Psychological Stress and Its Influence on Salivary Flow Rate, Total Protein Concentration and IgA, IgG and IgM Titers

Abstract

The hypothalamic-pituitary-adrenal and sympathetic-adrenomedullary axes are the main systems activated in response to stress. Alterations in salivary components and flow rate have been associated with oral health problems and psychological stress. Objectives: The aim of the present study was to investigate the influence of psychological stress on salivary flow, total protein concentration and IgG, IgM and IgA concentrations. Methods: Thirty-eight medical students, average age of 21.4 ± 2.1 years and enrolled in the 2nd to 5th years of their course, took part voluntarily in the study which involved two different periods: the first after vacations and the second during the final exams (a gap of 4 months). An Oral Health Questionnaire and the Lipp Inventory of Stress Symptoms for Adults (ISSL) were applied during both these periods. The flow rate, total protein concentration and immunoglobulin titers of saliva samples, collected after stimulation and stored in a container with protease inhibitor, were measured. Results: Analysis of the ISSL showed that 42.1% (n = 16) of the students had stress during the post-vacation period, and 44.7% (n = 17) during the final exams. The students’ salivary flow rate was significantly lower during the latter period than during the post-vacation period (p < 0.0001), regardless of the presence or absence of psychological stress as measured by the ISSL. There was a reduction in salivary flow rate and a consequent reduction in total protein concentration during the exam period (p = 0.0058). However, during both periods of the study there was no significant difference in total salivary protein concentration between the groups of students with or without psychological stress according to the ISSL (p > 0.05). IgG predominated over IgA and IgM (p < 0.001) during both study periods, regardless of the presence or absence of psychological stress. The study period and the presence of stress influenced the secretion of salivary immunoglobulins. IgM titers during the post-vacation period (p = 0.0044), and IgA (p = 0.028), IgG (p = 0.022) and IgM (p = 0.0075) titers during the final exams were higher in students with symptoms of psychological stress. Conclusions: Although the immunoglobulin titers were high, there was a reduction in the students’ salivary flow rates and a consequent reduction in total protein concentrations.