| IntroductionHypoxic - ischemic encephalopathy ( HIE) is one of the common diseases in neonate, which lethality and disable rate is higher. But the pathogenesis of HIE is unclear. One of the main reasons that prenatal ischemia and asphyxia of newborn produce hypoxic - ischemic brain damage ( HIBD) is the reperfiision injury after lacking oxygen and the blood. Lack of brain blood supply improvement is favour of the neuron function recovering. Vascular endothelial growth factor ( VEGF) is a newly discoveried angiogenesic factor , which consists of up of VEGF - A VEGF - B VEGF - C VEGF - D VEGF - E and placenta growth factor (PlGF). VEGF can augment vascular endothelial cell proliferation and migration , stick reciprocally between cells, and range into the right line along with the opening cavity type structure. VEGF provides a agreeable outside cell stro-mal circumstance for the formation of new cerebral blood vessels by enhancing the penetration of vessel. In addition , VEGF can reduce the injury of neurons and the formation of brain edema. There are a lot of evidences for VEGF which plays an important role on the hypoxic - ischemic (HI) brain damage in adult. But the research on VEGF expression and distribution in normal newborn brain and HIBD is rare. The aim of the present research is to investigate the distribution of VEGF - A mRNA and protein in the brain of normal postnatal 7 - day -old rats and HIBD rats at different post - HI timepoints.MethodsChoosing the 129 healthy postnatal 7 - day - old Wistar neonate rats were employed. The HI brain injure animal model was produced by the traditional Rice's method model. Briefly, 7 - day - old Wistar rats were subjected to the right common carotid artery (RCA) ligation followed by a hypoxic (5% oxygen, 95% nitrogen) experience for 20 minutes. The rat pups were sacriced at different timepoints after HI. RCA was isdated only in the sham operated rats without experiencing hypoxic procedure, which were sacrificed at the diffrente post - operation timepoints as mentioned above. Contents are as followings:Part one; Immunohistochemical staining was performed to examine the expression of VEGF protein in the brain of normal ponstatal 7 - day - rats and the HIBD rats which undergo HI at different timepoints. The cerebral samples were paraffin - embedded and cut into 5 micron coronal sections. Antigen retrieve was performed by microwave heating in citric buffer( pH 6.0) and were visualized by SABC method with DAB as chrogen. Nuclei were conventionally counterstained with hematoxylin.Part two: With in situ hybridization (ISH) to examine the expression of VEGF - A mRNA in the brain of normal postnatal 7 days rats and the HIBD rats at different HI timepoints.Part three: Rat cerebral tissue slices were observed under microscopy at 400 fold and VEGF positive cells were stained brown - yellow and the nuclei of positive cells were blue .Part four; The data were expressed as (x + s) and statistically analyzed with Dunnett t test spss 11.5 for Windows.Results1. Expression of VEGF protein by immunohistochemistied assay For nomal postnatal 7 - day Wistar rats, the distribution of VEGF - posti-tive cells were detected at the cerebral coital layer 2, 3 and 5, leptomeninges,ependymal cells, capillary vascular endothelial cell, hippocampus and choroids plesus. The expression peaked on the postnatal 9 days, and there afterlowered, its level of VEGF protein is lower.Comparing with postnatal 7 - day Wistar rats, the distribution of VEGF protein is nearly the same. The time course of VEGF - A expression of VEGF protein showed that VEGF - A began to up - regulated at 2h post HI, and reached to the peak at 24hrs after HI and persisted to 14d.2. In situ hybridization study:For nomal postnatal 7 days Wistar rats, the distribution of VEGF mRN A was in the cerebral coital layer 2, 3 and 5, Leptomeninges, ependymal cells, Cerebral capillary vascular endothelial cell, hippocampus and choroids plesus . The level of VEGF mRNA was lower.Comparing with postnata...
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