Effect of nasal allergen challenge on serotonin, substance P and vasoactive intestinal peptide in plasma and nasal secretions

Abstract

We have studied the changes in concentration of serotonin, substance P, and vasoactive intestinal peptide (VIP) in plasma following a nasal allergen provocation in 14 grass pollen-allergic subjects; in five the urinary excretion of serotonin and 5-hydroxy-indolylacetic acid (5-HIAA) was also measured. In addition, the concentration of serotonin and substance P was measured in nasal secretions following nasal challenge with allergen and methacholine. The results showed an allergen-increase in free plasma serotonin (P < 0.01) and no change in platelet serotonin, urinary serotonin and urinary 5-HIAA. The plasma substance P level tended to fall (P > 0.1), while plasma VIP increased significantly (P < 0.02). In nasal secretions, there were measurable levels of serotonin in all samples and of substance P in all but one. There was no difference between the concentrations of serotonin and substance P in secretions collected after allergen challenge and after methacholine challenge. For both substances, the secretion median value was comparable to that of plasma. Symptom reduction by topical and systemic pretreatment with a serotonin- and VIP-antagonist before nasal allergen provocation is necessary to define the role of these two agents in allergic rhinitis.