Research On The Regulation Of P38MAPK/NF-κb Signaling In Chronic Intermittent Hypoxia-induced Nonalcoholic Steatohepatits

Objective:In recent years, studies have shown that SAHS can lead to liver injury, characterized by abnormal liver enzymes, hepatic steatosis and fibrosis. Oxidative stress plays an important role in the liver inflammation. However, the underlying regulatory mechanism by what kind of signal pathways that oxidative stress induced by SAHS and CIH cause liver inflammation is unclear. p38MAPK/NF-κB that are classic inflammatory signal transduction pathways in cell which play an important role in the regulating on inflammatory may participate in the regulatory mechanism of chronic intermittent hypoxia liver damage, In this study, we establish intermittent hypoxia rat animal model by simulating SAHS in the purpose of studying the regulation and interactive effects of p38MAPK/NF-κB signal pathways in the liver inflammation induced by CIH in vivo levels, to further investigate the molecular mechanism that CIH leads to NASH.Methods:Randomly dividing48male Wistar rats into6groups of8each. The control group is assigned as control group, which is fed with regular diet. The high-fat group is fed with high fat food. The intermittent hypoxia group is treated with8h/d intermittent hypoxia. The high-fat plus intermittent hypoxia group is fed with high fat food and at the same time, treated with8h/d intermittent hypoxia. The SB203580group and SN50group are also fed with high fat food and at the same time, treated with8h/d intermittent hypoxia, but in the end of4th, the SB203580group and SN50group is injected with SB203580and SN50respectively for two days. After4weeks, all rats are put to death. Meanwhile, return blood specimens and hepatic tissue in the purpose of testing serum liver enzyme levels, lipid, oxidative stress indicators and proinflammatory cytokine and observing liver histology and liver ultrastructure of the model rats. And detect the p38MAPK and NF-κB protein of liver tissue homogenate by western-blot technology.Results:(1)The effect of intermittent hypoxia on liver function and structure:While liver function and structure of the rats in the control group showed normal, the liver enzymes (ALT, AST) level in the high-fat plus intermittent hypoxia group appears to be significantly higher than that of the control group, the high-fat group and the intermittent hypoxia group; However, the liver enzymes level in the SB203580group and SN50group is not significantly lower than that of the high-fat plus intermittent hypoxia group. Observations were also made under light and electron microscopes. It appears that rats both in the high-fat group and the intermittent hypoxia group showed hepatic steatosis, hepatic steatosis in the high-fat group was more serious; The intermittent hypoxia group began to appear steatohepatitis; The high-fat plus intermittent hypoxia group was the most serious damage, characterized by steatohepatitis and hepatic fibrous hyperplasia; Under both light and electron microscopes, the severity of the liver injury of the rats in the SB203580group and SN50group was improved.(2) The effect of intermittent hypoxia on oxidative stress and systemic inflammation indicator:The serum malondialdehyde (MDA) level in the high-fat plus intermittent hypoxia group appeared to be significantly higher than that of the control group, the high-fat group and the intermittent hypoxia group; And the MDA level in the SN50group was obviously decreased in comparison with the high-fat plus intermittent hypoxia group. The serum tumor necrosis factor-a(TNF-a) level in the high-fat group, the intermittent hypoxia group and the high-fat plus intermittent hypoxia group was obviously higher than that of the control group, especially in the high-fat group and the high-fat plus intermittent hypoxia group; The serum interleukin-1(IL-1)level in the high-fat plus intermittent hypoxia group appeared to be significantly higher than that of the control group, the high-fat group and the intermittent hypoxia group; And the TNF-a level and IL-1level in the SN50group was both obviously decreased in comparison with the high-fat plus intermittent hypoxia group.(3) The effect of intermittent hypoxia on hepatic tissue NF-κB and p38MAPK protein expression:The hepatic tissue NF-κB protein expression in the intermittent hypoxia group and the high-fat plus intermittent hypoxia group was remarkably higher than that of the control group; The high-fat plus intermittent hypoxia group was significantly higher than that of the intermittent hypoxia group; The high-fat group and the control group had no significant difference; The hepatic tissue p38MAPK protein expression in the high-fat group、the intermittent hypoxia group and the high-fat plus intermittent hypoxia group was remarkably higher than that of the control group; The high-fat plus intermittent hypoxia group was remarkably higher than that of the intermittent hypoxia group; The intermittent hypoxia group was remarkably higher than that of the high-fat group; The hepatic tissue p38MAPK and NF-κB protein expression in the SB203580and SN50group was both significantly decreased.Conclusion:It is demonstrated in this research that (1) Chronic intermittent hypoxia can lead to liver injury, especially on the basis of high-fat food; Liver injury of Chronic intermittent hypoxia is characterized by elevated liver enzyme level and the histology is characterized by the feature of nonalcoholic steatohepatitis. It is demonstrated that CIH can promote the progression from simple fatty liver to steatohepatitis.(2) In the process of liver injury caused by chronic intermittent hypoxia, oxidative stress reaction and systemic inflammation is enhanced.(3) chronic intermittent hypoxia can active NF-κB and p38MAPK pathway. Block the NF-κB and p38MAPK pathway specifically can inhibit the two pathways active, resulting in improving the liver injury caused by chronic intermittent hypoxia. It is indicated that NF-κB and p38MAPK pathway plays an important role in the regulation mechanism of NASH induced by CIH. The research provides experimental and theoretical basis for further understanding the mechanism of chronic intermittent hypoxia liver injury and looking for possible new therapeutic targets.