Multigenerational genetic effects of paternal cadmium exposure on ovarian granulosa cell apoptosis

To explore whether paternal cadmium (Cd) exposure causes ovarian granulosa cell (GC) apoptosis in offspring and the multigenerational genetic effects. From postnatal day 28 (PND28) until adulthood (PND56), SPF male Sprague-Dawley (SD) rats were gavaged daily with varying concentrations of CdCl2. (0, 0.5, 2, and 8 mg/kg). After treatment, the F1 generation was produced by mating with untreated female rats, and the F1 generation male rats were mated with untreated female rats to produce the F2 generation. Apoptotic bodies (electron microscopy) and significantly higher apoptotic rates (flow cytometry) were observed in both F1 and F2 ovarian GCs following paternal Cd exposure. Moreover, the mRNA (qRT-PCR) or protein (Western blotting) levels of bax, bcl2, bcl-xl, caspase 3, caspase 8, and caspase 9 were changed to varying degrees. Apoptosis-related miRNAs (qRT-PCR) and methylation modifications of apoptosis-related genes (bisulfite-sequencing PCR) in ovarian GCs were further detected. Compared with those of controls, the expression patterns of miRNAs in F1 and F2 offspring were different after paternal Cd exposure, while the average methylation level of apoptosis-related genes did not change significantly (except for individual loci). In summary, there are paternal genetic intergenerational and transgenerational effects on ovarian GC apoptosis induced by paternal Cd exposure. These genetic effects were related to the upregulation of BAX, BCL-XL, Cle-CASPASE 3, and Cle-CASPASE 9 in F1 and the upregulation of Cle-CASPASE 3 in F2 progeny. Important changes in apoptosis-related miRNAs were also observed.