rottlerin and Liver-Diseases

Liver ischemic preconditioning (IPC), pre-exposure of the liver to transient ischemia, has been applied as a useful surgical method to prevent liver ischemia and reperfusion (I/R) injury. Although activation of protein kinase C (PKC), especially novel PKCs, has been known as central signaling responsible for the liver protection of IPC, determination of the involved isozyme in strong protection afforded by IPC has not been elucidated.. Rats were subjected to 90 min of partial liver ischemia followed by 3, 6, and 24 h of reperfusion. IPC was induced by 10 min of ischemia after 10 min of reperfusion before sustained ischemia. Rottlerin, a PKC-δ selective inhibitor; PKC-εV1-2 peptide, a selective PKC-ε inhibitor; and 3,7-dimethyl-1-[2-propargyl] xanthine, an adenosine A2 receptor antagonist, were intravenously injected before IPC. N-acetyl-L-cysteine, a strong antioxidant, and Nω-nitro-L-arginine methyl ester, a nonselective nitric oxide synthase inhibitor, were injected intraperitoneally before IPC.. IPC resulted in strong protection against liver I/R injury as evidenced by biochemical and histologic analyses. Inhibition of PKC-δ strongly attenuated the IPC-induced liver protection, whereas PKC-ε inhibition did not exert any effect on IPC-induced protection. Although inhibition of reactive oxygen species, adenosine, and nitric oxide attenuated the beneficial effects of IPC, inhibition of adenosine only attenuated PKC-δ and -ε translocation.. Our findings suggest that IPC protects against I/R-induced hepatic injury through activation of PKC-δ.

Topics: Acetophenones; Animals; Apoptosis; Benzopyrans; Enzyme Activation; Enzyme Inhibitors; Ischemic Preconditioning; Lipid Peroxidation; Liver; Liver Diseases; Male; Oxidative Stress; Protein Kinase C-delta; Protein Kinase C-epsilon; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Activation of protein kinase C (PKC) has been implicated in the protection of ischemic preconditioning (IPC), but the exact role of PKC in early and late hepatic IPC is still unclear. The present study was conducted in order to investigate the differential role of PKC during early and late hepatic IPC. Rats were subjected to 90 min of partial hepatic ischemia followed by 3 (early IPC) and 24 h (late IPC) of reperfusion. IPC was induced by 10 min of ischemia following 10 min of reperfusion prior to sustained ischemia, and chelerythrine, a PKC inhibitor, was injected 10 min before IPC (5 mg/kg, i.v.). Chelerythrine abrogated the protection of early IPC, as indicated by increased serum aminotransferase activities and decreased hepatic glutathione content. While the IPC-treated group showed a few apoptotic cell deaths during both phases, chelerythrine attenuated these changes only at late IPC and limited IPC-induced inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) overexpression. Membrane translocation of PKC-δ and -ε during IPC was blocked by chelerythrine. Our results suggest that PKC might play a differential role in early and late IPC; activation of PKC-δ and -ε prevents necrosis in early IPC through preservation of redox state and prevents apoptosis in late IPC with iNOS and HO-1 induction. Therefore, PKC represents a promising target for hepatocyte tolerance to ischemic injury, and understanding the differential role of PKC in early and late IPC is important for clinical application of IPC.

Topics: Acetophenones; Animals; Apoptosis; Benzophenanthridines; Benzopyrans; Cytochromes c; Heme Oxygenase-1; Ischemic Preconditioning; Liver Diseases; Male; Nitric Oxide Synthase Type II; p38 Mitogen-Activated Protein Kinases; Protein Kinase C; Protein Kinase C-delta; Protein Kinase C-epsilon; Rats; Reperfusion Injury