Taurine Acts as an Osmolyte in Human and Mouse Oocytes and Embryos

Abstract

Taurine transport in mouse embryos has been shown to be osmotically regulated. We studied release of taurine from mouse and human oocytes and embryos when exposed to conditions that created osmotic imbalances, either by incubation in anisosmotic media or by inhibition of Na(+)-K(+)-ATPase with ouabain. Furthermore, we studied the effect of cleavage in mouse embryos on release of taurine. When human oocytes that remained unfertilized after in vitro fertilization, human embryos (2- to 8-cell), and mouse 2-cell embryos were loaded with [3H]taurine and subsequently incubated for 4 h in hyposmotic media (200 and 240 mOsm/kg), they showed significantly lower radioactivity as compared to those incubated in media of 280, 320, and 360 mOsm/kg and higher radioactivity of the incubation media. Incubation with 1.5 mM ouabain resulted in decreased radioactivity of mouse embryos and increased radioactivity of incubation medium. When mouse 2-cell embryos were cultured for 24 h after loading with [3H]taurine, radioactivity of embryos that cleaved to the 4-cell stage was significantly lower than that of uncleaved embryos. This finding is in accordance with the theory that cell division induces cell volume-regulatory mechanisms. In contrast, when 1-cell embryos were cultured for 24 h, radioactivity of embryos developing to the 2-cell stage was significantly higher than that of uncleaved embryos. These data support the theory that taurine is released by embryos when they have to adjust their cell volume because of either extracellularly induced or intracellularly occurring osmotic imbalances. When culture is performed without taurine, the resultant taurine depletion of embryos may be disadvantageous, either because the embryo has to rely more on its inorganic osmolytes for volume regulation or because taurine can no longer provide its other protective functions.

Coenzyme Q10 content in follicular fluid and its relationship with oocyte fertilization and embryo grading

“…As reported in sperimental in vitro cultures of myocardial cells, the CoQ10 stimulated the formation of ATP [19] that in reproductive biology could accelerate formation of the blastocoels cavity and consequently the hatching process [20,21], second the presence of CoQ10 may correct ionic imbalance that exists in embryos cultures [21].…”

Functional Expression of Taurine Transporter and its Up-Regulation in Developing Neurons from Mouse Cerebral Cortex

“…At present, it is unknown that TAUT expression is age-dependently elevated. Although taurine is not used for protein synthesis, it is normally present in high concentrations in mouse eggs and oviductal and uterine fluid, and acts as an osmolyte in mouse oocytes and embryos (30) and promotes embryo development in a variety of species, including mouse (31) and humans (32). Therefore, the taurine transport into neurons might be correlated to neuronal development and/or construction of neural network.…”

Coenzyme Q10 in Submicron-Sized Dispersion Improves Development, Hatching, Cell Proliferation, and Adenosine Triphosphate Content of In Vitro-Produced Bovine Embryos1

“…Hatching of expanded blastocysts was also stimulated by the presence of 30 M CoQ 10 , which could be due to several mechanisms: 1) CoQ 10 and electron transport automatically activate the proton antiport [9], which is important for ion changes and fluid distribution in the blastocyst; 2) by stimulating cell proliferation and increasing the ATP content, CoQ 10 could accelerate formation of the blastocoel cavity and consequently the hatching process, which in bovine embryos depends on the physical force of blastocoel expansion and repeated collapsing and re-expansion [40]; and 3) an ionic imbalance that exists in embryos cultured in conventional media [41] could be corrected by CoQ 10 .…”