Sensitivity of salivary hydrogen sulfide to psychological stress and its association with exhaled nitric oxide and affect

Abstract Background Hydrogen sulfide (H 2 S) is the third gasotransmitter recently discovered after nitric oxide (NO) and carbon monoxide. Both NO and H 2 S are involved in multiple physiological functions. Whereas NO has been shown to vary with psychological stress, the influence of stress on H 2 S and the relationship between H 2 S and NO are unknown. We therefore examined levels of salivary H 2 S and NO in response to a stressful final academic exam period. Methods Measurements of stress, negative affect, and fraction of exhaled NO (FE NO ), were obtained from students ( N  = 16) and saliva was collected at three time points: low-stress period in the semester, early exam period, and late exam period. Saliva was immediately analyzed for H 2 S with the fluorescent probe Sulfidefluor-4. Results H 2 S increased significantly during the early exam period and FE NO decreased gradually towards the late exam period. H 2 S, FE NO , negative affect, and stress ratings were positively associated with each other: as stress level and negative affect increased, values of H 2 S increased; in addition, as FE NO levels decreased, H 2 S also decreased. Asthma status did not modify these associations. Conclusion Sustained academic stress increases H 2 S and these changes are correlated with NO and the experience of stress and negative affect. These findings motivate research with larger samples to further explore the interaction and function of H 2 S and FE NO during psychological stress.