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Addiction Biology Jan 2022Cocaine blocks dopamine uptake via dopamine transporter (DAT) on plasma membrane of neuron cells and, as a result, produces the high and induces DAT trafficking to...
Cocaine blocks dopamine uptake via dopamine transporter (DAT) on plasma membrane of neuron cells and, as a result, produces the high and induces DAT trafficking to plasma membrane which contributes to the drug seeking or craving. In this study, we first examined the dose dependence of cocaine-induced DAT trafficking and hyperactivity in rats, demonstrating that cocaine at an intraperitoneal dose of 10 mg/kg or higher led to redistribution of most DAT to the plasma membrane while inducing significant hyperactivity in rats. However, administration of 5-mg/kg cocaine (ip) did not significantly induce DAT trafficking or hyperactivity in rats. So the threshold (intraperitoneal) dose of cocaine that can significantly induce DAT trafficking or hyperactivity should be between 5 and 10 mg/kg. These data suggest that when a cocaine dose is high enough to induce significant hyperactivity, it can also significantly induce DAT trafficking to the plasma membrane. Further, the threshold brain cocaine concentration required to induce significant hyperactivity and DAT trafficking was estimated to be ~2.0 ± 0.8 μg/g. Particularly, for treatment of cocaine abuse, previous studies demonstrated that an exogenous cocaine-metabolizing enzyme, for example, CocH3-Fc(M3), can effectively block cocaine-induced hyperactivity. However, it was unknown whether an enzyme could also effectively block cocaine-induced DAT trafficking to the plasma membrane. This study demonstrates, for the first time, that the enzyme is also capable of effectively blocking cocaine from reaching the brain even with a lethal dose of 60-mg/kg cocaine (ip) and, thus, powerfully preventing cocaine-induced physiological effects such as the hyperactivity and DAT trafficking.
Topics: Animals; Carboxylic Ester Hydrolases; Cell Membrane; Cocaine; Cocaine-Related Disorders; Dopamine Plasma Membrane Transport Proteins; Dose-Response Relationship, Drug; Hyperkinesis; Male; Rats; Rats, Sprague-Dawley; Recombinant Proteins
PubMed: 34363291
DOI: 10.1111/adb.13089 -
Scientific Reports Feb 2021The human dopamine transporter (hDAT) is one in three members of the monoamine transporter family (MAT). hDAT is essential for regulating the dopamine concentration in...
The human dopamine transporter (hDAT) is one in three members of the monoamine transporter family (MAT). hDAT is essential for regulating the dopamine concentration in the synaptic cleft through dopamine reuptake into the presynaptic neuron; thereby controlling hDAT dopamine signaling. Dysfunction of the transporter is linked to several psychiatric disorders. hDAT and the other MATs have been shown to form oligomers in the plasma membrane, but only limited data exists on which dimeric and higher order oligomeric states are accessible and energetically favorable. In this work, we present several probable dimer conformations using computational coarse-grained self-assembly simulations and assess the relative stability of the different dimer conformations using umbrella sampling replica exchange molecular dynamics. Overall, the dimer conformations primarily involve TM9 and/or TM11 and/or TM12 at the interface. Furthermore, we show that a palmitoyl group (palm) attached to hDAT on TM12 modifies the free energy of separation for interfaces involving TM12, suggesting that S-palmitoylation may change the relative abundance of dimers involving TM12 in a biological context. Finally, a comparison of the identified interfaces of hDAT and palmitoylated hDAT to the human serotonin transporter interfaces and the leucine transporter interface, suggests similar dimer conformations across these protein family.
Topics: Biological Transport; Cell Membrane; Dopamine; Dopamine Plasma Membrane Transport Proteins; Humans; Molecular Dynamics Simulation; Protein Conformation; Protein Multimerization; Serotonin Plasma Membrane Transport Proteins
PubMed: 33602981
DOI: 10.1038/s41598-021-83374-y -
Scientific Reports Oct 2019The aim of this study was to evaluate associations of motor and non-motor symptoms with dopamine transporter binding in prodromal stage of synucleinopathies. We examined...
The aim of this study was to evaluate associations of motor and non-motor symptoms with dopamine transporter binding in prodromal stage of synucleinopathies. We examined 74 patients with idiopathic REM sleep behavior disorder (RBD), which is a prodromal synucleinopathy, and 39 controls using Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Montreal Cognitive Assessment, University of Pennsylvania Smell Identification Test (UPSIT), Farnsworth-Munsell 100 hue test, orthostatic test, Scales for Outcomes in PD-Autonomic, Beck depression inventory-II, State-Trait Anxiety Inventory, and video-polysomnography. Electromyographic muscle activity during REM sleep was quantified according to Sleep Innsbruck-Barcelona criteria. In 65 patients, dopamine transporter single-photon emission computed tomography (DAT-SPECT) imaging was performed, putaminal binding ratio was calculated and scans were classified as normal, borderline, or abnormal. Compared to controls, RBD patients had significantly more severe scores in all examined tests. Patients with abnormal DAT-SPECT had higher MDS-UPDRS motor score (p = 0.006) and higher prevalence of orthostatic hypotension (p = 0.008). Putaminal binding ratio was positively associated with UPSIT score (p = 0.03) and negatively associated with tonic (p = 0.003) and phasic (p = 0.01) muscle activity during REM sleep. These associations likely reflect simultaneous advancement of underlying pathology in substantia nigra and susceptible brainstem and olfactory nuclei in prodromal synucleinopathy.
Topics: Aged; Case-Control Studies; Dopamine Plasma Membrane Transport Proteins; Female; Humans; Male; Mental Status and Dementia Tests; Middle Aged; Polysomnography; Protein Binding; REM Sleep Behavior Disorder
PubMed: 31664065
DOI: 10.1038/s41598-019-51710-y -
The Journal of Neuroscience : the... Jun 2021Dopaminergic neurons of the substantia nigra pars compacta (SNC) and ventral tegmental area (VTA) exhibit spontaneous firing activity. The dopaminergic neurons in these...
Dopaminergic neurons of the substantia nigra pars compacta (SNC) and ventral tegmental area (VTA) exhibit spontaneous firing activity. The dopaminergic neurons in these regions have been shown to exhibit differential sensitivity to neuronal loss and psychostimulants targeting dopamine transporter. However, it remains unclear whether these regional differences scale beyond individual neuronal activity to regional neuronal networks. Here, we used live-cell calcium imaging to show that network connectivity greatly differs between SNC and VTA regions with higher incidence of hub-like neurons in the VTA. Specifically, the frequency of hub-like neurons was significantly lower in SNC than in the adjacent VTA, consistent with the interpretation of a lower network resilience to SNC neuronal loss. We tested this hypothesis, in DAT-cre/loxP-GCaMP6f mice of either sex, when activity of an individual dopaminergic neuron is suppressed, through whole-cell patch clamp electrophysiology, in either SNC or VTA networks. Neuronal loss in the SNC increased network clustering, whereas the larger number of hub-neurons in the VTA overcompensated by decreasing network clustering in the VTA. We further show that network properties are regulatable via a dopamine transporter but not a D2 receptor dependent mechanism. Our results demonstrate novel regulatory mechanisms of functional network topology in dopaminergic brain regions. In this work, we begin to untangle the differences in complex network properties between the substantia nigra pars compacta (SNC) and VTA, that may underlie differential sensitivity between regions. The methods and analysis employed provide a springboard for investigations of network topology in multiple deep brain structures and disorders.
Topics: Animals; Dopamine Plasma Membrane Transport Proteins; Dopaminergic Neurons; Female; Male; Mice; Nerve Net; Pars Compacta; Ventral Tegmental Area
PubMed: 33980544
DOI: 10.1523/JNEUROSCI.0223-21.2021 -
The Journal of Neuroscience : the... Feb 2017Midbrain dopamine neuron dysfunction contributes to various psychiatric and neurological diseases, including drug addiction and Parkinson's disease. Because of its well...
Midbrain dopamine neuron dysfunction contributes to various psychiatric and neurological diseases, including drug addiction and Parkinson's disease. Because of its well established dopaminotrophic effects, the therapeutic potential of glial cell line-derived neurotrophic factor (GDNF) has been studied extensively in various disorders with disturbed dopamine homeostasis. However, the outcomes from preclinical and clinical studies vary, highlighting a need for a better understanding of the physiological role of GDNF on striatal dopaminergic function. Nevertheless, the current lack of appropriate animal models has limited this understanding. Therefore, we have generated novel mouse models to study conditional deletion in the CNS during embryonic development and reduction of striatal GDNF levels in adult mice via AAV-Cre delivery. We found that both of these mice have reduced amphetamine-induced locomotor response and striatal dopamine efflux. Embryonic GDNF deletion in the CNS did not affect striatal dopamine levels or dopamine release, but dopamine reuptake was increased due to increased levels of both total and synaptic membrane-associated dopamine transporters. Collectively, these results suggest that endogenous GDNF plays an important role in regulating the function of dopamine transporters in the striatum. Delivery of ectopic glial cell line-derived neurotrophic factor (GDNF) promotes the function, plasticity, and survival of midbrain dopaminergic neurons, the dysfunction of which contributes to various neurological and psychiatric diseases. However, how the deletion or reduction of GDNF in the CNS affects the function of dopaminergic neurons has remained unknown. Using conditional knock-out mice, we found that endogenous GDNF affects striatal dopamine homeostasis and regulates amphetamine-induced behaviors by regulating the level and function of dopamine transporters. These data regarding the physiological role of GDNF are relevant in the context of neurological and neurodegenerative diseases that involve changes in dopamine transporter function.
Topics: Amphetamine; Animals; Brain; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Glial Cell Line-Derived Neurotrophic Factor; Male; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Random Allocation
PubMed: 28096470
DOI: 10.1523/JNEUROSCI.1673-16.2016 -
Movement Disorders : Official Journal... Oct 2017Idiopathic REM sleep behavior disorder is a prodromal stage of Parkinson's disease and dementia with Lewy bodies. Hyposmia, reduced dopamine transporter binding, and...
BACKGROUND
Idiopathic REM sleep behavior disorder is a prodromal stage of Parkinson's disease and dementia with Lewy bodies. Hyposmia, reduced dopamine transporter binding, and expression of the brain metabolic PD-related pattern were each associated with increased risk of conversion to PD. The objective of this study was to study the relationship between the PD-related pattern, dopamine transporter binding, and olfaction in idiopathic REM sleep behavior disorder.
METHODS
In this cross-sectional study, 21 idiopathic REM sleep behavior disorder subjects underwent F-fluorodeoxyglucose PET, dopamine transporter imaging, and olfactory testing. For reference, we included F-fluorodeoxyglucose PET data of 19 controls, 20 PD patients, and 22 patients with dementia with Lewy bodies. PD-related pattern expression z-scores were computed from all PET scans.
RESULTS
PD-related pattern expression was higher in idiopathic REM sleep behavior disorder subjects compared with controls (P = 0.048), but lower compared with PD (P = 0.001) and dementia with Lewy bodies (P < 0.0001). PD-related pattern expression was higher in idiopathic REM sleep behavior disorder subjects with hyposmia and in subjects with an abnormal dopamine transporter scan (P < 0.05, uncorrected).
CONCLUSION
PD-related pattern expression, dopamine transporter binding, and olfaction may provide complementary information for predicting phenoconversion. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
Topics: Aged; Analysis of Variance; Cross-Sectional Studies; Dopamine Plasma Membrane Transport Proteins; Female; Fluorodeoxyglucose F18; Humans; Lewy Body Disease; Male; Middle Aged; Olfaction Disorders; Parkinson Disease; Positron-Emission Tomography; Psychiatric Status Rating Scales; REM Sleep Behavior Disorder; Tomography, Emission-Computed, Single-Photon
PubMed: 28734065
DOI: 10.1002/mds.27094 -
The Journal of Biological Chemistry Dec 2015The duration and strength of the dopaminergic signal are regulated by the dopamine transporter (DAT). Drug addiction and neurodegenerative and neuropsychiatric diseases...
The duration and strength of the dopaminergic signal are regulated by the dopamine transporter (DAT). Drug addiction and neurodegenerative and neuropsychiatric diseases have all been associated with altered DAT activity. The membrane localization and the activity of DAT are regulated by a number of intracellular proteins. α-Synuclein, a protein partner of DAT, is implicated in neurodegenerative disease and drug addiction. Little is known about the regulatory mechanisms of the interaction between DAT and α-synuclein, the cellular location of this interaction, and the functional consequences of this interaction on the basal, amphetamine-induced DAT-mediated dopamine efflux, and membrane microdomain distribution of the transporter. Here, we found that the majority of DAT·α-synuclein protein complexes are found at the plasma membrane of dopaminergic neurons or mammalian cells and that the amphetamine-mediated increase in DAT activity enhances the association of these proteins at the plasma membrane. Further examination of the interaction of DAT and α-synuclein revealed a transient interaction between these two proteins at the plasma membrane. Additionally, we found DAT-induced membrane depolarization enhances plasma membrane localization of α-synuclein, which in turn increases dopamine efflux and enhances DAT localization in cholesterol-rich membrane microdomains.
Topics: Amphetamine; Animals; Biotinylation; Brain; CHO Cells; Cell Line; Cell Membrane; Cricetinae; Cricetulus; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dopaminergic Neurons; Fluorescence Resonance Energy Transfer; Humans; Membrane Microdomains; Neurodegenerative Diseases; Synaptic Transmission; Synucleins; alpha-Synuclein
PubMed: 26442590
DOI: 10.1074/jbc.M115.691592 -
Biomolecules May 2020The activity of the hypothalamus-pituitary-adrenal (HPA) axis is pivotal in homeostasis and presides the adaptative response to stress. Dopamine Transporter (DAT) plays...
The activity of the hypothalamus-pituitary-adrenal (HPA) axis is pivotal in homeostasis and presides the adaptative response to stress. Dopamine Transporter (DAT) plays a key role in the regulation of the HPA axis. We used young adult female DAT Knockout (KO) rats to assess the effects of DAT ablation (partial, heterozygous DAT+/-, or total, homozygous DAT-/-) on vulnerability to stress. DAT-/- rats show profound dysregulation of pituitary homeostasis, in the presence of elevated peripheral corticosterone, before and after acute restraint stress. During stress, DAT-/- rats show abnormal autonomic response at either respiratory and cardiovascular level, and delayed body temperature increase. DAT+/- rats display minor changes of hypophyseal homeostatic mechanisms. These rats display a similar pituitary activation to that of the control animals, albeit in the presence of higher release of peripheral corticosterone than DAT-/- after stress, and reduced temperature during stress. Our data indicate that DAT regulates the HPA axis at both the central and peripheral level, including autonomic function during stress. In particular, the partial deletion of DAT results in increased vulnerability to stress in female rats, which display central and peripheral alterations that are reminiscent of PTSD, and they might provide new insights in the pathophysiology of this disorder.
Topics: Animals; Dopamine Plasma Membrane Transport Proteins; Female; Locomotion; Male; Pituitary Gland; Rats; Rats, Wistar; Stress, Psychological
PubMed: 32486390
DOI: 10.3390/biom10060842 -
Movement Disorders : Official Journal... Sep 2020Numerous studies indicate an association between neurodegenerative and metabolic diseases. Although still a matter of debate, growing evidence from epidemiological and...
BACKGROUND
Numerous studies indicate an association between neurodegenerative and metabolic diseases. Although still a matter of debate, growing evidence from epidemiological and animal studies indicate that preexisting diabetes increases the risk to develop Parkinson's disease. However, the mechanisms of such an association are unknown.
OBJECTIVES
We investigated whether diabetes alters striatal dopamine neurotransmission and assessed the vulnerability of nigrostriatal neurons to neurodegeneration.
METHODS
We used streptozotocin-treated and genetically diabetic db/db mice. Expression of oxidative stress and nigrostriatal neuronal markers and levels of dopamine and its metabolites were monitored. Dopamine release and uptake were assessed using fast-scan cyclic voltammetry. 6-Hydroxydopamine was unilaterally injected into the striatum using stereotaxic surgery. Motor performance was scored using specific tests.
RESULTS
Diabetes resulted in oxidative stress and decreased levels of dopamine and its metabolites in the striatum. Levels of proteins regulating dopamine release and uptake, including the dopamine transporter, the Girk2 potassium channel, the vesicular monoamine transporter 2, and the presynaptic vesicle protein synaptobrevin-2, were decreased in diabetic mice. Electrically evoked levels of extracellular dopamine in the striatum were enhanced, and altered dopamine uptake was observed. Striatal microinjections of a subthreshold dose of the neurotoxin 6-hydroxydopamine in diabetic mice, insufficient to cause motor alterations in nondiabetic animals, resulted in motor impairment, higher loss of striatal dopaminergic axons, and decreased neuronal cell bodies in the substantia nigra.
CONCLUSIONS
Our results indicate that diabetes promotes striatal oxidative stress, alters dopamine neurotransmission, and increases vulnerability to neurodegenerative damage leading to motor impairment. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Topics: Animals; Corpus Striatum; Diabetes Mellitus, Experimental; Dopamine; Dopamine Plasma Membrane Transport Proteins; Mice; Substantia Nigra; Synaptic Transmission
PubMed: 32666590
DOI: 10.1002/mds.28124 -
PloS One 2019The human dopamine transporter gene SLC6A3 is involved in substance use disorders (SUDs) among many other common neuropsychiatric illnesses but allelic association... (Clinical Trial)
Clinical Trial
The human dopamine transporter gene SLC6A3 is involved in substance use disorders (SUDs) among many other common neuropsychiatric illnesses but allelic association results including those with its classic genetic markers 3'VNTR or Int8VNTR remain mixed and unexplainable. To better understand the genetics for reproducible association signals, we report the presence of recombination hotspots based on sequencing of the entire 5' promoter regions in two small SUDs cohorts, 30 African Americans (AAs) and 30 European Americans (EAs). Recombination rate was the highest near the transcription start site (TSS) in both cohorts. In addition, each cohort carried 57 different promoter haplotypes out of 60 and no haplotypes were shared between the two ethnicities. A quarter of the haplotypes evolved in an ethnicity-specific manner. Finally, analysis of five hundred subjects of European ancestry, from the 1000 Genome Project, confirmed the promoter recombination hotspots and also revealed several additional ones in non-coding regions only. These findings provide an explanation for the mixed results as well as guidance for selection of effective markers to be used in next generation association validation (NGAV), facilitating the delineation of pathogenic variation in this critical neuropsychiatric gene.
Topics: Black or African American; Cohort Studies; Dopamine Plasma Membrane Transport Proteins; Female; Genetic Markers; Genome, Human; Humans; Male; Recombination, Genetic; Substance-Related Disorders; White People
PubMed: 31185047
DOI: 10.1371/journal.pone.0218129