Submitted on May 9, 2007
Accepted on August 21, 2007
Rho-kinase inhibitor prevents hepatocyte damage in acute liver injury induced by carbon tetrachloride in rats
Hitoshi Ikeda1*, Yukio Kume2, Kazuaki Tejima1, Tomoaki Tomiya3, Takako Nishikawa3, Naoko Watanabe3, Natsuko Ohtomo3, Masahiro Arai4, Chihiro Arai3, Masao Omata5, Kenji Fujiwara6, and Yutaka Yatomi7
1 Department of Laboratory Medicine, The University of Tokyo, Graduate School of Medicine, Japan; Department of Gastroenterology, The University of Tokyo, Graduate School of Medicine, Tokyo, Japan
2 Department of Laboratory Medicine, The University of Tokyo, Graduate School of Medicine, Japan
3 Department of Gastroenterology, The University of Tokyo, Graduate School of Medicine, Tokyo, Japan
4 Department of Gastroenterology, Toshiba Hospital, Tokyo, Japan
5 Department of Gastroenterology, The University of Tokyo, Graduate School of Medicine, Japan
6 Department of Gastroenterology, Yokohama Rohsai Hospital, Kanagawa, Japan
7 Department of Laboratory Medicine, The University of Tokyo, Graduate School of Medicine, Tokyo, Japan
* To whom correspondence should be addressed. E-mail: ikeda-1im{at}h.u-tokyo.ac.jp.
A protective effect of Rho-kinase inhibitor on various organ injuries is gaining attention. Regarding liver injury, Rho-kinase inhibitor is reported to prevent carbon tetrachloride (CCl4)- or dimethylnitrosamine-induced liver fibrosis and hepatic ischemia-reperfusion injury in rats. Because Rho-kinase inhibitor not only improved liver fibrosis, but also reduced serum alanine aminotransferase level in CCl4-induced liver fibrosis, we wondered whether Rho-kinase inhibitor might exert a hepatocyte-protective effect. We examined this possibility in acutely CCl4 intoxication in rats. Rho-kinase inhibitor, HA-1077, reduced serum alanine aminotransferase level in rats with acute liver injury induced by CCl4 with the improvement of histological damage and the reduction of the number of apoptotic cells. In cultured rat hepatocytes in serum-free condition, HA-1077 reduced apoptosis evaluated by quantitative determination of cytoplasmic histone-associated DNA oligonucleosome fragments with the reduction of caspase 3 activity and the enhancement of Bcl-2 expression. HA-1077 stimulated phosphorylation of Akt, and wortmannin, an inhibitor of PI3-kinase/Akt pathway, abrogated the reduction of hepatocyte apoptosis by HA-1077 in vitro. Furthermore, wortmannin abrogated the reduction of serum alanine aminotransferase level by HA-1077 in rats with acute liver injury induced by CCl4, suggesting that the activation of PI3-kinase/Akt pathway may be involved in the hepatocyte-protective effect by Rho-kinase inhibitor in vivo. In conclusion, Rho-kinase inhibitor prevented hepatocyte damage in acute liver injury induced by CCl4 in rats, and merits consideration as a hepatocyte-protective agent in liver injury, considering its direct anti-apoptotic effect on hepatocytes in vitro.
