Intranasal oxytocin administration is reflected in human saliva

Following the discovery that intranasal administration of neuropeptides can reach the central nervous system, a growing number of studies applied intranasal oxytocin (OT) paradigms to demonstrate the positive effects of OT on social and emotional processes. The three-step paradigm typically included: OT administration, a 45-min waiting period, and approximately 1-h period of active drug effects when experimental manipulations are applied. Yet, this schedule has not been put to systematic validation. Utilizing a double-blind placebo-control within-subject design, ten individuals were administered OT or placebo and salivary OT was measured ten times, at baseline and nine times over four consecutive hours. OT administration induced substantial increases in salivary OT across the entire period. OT rose dramatically 15 min after administration (from 6.9 pg/ml at baseline to 1265.4 pg/ml), reached plateau at 45-120 min (range = 131.6 and 105.3 pg/ml), and did not return to baseline by 4 h. Results contribute to discussion on brain-periphery coordination of OT and highlight the need for further research on the temporal dynamics and durations of OT administration effects.