Preventive effect of intravesical ozone supplementation on n-methyl-n-nitrosourea-induced non-muscle invasive bladder cancer in male rats

Although non-muscle invasive bladder cancer (NMIBC) is widely seen in men, most laboratory studies of new intravesical therapies to prevent NMIBC have been conducted on female animals. In addition, ozone (O3) has been shown to be a beneficial agent as an intravesical application in the treatment of various disorders. In the current study, we evaluated the immunohistopathological and oxidative-antioxidative effects of intravesical O3 treatment on n-methyl-n-nitrosourea (MNU)-induced NMIBC. Male Wistar-Albino rats (n=51) were divided into four groups: sham (n=6), O3 only (n=15), MNU only (n=15), and MNU+O3 (n=15). The MNU-only and MNU+O3 groups received MNU, and the O3-only group received saline every other week for 10 weeks. The MNU-only group received 1 ml saline in place of O3 treatment, whereas the O3-only and MNU+O3 groups were treated with 1 ml 25 µg/ml O3 between the 7th and 12th weeks. Rat bladders were collected in the 15th week for immunohistopathology and oxidant-antioxidant quantitation. Oxidant-antioxidant parameters were determined by ELISA. Although all surviving rats in the MNU-only group had preneoplastic (4/11, 36.4%) or neoplastic changes (7/11, 63.6%), a completely normal urothelium was observed in 2 rats (2/12, 16.7%) in the MNU+O3-group (P=0.478). More high-grade lesions were observed in the MNU-only group (4/11, 36.4%) than in the MNU+O3 group (1/12, 8.3%) (P=0.120). All oxidant-antioxidant parameters significantly increased (P<0.05) in the O3-only group compared with the sham group. However, only antioxidant superoxide dismutase was remarkably higher (178.9%, P=0.060) in the MNU+O3 group compared with the MNU-only group. This is the first methodologically and pathologically well-described male rat orthotopic bladder carcinogenesis model with intravesical MNU and administration of O3 in NMIBC.