Determination of importance of Akt and ERK1/2 proteins in diabetic and intrauterine growth retarded rat placental development by immunohistochemistry and western blot technics

Placenta is affected by the changes in maternal metabolism and give response to these changes to optimise the fetal survival. Overexposure to maternal glucose and glucocorticoids causes several placental and fetal pathologies.Akt and ERK1/2 are signal transduction proteins and have important roles in placental development. However, there is scarce data about phosphorylation and immunolocalization of these proteins in diabetic and IUGR (Intrauterine Growth Retardation) placentas. Therefore in this study we aimed to determine to immunolocalization and phosphorylation of Akt and ERK1/2 by immunohistochemistry and western blot techniques.In order to compose IUGR group, pregnant females were injected with 100µg/kg dexamethasone on the 10th and 12th day of gestation subcutaneously. Enjections continuied as 200µg/kg until the day they were sacrificed. Rats that were dexamethasone injected on the 10th day of gestation were sacrificed on the day 12 of gestation. The pregnant rats, whose dexamethasone injection started on the 12th day, were sacrificed on the 14th, 16th, 18th and 20th day of their gestation. The control groups were injected same dose isotonic salt solution.The females that take part in diabetic group was injected 40mg/kg streptozotocin (STZ) intraperitonally seven days before the sacrification. After 48 hours blood glucose was measured. Rats whose blood sugar is over 200 mg/dl were included in the diabetic group. The control groups were injected same dose isotonic salt solution. Placenta samples were examined with immunohistochemical and western blot techniquesIt was observed that Akt phosphorylation was reduced significantly in IUGR (except day 14) and diabetic (except day 12) placentas. Immune reactions were significant in the junctional zone of the rat placenta and decreased in the IUGR and diabetic groups. ERK1/2 phosphorylation was increased at 12th and 16th days of gestation and decreased in the other days of gestation in IUGR groups. The results were statistically significant at 16th and 18th days. In diabetic groups ERK1/2 activation was decreased in all groups except day 12. The differance was significant at 14th and 16th days. In all groups ERK1/2 phosphorylation was reduced until the mid-gestation and increased after the 18th day of gestation. Phospho-ERK1/2 immune reactions were not only significant in the junctional zone, it was also significant in the labyrinth zone of the placentas.In conclusion, in diabetic and IUGR rats phospho-Akt and phospho-ERK1/2 expressions were reduced. It is detected that these proteins were negatively affected by over exposure to maternal hyperglycemia and dexamethasone. As a result, the small placentas in the IUGR groups and the small placentas observed on early stages and placentomegaly observed during late stages of pregnancy in the diabetic groups may be a result of disturbed PI3K-Akt and MAPK-ERK1/2 pathways.