Generational stability of environmentally induced epigenetic transgenerational inheritance of adult-onset disease over ten mammalian generations

In traditional models of Drosophila flies and C. Elegans worms epigenetic transgenerational inheritance has persisted for hundreds of generations. Mammalian studies, however, have primarily investigated up to three or four generations. Environmental exposures to toxicants or other stressors have been linked to epigenetic transgenerational inheritance. Changes within the epigenome have the potential to alter gene expression and genetic processes, as well as potentially alter phenotypes and evolution in all organisms. In this study, an outcrossed mammalian colony of outbred rats was bred for ten successive generations and assessed for epigenetic alterations and incidence of pathological abnormalities. The hypothesis tested was that epigenetic transgenerational inheritance of disease would be maintained for ten generations. Sperm from male rats were analyzed for DNA methylation and pathology abnormalities in the outcross female and male lineage rats in successive generations. Effects on male sperm were observed in differential DNA methylated regions (DMRs) in both lineages. A dramatic increase in apoptosis of male spermatogenic cells in the testes for both male and female lineages was observed. Pathology of different tissue types was assessed by artificial intelligence (AI)-based technologies using deep learning histology protocols developed. Observations showed a dramatic increase in disease incidence within the tenth generation (F13) compared to the control lineage for kidney, ovary, prostate, and testis for both outcross lineages. As previously observed, no gross pathologies were observed in other organs. Observations demonstrate long-term impact of ancestral exposures on epigenetic modifications and health outcomes across multiple generations are stable for ten generations in mammals.