TAA and BDL caused significant liver dysfunction in rats and led to obvious liver fibrosis
Elevated serum levels of ALT and AST are indicators of liver injury(17). ALP levels are related to chronic liver injury(18). The serum levels of ALT, AST and ALP and the liver weights of normal female rats were significantly lower than those of male rats. The levels of ALT, AST, and ALP and the liver weights or liver indexes were significantly increased by BDL for 1 month and were much higher than those in rats treated with TAA for 23 weeks. These data suggest that BDL for 1 month induced an obvious inflammatory reaction in the livers of rats that was more potent than that of TAA (Figure 1).
Fibrosis is the excessive accumulation of collagen and other extracellular matrix components (EMCs) such as fibronectin (FN) and laminin (LN), due to chronic injury (19-21). Hydroxyproline is a characteristic component of collagen, and the content of hydroxyproline is related to the level of tissue fibrosis(22). As shown in Table 1, hydroxyproline in the livers of female rats was significantly higher than that in those of male rats. In addition, 1 month after BDL, the increase in hydroxyproline was significantly higher in female rats than in male rats treated with TAA for 23 weeks but BDL for 1 month showed lower pathological scoring, suggesting that the hydroxyproline level in liver was not completely proportional to the degree of fibrosis. The mediastinal form and connective tissue hyperplasia in the liver were more obvious in TAA rats than in BDL rats (Table 1, Figure 2), and α-SMA, the marker of HSC activation, was upregulated in the livers of BDL and TAA rats (Figure 3).
The effect of BDL on the levels of ILs in female rats is different from the effect of TAA in male rats
ILs include many cytokines that play an important role in liver injury or fibrosis. Many cells can synthesize or secrete ILs. Many cells can synthesis or secretion of ILs. As Figure 4 shows, the levels of interleukins, especially IL-4, IL-10, IL-13, IL-18 and L-12p70, in liver tissue of female rats were higher than those in the liver tissue of male rats. After BDL or TAA treatment, IL-1α, IL- 4 and IL-10 decreased, but IL-18 increased; BDL for a month upregulated IL-1β in the livers of female rats but had no significant effect on IL-6 and IL-12p70, while TAA decreased IL-1 β, IL-6 and IL-12p70 levels in the livers of male rats (Figure 4).