Modifying effect of vitamin C and N-acetylcysteine againts cyclophosphamide-induced DNA damage in exfoliated bladder cells of mice

People are exposed to many carcinogenic and mutagenic chemical in their everyday lifes. These include; antineoplastic drugs, PAHs, aromatic amines, nitrosamines, metals and radiation. Although the human body has developed a variety of defense mechanisms for its protection against such chemicals, increasing exposure to hazardous chemicals can lead to mutagenic and carcinogenic events in our cells. Thus, there is a need to indetify and use agents which can suppress the mutagenic and/or carcinogenic ability of environmental chemicals. In the present study, our aim was; to evaluate whether cyclophosphamide (CP) is a model mutagen to screen the genotoxic damage in exfoliated bladder cells of mice, and to obtain information about the modulating effect of vitamin C and N-acetylcysteine including dose-response association against CP- induced genotoxic damage by micronucleus (MN) test. Exfoliated cells were scraped "from the bladder of mice at 2,5,7,10,15 and 17 days after i.p. treatment with a 51.6mg/kg of CP to evaluate the maximum response time of CP. The mean (±S.D) MN frequencies (%o) for different treatment times were found as 4.0 (±1.16), 8.5 (±1.00), 11.9 (±0.50), 17.0 (±2.68), 9.3 (±1.71), 4.0 (±0.50) respectively. The number of micronucleated cells was increased at 2,5,7, days, and greatest at 10th day. At 15th and 17th days after treatment a decreasing trend was observed. The maximal response in frequency of MN occurred 10 days after treatment. To determine the dose-response association at 10 days, animals were treated with CP at doses of 12.9mg/kg, 25.8mg/kg, 51.6mg/kg and 64.5mg/kg. The mean (±S.D) MN frequencies (%o) by dose groups were found as 5.0 (±1.41), 7.25 (±0.50), 15.3 (±4.35), 17.8 (±5.35) respectively. CP at dose of 51.6mg/kg showed significant increases in MN frequencies when compared with103 that doses of 12.9mg/kg and 25.8mg/kg (p<0.05) while for the dose of 64.5mg/kg was not significant (p>0.05). Three doses (10,30 and 60mg/kg) of vitamin C were intraperitoneally administered twice, one dose 24 h prior to the positive mutagen cyclophosphamide and the second dose simultaneously to the positive mutagen. Mean (±S.D) frequencies of MN (%o) in exfoliated bladder cells by dose groups were found as 9.7 (±1.50), 8.1 (±2.90), 7.0 (±2.27) respectively. All the three doses of Vitamin C showed a significant inhibitory effect on MN frequencies in mouse bladder cells when compared with those of positive control group (16.5±3.55) (p<0.05). Dose-dependent inhibitory effect of vitamin C was only obsorved between at doses of 10mg/kg and 60mg/kg (p<0.05). Three doses (200,400 and 800mg/kg) of N-acetylcysteine were administered by gavage for consecutive days before the injection of CP. Mean (±S.D) frequencies of MN (%o) in exfoliated bladder cells were obsorved by dose groups as 7.66 (±2.94), 8.39 (±3.54), 5.0 (±1.41) respectively. All the three doses of N-acetylcysteine showed a significant inhibitory effect on MN frequencies in mouse bladder cells when compared with those of positive control group (17.0±3.09) (p<0.05). Although there is a trend towards decreasing MN frequencies increasing with the dose the number of MN in bladder cells was not dose dependent (p>0.05). In the present study, it has been observed that treatment with vitamin C and N-acetylcysteine have reduced the CP-induced MN frequencies in exfoliated bladder cells by 41-70 % in all cases. The modifying effects of vitamin C and N-acetyl cysteine against CP-induced genotoxic damage may be due to the their antioxidant, nucleophilic properties and to the ability to act as a precursor of GSH.104 Our results suggest that CP-induced MN test in exfoliated cells from the bladder of mice appears to a promising assay to get information on the antigenotoxic effects of several synthetic and natural compounds depending on the dose and time of treatment.