Aims: 

Cell volume regulation could be critical to early preimplantation mouse conceptuses, which are sensitive to changed osmolarity. Glycine has been proposed to function as an organic osmolyte, to provide intracellular osmotic support and control cell volume. The aim of this study was to investigate the glycine influence on kinetics of mouse oocyte osmotic response under hypotonic stress.

Methods: 

The keeping of the intact volume of mouse oocyte was based on freeze-drying technique. The hypotonicity was created by replacing 140mM NaCl in Dulbecco`s solution with 70mM NaCl. Oocytes were exposed for 60 minutes in the hypotonic conditions. The similar procedure was employed for Dulbecco`s containing 10 and 0,1mM glycine (Sigma, USA). Osmotic adaptation in oocyte has been studied employing the direct measurement of cell volume with laser scanning microscopy followed by three-dimensional reconstruction. A Z-stack of optical sections was obtained in a confocal microscope (Leica, Germany). 3-DR was performed in the 3ds max medium.

Results: 

Our data indicate that hypoosmotic incubation for 20 minutes resulted in the swelling peak of oocyte volume (22115 pl, these and all results below are presented as the mean and the standard deviation). After 60 minute incubation the cell volume was recovered to 17512 pl vs. 21411 pl and 20619 pl in hypotonic Dulbecco`s with 10 and 0,1mM glycine, respectively.

Conclusions: 

In the given research it was shown that glycine (10 mM) extracellularly abolishes the regulatory volume decrease (RVD) in mouse oocyte. RVD is not reestablished after the glycine content is decreased to submillimolar concentration. It allows us to suggest the glycinergic regulation of osmotic response in mouse oocyte to hypo-osmotic stress.