Effect of 5-aminosalicylic acid on radiation-induced micronuclei in mouse bone marrow

5-Aminosalicylic acid (5ASA), a prescribed drug for ulcerative colitis, is a potent scavenger of oxygen-derived free radicals. The present study was undertaken to ascertain its ability to protect against radiation-induced damage. The drug dose-dependent effect, optimum time of drug administration and radiation dose-dependent effect (0-4Gy) on in vivo radiation protection against micronuclei induction in polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) were studied in the bone marrow of mice. Intraperitoneal injection of 10-125mg/kg of the drug 30min before whole body irradiation with 3Gy produced a significant reduction in the frequency of micronucleated erythrocytes at 24h after exposure. The optimum dose for protection without drug toxicity was 25mg/kg body weight. Injection of 25mg/kg of the drug 60 or 30min before or within 15min after 3Gy whole body γ-irradiation resulted in a significant decrease in the radiation-induced PCE and NCE with micronuclei (MPCE and MNCE) and an increase in the ratio of PCE to NCE (P/N), at 24h post-irradiation. Maximum effect was seen when the drug was administered 30min before irradiation. Therefore, to study the radiation dose-response, mice were pre-treated with 25mg/kg of 5ASA 30min before 1-4Gy of γ-irradiation. Radiation increased the MN frequency linearly (r2=0.99) with dose. Pre-treatment with 5ASA significantly reduced the MN counts to 40-50% of the radiation (RT) alone values, giving a dose modification factor (DMF) of 2.02 (MPCE) and 2.53 (MNCE). Irradiation resulted in a dose-dependent decline in the P/N ratio at all the doses of radiation studied. 5ASA produced a significant increase in the P/N ratio from that of irradiated controls, at all doses of radiations tested. These results show that 5ASA protect mice against radiation-induced MN formation and mitotic arrest. © 2003 Elsevier Science B.V. All rights reserved.