Multiple generation distinct toxicant exposures and epigenetic transgenerational inheritance of sex‑specific outcross impacts on sperm epigenetics and obesity pathology.

Environmental factors can influence the epigenetic inheritance of pathology across generations. Prior studies found various toxicants increased pathology in their descendants through epigenetic transgenerational inheritance. Previously, three generations of rats were exposed separately to vinclozolin (F0 generation), a jet fuel hydrocarbon mixture (F1 generation), and dichlorodiphenyltrichloroethane (DDT) (F2 generation), producing a transgenerational F5 generation. The current study extends this study by breeding this transgenerational F5 generation with wild-type rats to create maternal and paternal outcross lineages, labeled MOC and POC, respectively. In the current study, we examined the differential DNA methylated regions (DMRs) in the outcross F6 generation offspring to detect potential parent-of-origin lineage‑specific inheritance impacts. When comparing both outcross MOC and POC lineages of the F6 generation to a control outcross F3 generation from the same lineage, with no toxicant exposure, a higher number of DMRs were observed in the F6 generation lineages. Additionally, while there was some common overlap between the two MOC and POC outcross generations, only the F6 POC generation had overlaps with the F5 multigenerational exposure lineage generation of the previous study, which was also a paternal outcross. Since previous pathology analysis has been extensive, limited pathology (e.g. obesity) was performed in the current study to primarily confirm the transgenerational pathology in the F6 generation outcross lineages. Comparisons between the control same lineage F3 generation and both of the outcross F6 generations identified outcross‑specific results, suggesting sex-specific epigenetic inheritance after ancestral toxicant exposure. Therefore, both the oocyte and sperm facilitate epigenetic transgenerational inheritance.