Protein kinase C-β inhibitor treatment attenuates hepatic ischemia and reperfusion injury in diabetic rats

Hepatic ischemia and reperfusion (I/R) injury plays an active role in hepatic resection and transplantation. While the effects of protein kinase C (PKC)-beta II activation and the role of PKC-beta inhibitors are well understood in myocardial I/R in diabetes, they remain unclear in liver I/R. The aim of this study was to explore the effect of PKC-beta inhibition and the potential mechanism by which PKC-beta inhibitor treatment protects against hepatic I/R injury in diabetic rats. Diabetic rats were established and randomized into two groups. These were an untreated group (n=10), which did not receive any treatment, and a treatment group (n=10), orally treated with ruboxistaurin at a dose of 5 mg/kg/day for 2 weeks. The rats from the two groups were subjected to hepatic I/R. Aspartate transaminase (AST) and lactate dehydrogenase (LDH) levels were measured by enzymatic methods at 1, 3 and 5 h after I/R. Tumor necrosis factor-alpha (TNF-alpha) and intercellular adhesion molecule 1 (ICAM-1) were examined by enzyme-linked immunosorbent assay at the same time-points. Nuclear factor-kappa B (NF-kappa B) p65 expression was analyzed by immunofluorescence and western blotting. Apoptosis of hepatic cells was examined by the western blot analysis of caspase 3 expression and by DNA ladder analysis. Pathological changes were examined using light and electron microscopy. Serum AST and LDH levels in the PKC-beta inhibitor treatment group were diminished compared with those in the untreated group (P<0.01). Serum TNF-alpha and ICAM-1 (P<0.01) levels were also decreased at different time-points in the PKC-beta inhibitor treatment group. The relative expression of NF-kappa B p65 and caspase 3 in the hepatic tissue was weakened in the PKC-beta inhibitor treatment group compared with that in the untreated group (P<0.01). Pathological changes in hepatic tissue were attenuated by the PKC-beta inhibitor. In conclusion, PKC-beta inhibitor treatment protected against liver I/R injury in diabetic rats. The mechanisms probably involved the attenuation of microvascular injury, reduced transport of injury-associated factors and diminishment of the activation of NF-kappa B p65.