Epigenetics of drug abuse: predisposition or response

Drug addiction and treatment: An epigenetic perspective

Drug addiction is a complex disease affected by numerous genetic and environmental factors. Brain regions in reward pathway, neuronal adaptations, genetic and epigenetic interactions causing transcriptional enhancement or repression of multiple genes induce different addiction phenotypes for varying duration. Addictive drug use causes epigenetic alterations and similarly epigenetic changes induced by environment can promote addiction. Epigenetic mechanisms include DNA methylation and post-translational modifications like methylation, acetylation, phosphorylation, ubiquitylation, sumoylation, dopaminylation and crotonylation of histones, and ADP-ribosylation. Non-coding RNAs also induce epigenetic changes. This review discusses these above areas and stresses the need for exploring epidrugs as a treatment alternative and adjunct, considering the limited success of current addiction treatment strategies. Epigenome editing complexes have lately been effective in eukaryotic systems. Targeted DNA cleavage techniques such as CRISPR-Cas9 system, CRISPR-dCas9 complexes, transcription activator-like effector nucleases (TALENs) and zinc-finger nucleases (ZFNs) have been exploited as targeted DNA recognition or anchoring platforms, fused with epigenetic writer or eraser proteins and delivered by transfection or transduction methods. Efficacy of epidrugs is seen in various neuropsychiatric conditions and initial results in addiction treatment involving model organisms are remarkable. Epidrugs present a promising alternative treatment for addiction.

miRNAs and Substances Abuse: Clinical and Forensic Pathological Implications: A Systematic Review

Substance addiction is a chronic and relapsing brain disorder characterized by compulsive seeking and continued substance use, despite adverse consequences. The high prevalence and social burden of addiction are indisputable; however, the available intervention is insufficient. The modulation of gene expression and aberrant adaptation of neural networks are attributed to the changes in brain functions under repeated exposure to addictive substances. Considerable studies have demonstrated that miRNAs are strong modulators of post-transcriptional gene expression in substance addiction. The emerging role of microRNA (miRNA) provides new insights into many biological and pathological processes in the central nervous system: their variable expression in different regions of the brain and tissues may play a key role in regulating the pathophysiological events of addiction. This work provides an overview of the current literature on miRNAs involved in addiction, evaluating their impaired expression and regulatory role in neuroadaptation and synaptic plasticity. Clinical implications of such modulatory capacities will be estimated. Specifically, it will evaluate the potential diagnostic role of miRNAs in the various stages of drug and substance addiction. Future perspectives about miRNAs as potential novel therapeutic targets for substance addiction and abuse will also be provided.

Addictive drugs modify neurogenesis, synaptogenesis and synaptic plasticity to impair memory formation through neurotransmitter imbalances and signaling dysfunction

Drug abuse changes neurophysiological functions at multiple cellular and molecular levels in the addicted brain. Well-supported scientific evidence suggests that drugs negatively affect memory formation, decision-making and inhibition, and emotional and cognitive behaviors. The mesocorticolimbic brain regions are involved in reward-related learning and habitual drug-seeking/taking behaviors to develop physiological and psychological dependence on the drugs. This review highlights the importance of specific drug-induced chemical imbalances resulting in memory impairment through various neurotransmitter receptor-mediated signaling pathways. The mesocorticolimbic modifications in the expression levels of brain-derived neurotrophic factor (BDNF) and the cAMP-response element binding protein (CREB) impair reward-related memory formation following drug abuse. The contributions of protein kinases and microRNAs (miRNAs), along with the transcriptional and epigenetic regulation have also been considered in memory impairment underlying drug addiction. Overall, we integrate the research on various types of drug-induced memory impairment in distinguished brain regions and provide a comprehensive review with clinical implications addressing the upcoming studies.

Neonatal opioid toxicity: opioid withdrawal (abstinence) syndrome with emphasis on pharmacogenomics and respiratory depression

The increasing use of opioids in pregnant women has led to an alarming rise in the number of cases of neonates with drug-induced withdrawal symptoms known as neonatal opioid withdrawal syndrome (NOWS). NOWS is a toxic heterogeneous condition with many neurologic, autonomic, and gastrointestinal symptoms including poor feeding, irritability, tachycardia, hypertension, respiratory defects, tremors, hyperthermia, and weight loss. Paradoxically, for the management of NOWS, low doses of morphine, methadone, or buprenorphine are administered. NOWS is a polygenic disorder supported by studies of genomic variation in opioid-related genes. Single-nucleotide polymorphisms (SNPs) in CYP2B6 are associated with variations in NOWS infant responses to methadone and SNPs in the OPRM1, ABCB1, and COMT genes are associated with need for treatment and length of hospital stay. Epigenetic gene changes showing higher methylation levels in infants and mothers have been associated with more pharmacologic treatment in the case of newborns, and for mothers, longer infant hospital stays. Respiratory disturbances associated with NOWS are not well characterized. Little is known about the effects of opioids on developing neonatal respiratory control and respiratory distress (RD), a potential problem for survival of the neonate. In a rat model to test the effect of maternal opioids on the developing respiratory network and neonatal breathing, maternal-derived methadone increased apneas and lessened RD in neonates at postnatal (P) days P0 and P1. From P3, breathing normalized with age suggesting reorganization of respiratory rhythm-generating circuits at a time when the preBötC becomes the dominant inspiratory rhythm generator. In medullary slices containing the preBötC, maternal opioid treatment plus exposure to exogenous opioids showed respiratory activity was maintained in younger but not older neonates. Thus, maternal opioids blunt centrally controlled respiratory frequency responses to exogenous opioids in an age-dependent manner. In the absence of maternal opioid treatment, exogenous opioids abolished burst frequencies at all ages. Prenatal opioid exposure in children stunts growth rate and development while studies of behavior and cognitive ability reveal poor performances. In adults, high rates of attention deficit disorder, hyperactivity, substance abuse, and poor performances in intelligence and memory tests have been reported.

Biopharmaceuticals against substance use disorders - Present and future

BACKGROUND AND OBJECTIVES

Pharmacological treatments available for substance use disorder (SUD) focus on pharmacodynamics, agonizing or antagonizing the drug of abuse (DOA) on receptor level. Drawbacks of this approach include the reliance on long-term patient compliance, on-target off-site effects, perpetuation of addiction and unavailability for many DOAs. Newer, pharmacokinetic approaches are needed that restrict DOA's access to the brain or disrupt DOA-instated brain changes maintaining addiction. Biotechnology might be able to provide the right biopharmaceutical tools to deliver a fine-tuned solution with less side effects compared to currently available treatments.

METHODS

This review examines the available literature on biopharmaceuticals developed to treat SUD.

RESULTS

Active and passive immunization, metabolic enhancers that augment DOA metabolism and clearance, as well as genetic/epigenetic modulation are promising next generation SUD treatments. Active immunization relies on production of antidrug antibodies by means of vaccination, while passive immunization constitutes of exogenous administration of such antibodies. Metabolic enhancers include drug-specific metabolizing enzymes that can be administered or secreted by modified skin grafts, as well as catalytic antibodies that hasten DOA metabolism. Nanotechnological advances can also allow for brain delivery of siRNAs, mRNAs or DNA in order to modulate central, common in all addictions, genetic or epigenetic targets attenuating drug seeking behavior and reversing drug-induced brain changes.

CONCLUSIONS

and Scientific Significance: Biopharmaceuticals can in the future complement or even replace traditional pharmacodynamics approaches in SUD treatment. While passive and active immunization biopharmaceuticals have entered human clinical trials, metabolic enhancers and genetic approaches are at the preclinical level.

Nicotine on the developing brain

Developmental periods such as gestation and adolescence have enhanced plasticity leaving the brain vulnerable to harmful effects from nicotine use. Proper brain maturation and circuit organization is critical for normal physiological and behavioral outcomes. Although cigarette smoking has declined in popularity, noncombustible nicotine products are readily used. The misperceived safety of these alternatives lead to widespread use among vulnerable populations such as pregnant women and adolescents. Nicotine exposure during these sensitive developmental windows is detrimental to cardiorespiratory function, learning and memory, executive function, and reward related circuitry. In this review, we will discuss clinical and preclinical evidence of the adverse alterations in the brain and behavior following nicotine exposure. Time-dependent nicotine-induced changes in reward related brain regions and drug reward behaviors will be discussed and highlight unique sensitivities within a developmental period. We will also review long lasting effects of developmental exposure persisting into adulthood, along with permanent epigenetic changes in the genome which can be passed to future generations. Taken together, it is critical to evaluate the consequences of nicotine exposure during these vulnerable developmental windows due to its direct impact on cognition, potential trajectories for other substance use, and implicated mechanisms for the neurobiology of substance use disorders.

Is DNA methylation in the brain a mechanism of alcohol use disorder?

Alcohol use disorder (AUD) is a worldwide problem. Unfortunately, the molecular mechanisms of alcohol misuse are still poorly understood, therefore successful therapeutic approaches are limited. Accumulating data indicate that the tendency for compulsive alcohol use is inherited, suggesting a genetic background as an important factor. However, the probability to develop AUD is also affected by life experience and environmental factors. Therefore, the epigenetic modifications that are altered over lifetime likely contribute to increased risk of alcohol misuse. Here, we review the literature looking for the link between DNA methylation in the brain, a common epigenetic modification, and AUD-related behaviors in humans, mice and rats. We sum up the main findings, identify the existing gaps in our knowledge and indicate future directions of the research.

Differences in MB-COMT DNA methylation in monozygotic twins on phenotypic indicators of impulsivity

Epigenetic modifications of the membrane bound catechol-O-methyltransferase (MB-COMT) gene may affect the enzymatic degradation of dopamine, and consequently, human behavior. This study investigated the association between membrane bound catechol-O-methyltransferase DNA methylation (DNAm) differences in 92 monozygotic (MZ) twins with phenotypic manifestations of cognitive, behavioral, and personality indicators associated with reward-related behaviors and lack of control. We used pyrosequencing to determine DNAm of the regulatory region of membrane bound catechol-O-methyltransferase in saliva DNA. Results of intrapair differences in the percentage of membrane bound catechol-O-methyltransferase DNAm at each of five CpG sites show that there are associations between phenotypic indicators of lack of control and membrane bound catechol-O-methyltransferase DNAm differences on CpG1, CpG2 and CpG4, suggesting the common epigenetic patterns for personality traits, cognitive functions, and risk behaviors.

A review of the genomics of neonatal abstinence syndrome

Neonatal abstinence syndrome (NAS) is a constellation of signs of withdrawal occurring after birth following in utero exposure to licit or illicit opioids. Despite significant research and public health efforts, NAS remains challenging to diagnose, predict, and manage due to highly variable expression. Biomarker discovery in the field of NAS is crucial for stratifying risk, allocating resources, monitoring longitudinal outcomes, and identifying novel therapeutics. There is considerable interest in identifying important genetic and epigenetic markers of NAS severity and outcome that can guide medical decision making, research efforts, and public policy. A number of recent studies have suggested that genetic and epigenetic changes are associated with NAS severity, including evidence of neurodevelopmental instability. This review will provide an overview of the role of genetics and epigenetics in short and longer-term NAS outcomes. We will also describe novel research efforts using polygenic risk scores for NAS risk stratification and salivary gene expression to understand neurobehavioral modulation. Finally, emerging research focused on neuroinflammation from prenatal opioid exposure may elucidate novel mechanisms that could lead to development of future novel therapeutics.

DNA methylation in cocaine use disorder-An epigenome-wide approach in the human prefrontal cortex

BACKGROUND

Cocaine use disorder (CUD) is characterized by a loss of control over cocaine intake and is associated with structural, functional, and molecular alterations in the human brain. At the molecular level, epigenetic alterations are hypothesized to contribute to the higher-level functional and structural brain changes observed in CUD. Most evidence of cocaine-associated epigenetic changes comes from animal studies while only a few studies have been performed using human tissue.

METHODS

We investigated epigenome-wide DNA methylation (DNAm) signatures of CUD in human post-mortem brain tissue of Brodmann area 9 (BA9). A total of N = 42 BA9 brain samples were obtained from N = 21 individuals with CUD and N = 21 individuals without a CUD diagnosis. We performed an epigenome-wide association study (EWAS) and analyzed CUD-associated differentially methylated regions (DMRs). To assess the functional role of CUD-associated differential methylation, we performed Gene Ontology (GO) enrichment analyses and characterized co-methylation networks using a weighted correlation network analysis. We further investigated epigenetic age in CUD using epigenetic clocks for the assessment of biological age.

RESULTS

While no cytosine-phosphate-guanine (CpG) site was associated with CUD at epigenome-wide significance in BA9, we detected a total of 20 CUD-associated DMRs. After annotation of DMRs to genes, we identified Neuropeptide FF Receptor 2 (NPFFR2) and Kalirin RhoGEF Kinase (KALRN) for which a previous role in the behavioral response to cocaine in rodents is known. Three of the four identified CUD-associated co-methylation modules were functionally related to neurotransmission and neuroplasticity. Protein-protein interaction (PPI) networks derived from module hub genes revealed several addiction-related genes as highly connected nodes such as Calcium Voltage-Gated Channel Subunit Alpha1 C (CACNA1C), Nuclear Receptor Subfamily 3 Group C Member 1 (NR3C1), and Jun Proto-Oncogene, AP-1 Transcription Factor Subunit (JUN). In BA9, we observed a trend toward epigenetic age acceleration (EAA) in individuals with CUD remaining stable even after adjustment for covariates.

CONCLUSION

Results from our study highlight that CUD is associated with epigenome-wide differences in DNAm levels in BA9 particularly related to synaptic signaling and neuroplasticity. This supports findings from previous studies that report on the strong impact of cocaine on neurocircuits in the human prefrontal cortex (PFC). Further studies are needed to follow up on the role of epigenetic alterations in CUD focusing on the integration of epigenetic signatures with transcriptomic and proteomic data.

Psychostimulants influence oxidative stress and redox signatures: the role of DNA methylation

Objective: Psychostimulant use induces oxidative stress and alters redox imbalance, influencing epigenetic signatures in the central nervous system (CNS). Among the various epigenetic changes, DNA methylation is directly linked to oxidative stress metabolism via critical redox intermediates such as NAD+, S-adenosylmethionine (SAM), and 2-oxoglutarate. Fluctuations in these intermediates directly influence epigenetic signatures, which leads to detectable alterations in gene expression and protein modification. This review focuses on recent advances in the impact of psychostimulant use on redox-imbalance-induced DNA methylation to develop novel epigenetics-based early interventions. Methods: This review is based on collective research data obtained from the PubMed, Science Direct, and Medline databases. The keywords used in the electronic search in these databases were redox, substance use disorder, psychostimulants, DNA methylation, and neurological diseases. Results: Instability in DNA methylation levels and redox expression effects are reported in various behavioral models stimulated by psychostimulants and opioids, indicating the widespread involvement of epigenetic changes in DNA methylation signatures in neurological disorders. Discussion: This review summarizes the need for more studies and experimental evaluations of DNA-methylation-based strategies that may help to understand the association between psychostimulant use and oxidative stress or redox-linked metabolic recalibration influencing neuronal impairments.

A study on methylation of two CpG islands of MAOA gene promoter among opium-addicted males undergoing methadone treatment

The association between methylation of MAOA gene promoter and alcohol and nicotine dependence has been demonstrated in women but not in men yet. Antisocial personality disorder (ASPD) and substance use disorders (SUD) are two types of disorders that could highly be influenced by methylation-induced changes in MAOA function. The aim of the current study is to investigate the effect of opioid addiction on methylation of MAOA gene promoter in males. DNA was extracted from the whole blood of all samples (29 opium-addicted individuals undergoing methadone treatment and 28 healthy people) according to the extraction protocol, followed by treating these samples with bisulfite kits. The investigated region including two CpG islands in the promoter region of MAOA gene contained 35 CpG dinucleotides investigated through Sanger sequencing method. The frequency of methylation at two CpG islands of MAOA gene promoter regions was equal to zero among addicted individuals undergoing methadone treatment and healthy peoples. Then, comparing methylation levels among the study group is not applicable. In conclusion, there was no association between opium addiction and methylation of the MAOA promoter regions in opium-addicted male undergoing methadone treatment.

Potential biomarkers of addiction identified by real-time PCR in human peripheral blood lymphocytes: a narrative review

Addiction-related neurobiological factors could be considered as potential biomarkers. The concentration of peripheral biomarkers in tissues like blood lymphocytes may mirror their brain levels. This review is focused on the mRNA expression of potential addiction biomarkers in human peripheral blood lymphocytes (PBLs). PubMed, EMBASE, Web of Science, Scopus and Google Scholar were searched using the keywords 'addiction', 'biomarker', 'peripheral blood lymphocyte', 'gene expression' and 'real-time PCR'. The results showed the alterations in the regulation of genes such as dopamine receptors, opioid receptors, NMDA receptors, cannabinoid receptors, α-synuclein, DYN, MAO-A, FosB and orexin-A as PBLs biomarkers in addiction stages. Such variations could also be found during abstinence and relapse. PBLs biomarkers may help in drug development and have clinical implications.

Effect of Prenatal Opioid Exposure on the Human Placental Methylome

Prenatal exposure to addictive drugs can lead to placental epigenetic modifications, but a methylome-wide evaluation of placental DNA methylation changes after prenatal opioid exposure has not yet been performed. Placental tissue samples were collected at delivery from 19 opioid-exposed and 20 unexposed control full-term pregnancies. Placental DNA methylomes were profiled using the Illumina Infinium HumanMethylationEPIC BeadChip. Differentially methylated CpG sites associated with opioid exposure were identified with a linear model using the ‘limma’ R package. To identify differentially methylated regions (DMRs) spanning multiple CpG sites, the ‘DMRcate’ R package was used. The functions of genes mapped by differentially methylated CpG sites and DMRs were further annotated using Enrichr. Differentially methylated CpGs (n = 684, unadjusted p < 0.005 and |∆β| ≥ 0.05) were mapped to 258 genes (including PLD1, MGAM, and ALCS2). Differentially methylated regions (n = 199) were located in 174 genes (including KCNMA1). Enrichment analysis of the top differentially methylated CpG sites and regions indicated disrupted epigenetic regulation of genes involved in synaptic structure, chemical synaptic transmission, and nervous system development. Our findings imply that placental epigenetic changes due to prenatal opioid exposure could result in placental dysfunction, leading to abnormal fetal brain development and the symptoms of opioid withdrawal in neonates.

Roles of miR-592-3p and Its Target Gene, TMEFF1, in the Nucleus Accumbens During Incubation of Morphine Craving

BACKGROUND

Prolonged forced abstinence from morphine can increase cue-induced cravings for the drug, contributing to a persistent vulnerability to relapse. Previous studies have identified the implications of aberrant microRNA (miRNA) regulation in the pathogenesis of morphine addiction, but the changes in miRNA expression during the incubation of morphine craving are still unknown.

METHODS

Nucleus accumbens (NAc)-specific altered miRNA transcriptomics was determined in a mouse model of cue-induced incubation of morphine craving following a next-generation sequencing method and verified by RT-qPCR. Bioinformatics analysis was performed to predict the target gene of selected miRNA, and the protein expression of the target gene was detected by western blot. A dual-luciferase assay was performed to confirm the binding sites, and gain- and loss-of-function strategy was applied to understand the mechanism of miRNA and its target gene.

RESULTS

The miR-592-3p observed to be downregulated in the NAc core was linked to the incubation of morphine craving, and a dual-luciferase assay was performed to confirm the binding sites of miR-592-3p in its target gene, tomoregulin-1 (TMEFF1). Also, gain- and loss-of-function analyses revealed that the inhibition of miR-592-3p expression in the NAc core negatively regulated TMEFF1 expression, thereby enhancing the incubation of morphine craving; however, the overexpression of miR-592-3p in the NAc core resulted in a decreased expression of TMEFF1, thereby reducing the incubation of morphine craving.

CONCLUSION

Our findings demonstrated that miR-592-3p can improve the incubation of morphine craving by targeting TMEFF1, and thus, it holds a therapeutic potential to inhibit opioid craving.

Commentary on the Culture of Prevention

Despite significant progress in prevention science over the past 30 years in developing evidence-based interventions and policies, there has not been equal success in attracting support from policymakers and gaining acceptance by communities. In recognition of this gap, the editors of Prevention Science put out a call to scientists to help clarify and define the concept of a “culture of prevention.” Such a culture would influence the creation of an infrastructure for implementing and sustaining the most effective strategies informed by research. The journal call stated a culture of prevention was a “general orientation or readiness of a group of people… to address problems by using a preventive, rather than a reactive approach.” This commentary examines the concept demonstrated in the array of papers presented here in which the “culture of prevention” is applied in different contexts—occupational safety and health, substance use, school, governmental, community, around problem behaviors, and violence. It is important to note that the papers represent perspectives and experiences from several countries, including some cross-national experiences providing an international framework. While a final definition awaits further research, the commentary summarizes important elements that might constitute that evolving definition and pave the way for the implementation of more effective prevention programming.

DNA methylation of the glucocorticoid receptor gene predicts substance use in adolescence: longitudinal data from over 1000 young individuals

Early life stress has been linked to increased methylation of the Nuclear Receptor Subfamily 3 Group C Member 1 (NR3C1) gene, which codes for the glucocorticoid receptor. Moreover, early life stress has been associated with substance use initiation at a younger age, a risk factor for developing substance use disorders. However, no studies to date have investigated whether NR3C1 methylation can predict substance use in young individuals. This study included adolescents 13-14 years of age that reported no history of substance use at baseline, (N = 1041; males = 46%). Participants contributed saliva DNA samples and were followed in middle adolescence as part of KUPOL, a prospective cohort study of 7th-grade students in Sweden. Outcome variables were self-reports of (i) recent use, (ii) lifetime use, and (iii) use duration of (a) alcohol, (b) tobacco products, (c) cannabis, or (d) any substance. Outcomes were measured annually for three consecutive years. The predictor variable was DNA methylation at the exon 1 F locus of NR3C1. Risk and rate ratios were calculated as measures of association, with or without adjustment for internalizing symptoms and parental psychiatric disorders. For a subset of individuals (N = 320), there were also morning and afternoon salivary cortisol measurements available that were analyzed in relation to NR3C1 methylation levels. Baseline NR3C1 hypermethylation associated with future self-reports of recent use and use duration of any substance, before and after adjustment for potential confounders. The overall estimates were attenuated when considering lifetime use. Sex-stratified analyses revealed the strongest association for cigarette use in males. Cortisol analyses revealed associations between NR3C1 methylation and morning cortisol levels. Findings from this study suggest that saliva NR3C1 hypermethylation can predict substance use in middle adolescence. Additional longitudinal studies are warranted to confirm these findings.

HIV-1 Natural Antisense Transcription and Its Role in Viral Persistence

Natural antisense transcripts (NATs) represent a class of RNA molecules that are transcribed from the opposite strand of a protein-coding gene, and that have the ability to regulate the expression of their cognate protein-coding gene via multiple mechanisms. NATs have been described in many prokaryotic and eukaryotic systems, as well as in the viruses that infect them. The human immunodeficiency virus (HIV-1) is no exception, and produces one or more NAT from a promoter within the 3’ long terminal repeat. HIV-1 antisense transcripts have been the focus of several studies spanning over 30 years. However, a complete appreciation of the role that these transcripts play in the virus lifecycle is still lacking. In this review, we cover the current knowledge about HIV-1 NATs, discuss some of the questions that are still open and identify possible areas of future research.

Epigenome-wide study of brain DNA methylation following acute opioid intoxication

BACKGROUND

Opioid abuse poses significant risk to individuals in the United States and epigenetic changes are a leading potential biomarker of opioid abuse. Current evidence, however, is mostly limited to candidate gene analysis in whole blood. To clarify the association between opioid abuse and DNA methylation, we conducted an epigenome-wide analysis of DNA methylation in brain samples of individuals who died from acute opioid intoxication and group-matched controls.

METHODS

Tissue samples were extracted from the dorsolateral prefrontal cortex of 153 deceased individuals (Mage = 35.42; 62 % male; 77 % European ancestry). The study included 72 opioid samples, 53 psychiatric controls, and 28 normal controls. The epigenome-wide analysis was implemented using the Illumina MethylationEPIC BeadChip; analyses adjusted for sociodemographic characteristics, negative control principal components, ancestry principal components, cellular composition, and surrogate variables. Horvath's epigenetic age and Levine's PhenoAge were calculated, and gene set enrichment analyses were performed.

RESULTS

Although no CpG sites survived false-discovery rate correction for multiple testing, 13 sites surpassed a relaxed significance threshold (p < 1.0 × 10-5). One of these sites was located within Netrin-1, a gene implicated in kappa opioid receptor activity. There was an association between opioid use and accelerated PhenoAge (b = 2.24, se = 1.11, p = .045). Gene set enrichment analyses revealed enrichment of differential methylation in GO and KEGG pathways broadly related to substance use.

CONCLUSIONS

Netrin-1 may be associated with opioid overdose, and future research with larger samples across stages of opioid use will elucidate the complex genomics of opioid abuse.

Placental OPRM1 DNA methylation and associations with neonatal opioid withdrawal syndrome, a pilot study

Aims:

Epigenetic variation of DNA methylation of the mu-opioid receptor gene (OPRM1) has been identified in the blood and saliva of individuals with opioid use disorder (OUD) and infants with neonatal opioid withdrawal syndrome (NOWS). It is unknown whether epigenetic variation in OPRM1 exists within placental tissue in women with OUD and whether it is associated with NOWS outcomes. In this pilot study, the authors aimed to 1) examine the association between placental OPRM1 DNA methylation levels and NOWS outcomes, and 2) compare OPRM1 methylation levels in opioid-exposed versus non-exposed control placentas.

Methods:

Placental tissue was collected from eligible opioid (n = 64) and control (n = 29) women after delivery. Placental DNA was isolated and methylation levels at six cytosine-phosphate-guanine (CpG) sites within the OPRM1 promoter were quantified. Methylation levels were evaluated for associations with infant NOWS outcome measures: need for pharmacologic treatment, length of hospital stay (LOS), morphine treatment days, and treatment with two medications. Regression models were created and adjusted for clinical co-variates. Methylation levels between opioid and controls placentas were also compared.

Results:

The primary opioid exposures were methadone and buprenorphine. Forty-nine (76.6%) of the opioid-exposed infants required pharmacologic treatment, 10 (15.6%) two medications, and average LOS for all opioid-exposed infants was 16.5 (standard deviation 9.7) days. There were no significant associations between OPRM1 DNA methylation levels in the six CpG sites and any NOWS outcome measures. No significant differences were found in methylation levels between the opioid and control samples.

Conclusions:

No significant associations were found between OPRM1 placental DNA methylation levels and NOWS severity in this pilot cohort. In addition, no significant differences were seen in OPRM1 methylation in opioid versus control placentas. Future association studies examining methylation levels on a genome-wide level are warranted.

Role of GABRD Gene Methylation in the Nucleus Accumbens in Heroin-Seeking Behavior in Rats

Epigenetic modifications such as DNA methylation play important roles in regulating gene expression and may mediate neuroplasticity and lead to drug-induced aberrant behaviors. Although several brain regions and neurobiological mechanisms have been suggested to be involved in these processes, there is remarkably little known about the effects of DNA methylation on heroin-seeking behavior. Using a Sprague-Dawley rat model, we show that heroin self-administration resulted in gamma-aminobutyric acid type A receptor subunit delta (GABRD) gene hypomethylation, which was associated with transcriptional upregulation of GABRD in the nucleus accumbens (NAc). Systemic l-methionine (MET) administration significantly strengthened the reinstatement of heroin-seeking behavior induced by heroin priming, whereas intra-NAc injections of the DNA methyltransferase (DNMT) inhibitor 5-aza-2'-deoxycytidine (5-Aza-dC) had the opposite effect on heroin-seeking. Meanwhile, 5-Aza-dC treatment decreased DNA methylation and upregulated the expression of GABRD in the NAc, whereas MET had the opposite effect. Our results also reveal that 5-Aza-dC might alter the methylation landscape of the GABRD gene by directly repressing DNMT1 and DNMT3A expression. Furthermore, reinstatement of heroin-seeking behavior was significantly inhibited by directly overexpressing GABRD and remarkably reinforced by GABRD gene silencing in the NAc. Collectively, these results suggest that targeting the GABRD gene and its methylation might represent a novel pharmacological strategy for treating heroin addiction and relapse.

Classical Psychedelics as Therapeutics in Psychiatry - Current Clinical Evidence and Potential Therapeutic Mechanisms in Substance Use and Mood Disorders

Classical psychedelics, primarily psilocybin and lysergic acid diethylamide (LSD), have been used and extensively studied in Western medicine as part of substance-assisted psychotherapy in the 1950s and 1960s. Modern clinical research is currently gaining momentum and provides new evidence for the safety and efficacy of classical psychedelics (primarily psilocybin, but also LSD and ayahuasca) in the treatment of different psychiatric conditions, including substance use and mood disorders.In this review article, we outline common pathological mechanisms of substance use disorders (SUD) and unipolar depression. Next, the current literature on the effects of psychedelics is summarized in order to generate hypotheses regarding their potential therapeutic mechanisms of action in treating these psychiatric conditions. Finally, we review and discuss clinical trials published since 2011 investigating the effects of psychedelics in SUD and depression.While results from those modern clinical trials are promising, most of them do not meet the methodological requirements to allow firm conclusions on the clinical efficacy of psychedelics. Larger, blinded, randomized controlled trials (RCT) with clearly defined patient groups and well-defined primary endpoints are needed. Additionally, the therapeutic mechanisms of classical psychedelics are currently unknown. This review presents hypotheses derived from preclinical and human studies that need to be tested in future trials to better understand the clinical potential of psychedelic substances in modern psychiatry.

Changes in the Expression of DNA Methylation Related Genes in Leukocytes of Persons with Alcohol and Drug Dependence

Background and objectives. Though numerous studies have shown that the dysregulation of the epigenetic control is involved in disease manifestation, limited data is available on the transcriptional activity of DNA methylation related genes in alcohol and drug addiction. With regard to this, in this study we analyzed the expression levels of genes involved in DNA methylation, including DNMT1, DNMT3a, MeCP2, MBD1, MBD2, MBD3 and MBD4, in blood samples of alcohol and drug dependent persons in comparison to healthy abstainers.

Methods. The study included 51 participants: 16 persons with alcohol dependence, 17 persons with drug dependence and 18 clinically healthy controls. To detect the relative mRNA expression levels of the studied genes, Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis was applied.

Results. Of the seven studied genes, four showed altered expression. MeCP2 and MBD1 were downregulated in the alcohol dependent group (FC = 0.805, p = 0.015 and FC = 0.846, p = 0.034, respectively), while DNMT1 and MBD4 were upregulated in the group with drug dependence (FC = 1.262, p = 0.001 and FC = 1.249, p = 0.005, respectively). No statistically significant changes in the relative mRNA expression were found for DNMT3a, MBD2 and MBD3 genes.

Conclusions. Our results are indicative for a role of DNA methylation related genes in alcohol and drug addiction mediated through changes in their transcriptional activity. Studies in this direction will enable better understanding of the underlying mechanisms of addictions supporting the development of more effective therapeutic strategies.

Depression and substance use disorders: Clinical comorbidity and shared neurobiology

Mood disorders, including major depressive disorder (MDD), are the most prevalent psychiatric illnesses, and pose an incredible burden to society, both in terms of disability and in terms of costs associated with medical care and lost work time. MDD has extremely high rates of comorbidity with substance use disorders (SUD) as many of the same neurobiological circuits and molecular mechanisms regulate the reward pathways disrupted in both conditions. MDD may induce SUDs, SUD may contribute to MDD development, or underlying vulnerabilities and common life experience may confer risk to developing both conditions. In this chapter we explore theories of MDD and SUD comorbidity, the neurobiological underpinnings of depression, overlapping cellular and molecular pathways for both conditions, and current treatment approaches for these comorbid conditions.

Exposure to drugs of abuse induce effects that persist across generations

Substance use disorders are highly prevalent and continue to be one of the leading causes of disability in the world. Notably, not all people who use addictive drugs develop a substance use disorder. Although substance use disorders are highly heritable, patterns of inheritance cannot be explained purely by Mendelian genetic mechanisms. Vulnerability to developing drug addiction depends on the interplay between genetics and environment. Additionally, evidence from the past decade has pointed to the role of epigenetic inheritance in drug addiction. This emerging field focuses on how environmental perturbations, including exposure to addictive drugs, induce epigenetic modifications that are transmitted to the embryo at fertilization and modify developmental gene expression programs to ultimately impact subsequent generations. This chapter highlights intergenerational and transgenerational phenotypes in offspring following a history of parental drug exposure. Special attention is paid to parental preconception exposure studies of five drugs of abuse (alcohol, cocaine, nicotine, cannabinoids, and opiates) and associated behavioral and physiological outcomes in offspring. The highlighted studies demonstrate that parental exposure to drugs of abuse has enduring effects that persist into subsequent generations. Understanding the contribution of epigenetic inheritance in drug addiction may provide clues for better treatments and therapies for substance use disorders.

Monoamine and genome-wide DNA methylation investigation in behavioral addiction

Behavioral addiction (BA) is characterized by repeated, impulsive and compulsive seeking of specific behaviors, even with consequent negative outcomes. In drug addiction, alterations in biological mechanisms, such as monoamines and epigenetic processes, have been suggested, whereas whether such mechanisms are also altered in BA remains unknown. In this preliminary study with a small sample size, we investigated monoamine concentrations and genome-wide DNA methylation in blood samples from BA patients and control (CT) subjects. Higher dopamine (DA) metabolites and the ratio between DA and its metabolites were observed in the BA group than in the CT group, suggesting increased DA turnover in BA. In the methylation assay, 186 hyper- or hypomethylated CpGs were identified in the BA group compared to the CT group, of which 64 CpGs were further identified to correlate with methylation status in brain tissues with database search. Genes identified with hyper- or hypomethylation were not directly associated with DA transmission, but with cell membrane trafficking and the immune system. Some of the genes were also associated with psychiatric disorders, such as drug addiction, schizophrenia, and autism spectrum disorder. These results suggest that BA may involve alterations in epigenetic regulation of the genes associated with synaptic transmission, including that of monoamines, and neurodevelopment.

Effect of short-term prescription opioids on DNA methylation of the OPRM1 promoter

Background

A long-term opioid use has been associated with hypermethylation of the opioid receptor mu 1 (OPRM1) promoter. Very little is currently known about the early epigenetic response to therapeutic opioids. Here, we examine whether we can detect DNA methylation changes associated with a few days’ use of prescribed opioids. Genome-wide DNA methylation was assayed in a cohort of 33 opioid-naïve participants who underwent standard dental surgery followed by opioid self-administration. Saliva samples were collected before surgery (visit 1), and at two postsurgery visits at 2.7 ± 1.5 days (visit 2), and 39 ± 10 days (visit 3) after the discontinuation of opioid analgesics.

Results

The perioperative methylome underwent significant changes over the three visits that were primarily due to postoperative inflammatory response and cell heterogeneity. To specifically examine the effect of opioids, we started with a candidate gene approach and evaluated 10 CpGs located in the OPRM1 promoter. There was a significant cross-sectional variability in opioid use, and for participants who self-administered the prescribed drugs, the total dosage ranged from 5–210 morphine milligram equivalent (MME). Participants were categorized by cumulative dosage into three groups: < 25 MME, 25–90 MME, and ≥ 90 MME. Using mixed-effects modeling, 4 CpGs had significant positive associations with opioid dose at two-tailed p value < 0.05, and overall, 9 of the 10 OPRM1 promoter CpGs showed the predicted higher methylation in the higher dose groups relative to the lowest dose group. After adjustment for age, cellular heterogeneity, and past tobacco use, the promoter mean methylation also had positive associations with cumulative MME (regression coefficient = 0.0002, one-tailed p value = 0.02) and duration of opioid use (regression coefficient = 0.003, one-tailed p value = 0.001), but this effect was significant only for visit 3. A preliminary epigenome-wide association study identified a significant CpG in the promoter of the RAS-related signaling gene, RASL10A, that may be predictive of opioid dosage.

Conclusion

The present study provides evidence that the hypermethylation of the OPRM1 promoter is in response to opioid use and that epigenetic differences in OPRM1 and other sites are associated with a short-term use of therapeutic opioids.

Adversity profiles among court-involved youth: Translating system data into trauma-responsive programming

BACKGROUND

Court-involved youth have high levels of adverse childhood experiences (ACEs), which can impact functioning in adolescence and throughout adulthood. Yet there is limited research to help clinicians translate these histories into trauma-responsive programming guidelines.

OBJECTIVE

This manuscript utilizes data that is routinely collected to inform practitioners about how to utilize trauma histories to inform program and practice decisions.

METHODS

This study used administrative data with a diverse sample of medium- to high-risk youth on probation (N = 5,378) to examine how ACE clusters, identified through Latent Class Analysis, evinced differential treatment needs across multiple domains.

RESULTS

Six identified classes - Low All, Parental Incarceration, Parental Health Problems, High Conflict, High Maltreatment, and High All - were assessed for differences in self-regulation, mental health, substance use, academic functioning, family/social resources, and behavioral problems. Classes varied significantly on all assessed domains, indicating differential needs for effective interventions to interrupt negative trajectories.

CONCLUSIONS

Utilizing existing data in a real-world setting and addressing challenges and barriers in real-time can help bring research evidence to practice. In addition to juvenile justice settings, we conclude with discussion of ways that allied community based services in schools, youth programming, and family services can benefit from awareness of these youth adversity profiles.

The epigenetic modulation of alcohol/ethanol and cannabis exposure/co-exposure during different stages

Studies have reported the significant economic impact of smoking cannabis and drinking alcohol In the USA. It was estimated that the costs of cannabis-related treatment, hospitalization and loss of work-related pay have amounted to $200 billion. (Andersen AM, Dogan MV, Beach SRH, Philibert RA. 2015 Genes 6, 991-1022. ( doi:10.3390/genes6040991 )). Data from the National Epidemiologic Survey on Alcohol and Related Conditions showed that individuals with general anxiety disorder and substance use disorder (GAD-SUD) have higher psychiatric comorbidity rates than those without substance use disorder (Alegría AA, Hasin DS, Nunes EV, Liu SM, Davies C, Grant BF, Blanco C. 2010 J. Clin. Psychiatry 71, 1187-1195. ( doi:10.4088/JCP.09m05328gry )). Moreover, the criminal justice system is significantly impacted by this cost (Andersen AM, Dogan MV, Beach SRH, Philibert RA. 2015 Genes 6, 991-1022. ( doi:10.3390/genes6040991 )). Despite the increasing use of cannabis, there are still too many obscure facts. One of the new areas that scientific evidence shows is impacted negatively by cannabis use is the epigenome, which is an understudied area that we are still learning about. In addition, over the past few decades, we have seen various social and healthcare changes that have raised critical questions about their ongoing roles in regulating marijuana and alcohol use. This is important because of the increasing popularity and usage across various ages especially young adults and teenagers. More than 97.5 million Americans over 12 years old have used cannabis for non-medical use despite the significant side effects, with 1 in 10 users developing cannabis dependence (Crean RD, Crane NA, Mason BJ. 2011 J. Addict. Med. 5, 1-8. ( doi:10.1097/ADM.0b013e31820c23fa ), Office of Applied Studies. 2006 Substance Abuse and Mental Health Services Administration, USA.). It was reported that 16% of substance abuse admissions in the USA were for cannabis-related symptoms, which is second only to alcohol-related disorders (Agalioti T, Lomvardas S, Parekh B, Yie J, Maniatis T, Thanos D. 2000 Cell 103, 667-678. ( doi:10.1016/S0092-8674(00)00169-0 ), Soutoglou E, Talianidis I. 2002 Science 295, 1901-1904. ( doi:10.1126/science.1068356 )). Today there are thirty-one states and the District of Columbia that currently have legalized marijuana for either medical or recreational use. Data about marijuana use from NIAAA's National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) indicates that 'in total, 79 000 people were interviewed on alcohol and drug use. When examined by age young adults (ages 18-21) were found to be at highest risk for marijuana use and marijuana use disorder, with use increasing from 10.5 to 21.2% and disorder increasing from 4.4 to 7.5%'. 'Given these facts, George Koob, PhD, director of NIAAA stated the importance for the scientific community to convey this information to the public about the potential hazards of marijuana and it's use'. On the other hand, according to the National Institute on Alcohol Abuse and Alcoholism, 16 million adults suffer from alcohol use disorders. To the best of our knowledge, epigenetic mechanisms have been previously studied in alcohol and cannabis abuse separately. Recent studies highlighted the molecular mechanisms that are linked with drug-induced transcriptional regulation, behavioural abnormalities and neurodegeneration, which has emphasized the role of chromatin modification/remodelling in the generation of drug activation of certain genes and the disabling of others, and the effect of that on addiction (Maze I, Nestler EJ. 2011 Ann. N. Y. Acad. Sci. 1216, 99-113. ( doi:10.1111/j.1749-6632.2010.05893.x ); Renthal W, Nestler EJ. 2008 Trends Mol. Med. 14, 341-350. ( doi:10.1016/j.molmed.2008.06.004 )). In this review, we will give an overview of epigenome science relevant to cannabis/the endocannabinoid system and the potential of epigenetic overlap between alcohol and cannabinergic activity at different stages, to aid further investigations that could bring more treatment options to our horizon.

Attitudes of Psychiatry Residents in Canadian Universities toward Neuroscience and Its Implication in Psychiatric Practice

OBJECTIVE

Despite recent advances in neuroscience highlighting its potential applications in the assessment and treatment of psychiatric disorders, the training of psychiatrists in neuroscience is lacking. However, it is not clear to what extent Canadian trainees are interested in further learning and using neuroscience in their daily clinical practice. This study explored the attitudes of Canadian psychiatry trainees with regard to neuroscience education and training by asking them to assess their own understanding of neuroscience and the perceived relevance of neuroscience knowledge to effective psychiatric practice.

METHODS

An online questionnaire was sent to psychiatry residents at Canadian universities. This questionnaire consisted of self-assessments of neuroscience knowledge, attitudes toward neuroscience education, preferences in learning modalities, and interest in specific neuroscience topics.

RESULTS

One hundred and eleven psychiatry residents from psychiatry residency programs at Canadian universities responded to this survey. Participants represented trainees from all 5 years of residency. Almost half of all trainees (49.0%) reported their knowledge of neuroscience to be either "inadequate" or "less than adequate," and only 14.7% of trainees reported that they feel "comfortable" or "very comfortable" discussing neuroscience findings with their patients. 63.7% of Canadian trainees rated the quantity of neuroscience education in their residency program as either less than adequate or inadequate, and 46.1% rated the quality of their neuroscience education as "poor" or "very poor." The vast majority of participants (>70%) felt that additional neuroscience education would be moderately-to-hugely helpful in finding personalized treatments, discovering future treatments, destigmatizing patients with psychiatric illness, and understanding mental illness.

CONCLUSIONS

Canadian trainees generally feel that their neuroscience knowledge and the neuroscience education they receive during their psychiatry residencies is inadequate. However, as the first step for any change, the majority of future Canadian psychiatrists are very motivated and have a positive attitude toward neuroscience learning.

Transgenerational influence of parental morphine exposure on pain perception, anxiety-like behavior and passive avoidance memory among male and female offspring of Wistar rats

Accumulating evidence suggests that epigenetic mechanisms play an important role in the formation and maintenance of memory within the brain. Moreover, the effect of parental drug-exposure before gestation on behavioral state of offspring has been little studied. The main objective of the current study is to evaluate the effect of parental morphine exposure on avoidance memory, morphine preference and anxiety-like behavior of offspring. The total of 32 males and 32 females were used for mating. The animals were treated with morphine. The offspring according to their parental morphine treatment was divided into four groups (n=16) including paternally treated, maternally treated, both of parents treated and naïve animals. The pain perception, anxiety-like behavior, and avoidance memory were evaluated in the offspring. In the current study, the total of 256 offspring was used for the experiments (4 tasks × 4 groups of offspring × 8 female offspring × 8 male offspring). The finding revealed that the avoidance memory and visceral pain were reduced significantly in male and female offspring with at least one morphine-treated parent. Moreover, anxiety-like behavior was reduced significantly in the male offspring with at least one morphine-treated parent. While anxiety-like behavior was increased significantly in female offspring that were treated by morphine either maternally or both of parents. The data revealed that the endogenous opioid system may be altered in the offspring of morphine-treated parent(s), and epigenetic role could be important. However, analysis of variance signified the important role of maternal inheritance.

The epigenetic legacy of illicit drugs: developmental exposures and late-life phenotypes

The effects of in utero exposure to illicit drugs on adult offspring are a significant and widespread but understudied global health concern, particularly in light of the growing opioid epidemic and emerging therapeutic uses for cannabis, ketamine, and MDMA. Epigenetic mechanisms including DNA methylation, histone modifications, and expression of non-coding RNAs provide a mechanistic link between the prenatal environment and health consequences years beyond the original exposure, and shifts in the epigenome present in early life or adolescence can lead to disease states only appearing during adulthood. The current review summarizes the literature assessing effects of perinatal illicit drug exposure on adult disease phenotypes as mediated by perturbations of the epigenome. Both behavioral and somatic phenotypes are included and studies reporting clinical data in adult offspring, epigenetic readouts in offspring of any age, or both phenotypic and epigenetic measures are prioritized. Studies of licit substances of abuse (i.e. alcohol, nicotine) are excluded with a focus on cannabis, psychostimulants, opioids, and psychedelics; current issues in the field and areas of interest for further investigation are also discussed.

Racial association and pharmacotherapy in neonatal opioid withdrawal syndrome

OBJECTIVE

To determine if racial differences are associated with Neonatal Opioid Withdrawal Syndrome (NOWS) severity.

STUDY DESIGN

A 10-year (2008-2017) retrospective cohort of infants ≥35 weeks gestation with prenatal exposure to opioids was included. The primary measure was the need for pharmacotherapy. Multivariable logistic regression and propensity score analysis were performed.

RESULTS

Among 345 infants with NOWS, 111 (32%) were black infants with 70% of them requiring pharmacotherapy as compared with 84% of white infants. Upon adjusting for significant covariates (methadone, benzodiazepine use, and gestational age), black infants were 57% less likely than whites to require pharmacotherapy (Odds ratio: 0.43, 95%CI: 0.22-0.80, p = 0.009). Similar results were observed with propensity score analysis.

CONCLUSIONS

Significant racial disparity observed may be secondary to genetic variations in opioid pharmacogenomics and/or extrinsic factors. Large-scale studies are warranted to include race in predictive models for early pharmacological intervention.

Permisividad parental y diferencias de género en el consumo de alcohol en escolares

El consumo de alcohol en menores de edad representa un problema social y de salud pública de magnitud considerable. La investigación muestra que la familia es una instancia determinante del riesgo de consumo de sustancias por parte de niños, niñas y adolescentes. Existe evidencia acerca de que la familia puede incidir de manera diferencial de acuerdo con el género, en un contexto en que ha aumentado la proporción de mujeres que consumen sustancias, por lo que esta investigación indagó acerca de la permisividad familiar según el género, en 3064 estudiantes de colegios públicos de Bogotá D.C. Los análisis mostraron el peso de las variables relativas a la permisividad parental, particularmente en el inicio del consumo y en la favorabilidad al consumo de alcohol, en ambos géneros.

Who's your daddy? Behavioral and epigenetic consequences of paternal drug exposure

Substance use disorders (SUDs) reflect genetic and environmental factors. While identifying reliable genetic variants that predispose individuals to developing SUDs has been challenging, epigenetic factors may also contribute to the heritability of SUDs. Familial drug use associates with a wide range of problems in children, including an increased risk for developing a SUD. The implications of maternal drug use on offspring development are a well-studied area; however, paternal drug use prior to conception has received relatively little attention. Paternal exposure to several environmental stimuli (i.e. stress or diet manipulations) results in behavioral and epigenetic changes in offspring. The purpose of this review is to determine the state of the preclinical literature on the behavioral and epigenetic consequences of paternal drug exposure. Drug-sired offspring show several developmental and physiological abnormalities. These offspring also show deficits in cognitive and emotional domains. Examining sensitivity to drugs in offspring is a growing area of research. Drug-sired offspring are resistant to the rewarding and reinforcing properties of drugs. However, greater paternal motivation for the drug, combined with high drug intake, can result in addiction-like behaviors in offspring. Drug-sired offspring also show altered histone modifications and DNA methylation levels of imprinted genes and microRNAs; epigenetic-mediated changes were also noted in genes related to glutamatergic and neurotrophic factor signaling. In some instances, drug use resulted in aberrant epigenetic modifications in sire sperm, and these changes were maintained in the brains of offspring. Thus, paternal drug exposure has long-lasting consequences that include altered drug sensitivity in subsequent generations. We discuss factors (i.e. maternal behaviors) that may moderate these paternal drug-induced effects as well as ideas for future directions.

Maternal use of illicit drugs, tobacco or alcohol and the risk of childhood cancer before 6 years of age

BACKGROUND

Previous studies provide conflicting evidence of a link between maternal substance use and risk of childhood cancer.

METHODS

We analyzed a cohort of 785,438 newborns in Quebec (2006-2016). We identified infants whose mothers had problematic illicit drug, tobacco, or alcohol use before or during pregnancy. The primary outcomes were childhood hematopoietic cancer or solid tumors within 0-5 years of age. Using Cox proportional hazards models, we computed hazard ratios (HR) and 95% confidence intervals (CI) for the association between maternal substance use and childhood cancer, adjusted for potential confounders.

RESULTS

A total of 925 cases of cancer occurred during 3.5 million person-years of follow-up. Children exposed to any maternal substance use had marginally elevated cancer incidence rates compared with unexposed children (29.4 vs. 26.1 per 100,000 person-years). Maternal illicit drug use was associated with the risk of acute lymphoblastic leukemia (HR 1.63, 95% CI 0.79-3.36) and fibrosarcoma (HR 2.11, 95% CI 0.86-5.16). Maternal tobacco use was associated with acute myeloid leukemia (HR 2.01, 95% CI 0.72-5.60) and fibrosarcoma (HR 2.13, 95% CI 1.05-4.32), but a weak association with neuroblastoma (HR 1.21, 95% CI 0.61-2.40) and renal tumors (HR 1.14, 95% CI 0.42-3.13) also appeared to be present.

CONCLUSIONS

We found a potential association between maternal substance use and certain types of early childhood cancer. Although effects were modest, maternal substance use may contribute to some types of childhood cancer, especially leukemia and fibrosarcoma.

Association of status of acetylcholinesterase and ACHE gene 3' UTR variants (rs17228602, rs17228616) with drug addiction vulnerability in pakistani population

Substance addiction is a chronic, relapsing mental disorder Characterized by compulsive drug seeking, and loss of control over drug intake and relapse after prolonged abstinence. Genetics has been shown to contribute towards an individual's vulnerability to addiction. Acetylecholine (ACh), a cholinergic neurotransmitter hydrolyzed by acetylcholinesterase (AChE), is an essential neurotransmitter and neuromodulator in central and peripheral nervous system and has regulatory influence on numerous neuronal functions including addiction. The present study was carried out to investigate the role of acetylcholinesterase (AChE) in addiction through measurement of enzyme activity and to find potential association of ACHE gene 3'UTR variants rs17228602 and rs17228616 in heroin, hashish and poly drug addicts. Both SNPs are located within microRNA (miRNA) recognition sites with potential to affect miRNA/transcript interaction. A total of 122 addicts of heroin, hashish and polydrug were recruited from local rehabilitation centers to participate in this study. AChE activity was measured in blood by Ellman's method. SNP genotyping was performed by restriction fragment length polymorphism (PCR-RFLP) and Sanger sequencing. The AChE activity was found significantly higher (p ≤ 0.005) in addicted cohort (mean ± standard error of mean 0.020 ± 0.001 μmol/L/min; 95% confidence interval (CI) 0.018-0.022) in comparison to non-addicted healthy subjects (0.011 ± 0.001 μmol/L/min; 95% confidence interval CI 0.010-0.013). A statistically significant association of ACHE rs17228602 SNP with addiction vulnerability in dominant (DM: Odd's ratio OR = 2.095, 95% CI = 1.157-3.807 p = 0.009) and allelic genetic models (OR = 1.854 95% CI = 1.082-3.187, p = 0.016) was observed. However, no statistically significant association of rs17228616 SNP with substance abuse disorder was found. The data presented here shows that AChE could play significant role in substance addiction. Further studies with larger sample size and other variants of AChE are recommended to identify novel therapeutic approaches for cholinergic based treatment of addiction.

The genetics and epigenetics of Neonatal Abstinence Syndrome

Neonatal abstinence syndrome (NAS) due to in-utero opioid exposure is a growing epidemic with significant variability in clinical presentation and severity. Currently, NAS severity cannot be predicted based on clinical factors alone. To date, small studies have identified genetic variants in opioid receptor and stress response genes that are associated with differences in NAS pharmacologic treatment rates and length of hospitalization. In addition, epigenetic variation in the mu opioid receptor (OPRM1) gene has been associated with differences in NAS hospitalization outcomes. Examination of maternal genetic and epigenetic profiles may assist in prediction of NAS severity. Large-scale genomic studies are needed to elucidate the genetic architecture of and epigenetic modification related to NAS in order to develop more tailored personalized treatments for NAS.

Effects of nicotine and stress exposure across generations in C57BL/6 mice

Chronic administration of nicotine or exposure to stress can produce long-lasting behavioral and physiological changes in humans and animals alike. Further, the impact of nicotine and stress exposure can be inherited by offspring to produce persistent changes in physiology and behavior. To determine if nicotine and stress interact across generations to influence offspring behavior we exposed F0 male mice to nicotine and F1 male and female mice to chronic unpredictable stress during adolescence. We then measured locomotor sensitization to repeated nicotine injections in the subsequent F2 and F3 generations. Stress exposure alone (F1) did not influence locomotor sensitization in any lineage. However, in the F1 male lineage, F0 nicotine exposure abrogated locomotor sensitization in F2 male and transiently enhanced locomotor sensitization in F2 female offspring. These effects were not passed down to the F3 generations or observed in the F1 female lineage. F1 stress exposure modulated the effects of prior F0 nicotine exposure in a sex-dependent manner. Specifically, stress blunted the nicotine-induced enhancement in locomotor sensitization observed in F2 female offspring of F1 males. The effect of F0 nicotine and F1 stress exposure in females appears to have skipped a generation and enhanced nicotine sensitization only in the F3 generation, and only in females. This novel multigenerational exposure paradigm examining the inheritance of two different environmental exposures demonstrates that nicotine responses can be modified by nicotine and stress exposure from previous generations, and these effects are strongly influenced by sex.

Epigenetic Effects of Intravenous Diacetylmorphine on the Methylation of POMC and NR3C1

The administration of diacetylmorphine (DAM) reduces the activation of the hypothalamic-pituitary-adrenal (HPA) axis in opioid-maintained patients. However, the epigenetic effects of DAM on addiction-related genes have not been investigated yet. In a randomized controlled study, we examined the immediate effects of intravenous DAM versus placebo on the promoter methylation of the POMC (pro- opiomelanocortin) and NR3C1 (glucocorticoid receptor 1) genes. Twenty-eight heroin-dependent patients on DAM-assisted treatment received either DAM or saline in a randomized crossover design and 17 healthy participants received saline only. EDTA blood samples were taken 25 min before and 10 min after the injection of DAM or saline. We found reciprocal regulation effects for DAM versus saline application regarding the methylation of POMC; while DAM injection significantly increased methylation, saline injection led to a significant decrease in methylation for patients as well as controls. NR3C1 data did not show significant changes in methylation. Injection of DAM blunted stress hormone levels and the POMC promoter methylation of heroin-dependent patients. These findings provide first preliminary insights into the epigenetic mechanisms underlying the emotional regulation effects of DAM-assisted treatment in severe heroin-dependent patients.

Exposure to environmental enrichment attenuates addiction-like behavior and alters molecular effects of heroin self-administration in rats

Environmental factors profoundly affect the addictive potential of drugs of abuse and may also modulate the neuro-anatomical/neuro-chemical impacts of uncontrolled drug use and relapse propensity. This study examined the impact of environmental enrichment on heroin self-administration, addiction-related behaviors, and molecular processes proposed to underlie these behaviors. Male Sprague-Dawley rats in standard and enriched housing conditions intravenously self-administered similar amounts of heroin over 14 days. However, environmental enrichment attenuated progressive ratio, extinction, and reinstatement session responding after 14 days of enforced abstinence. Molecular mechanisms, namely DNA methylation and gene expression, are proposed to underlie abstinence-persistent behaviors. A global reduction in methylation is reported to coincide with addiction, but no differences in total genomic methylation or repeat element methylation were observed in CpG or non-CpG (CH) contexts across the mesolimbic circuitry as assessed by multiple methods including whole genome bisulfite sequencing. Immediate early gene expression associated with drug seeking, taking, and abstinence also were examined. EGR1 and EGR2 were suppressed in mesolimbic regions with heroin-taking and environmental enrichment. Site-specific methylation analysis of EGR1 and EGR2 promoter regions using bisulfite amplicon sequencing (BSAS) revealed hypo-methylation in the EGR2 promoter region and EGR1 intragenic CpG sites with heroin-taking and environmental enrichment that was associated with decreased mRNA expression. Taken together, these findings illuminate the impact of drug taking and environment on the epigenome in a locus and gene-specific manner and highlight the need for positive, alternative rewards in the treatment and prevention of drug addiction.

Apolipoprotein E DNA methylation and posttraumatic stress disorder are associated with plasma ApoE level: A preliminary study

Mild traumatic brain injury (mTBI) occurred in 15-30% of Veterans returning from Iraq and Afghanistan. We examined whether DNA methylation of the apolipoprotein E (APOE) gene promoter region or plasma ApoE protein levels are altered in mTBI. APOE promoter region DNA methylation, APOE genotype, and plasma ApoE concentration were determined in 87 Veterans with or without mTBI who were recruited from 2010-2014. Plasma ApoE concentration was found to be associated with Posttraumatic Stress Disorder (PTSD) symptom severity ratings by hierarchical linear regression (p = .013) and ANCOVA (p = .007). Hierarchical linear regression revealed that plasma ApoE concentration was associated with APOE-ε4 genotype status (p=.022). Higher ApoE plasma levels were found in ε3/ε3 Veterans than in APOE-ε4 carriers (p = .031). Furthermore, plasma ApoE concentration was associated experiment-wise with DNA methylation at CpG sites -877 (p = .021), and -775 (p = .014). The interaction between APOE-ε4 genotype and having a PTSD diagnosis was associated with DNA methylation at CpG site -675 (p = .009).

Opposite Epigenetic Associations With Alcohol Use and Exercise Intervention

Alcohol use disorder (AUD) is a devastating public health problem in which both genetic and environmental factors play a role. Growing evidence supports that epigenetic regulation is one major mechanism in neuroadaptation that contributes to development of AUD. Meanwhile, epigenetic patterns can be modified by various stimuli including exercise. Thus, it is an intriguing question whether exercise can lead to methylation changes that are opposite to those related to drinking. We herein conducted a comparative study to explore this issue. Three cohorts were profiled for DNA methylation (DNAm), including a longitudinal exercise intervention cohort (53 healthy participants profiled at baseline and after a 12-months exercise intervention), a cross-sectional case-control cohort (81 hazardous drinkers and 81 healthy controls matched in age and sex), and a cross-sectional binge drinking cohort (281 drinkers). We identified 906 methylation sites showing significant DNAm differences between drinkers and controls in the case-control cohort, as well as, associations with drinking behavior in the drinking cohort. In parallel, 341 sites were identified for significant DNAm alterations between baseline and follow-up in the exercise cohort. Thirty-two sites overlapped between these two set of findings, of which 15 sites showed opposite directions of DNAm associations between exercise and drinking. Annotated genes of these 15 sites were enriched in signaling pathways related to synaptic plasticity. In addition, the identified methylation sites significantly associated with impaired control over drinking, suggesting relevance to neural function. Collectively, the current findings provide preliminary evidence that exercise has the potential to partially reverse DNAm differences associated with drinking at some CpG sites, motivating rigorously designed longitudinal studies to better characterize epigenetic effects with respect to prevention and intervention of AUD.

Drug-seeking motivation level in male rats determines offspring susceptibility or resistance to cocaine-seeking behaviour

Liability to develop drug addiction is heritable, but the precise contribution of non-Mendelian factors is not well understood. Here we separate male rats into addiction-like and non-addiction-like groups, based on their incentive motivation to seek cocaine. We find that the high incentive responding of the F0 generation could be transmitted to F1 and F2 generations. Moreover, the inheritance of high incentive response to cocaine is contingent on high motivation, as it is elicited by voluntary cocaine administration, but not high intake of cocaine itself. We also find DNA methylation differences between sperm of addiction-like and non-addiction-like groups that were maintained from F0 to F1, providing an epigenetic link to transcriptomic changes of addiction-related signalling pathways in the nucleus accumbens of offspring. Our data suggest that highly motivated drug seeking experience may increase vulnerability and/or reduce resistance to drug addiction in descendants.

Drug addiction is partially heritable but the non-genetic inheritance mechanisms are not well understood. The authors show that motivation of male rats in response to cocaine self-administration elicit susceptibility and/or decreased resistance to developing addiction like behaviour in offspring.