Effects of paternal alcohol consumption on pregnancy outcome in rats

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.

Paternal Diet before Conception and Its Social Determinants in the Elfe Cohort

This study aimed to characterize paternal diet during the peri-conception period and its associated characteristics. These cross-sectional analyses were based on 998 fathers from the French nationwide ELFE birth cohort recruited in 2011. Fathers’ diet before mothers’ pregnancies was assessed by a 46-item food frequency questionnaire. Six exploratory dietary patterns were identified by principal component analysis: “Diverse diet”, “Balanced”, “Alcohol”, “Snacking”, “Bread and cheese”, and “Processed products”. Older age was related to higher scores for the “Balanced”, “Alcohol”, and “Snacking” patterns, and high education level with high scores on the “Balanced” pattern and low scores on the “Processed products” pattern. Unemployment and having a first child were related to high scores on the “Alcohol” pattern. Smoking was positively related to “Alcohol” and “Processed products” patterns. A restrictive diet was associated with high scores on the “Balanced” and “Processed products” patterns and low scores on “Alcohol”, “Snacking”, and “Bread and cheese” patterns. Maternal dietary patterns, identified in a previous analysis, were moderately and positively related to the similar patterns among fathers. These findings are important for screening fathers at risk of a suboptimal diet and for accounting for this factor in future studies to examine the specific influence of paternal diet on a child’s health and development.

Transgenerational Abnormalities Induced by Paternal Preconceptual Alcohol Drinking: Findings from Humans and Animal Models

Alcohol consumption during pregnancy and lactation is a widespread preventable cause of neurodevelopmental impairment in newborns. While the harmful effects of gestational alcohol use have been well documented, only recently, the role of paternal preconceptual alcohol consumption (PPAC) prior to copulating has drawn specific epigenetic considerations. Data from human and animal models have demonstrated that PPAC may affect sperm function, eliciting oxidative stress. In newborns, PPAC may induce changes in behavior, cognitive functions, and emotional responses. Furthermore, PPAC may elicit neurobiological disruptions, visuospatial impairments, hyperactivity disorders, motor skill disruptions, hearing loss, endocrine, and immune alterations, reduced physical growth, placental disruptions, and metabolic alterations. Neurobiological studies on PPAC have also disclosed changes in brain function and structure by disrupting the growth factors pathways. In particular, as shown in animal model studies, PPAC alters brain nerve growth factor (NGF) and brainderived neurotrophic factor (BDNF) synthesis and release. This review shows that the crucial topic of lifelong disabilities induced by PPAC and/or gestational alcohol drinking is quite challenging at the individual, societal, and familial levels. Since a nontoxic drinking behavior before pregnancy (for both men and women), during pregnancy, and lactation cannot be established, the only suggestion for couples planning pregnancies is to completely avoid the consumption of alcoholic beverages.

Mapping the past, present and future research landscape of paternal effects

BACKGROUND

Although in all sexually reproducing organisms an individual has a mother and a father, non-genetic inheritance has been predominantly studied in mothers. Paternal effects have been far less frequently studied, until recently. In the last 5 years, research on environmentally induced paternal effects has grown rapidly in the number of publications and diversity of topics. Here, we provide an overview of this field using synthesis of evidence (systematic map) and influence (bibliometric analyses).

RESULTS

We find that motivations for studies into paternal effects are diverse. For example, from the ecological and evolutionary perspective, paternal effects are of interest as facilitators of response to environmental change and mediators of extended heredity. Medical researchers track how paternal pre-fertilization exposures to factors, such as diet or trauma, influence offspring health. Toxicologists look at the effects of toxins. We compare how these three research guilds design experiments in relation to objects of their studies: fathers, mothers and offspring. We highlight examples of research gaps, which, in turn, lead to future avenues of research.

CONCLUSIONS

The literature on paternal effects is large and disparate. Our study helps in fostering connections between areas of knowledge that develop in parallel, but which could benefit from the lateral transfer of concepts and methods.

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.

Impact of nicotine, alcohol, and cocaine exposure on germline integrity and epigenome

Converging evidence suggests that parental exposure to drugs of abuse can affect offspring phenotypes. The impacts of drug abuse on germ cell quality may mediate multigenerational and transgenerational inheritance, although biological pathways underlying this mode of inheritance are not yet characterized. Germline epigenetic marks are modified by drug exposure and have emerged as promising mechanistic candidates in recent work. Drug exposure also impacts overall germline integrity and reproductive functioning, although the role of these consequences in multi/transgenerational inheritance is unclear. This review synthesizes literature on effects of exposure to alcohol, cocaine, and nicotine on the germline with a focus on epigenetic modifications following drug exposure and broader impacts on germline integrity and reproductive functioning. We discuss potential interactions between reproductive functioning, germline integrity, and germline epigenome/transcriptome in pathways underlying multi/transgenerational inheritance. We find that existing data may support independent or interactive contributions of these germline impacts on offspring phenotypes in a manner that may mediate multi/transgenerational inheritance.

Multi-, Inter-, and Transgenerational Effects of Drugs of Abuse on Behavior

Transgenerational epigenetic inheritance is a burgeoning field that has recently garnered much attention. A growing body of evidence identifies behavioral phenotypes associated with inter-, multi-, and transgenerational studies following a wide variety of parental exposures. This chapter in current topics in behavioral neurogenomics examines the evidence for the presence of behavioral phenotypes and, in particular, the varied and often opposite behavioral responses observed with protocol shifts. Effects following parental exposure to drugs of abuse are used as an example of the wide range of behavioral outcomes and the variability associated with these multiple generation studies. The behavioral phenotypes associated with drug exposure are reviewed in depth.

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.

Offspring of male rats exposed to binge alcohol exhibit heightened ethanol intake at infancy and alterations in T-maze performance

Alcohol use is associated with a variety of negative consequences, including heightened likelihood of cognitive impairment, proclivity to alcohol use disorders (AUD), and alterations in the drinker's offspring. Children and rodents exposed to alcohol during pregnancy, or those whose fathers consumed alcohol prior to mating, often exhibit neurodevelopmental, physiological, and behavioral deficits. The present study assessed cognitive function and alcohol intake in male and female rats that were offspring of alcohol-exposed fathers. Adult male rats were exposed to alcohol or vehicle (0.0 or 2.0 g/kg, respectively; twice daily for 2 days followed by a rest day, for a total of eight alcohol or vehicle exposure days), or were left untreated and then mated with non-manipulated females. The offspring were assessed for alcohol intake, via intraoral infusion, followed by cognitive assessment via an alternating T-maze task. The results indicated that paternal ethanol exposure, prior to breeding, resulted in offspring that consumed significantly more ethanol than vehicle or untreated controls. Furthermore, the offspring of alcohol-exposed fathers exhibited a significant failure to initiate and complete the T-maze performance tests. Although, when they did engage in the tests they performed at the level of controls (i.e., 80% correct). The present results add to a growing body of literature suggesting that paternal pre-conception alcohol exposure can have deleterious effects on the offspring.

Epigenetic effects of paternal cocaine on reward stimulus behavior and accumbens gene expression in mice

Paternal cocaine use causes phenotypic alterations in offspring behavior and associated neural processing. In rodents, changes in first generation (F1) offspring include drug reward behavior, circadian timing, and anxiety responses. This study, utilizing a murine (C57BL/6J) oral cocaine model, examines the effects of paternal cocaine exposure on fundamental characteristics of offspring reward responses, including: 1) the extent of cocaine-induced effects after different durations of sire drug withdrawal; 2) sex- and drug-dependent differences in F1 reward preference; 3) effects on second generation (F2) cocaine preference; and 4) corresponding changes in reward area (nucleus accumbens) mRNA expression. We demonstrate that paternal cocaine intake over a single ˜40-day spermatogenic cycle significantly decreased cocaine (but not ethanol or sucrose) preference in a sex-specific manner in F1 mice from sires mated 24 h after drug withdrawal. However, F1 offspring of sires bred 4 months after withdrawal did not exhibit altered cocaine preference. Altered cocaine preference also was not observed in F2's. RNASeq analyses of F1 accumbens tissue revealed changes in gene expression in male offspring of cocaine-exposed sires, including many genes not previously linked to cocaine addiction. Enrichment analyses highlight genes linked to CNS development, synaptic signaling, extracellular matrix, and immune function. Expression correlation analyses identified a novel target, Fam19a4, that may negatively regulate many genes in the accumbens, including genes already identified in addiction. Collectively, these results reveal that paternal cocaine effects in F1 offspring may involve temporally limited epigenetic germline effects and identify new genetic targets for addiction research.

Reduced alcohol-seeking in male offspring of sires exposed to alcohol self-administration followed by punishment-imposed abstinence

Emerging evidence has demonstrated that paternal alcohol use can modify the behavior of offspring, particularly male offspring. However, preclinical studies to date have not used voluntary self-administration of alcohol to examine alcohol-related behaviors in offspring. Here, we tested the hypothesis that paternal alcohol self-administration followed by punishment-imposed abstinence alters alcohol consumption and seeking in male offspring. Male inbred alcohol preferring iP rats were trained to self-administer alcohol in one context followed by punishment-imposed suppression of alcohol-seeking in a different context using contingent footshock. Following this, all rats were bred with alcohol naïve female iP rats. F1 offspring were then trained to self-administer alcohol in an identical operant paradigm as sires. Alcohol intake and self-administration behaviors of alcohol-sired offspring were compared to control-sired offspring whose fathers had not been exposed to the alcohol operant conditioning experience. We found that paternal alcohol self-administration reduced context-induced relapse to alcohol-seeking in male offspring. These findings indicate that voluntary paternal alcohol experience, operant conditioning, and punishment can result in intergenerational changes in offspring behavior, and that this effect may protect against the vulnerability to relapse after alcohol use. We also noted reduced alcohol responding in the punishment-associated context in alcohol-sired offspring, suggesting altered perception of punishment sensitivity or the anxiogenic response to footshock. Collectively, these findings provide evidence that paternal alcohol abuse can impact alcohol-related behaviors in male offspring.

Alcohol effects on the epigenome in the germline: Role in the inheritance of alcohol-related pathology

Excessive alcohol exposure has severe health consequences, and clinical and animal studies have demonstrated that disruptions in the epigenome of somatic cells, such as those in brain, are an important factor in the development of alcohol-related pathologies, such as alcohol-use disorders (AUDs) and fetal alcohol spectrum disorders (FASDs). It is also well known that alcohol-related health problems are passed down across generations in human populations, but the complete mechanisms for this phenomenon are currently unknown. Recent studies in animal models have suggested that epigenetic factors are also responsible for the transmission of alcohol-related pathologies across generations. Alcohol exposure has been shown to induce changes in the epigenome of sperm of exposed male animals, and these epimutations are inherited in the offspring. This paper reviews evidence for multigenerational and transgenerational epigenetic inheritance of alcohol-related pathology through the germline. We also review the literature on the epigenetic effects of alcohol exposure on somatic cells in brain, and its contribution to AUDs and FASDs. We note gaps in knowledge in this field, such as the lack of clinical studies in human populations and the lack of data on epigenetic inheritance via the female germline, and we suggest future research directions.

Drinking beyond a lifetime: New and emerging insights into paternal alcohol exposure on subsequent generations

Alcohol-use disorder (AUD) is prevalent and associated with substantial socioeconomic costs. While heritability estimates of AUD are ∼50%, identifying specific gene variants associated with risk for AUD has proven challenging despite considerable investment. Emerging research into heritability of complex diseases has implicated transmission of epigenetic variants in the development of behavioral phenotypes, including drug preference and drug-induced behavior. Several recent rodent studies have specifically focused on paternal transmission of epigenetic variants, which is especially relevant because sires are not present for offspring rearing and changes to offspring phenotype are assumed to result from modifications to the sperm epigenome. While considerable interest in paternal transmission of epigenetic variants has emerged recently, paternal alcohol exposures have been studied for 30+ years with interesting behavioral and physiologic effects noted on offspring. However, only recently, with improvements in technology to identify epigenetic modifications in germ cells, has it been possible to identify mechanisms by which paternal ethanol exposure alters offspring behavior. This review presents an overview of epigenetic inheritance in the context of paternal ethanol exposure and suggests future studies to identify specific effects of paternal ethanol exposure on offspring behavior and response to ethanol.

Multigenerational and transgenerational inheritance of drug exposure: The effects of alcohol, opiates, cocaine, marijuana, and nicotine

Familial inheritance of drug abuse is composed of both genetic and environmental factors. Additionally, epigenetic transgenerational inheritance may provide a means by which parental drug use can influence several generations of offspring. Recent evidence suggests that parental drug exposure produces behavioral, biochemical, and neuroanatomical changes in future generations. The focus of this review is to discuss these multigenerational and transgenerational phenotypes in the offspring of animals exposed to drugs of abuse. Specifically, changes found following the administration of alcohol, opioids, cocaine, marijuana, and nicotine will be discussed. In addition, epigenetic modifications to the genome following administration of these drugs will be detailed as well as their potential for transmission to the next generation.

Chronic exposure to ethanol of male mice before mating produces attention deficit hyperactivity disorder-like phenotype along with epigenetic dysregulation of dopamine transporter expression in mouse offspring

Preconception exposure to EtOH through the paternal route may affect neurobehavioral and developmental features of offspring. This study investigates the effects of paternal exposure to EtOH before conception on the hyperactivity, inattention, and impulsivity behavior of male offspring in mice. Sire mice were treated with EtOH in a concentration range approximating human binge drinking (0-4 g/kg/day EtOH) for 7 weeks and mated with untreated females mice to produce offspring. EtOH exposure to sire mice induced attention deficit hyperactivity disorder (ADHD)-like hyperactive, inattentive, and impulsive behaviors in offspring. As a mechanistic link, both protein and mRNA expression of dopamine transporter (DAT), a key determinant of ADHD-like phenotypes in experimental animals and humans, were significantly decreased by paternal EtOH exposure in cerebral cortex and striatum of offspring mice along with increased methylation of a CpG region of the DAT gene promoter. The increase in methylation of DAT gene promoter was also observed in the sperm of sire mice, suggesting germline changes in the epigenetic methylation signature of DAT gene by EtOH exposure. In addition, the expression of two key regulators of methylation-dependent epigenetic regulation of functional gene expression, namely, MeCP2 and DNMT1, was markedly decreased in offspring cortex and striatum sired by EtOH-exposed mice. These results suggest that preconceptional exposure to EtOH through the paternal route induces behavioral changes in offspring, possibly via epigenetic changes in gene expression, which is essential for the regulation of ADHD-like behaviors.

The impact of exposure to addictive drugs on future generations: Physiological and behavioral effects

It is clear that both genetic and environmental factors contribute to drug addiction. Recent evidence indicating trans-generational influences of drug abuse highlight potential epigenetic factors as well. Specifically, mounting evidence suggests that parental ingestion of abused drugs influence the physiology and behavior of future generations even in the absence of prenatal exposure. The goal of this review is to describe the trans-generational consequences of preconception exposure to drugs of abuse for five major classes of drugs: alcohol, nicotine, marijuana, opioids, and cocaine. The potential epigenetic mechanisms underlying the transmission of these phenotypes across generations also are detailed. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Paternal dietary restriction affects progeny fat content in Caenorhabditis elegans

Epidemiological data from human populations and few reports in rodents suggested that the paternal diet affects offspring adiposity and its related diseases. We tested whether this nongenetic and intergenerational inheritance depends on paternal treatment dose. Using the model organism Caenorhabditis elegans, males undergoing several dietary restriction regimes were crossed with ad libitum fed females. We found an inverted U-shaped relationship between the extent of paternal dietary restriction and the level of fat content of progeny. The relationship was evident in both sexes. Body proportions were not affected in offspring. Overall, our findings extent the concept of developmental and adaptive plasticity to include the extent of paternal food consumption in the origin of phenotypic alterations.

The effect of preconception paternal alcohol exposure on epigenetic remodeling of the h19 and rasgrf1 imprinting control regions in mouse offspring

Imprinted loci play a critical role in fetal development. Their expression is often regulated by CCCTC-binding factor (CTCF) protein binding at imprinting control regions (ICRs). Prenatal alcohol exposure has been shown to reduce global DNA methylation in the developing mouse fetus. This study explored the effect of preconception paternal alcohol exposure on DNA methylation at two paternally methylated ICRs (H19 and Rasgrf1) in the sperm of exposed males and somatic DNA of sired offspring. Significant reductions at the H19 CTCF 1 (p = 0.0027) and CTCF 2 (p = 0.0009) binding sites were observed in the offspring of ethanol-treated sires, which was significantly correlated with reduced weight at postnatal days 35–42 (p < 0.05). As birth weight was unaffected and growth was only delayed during the postnatal weaning period, with subsequent re-convergence, we hypothesize that this may be the result of a mental deficit causing delayed establishment of independent feeding following weaning and would explain why this effect is transient. No difference in DNA methylation was observed in the sperm of alcohol-exposed males, indicating that the transmission of the epigenetic signal at conception is not due to altered methylation, but may be the result of an RNA-mediated mechanism or altered chromatin remodeling.

Epigenetics and the origins of paternal effects

Though there are multiple routes through which parents can influence their offspring, recent studies of environmentally induced epigenetic variation have highlighted the role of non-genomic pathways. In addition to the experience-dependent modification of DNA methylation that can be achieved via mother-infant interactions, there has been increasing interest in the epigenetic mechanisms through which paternal influences on offspring development can be achieved. Epidemiological and laboratory studies suggest that paternal nutritional and toxicological exposures as well as paternal age and phenotypic variation can lead to variations in offspring and, in some cases, grand-offspring development. These findings suggest a potential epigenetic germline inheritance of paternal effects. However, it may be important to consider the interplay between maternal and paternal influences as well as the experimental dissociation between experience-dependent and germline transmission when exploring the role of epigenetic variation within the germline as a mediator of these effects. In this review, we will explore these issues, with a particular focus on the potential role of paternally induced maternal investment, highlight the literature illustrating the transgenerational impact of paternal experiences, and discuss the evidence supporting the role of epigenetic mechanisms in maintaining paternal effects both within and across generations.

Genetic and epigenetic insights into fetal alcohol spectrum disorders

The magnitude of the detrimental effects following in utero alcohol exposure, including fetal alcohol syndrome and other fetal alcohol spectrum disorders (FASD), is globally underestimated. The effects include irreversible cognitive and behavioral disabilities as a result of abnormal brain development, pre- and postnatal growth retardation and facial dysmorphism. Parental alcohol exposure and its effect on offspring has been recognized for centuries, but only recently have we begun to gain molecular insight into the mechanisms involved in alcohol teratogenesis. Genetic attributes (susceptibility and protective alleles) of the mother and the fetus contribute to the risk of developing FASD and specific additional environmental conditions, including malnutrition, have an important role. The severity of FASD depends on the level of alcohol exposure, the developmental stage at which exposure occurs and the nature of the exposure (chronic or acute), and although the most vulnerable period is during the first trimester, damage can occur throughout gestation. Preconception alcohol exposure can also have a detrimental effect on the offspring. Several developmental pathways are affected in FASD, including nervous system development, growth and remodeling of tissues, as well as metabolic pathways that regulate glucocorticoid signaling and balanced levels of retinol, insulin and nitric oxide. A body of knowledge has accumulated to support the role of environmentally induced epigenetic remodeling during gametogenesis and after conception as a key mechanism for the teratogenic effects of FASD that persist into adulthood. Transgenerational effects are likely to contribute to the global burden of alcohol-related disease. FASD results in lifelong disability and preventative programs should include both maternal alcohol abstention and preconception alcohol avoidance.

Fetal alcohol spectrum disorders: the epigenetic perspective

Ethanol is a classic teratogen capable of inducing a wide range of developmental abnormalities. Studies in animal models suggest that differences in timing and dosage underlie this variability, with three particularly important developmental periods: preconception, preimplantation, and gastrulation. These periods of teratogenesis correlate with peak periods of epigenetic reprogramming which, together with the evidence that ethanol interferes with one-carbon metabolism, DNA methylation, histone modifications, and noncoding RNA, suggests an important role for epigenetic mechanisms in the etiology of fetal alcohol spectrum disorders (FASDs). In addition to a number of testable hypotheses, an epigenetic model suggests that the concept of a "fetal alcohol spectrum" should be expanded to include "preconceptional effects." This proposal has important public health implications, highlighting the urgency of research into the epigenetic basis of FASDs.

Acute paternal alcohol use affects offspring development and adult behavior

Swiss Webster pups were fathered by sires given either an acute dose of alcohol (alcohol-sired) or saline (saline-sired) 12-24 h before mating. The same sires were used to father both groups of pups. Alcohol-sired pups were significantly lighter at birth and for the following three weeks than were saline-sired pups. Significantly more pups were fathered by saline-exposed sires, and dams carrying those pups had significantly longer gestations than those carrying pups of alcohol-using sires. More runts were born to the alcohol-sired group, and more pups in that group died over the next three weeks than in the saline-sired group. Significantly more pups in the saline-sired group achieved such developmental milestones as surface righting, clinging, the tail-pull reflex, rotation, linear movement and climbing an inclined surface earlier than did alcohol-sired pups. As adults, animals from the alcohol-sired group showed significantly less risk assessment behavior and longer latencies to such behaviors as stretched attention, flatback, freezing and defensive burying than did the saline-sired animals. Alcohol-sired animals contacted the stimulus object in the risk assessment test significantly sooner and more often than did the saline-sired group. In tests of aggression, alcohol-sired male offspring showed more frequent aggressive behaviors such as on-top, lateral attacks and jump-attacks, and significantly fewer defensive/fearful behaviors such as piloerection, tail rattling and jump-escape. This pattern of results suggests that exposure of the sire to one acute dose of alcohol before insemination caused some early developmental delays and that alcohol-sired animals are less fearful and more aggressive as adults than saline-sired animals.

Neurobehavioral effects in rat pups whose sires were exposed to alcohol

Developmental neurobehavioral effects associated with maternal exposure to alcohol during pregnancy are well described, but little is known about the effects of paternal exposure prior to conception. Using a quasi-experimental, within-subjects design, neurobehavioral outcomes (reflex acquisition, activity, gait) and cerebral cortical layer thickness were assessed in Sprague-Dawley rat pups from breeding pairs where the sires were exposed to alcohol. Comparisons were made on the basis of the timing of conception relative to alcohol exposure: phase 1 (controls), prior to initiation of alcohol exposure; phase 2, during the period of treatment with 20% alcohol; and phase 3, following cessation of alcohol exposure. Phase 2 and 3 pups were noted to attain negative geotaxis and reflex suspension benchmarks earlier than control pups and to have more difficulty with balance. Phase 3 pups were noted to attain righting reflex earlier than controls. In addition, phase 3 pups demonstrated increased levels of reverse maze activity and a shorter and narrower gait. Brain morphometry revealed thickening of cortical sections I-IV and V-VI resulting in overall cortical enlargement in both phase 2 and 3 pups. Further analysis of phase 2 and 3 subphases based on the presumed stages of the spermatogenic cycle during which sires were exposed to alcohol revealed significant differences in maze activity, reflex acquisition, and gait length. These findings suggest pre-conception male exposure to alcohol may have an effect on the offspring and the extent of the effects may vary with the timing of alcohol exposure relative to conception.

Peripubertal paternal EtOH exposure

Fetal alcohol syndrome usually implies effects on the offspring of maternal EtOH consumption during gestation, with fewer reports addressing the impact of paternal exposure on the progeny. One previous report has dealt with the impact of EtOH exposure on peripubertal male rats as a model of teenage drinking and the deleterious effects on the offspring. We report here findings examining the effect of 2 mo of EtOH feeding on male animals as they progressed through puberty on their ability to impregnate EtOH-naive female rats and characteristics of the subsequent litters. The EtOH-imbibing fathers weighed significantly less than pairfed controls and animals ingesting a non-EtOH liquid diet ad libitum. Nevertheless, they were able to mate successfully, although fecundity was significantly reduced. The number of successful pregnancies, defined as carried to term, was diminished from 92% in controls to 75% in EtOH-fed animals (p < 0.05). There was increased paternal testicular oxidative injury demonstrated by enhanced lipid peroxidation, protein oxidation, and decreased ratio of reduced to oxidized glutathione. The litter size of the EtOH-exposed males was reduced by 46%. The average litter size was 12.4+/-1.5 pups/litter in ad libitum animals, virtually identical to the 12.5+/-0.6 pups/litter in the pair fed controls. This is in sharp contrast to the 6.7+/-0.1 pups/litter from the paternal EtOH matings (p < 0.001). There was an increase in the average individual weight of pup offspring of paternally EtOH-exposed animals (p < 0.01 vs pair-fed controls and p < 0.05 vs ad libitum). Curiously, the male-to-female pup ratio was altered with a higher preponderance of male offspring from EtOH-fed fathers. There were no gross malformations noted among the pups. Insulin-like growth factor-1 levels in the pups at 10 d of age were unaltered between the groups. However, leptin was significantly elevated in the EtOH offspring. It appears that chronic EtOH exposure in the peripubertal fathers subsequently decreases fecundity and that this may be mediated by testicular oxidative injury, perhaps leading to accelerated germ cell apoptosis.

Second generation effects of maternal alcohol consumption during pregnancy in rats

1. Previous studies have shown that when female rats are administered alcohol during pregnancy there are adverse effects on their progeny, including decreased birth weight and delayed neuromotor development. Evidence from several sources suggests alcohol exposure may contribute to cytogenetic abnormalities, suggesting the possibility of cross generational effects from prenatal exposure. 2. On day 1 of gestation female rats were randomly allocated to the Alcohol group, which received a liquid diet containing 5% (v/v) ethanol solution until parturition, the Sucrose control group, which received an identical diet, except that sucrose had been isocalorically substituted for ethanol, or the Chow control, which received standard laboratory chow. 3. When the offspring of these rats reached adulthood they were mated with drug-free rats and the development of their offspring was monitored. 4. In comparison with female pups whose sires had been exposed to alcohol in utero, the weight of pups descended from fetally-exposed dams increased more slowly from day 1 to day 7. 5. At five days of age, significant differences favouring the two control groups were found in latency to right for pups descended from fetally-exposed dams. 6. These data suggest that the effects of prenatal exposure to alcohol are more pervasive than previously thought and affect female pups to a greater extent than males.

Paternal alcohol exposure: developmental and behavioral effects on the offspring of rats

The effect of paternal alcohol exposure on neurochemical and behavioral parameters was investigated using as a model system glial cells derived from newborn rat brain and cultured for 4 weeks. The total brain neurochemical parameters from rats born to mothers sired by an alcohol treated father were also investigated. Enzymatic markers of nerve cell development (enolase isoenzymes and glutamine synthetase) and the defense system (superoxide dismutase) against free radicals formed during alcohol degradation were measured in order to evaluate nerve cell damage. Behavioral locomotor tests (open-field, novelty-seeking, light/dark) were carried out to show long-lasting effects of paternal alcoholization on the offspring. Behavioral and developmental alterations were found until 1 year of age in the offspring and a significant growth retardation was observed in the males. Our results suggest that paternal alcohol exposure produces developmental and behavioral effects in the offspring. The consequence of either alcohol withdrawal during stage one spermatogenesis, or maternal diet supplementation with manganese during pregnancy were investigated. It was observed that some of the effects of paternal alcohol exposure on the offspring may be reversed by these treatments.

Effect of paternal alcohol consumption before conception on infant birth weight. ALSPAC Study Team. Avon Longitudinal Study of Pregnancy and Childhood

Previous studies of paternal drinking and fetal growth in both animals and human have produced conflicting results. We evaluated the association between paternal drinking before conception and infant birth weight in a cohort of 9,845 liveborn singleton infant born to couples who participated in the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC), ALSPAC is a population-based cohort study in which women and their partners completed several self-administered questionnaires over the course of pregnancy. Of participating male partners, 20% were reportedly daily drinkers before conception, and 8% were considered moderately heavy or very heavy drinkers. Because maternal drinking is highly correlated with paternal, the analyses were stratified by maternal drinking in early pregnancy. We also adjusted for confounders and known predictors of birth weight. For all three maternal drinking strata, all adjusted mean differences in birth weight across levels of paternal drinking were similar, and all had confidence intervals that included zero. These findings persisted even after adjustment for other covariates and after stratification by parental smoking, race, and education. The size of the ALSPAC cohort, the large number of heavy drinkers, and the availability of data from the fathers themselves support the conclusion that paternal drinking before conception is not an important predictor of infant birth weight in humans.

Acute treatment of paternal alcohol exposure produces malformations in offspring

Male rats were intubated only once with either 6, 4, 2, or 0 g/kg alcohol. Food was removed from all animals for several hours after intubation. Males were bred with a single female until sperm was observed in the vaginal smear, for up to a maximum of 7 days after treatment. Females were sacrificed on gestation day 20. There were no significant effects on mating, fecundity, or litter size, but there were significant dose-response increases in "runts" and significant linear associations in the number of malformations in alcohol-sired offspring. A second study using the same methodology found similar results. The results indicate that a single acute treatment with alcohol just prior to breeding may have a significant effect on offspring.

Paternal exposures: impact on reproductive and developmental outcome. An overview

Experimental and epidemiologic investigations document the adverse consequences of an array of paternal exposures on the development of subsequent offspring. Male-mediated abnormalities have been reported after exposure to therapeutic and recreational drugs, to chemicals in the workplace and environment and to ionizing radiation. The impact on progeny outcome includes: an increase in congenital malformations, spontaneous abortions, fetal resorptions; low birth weight; increase in childhood cancers; developmental, neurobehavioral, neuroendocrine, neurochemical abnormalities; effects in F2 generation progeny. Fertility is often unaffected. The comparative influence of genetic, epigenetic and nongenetic mechanisms in the etiology of paternally-mediated adverse outcomes is unknown. There is no a priori reason to assume that male-mediated effects are limited to the agents studied to date. The broad spectrum of alterations recorded after exposure to a variety of unrelated agents suggests the need for a more focused effort and multidisciplinary exploration of the potential impact of the male parent on reproductive outcome.

A surprising effect of paternal alcohol treatment on rat fetuses

Male rats were intubated with either 5, 2.5, or 0 g/kg alcohol. Animals in the latter two groups were pairfed to those in the 5 g/kg group. A fourth group of males was not treated and was fed ad lib. Males were bred once after 3 weeks of intubation and twice after 9 weeks of intubation. Females in the first two breedings were sacrificed prior to delivery, whereas females in the last breeding were allowed to deliver their litters. There were no significant decreases in male fertility or litter size, but fecundity was reduced in females bred to alcohol-treated males when all breedings were pooled. Newborn weights (third breeding) were not significantly affected by paternal alcohol treatment, but fetal weights in the first two breedings were significantly increased in association with paternal alcohol treatment. There was also an alcohol-related increase in the number of male fetuses in breeding one, and an increase in placental weights in breeding two; the placental index (placental weight/fetal weight) was also decreased by paternal alcohol treatment for fetuses in the second breeding. These results suggest paternal alcohol treatment can have effects on offspring body weights, which are not observable once females have given birth.

Effects of physostigmine on male offspring sired by alcohol-treated fathers

Male rats were intubated with either 3, 2, or 0 g/kg alcohol, twice daily, for 7 months and were then bred to untreated females. At 18 and 58-62 days of age, male offspring were tested for passive avoidance learning. At 82-88 days of age, another group of male offspring were tested for open field activity after receiving 0, 0.1, or 0.4 mg/kg physostigmine, a cholinesterase inhibitor. Offspring sired by alcohol-treated fathers required more trials to reach criterion in the passive avoidance task at 18 days of age, but did not differ significantly at 58-62 days of age. These offspring were more active in the open field compared with controls after receiving vehicle, but did not differ from controls after receiving physostigmine. These results suggest animals sired by alcohol-treated fathers are more active than controls, and this effect is cholinergically mediated. These results are of interest because of their possible relevance to the hyperactivity noted in children born to alcoholic fathers.

Paternal alcohol exposure and hyperactivity in rat offspring: effects of amphetamine

Locomotor activity of rat offspring sired by fathers treated with 0, 2 or 3 g/kg of alcohol twice daily was assessed at 21, 42 and 90 days of age. Fathers treated with the two lower doses were pair-fed to those treated with the highest dose. Offspring of nontreated ad-lib fed fathers were also evaluated to determine the possible role of paternal stress associated with intubation and pair-feeding. The behavioral response to amphetamine was also examined in 90-day-old male offspring. Paternal alcohol treatment resulted in increased activity at each age for 3 g/kg offspring compared to pair-fed controls. Ad-lib offspring did not differ from 0 g/kg controls at 21 and 42 days of age. The significant effect of paternal alcohol treatment on offspring activity at 90 days, including a significant linear paternal effect, occurred when all amphetamine-treated groups were pooled. The alcohol x amphetamine interaction was not significant, but a significant linear paternal alcohol x linear amphetamine interaction indicated that the paternal alcohol effect on activity was differentially responsive to amphetamine. Subsequent analysis of this interaction indicated a significant linear paternal alcohol trend only at the high dose of amphetamine. These results corroborate a previous report of increased activity on the part of offspring sired by fathers treated with alcohol. The presence of a differential effect of amphetamine suggests that the paternal effect on activity may be mediated by catecholaminergic activity. The absence of significant differences between ad lib and 0 g/kg pair-fed controls indicates that paternal stress/undernutrition does not significantly affect offspring activity.

Rat offspring sired by males treated with alcohol

Male rats were intubated twice daily with either 2 or 3 g/kg of alcohol for nine weeks and were then bred to untreated females. Control animals were intubated with vehicle (distilled water). Controls and 2-g/kg males were pair-fed to 3-g/kg males. A fourth group served as a nonintubated, ad lib control. Male fertility was not affected by alcohol. Mean birth weights were not affected by paternal alcohol treatment, but there was a significant increase in the number of "runts" (< 5.5 g at birth) in the 3-g/kg paternal group. There was also a decrease in the percent of males per litter sired by alcohol-treated fathers. Adrenal weights were increased at birth and spleen weights were decreased at 21 days of age in these offspring as well. These results indicate the potential of paternal alcohol consumption for significantly altering stature and organs in offspring.

Genomic imprinting: implications for behavioral genetics

In recent years it has become apparent that the parental origin of genetic material has an impact on gene expression and this effect has become known as genomic imprinting. The evidence for the influence of genomic imprinting on behavior and in the etiology of certain neurobehavioral disorders is discussed. The possibilities for a role for genomic imprinting in the inheritance of behaviors related to alcohol abuse and alcoholism and in the paternal alcohol syndrome are also explored.

Association of paternal alcohol use with gestational age and birth weight

Paternal alcohol use has been associated with a number of adverse reproductive outcomes in laboratory animals and there is one epidemiologic report of a detrimental effect on infant birth weight. To expand the epidemiologic evidence, data from the Child Health and Development Studies were analyzed. Data collected from the onset of prenatal care in 10,232 women enrolled in the Kaiser Foundation Health Plan and residing in the San Francisco East Bay area between June 1959 and September 1966 were available, including information on the mother's report of paternal alcohol consumption and a number of potential confounders. Pregnancy outcomes included preterm delivery (< 37 weeks completed gestation), moderately low birth weight (1,501-2,500 g), very low birth weight (< or = 1,500 g), small-for-gestational-age (< 10th percentile of weight for gestational age), and mean birth weight. Paternal alcohol use, analyzed in intervals from 0 to 2.0 or more drinks per day, showed no association with any of the outcomes of interest. Adjusted prevalence odds ratios ranged from 0.7 to 1.5, with no indication of a monotonic dose-response gradient. Mean birth weight was also virtually unrelated to paternal alcohol use. Compared with the earlier report, this population had a very modest level of alcohol consumption. Nonetheless, within the range that was studied there appears to be no association between paternal alcohol use and birth outcome.

Effects of prepregnancy ethanol on neuromotor development, activity, and learning

This study examines the behavioral consequences of both long-term chronic and acute high-dose administration of ethanol before pregnancy. Female rats were assigned to one of five conditions: a self-administered liquid diet with 35% ethanol-derived calories, a pair-fed liquid diet with 0% ethanol-derived calories, a gavage intubation with 4 g/kg ethanol, a gavage intubation control, or a standard lab chow control. Offspring were weighed at various ages and tested for neuromotor development, activity, and learning a Morris maze water task. Offspring of mothers in the high-dose condition were hyperactive as juveniles but not as adults. Hyperactivity was not seen in the low-dose chronic ethanol condition, contrary to previous reports. Neither ethanol administration paradigm was associated with learning deficits. Prepregnancy stress effects were apparent from both the restricted liquid diet feeding and the gavage treatment on neuromotor development. A possible mechanism for the effects of prepregnancy ethanol treatment is linked to ethanol's potential to alter hormone levels. Since hormones are directly responsible for the maturation of the egg, hormonal imbalances as a result of ethanol exposure may result in developmental deficiencies in the offspring.

Evaluation of the co-mutagenicity of ethanol and Δ9-tetrahydrocannabinol with Trenimon

The mutagenic potential of chronic treatments of male CF-1 mice with ethanol and delta 9-tetrahydrocannibinol (THC), and their comutagenic potential with a known mutagenic agent, Trenimon, were examined. This was accomplished by measuring the frequency of dominant lethal mutations arising from mating of treated males with nontreated females. Adult male mice were treated with 5% (v/v) ethanol as part of a liquid diet (28% ethanol-derived calories) for five weeks; 10 mg/kg body weight (p.o.) THC every two days for five weeks; a single injection of Trenimon (0.125 mg/kg, i.p.) on day 28 of diet treatment; and all combinations of treatments. The control group was pair-fed a liquid diet in which isocaloric sucrose replaced ethanol; these males were also given sesame oil (vehicle for THC) and saline (vehicle for Trenimon) on the same schedule as that for the treated males. Neither body weights nor hematocrits were adversely affected by any treatment. Both ethanol and Trenimon treatments resulted in a small (8-9%; p less than 0.05) decrease in testicular weight. The effect of combined treatment with ethanol and Trenimon was roughly additive. Treatment with THC had no effect on testicular weight. Seminal vesicle weights were not affected by any treatment. Treatments were without significant effect on fertility, as measured by the frequency of males producing pregnancies. Ethanol and Trenimon treatments produced approximately 3- and 7-fold increases, respectively in the frequencies of preimplantational loss over that seen for the control group (7.3%), resulting in significant ethanol and Trenimon effects (p less than 0.001). No interactive effects of ethanol and Trenimon treatments were noted. Frequencies of dead fetuses per pregnancy in the ethanol- and Trenimon-treated groups were increased approximately 2.5- and 4-fold, respectively, over the control value of approximately 16%. However, the effect of combined treatments was not greater than that due to Trenimon alone, resulting in Trenimon and ethanol effects (p less than 0.001) and ethanol-Trenimon interaction (p less than 0.001). The calculated mutation index resulting from each treatment yielded significant (p less than 0.001) ethanol- and Trenimon-induced effects. In contrast to effects of ethanol and Trenimon treatments, THC, given alone, or in combination with ethanol and/or Trenimon, had no effect on either preimplantational loss, fetal mortality or the resulting mutation index. The data suggest that chronic ethanol treatment, at levels resulting in minimal fertility impairment, increases the frequency of dominant lethal mutations. In contrast, chronic treatment with THC, as administered in the present study, appears to be without effect.(ABSTRACT TRUNCATED AT 400 WORDS)

Paternal alcohol consumption affects grooming response in rat offspring

Grooming behavior in response to novelty and water immersion was examined in rat offspring sired by males consuming liquid alcohol diets containing 35%, 17.5% or 0% ethanol-derived calories (EDC). In the first study, offspring were tested at 35-38 days of age under conditions of lights on or off. Offspring in the 35% EDC group groomed less than controls. Lighting conditions did not affect grooming significantly. In the second study, animals were immersed in a water bath for 15 seconds and were then placed in the same observation chambers. As in the previous study, animals sired by alcohol-consuming fathers groomed considerably less than controls. These results were interpreted as suggesting offspring sired by alcohol-consuming fathers have a blunted response to conditions which spontaneously elicit behavior like grooming or ambulation.

Paternal alcohol consumption in the rat impairs spatial learning performance in male offspring

Pubescent (30 day old) male rats were maintained on an alcohol liquid diet containing 35% ethanol-derived calories (ALC) for 39 days or were pairfed an isocaloric control diet (PF). The concentration of alcohol in the diet was gradually increased to permit adaptation, then stabilized and then gradually tapered to prevent an alcohol withdrawal syndrome. Following a drug-free period (2 weeks), the males were mated with nontreated females. Offspring were evaluated on several developmental indices and on various learning/memory tasks to assess functional deficits in adulthood. Offspring sired by ALC-treated males did not differ from the offspring of PF males on several developmental parameters including body weights, when developmental landmarks appeared, or on tests of sensorimotor development. As adults, male offspring groups did not differ on tests of activity or on an object exploration/recognition task. However, male offspring of ALC-treated males demonstrated impaired acquisition performance (days and errors to criterion) on a win-shift spatial discrimination in an eight-arm radial maze and on a win-stay discrimination (days to criterion) conducted in a T-maze at a later age. The radial maze results were replicated in a subsequent experiment using different groups of rats.

Alcohol consumption does not affect fathers but does affect their offspring in the forced swimming test

Male rats that had consumed alcohol for seven months did not differ significantly from controls in their immobility response in the forced swimming test. In contrast to this observation, the offspring of these males exhibited a significant dose-related decrease in immobility. These results suggest that while alcohol's effects may not be observable in males consuming it, this does not necessarily mean that it has no important biological effects on these males. However, these effects may not be appreciated until their offspring are examined.

Paternal alcohol exposure: paradoxical effect in mice and rats

Male mice consumed liquid alcohol diets containing 25%, 10% or 0% ethanol-derived calories (EDC). Animals receiving the 10 and 0% EDC diets were pair fed to those consuming the 25% EDC diet. After 7 or 14 weeks of consumption, males were bred to non-treated females. Offspring were tested for swimming behavior at 75 days of age. Offspring sired by alcohol-consuming males were more immobile regardless of duration of paternal alcohol consumption or housing conditions (group or isolated). Imipramine (5, 15 mg/kg) reversed this effect such that after drug treatment, alcohol-sired offspring were less immobile than controls. Propranolol (1, 3 mg/kg) eliminated the group differences. Yohimbine (1, 10 mg/kg) significantly increased immobility in all groups but did not reverse the effects of paternal alcohol consumption. Metergoline (1 mg/kg) increased immobility in all groups but did not reverse the effects of paternal alcohol exposure. When rat offspring of alcohol-consuming fathers were tested, their swimming behavior was opposite to that of mice (i.e., rats were less immobile). However, as observed in mice, the effect was reversed by imipramine. These results extend the evidence for paternally mediated behavioral mutagenesis. They also indicate that the direction of induced changes are species dependent and that some of these effects, regardless of direction of change, are mediated by neurochemical changes sensitive to imipramine.

Paternal alcohol consumption: effects of age of testing and duration of paternal drinking in mice

Male mice consumed liquid alcohol diets containing 25, 20, 15, 10, 5, or 0% ethanol-derived calories (EDC). Animals receiving the 20-0% EDC diets were pair-fed to those consuming the 25% EDC diet. After 7 weeks of consumption males were bred to nontreated females. Offspring were tested for activity at 16-20 and 75 days of age. Offspring sired by alcohol-consuming males did not differ from controls in litter size, birth weight, or weight at weaning, but were less active than controls on several measures of activity. Many of these decreases were best defined in terms of linear trends. However, these differences were evident only for animals tested prior to 20 days of age for most activity measures. In a second experiment adult males continued to consume alcohol for another 7 weeks and were bred again. Offspring of this second breeding were tested for activity at 16 days of age and were compared with offspring sired by the same father from the previous breeding. Offspring sired after this longer duration of paternal alcohol consumption did not differ significantly from controls in any of the above-mentioned variables.

Paternal and maternal alcohol consumption: effects on offspring in two strains of rats

Long-Evans and Sprague-Dawley male rats were given liquid alcohol diets containing 35%, 17.5%, or 0% ethanol-derived calories (EDC). The latter two groups were pair fed to the higher alcohol diet group. A fourth group received lab chow and water ad libitum to assess the role of paternal undernutrition associated with alcohol consumption. After three or four weeks of diet consumption, these males were bred to females of the same strain. Pregnant females were divided into similarly treated alcohol groups and were fed these diets beginning on gestation Day 8, thus creating a factorial study with strain, paternal, and maternal alcohol consumption as main factors. Paternal alcohol consumption was associated with decreased litter size, decreased testosterone levels, and a strain-related effect on offspring activity. Offspring activity decreased for those sired by 35% and 17.5% EDC Long-Evans fathers. Activity also decreased for offspring sired by 17.5% EDC Sprague-Dawley fathers but increased for those sired by 35% EDC fathers. Paternal alcohol consumption did not affect postnatal mortality or passive avoidance learning of offspring. Maternal alcohol consumption was associated with lower birth weights, lower offspring weights at weaning, increased postnatal mortality, and poorer passive avoidance learning. However, offspring activity was not affected. In a separate study, levels of alcohol in the testes were found to be somewhat, but not significantly, lower than blood alcohol levels. DNA taken from sperm of Long-Evans males consuming alcohol, migrated farther under pulsed field electrophoresis than DNA from control fathers, suggestive of an alcohol-related effect on sperm DNA.