Paternal alcohol exposure has task- and sex-dependent behavioral effect in offspring.

BACKGROUND: Endophenotypes for alcohol use disorder are well known and may reflect paternal exposure effects passed down to offspring via epigenetic mechanisms. Previously, we showed that paternal alcohol exposure prior to conception attenuates the acquisition of operant alcohol self-administration. We now test whether paternal alcohol exposure alters their offsprings' behavioral responses to alcohol (endophenotypes) and global DNA methylation levels in reward-related brain regions. METHODS: Adult male rats were exposed to alcohol vapors or air for 6 weeks and mated with alcohol-naïve females 8 weeks later. Adult male and female offspring of the alcohol- and control-sired litters were tested on three behaviors 30 m after gavage with water or alcohol (1.5 g/kg): open field, elevated plus maze, and accelerating rotarod. Global DNA methylation levels in sperm, nucleus accumbens, and prefrontal cortex were examined in male sires and in another group of offspring. RESULTS: Alcohol-sired males showed less anxiety-like behavior in the elevated plus maze that was not affected by alcohol administration. By contrast, alcohol had anxiolytic effects in the open field in male offspring only with no paternal alcohol effect. Neither paternal alcohol exposure nor alcohol administration altered locomotor activity in either sex. Sex-specific effects of paternal alcohol exposure were seen in the rotarod test. Alcohol-sired male offspring showed blunted sensitivity to the alcohol's motor-impairing effects, whereas alcohol-sired female offspring showed enhanced sensitivity. Global DNA methylation was altered in the sperm of alcohol-exposed males, but no changes were seen in their offspring. CONCLUSIONS: Paternal alcohol exposure prior to conception has sex- and task-dependent effects on unconditioned behaviors in their offspring.

Pharmacogenetics of Addiction Therapy.

Drug addiction is a serious relapsing disease that has high costs to society and to the individual addicts. Treatment of these addictions is still in its nascency, with only a few examples of successful therapies. Therapeutic response depends upon genetic, biological, social, and environmental components. A role for genetic makeup in the response to treatment has been shown for several addiction pharmacotherapies with response to treatment based on individual genetic makeup. In this chapter, we will discuss the role of genetics in pharmacotherapies, specifically for cocaine, alcohol, and opioid dependences. The continued elucidation of the role of genetics should aid in the development of new treatments and increase the efficacy of existing treatments.

Methylation of the serotonin transporter gene moderates the depressive subjective effect of cocaine.

Genetic variation in the serotonin transporter (SLC6A4) has been shown to moderate the acute subjective effects of cocaine. Methylation of the SLC6A4 gene is associated with decreased transcription of the serotonin transporter, leading to increased serotonin in the synapse. In this study, methylation of the SLC6A4 gene was investigated in the moderation of the subjective effects of cocaine. Non-treatment-seeking cocaine-dependent individuals (N = 53) were intravenously administered cocaine (40 mg) and saline in a randomized order. The subjective effects of cocaine were self-reported using a visual analog scale starting prior to the administration of cocaine (-15 min) or saline and up to 20 min after infusion. Participants were evaluated for methylation of the SLC6A4 promoter region and 5-HTTLPR genotype. A series of ANCOVAs for SLC6A4 methylation (high/low) were run for each of ten subjective and three cardiovascular effects controlling for age, sex [utilizing the sex-determining region Y protein (SRY)], and population structure (determined from ancestry informative markers and STRUCTURE software). Participants with SLC6A4 hypermethylation reported greater subjective response to cocaine for 'depressed' relative to participants with SLC6A4 hypomethylation (experiment-wise p = 0.002). These findings indicate that SLC6A4 methylation moderates the 'depressed' subjective effect of cocaine in non-treatment-seeking cocaine-dependent participants.

Paternal alcohol exposure reduces acquisition of operant alcohol self-administration and affects Bdnf DNA methylation in male and female offspring.

Familial transmission of alcohol use disorder reflects genetic and environmental factors. Paternal alcohol exposure may affect rodent offspring via epigenetic modifications transmitted through the male germ line. While such exposure alters alcohol sensitivity in mouse offspring, no studies examined if it impacts the development of operant alcohol self-administration in rats. We exposed male (sires) Wistar rats to chronic intermittent ethanol in vapour chambers (16 h/day; 5 days/week) or to air for 6 weeks. Eight weeks later, rats were mated with alcohol-naive females. Adult alcohol- and control-sired F1 offspring were assessed in acquisition of alcohol self-administration in which increasing alcohol concentrations (2.5%, 5% and 10%, v/v) were delivered after one lever press (fixed ratio 1 or FR1). Prior to alcohol sessions, rats were trained to lever press for food delivery under an FR1 schedule of reinforcement. DNA methylation levels of the brain derived neurotrophic factor (Bdnf) gene were measured in sperm, nucleus accumbens (NAc) and medial prefrontal cortex (mPFC) in sires and in offspring. Alcohol-exposed sires had lower Bdnf DNA methylation levels in NAc and greater methylation levels in mPFC. Although this pattern was not recapitulated in offspring, alcohol-sired offspring of both sexes did show aberrant Bdnf DNA methylation patterns compared to control-sired offspring. Alcohol-sired offspring self-administered less alcohol (5% and 10%) with no group differences in food responding. Results indicate that paternal alcohol exposure prior to conception protects against alcohol's initial reinforcing effects but the pattern of dysregulated Bdnf methylation in reward-related circuitry did not mimic changes seen in sires.

The OPRD1 rs678849 variant influences outcome of disulfiram treatment for cocaine dependency in methadone-maintained patients.

OBJECTIVE: Prior research demonstrated that the δ-opioid receptor (OPRD1) rs678849 variant influences opioid use in African Americans treated with methadone. We examined whether this variant moderated cocaine and opioid use in our clinical cohort of methadone and disulfiram treated recipients. METHODS: Cocaine and opioid codependent patients were stabilized for 2 weeks on methadone and subsequently randomized into groups treated with either methadone + placebo (n = 37) or methadone + disulfiram (250 mg/day; n = 33) for 12 weeks. RESULTS: A drop in cocaine-positive urine was found in the OPRD1 CC genotype group compared to T-allele carrier patients treated with methadone + disulfiram (P < 0.0001), but not in the methadone + placebo group. No difference in opioid-positive urines was found among each genotype group in either treatment group. CONCLUSION: These findings suggested that rs678849 genotype may predict treatment response of disulfiram for cocaine use in patients with co-occurring opioid and cocaine dependence.

Association of TPH1 and serotonin transporter genotypes with treatment response for suicidal ideation: a preliminary study.

Variants in three genes coding for components of the serotonergic system, the tryptophan hydroxylase 1 (TPH1) rs1799913, serotonin transporter (SLC6A4) 5-HTTLPR, and serotonin receptor 2A (HTR2A) rs6311, were evaluated for association with suicidal ideation (SI) and with recovery from SI in a psychiatric inpatient population. Five hundred and eighty-two adult inpatients, including 390 patients who had SI, collected from December 2012 to April 2016 were assessed. SI recovery, calculated as change in SI between the first two-week period after admission and weeks 5 and 6, was appraised for association with the three variants. In this preliminary study, both TPH1 and 5-HTTLPR genotypes were associated with recovery (TPH1: recessive model, increased recovery with AC genotype, P = 0.026; additive model, increased recovery with AC genotype, P = 0.037; 5-HTTLPR: recessive model, increased recovery with AC, P = 0.043). When patients with comorbid alcohol use disorder (AUD) were removed, given that TPH1 has been associated with alcoholism, the associations of those recovered from SI with TPH1 rs1799913 remained significant for the additive (increased recovery with AC, P = 0.045) and recessive (increased recovery with C-carriers, P = 0.008) models, and with 5-HTTLPR using the dominant model (increased recovery with S'S', P = 0.016). In females, an association of SI recovery with TPH1 rs1799913 was found using a recessive model (increased recovery with C-carriers, P = 0.031), with 5-HTTLPR using additive (increased recovery with L'S', P = 0.048) and recessive (increased recovery with S'S', P = 0.042) models. Additionally, an association of SI with TPH1 rs1799913 was found in females using both additive (increased risk in AC, P = 0.033) and recessive (increased risk in C-carriers, P = 0.043) models, and with 5-HTTLPR using a recessive model (increased risk in S'S', P = 0.030). This study provides evidence that variation in the TPH1 and serotonin transporter genes play key roles in moderating recovery from SI during treatment in an inpatient psychiatric clinic.

Pharmacogenetic role of dopamine transporter (SLC6A3) variation on response to disulfiram treatment for cocaine addiction.

BACKGROUND AND OBJECTIVES: Disulfiram has been beneficial in treating cocaine addiction in several studies. Patients with two SLC6A3 (DAT1) rs28363170 10-repeat alleles who have with genetically high dopamine transporter (DAT) levels may benefit from increased dopamine levels resulting from disulfiram treatment. METHODS: After stabilization for 2 weeks on methadone, 70 cocaine and opioid codependent patients were randomized into disulfiram and placebo groups for 12 weeks of treatment. We genotyped the SLC6A3 (DAT1) 40 bp 3'-untranslated region variable number tandem repeat variant and evaluated its role in moderating disulfiram efficacy for cocaine dependence. RESULTS: Among the 10,10-repeat genotype group, cocaine-positive urines dropped from 78% to 48% and from 80% to 75% among the 9-repeat carrier group in the disulfiram group (P = 0.0001, with an effect size of 0.09). No difference was observed in cocaine-positive urines in the placebo group between the 10,10-repeat genotype and the 9-allele carrier patients. CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE: We found that patients with genetically higher DAT levels had better treatment outcomes with disulfiram pharmacotherapy of cocaine dependence than those with lower DAT levels. (Am J Addict 2019;28:311-317).

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

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

Increased habenular connectivity in opioid users is associated with an α5 subunit nicotinic receptor genetic variant.

BACKGROUND AND OBJECTIVES: Opioid use disorder (OUD) is a chronic disorder with relapse based on both desire for reinforcement (craving) and avoidance of withdrawal. The aversive aspect of dependence and relapse has been associated with a small brain structure called the habenula, which expresses large numbers of both opioid and nicotinic receptors. Additionally, opioid withdrawal symptoms can be induced in opioid-treated rodents by blocking not only opioid, but also nicotinic receptors. This receptor co-localization and cross-induction of withdrawal therefore might lead to genetic variation in the nicotinic receptor influencing development of human opioid dependence through its impact on the aversive components of opioid dependence. METHODS: We studied habenular resting state functional connectivity with related brain structures, specifically the striatum. We compared abstinent psychiatric patients who use opioids (N = 51) to psychiatric patients who do not (N = 254) to identify an endophenotype of opioid use that focused on withdrawal avoidance and aversion rather than the more commonly examined craving aspects of relapse. RESULTS: We found that habenula-striatal connectivity was stronger in opioid-using patients. Increased habenula-striatum connectivity was observed in opioid-using patients with the low risk rs16969968 GG genotype, but not in patients carrying the high risk AG or AA genotypes. CONCLUSIONS: We propose that increased habenula-striatum functional connectivity may be modulated by the nicotinic receptor variant rs16969968 and may lead to increased opioid use. SCIENTIFIC SIGNIFICANCE: Our data uncovered a promising brain target for development of novel anti-addiction therapies and may help the development of personalized therapies against opioid abuse. (Am J Addict 2017;26:751-759).

Genetic moderation of cocaine subjective effects by variation in the TPH1, TPH2, and SLC6A4 serotonin genes.

OBJECTIVE: This study investigated variants of tryptophan hydroxylase (TPH)1, TPH2, and SLC6A4 in the moderation of the subjective effects of cocaine. METHODS: Non-treatment-seeking cocaine-dependent individuals (N=66) were intravenously administered saline and cocaine (40 mg) in a randomized order. Participants self-reported subjective effects of cocaine using a visual analog scale starting before administration of saline or cocaine (-15 min) to up to 20 min after infusion. Self-report ratings on the visual analog scale ranged from 0 (no effect) to 100 (greatest effect). Participants were genotyped for the TPH1 rs1799913, TPH2 rs4290270, and SLC6A4 5-HTTLPR variants. Repeated-measures analysis of covariance was used to examine changes in subjective effect scores over time while controlling for population structure. RESULTS: Participants carrying the TPH1 rs1799913 A allele reported greater subjective response to cocaine for 'stimulated' and 'access' relative to the CC genotype group. Those carrying the TPH2 rs4290270 A allele reported higher 'good effect' and lower 'depressed' effect relative to the TT genotype group. Those carrying the SLC6A4 5-HTTLPR S' allele reported greater 'desire' and 'access' compared with the L'L' genotype group. CONCLUSION: These findings indicate that TPH1, TPH2, and SLC6A4 variants moderate the subjective effects of cocaine in non-treatment-seeking cocaine-dependent participants.