Specific Salivary Neuropeptides Shift Synchronously during Acute Stress in Fire Recruits

Area of Science:

• Neuroscience
• Immunology
• Endocrinology

Background:

• The nervous system and immune system communicate bidirectionally via the neuroimmune axis.
• Neuropeptides are key signaling molecules within the neuroimmune axis, influencing brain and peripheral functions.
• The role of salivary neuropeptides in acute stress responses remains largely uncharacterized.

Purpose of the Study:

• To investigate the dynamic changes in salivary neuropeptide concentrations during an acute stress event.
• To explore the relationship between salivary neuropeptide levels and psychological factors like hardiness and past trauma.

Main Methods:

• Salivary samples were collected from fire recruits during a validated acute stress simulation.
• Levels of five key neuropeptides (oxytocin, neurotensin, Substance P, α-MSH, β-Endorphin) were quantified using a multiplex assay.
• Statistical analyses included exploratory factor analysis and Pearson correlation to assess neuropeptide interrelationships and associations with psychological measures.

Main Results:

• All measured salivary neuropeptides significantly increased during the stress simulation and recovery phases.
• A single underlying factor explained baseline variation across the five neuropeptides.
• Strong positive correlations (>0.9) were observed between most neuropeptide pairs at baseline.
• Neuropeptide scores demonstrated a positive correlation with self-assessed hardiness, while past trauma showed a negative correlation.

Conclusions:

• Salivary neuropeptides exhibit synchronous elevation during acute stress.
• Increased salivary neuropeptide levels are associated with greater self-assessed hardiness.
• Further research is warranted to explore neuropeptide-enhancing interventions for improving stress resilience in high-stress professions.