RESUMO
Objective To observe hepatocellular apoptosis and inflammatory cytokines expression and their mechanisms for lipopolysaeeharide (LPS)-induced acute liver failure in D-ga|actosamine (D-GalN)-sensitized rats. Methods Fifty-six rats were randomly divided into following groups: 0, 1, 2, 4, 6, 24 and 48 hours. 0 hour group served as control group and the rest did as treatment groups. The rats in the treatment groups received intraperitoneal injections of LPS (50 ng/g) and D-GaIN (300 μg/g) dissolved in 1 mL sterile 0.9% sodium chloride solution, while the rats in control group were treated with 1 mL sterile 0.9% sodium chloride solution only. The rats were sacrificed in the corresponding time points and their sera and liver tissues were collected. Liver tissues were fixed and stained with hematoxylin and eosin for optical microscopy examination. The serum cytokine expressions were detected by enzyme-linked immunosorbent assay (ELISA). The expressions of tumor necrosing factor (TNF)-α, interleukin (IL)-1β, inducible nitric oxide synthase (iNOS) and p53 gene were detected by reverse transcriptase-polymerase chain reaction, and the 24 hours treated rats liver Caspase-3,8,9,12 activity were detected by chromogenie substrate method. Data for the experiments were expressed as x±s, and differences among means were compared using the analysis of variance. Results After drug treatment, liver tissues showed piecemeal necrosis and inflammatory cell infiltration, which significantly increased from 6 hours, 24 hours to 48 hours. The 1 hour treatment group with the highest concentration of TNF-α (727. 8 ± 261. 3) ng/L were significantly higher than the control group and other treatment groups(F= 49.82, P<0.01), 2 hours treatment group (156.4 ± 52.2) ng/L was significantly lower than the 1 hour group, but significantly higher than the control group (F = 30. 23, P< 0.01 ). But serum concentrations of IL-1β gradually increased, reaching the highest level in 24 hours group (360.5±121.6)ng/L (F= 18. 61, P<0. 01). Liver Caspase-3,8,9, 12 activity in 24 hours treatment group was significantly higher than in the control group (F= 84.96, P<0.01). The mRNA expression of iNOS gene, which were not detected in normal controls, reached the peak at 6 hours group after drug treatment and notably dropped in 24 hours and 48 hours groups(F=34.07,P<0.01), p53 gene expression significantly upregulated at 24 hours and 48 hours groups(F=37.43,P<0.01). TNF-α and IL-1β gene expression in the treatment group were higher than in the control group(F=2.94,P<0.05), and both reached the peak at 1 hour treatment group. Conclusions Acute liver failure can be induced by low dose LPS in D-GaiN-sensitized rats. One of the features changes is that Caspase-3,8,9,12 activities are markedly enhanced, and the occurrence of liver injury may be associated with the early high expression of TNF-α, iNOS and p53 gene.