Role of curcumin and thymoquinone on in vitro bovine embryo production

Bovine in vitro culture and embryo transfer research continues rapidly in the world. Although antioxidant substances have been found to protect cells and inhibit DNA fragmentation, their positive effects on embryo production are still under investigation. Curcumin and thymoquinone are known to have antiproliferative, anticarcinogenic, anti-inflammatory, cell regenerative, DNA fragmentation inhibitory, apoptosis suppressive, antiproliferative, anticarcinogenic and anti-inflammatory effects. In this doctoral thesis project, it was aimed to determine the effects of curcumin and thymoquinone on bovine embryo production in vitro. In the study, oocytes were obtained from ovaries collected from slaughterhouse. For in vitro maturation, oocytes were matured in in vitro maturation (IVM-TCM199) medium with or without 5 and 10 µM curcumin and 10 and 20 µM thymoquinone. Embryos fertilized in in vitro fertilization (IVF-TALP) medium and presumed to be zygotes were transferred to SOF and CR1aa medium and embryo development was recorded. Embryos that reached the blastocyst stage were frozen and their viability was checked after thawing. Oocytes separated for maturation assays were evaluated for intracellular oxidation, caspase-3 and connexin 43 assays. At the end of all experimental studies, there was no difference in total embryo ratios between the groups in SOF and CR1 media, while cleavage rate in CR1 media was found to be statistically significant in favor of the T10 group. While there was no difference between the groups in the intracellular oxidation analysis, it was determined that the caspase-3 level decreased statistically significantly in favor of K5, K10, T10 and T20 compared to the control group in the active caspase-3 test (p<0.05). In connexin 43 analysis, while T10 group gave parallel results with the control group, K5 was statistically significant at p<0.05 level, K10 and T20 were statistically significant at p<0.001 compared to the control group. When the viability of the embryos cultured after thawing was evaluated, a statistical difference was found in the SOF medium, to the detriment of the K5 group. In conclusion, although curcumin and thymoquinone are thought to support the oocyte in in vitro maturation as antioxidants, the lack of difference between the groups in embryo development at the end of the 8th day was attributed to the short-term exposure of the oocyte to antioxidants and it was concluded that these substances should be added to in vitro culture and analyzes should be performed.