Protective effects of Ginkgo Biloba Dropping Pills against liver ischemia/reperfusion injury in mice

BACKGROUND: Liver ischemia/reperfusion (I/R) injury is an inevitable pathological phenomenon in various clinical conditions, such as liver transplantation, resection surgery, or shock, which is the major cause of morbidity and mortality after operation. Ginkgo Biloba Dropping Pill (GBDP) is a unique Chinese Ginkgo Biloba leaf extract preparation that exhibits a variety of beneficial biological activities. The aim of this study is to investigate the protective effects of GBDP on the liver I/R injury both in the in vitro and in vivo. METHODS: Hypoxia/reoxygenation (H/R) experiments were performed in alpha mouse liver 12 (AML-12) cells and primary hepatocytes, which were pretreated with GBDP (60 or 120 µg/mL) followed by incubation in a hypoxia chamber. Cell viability was detected by 3-(4,5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) assay. Annexin V staining as well as western blot analysis of apoptosis-related proteins was performed to detect the protective effect of GBDP on cell apoptosis induced by H/R injury. C57BL/6 mice were used to establish the liver I/R injury model, and were pretreated with GBDP (100 or 200 mg/kg/day, i.g.) for two weeks. The liver damage was evaluated by detection of plasma levels of alanine transaminase (ALT) and aspartate transaminase (AST), as well as histopathological examinations. Liver inflammation was determined by detecting the secretion of pro-inflammatory cytokines and neutrophil infiltration through enzyme-linked immunosorbent assay (ELISA) and myeloperoxidase (MPO) immunohistochemistry staining. Finally, Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick and labeling (TUNEL) staining and western blot analysis of apoptosis-related proteins were used to investigate the anti-apoptotic effect of GBDP in mice. RESULTS: In the in vitro study, GBDP pretreatment improved the cell viability of AML-12 cells in the H/R injury model. Similarly, the same result was found in the primary hepatocytes isolated from C57BL/6 mice. Moreover, GBDP decreased the number of apoptotic cells and reduced the expression of apoptosis-related proteins induced by H/R injury. In the in vivo study, oral administration of GBDP ameliorated liver injury evidenced by a significant decline in the levels of ALT and AST. Furthermore, the result of hematoxylin and eosin (H&E) staining showed that GBDP reduced the size of necrosis area in the liver tissue. In addition, the decreased infiltration of neutrophils and secretion of pro-inflammatory cytokines indicated that GBDP may play an anti-inflammatory effect. More importantly, GBDP reduced TUNEL-positive cells and the expression of apoptosis-related proteins in the liver indicating GBDP has anti-apoptotic effects. CONCLUSIONS: Our findings elucidated that GBDP has potential effects for protecting against liver I/R injury characterized by its anti-apoptotic, anti-necrotic, and anti-inflammatory properties, which would promisingly make contributions to the exploration of therapeutic strategies in the liver I/R injury.