Fig 1. Scheme of the two experimental set-ups.

In set-up 1 (acute colitis), rats were instilled with TNBS (colitis) or saline (control) and further experiments were conducted 3 days later, during the acute phase of colitis. In set-up 2 (post-colitis), rats were instilled with TNBS or saline and the extent of colitis and the healing process were monitored individually by repeated colonoscopy: first on day 3 to confirm the presence of colitis and thereafter, starting from day 10, every 4 days until complete mucosal healing (score = 0) occurred. Further experiments were conducted 3 days after colonoscopically proven mucosal healing. A-317491 (10–25 mg/kg) or vehicle (saline), denoted by the injection needle, was administered 30 min prior to the start of the VMR protocol. Evaluation of the inflammatory status entailed colonoscopy, macroscopic and microscopic assessment of the colonic tissue in addition to a myeloperoxidase activity (MPO) assay. ATP, adenosine 5’-triphosphate; DRG, dorsal root ganglion; IHC, immunohistochemistry; RT-PCR, reverse transcription polymerase chain reaction; TNBS, trinitrobenzene sulphonic acid; VMR, visceromotor response.