Mouse spermatocytes express CYP2E1 and respond to acrylamide exposure

PLoS One. 2014 May 2;9(5):e94904. doi: 10.1371/journal.pone.0094904. eCollection 2014.

Abstract

Metabolism of xenobiotics by cytochrome P450s (encoded by the CYP genes) often leads to bio-activation, producing reactive metabolites that interfere with cellular processes and cause DNA damage. In the testes, DNA damage induced by xenobiotics has been associated with impaired spermatogenesis and adverse effects on reproductive health. We previously reported that chronic exposure to the reproductive toxicant, acrylamide, produced high levels of DNA damage in spermatocytes of Swiss mice. CYP2E1 metabolises acrylamide to glycidamide, which, unlike acrylamide, readily forms adducts with DNA. Thus, to investigate the mechanisms of acrylamide toxicity in mouse male germ cells, we examined the expression of the CYP, CYP2E1, which metabolises acrylamide. Using Q-PCR and immunohistochemistry, we establish that CYP2E1 is expressed in germ cells, in particular in spermatocytes. Additionally, CYP2E1 gene expression was upregulated in these cells following in vitro acrylamide exposure (1 µM, 18 h). Spermatocytes were isolated and treated with 1 µM acrylamide or 0.5 µM glycidamide for 18 hours and the presence of DNA-adducts was investigated using the comet assay, modified to detect DNA-adducts. Both compounds produced significant levels of DNA damage in spermatocytes, with a greater response observed following glycidamide exposure. A modified comet assay indicated that direct adduction of DNA by glycidamide was a major source of DNA damage. Oxidative stress played a small role in eliciting this damage, as a relatively modest effect was found in a comet assay modified to detect oxidative adducts following glycidamide exposure, and glutathione levels remained unchanged following treatment with either compound. Our results indicate that the male germ line has the capacity to respond to xenobiotic exposure by inducing detoxifying enzymes, and the DNA damage elicited by acrylamide in male germ cells is likely due to the formation of glycidamide adducts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acrylamide / metabolism
  • Acrylamide / toxicity*
  • Animals
  • Cytochrome P-450 CYP2E1 / genetics*
  • Cytochrome P-450 CYP2E1 / metabolism*
  • DNA Adducts / metabolism
  • Environmental Pollutants / metabolism
  • Environmental Pollutants / toxicity*
  • Epoxy Compounds / toxicity
  • Gene Expression Regulation, Enzymologic / drug effects*
  • Male
  • Meiosis / drug effects
  • Mice
  • Oxidation-Reduction / drug effects
  • Spermatocytes / drug effects*
  • Spermatocytes / metabolism*

Substances

  • DNA Adducts
  • Environmental Pollutants
  • Epoxy Compounds
  • Acrylamide
  • glycidamide
  • Cytochrome P-450 CYP2E1

Grants and funding

This work was supported by funding from Hunter Medical Research Institute, The Australian Research Council Centre of Excellence in Biotechnology and Development (CE0348239) and the University of Newcastle. B.J.N. is the recipient of an Australian Postgraduate Award from the Commonwealth of Australia. A.L.K. is the recipient of a Faculty of Science and Information Technology Research Training Scholarship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.