2-Methoxystypandrone improves in vitro-produced bovine embryo quality through inhibition of IKBKB

- The main difference between the in vivo and in vitro environments is the O2 concentration.
- Higher O2 concentration under the in vitro environment leading to the production of high concentrations of ROS.
- The molecular mechanisms that induce oxidative stress have shed light on the development of novel antioxidant therapies.
- Treatment of oocytes with a potential anti-oxidant, 2-MS improved in vitro developmental competence of bovine embryos.
- Addition of 2-MS to IVM medium counterbalanced the ROS, reduced apoptosis, and improved the blastocyst development.

2-Methoxystypandrone (2-MS), a naphthoquinone from Polygonum cuspidatum, has been reported to exhibit antioxidant activities. However, its pharmacological properties have not been fully studied in vitro culture system of oocytes and embryos development. In this study, we examined the effects of 2-MS on bovine blastocyst developmental competency during preimplantation using TUNEL assay, qRT-PCR and immunocytochemistry. Oocytes were treated with 1 μM 2-MS during maturation, followed by in vitro fertilized and the zygotes were cultured. We observed that blastocyst development was significantly higher in the 2-MS treated oocytes (45.29%) compared to control groups (32.21%). We also found that 2-MS treatment significantly increased total cell number and decreased the apoptotic cells in Day-8 blastocyst. Finally, we examined the signal pathway affecting the embryo development after the 2-MS treatment. We detected a significant decrease in the mRNA levels of NFKB1, IKBKB, COX2, NOS2, BAX, CASP3, and JAK2 after 2-MS treatment, however, the mRNA level of the anti-apoptotic gene BCL2 was significantly higher than that in the control. Moreover, protein expression levels of NFKB1, IKBKB, and COX2, and 8-oxoG DNA lesion decreased significantly in the 2-MS treatment group, compared to the control. In summary, our findings suggested that treatment of oocytes with a potential anti-oxidant, 2-MS during IVM improved in vitro developmental competence of bovine embryos.