The present study investigated the mechanism of the Tibetan medicine Ershiwuwei Songshi Pills(ESP) against the liver injury induced by acetaminophen(APAP) in mice based on the kelch-like ECH-associated protein 1(Keap1)/nuclear transcription factor E2 related factor 2(Nrf2) and Toll-like receptor 4(TLR4)/nuclear factor-kappa B(NF-κB) p65 signaling pathways. Kunming mice were randomly divided into a blank control group, a model group, an N-acetyl-L-cysteine(NAC) group, and high-(400 mg·kg~(-1)), medium-(200 mg·kg~(-1)), and low-dose(100 mg·kg~(-1)) ESP groups. After 14 days of continuous administration, except for those in the control group, the mice were intraperitoneally injected with 200 mg·kg~(-1) APAP. After 12 h, the serum and liver tissues of mice were collected. Hematoxylin-eosin(HE) staining was performed on pathological sections of the liver, and the levels of aspartate aminotransferase(AST) and alanine aminotransferase(ALT) in the serum and the levels of glutathione(GSH), malondialdehyde(MDA), superoxide dismutase(SOD), catalase(CAT), myeloperoxidase(MPO), and total antioxidant capacity(T-AOC) in liver tissue homogenate were detected to observe and analyze the protective effect of ESP on APAP-induced liver injury in mice. The serum levels of tumor necrosis factor-alpha(TNF-α), interleukin-1 beta(IL-1β), and interleukin-6(IL-6) were determined by enzyme-linked immunosorbent assay(ELISA). The protein expression of Nrf2, Keap1, TLR4, and NF-κB p65 in the liver was determined by Western blot. Quantitative real-time was used to determine the mRNA expression of glutamate-cysteine ligase catalytic subunit(GCLC), glutamate-cysteine ligase regulatory subunit(GCLM), heme oxygenase-1(HO-1), and NAD(P)H dehydrogenase quinone 1(NQO-1) in the liver to explore the mechanism of ESP in improving APAP-induced liver damage in mice. As revealed by results, compared with the model group, the ESP groups showed improved liver pathological damage, decreased ALT and AST levels in the serum and MDA and MPO content in the liver, increased GSH, SOD, CAT, and T-AOC in the liver, reduced TNF-α and IL-6 levels in the serum, down-regulated expression of Keap1 in the liver cytoplasm and NF-κB p65 in the liver nucleus, up-regulated expression of Nrf2 in the liver nucleus, insignificant change in TLR4 expression, and elevated relative mRNA expression levels of antioxidant genes GCLC, GCLM, HO-1, and NQO-1. ESP can reduce the oxidative damage and inflammation caused by APAP, and the mechanism may be related to the Keap1/Nrf2 signaling pathway and the signal transduction factors on the TLR4/NF-κB p65 pathway.
Keywords: Ershiwuwei Songshi Pills; NF-κB p65; Nrf2; Tibetan medicine; acetaminophen; signaling pathway.