Poster #62 - DNA methylation of the oxytocin receptor changes during infancy and is impacted by maternal behavior

• In Event: 2-002 - Special Poster Session 05 with Continental Breakfast Reception
  In Poster Session: PS 05 - Interdisciplinary Section

Integrative Statement

Oxytocin is a neurohormone that plays a critical role in the regulation of a host of social functions, including maternal care, social perception, and prosocial behavior. Its actions are dependent on its receptor, whose expression is partially controlled by DNA methylation. Our work in the prairie vole suggests that parental care has a direct impact on oxytocin receptor gene (OXTR) methylation in pups, positing a potential mechanism through which early care can regulate the oxytocinergic system and, in turn, impact downstream behavior. We hypothesize that OXTR methylation may be used to inform individual differences in social function as well as early caregiving experience in humans.
In the current project, we aimed to better understand and characterize the plasticity of the oxytocinergic system across the first year and a half of life. 101 mother-infant dyads participated in this study in Leipzig, Germany. OXTR methylation was assessed through saliva collection at two timepoints: 5 months and 18 months of age. Maternal and infant engagement was assessed through a coded free play session at 5 months of age and infant temperament was assessed at 18 months of age.
Our analyses indicate that OXTR methylation remains relatively stable in mothers. In contrast, infant OXTR methylation is dynamic between 5 and 18 months of life, showing evidence of both reductions and increases. Moreover, we find that this change in OXTR methylation is significantly predicted by maternal, but not infant, engagement coded during free play. Specifically, higher displays of maternal engagement at 5 months predicted a reduction of OXTR methylation from 5 to 18 months in infants (ß = -0.326, p = 0.014). Our analysis further showed that lower levels of methylation at 18 months were associated with more positive behavioral temperament as reflected in lower levels of discomfort measured through the Early Childhood Behavior Questionnaire (r(83) = 0.303, p = 0.005).
This suggests that maternal behavior impacts epigenetic change of OXTR in human infancy. Our results indicate that higher maternal engagement early in infancy may increase oxytocin system efficiency through reduction of methylation, previously associated with greater OXTR expression. These findings are in line with research in animal models, demonstrating that early social experience impacts offspring development through epigenetic modification. The current study contributes to our understanding of the complex interplay between nature and nurture by identifying an epigenetic mechanism by which maternal care influences offspring behavioral development.

Authors

• Kathleen M Krol, University of Virginia
  Presenting Author

• Robert G Moulder, University of Virginia
  Non-Presenting Author

• Travis S Lillard, University of Virginia
  Non-Presenting Author

• Tobias Grossmann, University of Virginia
  Non-Presenting Author

• Jessica J Connelly, University of Virginia
  Non-Presenting Author