**2.5 Other salivary possible biomarkers**

Salivary alpha-amylase (sAA) has been reported to show a transient increase against shortterm laboratory stressors along with the activation of sympathetic nervous system mediated via beta-receptor (van Stegeren, 2006; Deguchi, 2006; Yamaguchi, 2004;). Therefore it is also considered to be a possible biomarker representing SAM system activity (Bosch, 2002). However it is suggested that the activation of parasympathetic nervous system also results in a transient increase of sAA mediated via increment of saliva flow rate (Bosch, 2002).

Regarding with chronic stress sAA was reported to have no remarkable association with depression, anxiety, work stress and burnout but a small negative correlation between "social difficulties" measured with a chronic stress scale in a population of nurses (Wingenfeld, 2010). Recently alpha-amylase is used to highlight the difference in the activity of SAM system and HPA system which is measured by salivary cortisol (Strahler, 2010), and a study reported that the salivary alpha-amylase over cortisol ratio, named as AOCg, can be a better indication of stress system dysregulation than sAA or cortisol alone (Ali, 2011).

Free-3-mehoxy-4-hydroxyphenylglycol (free-MHPG) (Okamura, 2010; Buchsbaum, 1981) and testosterone was reported to show transient increase by short-term laboratory stressors, while the number of studies assessing these substances are very small and frequently showed inconsistent results (e.g. Schoofs, 2011).
