Vinclozolin and MEHP disrupt piRNA and miRNA expression and increase apoptosis in embryonic mouse ovaries

Primordial germ cells are the embryonic precursors to sperm and egg cells, and their development is regulated by multiple molecular pathways, including small non-coding RNAs. Environmental toxicants such as vinclozolin and mono-(2-ethylhexyl) phthalate (MEHP) can alter the expression of these regulatory RNAs, affecting both the exposed individuals and their descendants. To investigate these effects, we exposed pregnant mice to vinclozolin or MEHP and collected embryonic ovaries from their offspring across three generations. Small RNA sequencing identified 3,498 microRNA and 12,078 piwi-interacting RNA sequences. Exposure led to the deregulation of 34 microRNAs and 668 piwi-interacting RNAs, with changes persisting unexposed descendants of two generations. When both parents were exposed, dysregulation was more pronounced than with maternal exposure alone, an average increase of 4.06-fold for piRNAs and 5.5-fold for microRNAs. Quantitative PCR confirmed changes in selected microRNAs. Immunofluorescence analysis showed an increase in apoptotic cells in embryonic ovaries, particularly within primordial germ cells. The number of dying cells increased 2.44-fold after vinclozolin exposure and 1.75-fold after MEHP exposure. These findings contributed to the knowledge that in utero exposure to vinclozolin or MEHP disrupts small RNA expression and increases apoptosis in the developing ovary, with effects that persist across multiple generations.