| PrefaceDuring Preoperation, the anesthesia, operation and the developing of diseases can cause critical hypoxia. The brain cells highly depend on oxygen metabolism in mitochondria!, so they are sensitive to hypoxia and the acute neuronal damage caused by hypoxia occur easier. Therefore, acute hypoxia plays an important role in the preopera-tional death and central nervous system damage. Preoxygenation is the routine treatment of clinical anesthesia in preventing from hypoxia, whereas hyperoxia can not avoid hypoxia completely, so the phase of preoxygenation, hypoxia and reoxygenation appears. Normally, it is considered that hyperoxia cant induce serious damage, but hyperoxia is the major origin of ROS and cause the hyperoxidate response. The effects of preoxygenation on neuronal mitochondrial antioxidant defense and brain injury are still unknown, so it is important to evaluate the effect of preoxygenation on hypoxia/reoxygenation cerebral injury. This study was designed to examine the rat cortex HSP70 by imunohis-tochemistry, observe the neuronal damage by histology, and evaluate the change of endogenous Mn - SOD in mitochondrial by xanthine oxi-dase.Material84 Wistar male rats ( 230 - 280g, supplied by the department of Laboratory Animals, China Medical University) were randomly divid-ed into three groups, group A (Control group) , group B and C (50% and 100% preoxygenation test group) , and each group was divided into four subgroups, followed the four phases of preoxygenation (or normoxia) - hypoxia - reoxygenation 1h - reoxygenation 6h, n = 7. A1,B1 and C1 were individually exposed to normoxia or preoxygenation ( 50% and 100% O2) for 30 minutes. A2,B2 and C2 were exposed to hypoxia (5%O2) for 30 minutes after preoxygenation. A3 -4,B3 -4 and C3 -4 were exposed to reoxygenation (100%O2) for 1h or 6h after preoxygenation and hypoxia. A1 was normal control subgroup, A2 was hypoxia control subgroup, A3 and A4 were reoxygenation 1h and 6h control subgroup.Methods1. Imunohistochemistry: we used an affinity - purified HSP70 antibody and peroxidase marked streptavidin to detect the presence of HSP70 positive cells in the cerebral cortex.2. Histology; The brain samples were fixed and embedded as previous reported method. 4u,m - sections were cut and stained with a hematoxylin -eosin (HE) for histological examination.3. Xanthine oxidase method: Detecting of Mn -SOD activity accorded the standard kit production.4. Thiobarbiturate method: Preparing the homogenate, measuring the protein content, malondialdehyde (MDA) was assayed according the standard kit production.5. Statistics: All values were expressed as the mean ?standard deviation. Statistics analysis was performed with One - Way analysis of variation ( ANOVA) and Dunnett t test. A level of p <0. 05 wasconsidered significant.Result1. The results of control groupThe HSP70 positive cells appeared less in normal control subgroup , and didnt change obviously in A2 and A3 subgroups, but it increased obviously in reoxygenation A4 subgroup. The content of MDA increased in A2 and A3 -4 subgroups, but only the A2 subgroup was considered significandy as compared with control subgroup, and A3 -4 subgroups decreased significandy as compared with A2 subgroup. The activity of Mn - SOD increased gradually after hypoxia and reoxygenation, but only A3 -4 subgroups increased significandy, and A4 also increased significandy as compared with A2 subgroup.2. The results of Preoxygenation test groupsThe rate of HSP70 positive cells in B and C corresponding subgroups was significandy different from that of control subgroups except C2 subgroup. The HSP70 positive rate increased after preoxygenation, and Cl increased more significandy than Bl subgroup. The positive rate decreased significandy after hypoxia, especially in the C2 subgroup, but increased significandy after reoxygenation. B4 exceeded the B3 subgroup significandy, but C4 subgroup had the opposite result.MDA increased after preoxygenation, especially in... |
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