Taurine alleviates lipopolysaccharide‑induced liver injury by anti‑inflammation and antioxidants in rats

Abstract

The aim of the present study was to investigate the protective effect of taurine on lipopolysaccharide (LPS)‑induced liver injury and its mechanisms. Male rats were randomly divided into three groups: Normal saline, LPS model and taurine treatment. Experimental animals were treated with saline or taurine (dissolved in saline, 200 mg/kg/day) via intravenous injection. After 2 h, saline or LPS (0.5 mg/kg) was administrated via intraperitoneal injection. Markers of liver injury, pro‑inflammatory cytokines and superoxide dismutase (SOD) activity were determined in plasma. Liver tissues were removed for morphological analysis and determination by western blot analysis. Taurine significantly reduced the elevation in the levels of LPS‑induced aspartate transaminase and alanine transaminase and decreased the concentrations of LPS‑induced inflammatory factors including tumor necrosis factor‑α and interleukin‑6. Taurine also increased the activity of SOD in serum and the expression of heme oxygenase‑1 protein in liver tissue. Taurine pretreatment also reduced the elevated expression levels of LPS‑induced cyclooxygenase‑2, nuclear factor κB and extracellular regulated protein kinase. The results from the present study demonstrated that taurine alleviates LPS‑induced liver injury. The beneficial role of taurine may be associated with its reduction of pro‑inflammatory response and oxidative stress.

Figure 1.

Effects of taurine on the levels of (A) AST and (B) ALT. Data are presented as the mean ± standard deviation (n=10). **P<0.01 vs. NS group and ^##P<0.01 vs. LPS group. AST, aspartate transaminase; ALT, alanine transaminase; NS, normal saline group; LPS, lipopolysaccharide control group; TL, taurine + LPS group.

Figure 2.

Effects of taurine on the levels of (A)SOD and (B) MDA. Data are presented as the mean ± standard deviation (n=10). **P<0.01 vs. NS group and ^##P<0.01 vs. LPS group. SOD, superoxide dismutase; MDA, malonaldehyde; NS, normal saline group; LPS, lipopolysaccharide control group; TL, taurine + LPS group.

Figure 3.

Effects of taurine on the levels of (A) IL-6, (B) TNF-α and (C) PCT. Data are presented as the mean ± standard deviation (n=10). *P<0.05 vs. NS group, **P<0.01 vs. NS group, ^#P<0.05 vs. LPS group and ^##P<0.01 vs. LPS group. IL-6, interleukin 6; TNF-α, tumor necrosis factor-α; PCT, procalcitonin; NS, normal saline group; LPS, lipopolysaccharide control group; TL, taurine + LPS group.

Figure 4.

Photomicrographs of hematoxylin and eosin staining in the liver tissue of each group. (A) NS group, (B) LPS group and (C) TL group. Scale bar, 100 µm. NS, normal saline group; LPS, lipopolysaccharide control group; TL, taurine + LPS group.

Figure 5.

Effects of taurine on the expression levels of HO-1, COX-2, pNF-κB and p-ERK protein. Representative western blot images and quantification of (A) HO-1, (B) COX-2, (C) pNF-κB and (D) p-ERK. Data are presented as the mean ± standard deviation. **P<0.01 vs. NS group and ^##P<0.01 vs. TL group; n=6 per group. HO-1, heme oxygenase-1; COX-2, cyclooxygenase-2; NF-κB, nuclear factor-κB; ERK, extracellular signal-regulated kinase; p-, phosphorylated.