Oxytocin's influence on human startle reflex and emotional modulation to be investigated in a randomized controlled trial

Psychiatric conditions like schizophrenia, social anxiety, and PTSD are characterized by impaired social behavior, emotional dysregulation, and heightened stress reactions, often linked to Oxytocin (OXT) system dysfunction. OXT, a crucial neuropeptide, mediates social affiliation, recognition, and modulates anxiety, mood, and aggression. The startle reflex, a basic defensive reaction, serves as a validated method to assess stress and emotional regulation, processes frequently impaired in these OXT-dysfunctional disorders. While previous animal studies suggest OXT system dysfunction impacts startle reflex modulation, human data on exogenous OXT's influence on this response and its affective modulation is currently lacking.

Researchers will conduct a randomized, double-blind, placebo-controlled crossover study involving 50 male healthy participants. Each participant will undergo testing on two separate occasions: once after intranasal administration of 24 IU Oxytocin, and once with a placebo nasal spray. During each session, participants will engage in a computer-based experiment presenting emotional pictures and auditory startle probes. The study's primary endpoints include subjective ratings of the pictures, facial EMG activation (to measure startle response), heart rate, and electrodermal activation, all continuously measured to assess stress reactivity and emotional modulation.