The role of salivary neurotensin and oxytocin in emotional responses to stress inoculation

Neuropeptides comprise a class of signaling molecules that exert direct effects on target tissues and modulatory influences across multiple physiological systems; however, their roles in mediating stress responses remains incompletely characterized. Previous studies have shown that acute stress alters salivary levels of neuropeptides but the extent to which these alterations are associated with mechanisms of stress inoculation and emotional valence requires exploration. This study aimed to examine the relationship between salivary neuropeptides and emotional valence following acute stress in military medical students. Salivary samples for oxytocin, neurotensin and data from two questionnaires, ACE and SPANE, were collected from participants pre- and post-stress inoculation. Spearman rank correlation analysis revealed positive correlations >0.9 for neurotensin and oxytocin at pre- and post-inoculation. Post-inoculation neurotensin showed an inverse correlation with pre-simulation SPANE-P and SPANE-B scores (p = 0.006 and p = 0.009 respectively) and demonstrated a positive correlation with pre-simulation SPANE-N score (p = 0.043). Post-inoculation oxytocin demonstrated a negative correlation with pre-inoculation SPANE-P and SPANE-B scores (p = 0.007 and p = 0.006 respectively). Cohorts were established of participants whose neuropeptide levels increased or decreased during inoculation. Inverse correlations existed between oxytocin post-simulation and post-SPANE positive emotions in the increased oxytocin group (R = -0.4607), and between pre-simulation oxytocin and pre-SPANE positive emotions in the decreased oxytocin group (R = -0.4005). Individual variability in salivary neuropeptide responses to inoculation was inversely associated with positive affect, suggesting these neuropeptides as modulators of affective stress responsivity. Future studies should explore the mechanism of these associations and evaluate the potential of salivary neuropeptides as biomarkers for emotional and stress adaptation.