Sinomenine pretreatment attenuates cold ischemia/reperfusion injury in rats: The role of heme oxygenase-1

Ischemia/reperfusion (I/R) injury can be characterized as an inflammatory response including recruitment of inflammatory cells to a post-ischemic organ or tissue and a cascade of mediators. Sinomenine (SIN), a pure alkaloid extracted from the Chinese medical plant Sinomenium acutum, has been used to treat various inflammatory diseases including rheumatism and arthritis. However, whether SIN can attenuate I/R injury has not previously been examined. Using a syngeneic orthotopic liver transplantation model in rats, we investigated the effect of SIN on hepatic I/R injury, in particular its effect on heme oxygenase-1 (HO-1) induction and its hepatocellular protective effect. To our knowledge, our results were the first to show that: (a) SIN pretreatment was able to induce HO-1 expression in donor livers in a dose dependent manner; (b) SIN pretreatment protected the liver graft from cold I/R injury; and (c) the protective effect of SIN was, at least in part, mediated by HO-1, as proved by the fact that inhibiting HO-1 activity with zinc protoporphyrin (ZnPP) reduced the protection. Thus, SIN deserves further exploration as a novel agent to attenuate I/R injury.