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Effect of prenatal exposure to α-cypermethrin on DNA methylation patterns in rat sperm

α-cypermethrin belongs to pyrethroids, one of the most used groups of insecticides that can act as endocrine disruptive chemicals (EDCs), known to impact gene expression at the epigenetic level. Testicular exposure to EDCs in foetal development may impair PGC differentiation causing decreased sperm quality and number and increased apoptosis of germ cells, as well as infertility in adults. However, such an effect has still not been established for α- cypermethrin. One of the most studied epigenetic mechanism is DNA methylation, which plays a major role in the de novo silencing of retrotransposon sequences in germ cells, as well as in the establishment of sex-specific imprinting. In this study, we investigated the effect of prenatal exposure to α-cypermethrin on DNA methylation patterns in rat sperm of F1 offspring. Pregnant female Wistar rats were divided into 6 groups. The first three experimental groups (α- cyp1, α-cyp10 and α-cyp19) were treated per os from the 6th up to 21st gestational day with three different doses of α- cypermethrin (1, 10 and 19 mg/kg bw/day). In the same period, the positive control group (PC) was treated with diethylstilbestrol, solvent control group (SC) with corn oil and negative control group (NC) with water. DNA was isolated from the sperm of F1 generation pubertal pups. Subsequently, the methylation level of 3 different CpG sites within repetitive element LINE-1 was analysed for the assessment of global methylation by pyrosequencing method. Additionally, methylation analysis was performed for 7 different CpG sites within the differentially methylated regions (DMRs) of the imprinted genes Igf2 and H19. The results showed no significant difference in the methylation levels of examined DNA sequences of LINE-1 between the experimental groups and the controls. Also, exposure to α-cypermethrin had no effect on the methylation levels of the examined DNA sequences of Igf2 and H19. This study implies to the possibility that prenatal exposure to α- cypermethrin does not affect the de novo DNA methylation process in the rat sperm of F1 offspring and indicates a need for further research of epigenetic changes caused by this endocrine disruptor at the genome-wide level.

pyrethroids ; endocrine disruptive chemicals ; DNA methylation ; sperm ; rat offspring

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