The effects of sulfasalazine, 5-ASA, and sulfapyridine on toxin A-induced substance P release in the colon. Laser scanning confocal fluorescent micrographs of neurons immunostained for the NK-1R from colonic segments treated for 3 h with (a) vehicle, (b) 5 μg toxin A, (c) 5 μg toxin A after 5 days of treatment with sulfasalazine (100 mg/kg·day), (d) 5 μg toxin A after 30 minutes of intraluminal pretreatment with 5-ASA (100 μg), and (e) 5 μg toxin A after 30 minutes of intraluminal pretreatment with sulfapyridine (100 μg). Bar, 5 μm.
