[Effects of granulocyte colony-stimulating factor on hepatocyte apoptosis in acute liver failure: experiment with rats].

OBJECTIVE

To explore the effects of granulocyte colony- stimulating factor (G-CSF) on hepatocyte apoptosis in acute liver failure (ALF) and possible mechanism thereof.

METHODS

One hundred and sixty SD rats underwent intraperitoneal injection of D-galactosamine (D-GalN) 1.4 g/kg so as to establish AFL models and then were randomly divided into 2 equal groups: G-CSF therapy group, injected hypodermically with recombinant human G-CSF 50 microg x kg(-1) x d(-1) 2 hours after D-GalN injection for 3 consecutive days, and placebo control group, injected hypodermically with normal saline for 3 consecutive days. Liver samples were collected from 6 rats of each group 6 h, 12 h, 1 day, and 3 days after D-GalN injection respectively. Another six normal rats were used as normal control group. Hepatocyte apoptosis rate was measured by flow cytometry. Immunohistochemistry was used to detect the expression of Bcl-2 and caspase-3, a proapoptosis protein, in the liver sections.

RESULTS

The survival rate of the G-CSF therapy group was 53.3%, significantly higher than that of the placebo control group (33.3%, P = 0.027). The hepatocyte apoptosis rate and expression rates of Bcl-2 and caspase-3 in the liver sections after D-GalN injection increased along with time. The hepatocyte apoptosis rate peaked 1 day after the D-GalN injection in both groups. The maximum hepatocyte apoptosis rate of the G-CSF group was 29% +/- 7%, significantly lower than that of the placebo control group (44% +/- 12%, P = 0.026). The gray scale of Bcl-2 in liver sections at hour 12 of the G-CSF group was 152 +/- 37, significantly lower than that of the placebo control group (161 +/- 7, P = 0.012). and the gray scale of Bcl-2 on day 1 of the G-CSF group was 150 +/- 12, significantly lower than that of the placebo control group (159 +/- 9, P = 0.018). The gray scales of caspase-3 on days 1 and 3 of the G-CSF group were 189.6 +/- 4.6 and 184.7 +/- 4.8 respectively, both significantly higher than those of the placebo control group (169.6 +/- 15.7 and 160.0 +/- 5.0, both P = 0.000).

CONCLUSION

Apoptosis is a key mechanism contributing to ALF. G-CSF prevents ALF induced by D-GalN, thus raising the survival rate. G-GSF shows an inhibitory efficacy on hepatocytes apoptosis by probably up-regulating Bcl-2 and reducing caspase-3 expression.