Mild hypothermia exerts a protective effect against hepatic ischemia-reperfusion injury in rats by activating the PI3K/Akt signaling pathway

• Main Author: LIU Jian
• Format: Article
• Language: zho
• Published: Editorial Department of Journal of Clinical Hepatology 2019-04-01
• Series: Linchuang Gandanbing Zazhi
• Online Access: http://www.lcgdbzz.org/qk_content.asp?id=9752

ObjectiveTo investigate the protective mechanism of mild hypothermia pretreatment against hepatic ischemia-reperfusion injury in rats. MethodsA total of 40 male Sprague-Dawley rats were randomly divided into sham-operation group (Sham group), hepatic ischemia-reperfusion injury group (HIRI group), mild hypothermia group (MH group), and mild hypothermia+LY294002 group (MH+LY group), with 10 rats in each group. Serum and liver tissue samples were collected at 3, 6, 12, and 24 hours of hepatic ischemia-reperfusion. Western blotting was used to measure the protein expression of phosphoinositide 3-kinase (PI3K), phosphorylated PI3K (p-PI3K), protein kinase-B (Akt), and phosphorylated Akt (p-Akt, Ser308) in liver tissue. TUNEL and Western blotting were used to measure cell apoptosis and expression of apoptosis-related proteins in liver tissue. ELISA was used to measure the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) in liver tissue. An automatic biochemical analyzer was used to measure the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum. A one-way analysis of variance was used for comparison between multiple groups, and the SNK-q test was used for further comparison between two groups. ResultsThe HIRI group had significantly lower relative expression levels of p-PI3K and p-Akt than the Sham group (q=5.217 and 5456, both P＜0.01), and the MH group had significantly higher relative expression levels of p-PI3K and p-Akt in liver tissue than the HIRI group (q=10.434 and 14.116, both P＜0.01). At 3, 6, 12, and 24 hours of hepatic ischemia-reperfusion, the HIRI group, the MH group, and the MH+LY group had significantly higher activities of AST and ALT in serum than the Sham group (all P＜0.001). TUNEL staining showed that the HIRI group had a significantly higher proportion of apoptotic cells in liver tissue than the Sham group (4225%±3.50% vs 3.21%±0.5%, q=10.187, P＜0.01). Compared with the HIRI group, the MH group had a significant reduction in the proportion of apoptotic cells (q=7.784, P＜0.01), while there was no significant difference in the proportion of apoptotic cells between the HIRI group and the MH+LY group (42.25%±3.50% vs 38.19%±2.8%, q=1.059, P＞0.05). Western blotting showed that compared with the Sham group, the HIRI group had a significant reduction in the expression of the anti-apoptotic protein Bcl-2 (q=2.101, P＜0.05) and significant increases in the expression of the pro-apoptotic proteins Bax, Fas, and Fasl (q=11016、4735, and 10201, all P＜0.01), and the regulatory effect of HIRI on apoptotic-related proteins was downregulated by mild hypothermia treatment. According to the results of oxidative indices, the HIRI group, the MH group, and the MH+LY group had significantly lower expression of SOD and GSH-Px and significantly higher expression of MDA in liver tissue than the Sham group (all P＜0.05); compared with the HIRI group, the MH group had significantly higher expression of SOD and GSH-Px (q=2.894 and 2.731, both P＜005) and significantly lower expression of MDA (q=5.888, P＜0.05) in liver tissue. In addition, mild hypothermia+LY294002 treatment significantly reduced the regulatory effect on the expression of SOD, MDA, and GSH-Px in liver tissue in the MH group (q=2.999, 2.944, and 2.620, all P＜0.05). ConclusionMH exerts a protective effect against HIRI in rats, possibly by activating the PI3K/Akt pathway to downregulate hepatocyte apoptosis and enhance antioxidant capacity in vivo.