Transgenerational epigenetic and transcriptomic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure in rat [Bisulfite-Seq]

In rats, direct exposure to TCDD causes myriad toxicities. Exposed rats experience hepatotoxicity, wasting syndrome and immune suppression, amongst others. “Inherited exposure”, as occurs in the F3 generation of directly exposed F0 animals, has also been shown to cause toxicity: both male and female F3 rats demonstrate an increased incidence of adult onset disease while males show increased incidence of kidney disease and an altered sperm epigenome. Here, we employ bisulfite-sequencing to explore the methylation profile of male F3 Sprague-Dawley rats bred through the paternal germ line from F0 dams exposed to a single dose of TCDD (0 or 1000 ng/kg body weight) by oral gavage. We identified multiple significant differentially methylated regions (DMRs) affecting receptor genes, including multiple olfactory receptors, as well as Egfr and Mc5r, typically with increased methylation among the TCDD-exposed lineage relative to control lineage. On gestational day 11, groups of pregnant female Sprague-Dawley rats (n=6-8) were treated with a single dose of TCDD (0 or 1000 ng/kg bodyweight) dissolved in corn oil by oral gavage. Adult male F1 progeny were mated with untreated female rats to achieve F2 generations. The above procedure was repeated to further achieve F3 generations. At the end of the examination period, rats were euthanized by carbon dioxide exposure and subjected to tissue sampling. Testicular tissue was shipped on dry ice to the analytical laboratory for processing.