Hepatoprotective effects of Yi Guan Jian, an herbal medicine, in rats with dimethylnitrosamine-induced liver fibrosis

Abstract

Aims of the study

Yi Guan Jian (YGJ) has long been employed clinically to treat liver fibrosis in traditional Chinese Medicine but the mechanism underlying the regulation has not been clarified in detail. The present investigation was designed to assess the involvement of the fibrosis pathway in dimethylnitrosamine (DMN)-induced liver fibrosis in rats.

Materials and methods

Liver fibrosis was induced by DMN injection (10 mg/kg, i.p., given three consecutive days each week) following 4 weeks. YGJ was oral administered (1.8 g/kg daily via gastrogavage for two weeks). Liver sample were subjected to histological and western blot studies. For evaluation of hepatic fibrosis-related factors, collagen α1-I, tissue inhibitor of metalloproteinase-1 (TIMP-1), and α-smooth muscle actin (α-SMA) mRNA and protein levels were analyzed.

Results

YGJ remarkably prevented body weight loss and DMN damage in the liver, and it inhibited the elevation of serum glutamate oxaloacetate transaminase (GOT), and glutamic pyruvic transaminase (GPT). Oral administration of YGJ extract significantly reduced the accumulation of collagen α1-I, TIMP-1, and α-SMA in liver tissues.

Conclusions

Taken together, these findings indicate that the YGJ Chinese herb showed hepatoprotective and anti-fibrogenic effects against DMN-induced hepatic injury. Our data suggest that the YGJ may be useful in reversing the development of hepatic fibrosis.

Introduction

Liver fibrosis is a result of severe liver damage that occurs in the presence of viral infections (especially hepatitis B or C), cholestasis, metabolic diseases, persistent alcohol abuse, autoimmune liver diseases or as a result of the administration of some medicines. Pathological liver fibrosis is mainly due to a loss of homeostasis that results in fibrogenesis and a disturbance of matrix degradation. The disease attributes include disruption of the architecture of the hepatic extracellular matrix (ECM) and an impairment of liver function (Iredale, 2003). It has been demonstrated that activated hepatic stellate cells (HSCs) are the primary cells responsible for the development of liver fibrosis (Tsukada et al., 2006). During liver injury, HSCs change from a quiescent to an activated state and undergo transformation into myofibroblast-like cells (Tsukada et al., 2006) that produce excessive ECM proteins, such as collagen α1-І and α1-Ш, glycoprotein, and other fibrosis-associated proteins, including tissue inhibitor of metalloproteinase-1 (TIMP-1) and matrix metalloproteinase-2 (MMP-2) (Friedman, 2000). Therefore, the inactivation of HSCs is the primary approach for blocking the progression of liver fibrosis (Bataller and Brenner, 2005).

Traditional Chinese herbal medicines (TCM) are multi-ingredient extracts with low adverse effects in the treatment of chronic liver diseases and are effective in preventing fibrogenesis and other chronic liver injuries (Yang et al., 2008, Mu et al., 2009, Lou et al., 2010). Yi Guan Jian (YGJ) is a complex prescription of Chinese herbal medicine consisting of 9 medical herbs (Radix Rehmanniae, Radix Glehniae, Radix Angelicae sinensis, Fructus Lycii, Radix Ophiopogomis, Fructus Mediae, Radix Astragalus membranaceus, Trionyx sinensis, and Eupolyphaga sinensis) (Mu et al., 2009). YGJ has been used to treat human liver fibrosis induced by hepatitis and has shown apparent efficacy in the reversal of liver fibrosis. The major active components of YGJ extract, ferulic acid and catalpol, significantly inhibit the progression of hepatic fibrosis induced by carbon tetrachloride (CCL₄) in animal model (Mu et al., 2009). In addition, a more clinical representation of liver fibrosis model showed that the livers in dimethylnitrosamine (DMN)-treated animals were shrunken with dark discoloration because of congestion (Nishikawa et al., 2009). However, the therapeutic effect of YGJ extract in the DMN-induced liver fibrosis has not been fully elucidated.

The HSCs produce the extracellular matrix and play important roles in injury repair and fibrosis in the liver. α-Smooth muscle actin (α-SMA) is a reliable marker for activated HSCs in human and rat liver. Strategies to prevent the proliferation of activated HSCs include prevention of the stimulation of growth factor receptors and/or to blockade of intracellular pathways required for proliferation (Friedman, 2008, Ikeda et al., 1999). Recent studies showed that the inhibition of HSC activation and the stimulation of HSC apoptosis enhance the resolution of liver fibrosis (Friedman, 2003, Elsharkawy et al., 2005). Furthermore, HSC apoptosis may also play a central role in the spontaneous recovery from biliary fibrosis (Issa et al., 2001). Therefore, it is important to discover the apoptosis mechanisms of HSC treated by traditional Chinese herbal medicines that might resolve progressive HSC proliferation and matrix synthesis (Lin et al., 2011).

The aim of this study was to investigate the therapeutic effects of YGJ extract, a traditional Chinese medicine (Mu et al., 2009) in a rat model of DMN-induced liver fibrosis (Jezequel et al., 1987). The therapeutic efficacy of YGJ extract for liver fibrosis was extensively evaluated on the basis of several HSC functions, histological examination, biochemical values, and fibrotic gene regulations.