Preimplantation embryotoxicity after mouse embryo exposition to reactive oxygen species

Exposure of either gametes or embryos to conditions and/or factors that generate oxidative stress has been associated with impaired early embryogenesis. The effects of reactive oxygen species (ROS) on mouse preimplantation development, depending of the ROS-concentration and time of exposition, were studied. Two-cell embryos were incubated with 5, 10, 25 and 50 μM of hydrogen peroxide (H2O2) for 30 and 60 minutes of exposition and allowed to develop for 72 h to study the quality of development. The incubation with 50 μM H2O2 for 30 or 60 minutes, strongly inhibited the 2-cell embryo development as compared to the control (p<0.001). Twenty-five μM H2O2 produced inhibition of blastocyst formation (p<0.001) and 10 μM H2O2 significantly decreased the percentages of expanded and hatched blastocysts, which resulted morphologically altered (p<0.05 and p<0.01, respectively). The higher H2O2 concentrations were able to elicit necrotic morphology in the 2-cell arrested embryos, while 10 μM H2O 2 induced moderate damage with the arrested embryos partially fragmented. In conclusion, important causes for defective preimplantation development and for early embryo losses may be due to oxidative stress because early mouse embryos exposed to ROS for short times arrested at the first cellular cycle (2-cell) and/or impaired embryo differentiation and morphogenesis, being these effects ROS-concentration-dependent.Fil:Cebral, E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Regulatory role of angiotensin II on progesterone production by cultured human granulosa cells. Expression of angiotensin II type-2 receptor

The role of angiotensin II (Angll) in ovarian steroidogenesis is not clearly understood. In order to study its action on progesterone synthesis and to determine which receptor subtype is involved, granulosa cells obtained from women undergoing in-vitro fertilization were cultured for2 or4 days and then incubated in the presence of Angll (10-7 M) with or without human chorionic gonadotrophin (HCG,10 IU/ml) for3 or18 h. In cells cultured for2 days, incubation with Angll decreased progesterone secretion by36%, and inhibited activity of3β-hydroxysteroid dehydrogenase (3β-HSD) by87% (P <0.05), although its expression was not significantly reduced. However, in cells cultured for 4 days, progesterone production was enhanced by incubation with Angll (38%), and no change was observed in 3β-HSD expression. Both inhibitory and stimulatory effects were dose-dependent. Progesterone secretion was increased (93%) by incubation with HCG of cells cultured for4, but not for2 days, and no potentiation w