Role of capsaicin-sensitive sensory nerve reflexes in guinea pig model of nasal allergy.

The aim of this study was to examine the pathophysiological role of capsaicin-sensitive sensory nerves in an animal model of nasal allergy. In ovalbumin (OA)-sensitized guinea pigs, a significant increase in nasal total airway resistance (TAR) was noted for at least 180 min after topical antigen challenge. The TAR response to antigen challenge was significantly inhibited for 120 min by general capsaicin pretreatment (167 +/- 12.1 vs. 113 +/- 5.0%, p < 0.001, and 186 +/- 14.9 vs. 119 +/- 6.6%, p < 0.001, control vs. capsaicin pretreatment group at 20 and 90 min after challenge, respectively). However, TAR was significantly though slightly affected even after general capsaicin pretreatment. Following nasal capsaicin challenge, TAR increased for 90 min, and nasal secretion for 30 min. Both the TAR and secretory responses to nasal capsaicin challenge were significantly greater in OA-sensitized guinea pigs than in nonsensitized animals (171 +/- 12.1 vs. 137 +/- 7.4% at 30 min, p < 0.05, and 82.3 +/- 8.6 vs. 13.4 +/- 1.7 mg/10 min, p < 0.05, TAR and secretory response to 300 microM nasal capsaicin challenge, respectively). These results suggest that capsaicin-sensitive sensory nerve reflexes play an important role in the occurrence of early-phase nasal symptoms following topical antigen exposure and are accelerated in OA-sensitized guinea pigs.