Effect of tamoxifen treatment on global and insulin-like growth factor 2-H19 locus-specific DNA methylation in rat spermatozoa and its association with embryo loss

Objective

To determine the effect of tamoxifen treatment on global and insulin-like growth factor 2-H19 imprinting control region (Igf2-H19 ICR)-specific DNA methylation in rat spermatozoa and analyze its association with postimplantation loss.

Design

Experimental prospective study.

Setting

Animal research and academic research facility.

Subject(s)

Male and female 75-day-old Holtzman rats.

Intervention(s)

Global and Igf2-H19 ICR-specific DNA methylation was analyzed in an epididymal sperm sample in control and tamoxifen-treated rats at a dose of 0.4 mg tamoxifen/kg/day. DNA methylation status was correlated to postimplantation loss in females mated with tamoxifen-treated males.

Main Outcome Measure(s)

Global sperm DNA methylation level, methylation status of Igf2-H19 ICR in sperm, postimplantation loss.

Result(s)

Tamoxifen treatment significantly reduced methylation at Igf2-H19 ICR in epididymal sperm. However, the global methylation level was not altered. A mating experiment confirmed a significant increase in postimplantation loss upon tamoxifen treatment and showed significant correlation with methylation at Igf2-H19 ICR.

Conclusion(s)

Reduced DNA methylation at Igf2-H19 ICR in rat spermatozoa upon tamoxifen treatment indicated a role of estrogen-associated signaling in the acquisition of paternal-specific imprints during spermatogenesis. In addition, association between DNA methylation and postimplantation loss suggests that errors in paternal imprints at Igf2-H19 ICR could affect embryo development.

Key Words: Tamoxifen, estrogen, DNA methylation, genomic imprinting, imprinting control region, embryo development