Protective effects of Lycium ruthenicum Murr. juice on alcoholic liver injury in rats

Abstract

Objective: To study the protective effects of Lycium ruthenicum Murr. juice on alcoholic liver injury in rats and explore the regulatory mechanism of toll-like receptors 4 (TLR4)/p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway in this process. Methods: Sixty male SD rats were randomly divided into control group (C), model group (M), low-dose Lycium ruthenicum Murr. juice group (LLM), medium-dose Lycium ruthenicum Murr. juice group (MLM) and high-dose Lycium ruthenicum Murr. juice group (HLM), 12 rats in each group. The group M, LLM, MLM and HLM were treated with 20 ml/kg (8 g/(kg·d)) ethanol (400 g/L) intragastrically and the gavage was divided into two sessions, group C was treated with an equal volume of distilled water at the same time point. Four hours before the first alcohol gavage session, rats in each dose group of Lycium ruthenicum Murr. juice were administered with 2.4, 4.8, 9.6 ml/(kg·d) Lycium ruthenicum Murr. juice respectively, and the other groups were given equal volume of distilled water at the corresponding time points. Four weeks later, the rats were sacrificed 24 hours after the end of the last experiment, blood and liver were collected. The liver index was calculated. The morphology of the liver was observed by HE staining. The expressions of hepatic TLR4, p38 MAPK and phosphorylated p38 mitogen-activated protein kinase (p-p38 MAPK) were detected by immunohistochemistry. The activities of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were detected by colorimetry. The levels of hepatic tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-10 (IL-10) and interleukin-18 (IL-18) were detected by enzyme linked immunosorbent assay. Results: Compared with group C, the alcoholic liver injury model was established successfully in Group M. Compared with group M, related indicators in each dose group of Lycium ruthenicum Murr. juice were improved, the improvement of hepatic morphology in group HLM was the most significant, the liver index, the levels of serum ALT, AST and hepatic TLR4, p38 MAPK/p-p38 MAPK ratio, TNF-α, IL-1β, IL-18 were decreased (P＜ 0.05 or P＜0.01), while the level of hepatic IL-10 was increased (P＜0.01). Comparison among the dose groups of Lycium ruthenicum Murr. juice, the levels of liver index, serum AST and hepatic TLR4, p38 MAPK/p-p38 MAPK ratio, TNF-α, IL-18 in HLM were lower than those in LLM (P＜0.05 or P＜0.01); the level of hepatic IL-10 in HLM was higher than that in LLM and MLM (P＜0.05 or P＜0.01); the other indicators in each dose group had no statistical difference (P＞0.05). Conclusion: Lycium ruthenicum Murr. juice can improve the inflammatory stress by regulating TLR4/p38 MAPK signaling pathway, relieve alcoholic liver injury in rats, and the effect of high-dose group is better than the others.