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Neurobiology of Disease Aug 2023Neurotransmission signaling is a highly conserved system attributed to various regulatory events. The excitatory and inhibitory neurotransmitter systems have been... (Review)
Review
Neurotransmission signaling is a highly conserved system attributed to various regulatory events. The excitatory and inhibitory neurotransmitter systems have been extensively studied, and their role in neuronal cell proliferation, synaptogenesis and dendrite formation in the adult brain is well established. Recent research has shown that epigenetic regulation plays a crucial role in mediating the expression of key genes associated with neurotransmitter pathways, including neurotransmitter receptor and transporter genes. The dysregulation of these genes has been linked to a range of neurological disorders such as attention-deficit/hyperactivity disorder, Parkinson's disease and schizophrenia. This article focuses on epigenetic regulatory mechanisms that control the expression of genes associated with four major chemical carriers in the brain: dopamine (DA), Gamma-aminobutyric acid (GABA), glutamate and serotonin. Additionally, we explore how aberrant epigenetic regulation of these genes can contribute to the pathogenesis of relevant neurological disorders. By targeting the epigenetic mechanisms that control neurotransmitter gene expression, there is a promising opportunity to advance the development of more effective treatments for neurological disorders with the potential to significantly improve the quality of life of individuals impacted by these conditions.
Topics: Humans; Epigenesis, Genetic; Quality of Life; Nervous System Diseases; Signal Transduction; Neurotransmitter Agents
PubMed: 37479091
DOI: 10.1016/j.nbd.2023.106232 -
Psychiatria Danubina Oct 2023Bipolar disorder and Parkinson's disease are two distinct neurological conditions that share common features related to dopaminergic dysfunction. This article presents a... (Review)
Review
Bipolar disorder and Parkinson's disease are two distinct neurological conditions that share common features related to dopaminergic dysfunction. This article presents a comprehensive review of the existing literature to investigate the association between bipolar disorder and Parkinson's disease, focusing on the dopaminergic hypothesis and potential therapeutic options. The dopaminergic hypothesis suggests that both bipolar disorder and Parkinson's disease involve impairments in the nigrostriatal or mesolimbic dopaminergic pathways. Studies have demonstrated alterations in dopamine regulation during manic and depressive phases of bipolar disorder. Similarly, Parkinson's disease is characterized by the loss of dopaminergic neurons in the substantia nigra, resulting in motor symptoms. Recent analyses have highlighted a predisposition to Parkinson's disease in individuals with bipolar disorder. Longitudinal studies and meta-analyses have demonstrated an increased risk of developing Parkinson's disease in patients with bipolar disorder. However, differentiating idiopathic Parkinson's disease from parkinsonism induced by medications used in bipolar disorder can be challenging. Dopamine transporter (DAT) scans can aid in making a differential diagnosis. Treatment options for patients with both bipolar disorder and Parkinson's disease are limited. Neuroleptics, commonly used to manage psychotic symptoms in Parkinson's disease, may worsen motor symptoms and have limitations in bipolar disorder patients. Clozapine has shown efficacy in treating psychosis without worsening motor symptoms. Pimavanserin, an inverse agonist of the 5-HT2A receptor can offer new opportunities. However, its efficacy in bipolar disorder patients with Parkinson's disease remains unexplored. In conclusion, the association between bipolar disorder and Parkinson's disease is supported by the involvement of the dopaminergic system in both conditions. The identification of shared mechanisms opens new avenues for potential therapeutic interventions. Further research is needed to investigate the efficacy of pimavanserin and explore other treatment options for individuals with both bipolar disorder and Parkinson's disease.
Topics: Humans; Parkinson Disease; Bipolar Disorder; Drug Inverse Agonism; Piperidines; Dopamine
PubMed: 37800205
DOI: No ID Found -
Cureus Sep 2023This drug review provides a comprehensive analysis of a novel antipsychotic called lumateperone, marketed as Caplyta. Lumateperone gained FDA approval in 2019 for... (Review)
Review
This drug review provides a comprehensive analysis of a novel antipsychotic called lumateperone, marketed as Caplyta. Lumateperone gained FDA approval in 2019 for treating schizophrenia and later, in 2021, for treating bipolar depression. The review begins by delving into lumateperone's mechanism of action, which involves the partial agonism of the dopamine D2 receptor as well as its unique effects on the dopamine transporter, N-methyl-D-aspartate (NMDA) receptor, and serotonin transporter. Additionally, the study examines lumateperone's distinctive pharmacokinetics. Moreover, this review assesses lumateperone's metabolic profile and highlights its favorable outcomes regarding mean body weight, BMI, and waist circumference, surpassing those of other second-generation antipsychotic medications. The study explicitly emphasizes the efficacy and safety of lumateperone in treating schizophrenia and bipolar depression associated with bipolar I and II disorders. An extensive investigation of multiple clinical trials provides compelling evidence of lumateperone's advantages over existing antipsychotic medications. The review also acknowledges the limitations of lumateperone compared to other antipsychotics. In conclusion, this drug review underscores the importance of further research to uncover the additional limitations of lumateperone while acknowledging its promising benefits and potential for advancing treatment options.
PubMed: 37900490
DOI: 10.7759/cureus.46143 -
PLCγ1 in dopamine neurons critically regulates striatal dopamine release via VMAT2 and synapsin III.Experimental & Molecular Medicine Nov 2023Dopamine neurons are essential for voluntary movement, reward learning, and motivation, and their dysfunction is closely linked to various psychological and...
Dopamine neurons are essential for voluntary movement, reward learning, and motivation, and their dysfunction is closely linked to various psychological and neurodegenerative diseases. Hence, understanding the detailed signaling mechanisms that functionally modulate dopamine neurons is crucial for the development of better therapeutic strategies against dopamine-related disorders. Phospholipase Cγ1 (PLCγ1) is a key enzyme in intracellular signaling that regulates diverse neuronal functions in the brain. It was proposed that PLCγ1 is implicated in the development of dopaminergic neurons, while the physiological function of PLCγ1 remains to be determined. In this study, we investigated the physiological role of PLCγ1, one of the key effector enzymes in intracellular signaling, in regulating dopaminergic function in vivo. We found that cell type-specific deletion of PLCγ1 does not adversely affect the development and cellular morphology of midbrain dopamine neurons but does facilitate dopamine release from dopaminergic axon terminals in the striatum. The enhancement of dopamine release was accompanied by increased colocalization of vesicular monoamine transporter 2 (VMAT2) at dopaminergic axon terminals. Notably, dopamine neuron-specific knockout of PLCγ1 also led to heightened expression and colocalization of synapsin III, which controls the trafficking of synaptic vesicles. Furthermore, the knockdown of VMAT2 and synapsin III in dopamine neurons resulted in a significant attenuation of dopamine release, while this attenuation was less severe in PLCγ1 cKO mice. Our findings suggest that PLCγ1 in dopamine neurons could critically modulate dopamine release at axon terminals by directly or indirectly interacting with synaptic machinery, including VMAT2 and synapsin III.
Topics: Animals; Mice; Dopamine; Dopaminergic Neurons; Presynaptic Terminals; Synapsins; Vesicular Monoamine Transport Proteins
PubMed: 37907739
DOI: 10.1038/s12276-023-01104-y -
Frontiers in Cellular Neuroscience 2023Alzheimer's disease (AD) is characterized by the pathologic deposition of amyloid and neurofibrillary tangles in the brain, leading to neuronal damage and defective... (Review)
Review
Alzheimer's disease (AD) is characterized by the pathologic deposition of amyloid and neurofibrillary tangles in the brain, leading to neuronal damage and defective synapses. These changes manifest as abnormalities in cognition and behavior. The functional deficits are also attributed to abnormalities in multiple neurotransmitter systems contributing to neuronal dysfunction. One such important system is the dopaminergic system. It plays a crucial role in modulating movement, cognition, and behavior while connecting various brain areas and influencing other neurotransmitter systems, making it relevant in neurodegenerative disorders like AD and Parkinson's disease (PD). Considering its significance, the dopaminergic system has emerged as a promising target for alleviating movement and cognitive deficits in PD and AD, respectively. Extensive research has been conducted on dopaminergic neurons, receptors, and dopamine levels as critical factors in cognition and memory in AD. However, the exact nature of movement abnormalities and other features of extrapyramidal symptoms are not fully understood yet in AD. Recently, a previously overlooked element of the dopaminergic system, the dopamine transporter, has shown significant promise as a more effective target for enhancing cognition while addressing dopaminergic system dysfunction in AD.
PubMed: 38026688
DOI: 10.3389/fncel.2023.1292858 -
Current Research in Physiology 2023The primary regulator of dopamine availability in the brain is the dopamine transporter (DAT), a plasma membrane protein that drives reuptake of released dopamine from... (Review)
Review
The primary regulator of dopamine availability in the brain is the dopamine transporter (DAT), a plasma membrane protein that drives reuptake of released dopamine from the extracellular space into the presynaptic neuron. DAT activity is regulated by post-translational modifications that establish clearance capacity through impacts on transport kinetics, and dysregulation of these events may underlie dopaminergic imbalances in mood and psychiatric disorders. Here, using fluorescence recovery after photobleaching, we show that phosphorylation and palmitoylation induce opposing effects on DAT lateral membrane mobility, which may influence functional outcomes by regulating subcellular localization and binding partner interactions. Membrane mobility was also impacted by amphetamine and in polymorphic variant A559V in directions consistent with enhanced phosphorylation. These findings grow the list of DAT properties controlled by these post-translational modifications and highlight their role in establishment of dopaminergic tone in physiological and pathophysiological states.
PubMed: 38107792
DOI: 10.1016/j.crphys.2023.100106 -
Biomolecules Nov 2023L-DOPA is the mainstay of treatment for Parkinson's disease (PD). However, over time this drug can produce dyskinesia. A useful acute PD model for screening novel...
L-DOPA is the mainstay of treatment for Parkinson's disease (PD). However, over time this drug can produce dyskinesia. A useful acute PD model for screening novel compounds for anti-parkinsonian and L-DOPA-induced dyskinesia (LID) are dopamine-depleted dopamine-transporter KO (DDD) mice. Treatment with α-methyl--tyrosine rapidly depletes their brain stores of DA and renders them akinetic. During sensitization in the open field (OF), their locomotion declines as vertical activities increase and upon encountering a wall they stand on one leg or tail and engage in climbing behavior termed "three-paw dyskinesia". We have hypothesized that L-DOPA induces a stereotypic activation of locomotion in DDD mice, where they are unable to alter the course of their locomotion, and upon encountering walls engage in "three-paw dyskinesia" as reflected in vertical counts or beam-breaks. The purpose of our studies was to identify a valid index of LID in DDD mice that met three criteria: (a) sensitization with repeated L-DOPA administration, (b) insensitivity to a change in the test context, and (c) stimulatory or inhibitory responses to dopamine D1 receptor agonists (5 mg/kg SKF81297; 5 and 10 mg/kg MLM55-38, a novel compound) and amantadine (45 mg/kg), respectively. Responses were compared between the OF and a circular maze (CM) that did not hinder locomotion. We found vertical counts and climbing were specific for testing in the OF, while oral stereotypies were sensitized to L-DOPA in both the OF and CM and responded to D1R agonists and amantadine. Hence, in DDD mice oral stereotypies should be used as an index of LID in screening compounds for PD.
Topics: Mice; Animals; Levodopa; Dopamine Agonists; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dyskinesia, Drug-Induced; Mice, Knockout; Parkinson Disease; Amantadine
PubMed: 38002340
DOI: 10.3390/biom13111658 -
Signal Transduction and Targeted Therapy Sep 2023Substance use disorder remains a major challenge, with an enduring need to identify and evaluate new, translational targets for effective treatment. Here, we report the...
Substance use disorder remains a major challenge, with an enduring need to identify and evaluate new, translational targets for effective treatment. Here, we report the upregulation of Hypoxia-inducible factor-1α (HIF-1α) expression by roxadustat (Rox), a drug developed for renal anemia that inhibits HIF prolyl hydroxylase to prevent degradation of HIF-1α, administered either systemically or locally into selected brain regions, suppressed morphine (Mor)-induced conditioned place preference (CPP). A similar effect was observed with methamphetamine (METH). Moreover, Rox also inhibited the expression of both established and reinstated Mor-CPP and promoted the extinction of Mor-CPP. Additionally, the elevation of HIF-1α enhanced hepcidin/ferroportin 1 (FPN1)-mediated iron efflux and resulted in cellular iron deficiency, which led to the functional accumulation of the dopamine transporter (DAT) in plasma membranes due to iron deficiency-impaired ubiquitin degradation. Notably, iron-deficient mice generated via a low iron diet mimicked the effect of Rox on the prevention of Mor- or METH-CPP formation, without affecting other types of memory. These data reveal a novel mechanism for HIF-1α and iron involvement in substance use disorder, which may represent a potential novel therapeutic strategy for the treatment of drug abuse. The findings also repurpose Rox by suggesting a potential new indication for the treatment of substance use disorder.
Topics: Animals; Mice; Up-Regulation; Iron; Brain; Homeostasis; Iron Deficiencies; Hypoxia
PubMed: 37718358
DOI: 10.1038/s41392-023-01578-2 -
CNS Neuroscience & Therapeutics Sep 2023Electroacupuncture (EA) shows advantages in both clinical practice and depression animal models. Dopaminergic-related dysfunction in the prefrontal cortex (PFC) may be a...
Electroacupuncture alleviated depression-like behaviors in ventromedial prefrontal cortex of chronic unpredictable mild stress-induced rats: Increasing synaptic transmission and phosphorylating dopamine transporter.
AIMS
Electroacupuncture (EA) shows advantages in both clinical practice and depression animal models. Dopaminergic-related dysfunction in the prefrontal cortex (PFC) may be a hidden antidepressant mechanism of EA, where dopamine transporter (DAT) plays an essential role. This study aimed to investigate the synaptic transmission and DAT-related changes of EA in depression.
METHODS
Male Sprague-Dawley rats were subjected to 3-week chronic unpredictable mild stress (CUMS). The successfully modeled rats were then randomly and equally assigned to CUMS, selective serotonin reuptake inhibitor (SSRI), and EA or SSRI + EA groups, followed by a 2-week treatment respectively. After monitoring body weight and behavioral tests of all rats, the ventromedial PFC (vmPFC) tissue was collected for electrophysiology and the expression detection of DAT, phosphorylated DAT (p-DAT), cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), and trace amine-associated receptor 1 (TAAR1).
RESULTS
Depressive-like behaviors induced by CUMS were alleviated by EA, SSRI, and SSRI + EA treatments through behavioral tests. Compared with CUMS group, EA improved synaptic transmission in vmPFC by upregulating spontaneous excitatory postsynaptic currents amplitude. Molecularly, EA reversed the increased total DAT and p-DAT expression as well as the decreased ratio of p-DAT/total DAT along with the activation of TAAR1, cAMP, and PKA in vmPFC.
CONCLUSION
We speculated that the antidepressant effect of EA was associated with enhanced synaptic transmission in vmPFC, and the upregulated phosphorylation of DAT relevant to TAAR1, cAMP, and PKA may be the potential mechanism.
Topics: Rats; Male; Animals; Rats, Sprague-Dawley; Depression; Electroacupuncture; Dopamine Plasma Membrane Transport Proteins; Hippocampus; Antidepressive Agents; Synaptic Transmission; Selective Serotonin Reuptake Inhibitors; Prefrontal Cortex; Disease Models, Animal
PubMed: 37002793
DOI: 10.1111/cns.14200 -
Journal of Psychopharmacology (Oxford,... Nov 2023Major depressive disorder (MDD) is a leading cause of global disability. Several lines of evidence implicate the dopamine system in its pathophysiology. However, the... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Major depressive disorder (MDD) is a leading cause of global disability. Several lines of evidence implicate the dopamine system in its pathophysiology. However, the magnitude and consistency of the findings are unknown. We address this by systematically reviewing in vivo imaging evidence for dopamine measures in MDD and meta-analysing these where there are sufficient studies.
METHODS
Studies investigating the dopaminergic system using positron emission tomography or single photon emission computed tomography in MDD and a control group were included. Demographic, clinical and imaging measures were extracted from each study, and meta-analyses and sensitivity analyses were conducted.
RESULTS
We identified 43 studies including 662 patients and 801 controls. Meta-analysis of 38 studies showed no difference in mean or mean variability of striatal D receptor availability ( = 0.06, = 0.620), or combined dopamine synthesis and release capacity ( = 0.19, = 0.309). Dopamine transporter (DAT) availability was lower in the MDD group in studies using DAT selective tracers ( = -0.56, = 0.006), but not when tracers with an affinity for serotonin transporters were included ( = -0.21, = 0.420). Subgroup analysis showed greater dopamine release ( = 0.49, = 0.030), but no difference in dopamine synthesis capacity ( = -0.21, = 0.434) in the MDD group. Striatal D receptor availability was lower in patients with MDD in two studies.
CONCLUSIONS
The meta-analysis indicates striatal DAT availability is lower, but D receptor availability is not altered in people with MDD compared to healthy controls. There may be greater dopamine release and lower striatal D receptors in MDD, although further studies are warranted. We discuss factors associated with these findings, discrepancies with preclinical literature and implications for future research.
Topics: Humans; Dopamine; Depressive Disorder, Major; Tomography, Emission-Computed, Single-Photon; Positron-Emission Tomography; Receptors, Dopamine D2; Dopamine Plasma Membrane Transport Proteins
PubMed: 37811803
DOI: 10.1177/02698811231200881