The Study Of Inhibition Of Proteasome LMP7 And Proteasome Maturation Protein Induced By Ethanol

Objective To observe the pathology and ultramicro-structure changes in the rat models of alcoholic liver disease, and to evaluate the expression of proteasome LMP7 and proteasome maturation protein under carbonyl stress, and investigate the effect of the two in the pathogenesis of alcoholic liver disease.Methods After one-week acclimatization period, 40 male Wistar rats (180-200g) were divided into model groups and control group (n=8). The rats in the model groups were gavaged by intragastric ethanol infusion: 40% ethanol 5g/kg/day for 4 weeks, 50% ethanol 7g/kg/day for the next 4 weeks, 60% ethanol 10g/kg/day for the last 4 weeks. They had free access to water and to a diet: ethanol, 46% of the total calories; proteins 18%, carbohydrates 12% and lipids 14%(9% was unsaturated fatty acid) and adequate vitamin and salt mix during the whole experiment. The rats in the control group were treated with saline of the same volume, and the carbohydrate content was up to 52% of the total energy required which had been replaced by ethanol. At the end of 6^th , 8^th. 10^th 12^th week of the experiment, the rats were sacrificed. HE staining histopathological section and electron micrograph investigate the histological alterations; Protein carbonyl contents were detected by 2,4-Dinitrophenyl hydrazine colorimetry, the expressions of chymotrypsin-like activity subunit LMP7 and POMP were detected by RT-PCR and Western -blotting. Results Pathological findings revealed that liver damage occurred at 6^th week, and it is obviously at 12^th week and apoptotic changes were seen. The biochemical criterion of model groups were dramatic higher than control group. Compared with control group, the contents of protein carbonyl were much higher in model guoups (P<0.05), and increased in a dose dependent manner. The expressions of LMP7 were decreased in model groups. It shows the negative correlation with protein carbonyl content. After infusion of ethanol, there was a dramatic increase in POMP levels, which was not observed in control vector.Conclusion 1 We successefully copied alcoholic liver animal model. 2 Hepatic tissues are under carbonyl stress in alcoholic liver disease, the alcohol administration result in decreased expression of LMP7 which may be play a vital role in the pathogenesis of alcoholic liver disease. 3 Ethanol inhibits proteasome activities and reduce the proteolysis of carbonylated proteins, and thus induced the changes of cellular morphology and function. 4 Ethanol induced proteasome malfuntion might be responsible, at least in part, for the obstacles of proteasome mature mechanism.