Determination of salivary α-amylase and cortisol in psoriatic subjects undergoing the Trier Social Stress Test

Abstract

The study was aimed to investigate the response in psoriatic patients of the two primary neuroendocrine systems, namely the Autonomic Nervous System and the Hypothalamic-Pituitary-Adrenal (HPA) axis, whose main biomarkers of activation are salivary α-amylase and cortisol, respectively. Reliable analytical procedures for the determination of salivary α-amylase enzymatic activity and cortisol concentration in oral fluid were developed. The non-invasive sampling that does not require trained personnel represents one of the main advantages of oral fluid analysis compared to the analysis of blood and its derivatives (e.g. plasma). Since oral fluid offers the advantage of a simple and stress free sample collection, it is particularly useful to quantify stress related molecules.α-amylase activity was measured by a spectrometric method, whereas salivary cortisol by Reversed-Phase High-Performance Liquid Chromatography coupled to Electrospray Ionization Quadrupole Time-of-Flight Mass Spectrometry. The effect of salivary pH and flow rate on salivary α-amylase activity and cortisol were also investigated.Finally, both methods were preliminary tested on oral fluid samples of psoriatic volunteers underwent to a psychosocial stress task (the Trier Social Stress Test), as a first step of a more comprehensive study on the responsiveness of psoriatic subjects to stressors.