Paternal alcohol exposure affects sperm cytosine methyltransferase messenger RNA levels

Background: Although paternal alcohol exposure has been shown to affect the growth and behavior of offspring, the mechanisms underlying these effects still remain to be elucidated. This study examines one possible mechanism, namely, altered genomic imprinting as reflected by changes in sperm cytosine methyltransferase messenger RNA (mRNA) levels. Methods: Male rats were treated with alcohol for 9 weeks before breeding. Resulting fetuses were counted and weighed, and paternal sperm was examined for changes in cytosine methyltransferase mRNA levels. Results. Alcohol did not affect mating, fecundity, or litter size, but it did result in significantly decreased mean fetal weight, increased fetal runt incidence in offspring, and decreased cytosine methyltransferase mRNA levels in paternal sperm, compared with pair-fed and ad libitum controls. Conclusions: Alcohol-induced reductions in cytosine methyltransferase mRNA levels may reflect altered genomic imprinting caused by reduced DNA methylation, which, in turn, may lead to the expression of normally silent paternal alleles and may be a mechanism for paternal alcohol effects.