Expression Of NADH Dehydrogenase Gene In Placentas Of Patients With Pregnancy-induced Hypertension

Pregnancy-induced hypertension (PIH) is a pregnancy specific disease that characterize as hypertension, proteinuria and edema. Severe PIH can be complicated with intra-uterine fetus death and maternal death due to cerebral haemorrhage and renal and heptic failure.The aetiology of PIH remains unknown. PIH can spontaneously relieve its symptoms and signs after the delivery of placenta. It can also occur in hydatidiform mole, where no fetus is present, indicating that it is truly a 'placental disease. But it seems clear that one of the very first steps in the pathophysiological cascade that results in PIH is abnormal cytotrophoblast differentiation and invasion to the spiral arteries.Reduced form of nicotinamide edenine dinucleotide (NADH) dehydrogenase locates at the inner mitochondrial membrane. It is an important enzyme in tricarboxylic acid cycle, consisting of at least 43 proteins,of which, seven proteins are encoded by the mitochondrial genome, while the remainder are encoded by the nuclear genome. Now many studies have described thatabnormal expression of NADH dehydrogenase gene may be related with mitochondrial defect. In the present study, the expression of NADH dehydrogenase gene in placenta! tissue of patients with PIH was investigated and its role in PIH pathogenesis was discussed.Using 32P dATP labeled human NADH dehydrogenase cDNA probe, dot blot and Northern blot analysis were performed to detect the expression of NADH dehydrogenase gene in placental tissues from 10 normotensive term pregnant women and 10 PIH patients. Mean OD of each hybridization dot and band were measured by Image Analysis System to compare NADH dehydrogenase mRNA level in PIH placentas with that in normal placentas. Mean OD of NADH dehydrogenase gene in patients with PIH and normal pregnancy were 21.041+6.320, 56.263+16.517(dot blot), 27.182+8.605, 60.059+15.153 (Northern blot analysis) , respectively. It suggest that NADH dehydrogenase mRNA level in PIH placentas was significantly higher than that in normal placentas (p<0.05).Using Digoxin labeled human NADH dehydrogenase cDNA probe, in situ hybridization was carried out to detect the expression and localization of NADH dehydrogenase gene in placental tissues of 10 normal term pregnant women and 10 PIH patients. In situ hybrydization showed that NADH dehydrogenase gene is located at trophoblast of placenta. Density of NADH dehydrogenase staining of in situ hybridization in PIH and normal plasentas were 113+17,143+12, respectively. The level of NADH dehydrogenase mRNA in PIH placentas was significantly higher than that in normal placentas (p<0.05).Present results suggest that NADH dehydrogenase gene is located atplacental trophoblast and the elevated expression of NADH dehydrogenase gene may play some role in PIH pathogenesis.