[Effects of ischemic postconditioning on liver regeneration and energy metabolism in rats].

OBJECTIVE: To explore the effects of ischemic postconditioning on the remnant liver regeneration under ischemic reperfusion after subtotal hepatectomy. METHODS: A total of 90 male SD rats weighting 230-280 g were randomly divided into 3 groups of simple subtotal hepatectomy (SH), ischemia reperfusion (IR) and ischemic postconditioning (IPO). The left and middle liver lobes were resected. And the remnant liver was treated as follows: blood flow was non-blocked in SH group, but blocked for 30 min in IR group, then reperfused. The IPO group was established by 30-30 s intermittent interruptions of blood flow thrice during the early phase of reperfusion. At 1, 6, 12, 24, 48 h respectively, the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), hepatocyte growth factor (HGF) and the positive ratio of proliferating cell nuclear antigen (PCNA) were detected. Also the contents of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were measured and the regenerated liver weight was calculated. RESULTS: The activities of ALT and AST in IPO group from 1 - 48 h were (138 ± 20), (340 ± 22), (770 ± 55), (389 ± 60), (113 ± 25) U/L and (247 ± 31), (509 ± 51), (972 ± 77), (955 ± 159), (222 ± 44) U/L respectively at each time point and they were significantly lower than those (294 ± 37), (560 ± 69), (1222 ± 162), (540 ± 40), (161 ± 15) U/L and (439 ± 34), (669 ± 94), (1347 ± 118), (1274 ± 223), (403 ± 68) U/L in IR group (P < 0.05); the regenerated liver weight (18.8 ± 3.2, 34.0 ± 3.5%) and positive cell ratio of PCNA (43.9 ± 2.7, 56.2 ± 4.0%) in IPO group at 24 and 48 h were respectively higher than those in IR group ((11.3 ± 2.9), (26.8 ± 2.5)% and (34.5 ± 2.8), (48.8 ± 1.8)%)(P < 0.05); The HGF levels ((261 ± 54) and (252 ± 103) pg/ml) at 24 and 48 h in IPO group were significantly higher than those ((99 ± 47) and (70 ± 19) pg/ml) in IR group (P < 0.05); the contents of ATP in hepatic tissue at 24 and 48 h in IPO group were (22.20 ± 3.6) and (12.87 ± 2.49) µg/g respectively. And they were significantly higher than those in IR group (P < 0.05), but lower than those in SH group (P < 0.05). CONCLUSION: Ischemic postconditioning improves the remnant liver regeneration under ischemic reperfusion after subtotal hepatectomy through its actions of stimulating HGF production and maintaining hepatic energy metabolism.

[The impact of ischemic postconditioning on the tumor necrosis factor-α/IL-6/signal transducers and activators of transcription-3 signal pathway of liver regeneration].

OBJECTIVE: To investigate the impact of the ischemic postconditioning on the tumor necrosis factor (TNF)-α/IL-6/signal transducers and activators of transcription (STAT)-3 signal pathway of liver regeneration. METHODS: Ninety healthy clean grade male Sprague-Dawley rats weighting 230 to 280 g were selected and assigned into three groups randomly: group I subtotal hepatectomy (SH), group II ischemia reperfusion (IR), group III ischemic postconditioning (IPO). The left and middle liver was resected, and the remnant liver was treated as followed: the blood flow was not blocked in SH group, but blocked 30 minutes in IR group, then reperfused; IPO groups received three cycles of 30 s-30 s intermittent interruptions of blood flow at onset of reperfusion. At 1, 6, 12, 24, 48 h after reperfusion, the serum TNF-α, IL-6 was detected and the mRNA of cyclinD1, Cdk4, STAT-3 was assayed by real-time PCR as well as the protein expression of cyclinD1 and Cdk4 by Western blot. RESULTS: Compared with SH group, the expression of IL-6 declined at each set time point in IR group (t = 5.076 to 8.334, P = 0.000), but the content of TNF-α increased in early stage (1 to 12 h) (t = 2.972 to 7.215, P = 0.000 - 0.014). The expression of STAT-3, cyclinD1 and Cdk4 mRNA and protein of cyclinD1 and Cdk4 at 24 and 48 h after reperfusion were lower in IR group than in SH group (t = 2.857 to 6.684, P = 0.000 to 0.017). However, there was a significant decrease in TNF-α from 1 to 12 h after reperfusion (t = 2.995 to 4.112, P = 0.002 to 0.017), but a significant increase in IL-6 in IPO group than in IR group (t = 2.458 to 3.543, P = 0.005 to 0.034). The expression of STAT-3, cyclinD1, Cdk4 mRNA and protein of cyclinD1 and Cdk4 at 24 and 48 h after reperfusion were all increased in IPO group in comparison with in IR group (t = 2.383 to 6.803, P = 0.000 to 0.038). CONCLUSIONS: The ischemic postconditioning could promote the remnant liver regeneration after subtotal hepatectomy with ischemia reperfusion injury. Its mechanism relates with the activation of the TNF-α/IL-6/STAT-3 signal pathway of and the cyclinD1-Cdk4 complex which enhances the proliferation of hepatocyte.