INTRODUCTION AND OBJECTIVES: Pelvic organ cross-sensitization has been proposed as one of the pathogenesis of bladder pain syndrome/interstitial cystitis. Thus, we examined changes in bladder function after the stimulation of transient receptor potential (TRP) channels in the colon, uterus or stomach because TRP channels are one of the main nociceptive receptors. METHODS: Under isoflurane anesthesia, a polyethylene catheter was implanted into the colon, uterus or stomach as well as the bladder in female Sprague-Dawley rats, and cystometry was then performed in an awake condition. 1) Capsaicin (TRPV1 activator; 1, 3, 10 & 30mM), R1747 (TRPV4 activator; 1, 3, 10 & 30mM), allyl isothiocyanate (AITC: TRPA1 activator; 1, 3, 10 & 30%) or menthol (TRPM8 activator; 3, 10, 30 & 100%) was cumulatively applied in a 50ul solution of each dose with 30min intervals into the colon, uterus or stomach. 2) Time-dependent changes in bladder function were examined after 30% AITC injection into the colon or uterus. We also examined changes in bladder function when ruthenium red (RR: TRPA1 inhibitor) was intrathecally (i.t.; 0.03ug, 5ul) or intravenously (i.v.; 3mg/kg, 0.5ml/ kg) applied 30min before or 120min after colon AITC injection. RESULTS: 1) There were no significant changes in bladder function after the TRPV1, V4 or M8 stimulation in the colon or uterus, whereas threshold pressure (TP) and intercontraction interval (ICI) were significantly decreased by 10% or greater AITC injection into the colon or 30% AITC injection into the uterus. None of TRP channel stimulations in the stomach influenced bladder function. 2) TP and ICI were significantly decreased from 30 min and 60 min after 30% AITC injection, respectively, in the colon. TP and ICI were significantly decreased 60 min after AITC injection in the uterus, and became stable after 120min. Bladder overactivity induced by colon AITC application was prevented by the pretreatment of RR (i.v. and i.t.). On the other hand, only the i.t., but not i.v., application of RR increased TP and ICI significantly when RR was applied after the induction of colon-toblabber cross-sensitization. CONCLUSIONS: Bladder overacitvity occurs from 30–60 min after the stimulation of TRPA1 channels, but not TRPV1, V4 or M8, in the colon or uterus, indicating the importance of TRPA1 for the pelvic organ cross-sensitization. In addition, central sensitization seems to be involved in the pelvic organ cross-sensitization because i.t. application of a TRPA1 inhibitor can attenuate the colon-to-bladder cross-sensitization.