Mice were instilled with vehicle or P2 purinergic receptor antagonist PPADS (200 μmoles/kg) prior to intranasal instillation of vehicle or ATP (400 nmoles/kg). 20 hrs later, OE tissue was collected and assayed for NPY levels by enzyme immunoassay. n = 5, 4, 4, 3 animals each treatment.*, p<0.05 v. vehicle/saline group. #, p<0.05 v. vehicle/ATP group (two-way ANOVA followed by Bonferroni post-hoc test).