Genetic variation and epigenetic modification of the prodynorphin gene in peripheral blood cells in alcoholism.

Dynorphins are critically involved in the development, maintenance and relapse of alcoholism. Alcohol-induced changes in the prodynorphin gene expression may be influenced by both gene polymorphisms and epigenetic modifications. The present study of human alcoholics aims to evaluate DNA methylation patterns in the prodynorphin gene (PDYN) promoter and to identify single nucleotide polymorphisms (SNPs) associated with alcohol dependence and with altered DNA methylation. Genomic DNA was isolated from peripheral blood cells of alcoholics and healthy controls, and DNA methylation was studied in the PDYN promoter by bisulfite pyrosequencing. In alcoholics, DNA methylation increased in three of the seven CpG sites investigated, as well as in the average of the seven CpG sites. Data stratification showed lower increase in DNA methylation levels in individuals reporting craving and with higher levels of alcohol consumption. Association with alcoholism was observed for rs2235751 and the presence of the minor allele G was associated with reduced DNA methylation at PDYN promoter in females and younger subjects. Genetic and epigenetic factors within PDYN are related to risk for alcoholism, providing further evidence of its involvement on ethanol effects. These results might be of relevance for developing new biomarkers to predict disease trajectories and therapeutic outcome.

Cesarean delivery and hematopoietic stem cell epigenetics in the newborn infant: implications for future health?

OBJECTIVE: Cesarean section (CS) has been associated with a greater risk for asthma, diabetes, and cancer later in life. Although elective CS continues to rise, it is unclear whether and how it may contribute to compromised future health. Our aim was to investigate the influence of mode of delivery on the epigenetic state in neonatal hematopoietic stem cells. STUDY DESIGN: This was an observational study of 64 healthy, singleton, newborn infants (33 boys) born at term. Cord blood was sampled after elective CS (n = 27) and vaginal delivery. Global deoxyribonucleic acid (DNA) methylation in hematopoietic stem cells (CD34+) was determined by luminometric methylation assay, and genome-wide, locus-specific DNA methylation analysis was performed by Illumina Infinium 450K (Illumina, San Diego, CA), validated by bisulfite-pyrosequencing. RESULTS: CD34+ cells from infants delivered by CS were globally more DNA methylated (+2%) than DNA from infants delivered vaginally (P = .02). In relation to mode of delivery, a locus-specific analysis identified 343 loci with a difference in DNA methylation of 10% or greater (P < .01). A majority of the differentially methylated loci in neonatal CD34+ cells (76%) were found to be hypermethylated after vaginal delivery. In these infants, the degree of DNA methylation in 3 loci correlated to the duration of labor. The functional relevance of differentially methylated loci involved processes such as immunoglobulin biosynthetic process, regulation of glycolysis and ketone metabolism, and regulation of the response to food. CONCLUSION: A possible interpretation is that mode of delivery affects the epigenetic state of neonatal hematopoietic stem cells. Given the functional relevance indicated, our findings may have important implications for health and disease in later life.

Brain-derived neurotrophic factor gene variation influences cerebrospinal fluid 3-methoxy-4-hydroxyphenylglycol concentrations in healthy volunteers.

Brain-derived neurotrophic factor (BDNF) has been shown to influence monoamine transmitter synthesis, metabolism and release. We investigated possible relationships between four BDNF gene polymorphisms and cerebrospinal fluid (CSF) concentrations of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) in healthy volunteers (n = 132). All BDNF polymorphisms (270 C/T, -633 T/A, Val66Met, and 11757 G/C) were associated with MHPG (P < 0.02), but not with 5-HIAA and HVA concentrations. At a second clinical investigation 8-20 years after CSF sampling 30% of the subjects had experienced various psychiatric disorders. Development of a psychiatric disorder was predicted by low 5-HIAA concentrations (P = 0.01). The results suggest that BDNF gene variation participates in regulation of norepinephrine turnover rates in the central nervous system of human subjects.

The opioid peptides enkephalin and beta-endorphin in alcohol dependence.

BACKGROUND: Experimental evidence indicates that the endogenous opioid system influences stress responses as well as reinforces effects of addictive drugs. Because stress is an important factor contributing to drug dependence and relapse, we have now studied ethanol preference in enkephalin- and beta-endorphin-deficient mice under baseline conditions and after stress exposure. METHODS: In the present study we used a two-bottle choice paradigm to study ethanol consumption and stress-induced ethanol preference. To examine alcohol withdrawal symptoms the forced drinking procedure was employed. We performed an association analysis in two case-control samples of alcohol addicts to determine whether these opioid peptides also contribute to ethanol dependence in humans. RESULTS: Ethanol consumption was significantly reduced in the absence of beta-endorphins, particularly in female knockout animals. Stress exposure results in an increased ethanol consumption in wild-type mice but did not influence ethanol-drinking in beta-endorphin knockouts. Enkephalin-deficient mice showed no difference from wild-type mice in baseline ethanol preference but also showed no stress-induced elevation of ethanol consumption. Interestingly, we found a two-marker haplotype in the POMC gene that was associated with alcohol dependence in females in both cohorts. CONCLUSIONS: Together these results indicate a contribution of beta-endorphin to ethanol consumption and dependence.

Brain-derived neurotrophic factor gene (BDNF) variants and schizophrenia: an association study.

Polymorphisms in the brain-derived neurotrophic factor (BDNF) gene have been suggested to be associated with schizophrenia. In a replication attempt, Swedish patients with schizophrenia (n=187) and control subjects (n=275) were assessed for four BDNF gene polymorphisms. There were no significantly different allele, genotype or haplotype frequencies between cases or controls. Neither were there any differences when schizophrenic patients were sub-divided with regard to a number of different clinical variables, although a small group of psychotic patients with prominent affective features displayed higher frequencies of the less common alleles of the Val66Met and 11757 G/C polymorphisms compared to controls. The present Swedish results do not verify previous associations between putative functional BDNF gene polymorphisms and schizophrenia. However, when combined with previous studies meta-analyses indicated that the BDNF 270 T-allele and the Val66Met homozygous state were associated with the disorder. Thus, the BDNF gene may confer susceptibility to schizophrenia. Additional studies are warranted to shed further light on this possibility.