The expression of cell cycle proteins cyclin-E, PCNA and p27 in normal and dexamethasone induced rat placentas.

During the growth of fetus in prenatal life glucocorticoids are very important, especially in cell maturation and differentiation events. Today it is known that glucocorticoids lead to IUGR by antiproliferative effects. However, there is not any study that determined whether glucocorticoids do these effects during G1 phase. In this project, we aimed to define the effects of dexamethasone -a glucocorticoid- on G1 phase proteins such as cyclin-E, PCNA and p27 during placental development by immunohistochemical, TUNEL techniques and transmission electron microscopy. We composed two groups of pregnant rats; control (8 female) and experiment (8 female). In order to compose IUGR on rats via dexamethasone, every pregnant rat in experiment group was injected 100?g of dexamethasone acetate subcutaneously on the 13th day of pregnancy and 200?g between 14th-19th days of gestation. Between the 13th-19th days of gestation vehicle was applied to control rats. On the 20th day of gestation blood samples were taken from rats under ether anesthesia in order to measure plasma glucocorticoid levels. Then dissected placentas and fetuses were weighed. Placentas which were obtained for light microscopy were fixed in Holland fixative. Electron microscopic samples were fixed in 4% glutaraldehyde and following in 1% OsO4. Additionally rutin histological tissue preparing processes were applied to the samples. On sections obtained from prepared blocks immunostaining densities of cyclin-E, PCNA, p27 antibodies and positive stained cell frequency - HSCORE levels- were examined. TUNEL positive cells were determined. Besides ultrastructural changes were tried to be determined by electron microscope. It was determined that dexamethasone leads to statistically significant weight loss on rat placenta and fetus (p<0,005). Immunostaining density of PCNA decreased in labyrinth and junctional zone. There was a decrease in PCNA staining of trophoblast giant cells. In contrary to PCNA, p27 staining increased in all of the cells. However cyclin-E immunostaining could not carried out. Also apoptotic cells were observed by TEM. In conclusion, dexamethasone has decreased the expression of PCNA but increased p27 expression on rat placenta. Thus it creates an antiproliferative effect on cell cycle. Key words: IUGR, placenta, rat, cyclin-E, PCNA, p27, immunohistochemistry, TUNEL, TEM