单磷酸类脂A预处理对大鼠肝缺血再灌注损伤的保护作用及其机制

The protective effect of MPLA preconditioning on hepatic ischemia - reperfusion injury in rats and its mechanism

目的研究单磷酸类脂A（MPLA）是否通过血红素氧合酶-1-一氧化碳-环磷酸鸟苷（HO-1-CO-cGMP）途径促进降钙素基因相关肽（CGRP）释放，发挥其对大鼠肝缺血再灌注损伤的保护作用。方法健康雄性SD大鼠分为对照组、假手术组、肝脏缺血再灌注组、MPLA低、中、高剂量组（肝脏缺血再灌注＋MPLA0．2、0．5、1．0mg／kg），复制肝缺血再灌注模型，随后电子显微镜观察细胞超微结构；多功能生化分析仪测定血清丙氨酸转氨酶（ALT）、天冬氨酸转氨酶（AST）、乳酸脱氢酶（LDH）和肝组织CO水平；免疫组化检测肝组织HO-1表达；放射免疫分析法测定肝组织CGRP、cGMP浓度。结果和缺血再灌注组比较，MPLA低、中、高剂量组细胞损害相对较轻；各项肝功能指标显著降低；HO-1、CO、cGMP、CGRP含量升高（P〈0．05），且HO—1与CO、CO与cGMP、cGMP与CGRP两两者之间存在明显的正相关关系（P〈0．05）。结论MPLA通过HO—1—CO-cGMP途径促进肝脏缺血／再灌注期间CGRP的合成和释放，这可能是MPLA减轻大鼠肝缺血再灌注损伤作用机制之一。

Objective To study the mechanism of monophosphoryl lipid A （MPLA） protecting liver isehemia-reperfusion injury in rats, and explore the hemeoxygenase -1-carbon monoxide-cyclic guanosine monophosphate （HO-1-CO-eGMP） pathway whether involved in MPLA enhance calcitonin gene-related peptides （CGRP） releasing or not. Methods Male SD rats were randomly divided into control group, sham-operated group, hepatic ischemia-reperfusion group, MPLA low, medium and high dose groups （hepatic ischemia-reperfusion ＋ MPLA0. 2, 0. 5,1.0 mg / kg ）. Hepatic ischemia-reperfusion model was constructed, followed by observation of cell ultrastructure through electron microscope. Serum alanine aminotransferase （ALT） , aspartate aminotransferase （AST） , lactate dehydrogenase （LDH） and liver tissue levels of CO were determined. HO-1 expression in liver tissue was detected by immunohistochemie, CGRP, cGMP concentration in liver tissue was detected by RIA assay. Results Compared with hepatic ischemia-reperfusion group, the cell damage in MPLA group were relatively minor, and ALT, AST, LDH were significantly decreased （ P 〈0. 05）, while HO-1, CO, cGMP, CGRP levels were signifi- cantly increased （ P 〈0. 05）. HO-1 and CO, CO and cGMP, cGMP and CGRP were obviously positive correlated （ P 〈0. 05）. Conclusion MPLA enhanced CGRP synthesis and release through HO-1-CO-cGMP pathway in liver ischemia / reperfusion, which may be one of the mechanisms of MPLA reducing hepatic ischemia-repcrfusion injury in rat.