Environmental Toxicant Induced Epigenetic Transgenerational Inheritance of Ovarian Pathology and Granulosa Cell Epigenome and Transcriptome Alterations: Ancestral Origins of PCO and POI

Previous studies have shown that exposure to a number of environmental toxicants can promote the epigenetic transgenerational inheritance of ovarian disease, including decreases in the primordial follicle pool of oocytes that are similar to what is seen in POI, and increases in ovarian cysts that are similar to what is seen in PCOS. In the current study, transgenerational changes to the epigenome of ovarian granulosa cells are characterized in F3 generation rats after ancestral vinclozolin or DDT exposures compared to controls. In purified granulosa cells from 20 day old F3 generation females 164 differentially methylated regions (DMRs) (p<1e-06) were found in the F3 generation vinclozolin lineage, and 293 DMRs (p<1e-06) in the DDT lineage, compared to controls. Pregnant F0 generation female rats were transiently exposed with vinclozolin, DDT or control vehicle (dimethylsulfoxide, DMSO) from days 8-14 of gestation. The in utero exposed offspring, F1 generation rats, were bred to produce the F2 generation, and similarly F2 generation animals were bred to produce the transgenerational F3 generation. No sibling or cousin crosses were used to avoid inbreeding artifacts. Only the F0 generation rats received the experimental treatments. Granulosa cells were harvested from the ovaries of super-ovulated F3 generation females at 20-22 days of age. Granulosa cells were isolated and analyzed so as to characterize DNA methylation.