role of L-arginine in control of apoptosis in preimplantation mouse embryos cultured in high glucose media

Maternal hyperglycemia causes delay in early stages of embryonic growth and development, higher incidence of congenital malformations and spontaneous miscarriage compared with those of non-diabetic conditions. High glucosis tratogenicity seems to be related to reduction of Nitric Oxide production [NO] in hyperglycemic condition. In order to test this hypothesis, 2-cell stage embryos of normal mice were cultured with high concentration of glucose [30mM] and different concentrations of L-arginine [5,10,20 mM] or L-NAME, an NO syntase [NOS] inhibitor. In the end of culture, blastocysts were stained by by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling [TUNEL] technique and apoptotic cells were detected by using a Fluorescence microscope. Finally the amount of nitrite in the cultured media was assayed by Griess method. The results indicated that high glucose reduces Nitric Oxide production by preimplantation embryos and increases apoptosis of embryonic cells, but 5-20mM of L-arginine significantly increases Nitric Oxide production and decreases apoptosis. On the contrary L-NAME significantly inhibits the development of pre-implantation embryos. In conclusion, this study indicated that reduced nitric oxide production in high glucosis condition is a main factor for embryonic damage, and supplementation of high glucose media with L-arginine has an important role in prevention of high glucosis embryotoxicity