Tauroursodeoxycholic Acid Enhances the Pre‐Implantation Embryo Development by Reducing Apoptosis in Pigs

Apoptosis is an important determinant of the normal development of pre‐implantation embryos in vitro. Recently, endoplasmic reticulum (ER) stress‐mediated apoptosis has been extensively investigated in a wide variety of diseases. Efficient functioning of the ER is essential for most cellular activities and survival. Tauroursodeoxycholic acid (TUDCA), an endogenous bile acid, has been reported to attenuate ER stress‐mediated cell death by interrupting the classic pathways of apoptosis. Therefore, in this study, the anti‐apoptotic effect of TUDCA on ER stress‐induced apoptosis was examined in pre‐implantation pig embryos. Also, tunicamycin was used to investigate the effects of ER stress on pig embryo development. After in vitro maturation and fertilization, presumptive pig embryos were cultured in NCSU‐23 medium supplemented with TUDCA or TM for 6 days at 39°C, 5% CO2 in air. All data were analysed using one‐way anova and Duncan’s multiple range test in the statistical analysis system (SAS). In addition, we also determined the optimal TM and TUDCA concentrations. Samples were treated with TM at concentrations of 0, 1, 2 or 5 μm and with TUDCA at concentrations of 0, 100, 200 or 300 μm. When TM was used during in vitro culture, only 8.2% (8/97) of the embryos developed to the blastocyst stage when the treatment concentration was 1 μm compared with 27.4% (28/102) of the embryos in the control group (p