Salivary cortisol and nitrite concentrations in school teachers: A longitudinal pilot study

Occupational/mental stressors, which may be evaluated with measurements of salivary cortisol concentrations, affect the endothelial function and has implications on cardiovascular health. Nitric oxide (NO) is known to have an important role in cardiac function and may also be assessed in the saliva, but its participation in physiological responses to hypothalamic-pituitary-adrenal (HPA) axis stimulation is still not completely understood. The aim of the present study was to test the hypothesis that salivary NO (as nitrite) and cortisol concentrations in school teachers vary throughout the academic year.

Saliva samples were collected from 13 teachers distributed across five secondary schools. The samples were collected at 6:30 a.m., 11:30 a.m., and 5:30 p.m. in the months of March, July, and December. Salivary cortisol levels were measured by enzyme immunoassay (EIA), and salivary NO concentration was determined by the quantification of nitrite. The area under the curve in relation to ground (AUC) was calculated to assess the cortisol and nitrite concentrations throughout the day.

No significant changes were observed in cortisol or nitrite concentrations across the three periods of the school year, while cortisol and nitrite levels showed a low positive and significant correlation (r=0.3455, p=0.0336).

The results suggest that changes in salivary cortisol levels are accompanied by changes in salivary nitrite levels. This is the first time that such association has been demonstrated. These results encourage further studies aimed to confirm the importance of salivary NO measurement in relation to occupational stress and cardiovascular health.