DNA fragmentation in leukocytes following repeated low dose sarin exposure in guinea pigs

Abstract

The objective of this study was to determine levels of DNA fragmentation in blood leukocytes and parietal cortex from guinea pigs following repeated lowlevel exposure to the chemical warfare nerve agent (CWNA) sarin. Guinea pigs were injected (s.c.) once a day for 10 days with saline, or 0.1, 0.2, or 0.4 LD 50 (50 % mean lethal dose) sarin dissolved in sterile physiological saline. Blood and parietal cortex was collected after injection at 0, 3, and 17 days recovery and evaluated for DNA fragmentation using single-cell gel electrophoresis (Comet assay). Cells were imaged using comet analysis software and three parameters of DNA fragmentation measured: tail length, percent DNA in the tail, and tail moment arm. Repeated low-dose exposure to sarin produced a dose-dependent response in leukocytes at 0 and 3 days post-exposure. There was a significant increase in all measures of DNA fragmentation at 0.2 and 0.4 LD 50 , but not at 0.1 LD 50 . There was no significant increase in DNA fragmentation in any of the groups at 17 days post-exposure. Sarin did not produce a systematic dose-dependent response in parietal cortex at any of the time points. However, significant increases in DNA fragmentation at 0.1 and 0.4 LD 50 were observed at 0 and 3 days post-exposure. All measures of DNA fragmentation in both leukocytes and neurons returned to control levels by 17 days post-exposure, indicating a small and non-persistent increase in DNA fragmentation following repeated low-level exposure to sarin.

The evaluation of oxidative damage of DNA after poisoning with nerve agents

“…However, sarin was administered repeatedly for 10 days in above mentioned study. No significant increase in DNA fragmentation in any experimental group at 17 days after sarin exposure was found (Dave et al, 2007). Our results presented in this paper confirm the ability of sarin, soman and tabun to induce the DNA damage in vivo.…”

“…In the case of poisoning with sublethal doses of nerve agents studied, no significant DNA damage was observed. According to our knowledge, there is only one paper decribing the induction of the DNA damage by sarin in the blood leucocytes and parietal cortex in vivo in guinea pigs, which describes an increase in DNA fragmentation at 0.2 and 0.4 LD 50 , but not at 0.1 LD 50 (Dave et al, 2007). However, sarin was administered repeatedly for 10 days in above mentioned study.…”

Assessment of Potential Long Term Health Effects on Army Human Test Subjects of Relevant Biological and Chemical Agents, Drugs, Medications and Substances

“…In a case-control study of 594 skin lesion cases and 1041 controls, the dose-response relationship of skin lesion risk was significantly higher in individuals with the 677TT/1298AA and 677CT/1298AA diplotypes in the methylenetetrahydro-folate reductase (MTHFR) enzyme (1.66 and 1.77 respectively), than for those with the 677CC/1298CC diplotype. 165 The OR for skin lesions in relation to the GSTO1 diplotype (Glutathione S-transferase 1) containing all at-risk alleles was 3.91. 166 These early changes in the skin associated with arsenic also predispose to the development of a variety of skin cancers, and a squamous cell carcinoma (in situ) known as Bowen's Disease may also develop.…”

“…The HEALS group of researchers also found that males and elderly people are more affected by arsenic exposure, (Ahsan 2006b) as were those with excessive sun exposure, 161 lower nutritional status, 162,163 and lower socioeconomic status (non-land owners). 164,165 Genetic variability in genes that code for enzymes in arsenic metabolism may also affect individual susceptibility to skin lesions. In a case-control study of 594 skin lesion cases and 1041 controls, the dose-response relationship of skin lesion risk was significantly higher in individuals with the 677TT/1298AA and 677CT/1298AA diplotypes in the methylenetetrahydro-folate reductase (MTHFR) enzyme (1.66 and 1.77 respectively), than for those with the 677CC/1298CC diplotype.…”