BackgroundCortisol is an essential hormone in the regulation of the stress response along the HPA axis, and salivary cortisol has been used as a measure of free circulating cortisol levels. Recently, salivary alpha-amylase (sAA) has also emerged as a novel biomarker for psychosocial stress responsiveness within the sympathetic adrenomedullary (SAM) system.Principal FindingsWe measured sAA and salivary cortisol in healthy volunteers after exposure to the Trier Social Stress Test (TSST) and electric stimulation stress. One hundred forty-nine healthy volunteers participated in this study. All subjects were exposed to both the TSST and electric stimulation stress on separate days. We measured sAA and salivary cortisol levels three times immediately before, immediately after, and 20 min after the stress challenge. The State (STAI-S) and Trait (STAI-T) versions of the Spielberger Anxiety Inventory test and the Profile of Mood State (POMS) tests were administered to participants before the electrical stimulation and TSST protocols. We also measured HF, LF and LF/HF Heart Rate Variability ratio immediately after electrical stimulation and TSST exposure. Following TSST exposure or electrical stimulation, sAA levels displayed a rapid increase and recovery, returning to baseline levels 20 min after the stress challenge. Salivary cortisol responses showed a delayed increase, which remained significantly elevated from baseline levels 20 min after the stress challenge. Analyses revealed no differences between men and women with regard to their sAA response to the challenges (TSST or electric stimulations), while we found significantly higher salivary cortisol responses to the TSST in females. We also found that younger subjects tended to display higher sAA activity. Salivary cortisol levels were significantly correlated with the strength of the applied electrical stimulation.ConclusionsThese preliminary results suggest that the HPA axis (but not the SAM system) may show differential response patterns to distinct kinds of stressors.

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These results suggest that SAD patients displayed enhanced ANS (but not HPA axis) activity vs. healthy controls.

Objective. Major depressive disorder (MDD) is often associated with dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis via chronic stress. Psychosocial stress-induced activation of salivary α-amylase (sAA) represents sympathoadrenal medullary system (SAM) activity, and sAA has become an emerging biomarker for sympathetic nervous system activity. In contrast to salivary cortisol, sAA has been less extensively studied in depressed patients. The present study sought to address this problem by measuring sAA and salivary cortisol levels in patients with major depressive disorder. Methods. The authors recorded Spielberger State-Trait Anxiety Inventory (STAI) scores along with, levels of sAA and salivary cortisol in 28 patients with unremitted major depressive disorder, 43 remitted patients and 103 healthy volunteers. Results. STAI (State or Trait) measurements in unremitted patients with MDD were significantly increased compared with healthy controls and remitted patients. SAA and cortisol levels in unremitted patients were also significantly elevated compared to controls and remitted patients. Finally, sAA levels were significantly correlated with HRSD in unremitted patients with MDD. Conclusion. These preliminary results suggest that sAA may be a state-dependent marker of major depressive disorder in addition to salivary cortisol.