Effects of Aroclor 1254 on the DNA methylation of imprinted genes in the adult mouse sperm

Abstract

As estrogen-like and anti-androgenic endocrine-disrupting chemicals, polychlorinated biphenyls have been reported to affect the male reproductive axis resulting in infertility. In the present study, Aroclor 1254 was administered to adult male mice, and its possible effects on the differentially methylated regions of two paternally (H19 and Gtl2) and three maternally (Mest, Snrpn and Igf2r) imprinted genes were tested in the sperm DNA. In the control, the percentages of methylated CpGs were close to 100% and 0% in paternally or maternally imprinted genes respectively. Aroclor 1254 significantly decreased the percentages of methylated CpGs of H19 and Gtl2 and markedly increased those of Mest, Snrpn, and Igf2r. In addition, dramatically increased mRNA expression of estrogen receptor α and β were obtained in the treatment. We postulate that the effects of PCBs on male spermatogenesis and fertility rates might involve imprinting alterations in the sperm.