Neuropeptides of the autonomic nervous system in Sjögren's syndrome

To assess the activity level of the autonomic nervous system in Sjögren's syndrome (SS) and to correlate this with stress.

Patients with SS (n = 12) and healthy controls (n = 10) were analysed for the content of vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY) in their stimulated saliva by radioimmunoassays and for stress by the use of a modified Jenkins Activity Survey (JAS).

The data are expressed as median (interquartile range). Salivary VIP output (pg/min) and NPY output (pg/min) were high in SS compared with healthy controls (30.0 (15.6, 36.6) versus 12.3 (9.2, 24.0), p = 0.045, 4.8 (0.6, 24.1) versus 0.7 (0.0, 2.4), p = 0.038, respectively). Patients experienced only a little, but not significantly, more stress than the healthy controls (stress index -2.8 (-7.7, 6.9) versus -5.2 (-12.9, 2.7), p > 0.05). Stress in general was associated with high salivary VIP concentrations (r = 0.41, p = 0.05).

These findings show that adequately processed saliva (containing aprotinin and EDTA as neuropeptidase inhibitors) contains measurable amounts of marker peptides of the autonomic nervous system. Secondly, VIP concentration but not output may be affected by stress, which may act by decreasing watery salivary flow. In patients with SS, VIP and NPY outputs are increased. This may indicate increased leakage into saliva or efforts to compensate for the diminished salivary flow, or both.