RESUMEN
BACKGROUND: Acute mucosal inflammation may initiate alterations of visceral sensory function. However, experimental studies on the potential effects of a transient inflammation on visceral sensitivity are lacking. METHODS: We performed colorectal distensions with a barostat device in fasted, conscious, male Lewis rats (n = 20) and assessed the nociceptive response (visceromotor response; VMR) to tonic colorectal distension (CRD) (60 mmHg/3 min) by abdominal-wall electromyography. Measurements were taken before and 3, 5 and 14 days after induction of a transient and self-limiting colitis by instillation of trinitrobenzenesulphonic acid (TNB)/ethanol (or saline as control). Tissue samples from paired controls were obtained to assess histological tissue alterations. RESULTS: TNB/ethanol but not saline induced an acute colitis, with most severe histological lesions occurring 5 days after instillation. After 14 days, there was no histological evidence for persisting mucosal alterations. Five days after induction of TNB/ethanol colitis, the VMR to CRD reached a transient increase (P < 0.05 v. baseline), which returned to baseline levels by day 14. In control experiments (rectal saline instillation), the VMR to CRD decreased significantly compared with baseline values (P < 0.05). CONCLUSION: Following an acute colitis due to single colorectal instillation of TNB/ethanol, histological changes are associated with an enhanced nociceptive response to CRD.