Tauroursodeoxycholic Acid Enhances the Quality of Postovulatory Aged Oocytes by Alleviating Oxidative Stress, Apoptosis, and Endoplasmic Reticulum Stress in Pigs.

One of the major factors causing reduced developmental capacity of aged porcine oocytes is the induction of oxidative stress during oocyte aging. Tauroursodeoxycholic acid (TUDCA) supports cellular function by acting as an antioxidant and free radical scavenger. The aim of this study is to evaluate whether exogenous supplementation of TUDCA to the porcine in vitro maturation system can ameliorate the compromised quality of aged oocytes by mitigating free radical production. We found that TUDCA was able to effectively maintain normal oocyte morphology, cortical granule distribution, and spindle structure during postovulatory aging. Additionally, the blastocyst rate and total cell number in blastocysts were significantly increased in aged porcine oocytes treated with TUDCA. Importantly, aged porcine oocytes treated with TUDCA reduced ROS levels, increased the expression levels of GSH and SOD1 genes, and improved the mitochondrial membrane potential ratio. Further study demonstrated that TUDCA significantly alleviated apoptosis in aged porcine oocytes, confirmed by the decreased Caspase 3 levels and ratio of BAX to BCL2. Interestingly, TUDCA could effectively alleviate the phenomenon of endoplasmic reticulum stress triggered during the oocyte aging process. Taking these findings together, our study demonstrates that TUDCA supplementation beneficially affects the quality of aged porcine oocytes by suppressing oxidative stress, apoptosis, and endoplasmic reticulum stress.