural stem cell-derived dopaminergic neurons monitored by optogenetics in an in vitro Parkinson model

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Tønnesen, Jan; Parish, Clare L; Sørensen, Andreas T

2011-01-01

Intrastriatal grafts of stem cell-derived dopamine (DA) neurons induce behavioral recovery in animal models of Parkinson's disease (PD), but how they functionally integrate in host neural circuitries is poorly understood. Here, Wnt5a-overexpressing neural stem cells derived from embryonic ventral...... of post-synaptic currents, and functional expression of DA D₂ autoreceptors. These properties resembled those recorded from identical cells in acute slices of intrastriatal grafts in the 6-hydroxy-DA-induced mouse PD model and from DA neurons in intact substantia nigra. Optogenetic activation...... using optogenetics that ectopically grafted stem cell-derived DA neurons become functionally integrated in the DA-denervated striatum. Further optogenetic dissection of the synaptic wiring between grafted and host neurons will be crucial to clarify the cellular and synaptic mechanisms underlying...

Olfactory impairment is related to REM sleep deprivation in rotenone model of Parkinson's disease

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Mariana F. Aurich

Full Text Available Introduction: Olfactory dysfunction affects about 85-90% of Parkinson's disease (PD patients with severe deterioration in the ability of discriminate several types of odors. In addition, studies reported declines in olfactory performances during a short period of sleep deprivation. Besides, PD is also known to strongly affect the occurrence and maintenance of rapid eye movement (REM sleep. Methods: Therefore, we investigated the mechanisms involved on discrimination of a social odor (dependent on the vomeronasal system and a non-social odor (related to the main olfactory pathway in the rotenone model of PD. Also, a concomitant impairment in REM sleep was inflicted with the introduction of two periods (24 or 48 h of REM sleep deprivation (REMSD. Rotenone promoted a remarkable olfactory impairment in both social and non-social odors, with a notable modulation induced by 24 h of REMSD for the non-social odor. Results: Our findings demonstrated the occurrence of a strong association between the density of nigral TH-ir neurons and the olfactory discrimination capacity for both odorant stimuli. Specifically, the rotenone-induced decrease of these neurons tends to elicit reductions in the olfactory discrimination ability. Conclusions: These results are consistent with the participation of the nigrostriatal dopaminergic system mainly in the olfactory discrimination of a non-social odor, probably through the main olfactory pathway. Such involvement may have produce relevant impact in the preclinical abnormalities found in PD patients.