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Butyl paraben‐induced changes in DNA methylation in rat epididymal spermatozoa

Parabens have been shown to affect male rodent reproductive parameters, including testosterone levels and sperm production. In this study, we examined the effect of long‐term exposure to butyl paraben (BP) on rat epididymal sperm DNA methylation. Adult male rats were exposed to BP (0, 10, 100 and 1000 mg kg−1 per day) according to OECD TG407 for a repeated 28‐day oral toxicity study. Sperm DNA methylation was examined by differential display random amplification of polymorphic DNA (RAPD) following methylation‐specific restriction digestion of DNA. Among the 57 RAPD amplicons, six were methylation specific. Of these, five amplicons increased by 1.4‐ to 3.8‐fold in epididymal sperm DNA at testing dose of BP. This indicates that BP can cause DNA hypermethylation in germ cells from the mitotic through post‐meiotic stage in adult rat testes. To our knowledge, this is the first report on the epigenetic modification of sperm DNA by parabens.