alpha-synuclein and Alcoholism

Alpha-synuclein (α-Syn) is a 140-amino acid (aa) protein encoded by the Synuclein alpha SNCA gene. It is the synaptic protein associated with Parkinson's disease (PD) and is the most highly expressed protein in the Lewy bodies associated with PD and other alpha synucleopathies, including Lewy body dementia (LBD) and multiple system atrophy (MSA). Iron deposits are present in the core of Lewy bodies, and there are reports suggesting that divalent metal ions including Cu

Topics: 5' Untranslated Regions; Alcoholism; alpha-Synuclein; Brain; Gene Expression Regulation; Humans; Lewy Bodies; Neurons; Parkinson Disease; Small Molecule Libraries

Alcoholism has complex etiology and there is evidence for both genetic and environmental factors in its pathophysiology. Chronic, long-term alcohol abuse and alcohol dependence are associated with neuronal loss with the prefrontal cortex being particularly susceptible to neurotoxic damage. This brain region is involved in the development and persistence of alcohol addiction and neurotoxic damage is likely to exacerbate the reinforcing effects of alcohol and may hinder treatment. Understanding the mechanism of alcohol's neurotoxic effects on the brain and the genetic risk factors associated with alcohol abuse are the focus of current research. Because of its well-established role in neurodegenerative and neuropsychological disorders, and its emerging role in the pathophysiology of addiction, here we review the genetic and epigenetic factors involved in regulating α-synuclein expression and its potential role in the pathophysiology of chronic alcohol abuse. Elucidation of the mechanisms of α-synuclein regulation may prove beneficial in understanding the role of this key synaptic protein in disease and its potential for therapeutic modulation in the treatment of substance use disorders as well as other neurodegenerative diseases.

Topics: Alcoholism; alpha-Synuclein; Brain; Ethanol; Humans; MicroRNAs; Phenotype

A major focus of research in alcohol-related disorders is to identify the genes and pathways that modulate alcohol-seeking behavior. In light of this, animal models have been established to study various aspects of alcohol dependence. The selectively bred alcohol-preferring (P) and -nonpreferring (NP) lines were developed from Wistar rats to model high and low voluntary alcohol consumption, respectively. Using inbred P and NP strains, a strong QTL (LOD-9.2) for alcohol consumption was identified on rat chromosome 4. To search for candidate genes that underlie this chromosomal region, complementary molecular-based strategies were implemented to identify genetic targets that likely contribute to the linkage signal. In an attempt to validate these genetic targets, corroborative studies have been utilized including pharmacological studies, knock-out/transgenic models as well as human association studies. Thus far, three candidate genes, neuropeptide Y (Npy), alpha-synuclein (Snca), and corticotrophin-releasing factor receptor 2 (Crhr2), have been identified that may account for the linkage signal. With the recent advancements in bioinformatics and molecular biology, QTL analysis combined with molecular-based strategies provides a systematic approach to identify candidate genes that contribute to various aspects of addictive behavior.

Topics: Alcohol Drinking; Alcohol-Related Disorders; Alcoholism; alpha-Synuclein; Animals; Chromosome Mapping; Humans; Models, Genetic; Neuropeptide Y; Quantitative Trait Loci; Rats; Rats, Wistar; Receptors, Corticotropin-Releasing Hormone

Introduction: Excessive alcohol consumption results in neuroadaptation, neurodegeneration, and differential expression of numerous genes.\ Objective: To determine the relationship between the expression of the alpha synuclein gene (SNCA) in blood, single nucleotide variant (SNV) in its promoter region, and chronic constipation in people with problems of alcohol consumption.\ Materials and methods: The sample consisted of 35 controls and 27 cases selected according to the score obtained with the AUDIT tool. For the diagnosis of constipation, the Rome IV criteria were applied. Nucleic acid extraction was performed from peripheral blood and the expression of the gene was evaluated by qPCR, protein quantification by ELISA, and the presence of SNV in the promoter region of the gene by Sanger sequencing.\ Results: We observed a relative gene overexpression of SNCA mRNA in the case group, which was not related to the diagnosis of chronic constipation. There was 4.8 times greater risk of presenting constipation in the group of cases. Besides, nine single nucleotide variants were found in a segment of the promoter region of the gene rich in CpG regulatory sequences with similar frequency between the groups while a variant was identified in position -2171, which is not reported in GenBank for variants and whose genotype A/T was associated with increased expression of SNCA mRNA.\ Conclusion: We evidenced an overexpression of alpha synuclein mRNA in people with problems of alcohol consumption that was not related to the diagnosis of chronic constipation.. Introducción. El consumo excesivo de alcohol resulta en neuroadaptación, neurodegeneración y expresión diferencial de numerosos genes. Objetivo. Determinar la relación entre la expresión del gen de la alfa sinucleína (SNCA) en sangre, las variantes de nucleótido único (Single Nucleotide Variant, SNV) en su región promotora y el estreñimiento crónico en personas con problemas de consumo de alcohol. Materiales y métodos. La muestra estuvo conformada por 35 controles y 27 casos, seleccionados según el puntaje obtenido con la herramienta AUDIT. En el diagnóstico del estreñimiento se aplicaron los criterios de Roma IV. La extracción de ácidos nucleicos se hizo a partir de sangre periférica y se evaluó la expresión del gen mediante qPCR, la cuantificación proteica por ELISA y la presencia de SNV en la región promotora del gen por la secuenciación de Sanger. Resultados. Se observó sobreexpresión génica relativa de ARNm del gen SNCA en el grupo de casos sin relación con el estreñimiento crónico. Se evidenció un riesgo 4,8 veces mayor de presentar estreñimiento en el grupo de casos. Se encontraron nueve variantes de nucleótido simple en un segmento de la región promotora del gen rica en secuencias reguladoras CpG, con frecuencia similar entre los grupos, y se detectó una variante en la posición -2171 que no se encuentra reportada en GenBank para variantes clínicas y cuyo genotipo A/T se relacionó con el incremento de la expresión del ARNm del SNCA. Conclusión. En personas con problemas de consumo de alcohol se evidenció la sobreexpresión del ARNm de alfa sinucleína, lo cual no se relacionó con el diagnóstico de estreñimiento crónico.

Topics: Adult; Alcoholism; alpha-Synuclein; Case-Control Studies; Chronic Disease; Colombia; Constipation; Female; Gastrointestinal Motility; Gene Expression; Gene Frequency; Humans; Inflammation; Leukocytes, Mononuclear; Male; Polymorphism, Single Nucleotide; Prevalence; Promoter Regions, Genetic; RNA, Messenger; Urban Population; Young Adult

Data have shown a role of α-synuclein in anxiety and also in addiction, particularly in alcohol use disorders (AUD). Since the comorbidity between AUD and anxiety is very high and because anxiety is an important factor in ethanol (EtOH) relapse, the aim of the present study was to investigate the role of α-synuclein in moderating EtOH intake, the anxiolytic effects of EtOH, and EtOH withdrawal-induced anxiety and convulsions in mice. The study aimed to determine whether SNCA variants moderated anxiety in EtOH-dependent patients.. We analyzed the moderator effect of 3 SNCA Tag-single nucleotide polymorphisms (Tag-SNPs) rs356200, rs356219, and rs2119787 on the anxiety symptoms in 128 EtOH-dependent patients. We used the C57BL/6JOlaHsd Snca mutant mice to assess EtOH intake; sensitivity to the anxiolytic effects of EtOH in a test battery comprising the open field, the light-dark box, and the elevated plus maze; and both anxiety and convulsions induced by EtOH withdrawal.. Our results demonstrated a reduction in both EtOH intake and preference and also a lack of sensitivity to the anxiolytic effects of EtOH in α-synuclein mutant mice. Results on anxiety-like behavior were mixed, but mutant mice displayed increased anxiety when exposed to a low anxiogenic environment. Mutant mice also displayed an increase in handling-induced convulsion scores during withdrawal after EtOH inhalation, but did not differ in terms of EtOH withdrawal-induced anxiety. In humans, we found a significant association of the rs356219 SNP with a high level of anxiety (Beck Anxiety Inventory score >15) and the rs356200 SNP with a positive familial history of AUD.. Our translational study highlights a significant role of α-synuclein in components of AUD.

Topics: Adult; Alcoholism; alpha-Synuclein; Animals; Anxiety; Behavior, Animal; Central Nervous System Depressants; Ethanol; Female; Humans; Male; Mice; Mice, Inbred C57BL; Middle Aged; Motor Activity; Mutation; Neuropsychological Tests; Polymorphism, Single Nucleotide; Seizures; Substance Withdrawal Syndrome; Young Adult

To observe the changes of expression of α-synuclein （α-syn） and neuronal apoptosis in brain cortex of acute alcoholism rats and to explore the mechanism of the damage caused by ethanol to the neurons.. The model of acute alcoholism rat was established by 50% alcohol gavage. The α-syn and caspase-3 were detected by immunohistochemical staining and imaging analysis at 1 h, 3 h, 6 h and 12 h after acute alcoholism. The number of positive cell and mean of optical density were detected and the trend change was analyzed. The variance analysis and. The number of α-syn positive cell and average optical density in brain cortex of acute alcoholism rat increased significantly and peaked at 6 hour with a following slight decrease at 12 h, but still higher than the groups at 1 h and 3 h. Within 12 hours after poisoning, the number of caspase-3 positive cell and average optical density in brain cortex of rats gradually increased.. The abnormal aggregation of α-syn caused by brain edema and hypoxia may participate the early stage of neuronal apoptosis in brain cortex after acute alcoholism.

Topics: Alcoholism; alpha-Synuclein; Animals; Apoptosis; Brain Edema; Caspase 3; Cerebral Cortex; Ethanol; Hypoxia; Neurons; Rats

Chronic alcohol misuse causes damage in the central nervous system that may lead to tolerance, craving and dependence. These behavioural changes are likely the result of cellular adaptations that include changes in gene expression. α-Synuclein is involved in the dopaminergic reward pathway, where it regulates dopamine synthesis and release. Previous studies have found that the gene for α-synuclein, SNCA, is differentially expressed in alcohol misusers.. The present study measured the expression of three α-synuclein variants, SNCA-140, SNCA-112, and SNCA-115 in the prefrontal cortex of controls and alcohol misusers with and without cirrhosis of the liver. In addition, eight SNPs located in the 5'- and 3'-UTRs were genotyped in a Caucasian population of 125 controls and 115 alcohol misusers.. The expression of SNCA-140 and SNCA-112 was significantly lower in alcohol misusers with cirrhosis than in controls. However, SNCA-115 expression was significantly greater in alcohol misusers with cirrhosis than in controls. Allele and genotype frequencies differed significantly between alcohol misusers and controls for three SNPs, rs356221, rs356219 and rs2736995. Two SNPs, rs356221 and rs356219, were in high linkage disequilibrium. There was no increased risk of alcoholism associated with specific genotypes or haplotypes. Our results suggest that the rs356219/356221 G-A haplotype may decrease the chance of having an alcohol misuse phenotype.. These findings suggest that alcohol misuse may alter the expression of the individual α-synuclein splice variants differently in human brain. There was no evidence of an effect of sequence variation on the expression of α-synuclein splice variants in this population.

Topics: Alcoholism; Alleles; alpha-Synuclein; Case-Control Studies; Gene Expression; Genetic Variation; Genotype; Haplotypes; Humans; Linkage Disequilibrium; Liver Cirrhosis, Alcoholic; Polymorphism, Single Nucleotide; Prefrontal Cortex; Protein Isoforms; White People

α-Synuclein has recently been implicated in the pathophysiology of alcohol abuse due to its role in dopaminergic neurotransmission. In these studies, genetic variability in the α-synuclein gene influences its expression which may contribute to susceptibility to chronic alcohol abuse. Real-time PCR was used to quantify α-synuclein mRNA expression in autopsy samples of human dorsolateral prefrontal cortex. Because of the association between length of the α-synuclein-repeat 1 microsatellite marker and expression levels of the gene, this marker was genotyped in a Caucasian sample of 126 controls and 117 alcoholics using capillary gel electrophoresis. The allele and genotype frequencies of α-synuclein-repeat 1 marker differed significantly between alcoholics and controls. Alcoholics had greater frequencies of the shortest allele found (267 bp). The shortest allele of the α-synuclein-repeat 1 marker was associated with decreased expression of α-synuclein in prefrontal cortex. Individuals with at least one copy of the 267 bp allele were more likely to exhibit an alcohol abuse phenotype. These results suggest that individuals with the 267 bp allele may be at increased risk of developing alcoholism and that genetic variation at the α-synuclein-repeat 1 locus may influence α-synuclein expression in the prefrontal cortex.

Topics: Alcoholism; alpha-Synuclein; Case-Control Studies; Female; Gene Frequency; Genotype; Humans; Male; Middle Aged; Prefrontal Cortex; RNA, Messenger

Craving is being considered for inclusion in the Diagnostic and Statistical Manual (DSM) DSM-5. However, little is known of its genetic underpinnings - specifically, whether genetic influences on craving are distinct from those influencing DSM-IV alcohol dependence.. Analyses were conducted in a sample of unrelated adults ascertained for alcohol dependence (N=3976). Factor analysis was performed to examine how alcohol craving loaded with the existing DSM-IV alcohol dependence criteria. For genetic analyses, we first examined whether genes in the dopamine pathway, including dopamine receptor genes (DRD1, DRD2, DRD3, DRD4) and the dopamine transporter gene (SLC6A3), which have been implicated in neurobiological studies of craving, as well as alpha-synuclein (SNCA), which has been previously found to be associated with craving, were associated with alcohol craving in this sample. Second, in an effort to identify novel genetic variants associated with craving, we conducted a genomewide association study (GWAS). For variants that were implicated in the primary analysis of craving, we conducted additional comparisons - to determine if these variants were uniquely associated with alcohol craving as compared with alcohol dependence. We contrasted our results to those obtained for DSM-IV alcohol dependence, and also compared alcohol dependent individuals without craving to non-dependent individuals who also did not crave alcohol.. Twenty-one percent of the full sample reported craving alcohol. Of those reporting craving, 97.3% met criteria for DSM-IV alcohol dependence with 48% endorsing all 7 dependence criteria. Factor analysis found a high factor loading (0.89) for alcohol craving. When examining genes in the dopamine pathway, single nucleotide polymorphisms (SNPs) in DRD3 and SNCA were associated with craving (p<0.05). There was evidence for association of these SNPs with DSM-IV alcohol dependence (p<0.05) but less evidence for dependence without craving (p>0.05), suggesting that the association was due in part to craving. In the GWAS, the greatest evidence of association with craving was for a SNP in the integrin alpha D (ITGAD) gene on chromosome 7 (rs2454908; p=1.8×10(-6)). The corresponding p-value for this SNP with DSM-IV alcohol dependence was similar (p=4.0×10(-5)) but was far less with dependence without craving (p=0.02), again suggesting the association was due to alcohol craving. Adjusting for dependence severity (number of endorsed criteria) attenuated p-values but did not eliminate association.. Craving is frequently reported by those who report multiple other alcohol dependence symptoms. We found that genes providing evidence of association with craving were also associated with alcohol dependence; however, these same SNPs were not associated with alcohol dependence in the absence of alcohol craving. These results suggest that there may be unique genetic factors affecting craving among those with alcohol dependence.

Topics: Adult; Alcoholism; alpha-Synuclein; CD11 Antigens; Cues; Diagnostic and Statistical Manual of Mental Disorders; Dopamine Plasma Membrane Transport Proteins; Factor Analysis, Statistical; Female; Genetic Predisposition to Disease; Genome-Wide Association Study; Genotype; Humans; Integrin alpha Chains; Logistic Models; Male; Polymorphism, Single Nucleotide; Psychometrics; Receptors, Dopamine; Severity of Illness Index

Preclinical studies implicate the gene encoding the alpha synuclein protein (SNCA) in the pathophysiology of alcohol dependence and dopamine neuron function. Results from clinical studies are less conclusive. Using neurobiological phenotypes in genetic studies, rather than typical heterogeneous diagnostic categories derived from self-report, may improve reliability across studies. This study aimed to examine whether polymorphisms in the SNCA gene were associated with alcohol taste cue-elicited responses in the brain, one such intermediate phenotype.. A total of 326 heavy drinkers who underwent an alcohol taste task during functional magnetic resonance imaging (fMRI) also were genotyped. Analyses focused on two previously identified SNCA variants (rs2583985 and rs356168) as well as 27 other single nucleotide polymorphisms from the Illumina Human1M BeadChip that were used in an exploratory analysis of the whole gene. Neurobiological phenotypes were defined as fMRI blood oxygenation level-dependent (BOLD) responses to alcohol taste cue (vs. a control cue) in seven regions of interest known to be involved in cue processing and rich in dopaminergic axon terminals.. Polymorphisms in the SNCA gene were significantly correlated with BOLD activation. Specifically, the largest effect sizes and significance were seen for rs2583985 in paracingulate and caudate (focused analysis) and for rs1372522 in paracingulate (exploratory analysis). Activation in all regions of interest was correlated with alcohol-dependence severity.. SNCA genotype was found to be associated with the degree of fMRI BOLD response during exposure to the taste of alcohol versus a control taste. This study also further validates the use of this alcohol taste task as an intermediate phenotype for alcohol-dependence severity.

Topics: Adult; Alcoholism; alpha-Synuclein; Axons; Brain; Brain Mapping; Cues; Dopamine; Female; Functional Neuroimaging; Humans; Magnetic Resonance Imaging; Male; Oxygen; Polymorphism, Single Nucleotide; Severity of Illness Index

Collaborative pooled analyses demonstrated that allele length variability of the dinucleotide repeat sequence within the alpha-synuclein gene promoter (SNCA REP1) is associated with Parkinson disease (PD) worldwide. Other studies demonstrated that variability in the SNCA promoter is also associated with alcohol use disorders, but not consistently. Yet other studies demonstrated that alcohol use disorders are inversely associated with PD, but not consistently. The aim of this study was to clarify the patterns of association between REP1 genotype, alcohol use disorders, and PD. Cases were recruited from the Department of Neurology of the Mayo Clinic in Rochester, MN. The controls included unaffected siblings and unrelated controls. We assessed alcohol use via a structured telephone interview and screened for alcohol use disorders using the CAGE questionnaire. REP1 genotyping was performed using an ABI 3730XL platform. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined using conditional logistic regression models. We recruited 893 case-control pairs. There was an increasing risk of PD with increasing SNCA REP1 allele length (OR 1.18 for each REP1 genotype score unit, 95% CI 1.02-1.35; p=0.02). There was a decreasing risk of PD with increasing CAGE score (p=0.01). The association of REP1 score with PD remained significant after adjusting for CAGE score, and the association of CAGE score with PD remained significant after adjusting for REP1 score. There were no pairwise interactions. Our findings suggest that SNCA REP1 genotype and alcohol use disorders are independently associated with PD.

Topics: Adult; Aged; Aged, 80 and over; Alcohol Drinking; Alcoholism; alpha-Synuclein; Case-Control Studies; Dinucleotide Repeats; DNA Mutational Analysis; Female; Gene Frequency; Genetic Predisposition to Disease; Genotype; Humans; Male; Middle Aged; Multivariate Analysis; Parkinson Disease; Promoter Regions, Genetic; Risk Factors

Epidemiological studies have indicated that excessive alcohol consumption leads to cognitive impairment, but the specific pathological mechanism involved remains unknown. The present study evaluated the association between heavy alcohol intake and the neuropathological hallmark lesions of the three most common neurodegenerative disorders, i.e., Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and vascular cognitive impairment (VCI), in post-mortem human brains. The study cohort was sampled from the subjects who underwent a medicolegal autopsy during a 6-month period in 1999 and it included 54 heavy alcohol consumers and 54 age- and gender-matched control subjects. Immunohistochemical methodology was used to visualize the aggregation of beta-amyloid, hyperphosphorylated tau, and alpha-synuclein and the extent of infarcts. In the present study, no statistically significant influence was observed for alcohol consumption on the extent of neuropathological lesions encountered in the three most common degenerative disorders. Our results indicate that alcohol-related dementia differs from VCI, AD, and DLB; i.e., it has a different etiology and pathogenesis.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Alcohol-Induced Disorders, Nervous System; Alcoholism; alpha-Synuclein; Alzheimer Disease; Amyloid beta-Peptides; Autopsy; Biomarkers; Brain; Central Nervous System Depressants; Child; Cohort Studies; Dementia; Dementia, Vascular; Disease Progression; Ethanol; Female; Finland; Humans; Lewy Body Disease; Male; Middle Aged; tau Proteins; Young Adult

A genomic region neighboring the alpha-synuclein gene, on rat chromosome 4, has been associated with anxiety- and alcohol-related behaviors in different rat strains. In this study, we have investigated potential molecular and physiological links between alpha-synuclein and the behavioral differences observed between Lewis (LEW) and Spontaneously Hypertensive (SHR) inbred rats, a genetic model of anxiety. As expected, LEW rats appeared more fearful than SHR rats in three anxiety models: open field, elevated plus maze and light/dark box. Moreover, LEW rats displayed a higher preference for alcohol and consumed higher quantities of alcohol than SHR rats. alpha-Synuclein mRNA and protein concentrations were higher in the hippocampus, but not the hypothalamus of LEW rats. This result inversely correlated with differences in dopamine turnover in the hippocampus of LEW and SHR rats, supporting the hypothesis that alpha-synuclein is important in the downregulation of dopamine neurotransmission. A novel single nucleotide polymorphism was identified in the 3'-untranslated region (3'-UTR) of the alpha-synuclein cDNA between these two rat strains. Plasmid constructs based on the LEW 3'-UTR sequence displayed increased expression of a reporter gene in transiently transfected PC12 cells, in accordance with in-vivo findings, suggesting that this nucleotide exchange might participate in the differential expression of alpha-synuclein between LEW and SHR rats. These results are consistent with a novel role for alpha-synuclein in modulating rat anxiety-like behaviors, possibly through dopaminergic mechanisms. Since the behavioral and genetic differences between these two strains are the product of independent evolutionary histories, the possibility that polymorphisms in the alpha-synuclein gene may be associated with vulnerability to anxiety-related disorders in humans requires further investigation.

Topics: Adaptation, Physiological; Alcohol Drinking; Alcoholism; alpha-Synuclein; Analysis of Variance; Animals; Anxiety; Chromatography, High Pressure Liquid; Disease Models, Animal; Dopamine; Exploratory Behavior; Hippocampus; Maze Learning; PC12 Cells; Polymorphism, Single Nucleotide; Rats; Rats, Inbred Lew; Rats, Inbred SHR; RNA, Messenger; Species Specificity; Transfection; Up-Regulation

The content of mRNA for alpha-synuclein (a key protein of the dopaminergic system) was elevated in the peripheral lymphocytes of patients with alcohol dependence syndrome. Increased level of alpha-synuclein mRNA was not associated with changes in the expression of NR4A2 gene encoding Nurrl, one of the main transcription factors of dopaminergic neurons.

Topics: Adult; Alcoholism; alpha-Synuclein; Analysis of Variance; DNA-Binding Proteins; Genetic Predisposition to Disease; Humans; Lymphocytes; Male; Middle Aged; Nuclear Receptor Subfamily 4, Group A, Member 2; Transcription Factors

Studies have found that genomic variation in the gene SNCA, which encodes the protein alpha-synuclein, may contribute to the variation in alcohol consumption in an inbred rat model of alcohol preference. Studies in humans have provided support for an association between SNCA and craving for alcohol.. To examine the role of this gene in alcohol dependence and related phenotypes, 30 single nucleotide polymorphisms (SNPs) were genotyped across the SNCA gene in a sample of 219 multiplex alcoholic families of European American descent. Two phenotypes, alcohol dependence and alcohol craving, were analyzed using the pedigree disequilibrium test.. There was no evidence of association between any of the SNCA SNPs and alcohol dependence (p>or=0.13). In contrast, 8 SNPs provided evidence of association (p<0.05) with the phenotype of alcohol craving. Haplotype analysis further supported evidence of an association with alcohol craving; a haplotype encompassing SNPs in intron 4 through the region downstream of the gene was overtransmitted to cravers and a second haplotype was overtransmitted to noncravers.. These results suggest that variation in SNCA contributes to alcohol craving, a common, although not uniform, feature of alcohol dependence.

Topics: Alcoholism; alpha-Synuclein; Chromosomes, Human, Pair 4; Databases, Genetic; Genetic Linkage; Genotype; Haplotypes; Humans; Phenotype; Polymorphism, Single Nucleotide

Alpha-synuclein is involved in dopaminergic neurotransmission and has been implicated in a number of neurodegenerative disorders, such as Parkinson's disease. Recent studies, in humans and in rat and monkey models, have suggested that alpha-synuclein may play a role in the development and maintenance of certain addictive disorders.. Fifteen single-nucleotide polymorphisms (SNPs) in the alpha-synuclein gene (SNCA) and 1 upstream microsatellite repeat (NACP-REP1) were assayed in Southwest (SW; n=514) and Plains (n=420) American Indian populations. Patterns of linkage disequilibrium (LD) at SNCA were determined for the 2 populations and compared with Caucasian, African, and Asian populations in the HapMap database (http://www.hapmap.org). Assayed alleles and constructed haplotypes in the study populations were tested for association with 4 clinical phenotypes [alcohol dependence, alcohol use disorders, drug dependence, and drug use disorders (lifetime diagnoses)] as well as with 2 symptom count phenotypes (all 18 questions and the 8 questions diagnostic for alcohol dependence).. Patterns of LD at SNCA were similar in both Indian populations and were consistent with the LD structure in other populations as reflected in the HapMap database. Single allele tests revealed significant associations between 4 SNPs and drug dependence in the SW population and between 2 of those SNPs plus 2 other SNPs and drug dependence in SW males only. In the Plains population, a significant association was detected only in males between 2 SNPs and alcohol use disorders and between 1 SNP and alcohol dependence. In the SW population, 1 SNP was marginally significant with the total symptom count. However, in all cases, the support was modest and disappeared with correction for multiple comparisons. No association was found between constructed haplotypes and any of the phenotypes in either population.. Despite modest support for association between multiple SNCA SNPs and several of the addictive disorders tested in this study, statistical significance disappeared after correction for multiple testing. Thus, our data do not support a role for a variant in the SNCA gene that contributes to alcohol or drug addiction in the 2 studied American Indian populations. Future research may focus on variants in the promoter region that could cause the changes in mRNA and protein levels observed in previous studies.

Topics: Adult; Aged; Aged, 80 and over; Alcoholism; Alleles; alpha-Synuclein; Female; Genotype; Haplotypes; Humans; Indians, North American; Linkage Disequilibrium; Male; Microsatellite Repeats; Middle Aged; Polymorphism, Single Nucleotide; Psychological Tests; Sex Characteristics; Substance-Related Disorders

The gene SNCA (or NACP), which codes for alpha-synuclein, a small synaptic protein involved in dopaminergic neurotransmission, maps to a quantitative trait locus for alcohol preference and is differentially expressed in specific brain regions in alcohol-preferring versus -nonpreferring rats. Moreover, elevated alpha-synuclein messenger RNA (mRNA) and protein levels in peripheral blood have been shown to be associated with craving in patients with alcoholism. The focus of this study was to evaluate gene expression, including the levels of alpha-synuclein mRNA, in peripheral blood in nonhuman primates that were induced to drink ethanol (4 months) and then allowed 14 months of 22-h/day access to ethanol (4% wt/vol) or water compared to alcohol-naïve controls. Differential gene expression, including alpha-synuclein mRNA levels, was measured in 18 cynomolgus macaque monkeys, 8 that had been chronically self-administering ethanol for 18 months and 10 that were alcohol naïve. Cynomolgus monkeys in this study self-administered ethanol at average rates of between 1.2 and 4.2g/kg/day. This group of ethanol-drinking monkeys had a highly significant 3.21-fold higher level of alpha-synuclein mRNA in peripheral blood than alcohol-naïve controls. These data agree with recent reports of elevated alpha-synuclein mRNA and protein in the blood of human alcoholics, support the concept of an association between alpha-synuclein and alcoholism, and demonstrate, for the first time, a biomarker present in rats, monkeys, and humans for the consumption of ethanol.

Topics: Alcoholism; alpha-Synuclein; Animals; Biomarkers; Macaca fascicularis; Male; RNA, Messenger; Self Administration

The alpha-synuclein (Snca) gene is expressed at higher levels in alcohol-naïve, inbred alcohol-preferring (iP) rats than in alcohol-non preferring (iNP) rats. Snca modulates dopamine transmission and the dopamineregic system, which play a role in mediating the rewarding properties of alcohol consumption. Thus, understanding regulation of Snca gene expression could provide insight into the relationship of Snca and alcohol consumption. To study regulation of rat Snca expression, 1,912 bp of the iP and iNP 5'-regions were cloned and sequenced. 5'-rapid amplification of cDNA ends (RACE), primer extension and RT-PCR mapped three transcription start site clusters (clusters TSS1, TSS2 and TSS3), suggesting that the Snca proximal promoter region has a complex architecture. This proximal promoter region has three TATA-less core promoters containing SP1 binding sites, initiator elements and downstream core promoter elements, which are often located in such promoters. Snca-luc constructs transiently transfected into SK-N-SH neuroblastoma cells showed that the region from - 1,912 to - 1,746 contained a strong core promoter, and that the entire approximately 2 kb region had significant promoter activity. Five polymorphisms identified between the iP and iNP in the proximal promoter region did not influence differential expression between the strains. In contrast, a single nucleotide polymorphism (SNP) at + 679 in the 3'-untranslated region (UTR) resulted in a 1.3-fold longer half-life of iP mRNA compared with iNP mRNA, which is consistent with the differential expression observed between the iP and iNP strains. These results suggest that regulation of rat Snca gene expression is complex and may contribute to alcohol preference in the iP rats.

Topics: 3' Untranslated Regions; Alcohol-Induced Disorders, Nervous System; Alcoholism; alpha-Synuclein; Animals; Base Sequence; Brain; Cell Line, Tumor; Central Nervous System Depressants; Choice Behavior; Disease Models, Animal; Dopamine; Ethanol; Gene Expression Regulation; HeLa Cells; Humans; Neural Pathways; Polymorphism, Single Nucleotide; Promoter Regions, Genetic; Rats; Regulatory Elements, Transcriptional; RNA, Messenger; Species Specificity

The aim of this study was to investigate whether the DNA methylation pattern within the alpha synuclein promoter region is altered in intoxicated and early abstinence patients with alcoholism undergoing alcohol withdrawal. We observed a significant increase of the alpha synuclein promoter DNA methylation in patients with alcoholism which was significantly associated with their elevated homocysteine levels. No significant differences of the promoter DNA methylation within a control gene (presenilin-1) in alcoholics and controls were found. The present results hint to a gene specific DNA promoter hypermethylation within the alpha synuclein gene. Since hypermethylation of DNA is an important epigenetic factor in the down regulation of gene expression and since alpha synuclein has been linked to craving these findings may explain the reduced value of craving under alcohol drinking conditions.

Topics: Adult; Aged; Alcoholism; alpha-Synuclein; Case-Control Studies; DNA Methylation; Homocysteine; Humans; Leukocytes, Mononuclear; Male; Middle Aged; Nerve Tissue Proteins; Promoter Regions, Genetic; Prospective Studies; Regression Analysis; Synucleins; Temperance

Various studies have linked alcohol dependence phenotypes to chromosome 4. One candidate gene is NACP (non-amyloid component of plaques), coding for alpha synuclein. Recently, it has been shown that alpha synuclein mRNA is increased in alcohol-dependent patients within withdrawal state. This increase is significantly associated with craving, especially obsessive craving. On the basis of these observations, the present study analysed two polymorphic repeats within the NACP gene. We found highly significant longer alleles of NACP-REP1 in alcohol-dependent patients compared with healthy controls (Kruskal-Wallis test, chi(2)=99.5; df=3, P<0.001). In addition, these lengths significantly correlate with levels of expressed alpha synuclein mRNA (chi(2)=8.83; df=2, P=0.012). The present results point to a novel approach for a genetic determination of craving, a key factor in the genesis and maintenance not only of alcoholism but also of addiction in general.

Topics: Adult; Aged; Alcoholism; Alleles; alpha-Synuclein; Case-Control Studies; Chromosomes, Human, Pair 4; Exons; Female; Gene Expression; Genetic Markers; Humans; Introns; Male; Middle Aged; Nerve Tissue Proteins; Phenotype; Polymorphism, Genetic; RNA, Messenger; Sex Factors; Synucleins; Time Factors

Alpha synuclein has been found to be increased in dopamine neurones of cocaine abusers and in rats whose alcohol preference is inbred. Furthermore, increased alpha-synuclein messenger RNA expression has been linked to craving in patients with alcoholism. The aim of the current study was to investigate whether protein levels of alpha synuclein in alcoholics are changed and possibly influence alcohol craving.. The alpha-synuclein protein expression level was measured by enzyme-linked immunosorbent assay in the serum of 49 male alcoholics and 50 nondrinking healthy controls. Alcohol craving was assessed by the Obsessive-Compulsive Drinking Scale total score, including subscales for obsessive and compulsive craving.. Alpha-synuclein protein expression in patients with alcoholism (14.33 ng/ml; SD, 13.01 ng/ml) was significantly higher (t test, T = 3.66, p < 0.0001) when compared with that of healthy controls (5.92 ng/ml; SD, 9.72 ng/ml). Using a multivariate analysis, all craving scores (Obsessive-Compulsive Drinking Scale total score and obsessive and compulsive subscale scores) in alcoholics were significantly associated with their alpha-synuclein protein levels (multiple linear regression, p < 0.014).. To our knowledge, this is the first study evaluating alpha-synuclein protein expression in alcoholics. The current study provides further evidence of altered alpha-synuclein levels in patients with alcoholism and their linkage to alcohol craving. Because alpha synuclein is involved in the modulation of dopaminergic neurotransmission, these results deliver further pathophysiological explanations of craving mechanisms.

Topics: Adult; Aged; Alcoholism; alpha-Synuclein; Case-Control Studies; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Middle Aged; Nerve Tissue Proteins; Psychiatric Status Rating Scales; Synucleins; Temperance

Alpha synuclein has been found elevated in dopamine neurons of cocaine abusers and in rats whose alcohol preference is inbred.. The alpha synuclein mRNA expression level was measured by quantitative polymerase chain reaction in the blood of 75 male alcoholics and 69 nondrinking healthy control subjects. Alcohol craving was assessed by the Obsessive-Compulsive Drinking Scale total score, including subscales for obsessive and compulsive craving.. The alpha synuclein expression in patients with alcoholism (2.79 DeltaCT; SD = 1.69; p = .021) was significantly higher when compared with healthy control subjects (2.20 DeltaCT; SD = 1.59). Increased alpha synuclein levels significantly predict Obsessive-Compulsive Drinking Scale total score (odds ratio = 1.44, 95% confidence interval: 1.01-2.06, p = .042) and especially Obsessive-Compulsive Drinking Scale obsessive subscale (odds ratio = 1.74, 95% confidence interval: 1.18-2.58, p = .005) but not Obsessive-Compulsive Drinking Scale compulsive subscale alcohol craving.. Higher levels of alpha synuclein are associated with an increase in alcohol craving. The present results provide a novel pathophysiological approach to the explanation of craving mechanisms.

Topics: Adult; Alcohol Drinking; Alcoholism; alpha-Synuclein; Case-Control Studies; Humans; Logistic Models; Male; Middle Aged; Nerve Tissue Proteins; Psychiatric Status Rating Scales; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Synucleins