Paternal THC exposure in rats causes long-lasting neurobehavioral effects in the offspring

Influence of substance use on male reproductive health and offspring outcomes

The prevalence of substance use globally is rising and is highest among men of reproductive age. In Africa, and South and Central America, cannabis use disorder is most prevalent and in Eastern and South-Eastern Europe, Central America, Canada and the USA, opioid use disorder predominates. Substance use might be contributing to the ongoing global decline in male fertility, and emerging evidence has linked paternal substance use with short-term and long-term adverse effects on offspring development and outcomes. This trend is concerning given that substance use is increasing, including during the COVID-19 pandemic. Preclinical studies have shown that male preconception substance use can influence offspring brain development and neurobehaviour through epigenetic mechanisms. Additionally, human studies investigating paternal health behaviours during the prenatal period suggest that paternal tobacco, opioid, cannabis and alcohol use is associated with reduced offspring mental health, in particular hyperactivity and attention-deficit hyperactivity disorder. The potential effects of paternal substance use are areas in which to focus public health efforts and health-care provider counselling of couples or individuals interested in conceiving.

Phytocannabinoids in neuromodulation: From omics to epigenetics

BACKGROUND

Recent developments in metabolomics, transcriptomic and epigenetics open up new horizons regarding the pharmacological understanding of phytocannabinoids as neuromodulators in treating anxiety, depression, epilepsy, Alzheimer's, Parkinson's disease and autism.

METHODS

The present review is an extensive search in public databases, such as Google Scholar, Scopus, the Web of Science, and PubMed, to collect all the literature about the neurobiological roles of cannabis extract, cannabidiol, 9-tetrahydrocannabinol specially focused on metabolomics, transcriptomic, epigenetic, mechanism of action, in different cell lines, induced animal models and clinical trials. We used bioinformatics, network pharmacology and enrichment analysis to understand the effect of phytocannabinoids in neuromodulation.

RESULTS

Cannabidomics studies show wide variability of metabolites across different strains and varieties, which determine their medicinal and abusive usage, which is very important for its quality control and regulation. CB receptors interact with other compounds besides cannabidiol and Δ9-tetrahydrocannabinol, like cannabinol and Δ8-tetrahydrocannabinol. Phytocannabinoids interact with cannabinoid and non-cannabinoid receptors (GPCR, ion channels, and PPAR) to improve various neurodegenerative diseases. However, its abuse because of THC is also a problem found across different epigenetic and transcriptomic studies. Network enrichment analysis shows CNR1 expression in the brain and its interacting genes involve different pathways such as Rap1 signalling, dopaminergic synapse, and relaxin signalling. CBD protects against diseases like epilepsy, depression, and Parkinson's by modifying DNA and mitochondrial DNA in the hippocampus. Network pharmacology analysis of 8 phytocannabinoids revealed an interaction with 10 (out of 60) targets related to neurodegenerative diseases, with enrichment of ErbB and PI3K-Akt signalling pathways which helps in ameliorating neuro-inflammation in various neurodegenerative diseases. The effects of phytocannabinoids vary across sex, disease state, and age which suggests the importance of a personalized medicine approach for better success.

CONCLUSIONS

Phytocannabinoids present a range of promising neuromodulatory effects. It holds promise if utilized in a strategic way towards personalized neuropsychiatric treatment. However, just like any drug irrational usage may lead to unforeseen negative effects. Exploring neuro-epigenetics and systems pharmacology of major and minor phytocannabinoid combinations can lead to success.

Persisting neurobehavioral consequences of daily or intermittent paternal cannabis administration in F1 and F2 Rats

Repeated paternal preconception exposure to Δ9-tetrahydrocannabinol (Δ9-THC) alone or together with the other constituents in a cannabis extract has been shown in our earlier studies in rats to cause significant neurobehavioral impairment in their offspring. In the current study, we compared the effects of daily cannabis extract (CE) exposure to cannabis on two consecutive days per week, modeling weekend cannabis use in human. The CE contained Δ9-THC as well as cannabidiol and cannabinol. We also extended the investigation of the study to cross-generational effects of grand-paternal cannabis exposure on the F2 generation and included testing the effects of paternal cannabis exposure on responding for opiate self-administration in F1 and F2 generation offspring. We replicated the findings of neurobehavioral impairment in F1 offspring of male rats exposed to cannabis extract containing 4 mg/kg/day of Δ9-THC daily for four weeks prior to mating with drug naïve females. The 4-week cannabis extract exposure caused a significant decrease in weight gain in the male rats exposed daily. In contrast, their offspring showed significantly greater body weights and anogenital distances (AGD) in the third to fourth weeks after birth. The behavioral effects seen in the F1 generation were increased habituation of locomotor activity in the figure-8 maze in female offspring and increased lever pressing for the opiate drug remifentanil in male offspring. The F2 generation showed significantly impaired negative geotaxis and an elimination of the typical sex-difference in locomotor activity, with effects not seen in the F1 generation. This study shows that daily paternal cannabis exposure for four weeks prior to mating causes significant neurobehavioral impairment in the F1 and F2 offspring. Intermittent exposure on two consecutive days per week for four weeks caused comparable neurobehavioral impairment. In sum, there should be concern about paternal as well as maternal exposure to cannabis concerning neurobehavioral development of their offspring.

Trans-generational effects of parental exposure to drugs of abuse on offspring memory functions

Recent evidence reported that parental-derived phenotypes can be passed on to the next generations. Within the inheritance of epigenetic characteristics allowing the transmission of information related to the ancestral environment to the offspring, the specific case of the trans-generational effects of parental drug addiction has been extensively studied. Drug addiction is a chronic disorder resulting from complex interactions among environmental, genetic, and drug-related factors. Repeated exposures to drugs induce epigenetic changes in the reward circuitry that in turn mediate enduring changes in brain function. Addictive drugs can exert their effects trans-generally and influence the offspring of addicted parents. Although there is growing evidence that shows a wide range of behavioral, physiological, and molecular phenotypes in inter-, multi-, and trans-generational studies, transmitted phenotypes often vary widely even within similar protocols. Given the breadth of literature findings, in the present review, we restricted our investigation to learning and memory performances, as examples of the offspring's complex behavioral outcomes following parental exposure to drugs of abuse, including morphine, cocaine, cannabinoids, nicotine, heroin, and alcohol.

Prenatal Exposure to Cannabis: Effects on Childhood Obesity and Cardiometabolic Health

PURPOSE OF REVIEW

To consolidate information on the obesogenic and cardiometabolic effects of prenatal exposure to cannabis.

RECENT FINDINGS

A PubMed search strategy updated from January 1, 2014, through 14 June 2023, produced a total of 47 epidemiologic studies and 12 animal studies. Prenatal exposure to cannabis is consistently associated with small for gestational age and low birth weight. After birth, these offspring gain weight rapidly and have increased adiposity and higher glucose (fat mass percentage) in childhood. More preclinical and prospective studies are needed to deepen our understanding of whether these associations vary by sex, dose, timing, and composition of cannabis (e.g., ratio of delta-Δ9-tetrahydrocannabinol [Δ9-THC] to cannabidiol [CBD]). Addressing these gaps may help to solidify causality and identify intervention strategies. Based on the available data, clinicians and public health officials should continue to caution against cannabis use during pregnancy to limit its potential obesogenic and adverse cardiometabolic effects on the offspring.

Paternal methamphetamine exposure differentially affects first and second generations in mice

Amphetamine-type stimulants are abused worldwide, and methamphetamine (METH) accounts for a large majority of seized abused drug cases. Recently, the paternal origin of health and disease theory has been proposed as a concept wherein paternal factors influence descendants. Although METH abuse is more common among males, its effects on their descendants were not examined. Therefore, we investigated the effects of paternal METH exposure on F1 and F2 levels in a mouse model. Sires were administered METH for 21 days and mated with female mice to obtain F1 mice. Growth evaluations (number of births, survival rate, body weight, righting reflex, cliff avoidance tests, and wire-hanging maneuver) were performed on F1 mice. Upon reaching six weeks of age, the mice were subjected to spontaneous locomotion, elevated plus-maze, acute METH treatment, and passive avoidance tests. Additionally, RNA-seq was performed on the striatum of male mice. Male F1 mice were mated with female mice to obtain F2 mice. They were subjected to the same tests as the F1 mice. Paternal METH exposure resulted in delayed growth and decreased memory function in F1 mice, overweight in F2 mice, decreased METH sensitivity, and reduced anxiety-related behaviors in female F2 mice. Enrichment analysis revealed significant enrichment of terms related to behavior in F1 and protein folding in F2. These results indicated that the effects of paternal METH exposure vary across generations. The effects of paternal factors need to be examined not only in F1, but also in F2 and beyond.

Learning and memory deficits produced by aspartame are heritable via the paternal lineage

Environmental exposures produce heritable traits that can linger in the population for one or two generations. Millions of individuals consume substances such as artificial sweeteners daily that are declared safe by regulatory agencies without evaluation of their potential heritable effects. We show that consumption of aspartame, an FDA-approved artificial sweetener, daily for up to 16-weeks at doses equivalent to only 7-15% of the FDA recommended maximum daily intake value (equivalent to 2-4 small, 8 oz diet soda drinks per day) produces significant spatial learning and memory deficits in mice. Moreover, the cognitive deficits are transmitted to male and female descendants along the paternal lineage suggesting that aspartame's adverse cognitive effects are heritable, and that they are more pervasive than current estimates, which consider effects in the directly exposed individuals only. Traditionally, deleterious environmental exposures of pregnant and nursing women are viewed as risk factors for the health of future generations. Environmental exposures of men are not considered to pose similar risks. Our findings suggest that environmental exposures of men can produce adverse impact on cognitive function in future generations and demonstrate the need for considering heritable effects via the paternal lineage as part of the regulatory evaluations of artificial sweeteners.

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.

Cannabis and Paternal Epigenetic Inheritance

Cannabis is the most widely used illicit drug in Western counties and its abuse is particularly high in male adolescents and young adults. Its main psychotropic component, the cannabinoid delta-9-tetrahydrocannabinol (Δ⁹-THC), interferes in the endogenous endocannabinoid system. This signaling system is involved in the control of many biological activities, including the formation of high-quality male gametes. Direct adverse effects of Δ⁹-THC in male reproduction are well known in both animal models and humans. Nevertheless, the possibility of long-term effects due to epigenetic mechanisms has recently been reported. In this review, we summarize the main advances in the field suggesting the need to pay attention to the possible long-term epigenetic risks for the reproductive health of cannabis users and the health of their offspring.

Emerging Roles of Endocannabinoids as Key Lipid Mediators for a Successful Pregnancy

In recent years, Cannabis use/misuse for treating pregnancy-related symptoms and other chronic conditions has increased among pregnant women, favored by decriminalization and/or legalization of its recreational uses in addition to its easy accessibility. However, there is evidence that prenatal Cannabis exposure might have adverse consequences on pregnancy progression and a deleterious impact on proper neurodevelopmental trajectories in the offspring. Maternal Cannabis use could interfere with the complex and finely controlled role performed by the endocannabinoid system in reproductive physiology, impairing multiple gestational processes from blastocyst implantation to parturition, with long-lasting intergenerational effects. In this review, we discuss current clinical and preclinical evidence regarding the role of endocannabinoids in development, function, and immunity of the maternal–fetal interface, focusing on the impact of Cannabis constituents on each of these gestational processes. We also discuss the intrinsic limitations of the available studies and the future perspectives in this challenging research field.

Animal evidence considered in determination of cannabis smoke and Δ9 -tetrahydrocannabinol as causing reproductive toxicity (developmental endpoint): Part III. Proposed neurodevelopmental mechanisms of action

This review summarizes the most common potential pathways of neurodevelopmental toxicity due to perinatal exposure to Δ⁹ -tetrahydrocannabinol (Δ⁹ -THC) that lead to behavioral and other adverse outcomes (AOs). This is Part III in a set of reviews highlighting the animal-derived data considered by California's Developmental and Reproductive Toxicant Identification Committee (DARTIC) in 2019. The Hazard Identification Document (HID) provided to the DARTIC included a summary of human, whole animal, and mechanistic data on the neurodevelopmental toxicity of cannabis smoke and Δ⁹ -THC. The literature search for mechanistic data has been updated through 2020. We focus on mechanistic pathways relating to behavioral and other neurodevelopmental outcomes of perinatal exposure to Δ⁹ -THC. The endocannabinoid system (EC system) plays a crucial role in many processes involved in neurodevelopment and exposure to Δ⁹ -THC can alter these processes. Whole animal studies report changes in cognitive ability, behavior, and motor function after prenatal exposure to Δ⁹ -THC. Findings from mechanistic studies add to this evidence and further provide information regarding the pathways leading to these outcomes. Neuromechanistic studies can bridge the gaps between molecular initiating events and apical neurodevelopmental endpoints caused by a chemical. They offer insight into potential alterations in the same pathways by other chemicals that can also result in AOs. Studies of cannabinoid receptor agonist-induced molecular alterations and provide deep biological plausibility at the mechanistic level for the cognitive, behavioral, and motor impairments observed in animal studies after perinatal exposure to Δ⁹ -THC.

Sperm DNA methylation alterations from cannabis extract exposure are evident in offspring

Background

Cannabis legalization is expanding and men are the predominant users. We have limited knowledge about how cannabis impacts sperm and whether the effects are heritable.

Results

Whole genome bisulfite sequencing (WGBS) data were generated for sperm of rats exposed to: (1) cannabis extract (CE) for 28 days, then 56 days of vehicle only (~ one spermatogenic cycle); (2) vehicle for 56 days, then 28 days of CE; or (3) vehicle only. Males were then mated with drug-naïve females to produce F1 offspring from which heart, brain, and sperm tissues underwent analyses. There were 3321 nominally significant differentially methylated CpGs in F0 sperm identified via WGBS with select methylation changes validated via bisulfite pyrosequencing. Significant methylation changes validated in F0 sperm of the exposed males at the gene 2-Phosphoxylose Phosphatase 1 (Pxylp1) were also detectable in their F1 sperm but not in controls. Changes validated in exposed F0 sperm at Metastasis Suppressor 1-Like Protein (Mtss1l) were also present in F1 hippocampal and nucleus accumbens (NAc) of the exposed group compared to controls. For Mtss1l, a significant sex-specific relationship between DNA methylation and gene expression was demonstrated in the F1 NAc. Phenotypically, rats born to CSE-exposed fathers exhibited significant cardiomegaly relative to those born to control fathers.

Conclusions

This is the first characterization of the effect of cannabis exposure on the entirety of the rat sperm methylome. We identified CE-associated methylation changes across the sperm methylome, some of which persisted despite a “washout” period. Select methylation changes validated via bisulfite pyrosequencing, and genes associated with methylation changes were involved in early developmental processes. Preconception CE exposure is associated with detectable changes in offspring DNA methylation that are functionally related to changes in gene expression and cardiomegaly.

These results support that paternal preconception exposure to cannabis can influence offspring outcomes.

Prenatal Δ9-Tetrahydrocannabinol Exposure in Males Leads to Motivational Disturbances Related to Striatal Epigenetic Dysregulation

BACKGROUND

Cannabis remains one of the most widely abused drugs during pregnancy. In utero exposure to its principal psychoactive component, Δ⁹-tetrahydrocannabinol (THC), can result in long-term neuropsychiatric risk for the progeny. This study investigated epigenetic signatures underlying these enduring consequences.

METHODS

Rat dams were exposed daily to THC (0.15 mg/kg) during pregnancy, and adult male offspring were examined for reward and depressive-like behavioral endophenotypes. Using unbiased sequencing approaches, we explored transcriptional and epigenetic profiles in the nucleus accumbens (NAc), a brain area central to reward and emotional processing. An in vitro CRISPR (clustered regularly interspaced short palindromic repeats) activation model coupled with RNA sequencing was also applied to study specific consequences of epigenetic dysregulation, and altered molecular signatures were compared with human major depressive disorder transcriptome datasets.

RESULTS

Prenatal THC exposure induced increased motivation for food, heightened learned helplessness and anhedonia, and altered stress sensitivity. We identified a robust increase specific to males in the expression of Kmt2a (histone-lysine N-methyltransferase 2A) that targets H3K4 (lysine 4 on histone H3) in cellular chromatin. Normalizing Kmt2a in the NAc rescued the motivational phenotype of prenatally THC-exposed animals. Comparison of RNA- and H3K4me3-sequencing datasets from the NAc of rat offspring with the in vitro model of Kmt2a upregulation revealed overlapping, significant disturbances in pathways that mediate synaptic plasticity. Similar transcriptional alterations were detected in human major depressive disorder.

CONCLUSIONS

These studies provide direct evidence for the persistent effects of prenatal cannabis exposure on transcriptional and epigenetic deviations in the NAc via Kmt2a dysregulation and associated psychiatric vulnerability.

Cannabis significantly alters DNA methylation of the human ovarian follicle in a concentration-dependent manner

Cannabis is increasingly consumed by women of childbearing age, and the reproductive and epigenetic effects are unknown. The purpose of this study was to evaluate the potential epigenetic implications of cannabis use on the female ovarian follicle. Whole-genome methylation was assessed in granulosa cells from 14 matched case-control patients. Exposure status was determined by liquid chromatography-mass spectrometry (LC-MS/MS) measurements of five cannabis-derived phytocannabinoids in follicular fluid. DNA methylation was measured using the Illumina TruSeq Methyl Capture EPIC kit. Differential methylation, pathway analysis and correlation analysis were performed. We identified 3679 differentially methylated sites, with two-thirds affecting coding genes. A hotspot region on chromosome 9 was associated with two genomic features, a zinc-finger protein (ZFP37) and a long non-coding RNA (FAM225B). There were 2214 differentially methylated genomic features, 19 of which have been previously implicated in cannabis-related epigenetic modifications in other organ systems. Pathway analysis revealed enrichment in G protein-coupled receptor signaling, cellular transport, immune response and proliferation. Applying strict criteria, we identified 71 differentially methylated regions, none of which were previously annotated in this context. Finally, correlation analysis revealed 16 unique genomic features affected by cannabis use in a concentration-dependent manner. Of these, the histone methyltransferases SMYD3 and ZFP37 were hypomethylated, possibly implicating histone modifications as well. Herein, we provide the first DNA methylation profile of human granulosa cells exposed to cannabis. With cannabis increasingly legalized worldwide, further investigation into the heritability and functional consequences of these effects is critical for clinical consultation and for legalization guidelines.

Epidemiology of Δ8THC-Related Carcinogenesis in USA: A Panel Regression and Causal Inferential Study

The use of Δ8THC is increasing at present across the USA in association with widespread cannabis legalization and the common notion that it is "legal weed". As genotoxic actions have been described for many cannabinoids, we studied the cancer epidemiology of Δ8THC. Data on 34 cancer types was from the Centers for Disease Control Atlanta Georgia, substance abuse data from the Substance Abuse and Mental Health Services Administration, ethnicity and income data from the U.S. Census Bureau, and cannabinoid concentration data from the Drug Enforcement Agency, were combined and processed in R. Eight cancers (corpus uteri, liver, gastric cardia, breast and post-menopausal breast, anorectum, pancreas, and thyroid) were related to Δ8THC exposure on bivariate testing, and 18 (additionally, stomach, Hodgkins, and Non-Hodgkins lymphomas, ovary, cervix uteri, gall bladder, oropharynx, bladder, lung, esophagus, colorectal cancer, and all cancers (excluding non-melanoma skin cancer)) demonstrated positive average marginal effects on fully adjusted inverse probability weighted interactive panel regression. Many minimum E-Values (mEVs) were infinite. p-values rose from 8.04 × 10-78. Marginal effect calculations revealed that 18 Δ8THC-related cancers are predicted to lead to a further 8.58 cases/100,000 compared to 7.93 for alcoholism and -8.48 for tobacco. Results indicate that between 8 and 20/34 cancer types were associated with Δ8THC exposure, with very high effect sizes (mEVs) and marginal effects after adjustment exceeding tobacco and alcohol, fulfilling the epidemiological criteria of causality and suggesting a cannabinoid class effect. The inclusion of pediatric leukemias and testicular cancer herein demonstrates heritable malignant teratogenesis.

Proceedings of the 2021 annual meeting of the Fetal Alcohol Spectrum Disorders Study Group

The 2021 meeting of the Fetal Alcohol Spectrum Disorders Study Group (FASDSG) was titled "Role of Parental Experiences in Offspring Outcomes". The theme was reflected in the presentations of two keynote speakers: Edward Levin, Ph.D., who spoke about the role of paternal exposures in offspring development, and Catherine Monk, Ph.D., who spoke about the effects of maternal exposures and maternal mental health on offspring development. The conference included updates from three government agencies, short presentations by junior and senior investigators showcasing late-breaking FASD research, a report on international efforts to streamline FASD classifications for research, a presentation of observations from adults with FASD, a short film of people with FASDs describing their experiences, and a poster session. The conference was capped by awarding the 2021 Henry Rosett award for career-long contributions to the field to Cynthia J.M. Kane, Ph.D.

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.

Effects of Prenatal Nicotine, THC, or Co-Exposure on Cognitive Behaviors in Adolescent Male and Female Rats

INTRODUCTION

Although there has been a decrease in the prevalence of tobacco smoking, exposure to nicotine during pregnancy remains a substantial problem worldwide. Further, given the recent escalation in e-cigarette use and legalization of cannabis, it has become essential to understand the effects of nicotine and cannabinoid co-exposure during early developmental stages.

AIMS AND METHODS

We systematically examined the effects of nicotine and/or THC prenatal exposure on cognitive behaviors in male and female offspring. Dams were exposed to nicotine vape or vehicle, and oral edible THC or vehicle, throughout pregnancy. Adolescent offspring were then tested in the prepulse inhibition test, novel object recognition task, and novelty suppressed feeding task.

RESULTS

At birth, pups from mothers exposed to nicotine vape or oral THC exhibited reduced body weight, compared to control pups. Prenatal nicotine vape exposure resulted in a decreased baseline startle reactivity in adolescent male and female rats, and in females, enhanced sensorimotor gating in the prepulse inhibition test. Prenatal nicotine and THC co-exposure resulted in significant deficits in the prepulse inhibition test in males. Deficits in short-term memory were also found in males prenatally exposed to THC, either alone or with nicotine co-exposure, and in females exposed to THC alone. Finally, in males, a modest increase in anxiety-associated behaviors was found with THC or nicotine exposure in the latency to approach a novel palatable food.

CONCLUSIONS

These studies demonstrate differential effects of prenatal exposure to e-cigarette nicotine vape and/or edible THC on cognitive function, with differing effects within male and female groups.

IMPLICATIONS

These studies demonstrate an impact of nicotine, THC, or co-exposure during early developmental stages in utero on behavioral outcomes in adolescence. These findings have important translational implications given the continued use of nicotine and THC containing products by pregnant women worldwide, which can be applied to support healthcare and policy efforts restricting nicotine and THC use during pregnancy.

Does paternal methamphetamine exposure affect the behavior of rat offspring during development and in adulthood?

Methamphetamine (MA) is one of the most abused psychostimulants in the Czech Republic and worldwide. Previous studies have demonstrated the adverse effects of maternal drug abuse. However, the father's contribution as a parent and donor of the half genetic information is unclear. The present study aimed to examine the effect of paternal MA exposure on behavioral development and locomotor activity in rat offspring. MA was administrated subcutaneously for 30 days at a dose of 5 mg/kg to adult male rats. The impact of paternal MA exposure on rat pups was investigated using behavioral tests during development and locomotor activity tests in adulthood. Prior to testing, adult offspring were exposed to an acute challenge dose of MA (1 mg/kg) to examine the possible sensitizing effect of the paternal treatment. Our results found no significant differences in behavioral development or locomotor activity in adulthood of offspring linked to paternal MA application. These results differ from the effects induced by maternal MA application. Further, our results demonstrated a significant increase in locomotor activity on the Laboras test after acute MA application. When comparing sex differences, females showed more activity than males in adulthood, whereas males were more active during development.

Paternal Cannabis Exposure Prior to Mating, but Not Δ9-Tetrahydrocannabinol, Elicits Deficits in Dopaminergic Synaptic Activity in the Offspring

The legalization and increasing availability of cannabis products raises concerns about the impact on offspring of users, and little has appeared on the potential contribution of paternal use. We administered cannabis extract to male rats prior to mating, with two different 28-day exposures, one where there was a 56-day interval between the end of exposure and mating ("Early Cannabis"), and one just prior to mating ("Late Cannabis"); the extract delivered 4 mg/kg/day of the main psychoactive component, Δ9-tetrahydrocannabinol. We then assessed the impact on dopamine (DA) systems in the offspring from the onset of adolescence (postnatal day 30) through middle age (postnatal day 150), measuring the levels of DA and its primary metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC) in various brain regions. Paternal cannabis with either regimen elicited a profound and persistent deficit in DA utilization (DOPAC/DA ratio) in the offspring, indicative of subnormal presynaptic activity. However, the two regimens differed in the underlying mechanism, with Early Cannabis reducing DOPAC whereas Late Cannabis increased DA and elicited a smaller reduction in DOPAC. Effects were restricted to male offspring. The effects of cannabis were not reproduced by equivalent exposure to its Δ9-tetrahydrocannabinol, nor did we see the effects with perinatal exposure to tobacco smoke or some of its fetotoxic contributors (benzo[a]pyrene without or with nicotine). Our studies provide some of the first evidence for adverse effects of paternal cannabis administration on neurodevelopment in the offspring, and reinforce the important consequences of paternal drug use in the preconception period.

Effect of Multiple Sclerosis and Its Treatments on Male Fertility: Cues for Future Research

Multiple sclerosis is a chronic disease that may lead to different types of symptoms and disabilities. with the better quality of life and decreased disability due to early diagnosis and the availability of disease-modifying therapies (DMTs), the treating physician is increasingly asked to counsel patients on its effects on fertility and reproduction. In particular, reproductive issues are still scarcely studied and discussed in men. Among the still open questions are the following: (a) Does multiple sclerosis cause infertility per sè? (b) Is multiple sclerosis correlated with conditions that increase the risk of infertility? (c) Do DMTs or other therapies for multiple sclerosis impact gonadal function in men? The aim of this review is to provide an overview on the available literature data about the reproductive issues unique to men with multiple sclerosis, underlining the numerous areas where evidence is lacking and, therefore, the priorities for future research.

Metabolic Consequences of Gestational Cannabinoid Exposure

Up to 20% of pregnant women ages 18-24 consume cannabis during pregnancy. Moreover, clinical studies indicate that cannabis consumption during pregnancy leads to fetal growth restriction (FGR), which is associated with an increased risk of obesity, type II diabetes (T2D), and cardiovascular disease in the offspring. This is of great concern considering that the concentration of Δ9- tetrahydrocannabinol (Δ9-THC), a major psychoactive component of cannabis, has doubled over the last decade and can readily cross the placenta and enter fetal circulation, with the potential to negatively impact fetal development via the endocannabinoid (eCB) system. Cannabis exposure in utero could also lead to FGR via placental insufficiency. In this review, we aim to examine current pre-clinical and clinical findings on the direct effects of exposure to cannabis and its constituents on fetal development as well as indirect effects, namely placental insufficiency, on postnatal metabolic diseases.

Cannabis and tobacco use prior to pregnancy and subsequent offspring birth outcomes: a 20-year intergenerational prospective cohort study

There is increasing evidence that the life-course origins of health and development begin before conception. We examined associations between timing and frequency of preconception cannabis and tobacco use and next generation preterm birth (PTB), low birth weight (LBW) and small for gestational age. 665 participants in a general population cohort were repeatedly assessed on tobacco and cannabis use between ages 14-29 years, before pregnancy. Associations were estimated using logistic regression. Preconception parent (either maternal or paternal) daily cannabis use age 15-17 was associated with sixfold increases in the odds of offspring PTB (aOR 6.65, 95% CI 1.92, 23.09), and offspring LBW (aOR 5.84, 95% CI 1.70-20.08), after adjusting for baseline sociodemographic factors, parent sex, offspring sex, family socioeconomic status, parent mental health at baseline, and concurrent tobacco use. There was little evidence of associations with preconception parental cannabis use at other ages or preconception parental tobacco use. Findings support the hypothesis that the early life origins of growth begin before conception and provide a compelling rationale for prevention of frequent use during adolescence. This is pertinent given liberalisation of cannabis policy.

Paternal Fenitrothion Exposures in Rats Causes Sperm DNA Fragmentation in F0 and Histomorphometric Changes in Selected Organs of F1 Generation

The adverse effects of maternal pesticides exposure on the progeny is very well established. However, the impact of paternal exposure to pesticides such as Fenitrothion (FNT) on the histomorphometry of progeny’s organs in unexposed mothers are much less well studied. Therefore, this study aims to evaluate the effects of paternal FNT exposure on the sperm quality of the parent rat and its effects on the histomorphometry of the progeny’s organs. Randomly, male Sprague Dawley rats (n = 24) categorized as F0 were distributed equally into three groups namely Control, FNT-10, and FNT-20. Control received 1 mL/kg corn oil while FNT-10 and FNT-20 received 10 mg/kg and 20 mg/kg of FNT, respectively, via oral force feeding for 28 consecutive days. At the end of the study, male rats were mated with unexposed female rats and the male rats were sacrificed to obtain sperm for sperm characterization and DNA damage evaluation. Meanwhile, the rats’ progeny (F1) namely pControl, pFNT-10, and pFNT-20 were left to grow until postnatal day 70 before being sacrificed to obtain the matured organs for histology and morphometric analysis. Our results showed that both doses of FNT reduced sperm quality and caused DNA fragmentation in F0 rats compared with the control group (p < 0.05). The number of Leydig cells as well as the diameter of the seminiferous tubules and glomerulus of the pFNT-20 group had significantly decreased (p < 0.05) compared with the pControl group. The Bowman’s space of the pFNT-20 group had significantly increased (p < 0.05) compared with the pFNT-10 and pControl groups. Therefore, paternal exposure to FNT reduced the sperm quality and increased sperm DNA fragmentation in F0 male Sprague Dawley rats and altered the histology and morphometry of the selected organs in the F1 progeny.

Paternal and/or maternal preconception-induced neurobehavioral teratogenicity in animal and human models

Prenatal insult exposure effects on the offspring, have and are still considered the main interest of most teratological studies, while paternal and maternal preconception effects have received relatively little interest. Once thought to be a myth, paternal exposure to insults leading to numerous detrimental effects in the offspring, has been confirmed on several occasions and is gaining increased attention. These effects could be demonstrated molecularly, biochemically and/or behaviorally. Different epigenetic mechanisms have been proposed for these effects to occur, including DNA methylation, histone modification and sperm RNA transmission. Paternal insult exposure has been shown to cause several neurobehavioral and developmental defects in the offspring. Findings on parental insult exposure effects on the progeny will be discussed in this review, with the main focus being on neurobehavioral effects after parental preconceptional exposure. The exposure to the insults induced long-lasting, mostly marked, defects. A few pioneering, prevention and reversal studies were published. Interestingly, most studies were conducted on paternal exposure and, at the present state of this field, on animal models. Clinical translation remains the subsequent challenge.

Paternal Δ9-Tetrahydrocannabinol Exposure Prior to Mating Elicits Deficits in Cholinergic Synaptic Function in the Offspring

Little attention has been paid to the potential impact of paternal marijuana use on offspring brain development. We administered Δ9-tetrahydrocannabinol (THC, 0, 2, or 4 mg/kg/day) to male rats for 28 days. Two days after the last THC treatment, the males were mated to drug-naïve females. We then assessed the impact on development of acetylcholine (ACh) systems in the offspring, encompassing the period from the onset of adolescence (postnatal day 30) through middle age (postnatal day 150), and including brain regions encompassing the majority of ACh terminals and cell bodies. Δ9-Tetrahydrocannabinol produced a dose-dependent deficit in hemicholinium-3 binding, an index of presynaptic ACh activity, superimposed on regionally selective increases in choline acetyltransferase activity, a biomarker for numbers of ACh terminals. The combined effects produced a persistent decrement in the hemicholinium-3/choline acetyltransferase ratio, an index of impulse activity per nerve terminal. At the low THC dose, the decreased presynaptic activity was partially compensated by upregulation of nicotinic ACh receptors, whereas at the high dose, receptors were subnormal, an effect that would exacerbate the presynaptic defect. Superimposed on these effects, either dose of THC also accelerated the age-related decline in nicotinic ACh receptors. Our studies provide evidence for adverse effects of paternal THC administration on neurodevelopment in the offspring and further demonstrate that adverse impacts of drug exposure on brain development are not limited to effects mediated by the embryonic or fetal chemical environment, but rather that vulnerability is engendered by exposures occurring prior to conception, involving the father as well as the mother.

Cannabis and synaptic reprogramming of the developing brain

Recent years have been transformational in regard to the perception of the health risks and benefits of cannabis with increased acceptance of use. This has unintended neurodevelopmental implications given the increased use of cannabis and the potent levels of Δ⁹-tetrahydrocannabinol today being consumed by pregnant women, young mothers and teens. In this Review, we provide an overview of the neurobiological effects of cannabinoid exposure during prenatal/perinatal and adolescent periods, in which the endogenous cannabinoid system plays a fundamental role in neurodevelopmental processes. We highlight impaired synaptic plasticity as characteristic of developmental exposure and the important contribution of epigenetic reprogramming that maintains the long-term impact into adulthood and across generations. Such epigenetic influence by its very nature being highly responsive to the environment also provides the potential to diminish neural perturbations associated with developmental cannabis exposure.

Genetic overlap and causality between substance use disorder and attention-deficit and hyperactivity disorder

Substance use disorder (SUD) often co-occur at high prevalence with other psychiatric conditions. Among them, attention-deficit and hyperactivity disorder (ADHD) is present in almost one out of every four subjects with SUD and is associated with higher severity, more frequent polysubstance dependence and increased risk for other mental health problems in SUD patients. Despite studies suggesting a genetic basis in the co-occurrence of these two conditions, the genetic factors involved in the joint development of both disorders and the mechanisms mediating these causal relationships are still unknown. In this study, we tested whether the genetic liability to five SUD-related phenotypes share a common background in the general population and clinically diagnosed ADHD individuals from an in-house sample of 989 subjects and further explored the genetic overlap and the causal relationship between ADHD and SUD using pre-existing GWAS datasets. Our results confirm a common genetic background between ADHD and SUD and support the current literature on the causal effect of the liability to ADHD on the risk for SUD. We added novel findings on the effect of the liability of lifetime cannabis use on ADHD and found evidence of shared genetic background underlying SUD in general population and in ADHD, at least for lifetime cannabis use, alcohol dependence and smoking initiation. These findings are in agreement with the high comorbidity observed between ADHD and SUD and highlight the need to control for substance use in ADHD and to screen for ADHD comorbidity in all SUD patients to provide optimal clinical interventions.

Refraining from use diminishes cannabis-associated epigenetic changes in human sperm

Cannabis use alters sperm DNA methylation, but the potential reversibility of these changes is unknown. Semen samples from cannabis users and non-user controls were collected at baseline and again following a 77-day period of cannabis abstinence (one spermatogenic cycle). Users and controls did not significantly differ by demographics or semen analyses. Whole-genome bisulfite sequencing identified 163 CpG sites with significantly different DNA methylation in sperm between groups (P < 2.94 × 10^-9). Genes associated with altered CpG sites were enriched with those involved in development, including cardiogenesis and neurodevelopment. Many of the differences in sperm DNA methylation between groups were diminished after cannabis abstinence. These results indicate that sustained cannabis abstinence significantly reduces the number of sperm showing cannabis-associated alterations at genes important for early development.

Cross-generational THC Exposure Weakly Attenuates Cocaine's Rewarding Effects in Adult Male Offspring

Adolescents represent a large demographic of marijuana consumers. Regrettably, use during this developmental period has been associated with above average health risks. A growing body of evidence suggests that adolescent drug use in the lifetime of a parent can modify behavior and neurochemistry in descendants without direct exposure. The current study was designed to evaluate the effects of pre-conception THC during adolescence on vulnerability to cocaine in adult male offspring. Male and female rats were given an intermittent THC (0 or 1.5 mg/kg) exposure regimen during the adolescent window and mated with drug group conspecifics in adulthood. F1-THC and F1-Veh pups were cross fostered to drug naïve control dams. In Experiment 1, adult offspring underwent cocaine (0 or 15 mg/kg) locomotor sensitization procedures and showed no effect of parental THC exposure on locomotor activity. In Experiment 2, intravenous catheters were implanted and subjects were tested under a number of reinforcement schedules with cocaine (FR1, FR5, FR10, PR, dose-response, extinction, cue + stress induced reinstatement). F1-THC subjects exhibited a slight decrease in cocaine responding during acquisition and a more rapid extinction, but they failed to produce significant differences on any other measure. These findings indicate that adolescent cannabis use likely has minimal effects on cocaine abuse liability in the next generation.

Epigenetic changes on rat chromosome 4 contribute to disparate alcohol drinking behavior in alcohol-preferring and -nonpreferring rats

BACKGROUND

Paternal alcohol abuse is a well-recognized risk factor for the development of an alcohol use disorder (AUD). In addition to genetic and environmental risk factors, heritable epigenetic factors also have been proposed to play a key role in the development of AUD. However, it is not clear whether epigenetic factors contribute to the genetic inheritance in families affected by AUD. We used reciprocal crosses of the alcohol-preferring (P) and -nonpreferring (NP) rat lines to test whether epigenetic factors also impacted alcohol drinking in up to two generations of offspring.

METHODS

F1 offspring derived by reciprocal breeding of P and NP rats were tested for differences in alcohol consumption using a free-choice protocol of 10% ethanol, 20% ethanol, and water that were available concurrently. In a separate experiment, an F2 population was tested for alcohol consumption not only due to genetic differences. These rats were generated from inbred P (iP) and iNP rat lines that were reciprocally bred to produce genetically identical F1 offspring that remained alcohol-naïve. Intercrosses of the F1 generation animals produced the F2 generation. Alcohol consumption was then assessed in the F2 generation using a standard two-bottle choice protocol, and was analyzed using genome-wide linkage analysis. Alcohol consumption measures were also analyzed for sex differences.

RESULTS

Average alcohol consumption was higher in the F1 offspring of P vs. NP sires and in the F2 offspring of F0 iP vs. iNP grandsires. Linkage analyses showed the maximum LOD scores for alcohol consumption in both male and female offspring were on chromosome 4 (Chr 4). The LOD score for both sexes considered together was higher when the grandsire was iP vs. iNP (5.0 vs. 3.35, respectively). Furthermore, the F2 population displayed enhanced alcohol consumption when the P alleles from the F0 sire were present.

CONCLUSIONS

These results demonstrate that epigenetic and/or non-genetic factors mapping to rat chromosome 4 contribute to a transgenerational paternal effect on alcohol consumption in the P and NP rat model of AUD.

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.

Sperm DNA methylation altered by THC and nicotine: Vulnerability of neurodevelopmental genes with bivalent chromatin

Men consume the most nicotine and cannabis products but impacts on sperm epigenetics are poorly characterized. Evidence suggests that preconception exposure to these drugs alters offspring neurodevelopment. Epigenetics may in part facilitate heritability. We therefore compared effects of exposure to tetrahydrocannabinol (THC) and nicotine on DNA methylation in rat sperm at genes involved in neurodevelopment. Reduced representation bisulfite sequencing data from sperm of rats exposed to THC via oral gavage showed that seven neurodevelopmentally active genes were significantly differentially methylated versus controls. Pyrosequencing data revealed majority overlap in differential methylation in sperm from rats exposed to THC via injection as well as those exposed to nicotine. Neurodevelopmental genes including autism candidates are vulnerable to environmental exposures and common features may mediate this vulnerability. We discovered that autism candidate genes are significantly enriched for bivalent chromatin structure, suggesting this configuration may increase vulnerability of genes in sperm to disrupted methylation.

Cannabis Exposure During Critical Windows of Development: Epigenetic and Molecular Pathways Implicated in Neuropsychiatric Disease

PURPOSE OF REVIEW

Cannabis exposure during critical windows of development may have intergenerational physiological consequences disrupting epigenetic programming and marks. This review examines the literature relating to pre-gestational and prenatal cannabinoid exposure and its effect on genes and molecular pathways related to the development of psychiatric disease.

RECENT FINDINGS

Developmental cannabis exposure alters epigenetic processes with functional gene consequences. These include potentially heritable alterations in genes and molecular pathways critical for brain development and associated with autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), schizophrenia, addiction, and other psychiatric diseases. Cannabis consumption and mental health illness in adolescents and young adults are increasing in the United States (U.S.), and recent studies suggest that cannabis consumption during critical periods of brain development could contribute to mental health illness through epigenetic mechanisms. These findings warrant future studies and consideration by regulators and health communicators.

Update on the developmental consequences of cannabis use during pregnancy and lactation

There is a strong increase in prevalence trends for cannabis use during pregnancy and lactation as more states legalize use of this drug. Information on the teratogenic risk of cannabis is limited but some important themes can be gleaned. Studies have not found a unique phenotypic signature of prenatal exposure but an increased risk of congenital anomalies, particularly gastroschisis, has been reported. Changes in fetal growth have been described in some epidemiological studies but long-term patterns of physical growth appear unaffected. Prenatal exposure to cannabis is not generally associated with reductions in global IQ but specific cognitive skills, especially attention and memory, can be negatively impacted. Long-term impacts on psychological health include increased rates of depressive symptoms and anxiety as well as delinquency. Relatively little is known about the risk of maternal cannabis use during lactation but data suggest that infant exposure is relatively low compared to maternal exposure. As delta-9-tetrahydrocannabinol (THC) levels increase to meet consumer demand and routes of exposure diversify, there is a strong need for prospective birth-cohort studies that collect biological samples to quantify exposure. Data from such studies will be critical to overcoming the weaknesses of past cannabis research and are essential to establishing reliable information on the risks of maternal use. Until that time, health care providers should be encouraged to talk about the risks and benefits associated with cannabis use during pregnancy and lactation with their patients, emphasizing that fetal and neonatal risks cannot be excluded at this time.

Early life lessons: The lasting effects of germline epigenetic information on organismal development

BACKGROUND

An organism's metabolic phenotype is primarily affected by its genotype, its lifestyle, and the nutritional composition of its food supply. In addition, it is now clear from studies in many different species that ancestral environments can also modulate metabolism in at least one to two generations of offspring.

SCOPE OF REVIEW

We limit ourselves here to paternal effects in mammals, primarily focusing on studies performed in inbred rodent models. Although hundreds of studies link paternal diets and offspring metabolism, the mechanistic basis by which epigenetic information in sperm programs nutrient handling in the next generation remains mysterious. Our goal in this review is to provide a brief overview of paternal effect paradigms and the germline epigenome. We then pivot to exploring one key mystery in this literature: how do epigenetic changes in sperm, most of which are likely to act transiently in the early embryo, ultimately direct a long-lasting physiological response in offspring?

MAJOR CONCLUSIONS

Several potential mechanisms exist by which transient epigenetic modifications, such as small RNAs or methylation states erased shortly after fertilization, could be transferred to more durable heritable information. A detailed mechanistic understanding of this process will provide deep insights into early development, and could be of great relevance for human health and disease.

Epigenetic alterations in cytochrome P450 oxidoreductase (Por) in sperm of rats exposed to tetrahydrocannabinol (THC)

As marijuana legalization is increasing, research regarding possible long-term risks for users and their offspring is needed. Little data exists on effects of paternal tetrahydrocannabinol (THC) exposure prior to reproduction. This study determined if chronic THC exposure alters sperm DNA methylation (DNAm) and if such effects are intergenerationally transmitted. Adult male rats underwent oral gavage with THC or vehicle control. Differentially methylated (DM) loci in motile sperm were identified using reduced representation bisulfite sequencing (RRBS). Another cohort was injected with vehicle or THC, and sperm DNAm was analyzed. Finally, THC-exposed and control adult male rats were mated with THC-naïve females. DNAm levels of target genes in brain tissues of the offspring were determined by pyrosequencing. RRBS identified 2,940 DM CpGs mapping to 627 genes. Significant hypermethylation was confirmed (p < 0.05) following oral THC administration for cytochrome P450 oxidoreductase (Por), involved in toxin processing and disorders of sexual development. Por hypermethylation was not observed after THC injection or in the subsequent generation. These results support that THC alters DNAm in sperm and that route of exposure can have differential effects. Although we did not observe evidence of intergenerational transmission of the DNAm change, larger studies are required to definitively exclude this possibility.

NRF2 loss recapitulates heritable impacts of paternal cigarette smoke exposure

Paternal cigarette smoke (CS) exposure is associated with increased risk of behavioral disorders and cancer in offspring, but the mechanism has not been identified. Here we use mouse models to investigate mechanisms and impacts of paternal CS exposure. We demonstrate that CS exposure induces sperm DNAme changes that are partially corrected within 28 days of removal from CS exposure. Additionally, paternal smoking is associated with changes in prefrontal cortex DNAme and gene expression patterns in offspring. Remarkably, the epigenetic and transcriptional effects of CS exposure that we observed in wild type mice are partially recapitulated in Nrf2-/- mice and their offspring, independent of smoking status. Nrf2 is a central regulator of antioxidant gene transcription, and mice lacking Nrf2 consequently display elevated oxidative stress, suggesting that oxidative stress may underlie CS-induced heritable epigenetic changes. Importantly, paternal sperm DNAme changes do not overlap with DNAme changes measured in offspring prefrontal cortex, indicating that the observed DNAme changes in sperm are not directly inherited. Additionally, the changes in sperm DNAme associated with CS exposure were not observed in sperm of unexposed offspring, suggesting the effects are likely not maintained across multiple generations.

Paternal exposure to recreational drugs before conception and its effect on live-born offspring: A scoping review

BACKGROUND

Men of reproductive age increasingly use recreational drugs. While many of these substances may reduce the quantity and quality of sperm, less is known about the effects of these exposures on their offspring. We performed a scoping review to summarize the available literature and identify areas for future research on the outcome of live-born offspring of fathers who were exposed to recreational drugs before conception.

METHODS

A systematic search was conducted of the Medline, EMBASE, and Web of Science databases, which included keywords for the following substances: cannabis-related products, cocaine, heroin, hallucinogens, ecstasy and amphetamines. In total, 2,983 records were screened, and 129 publications were selected for full-text assessment. Publications were included if (a) the timing of exposure included the preconceptional period, and (b) if outcomes in live-born offspring were compared with an unexposed group.

RESULTS

We included 30 publications, of which 15 animal studies and 15 human studies. Animal studies showed neurocognitive abnormalities, in particular in male offspring. Interestingly, these outcomes depend significantly on the method of exposure (i.e., fixed-dose administration vs. variable self-administration, which mimics addiction). Human studies were limited to specific congenital malformations and childhood cancers, which showed small increased odds ratios.

CONCLUSIONS

While animal studies describe impaired neurocognitive outcomes following paternal exposure to recreational drugs, data in humans is currently lacking. Human studies require sound methodology in order to confirm findings on congenital malformations and childhood cancers. In addition, future neurocognitive studies require parental neurocognitive assessments to correct for confounding effects (i.e., role of genetics).

Delta-9 THC can be detected and quantified in the semen of men who are chronic users of inhaled cannabis

PURPOSE

The purpose of this proof-of-concept study was to determine whether delta-9-tetrahydrocannabinol (THC) and THC metabolites (11-OH THC and THC-COOH) can be detected in semen.

METHODS

Twelve healthy men aged 18-45 years who identified as chronic and heavy users of inhaled cannabis were recruited. THC and THC metabolite levels were measured in serum, urine, and semen of the participants. Semen analyses were performed. Serum reproductive hormones were measured.

RESULTS

The median age and BMI of participants were 27.0 years and 24.7 kg/m², respectively. Over half the participants were daily users of cannabis for over 5 years. Serum reproductive hormones were generally within normal ranges, except prolactin, which was elevated in 6 of 12 participants (mean 13.9 ng/mL). The median sperm concentration, motility, and morphology were 75.5 million/mL, 69.5%, and 5.5%, respectively. Urinary THC-COOH was detected in all 12 participants, and at least one serum THC metabolite was present in 10 of 12 participants. Two semen samples had insufficient volume to be analyzed. THC was above the reporting level of 0.50 ng/mL in the semen of two of the remaining participants. Seminal THC was moderately correlated with serum levels of THC (r = 0.66), serum 11-OH THC (r = 0.57), and serum THC-COOH (r = 0.67). Seminal delta-9 THC was not correlated with urinary cannabinoid levels or semen analysis parameters.

CONCLUSION

This is the first study to identify and quantify THC in human semen, demonstrating that THC can cross the blood-testis barrier in certain individuals. Seminal THC was found to be moderately correlated with serum THC and THC metabolites.

Genes and Diet in the Prevention of Chronic Diseases in Future Generations

Nutrition is a modifiable key factor that is able to interact with both the genome and epigenome to influence human health and fertility. In particular, specific genetic variants can influence the response to dietary components and nutrient requirements, and conversely, the diet itself is able to modulate gene expression. In this context and the era of precision medicine, nutrigenetic and nutrigenomic studies offer significant opportunities to improve the prevention of metabolic disturbances, such as Type 2 diabetes, gestational diabetes, hypertension, and cardiovascular diseases, even with transgenerational effects. The present review takes into account the interactions between diet, genes and human health, and provides an overview of the role of nutrigenetics, nutrigenomics and epigenetics in the prevention of non-communicable diseases. Moreover, we focus our attention on the mechanism of intergenerational or transgenerational transmission of the susceptibility to metabolic disturbances, and underline that the reversibility of epigenetic modifications through dietary intervention could counteract perturbations induced by lifestyle and environmental factors.

Paternal factors in neurodevelopmental toxicology: THC exposure of male rats causes long-lasting neurobehavioral effects in their offspring

The potential health risks of cannabis are of growing concern, including effects on reproduction and development. Extensive research has investigated risks associated with maternal exposure to THC during gestation and its impacts on the development of offspring, but little research has been done regarding paternal THC exposure effects prior to conception. We have previously found that paternal THC exposure in rats causes changes in sperm methylation. In an initial study we also showed that a 12-day paternal THC exposure prior to conception alters locomotor activity and impairs cognitive function of their offspring. This study investigated the cross-generational effects of chronic paternal THC exposure in rats (0, 2, or 4 mg/kg/day SC for 28 days) prior to mating with drug naïve females. The offspring of THC-exposed male rats had significant alterations in locomotor activity and cognitive function. Specifically, during adolescence there was significant locomotor hyperactivity in the offspring of males exposed to 2 mg/kg/day of THC. During the novel object recognition task, the controls maintained their relative preference for the novel object across the duration of the ten-min session while the rats whose fathers received THC (2 mg/kg/day) showed a significantly greater drop-off in interest in the novel object during the second half of the session. Learning in the radial-arm maze was significantly delayed in the offspring of males exposed to 4 mg/kg/day of THC. This study shows that premating chronic paternal THC exposure at multiple dose regimens can cause long-lasting detrimental behavioral effects in their offspring, including abnormal locomotor activity and impaired cognitive function. Future studies should investigate the underlying mechanisms driving these aberrant developmental outcomes and seek to identify possible treatments of alleviation in the presence of paternal THC exposure.

The Epigenetics of the Endocannabinoid System

The endocannabinoid system (ES) is a cell-signalling system widely distributed in biological tissues that includes endogenous ligands, receptors, and biosynthetic and hydrolysing machineries. The impairment of the ES has been associated to several pathological conditions like behavioural, neurological, or metabolic disorders and infertility, suggesting that the modulation of this system may be critical for the maintenance of health status and disease treatment. Lifestyle and environmental factors can exert long-term effects on gene expression without any change in the nucleotide sequence of DNA, affecting health maintenance and influencing both disease load and resistance. This potentially reversible "epigenetic" modulation of gene expression occurs through the chemical modification of DNA and histone protein tails or the specific production of regulatory non-coding RNA (ncRNA). Recent findings demonstrate the epigenetic modulation of the ES in biological tissues; in the same way, endocannabinoids, phytocannabinoids, and cannabinoid receptor agonists and antagonists induce widespread or gene-specific epigenetic changes with the possibility of trans-generational epigenetic inheritance in the offspring explained by the transmission of deregulated epigenetic marks in the gametes. Therefore, this review provides an update on the epigenetics of the ES, with particular attention on the emerging role in reproduction and fertility.

Cannabis use and the sperm epigenome: a budding concern?

The United States is swiftly moving toward increased legalization of medical and recreational cannabis. Currently considered the most commonly used illicit psychoactive drug, recreational cannabis is legal in 11 states and Washington, DC, and male use is an important and understudied concern. Questions remain, however, about the potential long-term consequences of this exposure and how cannabis might impact the epigenetic integrity of sperm in such a way that could influence the health and development of offspring. This review summarizes cannabis use and potency in the USA, provides a brief overview of DNA methylation as an epigenetic mechanism that is vulnerable in sperm to environmental exposures including cannabis, and summarizes studies that have examined the effects of parental exposure to cannabis or delta-9 tetrahydrocannabinol (THC, the main psychoactive component of cannabis) on the epigenetic profile of the gametes and behavior of offspring. These studies have demonstrated significant changes to the sperm DNA methylome following cannabis use in humans, and THC exposure in rats. Furthermore, the use of rodent models has shown methylation and behavioral changes in rats born to fathers exposed to THC or synthetic cannabinoids, or to parents who were both exposed to THC. These data substantiate an urgent need for additional studies assessing the effects of cannabis exposure on childhood health and development. This is especially true given the current growing state of cannabis use in the USA.

Prenatal Cannabinoid Exposure: Emerging Evidence of Physiological and Neuropsychiatric Abnormalities

Clinical reports of cannabis use prevalence during pregnancy vary widely from 3% to upwards of 35% in North America; this disparity likely owing to underestimates from self-reporting in many cases. The rise in cannabis use is mirrored by increasing global legalization and the overall perceptions of safety, even during pregnancy. These trends are further compounded by a lack of evidence-based policy and guidelines for prenatal cannabis use, which has led to inconsistent messaging by healthcare providers and medically licensed cannabis dispensaries regarding prenatal cannabis use for treatment of symptoms, such as nausea. Additionally, the use of cannabis to self-medicate depression and anxiety during pregnancy is a growing medical concern. This review aims to summarize recent findings of clinical and preclinical data on neonatal outcomes, as well as long-term physiological and neurodevelopmental outcomes of prenatal cannabis exposure. Although many of the outcomes under investigation have produced mixed results, we consider these data in light of the unique challenges facing cannabis research. In particular, the limited longitudinal clinical studies available have not previously accounted for the exponential increase in (-)-Δ9- tetrahydrocannabinol (Δ9-THC; the psychoactive compound in cannabis) concentrations found in cannabis over the past two decades. Polydrug use and the long-term effects of individual cannabis constituents [Δ9-THC vs. cannabidiol (CBD)] are also understudied, along with sex-dependent outcomes. Despite these limitations, prenatal cannabis exposure has been linked to low birth weight, and emerging evidence suggests that prenatal exposure to Δ9-THC, which crosses the placenta and impacts placental development, may have wide-ranging physiological and neurodevelopmental consequences. The long-term effects of these changes require more rigorous investigation, though early reports suggest Δ9-THC increases the risk of cognitive impairment and neuropsychiatric disease, including psychosis, depression, anxiety, and sleep disorders. In light of the current trends in the perception and use of cannabis during pregnancy, we emphasize the social and medical imperative for more rigorous investigation of the long-term effects of prenatal cannabis exposure.

Cannabinoid Receptors Signaling in the Development, Epigenetics, and Tumours of Male Germ Cells

Endocannabinoids are natural lipid molecules whose levels are regulated by specific biosynthetic and degradative enzymes. They bind to and activate two main cannabinoid receptors type 1 (CB₁) and type 2 (CB₂), and together with their metabolizing enzymes form the “endocannabinoid system” (ECS). In the last years, the relevance of endocannabinoids (eCBs) as critical modulators in various aspects of male reproduction has been pointed out. Mammalian male germ cells, from mitotic to haploid stage, have a complete ECS which is modulated during spermatogenesis. Compelling evidence indicate that in the testis an appropriate “eCBs tone”, associated to a balanced CB receptors signaling, is critical for spermatogenesis and for the formation of mature and fertilizing spermatozoa. Any alteration of this system negatively affects male reproduction, from germ cell differentiation to sperm functions, and might have also an impact on testicular tumours. Indeed, most of testicular tumours develop during early germ-cell development in which a maturation arrest is thought to be the first key event leading to malignant transformation. Considering the ever-growing number and complexity of the data on ECS, this review focuses on the role of cannabinoid receptors CB₁ and CB₂ signaling in male germ cells development from gonocyte up to mature spermatozoa and in the induction of epigenetic alterations in these cells which might be transmitted to the progeny. Furthermore, we present new evidence on their relevance in testicular cancer.

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.