Reduction of Mitochondrial Function by FCCP During Mouse Cleavage Stage Embryo Culture Reduces Birth Weight and Impairs the Metabolic Health of Offspring.

The periconceptual environment represents a critical window for programming fetal growth trajectories and susceptibility to disease; however, the underlying mechanism responsible for programming remains elusive. This study demonstrates a causal link between reduction of precompaction embryonic mitochondrial function and perturbed offspring growth trajectories and subsequent metabolic dysfunction. Incubation of embryos with carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), which uncouples mitochondrial oxidative phosphorylation, significantly reduced mitochondrial membrane potential and ATP production in 8-cell embryos and the number of inner cell mass cells within blastocysts; however, blastocyst development was unchanged. This perturbed embryonic mitochondrial function was concomitant with reduced birth weight in female offspring following embryo transfer, which persisted until weaning. FCCP-treated females also exhibited increased adiposity at 4 wk, increased adiposity gain between 4 and 14 wk, glucose intolerance at 8 wk, and insulin resistance at 14 wk. Although FCCP-treated males also exhibited reduced glucose tolerance, but their insulin sensitivity and adiposity gain between 4 and 14 wk was unchanged. To our knowledge, this is one of the first studies to demonstrate that reducing mitochondrial function and, thus, decreasing ATP output in the precompacting embryo can influence offspring phenotype. This is of great significance as a large proportion of patients requiring assisted reproductive technologies are of advanced maternal age or have a high body mass index, both of which have been independently linked with perturbed early embryonic mitochondrial function.

Oxidative stress in mouse sperm impairs embryo development, fetal growth and alters adiposity and glucose regulation in female offspring.

Paternal health cues are able to program the health of the next generation however the mechanism for this transmission is unknown. Reactive oxygen species (ROS) are increased in many paternal pathologies, some of which program offspring health, and are known to induce DNA damage and alter the methylation pattern of chromatin. We therefore investigated whether a chemically induced increase of ROS in sperm impairs embryo, pregnancy and offspring health. Mouse sperm was exposed to 1500 µM of hydrogen peroxide (H2O2), which induced oxidative damage, however did not affect sperm motility or the ability to bind and fertilize an oocyte. Sperm treated with H2O2 delayed on-time development of subsequent embryos, decreased the ratio of inner cell mass cells (ICM) in the resulting blastocyst and reduced implantation rates. Crown-rump length at day 18 of gestation was also reduced in offspring produced by H2O2 treated sperm. Female offspring from H2O2 treated sperm were smaller, became glucose intolerant and accumulated increased levels of adipose tissue compared to control female offspring. Interestingly male offspring phenotype was less severe with increases in fat depots only seen at 4 weeks of age, which was restored to that of control offspring later in life, demonstrating sex-specific impacts on offspring. This study implicates elevated sperm ROS concentrations, which are common to many paternal health pathologies, as a mediator of programming offspring for metabolic syndrome and obesity.