Hepatoprotective effects of antioxidants against non-target toxicity of the bio-insecticide spinosad in rats

The bio-insecticide spinosad (SPD) is increasingly being used in pest management programmes. In order to further assess its toxic effects to non-target species, male rats were exposed sub-chronically to SPD at a dose equivalent to (1/20) LD50 for four weeks. In order to assess the toxicity of SPD, parameters such as the activities of enzymes and concentrations of non-enzymatic antioxidant components, histopathological examination, DNA fragmentation and chromosomal aberrations in liver were analysed. Protection by an antioxidants mixture (AM), containing vitamin C, vitamin E and silymarin, against the effects of SPD was investigated. Exposure to SPD inhibited the activity of acetylcholinestrase, and depleted contents of reduced glutathione and malondialdehyde. SPD caused signification inhibition of activity of key antioxidant enzymes (GST, SOD) and induction in GPx. Treatment with AM attenuated all SPD-mediated effects. Histological examination of the liver revealed that SPD caused focal necrosis and degenerative changes in hepatocytes, along with cytoplasmic vacuolation. All of these lesions were significantly less in rats fed with AM. SPD accelerated formation of internucleosomal DNA fragmentation, which was attenuated by treatment with AM. Similarly, SPD caused significant structural chromosomal aberrations in bone marrow cells, the frequency of which was diminished by AM.