Oxidative Stress Reacting And Expression Of Nuclear Factor-kappa B And Its Significance In Liver Cell Of Rats After Repeated And Sustained +10Gz Exposure

Objective 1. To make the animal model of +10Gz after repeated and sustained positive acceleration on rat liver tissue injury and explore physiological changes and behavioral activity in different periods; 2. Research + 10 Gz level of repeat sustained acceleration(+ Gz) on pathologic changes in the liver tissue; 3. To study oxidative stress reactions affects the expression of substance on liver cells after repeated and sustained +10Gz exposure; 4. Study and discuss the changes of the distribution and expression of NF-κB in the liver tissue under the positive acceleration(+Gz) exposure and self-protection mechanism.Methods All of Twenty four male Wistar rats were divided randomly into four groups and tested A, B and C groups-each group represented 0.5h,24 h and 48 h. The test was held in PLA of studying of acceleration. All tested rats were subjected of acceleration rate of 0.5G/s with the peak +10Gz and each +Gz exposure repeated 5 times with an interval of 30 min by computed control. The rats were in prone position, which fixed to the centrifuge arm and the direction of rat headed to the axis. Control group rats,however, were not subjected the acceleration stress, only fixed to the centrifuge arm. The details of tested methods refer to the public article[1]. Plasma of AST and ALT was monitored. Determination of antioxidant levels and lipid peroxidation products including superoxide dismutase(SOD), glutathione peroxidase(GSH- PX) and malondialdehyde(MDA) in liver tissue. Liver tissue was removed to use for immunohistochemistry and western blotting analysis in the expression of NF-κB after exposure.Results 1. The exposed rats were upset, dispersed hair, and disable to control piss and shit at the first and second period, and seemed aggravated to the acceleration condition after third and fourth period. At last period, the exposed rats didn’t have the force to resist; After +10 Gz exposure, the rats were seemed adapted to stress in the group A and B. They could have the normal activities in the group C; 2. the result revealed that+10Gz stress injury increased serum AST and ALT levels in Table1. Compared with the stress control, exposed group significantly increased in plasma ALT and AST compared with control group(P<0.05); 3.Compared with the control group, the SOD, GSH- P X expression levels is lower in the experimental B group(P <0.05). The experimental A and C groups have no difference compared to the control group(P>0.05); However, the expression level of the MDA in the experimental B group was higher than the control group(P<0.05). the experimental A and C groups compared to the control group have no significant difference(P>0.05); 4. NF-κB expression stained as brown particles was mainly detected in rat hepatocytes, also in the infiltrated cells and Kupffer cells.Exposed group significantly increased liver NF-κB expression in rats(P<0.05).Gradually, the expression level of NF-κB in experimental groups was significantly decreased(P<0.05). Group B liver tissue expression of NF-κB was the highest level and the group B was significantly higher than in group A(P<0.05).However, Group A and group C, group B and group C showed no significant difference(P> 0.05).Conclusion Experimental study of phase I research has found that repeated of +6Gz positive acceleration which had no significant effect on liver cells. The Subcellular damage of rat liver cells were seriously caused after high + Gz(above +6Gz) exposure.Mechanisms of injury involved multiple immediate early expression of genes and proteins. The study found that oxidative stress may be involved in the mechanism of injury reactive substances of SOD, GSH- PX and MDA; At the same time the exposure of +10 Gz, especially in the early stage acts as a stress to induce the activation of NF-κB suggesting that NF-κB plays an important role in the cascade reactions and adaptation to the acceleration stress. However, the clear gene regulation mechanism needs further studying.