Abstract
OBJECTIVE: Given the role of sympathetic nervous system and hypothalamic-pituitary-adrenal (HPA) axis in trauma transmission and oxytocin's stress buffering effects, this study examined whether placental oxytocin receptor (OXTR) gene expression differs by maternal trauma exposure status. METHODS: A sample (N = 152) was drawn from a longitudinal birth cohort. OXTR was quantified using nCounter platform as expressed or unexpressed. Maternal trauma exposure was assessed via validated questionnaire and categorized into four groups: before pregnancy trauma, Superstorm Sandy exposure during pregnancy, both, or neither (reference). Logistic regression and synergy index (SI) were calculated to examine individual and additive interaction effects. RESULTS: In the proportion of samples with detectable OXTR, neither individual exposure significantly altered placental OXTR expression. However, both traumas exposure group had an over a 6-fold increase (OR = 6.13, p = .01) compared to the reference. The SI was 2.17 suggesting that the combined effect of both traumas exceeded the sum of their individual effects on placental OXTR expression. CONCLUSION: Given oxytocin linked placental adaptations to cope with consequences of stress, this greater-than-additive modification, as evidenced by the synergy index, suggests trauma exposure before pregnancy fundamentally changes how the placenta responds to disaster exposure during pregnancy in anticipation of harsh external conditions.