A short exposure to polychlorinated biphenyls deregulates cellular autophagy in mammalian blastocyst in vitro

Polychlorinated biphenyls (PCBs) are common environmental contaminants that represent an important risk factor of reproductive disorders in chronically exposed human populations. However, it is not known whether a short accidental exposure of embryos to PCBs before implantation might influence their further development and whether the effect might be reversible. To this aim, in vitro-matured sheep blastocysts were incubated with 2 or 4 g/ml Aroclor 1254 (A1254), a mixture of 60 PCB congeners for 48h after which blastocyst proliferation and ability for outgrowth in vitro were assessed. Blastocysts exposed to A1254 showed: (i) reduced proliferation and cell number (particularly in the inner cell mass compartment); (ii) accumulation of vacuoles and lipid droplets, diffused mitochondrial damage and up-regulation of autophagy markers (ATG6 and LC3), all signs indicative of deregulated autophagy, and (iii) massive cell death. Although exposed embryos resumed growth following A1254 removal, their subsequent development remained severely perturbed. These findings indicate that short exposure of blastocysts to PCBs leads to its damage characterized by deregulated autophagy and subsequent cell death.