GENOTOXICITY OF ETHIDIUM BROMIDE AND ITS PROTECTION BY SOME PROBIOTIC IN MICE

Abstract

This study was conducted to investigate the genotoxicity of ethidium bromide (EtBr) and modulating effects of lactic acid bacteria (supplemented by NIDO® powdered-milk) as a kind of probiotic on this genotoxic damage in mice. Animals were randomly divided into seven groups each of which represented different treatment. The first group is the control group. The consecutive three groups treated with EtBr added to the drinking water with separate three doses (40 mg/kg body weight, 50 mg/kg body weight, and 60 mg/kg body weight). In the three following groups the same doses of EtBr were used) in addition to a single dose (24 x 107 CFU/g) of probiotic bacteria carried on a commercial powder milk mixed with ordinary food. After one month of daily application of these treatments, all mice were killed and autopsied to get the liver. The effect of tested materials was evaluated on histological and molecular levels. Histological examination, DNA fragmentation assay, and Quantitative Polymerase Chain Reaction (q-PCR) were conducted. Microscopic examination of liver tissues showed many hepatocellular problems in treated mice compared with control group. Fatty change was the hallmark of both the high dose (60 mg/kg b.w) and median lethal dose (50 mg/kg b.w) of EtBr, while the low dose (40 mg/kg b.w) was marked by the emergence of bleeding. Probiotic was not lucky in full confronting those histological problems resulting from EtBr, but the liver also appeared variable than the ordinary. However, there was no fragmented DNA obtained by all treatments in comparison with control group. While, EtBr led to relative induction of p53 gene expression, which appeared higher than a normal state. With a note of a positive relationship between gene expression and the dosage used of ethidium bromide. In the presence of probiotics, p53 gene expression gradually declined, which explains the appearance of tumors in those treatments only.The current study suggests that EtBr is genotoxic and cytotoxic agentbut that is conditioned with used dose. Interestingly, LAB did not show the expected performance as antigenotoxic and anticytotoxic agent, which may be due to the conditions of the experiment, the used dose or the manner through which probiotic was applied.

Key words: Genotoxicity, Ethidium Bromide, Probiotics, p53, Quantitative Polymerase Chain Reaction (q-PCR), DNA fragmentation analysis, and Histology.