Acute Short-Term Mental Stress Does Not Influence Salivary Flow Rate Dynamics

Abstract

Background: Results of studies that address the influence of stress on salivary flow rate and composition are controversial. The aim of this study was to reveal the influence of stress vulnerability and different phases of stress reactivity on the unstimulated and stimulated salivary flow rate. We examined that acute mental stress does not change the salivary flow rate. In addition, we also examined the salivary cortisol and protein level in relation to acute mental stress stimuli. Methods: Saliva of male subjects was collected for five minutes before, immediately, 10, 30 and 120 min after toothbrushing. Before toothbrushing, the subjects were exposed to acute stress in the form of a 2 min public speech. Salivary flow rate and total protein was measured. The physiological stress marker cortisol was analyzed using enzyme-linked immunosorbent assay. To determine the subjects' psychological stress reaction, the State-Trait-Anxiety Inventory State questionnaire (STAI) data were obtained. The subjects were divided into stress subgroup (S1) (psychological reactivity), stress subgroup (S2) (psychological and physiological reactivity) and a control group. The area under the curve for salivarycortisol concentration and STAI-State scores were calculated. All data underwent statistical analysis using one-way analysis of variance. Results: Immediately after stress exposure, all participants exhibited a psychological stress reaction. Stress exposure did not change the salivary flow rate. Only 69% of the subjects continued to display a physiological stress reaction 20 minutes after the public talk. There was no significant change in the salivary flow rate during the psychological and the physiological stress reaction phases relative to the baseline. Conclusions: Acute stress has no impact on the salivary flow rate; however, there may be other responses through salivary proteins that are increased with the acute stress stimuli. Future studies are needed to examine specific proteins and their possible roles in acute stress responses.

Stress-Induced Increase in Kynurenic Acid as a Potential Biomarker for Patients With Schizophrenia and Distress Intolerance

“…Furthermore, previous studies have found that acute mental stress can increase protein concentration without decreasing salivary flow rate. 37,38 …”

Dynamic changes in saliva after acute mental stress

“…Saliva consists of more than 99% water7; therefore, the saliva was presumed to have the same density as water (1 g ≙ 1 ml)814.…”

“…The stress reaction was determined as previously described14 by analyzing saliva cortisol concentration. A significant increase in salivary cortisol concentration after the public speech compared to baseline values indicated a positive stress reaction.…”

“…Usually, salivary composition and saliva's consequent traits undergo fluctuations due to the influence of various factors: daily and seasonal circadian rhythms11, taste and smell12 and short-term acute mental stress1314. The complex patterns of salivary responsiveness during mental stress are reflected by an increase in total salivary protein concentration131415 and changing cortisol levels16.…”

“…The complex patterns of salivary responsiveness during mental stress are reflected by an increase in total salivary protein concentration131415 and changing cortisol levels16.…”