Di (2-ethylhexyl) phthalate impairs primordial follicle assembly by increasing PDE3A expression in oocytes

It is known that Di (2-ethylhexyl) phthalate (DEHP) may impact mammalian reproduction and that in females one target of the drug's action is follicle assembly. Here we revisited the phthalate's action on the ovary and from bioinformatics analyses of the transcriptome performed on newborn mouse ovaries exposed in vitro to DEHP, up-regulation of PDE3A, as one of the most important alterations caused by DEHP on early folliculogenesis, was identified. We obtained some evidence suggesting that the decrease of cAMP level in oocytes and the parallel decrease of PKA expression, consequent on the PDE3A increase, were a major cause of the reduction of follicle assembly in the DEHP-exposed ovaries. In fact, Pde3a RNAi on cultured ovaries reducing cAMP and PKA decrease counteracted the primordial follicle assembly impairment caused by the compound. Moreover, RNAi normalized the level of Kit, Nobox, Figla mRNA and GDF9, BMP15, CX37, γH2AX proteins in oocytes, and KitL transcripts in granulosa cells as well as their proliferation rate altered by DEHP exposure. Taken together, these results identify PDE3A as a new critical target of the deleterious effects of DEHP on early oogenesis in mammals and highlight cAMP-dependent pathways as major regulators of oocyte and granulosa cell activities crucial for follicle assembly. Moreover, we suggest that the level of intracellular cAMP in the oocytes may be an important determinant for their capability to repair DNA lesions caused by DNA damaging compounds including DEHP.