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Medecine Sciences : M/S 2016Since the work of Johnson and North, it is known that opiates increase the activity of dopaminergic neurons by a GABA neuron-mediated desinhibition. This model should... (Review)
Review
Since the work of Johnson and North, it is known that opiates increase the activity of dopaminergic neurons by a GABA neuron-mediated desinhibition. This model should however be updated based on recent advances. Thus, the neuroanatomical location of the GABA neurons responsible for this desinhibition has been recently detailed: they belong to a brain structure in continuity with the posterior part of the ventral tegmental area and discovered this past decade. Other data also highlighted the critical role played by glutamatergic transmission in the opioid regulation of dopaminergic neuron activity. During protracted opiate withdrawal, the inhibitory/excitatory balance exerted on dopaminergic neurons is altered. These results are now leading to propose an original hypothesis for explaining the impact of protracted opiate withdrawal on mood.
Topics: Animals; Brain; Dopaminergic Neurons; GABAergic Neurons; Humans; Opiate Alkaloids; Synaptic Transmission; Ventral Tegmental Area
PubMed: 27406773
DOI: 10.1051/medsci/20163206026 -
Neuron Aug 2020The midbrain dopamine (mDA) system is composed of molecularly and functionally distinct neuron subtypes that mediate specific behaviors and show select disease...
The midbrain dopamine (mDA) system is composed of molecularly and functionally distinct neuron subtypes that mediate specific behaviors and show select disease vulnerability, including in Parkinson's disease. Despite progress in identifying mDA neuron subtypes, how these neuronal subsets develop and organize into functional brain structures remains poorly understood. Here we generate and use an intersectional genetic platform, Pitx3-ITC, to dissect the mechanisms of substantia nigra (SN) development and implicate the guidance molecule Netrin-1 in the migration and positioning of mDA neuron subtypes in the SN. Unexpectedly, we show that Netrin-1, produced in the forebrain and provided to the midbrain through axon projections, instructs the migration of GABAergic neurons into the ventral SN. This migration is required to confine mDA neurons to the dorsal SN. These data demonstrate that neuron migration can be controlled by remotely produced and axon-derived secreted guidance cues, a principle that is likely to apply more generally.
Topics: Animals; Axons; Cell Movement; Dopaminergic Neurons; GABAergic Neurons; Mice; Mice, Transgenic; Netrin-1; Prosencephalon; Substantia Nigra
PubMed: 32562661
DOI: 10.1016/j.neuron.2020.05.037 -
Journal of Visualized Experiments : JoVE Sep 2014Dopaminergic (DA) neurons in the substantia nigra pars compacta (also known as A9 DA neurons) are the specific cell type that is lost in Parkinson's disease (PD). There...
Dopaminergic (DA) neurons in the substantia nigra pars compacta (also known as A9 DA neurons) are the specific cell type that is lost in Parkinson's disease (PD). There is great interest in deriving A9 DA neurons from human pluripotent stem cells (hPSCs) for regenerative cell replacement therapy for PD. During neural development, A9 DA neurons originate from the floor plate (FP) precursors located at the ventral midline of the central nervous system. Here, we optimized the culture conditions for the stepwise differentiation of hPSCs to A9 DA neurons, which mimics embryonic DA neuron development. In our protocol, we first describe the efficient generation of FP precursor cells from hPSCs using a small molecule method, and then convert the FP cells to A9 DA neurons, which could be maintained in vitro for several months. This efficient, repeatable and controllable protocol works well in human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) from normal persons and PD patients, in which one could derive A9 DA neurons to perform in vitro disease modeling and drug screening and in vivo cell transplantation therapy for PD.
Topics: Animals; Cell Culture Techniques; Cell Differentiation; Dopaminergic Neurons; Embryonic Stem Cells; Humans; Induced Pluripotent Stem Cells; Mice; Morpholines; Purines; Pyridines; Pyrimidines
PubMed: 25285746
DOI: 10.3791/51737 -
Nature Communications Mar 2022The prefrontal cortex is involved in goal-directed behavior. Here, we investigate circuits of the PFC regulating motivation, reinforcement, and its relationship to...
The prefrontal cortex is involved in goal-directed behavior. Here, we investigate circuits of the PFC regulating motivation, reinforcement, and its relationship to dopamine neuron activity. Stimulation of medial PFC (mPFC) neurons in mice activated many downstream regions, as shown by fMRI. Axonal terminal stimulation of mPFC neurons in downstream regions, including the anteromedial thalamic nucleus (AM), reinforced behavior and activated midbrain dopaminergic neurons. The stimulation of AM neurons projecting to the mPFC also reinforced behavior and activated dopamine neurons, and mPFC and AM showed a positive-feedback loop organization. We also found using fMRI in human participants watching reinforcing video clips that there is reciprocal excitatory functional connectivity, as well as co-activation of the two regions. Our results suggest that this cortico-thalamic loop regulates motivation, reinforcement, and dopaminergic neuron activity.
Topics: Animals; Axons; Dopaminergic Neurons; Goals; Humans; Mice; Neural Pathways; Prefrontal Cortex; Thalamus
PubMed: 35296648
DOI: 10.1038/s41467-022-28892-7 -
Scientific Reports Apr 2016Human pluripotent stem cells provide a powerful human-genome based system for modeling human diseases in vitro and for potentially identifying novel treatments. Directed...
Human pluripotent stem cells provide a powerful human-genome based system for modeling human diseases in vitro and for potentially identifying novel treatments. Directed differentiation of pluripotent stem cells produces many specific cell types including dopaminergic neurons. Here, we generated a genetic reporter assay in pluripotent stem cells using newly-developed genome editing technologies in order to monitor differentiation efficiency and compare dopaminergic neuron survival under different conditions. We show that insertion of a luciferase reporter gene into the endogenous tyrosine hydroxylase (TH) locus enables rapid and easy quantification of dopaminergic neurons in cell culture throughout the entire differentiation process. Moreover, we demonstrate that the cellular assay is effective in assessing neuron response to different cytotoxic chemicals and is able to be scaled for high throughput applications. These results suggest that stem cell-derived terminal cell types can provide an alternative to traditional immortal cell lines or primary cells as a quantitative cellular model for toxin evaluation and drug discovery.
Topics: Cell Differentiation; Cells, Cultured; Cytological Techniques; Cytotoxins; Dopaminergic Neurons; Gene Editing; Genes, Reporter; Genetic Loci; High-Throughput Screening Assays; Humans; Luciferases; Pluripotent Stem Cells
PubMed: 27121904
DOI: 10.1038/srep25181 -
The Neuroscientist : a Review Journal... Dec 2015The small GTP-binding protein Rho plays an important role in several cellular functions. RhoA, which is a member of the Rho family, initiates cellular processes that act... (Review)
Review
The small GTP-binding protein Rho plays an important role in several cellular functions. RhoA, which is a member of the Rho family, initiates cellular processes that act on its direct downstream effector Rho-associated kinase (ROCK). ROCK inhibition protects against dopaminergic cell death induced by dopaminergic neurotoxins. It has been suggested that ROCK inhibition activates neuroprotective survival cascades in dopaminergic neurons. Axon-stabilizing effects in damaged neurons may represent another mechanism of neuroprotection of dopaminergic neurons by ROCK inhibition. However, it has been shown that microglial cells play a crucial role in neuroprotection by ROCK inhibition and that activation of microglial ROCK mediates major components of the microglial inflammatory response. Additional mechanisms such as interaction with autophagy may also contribute to the neuroprotective effects of ROCK inhibition. Interestingly, ROCK interacts with several brain factors that play a major role in dopaminergic neuron vulnerability such as NADPH-oxidase, angiotensin, and estrogen. ROCK inhibition may provide a new neuroprotective strategy for Parkinson's disease. This is of particular interest because ROCK inhibitors are currently used against vascular diseases in clinical practice. However, it is necessary to develop more potent and selective ROCK inhibitors to reduce side effects and enhance the efficacy.
Topics: Animals; Antiparkinson Agents; Dopaminergic Neurons; Humans; Nerve Degeneration; Neuroprotective Agents; Parkinson Disease; rho-Associated Kinases
PubMed: 25323761
DOI: 10.1177/1073858414554954 -
Cells Dec 2023Advances in stem cell technologies open up new avenues for modelling development and diseases. The success of these pursuits, however, relies on the use of cells most...
Single-Cell Transcriptomics and In Vitro Lineage Tracing Reveals Differential Susceptibility of Human iPSC-Derived Midbrain Dopaminergic Neurons in a Cellular Model of Parkinson's Disease.
Advances in stem cell technologies open up new avenues for modelling development and diseases. The success of these pursuits, however, relies on the use of cells most relevant to those targeted by the disease of interest, for example, midbrain dopaminergic neurons for Parkinson's disease. In the present study, we report the generation of a human induced pluripotent stem cell (iPSC) line capable of purifying and tracing nascent midbrain dopaminergic progenitors and their differentiated progeny via the expression of a Blue Fluorescent Protein (BFP). This was achieved by CRISPR/Cas9-assisted knock-in of BFP and Cre into the safe harbour locus AAVS1 and an early midbrain dopaminergic lineage marker gene LMX1A, respectively. Immunocytochemical analysis and single-cell RNA sequencing of iPSC-derived neural cultures confirm developmental recapitulation of the human fetal midbrain and high-quality midbrain cells. By modelling Parkinson's disease-related drug toxicity using 1-Methyl-4-phenylpyridinium (MPP), we showed a preferential reduction of BFP cells, a finding demonstrated independently by cell death assays and single-cell transcriptomic analysis of MPP treated neural cultures. Together, these results highlight the importance of disease-relevant cell types in stem cell modelling.
Topics: Humans; Induced Pluripotent Stem Cells; Parkinson Disease; Dopaminergic Neurons; Dopamine; Gene Expression Profiling; Mesencephalon
PubMed: 38132179
DOI: 10.3390/cells12242860 -
Stem Cell Reports Apr 2018The differentiation of dopaminergic neurons requires concerted action of morphogens and transcription factors acting in a precise and well-defined time window. Very...
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.
Topics: Animals; Base Sequence; Cell Differentiation; Cell Transdifferentiation; Dopaminergic Neurons; Fibroblasts; Gene Expression Regulation; Germ Layers; Green Fluorescent Proteins; Homeodomain Proteins; Mesencephalon; Mice; MicroRNAs; Neurogenesis; Transcription Factors; Wnt Signaling Pathway; Wnt1 Protein
PubMed: 29526736
DOI: 10.1016/j.stemcr.2018.02.006 -
Molecular Neurodegeneration Jun 2022A constant metabolism and energy supply are crucial to all organs, particularly the brain. Age-dependent neurodegenerative diseases, such as Parkinson's disease (PD),... (Review)
Review
A constant metabolism and energy supply are crucial to all organs, particularly the brain. Age-dependent neurodegenerative diseases, such as Parkinson's disease (PD), are associated with alterations in cellular metabolism. These changes have been recognized as a novel hot topic that may provide new insights to help identify risk in the pre-symptomatic phase of the disease, understand disease pathogenesis, track disease progression, and determine critical endpoints. Nuclear receptor-related factor 1 (NURR1), an orphan member of the nuclear receptor superfamily of transcription factors, is a major risk factor in the pathogenesis of PD, and changes in NURR1 expression can have a detrimental effect on cellular metabolism. In this review, we discuss recent evidence that suggests a vital role of NURR1 in dopaminergic (DAergic) neuron development and the pathogenesis of PD. The association between NURR1 and cellular metabolic abnormalities and its implications for PD therapy have been further highlighted.
Topics: Dopamine; Dopaminergic Neurons; Humans; Nuclear Receptor Subfamily 4, Group A, Member 2; Parkinson Disease; Transcription Factors
PubMed: 35761385
DOI: 10.1186/s13024-022-00544-w -
Journal of Visualized Experiments : JoVE Feb 2021Estimation of the number of dopaminergic neurons in the substantia nigra is a key method in pre-clinical Parkinson's disease research. Currently, unbiased stereological...
Estimation of the number of dopaminergic neurons in the substantia nigra is a key method in pre-clinical Parkinson's disease research. Currently, unbiased stereological counting is the standard for quantification of these cells, but it remains a laborious and time-consuming process, which may not be feasible for all projects. Here, we describe the use of an image analysis platform, which can accurately estimate the quantity of labeled cells in a pre-defined region of interest. We describe a step-by-step protocol for this method of analysis in rat brain and demonstrate it can identify a significant reduction in tyrosine hydroxylase positive neurons due to expression of mutant α-synuclein in the substantia nigra. We validated this methodology by comparing with results obtained by unbiased stereology. Taken together, this method provides a time-efficient and accurate process for detecting changes in dopaminergic neuron number, and thus is suitable for efficient determination of the effect of interventions on cell survival.
Topics: Animals; Dopaminergic Neurons; Female; Image Processing, Computer-Assisted; Immunohistochemistry; Rats; Rats, Sprague-Dawley; Substantia Nigra; Tyrosine 3-Monooxygenase; alpha-Synuclein
PubMed: 33616088
DOI: 10.3791/62062