Effects of the addition of insulin-transferrin-selenium (ITS) and/or metformin to the in vitro maturation of porcine oocytes on cytoplasmic maturation and embryo development

Context. One of the main problems of porcine in vitro maturation (IVM) is incomplete cytoplasmatic maturation. Nuclear and cytoplasmic maturation will determine the future success of fertilisation and embryo development. Insulin-transferrin-selenium (ITS) has insulin-like and antioxidant effects, and metformin (M) is an insulin-sensitiser and antioxidant drug. Aims. To assess the effects of adding ITS and/or M in porcine IVM media on cytoplasmic maturation and early embryo development. Methods. Cumulus-oocyte complexes (COC) were IVM with M (10-4M), ITS (0.1% v/v), M + ITS or no adding (Control). Key results. ITS increased glucose consumption compared to Control and M (P < 0.01), and M + ITS did not differ from ITS or Control. Redox balance: M, ITS and M + ITS increased glutathione (P < 0.01) and decreased lipid peroxidation (P < 0.005). The viability of cumulus cells by flow cytometry increased with M (P < 0.005) and decreased with ITS (P < 0.001); M + ITS did not differ from Control. After IVF, M increased penetration and decreased male pronucleus (P < 0.05). Embryo development: cleavage increased with M (P < 0.05), and blastocysts increased with ITS and M + ITS (P < 0.05). The number of blastocyst cells increased with ITS (P < 0.05). Conclusions. Adding ITS and M + ITS to porcine IVM media benefits embryo development to blastocysts, but ITS alone has better effects than M + ITS. Implications. ITS is an excellent tool to improve IVM and embryo development after IVF in pigs.