Niacin alleviates dibutyl phthalate-induced impairment of porcine oocyte quality.

Dibutyl phthalate (DBP) is a common plasticizer widely used in industrial and medical applications. DBP can cause damage to the female reproductive system due to its estrogen-like effects. However, the mechanisms of DBP toxicity on oocytes and the potential for effective intervention have not been investigated. In this study, porcine oocytes were exposed to different concentrations of DBP, and 600 μM DBP exposure in vitro significantly affected cumulus cell expansion, polar body expulsion, and cytoskeleton formation. Further experiments showed that DBP exposure affects embryonic developmental competence. In addition, DBP exposure led to mitochondrial dysfunction, which was reflected by a decrease in mitochondrial membrane potential, scattered mitochondrial distribution, and decreased ATP production. The results also showed that DBP exposure increased ROS levels, decreased GSH levels and antioxidant gene expression levels, thereby inducing oxidative stress. Moreover, DBP exposure significantly elevated LC3 level and promoted apoptosis in porcine oocytes. In contrast, co-treatment with 600 μM niacin (NA, also known as vitamin B3, an essential antioxidant), selected from different protective concentrations, decreased oxidative stress and LC3 level, thus attenuating the adverse effects of DBP. Moreover, the inhibition of autophagy by 3-methyladenine (3-MA, a specific autophagy inhibitor) also abolished DBP-induced apoptosis. In conclusion, the results suggest that DBP impairs mitochondrial function, increases oxidative stress, LC3 level and apoptosis in porcine oocytes, and that NA effectively attenuates these effects. These results demonstrate the toxic effects of DBP on oocytes and provide an effective therapeutic strategy.