CB1R-Mediated Activation of Caspase-3 Causes Epigenetic and Neurobehavioral Abnormalities in Postnatal Ethanol-Exposed Mice

Relationship between apoptosis gene DNA methylation and fetal growth and development

OBJECTIVE

To investigate the relationship between DNA methylation of cord blood apoptosis genes and low birth weight (LBW).

METHODS

A case-control study was conducted on 50 pairs of LBW neonates and normal birth weight. Genome-wide methylation assay was performed using Illumina Human Methylation EPIC microarray to analyze the methylation sites of apoptosis-related genes BCL-2, CASP3, and CASP8. The mRNA level of apoptosis gene was verified by RT-qPCR.

RESULTS

Three CpG sites of BCL-2 and three CpG sites of CASP3 were different between the LBW and NBW groups. Logistic regression showed that higher methylation of BCL-2 CpG sites cg12459502 (OR = 1.208, 95% CI:1.029, 1.418) and cg25059899 (OR = 1.193, 95% CI:1.019, 1.395) increased LBW risk, while cg22152050 was protective (OR = 0.589, 95% CI:0.424, 0.820). Stratified analysis confirmed this. Maternal pre-pregnancy BMI positively correlated with BCL-2 methylation (cg12459502, cg25059899) (b = 0.431, 95% CI: 0.027, 0.835; b = 0.494, 95% CI: 0.141, 0.848), while excessive pregnancy weight gain negatively correlated with cg12459502 methylation (b = -0.269, 95% CI: -0.525, -0.013). The results showed that the mRNA level of BCL-2 in NBW group was significantly higher than that in LBW group (P-value < 0.0001).

CONCLUSION

The DNA methylation levels of BCL-2 and CASP3 genes are associated with fetal growth and development. Additionally, maternal pre-pregnancy BMI and weight gain during pregnancy were found to correlate with BCL-2 methylation, indicating potential epigenetic mechanisms influencing fetal growth.

Death and survival from executioner caspase activation

Executioner caspases are evolutionarily conserved regulators of cell death under apoptotic stress. Activated executioner caspases drive apoptotic cell death through cleavage of diverse protein substrates or pyroptotic cell death in the presence of gasdermin E. On the other hand, activation of executioner caspases can also trigger pro-survival and pro-proliferation signals. In recent years, a growing body of studies have demonstrated that cells can survive from executioner caspase activation in response to stress and that the survivors undergo molecular and phenotypic alterations. This review focuses on death and survival from executioner caspase activation, summarizing the role of executioner caspases in apoptotic and pyroptotic cell death and discussing the potential mechanism and consequences of survival from stress-induced executioner caspase activation.

Perturbation of 3D nuclear architecture, epigenomic dysregulation and aging, and cannabinoid synaptopathy reconfigures conceptualization of cannabinoid pathophysiology: part 1-aging and epigenomics

Much recent attention has been directed toward the spatial organization of the cell nucleus and the manner in which three-dimensional topologically associated domains and transcription factories are epigenetically coordinated to precisely bring enhancers into close proximity with promoters to control gene expression. Twenty lines of evidence robustly implicate cannabinoid exposure with accelerated organismal and cellular aging. Aging has recently been shown to be caused by increased DNA breaks. These breaks rearrange and maldistribute the epigenomic machinery to weaken and reverse cellular differentiation, cause genome-wide DNA demethylation, reduce gene transcription, and lead to the inhibition of developmental pathways, which contribute to the progressive loss of function and chronic immune stimulation that characterize cellular aging. Both cell lineage-defining superenhancers and the superanchors that control them are weakened. Cannabis exposure phenocopies the elements of this process and reproduces DNA and chromatin breakages, reduces the DNA, RNA protein and histone synthesis, interferes with the epigenomic machinery controlling both DNA and histone modifications, induces general DNA hypomethylation, and epigenomically disrupts both the critical boundary elements and the cohesin motors that create chromatin loops. This pattern of widespread interference with developmental programs and relative cellular dedifferentiation (which is pro-oncogenic) is reinforced by cannabinoid impairment of intermediate metabolism (which locks in the stem cell-like hyper-replicative state) and cannabinoid immune stimulation (which perpetuates and increases aging and senescence programs, DNA damage, DNA hypomethylation, genomic instability, and oncogenesis), which together account for the diverse pattern of teratologic and carcinogenic outcomes reported in recent large epidemiologic studies in Europe, the USA, and elsewhere. It also accounts for the prominent aging phenotype observed clinically in long-term cannabis use disorder and the 20 characteristics of aging that it manifests. Increasing daily cannabis use, increasing use in pregnancy, and exponential dose-response effects heighten the epidemiologic and clinical urgency of these findings. Together, these findings indicate that cannabinoid genotoxicity and epigenotoxicity are prominent features of cannabis dependence and strongly indicate coordinated multiomics investigations of cannabinoid genome-epigenome-transcriptome-metabolome, chromatin conformation, and 3D nuclear architecture. Considering the well-established exponential dose-response relationships, the diversity of cannabinoids, and the multigenerational nature of the implications, great caution is warranted in community cannabinoid penetration.

Endocannabinoid signaling and epigenetics modifications in the neurobiology of stress-related disorders

Stress exposure is associated with psychiatric conditions, such as depression, anxiety, and post-traumatic stress disorder (PTSD). It is also a vulnerability factor to developing or reinstating substance use disorder. Stress causes several changes in the neuro-immune-endocrine axis, potentially resulting in prolonged dysfunction and diseases. Changes in several transmitters, including serotonin, dopamine, glutamate, gamma-aminobutyric acid (GABA), glucocorticoids, and cytokines, are associated with psychiatric disorders or behavioral alterations in preclinical studies. Complex and interacting mechanisms make it very difficult to understand the physiopathology of psychiatry conditions; therefore, studying regulatory mechanisms that impact these alterations is a good approach. In the last decades, the impact of stress on biology through epigenetic markers, which directly impact gene expression, is under intense investigation; these mechanisms are associated with behavioral alterations in animal models after stress or drug exposure, for example. The endocannabinoid (eCB) system modulates stress response, reward circuits, and other physiological functions, including hypothalamus-pituitary-adrenal axis activation and immune response. eCBs, for example, act retrogradely at presynaptic neurons, limiting the release of neurotransmitters, a mechanism implicated in the antidepressant and anxiolytic effects after stress. Epigenetic mechanisms can impact the expression of eCB system molecules, which in turn can regulate epigenetic mechanisms. This review will present evidence of how the eCB system and epigenetic mechanisms interact and the consequences of this interaction in modulating behavioral changes after stress exposure in preclinical studies or psychiatric conditions. Moreover, evidence that correlates the involvement of the eCB system and epigenetic mechanisms in drug abuse contexts will be discussed.

Chemotherapy-induced executioner caspase activation increases breast cancer malignancy through epigenetic de-repression of CDH12

Cancer relapse and metastasis are major obstacles for effective treatment. One important mechanism to eliminate cancer cells is to induce apoptosis. Activation of executioner caspases is the key step in apoptosis and was considered "a point of no return". However, in recent years, accumulating evidence has demonstrated that cells can survive executioner caspase activation in response to apoptotic stimuli through a process named anastasis. Here we show that breast cancer cells that have survived through anastasis (anastatic cells) after exposure to chemotherapeutic drugs acquire enhanced proliferation and migration. Mechanistically, cadherin 12 (CDH12) is persistently upregulated in anastatic cells and promotes breast cancer malignancy via activation of ERK and CREB. Moreover, we demonstrate that executioner caspase activation induced by chemotherapeutic drugs results in loss of DNA methylation and repressive histone modifications in the CDH12 promoter region, leading to increased CDH12 expression. Our work unveils the mechanism underlying anastasis-induced enhancement in breast cancer malignancy, offering new therapeutic targets for preventing post-chemotherapy cancer relapse and metastasis.

Postnatal ethanol exposure impairs social behavior and operant extinction in the adult female mouse offspring

Fetal Alcohol Spectrum Disorder (FASD) comprises a group of neurodevelopmental deficits caused by alcohol exposure during pregnancy. Clinical studies suggest that while the male progeny experiences serious neurodevelopmental defects, female patients have more severe cognitive, social, and affective symptoms. Other than sex, dose, frequency, and timing of exposure determine the neurobehavioral outcomes in young and adult progeny. In this regard, human studies indicate that some individuals relapse during late-term gestational periods. In mice, this interval corresponds to the first 10 days after birth (postnatal, P0-P10). In our model of postnatal ethanol exposure (PEE^P0-P10), we tested whether adult female and male offspring show deficits in sociability, anxiety-like, reward consumption, and action-outcome associations. We report that female PEE^P0-P10 offspring have mild social impairments and altered extinction of operant responding in the absence of anxiety-like traits and reward consumption defects. None of these deficits were detected in the male PEE^P0-P10 offspring. Our data provide novel information on sex-specific neurobehavioral outcomes of postnatal ethanol exposure in female adult offspring.

Anastasis confers ovarian cancer cells increased malignancy through elevated p38 MAPK activation

Activation of executioner caspases was once considered as a point of no return in apoptosis. However, in recent years, accumulating evidence has demonstrated that cells can survive executioner caspase activation in response to apoptotic stimuli through a process called anastasis. In this study, we developed a reporter system, mCasExpress, to track mammalian cells that survive executioner caspase activation. We demonstrate that anastatic ovarian cancer cells acquire enhanced migration following their transient exposure to apoptotic stimulus TRAIL or Paclitaxel. Moreover, anastatic cancer cells secrete more pro-angiogenic factors that enable tumor angiogenesis, growth and metastasis. Mechanistically, we demonstrate that activation of p38 MAPK, which occurs in a caspase-dependent manner in response to apoptotic stress to promote anastasis, persists at a higher level in anastatic cancer cells even after removal of apoptotic stimuli. Importantly, p38 is essential for the elevated migratory and angiogenic capacity in the anastatic cells. Our work unveils anastasis as a potential driver of tumor angiogenesis and metastasis.

Patterns of Cannabis- and Substance-Related Congenital General Anomalies in Europe: A Geospatiotemporal and Causal Inferential Study

INTRODUCTION

Recent series of congenital anomaly (CA) rates (CARs) have showed the close and epidemiologically causal relationship of cannabis exposure to many CARs. We investigated these trends in Europe where similar trends have occurred.

METHODS

CARs from EUROCAT. Drug use from European Monitoring Centre for Drugs and Drug Addiction. Income data from World Bank.

RESULTS

CARs were higher in countries with increasing daily use overall (p = 9.99 × 10-14, minimum E-value (mEV) = 2.09) and especially for maternal infections, situs inversus, teratogenic syndromes and VACTERL syndrome (p = 1.49 × 10-15, mEV = 3.04). In inverse probability weighted panel regression models the series of anomalies: all anomalies, VACTERL, foetal alcohol syndrome, situs inversus (SI), lateralization (L), and teratogenic syndromes (TS; AAVFASSILTS) had cannabis metric p-values from: p < 2.2 × 10-16, 1.52 × 10-12, 1.44 × 10-13, 1.88 × 10-7, 7.39 × 10-6 and <2.2 × 10-16. In a series of spatiotemporal models this anomaly series had cannabis metric p-values from: 8.96 × 10-6, 6.56 × 10-6, 0.0004, 0.0019, 0.0006, 5.65 × 10-5. Considering E-values, the cannabis effect size order was VACTERL > situs inversus > teratogenic syndromes > FAS > lateralization syndromes > all anomalies. 50/64 (78.1%) E-value estimates and 42/64 (65.6%) mEVs > 9. Daily cannabis use was the strongest predictor for all anomalies.

CONCLUSION

Data confirmed laboratory, preclinical and recent epidemiological studies from Canada, Australia, Hawaii, Colorado and USA for teratological links between cannabis exposure and AAVFASSILTS anomalies, fulfilled epidemiological criteria for causality and underscored importance of cannabis teratogenicity. VACTERL data are consistent with causation via cannabis-induced Sonic Hedgehog inhibition. TS data suggest cannabinoid contribution. SI&L data are consistent with results for cardiovascular CAs. Overall, these data show that cannabis is linked across space and time and in a manner which fulfills epidemiological criteria for causality not only with many CAs, but with several multiorgan teratologic syndromes. The major clinical implication of these results is that access to cannabinoids should be tightly restricted in the interests of safeguarding the community's genetic heritage to protect and preserve coming generations, as is done for all other major genotoxins.

Synaptic Plasticity Abnormalities in Fetal Alcohol Spectrum Disorders

The brain's ability to strengthen or weaken synaptic connections is often termed synaptic plasticity. It has been shown to function in brain remodeling following different types of brain damage (e.g., drugs of abuse, alcohol use disorders, neurodegenerative diseases, and inflammatory conditions). Although synaptic plasticity mechanisms have been extensively studied, how neural plasticity can influence neurobehavioral abnormalities in alcohol use disorders (AUDs) is far from being completely understood. Alcohol use during pregnancy and its harmful effects on the developing offspring are major public health, social, and economic challenges. The significant attribute of prenatal alcohol exposure on offspring is damage to the central nervous system (CNS), causing a range of synaptic structural, functional, and behavioral impairments, collectively called fetal alcohol spectrum disorder (FASD). Although the synaptic mechanisms in FASD are limited, emerging evidence suggests that FASD pathogenesis involves altering a set of molecules involved in neurotransmission, myelination, and neuroinflammation. These studies identify several immediate and long-lasting changes using many molecular approaches that are essential for synaptic plasticity and cognitive function. Therefore, they can offer potential synaptic targets for the many neurobehavioral abnormalities observed in FASD. In this review, we discuss the substantial research progress in different aspects of synaptic and molecular changes that can shed light on the mechanism of synaptic dysfunction in FASD. Increasing our understanding of the synaptic changes in FASD will significantly advance our knowledge and could provide a basis for finding novel therapeutic targets and innovative treatment strategies.

Epigenetics in fetal alcohol spectrum disorder

During pregnancy, alcohol abuse and its detrimental effects on developing offspring are major public health, economic and social challenges. The prominent characteristic attributes of alcohol (ethanol) abuse during pregnancy in humans are neurobehavioral impairments in offspring due to damage to the central nervous system (CNS), causing structural and behavioral impairments that are together named fetal alcohol spectrum disorder (FASD). Development-specific alcohol exposure paradigms were established to recapitulate the human FASD phenotypes and establish the underlying mechanisms. These animal studies have offered some critical molecular and cellular underpinnings likely to account for the neurobehavioral impairments associated with prenatal ethanol exposure. Although the pathogenesis of FASD remains unclear, emerging literature proposes that the various genomic and epigenetic components that cause the imbalance in gene expression can significantly contribute to the development of this disease. These studies acknowledged numerous immediate and enduring epigenetic modifications, such as methylation of DNA, post-translational modifications (PTMs) of histone proteins, and regulatory networks related to RNA, using many molecular approaches. Methylated DNA profiles, PTMs of histone proteins, and RNA-regulated expression of genes are essential for synaptic and cognitive behavior. Thus, offering a solution to many neuronal and behavioral impairments reported in FASD. In the current chapter, we review the recent advances in different epigenetic modifications that cause the pathogenesis of FASD. The information discussed can help better explain the pathogenesis of FASD and thereby might provide a basis for finding novel therapeutic targets and innovative treatment strategies.

Epigenomic and Other Evidence for Cannabis-Induced Aging Contextualized in a Synthetic Epidemiologic Overview of Cannabinoid-Related Teratogenesis and Cannabinoid-Related Carcinogenesis

BACKGROUND

Twelve separate streams of empirical data make a strong case for cannabis-induced accelerated aging including hormonal, mitochondriopathic, cardiovascular, hepatotoxic, immunological, genotoxic, epigenotoxic, disruption of chromosomal physiology, congenital anomalies, cancers including inheritable tumorigenesis, telomerase inhibition and elevated mortality.

METHODS

Results from a recently published longitudinal epigenomic screen were analyzed with regard to the results of recent large epidemiological studies of the causal impacts of cannabis. We also integrate theoretical syntheses with prior studies into these combined epigenomic and epidemiological results.

RESULTS

Cannabis dependence not only recapitulates many of the key features of aging, but is characterized by both age-defining and age-generating illnesses including immunomodulation, hepatic inflammation, many psychiatric syndromes with a neuroinflammatory basis, genotoxicity and epigenotoxicity. DNA breaks, chromosomal breakage-fusion-bridge morphologies and likely cycles, and altered intergenerational DNA methylation and disruption of both the histone and tubulin codes in the context of increased clinical congenital anomalies, cancers and heritable tumors imply widespread disruption of the genome and epigenome. Modern epigenomic clocks indicate that, in cannabis-dependent patients, cannabis advances cellular DNA methylation age by 25-30% at age 30 years. Data have implications not only for somatic but also stem cell and germ line tissues including post-fertilization zygotes. This effect is likely increases with the square of chronological age.

CONCLUSION

Recent epigenomic studies of cannabis exposure provide many explanations for the broad spectrum of cannabis-related teratogenicity and carcinogenicity and appear to account for many epidemiologically observed findings. Further research is indicated on the role of cannabinoids in the aging process both developmentally and longitudinally, from stem cell to germ cell to blastocystoids to embryoid bodies and beyond.

Molecular Insights into Epigenetics and Cannabinoid Receptors

The actions of cannabis are mediated by G protein-coupled receptors that are part of an endogenous cannabinoid system (ECS). ECS consists of the naturally occurring ligands N-arachidonylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG), their biosynthetic and degradative enzymes, and the CB1 and CB2 cannabinoid receptors. Epigenetics are heritable changes that affect gene expression without changing the DNA sequence, transducing external stimuli in stable alterations of the DNA or chromatin structure. Cannabinoid receptors are crucial candidates for exploring their functions through epigenetic approaches due to their significant roles in health and diseases. Epigenetic changes usually promote alterations in the expression of genes and proteins that can be evaluated by various transcriptomic and proteomic analyses. Despite the exponential growth of new evidence on the critical functions of cannabinoid receptors, much is still unknown regarding the contribution of various genetic and epigenetic factors that regulate cannabinoid receptor gene expression. Recent studies have identified several immediate and long-lasting epigenetic changes, such as DNA methylation, DNA-associated histone proteins, and RNA regulatory networks, in cannabinoid receptor function. Thus, they can offer solutions to many cellular, molecular, and behavioral impairments found after modulation of cannabinoid receptor activities. In this review, we discuss the significant research advances in different epigenetic factors contributing to the regulation of cannabinoid receptors and their functions under both physiological and pathological conditions. Increasing our understanding of the epigenetics of cannabinoid receptors will significantly advance our knowledge and could lead to the identification of novel therapeutic targets and innovative treatment strategies for diseases associated with altered cannabinoid receptor functions.

Binge-like Prenatal Ethanol Exposure Causes Impaired Cellular Differentiation in the Embryonic Forebrain and Synaptic and Behavioral Defects in Adult Mice

An embryo’s in-utero exposure to ethanol due to a mother’s alcohol drinking results in a range of deficits in the child that are collectively termed fetal alcohol spectrum disorders (FASDs). Prenatal ethanol exposure is one of the leading causes of preventable intellectual disability. Its neurobehavioral underpinnings warrant systematic research. We investigated the immediate effects on embryos of acute prenatal ethanol exposure during gestational days (GDs) and the influence of such exposure on persistent neurobehavioral deficits in adult offspring. We administered pregnant C57BL/6J mice with ethanol (1.75 g/kg) (GDE) or saline (GDS) intraperitoneally (i.p.) at 0 h and again at 2 h intervals on GD 8 and GD 12. Subsequently, we assessed apoptosis, differentiation, and signaling events in embryo forebrains (E13.5; GD13.5). Long-lasting effects of GDE were evaluated via a behavioral test battery. We also determined the long-term potentiation and synaptic plasticity-related protein expression in adult hippocampal tissue. GDE caused apoptosis, inhibited differentiation, and reduced pERK and pCREB signaling and the expression of transcription factors Pax6 and Lhx2. GDE caused persistent spatial and social investigation memory deficits compared with saline controls, regardless of sex. Interestingly, GDE adult mice exhibited enhanced repetitive and anxiety-like behavior, irrespective of sex. GDE reduced synaptic plasticity-related protein expression and caused hippocampal synaptic plasticity (LTP and LTD) deficits in adult offspring. These findings demonstrate that binge-like ethanol exposure at the GD8 and GD12 developmental stages causes defects in pERK–pCREB signaling and reduces the expression of Pax6 and Lhx2, leading to impaired cellular differentiation during the embryonic stage. In the adult stage, binge-like ethanol exposure caused persistent synaptic and behavioral abnormalities in adult mice. Furthermore, the findings suggest that combining ethanol exposure at two sensitive stages (GD8 and GD12) causes deficits in synaptic plasticity-associated proteins (Arc, Egr1, Fgf1, GluR1, and GluN1), leading to persistent FASD-like neurobehavioral deficits in mice.

Geospatiotemporal and causal inference study of cannabis and other drugs as risk factors for female breast cancer USA 2003-2017

Breast cancer (BC) is the commonest human cancer and its incidence (BC incidence, BCI) is rising worldwide. Whilst both tobacco and alcohol have been linked to BCI genotoxic cannabinoids have not been investigated. Age-adjusted state-based BCI 2003-2017 was taken from the Surveillance Epidemiology and End Results database of the Centers for Disease Control. Drug use from the National Survey of Drug Use and Health, response rate 74.1%. Median age, median household income and ethnicity were from US census. Inverse probability weighted (ipw) multivariable regression conducted in R. In bivariate analysis BCI was shown to be significantly linked with rising cannabis exposure {β-est. = 3.93 [95% confidence interval 2.99, 4.87], P = 1.10 × 10-15}. At 8 years lag cigarettes:cannabis [β-est. = 2660 (2150.4, 3169.3), P = 4.60 × 10-22] and cannabis:alcoholism [β-est. = 7010 (5461.6, 8558.4), P = 1.80 × 10-17] were significant in ipw-panel regression. Terms including cannabidiol [CBD; β-est. = 16.16 (0.39, 31.93), P = 0.446] and cannabigerol [CBG; β-est. = 6.23 (2.06, 10.39), P = 0.0034] were significant in spatiotemporal models lagged 1:2 years, respectively. Cannabis-liberal paradigms had higher BCI [67.50 ± 0.26 v. 65.19 ± 0.21/100 000 (mean ± SEM), P = 1.87 × 10-11; β-est. = 2.31 (1.65, 2.96), P = 9.09 × 10-12]. 55/58 expected values >1.25 and 13/58 >100. Abortion was independently and causally significant in space-time models. Data show that exposure to cannabis and the cannabinoids Δ9-tetrahydrocannabinol, CBD, CBG and alcoholism fulfil quantitative causal criteria for BCI across space and time. Findings are robust to adjustment for age and several known sociodemographic, socio-economic and hormonal risk factors and establish cannabinoids as an additional risk factor class for breast carcinogenesis. BCI is higher under cannabis-liberal legal paradigms.

Cannabinoid and substance relationships of European congenital anomaly patterns: a space-time panel regression and causal inferential study

With reports from Australia, Canada, USA, Hawaii and Colorado documenting a link between cannabis and congenital anomalies (CAs), this relationship was investigated in Europe. Data on 90 CAs were accessed from Eurocat. Tobacco and alcohol consumption and median household income data were from the World Bank. Amphetamine, cocaine and last month and daily use of cannabis from the European Monitoring Centre for Drugs and Drug Addiction. Cannabis herb and resin Δ9-tetrahydrocannabinol concentrations were from published reports. Data were processed in R. Twelve thousand three hundred sixty CA rates were sourced across 16 nations of Europe. Nations with a higher or increasing rate of daily cannabis use had a 71.77% higher median CA rates than others [median ± interquartile range 2.13 (0.59, 6.30) v. 1.24 (0.15, 5.14)/10 000 live births (P = 4.74 × 10^-17; minimum E-value (mEV) = 1.52]. Eighty-nine out of 90 CAs in bivariate association and 74/90 CAs in additive panel inverse probability weighted space-time regression were cannabis related. In inverse probability weighted interactive panel models lagged to zero, two, four and six years, 76, 31, 50 and 29 CAs had elevated mEVs (< 2.46 × 10³⁹) for cannabis metrics. Cardiovascular, central nervous, gastrointestinal, genital, uronephrology, limb, face and chromosomalgenetic systems along with the multisystem VACTERL syndrome were particularly vulnerable targets. Data reveal that cannabis is related to many CAs and fulfil epidemiological criteria of causality. The triple convergence of rising cannabis use prevalence, intensity of daily use and Δ9-tetrahydrocannabinol concentration in herb and resin is powerfully implicated as a primary driver of European teratogenicity, confirming results from elsewhere.

A possible neuroprotective property of ethanol and/or NeuroAiD on the modulation of cognitive function

Cognitive impairments and poor performance on tasks needing behavioral flexibility are observable in chronic alcohol exposure. NeuroAid decreases cognitive deficits and improves functional outcomes by restoring neuronal circuits. The aim of the current study was to assess the hypothesis that ethanol exposure would induce neurobehavioral defects which may be reversed by the neuroprotective property of NeuroAid. Adult male Wistar rats were treated with saline, ethanol (0.2 g/kg), NeuroAid (0.8 g/kg) and ethanol (0.2 g/kg) + NeuroAid (0.8 g/kg). Then, behavioral tests were performed using the Y-maze apparatus, hot-plate and tail-flick apparatuses, locomotion apparatus as well as the loss of righting reflex (LORR) and hanging protocols (performance in a wire hanging test). Our results indicated that intraperitoneal (i.p.) administration of ethanol alone and administration of ethanol along with NeuroAid for one week reversed ethanol-induced spatial memory deficits in rats (P < 0.01). Interestingly, treatment with ethanol (0.2 g/kg) for one week induced nociception (P < 0.01). Moreover, one week administration of ethanol (0.2 g/kg) along with NeuroAid (0.8 g/kg) increased latency to LORR (P < 0.001) while four weeks administration of ethanol (0.2 g/kg) along with NeuroAid (0.8 g/kg) decreased sleep time (P < 0.01). In addition, a single administration of all drugs did not alter locomotor activity (P > 0.05) and hanging (P > 0.05). Improvement of behavioral tasks after one-week i.p. administration of ethanol and/or NeuroAid in comparison with a single administration of ethanol and/or NeuroAid may be due to the neuroprotective property of ethanol and/or NeuroAiD.

Postnatal Ethanol-Induced Neurodegeneration Involves CB1R-Mediated β-Catenin Degradation in Neonatal Mice

Alcohol consumption by pregnant women may produce neurological abnormalities that affect cognitive processes in children and are together defined as fetal alcohol spectrum disorders (FASDs). However, the molecular underpinnings are still poorly defined. In our earlier studies, we found that ethanol exposure of postnatal day 7 (P7) mice significantly induced widespread neurodegeneration mediated via endocannabinoids (eCBs)/cannabinoid receptor type 1 (CB1R). In the current study, we examined changes in the β-catenin protein levels that are involved in the regulation of neuronal function including neuronal death and survival. We found that moderate- and high-dose postnatal ethanol exposure (PEE) significantly reduced active-β-catenin (ABC) (non-phosphorylated form) protein levels in the hippocampus (HP) and neocortex (NC). In addition, we found that moderate- and high-dose PEE significantly increased the phosphorylated-β-catenin (p-β-catenin)/ABC ratios in the HP and NC. Antagonism/null mutation of CB1R before PEE to inhibit CC3 production mitigated the loss of ABC protein levels. Collectively, these findings demonstrated that the CB1R/β-catenin signaling mechanism causes neurodegeneration in neonatal mouse brains following PEE.

Postnatal Ethanol Exposure Activates HDAC-Mediated Histone Deacetylation, Impairs Synaptic Plasticity Gene Expression and Behavior in Mice

BACKGROUND

Alcohol consumption during pregnancy is widespread and contributes to pediatric neurological defects, including hippocampal and neocortex dysfunction, causing cognitive deficits termed fetal alcohol spectrum disorders. However, the critical mechanisms underlying these brain abnormalities remain poorly described.

METHODS

Using a postnatal ethanol exposure (PEE) animal model and pharmacological, epigenetic, synaptic plasticity-related and behavioral approaches, we discovered a novel persistent epigenetic mechanism of neurodegeneration in neonatal hippocampus and neocortex brain regions and of cognitive decline in adult animals.

RESULTS

PEE, which activates caspase-3 (CC3, a neurodegeneration marker), enhanced histone deacetylase (HDAC1-HDAC3) levels and reduced histone 3 (H3) and 4 (H4) acetylation (ac) in mature neurons. PEE repressed the expression of several synaptic plasticity genes, such as brain-derived neurotrophic factor, C-Fos, early growth response 1 (Egr1), and activity-regulated cytoskeleton-associated protein (Arc). Detailed studies on Egr1 and Arc expression revealed HDAC enrichment at their promoter regions. HDAC inhibition with trichostatin A (TSA) before PEE rescued H3ac/H4ac levels and prevented CC3 formation. Antagonism/null mutation of cannabinoid receptor type-1 (CB1R) before PEE to inhibit CC3 production prevented Egr1 and Arc loss via epigenetic events. TSA administration before PEE prevented postnatal ethanol-induced loss of Egr1 and Arc expression and neurobehavioral defects in adult mice via epigenetic remodeling. In adult mice, 3-day TSA administration attenuated PEE-induced behavioral defects.

CONCLUSIONS

These findings demonstrate that CB1R/HDAC-mediated epigenetic remodeling disrupts gene expression and is a critical step in fetal alcohol spectrum disorder-associated cognitive decline but is reversed by restoration of histone acetylation in the brain.

Early Postnatal Ethanol Exposure in Mice Induces Sex-Dependent Memory Impairment and Reduction of Hippocampal NMDA-R2B Expression in Adulthood

Drinking alcohol during pregnancy is particularly detrimental for the developing brain and may cause a broad spectrum of cognitive and behavioral impairments, collectively known as fetal alcohol spectrum disorder (FASD). While behavioral abnormalities and brain damage have been widely investigated in animal models of FASD, the sex differences in the vulnerability to perinatal ethanol exposure have received less consideration. Here we investigated the long-term behavioral and molecular effects of acute ethanol-binge like exposure during the early postnatal period (equivalent to the third trimester of human pregnancy) in adult male and female mice. CD1 mice received a single ethanol exposure on P7 and were analyzed starting from P60. We found that ethanol-exposed mice showed increased activity in the open field test and in the plus-maze test, regardless of the sex. Interestingly, only ethanol-exposed adult male mice exhibited memory impairment in the water maze and fear-conditioning tests. Remarkably, hippocampal levels of NMDA-R2B were reduced only in ethanol-exposed male, while total BDNF levels were increased in both male and female ethanol-exposed mice. Our data suggest a different susceptibility of early postnatal ethanol exposure in male and female CD1 mice.

Distinct functions of endogenous cannabinoid system in alcohol abuse disorders

Δ⁹ -tetrahydrocannabinol, the principal active component in Cannabis sativa extracts such as marijuana, participates in cell signalling by binding to cannabinoid CB₁ and CB₂ receptors on the cell surface. The CB₁ receptors are present in both inhibitory and excitatory presynaptic terminals and the CB₂ receptors are found in neuronal subpopulations in addition to microglial cells and astrocytes and are present in both presynaptic and postsynaptic terminals. Subsequent to the discovery of the endocannabinoid (eCB) system, studies have suggested that alcohol alters the eCB system and that this system plays a major role in the motivation to abuse alcohol. Preclinical studies have provided evidence that chronic alcohol consumption modulates eCBs and expression of CB₁ receptors in brain addiction circuits. In addition, studies have further established the distinct function of the eCB system in the development of fetal alcohol spectrum disorders. This review provides a recent and comprehensive assessment of the literature related to the function of the eCB system in alcohol abuse disorders.

Impacts of cannabinoid epigenetics on human development: reflections on Murphy et. al. 'cannabinoid exposure and altered DNA methylation in rat and human sperm' epigenetics 2018; 13: 1208-1221

Recent data from the Kollins lab (‘Cannabinoid exposure and altered DNA methylation in rat and human sperm’ Epigenetics 2018; 13: 1208–1221) indicated epigenetic effects of cannabis use on sperm in man parallel those in rats and showed substantial shifts in both hypo- and hyper-DNA methylation with the latter predominating. This provides one likely mechanism for the transgenerational transmission of epigenomic instability with sperm as the vector. It therefore contributes important pathophysiological insights into the probable mechanisms underlying the epidemiology of prenatal cannabis exposure potentially explaining diverse features of cannabis-related teratology including effects on the neuraxis, cardiovasculature, immune stimulation, secondary genomic instability and carcinogenesis related to both adult and pediatric cancers. The potentially inheritable and therefore multigenerational nature of these defects needs to be carefully considered in the light of recent teratological and neurobehavioural trends in diverse jurisdictions such as the USA nationally, Hawaii, Colorado, Canada, France and Australia, particularly relating to mental retardation, age-related morbidity and oncogenesis including inheritable cancerogenesis. Increasing demonstrations that the epigenome can respond directly and in real time and retain memories of environmental exposures of many kinds implies that the genome-epigenome is much more sensitive to environmental toxicants than has been generally realized. Issues of long-term multigenerational inheritance amplify these concerns. Further research particularly on the epigenomic toxicology of many cannabinoids is also required.

Targeting Microglia Using Cx3cr1-Cre Lines: Revisiting the Specificity

Microglia play a pivotal role in maintaining homeostasis of the CNS. There is growing interest in understanding how microglia influence normal brain function and disease progression. Several microglia-specific Cx3cr1-Cre lines have been developed and have become indispensable tools in many investigations of microglial function. However, some recent studies have reported that these lines may have significant leakage into neurons. Other studies have reported that Cx3cr1 is expressed in non-microglial cells, including neurons and astrocytes, in vitro or in vivo either during brain development or upon neurological insult. All these reports raise serious concerns about the trustworthiness of these Cre-lines and whether the conclusions drawn from previous studies are valid. Here, we found that a floxed fluorescent reporter mouse line which has been frequently used to verify Cre lines displayed spontaneous expression of the GFP reporter, independent of Cre recombinase, thus revealing a potential caveat in assessing cre lines. We further confirmed that two Cx3cr1-Cre mouse lines can drive fluorescent reporter expression largely restrictively in microglia. Finally, we clarified that these two mouse lines maintain microglia-specific expression even following excitatory injury. Together, our findings confirm that two previously created Cx3cr1-Cre lines remain as invaluable tools for studying microglia. Moreover, to ensure the quality of data generated and the soundness of conclusions drawn from such data, it should be compulsory to thoroughly examine reporter lines for spontaneous leakiness when labeling cells to study CNS function and diseases.

CB1R regulates CDK5 signaling and epigenetically controls Rac1 expression contributing to neurobehavioral abnormalities in mice postnatally exposed to ethanol

Fetal alcohol spectrum disorders (FASD) represent a wide array of defects that arise from ethanol exposure during development. However, the underlying molecular mechanisms are limited. In the current report, we aimed to further evaluate the cannabinoid receptor type 1 (CB1R)-mediated mechanisms in a postnatal ethanol-exposed animal model. We report that the exposure of postnatal day 7 (P7) mice to ethanol generates p25, a CDK5-activating peptide, in a time- and CB1R-dependent manner in the hippocampus and neocortex brain regions. Pharmacological inhibition of CDK5 activity before ethanol exposure prevented accumulation of cleaved caspase-3 (CC3) and hyperphosphorylated tau (PHF1) (a marker for neurodegeneration) in neonatal mice and reversed cAMP response element-binding protein (CREB) activation and activity-regulated cytoskeleton-associated protein (Arc) expression. We also found that postnatal ethanol exposure caused a loss of RhoGTPase-related, Rac1, gene expression in a CB1R and CDK5 activity-dependent manner, which persisted to adulthood. Our epigenetic analysis of the Rac1 gene promoter suggested that persistent suppression of Rac1 expression is mediated by enhanced histone H3 lysine 9 dimethylation (H3K9me2), a repressive chromatin state, via G9a recruitment. The inhibition of CDK5/p25 activity before postnatal ethanol exposure rescued CREB activation, Arc, chromatin remodeling and Rac1 expression, spatial memory, and long-term potentiation (LTP) abnormalities in adult mice. Together, these findings propose that the postnatal ethanol-induced CB1R-mediated activation of CDK5 suppresses Arc and Rac1 expression in the mouse brain and is responsible for persistent synaptic plasticity and learning and memory defects in adult mice. This CB1R-mediated activation of CDK5 signaling during active synaptic development may slow down the maturation of synaptic circuits and may cause neurobehavioral defects, as found in this FASD animal model.

Endocannabinoid System and Alcohol Abuse Disorders

Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the primary active component in Cannabis sativa preparations such as hashish and marijuana, signals by binding to cell surface receptors. Two types of receptors have been cloned and characterized as cannabinoid (CB) receptors. CB1 receptors (CB1R) are ubiquitously present in the central nervous system (CNS) and are present in both inhibitory interneurons and excitatory neurons at the presynaptic terminal. CB2 receptors (CB2R) are demonstrated in microglial cells, astrocytes, and several neuron subpopulations and are present in both pre- and postsynaptic terminals. The majority of studies on these receptors have been conducted in the past two and half decades after the identification of the molecular constituents of the endocannabinoid (eCB) system that started with the characterization of CB1R. Subsequently, the seminal discovery was made, which suggested that alcohol (ethanol) alters the eCB system, thus establishing the contribution of the eCB system in the motivation to consume ethanol. Several preclinical studies have provided evidence that CB1R significantly contributes to the motivational and reinforcing properties of ethanol and that the chronic consumption of ethanol alters eCB transmitters and CB1R expression in the brain nuclei associated with addiction pathways. Additionally, recent seminal studies have further established the role of the eCB system in the development of ethanol-induced developmental disorders, such as fetal alcohol spectrum disorders (FASD). These results are augmented by in vitro and ex vivo studies, showing that acute and chronic treatment with ethanol produces physiologically relevant alterations in the function of the eCB system during development and in the adult stage. This chapter provides a current and comprehensive review of the literature concerning the role of the eCB system in alcohol abuse disorders (AUD).

Alcohol and the Developing Brain: Why Neurons Die and How Survivors Change

The consequences of alcohol drinking during pregnancy are dramatic and usually referred to as fetal alcohol spectrum disorders (FASD). This condition is one of the main causes of intellectual disability in Western countries. The immature fetal brain exposed to ethanol undergoes massive neuron death. However, the same mechanisms leading to cell death can also be responsible for changes of developmental plasticity. As a consequence of such a maladaptive plasticity, the functional damage to central nervous system structures is amplified and leads to permanent sequelae. Here we review the literature dealing with experimental FASD, focusing on the alterations of the cerebral cortex. We propose that the reciprocal interaction between cell death and maladaptive plasticity represents the main pathogenetic mechanism of the alcohol-induced damage to the developing brain.

Activity-dependent Signaling and Epigenetic Abnormalities in Mice Exposed to Postnatal Ethanol

Postnatal ethanol exposure has been shown to cause persistent defects in hippocampal synaptic plasticity and disrupt learning and memory processes. However, the mechanisms responsible for these abnormalities are less well studied. We evaluated the influence of postnatal ethanol exposure on several signaling and epigenetic changes and on expression of the activity-regulated cytoskeletal (Arc) protein in the hippocampus of adult offspring under baseline conditions and after a Y-maze spatial memory (SP) behavior (activity). Postnatal ethanol treatment impaired pCaMKIV and pCREB in naïve mice without affecting H4K8ac, H3K14ac and H3K9me2 levels. The Y-maze increased pCaMKIV, pCREB, H4K8ac and H3K14ac levels in saline-treated mice but not in ethanol-treated mice; while H3K9me2 levels were enhanced in ethanol-exposed animals compared to saline groups. Like previous observations, ethanol not only reduced Arc expression in naïve mice but also behaviorally induced Arc expression. ChIP results suggested that reduced H3K14ac and H4K8ac in the Arc gene promoter is because of impaired CBP, and increased H3K9me2 is due to the enhanced recruitment of G9a. The CB1R antagonist and a G9a/GLP inhibitor, which were shown to rescue postnatal ethanol-triggered synaptic plasticity and learning and memory deficits, were able to prevent the negative effects of ethanol on activity-dependent signaling, epigenetics and Arc expression. Together, these findings provide a molecular mechanism involving signaling and epigenetic cascades that collectively are responsible for the neurobehavioral deficits associated with an animal model of fetal alcohol spectrum disorders (FASD).