Supplementation of cGMP during in vitro culture enhances the developmental competence of sheep embryos

This study aims to investigate the effect of cyclic guanosine-3’,5’-monophosphate (cGMP) on ovine embryo development, thereby providing new strategies to improve the efficiency of in vitro embryo production (IVP). Following in vitro maturation (IVM) and in vitro fertilization (IVF) of ovine oocytes derived from abattoir, the presumptive zygotes were treated with different concentrations of cGMP. In order to explore the effect of cGMP on the developmental competence of embryos derived from ovum pick-up (OPU)-oocytes, the presumptive zygotes were cultured with cGMP after IVF. The cleavage rate and blastocyst rate were recorded at 24 h and on day 7 after IVF. On day 7, the blastocysts derived from slaughterhouse oocytes were collected to assess mRNA expression of development- and apoptosis-related genes. Additionally, the blastocyst quality, antioxidant capacity, mitochondrial function and lipid metabolism of blastocysts were evaluated. The results showed that cGMP significantly increased cleavage rate and blastocyst rate, with an increase in total cell number and ICM. The expression of pluripotency-related gene ( NANOG ) was upregulated and apoptosis-related gene ( CASPASE3 ) was downregulated after cGMP treatment. The administration of cGMP resulted in decreased lipid content and fatty acid levels, along with a significant decrease in reactive oxygen species (ROS) and lipid peroxidation. Additionally, mitochondrial membrane potential and ATP levels were elevated after cGMP treatment. Furthermore, cGMP also increased blastocyst rate of IVF embryos from ovine oocytes collected via OPU. These results demonstrate that cGMP can improve embryo developmental competence by enhancing lipid metabolism and reducing oxidative stress.