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Cells Dec 2022Attention deficit and hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by alterations in the mesocorticolimbic and nigrostriatal dopaminergic...
Attention deficit and hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by alterations in the mesocorticolimbic and nigrostriatal dopaminergic pathways. Polymorphisms in the Synapsin III (Syn III) gene can associate with ADHD onset and even affect the therapeutic response to the gold standard ADHD medication, methylphenidate (MPH), a monoamine transporter inhibitor whose efficacy appears related with the stimulation of brain-derived neurotrophic factor (BDNF). Interestingly, we previously showed that MPH can bind Syn III, which can regulate neuronal development. These observations suggest that Syn III polymorphism may impinge on ADHD onset and response to therapy by affecting BDNF-dependent dopaminergic neuron development. Here, by studying zebrafish embryos exposed to Syn III gene knock-down (KD), Syn III knock-out (ko) mice and human induced pluripotent stem cells (iPSCs)-derived neurons subjected to Syn III RNA interference, we found that Syn III governs the earliest stages of dopaminergic neurons development and that this function is conserved in vertebrates. We also observed that in mammals Syn III exerts this function acting upstream of brain-derived neurotrophic factor (BDNF)- and cAMP-dependent protein kinase 5 (Cdk5)-stimulated dendrite development. Collectively, these findings own significant implications for deciphering the biological basis of ADHD.
Topics: Animals; Humans; Mice; Brain-Derived Neurotrophic Factor; Dopamine; Dopaminergic Neurons; Induced Pluripotent Stem Cells; Methylphenidate; Mice, Knockout; Synapsins; Zebrafish
PubMed: 36497160
DOI: 10.3390/cells11233902 -
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 -
Genetics Aug 2021Parkinson's disease (PD) is primarily characterized by the loss of dopaminergic (DA) neurons in the brain. However, little is known about why DA neurons are selectively...
Parkinson's disease (PD) is primarily characterized by the loss of dopaminergic (DA) neurons in the brain. However, little is known about why DA neurons are selectively vulnerable to PD. To identify genes that are associated with DA neuron loss, we screened through 201 wild-caught populations of Drosophila melanogaster as part of the Drosophila Genetic Reference Panel. Here, we identify the top-associated genes containing single-nucleotide polymorphisms that render DA neurons vulnerable. These genes were further analyzed by using mutant analysis and tissue-specific knockdown for functional validation. We found that this loss of DA neurons caused progressive locomotor dysfunction in mutants and gene knockdown analysis. The identification of genes associated with the progressive loss of DA neurons should help to uncover factors that render these neurons vulnerable in PD, and possibly develop strategies to make these neurons more resilient.
Topics: Animals; Dopaminergic Neurons; Drosophila melanogaster; Genome, Insect; Locomotion; Parkinson Disease; Polymorphism, Single Nucleotide
PubMed: 34038543
DOI: 10.1093/genetics/iyab081 -
Neuroscience Research Oct 2020In 2018, we summarized Parkin mutation analysis over the 20 years since its discovery. As a strategy for treating Parkinson's disease (PD), disease-modifying therapies...
In 2018, we summarized Parkin mutation analysis over the 20 years since its discovery. As a strategy for treating Parkinson's disease (PD), disease-modifying therapies based on the overall picture of PD, including pathological studies of hereditary PD, have been developed. With the discovery of Parkin, research on PD accelerated explosively around the world. Several PD mouse models were generated to investigate the pathology of PD. Recently, we reported dopaminergic neuron-specific autophagy-deficient mice as a model of sporadic PD. These mice exhibit Lewy pathology and motor dysfunction, and provide in vivo evidence for Lewy body formation. In these animals, synuclein deposition is preceded by p62, resulting in the formation of inclusions containing both proteins. The number and size of these inclusions increase gradually with aging. Consequently, dopaminergic (DA) neuron loss and motor dysfunction are observed in 120-week-old mice. To assess the critical role of Parkin in vivo, we characterized Parkin-knockout mice over a long period of time. At the age of 110 weeks, Parkin-knockout mice exhibited locomotor impairments, including hindlimb defects and neuronal loss, and fragmented mitochondria with abnormal internal structures accumulated in their DA neurons. Age-related motor dysfunction and damaged mitochondria were observed in Parkin-deficient mice.
Topics: Animals; Disease Models, Animal; Dopaminergic Neurons; Gene Knockout Techniques; Mice; Mice, Knockout; Parkinson Disease; Ubiquitin-Protein Ligases
PubMed: 32360487
DOI: 10.1016/j.neures.2020.03.014 -
Journal of Neuroinflammation Mar 2023Noradrenergic neurons in the locus coeruleus (LC) are the primary source of norepinephrine (NE) in the brain and degeneration of these neurons is reported in the early...
BACKGROUND
Noradrenergic neurons in the locus coeruleus (LC) are the primary source of norepinephrine (NE) in the brain and degeneration of these neurons is reported in the early stages of Parkinson's disease (PD), even prior to dopaminergic neuron degeneration in the substantia nigra (SN), which is a hallmark of PD pathology. NE depletion is generally associated with increased PD pathology in neurotoxin-based PD models. The effect of NE depletion in other models of PD-like α-synuclein-based models is largely unexplored. In PD models and in human patients, β-adrenergic receptors' (AR) signaling is associated with a reduction of neuroinflammation and PD pathology. However, the effect of NE depletion in the brain and the extent of NE and β-ARs signaling involvement in neuroinflammation, and dopaminergic neuron survival is poorly understood.
METHODS
Two mouse models of PD, a 6OHDA neurotoxin-based model and a human α-synuclein (hα-SYN) virus-based model of PD, were used. DSP-4 was used to deplete NE levels in the brain and its effect was confirmed by HPLC with electrochemical detection. A pharmacological approach was used to mechanistically understand the impact of DSP-4 in the hα-SYN model of PD using a norepinephrine transporter (NET) and a β-AR blocker. Epifluorescence and confocal imaging were used to study changes in microglia activation and T-cell infiltration after β1-AR and β2-AR agonist treatment in the hα-SYN virus-based model of PD.
RESULTS
Consistent with previous studies, we found that DSP-4 pretreatment increased dopaminergic neuron loss after 6OHDA injection. In contrast, DSP-4 pretreatment protected dopaminergic neurons after hα-SYN overexpression. DSP-4-mediated protection of dopaminergic neurons after hα-SYN overexpression was dependent on β-AR signaling since using a β-AR blocker prevented DSP-4-mediated dopaminergic neuron protection in this model of PD. Finally, we found that the β-2AR agonist, clenbuterol, reduced microglia activation, T-cell infiltration, and dopaminergic neuron degeneration, whereas xamoterol a β-1AR agonist showed increased neuroinflammation, blood brain barrier permeability (BBB), and dopaminergic neuron degeneration in the context of hα-SYN-mediated neurotoxicity.
CONCLUSIONS
Our data demonstrate that the effects of DSP-4 on dopaminergic neuron degeneration are model specific, and suggest that in the context of α-SYN-driven neuropathology, β2-AR specific agonists may have therapeutic benefit in PD.
Topics: Animals; Humans; Mice; alpha-Synuclein; Dopaminergic Neurons; Nerve Degeneration; Neuroinflammatory Diseases; Neurotoxicity Syndromes; Neurotoxins; Parkinson Disease; Receptors, Adrenergic, beta-1; Receptors, Adrenergic, beta-2
PubMed: 36864439
DOI: 10.1186/s12974-023-02748-3 -
Journal of Neurochemistry May 2023Dietary lipids, particularly omega-3 polyunsaturated fatty acids, are speculated to impact behaviors linked to the dopaminergic system, such as movement and control of...
Dietary lipids, particularly omega-3 polyunsaturated fatty acids, are speculated to impact behaviors linked to the dopaminergic system, such as movement and control of circadian rhythms. However, the ability to draw a direct link between dopaminergic omega-3 fatty acid metabolism and behavioral outcomes has been limited to the use of diet-based approaches, which are confounded by systemic effects. Here, neuronal lipid metabolism was targeted in a diet-independent manner by manipulation of long-chain acyl-CoA synthetase 6 (ACSL6) expression. ACSL6 performs the initial reaction for cellular fatty acid metabolism and prefers the omega-3 polyunsaturated fatty acid, docosahexaenoic acid (DHA). The loss of Acsl6 in mice (Acsl6 ) depletes neuronal membranes of DHA content and results in phenotypes linked to dopaminergic control, such as hyperlocomotion, impaired short-term spatial memory, and imbalances in dopamine neurochemistry. To investigate the role of dopaminergic ACSL6 on these outcomes, a dopaminergic neuron-specific ACSL6 knockout mouse was generated (Acsl6 ). Acsl6 mice demonstrated hyperlocomotion and imbalances in striatal dopamine neurochemistry. Circadian rhythms of both the Acsl6 and the Acsl6 mice were similar to control mice under basal conditions. However, upon light entrainment, a mimetic of jet lag, both the complete knockout of ACSL6 and the dopaminergic-neuron-specific loss of ACSL6 resulted in a longer recovery to entrainment compared to control mice. In conclusion, these data demonstrate that ACSL6 in dopaminergic neurons alters dopamine metabolism and regulation of light entrainment suggesting that DHA metabolism mediated by ACSL6 plays a role in dopamine neuron biology.
Topics: Mice; Animals; Dopaminergic Neurons; Lipid Metabolism; Dopamine; Dietary Fats; Diet; Mice, Knockout; Docosahexaenoic Acids; Coenzyme A Ligases
PubMed: 36815399
DOI: 10.1111/jnc.15793 -
The European Journal of Neuroscience Mar 2024Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive dysfunction and loss of dopaminergic neurons of the substantia nigra pars compacta... (Review)
Review
Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive dysfunction and loss of dopaminergic neurons of the substantia nigra pars compacta (SNc). Several pathways of programmed cell death are likely to play a role in dopaminergic neuron death, such as apoptosis, necrosis, pyroptosis and ferroptosis, as well as cell death associated with proteasomal and mitochondrial dysfunction. A better understanding of the molecular mechanisms underlying dopaminergic neuron death could inform the design of drugs that promote neuron survival. Necroptosis is a recently characterized regulated cell death mechanism that exhibits morphological features common to both apoptosis and necrosis. It requires activation of an intracellular pathway involving receptor-interacting protein 1 kinase (RIP1 kinase, RIPK1), receptor-interacting protein 3 kinase (RIP3 kinase, RIPK3) and mixed lineage kinase domain-like pseudokinase (MLKL). The potential involvement of this programmed cell death pathway in the pathogenesis of PD has been studied by analysing biomarkers for necroptosis, such as the levels and oligomerization of phosphorylated RIPK3 (pRIPK3) and phosphorylated MLKL (pMLKL), in several PD preclinical models and in PD human tissue. Although there is evidence that other types of cell death also have a role in DA neuron death, most studies support the hypothesis that this cell death mechanism is activated in PD tissues. Drugs that prevent or reduce necroptosis may provide neuroprotection for PD. In this review, we summarize the findings from these studies. We also discuss how manipulating necroptosis might open a novel therapeutic approach to reduce neuronal degeneration in PD.
Topics: Humans; Dopaminergic Neurons; Parkinson Disease; Necroptosis; Cell Death; Apoptosis; Necrosis; Dopamine
PubMed: 37667848
DOI: 10.1111/ejn.16136 -
Brain, Behavior, and Immunity May 2021Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent psychiatric disorders in children. The orexigenic hormone ghrelin is important in...
Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent psychiatric disorders in children. The orexigenic hormone ghrelin is important in neuroprotection and neurodevelopment, which may play an important role in psychopathogenesis of ADHD. This study aimed to systematically investigate the genomic and pharmacological manipulations of ghrelin functioning in ADHD-like symptoms in zebrafish models and validated the effects of ghrelin polymorphisms in human subjects with ADHD. We firstly generated ghrelin zebrafish mutant, which displayed hyperactive, attention deficit-like and impulsive-like behaviors, as well as endophenotypes, mimicking human ADHD. Ghrelin zebrafish exhibited downregulated expression levels of wnt1, wnt3a, wnt5a that are critical for dopaminergic neuron development to possibly regulate their number and spatial organization. Pharmacological blockade of wnt signaling with XAV939 induced a reduced moving activity and less dopaminergic neurons; whereas, wnt agonist SB415286 rescued hyperactivity and dopaminergic neuron loss in ghrelin zebrafish. In addition, we further identified and validated a SNP, rs696217, on orexigenic hormone preproghrelin/ghrelin (T408T, Met72Met) to be associated with a higher risk of ADHD in a case-controlled association study with 248 subjects with ADHD and 208 subjects of healthy controls. Together, our results reveal a novel endogenous role for orexigenic hormone ghrelin in ADHD, which provides insights into genetic regulation and drug screens for the identification of novel treatments of ADHD.
Topics: Animals; Attention Deficit Disorder with Hyperactivity; Child; Dopaminergic Neurons; Ghrelin; Humans; Impulsive Behavior; Zebrafish
PubMed: 33412253
DOI: 10.1016/j.bbi.2020.12.029 -
Current Opinion in Neurobiology Feb 2019Cocaine exposure induces persistent changes in synaptic transmission and intrinsic properties of ventral tegmental area (VTA) dopamine neurons. Despite significant... (Review)
Review
Cocaine exposure induces persistent changes in synaptic transmission and intrinsic properties of ventral tegmental area (VTA) dopamine neurons. Despite significant progress in understanding cocaine-induced plasticity, an effective treatment of cocaine addiction is lacking. Chronic cocaine potentiates excitatory and alters inhibitory transmission to dopamine neurons, induces dopamine neuron hyperexcitability, and reduces dopamine release in projection areas. Understanding how intrinsic and synaptic plasticity interact to control dopamine neuron firing and dopamine release could prove useful in the development of new therapeutics. In this review, we examine recent literature discussing cocaine-induced plasticity in the VTA and highlight potential therapeutic interventions.
Topics: Animals; Cocaine; Cocaine-Related Disorders; Dopamine; Dopamine Uptake Inhibitors; Dopaminergic Neurons; Humans; Neuronal Plasticity; Neurotransmitter Agents; Synapses; Ventral Tegmental Area
PubMed: 30237117
DOI: 10.1016/j.conb.2018.08.013 -
Frontiers in Immunology 2023Tourette syndrome (TS) is associated with immunological dysfunction. The DA system is closely related to TS development, or behavioral stereotypes. Previous evidence...
BACKGROUND
Tourette syndrome (TS) is associated with immunological dysfunction. The DA system is closely related to TS development, or behavioral stereotypes. Previous evidence suggested that hyper-M1-polarized microglia may exist in the brains of TS individuals. However, the role of microglia in TS and their interaction with dopaminergic neurons is unclear. In this study, we applied iminodipropionitrile (IDPN) to establish a TS model and focused on the inflammatory injury in the striatal microglia-dopaminergic-neuron crosstalk.
METHODS
Male Sprague-Dawley rats were intraperitoneally injected with IDPN for seven consecutive days. Stereotypic behavior was observed to verify the TS model. Striatal microglia activation was evaluated based on different markers and expressions of inflammatory factors. The striatal dopaminergic neurons were purified and co-cultured with different microglia groups, and dopamine-associated markers were assessed.
RESULTS
First, there was pathological damage to striatal dopaminergic neurons in TS rats, as indicated by decreased expression of TH, DAT, and PITX3. Next, the TS group showed a trend of increased Iba-1 positive cells and elevated levels of inflammatory factors TNF-α and IL-6, as well as an enhanced M1-polarization marker (iNOS) and an attenuated M2-polarization marker (Arg-1). Finally, in the co-culture experiment, IL-4-treated microglia could upregulate the expression of TH, DAT, and PITX3 in striatal dopaminergic neurons LPS-treated microglia. Similarly, the TS group (microglia from TS rats) caused a decreased expression of TH, DAT, and PITX3 compared with the Sham group (microglia from control rats) in the dopaminergic neurons.
CONCLUSION
In the striatum of TS rats, microglia activation is M1 hyperpolarized, which transmits inflammatory injury to striatal dopaminergic neurons and disrupts normal dopamine signaling.
Topics: Rats; Male; Animals; Microglia; Dopaminergic Neurons; Rats, Sprague-Dawley; Dopamine; Tourette Syndrome
PubMed: 37187752
DOI: 10.3389/fimmu.2023.1178113