Hippocampal volume modulates salivary oxytocin level increases after intranasal oxytocin administration.

Adverse childhood experiences have been shown to affect sensitivity to intranasal oxytocin administration, but the neural mechanisms underlying this altered sensitivity are unclear. The aim of the current study was to examine whether hippocampal abnormalities underlie the effects of adversity on the response to oxytocin administration. In a sample of healthy women (N = 54, age M = 19.63), we examined 1) the association between hippocampal volume and experiences of emotional maltreatment and 2) whether hippocampal volume reductions influence the effect of intranasal oxytocin administration on salivary oxytocin levels. There was no association between hippocampal volume and experiences of emotional maltreatment in the current study. However, we found that larger hippocampal volume was related to a stronger increase in salivary oxytocin level after intranasal oxytocin administration. The hippocampus may be a neural substrate underlying individual differences in sensitivity to oxytocin administration.