Therapy to teratology: chronic paternal antioxidant supplementation alters offspring placental architecture and craniofacial morphogenesis in a mouse model

Oxidative stress is an important regulator of the mammalian epigenome, with redox imbalances triggering stress-responsive epigenetic modifications linked to various diseases. Accordingly, antioxidant therapies are commonly used to reduce oxidative damage and are widely employed in cases of male infertility. Interestingly, in ostensibly healthy males, recent research suggests that antioxidants may have a negative influence on sperm DNA methylation, indicating a potential epigenetic liability. However, whether male antioxidant treatment can induce paternal effects on offspring growth and development remains untested. Here, we employed micro-CT imaging and geometric morphometrics to determine whether chronic antioxidant supplementation in healthy male mice affects placental growth and craniofacial development in their offspring. Adult C57BL/6J male mice were given a six-week preconception regimen of N-acetyl-L-cysteine and selenium, then paired with treatment-naïve females. Although we observed sex-specific changes in the decidua and junctional zone, we did not detect changes in placental weight and efficiency. In contrast, we observed significant changes in facial shape in both male and female offspring, with female offspring exhibiting significant reductions in eye spacing and head area. These changes occurred without any macro changes in paternal metabolic health, indicating that alterations in developmental programming may occur independent of changes in overall health. Our findings highlight the need for caution in the indiscriminate use of antioxidants, showing that supplementation in healthy males is not harmless and that perturbing the paternal redox balance may alter developmental programming and induce teratogenic outcomes.