Genotoxicity of Chlorpyrifos and the Antimutagenic Role of Lettuce Leaves in Male Mice

Abstract

Chlorpyrifos [O O-diethyl-O-(3 5 6-trichloro-2-pyridyl)-phosphorothioate] is one of the most widely used organophosphate insecticides. Previous studies proved that chlorpyrifos, at different doses, induced genotoxicity. In Egyptian foods, the residual levels of pesticides are often higher than those found in developed country ones. So the aim of this research was to evaluate the genotoxicity of the insecticide chlorpyrifos at doses equal to its maximum residue limit (MRL) in the leafy vegetables, its double and quadruple (0.5, 1 and 2 mg/kg body weight) in somatic and germ cells of male mice. In addition to that, evaluating the role of lettuce leaves as antigenotoxic in reducing the genotoxic effects of chlorpyrifos tested doses when concurrently administrated to these animals. The study was conducted on adult male laboratory mice at three levels: bone marrow cells as a model for mitotic chromosome aberrations, spermatocytes as a model for meiotic chromosomes and sperm count and morphology. The results of the present study indicate that the treatment of male mice with chlorpyrifos by oral gavages for three months induced significant increase in the frequencies of total chromosomal aberrations in both somatic and germ cells in relation to control groups. Results of the sperm analysis showed that chlorpyrifos induced significant decrease in the sperm count when compared to negative control. Furthermore, it induced significant increase in head and tail sperm abnormalities, among which coiled tail was considered the most obvious sperm abnormality induced by chlorpyrifos. At the same time, the present study indicated that lettuce leaves feed concurrently with three doses of chlorpyrifos could not protect cells from damage.Chlorpyrifos [O O-diethyl-O-(3 5 6-trichloro-2-pyridyl)-phosphorothioate] is one of the most widely used organophosphate insecticides. Previous studies proved that chlorpyrifos, at different doses, induced genotoxicity. In Egyptian foods, the residual levels of pesticides are often higher than those found in developed country ones. So the aim of this research was to evaluate the genotoxicity of the insecticide chlorpyrifos at doses equal to its maximum residue limit (MRL) in the leafy vegetables, its double and quadruple (0.5, 1 and 2 mg/kg body weight) in somatic and germ cells of male mice. In addition to that, evaluating the role of lettuce leaves as antigenotoxic in reducing the genotoxic effects of chlorpyrifos tested doses when concurrently administrated to these animals. The study was conducted on adult male laboratory mice at three levels: bone marrow cells as a model for mitotic chromosome aberrations, spermatocytes as a model for meiotic chromosomes and sperm count and morphology. The results of the present study indicate that the treatment of male mice with chlorpyrifos by oral gavages for three months induced significant increase in the frequencies of total chromosomal aberrations in both somatic and germ cells in relation to control groups. Results of the sperm analysis showed that chlorpyrifos induced significant decrease in the sperm count when compared to negative control. Furthermore, it induced significant increase in head and tail sperm abnormalities, among which coiled tail was considered the most obvious sperm abnormality induced by chlorpyrifos. At the same time, the present study indicated that lettuce leaves feed concurrently with three doses of chlorpyrifos could not protect cells from damage.Genotoxidade de Chlorpyrifos e papel antimutagênico das folhas de alfaces em ratosResumoChlorpyrifos [O O-diethyl-O-(3 5 6-trichloro-2-pyridyl)-phosphorothioate] é um dos inseticidades a basede organofosfato mais utilizados. Estudos anteriores provaram que chlorpyrifos, em doses diferentes,induziu a genotoxidade. Em alimentos egípcios, os níveis residuais de pesticidas são normalmentemais elevados que aqueles encontrados em países desenvolvidos. Então, o objetivo dessa pesquisafoi o de avaliar a genotoxidade do inseticida chlorpyrifos em doses iguais ao limite residual máximo(MRL) em vegetais com folhas, seu dobro e quádruplo (0.5, 1 and 2 mg/kg peso corpóreo) emcélulas somáticas e germinativas de ratos. Além disso, avaliando o papel das folhas de alfacecomo antígenos tóxicos na redução dos efeitos de genotoxidade em doses de chlorpyrifos testadasquando administradas a esses animais. O estudo foi conduzido em ratos adultos de laboratório, emtrês níveis: células ósseas como modelo para aberrações miótico-cromossômicas; espermatócitoscomo modelo meiótico-cromossômico, contagem e morfologia de espermatozóides. Os resultadosdo presente estudo indicaram que o tratamento de ratos com chlorpyrifos, administrado emdoses orais por três meses induziram um significativo aumento da freqüência de aberraçõescromossômicas totais tanto em células somáticas quanto em células germinativas se relacionadosaos grupos de controle. Os resultados da análise de espermatozóide demonstraram que chlorpyrifosinduziu uma diminuição significativa na contagem de espermatozóides quando comparado aogrupo de controle negativo. Além disso, também houve a indução de um aumento significativoem anomalias na cabeça e na cauda dos espermatozóides, dentre as quais a cauda enroladafoi considerada a anomalia mais óbvia entre os espermatozóides induzidos por chlorpyrifos. Aomesmo tempo, o presente estudo indicou que as folhas de alface alimentadas regularmente comtrês doses de chlorpyrifos não conseguiram proteger suas células de danos.