Influence of Oxytocin on the Startle Reflex and on Its Modulation
Status:
Unknown status
Trial end date:
2012-12-01
Target enrollment:
Participant gender:
Summary
Oxytocin (OXT) is currently regarded as a crucial neuropeptide in the mediation of various
human social behaviors, e.g. social affiliation, social recognition, and the modulation of
anxiety, mood, and aggression. An impairment of social behavior, emotional regulation as well
as increased stress reactions are characteristic of several psychiatric conditions, including
schizophrenia, social anxiety and PTSD, in which there is also some evidence for OXT
dysfunction. The startle reflex is a basic defensive reaction that can be modulated by
emotional stimuli. The investigation of the startle reflex and of its modulation is a
well-validated method to test stress reactions and emotional regulation. These processes are
impaired in the same psychiatric diseases, in which OXT dysfunction was evidenced. Although
previous animal studies showed that the dysfunction of brain OXT systems might be implicated
in startle reflex and in its modulation, no study has been performed yet in human that
investigated the influence of OXT administration on the startle response and on its affective
modulation. A first aim of this study is to investigate the influence of OXT on stress
reactivity and emotional modulation in healthy humans. A second aim is to develop a method
for the investigation of anxiety disorders. Fifty male healthy participants will be tested
using a randomized double-blind placebo-controlled cross-over design in two occasions; once
with administration of 24 IU OXT, and once with placebo using nasal sprays while performing a
computer-based experiment, in which emotional pictures and auditory startle probes are
presented. We will measure the subject's subjective ratings of the pictures as well as the
facial EMG activation, heart rate and electrodermal activation throughout the study. This
project offers a unique opportunity to study the relationship between the OXT system and
basic motivational and emotional behaviors. The investigation of these mechanisms is in turn
greatly worthwhile, not only for understanding of the neurochemical and physiological
processes involved in emotional regulation, but also for the comprehension of the
neuroendocrine and neurophysiological mechanismsunderlying anxiety disorders. In the long
term, it could open the possibilities of OXT as a psychobiological therapeutics of
psychiatric disorders.