BACKGROUND: Gadolinium chloride (GdCl3) is a specific inhibitor of Kupffer cells (KCs), which are important promoters of various liver injuries. It is therefore of interest to explore the role of KCs in liver ischemia-reperfusion injury and their relations with apoptosis caused by ischemia-reperfusion injury.
METHODS: One hundred male Wistar rats (190-210 g, 6-7 weeks old) were divided into two groups at random, GdCl3 group and control group. Samples were collected at 0.5, 1, 6, 12, and 24 hours from each group after reperfusion. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured by an automatic biochemical analyzer. TNF-α in serum was measured by enzyme-linked immunosorbent assay (ELISA). Malondialdehyde (MDA) in the liver mitochondria was measured by a colorimetric method. Pathological changes in the liver and immunohistochemical staining for caspase-3 were observed under an optical microscope. The ratio of apoptotic cells was measured by TdT-mediated dUTP nick-end labeling (TUNEL), and ultrastructural features of apoptosis were observed with a transmission electron microscope (TEM).
RESULTS: The levels of ALT in the GdCl3 group were lower than those in the control group after reperfusion for 0.5, 1, 6 and 12 hours (P<0.05); and the levels of AST in the GdCl3 group were lower than those in the control group after reperfusion for 6 and 12 hours (P<0.05). The levels of TNF-α in the GdCl3 group were lower than those in the control group after reperfusion for each time (P<0.05). The concentrations of MDA after reperfusion in the GdCl3 group were lower than those in the control group after reperfusion for 6, 12 and 24 hours (P<0.05). After reperfusion for 0.5, 1, 6 and 12 hours, the integral optical density (IOD) of caspase-3-positive cells was lower in the GdCl3 group than in the control group (P<0.05). After reperfusion for 1, 6, and 12 hours, the IOD of cells stained by TUNEL in the GdCl3 group was lower than that in the control group (P<0.05).
CONCLUSIONS: GdCl3 inhibits the activity of ALT, AST and TNF-α, decreases the accumulation of MDA in mitochondria, and depresses the expression of caspase-3 in liver after ischemia-reperfusion. This may be an important protective mechanism by depressing KCs and indirectly inhibiting liver cell apoptosis.