Yet Another Reason to Thank Dad This Father’s Day! Evidence for Paternally-Inherited Epigenetic Modifications
Maternal health during gestation and prenatal conditions are well documented as having profound effects on health and development of a baby after birth. The mechanisms behind many of these effects are attributed to epigenetic changes that take place in utero. More recently, pre-fertilization maternal health has been also been implicated in affecting development of babies after birth. Despite the growing evidence for pre-fertilization maternal effects, little research has focused on how paternal health and lifestyle might affect offspring. A recent paper provides the first hints as to what kind of role Dad’s health, at the time of conception, might play in the development of his children.
Mychasiuk et al. looked at the effect of paternal stress on offspring in rats. Male rats were subjected to stressful conditions by placing them on an elevated Plexiglas platform, which is known to induce stress in rats, for 27 straight days prior to mating. Offspring were then tested for behavioral and developmental differences. Two well-established paradigms, the negative geotaxis task and the open field test, were used to measure sensory motor development and anxiety, respectively. Offspring of stressed-out Dads showed delayed development of motor skills, implying a possible slower maturation of the brain. These mice also tended to be less anxious and more daring later in life – particularly the male offspring!
The group then looked for correlations between these behavioral results and epigenetic changes in the brains by investigating global DNA methylation levels in the frontal cortex and hippocampus. The frontal cortex integrates input from many other regions of the brain and controls higher cognitive functions such as behavior, problem solving, and decision making. In the frontal cortex of females, the authors found a decrease in global DNA methylation, whereas in males there was little difference. In the hippocampus, famously implicated in learning and memory, they found increased levels of DNA methylation in both males and females.
Researchers are just beginning to tease apart the intricate mechanisms behind the interactions of maternal, environmental – and now paternal – influences on offspring growth and development. The brain and nervous system are vastly complex, and while a single, small epigenetic change might not leave a noticeable effect, several small changes, or a select few of the right changes in combination, can lead to potentially drastic changes in phenotypes of behavior, personality, development and disease. Although many questions remain, this study sets the stage for much needed and deeper research of the paternal influences on offspring.
So this coming Father’s Day, don’t forget to thank Dad for his part in making you who you are; including his behavior prior to conception!
Mychasiuk R, Harker A, Ilnytskyy S, & Gibb R (2013). Paternal stress prior to conception alters DNA methylation and behaviour of developing rat offspring. Neuroscience, 241, 100-5 PMID: 23531434