Oxidative stress in the testis induced by tamoxifen and its effects on early embryo development in isogenic mice

Oxidative stress induced by tamoxifen (TAM) in male testis and its effects on fertility and early embryo development were investigated. TAM was orally administered for 4 weeks repeatedly to two isogenic male mice strains, inbred strain of C57BL/6J (B6) mice and hybrid strain of C57BL/6J x CBA F1 (B6CBAF1) mice. Oxidative stress in mice testis was measured based on the level of lipid peroxidation (LPO). The LPO level was significantly increased in inbred strain of B6 mice (p < 0.05), but not hybrid strain of B6CBAF1 mice. Paternal exposure to TAM led to a significant decrease in the fertilization rate in B6 mice (p < 0.05), but not their B6CBAF1 counterparts. Interestingly, TAM had no impact on the cell number and apoptosis status in blastocysts. These results indicate that susceptibility to TAM-induced oxidative stress in the testis differs between isogenic mice strains, and genetic variations play an important role in promoting differential degrees of toxic response.