NF-κB Activation Precedes Increases in mRNA Encoding Neurokinin-1 Receptor, Proinflammatory Cytokines, and Adhesion Molecules in Dextran Sulfate Sodium–Induced Colitis in Rats

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Abstract
Nuclear factor kappa B (NF-κ B) plays a key role in initiating inflammation associated with colitis. A systematic study was conducted in the rat DSS colitis model to determine the temporal relationship between NF-κ B activation and expression of substance P (SP), neurokinin-1 receptor (NK-1R), proinflammatory cytokines, and adhesion molecules. Rats were given 5% DSS in their water and sacrificed daily for 6 days. Colon tissue was collected for assessment of histological changes, NF-κ B activation, myeloperoxidase (MPO) activity, and expression of NK-1R, SP, TNFα, IL-1β, VCAM-1, ICAM-1, E-selectin, CINC-1, MIP-1α, and iNOS. NF-κ B activation increased, biphasically, on Day 1 and again on Days 4–6. The mRNA levels for ICAM-1, CINC-1, IL-1β, TNFα, VCAM-1, and NK-1R rose significantly (P< 0.05) by 2–4 days. Increased iNOS mRNA levels, MPO activity, and mucosal damage occurred on Day 6. These data demonstrate that NF-κ B activation substantially precedes the onset of physical disease signs and active inflammation.