Diisononyl phthalate (DINP), a mixture of chemical compounds composed of diverse isononyl esters of phthalic acid, is commonly applied as a plasticizer to substitute for di (2-ethylhexyl) phthalate (DEHP). It has been demonstrated that DINP exposure impairs the functions of kidney and liver in animals. However, the effects and potential mechanisms of DINP exposure on the female reproduction, especially the oocyte quality are still poorly understood. Here, we discovered that DINP exposure weakened the porcine oocyte meiotic competency (78.9% vs 53.6%, P < 0.001) and fertilization ability (78.5% vs 34.1%, P < 0.0001) during in vitro maturation. Specifically, DINP exposure induced the persistent spindle assembly checkpoint (SAC) activation caused by the disorganized spindle/chromosome apparatus (spindle: 20.0% vs 83.3%, P < 0.001; chromosome: 20.0% vs 80.0%, P < 0.01) to arrest meiotic progression of oocytes at metaphase I stage. In addition, DINP exposure disturbed the dynamics of sperm binding (146.7 vs 58.6, P < 0.0001) and fusion proteins (19.5 vs 11.6, P < 0.0001) in oocytes to compromise their fertilization ability. In particular, transcriptome data uncovered that the action mechanism of DINP on the oocyte maturation was associated with oxidative phosphorylation, apoptosis and autophagy pathways. Lastly, we validated that DINP exposure resulted in the mitochondrial dysfunction (27.2 vs 19.8, P < 0.0001) and elevated levels of reactive oxygen species (ROS; 8.9 vs 19.9, P < 0.0001) to trigger the occurrence of apoptosis (7.2 vs 13.1, P < 0.0001) and protective autophagy (68.6 vs 139.3, P < 0.01). Altogether, our findings not only testify that DINP has a potentially adverse impact on the mammalian oocyte quality, but also provide a scientific reference regarding how environment pollutants act on the female germ cell development.
Keywords: Apoptosis; Autophagy; Diisononyl phthalate; Fertilization ability; Oocyte quality.
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