(Z)-5-(4-methoxybenzylidene)thiazolidine-2,4-dione protects rats from carbon tetrachloride-induced liver injury and fibrogenesis

Abstract

To evaluate the hepatoprotective roles of (Z)-5-(4-methoxybenzylidene)thiazolidine-2,4-dione (SKLB010) against carbon tetrachloride (CCl₄)-induced acute and chronic liver injury and its underlying mechanisms of action. In the first experiment, rats were weighed and randomly divided into 5 groups (five rats in each group) to assess the protective effect of SKLB010 on acute liver injury. For induction of acute injury, rats were administered a single intraperitoneal injection of 2 mL/kg of 50% (v/v) CCl₄ dissolved in olive oil (1:1). Group 1 was untreated and served as the control group; group 2 received CCl₄ for induction of liver injury and served as the model group. In groups 3, 4 and 5, rats receiving CCl₄ were also treated with SKLB010 at doses of 25, 50 and 100 mg/kg, respectively. Blood samples were collected at 6, 12 and 24 h after CCl₄ intoxication to determine the serum activity of alanine amino transferase. Tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) were determined using enzyme-linked immunosorbent assay. At 24 h after CCl₄ injection, liver fibrogenesis was evaluated by hematoxylin-eosin (HE) staining and immunohistochemical analyses. Cytokine transcript levels of TNF-α, IL-1β and inducible nitric oxide synthase in the liver tissues of rats were measured using a reverse transcriptase reverse transcription-polymerase chain reaction technique. In the second experiment, rats were randomly divided into 2 groups (15 rats in each group), and liver injury in the CCl₄-administered groups was induced by a single intraperitoneal injection of 2 mL/kg of 50% (v/v) CCl₄ dissolved in olive oil (1:1). The SKLB010-treated groups received oral 100 mg/kg SKLB010 before CCl₄ administration. Five rats in each group were sacrificed at 2 h, 6 h, 12 h after CCl₄ intoxication and small fortions of livers were rapidly frozen for extraction of total RNA, hepatic proteins and glutathione (GSH) assays. In the hepatic fibrosis model group, rats were randomly divided into 2 groups (5 rats each group). Rats were injected intraperitoneally with a mixture of CCl₄ (1 mL/kg body weight) and olive oil [1:1 (v/v)] twice a week for 4 wk. In the SKLB010-treated groups, SKLB010 (100 mg/kg) was given once daily by oral gavage for 4 wk after CCl₄ administration. The rats were sacrificed one week after the last injection and the livers from each group were harvested and fixed in 10% formalin for HE and immunohistochemical staining. In this rat acute liver injury model, oral administration of SKLB010 blocked liver tissue injury by down-regulating the serum levels of alanine aminotransferase, suppressing inflammatory infiltration to liver tissue, and improving the histological architecture of liver. SKLB010 inhibited the activation of NF-κB by suppressing the degradation of IκB, and prevented the secretion of pro-inflammatory mediators such as tumor necrosis factor-α, interleukin-1β, and the reactive free radical, nitric oxide, at the transcriptional and translational levels. In this chronic liver fibrosis model, treatment with 100 mg/kg per day SKLB010 attenuated the degree of hepatic fibrosis and area of collagen, and blocked the accumulation of smooth-muscle actin-expressed cells. These results suggest that SKLB010 is a potent therapeutic agent for the treatment of CCl₄-induced hepatic injury.