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 (10-4 M), 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.