Prolonged pre-treatment with RTX blocked BDNF expression in L1 DRG during colonic inflammation. In vehicle-treated animals, colonic inflammation increased the level of BDNF in the L1 DRG at 3 days post TNBS treatment (A, B, E). Following prolonged RTX pre-treatment, the level of BDNF in L1 DRG from the inflamed animals was attenuated to almost normal level (D, E). Bar = 40 μm, *, p < 0.05 vs. control; #, p < 0.05 vs. TNBS-treated. n = 4 animals for each experimental group.