Glycine protects preimplantation mouse conceptuses from a detrimental effect on development of the inorganic ions in oviductal fluid

Abstract

Two-cell mouse conceptuses were cultured in media that contained various concentrations of inorganic ions and amino acids. Substrates of the amino acid transport system Gly were detrimental to development at slightly hyposmotic concentrations of other ions. In contrast, these amino acids increased the frequency at which two-cell conceptuses developed into blastocysts at total ion concentrations of 355 to 405 mM. Data reported elsewhere is consistent with the possibility that the total ion concentration in oviductal fluid exceeds 360 mM, whereas the concentration of glycine in this fluid may be on the order of 10 mM. Therefore, a high ion concentration and glycine may counteract the potentially harmful effects of each other in situ. Like some marine organisms, preimplantation mouse conceptuses may use glycine as an intracellular osmolite because accumulation of inorganic ions could perturb the activities of some enzymes.

Nonessential amino acids and glutamine decrease the time of the first three cleavage divisions and increase compaction of mouse zygotes in vitro

“…Effects of nonessential amino acids and glutamine on the cleavage-stage embryo include protection against osmotic/ionic stress (17,18), regulators of metabolic function (19), and regulators of intracellular pH (Gardner and Edwards, unpublished observations).…”

Cell volume regulation in mammalian oocytes and preimplantation embryos

“…Glutamine, glycine, proline, betaine (N,N,Ntrimethylglycine), or b-alanine each protects mouse embryo development past the 2-cells stage at higher osmolarities (Van Winkle et al, 1990b;Lawitts and Biggers, 1992;Biggers et al, 1993;Dawson and Baltz, 1997). Such observations led Biggers and Van Winkle to independently propose that preimplantation embryos require organic osmolytes for cell volume regulation (Van Winkle et al, 1990b;Lawitts and Biggers, 1992). The empirical findings that preimplantation embryo development could be restored in vitro if the osmolarity of the medium was lowered, or if any of several organic compounds were added to the medium, was consistent with the hypothesis that preimplantation embryos maintain volume using the same type of Figure 1.…”

“…Among the putative organic osmolytes in embryos, glycine showed an excellent ability to protect embryos against increased osmolarity (Van Winkle et al, 1990b;Hadi et al, 2005). One-cell mouse embryos will develop through the 2-cell block in media that are up to about 70 mOsM more hypertonic when glycine is present than when it is absent (Hadi et al, 2005).…”

Concentration and composition of free amino acids and osmolalities of porcine oviductal and uterine fluid and their effects on development of porcine IVF embryos

“…The osmolality of mouse oviductal fluid has been calculated to be above 340 mOsM (Borland et al 1977;Van Winkle et al 1990). A similarly high osmolality is predicated for human fallopian tube fluid by electron probe measurements (Borland et al 1988).…”

“…It appears that the reason the embryo can survive the high physiological osmolality in vivo is that there are amino acids serving as "organic osmolytes", such as glycine (Dawson & Baltz 1997) glutamine (Biggers et al 1993) and β-alanine (Hammer & Baltz 2003), in the female reproductive tract. If any of a number of "organic osmolytes" is included in the culture medium, the embryo will develop at significantly higher osmolalities than in the absence of such compounds in vitro (Van Winkle et al 1990;Dawson & Baltz 1997). These osmoprotectants can be imported into the cell to provide intracellular osmotic support and maintain cell volume against exposure to high osmolality (Hammer & Baltz 2003).…”