Cryptotanshinone ameliorates hemorrhagic shock-induced liver injury via activating the Nrf2 signaling pathway

Abstract

Introduction: Hemorrhagic shock (HS) is an important cause of high mortality in traumatized patients. Cryptotanshinone (CTS) is a bioactive compound extracted from Salvia miltiorrhiza Bunge (Danshen). The current study aimed to explore the effect and underlying mechanism of CTS on the liver injury induced by HS.

Material and methods: Male Sprague-Dawley rats were used to establish the HS model by hemorrhaging and monitoring mean arterial pressure (MAP). CTS was intravenously administered at concentration of 3.5 mg/kg, 7 mg/kg, or 14 mg/kg 30 minutes before resuscitation. Twenty-four hours after resuscitation, the liver tissue and serum samples were collected for the following examinations. Hematoxylin and eosin (H&E) staining was used to evaluate hepatic morphology changes. The myeloperoxidase (MPO) activity in liver tissue and the serum activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were examined to reveal the extent of liver injury. The protein expression of Bax and Bcl-2 in liver tissue was detected by western blot. The TUNEL assay determined the apoptosis of hepatocytes. Oxidative stress of liver tissue was assessed by the examination of reactive oxygen species (ROS) generation. The content of malondialdehyde (MDA), glutathione (GSH), and adenosine triphosphate (ATP), the activity of superoxide dismutase (SOD) and oxidative chain complexes (complex I, II, III, IV), as well as cytochrome c expression in cytoplasm and mitochondria, were also used to determine the extent of oxidative injury in the liver. Immunofluorescence (IF) was employed to estimate nuclear factor E2-related factor 2 (Nrf2) expression. The mRNA and protein levels of heme oxygenase 1 (HO-1), NAD(P)H: quinone oxidoreductases 1 (NQO1), cyclooxygenase-2 (COX-2), and nitric oxide synthase (iNOS) were assessed by real-time qPCR, western blot to investigate the mechanism of CTS regulating HS-induced liver injury.

Results: H&E staining and a histological score of rat liver suggested that HS induced liver injury. The activity of ALT, AST, and MPO was significantly increased by HS treatment. After CTS administration the ALT, AST, and MPO activities were suppressed, which indicates the liver injury was alleviated by CTS. The HS-induced upregulation of the TUNEL-positive cell rate was suppressed by various doses of CTS. HS-induced ROS production was decreased and the protein expression of Bax and Bcl-2 in the HS-induced rat liver was reversed by CTS administration. In the liver of HS-induced rats, the upregulation of MDA content and the downregulation of GSH content and SOD activitywere suppressed by CTS. Additionally, CTS increases ATP content and mitochondrial oxidative complexes activities and suppressed the release of cytochrome c from mitochondria to the cytoplasm. Moreover, IF and western blot demonstrated that the activation of Nrf2 blocked by HS was recovered by different doses of CTS in liver tissue. The expression of downstream enzymes of the Nrf2 pathway, including HO-1, NQO1, COX-2, and iNOS, was reversed by CTS in the HS rat model.

Conclusions: The current study for the first time revealed the protective effect of CTS in HS-induced liver injury. CTS effectively recovered hepatocyte apoptosis, oxidative stress, and mitochondria damage induced by HS in the rat liver partly via regulating the Nrf2 signaling pathway.

Keywords: Nrf2; ROS; Salvia miltiorrhiza Bunge; cryptotanshinone; hemorrhagic shock; liver injury.