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Abstract

Aims
Alcohol use alters the reward signaling processes contributing to the development of addiction. We studied the effects of alcohol use disorder (AUD) on brain regions and blood of deceased women and men to examine sex-dependent differences in epigenetic changes associated with AUD. We investigated the effects of alcohol use on the gene promoter methylation of GABBR1 coding for GABAB receptor subunit 1 in blood and brain.


Methods
We chose six brain regions associated with addiction and the reward pathway (nucleus arcuatus, nucleus accumbens, the mamillary bodies, amygdala, hippocampus and anterior temporal cortex) and performed epigenetic profiling of the proximal promoter of the GABBR1 gene of post-mortem brain and blood samples of 17 individuals with AUD pathology (4 female, 13 male) and 31 healthy controls (10 female, 21 male).


Results
Our results show sex-specific effects of AUD on GABBR1 promoter methylation. Especially, CpG −4 showed significant tissue-independent changes and significantly decreased methylation levels for the AUD group in the amygdala and the mammillary bodies of men. We saw prominent and consistent change in CpG-4 across all investigated tissues. For women, no significant loci were observed.


Conclusion
We found sex-dependent differences in GABBR1 promoter methylation in relation to AUD. CpG-4 hypomethylation in male individuals with AUD is consistent for most brain regions. Blood shows similar results without reaching significance, potentially serving as a peripheral marker for addiction-associated neuronal adaptations. Further research is needed to discover more contributing factors in the pathological alterations of alcohol addiction to offer sex-specific biomarkers and treatment.

AbstractAimsThe dopamine receptor D2 (DRD2) is substantially involved in several forms of addiction. In addition to genetic polymorphisms, epigenetic mechanisms have emerged as an important means of regulation. Previously, DRD2 hypo- and hyper-methylation have been observed in alcohol use disorder (AUD). Blood samples are commonly used as a surrogate marker of epigenetic alterations in epigenetic research, but few specific comparisons between blood and brain tissue samples in AUD exist.MethodsWe used post-mortem brain tissue samples of 17 deceased patients with AUD and 31 deceased controls to investigate the relationship between blood and brain methylation of the DRD2 promoter.ResultsWhen investigating individual cytosine methylation sites (CpG), several significant differences were found in the nucleus accumbens and hippocampus in the study population. Investigating binding sites with significant differences in methylation levels revealed hypomethylated CpGs targeting mainly activating transcription factors.ConclusionThese findings support an altered transcription of the DRD2 gene in AUD specimens with a consecutively changed reward response in the brain. While methylation between specific brain regions and blood is comparable, our study further suggests that blood methylation cannot provide meaningful perspectives on DRD2 promoter methylation in the brain.

Examination of a person who has been a victim of a physical or sexual assault may be very important for upcoming legal proceedings. In the context of a clinical forensic examination, physical findings are recorded and biological trace material is gathered and secured. Ideally, all forensic findings are documented in a detailed report combined with photographic documentation, which employs a forensic scale to depict the size of the injuries. However, the integrity of such forensic findings depends particularly on two factors. First, the examination needs to be conducted professionally to ensure that the findings are properly admissible as court evidence. Second, the examination should take place as soon as possible because the opportunity to successfully secure biological samples declines rapidly with time. Access to low-threshold clinical forensic examinations is not evenly provided in all member states of the European Union (EU); in some states, they are not available at all. As part of the JUSTeU! (Juridical standards for clinical forensic examinations of victims of violence in Europe) project, the Ludwig Boltzmann Institute for Clinical Forensic Imaging in Graz, Austria created (in cooperation with its international partner consortium) a questionnaire: the purpose was to collect information about support for victims of physical and/or sexual assault in obtaining a low-threshold clinical forensic examination in various countries of the EU. Our paper provides a summary of the responses and an overview of the current situation concerning provided clinical forensic services.