The Impact Of Hypoxia Preconditioning On Expression Of HSP70in Rem-Nant Liver After The Hepatectomy Of Transplanted Hepatic Cancer Models In SD Rats

1Objective:This study based on the transplanted hepatic cancer models in SD rats. The models should be dealt with hypoxia preconditioning (HP) before operation, then we detected the expression of heat shock protein70(HSP70),Bax and NF-κB p65and the levels of TNF-α IL-1β, the changes of hepatocytes apoptosis, liver function and structure in the remnant liver tissues. We compa-redthe expression of heat shock protein70(HSP70), Bax and NF-κB p65during the processes of ischemia-reperfusion and investigated the effect induced by hypoxia preconditioning on apopto-sis and the regulation on inflammatory mediators in the remnant livers and its underlying me-chanisms.2Methods2.1SD rats of transplanted hepatic cancer models were divided into A group (sham operation group), B group (IR+hepatectomy group), and C group (hypoxia preconditioning+IR+hepatectomy group), with20rats in each group. C group was given10%oxygen atmosphere for90minutes before operation, In15minutes of hepatic vascular occlusion with pringle method, left lateral of liver with tumor resected.2.2At1,8,12,24hours after operation,the remnant liver tissues were sampled to measure the hepatocytes apoptosis rate by the flow cytometry. the expression of heat shock protein70(HSP70),Bax and NF-κB p65were detected by Western blot and the levels of TNF-α IL-1β in the liver tissues were detected by ELISA, respectively. The serum AST and ALT activities were measured by the automatic analyzer. The histological changes of the hepatocytes were also ob-served by the optical microscopy.3Results3.1The relative expression of HSP70in remnant liver tissues of each groupAt each time point after operation, The expression of HSP70due to preoperative hypoxia in C group dramatically increased compared with A and B groups, respectively (all P<0.05).The protein showed less expression in group A and group B without significant fluctuation of the time while the index had no significant differences between two groups (P>0.05). In C group: HSP70/actin was0.332±0.122at1h and then significantly increased at8h and12h (all P<0.05). At24h, it decreased to the same level of1h (P>0.05).3.2The relative expression of Bax in remnant liver tissues of each groupCompared with A group, the relative expression of Bax due to intraoperative ischemia injury were significantly increased at each time point after operation in B group (P<0.05or0.01). Compared with B group, the expression in C group obviously decreased (all P<0.05). In B group, Bax/actin was0.390±0.055at1h and then continued to rise at24hours up to peak(P<0.05).3.3The relative expression of NF-κB p65in remnant liver tissues of each groupThe expression of NF-κB p65in both B and C groups at each time point after operation dramatically increased compared with A group (all P<0.05). The expression of p65in group C was significantly less than in group B. In group B at1hour p65/actin was0.362±0.064,then con-tinued to rise at24hours to peak(P<0.05).3.4The change of the hepatocytes apoptosis rate in remnant liver tissues of each groupThe hepatocytes apoptosis rates in both B group and C group were obviously higher than in A group (P<0.05) and that in group C was lower than in group B (P<0.05). The rates in group B gradually increased at1h,8h,12h and then rise to peak at24h (all P<0.01).3.5The concentrations of TNF-α and IL-1β in remnant liver tissues of each groupThe concentrations of TNF-α and IL-1β in both B and C groups dramatically increased compared with A group (P<0.05). The concentrations of TNF-α and IL-1β significantly decreased in the C group compared with B group (P<0.05).3.6The levels of ALT and AST in the serum in each groupAt the same time point, the levels of ALT and AST in both B and C groups dramatically in-creased compared with A group (all P<0.01). Compared with B group, the levels of ALT and AST significantly decreased in the C group (all P<0.05).3.7The pathological changes of remnant liver tissues in each group underoptical microscopeUnder the optical microscope, after24h of operation the changes in group A were that he-patocytes, hepatic sinusoid endothelial cells had no degeneration and necrosis and the structures of hepatic lobules, central veins and portal areas were normal. In group B hepatocytes swelled obviously, vacuolar degeneration occurred, cellular outlines disappearance and hepatic sinusoid obvious congestion and dilation were observed. There is less congestion in hepatic sinusoid in group C than in group B, only hepatocytes moderate swelling occurred and liver structures were basically normal.4ConclusionHypoxia preconditioning has protective effect against IR injury after the hepatectomy of trans-planted hepatic cancer models in rats, its underlying mechanisms is that HP can induce HSP70expression at great intensity, which might both inhibit cell apoptosis through decreasing the ex-pression of Bax and regulate inflammatory mediators through reducing the activation of NF-κB.