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International Journal of Molecular... Oct 2021Noradrenaline (NE) is a catecholamine acting as both a neurotransmitter and a hormone, with relevant effects in modulating feeding behavior and satiety. Several studies...
Noradrenaline (NE) is a catecholamine acting as both a neurotransmitter and a hormone, with relevant effects in modulating feeding behavior and satiety. Several studies have assessed the relationship between the noradrenergic system and Eating Disorders (EDs). This systematic review aims to report the existing literature on the role of the noradrenergic system in the development and treatment of EDs. A total of 35 studies were included. Preclinical studies demonstrated an involvement of the noradrenergic pathways in binge-like behaviors. Genetic studies on polymorphisms in genes coding for NE transporters and regulating enzymes have shown conflicting evidence. Clinical studies have reported non-unanimous evidence for the existence of absolute alterations in plasma NE values in patients with Anorexia Nervosa (AN) and Bulimia Nervosa (BN). Pharmacological studies have documented the efficacy of noradrenaline-modulating therapies in the treatment of BN and Binge Eating Disorder (BED). Insufficient evidence was found concerning the noradrenergic-mediated genetics of BED and BN, and psychopharmacological treatments targeting the noradrenergic system in AN. According to these data, further studies are required to expand the existing knowledge on the noradrenergic system as a potential target for treatments of EDs.
Topics: Adrenergic Neurons; Animals; Brain; Feeding Behavior; Feeding and Eating Disorders; Humans; Norepinephrine; Norepinephrine Plasma Membrane Transport Proteins
PubMed: 34681746
DOI: 10.3390/ijms222011086 -
Movement Disorders : Official Journal... Aug 2021Dopamine receptors are abundant along the central nigrostriatal tract and are expressed as 5 subtypes in two receptor families. In PD, compensatory changes in dopamine... (Meta-Analysis)
Meta-Analysis Review
Dopamine receptors are abundant along the central nigrostriatal tract and are expressed as 5 subtypes in two receptor families. In PD, compensatory changes in dopamine receptors emerge as a consequence of the loss of dopamine nerve terminals or dopaminergic pharmacotherapy. We performed a systematic review and meta-analysis of the available PET and single-photon emission computed tomography studies that have investigated dopamine receptors in PD, PSP and MSA. The inclusion criteria were studies including human PET or single-photon emission computed tomography imaging; dopamine receptor tracers (D1-like or D2-like) and idiopathic PD, PSP, or MSA patients compared with healthy controls. The 67 included D2-like studies had 1925 patients. Data were insufficient for an analysis of D1-like studies. PD patients had higher striatal binding early in the disease, but after a disease duration of 4.36 years, PD patients had lower binding values than healthy controls. Striatal D2R binding was highest in unmedicated early PD patients and in the striatum contralateral to the predominant motor symptoms. PSP and MSA-P patients had lower striatal D2R binding than PD patients (14.2% and 21.8%, respectively). There is initial upregulation of striatal D2Rs in PD, which downregulate on average 4 years after motor symptom onset, possibly because of agonist-induced effects. The consistent upregulation of D2Rs in the PD striatum contralateral to the predominant motor symptoms indicates that receptor changes are driven by neurodegeneration and loss of striatal neuropil. Both PSP and MSA patients have clearly lower striatal D2R binding values than PD patients, which offers an opportunity for differential diagnostics. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Topics: Corpus Striatum; Dopamine; Dopamine Plasma Membrane Transport Proteins; Humans; Parkinson Disease; Receptors, Dopamine D2; Tomography, Emission-Computed, Single-Photon
PubMed: 33955044
DOI: 10.1002/mds.28632 -
Frontiers in Neuroscience 2020The dopaminergic system is involved in many psychiatric disorders as a GABAergic, serotonergic, and glutamatergic system. A systematic review and meta-analysis was...
The dopaminergic system is involved in many psychiatric disorders as a GABAergic, serotonergic, and glutamatergic system. A systematic review and meta-analysis was performed to elucidate the alteration of the dopaminergic system in anxiety and compulsive disorders. The databases of Pubmed, Embase, and ScienceDirect were searched and articles reporting the involvement of the dopaminergic system in patients with anxiety disorder and obsessive compulsive disorder (OCD) were recognized. The key research data were extracted from the included articles and standardized mean differences were calculated using meta-analyses if there were more than two studies with obtainable data. Sensitivity analyses were further performed to detect the stability of results, and the qualities of all the included studies were assessed using the Newcastle Ottawa scale. Finally, we identified 8 and 11 studies associated with anxiety disorder and OCD for further analysis, respectively. Most consistently, the striatal dopamine D receptor (DR) of OCD patients had decreased while no significant correlation was found between striatal D2R and disease severity. The striatal dopamine transporter (DAT) had not been significantly altered in both the anxiety disorder and OCD patients. The heterogeneity values from the meta-analyses were extremely high while those results remained stable after sensitivity analyses. Inconsistent data were found in the striatal DR of patients with anxiety disorder. Limited data had suggested that dopamine synthesis increased in most regions of the cerebral cortex and cerebellum in OCD patients. The most convincing finding was that the D receptor decreased in patients with obsessive compulsive disorder. The dopamine transporter may have no relationship with anxiety and compulsive disorder.
PubMed: 33343291
DOI: 10.3389/fnins.2020.608520 -
Biological Psychiatry Oct 2019Many polymorphisms in dopamine genes are reported to affect cognitive, imaging, or clinical phenotypes. It is often inferred or assumed that such associations are... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Many polymorphisms in dopamine genes are reported to affect cognitive, imaging, or clinical phenotypes. It is often inferred or assumed that such associations are causal, mediated by a direct effect of the polymorphism on the gene product itself. However, the supporting evidence is not always clear.
METHODS
We conducted systematic reviews and meta-analyses to assess the empirical evidence for functional polymorphisms in genes encoding dopaminergic enzymes (COMT, DBH, DDC, MAOA, MAOB, and TH), dopamine receptors (DRD1, DRD2, DRD3, DRD4, and DRD5), the dopamine transporter (DAT), and vesicular transporters (VMAT1 and VMAT2). We defined functionality as an effect of the polymorphism on the expression, abundance, activity, or affinity of the gene product.
RESULTS
We screened 22,728 articles and identified 255 eligible studies. We found robust and medium to large effects for polymorphisms in 4 genes. For catechol-O-methyltransferase (COMT), the ValMet polymorphism (rs4680) markedly affected enzyme activity, protein abundance, and protein stability. Dopamine β-hydroxylase (DBH) activity was associated with rs1611115, rs2519152, and the DBH-STR polymorphism. Monoamine oxidase A (MAOA) activity was associated with a 5' VNTR polymorphism. Dopamine D receptor (DRD2) binding was influenced by the Taq1A (rs1800497) polymorphism, and rs1076560 affected DRD2 splicing.
CONCLUSIONS
Some widely studied dopaminergic polymorphisms clearly and substantially affect the abundance or activity of the encoded gene product. However, for other polymorphisms, evidence of such an association is negative, inconclusive, or lacking. These findings are relevant when selecting polymorphisms as "markers" of dopamine function, and for interpreting the biological plausibility of associations between these polymorphisms and aspects of brain function or dysfunction.
Topics: Brain; Dopamine; Dopamine Plasma Membrane Transport Proteins; Humans; Polymorphism, Single Nucleotide; Receptors, Dopamine
PubMed: 31303260
DOI: 10.1016/j.biopsych.2019.05.014 -
Journal of Neural Transmission (Vienna,... Apr 2019Attention-deficit hyperactivity disorder (ADHD) has been postulated to associate with dopaminergic dysfunction, including the dopamine transporter (DAT1). Several... (Meta-Analysis)
Meta-Analysis
Attention-deficit hyperactivity disorder (ADHD) has been postulated to associate with dopaminergic dysfunction, including the dopamine transporter (DAT1). Several meta-analyses showed small but significant association between the 10-repeat allele in the DAT1 gene in 3'-untranslated region variant number tandem repeat polymorphism and child and adolescent ADHD, whereas in adult ADHD the 9-repeat allele was suggested to confer as risk allele. Interestingly, recent evidence indicated that the long-allele variants (10 repeats and longer) might confer to lower expression of the transporter in comparison to the short-allele. Therefore, we assessed here the association in samples consisting of families with child and adolescent ADHD as well as a case-control sample, using either the 10- versus 9-repeat or the long- versus short-allele approach. Following, we conducted a systematic review and meta-analysis, including family and case-control studies, using the two aforementioned approaches as well as stratifying to age and ethnicity. The first approach (10-repeat) resulted in nominal significant association in child and adolescent ADHD (OR 1.1050 p = 0.0128), that became significant stratifying to European population (OR 1.1301 p = 0.0085). The second approach (long-allele) resulted in significant association with the whole ADHD population (OR 1.1046 p = 0.0048), followed by significant association for child and adolescent ADHD (OR 1.1602 p = 0.0006) and in Caucasian and in European child and adolescent ADHD (OR 1.1310 p = 0.0114; OR 1.1661 p = 0.0061; respectively). We were not able to confirm the association reported in adults using both approaches. In conclusion, we found further indication for a possible DAT1 gene involvement; however, further studies should be conducted with stringent phenotyping to reduce heterogeneity, a limitation observed in most included studies.
Topics: 3' Untranslated Regions; Adolescent; Attention Deficit Disorder with Hyperactivity; Child; Dopamine Plasma Membrane Transport Proteins; Female; Genetic Predisposition to Disease; Genome-Wide Association Study; Humans; Male; Minisatellite Repeats; Polymorphism, Genetic
PubMed: 30923918
DOI: 10.1007/s00702-019-01998-x -
Frontiers in Neurology 2018Around 30% Parkinson's disease (PD) patients develop impulse control disorders (ICDs) to D dopamine agonists and, to a lesser extent, levodopa. We aim to investigate...
Around 30% Parkinson's disease (PD) patients develop impulse control disorders (ICDs) to D dopamine agonists and, to a lesser extent, levodopa. We aim to investigate striatal dopaminergic function in PD patients with and without ICD. PubMed, Science Direct, EBSCO, and ISI Web of Science databases were searched (from inception to March 7, 2018) to identify PET or SPECT studies reporting striatal dopaminergic function in PD patients with ICD (ICD+) compared to those without ICD (ICD-). Studies which included drug naïve patients, explored non-pharmacological procedures (e.g., deep brain stimulation), and those using brain blood perfusion or non-dopaminergic markers were excluded. Standardized mean difference (SDM) was used and random-effect models were applied. Separate meta-analyses were performed for dopamine transporter level, dopamine release, and dopamine receptors availability in the putamen, caudate, dorsal, and ventral striatum. A total of 238 studies were title and abstract screened, of which 19 full-texts were assessed. Nine studies (ICD+: = 117; ICD-: = 175 patients) were included in the analysis. ICD+ showed a significant reduction of dopamine transporter binding in the putamen (SDM = -0.46; 95% CI: -0.80, -0.11; = 2.61; = 0.009), caudate (SDM = -0.38; 95% CI: -0.73, -0.04; = 2.18; = 0.03) and dorsal striatum (SDM = -0.45; 95% CI: -0.77, -0.13; = 2.76; = 0.006), and increased dopamine release to reward-related stimuli/gambling tasks in the ventral striatum (SDM = -1.04; 95% CI: -1.73, -0.35; = 2.95; = 0.003). Dopamine receptors availability did not differ between groups. Heterogeneity was low for dopamine transporter in the dorsal striatum ( = 0%), putamen ( = 0%) and caudate ( = 0%), and pre-synaptic dopamine release in the dorsal ( = 0%) and ventral striatum ( = 0%); heterogeneity was high for dopamine transporter levels in the ventral striatum ( = 80%), and for dopamine receptors availability in the ventral ( = 89%) and dorsal ( = 86%) striatum, putamen ( = 93%), and caudate ( = 71%). ICD+ patients show lower dopaminergic transporter levels in the dorsal striatum and increased dopamine release in the ventral striatum when engaged in reward-related stimuli/gambling tasks. This dopaminergic imbalance might represent a biological substrate for ICD in PD. Adequately powered longitudinal studies with drug naïve patients are needed to understand whether these changes may represent biomarkers of premorbid vulnerability to ICD.
PubMed: 30568628
DOI: 10.3389/fneur.2018.01018 -
Neuropsychopharmacology : Official... Mar 2019Use of alcohol, cannabis and opioids is highly prevalent and is associated with global disease burden and high economic costs. The exact pathophysiology of abuse or... (Meta-Analysis)
Meta-Analysis
Use of alcohol, cannabis and opioids is highly prevalent and is associated with global disease burden and high economic costs. The exact pathophysiology of abuse or addiction associated with these sedative substances is not completely understood, but previous research implicates the important role of the striatal dopamine system in the addiction process. Multiple studies investigated changes in the striatal dopamine systems of users of sedative substances, but currently these results are very heterogeneous. Therefore, we conducted a meta-analysis of in vivo neuroimaging studies investigating dopaminergic alterations in the striatum of users of alcohol, opioids or cannabis. Analyses for each substance were conducted separately for the availability of D2/D3 dopamine receptors, dopamine transporters and dopamine synthesis capacity. In total, 723 substance users and 752 healthy controls were included. The results indicated a significant lower striatal D2/D3 receptor availability in alcohol users compared to controls (g = 0.46) but no difference in dopamine transporter availability or dopamine synthesis capacity. Our analysis indicated that changes of dopamine receptors and transporters are moderated by the duration of abstinence. Comparing opioid users with controls revealed a significant lower D2/D3 receptor availability (g = 1.17) and a significantly lower transporter availability (g = 1.55) in opioid users. For cannabis users, there was no significant difference in receptor availability compared to controls and too few studies provided information on dopamine transporter availability or synthesis capacity. Our analysis provides strong evidence for a central role of the striatal dopamine system in use of alcohol or opioids. Further studies are needed to clarify the impact of the dopamine system in cannabis users.
Topics: Alcoholism; Corpus Striatum; Dopamine Plasma Membrane Transport Proteins; Humans; Marijuana Abuse; Neuroimaging; Opioid-Related Disorders; Receptors, Dopamine D2; Receptors, Dopamine D3
PubMed: 30188512
DOI: 10.1038/s41386-018-0191-9 -
Translational Psychiatry Aug 2018Despite intense research, the underlying mechanisms and the etiology of Tourette's syndrome (TS) remain unknown. Data from molecular imaging studies targeting the... (Meta-Analysis)
Meta-Analysis
Despite intense research, the underlying mechanisms and the etiology of Tourette's syndrome (TS) remain unknown. Data from molecular imaging studies targeting the dopamine system in Tourette patients are inconclusive. For a better understanding of the striatal dopamine function in adult dopamine-antagonist-free patients we performed a systematic review in August 2017 identifying 49 PET and SPECT studies on the topic of TS. A total of 8 studies appraised the dopamine transporter (DAT) with 111 Tourette patients and 93 healthy controls, and could be included in a meta-analytic approach. We found a significantly increased striatal DAT binding in Tourette patients (Hedges' g = 0.49; 95% CI: (0.01-0.98)), although this effect did not remain significant after correcting for age differences between cohorts. A second meta-analysis was performed for the striatal dopamine receptor including 8 studies with a total of 72 Tourette patients and 71 controls. This analysis revealed a nonsignificant trend toward lower dopamine 2/3 receptor binding in striatum of Tourette patients. Other analyses regarding study population characteristics in both the DAT and receptor meta-analysis did not show any meaningful results. Our results indicate that dopaminergic alterations in TS are likely and thereby this data would be in line with the current pathophysiological hypotheses of a dysfunction in the dopamine system, e.g., the hypothesis of tonic-phasic dysfunction. However, these analyses suffer from low effect sizes probably due to the heterogeneity of TS and highlight the need for further large-scaled neuroimaging studies.
Topics: Case-Control Studies; Dopamine; Dopamine Antagonists; Dopamine Plasma Membrane Transport Proteins; Humans; Neostriatum; Neuroimaging; Positron-Emission Tomography; Receptors, Dopamine D2; Tomography, Emission-Computed, Single-Photon; Tourette Syndrome
PubMed: 30072700
DOI: 10.1038/s41398-018-0202-y -
JAMA Psychiatry May 2017Stimulant use disorder is common, affecting between 0.3% and 1.1% of the population, and costs more than $85 billion per year globally. There are no licensed treatments... (Meta-Analysis)
Meta-Analysis Review
IMPORTANCE
Stimulant use disorder is common, affecting between 0.3% and 1.1% of the population, and costs more than $85 billion per year globally. There are no licensed treatments to date. Several lines of evidence implicate the dopamine system in the pathogenesis of substance use disorder. Therefore, understanding the nature of dopamine dysfunction seen in stimulant users has the potential to aid the development of new therapeutics.
OBJECTIVE
To comprehensively review the in vivo imaging evidence for dopaminergic alterations in stimulant (cocaine, amphetamine, or methamphetamine) abuse or dependence.
DATA SOURCES
The entire PubMed, EMBASE, and PsycINFO databases were searched for studies from inception date to May 14, 2016.
STUDY SELECTION
Case-control studies were identified that compared dopaminergic measures between stimulant users and healthy controls using positron emission tomography or single-photon emission computed tomography to measure striatal dopamine synthesis or release or to assess dopamine transporter availability or dopamine receptor availability.
DATA EXTRACTION AND SYNTHESIS
Demographic, clinical, and imaging measures were extracted from each study, and meta-analyses and sensitivity analyses were conducted for stimulants combined, as well as for cocaine and for amphetamine and methamphetamine separately if there were sufficient studies.
MAIN OUTCOMES AND MEASURES
Differences were measured in dopamine release (assessed using change in the D2/D3 receptor availability after administration of amphetamine or methylphenidate), dopamine transporter availability, and dopamine receptor availability in cocaine users, amphetamine and methamphetamine users, and healthy controls.
RESULTS
A total of 31 studies that compared dopaminergic measures between 519 stimulant users and 512 healthy controls were included in the final analysis. In most of the studies, the duration of abstinence varied from 5 days to 3 weeks. There was a significant decrease in striatal dopamine release in stimulant users compared with healthy controls: the effect size was -0.84 (95% CI, -1.08 to -0.60; P < .001) for stimulants combined and -0.87 (95% CI, -1.15 to -0.60; P < .001) for cocaine. In addition, there was a significant decrease in dopamine transporter availability: the effect size was -0.91 (95% CI, -1.50 to -0.32; P < .01) for stimulants combined and -1.47 (95% CI, -1.83 to -1.10; P < .001) for amphetamine and methamphetamine. There was also a significant decrease in D2/D3 receptor availability: the effect size was -0.76 (95% CI, -0.92 to -0.60; P < .001) for stimulants combined, -0.73 (95% CI, -0.94 to -0.53; P < .001) for cocaine, and -0.81 (95% CI, -1.12 to -0.49; P < .001) for amphetamine and methamphetamine. Consistent alterations were not found in vesicular monoamine transporter, dopamine synthesis, or D1 receptor studies.
CONCLUSIONS AND RELEVANCE
Data suggest that both presynaptic and postsynaptic aspects of the dopamine system in the striatum are down-regulated in stimulant users. The commonality and differences between these findings and the discrepancies with the preclinical literature and models of drug addiction are discussed, as well as their implications for future drug development.
Topics: Amphetamine-Related Disorders; Cocaine-Related Disorders; Corpus Striatum; Dopamine; Dopamine Plasma Membrane Transport Proteins; Humans; Receptors, Dopamine
PubMed: 28297025
DOI: 10.1001/jamapsychiatry.2017.0135 -
Translational Psychiatry Jan 2017Disrupted-in-Schizophrenia 1 (DISC1) is a gene known as a risk factor for mental illnesses possibly associated with dopamine impairments. DISC1 is a scaffold protein... (Review)
Review
Disrupted-in-Schizophrenia 1 (DISC1) is a gene known as a risk factor for mental illnesses possibly associated with dopamine impairments. DISC1 is a scaffold protein interacting with proteins involved in the dopamine system. Here we summarise the impact of DISC1 disruption on the dopamine system in animal models, considering its effects on presynaptic dopaminergic function (tyrosine hydroxylase levels, dopamine transporter levels, dopamine levels at baseline and after amphetamine administration) and postsynaptic dopaminergic function (dopamine D1 and D2 receptor levels, dopamine receptor-binding potential and locomotor activity after amphetamine administration). Our findings show that many but not all DISC1 models display (1) increased locomotion after amphetamine administration, (2) increased dopamine levels after amphetamine administration in the nucleus accumbens, and (3) inconsistent basal dopamine levels, dopamine receptor levels and binding potentials. There is also limited evidence for decreased tyrosine hydroxylase levels in the frontal cortex and increased dopamine transporter levels in the striatum but not nucleus accumbens, but these conclusions warrant further replication. The main dopaminergic findings are seen across different DISC1 models, providing convergent evidence that DISC1 has a role in regulating dopaminergic function. These results implicate dopaminergic dysregulation as a mechanism underlying the increased rate of schizophrenia seen in DISC1 variant carriers, and provide insights into how DISC1, and potentially DISC1-interacting proteins such as AKT and GSK-3, could be used as novel therapeutic targets for schizophrenia.
Topics: Amphetamine; Animals; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Locomotion; Mice; Nerve Tissue Proteins; Nucleus Accumbens; Rats; Receptors, Dopamine D1; Receptors, Dopamine D2; Tyrosine 3-Monooxygenase
PubMed: 28140405
DOI: 10.1038/tp.2016.282