The NSW brain tissue resource centre: Banking for alcohol and major neuropsychiatric disorders research

Phosphatidylethanol in post-mortem brain: Correlation with blood alcohol concentration and alcohol use disorder

Phosphatidylethanol (PEth) is an alcohol derivative that has been employed as a blood-based biomarker for regular alcohol use. This study investigates the utility of phosphatidylethanol (PEth) as a biomarker for assessing alcohol consumption in post-mortem brain tissue. Using samples from the New South Wales Brain Tissue Resource Centre, we analysed PEth(16:0/18:1) levels in the cerebellum and meninges of individuals with varying histories of alcohol use, including those diagnosed with alcohol use disorder (AUD) and controls. Our findings demonstrate a significant correlation between PEth levels and blood alcohol content (BAC) at the time of death, supporting the biomarker's sensitivity to recent alcohol intake. Furthermore, this study explores the potential of PEth levels in differentiating AUD cases from controls, taking into consideration the complexities of diagnosing AUD post-mortem. The study also examined the relationship between PEth levels and liver pathology, identifying a link with the severity of liver damage. These results underscore the value of PEth as a reliable indicator of alcohol consumption and its potential contributions to post-mortem diagnostics and consequently, research into alcohol-related brain damage.

Double Chromogen-based Immunohistochemical Staining: An Efficient Approach for Utilizing Long-term Formalin-fixed Tissue in Biobanks

The New South Wales Brain Tissue Resource Centre is a human brain bank that provides top-quality brain tissue for cutting-edge neuroscience research spanning various conditions from alcohol use disorder to neurodegenerative diseases. However, the conventional practice of preserving brain tissue in formalin poses challenges for immunofluorescent staining primarily due to the formalin's tendency, over time, to create cross-links between antigens, which can obscure epitopes of interest. In addition, researchers can encounter issues such as spectral bleeding, limitations in using multiple colors, autofluorescence, and cross-reactivity when working with long-term formalin-fixed brain tissue. The purpose of the study was to test chromogen-based double immunolabeling to negate the issues with immunofluorescent staining. Colocalization of antigens was explored using chromogens 3-amino-9-ethylcarbazole (AEC) and 3,3,-diaminobenzidine in a sequential staining procedure where the AEC signal was eliminated by alcohol treatment. Combinations of 2 or 3 primary antibodies from the same or different species were trialed successfully with this protocol. The colocalization of antigens was also demonstrated with pseudocoloring that mimicked immunofluorescence staining. This staining technique increases the utility of archival formalin-fixed tissue samples.

A Survey of Community Perceptions on Brain Donation for Research

Postmortem brain donation for medical research is a little-known form of organ donation. While most brain research is carried out using animal models, many neurological diseases are uniquely human. Greater availability of human postmortem brain tissue from diseased individuals and controls would therefore improve the development of treatments for neurological and neuropsychiatric diseases. Globally, organ donation for medical research is dwarfed by organ donation for transplantation. In 2021, 36% of Australians were registered organ donors for transplantation, with public "in-principle" support even higher, at 76%. In contrast, there are little data on Australian or international brain donation rates for research. A 30-item online survey was conducted to ascertain knowledge of, and attitudes toward, brain donation in Australia. Of the respondents, 12/237 (5%) were current brain donors and excluded from further analysis. Of the remaining 225, 75% were registered organ donors for transplant. The vast majority (n = 189/225, 84%) of respondents supported or strongly supported the principle of brain donation. However, of those registered for transplantation or whole-body donors, 93/170 (55%) were not aware that brain donation was possible, while 50%, alternatively or also, thought that registering as an organ donor for transplantation rendered them a brain donor by default. Only 9/225 (4%) respondents indicated that they would definitely not donate their brain in the future, while 27 remained unsure. There is prominent public support for brain donation in Australia, with 84% of respondents willing to donate their brain. Yet, the extent of public misconceptions on brain donation for research suggests the need for further education on all types of organ donation, so individuals may make informed decisions.

Brain proteomic atlas of alcohol use disorder in adult males

Alcohol use disorder (AUD) affects transcriptomic, epigenetic and proteomic expression in several organs, including the brain. There has not been a comprehensive analysis of altered protein abundance focusing on the multiple brain regions that undergo neuroadaptations occurring in AUD. We performed a quantitative proteomic analysis using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of human postmortem tissue from brain regions that play key roles in the development and maintenance of AUD, the amygdala (AMG), hippocampus (HIPP), hypothalamus (HYP), nucleus accumbens (NAc), prefrontal cortex (PFC) and ventral tegmental area (VTA). Brain tissues were from adult males with AUD (n = 11) and matched controls (n = 16). Across the two groups, there were >6000 proteins quantified with differential protein abundance in AUD compared to controls in each of the six brain regions. The region with the greatest number of differentially expressed proteins was the AMG, followed by the HYP. Pathways associated with differentially expressed proteins between groups (fold change > 1.5 and LIMMA p < 0.01) were analyzed by Ingenuity Pathway Analysis (IPA). In the AMG, adrenergic, opioid, oxytocin, GABA receptor and cytokine pathways were among the most enriched. In the HYP, dopaminergic signaling pathways were the most enriched. Proteins with differential abundance in AUD highlight potential therapeutic targets such as oxytocin, CSNK1D (PF-670462), GABAB receptor and opioid receptors and may lead to the identification of other potential targets. These results improve our understanding of the molecular alterations of AUD across brain regions that are associated with the development and maintenance of AUD. Proteomic data from this study is publicly available at www.lmdomics.org/AUDBrainProteomeAtlas/ .

The ethical and legal landscape of brain data governance

Neuroscience research is producing big brain data which informs both advancements in neuroscience research and drives the development of advanced datasets to provide advanced medical solutions. These brain data are produced under different jurisdictions in different formats and are governed under different regulations. The governance of data has become essential and critical resulting in the development of various governance structures to ensure that the quality, availability, findability, accessibility, usability, and utility of data is maintained. Furthermore, data governance is influenced by various ethical and legal principles. However, it is still not clear what ethical and legal principles should be used as a standard or baseline when managing brain data due to varying practices and evolving concepts. Therefore, this study asks what ethical and legal principles shape the current brain data governance landscape? A systematic scoping review and thematic analysis of articles focused on biomedical, neuro and brain data governance was carried out to identify the ethical and legal principles which shape the current brain data governance landscape. The results revealed that there is currently a large variation of how the principles are presented and discussions around the terms are very multidimensional. Some of the principles are still at their infancy and are barely visible. A range of principles emerged during the thematic analysis providing a potential list of principles which can provide a more comprehensive framework for brain data governance and a conceptual expansion of neuroethics.

Increased immune cell and altered microglia and neurogenesis transcripts in an Australian schizophrenia subgroup with elevated inflammation

We previously identified a subgroup of schizophrenia cases (~40 %) with heightened inflammation in the neurogenic subependymal zone (SEZ) (North et al., 2021b). This schizophrenia subgroup had changes indicating reduced microglial activity, increased peripheral immune cells, increased stem cell dormancy/quiescence and reduced neuronal precursor cells. The present follow-up study aimed to replicate and extend those novel findings in an independent post-mortem cohort of schizophrenia cases and controls from Australia. RNA was extracted from SEZ tissue from 20 controls and 22 schizophrenia cases from the New South Wales Brain Tissue Resource Centre, and gene expression analysis was performed. Cluster analysis of inflammation markers (IL1B, IL1R1, SERPINA3 and CXCL8) revealed a high-inflammation schizophrenia subgroup comprising 52 % of cases, which was a significantly greater proportion than the 17 % of high-inflammation controls. Consistent with our previous report (North et al., 2021b), those with high-inflammation and schizophrenia had unchanged mRNA expression of markers for steady-state and activated microglia (IBA1, HEXB, CD68), decreased expression of phagocytic microglia markers (P2RY12, P2RY13), but increased expression of markers for macrophages (CD163), monocytes (CD14), natural killer cells (FCGR3A), and the adhesion molecule ICAM1. Similarly, the high-inflammation schizophrenia subgroup emulated increased quiescent stem cell marker (GFAPD) and decreased neuronal progenitor (DLX6-AS1) and immature neuron marker (DCX) mRNA expression; but also revealed a novel increase in a marker of immature astrocytes (VIM). Replicating primary results in an independent cohort demonstrates that inflammatory subgroups in the SEZ in schizophrenia are reliable, robust and enhance understanding of neuropathological heterogeneity when studying schizophrenia.

The Amygdala Noradrenergic System Is Compromised With Alcohol Use Disorder

BACKGROUND

Alcohol use disorder (AUD) is a leading preventable cause of death. The central amygdala (CeA) is a hub for stress and AUD, while dysfunction of the noradrenaline stress system is implicated in AUD relapse.

METHODS

Here, we investigated whether alcohol (ethanol) dependence and protracted withdrawal alter noradrenergic regulation of the amygdala in rodents and humans. Male adult rats were housed under control conditions, subjected to chronic intermittent ethanol vapor exposure to induce dependence, or withdrawn from chronic intermittent ethanol vapor exposure for 2 weeks, and ex vivo electrophysiology, biochemistry (catecholamine quantification by high-performance liquid chromatography), in situ hybridization, and behavioral brain-site specific pharmacology studies were performed. We also used real-time quantitative polymerase chain reaction to assess gene expression of α1B, β1, and β2 adrenergic receptors in human postmortem brain tissue from men diagnosed with AUD and matched control subjects.

RESULTS

We found that α1 receptors potentiate CeA GABAergic (gamma-aminobutyric acidergic) transmission and drive moderate alcohol intake in control rats. In dependent rats, β receptors disinhibit a subpopulation of CeA neurons, contributing to their excessive drinking. Withdrawal produces CeA functional recovery with no change in local noradrenaline tissue concentrations, although there are some long-lasting differences in the cellular patterns of adrenergic receptor messenger RNA expression. In addition, postmortem brain analyses reveal increased α1B receptor messenger RNA in the amygdala of humans with AUD.

CONCLUSIONS

CeA adrenergic receptors are key neural substrates of AUD. Identification of these novel mechanisms that drive alcohol drinking, particularly during the alcohol-dependent state, supports ongoing new medication development for AUD.

A qualitative study exploring the process of postmortem brain tissue donation after suicide

Access to postmortem brain tissue can be valuable in refining knowledge on the pathophysiology and genetics of neuropsychiatric disorders. Obtaining postmortem consent for the donation after death by suicide can be difficult, as families may be overwhelmed by a violent and unexpected death. Examining the process of brain donation can inform on how the request can best be conducted. This is a qualitative study with in-depth interviews with forty-one people that were asked to consider brain donation—32 who had consented to donation and 9 who refused it. Data collection and analyses were carried out according to grounded theory. Five key themes emerged from data analysis: the context of the families, the invitation to talk to the research team, the experience with the request protocol, the participants’ assessment of the experience, and their participation in the study as an opportunity to heal. The participants indicated that a brain donation request that is respectful and tactful can be made without adding to the family distress brought on by suicide and pondering brain donation was seen as an opportunity to transform the meaning of the death and invest it with a modicum of solace for being able to contribute to research.

A closer look at alcohol-induced changes in the ghrelin system: novel insights from preclinical and clinical data

Ghrelin is a gastric-derived peptide hormone with demonstrated impact on alcohol intake and craving, but the reverse side of this bidirectional link, that is, the effects of alcohol on the ghrelin system, remains to be fully established. To further characterize this relationship, we examined (1) ghrelin levels via secondary analysis of human laboratory alcohol administration experiments with heavy-drinking participants; (2) expression of ghrelin, ghrelin receptor, and ghrelin-O-acyltransferase (GOAT) genes (GHRL, GHSR, and MBOAT4, respectively) in post-mortem brain tissue from individuals with alcohol use disorder (AUD) versus controls; (3) ghrelin levels in Ghsr knockout and wild-type rats following intraperitoneal (i.p.) alcohol administration; (4) effect of alcohol on ghrelin secretion from gastric mucosa cells ex vivo and GOAT enzymatic activity in vitro; and (5) ghrelin levels in rats following i.p. alcohol administration versus a calorically equivalent non-alcoholic sucrose solution. Acyl- and total-ghrelin levels decreased following acute alcohol administration in humans, but AUD was not associated with changes in central expression of ghrelin system genes in post-mortem tissue. In rats, alcohol decreased acyl-ghrelin, but not des-acyl-ghrelin, in both Ghsr knockout and wild-type rats. No dose-dependent effects of alcohol were observed on acyl-ghrelin secretion from gastric mucosa cells or on GOAT acylation activity. Lastly, alcohol and sucrose produced distinct effects on ghrelin in rats despite equivalent caloric value. Our findings suggest that alcohol acutely decreases peripheral ghrelin concentrations in vivo, but not in proportion to alcohol's caloric value or through direct interaction with ghrelin-secreting gastric mucosal cells, the ghrelin receptor, or the GOAT enzyme.

Lipidome changes in alcohol-related brain damage

Alcohol-related brain injury is characterized by cognitive deficits and brain atrophy with the prefrontal cortex particularly susceptible. White matter in the human brain is lipid rich and a major target of damage from chronic alcohol abuse; yet, there is sparse information on how these lipids are affected. Here, we used untargeted lipidomics as a discovery tool to describe these changes in the prefrontal, middle temporal, and visual cortices of human subjects with alcohol use disorder and controls. Significant changes to the lipidome, predominantly in the prefrontal and visual cortices, and differences between the white and grey matter of each brain region were identified. These effects include broad decreases to phospholipids and ceramide, decreased polyunsaturated fatty acids, decreased sphingadiene backbones, and selective decreases in cholesteryl ester fatty acid chains. Our findings show that chronic alcohol abuse results in selective changes to the neurolipidome, which likely reflects both the directs effects on the brain and concurrent effects on the liver.

Ground state depletion microscopy as a tool for studying microglia-synapse interactions

Ground state depletion followed by individual molecule return microscopy (GSDIM) has been used in the past to study the nanoscale distribution of protein co-localization in living cells. We now demonstrate the successful application of GSDIM to archival human brain tissue sections including from Alzheimer's disease cases as well as experimental tissue samples from mouse and zebrafish larvae. Presynaptic terminals and microglia and their cell processes were visualized at a resolution beyond diffraction-limited light microscopy, allowing clearer insights into their interactions in situ. The procedure described here offers time and cost savings compared to electron microscopy and opens the spectrum of molecular imaging using antibodies and super-resolution microscopy to the analysis of routine formalin-fixed paraffin sections of archival human brain. The investigation of microglia-synapse interactions in dementia will be of special interest in this context.

Increased transcription of TSPO, HDAC2, and HDAC6 in the amygdala of males with alcohol use disorder

INTRODUCTION

Repeated exposure to high doses of alcohol triggers neuroinflammatory processes that contribute to craving and mood dysfunction in alcohol use disorder (AUD). The upregulation of the translocator protein (TSPO) is considered a biomarker of neuroinflammation, and TSPO ligands have been used as neuroimaging biomarkers of neuroinflammation. Epigenetic mechanisms are also implicated in neuroinflammatory responses to alcohol, and elevated expression of HDAC2 and HDAC6 has been reported in the brain of animals exposed to chronic alcohol.

METHODS

The present study examined the transcriptional regulation of TSPO, HDAC2, and HDAC6 in human postmortem brain tissue from males previously diagnosed with AUD (n = 11) compared to age-matched nondependent males (n = 13) in four brain regions relevant to AUD: prefrontal cortex (PFC), nucleus accumbens (NAc), hippocampus (HPP), and amygdala (AMY).

RESULTS

Translocator protein mRNA levels in AMY and PFC and HDAC2 and HDAC6 mRNA levels in AMY were upregulated in AUD compared to controls. In AMY, TSPO mRNA levels were positively associated with HDAC2 and HDAC6 mRNA levels, suggesting a possible regulation of TSPO by HDAC2 and HDAC6 in this brain region. In contrast, there were no group differences for TSPO, HDAC2, and HDAC6 in NAc and HPP.

CONCLUSION

Our study is the first to find upregulated TSPO mRNA levels in AMY and PFC in postmortem brains from AUD consistent with neuroinflammation, and in the amygdala, they implicate epigenetic regulation of TSPO by HDAC2 and HDAC6.

Identifying functionally relevant candidate genes for inflexible ethanol intake in mice and humans using a guilt-by-association approach

Gene prioritization approaches are useful tools to explore and select candidate genes in transcriptome studies. Knowing the importance of processes such as neuronal activity, intracellular signal transduction, and synapse plasticity to the development and maintenance of compulsive ethanol drinking, the aim of the present study was to explore and identify functional candidate genes associated with these processes in an animal model of inflexible pattern of ethanol intake. To do this, we applied a guilt-by-association approach, using the GUILDify and ToppGene software, in our previously published microarray data from the prefrontal cortex (PFC) and striatum of inflexible drinker mice. We then tested some of the prioritized genes that showed a tissue-specific pattern in postmortem brain tissue (PFC and nucleus accumbens (NAc)) from humans with alcohol use disorder (AUD). In the mouse brain, we prioritized 44 genes in PFC and 26 in striatum, which showed opposite regulation patterns in PFC and striatum. The most prioritized of them (i.e., Plcb1 and Prkcb in PFC, and Dnm2 and Lrrk2 in striatum) were associated with synaptic neuroplasticity, a neuroadaptation associated with excessive ethanol drinking. The identification of transcription factors among the prioritized genes suggests a crucial role for Irf4 in the pattern of regulation observed between PFC and striatum. Lastly, the differential transcription of IRF4 and LRRK2 in PFC and nucleus accumbens in postmortem brains from AUD compared to control highlights their involvement in compulsive ethanol drinking in humans and mice.

Clustering of activated microglia occurs before the formation of dystrophic neurites in the evolution of Aβ plaques in Alzheimer's disease

Alzheimer's disease (AD) is a late-onset disease that has proved difficult to model. Microglia are implicated in AD, but reports vary on precisely when and how in the sequence of pathological changes they become involved. Here, post-mortem human tissue from two differentially affected regions of the AD brain and from non-demented individuals with a high load of AD-type pathology (high pathology controls) was used to model the disease time course in order to determine how microglial activation relates temporally to the deposition of hallmark amyloid-β (Aβ) and hyperphosphorylated microtubule associated protein tau pathology. Immunofluorescence against the pan-microglial marker, ionised calcium-binding adapter molecule 1 (IBA1), Aβ and tau, was performed in the primary motor cortex (PMC), a region relatively spared of AD pathological changes, and compared to the severely affected inferior temporal cortex (ITC) in the same cases. Unlike the ITC, the PMC in the AD cases was spared of any degenerative changes in cortical thickness and the density of Betz cells and total neurons. The clustering of activated microglia was greatest in the PMC of AD cases and high pathology controls compared to the ITC. This suggests microglial activation is most prominent in the early phases of AD pathophysiology. Nascent tau inclusions were found in neuritic plaques in the PMC but were more numerous in the ITC of the same case. This shows that tau positive neuritic plaques begin early in AD which is likely of pathogenic importance, however major tau deposition follows the accumulation of Aβ and clustering of activated microglia. Importantly, findings presented here demonstrate that different states of microglial activation, corresponding to regional accumulations of Aβ and tau, are present simultaneously in the same individual; an important factor for consideration if targeting these cells for therapeutic intervention.

Beyond genome-wide significance: integrative approaches to the interpretation and extension of GWAS findings for alcohol use disorder

Alcohol use disorder (AUD) is a heritable complex behavior. Due to the highly polygenic nature of AUD, identifying genetic variants that comprise this heritable variation has proved to be challenging. With the exception of functional variants in alcohol metabolizing genes (e.g. ADH1B and ALDH2), few other candidate loci have been confidently linked to AUD. Genome-wide association studies (GWAS) of AUD and other alcohol-related phenotypes have either produced few hits with genome-wide significance or have failed to replicate on further study. These issues reinforce the complex nature of the genetic underpinnings for AUD and suggest that both GWAS studies with larger samples and additional analysis approaches that better harness the nominally significant loci in existing GWAS are needed. Here, we review approaches of interest in the post-GWAS era, including in silico functional analyses; functional partitioning of single nucleotide polymorphism heritability; aggregation of signal into genes and gene networks; and validation of identified loci, genes and gene networks in postmortem brain tissue and across species. These integrative approaches hold promise to illuminate our understanding of the biological basis of AUD; however, we recognize that the main challenge continues to be the extremely polygenic nature of AUD, which necessitates large samples to identify multiple loci associated with AUD liability.

Normal Aging Brain Collection Amsterdam (NABCA): A comprehensive collection of postmortem high-field imaging, neuropathological and morphometric datasets of non-neurological controls

Well-characterized, high-quality brain tissue of non-neurological control subjects is a prerequisite to study the healthy aging brain, and can serve as a control for the study of neurological disorders. The Normal Aging Brain Collection Amsterdam (NABCA) provides a comprehensive collection of post-mortem (ultra-)high-field MRI (3Tesla and 7 Tesla) and neuropathological datasets of non-neurological controls. By providing MRI within the pipeline, NABCA uniquely stimulates translational neurosciences; from molecular and morphometric tissue studies to the clinical setting. We describe our pipeline, including a description of our on-call autopsy team, donor selection, in situ and ex vivo post-mortem MRI protocols, brain dissection and neuropathological diagnosis. A demographic, radiological and pathological overview of five selected cases on all these aspects is provided. Additionally, information is given on data management, data and tissue application procedures, including review by a scientific advisory board, and setting up a material transfer agreement before distribution of tissue. Finally, we focus on future prospects, which includes laying the foundation for a unique platform for neuroanatomical, histopathological and neuro-radiological education, of professionals, students and the general (lay) audience.

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NABCA provides a collection of correlative post-mortem MRI and pathological datasets.

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Non-neurological control brains for studies on aging and neurological disorders.

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Stimulating micro- to macroscale structural exploration within same patient

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Post-mortem MRI data and tissue available for integrated advanced data analytics

Considerations for optimal use of postmortem human brains for molecular psychiatry: lessons from schizophrenia

Schizophrenia is a disabling disease impacting millions of people around the world, for which there is no known cure. Current antipsychotic treatments for schizophrenia mainly target psychotic symptoms, do little to ameliorate social or cognitive deficits, have side-effects that cause weight gain, and diabetes and 30% of people do not respond. Thus, better therapeutics for schizophrenia aimed at the route biologic changes are needed and discovering the underlying neurobiology is key to this quest. Postmortem brain studies provide the most direct and detailed way to determine the pathophysiology of schizophrenia. This chapter outlines steps that can be taken to ensure the best-quality molecular data from postmortem brain tissue are obtained. In this chapter, we also discuss targeted and high-throughput methods for examining gene and protein expression and some of the strengths and limitations of each method. We briefly consider why gene and protein expression changes may not always concur within brain tissue. We conclude that postmortem brain research that investigates gene and protein expression in well-characterized and matched brain cohorts provides an important foundation to be considered when interpreting data obtained from studies of living schizophrenia patients.

Effect of alcohol use disorder on oxytocin peptide and receptor mRNA expression in human brain: A post-mortem case-control study

Animal and human evidence supports a role for oxytocin in alcohol-seeking behaviors. There is interest, therefore, in targeting the oxytocin pathway as a new pharmacologic approach to treat alcohol use disorder. To this end, it is important to understand the effect of alcohol use disorder on endogenous oxytocin in brain regions that are relevant for the initiation and maintenance of alcohol use disorder. We examined human post-mortem brain tissue from males with alcohol use disorder (n=11) compared to nonalcohol dependent male controls (n=16). We a priori targeted five brain regions that in rodent studies, are projection areas for oxytocin neurons: nucleus accumbens, amygdala, hippocampus, ventral tegmental area and prefrontal cortex. Fold change in mRNA levels of oxytocin peptide and receptor were measured in each of the brain regions studied. Fold change for oxytocin peptide mRNA was significantly elevated in the prefrontal cortex of subjects with alcohol use disorder compared to controls (uncorrected p=0.0001; FDR-corrected p=0.001). For the entire sample of 27 subjects, there was a significant positive correlation between the fold change in oxytocin peptide mRNA in the prefrontal cortex and both daily alcohol intake (r²=0.38; p=0.002) and drinks per week (r²=0.24; p=0.02). Results are discussed in light of the previous animal and human literature on changes in the endogenous oxytocin system as an effect of chronic alcohol exposure.

Gene expression profiling in the human alcoholic brain

Long-term alcohol use causes widespread changes in gene expression in the human brain. Aberrant gene expression changes likely contribute to the progression from occasional alcohol use to alcohol use disorder (including alcohol dependence). Transcriptome studies have identified individual gene candidates that are linked to alcohol-dependence phenotypes. The use of bioinformatics techniques to examine expression datasets has provided novel systems-level approaches to transcriptome profiling in human postmortem brain. These analytical advances, along with recent developments in next-generation sequencing technology, have been instrumental in detecting both known and novel coding and non-coding RNAs, alternative splicing events, and cell-type specific changes that may contribute to alcohol-related pathologies. This review offers an integrated perspective on alcohol-responsive transcriptional changes in the human brain underlying the regulatory gene networks that contribute to alcohol dependence. This article is part of the Special Issue entitled "Alcoholism".

The phospholipid composition of the human entorhinal cortex remains relatively stable over 80 years of adult aging

Membrane lipid composition is altered in the brain during the pathogenesis of several age-related neurodegenerative diseases, including Alzheimer's disease. The entorhinal cortex is one of the first regions of the brain to display the neuropathology typical of Alzheimer's disease, yet little is known about the changes that occur in membrane lipids within this brain region during normal aging (i.e., in the absence of dementia). In the present study, the phospholipid composition of mitochondrial and microsomal membranes from human entorhinal cortex was examined for any changes over the adult lifespan (18-98 years). Overall, changes in several molecular phospholipids were seen with age in the entorhinal cortex across both membranes. The proportion of total phosphatidylcholine within the mitochondrial fraction increased within the entorhinal cortex with age, while total mitochondrial phosphatidylethanolamine decreased. Many mitochondrial phosphatidylethanolamines containing docosahexaenoic acid increased with age; however, this did not translate into an overall age-related increase in total mitochondrial docosahexaenoic acid. The most abundant phospholipid present within the human brain, PC 16:0_18:1, also increased with age within the mitochondrial membranes of the entorhinal cortex. When compared to other regions of the brain, the phospholipid composition of the entorhinal cortex remains relatively stable in adults over the lifespan in the absence of dementia.

Cortical grey matter volume reduction in people with schizophrenia is associated with neuro-inflammation

Cortical grey matter volume deficits and neuro-inflammation exist in patients with schizophrenia, although it is not clear whether elevated cytokines contribute to the cortical volume reduction. We quantified cortical and regional brain volumes in fixed postmortem brains from people with schizophrenia and matched controls using stereology. Interleukin (IL)-6, IL-1β, IL-8 and SERPINA3 messenger RNAs (mRNAs) were quantified in the contralateral fresh frozen orbitofrontal cortex. We found a small, but significant reduction in cortical grey matter (1.3%; F(1,85)=4.478, P=0.037) and superior frontal gyrus (6.5%; F(1,80)=5.700, P=0.019) volumes in individuals with schizophrenia compared with controls. Significantly reduced cortical grey matter (9.2%; F(1,24)=8.272, P=0.008) and superior frontal gyrus (13.9%; F(1,20)=5.374, P=0.031) volumes were found in cases with schizophrenia and 'high inflammation' status relative to schizophrenia cases with 'low inflammation' status in the prefrontal cortex. The expression of inflammatory mRNAs in the orbitofrontal cortex was significantly correlated with those in dorsolateral prefrontal cortex (all r>0.417, all P<0.022), except for IL-8. Moreover, average daily and lifetime antipsychotic intake negatively correlated with cortical grey matter and superior frontal gyrus volumes (all r<-0.362, all P<0.05). The results suggest that the reduction in cortical grey matter volume in people with schizophrenia is exaggerated in those who have high expression of inflammatory cytokines. Further, antipsychotic medication intake does not appear to ameliorate the reduction in brain volume.

The effects of chronic smoking on the pathology of alcohol-related brain damage

Both pathological and neuroimaging studies demonstrate that chronic alcohol abuse causes brain atrophy with widespread white matter loss limited gray matter loss. Recent neuroimaging studies suggest that tobacco smoking also causes brain atrophy in both alcoholics and neurologically normal individuals; however, this has not been confirmed pathologically. In this study, the effects of smoking and the potential additive effects of concomitant alcohol and tobacco consumption were investigated in autopsied human brains. A total of 44 cases and controls were divided into four groups: 16 non-smoking controls, nine smoking controls, eight non-smoking alcoholics, and 11 smoking alcoholics. The volumes of 26 gray and white matter regions were measured using an established point-counting technique. The results showed trends for widespread white matter loss in alcoholics (p < 0.007) but no effect on gray matter regions. In contrast, smoking alone had no effect on brain atrophy and the combination of smoking and alcohol showed no additional effect. Neuronal density was analyzed as a more sensitive assay of gray matter integrity. Similar to the volumetric analysis, there was a reduction in neurons (29%) in the prefrontal cortex of alcoholics, albeit this was only a trend when adjusted for potential confounders (p < 0.06). There were no smoking or combinatorial effects on neuronal density in any of the three regions examined. These results do not support the hypothesis that smoking exacerbates alcohol-related brain damage. The trends here support previous studies that alcohol-related brain damage is characterized by focal neuronal loss and generalized white matter atrophy. These disparate effects suggest that two different pathogenic mechanisms may be operating in the alcoholic brain. Future studies using ultrastructural or molecular techniques will be required to determine if smoking has more subtle effects on the brain and how chronic alcohol consumption leads to widespread white matter loss.