Effect Of Pioglitazone On Liver Ischemia Reperfusion Injury In Rats

Objective To investigate the effect of a specific peroxisome proliferator-activated receptor-γ (PPAR-γ) ligand, pioglitazone on liver ischemia reperfusion injury in male rat model and to clarify its possible mechanism.Methods Male Wistar rats weighting between 220g to 280g were randomly divided into two groups. Control group: rats administered vehicle subjected to the surgical procedures described below and underwent liver ischemia for 1 hour followed by reperfusion(n=25);Experimental group: rats received pioglitazone (10 mg/kg) 1 hour prior to liver ischemia reperfusion(n=25).Rats were fasted for 12 hours before each experiment. Vehicle or pioglitazone were administered intraperitoneally 1 hour prior to occlusion of the hepatic blood vessels. The rats were intraperitoneally anesthetized by chloral hydrate, and incised through median incision of the abdomen. After the liver pedicel between left and middle lobes of liver was exposed, ligaments between liver and septum transversum and abdominal wall were cut. The scatheless vascular clamp was used to block blood stream of portal veins and hepatic arteries of left and middle lobes of liver. After 60 min, the vascular clamp was released and blood stream recovered. So approximately seventy percent of liver was hypoxia, thus severe congestion of the mesentery vein was prevented. Blood samples (5mL) of all animals in each group were taken from inferior vena cava before occlusion and at 1, 3, 6 and 12 h after reperfusion. Then the rats were killed and liver samples were obtained. ALT, AST and LDH levels of sample serum were determined by an automatic biochemistry analyzer. Histological changes of the livers were evaluated by Haematoxylin-Eosin (HE) staining. The expression of nuclear factor-κB(NF-κB) was assessed by immunohistochemistry.Result (1)Without ischemia reperfusion, the levels of serum ALT,AST and LDH did not differ between the two groups. The levels of serum ALT, AST and LDH rapidly increased after reperfusion, reached a peak level at 3 hours after reperfusion and then decreased mildly, but they were still higher at 12 hours after reperfusion than those without ischemia reperfusion. The levels of ALT, AST and LDH in experimental group were remarkably lower than those in ischemic reperfusion injury group (P<0.01). (2) HE staining showed that the hepatic damage of control group is severer than experimental group. The liver in the control group after reperfusion expressed an irregular trabecular derangement, slight hepatocyte necrosis, invasion of inflammatory cells, hemorrhage, and sinusoidal congestion. However, the livers in the experimental group showed almost normal trabecular arrangement and no severe hepatic damage. (3) Expression of NF-kB was both found in the two groups, while expression in experimental group was lower than that in control group.Conclusion Pioglitazone can alleviate ischemia reperfusion induced liver injury and dysfunction. In addition, it has been also ascertained that pioglitazone did not affect normal livers. During liver ischemia reperfusion NF-kB was activated and pioglitazone pretreatment can inhibit its activation. The mechanism underlying the protective effects against liver reperfusion injury involves reduction the activation of NF-kB followed by reduction of the expression of genes implicated in the development of liver reperfusion injury.