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.