Background:Phloroglucinol plays an important role in oxidative stress and inflammatory responses.The effects of phloroglucinol have been proven in various disease models.The aim of the present study was to investigate the efficacy and possible mechanisms of phloroglucinol in the treatment of interstitial cystitis (IC).Methods:Thirty-two female Sprague-Dawley (SD) rats were used in this study.IC was induced by intraperitoneal injection of cyclophosphamide (CYP).Rats were randomly allocated to one of four groups (n =8 per group):A control group,which was injected with saline (75 mg/kg; i.p.) instead of CYP on days 1,4,and 7; a chronic IC group,which was injected with CYP (75 mg/kg; i.p.) on days 1,4,and 7; a high-dose (30 mg/kg) phloroglucinol-treated group; and a low-dose (15 mg/kg) phloroglucinol-treated group.On day 8,the rats in each group underwent cystometrography (CMG),and the bladders were examined for evidence of oxidative stress and inflammation.Statistical analysis was performed by analysis of variance (ANOVA) followed by least square difference multiple comparison post-hoc test.Results:Histological evaluation showed that bladder inflammation in CYP-treated rats was suppressed by phloroglucinol.CMG revealed that the CYP treatment induced overactive bladder in rats that was reversed by phloroglucinol.Up-regulated tumor necrosis factor-α and interleukin-6 expression in the CYP-treated rats were also suppressed in the phloroglucinol treated rats.CYP treatment significantly increased myeloperoxidase activity as well as the decreased activities of catalase of the bladder,which was reversed by treatment with phloroglucinol.Conclusions:The application of phloroglucinol suppressed oxidative stress,inflammation,and overactivity in the bladder.This may provide a new treatment strategy for IC.