Introduction: Preventing spontaneous maturation in vitro by adding cAMP regulators is thought to maintain the communication between oocyte and cumulus cells via gap junction communication (GJC), hence promoting developmental competence. We aimed to assess the integrity of gap junction maintenance in cumulus oocyte complexes (COCs) after pre-maturation with IBMX and Forskolin (FSK) and the influence on bovine embryo development.
Materials and methods: Immature COCs were cultured in VitroMat (IVF Vet Solutions)+4 mg/ml FAFBSA and divided into the following treatments groups: i) IBMX+FSK: pre-treatment with IBMX (500 μM; SigmaAldrich) and FSK(100 μM; SigmaAldrich) for 2 h (pre-IVM) following 22 h maturation with rhFSH (0.1 IU/ml) and ii) spontaneous IVM: rhFSH (0.1 IU/ml) for 24 h. Oocytes were inseminated and zygotes were cultured for 5 days in VitroCleave (IVF Vet Solutions) and transferred into VitroBlast (IVF Vet Solutions), untilblastocystassessment (days 7and 8). Lucifer yellow (3% in 5 mM lithium chloride) dye was microinjected into the ooplasm to assess GJC.COC GJC was scored as open (+2), partially open (+1), and closed (0) communication.
Results and Discussion: Embryo development did not differ between groups probably due to the short period of maturation after pre-IVM (22 h). Functional GJC were 1.6-fold increased in IBMX+FSK group. In summary, pre-treatment with IBMX and FSK improved communication between oocyte and cumulus, but 22 h of maturation seems insufficient to improve embryo development.
02 Sep 2014 - 04 Sep 2014