Paternal over- and under-nutrition programme fetal and placental development in a sex-specific manner in mice

The association between sub-optimal paternal diet and offspring well-being is becoming established. However, the underlying mechanisms are yet to be fully defined. The aim of this study was to establish the impact of over- and under-nutrition, with or without macronutrient supplementation, on male reproductive fitness and post-fertilisation development. Male C57BL/6J mice were fed either control diet (CD), isocaloric low-protein diet (LPD), high-fat/sugar 'Western' diet (WD), or LPD or WD supplemented with methyl donors and carriers (MD-LPD or MD-WD, respectively) for 8 weeks before mating with virgin C57/BL6J females. Placental tissue was collected at embryonic day (E)8.5 to assess early placental (ectoplacental cone) morphology and metabolism and E17.5 for sex-specific transcriptomic profiling. Post-mating, stud male tissues were harvested for the assessment of testicular morphology and gene expression, gut microbiota composition, and metabolic status. WD and MD-WD males displayed increased adiposity, hepatic cholesterol and free fatty acids, and gut microbiota dysbiosis when compared to CD-fed males. In the testes, WD and MD-WD perturbed the expression of genes associated with metabolism and transcription regulation. Additionally, we observed differential expression of multiple genes within the Wnt signalling pathway, central in the regulation of cellular proliferation, migration, survival, and cell fate determination during development. Despite no impact on fundamental male fertility, significant changes in ectoplacental cone metabolism, fetal growth, and placental gene expression were observed in response to specific dietary regimens. Interestingly, while CD male and female placentas displayed 301 genome-wide, sexually dimorphic genes, LPD, MD-LPD, WD, and MD-WD male and female placentas possessed only 13, 0, 14, and 15 sexually dimorphic genes, respectively. Our data show that while sub-optimal paternal diet has minimal impact on male fertility, fetal and placental development are perturbed in a sex-specific manner.