Secoemestrin C ameliorates liver injury in Con A-challenged mice
Next, we evaluated the effects of secoemestrin C on Con A-induced hepatitis in vivo . A severe liver injury was observed in mice 8 h after Con A administration, which manifested itself as a significant elevation in serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) when compared to the normal (control) mice (Fig. 3A-C). In contrast, pretreatment with secoemestrin C at a higher dose (10mg·kg-1) almost completely inhibited the increase in the serum levels of ALT, AST, and LDH induced by the Con A challenge (Fig. 3A-C).
To further confirm the hepatoprotective effect of secoemestrin C, hematoxylin-eosin (H&E)-stained liver tissue sections were evaluated for histopathology. In the Con A-treated group, massive bridging coagulative necrosis of hepatocytes was visualized by light microscopy (Fig. 3D). However, the hepatic pathological changes induced by Con A were dramatically reduced in the mice treated with high-dose secoemestrin C (Fig. 3D, E).
The apoptotic response plays an important role in Con A-induced liver injury. To investigate the pathway of secoemestrin C involved in the regulation of hepatocyte apoptosis, we used TUNEL staining as well as Fas and cleaved caspase-3 staining to analyze hepatocyte apoptosis in the livers of the mice. The area of apoptotic cells in the Con A group was significantly larger than that in the normal control group (Figure 3F, G). Mice pretreated with a high dose of secoemestrin C showed a much smaller apoptotic area in the liver (Fig. 3F, G). Furthermore, the expression of two apoptosis-related proteins, Fas and cleaved caspase-3, was markedly elevated in Con A-challenged mice, whereas expression of the two proteins was almost completely suppressed in the mice who received the high-dose secoemestrin C treatment (Supplemental Fig. 2). Together, these results indicate that pretreatment with secoemestrin C provides significant protection against Con A-induced hepatic damage.