Current trends in the role of neuroinflammation & α-synuclein in alcohol use disorder: A systematic quantitative literature review.

The neurodegenerative effects alcohol use disorder (AUD) have been well characterized and are likely due to the long-term effects of alcohol on the brain. The molecular events that underlie regional neuronal loss are a focus of current research. Chronic inflammation in the central nervous system, termed neuroinflammation, contributes to the progressive loss of neurons in the brain. Using data from genome-wide association studies and genetic and gene expression data, α-synuclein was identified as a gene of interest for AUD almost 10 years ago. Despite this and the well-recognized role of α-synuclein in mediating neuroinflammation in other neurodegenerative diseases, its role in alcohol-induced brain damage and AUD is yet to be elucidated. This systematic literature review quantifies and analyzes relationships between AUD, α-synuclein, and neuroinflammation. The review identified fewer studies focused on the role in AUD of α-synuclein (30) than on neuroinflammation (177), with published studies heavily centered on the myeloid differentiation primary response 88 (MyD88)-dependent toll-like receptor 4 (TLR4) pathway. The systematic review revealed that no original literature investigates the roles of α-synuclein and neuroinflammation in AUD and that there are significantly fewer published articles on the role of α-synuclein in AUD than in other neuroinflammatory conditions. Studies of the role of neuroinflammation in AUD are largely centered on the TLR4 signaling cascade, followed by TLR2 and TLR3, and soluble cytokines such as IL-10, IL-1ß, and TNF-α. Key research themes identified in other neurodegenerative disorders provide new insights for further investigation in AUD.

Influence of sex and liver cirrhosis on the expression of miR-146a-5p and its target genes, IRAK1 and TRAF6.

Long-term alcohol misuse triggers cellular adaptions in susceptible regions of the human brain, resulting in neurodegeneration, neuroinflammation and altered gene expression. Previous studies have identified ∼35 miRNAs, including miR-146a-5p, which are up-regulated in the frontal cortex of males with alcohol use disorder (AUD), but the influence of liver cirrhosis and sex is unknown. The expression of miR-146a-5p, IRAK1, and TRAF6 was measured in the prefrontal cortex of controls and individuals with AUD with and without cirrhosis of the liver. Further, individuals were genotyped for two SNPs, rs2910164 and rs57095329. The expression of miR-146a-5p was significantly different between sexes. In males the expression of miR-146a-5p was increased in individuals with AUD with and without liver cirrhosis compared with controls. In females miR-146a-5p expression was significantly lower in individuals with AUD compared with both controls and those with AUD and cirrhosis, suggesting that both the severity of alcohol misuse and the sex of the individual influences the expression of miR-146a-5p. The expression of TRAF6 was significantly lower in individuals with uncomplicated AUD compared with those with AUD and cirrhosis. The expression of IRAK1 did not differ between groups or sexes. There was no influence of genotype on expression. Increased expression of miR-146a-5p did not correlate with decreased IRAK1 or TRAF6 expression suggesting a loss of regulatory control of the TLR4 pathway. Understanding sex-specific differences in the regulation of gene expression in AUD is key to determine which inflammatory pathways could be targeted for therapeutic intervention.

Sex Differences in the Expression of the α5 Subunit of the GABAA Receptor in Alcoholics with and without Cirrhosis of the Liver.

BACKGROUND: Alcohol exposure alters the expression of a large number of genes, resulting in neuronal adaptions and neuronal loss, but the underlying mechanisms are largely unknown. miRNAs are gene repressors that are abundant in the brain. A recent study identified ~ 35 miRNAs that are up-regulated in the prefrontal cortex of human alcoholics and predicted to target genes that are down-regulated in the same region. Although interactions between alcohol-responsive miRNAs and their target genes have been predicted, few studies have validated these predictions. METHODS: We measured the expression of GABAA α5 mRNA in the prefrontal and motor cortices of human alcoholics and matched controls using real-time PCR. The expression of miR-203 was measured in a subset of these cases. The predicted interaction of miR-203 and GABRA5 was validated for miR-203 using a luciferase reporter assay. RESULTS: In both frontal and motor cortices, the expression of GABAA α5 was significantly lower in cirrhotic alcoholics compared with controls. Further, the pattern of expression between the groups was significantly different between males and females. The expression of miR-203 was higher in the prefrontal cortex of cirrhotic alcoholics compared with controls and uncomplicated alcoholics. These differences were particularly marked in female cases. Cotransfection of GABRA5 with miR-203 in HEK293T cells reduced luciferase reporter activity. CONCLUSION: There are sex differences in the expression of GABAA α5 and miR-203 in the brain of human alcoholics which are particularly marked in alcoholics with cirrhosis of the liver. Further, miR-203 may mediate the changes in expression of this GABAA receptor isoform that is brought about by alcohol exposure.

Expression of 14-3-3 transcript isoforms in response to ethanol exposure and their regulation by miRNAs.

The 14-3-3 proteins are a family of highly conserved molecular chaperones involved in the regulation of a number of key cellular functions including metabolism, stress response, protein trafficking, cell-cycle control, signal transduction, transcription, apoptosis and neurotransmission. 14-3-3 proteins have also been implicated in the pathophysiology of neurodegenerative disorders including Alzheimer disease and Parkinson disease. Recent studies have also shown that 14-3-3s are differentially expressed in the frontal cortex of human alcoholics suggesting a potential role in the pathophysiology of alcohol use disorders. Here we measured the expression of 14-3-3 transcripts in HEK293T cells in response to chronic ethanol treatment. Five of the seven transcripts (14-3-3ß, 14-3-3γ, 14-3-3ζ, 14-3-3ε and 14-3-3θ) were significantly down-regulated following chronic exposure to ethanol for a five day period with these changes persisting even after withdrawal from ethanol treatment. One transcript, 14-3-3σ, was significantly up-regulated following chronic ethanol exposure and 14-3-3η showed no differences in expression in the same treatment model. The pattern of expression changes is similar to those seen in the frontal cortex of human alcoholics. To investigate the role of miRNAs in mediating the expression changes we measured the expression of the 14-3-3 transcripts following transfection with miR-203, miR-144 and miR-7 mimics. Although these miRNAs had predicted target sites in the 3'untranslated region of each 14-3-3 isoform, only miR-203 resulted in a down-regulation of 14-3-3θ transcript. In addition, the expression of 14-3-3γ was upregulated following transfection with miR-7 and miR-144 mimics. MiRNA regulation of these isoforms following alcohol exposure may lead to alterations in neurotransmission, the balance between cell survival and cell death, as well as changing the rewarding effects of alcohol.

Differential expression of α-synuclein splice variants in the brain of alcohol misusers: Influence of genotype.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Reduced expression of α-synuclein in alcoholic brain: influence of SNCA-Rep1 genotype.

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.

The role of α-synuclein in the pathophysiology of alcoholism.

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.

Differential Effects of Chronic and Chronic-Intermittent Ethanol Treatment and Its Withdrawal on the Expression of miRNAs.

Chronic and excessive alcohol misuse results in changes in the expression of selected miRNAs and their mRNA targets in specific regions of the human brain. These expression changes likely underlie the cellular adaptations to long term alcohol misuse. In order to delineate the mechanism by which these expression changes occur, we have measured the expression of six miRNAs including miR-7, miR-153, miR-152, miR-15B, miR-203 and miR-144 in HEK293T, SH SY5Y and 1321 N1 cells following exposure to ethanol. These miRNAs are predicted to target key genes involved in the pathophysiology of alcoholism. Chronic and chronic-intermittent exposure to ethanol, and its removal, resulted in specific changes in miRNA expression in each cell line suggesting that different expression patterns can be elicited with different exposure paradigms and that the mechanism of ethanol's effects is dependent on cell type. Specifically, chronic exposure to ethanol for five days followed by a five day withdrawal period resulted in up-regulation of several miRNAs in each of these cell lines similar to expression changes identified in post mortem human brain. Thus, this model can be used to elucidate the role of miRNAs in regulating gene expression changes that occur in response to ethanol exposure.

Significant differences in gene expression of GABA receptors in peripheral blood leukocytes of migraineurs.

Migraine is a debilitating neurovascular disorder, with a substantial genetic component. The exact cause of a migraine attack is unknown; however cortical hyperexcitability is thought to play a role. As Gamma-aminobutyric Acid (GABA) is the major inhibitory neurotransmitter in the brain, malfunctioning of this system may be a cause of the hyperexcitability. To date, there has been limited research examining the gene expression or genetics of GABA receptors in relation to migraine. The aim of our study was to determine if GABA receptors play a role in migraine by investigating their gene expression using profile in migraine affected individuals and non-affected controls by Q-PCR. Gene expression of GABA(A) receptor subunit isoforms (GABRA3, GABRB3, GABRQ) and GABA(B) receptor 2 (GABBR2) was quantified in mRNA obtained from peripheral blood leukocytes from 28 migraine subjects and 22 healthy control subjects. Analysis of results showed that two of the tested genes, GABRA3 and GABBR2, were significantly down regulated in migraineurs (P=0.018; P=0.017), compared to controls. Results from the other tested genes did not show significant gene expression variation. The results indicate that there may be specific GABA receptor gene expression variation in migraine, particularly involving the GABRA3 and GABBR2 genes. This study also identifies GABRA3 and GABBR2 as potential biomarkers to select migraineurs that may be more responsive to GABA agonists with future investigations in this area warranted.

Up-regulation of microRNAs in brain of human alcoholics.

BACKGROUND: MicroRNAs (miRNAs) are small, noncoding oligonucleotides with an important role in posttranscriptional regulation of gene expression at the level of translation and mRNA degradation. Recent studies have revealed that miRNAs play important roles in a variety of biological processes, such as cell proliferation, neuronal differentiation, developmental timing, synapse function, and neurogenesis. A single miRNA can target hundreds of mRNA transcripts for either translation repression or degradation, but the function of many human miRNAs is not known. METHODS: miRNA array analysis was performed on the prefrontal cortex of 27 individual human cases (14 alcoholics and 13 matched controls). Target genes for differentially expressed miRNAs were predicted using multiple target prediction algorithms and a consensus approach, and predicted targets were matched against differentially expressed mRNAs from the same samples. Over- and under-representation analysis was performed using hypergeometric probability and z-score tests. RESULTS: Approximately 35 miRNAs were significantly up-regulated in the alcoholic group compared with controls. Target prediction showed a large degree of overlap with our published cDNA microarray data. Functional classification of the predicted target genes of the regulated miRNAs includes apoptosis, cell cycle, cell adhesion, nervous system development, and cell-cell signaling. CONCLUSIONS: These data suggest that the reduced expression of genes in human alcoholic cases may be because of the up-regulated miRNAs. Cellular processes fundamental to neuronal plasticity appear to represent major targets of the suggested miRNA regulation.

Differential expression of 14-3-3 isoforms in human alcoholic brain.

BACKGROUND: Neuropathological damage as a result of chronic alcohol abuse often results in the impairment of cognitive function. The damage is particularly marked in the frontal cortex. The 14-3-3 protein family consists of 7 proteins, ß, γ, ε, ζ, η, θ, and σ, encoded by 7 distinct genes. They are highly conserved molecular chaperones with roles in the regulation of metabolism, signal transduction, cell-cycle control, protein trafficking, and apoptosis. They may also play an important role in neurodegeneration in chronic alcoholism. METHODS: We used real-time PCR to measure the expression of 14-3-3 mRNA transcripts in both the dorsolateral prefrontal cortex and motor cortex of human brains obtained at autopsy. RESULTS: We found significantly lower 14-3-3ß, γ, and θ expression in both cortical areas of alcoholics, but no difference in 14-3-3η expression, and higher expression of 14-3-3σ in both areas. Levels of 14-3-3ζ and ε transcripts were significantly lower only in alcoholic motor cortex. CONCLUSIONS: Altered 14-3-3 expression could contribute to synaptic dysfunction and altered neurotransmission in chronic alcohol misuse by human subjects.

Association of polymorphisms in RGS4 and expression of RGS transcripts in the brains of human alcoholics.

Chronic alcoholism leads to neurotoxic effects in the central nervous system. Neuroadaptive changes in the brain may lead to tolerance to, and dependence on, alcohol as a result of alterations in synaptic complexity. G-proteins are negatively regulated by RGS proteins, which are integral to many neural pathways that include neurotransmission, hormonal responses, and chemotactic signals. These considerations, together with findings from microarray analyses of human autopsy brain, suggest that proteins involved in G-protein signalling, specifically the RGS protein family, may play an important role in the functioning of neural systems that are affected by chronic alcohol abuse. We used Real Time PCR to measure the expression of two members of the RGS family, RGS4 and RGS7, in the superior frontal gyrus and primary motor cortex from alcoholic and non-alcoholic cases. Overall, cirrhotic alcoholics had lower expression levels of RGS4 mRNA than controls and non-cirrhotic alcoholics. We also report that the four RGS4 SNPs (SNP1, 4, 7 and 18) may be associated with alcoholism in European Caucasians at the haplotype level. The haplotype T-C-G (SNP1-4-18) may exert a protective effect against alcoholism.

Synaptic proteome changes in the superior frontal gyrus and occipital cortex of the alcoholic brain.

Cognitive deficits and behavioral changes that result from chronic alcohol abuse are a consequence of neuropathological changes which alter signal transmission through the neural network. To focus on the changes that occur at the point of connection between the neural network cells, synaptosomal preparations from post-mortem human brain of six chronic alcoholics and six non-alcoholic controls were compared using 2D-DIGE. Functionally affected and spared regions (superior frontal gyrus, SFG, and occipital cortex, OC, respectively) were analyzed from both groups to further investigate the specific pathological response that alcoholism has on the brain. Forty-nine proteins were differentially regulated between the SFG of alcoholics and the SFG of controls and 94 proteins were regulated in the OC with an overlap of 23 proteins. Additionally, the SFG was compared to the OC within each group (alcoholics or controls) to identify region specific differences. A selection were identified by MALDI-TOF mass spectrometry revealing proteins involved in vesicle transport, metabolism, folding and trafficking, and signal transduction, all of which have the potential to influence synaptic activity. A number of proteins identified in this study have been previously related to alcoholism; however, the focus on synaptic proteins has also uncovered novel alcoholism-affected proteins. Further exploration of these proteins will illuminate the mechanisms altering synaptic plasticity, and thus neuronal signaling and response, in the alcoholic brain.

Altered gene expression profiles in the frontal cortex of cirrhotic alcoholics.

BACKGROUND: Cirrhosis is the result of chronic liver disease that causes scarring and dysfunction of the liver. The disease is a common concomitant condition resulting from sustained exposure to alcohol. Heavy alcohol use results in brain damage that is generally more severe in cirrhotic compared with noncirrhotic alcoholics. We examined, at the cellular level, gene expression in the frontal cortex of cirrhotic alcoholics. METHODS: Gene expression profiles were compared between cirrhotic and noncirrhotic alcoholics using approximately 47,000 element cDNA microarrays. RESULTS: Widespread differences in transcriptome patterns were observed in cirrhotic compared with noncirrhotic alcoholics and these differences in gene expression accurately distinguished cirrhotic from noncirrhotic alcoholics. Functionally related groups of genes were identified that are involved in cell adhesion, mitochondrial function, synaptic transmission, apoptosis, and cell proliferation. Both astrocytes and neuronal cells were affected at the transcriptional level. The regulated genes are involved in neurite growth, neuronal cell adhesion, synaptic vesicle release, and postsynaptic neurotransmission. CONCLUSIONS: These changes in the transcriptome likely contribute to the more severe brain dysfunction in cirrhotic alcoholics.

Patterns of gene expression in the frontal cortex discriminate alcoholic from nonalcoholic individuals.

Alcohol dependence is characterized by tolerance, physical dependence, and craving. The neuroadaptations underlying these effects of chronic alcohol abuse are likely due to altered gene expression. Previous gene expression studies using human post-mortem brain demonstrated that several gene families were altered by alcohol abuse. However, most of these changes in gene expression were small. It is not clear if gene expression profiles have sufficient power to discriminate control from alcoholic individuals and how consistent gene expression changes are when a relatively large sample size is examined. In the present study, microarray analysis (approximately 47,000 elements) was performed on the superior frontal cortex of 27 individual human cases (14 well characterized alcoholics and 13 matched controls). A partial least squares statistical procedure was applied to identify genes with altered expression levels in alcoholics. We found that genes involved in myelination, ubiquitination, apoptosis, cell adhesion, neurogenesis, and neural disease showed altered expression levels. Importantly, genes involved in neurodegenerative diseases such as Alzheimer's disease were significantly altered suggesting a link between alcoholism and other neurodegenerative conditions. A total of 27 genes identified in this study were previously shown to be changed by alcohol abuse in previous studies of human post-mortem brain. These results revealed a consistent re-programming of gene expression in alcohol abusers that reliably discriminates alcoholic from non-alcoholic individuals.

Expression of MBP, PLP, MAG, CNP, and GFAP in the Human Alcoholic Brain.

BACKGROUND: Chronic and excessive alcohol misuse results in neuropathological damage in the cerebral cortex. The damage includes white matter loss, brain atrophy, and selective loss of neurons in the superior frontal gyrus. Chronic alcohol misuse also results in alterations in the expression of a number of genes, including a selective reprogramming of myelin gene expression in the frontal cortex. METHODS: The expression of cyclic nucleotide phosphodiesterase, glial fibrillary acidic protein, myelin-associated glycoprotein, myelin basic protein, and myelin proteolipid protein were assessed in the superior frontal gyrus and the primary motor cortex of control, uncomplicated alcoholic, and cirrhotic alcoholic cases. RESULTS: Overall, the expression of cyclic nucleotide phosphodiesterase, glial fibrillary acidic protein, myelin-associated glycoprotein, and myelin basic protein were significantly lower in the cirrhotic alcoholic cases compared with controls, with a similar tendency for myelin proteolipid protein. There was a strong correlation between the expression of the proteins studied and the brain weight of the individual case, but this interaction did not confound the overall analysis. There was no significant difference between controls and uncomplicated alcoholics. CONCLUSIONS: The loss of myelin proteins occurred without gross changes in brain pathology or brain weight and was not restricted to pathologically susceptible brain regions. It is not possible to determine whether the loss of myelin proteins in cirrhotic alcoholics is the result of cirrhosis per se or the combination of alcohol misuse and liver cirrhosis. Future studies comparing cases with alcoholic and nonalcoholic cirrhosis of the liver disease are required to elucidate this further.

Expression Profiling in Alcoholism Research.

This article represents the proceedings of a symposium at the 2004 International Society for Biomedical Research on Alcoholism in Mannheim, Germany, organized and co-chaired by Susan E. Bergeson and Wolfgang Sommer. The presentations and presenter were (1) Gene Expression in Brains of Alcohol-Preferring and Non-Preferring Rats, by Howard J. Edenberg (2) Candidate Treatment Targets for Alcoholism: Leads from Functional Genomics Approaches, by Wolfgang Sommer (3) Microarray Analysis of Acute and Chronic Alcohol Response in Brain, by Susan E. Bergeson (4) On the Integration of QTL and Gene Expression Analysis, by Robert J. Hitzemann (5) Microarray and Proteomic Analysis of the Human Alcoholic Brain, by Peter R. Dodd.

The application of proteomics to the human alcoholic brain.

Alcoholism results in changes in the human brain that reinforce the cycle of craving and dependency, and these changes are manifest in the pattern of expression of proteins in key cells and brain areas. Described here is a proteomics-based approach aimed at determining the identity of proteins in the superior frontal cortex (SFC) of the human brain that show different levels of expression in autopsy samples taken from healthy and long-term alcohol abuse subjects. Soluble protein fractions constituting pooled samples combined from SFC biopsies of four well-characterized chronic alcoholics (mean consumption > 80 g ethanol/day throughout adulthood) and four matched controls (<20 g/day) were generated. Two-dimensional electrophoresis was performed in triplicate on alcoholic and control samples and the resultant protein profiles analyzed for differential expression. Overall, 182 proteins differed by the criterion of twofold or more between case and control samples. Of these, 139 showed significantly lower expression in alcoholics, 35 showed significantly higher expression, and 8 were new or had disappeared. To date, 63 proteins have been identified using MALDI-MS and MS-MS. The finding that the expression level of differentially expressed proteins is preponderantly lower in the alcoholic brain is supported by recent results from parallel studies using microarray mRNA transcript.

Gene expression profiling of individual cases reveals consistent transcriptional changes in alcoholic human brain.

Chronic alcohol exposure induces lasting behavioral changes, tolerance, and dependence. This results, at least partially, from neural adaptations at a cellular level. Previous genome-wide gene expression studies using pooled human brain samples showed that alcohol abuse causes widespread changes in the pattern of gene expression in the frontal and motor cortices of human brain. Because these studies used pooled samples, they could not determine variability between different individuals. In the present study, we profiled gene expression levels of 14 postmortem human brains (seven controls and seven alcoholic cases) using cDNA microarrays (46,448 clones per array). Both frontal cortex and motor cortex brain regions were studied. The list of genes differentially expressed confirms and extends previous studies of alcohol responsive genes. Genes identified as differentially expressed in two brain regions fell generally into similar functional groups, including metabolism, immune response, cell survival, cell communication, signal transduction and energy production. Importantly, hierarchical clustering of differentially expressed genes accurately distinguished between control and alcoholic cases, particularly in the frontal cortex.

Methods for the identification of differentially expressed genes in human post-mortem brain.

Microarrays can be used to monitor the expression of thousands of genes simultaneously. This technique requires high-quality RNA which can be extracted from a variety of tissues and cells including post-mortem human brain. Given the vast amount of information obtained from microarray studies, it is critical to establish valid analysis techniques to identify differentially expressed genes. This technical report describes the basic methodology and analyses used to identify such genes in human post-mortem brain tissue.