| IntroductionNeonatal asphyxia is one of the main causes of neonatal death and injury, for it usually leads to damages of many organs (such as heart, brain, and kidney) . Because of high consumption of oxygen and large blood flow in the renal tissues, kidney is the most sensitive organ to ischemia. So the renal injury happens as a high incidence. And there are no specific clinical manifestations, so early diagnosis is very difficult. Usually, when we found it, it was already in serious condition. Thus, the study about the mechanism of renal injury after asphyxia is always an important subject for pediatricians.Neonatal asphyxia often happens in intrauterine, about 80% -90% in perinatal period. With the foundation of the model of intrauterine acute ischemia and reperfusion, the study about mechanism of renal injury has been initiatorily developed. It has been proved that inflammation is one of the important mechanisms in renal injury after asphyxia. Cyclooxygenase ( COX) is an enzyme related with inflammation, which has two subtypes in human body, COX-1 and COX-2. COX-1 is constitutive type , while COX-2 is inductive type. COX-2 expression has been reported to be low under physiological condition, but is dramatically increased by variety of stimuli, including hypoxia, lipopolysaccharide, inter-leukin-1, tumor necrosis factor, epidermal growth factor, and platelet activatingfactor. Thus, people focused on how COX-2 takes part in inflammatory reaction during ischemia/ reperfusion injury. Now, it has been proved that COX-2 expression was dramatically upregulated during ischemia/ reperfusion injury, but according to different metabolism products, COX-2 has different effect on ischemia/ reperfusion injury. So far, its effect on ischemia/reperfusion renal injury is not very clear. It has never been reported how COX-2 expression varies during ischemia/ reperfusion injury in renal tissues of fetal rat. PKC is Ca2+/phospho-lipid dependent protein kinase, which has important regulatory effect on many processes, such as transmembrane signal conduction, cell generation/ differentiation and gene expression. A great deal research indicates: During renal injury after ischemia/reperfusion, PKC is activated, which is correlative with COX-2 expression.Thus, this study regarded SD fetal rat of 21 gestational days as object and use biochemistry method to detect expression of COX protein and gene during in-trauterine ischemia and reperfusion; Use radio immunity technology to measure metabolic product of COX, including PGE2, 6-keto-PGF,aand TXB2; Use improved Takai method to detect change of activity of PKC in signal conducting system in renal tissue cells after ischemia and reperfusion and its relationship with expression of COX gene. The subject is to study effect of COX system on mechanism of intrauterine ischemia/reperfusion injury of kidney on molecular level, providing academic foundation for prevention and cure of renal injury during perinatal period.Materials and Methods1. Animal model:The pregnant 21 days SD rats were anesthetized intraabdominaly. After two-horn uterus and vessels supplying uterus and ovary were exposed, arterial clamp occluded one side of vessels. The other side was regarded as sham operation group. The measured time after ischemia was 30 min. Then clamp was taken off for reperfusion. The measured time after reperfusion was 0 min, 30 min, 2h,6h, 12h, 24h, and 30h. During PKC determination, we added such groups, ischemia for 15 min, reperfusion for 45 min and Ih.2. Sample collecting and dealing:Reaching prescribed time, uterus horn was opened rapidly and pups were removed. The pups sacrificed by decapitation. Kidneys were taken away and stored with sub mentioned methods: (J)Samples were fixed in 10% neutral formalin ;(2)Samples were frozen in nitrogen liquid; (3)Samples were stored in -70@ refrigerator; (3)Samples were stored in Eppendorf tube removed off RNAase at -SOT:.3. Methods1) HE staining: The fixed samples were studied after dehydration, inwax, cutting, and HE staini...
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