| ObjectiveAcetaminophen (APAP) is a widely used antipyretic analgesics, which could cause serious hepatic injury even cause acute hepatic failure when taking large dose for a long time or over dose of APAP, taking APAP with drinking wine or alcoholic beverages simultaneously, taking APAP with other cold medications containing APAP or other medications at the same time and so on. The hepatic encephalopathy (HE) is a serious complication of liver failure with a high mortality and serious harm to human health. Taurine (TAU) possesses extensive biological effects as an antioxidant. Some researches have indicated that TAU had protective effects on various liver injuries. Therefor, this study would investigate the protection of TAU against APAP-induced hepatic damage and HE induced by thioacetamide (TAA) and the mechanisms of the protection by comparison with some oxidative/nitrative indicators of normal rats, APAP-induced hepatic damage rats, taurine pretreated APAP hepatic damage rats, HE rats and taurine pretreated HE rats, and provide new ideas and scientific basis to the prevention against APAP-induced hepatic damage and complication of liver failure.Methods1 Experimental study of hepatic damage rats1.1 Establishment and grouping of APAP-induced hepatic damage rats Male Wistar rats were divided into 3 groups randomly according to their weights (8 in each group):blank control group (Ⅰ), APAP-induced liver injury group(Ⅱ) and taurine pretreated liver injury group (Ⅲ). Rats in groupⅢwere treated intragastrically with taurine (100 mg/kg/d) for 30 days and the other two groups were given normal saline intragastrically in the same dose. After 30 days, All the groups except groupⅠwere given single oral administration of APAP (750 mg/kg) to establish liver damage model.1.2 Establishment and grouping of HE rats The model of HE rats was established by TAA. Male Wistar rats were divided into 3 groups randomly according to their weights (8 in each group):blank control group (Ⅰ), HE model group (Ⅳ) and taurine pretreated HE group (Ⅴ). Rats in group V were treated intragastrically with taurine (100 mg/kg/d) for 30 days and the other two groups were given normal saline intragastrically in the same dose. After 30 days, All the groups except groupⅠwere treated with TAA (300 mg/kg) by intraperitoneal injection (i.p.) at the first day and 150 mg/kg by i.p. at the second day to manufacture the model of HE until the symptoms of HE appeared. At the same time rats in groupⅠwere treated with normal saline i.p. in the same dose.2 Determination of various biochemical indicators All the rats were decapitated to collect blood and liver tissues to determine the contents of GSH, TAU, 3-NT, ALT, MDA and SOD in serum and TAU in hepatic tissues. The contents of GSH and 3-NT in serum were detected by HPLC-fluorescence detection method. The levels of TAU in serum and hepatic tissues were detected by HPLC-UV detection method. The activity of the ALT was detected by Reitman-Frankel. The contents of MDA were detected with the thiobarbituric acid method. And the vitality of SOD in serum was detected using xanthine oxides enzymaic method.3 The fabrication and stain of tissue section Liver tissues were obtained after rats in each group were sacrificed to make the paraffin section. And then the pathologic changes were observed by hematoxylin-eosin staining.Results1 The general state and the dissection of rats Anatomy of rats in groupⅡwe found that most livers were congestive, enlarged, purple, and soft. The shape, size and nature of livers in groupⅢwere similar with normal rats. After two days' injection of TAA, the rats in group IV presented the HE symptom ofⅠorⅡperiod. After reducing the quantity of TAA according to the condition of each rat, rats could aggravate to the symptom ofⅢorⅣperiod in 3-5 days. Anatomy of the rats, we found that the surface of liver was graininess, smaller in size, dark purple or dark red, crisp and had a large number of bleeding points. After gavaging rats in group V the development of HE symptoms delayed, and did not appear or only mild symptoms of HE. Anatomy of the rats, we found that the shape, size and nature were similar with normal rats.2 The analysis of biochemical indexes in serum of rats2.1 The comparison of serum levels of ALT,3-NT, GSH, SOD and MDA in groupⅠ,ⅡandⅢCompared to groupⅠ, the activity of ALT in groupⅡwas statistically increased (P<0.05) which suggested that APAP induced liver damage modle was successfully established. The obvious increase of 3-NT (P<0.05) indicated that tyrosine nitration was serious. The remarkable decrease of serum GSH (P<0.05) and SOD (P<0.05) and increase of MDA (P<0.05) suggested the antioxidation ability weakened and lipid peroxidation damage aggravated. Compared groupⅢwith groupⅡ, the contents of ALT,3-NT and MDA were statistically decreased, and the levels of GSH and SOD were obviously increased, but with groupⅠ, the indexes mentioned above had no significantly differences. That suggested taurine had some protection against the liver damage induced by APAP.2.2 The comparison of TAU levels in serum and livers of groupⅠ,ⅡandⅢTAU can be used as a marker of early liver damage induced by APAP. Compared among three groups, the serum TAU levels in groupⅡwere obviously increased (P<0.01) and there were no significant differences between groupⅢand I; TAU levels in liver tissue of groupⅡwere obviously decreased (P<0.01) and there were no statistical differences between groupⅢandⅠ.2.3 The correlation analysis of serum TAU with 3-NT, GSH, SOD and MDA in groupⅠ,ⅡandⅢThere was good correlation between TAU and 3-NT, GSH, SOD, MDA in serum of the three groups rats. The relation between TAU and 3-NT, MDA was positively correlated (P all<0.01), and negatively correlated (P all<0.01) between TAU and GSH, SOD.2.4 The comparison of serum levels of ALT,3-NT, GSH, SOD and MDA in groupⅠ,ⅣandⅤCompared to groupⅠ, the activity of ALT in group IV was statistically increased (P<0.05) which suggested that rats in group IV suffered liver damage. The obvious increase of 3-NT (P<0.05) indicated that tyrosine nitration was serious. The remarkable decrease of serum GSH (P<0.05) and SOD (P<0.05) and increase of MDA (P<0.05) suggested the antioxidation ability weakened and lipid peroxidation damage aggravated. Compared groupⅤwith groupⅣ, the contents of ALT,3-NT and MDA were statistically decreased (P<0.05, P<0.05, P<0.05), and the levels of GSH and SOD were obviously increased (P<0.05, P<0.05). Compared to groupⅠ, the indexes mentioned above had no significantly differences. That suggested taurine indeed had some protection against the development of HE.2.5 The comparison of TAU levels in serum and livers of groupⅠ,ⅣandⅤThat the serum TAU levels in group IV were obviously decreased (P<0.01) compared to groupⅠsuggested the hepatic cells were damaged in group IV rats. Compared group V with groupⅣ, TAU levels increased (P<0.01) and there were no significant differences compared to groupⅠ; TAU levels in liver tissue of groupⅣwere obviously decreased (P<0.01) and there were no statistical differences between groupⅤandⅠ.2.6 The correlation analysis of serum TAU with 3-NT, GSH, SOD and MDA in groupⅠ,ⅣandⅤThere was good correlation between TAU and 3-NT, GSH, SOD, MDA in serum of the three groups rats. The relation between TAU and 3-NT, MDA was negatively correlated (P all<0.01), and positively correlated (P all<0.01) between TAU and GSH, SOD.3 The result of histology observation Disorderd liver structure, varying degrees of necrosis and many inflammatory cells infiltration were showed in livers of groupⅡ. In livers of groupⅣ, hepatic lobule structure was unclear, the hepatic cells were serious necrosis, dissolved or disappeared, and many inflammatory cells infiltrated. In addition, a high degree of edema cells were showed in livers of rats in groupⅣ, they presented ground glass change or ballooning degeneration. As compared groupⅢ,Ⅴwith groupⅠ, there were no obvious changes with hepatic lobule structure, while the volume of liver cells increased.ConclusionsThis study discussed the role of taurine on liver damage from two points of biochemistry and histopathology. By comparing the changes of these oxidative /nitrative indexes, the research revealed that taurine not only had some protection against liver damage caused by APAP but also had protection on the conplication of liver failure, and the protective machanisms may be related to the antioxidant and anti nitrification of taurine. Besides, the study also indicated the relation between changes of taurine and oxidative/nitrative indexes by analysis of the correlation of serum TAU with the above indexes, and confirmed the significance of dietary supplement taurine. |
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