Cyclophosphamide-induced Chronic Cystitis Enhances Pain Behavior and Bladder Capacity Reduction Elicited by Resiniferatoxin in Rats

212 CYCLOPHOSPHAMIDE-INDUCED CHRONIC CYSTITIS ENHANCES PAIN BEHAVIOR AND BLADDER CAPACITY REDUCTION ELICITED BY RESINIFERATOXIN IN RATS Tomohiko Oguchi, Osamu Nishizawa, Naoki Yoshimura The authors note that while rats with chronic cystitis induced by repeated cyclophosphamide (CYP) injections have been used for basic research of hypersensitive bladder disorders including BPS/IC, changes in pain behaviour and voiding function in this model have not been well characterized. In this study, they therefore evaluated voiding and nociceptive behaviour following intravesical application of resiniferatoxin (RTX) to see whether frequent voiding and pain sensation are increased in these rats. They found that while bladder overactivity usually seen in rats with acute cystitis subsided after repeated CYP treatments, rats with CYP-induced chronic cystitis exhibit bladder hypersensitivity resulting in increased pain behaviour and smaller bladder capacity when afferent pathways are stimulated by RTX (TRPV1 stimulator). They consequently concluded that this chronic cystitis animal model can be considered to be suitable for studying pathophysiological mechanisms inducing chronic pelvic pain conditions in hypersensitive bladder disorders including BPS/IC.