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Introduction: The vestibular acute stress induces reversible alert-like reactions that involve the sympathetic adrenal-medullar system and hypothalamic-pituitary-adrenal axis responses. The present study aimed to evaluate salivary α-amylase and salivary cortisol production in relation with cardiovascular reactivity induced by acute stress in healthy subjects., Material and Methods: Forty-eight young healthy male volunteers were examined under basal conditions and at various times after reaching the maximal nystagmic reaction following air caloric vestibular test. Heart rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure were recorded at the same time as measurement of the salivary α-amylase and salivary cortisol. At the end of the caloric vestibular test session, perceived stress scale questionnaires were administered to measure the self-perceived stress impact induced by the task, and individual scores were compared with those measured on the enrollment day., Results: Following caloric vestibular test-evoked vertigo, salivary α-amylase and cortisol showed distinct trends in their production after acute stress: Student's t-test was used to compare the α-amylase vs cortisol slopes of the respective interpolated regression lines, and the difference was significant (t = -3.283; p<0.001); an increase in salivary cortisol production corresponded with a decrease in the salivary α-amylase concentration. In addition, salivary biomarker modifications were associated with consistent changes in the heart rate, systolic blood pressure and mean arterial pressure., Conclusions: Using the air caloric vestibular test task as a stressor, the present study demonstrated a connection between the acute hormonal stress response to vestibular stimulation and cardiovascular output. However, further research is needed before we can define the potential importance of the consistent cardiovascular activity changes evoked by vestibular stimulation and the possible functional consequences for cardiovascular regulation and orthostatic tolerance in humans.

Currently, the potential for cardiovascular (CV) stress-induced risk is primarily based on the theoretical (obvious) side effects of stress on the CV system. Salivary cortisol and α-amylase, produced respectively by the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic-adrenomedullary (SAM) system during stress response, are still not included in the routine evaluation of CV risk and require additional and definitive validation. Therefore, this article overviews studies published between 2010 and 2015, in which salivary cortisol and α-amylase were measured as stress biomarkers to examine their associations with CV/CMR (cardiometabolic risk) clinical and subclinical indicators. A comprehensive search of PubMed, Web of Science and Scopus electronic databases was performed, and 54 key articles related to the use of salivary cortisol and α-amylase as subclinical indicators of stress and CV/CMR factors, including studies that emphasized methodological biases that could influence the accuracy of study outcomes, were ultimately identified. Overall, the biological impact of stress measured by salivary cortisol and α-amylase was associated with CV/CMR factors. Results supported the use of salivary cortisol and α-amylase as potential diagnostic tools for detecting stress-induced cardiac diseases and especially to describe the mechanisms by which stress potentially contributes to the pathogenesis and outcomes of CV diseases.

Objectives: Because the cortisol awakening response (CAR) has received increasing attention as a useful index of adrenocortical activity, the primary objective of this study was to investigate the presence of an awakening response for various salivary biomarkers of adrenocortical activity, including dehydroepiandrosterone-sulphate (DHEA-S), which acts as a cortisol antagonist, and α-amylase, which is a predictor of circulating catecholamine activity. Salivary biological indicators are considered to be valuable markers of hypothalamus-pituitary-adrenal (HPA) axis diurnal activity., Methods: In an attempt to overcome problems associated with non-adherence to the requested sampling protocol, only young, healthy males with a physiological CAR value (defined as a 50% increase in salivary cortisol within 30 min after waking) were included in the study (67 out of 102 who initially enrolled met this criterion)., Results: Our results suggested that, as is already known for cortisol, DHEA-S and α-amylase have significant awakening responses. In addition, daily profile of salivary cortisol, α-amylase and DHEA-S fluctuations were analysed. Significant correlations were found between salivary cortisol, DHEA-S and α-amylase levels. The results showed that cortisol and DHEA-S concentrations were inversely correlated with α-amylase levels., Conclusion: This correlation confirmed the distinctiveness of the two regulatory systems: salivary cortisol and DHEA-S concentrations reflect the activity of the HPA axis, whereas α-amylase activity is more closely related to sympathetic activity. In addition, the present study emphasizes the potential value of saliva collection (which is both easy and stress-free) in monitoring changes of adrenal function, confirming that multiple sampling (especially within 1 h after awakening) is necessary to reliably characterise biomarker activity when investigating neuroendocrine changes under various conditions.