Dipeptide forms of glycine support mouse preimplantation embryo development in vitro and provide protection against high media osmolality.

To examine potential benefits of dipeptide forms of amino acids for embryo culture by determining ability of dipeptide glycine forms to support embryo development, act as osmolytes, and reduce ammonia production. Frozen thawed 1-cell mouse embryos were cultured in media with varying osmolality with glycine and dipeptide forms of glycine and development assessed. Ammonia levels were measured in various media. Dipeptide forms of glycine, alanyl- and glycyl-glycine, can support mouse embryo development in vitro. Additionally, dipeptide glycine can act as an organic osmolyte in developing embryos, permitting blastocyst formation in high osmolality media. Interestingly, as evidenced by decreased embryo development, dipeptides are not as efficient as osmolytes as their constituent individual amino acids. Dipeptide glycine produced less ammonia than glycine. Though dipeptides can provide osmoregulation in preimplantation embryos, efficacy may be lower than individual amino acids. The mechanism by which embryos transport and utilize dipeptide amino acids remains to be identified.